JP2001034131A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to prevent occurrence of a picture irregularity and to improve the cleaning suitability of remaining toner at transfer by constituting a cleaning means so as to recover the remaining toner at transfer which is re-electrified by a re-electrifying roller by means of a cleaning member to which a biased voltage is applied. SOLUTION: The remaining toner at transfer which remains on the peripheral surface of a photoreceptor drum 10 which is an image forming body reaches a cleaning device 190 which is the cleaning body of the image forming body. The remaining toner at transfer is re-electrified by the re-electrifying roller 192 which is in contact with the photoreceptor drum 10, is driven and rotated, and to which re-electrifying bias is applied and which is a re-electrifying means, thereafter, is cleaned by the cleaning roller 191 which is the cleaning member which is disposed on the downstream side, is brought into contact with the photoreceptor drum 10, and is driven and rotated. The toner which is subjected to the cleaning by a cleaning roller 191 is recovered to a recovering roller 195, is scraped from the recovering roller 195 by a scraping plate 196 and is recovered to a waste toner container by a screw 194.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image forming apparatus in which a charging means, an image writing means, a developing means and the like are arranged around an image forming body in a copying machine, a printer, a facsimile or the like. The present invention relates to an image forming apparatus having a cleaning unit used for forming, and more particularly to an image forming apparatus having a cleaning unit when a spherical toner or a small particle size toner is used as a developer.

[0002]

2. Description of the Related Art Conventionally, a blade (cleaning blade) or a roller (cleaning roller) has been used as a cleaning member of a cleaning means for cleaning untransferred toner such as an image forming body and an intermediate transfer body (an intermediate transfer belt or an intermediate transfer drum). Commonly used. Further, an AC corona discharger is disposed on the upstream side of the cleaning blade in the moving direction of the image forming body and the intermediate transfer body, and after removing the transfer residual toner by the AC corona of the AC corona discharger, the cleaning blade is used. A method of cleaning the transfer residual toner, a method of applying a bias voltage having a polarity opposite to that of the transfer residual toner to the cleaning roller, and electrically collecting the transfer residual toner are used.

On the other hand, as a conventional method of forming a multi-color image, a single-color toner having the same number of image forming bodies, charging means, developing means and the like as the number of colors required for the image is formed. An apparatus for forming a color image by superimposing an image on an intermediate transfer body (intermediate transfer belt or intermediate transfer drum) or the like, or forming an image by repeating charging, image exposure and development for each color by rotating one image forming body a plurality of times An apparatus for forming a color image superimposed on a body, and a toner image formed by charging, image exposure and development on one image forming body is transferred onto an intermediate transfer body (intermediate transfer belt or intermediate transfer drum) An apparatus that repeats this process for each color to form a color image superimposed on an intermediate transfer member is known.

[0004]

However, in the above-mentioned cleaning method using a cleaning member such as a blade (cleaning blade) or a roller (cleaning roller), an image forming body or an intermediate transfer body (an intermediate transfer belt or an intermediate transfer drum) is used. When the cleaning member is brought into contact with or released from the cleaning member, there is a problem that image unevenness occurs at the time of transfer of the toner image due to the contact between the cleaning member and the shock at the time of releasing the contact. Further, even during the contact of the cleaning member, unevenness in the driving force of the cleaning member due to the fluctuation of the pressing force and the pressing operation causes a problem that image unevenness occurs when transferring the toner image due to the uneven driving. Further, the transfer residual toner has large variations in toner polarity and charge amount, and it is difficult to collect the transfer residual toner even by using the above-described electric cleaning method. In particular, when a spherical toner or a small particle size toner is used as a developer, the pressing force of a cleaning member such as a cleaning blade or a cleaning roller must be increased. There is a problem of image unevenness during transfer of a toner image caused by driving unevenness due to handling, and it is easy for transfer residual toner to slip through the cleaning member,
There is a problem that the cleaning property of the transfer residual toner is very poor and cleaning failure easily occurs.

Further, in each of the above color image forming apparatuses, image unevenness during transfer of the toner image due to a shock at the time of contact and release of the cleaning member, or the pressing force of the cleaning member during the contact of the cleaning member is also reduced. In addition to problems such as the occurrence of image unevenness during transfer of a toner image caused by fluctuations and uneven driving due to pressure handling, a small particle size toner or a spherical toner is preferably used to obtain a good color image. The pressing force of the cleaning member must be increased, and the fluctuation of the pressing force during the contact of the cleaning member and the unevenness in the image transfer at the time of transfer of the toner image caused by the uneven driving due to the pressing operation occur. There is a problem that the cleaning property is very poor and cleaning failure is likely to occur.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and provides a non-uniform image at the time of transfer of a toner image due to a shock at the time of contact and release of the cleaning member with the image forming body and the intermediate transfer member, or the contact of the cleaning member. Prevents fluctuations in the pressing force during contact and unevenness in the transfer of toner images caused by driving unevenness due to pressing, and facilitates cleaning of transfer residual toner that has large variations in toner polarity and charge amount and is difficult to electrically collect. In particular, when a small particle size toner or a spherical toner, which is likely to cause poor cleaning and is difficult to clean, is used,
It is necessary to increase the pressing force of the cleaning member to prevent the fluctuation of the pressing force during the contact of the cleaning member, to prevent the occurrence of image unevenness at the time of transferring the toner image caused by the driving unevenness due to the pressing operation, and to reduce the transfer residual toner. An object of the present invention is to provide an image forming apparatus that improves cleaning performance.

[0007]

An object of the present invention is to provide an image forming apparatus for forming and transferring a toner image on an image forming body.
The cleaning means for cleaning the transfer residual toner includes:
After the transfer residual toner is recharged by a recharge roller,
Transfer residual toner recharged by the recharging roller,
This is achieved by an image forming apparatus (first invention) in which collection is performed by a cleaning member to which a bias voltage is applied.

In the image forming apparatus for forming a toner image on an image forming body and transferring the toner image onto a transfer belt, the cleaning means for cleaning the transfer residual toner may include the step of cleaning the transfer residual toner. After being recharged by the recharging roller, transfer residual toner recharged by the recharging roller is collected by a cleaning member to which a bias voltage is applied, and the image forming body receives a driving force from the transfer belt. This is achieved by an image forming apparatus (second invention).

In the image forming apparatus for forming and transferring a superimposed toner image on an image forming body, the cleaning means for cleaning the transfer residual toner remaining on the image forming body includes the transfer residual toner. An image forming apparatus comprising: a recharging roller for recharging the toner; and a cleaning member for applying a bias voltage and collecting the transfer residual toner recharged by the recharging roller. Invention).

Another object of the present invention is to provide an image forming apparatus for transferring a toner image formed on an image forming body, forming a superimposed toner image on an intermediate transferring body, and transferring the toner image. The cleaning means for cleaning the remaining transfer residual toner includes a recharging roller for recharging the transfer residual toner, and a cleaning member for applying a bias voltage and collecting the transfer residual toner recharged by the recharge roller. The present invention is attained by an image forming apparatus (fourth invention) characterized in that:

[0011]

Embodiments of the present invention will be described below. Note that the description in this column does not limit the technical scope of the claims and the meaning of terms. Further, the following assertive description in the embodiment of the present invention indicates the best mode, and does not limit the meaning or technical scope of the terms of the present invention. In the image forming apparatuses described below, members having the same function, structure, and the like are denoted by the same reference numerals.

Embodiment 1 An image forming process and each mechanism of an embodiment of a first example of an image forming apparatus according to claims 1 to 4 of the present invention,
The cleaning means will be described with reference to FIGS. FIG. 1 is a sectional view of a laser printer showing an embodiment of a first example of an image forming apparatus according to claims 1 to 4 of the present invention, and FIG. 2 is an image forming apparatus of each example of the present invention. FIG. 3 is a diagram illustrating a layer configuration of a recharging roller and a cleaning member provided in the cleaning device of FIG. 2.

According to FIG. 1, a photosensitive drum 10, which is a drum-shaped image forming body, has a cylindrical metal base formed of, for example, an aluminum member provided inside, and an overcoat layer (protective layer) on the surface. An organic photoreceptor layer (OPC) provided with is provided on the outer periphery of the substrate, and is rotated in a direction shown by an arrow in FIG. 1 in a state of being grounded.

The organic photoreceptor layer comprises a charge generating material (CGM)
And a charge transport layer (CTL) containing a charge transport material (CTM) as a main component. The organic photoreceptor layer comprises a charge generation material (CGM) and a charge transport material (C
(TM) in one layer, and the photosensitive layer having the single-layer structure or the two-layer structure usually contains a binder resin.

In the photosensitive drum having the two-layered organic photosensitive layer, the CGM contained in the CGL may be an azo pigment, an azulenium pigment, a phthalocyanine pigment which is sensitive to light from a light source such as an LED or an LD. , A perylene pigment is used, and red to infrared light (600 nm
Copper phthalocyanine pigments, titanyl phthalocyanine pigments, and the like are preferably used as the CGM of the OPC photoreceptor that is sensitive to 850 nm.

As the binder resin used for CGL, a polyvinyl butyral resin or a polycarbonate resin is used, which is excellent in sensitivity, potential change upon repeated use, and the like. These binder resins can be used alone or as a mixture of two or more.

As a solvent or a dispersion medium used for the formation of CGL, a ketone-based or halogen-based solvent is preferably used, and the sensitivity and the potential change upon repeated use are further improved. In addition, these solvents can be used alone or as a mixed solvent of two or more kinds.

The weight ratio of CGM to the binder resin in CGL is 100: 1 to 1000, the thickness of the CGL is 0.01 to 10 μm, and the coating method for forming the CGL is a blade. There are various coating methods such as coating, wire bar coating, spray coating, dip coating and slide hopper coating.

Next, as the CTM contained in the CTL, a hydrazone compound, a styryl compound, a benzidine compound, a stilbene compound or the like is used.

As the binder resin used in the CTL, a wide range of insulating resins can be appropriately selected and used. Preferred binder resins include silicon-alkyd resin, phenol-formaldehyde resin, and poly-N- Insulating resins such as vinyl carbazole and polysilane can be mentioned, and these binder resins can be used alone or in combination of two or more.

The mixing ratio of the binder resin and CTM is 1:
It is set to 10 to 500, and more preferably 1:20 to 150. The thickness of the CTL is set to 1 to 100 μm.
~ 50 μm is preferred.

As a coating method, a method similar to CGL can be used.

If necessary, an intermediate layer is provided between the organic photoreceptor layer and the conductive layer. Examples of the intermediate layer include polyvinyl chloride vinyl acetate copolymer, vinyl acetate vinyl acetate maleate copolymer, ethyl cellulose, carboxymethyl cellulose. And a resin layer having a thickness of 0.01 to 2 μm, such as a copolymer type or modified type alcohol-soluble polyamide resin.

As the overcoat layer (protective layer), a layer obtained by dissolving a resin such as silicon or fluorine in an organic solvent and further adding an antioxidant, a matting agent and the like as necessary is used. The application method is not particularly limited, but spray application and slide hopper application are preferred. The film thickness is 0.
It is formed to a thickness of about 5 to 10 μm. Thereby, the hardness, strength, and the like of the surface of the photoreceptor layer are increased, and generation of scratches is prevented, and high-temperature durability is obtained. Further, since the surface of the photoconductor layer can be more strongly cleaned, it is easy to remove the deposits on the surface. Furthermore, toner transferability,
In particular, transferability with a small particle size toner or a spherical toner is also improved.

The organic photoreceptor layer and overcoat layer are used in other image forming apparatuses described later.

Reference numeral 11 denotes a scorotron charger serving as a charging means, which performs a charging action on the above-mentioned organic photosensitive layer of the photosensitive drum 10 by a grid maintained at a predetermined potential and corona discharge by a discharge wire, and Body drum 1
A uniform potential is given to 0.

The peripheral surface of the photosensitive drum 10 is uniformly distributed by a scorotron charger 11 by corona discharge having the same polarity (in the present embodiment, negative polarity) as the toner used (toner at the time of development). After being charged, image exposure based on an image signal is performed by an exposure optical system 12 serving as an image writing unit.

An exposure optical system 12 serving as an image writing means converts a laser beam emitted from a laser light source (not shown) into a rotating polygon mirror 1.
2b, the exposure is started by an electric signal corresponding to an image signal on the photosensitive drum 10 via the fθ lens 12c, the reflection mirror 12d, and the like, and the rotation scanning of the photosensitive drum 10 causes the surface of the photosensitive drum 10 to rotate. An electrostatic latent image corresponding to the original image is formed on the photoconductor layer.

A developing unit 13 is provided as a developing unit that contains a two-component developer composed of toner particles and carrier particles or a one-component developer composed only of toner particles. Development of the formed latent image is performed by a developing sleeve 131 that carries a one-component developer or a two-component developer. The development is performed in a non-contact manner by applying a developing bias in which a DC voltage of the same polarity as the toner (in this embodiment, a negative polarity) is superimposed on an AC voltage between the developing sleeve 131 serving as a developer carrier and the photosensitive drum 10. Alternatively, reversal development is performed in a contact state.

A developing device 13 as a developing means is conventionally provided with a two-component developer or an average particle size composed of a non-magnetic toner having an average particle size of tens μm and a magnetic carrier having an average particle size of tens to hundreds μm. Is a one-component developer composed of a non-magnetic toner having a size of about 10 μm. However, when the developer is used for non-contact development, the transfer of the toner can be effectively controlled by the oscillating electric field. Therefore, the toner having an average particle diameter of 1 to 20 μm, preferably 4 to 10 μm and the average particle diameter of 10 to 10 μm are used. 60μ
m, more preferably a two-component developer comprising a carrier of 20 to 50 μm or a one-component developer comprising a toner having an average particle diameter of 1 to 20 μm, preferably 4 to 10 μm. This will be described. In addition,
The two-component developer or one-component developer described below is also used in other image forming apparatuses described later.

(Carrier) In general, if the average particle size of the magnetic carrier particles is large, the state of the ears of the magnetic brush formed on the developer conveying member becomes coarse, so that the electrostatic latent image is formed while being vibrated by an electric field. Even when development is performed, unevenness tends to appear in the toner image, and the toner concentration in the ears becomes low, so that there is a problem that high-density development is not performed. In order to solve this problem, the average particle diameter dc of the magnetic carrier particles may be reduced.
m, preferably 20 to 50 μm, the above problem did not occur.

When dc is 10 μm or less, it is difficult to sufficiently magnetize the carrier, and the carrier adheres to the surface of the image forming body together with the toner particles and easily scatters.

When dc is 60 μm or more, the specific surface area of the carrier becomes small, so that the toner cannot be sufficiently charged. Further, since the covering ratio is high, toner scattering is also likely to occur.

The volume average particle diameter dc can be measured by a laser diffraction particle size distribution analyzer “HEROS” (S
YMPATEC). First, 10 mg of magnetic particles were added together with a surfactant to 50 m of water using a wet disperser.
g and then an ultrasonic homogenizer (output 15
0W), and the value was measured after performing a pretreatment of dispersing for 1 to 10 minutes while taking care not to cause re-aggregation due to heat generation.

The carrier has a magnetization intensity (maximum magnetization) of 5
-60 emu / g, preferably 10-40 emu / g. Although this strength depends on the magnetic flux density on the developer carrying member, under the general condition of the magnetic flux density of the developer carrying member, if it is less than 5 emu / g, the magnetic binding force does not work and the carrier is scattered. Becomes On the other hand, if it exceeds 60 emu / g, the carrier ears become too high, making it difficult to maintain a non-contact state with the image forming body.

To measure the magnetization intensity of the carrier, the carrier particles are filled while tapping into a sample cell of 0.25 cm × 3 cm ² , the sample is attached to a pickup coil, and the sample is set on a magnetizer. Recording device "TY
This is performed by causing the XY recorder to draw a hysteresis curve using "PE3257" (manufactured by Yokogawa Hokushin Electric Co., Ltd.).

Such a magnetic carrier is made of a metal such as iron, chromium, nickel, or cobalt, or a compound or alloy thereof, such as triiron tetroxide, γ-oxide, as in a conventional magnetic carrier. Ferric, chromium dioxide, manganese oxide, ferrite, manganese-copper alloy, ferromagnetic spherical particles, or the surface of these spherical magnetic particles styrene resin, vinyl resin, ethylene resin And a rosin-modified resin, an acrylic resin, a polyamide resin, an epoxy resin, a polyester resin, a silicone resin, a fluororesin, or the like, or a spherical coating with a copolymer.

A so-called resin dispersion type carrier in which magnetic fine particles are dispersed and contained in these resins can also be used.

(Toner) Generally, when the average particle size of the toner particles is reduced, the charge amount is qualitatively reduced in proportion to the square of the particle size, and the adhesive force such as van der Waals force is relatively increased. Scattered easily, and fogging is likely to occur. Then, when the average particle size is 10 μm or less, this problem becomes remarkable. The developing means of the present embodiment solves this problem by performing the development under an oscillating electric field.

When the volume average particle diameter D ₅₀ (μm) of the toner increases, as already mentioned, the roughness of the image becomes conspicuous. If D ₅₀ is used the toner following micronized 10 [mu] m (small particle size toner), the resolution is remarkably improved, so give a clear high-quality images shading difference also faithfully reproduced. D ₅₀ is 20μm or more, results in degradation of image quality, at the 1μm or less, poor charging, scattering and the like easily occurs.

For the above reasons, the volume average particle diameter D _{50 of the} toner is
Is 1 to 20 μm, preferably 4 μm ≦ D ₅₀ ≦ 10 μm.

When D ₅₀ is larger than 10 μm, the particle size is large and the resolution is insufficient, and when D ₅₀ is smaller than 4 μm, the cohesive force is large and triboelectric charging is likely to occur.

Here, the volume average particle diameter D used for the average particle diameter is
₅₀ is a coulter counter TA-II type (aperture 1
00 μm, manufactured by Coulter Corporation).

Further, since the toner particles follow the electric field of the developing bias, the absolute value of the charge amount of the toner particles is preferably set to 10 to 30 μC / g in the case of the two-component magnetic developer to ensure the developing property. It is desirable from the viewpoint of preventing fog and scattering. In particular, when the particle size is small, a high charge amount is required.

Examples of the binder resin for such a toner include styrene resins, vinyl resins, ethyl resins, rosin modified resins, acrylic resins, polyamide resins, epoxy resins, polyester resins, and styrene-acryl resins. And the like, or a mixed resin or the like. Coloring components such as color pigments, a charge controlling agent, a releasing agent such as wax if necessary, a fluidizing agent for improving the fluid sliding of the particles, and a cleaning agent useful for cleaning the surface of the image carrier. In addition, the toner can be produced by a method known in the art, such as a conventionally known pulverization granulation method, suspension polymerization method, emulsion polymerization method, or the like. As a fluidizing agent, colloidal silica, silicon varnish, metal soap, a nonionic surfactant, or the like can be used. As a cleaning agent, a surfactant such as a fatty acid metal salt, organic group-substituted silicon, or fluorine can be used. Can be.

As the toner shape, a spherical toner produced by a polymerization method or the like is preferable because it has higher fluidity than amorphous toner, has low adhesion to an image forming body, and has a high transfer rate.

(Developer) When used as a one-component developer in the developing device 13 of the present embodiment, the toner described above is used. When used as a two-component developer in the developing device 13, the above-described toner is used. As described above, a developer in which spherical carrier particles and toner are mixed at the same ratio as in a conventional two-component developer is preferably used. As a carrier, a general coating carrier (density of 5 to 8 g / c) is used.
m ³ ), the toner concentration in the developer is 2-3.
0% by weight, preferably 5 to 20% by weight.

If the amount is less than 2% by weight, the number of toners required for development cannot be secured, and the coverage decreases, resulting in excessive charging and a decrease in developability.

If the content is more than 30% by weight, the coverage becomes large, and poor charging and toner scattering tend to occur.

However, when a relatively light (2-4 g / cm ³ ) resin-dispersed carrier having the above-mentioned density is used as the carrier in the developer, the toner concentration in the developer is as follows:
Slightly higher than when using a general resin-coated carrier,
The content is preferably 5 to 40% by weight, more preferably 10 to 30% by weight.

The developer is mixed with a fluidizing agent for improving the fluid sliding of the particles and a cleaning agent useful for cleaning the surface of the image forming body, if necessary. As the fluidizing agent, colloidal silica, silicon varnish, metal soap or nonionic surfactant can be used. As the cleaning agent, a surfactant such as fatty acid metal salt, organic group-substituted silicon or fluorine can be used. Can be.

On the other hand, the recording paper P, which is a transfer material, is fed from a paper feed cassette 15 which is a transfer material storage means to a delivery roller
a, is fed by the feed roller 15b, and is conveyed to the timing roller 15c.

The recording paper P is fed to the transfer area of the transfer roller 16a by driving the timing roller 15c in synchronization with the conveyance of the toner image on the photosensitive drum 10.

The transfer roller 16a is rotated in the same direction as the photosensitive drum 10 in the transfer area in synchronization with the peripheral speed of the photosensitive drum 10, and the recording paper P fed to the transfer area is transferred to the transfer roller 16a. The photosensitive drum 10 is in close contact with the toner image, and a bias voltage of 1-2 kV opposite to that of the toner (positive polarity in the present embodiment) is applied to the transfer roller 16a. The toner image is transferred onto the recording paper P.

The recording paper P to which the toner image has been transferred is neutralized by a neutralizing electrode 16b, which is a separating means composed of a sawtooth electrode plate, and a fixing roller 17a having a heater inside at least one of the rollers and a pressure roller 17b are separated. Is transported to a fixing device 17 which is a fixing unit having
When heat and pressure are applied between the recording paper P and the pressure roller 17b, the toner adhered on the recording paper P is fixed, and the recording paper P is discharged to the outside of the apparatus by the discharge roller 18.

The transfer residual toner remaining on the peripheral surface of the photosensitive drum 10 as an image forming body reaches a cleaning device 190 as cleaning means for the image forming body, and as will be described later in detail, the photosensitive drum 10 In the cleaning position, a recharging roller 19 which is disposed on the upstream side in the rotation direction of the photosensitive drum 10, is a recharging unit which is in contact with the photosensitive drum 10, is driven to rotate, and is applied with a recharging bias.
After being recharged by the cleaning roller 2, the cleaning roller 191 is disposed on the downstream side and is a cleaning member that is in contact with the photosensitive drum 10 and is driven to rotate. The toner cleaned by the cleaning roller 191 is removed from the cleaning roller 191 by the collection roller 1.
95, and is collected by a scraping plate 196 to a collecting roller 195.
And is collected by a screw 194 into a waste toner container (not shown). Further, the cleaning device 190 is provided with a thin plate member having elasticity so that toner scattered after being cleaned by the cleaning roller 191 does not adhere to the recharge roller 192. Roller 1
It is provided between the cleaning roller 92 and the cleaning roller 191.
The cleaning unit is used in other image forming apparatuses described later, and members having the same functions and structures are given the same numbers.

According to FIG. 2 or FIG. 3, the cleaning device 190, which is a means for cleaning the image forming body, is located at the cleaning position on the upstream side in the rotation direction of the photosensitive drum 10 at the cleaning position. A recharging roller 192, which is a recharging unit that is arranged to contact and rotate following the photoconductor drum 10, and a photoconductor drum 10 that is disposed downstream of the photoconductor drum 10 in the rotation direction.
The cleaning roller 191 is a cleaning member that is driven and rotated by forming a nip of mm, a collection roller 195 made of a metal roller such as aluminum or stainless steel that collects toner from the cleaning roller 191, and the toner is scraped off from the collection roller 195. A scraping plate 196 and a thin plate member having elasticity such as a Mylar film or the like are used so that toner scattered after being cleaned by the cleaning roller 191 does not adhere to the recharging roller 192.
It is constituted by a partition plate 193 which is a partition member provided between the recharging roller 192 and the cleaning roller 191, and cleans the transfer residual toner remaining on the peripheral surface of the photosensitive drum 10. The toner scraped into the cleaning device 190 is collected by a screw 194 into a waste toner container (not shown).

As shown in FIG. 3, the cleaning device 19
Recharging roller 192 which is a roller-shaped recharging means
Is provided with a conductive core 192a to which a high AC voltage, preferably a DC voltage is superimposed, is applied via a sliding electrode (not shown), and which is functionally provided on the core 192a. Cell diameter 150 in which conductive carbon powder is dispersed
It is made of a sponge-like EDMD, urethane rubber, or the like having a thickness of about μm, and ensures the contact of the recharging roller 192 with the photosensitive drum 10. The volume resistivity is about 10 ⁵ to 10 ⁶ Ω · cm, and the hardness is 25 to 25. Volume resistivity having a conductive elastic layer 192b of 35 degrees (Asker C) and a function of suppressing current by an in-layer voltage drop against an excess current and preventing charging failure and photoconductor dielectric breakdown due to a power supply voltage drop. Is about 10 ⁸
To prevent contamination of the photoreceptor due to the medium resistance layer 192c having semiconductive properties of about Ω · cm and additives contained in the internal rubber material, and accumulation of dirt on the surface of the recharging roller 192 due to adhesion of the developer and paper powder. For example, a three-layer elastic roller member including a protective layer 192d made of a resin such as nylon is used. The cleaning roller 191 of the cleaning device 190 has the same structure as the recharging roller 192, and the elasticity of the three-layer structure of the conductive elastic layer 191b, the medium resistance layer 191c, and the protective layer 191d is provided on the cored bar 191a. Roller member.

The outer diameter of the recharging roller 192 and the cleaning roller 191 is 5 to 20 mm, and the hardness measured from the outside is 35 to 55 degrees (Asker C). The hardness measured from the surface of the conductive elastic layers 192b and 191b is 2
0 to 40 degrees (Asker C) and the conductive elastic layer 192
The electrical resistance measured between the layer surfaces of the layers b and 191b and the metal cores 192a and 191a is 10 ⁴ to 10 ⁶ Ω. The surface of the middle resistance layers 192c, 191c and the cores 192a, 192c
1a is 10 ⁶ to 10 ⁹ Ω, and the thickness of the outer protective layers 192d and 191d is 50 to 1Ω.
00 μm.

In the image area where the toner image is formed, the recharging roller 192 has the same polarity as the toner as the recharging bias (minus polarity in this embodiment).
Is applied, and the untransferred toner remaining in the untransferred toner area on the peripheral surface of the photosensitive drum 10 after the transfer is recharged. A sin-wave or rectangular wave having a frequency of 1 to 2 kHz and a voltage V _{PP of} 1.0 to 2.5 kV is used as the AC voltage at 100 to -400 V. The average charge of the transfer residual toner is obtained by applying a recharge bias. The amount (Q / M) is the average charge amount of the toner (toner to be used) at the time of development (the charge amount of the negative polarity in the present embodiment).
For μC / g, -5 to -1 which is lower than this in absolute value
The toner is uniformly charged to 5 μC / g (it is made uniform by increasing the charge amount), and the uneven (non-uniform) potential of the surface potential of the photosensitive drum 10 is made flat by recharging, and the transfer residual toner is exposed. The adhesive force with the body drum 10 is reduced uniformly, and is conveyed to the cleaning area of the cleaning roller 191 on the downstream side without being scattered from above the photosensitive drum 10.

At the position of the cleaning roller 191, the charging amount is increased by the recharging roller 192 by a cleaning bias having a polarity opposite to that of the toner (positive polarity in the present embodiment) and a DC voltage of +300 to +1500 V is applied. The transfer residual toner on the photosensitive drum 10 that has been made uniform is cleaned on the cleaning roller 191.

The toner on the cleaning roller 191 is
The recovery roller 195, which is driven and rotated in contact with the cleaning roller 191, has a polarity opposite to that of the toner (positive polarity in the present embodiment) and a DC bias voltage of +300 to + 1500V is applied. It is collected on the collection roller 195.

The toner collected on the collecting roller 195 is scraped by the scraping plate 196 into the cleaning device 190 and collected by the screw 194 into a waste toner container (not shown).

In the above embodiment, after the toner image formed on the image forming member is once transferred to a belt-like or drum-like intermediate transfer member, the toner image on the intermediate transfer member is transferred to the transfer material. The image forming apparatus may be configured such that the above-described cleaning unit is applied to a belt-like or drum-like intermediate transfer member of the image forming apparatus.

As described above, the unevenness in the transfer of the toner image due to the shock when the cleaning member comes into contact with the image forming member and the release of the contact, or the fluctuation of the pressing force during the contact of the cleaning member and the driving by the pressing operation In addition to preventing image unevenness during transfer of a toner image due to unevenness, it also facilitates cleaning of transfer residual toner that has a large variation in toner polarity and charge amount and is difficult to electrically collect.In particular, cleaning failure easily occurs. When difficult-to-use small particle size toner or spherical toner is used, the pressing force of the cleaning member must be increased to change the pressing force during the contact of the cleaning member and the toner image caused by uneven driving due to the pressing operation. It is possible to prevent the occurrence of image unevenness at the time of transfer and to improve the cleaning property of the transfer residual toner.

Embodiment 2 An image forming process and each mechanism of an embodiment of a second example of the image forming apparatus according to claims 5 to 9 of the present invention,
The cleaning means will be described with reference to FIG. 4 and FIGS. 2 and 3 described above. FIG. 4 shows claim 5 of the present invention.
FIG. 9 is a cross-sectional configuration diagram of a main part of a color image forming apparatus showing an embodiment of a second example of the image forming apparatus according to any one of Examples 1 to 9;

In FIG. 4, reference numeral 10 denotes a photosensitive drum as an image forming body for each color, 11 a scorotron charger as charging means for each color, 12 an exposure optical system as image writing means for each color, and 13 Denotes a developing device which is a developing means for each color;
a is a transfer belt, 14c is a primary transfer device as a transfer unit for each color, 14m is a static eliminator as a static eliminator of the transfer belt,
14b is a pressing elastic plate which is a pressing means of the transfer belt, 17
Reference numeral 190 denotes a fixing device as a fixing unit; 190, a cleaning device as a cleaning unit for an image forming body for each color;
Reference numeral denotes a cleaning device that is a cleaning unit for the transfer belt.

In this embodiment, a photosensitive drum 10 as an image forming body for each color, a scorotron charger 11 as a charging unit for each color, an exposure optical system 12 as an image writing unit for each color, and a Developing device 13 as a developing means and cleaning device 1 as an image forming body cleaning means
Reference numeral 90 denotes an image having the same structure as that described in the first embodiment, and a set of these is used as an image for each color of yellow (Y), magenta (M), cyan (C), and black (K). Four sets of forming units 100 are provided, and Y, M are formed below the transfer belt 14a in the rotation direction of the transfer belt 14a rotated clockwise as indicated by the arrow in FIG. , C, and K in this order.

The photosensitive drum 10 as an image forming body for each color
Is formed by forming an organic photoreceptor layer (OPC) having an overcoat layer (protective layer) on the outer periphery of a cylindrical metal substrate formed of, for example, an aluminum material on the outer periphery of the metal substrate. As will be described later, the transfer belt 14a in the contact state is rotated by receiving the driving force from the transfer belt 14a, and is rotated in a counterclockwise direction indicated by an arrow in FIG. The drum 10 is rotated.

The organic photoreceptor layer is composed of a charge generation material (CGM)
And a charge transport layer (CTL) containing a charge transport material (CTM) as a main component. The organic photoreceptor layer comprises a charge generation material (CGM) and a charge transport material (C
(TM) in one layer, and the photosensitive layer having the single-layer structure or the two-layer structure usually contains a binder resin.

In the photosensitive drum having the two-layered organic photosensitive layer, the CGM contained in the CGL may be an azo pigment, an azulenium pigment, a phthalocyanine pigment which is sensitive to light from a light source such as an LED or an LD. , A perylene pigment is used, and red to infrared light (600 nm
Copper phthalocyanine pigments, titanyl phthalocyanine pigments, and the like are preferably used as the CGM of the OPC photoreceptor that is sensitive to 850 nm.

As the binder resin used for CGL, a polyvinyl butyral resin or a polycarbonate resin is used, which is excellent in sensitivity, potential change upon repeated use, and the like. These binder resins can be used alone or as a mixture of two or more.

As a solvent or a dispersion medium used for forming CGL, a ketone-based or halogen-based solvent is preferably used, and the sensitivity and the potential change upon repeated use are further improved. In addition, these solvents can be used alone or as a mixed solvent of two or more kinds.

The weight ratio of CGM to binder resin in CGL is 100: 1 to 1000, the film thickness of CGL is 0.01 to 10 μm, and the coating method for forming the CGL is a blade. There are various coating methods such as coating, wire bar coating, spray coating, dip coating and slide hopper coating.

Next, as the CTM contained in the CTL, hydrazone compounds, styryl compounds, benzidine compounds, stilbene compounds and the like are used.

The binder resin used in the CTL can be selected from a wide range of insulating resins as appropriate, and preferred binder resins include silicone-alkyd resins, phenol-formaldehyde resins, and poly-N- Insulating resins such as vinyl carbazole and polysilane can be mentioned, and these binder resins can be used alone or in combination of two or more.

The mixing ratio of the binder resin and CTM is 1:
It is set to 10 to 500, and more preferably 1:20 to 150. The thickness of the CTL is set to 1 to 100 μm.
~ 50 μm is preferred.

As a coating method, a method similar to CGL can be used.

If necessary, an intermediate layer is provided between the organic photoreceptor layer and the conductive layer. Examples of the intermediate layer include polyvinyl chloride vinyl acetate copolymer, vinyl acetate vinyl acetate maleic acid copolymer, ethyl cellulose and carboxymethyl cellulose. And a resin layer having a thickness of 0.01 to 2 μm, such as a copolymer type or modified type alcohol-soluble polyamide resin.

As the overcoat layer (protective layer), a layer obtained by dissolving a resin such as silicon or fluorine in an organic solvent and further adding an antioxidant, a matting agent and the like as necessary is used. The application method is not particularly limited, but spray application and slide hopper application are preferred. The film thickness is 0.
It is formed to a thickness of about 5 to 10 μm. Thereby, the hardness, strength, and the like of the surface of the photoreceptor layer are increased, and generation of scratches is prevented, and high-temperature durability is obtained. Further, since the surface of the photoconductor layer can be more strongly cleaned, it is easy to remove the deposits on the surface. Furthermore, toner transferability,
In particular, transferability with a small particle size toner or a spherical toner is also improved.

The scorotron charger 11, which is a charging means for each color, has the same polarity as the toner (toner at the time of development) used by the control grid and the corona discharge electrode maintained at a predetermined potential. The charging action (minus charging in the present embodiment) is performed by the corona discharge of (negative polarity), and a uniform potential is applied to the photosensitive drum 10. As the corona discharge electrode of the scorotron charger 11, a saw-tooth electrode or a needle electrode can also be used.

Exposure optical system 1 as image writing means for each color
2 indicates that the exposure position on the photosensitive drum 10 is the photosensitive drum 1 with respect to the scorotron charger 11 for each color described above.
It is arranged around the photosensitive drum 10 so as to be located on the downstream side in the rotation direction of 0. The exposure optical system 12 rotationally scans a laser beam emitted from a laser light source (not shown) with a rotary polygon mirror (not shown), and comprises an fθ lens (not shown), a reflection mirror (not shown), and the like, and is separate. In accordance with the image data of each color read by the image reading device and stored in the memory, the photosensitive layer of the photosensitive drum 10 is image-exposed to form an electrostatic latent image on the photosensitive drum 10 for each color.

The developing device 13 which is a developing means for each color keeps a predetermined gap with respect to the peripheral surface of the photosensitive drum 10 and rotates in a forward direction with respect to the rotating direction of the photosensitive drum 10, for example, 0.5 to 1 mm in thickness. A cylindrical developing sleeve 131 made of non-magnetic stainless steel or aluminum having an outer diameter of 15 to 25 mm, and has yellow (Y), magenta (M), and cyan (C) therein according to the developing color of each color. And a black (K) one-component or two-component developer. The developing device 13 is provided with an abutting roller (not shown),
0 and a predetermined gap, for example, 100 to 500 μm, and is kept in a non-contact state. By applying a developing bias in which a DC voltage and an AC voltage are superimposed on the developing sleeve 131, non-contact reversal development is performed. Then, a toner image is formed on the photosensitive drum 10.

A developing device 13 serving as a developing means is provided with a two-component developer or an average particle size which is conventionally composed of a non-magnetic toner having an average particle size of tens of μm and a magnetic carrier having an average particle size of tens to hundreds of μm. Is a one-component developer composed of a non-magnetic toner having a size of about 10 μm. However, when the developer is used for non-contact development, the transfer of the toner can be effectively controlled by the oscillating electric field. Therefore, the toner having an average particle diameter of 1 to 20 μm, preferably 4 to 10 μm and the average particle diameter of 10 to 10 μm are used. 60μ
m, more preferably a two-component developer comprising a carrier of 20 to 50 μm or a one-component developer comprising a toner having an average particle diameter of 1 to 20 μm, preferably 4 to 10 μm. This will be described.

(Carrier) In general, if the average particle size of the magnetic carrier particles is large, the condition of the ears of the magnetic brush formed on the developer conveying member becomes coarse, so that an electrostatic latent image is formed while applying vibration by an electric field. Even when development is performed, unevenness tends to appear in the toner image, and the toner concentration in the ears becomes low, so that there is a problem that high-density development is not performed. In order to solve this problem, the average particle diameter dc of the magnetic carrier particles may be reduced.
m, preferably 20 to 50 μm, the above problem did not occur.

When the dc is less than 10 μm, it is difficult to sufficiently magnetize the carrier, and the carrier adheres to the surface of the image forming body together with the toner particles or easily scatters.

When dc is 60 μm or more, the specific surface area of the carrier becomes small, so that the toner cannot be sufficiently charged. Further, since the covering ratio is high, toner scattering is also likely to occur.

The volume average particle diameter dc can be measured by a laser diffraction particle size distribution analyzer “HEROS” (S
YMPATEC). First, 10 mg of magnetic particles were added together with a surfactant to 50 m of water using a wet disperser.
g and then an ultrasonic homogenizer (output 15
0W), and the value was measured after performing a pretreatment of dispersing for 1 to 10 minutes while taking care not to cause re-aggregation due to heat generation.

The intensity of the magnetization of the carrier (maximum magnetization) is 5
-60 emu / g, preferably 10-40 emu / g. Although this strength depends on the magnetic flux density on the developer carrying member, under the general condition of the magnetic flux density of the developer carrying member, if it is less than 5 emu / g, the magnetic binding force does not work and the carrier is scattered. Becomes On the other hand, if it exceeds 60 emu / g, the carrier ears become too high, making it difficult to maintain a non-contact state with the image forming body.

Measurement of the magnetization intensity of the carrier was carried out by filling the carrier particles while tapping them into a sample cell of 0.25 cm × 3 cm ² , attaching the sample to a pickup coil, setting the sample on a magnetizer, and setting the DC magnetization characteristics automatically. Recording device "TY
This is performed by causing the XY recorder to draw a hysteresis curve using "PE3257" (manufactured by Yokogawa Hokushin Electric Co., Ltd.).

Such a magnetic carrier is made of a metal such as iron, chromium, nickel, cobalt or the like, or a compound or alloy thereof, such as triiron tetroxide, γ-oxide, as in a conventional magnetic carrier. Ferric, chromium dioxide, manganese oxide, ferrite, manganese-copper alloy, ferromagnetic spherical particles, or the surface of these spherical magnetic particles styrene resin, vinyl resin, ethylene resin And a rosin-modified resin, an acrylic resin, a polyamide resin, an epoxy resin, a polyester resin, a silicone resin, a fluororesin, or the like, or a spherical coating with a copolymer.

Further, a so-called resin-dispersed carrier in which magnetic fine particles are dispersed and contained in these resins can also be used.

(Toner) Generally, when the average particle size of the toner particles is reduced, the charge amount is qualitatively reduced in proportion to the square of the particle size, and the adhesive force such as van der Waals force is relatively increased. Scattered easily, and fogging is likely to occur. Then, when the average particle size is 10 μm or less, this problem becomes remarkable. The developing means of the present embodiment solves this problem by performing the development under an oscillating electric field.

When the volume average particle diameter D ₅₀ (μm) of the toner increases, as already mentioned, the roughness of the image becomes conspicuous. If D ₅₀ is used the toner following micronized 10 [mu] m (small particle size toner), the resolution is remarkably improved, so give a clear high-quality images shading difference also faithfully reproduced. D ₅₀ is 20μm or more, results in degradation of image quality, at the 1μm or less, poor charging, scattering and the like easily occurs.

For the above reasons, the volume average particle diameter D _{50 of the} toner is
Is 1 to 20 μm, preferably 4 μm ≦ D ₅₀ ≦ 10 μm.

When D ₅₀ is larger than 10 μm, the particle size is large and the resolution is insufficient, and when D ₅₀ is smaller than 4 μm, the cohesive force is large and triboelectric charging tends to be poor.

Here, the volume average particle size D used for the average particle size is
₅₀ is a coulter counter TA-II type (aperture 1
00 μm, manufactured by Coulter Corporation).

Further, since the toner particles follow the electric field of the developing bias, the absolute value of the charge amount of the toner particles is preferably set to 10 to 30 μC / g in the case of the two-component magnetic developer, in order to secure the developability. It is desirable from the viewpoint of preventing fog and scattering. In particular, when the particle size is small, a high charge amount is required.

Examples of the binder resin for such a toner include styrene resins, vinyl resins, ethyl resins, rosin-modified resins, acrylic resins, polyamide resins, epoxy resins, polyester resins, and styrene-acryl resins. And the like, or a mixed resin or the like. Coloring components such as color pigments, a charge controlling agent, a releasing agent such as wax if necessary, a fluidizing agent for improving the fluid sliding of the particles, and a cleaning agent useful for cleaning the surface of the image carrier. In addition, the toner can be produced by a method known in the art, such as a conventionally known pulverization granulation method, suspension polymerization method, emulsion polymerization method, or the like. As a fluidizing agent, colloidal silica, silicon varnish, metal soap, a nonionic surfactant, or the like can be used. As a cleaning agent, a surfactant such as a fatty acid metal salt, organic group-substituted silicon, or fluorine can be used. Can be.

As the toner shape, a spherical toner produced by a polymerization method or the like is preferable because it has higher fluidity than amorphous toner, has low adhesion to an image forming body, and has a high transfer rate.

(Developer) When the toner is used as a one-component developer in the developing device 13 of the present embodiment, the toner described above is used. As described above, a developer in which spherical carrier particles and toner are mixed at the same ratio as in a conventional two-component developer is preferably used. As a carrier, a general coating carrier (density of 5 to 8 g / c) is used.
m ³ ), the toner concentration in the developer is 2-3.
0% by weight, preferably 5 to 20% by weight.

If the amount is less than 2% by weight, the number of toners required for development cannot be secured, and the coverage decreases, resulting in excessive charging and a decrease in developability.

If the content is more than 30% by weight, the coverage becomes large, and poor charging and toner scattering easily occur.

However, when a relatively light (2-4 g / cm ³ ) resin-dispersed carrier having the above-mentioned density is used as the carrier in the developer, the toner concentration in the developer is as follows:
Slightly higher than when using a general resin-coated carrier,
The content is preferably 5 to 40% by weight, more preferably 10 to 30% by weight.

If necessary, a fluidizing agent for improving the fluid sliding of the particles, a cleaning agent for cleaning the surface of the image forming body 1 and the like are mixed with the developer. As the fluidizing agent, colloidal silica, silicon varnish, metal soap or nonionic surfactant can be used. As the cleaning agent, a surfactant such as fatty acid metal salt, organic group-substituted silicon or fluorine can be used. Can be.

The transfer belt 14a has a volume resistivity of 10 ¹² -1.
It is an endless belt of 0 ¹⁵ Ωcm, for example, a conductive material is dispersed in engineering plastics such as modified polyimide, thermosetting polyimide, ethylene tetrafluoroethylene copolymer, polyvinylidene fluoride, nylon alloy, etc. This is a seamless belt having a two-layer structure in which a 1.0 mm semiconductive film substrate is coated with a fluorine coating having a thickness of 5 to 50 μm, preferably as a toner filming preventing layer. In addition, as the base of the transfer belt 14a, a semiconductive rubber belt having a thickness of 0.5 to 2.0 mm in which a conductive material is dispersed in silicon rubber or urethane rubber can be used. Transfer belt 1
4a is stretched in contact with the driving roller 14d and the driven roller 14e, and at the time of the image forming apparatus, the driving roller 14d is rotated by a driving motor (not shown) so as to be upstream of the transfer position for each color. Pressing elastic plate 14b provided
As a result, the transfer belt 14a is pressed against the photosensitive drum 10, and the transfer belt 14a is rotated clockwise as indicated by the arrow in FIG. At this time, the photosensitive drum 10 is driven to rotate by receiving the driving force of the transfer belt 14a following the movement of the transfer belt 14a.

A primary transfer unit 14c as a transfer unit for each color
Is preferably constituted by a corona discharger, is provided opposite to the photosensitive drum 10 for each color with the transfer belt 14a interposed therebetween, and the transfer belt 14a and the photosensitive drum 1 for each color are provided.
A transfer area (no sign) is formed for each color between 0 and 0. A DC voltage having a polarity opposite to that of the toner (positive polarity in the present embodiment) is applied to the primary transfer device 14c for each color, and a transfer electric field is formed in the transfer area. The toner image is transferred onto the transfer belt 14a.

The static eliminator 14m, which is a static eliminator for each color,
Preferably, the primary transfer unit 1 is constituted by a corona discharger.
The transfer belt 14a charged by 4c is neutralized.

Pressing elastic plate 1 serving as pressing means for the transfer belt
4b is formed by a rubber blade of urethane or the like, is disposed upstream of the transfer position for each color, presses the transfer belt 14a against the photosensitive drum 10 at the time of image formation, and follows the movement of the transfer belt 14a to move the photosensitive belt. The body drum 10 is rotated.

The fixing device 17 serving as a fixing means includes a fixing roller 17 having a heater inside at least one of the rollers.
a, and a pressure roller 17b. The toner image on the transfer material is fixed by applying heat and pressure between the fixing roller 17a and the pressure roller 17b.

The cleaning device 190, which is a means for cleaning the image forming body for each color, and the cleaning device 190a, which is a means for cleaning the transfer belt, have the same structure, and as will be described later in detail, the cleaning device 190 and the cleaning device 190 The cleaning device 190 removes the transfer residual toner of the photosensitive drum 10 for each color by the recharging roller 192 and the cleaning roller 191 that is a cleaning member provided in each of the devices 190a.
The cleaning device 190a cleans the transfer residual toner on the transfer belt 14a.

Next, the image forming process (image forming step) will be described.

When the photosensitive member drive motor (not shown) is started by the start of image recording, the photosensitive drum 10 of the yellow (Y) image forming unit 100 is rotated in the counterclockwise direction indicated by the arrow in FIG. Charger 11
, The application of a potential to the Y photoconductor drum 10 is started.

After the electric potential is applied to the Y photosensitive drum 10, the Y exposure optical system 12 starts the image writing by the first color signal, that is, the electric signal corresponding to the Y image data, so that the Y photosensitive drum 10 is exposed. Y of the original image on the surface of the body drum 10
An electrostatic latent image corresponding to the image is formed.

The latent image is reversal-developed in a non-contact state by the Y developing unit 13 to form a yellow (Y) toner image in accordance with the rotation of the Y photosensitive drum 10.

The Y toner image formed on the Y photoreceptor drum 10 as an image forming body by the above-described image forming process is transferred to the Y transfer area (no symbol) in the Y transfer area (no sign). The transfer belt 1 is moved by the primary transfer device 14c.
4a.

Next, the transfer belt 14a is synchronized with the Y toner image, and the magenta (M) image forming unit 1 is rotated.
00, an electric potential is applied by the charging action of the M scorotron charger 11, and the M exposure optical system 12 performs image writing using the second color signal, that is, an electric signal corresponding to M image data, and develops the M image. By the non-contact reversal development by the device 13, the M toner image is transferred onto the M photoreceptor drum 10 in the M transfer area (no symbol) by the M primary transfer device 14 c as the first transfer means. The M toner image is formed by being superimposed on the Y toner image of FIG.

By the same process, the image is synchronized with the superposed toner images of Y and M, and is formed by the third color signal formed on the photosensitive drum 10 of C by the image forming unit 100 of cyan (C). The C toner image corresponding to the C image data is transferred from the top of the Y and M toner images by the C primary transfer unit 14c, which is the first transfer unit, in the C transfer area (no symbol). A toner image of C is formed on the photosensitive drum 10 of K by the black (K) image forming unit 100 in synchronism with the toner image of Y, M, and C. The K toner image corresponding to the K image data based on the fourth color signal is transferred by the K primary transfer unit 14c as the first transfer unit in the K transfer area (no sign). From the top of the C toner image Over image is formed by overlapping, Y, M, color toner image overlay C and K are formed on the transfer belt 14a.

The transfer residual toner remaining on the peripheral surface of the photosensitive drum 10 for each color after the transfer is cleaned by a cleaning device 190 which is a cleaning means of the image forming body for each color.

In synchronization with the formation of the superimposed color toner image on the transfer belt 14a, a recording sheet is fed from a paper feed cassette (not shown) as a transfer material storage means via a timing roller (not shown) as a transfer material feed means. P is conveyed to a transfer area (no sign) of a secondary transfer device 14g, which is a second transfer unit, and a secondary transfer device to which a DC voltage having the opposite polarity (positive polarity in the present embodiment) to the toner is applied. By 14g,
The superimposed color toner images on the transfer belt 14a are collectively transferred onto the recording paper P.

The recording paper P on which the color toner image has been transferred is
The charge is removed by a charge removing electrode 16b, which is a separating means formed of a sawtooth electrode plate, conveyed to the fixing device 17, and heat and pressure are applied between the fixing roller 17a and the pressure roller 17b, so that the recording paper P After the toner image is fixed,
The sheet is discharged to a tray (not shown) outside the apparatus.

The transfer residual toner remaining on the peripheral surface of the transfer belt 14a after the transfer is cleaned by a cleaning device 190a which is a transfer belt cleaning means provided opposite to the driven roller 14e across the transfer belt 14a. .

In the above, the transfer material is transferred to the transfer belt 14a.
The toner image formed by the image forming unit 100 for each color is sequentially transferred onto the transfer material by the first transfer means for each color, and a color toner image is formed on the transfer material. , May be established. In this case,
Transfer by the second transfer means is unnecessary.

As described with reference to FIG. 2 or FIG. 3 in the first embodiment, the cleaning device 190, which is a means for cleaning the image forming body, moves the photosensitive drum 10 having the transfer residual toner at the cleaning position. The photosensitive drum 1 is disposed upstream of the drum 10 in the rotation direction.
A recharging roller 192, which is a recharging unit that is driven to rotate by contacting with the photosensitive drum 10, is disposed downstream of the photosensitive drum 10 in the rotation direction, and is driven and rotated while forming a nip of 1 to 5 mm with the photosensitive drum 10. A cleaning roller 191 as a cleaning member, a collection roller 195 formed of a metal roller such as aluminum or stainless steel for collecting toner from the cleaning roller 191, a scraping plate 196 for scraping toner from the collection roller 195, and a cleaning roller 191.
The partition plate is a partition member provided between the recharging roller 192 and the cleaning roller 191 using a thin plate member having elasticity, for example, a mylar film, so that the toner scattered by the cleaning is not attached to the recharging roller 192. 193 and the photosensitive drum 1
The transfer residual toner remaining on the peripheral surface of No. 0 is cleaned.
The toner scraped into the cleaning device 190 is collected by a screw 194 into a waste toner container (not shown).

The cleaning device 190a, which is a transfer belt cleaning means, is disposed upstream of the transfer belt 14a having the transfer residual toner at the cleaning position in the rotation direction of the transfer belt 14a, and contacts the transfer belt 14a. A recharging roller 192, which is a recharging unit that is driven and rotated, and a cleaning member that is disposed downstream of the transfer belt 14a in the rotation direction and that is driven and rotated by forming a nip of 1 to 5 mm with the transfer belt 14a. A roller 191, a collection roller 195 made of a metal roller such as aluminum or stainless steel for collecting toner from the cleaning roller 191, a scraping plate 196 for scraping toner from the collection roller 195, and toner scattered by the cleaning roller 191 To the recharging roller 192 Sheet member having elasticity so as not to wear, for example, using a Mylar film or the like, re-charging roller 1
The transfer roller 14 includes a partition plate 193 which is a partition member provided between the transfer roller 92 and the cleaning roller 191, and cleans the transfer residual toner remaining on the peripheral surface of the transfer belt 14a. The toner scraped into the cleaning device 190a is collected by a screw 194 into a waste toner container (not shown).

As described with reference to FIG. 3 of the first embodiment,
The recharging roller 192, which is a roller-shaped recharging means of the cleaning devices 190 and 190a, is applied with a high AC voltage, preferably a DC voltage superimposed thereon, through a sliding electrode (not shown) as described later. Conductive metal core 192a
And a sponge-like EDMD or urethane rubber having a cell diameter of about 150 μm, in which conductive carbon powder is dispersed, provided functionally on the cored bar 192a.
The volume resistivity is about 10 ⁵ to 10 ⁶ Ω · cm, and the hardness is 25 to 35.
The conductive layer 192b has a volume resistivity having a function of suppressing current by an in-layer voltage drop against an excess current and preventing charging failure and photoconductor dielectric breakdown due to a power supply voltage drop. Prevents contamination of the photoreceptor by the medium resistance layer 192c of semiconducting property of about 10 ⁸ Ω · cm and additives contained in the internal rubber material, and accumulation of dirt on the surface of the recharging roller 192 due to adhesion of developer and paper powder. For example, a three-layer elastic roller member including a protective layer 192d using a resin such as nylon is used. The cleaning rollers 19 of the cleaning devices 190 and 190a
1 also has the same structure as the recharging roller 192,
1a, a conductive elastic layer 191b and a medium resistance layer 191c
And a protective layer 191d.

The outer diameter of the recharging roller 192 and the cleaning roller 191 is 5 to 20 mm, and the hardness measured from the outside is 35 to 55 degrees (Asker C). The hardness measured from the surface of the conductive elastic layers 192b, 191b is 20 to 40 degrees (Asker C), and the surface of the conductive elastic layers 192b, 191b and the metal cores 192a, 191b.
The electric resistance value measured between a and a is 10 ⁴ to 10 ⁶ Ω.
The surface of the middle resistance layers 192c and 191c and the core metal 192
a, 191a is 10 ⁶ to 10 ^9.
And the thickness of the outer protective layers 192d and 191d is 5
0 to 100 μm.

An AC voltage on which a DC voltage of the same polarity as the toner (in this embodiment, a negative polarity) is superimposed is applied to the recharging roller 192 as a recharging bias, so that the photosensitive drum 10 and the transfer belt 14a after the transfer are transferred. The transfer residual toner remaining in the transfer residual toner area on the peripheral surface is recharged, but has a negative DC voltage of -100 to -40.
0V, AC voltage frequency 1-2kHz, voltage V
A sine wave or rectangular wave having a _{PP of} 1.0 to 2.5 kV is used, and by applying a recharging bias, the average charge amount (Q / M) of the transfer residual toner is reduced by the toner (toner used) at the time of development. The average charge amount (the charge amount of the negative polarity in the present embodiment) is -10 to -30 μC / g, and is uniformly charged to -5 to -15 μC / g, which is lower than the absolute value (charge amount). The surface potential of the photoconductor drum 10 and the transfer belt 14a is made flat by recharging, and the residual toner is transferred to the photoconductor drum 10 and the transfer belt 14a. The adhesive force is reduced uniformly, and is conveyed to the cleaning area of the cleaning roller 191 on the downstream side without being scattered on the photosensitive drum 10 or the transfer belt 14a.

At the position of the cleaning roller 191, the charging amount is increased by the recharging roller 192 by a cleaning bias to which a DC voltage of +300 to +1500 V is applied in a polarity opposite to that of the toner (positive polarity in the present embodiment). The transfer residual toner on the photosensitive drum 10 and the transfer belt 14a that has been made uniform is cleaned on the cleaning roller 191.

The toner on the cleaning roller 191 is
The recovery roller 195, which is driven and rotated in contact with the cleaning roller 191, has a polarity opposite to that of the toner (positive polarity in the present embodiment) and a DC bias voltage of +300 to + 1500V is applied. It is collected on the collection roller 195.

The toner collected on the collection roller 195 is scraped into the cleaning device 190 by the scraping plate 196, and is collected by the screw 194 into a waste toner container (not shown).

As described above, unevenness in image transfer at the time of transfer of a toner image due to a shock at the time of contact of the cleaning member with the image forming body or the transfer belt and release of the contact, or fluctuation or pressing of the pressing force during the contact of the cleaning member. In addition to preventing image unevenness during transfer of the toner image caused by drive unevenness due to handling,
A cleaning member that facilitates cleaning of transfer residual toner that has large variations in toner polarity and charge amount and is difficult to electrically collect, particularly when a small particle size toner or a spherical toner that is difficult to clean and is difficult to clean is used. Pressure fluctuation during the contact of the cleaning member due to the need to increase the pressing force of the cleaning member, preventing the occurrence of image unevenness at the time of transfer of the toner image caused by the driving unevenness due to the pressing operation, and the cleaning property of the transfer residual toner. Is improved.
Further, a driving source for the image forming body is not required, and the image forming body follows the speed of the transfer belt, so that the driving unevenness of the image forming body does not occur and the image unevenness is prevented. Particularly, since the plurality of image forming bodies follow the speed of the transfer belt, the displacement of the toner images sequentially transferred from the plurality of image forming bodies onto the transfer belt is prevented.

Embodiment 3 The image forming process and each mechanism of one embodiment of the third example of the image forming apparatus according to the tenth, twelfth to fourteenth aspects of the present invention, and the cleaning means are described with reference to FIGS. This will be described with reference to FIGS. FIG. 5 is a sectional view of a color image forming apparatus showing an embodiment of a third example of the image forming apparatus according to claims 10, 12 to 14 of the present invention.

In this embodiment, a photosensitive drum 10 as one image forming body, a scorotron charger 11 as one charging unit, an exposure optical system 12 as one image writing unit, A process member such as a developing unit 13 as a developing means is used, and charging of a scorotron charger 11 on a photosensitive drum 10, image writing by an exposure optical system 12, and development by a developing unit 13 are repeated to form a toner. An image is formed, and a color toner image is formed by superimposing each color toner image sequentially formed on the photoconductor drum 10, and then the superimposed color toner image formed on the photoconductor drum 10 is transferred by a transfer unit. A color image is formed by transferring the recording paper P on the recording paper P at one time to form a color image, and then separating the recording paper P from the surface of the photosensitive drum 10 by a separating unit and fixing by a fixing unit. An image forming apparatus. Process members such as a photosensitive drum 10 as an image forming body, a scorotron charger 11 as a charging unit, an exposure optical system 12 as an image writing unit, and a developing unit 13 as a developing unit for each color are described above. Those having the same functions and structures as described in the first embodiment are used. The cleaning device 190, which is a cleaning unit for the image forming body, has the same structure as that described in the first embodiment.

Referring to FIG. 5, reference numeral 10 denotes a photosensitive drum as an image forming member, which is formed by coating an organic photosensitive layer (OPC) on a cylindrical metal substrate made of aluminum or the like. It is formed by applying an overcoat layer (protective layer) on the surface, and is grounded and driven to rotate clockwise in FIG.
Prior to the formation of a toner image on the photosensitive drum 10, a cleaning device 190, which is a cleaning unit for an image forming body, which will be described in detail later, includes a recharging roller 192 provided in the cleaning device 190 and a cleaning roller 191 as a cleaning member. Are kept at a position separated from (contact release from) the photosensitive drum 10 indicated by a dotted line in FIG. The contact and release (separation) of the cleaning device 190 from the photosensitive drum 10 are performed by sliding on the guide rail GL using a cam, a lever, and the like (not shown). Also, the transfer roller 16a can be brought into contact with or released from (separated from) the photosensitive drum 10, and is separated when a superimposed color toner image is formed on the photosensitive drum 10.

The organic photoreceptor layer comprises a charge generation material (CGM)
And a charge transport layer (CTL) containing a charge transport material (CTM) as a main component. The organic photoreceptor layer comprises a charge generation material (CGM) and a charge transport material (C
(TM) in one layer, and the photosensitive layer having the single-layer structure or the two-layer structure usually contains a binder resin.

In the photoreceptor drum having the two-layered organic photoreceptor layer, the CGM contained in the CGL may be an azo pigment, an azulenium pigment, a phthalocyanine pigment which is sensitive to light from a light source such as an LED or an LD. , A perylene pigment is used, and red to infrared light (600 nm
Copper phthalocyanine pigments, titanyl phthalocyanine pigments, and the like are preferably used as the CGM of the OPC photoreceptor that is sensitive to 850 nm.

As the binder resin used for CGL, a polyvinyl butyral resin or a polycarbonate resin is used, which is excellent in sensitivity, potential change upon repeated use, and the like. These binder resins can be used alone or as a mixture of two or more.

As a solvent or a dispersion medium used for the formation of CGL, a ketone-based or halogen-based solvent is preferably used, and the sensitivity and the potential change upon repeated use are further improved. In addition, these solvents can be used alone or as a mixed solvent of two or more kinds.

The weight ratio of CGM to the binder resin in the CGL is 100: 1 to 1000, the film thickness of the CGL is 0.01 to 10 μm, and the coating method for forming the CGL is as follows. There are various coating methods such as coating, wire bar coating, spray coating, dip coating and slide hopper coating.

Next, as the CTM contained in the CTL, hydrazone compounds, styryl compounds, benzidine compounds, stilbene compounds and the like are used.

As the binder resin used in the CTL, a wide range of insulating resins can be appropriately selected and used. Preferred binder resins are silicon-alkyd resin, phenol-formaldehyde resin, and poly-N- Insulating resins such as vinyl carbazole and polysilane can be mentioned, and these binder resins can be used alone or in combination of two or more.

The mixing ratio of the binder resin and CTM is 1:
It is set to 10 to 500, and more preferably 1:20 to 150. The thickness of the CTL is set to 1 to 100 μm.
~ 50 μm is preferred.

As a coating method, a method similar to CGL can be used.

If necessary, an intermediate layer is provided between the organic photoreceptor layer and the conductive layer. Examples of the intermediate layer include vinyl chloride vinyl acetate copolymer, vinyl chloride vinyl acetate maleate copolymer, ethyl cellulose and carboxymethyl cellulose. And a resin layer having a thickness of 0.01 to 2 μm, such as a copolymer type or modified type alcohol-soluble polyamide resin.

As the overcoat layer (protective layer), a layer obtained by dissolving a resin such as silicon or fluorine in an organic solvent and further adding an antioxidant, a matting agent and the like as necessary is used. The application method is not particularly limited, but spray application and slide hopper application are preferred. The film thickness is 0.
It is formed to a thickness of about 5 to 10 μm. Thereby, the hardness, strength, and the like of the surface of the photoreceptor layer are increased, and generation of scratches is prevented, and high-temperature durability is obtained. Further, since the surface of the photoconductor layer can be more strongly cleaned, it is easy to remove the deposits on the surface. Furthermore, toner transferability,
In particular, transferability with a small particle size toner or a spherical toner is also improved.

Scorotron charger 11 as charging means
Is charged by a control grid maintained at a predetermined potential and corona discharge having the same polarity (minus polarity in the present embodiment) as toner (toner during development) used by the corona discharge electrode (in the present embodiment). Performs negative charging) to apply a uniform potential to the photosensitive drum 10. As the corona discharge electrode of the scorotron charger 11, a saw-tooth electrode or a needle electrode can also be used.

The exposure optical system 12, which is an image writing means, rotationally scans a laser beam emitted from a laser light source (without a sign) with a rotating polygon mirror (without a sign), and scans an fθ lens (without a sign) and a reflection mirror (without a sign). The photosensitive layer of the photosensitive drum 10 charged by the scorotron charger 11 is image-exposed according to image data read by a separate image reading device and stored in the memory. The formation of an electrostatic latent image thereon is repeated for each color.

A developing device 13 provided around the photoreceptor drum 10 is a developing unit for each color such as yellow (Y), magenta (M), cyan (C), and black (K). A cylindrical non-magnetic stainless steel or aluminum material having a thickness of, for example, 0.5 to 1 mm and an outer diameter of 15 to 25 mm that rotates in the forward direction with respect to the rotation direction of the photosensitive drum 10 at the developing position while maintaining a predetermined gap with respect to the peripheral surface. And contains therein a one-component or two-component developer of yellow (Y), magenta (M), cyan (C), and black (K) according to the development color of each color. I have. The developing device 13 is kept in non-contact with the photosensitive drum 10 with a predetermined gap, for example, 100 to 500 μm, by an abutting roller (not shown), and a DC voltage (DC bias) and an AC voltage are applied to the developing sleeve 131. By applying a developing bias on which (AC bias) is superimposed, non-contact reversal development is performed, and a toner image is formed on the photosensitive drum 10.

A developing device 13 as a developing means is conventionally provided with a two-component developer or a two-component developer comprising a non-magnetic toner having an average particle diameter of tens μm and a magnetic carrier having an average particle diameter of tens to hundreds μm. Is a one-component developer composed of a non-magnetic toner having a size of about 10 μm. However, when the developer is used for non-contact development, the transfer of the toner can be effectively controlled by the oscillating electric field. Therefore, the toner having an average particle diameter of 1 to 20 μm, preferably 4 to 10 μm and the average particle diameter of 10 to 10 μm are used. 60μ
m, more preferably a two-component developer comprising a carrier of 20 to 50 μm or a one-component developer comprising a toner having an average particle diameter of 1 to 20 μm, preferably 4 to 10 μm. This will be described.

(Carrier) In general, if the average particle size of the magnetic carrier particles is large, the condition of the ears of the magnetic brush formed on the developer carrying member becomes coarse, so that the electrostatic latent image is formed while being vibrated by an electric field. Even when development is performed, unevenness tends to appear in the toner image, and the toner concentration in the ears becomes low, so that there is a problem that high-density development is not performed. In order to solve this problem, the average particle diameter dc of the magnetic carrier particles may be reduced.
m, preferably 20 to 50 μm, the above problem did not occur.

When dc is 10 μm or less, it is difficult to sufficiently magnetize the carrier, so that the carrier adheres to the surface of the image forming body together with the toner particles, or the carrier easily scatters.

If dc is 60 μm or more, the specific surface area of the carrier becomes small, so that the toner cannot be sufficiently charged. Further, since the covering ratio is high, toner scattering is also likely to occur.

The volume average particle diameter dc can be measured by a laser diffraction particle size distribution analyzer “HEROS” (S
YMPATEC). First, 10 mg of magnetic particles were added together with a surfactant to 50 m of water using a wet disperser.
g and then an ultrasonic homogenizer (output 15
0W), and the value was measured after performing a pretreatment of dispersing for 1 to 10 minutes while taking care not to cause re-aggregation due to heat generation.

The carrier magnetization intensity (maximum magnetization) is 5
-60 emu / g, preferably 10-40 emu / g. Although this strength depends on the magnetic flux density on the developer carrying member, under the general condition of the magnetic flux density of the developer carrying member, if it is less than 5 emu / g, the magnetic binding force does not work and the carrier is scattered. Becomes On the other hand, if it exceeds 60 emu / g, the carrier ears become too high, making it difficult to maintain a non-contact state with the image forming body.

The measurement of the magnetization intensity of the carrier is performed by filling the carrier particles while tapping them into a sample cell of 0.25 cm × 3 cm ² , attaching the sample to a pickup coil, setting the sample on a magnetizer, and setting the DC magnetization characteristics automatically. Recording device "TY
This is performed by causing the XY recorder to draw a hysteresis curve using "PE3257" (manufactured by Yokogawa Hokushin Electric Co., Ltd.).

Such a magnetic carrier is made of a metal such as iron, chromium, nickel, cobalt or the like, or a compound or alloy thereof, such as triiron tetroxide, γ-oxide, as in a conventional magnetic carrier. Ferric, chromium dioxide, manganese oxide, ferrite, manganese-copper alloy, ferromagnetic spherical particles, or the surface of these spherical magnetic particles styrene resin, vinyl resin, ethylene resin And a rosin-modified resin, an acrylic resin, a polyamide resin, an epoxy resin, a polyester resin, a silicone resin, a fluororesin, or the like, or a spherical coating with a copolymer.

Further, a so-called resin-dispersed carrier in which magnetic fine particles are dispersed and contained in these resins can also be used.

(Toner) Generally, when the average particle size of the toner particles is reduced, the charge amount is qualitatively reduced in proportion to the square of the particle size, and the adhesive force such as van der Waals force is relatively increased. Scattered easily, and fogging is likely to occur. Then, when the average particle size is 10 μm or less, this problem becomes remarkable. The developing means of the present embodiment solves this problem by performing the development under an oscillating electric field.

As the volume average particle diameter D ₅₀ (μm) of the toner increases, the roughness of the image becomes conspicuous as already mentioned. If D ₅₀ is used the toner following micronized 10 [mu] m (small particle size toner), the resolution is remarkably improved, so give a clear high-quality images shading difference also faithfully reproduced. D ₅₀ is 20μm or more, results in degradation of image quality, at the 1μm or less, poor charging, scattering and the like easily occurs.

For the above reasons, the volume average particle diameter D _{50 of the} toner
Is 1 to 20 μm, preferably 4 μm ≦ D ₅₀ ≦ 10 μm.

When D ₅₀ is larger than 10 μm, the particle size is large and the resolution is insufficient, and when D ₅₀ is smaller than 4 μm, the cohesive force is large and triboelectric charging tends to be poor.

Here, the volume average particle diameter D used for the average particle diameter was
₅₀ is a coulter counter TA-II type (aperture 1
00 μm, manufactured by Coulter Corporation).

Further, since the toner particles follow the electric field of the developing bias, the absolute value of the charge amount of the toner particles is preferably set to 10 to 30 μC / g in the case of the two-component magnetic developer, in order to secure the developability. It is desirable from the viewpoint of preventing fog and scattering. In particular, when the particle size is small, a high charge amount is required.

Examples of the binder resin for such a toner include a styrene resin, a vinyl resin, an ethyl resin, a rosin-modified resin, an acrylic resin, a polyamide resin, an epoxy resin, a polyester resin, and a styrene-acryl resin. And the like, or a mixed resin or the like. Coloring components such as color pigments, a charge controlling agent, a releasing agent such as wax if necessary, a fluidizing agent for improving the fluid sliding of the particles, and a cleaning agent useful for cleaning the surface of the image carrier. In addition, the toner can be produced by a method known in the art, such as a conventionally known pulverization granulation method, suspension polymerization method, emulsion polymerization method, or the like. As a fluidizing agent, colloidal silica, silicon varnish, metal soap, a nonionic surfactant, or the like can be used. As a cleaning agent, a surfactant such as a fatty acid metal salt, organic group-substituted silicon, or fluorine can be used. Can be.

As the toner shape, a spherical toner produced by a polymerization method or the like is preferable because it has a higher fluidity than an irregular toner and has a small adhesive force with an image forming body and a high transfer rate.

(Developer) When the toner is used as a one-component developer in the developing device 13 of the present embodiment, the toner described above is used. As described above, a developer in which spherical carrier particles and toner are mixed at the same ratio as in a conventional two-component developer is preferably used. As a carrier, a general coating carrier (density of 5 to 8 g / c) is used.
m ³ ), the toner concentration in the developer is 2-3.
0% by weight, preferably 5 to 20% by weight.

If the amount is less than 2% by weight, the number of toners required for development cannot be secured, and the coverage decreases, resulting in excessive charging and a decrease in developability.

When the content is more than 30% by weight, the coverage becomes large, and poor charging and toner scattering are likely to occur.

However, when a relatively light (2 to 4 g / cm ³ ) resin-dispersed carrier having the above-described density is used as the carrier in the developer, the toner concentration in the developer is as follows:
Slightly higher than when using a general resin-coated carrier,
The content is preferably 5 to 40% by weight, more preferably 10 to 30% by weight.

[0171] If necessary, a fluidizing agent for improving the fluid sliding of the particles, a cleaning agent useful for cleaning the surface of the image forming body 1 and the like are mixed with the developer. As the fluidizing agent, colloidal silica, silicon varnish, metal soap or nonionic surfactant can be used. As the cleaning agent, a surfactant such as fatty acid metal salt, organic group-substituted silicon or fluorine can be used. Can be.

First, development of yellow (Y) by the Y developing device 13 for the first color is performed by the developing sleeve 131 which rotates while holding the Y developer. Since the DC bias and the photoconductor charging potential V _H and the toner charging are of the same polarity, the toner which has been triggered to separate from the magnetic carrier by the AC bias has a photoconductor charging potential V higher than the DC bias during positive charging. _It does not adhere to the portion _H , but adheres to the exposed portion potential _VL portion lower in potential than the DC bias, and the latent image on the photosensitive drum 10 is visualized (developed) by non-contact reversal development. A Y toner image is formed on the photosensitive drum 10.

After the visualization of the first color is completed, the image forming process of the magenta (M) of the second color is started, and the uniform charging is again performed by the scorotron charger 11, and the latent image based on the image data of the second color is formed. It is formed by the exposure optical system 12. Again, the photoconductor charging potential V is applied over the entire surface of the photoconductor drum 10.
A latent image similar to that of the first color is formed in a portion of the photoconductor layer charged with _H in which the first color image is not formed, and an M toner image is formed by development in the M developing unit 13. However, in the portion where the image of the first color is developed again in the portion where the image of the first color is present, the potential is slightly higher than the exposure portion potential _VL of the first color due to the effect of the light shielding by the toner attached to the first color and the charge of the toner itself. a latent image of V _M is formed, developed in accordance with the voltage of the DC bias and the potential V _M is performed.

An image forming process similar to that for magenta (M) for the second color is performed for cyan (C) for the third color and black (K) for the fourth color.
A superimposed four color toner image is formed by each of the M, C and K toner images.

On the other hand, the recording paper P, which is the transfer material, is fed from the paper feed cassette
a, is fed by the feed roller 15b, and is conveyed to the timing roller 15c.

The recording paper P is fed to the transfer area (no symbol) of the transfer roller 16a in synchronization with the conveyance of the toner image on the photosensitive drum 10 by the driving of the timing roller 15c.

The transfer roller 16a brought into contact with the photosensitive drum 10 is rotated in the same direction as the photosensitive drum 10 in the transfer area in synchronization with the peripheral speed of the photosensitive drum 10, and Paper P fed to the transfer roller 1
6a and the photosensitive drum 10 are in close contact with the toner image,
By applying a bias voltage of the opposite polarity (positive polarity in the present embodiment) to the toner of 1-2 kV to the transfer roller 16a, the color toner image on the photosensitive drum 10 is collectively transferred onto the recording paper P. .

The recording paper P to which the toner image has been transferred is neutralized by the neutralizing electrode 16b formed of a sawtooth electrode plate, and the fixing roller 1 having a heater inside at least one of the rollers.
The toner is conveyed to a fixing device 17 which is a fixing unit having a fixing roller 7a and a pressure roller 17b, and heat and pressure are applied between the fixing roller 17a and the pressure roller 17b to fix the toner adhered on the recording paper P. Then, the sheet is discharged to the outside of the apparatus by a sheet discharge roller 18.

A cleaning device 190 as a means for cleaning an image forming body in which the recharging roller 192 and the cleaning roller 191 as a cleaning member are integrated.
5 is brought into contact with the photosensitive drum 10 indicated by a solid line in FIG. 5, and the transfer residual toner remaining on the peripheral surface of the photosensitive drum 10 serving as an image forming body reaches the cleaning device 190, which will be described in detail later. In the cleaning position with respect to the photoconductor drum 10, the recharging means is disposed upstream of the photoconductor drum 10 in the rotational direction, is rotated in contact with the photoconductor drum 10, is driven to rotate, and is applied with a recharging bias. After being recharged by the recharging roller 192, it is cleaned by a cleaning roller 191 which is a cleaning member that is disposed downstream and abuts on the photosensitive drum 10 and is driven to rotate. The toner cleaned by the cleaning roller 191 is collected by the collection roller 195 from the cleaning roller 191, is scraped from the collection roller 195 by the scraping plate 196, and is collected by the screw 194 in a waste toner container (not shown). Further, the cleaning device 190 is provided with a thin plate member having elasticity so that toner scattered after being cleaned by the cleaning roller 191 does not adhere to the recharge roller 192. It is provided between the roller 192 and the cleaning roller 191.

As described with reference to FIG. 2 or FIG. 3 in the first embodiment, the cleaning device 190, which is a means for cleaning the image forming member, moves the photosensitive drum 10 having the transfer residual toner at the cleaning position. The photosensitive drum 1 is disposed upstream of the drum 10 in the rotation direction.
A recharging roller 192, which is a recharging unit that is driven to rotate by contacting with the photosensitive drum 10, is disposed downstream of the photosensitive drum 10 in the rotation direction, and is driven and rotated while forming a nip of 1 to 5 mm with the photosensitive drum 10. A cleaning roller 191 as a cleaning member, a collection roller 195 formed of a metal roller such as aluminum or stainless steel for collecting toner from the cleaning roller 191, a scraping plate 196 for scraping toner from the collection roller 195, and a cleaning roller 191.
The partition plate is a partition member provided between the recharging roller 192 and the cleaning roller 191 using a thin plate member having elasticity, for example, a mylar film, so that the toner scattered by the cleaning is not attached to the recharging roller 192. 193 and the photosensitive drum 1
The transfer residual toner remaining on the peripheral surface of No. 0 is cleaned.
The toner scraped into the cleaning device 190 is collected by a screw 194 into a waste toner container (not shown).

As described with reference to FIG. 3 of the first embodiment,
The recharging roller 192, which is a roller-shaped recharging means of the cleaning device 190, is connected to a conductive electrode to which a high AC voltage, preferably a DC voltage superimposed thereon, is applied via a sliding electrode (not shown) as described later. Core metal 192a and core metal 19
2a, a sponge-like EDMD having a cell diameter of about 150 μm, in which conductive carbon powder is dispersed,
It is made of urethane rubber or the like, and has a volume resistivity of 10 ⁵ which ensures the contact of the recharging roller 192 with the photosensitive drum 10.
A conductive elastic layer 192b having a hardness of about 25 to 35 degrees (Asker C) having a hardness of about 10 to 10 ⁶ Ω · cm; Has a function to prevent body breakdown,
The medium resistance layer 192c having a semiconducting characteristic having a volume resistivity of about 10 ⁸ Ω · cm, contamination of the photoreceptor due to additives contained in the internal rubber material, and contamination of the surface of the recharging roller 192 due to adhesion of the developer and paper powder. The roller member has a three-layered elasticity with a protective layer 192d made of a resin such as nylon, for example, to prevent the accumulation of toner. Note that the cleaning roller 191 of the cleaning device 190 is also
2 is a roller member having a three-layered elasticity of a conductive elastic layer 191b, a medium resistance layer 191c, and a protective layer 191d on a cored bar 191a.

The outer diameter of the recharging roller 192 and the cleaning roller 191 is 5 to 20 mm, and the hardness measured from the outside is 35 to 55 degrees (Asker C). The hardness measured from the surface of the conductive elastic layers 192b, 191b is 20 to 40 degrees (Asker C), and the surface of the conductive elastic layers 192b, 191b and the metal cores 192a, 191b.
The electric resistance value measured between a and a is 10 ⁴ to 10 ⁶ Ω.
The surface of the middle resistance layers 192c and 191c and the core metal 192
a, 191a is 10 ⁶ to 10 ^9.
And the thickness of the outer protective layers 192d and 191d is 5
0 to 100 μm.

In the image area where the toner image is formed, the recharge roller 192 has the same polarity as the toner as the recharge bias (minus polarity in this embodiment).
Is applied, and the untransferred toner remaining in the untransferred toner area on the peripheral surface of the photosensitive drum 10 after the transfer is recharged. A sin-wave or rectangular wave having a frequency of 1 to 2 kHz and a voltage V _{PP of} 1.0 to 2.5 kV is used as the AC voltage at 100 to -400 V. The average charge of the transfer residual toner is obtained by applying a recharge bias. The amount (Q / M) is the average charge amount of the toner (toner to be used) at the time of development (the charge amount of the negative polarity in the present embodiment).
For μC / g, -5 to -1 which is lower than this in absolute value
The toner is uniformly charged to 5 μC / g (it is made uniform by increasing the charge amount), and the uneven (non-uniform) potential of the surface potential of the photosensitive drum 10 is made flat by recharging, and the transfer residual toner is exposed. The adhesive force with the body drum 10 is reduced uniformly, and is conveyed to the cleaning area of the cleaning roller 191 on the downstream side without being scattered from above the photosensitive drum 10.

At the position of the cleaning roller 191, the charging amount is increased by the recharging roller 192 by the cleaning bias applied with a DC voltage of +300 to +1500 V having the opposite polarity (positive polarity in this embodiment) to the toner. The transfer residual toner on the photosensitive drum 10 that has been made uniform is cleaned on the cleaning roller 191.

The toner on the cleaning roller 191 is
The recovery roller 195, which is driven and rotated in contact with the cleaning roller 191, has a polarity opposite to that of the toner (positive polarity in the present embodiment) and a DC bias voltage of +300 to + 1500V is applied. It is collected on the collection roller 195.

The toner collected on the collecting roller 195 is scraped by the scraping plate 196 into the cleaning device 190 and collected by the screw 194 into a waste toner container (not shown).

As described above, due to the shock at the time of contact of the cleaning member with the image forming member and the release of the contact, the image unevenness at the time of transferring the toner image formed by superposition, or the pressing force during the contact of the cleaning member. This prevents image fluctuations during transfer of superimposed toner images, which are caused by fluctuations in the toner and driving unevenness due to pressure handling, and also causes large variations in toner polarity and charge amount, and makes it difficult to electrically collect transfer residual toner. In order to facilitate cleaning, especially when a small particle size toner or a spherical toner, which is liable to cause cleaning failure and is difficult to clean, is used, the pressing force of the cleaning member must be increased due to the need to increase the pressing force of the cleaning member. Prevents image unevenness during transfer of toner images resulting from drive fluctuations due to pressure fluctuations and pressure handling, and cleans residual toner after transfer. Sex improvement of is achieved.

Embodiment 4 An image forming process and each mechanism of an embodiment of a fourth example of the image forming apparatus according to the eleventh to fourteenth aspects of the present invention, and a cleaning means are shown in FIG. 6 and FIG. This will be described with reference to FIG. FIG. 6 is a sectional view of a main part of a color image forming apparatus showing an embodiment of a fourth example of an image forming apparatus according to claims 11 to 14 of the present invention.

In this embodiment, a photosensitive drum 10 as one image forming body, a scorotron charger 11 as one charging unit, an exposure optical system 12 as one image writing unit, A process member such as a rotary developing device 13A which integrates a developing device 13 as a developing means is used.
Charging of the photosensitive drum 10 by the scorotron charger 11, image writing by the exposure optical system 12,
After a toner image is formed on the photosensitive drum 10 by development by the developing device 13 using the 3A, the toner image is transferred onto an intermediate transfer drum 14A as an intermediate transfer member, and this is repeated for each color, and sequentially. After each color toner image to be formed is superimposed on the intermediate transfer drum 14A to form a color toner image, the superimposed color toner image formed on the intermediate transfer drum 14A is transferred to a recording sheet P as a transfer material by a transfer unit. This is a color image forming apparatus of a type in which a color image is formed by transferring the recording paper P on the recording medium P once, and then the recording paper P is separated from the surface of the photosensitive drum 10 by a separation unit and fixed by a fixing unit.
A photosensitive drum 10 serving as an image forming body, a scorotron charger 11 serving as a charging unit, an exposure optical system 12 serving as an image writing unit, and a developing unit 13 serving as a developing unit for each color provided in a rotary developing unit 13A Process members such as those having the same functions and structures as described in the first embodiment are used. Further, in the present embodiment, the cleaning device 190 which is a cleaning unit for the image forming body and the cleaning device 190b which is a cleaning unit for the intermediate transfer body are used.
Also, a cleaning unit having the same structure as that described in the first embodiment is used.

Referring to FIG. 6, reference numeral 10 denotes a photosensitive drum which is an image forming body, which is formed by coating an organic photosensitive layer (OPC) on a cylindrical metal substrate made of aluminum or the like, and furthermore, a surface of the organic photosensitive layer. Is formed by applying an overcoat layer (protective layer), and is grounded and driven to rotate counterclockwise in FIG.
Prior to the transfer of the toner image formed on the photoreceptor drum 10 to the intermediate transfer drum 14A, a cleaning device 1 which is a cleaning means for an intermediate transfer member, which will be described in detail later.
Reference numeral 90b denotes an integrated unit of the recharging roller 192 provided in the cleaning device 190b and the cleaning roller 191 serving as a cleaning member, and is maintained at a position (released contact) with the intermediate transfer drum 14A indicated by a dotted line in FIG. The contact and release (separation) of the cleaning device 190b from the intermediate transfer drum 14A are performed by sliding on a guide rail GL using a cam, lever, or the like (not shown). Also, the transfer roller 16a can be brought into contact with or released from (separated from) the intermediate transfer drum 14A.
When the superimposed color toner image on A is formed, the separated state is set.

The organic photoreceptor layer is composed of a charge generation material (CGM)
And a charge transport layer (CTL) containing a charge transport material (CTM) as a main component. The organic photoreceptor layer comprises a charge generation material (CGM) and a charge transport material (C
(TM) in one layer, and the photosensitive layer having the single-layer structure or the two-layer structure usually contains a binder resin.

In the photoreceptor drum having the two-layered organic photoreceptor layer, the CGM contained in the CGL may be an azo pigment, an azulenium pigment, a phthalocyanine pigment which is sensitive to light from a light source such as an LED or an LD. , A perylene pigment is used, and red to infrared light (600 nm
Copper phthalocyanine pigments, titanyl phthalocyanine pigments, and the like are preferably used as the CGM of the OPC photoreceptor that is sensitive to 850 nm.

As the binder resin used for CGL, a polyvinyl butyral resin or a polycarbonate resin is used, which is excellent in sensitivity, potential change upon repeated use, and the like. These binder resins can be used alone or as a mixture of two or more.

As a solvent or a dispersion medium used for forming CGL, a ketone-based or halogen-based solvent is preferably used, and sensitivity and potential change upon repeated use are further improved. In addition, these solvents can be used alone or as a mixed solvent of two or more kinds.

The weight ratio of CGM in CGL to the binder resin is 100: 1 to 1000, the thickness of the CGL is 0.01 to 10 μm, and the coating method for forming the CGL is a blade. There are various coating methods such as coating, wire bar coating, spray coating, dip coating and slide hopper coating.

Next, as the CTM contained in the CTL, hydrazone compounds, styryl compounds, benzidine compounds, stilbene compounds and the like are used.

As the binder resin used in the CTL, a wide range of insulating resins can be appropriately selected and used. Preferred binder resins include a silicon-alkyd resin, a phenol-formaldehyde resin and a poly-N- Insulating resins such as vinyl carbazole and polysilane can be mentioned, and these binder resins can be used alone or in combination of two or more.

The mixing ratio of the binder resin and CTM is 1:
It is set to 10 to 500, and more preferably 1:20 to 150. The thickness of the CTL is set to 1 to 100 μm.
~ 50 μm is preferred.

As a coating method, a method similar to CGL can be used.

If necessary, an intermediate layer may be provided between the organic photoreceptor layer and the conductive layer. Examples of the intermediate layer include vinyl chloride vinyl acetate copolymer, vinyl chloride vinyl acetate maleate copolymer, ethyl cellulose, carboxymethyl cellulose. And a resin layer having a thickness of 0.01 to 2 μm, such as a copolymer type or modified type alcohol-soluble polyamide resin.

As the overcoat layer (protective layer), a layer obtained by dissolving a resin such as silicon or fluorine in an organic solvent and further adding an antioxidant, a matting agent and the like as necessary is used. The application method is not particularly limited, but spray application and slide hopper application are preferred. The film thickness is 0.
It is formed to a thickness of about 5 to 10 μm. Thereby, the hardness, strength, and the like of the surface of the photoreceptor layer are increased, and generation of scratches is prevented, and high-temperature durability is obtained. Further, since the surface of the photoconductor layer can be more strongly cleaned, it is easy to remove the deposits on the surface. Furthermore, toner transferability,
In particular, transferability with a small particle size toner or a spherical toner is also improved.

Scorotron charger 11 as charging means
Is charged by a control grid maintained at a predetermined potential and corona discharge having the same polarity (minus polarity in the present embodiment) as toner (toner during development) used by the corona discharge electrode (in the present embodiment). Performs negative charging) to apply a uniform potential to the photosensitive drum 10. As the corona discharge electrode of the scorotron charger 11, a saw-tooth electrode or a needle electrode can also be used.

The exposure optical system 12, which is an image writing means, rotationally scans a laser beam emitted from a laser light source (not shown) by a rotating polygon mirror (not shown), an fθ lens (not shown), and a reflection mirror (not shown). The photosensitive layer of the photosensitive drum 10 charged by the scorotron charger 11 is image-exposed according to image data read by a separate image reading device and stored in the memory. The formation of an electrostatic latent image thereon is repeated for each color.

A developing device 13 which is a developing means for each color such as yellow (Y), magenta (M), cyan (C) and black (K) is included in the order of Y, M, C and K in the rotation direction. Then, a rotary developing device 13A that is rotated clockwise is provided to face the photosensitive drum 10, and development for each color is performed. The developing unit 13 for each color, such as yellow (Y), magenta (M), cyan (C), and black (K), has a predetermined gap with respect to the peripheral surface of the photosensitive drum 10 at the developing position when developing the color. And has a cylindrical developing sleeve 131 made of non-magnetic stainless steel or aluminum having a thickness of, for example, 0.5 to 1 mm and an outer diameter of 15 to 25 mm, which rotates in the forward direction with respect to the rotation direction of the photosensitive drum 10. , Contains a one-component or two-component developer of yellow (Y), magenta (M), cyan (C) and black (K) according to the development color of each color. The developing device 13 is kept in non-contact with the photosensitive drum 10 at a predetermined gap, for example, 100 to 500 μm by an abutting roller (not shown).
DC voltage (DC bias) for developing sleeve 131
By applying a developing bias in which an AC voltage (AC bias) is superimposed, non-contact reversal development is performed, and a toner image is formed on the photosensitive drum 10.

A developing unit 13 as a developing means is conventionally provided with a two-component developer or a two-component developer comprising a non-magnetic toner having an average particle diameter of tens of μm and a magnetic carrier having an average particle diameter of tens to hundreds of μm. Is a one-component developer composed of a non-magnetic toner having a size of about 10 μm. However, when the developer is used for non-contact development, the transfer of the toner can be effectively controlled by the oscillating electric field. Therefore, the toner having an average particle diameter of 1 to 20 μm, preferably 4 to 10 μm and the average particle diameter of 10 to 10 μm are used. 60μ
m, more preferably a two-component developer comprising a carrier of 20 to 50 μm or a one-component developer comprising a toner having an average particle diameter of 1 to 20 μm, preferably 4 to 10 μm. This will be described.

(Carrier) In general, if the average particle size of the magnetic carrier particles is large, the state of the ears of the magnetic brush formed on the developer conveying member becomes coarse, so that the electrostatic latent image is formed while being vibrated by an electric field. Even when development is performed, unevenness tends to appear in the toner image, and the toner concentration in the ears becomes low, so that there is a problem that high-density development is not performed. In order to solve this problem, the average particle diameter dc of the magnetic carrier particles may be reduced.
m, preferably 20 to 50 μm, the above problem did not occur.

When dc is 10 μm or less, it is difficult to sufficiently magnetize the carrier, so that the carrier adheres to the surface of the image forming body together with the toner particles, or the carrier easily scatters.

If dc is 60 μm or more, the specific surface area of the carrier becomes small, so that the toner cannot be sufficiently charged. Further, since the covering ratio is high, toner scattering is also likely to occur.

The volume average particle diameter dc can be measured by a laser diffraction particle size distribution analyzer “HEROS” (S
YMPATEC). First, 10 mg of magnetic particles were added together with a surfactant to 50 m of water using a wet disperser.
g and then an ultrasonic homogenizer (output 15
0W), and the value was measured after performing a pretreatment of dispersing for 1 to 10 minutes while taking care not to cause re-aggregation due to heat generation.

The intensity of the carrier magnetization (maximum magnetization) is 5
-60 emu / g, preferably 10-40 emu / g. Although this strength depends on the magnetic flux density on the developer carrying member, under the general condition of the magnetic flux density of the developer carrying member, if it is less than 5 emu / g, the magnetic binding force does not work and the carrier is scattered. Becomes On the other hand, if it exceeds 60 emu / g, the carrier ears become too high, making it difficult to maintain a non-contact state with the image forming body.

The measurement of the magnetization intensity of the carrier was carried out by filling the carrier particles with tapping into a sample cell of 0.25 cm × 3 cm ² , attaching the sample to a pickup coil, setting the sample in a magnetizer, and setting the DC magnetization characteristics automatically. Recording device "TY
This is performed by causing the XY recorder to draw a hysteresis curve using "PE3257" (manufactured by Yokogawa Hokushin Electric Co., Ltd.).

Such a magnetic carrier is made of a metal such as iron, chromium, nickel, cobalt or the like, or a compound or alloy thereof such as triiron tetroxide, γ-oxide Ferric, chromium dioxide, manganese oxide, ferrite, manganese-copper alloy, ferromagnetic spherical particles, or the surface of these spherical magnetic particles styrene resin, vinyl resin, ethylene resin And a rosin-modified resin, an acrylic resin, a polyamide resin, an epoxy resin, a polyester resin, a silicone resin, a fluororesin, or the like, or a spherical coating with a copolymer.

A so-called resin dispersion type carrier in which magnetic fine particles are dispersed and contained in these resins can also be used.

(Toner) In general, as the average particle diameter of the toner particles decreases, the charge amount decreases qualitatively in proportion to the square of the particle diameter, and the adhesive force such as van der Waals force relatively increases. Scattered easily, and fogging is likely to occur. Then, when the average particle size is 10 μm or less, this problem becomes remarkable. The developing means of the present embodiment solves this problem by performing the development under an oscillating electric field.

When the volume average particle diameter D ₅₀ (μm) of the toner increases, as already mentioned, the roughness of the image becomes conspicuous. If D ₅₀ is used the toner following micronized 10 [mu] m (small particle size toner), the resolution is remarkably improved, so give a clear high-quality images shading difference also faithfully reproduced. D ₅₀ is 20μm or more, results in degradation of image quality, at the 1μm or less, poor charging, scattering and the like easily occurs.

For the above reasons, the volume average particle diameter D _{50 of the} toner
Is 1 to 20 μm, preferably 4 μm ≦ D ₅₀ ≦ 10 μm.

When D ₅₀ is larger than 10 μm, the particle size is large and the resolving power is insufficient, and when D ₅₀ is smaller than 4 μm, the cohesive force is large and triboelectric charging is likely to occur.

Here, the volume average particle diameter D used for the average particle diameter was
₅₀ is a coulter counter TA-II type (aperture 1
00 μm, manufactured by Coulter Corporation).

Since the toner particles follow the electric field of the developing bias, the absolute value of the charge amount of the toner particles is preferably set to 10 to 30 μC / g in the case of the two-component magnetic developer, in order to secure the developing property. It is desirable from the viewpoint of preventing fog and scattering. In particular, when the particle size is small, a high charge amount is required.

Examples of binder resins for such toners include styrene resins, vinyl resins, ethyl resins, rosin-modified resins, acrylic resins, polyamide resins, epoxy resins, polyester resins, and styrene-acrylic resins. And the like, or a mixed resin or the like. Coloring components such as color pigments, a charge controlling agent, a releasing agent such as wax if necessary, a fluidizing agent for improving the fluid sliding of the particles, and a cleaning agent useful for cleaning the surface of the image carrier. In addition, the toner can be produced by a method known in the art, such as a conventionally known pulverization granulation method, suspension polymerization method, emulsion polymerization method, or the like. As a fluidizing agent, colloidal silica, silicon varnish, metal soap, a nonionic surfactant, or the like can be used. As a cleaning agent, a surfactant such as a fatty acid metal salt, organic group-substituted silicon, or fluorine can be used. Can be.

As the toner shape, a spherical toner produced by a polymerization method or the like is preferable because it has a higher fluidity than an irregular toner and has a small adhesive force with an image forming body and a high transfer rate.

(Developer) When the toner is used as a one-component developer in the developing device 13 of the present embodiment, the toner described above is used. As described above, a developer in which spherical carrier particles and toner are mixed at the same ratio as in a conventional two-component developer is preferably used. As a carrier, a general coating carrier (density of 5 to 8 g / c) is used.
m ³ ), the toner concentration in the developer is 2-3.
0% by weight, preferably 5 to 20% by weight.

If the amount is less than 2% by weight, the number of toners required for development cannot be secured, and the coverage decreases, resulting in excessive charging and a decrease in developability.

If the content is more than 30% by weight, the coverage becomes large, and poor charging and toner scattering are likely to occur.

However, when a relatively light (2-4 g / cm ³ ) resin-dispersed carrier having the above-described density is used as the carrier in the developer, the toner concentration in the developer is as follows:
Slightly higher than when using a general resin-coated carrier,
The content is preferably 5 to 40% by weight, more preferably 10 to 30% by weight.

If necessary, a fluidizing agent for improving the fluidity of particles and a cleaning agent useful for cleaning the surface of the image forming body are mixed with the developer. As the fluidizing agent, colloidal silica, silicon varnish, metal soap or nonionic surfactant can be used. As the cleaning agent, a surfactant such as fatty acid metal salt, organic group-substituted silicon or fluorine can be used. Can be.

First, the yellow (Y) of the rotary developing unit 13A
Is rotated to the developing position, and yellow (Y) development by the first color Y developing device 13 is performed by the developing sleeve 131 that rotates while holding the Y developer.
The latent image on the photosensitive drum 10 is developed (developed) by non-contact reversal development, and the Y toner image is transferred to the photosensitive drum 1.
0.

The intermediate transfer drum 14A is the photosensitive drum 10
Is rotated in synchronization with the peripheral speed of the photosensitive drum 10, the Y toner image on the photosensitive drum 10 is included in the intermediate transfer drum 14A,
The image is transferred onto the intermediate transfer drum 14A by an intermediate transfer member transfer unit 14f provided at a transfer position with the photosensitive drum 10.

As will be described later in detail, the transfer residual toner remaining on the photosensitive drum 10 is recharged by a recharging roller 192 and a cleaning roller 191 provided in a cleaning device 190 which is a means for cleaning the image forming body. And the cleaning is performed.

Next, the magenta (M) of the rotary developing device 13A
Is rotated to the developing position, and magenta (M) development by the second color M developing device 13 is performed by the developing sleeve 131 that rotates while holding the M developer.
The latent image on the photoconductor drum 10 is developed (developed) by non-contact reversal development, and the M toner image is transferred to the photoconductor drum 1.
0.

After the M toner image on the photosensitive drum 10 is transferred onto the intermediate transfer drum 14A by the intermediate transfer body transfer unit 14f, the transfer residual toner remaining on the photosensitive drum 10 is cleaned by the cleaning device 190. You.

The same image forming process as that for the second color magenta (M) is performed for the third color cyan (C) and the fourth color black (K), and Y, M, A superimposed four color toner image is formed by each of the C and K toner images.

In synchronism with the formation of the superimposed color toner image on the transfer belt 14a, the recording paper is fed from a paper feed cassette (not shown) as a transfer material storage means via a timing roller (not shown) as a transfer material feeding means. P is the intermediate transfer drum 1
The toner image is fed to the transfer area (no reference numeral) of the transfer roller 16a in synchronization with the conveyance of the toner image on 4A.

The transfer roller 16a brought into contact with the intermediate transfer drum 14A is rotated in the transfer area in the same direction as the intermediate transfer drum 14A in synchronization with the peripheral speed of the intermediate transfer drum 14A. The recording paper P fed to the transfer roller 16a is brought into close contact with the toner image between the transfer roller 16a and the intermediate transfer drum 14A, and has the opposite polarity (positive polarity in this embodiment) to the toner of 1-2 kV applied to the transfer roller 16a. By applying the bias voltage, the color toner image on the intermediate transfer drum 14A is transferred onto the recording paper P at once.

The recording paper P on which the color toner image has been transferred is
The charge is removed by a charge removing electrode 16b, which is a separating means formed of a sawtooth electrode plate, conveyed to the fixing device 17, and heat and pressure are applied between the fixing roller 17a and the pressure roller 17b, so that the recording paper P After the toner image is fixed,
The sheet is discharged to a tray (not shown) outside the apparatus.

A cleaning device 190 as cleaning means for an intermediate transfer member, in which the recharging roller 192 and the cleaning roller 191 as a cleaning member are integrated.
b is brought into contact with the intermediate transfer drum 14A indicated by a solid line in FIG. 6, and the transfer residual toner remaining on the peripheral surface of the intermediate transfer drum 14A, which is an intermediate transfer member, is removed by the cleaning device 190.
b, as will be described in detail later, at the cleaning position with respect to the intermediate transfer drum 14A, it is disposed upstream of the intermediate transfer drum 14A in the rotation direction. Is recharged by a recharging roller 192 which is a recharging means to which the intermediate transfer drum 14A is applied.
The cleaning is performed by a cleaning roller 191 that is a cleaning member that is driven and rotated while being in contact with the cleaning roller 191. The toner cleaned by the cleaning roller 191 is collected by the collection roller 195 from the cleaning roller 191, is scraped from the collection roller 195 by the scraping plate 196, and is collected by the screw 194 in a waste toner container (not shown). Further, the cleaning device 190b is provided with a partition plate 193 which is an elastic thin plate member, for example, a partition member using a mylar film or the like, so that toner scattered after being cleaned by the cleaning roller 191 does not adhere to the recharging roller 192. It is provided between the roller 192 and the cleaning roller 191.

As described with reference to FIG. 2 or FIG. 3 in the first embodiment, the cleaning device 190, which is a means for cleaning the image forming member, moves the photosensitive drum 10 having the transfer residual toner at the cleaning position. The photosensitive drum 1 is disposed upstream of the drum 10 in the rotation direction.
A recharging roller 192, which is a recharging unit that is driven to rotate by contacting with the photosensitive drum 10, is disposed downstream of the photosensitive drum 10 in the rotation direction, and is driven and rotated while forming a nip of 1 to 5 mm with the photosensitive drum 10. A cleaning roller 191 as a cleaning member, a collection roller 195 formed of a metal roller such as aluminum or stainless steel for collecting toner from the cleaning roller 191, a scraping plate 196 for scraping toner from the collection roller 195, and a cleaning roller 191.
The partition plate is a partition member provided between the recharging roller 192 and the cleaning roller 191 using a thin plate member having elasticity, for example, a mylar film, so that the toner scattered by the cleaning is not attached to the recharging roller 192. 193 and the photosensitive drum 1
The transfer residual toner remaining on the peripheral surface of No. 0 is cleaned.
The toner scraped into the cleaning device 190 is collected by a screw 194 into a waste toner container (not shown).

Further, a cleaning device 19 which is a cleaning means for the intermediate transfer drum 14A as an intermediate transfer member.
0b indicates that the intermediate transfer drum 14A having the transfer residual toner is
The recharging roller 1, which is a recharging means that is disposed on the upstream side in the rotation direction of the
92, a cleaning roller 191 that is a cleaning member that is disposed downstream of the intermediate transfer drum 14A in the rotation direction and that is driven and rotated while forming a nip of 1 to 5 mm with the intermediate transfer drum 14A. A collecting roller 195 made of a metal roller of aluminum or stainless steel to be collected, a scraping plate 196 for scraping toner from the collecting roller 195, and a cleaning roller 1
The recharging roller 1 is made of an elastic thin plate member, for example, a mylar film or the like, so that toner scattered after being cleaned by the toner 91 does not adhere to the recharging roller 192.
The transfer roller 92 includes a partition plate 193 that is a partition member provided between the cleaning roller 92 and the cleaning roller 191, and cleans transfer residual toner remaining on the peripheral surface of the intermediate transfer drum 14 </ b> A. The toner scraped into the cleaning device 190a is collected by a screw 194 into a waste toner container (not shown).

As described with reference to FIG. 3 of the first embodiment,
A recharging roller 192, which is a roller-shaped recharging means of the cleaning devices 190 and 190b, is applied with a high AC voltage, preferably a DC voltage superimposed thereon, as described later, via a sliding electrode (not shown). Conductive metal core 192a
And a sponge-like EDMD or urethane rubber having a cell diameter of about 150 μm, in which conductive carbon powder is dispersed, provided functionally on the cored bar 192a.
The volume resistivity is about 10 ⁵ to 10 ⁶ Ω · cm, and the hardness is 25 to 35.
The conductive layer 192b has a volume resistivity having a function of suppressing current by an in-layer voltage drop against an excess current and preventing charging failure and photoconductor dielectric breakdown due to a power supply voltage drop. Prevents contamination of the photoreceptor by the medium resistance layer 192c of semiconducting property of about 10 ⁸ Ω · cm and additives contained in the internal rubber material, and accumulation of dirt on the surface of the recharging roller 192 due to adhesion of developer and paper powder. For example, a three-layer elastic roller member including a protective layer 192d using a resin such as nylon is used. The cleaning rollers 19 of the cleaning devices 190 and 190b are used.
1 also has the same structure as the recharging roller 192,
The conductive elastic layer 191b and the medium resistance layer 191
c and a protective layer 191d to form a three-layered elastic roller member.

The outer diameter of the recharging roller 192 and the cleaning roller 191 is 5 to 20 mm, and the hardness measured from the outside is 35 to 55 degrees (Asker C). The hardness measured from the surface of the conductive elastic layers 192b and 191b is 2
0 to 40 degrees (Asker C) and the conductive elastic layer 192
The electrical resistance measured between the layer surfaces of the layers b and 191b and the metal cores 192a and 191a is 10 ⁴ to 10 ⁶ Ω. The surface of the middle resistance layers 192c, 191c and the cores 192a, 192c
1a is 10 ⁶ to 10 ⁹ Ω, and the thickness of the outer protective layers 192d and 191d is 50 to 1Ω.
00 μm.

As a recharging bias, an AC voltage on which a DC voltage of the same polarity as the toner (in this embodiment, a negative polarity) is superimposed is applied to the recharging roller 192, and the photoreceptor drum 10 and the intermediate transfer drum 14A after transfer are applied. The transfer residual toner remaining in the transfer residual toner area on the peripheral surface is recharged.
A sine wave or rectangular wave having a frequency of 1 to 2 kHz and a voltage V _{PP of} 1.0 to 2.5 kV is used as the AC voltage, and the average charge amount (Q / M) is -10 to -30 μC / g, which is an absolute value of −5 to −30 μC / g, which is an average charge amount of the toner (toner used) during development. In addition to being uniformly charged to −15 μC / g (to be uniform by increasing the charge amount), the uneven potential (uneven) of the surface potential of the photosensitive drum 10 and the intermediate transfer drum 14A is flattened by recharging. The adhesion of the transfer residual toner to the photosensitive drum 10 and the intermediate transfer drum 14A is reduced uniformly, and the photosensitive drum 1
The cleaning roller 191 is conveyed to the cleaning area of the cleaning roller 191 on the downstream side without being scattered from above the intermediate transfer drum 14A.

At the position of the cleaning roller 191, the charging amount is increased by the recharging roller 192 by a cleaning bias having a polarity opposite to that of the toner (positive polarity in the present embodiment) and a DC voltage of +300 to +1500 V is applied. The transfer residual toner on the photosensitive drum 10 and the intermediate transfer drum 14A that has been made uniform is cleaned on the cleaning roller 191.

The toner on the cleaning roller 191 is
The recovery roller 195, which is driven and rotated in contact with the cleaning roller 191, has a polarity opposite to that of the toner (positive polarity in the present embodiment) and a DC bias voltage of +300 to + 1500V is applied. It is collected on the collection roller 195.

The toner collected on the collection roller 195 is scraped into the cleaning device 190 by the scraping plate 196, and collected by the screw 194 into a waste toner container (not shown).

In the above, an intermediate transfer belt using a belt-shaped member may be used as the intermediate transfer member instead of the intermediate transfer drum 14A.

As described above, due to the shock at the time when the cleaning member comes into contact with the image forming body or the intermediate transfer body and the shock at the time of releasing the contact, the image unevenness at the time of transferring the toner image formed by superposition or the contact of the cleaning member. In addition to preventing unevenness in image transfer during transfer of superimposed toner images due to fluctuations in the pressing force during driving and uneven driving due to pressure handling, variations in toner polarity and charge amount are large, making it difficult to electrically collect. This facilitates cleaning of the transfer residual toner, and particularly when small particle size toner or spherical toner that is difficult to clean due to poor cleaning is used, the pressing force of the cleaning member must be increased. Prevents image unevenness during transfer of toner images caused by fluctuations in pressing force during contact and uneven driving due to pressing, and residual toner Improvement of the cleaning performance can be achieved.

[0247]

According to the first to fourth aspects of the present invention, unevenness in image transfer at the time of transfer of a toner image due to a shock at the time of contact of the cleaning member with the image forming body and release of the contact, or pushing during the contact of the cleaning member. In addition to preventing image unevenness at the time of transfer of a toner image caused by drive fluctuation due to pressure fluctuations and pressure handling, it also facilitates cleaning of transfer residual toner, which has a large variation in toner polarity and charge amount and is difficult to electrically collect. When small particle size toner or spherical toner, which is apt to cause poor cleaning and is difficult to clean, is used, the pressing force of the cleaning member must be increased and the pressing force fluctuates during the contact of the cleaning member. This prevents the occurrence of image unevenness at the time of transfer of the toner image resulting from the drive unevenness, and improves the cleaning property of the transfer residual toner.

According to the fifth to ninth aspects, the unevenness of the image when transferring the toner image due to the shock at the time of the contact of the cleaning member with the image forming body or the transfer belt and the release of the contact, or during the contact of the cleaning member with the cleaning member. In addition to preventing fluctuations in the pressing force and unevenness in the transfer of the toner image caused by uneven driving due to the pressing operation, unevenness of the toner polarity and charge amount is large, and it is easy to clean the transfer residual toner which is difficult to electrically collect. In particular, when a small particle diameter toner or a spherical toner that is difficult to clean due to poor cleaning is used, the pressing force of the cleaning member must be increased and the pressing force fluctuates or is pressed during the contact of the cleaning member. It is possible to prevent the occurrence of image unevenness at the time of transferring a toner image caused by driving unevenness due to handling, and to improve the cleaning property of the transfer residual toner. Furthermore, since the driving source of the image forming body is not required, and the image forming body follows the speed of the transfer belt,
Uneven driving of the image forming body does not occur, and image unevenness is prevented.

In particular, since the plurality of image forming members follow the speed of the transfer belt, displacement of the toner images sequentially transferred from the plurality of image forming members onto the transfer belt is prevented.

According to the tenth to fourteenth aspects, the unevenness in the transfer of the superposed toner images due to the shock at the time when the cleaning member comes into contact with the image forming body or the intermediate transfer body and when the contact is released, Or, it may be caused by fluctuation of the pressing force during the contact of the cleaning member or driving unevenness due to the pressing operation.
In addition to preventing image unevenness at the time of transfer of a toner image formed by being superimposed, it also facilitates cleaning of transfer residual toner that has large variations in toner polarity and charge amount and is difficult to electrically collect, and in particular, cleaning failure easily occurs. When a small particle size toner or a spherical toner that is difficult to clean is used, the pressing force of the cleaning member must be increased, and the fluctuation of the pressing force during the contact of the cleaning member and the driving unevenness due to the pressing operation are caused. It is possible to prevent the occurrence of image unevenness during the transfer of the toner image and to improve the cleaning property of the transfer residual toner.

[Brief description of the drawings]

FIG. 1 is a sectional configuration view of a laser printer showing an embodiment of a first example of an image forming apparatus according to claims 1 to 4 of the present invention.

FIG. 2 is an enlarged cross-sectional configuration diagram of a cleaning device used in the image forming apparatus of each example of the present invention.

FIG. 3 is a diagram illustrating a layer configuration of a recharging roller and a cleaning member provided in the cleaning device of FIG. 2;

FIG. 4 is a sectional view of a main part of a color image forming apparatus showing an embodiment of a second example of the image forming apparatus according to claims 5 to 9 of the present invention.

FIG. 5 is a sectional configuration view of a color image forming apparatus showing an embodiment of a third example of the image forming apparatus according to claims 10, 12 to 14 of the present invention.

FIG. 6 is a sectional view of a main part of a color image forming apparatus showing an embodiment of a fourth example of the image forming apparatus according to claims 11 to 14 of the present invention.

DESCRIPTION OF SYMBOLS 10 Photoconductor drum 11 Scorotron charger 12 Exposure optical system 13 Developing device 13A Rotary developing device 14A Intermediate transfer drum 14a Transfer belt 14b Pressing elastic plate 16a Transfer roller 100 Image forming unit 190, 190a, 190b Cleaning device 191 Cleaning roller 192 Recharging roller 193 Partition plate 194 Screw 195 Collection roller 196 Scrape plate GL Guide rail P Recording paper

Claims (14)

[Claims] In an image forming apparatus for forming and transferring a toner image on an image forming body, a cleaning unit for cleaning a transfer residual toner includes:
After the transfer residual toner is recharged by a recharge roller,
Transfer residual toner recharged by the recharging roller,
An image forming apparatus wherein the toner is collected by a cleaning member to which a bias voltage is applied. 2. The image forming apparatus according to claim 1, wherein the cleaning member is a cleaning roller. 3. An average charge amount of the transfer residual toner recharged by the recharge roller has the same polarity as that of the toner at the time of development for forming a toner image on the image forming body, and has The image forming apparatus according to claim 1, wherein the charge amount is smaller than an average charge amount. 4. The image forming apparatus according to claim 1, wherein the average charge amount of the recharged transfer residual toner is 5 to 15 μC / g in absolute value. . 5. An image forming apparatus for forming a toner image on an image forming body and transferring the toner image onto a transfer belt, wherein the cleaning means for cleaning the transfer residual toner comprises:
After the transfer residual toner is recharged by a recharge roller,
Transfer residual toner recharged by the recharging roller,
An image forming apparatus, wherein the image forming body receives a driving force from the transfer belt while being collected by a cleaning member to which a bias voltage is applied. 6. The image forming apparatus according to claim 5, wherein the cleaning member is a cleaning roller. 7. A method for forming a toner image on a plurality of image forming bodies,
The image forming apparatus according to claim 5, wherein the plurality of toner images are sequentially transferred onto a transfer belt. 8. The average charge amount of the recharged transfer residual toner has the same polarity as that of the toner at the time of development for forming a toner image on the image forming body and is larger than the average charge amount of the toner at the time of development. The image forming apparatus according to any one of claims 5 to 7, wherein the image forming apparatus is also small. 9. The image forming apparatus according to claim 5, wherein an average charge amount of the recharged transfer residual toner is 5 to 15 μC / g in absolute value. . 10. An image forming apparatus for forming and transferring a superimposed toner image on an image forming body, wherein a cleaning means for cleaning the transfer remaining toner remaining on the image forming body recharges the transfer remaining toner. An image forming apparatus comprising: a recharging roller for applying a bias voltage; and a cleaning member for recovering transfer residual toner recharged by the recharging roller by applying a bias voltage. 11. An image forming apparatus for transferring a toner image formed on an image forming body to form a superimposed toner image on an intermediate transfer body and transferring the same, the transfer residue remaining on the intermediate transfer body. The cleaning means for cleaning the toner includes a recharging roller for recharging the transfer residual toner, and a cleaning member for applying a bias voltage and collecting the transfer residual toner recharged by the recharge roller. An image forming apparatus comprising: 12. The image forming apparatus according to claim 10, wherein the cleaning member is a cleaning roller. 13. The image forming apparatus according to claim 10, wherein the recharging roller and the cleaning member can be moved integrally. 14. An AC voltage on which a DC voltage is superimposed is applied to the recharging roller.
14. The image forming apparatus according to any one of claims 13 to 13.