JP2002031996A - Cleaning device and image forming device - Google Patents

Abstract

(57) [Problem] In a conventional cleaning device that performs cleaning by applying a bias voltage to a cleaning roller, since a constant voltage is applied, there is a problem such as image contamination due to local cleaning failure. Was. Further, when the applied bias voltage value is increased in order to improve the cleaning performance, the blade is easily turned up. SOLUTION: A bias voltage is applied to a cleaning roller using a constant current power supply. Further, the current value of the power supply for applying the bias voltage is increased in accordance with the increase in the number of image formation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a cleaning device for cleaning an image carrier used in an electrophotographic process, and an image forming apparatus having the cleaning device.

[0002]

2. Description of the Related Art In recent years, in the field of an image forming technique for forming an image by an electrophotographic system, the particle size of toner has been reduced from the viewpoint of high image quality. By reducing the particle size of the toner, the resolution is improved and a sharp image can be formed. However, the following problem occurs in the cleaning process.

[0003] As the particle size of the toner particles becomes smaller, the adhesive force of the toner to the image carrier becomes apparently larger, so that cleaning for removing the residual toner after transfer from the image carrier becomes difficult. Depending on the cleaning technique using only the cleaning blade, poor cleaning may occur and cause deterioration in image quality. In particular, when an image is formed using a toner having particles formed by a polymerization method such as an emulsion polymerization method or a suspension polymerization method, in addition to the small particle size, the shape of the toner particles is spherical. As a result, there is a problem in that the residual toner on the image carrier is not scraped off by the cleaning blade of the cleaning device, and a cleaning defect called “slippage” passes through the cleaning device.

Researches have been conducted to solve such problems associated with the reduction in the size of toner particles. For example, in Japanese Patent Application Laid-Open No. 11-52808, a conductive blade is made of a conductive material. Alternatively, a cleaning technique has been proposed in which a semi-conductive rubber is used to apply a voltage having a polarity opposite to that of the toner to the cleaning blade to mechanically and electrically remove the toner remaining on the image carrier. Have been.

Japanese Patent Laid-Open Publication No. Hei 3-189675 discloses a cleaning technique in which a cleaning brush which exerts an electrostatic force and a cleaning blade which exerts a mechanical cleaning force are provided downstream of the cleaning brush for cleaning. Have been.

[0006]

However, in these cleaning techniques, (1) cleaning is not performed sufficiently when the potential distribution on the image carrier is not uniform. (2) If the voltage applied to the cleaning blade is increased for the purpose of cleaning, electric discharge or injection of charges into the image carrier occurs, resulting in deterioration of image quality and deterioration of the image carrier. (3) The toner electrostatically adhering to the cleaning blade accumulates over time, and the accumulated toner drops to cause image stains and in-machine stains. (4) If the bias voltage applied to the cleaning roller is increased in order to improve the cleaning performance of the cleaning roller, a state in which no toner is interposed between the downstream cleaning blade and the image carrier occurs, and the friction reduction effect of the toner is reduced. The cleaning blade is likely to be turned up.

An object of the present invention is to solve the problems in the prior art as described above.

[0008]

The object of the present invention is as follows.
This is achieved by any of the following inventions.

1. A conductive or semiconductive cleaning roller that contacts an image carrier that carries charged toner, and a constant current power supply that applies a bias voltage having a polarity opposite to that of the toner involved in development on the image carrier to the cleaning roller. A cleaning blade that contacts the image carrier at a position downstream of the image carrier in the moving direction.

[0010] 2. The cleaning roller rotates at a position where the cleaning roller contacts the image carrier so that the contact surface moves in the same direction as the moving direction of the image carrier. Wherein the ratio of the moving speed of the contact surface is 0.5: 1 to 2: 1.

3. 3. The cleaning device according to 1 or 2, further comprising a removing unit that contacts the cleaning roller and removes toner on the cleaning roller.

4. The cleaning blade is 1 g / c
The cleaning device according to any one of Items 1 to 3, wherein the cleaning device contacts the image carrier with a load of m to 30 g / cm.

5. The cleaning device according to any one of claims 1 to 4, wherein a contact angle between the image carrier and the cleaning blade is in a range of 0 ° to 40 °.

6. The hardness of the cleaning blade is 2
The above-mentioned item 1 which is within a range of 0 ° to 90 °.
6. The cleaning device according to any one of 5.

[0015] 7. A conductive or semiconductive cleaning roller that contacts an image carrier that carries charged toner, a power supply that applies a bias voltage having a polarity opposite to that of toner involved in development on the image carrier to the cleaning roller, In a cleaning device having control means for controlling a power supply and a cleaning blade which comes into contact with the image carrier at a position downstream of the image carrier in the moving direction, the control means has an absolute value corresponding to an increase in the image formation amount. A cleaning device, wherein the power supply is controlled such that the power supply applies an increasing current.

8. The cleaning device according to claim 7, wherein the image formation amount is the number of image formations.

9. Image carrier and any one of 1 to 8 above
An image forming apparatus, comprising: the cleaning device according to item 1.

10. The image forming apparatus according to the item 9, wherein the image carrier is an organic photoconductor.

11. Volume average particle size of 3.0 μm to 8.5
a developing device for developing using a toner having particles formed by a polymerization method having a particle diameter of μm.
Alternatively, the image forming apparatus according to the above item 10.

[0020]

FIG. 1 shows an image forming apparatus according to an embodiment of the present invention. In the figure, reference numeral 1 denotes a photoconductor as an image carrier.

As the photoreceptor, an organic photoreceptor having a photosensitive layer in which an organic photoconductor is dispersed in a resin is preferable from the viewpoint of environmental friendliness and cost.

Reference numeral 2 denotes a charging device that charges the photosensitive member 1 and forms a uniform potential on the photosensitive member 1. As a charging device,
A scorotron charger having a control grid and a discharge electrode or a contact charger type charger using a roller to which a voltage is applied is preferable.

Reference numeral 3 denotes an exposure device for exposing the photosensitive member 1 in accordance with image data. As the exposure device, a scanning exposure device using a laser diode as a light source and having a scanning optical system including a polygon mirror, a lens, and a mirror, and a scanning optical device having a light emitting diode array and an image forming optical fiber are preferable. The exposure device 3 performs dot exposure on the photoconductor 1 according to the image data.

Reference numeral 4 denotes a developing device which contains a one-component developer or a two-component developer, transports the developer to a development area by a developing sleeve 41 as a developer transporting means, and transfers the developer to the developing area. The image is developed to form a toner image on the photoconductor 1. A DC developing bias having the same polarity as the charging polarity of the charging device 2 or a developing bias in which a DC voltage having the same polarity as the charging polarity of the charging device 2 is superimposed on the developing sleeve 41 is applied. Reversal development in which toner is adhered to the portion is performed.

Reference numeral 5 denotes a transfer device including a corona charger. The transfer device 5 charges the recording paper P with a polarity opposite to that of the toner on the photoconductor 1, and transfers the toner image to the recording paper P.

Reference numeral 6 denotes a separation device including a corona charger, which performs AC corona charging on the recording paper P to remove the charge from the recording paper P and separate the recording paper P from the photosensitive member 1.

A fixing device 7 fixes a toner image on the recording paper P by a heating roller 71 having a built-in heat source such as a halogen lamp and a pressure roller 72 pressed against the heating roller 71.

Reference numeral 8 denotes a cleaning device. Untransferred toner and untransferred toner adhere to the photoreceptor 1 after the transfer, and it is necessary to clean the photoreceptor 1 in order to perform the next image formation. The cleaning device 8 includes a cleaning blade 8 made of an elastic blade such as urethane rubber.
1 and a cleaning roller 82. The cleaning blade 81 is supported by a fixed blade holder 83, and the leading edge of the cleaning blade 81 is pressed against the photoconductor 1 with a substantially constant pressure due to the elasticity of the blade. As the blade holder 83, a blade holder that is rotatable about an axis and applies a constant pressing force to the cleaning blade 81 by a spring or gravity is also usable.

The load of the cleaning blade 81 at the leading edge is preferably in the range of 1 g / cm to 30 g / cm, particularly preferably in the range of 5 g / cm to 25 g / cm.

When the load is less than 1 g / cm, the cleaning power is insufficient, the cleaning is incomplete, and the image is easily stained. If the load is more than 30 g / cm, the surface of the image carrier will be greatly worn, and if the image carrier is used for a long period of time, the image will be blurred easily. The load may be measured by pressing the leading edge of the cleaning blade 81 against the balance, or by arranging a sensor such as a load cell at a press-contact portion between the image carrier and the leading edge of the cleaning blade 81 to electrically measure the load. And the like.

The contact angle of the cleaning blade 81 with the photosensitive member 1 is a value within a range of 0 ° to 40 °, particularly 0 ° to 2 °.
A value in the range of 5 ° is desirable. When the contact angle is larger than 40 °, the leading edge of the cleaning blade 81 reverses following the image carrier, that is, the blade is easily turned. On the other hand, when the angle is smaller than 0 °, the cleaning power is reduced, and image stains are likely to occur.
The contact angle is an acute angle formed by the intersection of the cleaning blade 81 and the tangent plane of the photoconductor 1 at the position where the tip of the cleaning blade 81 and the photoconductor 1 are in contact with each other. As shown, it is an angle indicated by θ as viewed from the cleaning position on the downstream side in the rotation direction of the photoconductor 1.

The cleaning blade 81 is made of an elastic material such as urethane rubber.
It is preferable that the JIS A hardness measured by the method described above is in the range of 20 ° to 90 °.

If the angle is smaller than 20 °, the blade is too soft and the blade is easily turned. Also, if it is larger than 90 °,
The ability to follow slight irregularities and foreign matter on the image carrier is insufficient, and toner particles tend to slip.

The thickness of the cleaning blade 81 is preferably in the range of 1 mm to 3 mm, and is preferably 1.5 m
Particularly preferred is a range of m to 2.5 mm. The length of the portion not restricted by the blade holder 83, that is, the free length of the blade is preferably 2 mm to 20 mm, and 3 mm to 1 mm.
Particularly preferred is a range of 5 mm.

Reference numeral 82 denotes a conductive or semiconductive and elastic cleaning roller.

A voltage having a polarity opposite to that of the toner involved in the development is applied to the cleaning roller 82 by a power supply 84. That is, when the development is performed with the negatively charged toner and the negatively charged toner forms a toner image, a positive bias voltage is applied to the cleaning roller 82 from the power supply 84.

As the power source 84, a constant current power source is preferable. When a bias voltage is applied to the cleaning roller 82 from the constant current power source, the toner is electrostatically attracted to the cleaning roller 82 and an excellent cleaning effect is achieved. Can be done. As will be described later, the applied current value of the power supply 84 changes under the control of the control unit 85. Here, the constant current power supply refers to a power supply device configured to control an output voltage according to a resistance between the cleaning roller and the image forming body so that a constant current value is always output. .

Next, the superior cleaning effect of the present embodiment will be described in comparison with a conventional cleaning method in which a constant voltage is applied.

An image portion, a non-image portion and an untransferred portion exist on the surface of the image carrier after the transfer, and the surface potential varies depending on the location and is not uniform. When a constant voltage is applied to the cleaning roller, the potential difference between the cleaning roller and the image carrier is not uniform due to the potential distribution on the image carrier as described above. The value differs depending on the part or the like.

For example, V1 and V2 (V1>
Assuming that a potential portion of V2) exists, when a constant potential V0 is applied to the cleaning roller, the potential difference between the surface of the image carrier and the cleaning roller is V0−
V1 and V0−V2, and the electrostatic attraction acting on the charged toner on the image carrier is not uniform. As a result, there is a difference in the cleaning effect depending on the location on the image carrier, and cleaning failure occurs.

When a constant current bias voltage is applied to the cleaning roller as compared with the above constant voltage application,
The electric field between the surface of the image carrier and the surface of the cleaning roller, which determines the force for separating the charged toner on the image carrier from the image carrier, is basically independent of the potential of the surface of the image carrier. It depends on the impedance of the image carrier as viewed from the roller. Basically, the impedance of the image carrier does not change depending on the position on the image carrier and is constant.

Therefore, by applying a constant current to the cleaning roller to perform cleaning, a uniform cleaning effect can be obtained. That is, regardless of the surface potential of the image carrier, a substantially constant electrostatic attraction force acts on the charged toner on the image carrier. As a result, a uniform cleaning effect can be achieved, and defective cleaning can be avoided.

The applied current value is 1 μA to 50 μm in absolute value.
The range of A is preferable.

If it is smaller than 1 μA, the cleaning effect may be insufficient. If it is larger than 50 μA, the cleaning effect may be insufficient.
Discharge and the like are likely to occur. The current value varies depending on the type of image bearing and the resistance value of the cleaning roller. However, the surface resistivity of the organic photoconductor obtained by dispersing an organic photoconductor in a resin to form a photosensitive layer having a thickness of 10 μm to 30 μm is 10 ² Ω. / □
When a cleaning roller of 〜１０10 ¹⁰ Ω / □ is used,
It is preferably in the range of 5 μA to 40 μA.

As the cleaning roller, a rubber elastic body is used. As a material of such an elastic body, rubber such as conventionally known silicone rubber or urethane rubber, a foam, or a foam covered with a resin film is preferable.

The hardness of the cleaning roller is 5 ゜ -60.
゜, preferably 10 ゜ to 50 ゜ is suitable for obtaining good performance. If it is less than 5 mm, it becomes difficult to secure durability,
If the angle is larger than 60 °, it is difficult to secure a contact width with the image forming body necessary for cleaning, and in addition, the surface of the image forming body is easily scratched. The hardness is measured using an Asker C hardness tester (load: 300 fg) on the elastic body formed into a roller.

The nip width at the time of contact with the image forming body depends on the diameter of the roller, but is preferably set in the range of 0.2 mm to 5 mm, preferably 0.5 mm to 3 mm from the viewpoint of ensuring performance. preferable. If it is less than 0.2 mm, the cleaning power is insufficient, and if it is more than 5 mm, the image forming body is liable to be scratched during rubbing.

The cleaning roller is conductive or semiconductive, and preferably has a surface resistivity in the range of 10 ² Ω / □ to 10 ¹⁰ Ω / □. If the resistance value is lower than 10 ² Ω / □, banding or the like due to discharge is likely to occur. On the other hand, if it is higher than 10 ¹⁰ Ω / □, the potential difference from the photoreceptor becomes low, and cleaning failure easily occurs.

Surface resistivity of cleaning roller Ω / □
Is a value measured at room temperature and normal humidity (26 ° C., relative humidity 50%) using a Hiresta IP (MCP-HT250) manufactured by Mitsubishi Yuka and an HA probe at an applied voltage of 10 V and a measurement time of 10 seconds.

The thickness of the conductive or semiconductive elastic layer depends on the surface resistivity and hardness of the material.
It is preferable to set the distance between m and 50 mm from the viewpoint of securing an appropriate resistance value and a nip width.

It is preferable that the cleaning roller rotates so that the contact portion moves in the same direction as the surface of the image carrier. When the contact portion moves in the opposite direction, if excess toner is present on the surface of the image bearing member, the toner removed by the cleaning roller may spill out and stain the recording paper or the apparatus.

When the image carrier and the cleaning roller move in the same direction as described above, the surface speed ratio between the two is preferably in the range of 0.5: 1 to 2: 1. Outside this range, the speed difference between the two becomes large,
When foreign matter such as recording paper is caught between the image carrier and the cleaning roller, the image carrier may be damaged.

It is preferable that a scraper is brought into contact with the cleaning roller to remove removed substances such as toner transferred from the image carrier to the cleaning roller. In FIG. 2, the scraper 8 is
9 is provided.

As the scraper 89, an elastic plate such as a phosphor bronze plate, a polyethylene terephthalate plate, or a polycarbonate plate is used. The cleaning roller 82 may be brought into contact with the cleaning roller 82 by any method of a counter method in which an acute angle is formed on the cleaning side.

To remove the removed matter such as toner transferred to the cleaning roller 82, a roller or a brush can be used in addition to the scraper.

The cleaning device used in the image forming apparatus according to the present embodiment is particularly effective when using a photosensitive member and a toner as an image carrier as described below.

As the image carrier, an organic photoreceptor is useful from the viewpoint of environmental friendliness or cost. The organic photoreceptor is represented by a photoreceptor in which an organic photoconductor is dispersed in a resin, and is a photoreceptor in which an organic compound has one of a charge generation function and a charge transport function. The surface of the organic photoreceptor has a relatively low strength, and it is difficult to apply a strong cleaning force. If the contact pressure of the cleaning blade widely used in the cleaning device is too high, the surface of the organic photoreceptor will be worn, so that the contact pressure is set to a certain low value. Therefore, it becomes difficult to secure stable cleaning performance for a long period of time.

By using the above-described cleaning device, a good cleaning effect can be obtained without increasing the contact pressure of the cleaning blade. The problem of cleaning in the prior art has been solved.

The toner used for development preferably has a volume average particle diameter of 3.0 μm to 8.5 μm, particularly preferably 3.0 μm to 6.5 μm from the viewpoint of high image quality. The volume average particle diameter of the toner of the present invention is determined by using a Coulter counter TA-.
It is measured by II or Coulter Multitizer (manufactured by Coulter). In the present invention, an interface (manufactured by Nikkaki Co., Ltd.) for outputting a particle size distribution was used with a personal computer connected using a Coulter Multitizer. The volume average particle diameter was calculated by measuring the volume and the number of toner particles having a size of 2 μm or more by using a 100 μm aperture as the aperture used in the Coulter Multitizer.

As the toner having such a small particle diameter, a toner in which particles are formed by a polymerization method such as an emulsion polymerization method, a suspension polymerization method, and a dispersion polymerization method is particularly preferable. That is, the toner in which the particles are formed by the polymerization method has a narrow particle size distribution, and is effective in improving the image quality in that the particles are not limited to a spherical shape but have a desired shape.

As the toner in which particles are formed by such polymerization, there are two types: a toner in which particles formed by polymerization form toner particles as they are, and a toner in which particles formed by polymerization are combined to form toner particles. included.

However, there is a problem that cleaning is difficult with a toner having a small particle diameter. In particular, in a toner in which particles are formed by this polymerization method, the toner particles are often spherical, making cleaning difficult. There is a problem.

The embodiment of the present invention is, of course, effective for cleaning in image formation using a toner having a relatively large particle diameter by a pulverization method in which a resin is pulverized to form toner particles. An excellent cleaning effect can be obtained even for the toner having the small particle diameter as described above, particularly for the toner having particles formed by the polymerization method.

In cleaning for removing toner from the image carrier by using a cleaning blade and a cleaning roller to which a bias voltage has been applied, charged toner is removed by electrostatic force by a cleaning roller disposed on the upstream side of the cleaning blade, and downstream of the cleaning roller. The cleaning is performed by a cleaning mechanism that removes uncharged or oppositely charged toner and fine particles that are not removed by the cleaning roller by the cleaning blade on the side.

In order to improve the cleaning performance, it is effective to increase the current value of the bias voltage applied to the cleaning roller. However, when the cleaning effect by the cleaning roller is improved,
In the early stage of image formation, inconveniences such as turning up of the cleaning blade and vibration of the tip of the cleaning blade tend to occur. This phenomenon occurs because the toner functioning as a slip agent between the image carrier and the cleaning blade is removed by the cleaning roller, so that the amount of toner present at the tip of the cleaning blade is reduced only by the conventional cleaning blade. It is thought to be caused by a small amount as compared with the cleaning method. In particular, this phenomenon occurs remarkably in the early stage of image formation in which the contact edge of the cleaning blade is sharp.

In the present embodiment, in order to solve such a problem, a relatively small current is applied to the cleaning roller in the early stage of image formation, and the current value is increased in accordance with an increase in the amount of image formation. Control means 8 to control the increase
By performing in step 5, a good cleaning effect is obtained throughout the entire image forming process. As the amount of image formation, the time for image formation and the number of image formation can be applied, and the number of image formation is preferable.

In the early stage of image formation, that is, when a new cleaning blade is mounted, the cleaning performance of the cleaning blade is high. Even if the cleaning performance of the cleaning roller is not increased, the desired cleaning performance of the entire cleaning device can be obtained. can get.

FIG. 3 shows an example of the relationship between the number of formed images and the current value of the bias voltage applied to the cleaning roller. As shown in the figure, the current value is gradually increased from A1 to A3 in response to the increase in the number of image formations from N1 to N3, and the current value is increased every time the cleaning blade is replaced. The cycle of returning to the initial value and increasing according to the number of image formation is repeated.

The toner used in the embodiment of the present invention is used for either a one-component developer or a two-component developer, and can be used as a magnetic toner or a non-magnetic toner.

[0070]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (1) As an embodiment of the present invention, a photoreceptor as an image carrier, an exposing device, a developing device, a toner, a cleaning roller, a cleaning blade, etc., using the image forming apparatus shown in FIGS. An image forming experiment was performed under the following conditions.

<Example 1> * Photoreceptor A phthalocyanine pigment was used as an organic photoconductor, and the organic photoconductor was dispersed in a polycarbonate resin and applied to a conductive drum made of aluminum (Al). 25μ
m photoreceptor formed with a photoconductive layer. * Exposure device An exposure device that uses a laser diode as a light source, has a scanning optical system composed of polygon mirrors, lenses, and mirrors, and performs scanning exposure. * Developing device A developing device that has a developing sleeve that rotates at a linear speed of 370 mm, and applies a bias voltage having the same polarity as the potential of the photoconductor to the developing sleeve to perform reversal development using a two-component developer. * Toner The volume average particle size of particles formed by emulsion polymerization is 6.5.
μm toner * Cleaning roller A conductive roller made of urethane foam having a surface resistivity of 5.0 × 10 ⁴ Ω / □. The hardness was set to 32 mm, and the nip portion with the image forming body was set to 2 mm. The roller is φ
A urethane layer was wound around a 6 mm metal shaft to a thickness of 4.5 mm (roller diameter φ15 m).
m).

A driving system branched from a driving system of the photoconductor is driven to rotate so as to move in the same direction as the photoconductor at a contact portion with the photoconductor, and a scraper is provided to remove toner on the roller surface. The ratio of the moving speeds of the image forming body and the contact portion was set to 1: 1. * Current value of bias voltage applied to cleaning roller Up to 150,000 sheets ... + 20 μA This was repeated two cycles to form an image up to 300,000 sheets. The power supply used was a constant current control power supply. Note that the current flowing from the cleaning roller to the photoreceptor is +. * Cleaning blade Made of urethane rubber, hardness 70 °, thickness 2.00m
The cleaning blade having a length of 10 mm and a free length of 10 mm was brought into contact with the photosensitive member at a contact angle of 10 ° and a load of 5 g / cm. * Environment ・ Normal temperature and normal humidity (temperature 20 ° C, relative humidity 50%) up to 50,000 sheets ・ High temperature and high humidity (temperature 30 ° C, 50 to 150,000 sheets)
(The relative humidity is 80%.) The durability of the used cleaning blade is 150,000 sheets.

In the experiment, when 150,000 images were formed, the cleaning blade was replaced, and the next 150,000 images were formed under the above environment, so that a total of 300,000 images were formed.

<Embodiment 2> Except that the current value of the bias voltage applied to the cleaning roller was changed as follows,
Image formation was performed under the same conditions as in Example 1.・ Up to 50,000 sheets ... + 5μA ・ From 51 to 100,000 sheets ... + 15μA ・ From 101,000 sheets to 150,000 sheets ... + 30μA

(2) As a comparative example, an image forming experiment was performed under the following conditions. Comparative Example 1 Same as Example 1 except that no current was applied to the cleaning roller (0 μA).

Comparative Example 2 A constant voltage power supply of +500 V was used as a power supply for applying a voltage to the cleaning roller. Others are the same as Example 1.

Comparative Example 3 The same as Example 1 except that the moving speed ratio of the cleaning roller and the image forming body at the contact surface was 0.3 to 1.0.

<Comparative Example 4> A moving speed ratio at a contact surface between a cleaning roller and an image forming body was 2.5 to 1, except that
Same as Example 1.

Comparative Example 5 The same as Example 1 except that the contact load of the cleaning blade was 0.5 g / cm.

Comparative Example 6 The same as Example 1 except that the contact load of the cleaning blade was 35 g / cm.

Comparative Example 7 The same as Example 1 except that the hardness of the cleaning blade was 10 °.

Comparative Example 8 The same as Example 1 except that the hardness of the cleaning blade was 95 °.

As a result of the above-described image forming experiment, in Examples 1 and 2 of the present invention, a good image was obtained without image stains or fogging. In particular, in Example 2, no vibration of the blade occurred, and stable cleaning performance could be obtained.

On the other hand, in Comparative Example 1, after the formation of 40,000 sheets of images, cleaning failure occurred due to insufficient cleaning force of the cleaning blade, and stains occurred on the images.

In Comparative Example 2, after the image formation of 110,000 sheets,
Local cleaning failure occurred due to potential unevenness of the image forming body, and stains occurred on the image.

In Comparative Example 3, scratches were generated on the image forming body due to rubbing, and black streaks were generated on the image after forming 60,000 sheets of the image.

Also in Comparative Example 4, scratches were generated on the image forming body due to rubbing, and black streaks were generated on the image after forming 60,000 sheets of the image.

In Comparative Example 5, cleaning failure occurred after 30,000 sheets of the image were formed due to insufficient cleaning of the cleaning blade, and the image was stained.

In Comparative Example 6, image fogging and blurring occurred after 200,000 sheets of an image were formed, since the film formation of the image forming body was large and local streaks occurred on the image forming body.

In Comparative Example 7, since the cleaning blade follows the movement on the image forming member too much, the cleaning blade was turned up at the beginning of image formation.

In Comparative Example 8, since the followability of the cleaning blade was low, cleaning failure occurred after formation of 40,000 sheets of images, and stains occurred on the images.

[0092]

According to the first aspect of the present invention, even in the case of an image carrier having a non-uniform surface potential, uniform and good cleaning is performed, so that a clear image free of image stains and fog can be formed. It is possible to produce a highly durable image forming apparatus.

According to the second aspect of the present invention, sufficient cleaning performance can be obtained, and even when foreign matter is caught between the image carrier and the cleaning roller, the image carrier is not damaged, and excellent cleaning performance is obtained. Will be maintained.

According to the third aspect of the invention, excellent cleaning performance is maintained for a long period of time.

According to the fourth aspect of the present invention, it is possible to manufacture an image forming apparatus having excellent cleaning performance and extending the life of the image carrier, and having high durability.

According to the fifth and sixth aspects of the present invention, excellent cleaning performance is obtained, and furthermore, the occurrence of blade turning is prevented.

According to the seventh and eighth aspects of the present invention, it is possible to prevent the blade turning which is likely to occur when the cleaning performance is improved, and to maintain the excellent cleaning performance for a long period of time.

According to the ninth aspect of the present invention, a highly durable image forming apparatus capable of forming a high-quality image free from image stains and fog is realized.

According to the tenth aspect, a low-cost and high-quality image forming apparatus is realized.

According to the eleventh aspect of the present invention, an image forming apparatus with high image quality in terms of resolution and the like is realized.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing an example of a cleaning roller in the cleaning device according to the embodiment of the present invention.

FIG. 3 is a graph showing the relationship between the number of formed images and the current value of a bias voltage.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photoconductor 2 Charging device 3 Exposure device 4 Developing device 5 Transfer device 6 Separation device 7 Fixing device 8 Cleaning device 81 Cleaning blade 82 Cleaning roller 83 Blade holder 84 Power supply

Claims (11)

[Claims] 1. A conductive or semi-conductive cleaning roller which comes into contact with an image carrier carrying charged toner, and a bias voltage having a polarity opposite to that of the toner involved in development on the image carrier. And a cleaning blade that is located downstream of the cleaning roller in the moving direction of the image carrier and is in contact with the image carrier. 2. The cleaning roller rotates at a position where the cleaning roller contacts the image carrier so that the contact surface moves in the same direction as the moving direction of the image carrier. 2. The cleaning apparatus according to claim 1, wherein a ratio between a speed and a moving speed of the contact surface of the image carrier is 0.5: 1 to 2: 1. 3. The cleaning device according to claim 1, further comprising a removing unit that contacts the cleaning roller and removes toner on the cleaning roller. 4. The cleaning blade is 1 g / cm.
The cleaning device according to claim 1, wherein the cleaning device contacts the image carrier with a load of 30 g / cm. 5. The cleaning device according to claim 1, wherein a contact angle between the image carrier and the cleaning blade is in a range of 0 ° to 40 °. 6. The cleaning blade has a hardness of 20.
The angle is in the range of 90 ° to 90 °.
6. The cleaning device according to any one of items 5 to 5. 7. A conductive or semi-conductive cleaning roller contacting an image carrier carrying a charged toner, and a bias voltage having a polarity opposite to that of the toner involved in development on the image carrier. And a control means for controlling the power supply; and a cleaning blade downstream of the cleaning roller in the moving direction of the image carrier and in contact with the image carrier. The cleaning device controls the power supply so that the power supply applies a current whose absolute value increases in accordance with an increase in the amount of image formation. 8. The cleaning apparatus according to claim 7, wherein the image formation amount is the number of image formations. 9. An image carrier and any one of claims 1 to 8.
An image forming apparatus, comprising: the cleaning device according to item 1. 10. The image forming apparatus according to claim 9, wherein said image bearing member is an organic photosensitive member. 11. A volume average particle size of 3.0 μm to 8.5 μm.
10. A developing device for performing development using a toner having particles formed by a polymerization method of m.
An image forming apparatus according to claim 10.