JP2002031997A - Cleaner and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To overcome a problem such that a cleaning blade is caused to chatter or turned over, in a conventional cleaner which electrostatically removes toner by application of a bias voltage to a cleaning brush and mechanically removes toner with the cleaning blade. SOLUTION: A toner recover voltage increasing according to an increase in an amount of image formation is applied to a cleaning roller. Besides the toner recovery voltage, a toner discharge voltage is regularly applied to the cleaning roller.

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 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 adhesion of the toner to the image bearing member becomes apparently larger, so that cleaning becomes difficult. Incorrect cleaning may cause image quality deterioration. 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, a cleaning defect called “slippage” that passes through the cleaning device without being scraped off by the cleaning blade of the cleaning device becomes a problem.

Researches have been conducted to solve such problems associated with the reduction in the size of toner particles, and a bias voltage is applied to apply electrostatic cleaning force to toner on an image carrier. JP-A-3-189675 discloses a cleaning device provided with a cleaning brush that works and a cleaning blade that mechanically works a cleaning force downstream of the cleaning brush.

[0005]

The cleaning device disclosed in the above-mentioned publication improves the cleaning performance by sharing a cleaning function with a cleaning brush and a cleaning blade.
Includes the following issues:

[0006] Since most of the toner is removed by the brush arranged on the upstream side, a state occurs in which the amount of toner interposed between the image carrier and the cleaning blade is extremely small. In such a state, the friction between the image carrier and the cleaning blade increases, and the vibration of the cleaning blade and chattering, and the tip of the cleaning blade being turned upside down by following the image carrier are easily generated. Become.

Accordingly, an object of the present invention is to solve the above-mentioned problems in the conventional cleaning technique and to provide a cleaning device having high cleaning performance and an image forming apparatus having the cleaning device.

[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 toner, a power supply that applies a toner collection voltage to the cleaning roller, a control unit that controls the power supply, and the image that is more than the cleaning roller. A cleaning blade downstream of the carrier in the moving direction and in contact with the image carrier, wherein the control unit is configured to control the toner collection voltage, the absolute value of which increases in accordance with an increase in the amount of image formation, with the cleaning voltage. A cleaning device, wherein the power supply is controlled so as to be applied to a roller.

[0010] 2. 2. The cleaning device according to claim 1, wherein the image formation amount is the number of image formations.

3. A conductive or semi-conductive cleaning roller that contacts an image carrier that carries toner, a power supply that applies a toner collection voltage and a toner discharge voltage to the cleaning roller, control means that controls the power supply, A cleaning blade that is located downstream of the roller in the moving direction of the image carrier and contacts the image carrier;
Has a, the control means, so that the toner recovery voltage and the toner discharge voltage is selected and applied temporally,
A cleaning device for controlling the power supply.

4. The cleaning device according to claim 3, wherein the toner discharge voltage is applied every time a predetermined number of images are formed.

5. The cleaning device according to claim 4, wherein the toner discharge voltage is applied every time the predetermined number of images is formed, which varies according to the number of formed images.

6. The toner discharge voltage is obtained by superimposing an AC voltage on a DC voltage.
The cleaning device according to any one of the preceding claims.

[0015] 7. A conductive or semiconductive cleaning roller that contacts the image carrier that carries the charged toner,
A power supply for applying a toner collection voltage and a toner discharge voltage to the cleaning roller, control means for controlling the power supply,
A cleaning blade downstream of the cleaning roller in the moving direction of the image carrier and in contact with the image carrier, wherein the control unit increases the absolute value in response to an increase in the amount of image formation. The cleaning device according to claim 1, wherein the power supply is controlled so that the recovery voltage is applied and the toner recovery voltage and the toner discharge voltage are temporally selected and applied.

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

9. Wherein the toner discharge voltage is applied every time a predetermined number of images are formed.
A cleaning device according to claim 1.

10. The cleaning device according to claim 9, wherein the toner emission voltage is applied every time the predetermined number of images is formed, which varies according to the number of images formed.

11. Wherein the toner discharge voltage is obtained by superimposing an AC voltage on a DC voltage.
The cleaning device according to any one of items 10 to 10.

[12] 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. The cleaning device according to any one of the items 1 to 11, wherein a ratio of the contact surface to the moving speed of the contact surface is 0.5: 1 to 2: 1.

13. Contacting the cleaning roller,
13. The cleaning device according to any one of items 1 to 12, further comprising a removing unit that removes toner on the cleaning roller.

14. The cleaning blade is 1 g /
14. The cleaning device according to any one of items 1 to 13, wherein the cleaning device contacts the image carrier with a load of 30 cm / cm to 30 g / cm.

[15] The cleaning device according to any one of claims 1 to 14, wherein a contact angle between the image carrier and the cleaning blade is an angle in a range of 0 ° to 40 °.

16. Wherein the hardness of the cleaning blade is in the range of 20 ° to 90 °.
The cleaning device according to any one of Items 1 to 15, wherein

17. An image forming apparatus comprising an image carrier and the cleaning device according to any one of the above items 1 to 16.

18. The image carrier is an organic photoreceptor,
A charging device for charging the organic photoreceptor, an exposure device for exposing the charged organic photoreceptor, and developing the electrostatic latent image formed on the organic photoreceptor by charging and exposing to attach charged toner. 18. The image forming apparatus according to 17, wherein the image forming apparatus further includes a developing device for forming an image.

19. The developing device described above, wherein the developing device performs development using a toner having a volume average particle diameter of 3.0 μm to 8.5 μm and having particles formed by a polymerization method.
An image forming apparatus according to claim 1.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (1) First Embodiment FIG. 1 shows an image forming apparatus according to a first 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,
It is preferable to use a scorotron charger having a control grid and a discharge electrode or a contact charger using a roller to which a transfer voltage is applied. In the present embodiment, the photoconductor 1 is negatively charged.

An exposure device 3 exposes the photosensitive member 1 in accordance with image data. As the exposure apparatus, a scanning exposure apparatus using a laser diode as a light source and having a scanning optical system composed of polygons, lenses and mirrors, and a scanning optical apparatus 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. In addition, as the developing device 4,
It is also possible to use a developing device for performing regular development in which toner is attached to an unexposed portion of the photoconductor 1.

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 it from the photoreceptor 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 particles separated from the recording paper P adhere to the photoreceptor 1 after the transfer, and the photoreceptor 1 needs to be cleaned in order to form the next image. Cleaning device 8
Has a cleaning blade 81 made of an elastic blade such as urethane rubber and a cleaning roller 82.
The cleaning blade 81 has a fixed blade holder 8.
3, the leading edge of which is pressed against the photoreceptor 1 with a substantially constant pressure due to the elasticity of the blade. As the blade holder, it is also possible to use a blade holder that is rotatable about an axis and applies a constant pressing force to the cleaning blade 81 by a load applied by a spring or gravity.

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 greater than 30 g / cm, the abrasion of the photoreceptor 1 is increased, and when the photoreceptor 1 is used for a long period of time, image fading or the like is likely to occur.
The load may be measured by pressing the leading edge of the cleaning blade against the balance, or by electrically arranging a sensor such as a load cell at a pressure contact portion between the photosensitive member 1 and the leading edge of the cleaning blade 81. A measuring method or the like is used.

The contact angle of the cleaning blade 81 to 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. If the contact angle is larger than 40 °, so-called turning, that is, chatter in which the cleaning blade 81 vibrates and the leading edge is reversed following the image carrier, is likely to occur. 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 determined by the cleaning blade 81.
Is the angle at which the cleaning blade 81 and the tangent plane of the photoconductor 1 intersect at the position where the tip of the photoconductor 1 abuts on the downstream side of the cleaning position in the rotation direction of the photoconductor 1 as shown in FIG. This is the angle indicated by θ.

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 °.

When the angle is smaller than 20 °, the sheet is too soft and is likely to be turned. If the angle is larger than 90 °, the photosensitive member 1
The ability to follow small irregularities and foreign matter is insufficient, and particles are likely 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. Cleaning roller 82
, A voltage having a polarity opposite to that of the toner is applied by the power supply 84. In the present embodiment, an image is formed by reversal developing the negatively charged photoconductor 1 with negatively charged toner.
The power supply 84 applies a positive voltage (hereinafter, referred to as a toner collection voltage) having a polarity opposite to the negative charge of the toner that has contributed to the development to the cleaning roller 82, and a residual toner after the transfer on the photosensitive member 1. Is collected by the cleaning roller 82. The toner collection voltage is a voltage that electrostatically transfers the toner on the photoconductor 1 to the cleaning roller 82, and the polarity of the voltage is opposite to the polarity of the toner that has formed an image and is involved in development in development.

As will be described later, the power supply 84 applies a toner collection voltage which is controlled by the control means 85 and increases with an increase in the amount of image formation.

Next, the cleaning operation according to the embodiment of the present invention will be described. On the photoconductor 1, in addition to toner charged to the same polarity as the charging potential of the photoconductor 1 in the developing device 4, toner charged to the opposite polarity, powder transferred from the recording paper P, and the like exist. The cleaning roller 82 electrostatically removes particles such as toner charged to the same polarity as the polarity of the toner involved in the development in the developing device 4 among the various kinds of attached matter. Then, the non-charged toner, the oppositely charged toner, and other particles not removed by the cleaning roller 82 are mechanically removed by the cleaning blade 81.

In the embodiment of the present invention, FIGS.
By controlling the power supply 84 by the control unit 85, a voltage that increases in accordance with an increase in the amount of image formation is applied to the cleaning roller 82 as shown in FIG.

The cleaning performance of the cleaning blade 81 gradually decreases because the edge of the cleaning blade 81 that scrapes off the toner from the photoreceptor 1 wears.
In the present embodiment, as shown in FIG. 3, the cleaning performance of the cleaning roller 82 is increased in accordance with the increase in the amount of image formation, so that the cleaning blade 81 is increased.
Is reduced as the image forming amount increases, and the cleaning performance of the entire cleaning device 8 is favorably maintained throughout the entire image forming process.

It is known that toner intervenes between the photosensitive member 1 and the cleaning blade 81 and acts as a slip agent. By this action, the cleaning blade 81
Smooth cleaning is performed. However, when the toner is removed by the cleaning roller 82 and there is no or little toner, the frictional resistance between the photosensitive member 1 and the cleaning blade 81 is large, and the phenomenon called chatter in which the cleaning blade vibrates or the cleaning is performed. A phenomenon called “turning” occurs in which the tip of the blade 81 reverses following the photosensitive member 1. If the cleaning performance by the cleaning roller 82 is made too high, the toner as the above-mentioned slip agent decreases, and chattering and turning over are likely to occur.

In the embodiment of the present invention, the voltage to be applied to the cleaning roller 82 is set relatively low at the beginning of the image formation in which the leading edge of the cleaning blade is sharp and curling is likely to occur. By increasing the value in accordance with the increase, good cleaning performance is maintained throughout the entire image forming process.

As shown in FIG. 2, when the number of image formations N1 to N3 increases, the bias voltage is increased from V1 to V3.
The bias voltage is increased stepwise until the initial value V1 is returned by replacing the cleaning blade.

As the initial value V1, it is preferable to apply a toner recovery voltage of 0 or a value of about 1/3 of the maximum value V3 while floating.

As the cleaning roller 82, an 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 cleaning roller has a hardness of 5 to 60 degrees, preferably 10 to 60 degrees.
50 ° is appropriate for obtaining good performance. If the angle is less than 5 °, it is difficult to ensure durability. If the angle is more than 60 °, it is difficult to secure a contact width with the image forming body required for cleaning, and the surface of the image forming body is easily scratched. The hardness of the elastic body after shaping was applied to a roller using an Asker C hardness meter (with a load of 30).
0fg). 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. 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 82 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 is low, and cleaning failure tends to occur. The surface resistivity (Ω / □) of the cleaning roller is normal temperature and normal humidity (26
℃, relative humidity 50%), Mitsubishi Yuka Hiresta I
It is a value measured using P (MCP-HT250) 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, but is preferably set to a value between about 0.5 mm and 50 mm. It is preferable from the viewpoint of securing.

It is preferable that the cleaning roller 82 rotates so that the contact portion moves in the same direction as the surface of the photosensitive member 1. When the contact portion moves in the opposite direction, if excess toner is present on the surface of the photoconductor 1, the toner removed by the cleaning roller 82 may be spilled and stain the recording paper or the apparatus.

When the photosensitive member 1 and the cleaning roller 82 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 of this range, the speed difference between the two becomes large, so that foreign matter such as recording paper is
When the photosensitive member 1 is caught between the two, the photosensitive member 1 may be damaged.

It is preferable that the scraper is brought into contact with the cleaning roller 82 to remove the removed material such as toner transferred from the photosensitive member 1 to the cleaning roller 82. FIG. 3 shows an example in which a scraper 89 is provided for the cleaning roller 82.

As the scraper 89, an elastic plate such as a phosphor bronze plate, a polyethylene terephthalate plate, a polycarbonate plate or the like is used, and a trail type in which the tip forms an acute angle on the non-cleaning side of the cleaning roller 82 or a cleaning method in which the tip 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.

Further, in order to remove the removed matter such as the toner transferred from the cleaning roller 82 to the cleaning roller 82, it is possible to use a roller or a brush in addition to the scraper.

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

As the image carrier, an organic photoreceptor is useful from the viewpoint of environmental friendliness and 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 a cleaning blade, which is widely used as a cleaning device, is set too high, the surface of the organic photoreceptor is worn, and the contact pressure is currently suppressed. Therefore, it has been 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. Good cleaning performance can be stably ensured, and the above-described problem of cleaning in the related art can be solved.

The toner used in the 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 is effective for improving the image quality in that it has a narrow particle size distribution, and is not limited to a spherical shape but has a desired shape.

However, there is a problem that cleaning is difficult with a toner having a small particle diameter. Particularly, in a toner in which particles are formed by a polymerization method, the toner particles often have a spherical shape, which makes cleaning difficult. The problem becomes noticeable.

The embodiment of the present invention is, of course, effective for cleaning in image formation using toner having a relatively large particle diameter by a pulverization method in which resin particles are formed 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.

As the toner in which particles are formed by such polymerization, there are a toner in which particles formed by polymerization form toner particles as it is, and a toner in which particles formed by polymerization are combined to form toner particles. included.

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.

(2) Second Embodiment Next, a second embodiment in which chatter and turning of the cleaning blade are prevented and good cleaning performance is obtained will be described.

FIG. 4 shows an image forming apparatus according to the second embodiment. In the second embodiment, power supplies 84 and 86 having mutually opposite polarities are temporally selected and connected to the cleaning roller 82. That is, the power supply 84 applies a toner collection voltage for electrostatically transferring the charged toner on the photoconductor 1 to the cleaning roller 82 to the cleaning roller 82, and the power supply 86 applies the charged toner on the cleaning roller 82 to the photoconductor 1 A voltage for shifting to 1, that is, a toner discharge voltage is applied. The polarity of the toner discharge voltage is opposite to the toner recovery voltage.

As described above, by applying the opposite bias voltages to each other, the toner on the cleaning roller 82 is discharged onto the photoreceptor 1, so that an appropriate amount of toner is always present on the photoreceptor 1. It is possible to prevent the above-mentioned chattering and turning over.

The application of the toner discharge voltage is performed at a timing at which the cleaning action of the cleaning roller 82 is not hindered. For example, it is preferable to periodically apply the toner release voltage with respect to the number of formed images so that the toner release voltage is applied every 10 to 1000 sheets of image formation. It is also possible to change the interval of the periodic application of the toner discharge voltage in accordance with the amount of image formation. For example, in the initial stage, a good cleaning effect can be obtained by applying the toner discharge voltage to each of 1000 images and every 500 sheets after forming 100,000 images. As in the embodiment described later,
The image formation may be performed while applying the toner discharge voltage. Alternatively, the toner may be applied to the photoconductor 1 by applying the toner discharge voltage while rotating the photoconductor 1 without performing the image formation. Switching between the toner collecting voltage and the toner discharging voltage is performed by controlling the switch 88 by the control means 85.

In the image forming process using the reversal development, the toner discharge voltage preferably has a value of 1-2 times the white background potential. For example, the white background voltage is -750V.
In this case, a voltage of -750V to -2250V is preferable. In the image forming step using regular development, a voltage value of 1/10 to 5 times the black background potential is preferable. In an image forming system in which discharge is likely to occur, a relatively low voltage for preventing discharge, that is, when reversal development is used, 1 to 1.5 times the white background potential is particularly preferable. When used, it is particularly preferably 1/3 to 2/3 times the black character potential.

Further, the power supply 86
It is also possible to apply a bias voltage in which an AC voltage from the power supply 87 is superimposed on a DC voltage from the power supply 87. The application of the AC voltage is an effective means for discharging the toner from the cleaning roller 82 to the photoreceptor 1.
It is preferable to use an AC voltage having a frequency in the range of Hz.
Further, the amplitude of the AC voltage is a peak-to-peak voltage, and in an image forming system using reversal development, the amplitude is 1/3 to 2
1/3 of the black background potential in an image forming system using regular development
A range of ~ 2 times is preferred.

Further, the combination of the first and second embodiments is also effective in improving the cleaning performance. That is, by controlling the power supply 84 and the switch 88 by the control unit 85, the toner collection voltage is increased in accordance with the increase in the number of formed images, and the toner discharge voltage is periodically applied to the cleaning roller 82 to improve the image quality. A cleaning effect is obtained. Also in such an embodiment, it is possible to change the interval of the periodic application of the toner discharge voltage in accordance with the image forming amount.

[0074]

Embodiment (1) FIGS. 1 and 3 show Embodiment 1 of the present invention.
A photoreceptor as an image carrier using the image forming apparatus shown in
An image forming experiment was performed on the exposure device, the developing device, the toner, the cleaning roller, the cleaning blade, and the like under the following conditions.

* Photoreceptor A phthalocyanine pigment is used as an organic photoconductor, and the organic photoconductor is dispersed in a polycarbonate resin and applied to a conductive drum made of aluminum (Al) to have a thickness of 25 μm.
m photoreceptor formed with a photoconductive layer. The photosensitive member is negatively charged to form an image.

The white background potential was -750V. * 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 having a developing sleeve rotating at a linear velocity of 370 mm, and applying a bias voltage having the same polarity as the potential of the photosensitive member to the developing sleeve to perform reversal development using a two-component developer.

* Toner The volume average particle diameter of particles formed by the emulsion polymerization method is 6.5.
μm negatively charged toner * Cleaning roller A conductive roller made of urethane foam having a surface resistivity of 4.5 × 10 ⁴ Ω / □. The hardness was 30 ° and the nip width with the image forming body was 2 mm. The roller was formed by winding a urethane layer around a metal shaft of φ6 mm to a thickness of 4.5 mm (roller diameter φ15 mm).

The photosensitive member is rotated following the direction of rotation (moves in the same direction at the nip portion), and a scraper is provided to remove toner on the roller surface. The peripheral speed ratio with the image forming body is 1:
It was set to 1.

* Voltage value of toner recovery voltage applied to cleaning roller Up to 50,000 sheets: +100 V From 51 to 100,000 sheets +300 V From 101,000 sheets to 150,000 sheets +600 V * Cleaning blade This cycle was repeated twice to form an image on 300,000 sheets. Made of urethane rubber, hardness 70 °, thickness 2.0
0 mm, 10 mm free length cleaning blade
The leading edge was brought into contact with the photoreceptor at a contact angle of ° and a load of 12 g / cm.

* Environment ・ Normal temperature and 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-mentioned environment, thereby forming a total of 300,000 images.

(2) As Embodiment 2, +600 V as a toner recovery voltage is applied to the cleaning roller throughout the image forming process, and a DC voltage of -1000 V as a toner discharge voltage, a peak-to-peak voltage of 500 V,
A voltage obtained by superimposing an AC voltage having a frequency of 2 kHz was periodically applied by the following method.

From 0 to 50,000 sheets, the toner discharge voltage is set in the image formation for one sheet every 1000 sheets. From 51,000 sheets to 100,000 sheets, the toner discharge voltage is set in the image formation for one sheet every 500 sheets. Voltage from 100,000 sheets to 150,000 sheets
In the image formation for one sheet every 00 sheets, the toner discharge voltage was applied, and the cycle of applying the toner discharge voltage was repeated twice to form a total of 300,000 images. In the third embodiment, the toner recovery voltage is set to 50,000 sheets: +100 V, from 51 to 100,000 sheets: +300 V, from 101,000 sheets to 150,000 sheets: +600 V, and the same toner discharge electric field as in the second embodiment is used. The application was performed at the same timing as in the example, and this was repeated for two cycles, thereby forming a total of 300,000 sheets of images. As for the experimental environment, as in Examples 1 and 2, normal temperature and normal humidity (20 ° C., 50% relative humidity) up to 50,000 sheets, high temperature and high humidity (30 ° C., relative humidity 80 % 9, and this was repeated two cycles to form a total of 300,000 sheets of images.

The experimental environment was 5 as in the case of Example 1.
Room temperature and humidity (20 ° C, relative humidity 50%) up to 10,000 sheets, high temperature and high humidity (30 ° C, relative humidity 8
0%).

(3) As a comparative example, an image forming experiment was performed under the following conditions. * Comparative Example 1 +60 on the cleaning roller throughout the entire image forming process
An image was formed under the same conditions as in the example except that a toner recovery voltage of 0 V was applied. In the comparative example, no toner discharge voltage is applied.

In Examples 1 and 2, good and stable cleaning performance was exhibited without the occurrence of image defects due to the turning of the cleaning blade, chatter and abrasion of the photosensitive member until the completion of image formation on 300,000 sheets. In the third embodiment, no image defect occurs due to the turning of the cleaning blade or the abrasion of the photoconductor until the image formation of 300,000 sheets is completed.
In particular, there is no chatter of the blade under high temperature and high humidity,
The cleaning performance was extremely good and stable.

On the other hand, in the comparative example, the cleaning blade was turned up at 60,000 sheets after the start of image formation under high temperature and high humidity. When image formation was continued after replacing the cleaning blade, cleaning failure due to chatter occurred at the time of image formation of 240,000 sheets, and stable cleaning performance was not obtained.

[0089]

According to the present invention, claims 1, 2, 3, 4, 5, 7, 8, 9
According to the inventions of (10) and (10), there is no chattering or curling of the cleaning blade, and an excellent cleaning effect can be obtained over a long period of time.

According to the sixth and eleventh aspects of the present invention, chattering and turning of the cleaning blade can be well prevented, and an excellent cleaning effect can be obtained over a long period of time.

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

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

According to the fourteenth aspect of the present invention, the image carrier has excellent cleaning performance and the life of the image carrier is extended.
A highly durable image forming apparatus can be manufactured.

According to the inventions of claims 15 and 16, excellent cleaning performance can be obtained, and furthermore, the occurrence of blade turning is prevented.

According to the seventeenth aspect of the present invention, there is provided an image forming apparatus capable of forming a high-quality image without causing chattering or turning of the cleaning blade, and without causing image stains and fogging for a long period of time. You.

According to the eighteenth aspect, a low-cost image forming apparatus capable of forming a high-quality image is realized.

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

[Brief description of the drawings]

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

FIG. 2 is a diagram illustrating a relationship between the number of formed images and a toner collection voltage.

FIG. 3 is a diagram illustrating a cleaning device.

FIG. 4 is a diagram illustrating an image forming apparatus according to a second embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 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, 86, 87 power supply 85 control means

Claims (19)

[Claims] An electroconductive or semiconductive cleaning roller for contacting an image carrier carrying a toner; a power supply for applying a toner collection voltage to the cleaning roller; a control unit for controlling the power supply; A cleaning blade that is located downstream of a roller in the moving direction of the image carrier and is in contact with the image carrier; and wherein the control unit is configured to control the toner whose absolute value increases in accordance with an increase in the amount of image formation. The cleaning device controls the power supply so that a recovery voltage is applied to the cleaning roller. 2. The cleaning apparatus according to claim 1, wherein the image formation amount is the number of image formations. 3. A conductive or semiconductive cleaning roller in contact with an image bearing member carrying a toner, a power supply for applying a toner collection voltage and a toner discharge voltage to the cleaning roller, and a control for controlling the power supply. Means, and a cleaning blade downstream of the cleaning roller in the moving direction of the image carrier and in contact with the image carrier, wherein the control means is configured to control the toner collection voltage and the toner discharge voltage A cleaning device, wherein the power supply is controlled so as to be selectively applied in time. 4. The cleaning apparatus according to claim 3, wherein the toner discharge voltage is applied every time a predetermined number of images are formed. 5. The cleaning apparatus according to claim 4, wherein the toner discharge voltage is applied every time the predetermined number of images is formed, which varies according to the number of images formed. 6. The method according to claim 3, wherein the toner discharge voltage is obtained by superimposing an AC voltage on a DC voltage.
The cleaning device according to any one of the preceding claims. 7. A conductive or semi-conductive cleaning roller in contact with an image bearing member carrying charged toner, a power supply for applying a toner collection voltage and a toner discharge voltage to the cleaning roller, and controlling the power supply 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. The control unit responds to an increase in the amount of image formation. A cleaning apparatus, wherein the power supply is controlled such that the collection voltage whose absolute value increases is applied, and the toner collection voltage and the toner discharge voltage are temporally selected and applied. 8. The cleaning apparatus according to claim 7, wherein the image formation amount is the number of image formations. 9. The cleaning device according to claim 7, wherein the toner discharge voltage is applied every time a predetermined number of images are formed. 10. The cleaning apparatus according to claim 9, wherein the toner discharge voltage is applied every time the predetermined number of images is formed, which varies according to the number of images formed. 11. The method according to claim 7, wherein the toner discharge voltage is obtained by superimposing an AC voltage on a DC voltage.
The cleaning device according to any one of items 10 to 10. 12. The cleaning roller rotates at a position where it contacts the image carrier so that the contact surface moves in the same direction as the moving direction of the image carrier. The cleaning device according to any one of claims 1 to 11, wherein a ratio of a moving speed of the contact surface of the image carrier to a moving speed of the image carrier is 0.5: 1 to 2: 1. 13. The cleaning apparatus according to claim 1, further comprising a removing unit that contacts the cleaning roller and removes toner on the cleaning roller. 14. The cleaning blade is 1 g / c.
14. The cleaning device according to claim 1, wherein the cleaning device contacts the image carrier with a load of m to 30 g / cm. 15. The cleaning according to claim 1, wherein a contact angle between the image bearing member and the cleaning blade is an angle in a range of 0 ° to 40 °. apparatus. 16. The cleaning blade having a hardness of 2
2. The method according to claim 1, wherein the angle is in a range of 0 to 90 degrees.
The cleaning device according to any one of Items 1 to 15, wherein 17. An image forming apparatus comprising an image carrier and the cleaning device according to claim 1. Description: 18. The image bearing member is an organic photosensitive member, a charging device for charging the organic photosensitive member, an exposing device for exposing the charged organic photosensitive member, and a device formed on the organic photosensitive member by charging and exposing. 18. The image forming apparatus according to claim 17, further comprising a developing device that develops the formed electrostatic latent image and attaches the charged toner to form an image. 19. The developing device according to claim 19, wherein the volume average particle diameter is 3.
The image forming apparatus according to claim 18, wherein the development is performed using a toner having particles formed by a polymerization method of 0 μm to 8.5 μm.