JP2000206736A - Image forming method and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain developing ability by lowering electrostatic repulsion due to lubricant on an image carrier at the time of developing with a developer by making at least one type of additive among additives added to the developer to be of the apposite polarity to electrified polarity of the lubricant existing on the surface of the image carrier. SOLUTION: In this image forming device, an electrostatic latent image is formed by carrying out optical writing on the image carrier 1 after the image carrier 1 that is set with a coefficient of friction μ within a range of 0.1<=μ<=0.4 is uniformly electrified beforehand. This image carrier 1 where the electrostatic latent image is formed is abutted to a developer carrier 3 carrying the developer to develop the electrostatic latent image on the image carrier 1 into a toner image. The toner image on this image carrier 1 is transferred to transfer paper fed from a paper feeding device, transfer material such as OHP, by a transfer means and fixed to the transfer material by a fixing means. In this case, at least one additive of the additives added to the developer is made to be of the opposite polarity of the electrifying polarity of the lubricant existing on the surface of the image carrier 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an image forming method and an image forming apparatus.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus, a photosensitive member as an image carrier is uniformly charged in advance by a charging means, and then the photosensitive member is optically written by an optical writing means to form an electrostatic latent image. Then, the photoreceptor on which the electrostatic latent image is formed is brought into contact with a developer carrying member comprising a developing roller carrying a toner as a one-component developer in a developing device to develop the electrostatic latent image on the photoreceptor. There is known a method in which a toner image is transferred to a transfer material such as transfer paper or OHP by a transfer unit and fixed by a fixing device.

Japanese Patent Application Laid-Open No. 8-254933 discloses a lubricant applying means for applying a lubricant on an image carrier, and a toner density detecting means for detecting a toner density adhering to the outside of an image area on the image carrier. An electrophotographic apparatus comprising: a control unit that controls the lubricant applying unit based on a detection result of the toner density detecting unit (controls the approach / separation and rotation thereof).

Japanese Patent Application Laid-Open No. Hei 9-73229 discloses a developing method in which a one-component developer is used and a developing roller having a toner layer formed thereon is brought into contact with a photoreceptor to perform development. The ratio of the linear velocity of the developing roller to the photosensitive member is increased, and the range is set to 1.2 to 3.0 times, particularly 1.5 to 3.0 times.
A method recommending 2.5 times is described.

Japanese Patent Application Laid-Open No. 9-274364 discloses a non-magnetic toner to which an external additive for imparting fluidity is added, which aims at preventing the external additive from adhering to the developer carrier. A developing device that carries the developer including the developer on the developer carrier and transports the developer to a development area corresponding to the electrostatic image carrier;
The member forming the developer carrier and the external additive may be formed of a member exhibiting a triboelectric charging property substantially equivalent to the non-magnetic toner, or the triboelectric charging property of the non-magnetic toner to the external additive may be improved. The developing device is characterized in that the developing device has a higher triboelectric charge imparting property of the developer carrier to an external additive.

Japanese Patent Application Laid-Open No. Hei 6-332215 discloses an image forming method in which a toner is formed on an image carrier and this toner image is transferred to a transfer material.
This is the description of the image forming method, wherein the image carrier has a transferability improving layer on the surface.

[0007]

In the above-mentioned prior art, since the photosensitive member and the developing roller are in contact with each other via the toner layer, a strong electrostatic force acts thereon. In general, a developer is externally added with one to three kinds of additives to enhance fluidity and also aim at charging stability. However, since the photoconductor and the developing roller are in contact with each other via the toner layer, the toner is transferred to the developing roller in a region where the friction coefficient of the photoconductor surface is relatively low (0.1 to 0.2). In some cases, the scavenging force acts strongly, and the developing ability is reduced particularly in a low density region, resulting in an image having a low density. In addition, when the development potential is increased by increasing the development potential between the photosensitive member and the development roller, the margin for background contamination tends to decrease, and the overall image quality may be reduced.

In the developing method described in Japanese Patent Application Laid-Open No. 9-73229, the ratio of the linear velocity of the developing roller to the photosensitive member is increased, and the range is set to 1.2 to 3.0 times.
Although 2.5 times is recommended, if the linear velocity ratio of the developing roller to the photosensitive member exceeds 1.2 times, an abnormal image such as the toner near the rear end is likely to occur. Further, in the image forming method described in JP-A-6-332215, the degree of aggregation of the toner is 30% or more, and the image carrier has a transferability improving layer on the surface, but the development efficiency is reduced by the aggregation of the toner. .

An object of the present invention is to provide an image forming method in which an additive of a developer during development can reduce electrostatic repulsion due to a lubricant on an image-carrying state and maintain a developing ability. Aim. Another object of the present invention is to provide an image forming method in which an additive of a developer during development can reduce electrostatic repulsion due to a lubricant on an image bearing state and maintain a developing ability. . A third object of the present invention is to provide an image forming method capable of reducing background contamination.

A fourth object of the present invention is to provide an image forming method capable of increasing the amount of toner developed on an image carrier. The invention according to claim 5 is
It is an object of the present invention to provide an image forming method in which an additive of a developer during development can reduce electrostatic repulsion due to a lubricant on an image carrying state and maintain a developing ability. It is another object of the present invention to provide an image forming apparatus capable of maintaining a developing ability by reducing an electrostatic repulsion caused by a lubricant in an image carrying state by an additive of a developer during development. .

Another object of the present invention is to provide an image forming apparatus capable of improving the charging characteristics and supply properties of the developer. An object of the invention according to claim 8 is to provide an image forming apparatus capable of improving the charging characteristics and supply properties of the developer. It is another object of the present invention to provide an image forming apparatus capable of sufficiently coping with a demand for high resolution and a reduction in toner particle size.

Another object of the present invention is to provide an image forming apparatus capable of transporting a developer without being buried in the surface of a developer carrier. Claim 1
It is an object of the present invention to provide an image forming apparatus capable of stabilizing the aging quality of a developer carrier and improving developer charging characteristics.

An object of the present invention is to provide an image forming apparatus capable of stabilizing the aging quality of a developer carrying member and having excellent releasability of the developer carrying member. And A further object of the present invention is to provide an image forming apparatus which can solve the problem that the coat layer of the developer carrying member is easily broken.

It is another object of the present invention to provide an image forming apparatus capable of reducing the size of a developing unit and suppressing occurrence of an abnormal image due to vibration. A further object of the present invention is to provide an image forming apparatus capable of suppressing the influence of the contact pressure of the developer regulating member on the developer carrier on the developing ability.

Another object of the present invention is to provide an image forming apparatus capable of reducing uneven contact force between a developer carrier and an image carrier. It is another object of the present invention to provide an image forming apparatus capable of reducing electrostatic repulsion due to a lubricant on an image carrier caused by a developer additive during development and maintaining a developing ability. . It is another object of the present invention to provide an image forming apparatus capable of reducing non-electrostatic adhesion of an image carrier to toner and reducing background contamination.

According to a nineteenth aspect of the present invention, the toner developed on the image carrier is not scraped off by the developer layer on the developer carrier, and the amount of toner developed on the image carrier is increased. It is an object of the present invention to provide an image forming apparatus capable of performing the following. A further object of the present invention is to provide an image forming apparatus capable of uniformly developing even a low contrast image. It is an object of the present invention to provide an image forming apparatus capable of reducing electrostatic repulsion due to a lubricant on an image carrier caused by a developer additive during development and maintaining a developing ability. .

[0017]

In order to achieve the above object, the invention according to claim 1 provides a friction coefficient μ of 0.1 ≦ μ ≦
After the image carrier set in the range of 0.4 is uniformly charged in advance, optical writing is performed on the image carrier to form an electrostatic latent image, and the image carrier on which the electrostatic latent image is formed is removed. An image forming method in which an electrostatic latent image on the image carrier is developed into a toner image by being brought into contact with a developer carrier carrying a developer, and the toner image is transferred to a transfer material; At least one of the additives externally added to the developer has a polarity opposite to the charge polarity of the lubricant present on the surface of the image bearing member.

According to a second aspect of the present invention, the friction coefficient μ is set to 0.1.
After the image carrier set in the range of 1 ≦ μ ≦ 0.4 was uniformly charged in advance, optical writing was performed on the image carrier to form an electrostatic latent image, and the electrostatic latent image was formed. The image carrier is
An image forming method, wherein an electrostatic latent image on the image carrier is developed into a toner image by being brought into contact with a developer carrier carrying a developer, and the toner image is transferred to a transfer material. At least one of the additives externally added to the agent has a polarity opposite to the charging polarity of the lubricant present on the surface of the image carrier, and the amount of the additive is converted into a surface area ratio. It is characterized by being at least twice.

According to a third aspect of the present invention, in the image forming method of the first aspect, the developer has a particle diameter of 4 μm to 6 μm.
m.

According to a fourth aspect of the present invention, the friction coefficient μ is set to 0.1.
After the image carrier set in the range of 1 ≦ μ ≦ 0.4 was uniformly charged in advance, optical writing was performed on the image carrier to form an electrostatic latent image, and the electrostatic latent image was formed. The image carrier is
An image forming method, wherein an electrostatic latent image on the image carrier is developed into a toner image by being brought into contact with a developer carrier carrying a developer, and the toner image is transferred to a transfer material. The coagulation degree of the agent is set to 15% or more.

The invention according to claim 5 is the invention according to claims 1, 2, and 3
5. The image forming method according to claim 4, wherein the image carrier is made of a photoconductor, and the developer carrier is made of a developing roller.

According to a sixth aspect of the present invention, the friction coefficient μ is set to 0.1.
Having an image carrier set in the range of 1 ≦ μ ≦ 0.4, and after uniformly charging the image carrier in advance, forming an electrostatic latent image by performing optical writing on the image carrier; The image carrier on which the electrostatic latent image is formed is brought into contact with a developer carrier carrying a developer to develop the electrostatic latent image on the image carrier into a toner image, and the toner image is transferred. An image forming apparatus for transferring to a material, wherein at least one kind of additive externally added to the developer has a polarity opposite to a charge polarity of a lubricant present on a surface of the image carrier. It is characterized by having.

According to a seventh aspect of the present invention, in the image forming apparatus according to the sixth aspect, the developer carrier is rotated in the same direction as the developer carrier and in the opposite direction by contacting the developer carrier. A developer supply member for supplying developer to the
The linear velocity ratio of the developer supply member to the developer carrier is set to 0.5 to 1.5, and the amount of one of the developer supply member and the developer carrier to the other is 0.5 m.
m to 1.5 mm.

According to an eighth aspect of the present invention, in the image forming apparatus of the sixth aspect, the developer supply member comprises a supply roller.

According to a ninth aspect of the present invention, in the image forming apparatus of the sixth aspect, the developer comprises a toner,
The average particle size is 3 μm to 12 μm.

According to a tenth aspect of the present invention, in the image forming apparatus according to the sixth aspect, the surface roughness of the developer carrier is set to 13% to 80% with respect to the toner particle size of the developer. It is a feature.

According to an eleventh aspect of the present invention, in the image forming apparatus of the sixth aspect, the surface of the developer carrier is coated with a silicon-based coating material.

According to a twelfth aspect of the present invention, in the image forming apparatus of the sixth aspect, the surface of the developer carrier is coated with a Teflon-based coating material.

According to a thirteenth aspect of the present invention, in the image forming apparatus of the sixth aspect, the thickness of the coating layer covering the surface of the developer carrier is set to 5 μm to 50 μm.

According to a fourteenth aspect of the present invention, in the image forming apparatus according to the sixth aspect, a developer regulating member for regulating the developer carried by the developer carrying member, and a holder for holding the developer regulating member are provided. And the length from the holder to the free end of the developer regulating member is set to 10 mm to 15 mm.

According to a fifteenth aspect of the present invention, in the image forming apparatus according to the sixth aspect, the image forming apparatus further includes a developer regulating member for regulating the developer carried on the developer carrying member, Contact pressure against the agent carrier is 5 g · f / c
m to 250 g · f / cm.

According to a sixteenth aspect of the present invention, in the image forming apparatus of the sixth aspect, a plurality of pressing means for bringing the developer carrier and the image carrier into contact with each other are provided. .

According to a seventeenth aspect of the present invention, there is provided an image bearing member having a friction coefficient μ set within a range of 0.1 ≦ μ ≦ 0.4,
After the image carrier is uniformly charged in advance, optical writing is performed on the image carrier to form an electrostatic latent image, and the image carrier on which the electrostatic latent image is formed is developed with a developer loaded thereon. An image forming apparatus that develops an electrostatic latent image on the image carrier into a toner image by bringing the toner image into contact with a developer carrier, and transfers the toner image to a transfer material; At least one of the additives has a polarity opposite to the charging polarity of the lubricant present on the surface of the image bearing member, and the amount of the additive is at least twice as much as the surface area ratio. It is characterized by the following.

According to an eighteenth aspect of the present invention, in the image forming apparatus of the sixth aspect, the developer has a particle size of 4 μm to 6 μm.
μm.

According to a nineteenth aspect of the present invention, there is provided an image bearing member having a friction coefficient μ set within a range of 0.1 ≦ μ ≦ 0.4,
After the image carrier is uniformly charged in advance, optical writing is performed on the image carrier to form an electrostatic latent image, and the image carrier on which the electrostatic latent image is formed is developed with a developer loaded thereon. An image forming apparatus that develops an electrostatic latent image on the image carrier by bringing the developer into contact with a developer carrier to form a toner image, and transfers the toner image to a transfer material; % Or more.

According to a twentieth aspect of the present invention, in the image forming apparatus according to the nineteenth aspect, the friction coefficient μ of the image carrier is set in a range of 0.1 <μ <0.2. It is.

The invention according to claim 21 is the invention according to claims 6 and 2.
0, wherein the image carrier is formed of a photoconductor, and the developer carrier is formed of a developing roller.

[0038]

FIG. 1 schematically shows a part of an embodiment of the present invention. The image forming apparatus of this embodiment is an image forming apparatus using an electrophotographic method, and uses a photosensitive member as an image carrier, and the photosensitive member is, for example, a drum-shaped photosensitive member 1. As the photoconductor 1, a belt-shaped photoconductor may be used. The present invention can be applied to an image forming apparatus for forming and developing an electrostatic latent image on an image carrier by a method other than the electrophotographic method.

The photoreceptor 1 is rotated and driven by a driving unit during image formation, is uniformly charged to a specified surface potential by a charging unit, and is optically written by an optical writing unit to form an electrostatic latent image. As the charging unit, a known unit such as a corona charger or a charging roller is used. The optical writing means converts an image signal into an optical signal and
A known device such as a laser light writing device for irradiating and exposing a document, a slit exposure device for irradiating a document with an illuminating device, irradiating the photoreceptor 1 with reflected light thereof, exposing the document, and scanning the document is used. It is possible.

The electrostatic latent image on the photoreceptor 1 is developed with a developer by a developing device 2 to form a toner image. The toner image on the photoreceptor 1 is transferred paper,
Then, the image is transferred to a transfer material such as by a transfer means, and is fixed to the transfer material by a known fixing device. As the transfer unit, a known unit such as a corona charger, a transfer roller, or a transfer / conveyance device is used. The toner image on the photoreceptor 1 is temporarily transferred to an intermediate transfer member by a transfer unit, and then transferred to a transfer material such as a transfer sheet fed from a known sheet feeding device or an OHP by the transfer unit. Is also good. After transferring the toner image to the transfer material, the photoreceptor 1 is cleaned by a cleaning device, becomes reusable, and is used repeatedly.

The developing device 2 has a developer carrier 3, a developer regulating member 4, a developer supply member 5, a developer stirring member 6, and a developing container 7, and the developer is stored in the developing container 7. You.
The developer carrier 3 is, for example, a developing roller, and the developer regulating member 4 is, for example, a developer regulating blade.
For example, a developer supply roller is used as the developer supply member 5, and an agitator is used as the developer stirring member 6, for example.
As the developer, for example, a toner as a one-component developer is used. The developing roller 3, the developer supply roller 5, and the agitator 6 are rotationally driven by a driving unit at a predetermined timing, and a developing bias voltage is applied to the developing roller 3 from a power supply device.

The toner in the developing container 7 is stirred by the agitator 6 and mechanically supplied to the developer supply roller 5, and is supplied to the developing roller 3 by the developer supply roller 5. The developer supply roller 5 is made of foamed polyurethane or the like, has flexibility, and has a structure in which cells having a diameter of 50 [μm] to 500 [μm] can easily hold toner. Further, the developer supply roller 5 has a hardness of 10 ° JIS A ~
30 ° JIS A, relatively low hardness, developing roller 3
Can be uniformly contacted.

When the developer supply roller 5 rotates in the same direction as the developing roller 3 (counter direction at the contact portion),
The linear velocity of the developer supply roller 5 is optimally such that the linear velocity ratio with respect to the linear velocity of the developing roller 3 is 0.5 to 1.5. Note that the developer supply roller 5 may be rotated in a direction opposite to that of the developing roller 3. In this embodiment, the developer supply roller 5 rotates in the same direction as the development roller 3, and the linear velocity ratio of the developer supply roller 5 to the development roller 3 is 0.9.
It is. The biting amount of the developer supply roller 5 into the developing roller 3 is 0.5 [mm] to 1.5 [mm]. Since this condition greatly affects the charging characteristics and supply properties of the toner, it is necessary and possible to set an optimum condition in a wider range depending on the combination.

The developing roller 3 of the developer supply roller 5
The amount of bite to the end also depends on the characteristics of the motor and the gear head of the drive unit that drives the developing roller 3, so it is necessary to consider all of them.
In this embodiment, the effective width of the developing device 2 is 240 [mm].
(A4 vertical size) 1.5 torque required
[Kg · fcm] to 2.5 [kg · fcm].

The above toner is prepared by adding a charge controlling agent (CC) to a resin such as polyester, polyol, styrene acryl, or the like.
A), a colorant is mixed, and substances such as silica and titanium oxide are externally added around the mixture. Examples of the coloring agent include carbon black, phthalocyanine blue, quinacridone, and carmine. The operation of this embodiment will be described later with respect to the charge amount, polarity and abundance ratio of the additive externally added to the toner, and the toner particle size.

The two types of toners A and B (the current toner A and the toner B of the present embodiment) are prepared by dispersing and mixing a CCA, a colorant, and, in some cases, a wax with a polyester resin. Various additives are externally added. The particle size of the toners A and B is 0.1 [μm] to 1.5.
[Μm]. In this embodiment, the average particle diameter of the toner is in the range of 3 [μm] to 12 [μm], for example, 7.5 [μm]. It is possible.

The developing roller 3 is preferably made of a rubber material, has a diameter of 10 [mm] to 30 [mm], and has a surface roughened to have a surface roughness of 1 [μm] RZ to 4 [μm] RZ. It is. This value is 13% to 80% of the toner particle size, and the toner is conveyed without being buried in the surface of the developing roller 3. Here, silicone, butadiene, NBR,
Hydrin, EPDM and the like can be mentioned. Further, it is preferable to coat the surface of the developing roller 3 with a coating material in order to stabilize the quality with time.

As the coating material, a silicon-based coating material and a Teflon-based coating material are particularly good. The former has good toner charging, and the latter has excellent releasability. Also,
The coating material may appropriately include a conductive material such as carbon black in order to obtain conductivity. The thickness of the coat layer is preferably in the range of 5 μm to 50 μm,
If it exceeds the range, problems such as cracking are likely to occur.
In this embodiment, the hardness of the developing roller 3 is set to be low, and the hardness of the photoconductor 1 is set to be high.

The toner existing on or in the developer supply roller 5 (the toner used in the present embodiment obtains a negative charge) is rotated by the rotation so that the toner rotates in opposite directions at the contact point. By being sandwiched between the roller 3 and the developer supply roller 5, a negative charge is obtained by a triboelectric charging effect and is held by the developing roller 3 by electrostatic force. Will be held. However, the toner layer on the developing roller 3 at this time is not uniform but excessive (1 [mg / cm ² ]).

Further, by bringing the developer regulating blade 4 into contact with the developing roller 3, a thin toner layer having a uniform layer thickness is formed on the developing roller 3. Developer regulating blade 4
Is a so-called belly contact, in which the front end faces downstream with respect to the rotation direction of the developing roller 3 and the central portion of the developer regulating blade 4 contacts the developing roller 3. Of course, the developer regulating blade 4 can be set in the opposite direction, and it is also possible to realize edge contact.

The developer regulating blade 4 is made of SUS
304 or other metal with a thickness of 0.1 [mm] to 0.2 [m
m], a rubber material such as polyurethane rubber having a thickness of 1 [mm] to 2 [mm], a silicone resin, and a fluorine-based resin having an opposite charging characteristic (eg, ETFE, PTF).
E, PVdF) and other resin materials having relatively high hardness can be used. Further, since the developer regulating blade 4 can be reduced in resistance by mixing carbon black or the like other than metal, an electric field can be formed between the developer regulating blade 4 and the developing roller by connecting a bias power supply.

The developer regulating blade 4 is fixed to the developing container 7 by the holder 8, and the length from the holder 8 to the free end is preferably 10 [mm] to 15 [mm]. If the length exceeds the upper limit of the range, the size of the developing unit 2 increases, and the size of the developing unit 2 cannot be reduced. If the length falls below the lower limit of the length, vibration occurs when the developing unit 2 comes into contact with the surface of the developing roller 3. As a result, an abnormal image such as stepwise unevenness in the horizontal direction easily occurs on the image.

The contact pressure of the developer regulating blade 4 against the developing roller 3 is 5 [g · f / cm] to 250 [g · f / c].
m], the effect on the developing ability is that if the contact pressure of the developer regulating blade 4 against the developing roller 3 exceeds the upper limit of the contact pressure range, the amount of toner adhering to the developing roller 3 decreases and Since the toner charge amount increases too much, the development amount decreases and the image density decreases. Developer regulating blade 4
When the contact pressure on the developing roller 3 falls below the lower limit of the contact pressure range, a thin toner layer may not be uniformly formed on the developing roller 3 and a lump of toner may pass through the developer regulating blade 4. The image quality is significantly reduced. In this embodiment, for example, the developing roller 3 has a hardness of 3 according to JIS A.
A SUS plate having a thickness of 0.1 [mm] is used as the developer regulating blade 4, and the contact pressure of the developer regulating blade 4 against the developing roller 3 is 60 [g · f / c].
m]. At this time, the target toner adhesion amount on the developing roller 3 was obtained.

The contact angle of the developer regulating blade 4 with respect to the developing roller 3 is 10 ° to 45 ° with respect to the tangent line of the developing roller 3 in a direction in which the tip of the developer regulating blade 4 faces the downstream side in the rotation direction of the developing roller 3. ° is good. An unnecessary portion of the toner layer on the developing roller 3 for forming a thin toner layer sandwiched between the developer regulating blade 4 and the developing roller 3 is peeled off from the developing roller 3 by the developer regulating blade 4 so that the toner layer on the developing roller 3 has a target range. 0.4 [mg / cm ² ] to 0.8 per unit area
It is formed into a thin toner layer having a uniform thickness of [mg / cm ² ]. The charge amount of the toner at this time is finally in the range of −5 [μC / g] to −30 [μC / g] in the present embodiment, and the latent image on the photoconductor 1 is transferred to the developing roller 3 via the toner layer.
, And the image is developed.

As the photoreceptor 1, inorganic and organic photoreceptors are used, and the surface friction coefficient is maintained in the range of 0.1 to 0.4. A method for maintaining this state is disclosed in JP-A-4-3729.
No. 81, “When a toner having a volume average particle diameter of 4 to 10 μm is used, a substance that reduces the friction coefficient of the photoconductor is supplied onto the photoconductor. The member carrying the agent may be brought into contact with the photoconductor at all times or at regular intervals. For example, a known method may be used. When the lubricant is applied by the lubricant applying device, the friction coefficient of the surface of the photoreceptor 1 is 0.1 to 0.1.
4 is maintained.

Here, the coefficient of friction of the surface of the photosensitive member 1 was determined by the Euler method as shown in FIG. That is, TY
A sheet of PE 6200 A4T (manufactured by Ricoh Co., Ltd.) was cut into a sheet 9 of 297 mm × 30 mm, and yarns 10 and 11 were attached to both ends of the sheet 9 to prepare a measurement sheet. The measuring paper strip 9 is placed on the photoreceptor 1 and 0.98 N (1
Then, the other thread 11 is pulled by a digital force gauge 13 and the value of the gauge 13 when the paper 9 starts to move is read. The value of the gauge 13 at this time is F
(N), the friction coefficient μ of the surface of the photoconductor 1 is μ =
[Ln (F / 0.98)] / (π / 2).

No lubricant or the like is applied to the surface of the photoreceptor 1
The value measured by the above method for the coefficient of friction μ of the surface of the photoreceptor 1 in the untreated state is 0.4 to 0.6, and tends to increase with time. On the other hand, the measured value of the friction coefficient μ of the surface of the photoreceptor 1 coated with the lubricant by the above method is as follows.
It was in the range of 0.1-0.4.

The photosensitive member 1 and the developing roller 3 come into contact with each other via a toner layer on the developing roller 3. Photoconductor 1 and developing roller 3
It is preferable that the photosensitive member 1 and the developing roller 3 are brought into contact with each other by a spring as a pressing means. In particular, the photosensitive member 1 and the developing roller 3 are brought into contact with a plurality of springs. It is possible to reduce contact unevenness between the photosensitive member 1 and the developing roller 3. As this spring, a coil spring, a leaf spring, or the like can be used. Assuming that the developing roller 3 of this embodiment has a hardness of 30 ° JIS-A, the developing roller 3
Is 2 [g · f / cm] to 10
The range of [g · f / cm] is preferable. Also, the greater the number of pressing means, the better the contact unevenness between the photosensitive member 1 and the developing roller 3 can be reduced, which is good.

An experimental result showing the effect of the contact pressure between the photosensitive member 1 and the developing roller 3 on the development characteristics (solid uniformity, background contamination) will be described below. If the contact pressure between the photoreceptor 1 and the developing roller 3 falls below the lower limit of the appropriate range, the developing ability becomes non-uniform, and a sufficient developing amount cannot be obtained. Photoconductor 1
When the contact pressure between the developing roller 3 and the developing roller 3 exceeds the upper limit of the appropriate range, the scavenging force of the developing roller 3 increases,
When the toner layer on the developing roller 3 is compressed, the toner on the developing roller 3 aggregates.
The toner once developed (adhered) thereon is scraped off by the toner layer on the developing roller 3 or remains on the developing roller 3 while being aggregated, thereby causing an abnormal image such as unevenness of a solid image. It will be easier. Photoconductor 1 and developing roller 3
As long as the contact pressure is within an appropriate range, a high-density uniform image can be obtained.

In this embodiment, the diameter of the photosensitive member 1 is set to 50
[Mm], and the developing step is performed with the diameter of the developing roller 3 set to 16 [mm]. The toner image formed on the photoconductor 1 is
Thereafter, an image is completed through a transfer step and a fixing step. Here, the contribution of the toner (the contribution of the additive) in this embodiment will be described in detail.

The photosensitive member 1 has a surface friction coefficient μ in the range of 0.1.
1 <μ <0.4. The photoreceptor 1 is made to contain a material such as zinc stearate or a fluorine-based material (a resin material such as PTFE) in advance, or is supplied to the surface from outside using a brush, a blade, or the like without containing the material. Of these, the second-listed fluorine-based materials have recently been known for their releasability, (environment, aging).
It is superior in stability to conventional materials and is widely used. In the triboelectric series, fluorine alone is likely to be "-charged" upon contact with the other party and "+ charged" on the contacted party.

In this embodiment, the negative and positive development of the electrostatic latent image on the photoreceptor 1 is performed by the developing unit 2 with the polarity of the charged potential of the photoreceptor 1 set to be negative. Therefore, a toner having a negative charge polarity in a state in which an additive is mixed is used. Basically, the charging characteristics of the toner are mostly determined by the base resin of the toner and the charge control agent (CCA) mixed therein, but are also slightly affected by additives externally added to the toner. The original function of this additive is to reduce the degree of aggregation of the toner to prevent the toner from forming a lump, and to "unfold" as much as possible to obtain uniform development and transfer properties.
Additives may also have a charging characteristic that inhibits the toner charging characteristics described above, so they do not contribute significantly to development characteristics.However, when the latent image on the photoreceptor has a low potential and the development electric field is relatively weak, The effect is likely to appear.

In the contact developing system used in this embodiment, since the developing roller 3 is in contact with the photosensitive member 1 via the toner carried by the developing roller 3, the surface of the photosensitive member 1 is very close to the toner. . The developing process is performed by an electric field formed by the latent image on the photoconductor 1 and the developing bias. When the toner on the developing roller 1 approaches the latent image on the photoconductor 1, the toner is charged by the charge of the additive of the toner. Development may not be performed. This is because, in the present method, since the friction coefficient μ of the photoconductor 1 is relatively low, the further developed toner is returned to the developing roller 3 again.

In order to solve this problem, it is considered necessary to prevent the locally charged additive of the toner from electrostatically repelling with the charged lubricant present on the surface of the photosensitive member 1. . As another solution, it is considered that by increasing the degree of aggregation of the toner, it is possible to prevent the toner once developed from being easily scraped off from the photoconductor 1 to the developing roller 3. . This will be described in an embodiment described later.

The current toner A is silica 0.4 [wt]
%] And titanium oxide 0.6 [wt%],
The toner B of the present embodiment is composed of 0.2% by weight of silica and 0.9% by weight of titanium oxide.
Assuming that ₂ [wt%] / Sio ₂ [wt%], the existence ratio of the former toner A is 1.5 and that of the latter toner B is 4.5, and the existence ratio of titanium oxide is increased. Have been.

The above setting requires that the specific gravity of titanium oxide is larger than that of silica, and that the amount of addition of titanium oxide is about twice that of silica when trying to obtain the same surface area. It comes from becoming. Therefore, it is considered that in the toner A, the area ratio between titanium oxide and silica is almost 1: 1. This can reduce the electrostatic repulsion by changing the ratio of the additives. The addition amount of the additive can be increased / decreased and converted in polarity (for example, converted from “+” to “−”) by performing a coupling treatment. Specifically, it is often used as a known method for causing a silane coupling agent to act.

Regarding the charge polarity of the additive, silica is basically often "-charged", and titanium oxide is often "+ -charged". Therefore, the charge amount of the toner in which the addition ratio of titanium oxide is increased as an additive tends to decrease under the influence. FIG. 5 shows the relationship between the charge amounts of the toners A and B and the additive amounts of the additives.

Further, when viewed microscopically, as shown in FIG. 3, the additive of the toner B exists near the latent image 14 near the photosensitive member 1. FIG. 4 shows the case of the toner A, in which the additive having “−charge” is rich and the additive is easily repelled electrostatically with the PTFE (“−charge”) present on the surface of the photoreceptor 1 to develop. Ability decreases. However, the toner B is richer in the “+ charge” as shown in FIG. 3 by reducing the amount of silica and increasing the amount of titanium oxide as compared with the toner A. The surface of the photoconductor 1 is uniformly developed. Thus, the toner B
By controlling the addition ratio of silica and titanium oxide, a uniform and high-density image can be obtained even for a low-contrast latent image.

This embodiment is characterized in that:
7 and 21 are embodiments of the invention according to the present invention, and have a friction coefficient μ
Is set in the range of 0.1 ≦ μ ≦ 0.4, the image carrier 1 is uniformly charged in advance, and then an optical writing is performed on the image carrier 1 to form an electrostatic latent image. The image carrier 1 on which the latent image is formed is brought into contact with a developer carrier 3 carrying a developer to develop an electrostatic latent image on the image carrier 1 into a toner image, and this toner image is transferred. An image forming apparatus to which an image forming method for transferring to a material is applied, wherein at least one kind of additive externally added to the developer is added to a lubricant present on the surface of the image carrier 1. By making the polarity opposite to the charging polarity, the additive of the developer during development can reduce the electrostatic repulsion due to the lubricant on the image carrier, and the developing ability can be maintained.

After the image carrier 1 with the friction coefficient μ set in the range of 0.1 ≦ μ ≦ 0.4 is uniformly charged in advance, the image carrier 1 is optically written to perform electrostatic latent image formation. An image is formed, and the image carrier 1 on which the electrostatic latent image is formed is brought into contact with a developer carrier 3 carrying a developer to develop the electrostatic latent image on the image carrier 1 to form a toner. An image forming apparatus to which an image forming method for transferring an image and transferring the toner image to a transfer material is provided, wherein at least one kind of additive externally added to the developer is added to the image carrier 1. By making the polarity opposite to the polarity of the lubricant existing on the surface of the toner, and by adding the amount thereof at least twice in terms of the surface area ratio, the lubricant of the developer is lubricated on the image carrier during development. The electrostatic repulsion due to the agent can be reduced, and the developing ability can be maintained.

The image carrier 1 has a friction coefficient μ in a range of 0.1 ≦ μ ≦ 0.4. After the image carrier 1 is uniformly charged in advance, the image carrier 1 is charged. An optical latent image is formed by performing optical writing on the image carrier 1, and the image carrier 1 on which the electrostatic latent image is formed is brought into contact with a developer carrier 3 carrying a developer so that an electrostatic latent image is formed on the image carrier 1. An image forming apparatus that develops an electrostatic latent image into a toner image and transfers the toner image to a transfer material, wherein at least one kind of additive externally added to the developer is added to the image. By making the polarity opposite to the charging polarity of the lubricant existing on the surface of the carrier 1, the developer additive during development can reduce electrostatic repulsion due to the lubricant on the image carrier and maintain the developing ability. can do.

Further, a developer supply member 5 is provided which is in contact with the developer carrier 3 and rotates in the same direction as the developer carrier 3 or in the opposite direction to supply the developer to the developer carrier 3. The linear velocity ratio of the developer supply member 5 to the developer carrier 3 is set to 0.5 to 1.5, and the other bite amount of one of the developer supply member 5 and the developer carrier 3 is reduced. By setting the thickness to 0.5 mm to 1.5 mm, the charging characteristics and supply properties of the developer can be improved.

Further, since the developer is composed of toner and has an average particle diameter of 3 μm to 12 μm, it is possible to sufficiently cope with a demand for a high resolution and a reduction in the particle diameter of the toner. In addition, by setting the surface roughness of the developer carrier 3 to 13% to 80% with respect to the toner particle diameter of the developer, the developer can be transported without being buried in the surface of the developer carrier. Can be.

Further, by coating the surface of the developer carrier 3 with a silicon-based coating material, the quality of the developer carrier over time can be stabilized, and the developer charging characteristics can be improved. it can. Further, the developer carrier 3
By coating the surface with a Teflon-based coating material, the temporal quality of the developer carrier can be stabilized, and the developer carrier can have excellent release properties.

Further, by setting the thickness of the coat layer covering the surface of the developer carrier 3 to 5 μm to 50 μm, it is possible to eliminate the problem that the coat layer of the developer carrier is easily broken. Further, it has a developer regulating member 4 for regulating the developer carried on the developer carrying member 3 and a holder 8 for holding the developer regulating member 4. Length to free end is 10
By setting the diameter to 15 mm, it is possible to reduce the size of the developing unit and suppress occurrence of an abnormal image due to vibration.

Further, a developer regulating member 3 for regulating the developer carried on the developer carrying member 3 is provided. The contact pressure of the developer regulating member 3 with respect to the developer carrying member 1 is 5 g · f.
/ Cm to 250 g · f / cm, it is possible to suppress the influence of the contact pressure of the developer regulating member on the developer carrier on the developing ability. Further, by providing a plurality of pressing means for bringing the developer carrier 3 into contact with the image carrier 1, unevenness in the contact force between the developer carrier and the image carrier can be reduced.

Further, at least one of the additives externally added to the developer has a polarity opposite to the polarity of the lubricant present on the surface of the image carrier 1 and is added. By making the amount twice or more in terms of the surface area ratio, it is possible to reduce the electrostatic repulsion of the additive of the developer due to the lubricant on the image carrier at the time of development and maintain the developing ability.

According to another embodiment of the present invention, in the above embodiment, the particle diameter D of the toner is set to 4 [μm] <D <6 [μ
m]. The toner material is as described above and is based on polyester, polyol, and styrene acrylic resin. The toner particle diameter used in the conventional examples and the like is generally 7 [μm] to 11 [μm], but the toner of this embodiment has a smaller particle diameter.

In general, when the particle size of the toner becomes small, the toner becomes closer to the vicinity of the surface of the adherend when it adheres to the adherend, so that the electrostatic force and the van der Waals force, which is a proximity force, act strongly, and the toner is developed and transferred. However, it was difficult to perform the cleaning. Further, the toner once in contact with the photoreceptor remains on the photoreceptor due to background contamination, which adversely affects the image. However, in this embodiment, the friction coefficient μ of the photoconductor 1 is set to 0.1.
Since the region was set at a relatively low value of <μ <0.4, the amount of the residue on the photoreceptor was extremely reduced.

The reason is considered to be that the frictional action of the photoreceptor has been eliminated and the non-electrostatic adhesion of the toner to the photoreceptor, such as van der Waals force, has been reduced. This is because the presence of the lubricant causes the toner that has been relatively close to the vicinity of the surface of the photoreceptor to be distant from the surface of the photoreceptor while being blocked by the lubricant particles.

FIG. 6 is a graph showing the background fouling characteristic based on the friction coefficient of the photosensitive member. This represents the optical density ΔID after transfer (by an adhesive), and the development potential −
400V is a development condition for background contamination. If the concentration at this time is 0.2 or less, there is no practical problem. Therefore, comparison was made between toners having particle diameters D of 4.5 μm and 7.5 μm, respectively, and it was found that there was no problem in both cases and that even when the particle diameter of the toner was reduced, there was little background contamination.

This embodiment is an embodiment of the invention according to claims 3, 18 and 21, wherein the particle diameter of the developer is 4 μm.
Since the thickness is about 6 μm, the non-electrostatic adhesion of the image carrier to the toner can be reduced, and the amount of toner developed on the image carrier can be increased.

In still another embodiment of the present invention, the coagulation degree of the toner is set to 15% or more in the above-described other embodiment. The measurement of the degree of aggregation of the toner is described in
The measurement method and definition of the degree of aggregation of the toner described in JP-A-60033 are generally used.

The method of measuring the degree of aggregation of the toner is as follows: “The sieve opening is 150 μm (upper), 75 μm (middle), 45 μm.
m (lower row) of the first set and the sieve opening is 7
5 μm (upper), 45 μm (middle), 22 μm (lower)
And the second set of the combinations of
Gram, and at an amplitude of 1 mm, T = 20 + | (1.6-
W) /0.016 | [sec. Here, W is the dynamic apparent specific gravity of the toner, and is calculated by the formula of W = (P−a) c / 100 + a, where P: firm apparent specific gravity, a: loose apparent specific gravity, c: loose apparent specific gravity and solid apparent After oscillating the time calculated by the formula of the compression degree obtained from the ratio with the specific gravity, the weight of the toner remaining on each sieve is measured and calculated by the following formula, and (1) | (Toner weight) / 2 | × 100 (2) | (weight of toner remaining in the middle stage) / 2 | × 100 ×
(3/5) (3) | (weight of toner remaining in lower part) / 2 | × 100 ×
(1/5) The sum of the above three calculated values is defined as the toner aggregation degree.

In the above embodiment, the friction coefficient μ of the photosensitive member is 1
When <μ <0.2, when a low-contrast image such as a one-dot image is formed, the amount of development is reduced and the density may be low. According to the above-described method of measuring the toner aggregation degree, the aggregation degree of the toner used at that time was 13%.
It is. In this case, since the friction coefficient of the photoreceptor 1 decreases, the toner once developed becomes
It is estimated that the toner layer on the developing roller 3 is broken by the conveying force and that the toner layer on the developing roller 3 is scraped again. However, in this embodiment, the degree of aggregation of the toner B was 19% when measured by the above-described method of measuring the degree of aggregation of the toner. When the image was formed, a one-dot image could be uniformly developed.

This embodiment is an embodiment of the present invention according to the nineteenth and twentieth aspects, wherein the toner to be developed on the image carrier is developed by setting the cohesion of the developer to 15% or more. The amount of toner that is not scraped off by the developer layer on the developer carrier and is developed on the image carrier can be increased. Further, the friction coefficient μ of the image carrier 1 is set to 0.1 <μ <
By setting the range to 0.2, a low-contrast image can be uniformly developed. It should be noted that the present invention is not limited to the above embodiment, and a color copying machine,
The present invention can be similarly applied to an image forming apparatus such as a printer and a facsimile.

[0087]

As described above, according to the first aspect of the present invention, with the above-described configuration, the additive of the developer can reduce the electrostatic repulsion due to the lubricant on the image carrier at the time of development and maintain the developing ability. can do. According to the second aspect of the present invention, with the above configuration, it is possible to reduce the electrostatic repulsion of the additive of the developer due to the lubricant on the image carrier at the time of development, and maintain the developing ability. According to the third aspect of the present invention, with the above configuration, background contamination can be reduced.

According to the present invention, the amount of toner developed on the image carrier can be increased by the above configuration. According to the fifth aspect of the present invention, with the above-described configuration, it is possible to reduce the electrostatic repulsion caused by the lubricant on the image carrier due to the additive of the developer during the development, thereby maintaining the developing ability. According to the invention according to claim 6, with the above configuration,
At the time of development, the additive of the developer can reduce the electrostatic repulsion due to the lubricant on the image bearing member, and can maintain the developing ability.

According to the seventh aspect of the present invention, the charging characteristics and supply properties of the developer can be improved by the above configuration. According to the invention according to claim 8, with the above configuration, the charging characteristics and supply properties of the developer can be improved. According to the ninth aspect of the present invention, with the above configuration, it is possible to sufficiently cope with a demand for a high resolution and a reduction in toner particle size.

According to the tenth aspect of the present invention, the developer can be transported without being buried in the surface of the developer carrier. According to the eleventh aspect, with the above-described configuration, the temporal quality of the developer carrier can be stabilized, and the developer charging characteristics can be improved. According to the twelfth aspect of the present invention, with the above configuration, the quality of the developer carrier over time can be stabilized, and the developer carrier can have excellent release properties.

According to the thirteenth aspect of the present invention, the above configuration can solve the problem that the coat layer of the developer carrying member is easily broken. According to the fourteenth aspect of the invention, with the above configuration, the developing unit can be made more compact, and the occurrence of an abnormal image due to vibration can be suppressed. According to the invention according to claim 15, with the above configuration, it is possible to suppress the influence of the contact pressure of the developer regulating member on the developer carrier on the developing ability.

According to the sixteenth aspect of the invention, with the above configuration, it is possible to reduce unevenness in the contact force between the developer carrier and the image carrier. According to the invention according to claim 17,
According to the above configuration, during development, the additive of the developer can reduce the electrostatic repulsion due to the lubricant on the image bearing member, and can maintain the developing ability. According to the eighteenth aspect of the present invention, with the above configuration, the non-electrostatic adhesion of the image carrier to the toner can be reduced, and the background stain can be reduced.

According to the nineteenth aspect of the present invention, with the above configuration, the toner developed on the image carrier is not scraped off by the developer layer on the developer carrier and is developed on the image carrier. The amount of toner can be increased. Claim 20
According to the invention according to the above, with the above configuration, a low-contrast image can be uniformly developed. According to the twenty-first aspect, with the above configuration, the additive can reduce electrostatic repulsion due to the lubricant at the time of development and maintain the developing ability.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically showing a part of an embodiment of the present invention.

FIG. 2 is a diagram for explaining a method of measuring a friction coefficient of a photosensitive member.

FIG. 3 is a diagram microscopically showing the vicinity of a photoconductor when toner B is used.

FIG. 4 is a view microscopically showing the vicinity of a photoconductor when toner A is used.

FIG. 5 is a characteristic diagram showing a relationship between the charge amounts of toners A and B and the additive amounts of additives.

FIG. 6 is a characteristic diagram showing a relationship between a development potential Vp and an optical density ΔID of a development toner after a film is transferred.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photoreceptor 2 Developing device 3 Developer carrier 4 Developer regulating member 5 Developer supply member 6 Developer stirring member 7 Developing container 8 Holder

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) G03G 15/08 507 G03G 15/08 507X (72) Inventor Junichi Matsumoto 1-3-3 Nakamagome, Ota-ku, Tokyo No. 6 / Ricoh F-term (reference) 2H005 AA08 DA01 EA05 EA07 EA10 2H068 AA06 AA08 FC08 FC11 2H077 AB04 AC04 AD02 AD06 AD13 AD17 AD23 AD32 AD35 AE02 EA14 EA15 FA01 FA13 FA22

Claims (21)

[Claims] An image carrier having a friction coefficient μ set within a range of 0.1 ≦ μ ≦ 0.4 is uniformly charged in advance, and thereafter, an optical latent image is formed on the image carrier by optical writing. The image carrier on which the formed electrostatic latent image is formed is brought into contact with a developer carrier carrying a developer, and the electrostatic latent image on the image carrier is developed to form a toner image. An image forming method for transferring an image to a transfer material, wherein at least one additive among additives externally added to the developer is charged with respect to the charge polarity of a lubricant present on the surface of the image carrier. An image forming method wherein the polarity is reversed. 2. An image bearing member having a friction coefficient .mu. Set within a range of 0.1.ltoreq..mu..ltoreq.0.4 is uniformly charged in advance, and optical writing is performed on the image bearing member to form an electrostatic latent image. The image carrier on which the formed electrostatic latent image is formed is brought into contact with a developer carrier carrying a developer, and the electrostatic latent image on the image carrier is developed to form a toner image. An image forming method for transferring an image to a transfer material, wherein at least one additive among additives externally added to the developer is charged with respect to the charge polarity of a lubricant present on the surface of the image carrier. Wherein the polarity is reversed and the amount of addition is twice or more in terms of surface area ratio. 3. The image forming method according to claim 1, wherein said developer has a particle size of 4 μm to 6 μm. 4. An image bearing member having a friction coefficient .mu. Set within a range of 0.1.ltoreq..mu..ltoreq.0.4 is charged uniformly beforehand, and then an optical latent image is written on the image bearing member to form an electrostatic latent image. The image carrier on which the formed electrostatic latent image is formed is brought into contact with a developer carrier carrying a developer, and the electrostatic latent image on the image carrier is developed to form a toner image. An image forming method for transferring an image to a transfer material, wherein the degree of aggregation of the developer is set to 15% or more. 5. An image forming method according to claim 1, wherein said image bearing member comprises a photosensitive member, and said developer carrying member comprises a developing roller. 6. An image carrier having a friction coefficient μ set within a range of 0.1 ≦ μ ≦ 0.4, and after the image carrier is uniformly charged in advance, optical writing is performed on the image carrier. To form an electrostatic latent image. The image carrier on which the electrostatic latent image is formed is brought into contact with a developer carrier carrying a developer to develop the electrostatic latent image on the image carrier. An image forming apparatus for transferring the toner image onto a transfer material, wherein at least one additive externally added to the developer is present on the surface of the image carrier. An image forming apparatus characterized in that the polarity of the lubricant is opposite to the polarity of the lubricant. 7. The image forming apparatus according to claim 6, wherein the developer is brought into contact with the developer carrier and rotated in the same direction as the developer carrier or in the opposite direction to supply the developer to the developer carrier. A developer supply member, and the linear velocity ratio of the developer supply member to the developer carrier is 0.5 to 1.5;
The image forming apparatus according to claim 1, wherein an amount of the other of the developer supply member and the developer carrier that bites the other is 0.5 mm to 1.5 mm. 8. An image forming apparatus according to claim 6, wherein said developer supply member comprises a supply roller. 9. An image forming apparatus according to claim 6, wherein said developer comprises a toner and has an average particle diameter of 3 μm to 12 μm.
μm. 10. The image forming apparatus according to claim 6, wherein
An image forming apparatus, wherein the surface roughness of the developer carrier is 13% to 80% with respect to the toner particle diameter of the developer. 11. The image forming apparatus according to claim 6, wherein:
An image forming apparatus, wherein the surface of the developer carrier is coated with a silicon-based coating material. 12. The image forming apparatus according to claim 6, wherein
An image forming apparatus, wherein the surface of the developer carrier is coated with a Teflon-based coating material. 13. The image forming apparatus according to claim 6, wherein
The thickness of the coating layer covering the surface of the developer carrier is 5
An image forming apparatus having a thickness of from 50 μm to 50 μm. 14. An image forming apparatus according to claim 6, wherein:
A developer regulating member that regulates the developer carried by the developer carrying member; and a holder that holds the developer regulating member. The length from the holder to the free end of the developer regulating member is 10 mm. An image forming apparatus having a thickness of 15 mm or less. 15. The image forming apparatus according to claim 6, wherein
A developer regulating member that regulates the developer carried by the developer carrying member; and a contact pressure of the developer regulating member with respect to the developer carrying member is 5 g · f / cm to 250 g · f / cm.
An image forming apparatus comprising: 16. An image forming apparatus according to claim 6, wherein:
An image forming apparatus comprising a plurality of pressing means for bringing the developer carrier and the image carrier into contact with each other. 17. An image carrier having a friction coefficient μ set within a range of 0.1 ≦ μ ≦ 0.4, and after the image carrier is uniformly charged in advance, optical writing is performed on the image carrier. Is performed to form an electrostatic latent image, and the image carrier on which the electrostatic latent image is formed is
An image forming apparatus, wherein an electrostatic latent image on the image carrier is developed into a toner image by being brought into contact with a developer carrier carrying a developer, and the toner image is transferred to a transfer material. At least one of the additives externally added to the agent has a polarity opposite to the charging polarity of the lubricant present on the surface of the image carrier, and the amount of the additive is converted into a surface area ratio. An image forming apparatus characterized in that the number is twice or more. 18. An image forming apparatus according to claim 6, wherein:
An image forming apparatus, wherein the particle size of the developer is 4 μm to 6 μm. 19. An image carrier having a coefficient of friction μ set in a range of 0.1 ≦ μ ≦ 0.4, and after the image carrier is uniformly charged in advance, optical writing is performed on the image carrier. Is performed to form an electrostatic latent image, and the image carrier on which the electrostatic latent image is formed is
An image forming apparatus, wherein an electrostatic latent image on the image carrier is developed into a toner image by being brought into contact with a developer carrier carrying a developer, and the toner image is transferred to a transfer material. An image forming apparatus wherein the cohesion of the agent is set to 15% or more. 20. An image forming apparatus according to claim 19, wherein a friction coefficient μ of said image carrier is set in a range of 0.1 <μ <0.2. 21. An image forming apparatus according to claim 6, wherein said image bearing member comprises a photosensitive member,
An image forming apparatus, wherein the developer carrier comprises a developing roller.