JP2000098848A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress damage of a developer when the developer remaining on an image carrier is recovered and to prevent image formation quality from being degraded when it is used in a reuse system by providing a non-magnetic sleeve which is disposed opposite to an image carrier without contact with it and has a rotary magnetic-pole generation means inside. SOLUTION: A cleaning means 7 has a recovery sleeve 7c, as the non- magnetic sleeve, incorporating a rotary multipolar magnet 7d which rotates as the rotary magnetic-pole generation means. By the rotation of the multipolar magnet 7d in the A direction of an arrow, developer peeled and recovered from the photoreceptor drum 2 in a developer recovery part (an empty space between the recovery sleeve 7c and the photoreceptor drum 2) is carried in the B direction of an arrow on the surface of the recovery sleeve 7c as the multipolar magnet 7d rotates. This carrying uses the phenomena in which the nap of the developer falls down toward the approaching subsequent pole. The developer finally falls down by the action of a developer damming part 7b and is carried to a recovered-developer storage part 7a as a recovery container.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image forming apparatus provided with a cleaning means for removing a developer remaining on an image bearing member carrying a developer.

[0002]

2. Description of the Related Art Regarding electrophotography, U.S. Pat.
The methods described in Japanese Patent Publication No. 297,691, Japanese Patent Publication No. 42-23910, and Japanese Patent Publication No. 43-24748 are known.

Generally, a photoconductive substance is used to form an electric latent image on a latent image carrier (photoreceptor) by various means, and then the latent image is developed with toner to be used. Accordingly, after the toner image is transferred onto a transfer material such as paper, the image is fixed by heating, pressurizing, heating and pressurizing, or solvent vapor to obtain a copy.

[0004] As the developing method, the size of the apparatus is reduced,
From the viewpoint of ease of maintenance, a non-contact magnetic one-component developing system in which a magnetic toner is developed by the action of an alternating electric field is known. Various methods and apparatuses have been developed for the step of fixing a toner image to a transfer material such as paper, which is the final step of the above-described electrophotographic method. At present, the most common fixing method is a pressure heating method using a heat fixing roller.

In the pressure heating method using a heat fixing roller, a toner image surface on a transfer material is passed under pressure while contacting the surface of the heat fixing roller, whose surface is formed of a material having releasability from toner, under pressure. The fixing is carried out by exercising.

In this method, since the surface of the heat fixing roller and the toner image on the transfer material are brought into contact with each other under pressure, the thermal efficiency at the time of fusing the toner image on the transfer material is extremely good, and the fixing is quickly performed. And is very effective for high-speed electrophotographic copying machines.

In the copying step, there is a step of cleaning the toner remaining on the photoreceptor after transfer. However, in view of miniaturization, weight reduction and reliability of the apparatus, cleaning with a blade (blade cleaning) is used today. It has become common.

Further, with the prolonged life of the photoconductor, the reduction in the diameter of the photoconductor drum, and the speeding up of the system, characteristics required for the toner, such as anti-fusing property and anti-filming property, have become severe. I have. In particular, amorphous silicon photoconductors that have been put into practical use recently have extremely high durability,
In addition, OPC (organic photoreceptor) has been designed to have a long life,
Various performances required for the toner are becoming higher.

In the transfer step, a photoconductor (latent image carrier)
The upper toner is not completely transferred, and 10 to 20
About weight% remains on the photoreceptor. As described above, the toner (untransferred toner) remaining on the photoreceptor is collected in the cleaning step, and is discharged out of the system as a so-called waste toner, and cannot be used again.

In recent years, the demand for copying machines has increased, and the demand for machines having a large copy volume, that is, high-speed copying machines has been increasing. In such a high-speed copying machine, a large amount of waste toner is generated.

If all of the waste toner generated in these high-speed copiers and the like is treated as waste (waste plastic), there is a risk of causing environmental pollution.

For this reason, recently, a study of reusing the waste toner, that is, a study of reuse of the toner has been widely performed.

If the waste toner becomes reusable, the waste toner can be effectively used, the space in the copying machine can be simplified, and the copying machine can be downsized.

[0014]

However, in a non-contact one-component developing system, an untransferred toner remaining on a latent image carrier after development and transfer using a toner most suitable for such a heat fixing system. The following problems have been encountered when trying to establish a system in which the wastewater is recovered in a cleaning step and reused.

When the waste toner is used again in the developing step, there are adverse effects such as a reduction in the reflection image density of the obtained copy, an increase in ground fog and reversal fog, and the occurrence of toner scattering.

In order to investigate the cause of the decrease in the density of the reflected image when the waste toner is used in the reuse system, the present inventors collect the toner on the developing sleeve at any time from the start of copying and conduct various studies. Was performed.

As a result, before and after the above-mentioned adverse effects begin to appear,
A change was observed in the shape of the toner. That is, when the toner on the developer sleeve is observed at any time using a scanning electron microscope (SEM), some of the waste toner, which is an adverse toner, has a surface peeled or broken from inside. It was confirmed that there were many.

Further investigation of this phenomenon reveals that the untransferred toner (waste toner) on the photoreceptor is largely caused by mechanical shock applied when it is scraped off by a cleaning blade in a cleaning step. Was.

In particular, non-contact one-component development uses the conventional two-component development.
Since the physical properties of the toner greatly affect the image as compared with the component development, fogging and a decrease in image density are remarkable, and it has been difficult to simply use the waste toner for a reuse system.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and an object of the present invention is to suppress the damage of the developer at the time of collecting the developer remaining on the image carrier, and to reuse the developer. An object of the present invention is to provide an image forming apparatus capable of suppressing a decrease in image forming quality when used in a system.

[0021]

According to the present invention, there is provided an image forming apparatus provided with a cleaning means for removing a developer remaining on an image carrier carrying a developer. The cleaning unit is disposed so as to face the image carrier in a non-contact manner and collects a non-magnetic sleeve having a rotating magnetic pole forming unit therein, and a developer separated from the image carrier and moving on the surface of the non-magnetic sleeve. It is characterized by having a collection container to perform.

It is also preferable to provide an electric field applying means for applying an alternating electric field to the gap between the non-magnetic sleeve and the image carrier.

It is also preferable that the apparatus further comprises a supply unit for supplying the collected developer from a collection container of the cleaning unit to a developing unit for forming a developed image on the image carrier.

It is also preferable to provide a polishing means for polishing the surface of the image carrier.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a specific description will be given of a copying machine as an image forming apparatus according to an embodiment of the present invention.

(Embodiment 1) FIG. 1 is an explanatory view of the overall configuration of a copying machine as an image forming apparatus according to a first embodiment.
FIG. 2 is an explanatory diagram of a developer collecting configuration. Here, as an order of description, first, the overall configuration of the copying machine will be described, and then the configuration of the developer collecting device will be described.

(Overall Configuration) First, the overall configuration of the copying machine will be described. Referring to FIG.
And scans the illumination lamp 1b and the reflecting mirror 1c for scanning, and reflects the reflected light from the document onto the reflecting mirror 1b.
C and the reflection mirrors 1d, 1e, 1f, and a lens 1g having a focusing and zooming function, and irradiates the photosensitive drum 2 as an image carrier to form an electrostatic latent image.

The photosensitive drum 2 has a photosensitive layer on its surface, and can be rotated by a main motor 3 in the direction of the arrow in FIG. Around the photosensitive drum 2, a charging unit 4, a developing unit 5, a transfer unit 6, and a cleaning unit 7 for uniformly charging the surface of the photosensitive drum are arranged.

The surface of the rotating photosensitive drum 2 is uniformly charged by the charging means 4, an electrostatic latent image is formed by exposure from the document reading means 1, and the electrostatic latent image is formed by the developing means 5. To form a developed image.

The developing means 5 sends the developer in the developer accommodating portion 5a to a developing sleeve 5c having a fixed magnet built therein by a stirring and sending member 5b, rotates the developing sleeve 5c, and generates a triboelectric charge by a developing blade 5d. Forming the applied developer layer on the surface of the developing sleeve 5c;
The developer is conveyed to the developing section as the sleeve rotates.

In the developing section, the developer sleeve and the photosensitive drum 2 are kept in a non-contact state, so that the developer is transferred to the image area and collected from the non-image area.
An AC bias is applied so as to overlap the C bias.

As a result, the developer is transferred to the photosensitive drum 2 in accordance with the latent image, thereby forming a developed image and visualizing the image.

At this time, the AC bias varies depending on the distance between the sleeve drums.
It is selected from the range of 3KVpp. Then, the developed image is transferred to the recording medium 9 conveyed by the conveyance unit 8 by applying a voltage of the transfer unit 6.

The transfer means 6 has a transfer charger 6a and a separation charger 6b. The recording medium 9 conveyed by applying a voltage having a polarity opposite to that of the developing toner by the transfer charger 6a.
Then, a voltage is applied to the recording medium 9 after the image transfer by the separation charger 6b to separate the recording medium 9 from the photosensitive drum 2.

The developer remaining on the surface of the photosensitive drum 2 after transferring the magnetically developed image to the recording medium 9 is configured to be collected and removed by a non-contact cleaning means 7 described later.

On the other hand, the structure of the transport means 8 is such that upper and lower cassettes 8a ₁ and 8a ₂ are mounted below the apparatus main body, and the recording medium 9 accommodated in the respective cassettes 8a ₁ and 8a ₂ is picked up by pickup rollers 8b ₁ and 8a ₁ . 8b ₂ makes it possible to supply the registration rollers 8c one by one.

The recording medium 9 supplied from the cassettes 8a ₁ and 8a ₂ or the manual tray 8d is supplied to the registration roller pair 8 in synchronization with the image forming operation by the photosensitive drum 2.
c drives and conveys, and transfers the developed image at the position of the transfer means 6 as described above.

Then, the recording medium 8 after the image transfer is conveyed by a conveying belt 8e to a fixing unit 10 comprising a driving roller 10a and a heating press roller 10b having a built-in heater, and heat and pressure are applied by the fixing unit 10. The transfer image is fixed and discharged to the outside of the apparatus by a discharge roller pair 8f.

In the copying machine according to this embodiment, an automatic document feeder 11 is mounted above the document glass 1a so that a plurality of documents can be automatically separated and supplied.
Since the configuration of the automatic document feeder 11 is known, a detailed description thereof will be omitted.

(Developer Supply Apparatus) In the image forming apparatus according to the present embodiment, the developer collected by the cleaning means 7 is supplied to the developing means 5 for reuse.

The developer used in the present embodiment is a magnetic one-component developer, which is roughly divided into a magnetic toner containing magnetite, resin and the like, and an external additive.

The external additive is added to control the charge amount and the fluidity of the magnetic toner. When the amount of the external additive changes, the developing efficiency of the magnetic toner greatly changes. Usually, the amount of the external additive added to a new developer (hereinafter referred to as "new developer") is set so that the development efficiency is optimized.

However, once used in the developing process, the collected used developer (hereinafter referred to as “collected developer”) is
Even when the collected developer is collected without contact, the amount of the external additive added changes, and if the collected developer is reused as it is, the developing efficiency is poor and the image quality is deteriorated.

For this reason, in the present embodiment, it is possible for the developing means 5 to have a fixed mixing ratio of the recovered developer as the first developer and the new developer as the second developer. A developer supply device is provided. Hereinafter, the configuration will be described.

As shown in FIGS. 2 and 3, the collected developer T1 collected by the cleaning means 7 is conveyed by the conveying screw 12 from the back side to the front side of the paper, and is stored in the first container for storing the collected developer T1. It is supplied to the unit 15.

The recovered developer T1 in the storage section 15 and the new developer T0 in the second storage section 16 are supplied to the first shutter 1 respectively.
7. The developing means 5 disposed below the first and second storage portions 15 and 16 by the opening operation of the second shutter 18
The developer is supplied to the developer accommodating section 5a, and is uniformly mixed by the stirring and feeding member 5b to be used in the developing process.

FIG. 4 is a perspective view showing the inside of the first storage section 15. After the recovered developer T 1 is transported through the transport pipe 13 to the first storage section 15 by the transport screw 14, subsequently, by the transport screw 19. Arrow a along the housing wall
Conveyed in the direction.

Along the conveying screw 19, on the wall of the storage section,
A gutter portion 15a is provided, and the collected developer falls from an opening 15b provided in the gutter portion 15a and is deposited on a lower portion of the housing portion 15 while being transported on the gutter portion 15a.

The size of the opening 15b is
9 is smaller on the front side in the transport direction and is gradually larger toward the rear side. For this reason, the amount of the collected developer that falls on the near side is small, and on the back side, the collected developer that has fallen and decreased on the near side is dropped, and as a result, the collected developer along the container wall is reduced. It falls evenly.

Thus, the recovered developer and the new developer can be uniformly mixed. Then, the toner is supplied to the developing unit 5 by the opening operation of the shutter 17 deposited on the lower part of the storage unit 15.

The shutter 17 is, as shown in FIG.
7a, and is rotatably supported by the shutter 17a.
Is in the position P1, the opening 15c provided at the lower part of the housing portion 15 is closed.

Then, the motor 17 is driven to drive the shutter 17.
Is rotated to the position P2 to open the opening 15c. Both ends of the shutter 17 are sealed with seal members 17b such as rubber and sponge to prevent toner leakage at the time of opening.

The second housing 16 is also provided with the first housing 1.
5, and a second shutter 18 is provided which is rotated by driving of the stepping motor M2 and opens and closes a second opening 16a formed in a lower portion of the second housing portion 16.

Here, the cleaning means will be described in detail. FIG. 5 shows the cleaning means of the present invention.

The cleaning means 7 rotates the multi-pole magnet 7d of the recovery sleeve 7c as a non-magnetic sleeve containing a rotating multi-pole magnet 7d as a rotating magnetic pole forming means in the direction indicated by an arrow A, thereby forming a developer. In the collecting section (a gap between the collecting sleeve 7c and the photosensitive drum 2), the photosensitive drum 2
The developer separated and collected from the collecting sleeve 7c is conveyed on the surface of the collecting sleeve 7c in the direction of the arrow B with the rotation of the multipolar magnet 7d (this conveyance is performed on the next pole side where the ears of the developer approach. (Utilizing the phenomenon of falling down), and finally falls down by the action of the developer damping portion 7b and is conveyed to the collected developer accommodating portion 7a as a collecting container.

The collection sleeve 7c itself may not be rotated and may be in a fixed state. Alternatively, the rotation of the multipole magnet 7d does not hinder the movement to the collection developer accommodating portion 7a.
It is also possible to rotate in the same direction.

In the developing and collecting section, the collecting sleeve 7c and the photosensitive drum 2 are kept out of contact with each other so that the developer is collected from the photosensitive drum 2 by the action of the magnetic force of the rotating multipolar magnet 7d and the electric field. An AC bias is applied to the collection sleeve 7c so as to overlap the DC bias.

As a result, the developer is transferred by transferring the developer from the photosensitive drum 2 onto the collecting sleeve 7c. The AC bias at this time varies depending on the distance between the sleeve drums, but is generally 1 to 3 KHz, 1 to 3 KHz.
A rectangular wave in the range of Vpp is selected.

As described above, the recovered developer is mixed with a new developer at an appropriate mixing ratio from the screw 12 as a starting point and used for development.

The feature of the present invention is that there is no place where the developer is rubbed at all. For this reason, there is no stress applied to the conventional developer at all, and embedding of external additives and shape change of the toner are minimized. No problem of fogging or reduction in density occurred when using.

Further, by utilizing both the action of the alternating electric field and the action of the alternating magnetic field for collecting the developer, a stable cleaning condition can be obtained.

(Embodiment 2) In the above-described first embodiment, almost 100% of the developer is collected. However, since the photosensitive drum 2 is damaged by a charger or the like, the surface layer is removed. Polishing slightly gives a stable image over a long period of time.

The embodiment shown in FIG. 6 has the same configuration as that of the first embodiment except that a polishing blade 7A is disposed as a polishing means on the downstream side of the cleaning means 7. Since almost 100% of the toner is recovered by the cleaning means 7, there is almost no toner remaining in the polishing blade 7A, and the drum surface is polished very little by the polishing blade 7Ac. Then, a stable image can be obtained for a long period of time without collecting the toner in the polishing blade section 7A.

(Embodiment 3) In the above-described first embodiment, a 50% duty rectangular wave shown in FIG. 7A is used. For example, when a toner having a negative polarity is used, As the AC applied to the collection sleeve, a bias provided with a duty may be applied so that the time of positive application is shortened and the electric field intensity is increased instead.

In this embodiment, 38 shown in FIG.
When a rectangular wave having a% duty is used, PP (PP: peak-to-peak (peak t
It is possible to completely recover the toner even if the value of “peak”) is reduced, and it is possible to suppress the power consumption.

As shown at 20 in FIG. 6, after the transfer,
Before the cleaning, it is more preferable to provide a charger which is an auxiliary cleaning operation for negatively charging the toner and the drum.

[0067]

According to the present invention described above, the developer remaining on the image carrier can be collected without giving stress or damage to the developer.

Therefore, even in a system in which the collected developer is reused, a change in the characteristics of the developer is suppressed, and a high-quality image that is stable over a long period of time can be formed.

By providing an electric field applying means for applying an alternating electric field to the gap between the non-magnetic sleeve and the image carrier, the developer can be collected more efficiently.

By providing the polishing means, the surface state of the image carrier can be maintained in a good condition.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of an overall configuration of a copying machine according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a configuration for collecting a developer.

FIG. 3 is an explanatory diagram of a shutter for adjusting a developer supply amount.

FIG. 4 is an explanatory perspective view of a supply configuration of a collected developer.

FIG. 5 is an explanatory diagram of a developer cleaning unit.

FIG. 6 is an explanatory diagram of another embodiment of a developer cleaning unit.

FIG. 7 is an explanatory diagram of a bias applied to a developer cleaning unit.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Original reading means 1a Original table glass 1b Illumination lamp 1c-1f Reflection mirror 1g Lens 2 Photoreceptor drum (image carrier) 3 Main motor 4 Charging means 5 Developing means 5a Developer accommodating part 5b Stirring feeding member 5c Developing sleeve 5d Developing blade 6 transfer means 6a transfer charger 6b separation charger 7 cleaning unit 7a recovered developer storing portion (collecting container) 7b developer stop part 7c recovered sleeve 7d multipolar magnet (rotating magnetic pole forming means) 8 conveying means 8a _1, 8a ₂ top / bottom cassette 8b _1, 8b ₂ pickup roller 8c pair of registration rollers 8d manual feed tray 8e conveyor belt 8f pair of discharge rollers 9 recording medium 10 fixing means 10a driven roller 10b heated pressure roller 11 automatic document feeder 12 conveying screw 13 conveyor Pipe 14 transport screw 5 First storage section 15a Gutter section 15b Opening 15c Opening 16 Second storage section 16a Second opening 17 First shutter 17a Shaft 17b Seal member 18 Second shutter 19 Transport screw 20 Cleaning auxiliary charger T0 New developer T1 Collection Developer

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yuji Mikituri 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Makoto Shinbayashi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Incorporated (72) Inventor Takaaki Kayaki 3-30-2 Shimomaruko, Ota-ku, Tokyo F-term in Canon Inc. (reference) 2H034 AA05 BA00 BE04 BE06 BE07 BE07 BE09 CA04 CB01 2H035 BA05 2H077 AA12 AA18 AA37 AB14 AB15 AB18 AD05 AD13 AD35 AE01 EA13

Claims (4)

[Claims] 1. An image forming apparatus comprising: a cleaning unit for removing a developer remaining on an image carrier that carries a developer, wherein the cleaning unit is disposed so as to be in non-contact with the image carrier, and rotates. An image forming apparatus comprising: a non-magnetic sleeve having a magnetic pole forming means therein; and a collection container for collecting a developer that is separated from the image carrier and moves on the surface of the non-magnetic sleeve. 2. The image forming apparatus according to claim 1, further comprising an electric field applying unit that applies an alternating electric field to a gap between the nonmagnetic sleeve and the image carrier. 3. The image forming apparatus according to claim 1, further comprising a supply unit that supplies the collected developer from a collection container of the cleaning unit to a developing unit that forms a developed image on the image carrier. Image forming apparatus. 4. The apparatus according to claim 1, further comprising a polishing means for polishing a surface of said image carrier.
Item 10. The image forming apparatus according to item 1.