JP2021139941A - Image forming apparatus - Google Patents

Abstract

To provide an image forming apparatus that can prevent leakage of toner at the ends of a blade cleaner.SOLUTION: In an image forming apparatus that transfers a toner image formed on an outer peripheral surface of a photoreceptor drum 210 to a transfer target body, a static eliminating lamp 202 eliminating static electricity on the outer peripheral surface of the photoreceptor drum 210 after the image transfer has a center part LED 301c and both end LEDs 301e. Prior to scraping off a residual toner from the outer peripheral surface after the elimination of static electricity by using a cleaning blade 201, when leakage of toner at the ends easily occurs, the both end LEDs 301e are turned off, and the center part LED 301c is not caused to eliminate static electricity at the ends in the axial direction of the photoreceptor drum 210. Thus, by an electrostatic repulsive force against the residual toner having the same polarity as a surface electric charge remaining in a non-static eliminating area 602, the residual toner is moved to the end sides to prevent the occurrence of leakage of toner at the ends.SELECTED DRAWING: Figure 6

Description

The present disclosure relates to an electrophotographic image forming apparatus, and more particularly to a technique for preventing edge toner leakage when cleaning the outer peripheral surface of a photoconductor drum using a cleaning blade.

The electrophotographic image forming apparatus electrostatically transfers the toner image formed on the surface of the photoconductor to an object to be transferred such as a recording sheet or an intermediate transfer body. Since the transfer efficiency of toner from the surface of the photoconductor to the object to be transferred is less than 100%, a part of the toner remains on the surface of the photoconductor after electrostatic transfer and becomes residual toner. If the residual toner is mixed with the toner image to be formed next, the image quality is deteriorated. Therefore, a cleaning device for cleaning the residual toner on the surface of the photoconductor is provided.

The cleaning device includes, for example, a brush roller in order to recover the residual toner from the surface of the photoconductor (see, for example, Patent Document 1). The brush roller can obtain high cleaning performance and reliability even if it is a high-end model with a high process speed.

JP-A-2010-026059 Japanese Unexamined Patent Publication No. 2010-128149

In recent years, there has been an increasing demand for an office environment that is comfortable to work in, and in order to meet this demand, space saving of office equipment is further accelerating. Multi-function peripherals (MFPs), which are often installed in offices, are also required to be miniaturized, and it is urgent to solve various technical problems.

In response to such demands, cleaning devices using brush rollers (brush cleaners) are difficult to miniaturize, and it is not always easy to control costs, power consumption, and noise, so it is hard to say that they are optimal for office use. .. On the other hand, a cleaning device (blade cleaner) using a cleaning blade is easier to configure than a brush cleaner, is suitable for miniaturization and low cost, and is widely used from popular machines to high-end machines.

In the blade cleaner, during cleaning, residual toner on the surface of the photoconductor is applied from the center to both ends in the longitudinal direction of the cleaning blade along the cut surface of the cleaning blade (the contact position between the cleaning blade and the surface of the photoconductor). Tends to spread towards. In the example shown in FIG. 7, the cleaning blade 701 is in contact with the outer peripheral surface of the photoconductor drum 702 rotating in the direction of arrow X, and the residual toner 703 on the outer peripheral surface of the photoconductor drum 702 is the photoconductor drum 702. It is conveyed toward the cleaning blade 701 by rotation.

The residual toner 703 continues to be pressed against the cleaning blade 701 by the rotation of the photoconductor drum 702 even after being dammed by the cleaning blade 701 like the residual toner 704. As a result, the residual toners 705, 706, and 707 are pushed out in the Y direction of the arrow, and thus spread from the central portion to both ends in the longitudinal direction of the cleaning blade 701.

When the residual toner 707 reaches both ends of the cleaning blade 701, the residual toner 708 leaks out of the cleaning range of the cleaning blade 701 as shown by the dashed line region 712 that expands the inside of the broken line region 711 (end toner leakage). ..

When the blade cleaner is miniaturized, the space for holding the residual toner scraped off by the cleaning blade 701 from the outer peripheral surface of the photoconductor drum 702 is narrowed, so that toner leakage at the end is likely to occur. Leakage of toner at the ends may stain each part of the device, stick to mechanical parts such as gears and cause malfunction, or cause electrical contact failure, which deteriorates image quality. Can be the cause.

The present disclosure has been made in view of the above-mentioned problems, and an object of the present disclosure is to provide an image forming apparatus capable of preventing edge toner leakage in a blade cleaner.

In order to achieve the above object, the image forming apparatus according to one embodiment of the present disclosure is an image forming apparatus that transfers a toner image formed on the outer peripheral surface of a photoconductor drum to a transfer target, and is a photoconductor after the image transfer. A static elimination means for removing static electricity from the outer peripheral surface of the drum, a cleaning blade for scraping residual toner from the outer peripheral surface after static elimination, and a determining means for determining whether or not toner leakage from the blade end is likely to occur during scraping. If the determination result is positive, only the central portion excluding the end region in the axial direction of the photoconductor drum is statically eliminated, and if the determination result is negative, the shaft of the photoconductor drum is removed. It is characterized by comprising a control means for controlling the static elimination means so as to eliminate static electricity over the entire range in which static elimination is possible in the direction.

In this case, the static elimination means is a light emitting element array in which a plurality of light emitting elements are arranged in a row along the axial direction, and the control means is the shaft when the determination result is positive. The light emitting element that eliminates static electricity in the end region in the direction is turned off, only the light emitting element that eliminates static electricity in the central portion is turned on, and if the determination result is negative, all the light emitting elements are turned on. The static elimination means may be controlled.

Further, the range of the end region in the axial direction of the photoconductor drum is the maximum width in which the electrostatic latent image formed on the outer peripheral surface of the photoconductor drum can be developed in the axial direction of the photoconductor drum. It is desirable that it is outside the end of the maximum development width.

Further, a developing device for developing an electrostatic latent image formed on the outer peripheral surface of the photoconductor drum by using a developing roller that magnetically attracts a two-component developer is provided, and the maximum developing width is the developing roller. The developing magnetizing width may be a range in which the developer can be magnetically attracted in the axial direction of.

Further, it is desirable that the end region of the photoconductor drum in the axial direction is located closer to the center than the blade end.

Further, when the residual toner is scraped off by the edge portion of the cleaning blade, the determination means causes end toner leakage when the torque acting on the cleaning blade is large centering on the fixed position of the cleaning blade. It is preferable to judge that it is easy to do.

Further, a coverage acquisition means for acquiring coverage of the printed image in the transferred body may be provided, and the determination means may determine that end toner leakage is likely to occur when the coverage is larger than a predetermined threshold value. ..

Further, a speed acquisition means for acquiring the rotation speed of the photoconductor drum may be provided, and the determination means may determine that end toner leakage is likely to occur when the rotation speed is higher than a predetermined speed. ..

Further, an environmental condition acquisition means for acquiring the environmental temperature and the environmental humidity of the photoconductor drum may be provided, and the determination means may determine that edge toner leakage is likely to occur in a low temperature and low humidity environment. ..

In this way, when it is determined that toner leakage at the end is likely to occur, the end of the photoconductor drum in the axial direction is not statically removed, so that the electrostatic repulsive force with the surface charge remaining at the end ( The repulsive force) makes it difficult for the residual toner to move toward the end, and it is possible to prevent the end toner from leaking.

It is an external perspective view which shows the main structure of the image forming apparatus 1 which concerns on embodiment of this disclosure. It is a figure which shows the main structure of the image-forming part 100. It is a figure which shows the main structure of the cleaning device 200. It is a block diagram which shows the main structure of the control part 110. It is a flowchart explaining the operation of the control unit 110. It is a figure explaining the relationship between the lighting state of the static elimination lamp 202, and the surface potential of a photoconductor drum 210. It is a figure explaining the generation mechanism of end toner leakage.

Hereinafter, embodiments of the image forming apparatus according to the present disclosure will be described with reference to the drawings.
[1] Configuration of Image Forming Device First, the configuration of the image forming apparatus according to the present embodiment will be described.

As shown in FIG. 1, the image forming apparatus 1 according to the present embodiment is a so-called tandem type multifunction device, and includes an image reading unit 120, an image forming unit 130, a paper feeding unit 140, and an operation panel 150. There is.

The image reading unit 120 includes an automatic document feeding device (ADF: Automatic Document Feeder) 121 and a scanner device 122, and uses the automatic document feeding device 121 to take a document from a bundle of documents placed on a document tray 123. Images are read from the original using the scanner device 122 while conveying the sheets one by one (sheet-through method). The scanned document is ejected onto the output tray 124. Further, the image reading unit 120 can also read an image from a document placed on a platen glass (not shown) by using a scanner device 122 (platen set method).

The image forming unit 130 includes image forming units 100Y, 100M, 100C and 100K that form toner images of yellow (Y), magenta (M), cyan (C) and black (K) colors. The image-creating units 100Y, 100M, 100C, and 100K all have the same configuration, and as shown in FIG. 2, the charging device 211, the exposure device 212, and the developing device are sequentially provided along the outer peripheral surface of the photoconductor drum 210. 213, a primary transfer roller 216 and a cleaning device 200 are arranged.

The photoconductor drum 210 has a photoconductor layer formed on the outer peripheral surface thereof, and is rotationally driven in the direction of arrow B by a drive source (not shown). The charging device 211 uniformly charges the outer peripheral surface of the photoconductor drum 210 (for example, −600 V). Although the charging roller is illustrated as the charging device 211 in FIG. 2, a device other than the charging roller such as a charging wire may be used.

The exposure apparatus 212 irradiates the outer peripheral surface of the photoconductor drum 210 with a laser beam modulated according to the RIP (Raster Image Processor) data of the color. As a result, when the photoconductor conducts in the normal direction of the outer peripheral surface and the surface charge disappears at the portion of the outer peripheral surface of the photoconductor drum 210 irradiated with the laser beam, an electrostatic latent image is formed.

The RIP data for each color of YMCK is generated by the control unit 110 using the image data specified in the image forming job. The RIP data is data in which the presence or absence of laser light irradiation is specified for each main scanning line for each pixel on the main scanning line. The larger the number of pixels to be irradiated with the laser beam in the RIP data, the wider the region on the outer peripheral surface of the photoconductor drum 210 where the surface charge has disappeared.

The developing device 213 supplies toner to the outer peripheral surface of the photoconductor drum 210. In the present embodiment, a case where a two-component developer containing toner and a carrier is used is taken as an example, and in the present embodiment, the developer is stirred and conveyed in the developing apparatus 213. The toner is negatively charged. When the toner is positively charged, not only the charged charge of the toner but also all the charging polarities in the present embodiment may be reversed.

The developing apparatus 213 supplies toner by using a developing roller 216 having a maglor 215 inserted in the developing sleeve 214. The carrier in the developing agent is adsorbed on the outer peripheral surface of the developing sleeve 214 by the magnetic force of the maglor 215, so that the toner adhering to the carrier is also adsorbed on the outer peripheral surface of the developing sleeve 214.

The developing sleeve 214 is rotationally driven by a drive source (not shown), and the toner adsorbed on the outer peripheral surface of the developing sleeve 214 is rotated by the rotation of the developing sleeve 214 so that the developing nip (the developing roller 216 and the photoconductor drum 210 face each other). It is transported to the position). While the toner is negatively charged, a development bias is applied to the developing sleeve 214, and the toner is electrostatically adsorbed from the outer peripheral surface of the developing sleeve 214 onto the outer peripheral surface of the photoconductor drum 210.

In the region where the surface charge from the charging device 211 remains on the outer peripheral surface of the photoconductor drum 210, the surface charge and the toner charge have the same polarity, and the outer peripheral surface of the photoconductor drum 210 and the toner Since the electrostatic repulsive force acts between and, the toner does not adhere. That is, in the present embodiment, the reversal development method is adopted, and the toner is adhered to the region of the outer peripheral surface of the photoconductor drum 210 whose surface charge has disappeared due to exposure.

In this way, the electrostatic latent image is developed and a toner image is formed. The axial length of the maglor 215 is shorter than the axial length of the developing sleeve 214, and the maglor 215 does not exist inside both ends of the developing sleeve 214 in the axial direction. The range in which the maglor 215 exists when viewed from the direction orthogonal to the rotation axis of the developing roller 216 is called the developing magnetizing width (image area).

The primary transfer roller 217 is pressure-welded to the photoconductor drum 210 with the intermediate transfer belt 131 interposed therebetween. The intermediate transfer belt 131 orbits in the direction of arrow A by the drive roller 132. The primary transfer roller 217 is driven by the intermediate transfer belt 131 and rotates in the direction of arrow C. A primary transfer bias is applied to the primary transfer roller 217, and a toner image is electrostatically transferred from the outer peripheral surface of the photoconductor drum 210 onto the intermediate transfer belt 131 (primary transfer).

The cleaning device 200 includes a static elimination lamp (eraser) 202 and a cleaning blade 201. The static elimination lamp 202 illuminates the outer peripheral surface of the photoconductor drum 210 to eliminate the residual charge on the outer peripheral surface of the photoconductor drum 210. The range illuminated by the static elimination lamp 202 on the outer peripheral surface of the photoconductor drum 210 is changed according to the conditions described later. The cleaning blade 201 scrapes residual toner from the outer peripheral surface of the photoconductor drum 210. The scraped residual toner is transported to the residual toner box by a transport screw (not shown).

As shown in FIG. 6, the size of the photoconductor drum 210 in the axial direction has the smallest development magnetizing width, followed by the charging width by the charging device 211 and the cleaning width (contact width) by the cleaning blade 201. growing. Further, the size of the photoconductor drum 210 in the axial direction is larger than these. Further, the static elimination lamp 202 can irradiate the static elimination light over the entire width in the axial direction of the photoconductor drum 210.

As described above, when the toner images of each color of YMCK formed by the image forming portions 100Y, 100M, 100C and 100K are primarily transferred onto the outer peripheral surface of the intermediate transfer belt 131 so as to overlap each other, a color toner image is formed. Will be done. In the case of a monochrome toner image, only the toner image of the color is primarily transferred onto the outer peripheral surface of the intermediate transfer belt 131. After that, the toner image is conveyed to the secondary transfer position by orbiting the intermediate transfer belt 131.

The drive roller 132 that rotationally drives the intermediate transfer belt 131 is pressed against the secondary transfer roller 133 with the intermediate transfer belt 131 interposed therebetween. The secondary transfer nip formed by this pressure welding is at the secondary transfer position where the toner is electrostatically transferred to the recording sheet S.

The paper feed unit 140 includes a paper feed cassette 141 that accommodates a bundle of recording sheets, a paper feed roller 142 that feeds the highest-level recording sheet S one by one from the bundle of recording sheets contained in the paper feed cassette 141, and the like. There is. The paper feeding unit 140 feeds the recording sheet S of the paper type specified in the image forming job to the image forming unit 130 in parallel with the image forming unit 130 forming the toner image.

The recording sheet S fed from the paper feed unit 140 is skew-corrected by abutting the tip against the resist roller 134 that has stopped rotating to form a loop, and then resists at the timing of the secondary transfer. By starting the rotation of the roller 134, the toner image is conveyed toward the secondary transfer position at the timing when the toner image is transferred to an appropriate position on the paper surface.

A secondary transfer bias is applied to the secondary transfer roller 133, and at the secondary transfer position, the toner image supported on the outer peripheral surface of the intermediate transfer belt 131 is electrostatically transferred to the recording sheet S. (Secondary transcription).

The fixing device 136 is a toner supported on the recording sheet S by passing the recording sheet S through a fixing nip formed by pressure-contacting the pressure roller 138 to the fixing roller 137 whose temperature has been raised by using a heater. The image is heat-fixed to the recording sheet S. The recording sheet S on which the toner image is heat-fixed is discharged onto the paper ejection tray 139.

The operation panel 150 is provided with a touch panel, hard keys, a speaker, etc., which are a combination of a touch pad and a liquid crystal display (LCD), and presents information to the user of the image forming apparatus 1 and performs input operations. Or accept.

When the control unit 110 accepts a job according to a user instruction using the operation panel 150 or receives a job from another device via a communication network such as a LAN (Local Area Network) or the Internet, each unit of the image forming apparatus 1 Control the operation of and execute the job.
[2] Configuration of Cleaning Device 200 Next, the configuration of the cleaning device 200 will be described.

As shown in FIG. 3, the cleaning device 200 has a long shape in the axial direction of the photoconductor drum 210, and the cleaning blade 201 and the static elimination lamp 202 are housed in the housing 302. Further, the static elimination lamp 202 has LEDs (Light Emitting Diodes) 301 arranged in a row along the axial direction (Z direction in FIG. 3) of the photoconductor drum 210, and all the LEDs 301 are the photoconductor drum 210. The static elimination light is emitted in the direction of arrow E toward the outer peripheral surface of the.

On the outer peripheral surface of the photoconductor drum 210, the area where each LED 301 can irradiate the static elimination light (the range where one LED 301 can eliminate static electricity) is narrow, so that the entire charging width by the charging device 211 is covered. A plurality of LEDs 301 are provided in order to eliminate the surface charge of the photoconductor drum 210. Further, the LEDs 301 adjacent to each other in the axial direction partially overlap the irradiation range of the static elimination light on the outer peripheral surface of the photoconductor drum 210.

This is because if the irradiation ranges of the static elimination light do not overlap between the adjacent LEDs 301, the surface charge on the outer peripheral surface of the photoconductor drum 210 may not be sufficiently statically eliminated at the boundary portion of the irradiation range. , The photoconductor layer may deteriorate in the part where the charge is not removed. On the other hand, if the irradiation ranges of the static elimination light are partially overlapped between the adjacent LEDs 301, the outer peripheral surface of the photoconductor drum 210 can be sufficiently statically eliminated over the entire width in the axial direction.

Of the LEDs 301, as shown in FIG. 6, an LED that irradiates both ends of the photoconductor drum 210 with static elimination light from the development magnetizing width in the axial direction of the photoconductor drum 210 (hereinafter, referred to as “both ends LEDs”). The 301e can be turned on and off by the control unit 110 regardless of the on / off state of the other LED (hereinafter, referred to as “central LED”) 301c. Since an electrostatic latent image is not formed by the exposure device 212 on the regions on both ends of the outer peripheral surface of the photoconductor drum 210 in the axial direction with respect to the developing magnetizing width, the charging device 211 is turned off when both ends LEDs 301e are turned off. Maintains the surface charge when uniformly charged.
[3] Configuration of Control Unit 110 Next, the configuration of the control unit 110 will be described.

As shown in FIG. 4, the control unit 110 includes a CPU (Central Processing Unit) 401, a ROM (Read Only Memory) 402, a RAM (Random Access Memory) 403, and the like, and the power is turned on to the image forming apparatus 1. When the CPU 401 is reset, the CPU 401 reads the boot program from the ROM 402 and starts it, and uses the RAM 403 as a working storage area to read the OS (Operating System), control program, etc. from the HDD (Hard Disk Drive) 404. To execute.

Thereby, the operations of the image reading unit 120, the image forming unit 130, the paper feeding unit 140, and the operation panel 150 can be controlled. In particular, the control unit 110 turns on and off the static elimination lamps 202Y, 202M, 202C and 202K LEDs 301Y, 301M, 301C and 301K of the image forming units 100Y, 100M, 100C and 100K of the image forming unit 130, respectively. The LEDs 301cY, 301cM, 301cC and 301cK and the two-end LEDs 301eY, 301eM, 301eC and 301eK can be controlled separately.

The NIC (Network Interface Card) 405 executes a process for the image forming apparatus 1 to communicate with another apparatus via a communication network such as a LAN or the Internet. The environment sensor 406 detects the temperature and humidity inside the image forming apparatus 1 as the ambient temperature and humidity of the residual toner on the outer peripheral surface of the photoconductor drum 210. If the index value is an index value of the environmental temperature and the environmental humidity of the residual toner on the outer peripheral surface of the photoconductor drum 210, an index value other than the temperature and humidity in the image forming apparatus 1 may be detected. For example, since the temperature and humidity outside the image forming apparatus 1 have a certain correlation with the environmental temperature and the environmental humidity of the residual toner on the outer peripheral surface of the photoconductor drum 210, the image forming apparatus 1 is used as an index value. The temperature and humidity outside the device may be detected.
[4] Control operation for preventing end toner leakage Next, a control operation for preventing end toner leakage will be described.

As shown in FIG. 5, when the control unit 110 receives the image forming job (S501: YES), the control unit 110 determines the system speed with reference to the paper type of the recording sheet S designated in the image forming job (S502). .. The system speed of the image forming apparatus 1 is two types, full speed and half speed. When the paper type of the recording sheet S is plain paper or thin paper, the system speed is set to full speed, and the paper type of the recording sheet S is thick paper. In some cases, the amount of heat required to fix the toner image is larger than in the case of plain paper or thin paper, so the speed is reduced to half speed.

It was determined that the faster the rotation speed (system speed) of the photoconductor drum 210, the faster the moving speed of the residual toner on the outer peripheral surface of the photoconductor drum 210, and the more likely the end toner leaks. When the system speed is full speed (S503: YES), only the central LED 301c of the LEDs 301 constituting the static elimination lamp 202 is turned on, and the LED 301e at both ends are turned off (S509).

By doing so, as shown in FIG. 6, the end portion of the outer peripheral surface of the photoconductor drum 210 that is on the end side of the developing magnetizing width 601 and is uniformly charged by the charging roller 211. Since the region (hereinafter, referred to as “non-static electricity elimination region”) 602 is a region in which an electrostatic latent image is not formed, the surface charge is not lost by the exposure of the exposure apparatus 212. Further, when the LEDs 301e at both ends are turned off, the static elimination light is not irradiated, so that the surface charge is not lost due to the static elimination.

The surface charge applied to the outer peripheral surface of the photoconductor drum 210 by the charging roller 211 and the charging voltage of the residual toner are both negative polarities and have the same polarity. Therefore, the electrostatic repulsive force acts on the residual toner, and the residual toner cannot enter the non-static elimination region 602, and at least the moving speed of the residual toner is reduced, so that the end toner leakage occurs. Be prevented.

When the system speed is half speed (S503: NO), RIP data is generated from the image data specified in the image formation job (S504). In the RIP data, the ratio (coverage) of the number of pixels to which toner is attached to the total number of pixels is calculated, and when the coverage is equal to or more than a predetermined threshold value (for example, 80%), the image is a high coverage image. Is determined.

Further, from the designation in the image forming job, it is confirmed whether or not the high coverage image is continuously printed in a predetermined number (for example, 100) or more. When it is determined that the high coverage image is continuously printed (S505: YES), when the high coverage image is formed, a large amount of residual toner is supplied to the cleaning blade 201, so that end toner leakage is likely to occur. Since it is determined, only the central LED 301 of the LEDs 301 constituting the static elimination lamp 202 is turned on, and the LED 301s at both ends are turned off (S509).

When it is determined that the image is not a high coverage image (S505: NO), the environmental temperature and the environmental humidity are acquired by referring to the detected value of the environmental sensor 406 (S506). When the environmental temperature is 23 degrees Celsius or less, it is called low temperature, and when the environmental humidity is 60% or less, it is called low humidity. In the case of low temperature and low humidity (LL), it is judged that the moving speed of the residual toner on the outer peripheral surface of the photoconductor drum 210 becomes high, and the end toner leakage is likely to occur.

Therefore, in a low-temperature and low-humidity environment (S507: YES), only the central LED301 of the LED301s constituting the static elimination lamp 202 is turned on, and the LED301s at both ends are turned off (S509).

If the environment is not low temperature and low humidity (S507: NO), it is considered unlikely that toner leakage at the end will occur, so all the LEDs 301 constituting the static elimination lamp 202 are turned on (S508). In this case, since the image is not formed as a high coverage image, the amount of residual toner on the outer peripheral surface of the photoconductor drum 210 is small. Further, since the system speed is half speed and the environment is not low temperature and low humidity, the speed of moving on the outer peripheral surface of the photoconductor drum 210 does not increase.

However, even if the moving speed of the residual toner is slow, as shown in FIG. 6, since the surface charge is removed from the non-static elimination region 602 by static electricity removal, the electrostatic repulsive force with the surface charge hinders the entry of the residual toner. It will never be done. Therefore, a certain amount of residual toner enters the non-static elimination region 602.

Since this residual toner acts as a lubricant between the cleaning blade 201 and the outer peripheral surface of the photoconductor drum 210 with respect to the portion of the cleaning blade 201 that comes into contact with the non-static elimination region 602, the cleaning blade 201 in the non-static elimination region 602 It can prevent curling and damage.

Further, if the outer peripheral surface of the photoconductor drum 210 is further charged by the charging device 211 without removing static electricity, the absolute value of the surface potential of the outer peripheral surface of the photoconductor drum 210 becomes too large, and the carrier contained in the developer is contained. Is more likely to adhere to the outer peripheral surface of the photoconductor drum 210. If the carrier adheres to the outer peripheral surface of the photoconductor drum 210, the toner image may be disturbed and the image quality may be deteriorated, or the photoconductor layer and the outer peripheral surface of the intermediate transfer belt 131 may be damaged.

For such a problem, as described above, if the non-static elimination region 602 is statically eliminated when end toner leakage is unlikely to occur, it is possible to prevent the absolute value of the surface potential of the non-static elimination region 602 from becoming too large. Therefore, it is possible to prevent problems such as deterioration of image quality and damage to the photoconductor layer and the intermediate transfer belt 131 as described above without causing edge toner leakage.

After the processing of steps S508 and S509, the execution of the image forming job is started (S510), and when the execution of the image forming job is completed (S511: YES), all the static elimination lamps 202 are turned off (S512). After that, the process proceeds to step S501, and the above process is repeated.

In this way, the speed at which the residual toner travels along the cleaning blade 201 toward the end in the axial direction on the outer peripheral surface of the photoconductor drum 210 can be suppressed, particularly at the end of the cleaning blade 201. Therefore, it is possible to prevent the end toner from leaking.
[5] Modified Examples Although the present disclosure has been described above based on the embodiments, it goes without saying that the present disclosure is not limited to the above-described embodiments, and the following modified examples can be implemented. ..
(5-1) In the above embodiment, a case where the presence / absence of static elimination in the non-static elimination region 602 is switched according to the coverage of RIP data, the system speed, the environmental temperature and the environmental humidity has been described as an example. Of these three conditions, in the case of forming a high coverage image, the amount of residual toner that rushes into the cleaning blade 201 is large. Therefore, as compared with the case of forming an image of normal coverage, the resistance when the cleaning blade 201 scrapes off the residual toner is increased, so that the torque of the cleaning blade 201 is increased.

Explaining with reference to FIG. 2, when the photoconductor drum 210 is rotationally driven in the direction of arrow B, a torque for rotating the photoconductor drum 210 in the direction of arrow D with the fixed position 220 as a center acts on the cleaning blade 201. The greater the amount of residual toner on the outer peripheral surface of the photoconductor drum 210, the greater the torque acting on the cleaning blade 201.

Further, when the system speed is full speed, the rotation speed of the photoconductor drum 210 is higher than that in the case of half speed, so that it is assumed that the torque applied to the cleaning blade 201 is large. In a low temperature and low humidity environment, the hardness of the cleaning blade 201 is higher than that in a normal temperature and humidity environment, so that the torque applied to the cleaning blade 201 is also large.

Therefore, when the torque of the cleaning blade 201 is large, if the static elimination in the static elimination region 602 is stopped, the end toner leakage can be prevented as described above.

Further, the same effect can be obtained by measuring the torque acting on the cleaning blade 201 and turning off the LEDs 301e at both ends when the torque exceeds a predetermined value. When torque acts on the cleaning blade 201, the amount of bending of the cleaning blade 201 increases. Therefore, if the strain gauge is attached to the cleaning blade 201 and the amount of deflection is measured, the torque acting on the cleaning blade 201 can be measured to control the turning on and off of the LEDs 301e at both ends.
(5-2) In the above embodiment, the case where the static elimination lamp 202 is composed of a plurality of LEDs 301 and the end LED 301e is turned on and off depending on whether or not end toner leakage is likely to occur has been described as an example. Needless to say, the present disclosure is not limited to this, and the following may be used instead.

For example, when it is determined that toner leakage at the end is likely to occur, instead of turning off the static elimination lamp 202, a shutter or the like is used to block both ends of the static elimination lamp 202 in the axial direction of the photoconductor drum 210. , The static elimination of the non-static elimination region 602 may be stopped. As the shutter, for example, if a shutter that can block light without mechanical operation such as a liquid crystal shutter is used, the space for installing the shutter can be saved.
(5-3) In the above embodiment, a case where the LED 301e at both ends is turned off when it is determined that toner leakage at the end is likely to occur has been described as an example, but it goes without saying that the present disclosure is not deducted from this. Instead, both ends of the outer peripheral surface of the photoconductor drum 210 are statically eliminated so that the surface potential in the non-static elimination region 602 can suppress the movement of the residual toner. The amount of light of the LED 301e may be reduced. In this way, even when the LEDs 301e at both ends are not turned off, the effect of suppressing toner leakage at the ends can be obtained.
(5-4) In the above embodiment, it is determined whether or not the image is a high coverage image by referring to the RIP data of the color for each image forming unit 100 of each YMCK color, and both ends are determined according to the determination result. Although the case where the LED 301e is determined to be turned on and off has been described as an example, it goes without saying that the present disclosure is not limited to this, and instead of this, the following may be used.

The toner adhering to the outer peripheral surface of the photoconductor drum 210 is not only the toner remaining after the primary transfer, but also the toner image already supported on the outer peripheral surface of the intermediate transfer belt 131 is photosensitive when forming a color toner image. It may be reverse-transferred to the outer peripheral surface of the body drum 210. Further, the amount of toner that is reverse-transferred to the photoconductor drum 210 is RIP data (hereinafter, RIP data) corresponding to the toner image that is primarily transferred onto the outer peripheral surface of the intermediate transfer belt 131 on the upstream side in the circumferential traveling direction of the intermediate transfer belt 131. , "Upstream RIP data") depends on whether or not it is a high coverage image.

Therefore, the on / off of the LEDs 301e at both ends may be controlled in consideration of whether or not the upstream RIP data is a high coverage image. For example, when the image forming unit 100 is arranged in the order of YMCK from the upstream side in the orbiting traveling direction of the intermediate transfer belt 131, the image forming unit 100Y arranged in the uppermost stream has another toner color. It is not necessary to consider whether or not the RIP data is a high-coverage image, and it is sufficient to control the turning on and off of the LEDs 301e at both ends by considering only whether or not the Y-color RIP data is a high-coverage image.

Regarding the second image-creating unit 100M, if the on-off of the LEDs 301e at both ends is controlled in consideration of whether or not the RIP data of the Y color is a high coverage image in addition to the M color, it is intermediate. Even when the amount of Y-color toner that is reverse-transferred from the outer peripheral surface of the transfer belt 131 is large, it is possible to suppress end toner leakage due to the reverse transfer toner.

For the image forming unit 100C arranged third, the RIP data of Y color and the RIP data of M color may be considered, and for the image forming unit 100K arranged fourth, each color of YMC may be considered. It may be considered with the RIP data of.

In particular, with respect to the image forming portion 100 arranged on the most downstream side in the circumferential traveling direction of the intermediate transfer belt 131, the amount of toner transferred on the outer peripheral surface of the intermediate transfer belt 131 on the upstream side is the other image forming portion. Compared to 100, it is the largest. For this reason, as compared with other image forming portions 100, edge toner leakage is more likely to occur due to the reverse transfer toner. Therefore, only the most downstream image forming portion 100 has high coverage image of the toner color RIP data on the upstream side. The on / off of the LED 301e at both ends may be controlled depending on whether or not the above.

For example, even if the K color RIP data is not a high coverage image, if all the upstream YMC color RIP data are high coverage images, the LEDs 301e at both ends may be turned off. By doing so, it is possible to more reliably suppress the toner leakage at the end.
(5-5) In the above embodiment, the case where the image forming apparatus 1 is a multifunction device has been described as an example, but it goes without saying that the present disclosure is not limited to this, such as a printer apparatus, a copying apparatus, and a facsimile apparatus. The same effect can be obtained by applying it to a single-function device.

The image forming apparatus according to the present disclosure is useful as an apparatus capable of preventing end toner leakage when cleaning the outer peripheral surface of the photoconductor drum using a cleaning blade.

1 ………… Image forming device 100 …… Image forming unit 110 …… Control unit 200 …… Cleaning device 201 …… Cleaning blade 202 …… Static elimination lamp 210 …… Photoreceptor drum 211 …… Charging device 212 …… Exposure device 213 ... Developing device 214 ... Magroll 215 ... Developing sleeve 216 ... Developing roller 215 ... Primary transfer roller 301c ... Central LED
301e ... End LED
406 …… Environmental sensor

Claims (9)

An image forming apparatus that transfers a toner image formed on the outer peripheral surface of a photoconductor drum to a transfer target.
A static elimination means for removing static electricity from the outer peripheral surface of the photoconductor drum after image transfer,
A cleaning blade that scrapes residual toner from the outer peripheral surface after static elimination,
A determination means for determining whether or not toner leakage from the blade end is likely to occur during scraping, and
If the determination result is affirmative, static elimination is performed only in the central portion excluding the end region in the axial direction of the photoconductor drum.
When the determination result is negative, the image forming apparatus includes a control means for controlling the static elimination means so as to eliminate the entire static elimination range in the axial direction of the photoconductor drum. .. The static elimination means is a light emitting element array in which a plurality of light emitting elements are arranged in a row along the axial direction.
When the determination result is positive, the control means turns off the light emitting element that eliminates static electricity in the end region in the axial direction, and turns on only the light emitting element that eliminates static electricity in the central portion.
The image forming apparatus according to claim 1, wherein when the determination result is negative, the static elimination means is controlled so as to light all the light emitting elements. The range of the end region in the axial direction of the photoconductor drum is the maximum width in which the electrostatic latent image formed on the outer peripheral surface of the photoconductor drum can be developed in the axial direction of the photoconductor drum. The image forming apparatus according to claim 1 or 2, wherein the image forming apparatus is outside the end of the maximum development width. A developing device for developing an electrostatic latent image formed on the outer peripheral surface of the photoconductor drum using a developing roller that magnetically attracts a two-component developer is provided.
The image forming apparatus according to claim 3, wherein the maximum developing width is a developing magnetizing width within a range in which the developing agent can be magnetically attracted in the axial direction of the developing roller. The image forming apparatus according to claim 3 or 4, wherein the end region of the photoconductor drum in the axial direction is located closer to the center than the blade end. When the residual toner is scraped off by the edge portion of the cleaning blade, the determination means tends to cause end toner leakage when the torque acting on the cleaning blade is large around the fixed position of the cleaning blade. The image forming apparatus according to any one of claims 1 to 5, wherein the image forming apparatus is determined to be. A coverage acquisition means for acquiring coverage of a printed image in a transferred body is provided.
The image forming apparatus according to any one of claims 1 to 6, wherein the determination means determines that edge toner leakage is likely to occur when the coverage is larger than a predetermined threshold value. A speed acquisition means for acquiring the rotation speed of the photoconductor drum is provided.
The image forming apparatus according to any one of claims 1 to 7, wherein the determination means determines that end toner leakage is likely to occur when the rotation speed is higher than a predetermined speed. An environmental condition acquisition means for acquiring the environmental temperature and the environmental humidity of the photoconductor drum is provided.
The image forming apparatus according to any one of claims 1 to 8, wherein the determination means determines that edge toner leakage is likely to occur in a low temperature and low humidity environment.

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