JP2005300683A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus in which residual toner can efficiently be captured by separately conducting the removal of foreign matter such as paper powder and the capture of residual toner on a photoreceptor, which has not been transferred to recording paper. <P>SOLUTION: An electrifier 15 for electrifying a photoreceptor drum 13 by contacting the drum 13 is disposed. An exposure unit 18 is disposed downstream of the electrifier 15. A developing roller 24 is disposed downstream of the exposure unit 18. A transfer unit 31 for transferring a toner image to recording paper P is disposed downstream of the developing roller 24. A foreign matter removal roller 41 is disposed downstream of the transfer unit 31. A residual toner capturing brush 45 for capturing residual toner on the surface of the photoreceptor drum 13 is disposed downstream of the foreign matter removal roller 41. The foreign matter removal roller 41 removes paper powder on the photoreceptor drum 13, whereas the residual toner capturing brush 45 captures residual toner on the photoreceptor drum 13. During the capturing operation, a potential with the negative polarity which is opposite the polarity of the residual toner electrified to the positive polarity is applied to the residual toner capturing brush 45. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus, and more particularly, a foreign material such as paper dust adhered to the surface of a photosensitive member after a recording material passes between the photosensitive member and a transfer unit and a toner image is transferred to the recording material. The present invention relates to an image forming apparatus in which a step of removing toner and a step of discarding or recycling residual toner remaining on the surface of a photoreceptor without being transferred to a recording material are separately performed.

  In general, in an electrophotographic image forming apparatus employed in a copying machine, a facsimile machine, a printer, or the like, an electrostatic latent image is formed on the surface of a photosensitive drum charged by a charger by an exposure unit. The latent image is developed by a toner type developing device provided with a developing roller. Further, the image forming apparatus transfers the developed toner image from the photosensitive drum onto the recording paper by the transfer device, and fixes the toner image on the recording paper as a permanent image by the fixing device provided on the downstream side of the transfer device. It has become.

  After the above-described transfer process, foreign matter such as paper dust generated from the recording paper adheres to the surface of the photosensitive drum, or toner that has not been transferred to the recording paper remains and becomes residual toner. Foreign matter and untransferred residual toner cause the image quality to deteriorate in the next step of forming a toner image on the surface of the photoreceptor, and therefore it is preferable to remove the toner.

By the way, in the image forming process of the so-called negative charging process in which the photosensitive drum is charged to the negative electrode, the negative potential on the surface of the photosensitive drum and the potential of paper dust (foreign matter) that is normally charged to the negative polarity. Repel each other, and paper dust hardly adheres to the surface of the photosensitive drum. For this reason, it is possible to remove paper dust with a simple removal brush, and both the residual toner and paper dust can be removed by one conductive fiber brush provided on the downstream side of the transfer device. It was supposed to be done. In Patent Document 1, a conductive brush is provided on the downstream side of the transfer unit corresponding to the photosensitive drum. Japanese Patent Application Laid-Open No. H10-228561 provides one cleaning device for collecting residual toner corresponding to the photosensitive drum on the downstream side of the transfer unit. In Patent Document 3, one conductive fiber brush is provided on the downstream side of the transfer unit corresponding to the photosensitive drum.
JP-A-8-114969 JP-A-9-138547 JP 2000-293083 A

  2. Description of the Related Art In recent years, a positive charging type image forming apparatus that charges an OPC photosensitive drum (Organic-Photo-Conductor: organic photoconductor) having a single-layer structure with a pigment on the surface in order to improve the image quality of a recording paper is positively charged. Has been proposed. In the image forming process of this image forming apparatus, since paper dust charged to a negative polarity is usually easily adsorbed on the surface of the photosensitive drum, the influence of the paper dust becomes significant, and a special dust removing paper dust from the photosensitive drum is used. The problem arises that this measure is necessary. However, since all described in Patent Documents 1 to 3 use only one conductive (fiber) brush or a cleaning device, an operation for removing foreign matters such as paper dust on the photosensitive drum, and on the photosensitive drum There is a problem in that it is impossible to appropriately deal with the remaining toner capturing operation.

  By the way, as an image forming apparatus, after the residual toner on the photosensitive drum is captured by the conductive fiber brush, it is discarded without being reused, and the toner captured during the non-paper passing period is returned to the photosensitive drum and developed. There is a cleaner-less process that is collected and reused by a vessel. In the former method, residual toner and foreign matter may be removed by a cleaning member. However, since the remaining toner and foreign matter usually have different charging polarities, it is difficult to efficiently remove them. On the other hand, in the latter cleanerless process, since there is no foreign matter removing means for removing only foreign matter, when the residual toner is collected by the developing device, paper dust is also collected together, and the image quality is deteriorated. is there. Therefore, the problem becomes remarkable in the image forming apparatus of the cleanerless process.

  The present invention solves the above-described problems in the prior art, and can appropriately remove foreign matters such as paper dust and treat residual toner that has not been transferred on the photosensitive member. An object of the present invention is to provide an image forming apparatus capable of efficiently capturing toner remaining on the surface of a photoreceptor by a toner capturing means.

  In order to solve the above problems, the invention described in claim 1 forms an electrostatic latent image on the surface of the photosensitive member charged by the charging means by the exposure means, and the electrostatic latent image is converted into a toner-based image. In the image forming apparatus developed by the developing means and transferring the developed toner image onto the recording material by the transfer means, the foreign matter removing means for removing the foreign matter adhering to the surface of the photoreceptor, and the photosensitive after the transfer A residual toner capturing means for capturing untransferred residual toner remaining on the surface of the body, and a charge polarity of the transfer residual toner with respect to the residual toner capturing means in the step of capturing the residual toner from the surface of the photoreceptor. The gist of the invention is that it includes reverse polarity potential applying means for applying a reverse polarity potential.

  According to a second aspect of the present invention, in the first aspect, the reverse polarity potential applying unit is configured to make the residual toner capturing unit negative when the charging polarity of the residual toner on the photosensitive member is positive. The gist is that it is configured.

The gist of a third aspect of the present invention is that, in the first aspect, the foreign matter removing means is provided on the upstream side of the remaining toner capturing means in the rotation direction of the photosensitive member.
According to a fourth aspect of the present invention, in any one of the first to third aspects, the residual toner capturing means is a conductive fiber brush, and the foreign matter removing means is a foreign matter removing roller. .

  According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the reverse polarity potential applying means returns the residual toner capturing means to return the toner captured by the residual toner capturing means to the surface of the photoreceptor. The gist of the present invention is to include polarity switching means for switching the polarity.

  According to the present invention, the foreign matter adhering to the surface of the photoconductor can be removed by the foreign matter removing unit, and the untransferred residual toner remaining on the surface of the photoconductor after the transfer can be captured by the residual toner capturing unit. it can. In this way, the foreign matter removing means that exclusively removes foreign matter and the residual toner supplementary means that exclusively catches residual toner are configured as separate functional parts. Can be performed properly. In particular, according to the present invention, in the step of capturing the transfer residual toner from the surface of the photoconductor, a potential having a polarity opposite to the charged polarity of the remaining toner is applied to the remaining toner capturing unit by the reverse polarity potential applying unit. Therefore, the remaining toner can be captured efficiently.

Hereinafter, an embodiment in which the present invention is embodied in an electrophotographic image forming apparatus employed in a copying machine, a facsimile machine, a printer, or the like will be described with reference to the drawings.
As shown in FIG. 1, a photosensitive drum 13 as a photosensitive member is rotatably supported on a main body frame 12 of the image forming apparatus 11, and a photoconductive film 14 is formed on the outer peripheral surface thereof. The photosensitive drum 13 is at a ground potential (for example, 0 V). A charger 15 serving as a charging means comprising a brush roller in which a conductive brush body is implanted is rotatably supported on the main body frame 12 so as to come into contact with the photosensitive drum 13. A superposed voltage of alternating current and direct current is applied to the charger 15 from an alternating current power source 16 and a direct current power source 17 to uniformly positively charge the photoconductive film 14 of the photosensitive drum 13 to a predetermined potential (for example, +900 V). An exposure unit 18 as an exposure unit is attached to the main body frame 12 so as to be positioned at a predetermined position directly above the photosensitive drum 13, and from a light-emitting diode (LED) array 19 provided on the lower surface thereof. Light is applied to the photoconductive film 14 of the photosensitive drum 13 to form an electrostatic latent image based on image data read by a document reading device (not shown).

  The main body frame 12 is replaceably mounted with a unitized developing device 21 as developing means. The developing device 21 is disposed in a toner case 22, a lower portion of the toner case 22, a supply roller 23 to which a predetermined voltage is supplied by a power source (not shown), and between the supply roller 23 and the photosensitive drum 13. And a developing roller 24 disposed in the lower end opening of the toner case 22. The developing roller 24 is in contact with the supply roller 23 and the photosensitive drum 13. The toner is frictionally charged at the contact portion between the developing roller 24 and the supply roller 23, and the toner carried on the charged developing roller 24 is developed. At the contact portion between the roller 24 and the photosensitive drum 13, the transfer is made to the photosensitive drum 13. A stirring body 25 is rotatably supported in the toner case 22. By the rotation of the stirring member 25, the toner in the toner case 22 is constantly stirred, and the toner is kept at a uniform density.

  A predetermined voltage (for example, −300 V or +400 V) is supplied to the developing roller 24 from a DC power supply 27. The toner conveyed from the toner case 22 by the supply roller 23 and applied with a predetermined potential by the developing roller 24 has the applied potential (for example, 400 V) and the electrostatic latent image formed on the photosensitive drum 13. Is selectively attached to the electrostatic latent image by the potential difference from the potential (for example, 100 V). A toner image is formed on the photosensitive drum 13 by the toner adhering to the electrostatic latent image.

  A transfer unit 31 serving as a transfer unit is rotatably disposed in the main body frame 12 so as to be in contact with the photosensitive drum 13 so as to be positioned immediately below the photosensitive drum 13. .7 kV or +900 V). Based on the potential difference between the potential of the transfer device 31 and the potential of the toner image, the toner image on the photosensitive drum 13 is transferred to a recording paper P as a recording material supplied from a recording paper supply device (not shown).

  The main body frame 12 is provided with a heat fixing unit 35 constituted by a heat roller 33 and a pressure roller 34 so as to be positioned on the recording paper feed side of the photosensitive drum 13. Accordingly, when the recording paper P is fed between the heating roller 33 and the pressure roller 34, the toner image is heated and fixed on the recording paper P.

  In the main body frame 12, a foreign matter removing roller 41, for example, a metal cylindrical body as a foreign matter removing means for removing foreign matters such as paper dust attached to the surface of the photosensitive drum 13 is transferred to the surface of the photosensitive drum 13. It is mounted so that it can be moved. The foreign matter removing roller 41 is connected to a DC positive power source 42 that applies a positive potential to the roller. The foreign matter removing roller 41 is provided with a scraper 43 for removing the paper dust that comes in contact with the surface thereof, and a case 44 for collecting the removed paper dust.

  The main body frame 12 is provided with a residual toner capturing brush 45 as a residual toner capturing means made of a conductive fiber brush. A DC positive power source 46 that applies a positive potential to the brush and a DC negative power source 47 that applies a negative potential are connected in parallel to the remaining toner capturing brush 45. The DC positive power source 46 and the DC negative power source 47 are switched by polarity switching means 48 as reverse polarity potential applying means. The residual toner capturing brush 45 temporarily captures residual toner remaining on the photosensitive drum 13 after transfer, and diffuses the captured toner back to the surface of the photosensitive drum 13.

Examples of the conductive fiber brush used for the residual toner capturing brush 45 include metal fibers, synthetic fibers such as carbon-dispersed polycarbonate, nylon, and polypropylene, or carbon fibers. Further, a brush length of 1 to ¹² mm, a brush density of 1 to 500,000 / inch ² , a brush diameter of 2.2 to 15.5 dtex, and a brush resistance of 10 ⁻² to 10 ¹² Ωcm are desirable. The one with a thickness of 5 mm was used.

  In the present embodiment, a series of processes such as charging to the photosensitive drum 13, exposure, development, transfer to the recording paper P, and heat fixing of the toner image on the recording paper P described above is a single recording process. .

  The image forming apparatus 11 includes a control device 51 having a computer for controlling various operations. The control device 51 includes a central processing unit (CPU) 52 for calculating various potentials necessary for the recording process based on various data, and a read-only memory (ROM) 53 in which various operation programs are recorded. A random access memory (RAM) 54 capable of reading and writing and an input / output interface or power supply circuit (not shown) are provided. The control device 51 outputs a switching operation signal to the polarity switching means 48 via a drive circuit (not shown). Further, a control signal is sent from the control device 51 to the power supply circuits of the charger 15, the developing roller 24, and the transfer device 31, so that the applied voltage is controlled.

Next, the operation of the image forming apparatus configured as described above will be described based on the timing chart of FIG.
In FIG. 2, the print switch is turned on / off, the photosensitive drum 13 is rotated, the bias potential of the charger 15, the developing roller 24, and the transfer device 31, the potential of the foreign matter removing roller 41, and the potential of the residual toner capturing brush 45 are sequentially shown from the top. The charging polarity in the vicinity of the residual toner capturing brush 45 on the photosensitive drum 13, the charging polarity of the residual toner, and the charging polarity of foreign matter (paper dust) are shown.

  When the power switch (not shown) of the image forming apparatus 11 is turned on at time t1 in the timing chart of FIG. 2, the warm-up operation of the heat fixing device 35 is started. Then, at time t2 when the temperature of the heating roller 33 reaches a predetermined temperature after a predetermined time has elapsed, the photosensitive drum 13 is rotated and the charger 15 is turned on to charge the surface of the photosensitive drum 13 to +1.2 kV. The Further, the potential of the developing roller 24 is charged to −300 V, development of the uncharged portion of the photosensitive drum 13 is prevented, and the potential of the transfer device 31 is charged to +900 V, and the residual toner attached to the transfer device 31 is photosensitive. The transfer is performed on the drum 13 and the transfer unit 31 is cleaned, the potential of the foreign matter removing roller 41 is charged to +500 V, and the foreign matter on the photosensitive drum 13 is collected. Further, the potential of the residual toner capturing brush 45 is charged to −350V. The charging polarity in the vicinity of the residual toner capturing brush 45 on the photosensitive drum 13 is positive, and the charging polarity of the residual toner is also positive. The charge polarity of the foreign material remains negative. At time t3, the developing bias potential is switched from + 300V to −300V, whereby the remaining toner on the photosensitive drum 13 is collected by the developing roller 24. At time t4, the transfer device 31 is uncharged and becomes uncharged, and this process prevents toner from adhering to the transfer device 31. Further, at time t5, the rotation of the photosensitive drum 13 is stopped, the charging of the charger 15 and the developing roller 24 is released, the potential of the foreign matter removing roller 41 and the potential of the remaining toner capturing brush 45 are non-potential, and the photosensitive drum. The polarity in the vicinity of the 13th brush 45 is nonpolar, and the charge polarity of the remaining toner is also nonpolar, so that the warm-up state shifts to the standby state.

  The foreign matter (paper dust) adhering to the surface of the photosensitive drum 13 during the above-described warm-up operation is removed by the foreign matter removing roller 41, and the residual toner is captured by the residual toner capturing brush 45, and the surface of the photosensitive drum 13 is removed. Removed from.

  When the print switch is turned on at time t6 during the above-described standby, the heat fixing device 35 is heated to the target temperature for fixing, and the photosensitive drum 13 is rotated at time t7 when the target temperature is reached. At the same time, the charger 15 is turned on, the surface of the photosensitive drum 13 is charged to +1.2 kV, the developing roller 24 is charged to −300 V, and development of the uncharged portion of the photosensitive drum 13 is prevented, and the transfer device 31 is The transfer unit 31 described above is cleaned by being charged to + 900V. Further, the foreign matter removing roller 41 is charged to + 500V, and the foreign matter on the photosensitive drum 13 is collected, and the residual toner capturing brush 45 is charged to -350V, and the residual toner on the photosensitive drum 13 is collected. Thereafter, at time t8, the developing roller 24 is reversely charged from −300 V to +300 V, and thereby, development of the uncharged portion of the photosensitive drum 13 that has been neutralized by the irradiation light from the exposure device 18 becomes possible.

  Next, at time t9, the charging of the transfer device 31 is released, and toner adhesion to the transfer device 31 is prevented between time t7 and time t9. Further, at time t10, the transfer unit 31 is charged to −3.7 kV. As a result, the toner image is transferred onto the recording paper P.

  Further, at time t11, the charging of the transfer device 31 is released, and a switching signal is output from the control device 51 to the polarity switching means 48 to switch from the DC negative power source 47 to the DC positive power source 46, and the remaining toner capturing brush. A positive potential is applied to 45, and +0 V, for example, is applied to the residual toner capturing brush 45. Between time t11 and time t12 described above, the potential of the surface of the photosensitive drum 13 is nonpolar and the potential of the residual toner capturing brush 45 is positive. Therefore, the residual toner capturing brush 45 is captured by the potential difference. The positive polarity toner diffuses back to the surface of the photosensitive drum 13. This toner passes through the charger 15 charged to the positive polarity, is collected by the developing roller 24, and is reused in the next recording process.

  Further, at time t12, the transfer device 31 is charged to + 900V, the positively charged toner adhering to the transfer device 31 is returned to the photosensitive drum 13, and the residual toner capturing brush 45 is charged to -350V, and the photosensitive drum. The toner returned to 13 is captured by the capture brush 45. Thereafter, at time t13, the charged state of the transfer device 31 is released. Finally, at the time t14, the rotation of the photosensitive drum 13 is stopped, and the charging of the charger 15, the developing roller 24, the foreign matter removing roller 41, and the residual toner capturing brush 45 is released to become no potential.

  Between time t7 and time t14 described above, the foreign matter removing roller 41 remains charged with positive polarity, and therefore the negative polarity foreign matter (paper dust) on the photosensitive drum 13 is removed. Further, the remaining toner on the photosensitive drum 13 is captured by the remaining toner capturing brush 45 from time t12 to time t14. Further, the charging polarity in the vicinity of the residual toner capturing brush 45 of the photosensitive drum 13 from time t7 to time t14 is affected by the charging potential of the transfer device 31, and is negative, nonpolar, positive, nonpolar, It changes sequentially with negative polarity and nonpolarity. Further, the charging polarity of the remaining toner is kept positive from time t7 to time t14.

  The potential applied to the foreign matter removing roller 41 is kept positive from time t7 to time t14. On the other hand, the charge polarity of the foreign matter is always kept negative. Therefore, the foreign matter on the surface of the photosensitive drum 13 is efficiently moved and removed by the foreign matter removing roller 41 due to the potential difference, and is collected in the case 44 by the scraper 43.

  By the way, the printing work on the recording paper P includes a case where the printing work is performed on one recording paper P and a case where the printing work is continuously performed on a plurality of recording papers P. In the former single feed, the remaining toner capturing brush 45 is charged during the sheet passing period, and the toner captured by the remaining toner capturing brush 45 at the end of the sheet passing period is returned to the surface of the photosensitive drum 13. . In the case where the latter plural sheets are continuously fed, in a short period between the sheet passing period, when the captured toner is returned to the developing roller 24, the insufficiently charged toner is used for development. Therefore, the remaining toner capturing brush 45 is charged to maintain the remaining toner capturing state.

According to the image forming apparatus of the above embodiment, the following effects can be obtained.
(1) In the above embodiment, the foreign material (paper powder) charged on the negative electrode attached to the surface of the photosensitive drum 13 is removed from the surface of the photosensitive drum 13 using the positive foreign material removing roller 41. To be discarded. On the other hand, with respect to the residual toner that is positively charged on the surface of the photosensitive drum 13, the residual toner is temporarily captured during the paper passing period by using a dedicated residual toner capturing brush 45. After completion of the process, the residual toner catching brush 45 diffuses back to the surface of the photosensitive drum 13 and the residual toner is collected by the developing roller 24. Therefore, the foreign matter removing operation and the remaining toner capturing and recycling operations can be appropriately performed by different means, and the image quality recorded on the recording paper P can be improved.

  (2) In the above embodiment, during the operation of capturing the residual toner on the photosensitive drum 13 by the residual toner capturing brush 45, the negative polarity having the opposite polarity to the charged polarity of the positive residual toner is applied to the residual toner capturing brush 45. The electric potential of was applied. For this reason, the remaining toner can be efficiently captured.

  (3) In the embodiment described above, the foreign matter removing roller 41 precedes the remaining toner capturing brush 45 in the rotational direction of the photosensitive drum 13. For this reason, since the foreign matter removal operation can be performed first, it is possible to avoid the foreign matter from being mixed with the residual toner and adversely affecting the image quality during the residual toner capturing and collecting operation by the residual toner capturing brush 45. .

  In the meantime, according to the present invention, in the step of capturing the residual toner from the surface of the photosensitive drum 13, reverse polarity potential applying means (polarity) is applied to the residual toner capturing brush 45 to apply a potential opposite to the charged polarity of the transfer residual toner. Switching means 48) is provided. However, by setting the charging polarity on the surface of the photosensitive drum 13 and the polarity of the potential applied to the foreign matter removing roller 41 to the same polarity, the remaining toner can be captured by the remaining toner capturing brush 45 as a result. The potential applying means is equivalent to means for applying a potential having the same polarity as that of the photosensitive drum 13 to the remaining toner capturing brush 45. At this time, it is desirable to make the potential of the remaining toner capturing brush 45 larger in absolute value than the potential of the photosensitive drum 13. Specifically, it is desirable to set the potential of the photosensitive drum 13 to, for example, +600 to +1200 V, and the potential of the remaining toner capturing brush 45 to −10 to +900 V.

In addition, you may change the said embodiment as follows.
In the positive charging process, negatively chargeable toner is used, and a positive potential having a polarity opposite to that of the toner is applied to the residual toner capturing brush 45 so as to efficiently capture the residual toner. Also good.

In FIG. 1, it may be configured to switch to the ground potential instead of the DC negative power source 47.
In the above embodiment, the captured toner is recycled by the residual toner capturing brush 45, but the toner captured by the residual toner capturing brush 45 is removed from the residual toner capturing brush 45 by another cleaning means and discarded. You may do it.

  In the above embodiment, the polarity switching unit 48 is used as the reverse polarity potential applying unit. Instead, in the recording process in which the residual toner on the surface of the photosensitive drum 13 is positively charged, the residual toner capturing brush 45 is used. Only a negative potential may be applied.

  In the development process in which the charge polarity of the foreign matter on the surface of the photosensitive drum 13 is positive, the DC positive power source 42 is replaced with a DC negative power source, and a negative potential is applied to the foreign matter removing roller 41 by this power source. Good.

As a storage means for the various data and operation programs, other means such as a hard disk and a magnetic recording medium may be used instead of the ROM 53 and the RAM 54.
As the recording material, in addition to the recording paper P, a synthetic resin sheet or another sheet may be used.

1 is a partial cross-sectional view showing an embodiment of an image forming apparatus embodying the present invention. 6 is a timing chart for explaining operations of various devices of the image forming apparatus.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Image forming apparatus, 41 ... Foreign matter removal roller as foreign matter removal means, 45 ... Residual toner catching brush as residual toner catching means, 48 ... Polarity switching means

Claims (5)

An electrostatic latent image is formed on the surface of the photosensitive member charged by the charging unit by an exposure unit, the electrostatic latent image is developed by a toner type developing unit, and the developed toner image is transferred onto a recording material by a transfer unit. In the image forming apparatus adapted to transfer to
Foreign matter removing means for removing foreign matter adhering to the surface of the photoreceptor;
Residual toner capturing means for capturing untransferred residual toner remaining on the surface of the photoreceptor after transfer;
An image having a reverse polarity potential applying means for applying a potential opposite to the charged polarity of the transfer residual toner to the residual toner capturing means in the step of capturing the residual toner from the surface of the photoreceptor. Forming equipment. 2. The image forming apparatus according to claim 1, wherein the reverse-polarity potential applying unit is configured to make the residual toner capturing unit negative when the charge polarity of the residual toner on the photosensitive member is positive. 2. The image forming apparatus according to claim 1, wherein the foreign matter removing unit is provided on the upstream side of the remaining toner capturing unit with respect to the rotation direction of the photosensitive member. The image forming apparatus according to claim 1, wherein the residual toner capturing unit is a conductive fiber brush, and the foreign matter removing unit is a foreign matter removing roller. 5. The reverse polarity potential applying means according to claim 1, further comprising a polarity switching means for switching the polarity of the residual toner capturing means in order to return the toner captured by the residual toner capturing means to the surface of the photoreceptor. An image forming apparatus.

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