JP2015230472A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus capable, even in a state where an external additive and the like stuck to a photoreceptor on a contact surface between the photoreceptor and a cleaning blade is stuck in a low image output, of removing them without consuming a toner during no image formation.SOLUTION: The image forming apparatus includes: an image carrier carrying a toner on an electrostatic latent image part; a cleaning blade 72 disposed in contact with the image carrier; an attachment removal member disposed at an upstream side in the rotation direction of the image carrier with respect to the cleaning blade 72, and having a contacting/separating mechanism with respect to the image carrier; a drive source for driving the image carrier and the attachment removal member; and calculation means for calculating an image area ratio of an output image. The image carrier is inversely operated by a distance from a contact point of the cleaning blade 72 and the image carrier to a contact point of the attachment removal member and the image carrier and, as for the execution condition of the attachment removal operation, when the output image is a low image area ratio, controlled to a condition where the attachment is more easily removed than that in a high image area ratio.

Description

  The present invention relates to an image forming apparatus having a technique for removing deposits.

  The photoreceptor used in the electrophotographic image forming apparatus adheres to a discharge product in the charging process, silica as an external additive component of the toner, and the like. The problem is that an abnormal image is output due to these deposits. For this reason, a technique for applying a lubricant to a photoconductor is already known for the purpose of protecting the surface layer or reducing the friction coefficient of the surface to make it difficult for deposits to adhere.

  Also, in order to remove the deposits on the photoconductor, the image area ratio of the output image is calculated, and according to the result, the toner is input to the cleaning device at the time of non-image formation only when necessary so that the surface of the photoconductor A method of removing deposits is already known.

  Patent Document 1 discloses the purpose of realizing the toner consumption while minimizing the toner consumption only when it is necessary to remove the adhering matter to the photosensitive member such as paper powder and talc contained in the paper and the intermediate transfer member. A configuration is disclosed in which the deposit removal mode is executed according to the number of times of image formation, temperature and humidity, and the image area ratio.

  However, the conventional deposit removal method and the technique disclosed in Patent Document 1 consume the toner during non-image formation, and thus there is a problem that the cost increases.

  In addition, toner and toner external additives that have entered the contact surface between the photosensitive member and the cleaning blade increase the amount of toner external additive when the amount of toner input to the blade is small, and the toner is firmly attached to the photosensitive member. It adheres and becomes easy to grow to medaka filming.

  That is, when the output image has a low image area, toner and toner external additives that have entered the contact surface between the photosensitive member and the cleaning blade tend to directly cause medaka filming. In such a case, there has been a problem that the adhering matter that has entered the contact surface between the photosensitive member and the cleaning blade cannot be sufficiently removed only by the toner input to the blade, which is the conventional adhering matter removing method.

  The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide an external additive attached to the photosensitive member at the contact surface between the photosensitive member and the cleaning blade without consuming toner during non-image formation. An object of the present invention is to provide an image forming apparatus capable of removing agents and the like even when they are attached at the time of low image output.

  In order to achieve this object, the present invention has the following features.

  An image forming apparatus according to the present invention includes an image carrier that carries toner on an electrostatic latent image portion, a cleaning blade that is disposed in contact with the image carrier, and an upstream side in the rotation direction of the image carrier from the cleaning blade. An adhering matter removing member disposed and having a contact / separation mechanism with respect to the image carrier, a drive source for driving the image carrier and the adhering matter removing member, and a calculating means for calculating an image area ratio of the output image; The image carrier is reversely operated by a distance from a contact point between the cleaning blade and the image carrier to a contact point between the deposit removing member and the image carrier, and the output image is a high image. When the image area ratio is lower than that at the area ratio, the execution condition of the deposit removal operation is controlled to a condition that the deposit is easily removed.

  According to the present invention, the external additive attached to the photoconductor on the contact surface between the photoconductor and the cleaning blade does not consume toner at the time of non-image formation, even in the state where the external additive is attached to the photoconductor at the time of low image output. Can be removed.

1 is a schematic diagram illustrating a configuration of an image forming apparatus according to an exemplary embodiment. 1 is a partial cross-sectional view of an image forming apparatus according to an embodiment. FIG. 2 is a block diagram illustrating functions of the image forming apparatus according to the present embodiment. It is a figure explaining the medaka filming generation | occurrence | production mechanism. It is a figure explaining the deposit removal operation | movement of the image forming apparatus which concerns on this embodiment. It is a flowchart which shows a deposit | attachment removal operation | movement. It is a figure which shows image area ratio Sn in each area | region. It is a flowchart which shows a deposit | attachment removal operation | movement. It is a figure which shows a deposit | attachment removal operation condition table.

  Hereinafter, the present embodiment will be described in detail with reference to the drawings.

  FIG. 1 is a schematic diagram illustrating a configuration of an image forming apparatus according to the present embodiment. The image forming apparatus includes four image forming units 1Y, 1C, 1M, and 1K for generating yellow, cyan, magenta, and black (hereinafter referred to as Y, C, M, and K) toner images. These image forming units 1 use different colors of Y toner, C toner, M toner, and K toner, but other configurations are common to four colors. Here, the image forming unit 1Y using Y toner will be described as an example.

  A schematic diagram of the image forming unit 1Y is shown in FIG. The image forming unit 1Y includes a photosensitive unit 2Y and a developing unit 7Y, and is detachable integrally with the main body of the image forming apparatus.

  The photoreceptor unit 2Y includes a drum-shaped photoreceptor 3Y that is a latent image carrier, a drum cleaning device 4Y, a charging device, and the like. The charging device uniformly charges the surface of the photoreceptor 3Y rotating in the clockwise direction in FIG. 2 by a driving means (not shown). FIG. 2 shows a method of charging the surface of the photoreceptor 3Y by applying a charging bias to the charging roller 6Y that is close to the photoreceptor 3Y. However, other than the charging roller method, a charging brush method or a scorotron method may be used.

  The drum cleaning device 4Y includes a cleaning blade 15Y and a waste toner conveying screw 16Y, and removes and collects transfer residual toner and the like attached to the photoreceptor 3Y. The photoreceptor unit 2Y also includes a lubricant application brush 17Y and a lubricant 18Y for setting the surface friction coefficient of the photoreceptor 3Y to predetermined values, and a lubricant application blade 19Y for uniformly applying the lubricant 18Y on the photoreceptor 3Y. And.

  In FIG. 1, an optical writing unit 20 is provided below the image forming unit 1. The optical writing unit 20 irradiates the photoreceptor 3 of the image forming unit 1 with laser light L based on the image information. As the configuration of the optical writing unit 20, FIG. 1 shows a configuration in which a laser beam L emitted from a light source is irradiated to a photosensitive member 3 through a plurality of lenses and mirrors while being deflected by a polygon mirror 21 that is rotationally driven by a motor. . However, an LED array method can be used in addition to such a polygon scanning method.

  Returning to FIG. 2, the surface potential of the photoreceptor 3 </ b> Y decreases only in the area exposed by the laser beam L, and an electrostatic latent image is formed. The electrostatic latent image is conveyed to the developing area facing the developing roller 12Y of the developing unit 7Y as the photoconductor 3Y rotates.

  The developing unit 7Y includes a first transport screw 8Y, a toner concentration sensor 10Y including a magnetic permeability sensor, a first developer circulation transport passage 9Y provided with a toner supply port (not shown), a dispersion mug, and the like, and a second And a second developer circulation conveyance path 14Y provided with a conveyance screw 11Y, a developing roller 12Y, a doctor blade 13Y, and the like. The developer circulation transport passages 9Y and 14Y are connected by connecting ports at both ends, and contain a Y developer (not shown) composed of negatively charged Y toner and a magnetic carrier.

  The first transport screw 8Y is rotated by a driving means (not shown) to transport the Y developer in the first transport path 9Y from the back side to the front side in the direction perpendicular to FIG. The Y developer conveyed to the front side moves to the second conveyance path 14Y through a communication port (not shown) on the front side. The second transport screw 11Y rotates in the same manner, and transports the Y developer that has entered the second transport path 14Y from the near side to the far side in FIG. The Y developer in the middle of conveyance is detected by the toner concentration sensor 10Y fixed to the bottom of the first conveyance path 9Y.

  Above the second conveyance path 14Y, a developing roller 12Y is arranged in parallel with the second conveyance screw 11Y. The developing roller 12Y includes a non-magnetic developing sleeve that rotates counterclockwise in FIG. 2 and a non-rotating magnet roller that is included in the developing sleeve. A part of the Y developer transported in the second transport path 14Y is pumped up to the surface of the developing sleeve by the magnetic force of the magnet roller. The developing sleeve is provided with a doctor blade 13Y that is opposed to each other while holding a minute gap, and the layer thickness (pumping amount) of the pumped-up Y developer is regulated when passing through the doctor blade 13Y.

  The Y developer that has passed through the doctor blade 13Y is transported to a developing area facing the photoreceptor 3Y. Due to the potential difference between the developing potential applied to the developing sleeve and the surface potential of the exposed portion of the photoreceptor 3Y, only the Y toner in the Y developer conveyed to the developing region adheres only to the exposed portion of the photoreceptor 3Y. As a result, a Y toner image is formed on the photoreceptor 3Y.

  The Y developer that has consumed Y toner due to the development is returned to the second transport path 14Y, transported to the back side in FIG. 2 by the second transport screw 11Y, and transferred to the first transport path 9Y by the communication port on the back side. Moving. The Y developer that has returned to the first transport path 9Y is newly supplied with toner at a toner supply port (not shown). There is a dispersion mug downstream of the toner supply port, and the developer drawn from the transport passage 9Y forms a wall. The replenishment toner is blocked by the developer wall and dispersed in the developer. The Y developer in which the replenishment toner is sufficiently dispersed is conveyed again to the front side in FIG. 2 by the first conveyance screw 8Y.

  The Y toner image formed on the photoreceptor 3Y is intermediately transferred to the intermediate transfer belt 41 in FIG. Waste toner remaining on the surface of the photoreceptor 3Y after the intermediate transfer is removed by the drum cleaning device 4Y. The photoreceptor 3Y from which the waste toner has been removed is neutralized by a neutralizing device (not shown), and is directed to a charging device in order to perform the next image formation.

  In FIG. 1, a first paper feed cassette 31 and a second paper feed cassette 32 are provided below the optical writing unit 20. A plurality of recording papers P are stored in these paper feeding cassettes, and the first paper feeding roller 31a and the second paper feeding roller 32a are applied to the uppermost recording paper P, respectively. It touches. By driving these paper feed rollers 31 a and 32 a counterclockwise, the uppermost recording paper P in the paper feed cassettes 31 and 32 is discharged to the paper feed path 33. The recording paper P is conveyed upward by the conveying roller pair 34, temporarily stops at the position of the registration roller pair 35, and then at a suitable timing, the secondary transfer nip (the contact between the secondary transfer roller 50 and the secondary transfer facing roller 46). It is conveyed to.

  An intermediate transfer unit 40 that rotates the intermediate transfer belt 41 counterclockwise is disposed above the image forming unit 1. The intermediate transfer unit 40 includes an intermediate transfer belt 41, a belt cleaning unit 42, primary transfer rollers 45Y, 45C, 45M, and 45K, a secondary transfer opposing roller 46, a drive roller 47, and the like. The intermediate transfer belt 41 is rotated counterclockwise by the driving roller 47.

  The four primary transfer rollers 45 sandwich the intermediate transfer belt 41 to form primary transfer nips with the corresponding color photoreceptors 3. The primary transfer roller 45 applies a primary transfer bias to the inside of the intermediate transfer belt 41. Due to the potential difference between the primary transfer roller 45 and the photoreceptor 3, the toner image on the photoreceptor 3 is transferred to the intermediate transfer belt 41 at the primary transfer nip portion. At the primary transfer nip of each color, a Y toner image, a C toner image, an M toner image, and a K toner image are sequentially transferred to the intermediate transfer belt 41, and the four-color toner in which the four-color toner images are superimposed on the intermediate transfer belt 41. An image is formed.

  The secondary transfer facing roller 46 is provided at a position facing the secondary transfer roller 50, and both of them sandwich the intermediate transfer belt 41 to form a secondary transfer nip. In accordance with the timing of the four-color toner image formed on the intermediate transfer belt 41, the registration roller pair 35 conveys the recording paper P to the secondary transfer nip. A secondary transfer bias is applied between the secondary transfer opposing roller 46 and the secondary transfer roller 50, and the four-color toner image on the draft transfer belt 41 is secondarily transferred onto the transfer paper P by that force. The Then, combined with the white color of the recording paper P, a full color toner image is obtained. The waste toner remaining on the intermediate transfer belt 41 after passing through the secondary transfer nip is removed by the belt cleaning unit.

  A fixing unit 60 is provided above the secondary transfer nip. The fixing unit 60 includes a pressure roller 61 including a heat source such as a halogen lamp, and a fixing belt unit 62. Further, the fixing belt unit 62 includes a fixing belt 64, a heating roller 63 containing a heat source such as a halogen lamp, a driving roller 66, and the like. The fixing belt 64 rotates counterclockwise by the driving roller 66 and is heated by the heating roller 63 to be maintained at a constant temperature (for example, 140 ° C.). The pressure roller 61 also rotates clockwise and is heated by an internal heat source and maintained at a constant temperature (for example, 120 ° C.).

  The fixing belt 64 and the pressure roller 61 are in contact with each other to form a fixing nip. The recording sheet P that has passed through the secondary transfer nip and has a full-color toner image thereon is conveyed to the fixing nip in the fixing unit 60. The full-color toner image is fixed on the recording paper P by being heated and pressurized at the fixing nip. The recording paper P on which the toner image is fixed passes through a pair of paper discharge rollers 67 and is discharged to a paper discharge stack unit 68 outside the apparatus.

  Above the intermediate transfer unit 40, four toner cartridges 100Y, 100C, 100M, and 100K that respectively store Y toner, C toner, M toner, and K toner are provided. Each color toner in the toner cartridge 100 is supplied to the developing unit 7 from a toner supply port (not shown) through a supply path (not shown). These toner cartridges 100 are detachable from the image forming apparatus main body independently of the image forming unit 1.

  FIG. 3 is a block diagram illustrating functions of the image forming apparatus according to the present embodiment. The image forming apparatus includes a CPU 91, a calculation unit 92, a storage unit 93, a drive unit 94, and a cam mechanism 95. The calculation unit 92, the storage unit 93, the drive unit 94, and the cam mechanism 95 are connected to the CPU 91. The storage unit 93 stores a deposit removal operation execution condition table 96.

  FIG. 4 is a diagram illustrating a mechanism for generating medaka filming. As shown in FIG. 4A, when residual toner that has not been transferred in the transfer process or toner 71 due to soiling enters the cleaning blade 72, they are cleaned and transported to the waste toner transport path. Silica 73 which is an external additive 71 is released from the toner 71 and enters and stays in the nip portion 74 of the cleaning blade 72 and the photoreceptor 3.

Thereafter, as shown in FIG. 4B, when the silica 73 is pressed against the photoreceptor 3 by the contact pressure of the cleaning blade 72, the retained silica 73 aggregates and adheres to the photoreceptor 3.
Thereafter, when the apparatus is operated for a longer period, an aggregate of silica 73 pressed by the cleaning blade 72 grows. Although it is not output as an abnormal image in the initial stage, if the agglomerated silica 73 grows by operating the apparatus for a long period of time, uniform charging of the photosensitive member 3 is hindered, the toner image does not remain, white spots, etc. The problem of becoming an abnormal image has occurred.

  The agglomerated silica 73 shown in FIG. 4B is weakly fixed to the photoconductor 3 in the initial state, and is easily removed from the photoconductor by a removing member or the like. However, when the apparatus is operated for a long period of time and the agglomerated silica 73 has grown, the state of fixing to the photoreceptor 3 becomes strong and difficult to remove.

  Further, as shown in FIG. 4C, when the toner 71 is sufficiently input to the cleaning blade 72, the convection caused by the toner 71 by the toner 71 is generated in the nip portion 74, and the retained silica is retained. 73 is carried to the waste toner conveyance path along the flow of the toner 71 indicated by an arrow. However, when the input amount of the toner 71 is small, convection due to the toner 71 is difficult to occur, so that the silica 73 tends to stay in the nip portion 74 and easily grows to medaka filming.

  Therefore, in the present embodiment, the silica 73 adhered to the photoreceptor 3 before the agglomerated silica 73 grows even under severe conditions for medaka filming where the output image area ratio is low and the input amount of the toner 71 is small. The aim is to completely remove

  Strict conditions for medaka filming are that when the output image has a low image area ratio, convection due to the input toner does not occur at the nip portion between the photosensitive member and the cleaning blade, and toner or silica is likely to stay. Therefore, the deposits are easy to grow.

Next, the deposit removal operation will be described. FIG. 5 is a diagram for explaining the deposit removal operation of the image forming apparatus according to the present embodiment.
The image forming apparatus includes a developing roller (not shown) that carries a developer on its surface, a photosensitive blade 3 that is an image carrier, a cleaning blade 72 for removing residual toner, and a brush on the upstream side of the cleaning blade 72. A roller 81, a case 82 for enclosing these cleaning devices, and a waste toner conveying screw 83 for conveying the deposits removed by the cleaning blade 72 or the brush roller 81 to the waste toner path below the case 82 And are installed.

  The photosensitive member 3 is arranged so as to be able to perform a reverse rotation operation in the direction of arrow 86 and a normal rotation operation in the direction opposite to the arrow 86 by a drive unit 94 which is a photosensitive member drive motor, and the brush roller 81 is a drive unit which is a brush drive motor. 94 is disposed in contact with the photosensitive member 3 so as to be rotationally driven.

  Further, the photosensitive member 3 has a cam that pushes up the shaft of the cleaning brush 72 and separates it from the photosensitive member 3 when the photosensitive member 3 rotates forward and the rotational force is transmitted. The cam is mounted via a one-way bearing that transmits the rotational force to the cam only when the photosensitive member 3 rotates forward on the rotational shaft of the photosensitive member 3. With this configuration, the brush roller 81 is separated during the forward rotation operation during image formation, and the photosensitive member 3 rotates in the reverse direction during the deposit removal operation described later, so that the brush roller 81 is brought into contact with the photosensitive member 3. .

FIG. 6 is a flowchart showing the deposit removal operation. The pixel number information is integrated (step S11), the image area ratio is compared with a predetermined value according to the image area ratio of the output image calculated from the value (step S12), and the execution condition is controlled (step S13). ).
At the time of non-image formation, the brush roller 81 as a removing member is separated (step S14). At this time, the photosensitive member 3 is reversely operated by the distance a in the direction of the arrow 86 in FIG. 5 (step S15). Non-image formation is a time other than normal image formation.

  The distance a is a distance from the tip edge portion 85 of the cleaning blade 72 to the contact point between the photosensitive member 3 and the brush roller 81 as shown in FIG. The photoreceptor 3 rotates in the direction of arrow 86. When the adhering matter adhering to the photoconductor 3 on the contact surface between the photoconductor 3 and the cleaning blade 72 moves to the position of the brush roller 81, the brush roller 81 is brought into contact with the photoconductor 3 (step S16).

  Thereafter, the brush roller 81 is rotationally driven to remove the deposits on the photoreceptor 3 (step S17). After completion of the deposit removal operation, the brush roller 81 is separated again (step S18). Accordingly, it is possible to remove the adhering matter attached to the photosensitive member 3 at the contact surface between the photosensitive member 3 and the cleaning blade 72 described with reference to FIG.

  The above deposit removal operation integrates the pixel number information obtained by the CPU 91, and the execution condition is controlled according to the image area ratio of the output image calculated from the value. When the image area ratio is low, that is, when the acquired image area ratio is less than or equal to the predetermined value S, the contact surface between the photosensitive member and the cleaning blade is set by making the condition for performing the deposit removal operation easy to remove deposits. Thus, it is possible to remove the adhered matter firmly adhered to the photoreceptor 3. The condition that the deposits are easily removed is to increase the rotation time, rotation speed, amount of biting, and the like of the brush roller 81.

  In addition, when the image area ratio is high, it is possible to suppress the wear of the photosensitive member 3 due to the rubbing of the brush roller 81 and to extend the life by suppressing the deposit removing operation to the minimum necessary. Therefore, it is desirable not to execute the deposit removal operation when the image area ratio is equal to or greater than a predetermined value. In addition, it is desirable that the calculation of the image area ratio and the execution of the deposit removal operation be performed after printing is completed in order to shorten the waiting time of the machine user.

  Depending on the image area ratio of the output image, by controlling the execution condition of the deposit removal operation at a low image area to a condition that the deposit is easy to be removed, even when the external additive or the like is firmly attached to the photoreceptor, A good surface state of the photoreceptor can always be maintained.

When the image area ratio is high, by suppressing the deposit removing operation to the minimum necessary, the wear of the photosensitive member due to the rubbing of the removing member can be suppressed and the life can be extended. Moreover, the effect that the waiting time of the apparatus user can be minimized can be obtained.
The operation for removing the adhered matter composed of the above operations can control the execution condition to be a condition in which the adhered matter is easily removed when the output image has a low image area ratio than when the output image has a high image area ratio.

  FIG. 7 is a diagram showing the image area ratio Sn in each region. A means for calculating an image area ratio of each region divided into n in the photosensitive member axis direction; The execution condition of the deposit removal operation is controlled in accordance with the results of the image area ratios S1 to Sn in each region obtained in this way.

  For example, when the minimum value Smin of the image area ratio of each region is equal to or less than a predetermined value S, the condition for executing the deposit removal operation is set to a condition that allows deposits to be easily removed, so that the contact surface between the photoreceptor and the cleaning blade can be removed. Thus, it is possible to remove deposits firmly attached to the photoreceptor. When any one of S1 to Sn is equal to or less than S, the condition that the deposit is easily removed is applied.

  Even in the case of an image with a high image area ratio, if there is a portion with a low image area in the image, the corresponding portion is a severe condition for medaka filming, and deposits such as external additives tend to grow. By the above method, the deposits can be removed without overlooking a portion more severe with respect to the adhesion of the external additive or the like in the direction of the photosensitive member axis.

  FIG. 8 is a flowchart showing the deposit removal operation. FIG. 9 is a diagram showing a deposit removal operation condition table. FIG. 8 differs from FIG. 6 in the case where the deposit removal operation is performed with the divided image area ratio.

  After the printing is completed, the image area ratios S1 to Sn in each area printed immediately before are acquired, and the minimum value Smin is acquired (step S21). The reason for referring to the minimum value is to control the execution condition of the deposit removal operation in accordance with the location where the input amount of toner is the smallest in the axial direction of the photosensitive member, that is, the location where medaka filming is most likely to occur.

  Thereafter, the deposit removal operation execution condition table stored in the storage unit 93 shown in FIG. 9 is referred to, and the rotation time Tsec of the brush roller 81 is determined to an experimentally obtained value (T1 to T4) according to Smin. (Step S22). The smaller the Smin, the more deposits on the photoreceptor 3 and the stronger the adherence state. Therefore, by increasing the rotation time, the capability of the deposit removal operation can be increased and the deposits can be removed. (Step S23).

  The execution condition of the deposit removal operation controls the execution time T of the deposit removal operation according to the image area ratio in each divided area. When any one of S1 to Sn is equal to or less than S, the execution time T is controlled according to the image area ratio.

  By this method, even when an external additive or the like is firmly attached to the photoconductor, it is possible to easily increase the removal capability without increasing the complexity of the cleaning device only by increasing the rotation time.

  Further, the brush roller 81 can change the contact position with the photosensitive member 3 stepwise by a cam mechanism 95. After obtaining the minimum value Smin, referring to the deposit removal operation execution condition table shown in FIG. 9, the biting amount α of the brush roller 81 is determined to be an experimentally obtained value (T1 to T4) according to Smin, Change the contact position.

The smaller the Smin is, the more adhered matter to the photosensitive member 3 and the stronger the attached state. Therefore, by increasing the amount of bite, the contact pressure to the photosensitive member 3 is increased and the ability to remove the adhered matter is increased. The deposit can be removed.
By this method, even when an external additive or the like is firmly attached to the photoconductor, only the contact pressure is increased, so that the attached matter can be removed in a short time without taking a long time.

Further, after acquiring the minimum value Smin, the rotational speed v of the brush roller is determined (v1 to v4) according to Smin with reference to the deposit removal operation execution condition table shown in FIG. The rotation speed is a value obtained through experiments, and is stored in the deposit removal operation execution condition table 96 of the storage unit 93 shown in FIG. When any one of S1 to Sn is equal to or less than S, the rotation speed v is controlled according to the image area ratio.
The smaller the Smin is, the more deposits are on the photoconductor and the stronger the adherence state is. Therefore, by increasing the rotational speed, the capability of the deposit removal operation can be increased and the deposits can be removed.

  With this method, even when an external additive or the like is firmly attached to the photoconductor, the rotational speed is only increased, so that it is not necessary to make the cleaning device complicated, and the removal capability can be easily enhanced and shortened. Removal of deposits can be performed in time.

  According to the present embodiment, the deposit removal operation is performed in which the photoreceptor is reversed by a predetermined amount to the position of the removal member arranged on the upstream side of the cleaning blade, and the deposit on the surface of the photoreceptor is removed by the removal member. The execution condition of the deposit removal operation is controlled according to the output image area ratio, and is made stronger in the case of a low image area ratio.

  Therefore, the external additive attached to the photosensitive member at the contact surface between the photosensitive member and the cleaning blade can be removed even when the low image output is performed without consuming toner during non-image formation. Can do.

  The above-described embodiment shows an example of a preferred embodiment of the present invention, and the present invention is not limited thereto, and various modifications can be made without departing from the scope of the invention. is there.

3 Photoreceptor 71 Toner 72 Cleaning Blade 73 Aggregated Silica 74 Nip Portion 81 Brush Roller 82 Case 83 Waste Toner Transport Screw 85 Tip Edge Portion 91 CPU
92 Calculation unit 93 Storage unit 94 Drive unit 95 Cam mechanism 96 Adherent removal operation execution condition table

Japanese Patent No. 4749152

Claims (6)

An image carrier that carries toner on the electrostatic latent image portion;
A cleaning blade disposed in contact with the image carrier;
An adhering matter removing member disposed upstream of the cleaning blade in the rotation direction of the image carrier and having a contact / separation mechanism with respect to the image carrier;
A drive source for driving the image carrier and the deposit removing member;
Calculating means for calculating the image area ratio of the output image,
The image carrier is reversely operated by a distance from a contact point between the cleaning blade and the image carrier to a contact point between the deposit removing member and the image carrier,
An image forming apparatus, wherein when the output image has a lower image area ratio than when the output image has a high image area ratio, the execution condition of the deposit removal operation is controlled to a condition in which the deposit is easily removed.   The adhering member removing member is separated from the image carrier, and after the image carrier is rotated in reverse, it is brought into contact with the image carrier, rotated for a predetermined time, and stopped, and separated from the image carrier. The image forming apparatus according to claim 1, wherein: Means for calculating an image area ratio in each region divided in the axial direction of the image carrier;
3. The method according to claim 1, wherein when the image area ratio in any one of the regions is lower than a predetermined value, the execution condition of the deposit removal operation is controlled to a condition in which deposits are easily removed. Image forming apparatus.   The image forming apparatus according to claim 3, wherein the execution condition controls an execution time T of the deposit removal operation according to an image area ratio in each divided region. A cam mechanism for adjusting a contact position of the deposit removing member;
The image forming apparatus according to claim 3, wherein the execution condition controls a contact pressure of the deposit removing member to the image carrier in accordance with an image area ratio in each divided region.   The image forming apparatus according to claim 3, wherein the execution condition controls a rotation speed of the deposit removing member according to an image area ratio in each divided area.

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