JP2007304508A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To appropriately execute a refreshing process by removing deposits from the image carrier surface, while suppressing drastic occurrence of image defects. <P>SOLUTION: A printer 1 executes the refreshing process of supplying a toner onto the surface of a photoreceptor drum 21 from a development means 23 within a non-transfer period to a paper sheet P, and cleaning the deposits of the surface of the photoreceptor drum 21 by a cleaning device 30 using the toner, thereby refreshing the surface of the photoreceptor drum 21. During the execution of the refreshing process, since the rotational driving of the photoreceptor drum 21 is once stopped, the residual toners and external additives deposited on a cleaning blade 32 can be moved temporarily to the surface of the photoreceptor drum 21 and after the lapse of a prescribed time; the rotational driving of the photoreceptor drum 21 is restarted; and consequently the deposits of the cleaning blade 32, moved to the surface of the photoreceptor drum 21, can be recovered, while being polished at a polishing roller 33. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electrophotographic image forming apparatus represented by a copying machine or a printer.

  In an electrophotographic image forming apparatus such as a copying machine or a printer, a photosensitive drum is widely used as an image carrier. A general image forming operation using the photosensitive drum is as follows. The surface of the photosensitive drum is uniformly charged with a predetermined potential by a charging device, and by irradiating the LED light or the like of the exposure device there, the potential is partially attenuated to form an electrostatic latent image of an original image. Is done. By developing the electrostatic latent image with a developing device, a toner image is formed on the surface of the photosensitive drum. The toner image is transferred onto the sheet when the sheet is inserted into a transfer region formed by bringing the photosensitive drum and the transfer member into contact with or in close proximity to each other.

  In such an image forming apparatus, after a toner image is transferred to a sheet, a small amount of toner may remain on the surface of the photosensitive drum without being transferred to the sheet. The residual toner adhering to the surface of the photosensitive drum becomes an obstacle to the next new image formation, so that it needs to be cleaned. As a cleaning method used for such a purpose, a method of moving and collecting residual toner on the rotating member by pressing a cleaning roller, a rotating brush, or the like that is a rotating member on the surface of the photosensitive drum, or a surface of the photosensitive drum A method of scraping residual toner by bringing a cleaning blade into contact therewith, or a cleaning method combining these methods is widely known.

  On the other hand, when an amorphous silicon photoconductor is used as the photoconductor, it is known that discharge products easily adhere to the surface of the photoconductor due to the discharge of the charging device. When this discharge product absorbs moisture, the electrical resistance on the surface of the photoreceptor is lowered, and a problem of image flow that disturbs the electrostatic latent image may occur. For this reason, a small amount of abrasive is mixed into the toner as an external additive, and a residual roller adhering to the surface of the photoreceptor is removed by using a polishing roller as a rotating member and a cleaning blade in combination. A method is known in which the discharge product and water adhering to the surface of the photoreceptor are polished by being carried on the surface and polished by this toner.

As described above, Patent Documents 1 to 3 show examples of cleaning methods for removing discharge products and moisture adhering to the surface of the photosensitive drum using a polishing roller. An image forming apparatus described in Patent Document 1 and Patent Document 2 includes a polishing roller (sliding roller) that contacts a photosensitive drum and polishes the surface thereof, and a cleaning blade provided on the downstream side in the drum rotation direction. And a polishing roller for cleaning the surface of the photosensitive drum so as to be polished with toner removed directly from the surface of the photosensitive drum or moved by being removed by the cleaning blade. The image forming apparatus described in Patent Document 3 refreshes the surface of the photoconductor by refreshing the surface of the photoconductor by supplying and polishing the toner from the developing device to the photoconductor drum during a non-transfer period to the paper separately from the normal printing operation mode. Has a mode.
Japanese Patent Laid-Open No. 10-63157 (page 2-3, FIG. 1) Japanese Patent Laying-Open No. 2005-49620 (page 3-5, FIG. 1) Japanese Patent Laid-Open No. 11-3014 (page 3, FIG. 1)

  In the refreshing process for refreshing the surface of the photoconductor as described above, in addition to the discharge products and moisture, all the deposits including residual toner and external additives themselves are removed from the surface of the photoconductor and cleaned. However, when the refresh process is performed, residual toner and external additives accumulated on the cleaning blade aggregate at the edge of the blade, and when the refresh process is completed and the photosensitive drum is stopped, the toner adheres again to the surface of the photoreceptor. There is a possibility that a problem such as will occur. As a result, when the operation of the image forming apparatus is started for image formation on the sheet next time, the portion where the residual toner or the external additive has adhered is not light attenuated even when the exposure apparatus is irradiated with light. The high potential is maintained. As a result, there is a possibility that a white streak may occur in a portion on the paper where an image should be originally formed with toner.

  The present invention has been made in view of the above points, and in an image forming apparatus that executes a refreshing process for removing and refreshing deposits on the surface of an image carrier by a cleaning device provided with a polishing roller and a cleaning blade. It is an object of the present invention to provide an image forming apparatus capable of suitably performing a refreshing process on the surface of an image carrier while devising so as to suppress remarkable occurrence of image defects.

  In order to solve the above problems, the present invention is provided with an image carrier, a developing device for supplying toner to an electrostatic latent image formed on the surface of the image carrier, and developing, a polishing roller, and a cleaning blade. A cleaning device for cleaning deposits remaining on the surface of the image carrier after transferring the toner image to the paper, and supplying the toner from the developing device to the image carrier within a non-transfer period to the paper. In the image forming apparatus that executes a refresh process for refreshing the surface of the image carrier by cleaning the deposits on the surface of the image carrier using a cleaning device, the image carrier is driven to rotate during the refresh process. The operation was temporarily stopped, and the rotation of the image carrier was resumed after a predetermined time.

  In the image forming apparatus having the above configuration, the toner contains titanium oxide as an external additive.

  According to the configuration of the present invention, in the image forming apparatus that executes the refresh process of removing the deposits on the surface of the image carrier and refreshing by the cleaning device provided with the polishing roller and the cleaning blade, Since the rotational driving of the image carrier is temporarily stopped, residual toner and external additives accumulated on the cleaning blade can be temporarily moved to the surface of the image carrier. Since the rotation of the image carrier is resumed after a predetermined time has elapsed, the cleaning blade deposit moved to the surface of the image carrier can be collected while being polished by the polishing roller. In this way, the residual toner and external additives accumulated on the cleaning blade aggregate at the edge of the blade and reattach to the surface of the image carrier when the refresh process is completed and the image carrier is stopped. Can be prevented. Therefore, it is possible to suppress the occurrence of a problem that white streaks enter a portion on the paper where an image should be originally formed with toner. As a result, it is possible to obtain an image forming apparatus capable of suitably performing the refreshing process on the surface of the image carrier while devising to suppress the remarkable occurrence of image defects.

  In addition, since the toner contains titanium oxide as an external additive, it has an excellent effect on polishing the surface of the image carrier, but on the other hand, it has a characteristic that it easily adheres to the surface of the image carrier. By applying the image forming apparatus of the present invention, it is possible to prevent reattachment to the surface of the image carrier after the refresh process is completed. While maintaining the polishing performance of the surface of the image carrier suitably, it is possible to suppress the remarkable occurrence of image defects.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

  First, an outline of the structure of an image forming apparatus according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a left side view of a schematic vertical section showing a schematic structure of a color printer which is an example of an image forming apparatus. This color printer is a type using an intermediate transfer belt. In FIG. 1, the right side is the front side of the printer, and the left side is the back side.

  As shown in FIG. 1, a paper cassette 3 is disposed below the inside of the main body 2 of the printer 1. Inside the paper cassette 3, paper P is stacked and stored. Then, the paper P is sent out toward the upper right of the paper cassette 3 in FIG. The paper cassette 3 can be pulled out horizontally from the front side of the main body 2, that is, from the right side in FIG.

  A paper feed paper transport path 4, a paper feed transport roller 5, a registration roller 6, and an image forming unit 20 are disposed downstream of the paper cassette 3 in the paper transport direction. The image forming unit 20 includes a photosensitive drum 21 which is a rotating image carrier at the center thereof. The photosensitive drum 21 rotates counterclockwise in FIG. Around the photosensitive drum 21, a charging device 22, a developing device 23, and a drum cleaning device 30 are sequentially arranged along the rotation direction.

The developing device 23 is mainly composed of a rotary rack 23a which is a rotating body that rotates clockwise in FIG. 1, and a total of four developing devices are arranged at equal intervals in the circumferential direction on the rotary rack 23a. The four developing devices are a black developing device 23B, a cyan developing device 23C, a magenta developing device 23M, and a yellow developing device 23Y. The rotary rack 23a is rotated by driving means (not shown), and the four developing devices are sequentially moved to positions facing the photosensitive drum 21 to form toner images of respective colors on the surface of the photosensitive drum 21. . The toner contains titanium oxide (TiO ₂ ) as an external additive, that is, an abrasive.

  An intermediate transfer belt 40 using an intermediate transfer member in the form of an endless belt is disposed immediately below the photosensitive drum 21. The intermediate transfer belt 40 is pressed against the photosensitive drum 21 from below to form a primary transfer nip portion. The intermediate transfer belt 40 is supported by being wound around a plurality of rollers, and rotates clockwise in FIG.

  A secondary transfer unit 50 is disposed at a position where the intermediate transfer belt 40 is suspended on the sheet conveyance path. The secondary transfer unit 50 includes a secondary transfer roller 51. The sheet P is inserted through a secondary transfer nip portion formed by press-contacting the intermediate transfer belt 40 and the secondary transfer roller 51. Note that the secondary transfer roller 51 is movable in the vertical direction in FIG. 1 and is pressed against or separated from the intermediate transfer belt 40 as necessary.

  A belt cleaning device 60 is provided downstream of the secondary transfer unit 50 in the sheet conveyance direction. The cleaning roller 61 of the belt cleaning device 60 is also pressed against or separated from the intermediate transfer belt 40 as necessary.

  An optical unit 7 is provided above the image forming unit 20, and a laser beam L is emitted from the optical unit 7 toward the photosensitive drum 21. A one-dot chain line in the figure indicates the laser beam L.

  A fixing unit 8, a discharge paper transport path 9, and a paper discharge unit 10 are disposed downstream of the image forming unit 20 and the secondary transfer unit 50 in the paper transport direction. The paper discharge unit 10 is provided on the upper surface of the main body 2 at a position where the printed paper P can be taken out from the outside.

  A paper conveyance path 11 for double-sided printing is disposed below the fixing unit 8 and the secondary transfer unit 50 and between the paper cassette 3. The double-sided printing paper conveyance path 11 branches from the middle of the discharge paper conveyance path 9 and joins the paper feeding paper conveyance path 4 immediately upstream of the registration rollers 6.

  The printer 1 having the above configuration performs a printing operation as follows.

  The paper P before printing is stored in the paper cassette 3 in a stacked state, and is sent out separately from here. The fed paper P enters the paper feed paper transport path 4, is transported by the paper feed transport roller 5, and reaches the registration roller 6. The registration roller 6 corrects the oblique feeding of the paper P, and measures the timing of the color toner image or black toner image formed on the surface of the intermediate transfer belt 40 by the image forming unit 20 to transfer the paper P to the secondary transfer unit. Send to 50.

  On the other hand, image data signals such as characters, graphics, and patterns from an external computer (not shown) are transmitted to the printer 1, and laser light L controlled by the optical unit 7 is irradiated based on the image data. As a result, an electrostatic latent image of the original image is formed on the surface of the photosensitive drum 21 in the image forming unit 20. For this electrostatic latent image, an electrostatic latent image corresponding to each color is formed in order for each color image forming process.

  Next, among the respective colors of black, cyan, magenta, and yellow, first, a black toner image, which is the first color, is formed on the surface of the photosensitive drum 21, so that the black developing device 23 </ b> B faces the photosensitive drum 21. In addition, the rotary rack 23a rotates. The black developing device 23B develops the electrostatic latent image on the surface of the photosensitive drum 21 to form a black toner image. Thereafter, the toner image is primarily transferred onto the surface of the intermediate transfer belt 40 at a primary transfer nip portion formed by press contact between the photosensitive drum 21 and the intermediate transfer belt 40.

  After the primary transfer, the black toner remaining on the surface of the photosensitive drum 21 is removed by the drum cleaning device 30. The intermediate transfer belt 40 rotates once so as to coincide with a predetermined primary transfer position with respect to the photosensitive drum 21 in order to perform primary transfer of the next color. When the toner image to be formed is a black toner image, the primary transfer process ends here. When the toner image to be formed is a color toner image, the image forming process of development, transfer, and cleaning similar to the first color is continuously repeated for each color from the second color to the fourth color, and the surface of the intermediate transfer belt 40 A color toner image is formed by superimposing four color toner images of black, cyan, magenta, and yellow. Note that the secondary transfer roller 51 of the secondary transfer unit 50 and the cleaning roller 61 of the belt cleaning device 60 are separated from the intermediate transfer belt 40 while the toner images of the respective colors are sequentially primary-transferred to the intermediate transfer belt 40. .

  When four color toner images or black toner images are formed on the surface of the intermediate transfer belt 40, the secondary transfer roller 51 comes into pressure contact with the intermediate transfer belt 40. The toner image is transferred to the paper P sent in synchronization by the registration roller 6 at a secondary transfer nip portion formed by the intermediate transfer belt 40 and the secondary transfer roller 51 being pressed against each other. At this time, a secondary transfer bias for moving the toner onto the paper P is applied to the secondary transfer roller 51. After the secondary transfer, the toner remaining on the surface of the intermediate transfer belt 40 is removed by a belt cleaning device 60 in pressure contact with the intermediate transfer belt 40.

  Thereafter, the paper P carrying the unfixed color toner image or black toner image is sent to the fixing unit 8 and the toner image is fixed by the heat roller and the pressure roller. The paper P discharged from the fixing unit 8 is sent upward through the discharge paper transport path 9 and is discharged to the paper discharge unit 10 provided on the upper surface of the main body 2.

  When performing duplex printing, the transport direction of the paper P discharged from the fixing unit 8 is switched to the reverse direction immediately before being discharged to the paper discharge unit 10 through the discharge paper transport path 9. Then, the paper P is sent to the double-sided printing paper transport path 11, merged with the paper feed paper transport path 4 immediately upstream of the registration roller 6, and sent again to the secondary transfer unit 50.

  Next, a detailed configuration around the image forming unit 20 of the printer 1 will be described with reference to FIG. 2 in addition to FIG. FIG. 2 is a partial enlarged vertical sectional view showing the periphery of the image forming unit of the printer.

  As shown in FIGS. 1 and 2, the image forming unit 20 includes a photosensitive drum 21 as an image carrier at the center thereof. An intermediate transfer belt 40 using an intermediate transfer member in the form of an endless belt is disposed immediately below the photosensitive drum 21. With respect to the primary transfer nip portion where the photosensitive drum 21 and the intermediate transfer belt 40 are in pressure contact with each other, the developing device 23 described above is provided on the upstream side in the drum rotation direction, and the drum cleaning device 30 is provided on the downstream side. ing.

  The photoconductive drum 21 extends in the paper width direction perpendicular to the paper conveyance direction in the printer 1, that is, the paper surface depth direction in FIGS. 1 and 2, and is arranged with its axial direction horizontal. The photosensitive drum 21 is an inorganic photosensitive drum in which an amorphous silicon photosensitive layer, which is an inorganic photoconductive material, is provided on the outer side of a conductive roller-shaped substrate made of aluminum or the like by vacuum deposition or the like, and has a diameter of 30 mm. It is. The photosensitive drum 21 is rotated by a driving device (not shown) so that the peripheral speed thereof is substantially the same as the paper conveyance speed (150 mm / s).

  As shown in FIGS. 1 and 2, the intermediate transfer belt 40 is wound around a primary transfer roller 41, a tension roller 42, a driving roller 43, and a guide roller 44. The intermediate transfer belt 40 is composed of a single-layer resin belt formed only of a synthetic resin such as polyimide, or an elastic belt in which a rubber layer is laminated on the surface of such a synthetic resin. The primary transfer roller 41 is provided in the primary transfer nip portion so as to contact the photosensitive drum 21 from below via the intermediate transfer belt 40. A primary transfer bias is applied to the primary transfer roller 41 as necessary.

  As shown in FIG. 2, the cleaning device 30 for the photosensitive drum 21 includes a cleaning blade 32, a polishing roller 33 that is a polishing member, and a discharge screw 34 that is a discharge member inside the housing 31.

  The cleaning blade 32 is made of a plate-like urethane rubber and has substantially the same axial length as the photosensitive drum 21. The cleaning blade 32 is provided so as to be brought into pressure contact with the photosensitive drum 21 so that the contact portion has a predetermined linear pressure. Then, after the primary transfer of the toner image to the intermediate transfer belt 40, the cleaning blade 32 performs cleaning so as to scrape off deposits such as toner remaining on the surface of the photosensitive drum 21.

  A polishing roller 33 as a polishing member is provided in contact with the photosensitive drum 21 on the upstream side of the cleaning blade 32 in the drum rotation direction. The polishing roller 33 is configured by providing ethylene propylene rubber (EPDM) around a core metal having a diameter of 8 mm, and the diameter of the roller portion is 14 mm. The polishing roller 33 is provided to be pressed against the photosensitive drum 21 with a predetermined force by an urging means (not shown) provided at both ends of the shaft portion. The polishing roller 33 collects toner around the surface of the photosensitive drum 21 and the cleaning blade 32, cleans (polls) the surface of the photosensitive drum 21 with the toner adhering to the surface of the polishing roller 33, and removes the toner from the discharge screw 34. It plays the role of sending it out.

  The polishing roller 33 is rotated by a driving means (not shown) constituted by a motor or the like. The driving means of the polishing roller 33 can change the peripheral speed of the polishing roller 33, switch the rotation direction, and rotate the polishing roller 33 according to the rotation of the photosensitive drum 21.

  In order to efficiently clean the surface of the photosensitive drum 21, it is necessary to rotate the polishing roller 33 at a predetermined surface speed. Therefore, when the polishing roller 33 is rotated in such a direction that the surface at the contact point with the photosensitive drum 21 moves in the same direction as the surface of the photosensitive drum 21, the surface speed of the polishing roller 33 is 0 of that of the photosensitive drum 21. .8 times is desirable. When the polishing roller 33 is rotated in such a direction that the surface at the contact point with the photosensitive drum 21 moves in a direction different from the surface of the photosensitive drum 21, the surface speed of the polishing roller 33 is 1.2 of that of the photosensitive drum 21. Double is desirable.

  As shown in FIG. 2, the discharge screw 34 is provided in the housing 31 at a position further away from the photosensitive drum 21 with the polishing roller 33 interposed therebetween. The discharge screw 34 is removed from the surface of the photosensitive drum 21 and serves to discharge the toner in the housing 31 used for cleaning (polishing) to the outside of the housing 31.

  The printer 1 as described above supplies toner from the developing device 23 to the photosensitive drum 21 within a non-transfer period to the paper P, and cleans the surface of the photosensitive drum 21 by the cleaning device 30 using the toner. Then, a refresh process for refreshing the surface of the photosensitive drum 21 is executed.

  Next, the operation of the refresh process on the surface of the photosensitive drum 21 will be described with reference to FIGS. FIG. 3 is a flowchart showing the operation of the surface refreshing process of the photosensitive drum, and FIG. 4 is a control chart of the photosensitive drum and the developing device. Note that the refreshing process of the surface of the photosensitive drum 21 described in these drawings is performed immediately after the startup of the printer 1, but may be performed during another period, such as before printing during printing or between sheets. Absent.

  Prior to executing the refresh step, 100 sheets were continuously printed in an environment where discharge products and moisture easily adhere to the surface of the photosensitive drum 21, that is, in an environment where the room temperature is 32.5 ° C. and the humidity is 80%. Thereafter, the printer 1 was left unattended.

  Based on the above conditions, the printer 1 is turned on as shown in FIG. When the process proceeds to step # 101, a refresh process for the surface of the photosensitive drum 21 is started. In the subsequent step # 102, as shown in FIG. 4, the power of the drum motor that rotationally drives the photosensitive drum 21 is turned on, and the rotation of the photosensitive drum 21 is started.

  In step # 103, a refreshing electrostatic latent image is formed, and the developing bias is turned on in the developing device 23 as shown in FIG. 4, and the toner image is developed from the electrostatic latent image.

  Thereafter, the process proceeds to step # 104, and the surface of the photosensitive drum 21 is cleaned (polished) by using an external additive, that is, toner mixed with titanium oxide as an abrasive by the polishing roller 33 of the cleaning device 30. The polishing of the surface of the photosensitive drum 21 by the polishing roller 33 is performed in a period of one drum or more as shown in FIG.

  When the polishing of the surface of the photosensitive drum 21 in step # 104 is finished, in step # 105, the drum motor is turned off as shown in FIG. 4 to temporarily stop the rotation of the photosensitive drum 21. The temporary stop period is 3 seconds. At this time, the deposits deposited on the edge portion of the cleaning blade 32 due to the polishing of the surface of the photosensitive drum 21 move to the surface of the photosensitive drum 21.

  After a temporary stop for 3 seconds, the process proceeds to step # 106, where the drum motor is turned on again as shown in FIG. 4, and the rotation of the photosensitive drum 21 is resumed. In step # 107, the polishing of the surface of the photosensitive drum 21 by the polishing roller 33 of the cleaning device 30 is executed again. At this time, in step # 105, the deposit that has moved from the cleaning blade 32 to the surface of the photosensitive drum 21 is cleaned. The polishing of the surface of the photosensitive drum 21 by the polishing roller 33 is performed in a period of one drum or more as shown in FIG. 4 as in step # 104.

  When the polishing of the surface of the photosensitive drum 21 in step # 107 is completed, in step # 108, the drum motor is turned off as shown in FIG. 4 to stop the rotation of the photosensitive drum 21. Then, the process proceeds to step # 109 to finish the refresh process.

  When the refresh process of the surface of the photosensitive drum 21 shown in steps # 101 to # 109 is completed, the printer 1 enters a normal operation state.

  After performing the refreshing process on the surface of the photosensitive drum 21 as described above, a normal printing operation was performed. As a result, no white streaks occurred on the paper P, and a good printed image could be obtained. .

  Further, as a comparative example with respect to the above-described embodiment, the rotation of the photosensitive drum 21 shown in FIG. 3 and step # 105 of FIG. 4 is not temporarily stopped, and the rotation is continued from the start to the end of the refresh process. In this case, slight white streaks were visually observed on the paper P. As a result, it can be seen that applying the refresh process on the surface of the photosensitive drum 21 according to the present invention is more effective in suppressing the occurrence of image defects in addition to the removal of deposits such as discharge products and moisture. It was.

  On the other hand, as Comparative Example 2 with respect to the above embodiment, it was confirmed that white streaks were conspicuously generated on the paper P when the refreshing process of the photosensitive drum 21 was not performed at all. Thereby, the necessity of the refreshing process of the surface of the photosensitive drum 21 was recognized.

  As described above, in the printer 1 that executes the refreshing process in which the cleaning device 30 provided with the polishing roller 33 and the cleaning blade 32 removes the deposits on the surface of the photosensitive drum 21 that is an image carrier and refreshes. Since the rotation of the photosensitive drum 21 is temporarily stopped during the refresh process, the residual toner and external additive accumulated on the cleaning blade 32 can be temporarily moved to the surface of the photosensitive drum 21. Then, after the predetermined time of 3 seconds has elapsed, the rotational drive of the photosensitive drum 21 is resumed, and thus the deposit on the cleaning blade 32 moved to the surface of the photosensitive drum 21 is collected while being polished by the polishing roller 33. be able to. In this way, residual toner and external additives accumulated on the cleaning blade 32 are aggregated at the edge of the blade, and reattached to the surface of the photosensitive drum 21 when the refreshing process is completed and the photosensitive drum 21 is stopped. It is possible to prevent the occurrence of problems such as. Therefore, it is possible to suppress the occurrence of the problem that white streaks enter the portion of the paper P where the image should originally be formed with toner. As a result, it is possible to obtain the printer 1 that can suitably perform the refreshing process of the surface of the photosensitive drum 21 while devising to suppress the remarkable occurrence of image defects.

  In addition, since the toner contains titanium oxide as an external additive, the toner exhibits an excellent action for polishing the surface of the photosensitive drum 21, but on the other hand, the toner has a characteristic that it easily adheres to the surface of the photosensitive drum 21. On the other hand, by applying the printer 1 of the present invention, it is possible to prevent reattachment to the surface of the photosensitive drum 21 after completion of the refresh process. While maintaining the polishing performance of the surface of the photoconductor drum 21 suitably, it is possible to suppress the remarkable occurrence of image defects.

  Although the embodiments of the present invention have been described above, the scope of the present invention is not limited to these embodiments, and various modifications can be made without departing from the spirit of the invention.

  For example, in the above-described embodiment, the printer 1 is a color that includes the rotary rack 23a in which four developing devices are arranged at equal intervals in the circumferential direction in the developing device 23, and the endless intermediate transfer belt 40 as an intermediate transfer member. Although it is an image forming apparatus for printing, it may be an image forming apparatus for tandem color printing or an image forming apparatus for monochrome printing using only black toner without using an intermediate transfer member.

  Further, in the refreshing process of the surface of the photosensitive drum 21, the time for rotating the photosensitive drum 21 and polishing with the polishing roller 33 is set to one drum or more, and the temporary stop time of the rotation of the photosensitive drum 21 is 3 seconds. However, the polishing time and the stop time are not limited to these times, and other times may be set.

  The present invention can be used in general image forming apparatuses.

It is a model vertical cross-section left side view of a printer according to an embodiment of the present invention. FIG. 2 is a partially enlarged vertical cross-sectional view showing the periphery of an image forming unit of the printer of FIG. It is a flowchart which shows operation | movement of the refreshing process of the photoreceptor drum surface. 3 is a control chart of a photosensitive drum and a developing device.

Explanation of symbols

1 Printer (image forming device)
20 Image forming unit 21 Photosensitive drum (image carrier)
23 Developing Device 30 Cleaning Device 32 Cleaning Blade 33 Polishing Roller 40 Intermediate Transfer Belt

Claims (2)

An image carrier, a developing device that supplies toner to the electrostatic latent image formed on the surface of the image carrier, and a developing roller, a polishing roller, and a cleaning blade are provided. After the toner image is transferred to a sheet, the surface of the image carrier And a cleaning device that cleans deposits remaining on the toner, and supplies toner from the developing device to the image carrier within the non-transfer period to the paper, and the toner is applied to the surface of the image carrier using the toner. In an image forming apparatus that executes a refresh process for refreshing the surface of an image carrier by cleaning a kimono,
An image forming apparatus, wherein the rotation of the image carrier is temporarily stopped during the refresh process, and the rotation of the image carrier is resumed after a predetermined time has elapsed.   The image forming apparatus according to claim 1, wherein the toner contains titanium oxide as an external additive.

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