JP2006178078A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of high quality image formation by providing a toner recovery device for efficiently discharging toner taken in a rotating brush, and preventing nonuniform charging or nonuniform exposure of an image carrier caused by transfer residual toner. <P>SOLUTION: The toner recovering device 18 comprises the rotary brush 18a and ultrasonic vibration device 18b. A bias potential is applied to the rotary brush 18a from a power source 19. Transfer residual toner, remaining on the surface of the image carrier 11, is taken into the rotary brush 18a during image formation period. During the image non-formation period, the ultrasonic vibration device 18b is turned on and a torsion bias potential is applied to the rotary brush 18a, so that the toner taken in the rotary brush 18a is discharged onto the surface of the image carrier 11. The toner discharged is recovered into a development device and is recycled. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus, and more particularly to a cleanerless image forming apparatus that collects and reuses toner remaining on an image carrier after a toner image is transferred to a recording medium.

  2. Description of the Related Art Conventional image forming apparatuses such as electrophotographic copying machines and printers use a charging device to uniformly charge the surface of an image carrier (for example, a photosensitive drum) and expose an image on the surface to expose an image latent image. Form an image. The formed image latent image is developed with toner to form a toner image, which is transferred to a recording medium, or transferred onto an intermediate transfer member, and further transferred to a recording medium. The transferred toner image Is heated and fixed by a fixing device to form an image.

  In such an image forming apparatus, conventionally, after a toner image formed on an image carrier or an intermediate transfer member (hereinafter referred to as an image carrier) is transferred to a recording medium, the toner remaining on the image carrier is removed. A cleaning device for cleaning is provided.

  Some of these cleaning devices use a cleaning brush made of conductive fibers, and the cleaning brush is in contact with the surface of the image carrier, and the cleaning brush adheres to the surface of the image carrier. An appropriate polarity of static electricity is provided to remove the toner. The cleaning brush is disposed in contact with a toner removing roll that wipes off the toner particles adhering to the bristles.

  By the operation of the cleaning device, the toner adhering to the surface of the image carrier is adsorbed by the cleaning brush, and the image carrier surface is cleaned. The toner particles adsorbed on the cleaning brush are removed by the toner removing roll, but are not completely removed. Therefore, the toner particles that have not been removed are gradually accumulated inside the cleaning brush, and finally the cleaning is poor. It reaches.

In order to cope with this problem, an apparatus in which an ultrasonic vibration device that applies ultrasonic vibration from the back side of the image carrier is arranged at the contact portion between the image carrier and the cleaning brush has been proposed. According to this apparatus, the surface adhesion force between the image carrier and the toner particles is reduced, and toner particles are collected at the tip of the brush bristles of the cleaning brush. It is said that it can be easily removed by this, and poor cleaning can be avoided (see Patent Document 1).
JP-A-8-224502.

  In the cleaning device described above, the toner particles adhering to the cleaning brush are removed by a toner removing roll and stored in a waste toner unit, and the waste toner unit is replaced by a service person during maintenance and inspection.

  On the other hand, in recent image forming apparatuses, there is a growing demand for downsizing, cost reduction, maintenance-free, etc., and the toner remaining on the image carrier without the waste toner unit (hereinafter referred to as transfer residual toner) is used as a developing device. An image forming apparatus equipped with a cleanerless system that collects and reuses toner to reduce the number of toner replenishment and reduce toner consumption has been developed.

  This cleaner-less system is a process for cleaning the transfer residual toner remaining on the image carrier without being transferred at the time of the transfer process in the previous image forming process at the same time as the development process of the latent image formed on the surface of the image carrier. Since the conventional image forming apparatus does not include the cleaning device disposed between the transfer unit and the charging unit, the entire image forming device can be reduced in size.

  However, in the image forming apparatus provided with the cleanerless system described above, if transfer residual toner remains on the surface of the image carrier, charging and exposure processes are executed through the transfer residual toner in the next image forming process. Therefore, inconveniences such as uneven charging and uneven exposure occur.

  Therefore, a member for collecting the transfer residual toner composed of a brush or the like is disposed between the transfer portion and the charging portion, and the transfer residual toner generated during the image forming period is once taken in and accumulated by the brush member. Although it is conceivable that the ink is discharged onto the image carrier outside the image period, the holding ability of the brush member is increased, or a process for forcibly discharging when a certain amount of transfer residual toner is accumulated is provided. This means that the entire device is enlarged, the control becomes complicated, the cost is high, the toner accumulates on the brush member, and the maintainability becomes poor, and the image quality is affected. There was a problem such as giving.

  The present invention solves the above-mentioned disadvantages such as uneven charging and uneven exposure due to transfer residual toner on the surface of the image carrier in the above-described conventional cleanerless system image forming apparatus, and enables high-quality image formation. Another object of the present invention is to provide an image forming apparatus that is small, low-cost, and has good maintainability.

  The present invention solves the above problems, and the invention of claim 1 is directed to an image carrier that rotates in a predetermined direction at a constant speed, a charging device disposed around the image carrier, an exposure device, a developing device, Image forming apparatus including an image forming apparatus including a transfer apparatus and a toner collecting apparatus that temporarily takes in and discharges transfer residual toner remaining on the surface of the image carrier, and a control device that controls the operation of the image forming apparatus. In the apparatus, the toner recovery device includes a toner recovery brush and a vibration device that applies mechanical vibration to the toner recovery brush, and the control device responds to an image forming period and a non-image forming period of the image forming device. An image forming apparatus that controls a vibration device that applies vibration to a toner recovery brush.

  The control device controls the vibration device so as to apply vibration to the toner recovery brush during a non-image formation period of the image forming device.

  In addition, the control device controls the vibration device to apply a low-intensity vibration to the toner collection brush during the image forming period by the image forming device and to apply a strong vibration to the toner collection brush during the non-image formation period. You may do it.

  Further, the toner recovery device further includes a bias power supply for supplying a bias potential to the toner recovery brush, and the control device applies vibration to the toner recovery brush of the toner recovery device during a non-image forming period by the image forming device. In addition, the vibration device and the bias power source may be controlled so as to apply a predetermined return bias potential to the toner recovery brush.

  The toner collecting device further includes a bias power source for supplying a bias potential to the toner collecting brush, and the control device applies a low-intensity vibration to the toner collecting brush during an image forming period of the image forming device. The vibration recovery device and the bias power source may be controlled to apply a strong vibration to the toner recovery brush during the image forming period and to apply a predetermined return bias potential to the toner recovery brush during the non-image generation period. Good.

  An ultrasonic vibration device using a piezoelectric element can be used as the vibration device.

  As described above in detail, according to the present invention, after the toner image formed on the surface of the image carrier during the image forming period is transferred to the recording medium, the transfer residual toner on the surface of the image carrier is removed by the toner recovery device. Is temporarily taken in by the rotating brush of the toner, discharged onto the surface of the image carrier during the non-image forming period, and collected inside the developing device. At this time, it is temporarily taken in by the rotating brush of the toner collecting device. When the ultrasonic vibration is applied to the rotating brush, the toner can be efficiently discharged to the surface of the image carrier in a short time.

  This prevents toner from accumulating on the rotating brush of the toner recovery device even when used for a long period of time, so that defective cleaning does not occur. An image forming apparatus capable of forming an image can be provided.

  In addition, according to the present invention, the toner temporarily taken in by the rotating brush is discharged to the surface of the image carrier during the non-image forming period and collected inside the developing device, so that it is smaller than the conventional toner collecting device. The image forming apparatus can be configured in a small size.

  Further, when the rotary brush is vibrated in the axial direction, the wear of the image carrier by the rotary brush can be made uniform, and the life of the image carrier can be maintained long.

  Embodiments of the present invention will be described below. FIG. 1 is a diagram illustrating an outline of the configuration of an image forming apparatus according to an embodiment of the present invention, FIG. 2 is an enlarged view of a portion of the toner recovery device, and FIG. 3 is another example of the toner recovery device. It is the figure which expanded and showed.

  In FIG. 1, an image forming apparatus 10 includes a charging device 12 that is a charging device, an exposure device 13, and a developing device around a photoconductor 11 that is an image carrier that is rotated at a constant speed in the direction of arrow a by a driving device (not shown). 14, a transfer device 15 and a toner recovery device 18 are disposed. A fixing device 17 is disposed on the downstream side in the transport direction of the recording medium P after passing through the transfer device 15. The toner recovery device 18 is composed of a rotating brush 18a and an ultrasonic vibration device 18b, and a bias potential is applied to the rotating brush 18a from a power source 19, which will be described in detail later.

  An image forming operation by the image forming apparatus 10 will be briefly described. First, it is assumed that the photoconductor 11 rotates at a constant speed in the direction of arrow a by turning on the power. The surface of the photoconductor 11 is uniformly charged by the charging device 12. Laser light emitted from the laser device of the exposure device 13 is modulated by an image signal output by reading an original image on a document table (not shown) by a scanning optical system, or an image signal output from a personal computer (not shown). The modulated laser light is projected onto the surface of the photoconductor 11 to form an image latent image.

  The latent image formed on the surface of the photoconductor 11 is developed with the developer of the developing device 14 to form a toner image. The toner image is transferred by the action of the transfer device 15 onto the recording medium P conveyed to the transfer position from a paper supply device (not shown) in accordance with the timing at which the toner image reaches the transfer position. The recording medium P onto which the toner image has been transferred is further fixed by the fixing device 17 and the image forming process is completed.

  The transfer residual toner remaining on the surface of the photoconductor 11 is taken into the rotating brush 18a of the toner collecting device 18 during the image forming period, and then discharged onto the surface of the photoconductor 11 during the non-image forming period. After passing below, it is collected inside the developing device 14.

  Next, the configuration and operation of the toner recovery device 18 will be described with reference to FIG.

  The toner recovery device 18 is in contact with the surface of the photoconductor 11, and applies vibration to the rotary brush 18a that rotates in a direction (arrow b direction) opposite to the rotation direction of the photoconductor (arrow a direction). The ultrasonic vibration device 18b is configured, and a return bias potential is applied to the rotating brush 18a from the power source 19. Note that the return bias potential is a potential in a direction in which the toner attached to the rotating brush 18 a is caused to fly toward the surface of the photoreceptor 11.

  The rotating brush 18a is a brush material in which a bristle of conductive fibers formed by mixing a conductive material with a synthetic resin material on a core metal made of a metal such as stainless steel or aluminum or a conductive material is planted on a base fabric. Is formed into a roller shape.

  As the synthetic resin material, polyamide, polyethylene terephthalate, polyolefin, polycarbonate, polyurethane, acrylic, and the like can be used. As the conductive material, conductive carbon, metal powder, zinc oxide, titanium oxide, tin oxide, or the like can be used, and the conductive material is not limited to these as long as the material can be uniformly mixed with the synthetic resin material.

  Since it is required to wind the brush material on the metal core without any gaps, a method of winding the brush material cut into a strip shape in a spiral shape on the metal core is easy. However, the method is not limited to this method as long as the brush material can be wound without a gap.

  As the ultrasonic vibration device 18b, a known device including an ultrasonic vibrator using a piezoelectric element is used. However, the ultrasonic vibration device 18b is not limited to this as long as it can apply mechanical vibration to the rotating brush 18a. By utilizing ultrasonic vibration, even if vibration is applied to the rotating brush 18a, unpleasant sound is not generated from the image forming apparatus.

  The ultrasonic vibration device 18b is configured such that the tip of the vibration portion of the ultrasonic vibrator is in contact with the cored bar 18c of the rotating brush 18a, and the rotating brush 18a reciprocates in the direction toward the photoconductor 11 and in the opposite direction. Is done. In FIG. 2, the ultrasonic vibration device 18 b is disposed on the side opposite to the photoconductor 11 as viewed from the core metal 18 c, but the ultrasonic vibration device 18 b may be disposed between the core metal 18 c and the photoconductor 11. In any arrangement, ultrasonic vibration can be applied to the rotating brush 18a.

  FIG. 3 is an enlarged view showing another embodiment of the toner recovery device. The same members as those in the toner recovery apparatus shown in FIG. 2 are denoted by the same reference numerals, detailed description thereof will be omitted, and differences will be described.

  The toner collection device shown in FIG. 3 differs from that shown in FIG. 2 in the direction in which ultrasonic vibration is applied to the rotating brush 18a. That is, the toner recovery device shown in FIG. 2 reciprocally vibrates in the direction toward the photoreceptor 11 and in the opposite direction, but the toner recovery device shown in FIG. A sonic vibration device 18b is arranged to reciprocate the rotating brush 18a in the axial direction. In both cases, ultrasonic vibration is applied to the rotary brush 18a. However, in the configuration shown in FIG. 3, the influence of wear on the surface of the photoconductor due to the vibration of the rotary brush becomes substantially uniform, thereby extending the life of the photoconductor. Can do.

  Next, the operation of the toner recovery device will be described. The operation of the toner recovery apparatus is shown in the first and second embodiments.

  FIG. 4 is a timing chart for explaining the operation of the first embodiment, and shows the operation timing when three images are formed.

  When the image forming cycle is started, first, a non-image forming period (period a) is entered. Under the control of the control device, the ultrasonic vibration device 18b is turned ON, the application of the return bias potential to the rotating brush 18a is turned ON, the rotating brush 18a starts to vibrate by ultrasonic vibration, and the return bias potential is applied to the rotating brush 18a. The adhered toner is ejected to the surface of the photoconductor 11 by vibration and bias potential and collected by the developing device.

  When the non-imaging period (period a) elapses, the first imaging period (period b1) starts. The ultrasonic vibration device 18b is turned OFF and the return bias potential is turned OFF, and the image forming operation of the first image by the image forming device is started. The toner image formed on the surface of the photoconductor 11 is transferred to the recording medium P, the transfer residual toner on the surface of the photoconductor 11 is adsorbed by the rotating brush 18a, and the transfer residual toner is cleaned.

  When the first image forming period (period b1) elapses, the image forming operation of the first image is finished, and the non-image forming period (period c1) is entered. The ultrasonic vibration device 18b is turned ON, the return bias potential is turned ON, the rotary brush 18a starts to vibrate, the return bias potential is applied to the rotary brush 18a, and the transfer residual toner adsorbed on the rotary brush 18a is the photoreceptor 11. Is discharged onto the surface of the ink and collected by the developing device.

  When the non-imaging period (period c1) elapses, the second imaging period (period b2) starts. The ultrasonic vibration device 18b is turned OFF and the return bias potential is turned OFF, and the image forming operation of the second image by the image forming device is started. As in the previous image formation, the toner image formed on the surface of the photoconductor 11 is transferred to a recording medium, and the transfer residual toner on the surface of the photoconductor 11 is adsorbed by the rotating brush 18a to clean the transfer residual toner. Is called.

  When the second image forming period (period b2) elapses, the image forming operation of the second image is finished, and the non-image forming period (period c2) is entered. The ultrasonic vibration device 18b is turned ON, the return bias potential is turned ON, the rotary brush 18a starts to vibrate, the return bias potential is applied to the rotary brush 18a, and the transfer residual toner adsorbed on the rotary brush 18a is the photoreceptor 11. Is discharged onto the surface of the ink and collected by the developing device.

  When the non-imaging period (period c2) elapses, the third imaging period (period b3) starts. The ultrasonic vibration device 18b is turned OFF and the return bias potential is turned OFF, and the image forming operation of the second image by the image forming device is started. As in the previous image formation, the toner image formed on the surface of the photoconductor 11 is transferred to a recording medium, and the transfer residual toner on the surface of the photoconductor 11 is adsorbed by the rotating brush 18a to clean the transfer residual toner. Is called.

  When the third image forming period (period b3) elapses, the image forming operation of the third image is finished, and the non-image forming period (period c3) is entered. The ultrasonic vibration device 18b is turned ON, the return bias potential is turned ON, the rotary brush 18a starts to vibrate, the return bias potential is applied to the rotary brush 18a, and the transfer residual toner adsorbed on the rotary brush 18a is the photoreceptor 11. Is discharged onto the surface of the ink and collected by the developing device.

  After the non-image forming period (period c3) has elapsed, the collection of the transfer residual toner is completed, the ultrasonic vibration device 18b is turned off, the return bias potential is also turned off, and the image forming operation is finished.

  FIG. 5 is a timing chart for explaining the operation of the second embodiment, and shows the operation timing when three images are formed.

  When the image forming cycle is started, first, a non-image forming period (period a) is entered. Under the control of the control device, the ultrasonic vibration device 18b is turned on at the first vibration intensity (high intensity), the application of the return bias potential to the rotating brush 18a is turned on, and the rotating brush 18a starts to vibrate at high vibration intensity and rotates. A return bias potential is applied to the brush 18a, and the adhering toner is ejected to the surface of the photoconductor 11 by vibration and bias potential and collected by the developing device.

  When the non-imaging period (period a) elapses, the first imaging period (period b1) starts. The ultrasonic vibration device 18b is kept ON at the second vibration intensity (low strength), the return bias potential is turned OFF, and the image forming operation of the first image by the image forming device is started. The toner image formed on the surface of the photoconductor 11 is transferred to the recording medium P, the transfer residual toner on the surface of the photoconductor 11 is adsorbed by the rotating brush 18a, and the transfer residual toner is cleaned.

  When the first image forming period (period b1) elapses, the image forming operation of the first image is finished, and the non-image forming period (period c1) is entered. The ultrasonic vibration device 18b is kept ON at the first vibration intensity (high intensity), the return bias potential is turned ON, the rotary brush 18a starts to vibrate with high vibration intensity, and the return bias potential is applied to the rotary brush 18a. The untransferred toner adsorbed on the rotating brush 18a is discharged onto the surface of the photoreceptor 11 and collected by the developing device.

  When the non-imaging period (period c1) elapses, the second imaging period (period b2) starts. The ultrasonic vibration device 18b is kept ON at the second vibration intensity (weak intensity), the return bias potential is turned OFF, and the image forming operation of the second image by the image forming device is started. As in the previous image formation, the toner image formed on the surface of the photoconductor 11 is transferred to a recording medium, and the transfer residual toner on the surface of the photoconductor 11 is adsorbed by the rotating brush 18a to clean the transfer residual toner. Is called.

  When the second image forming period (period b2) elapses, the image forming operation of the second image is finished, and the non-image forming period (period c2) is entered. The ultrasonic vibration device 18b is kept ON at the first vibration intensity (high intensity), the return bias potential is turned ON, the rotary brush 18a starts to vibrate with high vibration intensity, and the return bias potential is applied to the rotary brush 18a. The untransferred toner adsorbed on the rotating brush 18a is discharged onto the surface of the photoreceptor 11 and collected by the developing device.

  When the non-imaging period (period c2) elapses, the third imaging period (period b3) starts. The ultrasonic vibration device 18b is kept ON at the second vibration intensity (weak intensity), the return bias potential is turned OFF, and the image forming operation of the third image by the image forming device is started. As in the previous image formation, the toner image formed on the surface of the photoconductor 11 is transferred to a recording medium, and the transfer residual toner on the surface of the photoconductor 11 is adsorbed by the rotating brush 18a to clean the transfer residual toner. Is called.

  When the third image forming period (period b3) elapses, the image forming operation of the third image is finished, and the non-image forming period (period c3) is entered. The ultrasonic vibration device 18b is kept ON at the first vibration intensity (high intensity), the return bias potential is turned ON, the rotary brush 18a starts to vibrate with high vibration intensity, and the return bias potential is applied to the rotary brush 18a. The untransferred toner adsorbed on the rotating brush 18a is discharged onto the surface of the photoreceptor 11 and collected by the developing device.

  After the non-image forming period (period c3) has elapsed, the collection of the transfer residual toner is completed, the ultrasonic vibration device 18b is turned off, the return bias potential is also turned off, and the image forming operation is finished.

  In the first and second embodiments described above, the ultrasonic vibration device 18b is driven for each non-image forming period to apply vibration to the rotating brush. However, the rotating brush is not necessarily applied to each non-image forming period. It is not necessary to give vibration. For example, vibration may be applied to the rotating brush after completion of a plurality of (for example, three) image forming processes, and vibration may be applied to the rotating brush when the last image forming process is completed. . Furthermore, you may make it adjust the time which gives a vibration to a rotating brush according to the processed image size and the number of images.

  FIG. 6 is a diagram illustrating evaluation results of the toner recovery device. As conditions for evaluation, the black / white ratio (B / W ratio) of the original image is 5% and the number of continuous image formation is 10,000. When the operation is performed in the first embodiment of the image forming cycle described above, the second embodiment is performed. The amount of toner accumulated in the rotating brush and the image quality are measured when only the vibration by the ultrasonic vibration device is applied, when the return bias potential is applied, and when only the vibration and the return bias potential are applied. Visual evaluation was made.

  The evaluation results show that the toner accumulation amount is very good with little toner accumulation, ◎, good ones, ◯ when more toner accumulation is recognized than △, toner accumulation is not suitable for practical use. X, especially bad ones are indicated by xx. As for the image quality, the presence or absence of an image portion in which exposure vignetting (non-exposed portion) caused by transfer residual toner occurred during the exposure was evaluated. The evaluation was made visually by dividing into four categories: generation of slight exposure vignetting image and generation of clear exposure vignetting image.

  As is apparent from the evaluation results shown in FIG. 6, when the image forming apparatus is operated at the operation timing of the first embodiment, or when it is operated at the operation timing of the second embodiment, the toner accumulation amount inside the rotary brush The image quality was also good. In particular, when the toner was operated at the operation timing of the second embodiment, the toner accumulation amount inside the rotating brush was small.

  In addition, when only vibration was applied, the amount of accumulated toner was slightly disadvantageous compared to the example, and it was confirmed that slight exposure vignetting images were observed when carefully observed. When a return bias potential was applied, the toner accumulation amount reached a level unsuitable for practical use, and generation of a slight exposure vignetting image was observed. Further, when only the vibration and the return bias potential were applied, the occurrence of a clear exposure vignetting image was observed, and the effect of applying vibration to the rotating brush of the toner recovery device and the effect of applying the return bias potential were confirmed.

  Image formation provided with a toner recovery device having a rotating brush for temporarily taking in and discharging residual toner remaining on the surface of the image carrier after the toner image formed on the surface of the image carrier is transferred to a recording medium Device. By applying ultrasonic vibration to the rotating brush, it is possible to efficiently discharge the toner that has been taken in, prevent the occurrence of uneven charging and exposure unevenness of the image carrier based on the residual toner, and form a high-quality image. An image forming apparatus can be provided.

1 is a diagram illustrating an outline of a configuration of an image forming apparatus according to an embodiment of the invention. FIG. 2 is an enlarged view showing a toner recovery device portion of the image forming apparatus shown in FIG. 1. The figure which expanded and showed the other example of the toner collection | recovery apparatus. 2 is a timing chart for explaining a first embodiment of an image forming cycle. 9 is a timing chart for explaining a second embodiment of the image forming cycle. The figure which shows the evaluation result of a toner collection | recovery apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 11 Photoconductor (Image carrier)
DESCRIPTION OF SYMBOLS 12 Charging device 13 Exposure device 14 Developing device 15 Transfer device 17 Fixing device 18 Toner recovery device 18a Rotating brush 18b Ultrasonic vibration device 18c Core metal 19 Power source

Claims (6)

An image carrier that rotates at a constant speed in a predetermined direction, and a toner recovery device that temporarily takes in and discharges residual toner remaining on the surface of the charging device, exposure device, developing device, transfer device, and image carrier disposed around the image carrier. In an image forming apparatus including an image forming apparatus configured by the apparatus and a control device that controls the operation of the image forming apparatus,
The toner recovery device includes a toner recovery brush and a vibration device that applies mechanical vibration to the toner recovery brush, and the control device is configured to control the toner recovery brush according to an image forming period and a non-image forming period of the image forming device. An image forming apparatus that controls a vibration device that applies vibrations to the image forming apparatus. The image forming apparatus according to claim 1, wherein the control device controls the vibration device so as to apply vibration to the toner collection brush during a non-image formation period of the image forming device. The control device controls the vibration device so as to apply a weak vibration to the toner collecting brush during the image forming period by the image forming device and to apply a strong vibration to the toner collecting brush during the non-image forming period. The image forming apparatus according to claim 1, wherein: The toner collecting device further includes a bias power source that supplies a bias potential to the toner collecting brush, and the control device applies vibration to the toner collecting brush of the toner collecting device during a non-image forming period by the image forming device. 2. The image forming apparatus according to claim 1, wherein the bias power source and the vibration device are controlled so as to apply a predetermined return bias potential to the toner recovery brush. The toner recovery device further includes a bias power source for supplying a bias potential to the toner recovery brush, and the control device applies a low intensity vibration to the toner recovery brush during an image forming period of the image forming device, thereby preventing non-image formation. 2. The bias power supply and the vibration device are controlled so that a strong vibration is applied to the toner recovery brush during the period and a predetermined return bias potential is applied to the toner recovery brush during the non-image forming period. The image forming apparatus described. The image forming apparatus according to claim 1, wherein the vibration device is an ultrasonic vibration device using a piezoelectric element.

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