JP4312659B2 - Rotating brush cleaning device - Google Patents

Description

  The present invention relates to a rotary brush cleaning device used in an electrophotographic image forming apparatus.

  As is well known, in an electrophotographic image forming apparatus, the surface of the photosensitive drum is uniformly charged by a charging device while rotating the photosensitive drum (electrostatic latent image carrier), and the surface of the photosensitive drum is irradiated by a light beam. To form an electrostatic latent image on the photosensitive drum, and attach a developer to the electrostatic latent image on the photosensitive drum to form a developer image on the photosensitive drum. Is transferred from the photosensitive drum to the recording paper, and the developer image on the recording paper is fixed by heating and pressing.

  Here, examples of the charging device include a device that performs charging by corona discharge and a device that performs charging by contact with a brush. In the former corona discharge charging device, the photosensitive drum is charged in a non-contact manner, which is advantageous for uniform charging of the surface of the photosensitive drum. However, on the other hand, there is a drawback that the amount of ozone generated is large.

  The latter brush contact charging device has an advantage that ozone is hardly generated because the photosensitive drum is charged by bringing a brush to which a bias voltage is applied into contact with the surface of the photosensitive drum.

  However, the brush-contact charging device has a drawback that dirt such as residual developer on the photosensitive drum adheres to the brush and the brush becomes dirty. This contamination of the brush causes uneven charging and scratches on the photosensitive drum, and causes a reduction in image quality.

  More specifically, the developer on the photosensitive drum is not transferred onto the recording paper with 100% transfer efficiency, and a residual developer is generated on the photosensitive drum. Although this residual developer can be removed by sufficiently pressing the cleaning rubber blade or the like against the surface of the photosensitive drum, if the pressing force of the rubber blade is increased, the photosensitive layer of the photosensitive drum is scraped. Therefore, the pressure contact force of the rubber blade cannot be sufficiently increased. For this reason, a residual developer having a small particle diameter or a strong electrostatic coupling force with the photosensitive drum is not removed, and the residual developer on the photosensitive drum that has not been removed is removed from the brush of the charging device. To be adsorbed electrostatically.

  For this reason, a brush contact charging device is often provided with a cleaning mechanism for removing developer and the like attached to the brush.

For example, in Patent Document 1, the photosensitive drum and the rotating brush are rotated in opposite directions, and the photosensitive drum is charged while moving the outer periphery in the same direction at the contact portion between the photosensitive drum and the rotating brush. Further, the rotating brush is pressed against the bristles of the rotating brush while rotating the brush cleaner, thereby removing dirt from the rotating brush.
JP 2000-187373 A

  However, in Patent Document 1, there is no description about the removal of the developer attached to the brush cleaner even if the developer attached to the hair of the rotating brush is removed by the brush cleaner. For this reason, there is no developer attached to the brush cleaner. On the contrary, the developer attached to the brush cleaner may reversely transfer to the rotating brush. Therefore, it cannot be said that the developer attached to the bristles of the rotating brush is reliably removed.

  Another method of removing the developer and the like attached to the brush is to electrically remove the residual developer from the brush. However, in this method, since the electric field for removing the residual developer and the charging polarity of the photosensitive drum are reversed, the charging characteristics of the photosensitive drum are adversely affected.

  Furthermore, such a problem with a rotating brush is common to a static elimination brush that performs static elimination by contacting a photosensitive drum or a cleaning brush that performs cleaning by contacting a photosensitive drum or the like. Uneven charge removal and uneven cleaning occurred.

  Therefore, the present invention has been made in view of the above-described conventional problems, and it is possible to reliably remove dirt such as developer adhering to the hair of the rotating brush and to prevent the hair of the rotating brush from being disturbed. It is an object of the present invention to provide a rotary brush cleaning device that can be used.

In order to solve the above-described problems, the present invention provides a cleaning device for a rotating brush that cleans a rotating brush that comes into contact with or slides on an electrostatic latent image carrier in order to apply a potential to the electrostatic latent image carrier. A sliding member pressed against the bristles of the rotating brush on the downstream side in the rotational direction of the rotating brush with respect to the contact portion with the electrostatic latent image carrier, and a rotating brush on the downstream side of the rotating brush in the rotating direction of the rotating brush with respect to the sliding member. And a foamed elastic body pressed against the hair.

  In the present invention, the sliding member has a smooth surface, and the smooth surface is pressed against the bristles of the rotating brush to align the direction of the bristles of the rotating brush.

  Furthermore, in the present invention, the foamed elastic body is a continuous foamed foamed elastic body.

  In the present invention, the foamed elastic body is sealed on the other surfaces except the contact surface with the rotating brush and the discharge surface for discharging the developer and the like that has entered the foamed elastic body.

  Further, in the present invention, the rotating brush contacts the lower surface of the electrostatic latent image carrier.

  According to the present invention, the sliding member pressed against the bristles of the rotating brush and the continuous foamed foamed elastic body are provided. Since a large number of cells (bubbles) are formed on the surface of the foamed elastic body, when the foamed elastic body is pressed against the bristles of the rotating brush, each cell hole on the surface of the foamed elastic body causes the bristles of the rotating brush to move. Dirt such as developer adhering to the surface is scraped off, and further, dirt such as developer is absorbed into the foamed elastic body through the cells. For this reason, the dirt such as the developer adhering to the bristles of the rotating brush is surely removed, and the electrostatic latent image carrier may be charged unevenly or damaged due to the dirt such as the developer adhering to the bristles of the rotating brush. Can be prevented. However, when the foamed elastic body is brought into pressure contact with the bristles of the rotating brush, the direction of the bristles of the rotating brush is disturbed. Therefore, the sliding member aligns the bristles of the rotating brush that is in pressure contact with each other and moves in a certain direction. As a result, uneven charging on the surface of the latent electrostatic image bearing member due to disturbance in the direction of the bristles of the rotating brush can be prevented.

  Accordingly, the foamed elastic body is pressed against the bristles of the rotating brush to remove dirt such as developer adhering to the bristles of the rotating brush. The hairs are aligned in a certain direction. This prevents uneven charging of the surface of the electrostatic latent image carrier caused by dirt such as developer adhering to the bristles of the rotating brush, and prevents the surface of the electrostatic latent image carrier from being disturbed by the orientation of the bristles of the rotating brush. The charging unevenness is prevented from occurring.

  On the other hand, according to the cleaning device of the present invention, the sliding member that is in pressure contact with the bristles of the rotating brush is provided on the downstream side in the rotation direction of the rotating brush with respect to the contact portion with the surface of the electrostatic latent image carrier. The foamed elastic body is provided in pressure contact with the bristles of the rotating brush. Here, not only the bristles of the rotating brush are aligned in a certain direction by the sliding member, but also a large number of bristles of the rotating brush are pushed apart to expose the vicinity of the base of each bristles. Then, the foamed elastic member on the downstream side of the sliding member is pressed near the base of each hair, and the dirt such as the developer attached near the base of each hair is scraped off by the foamed elastic body. As a result, uneven charging on the surface of the electrostatic latent image carrier due to contamination of the developer or the like attached to the bristles of the rotating brush, and uneven charging on the surface of the electrostatic latent image carrier due to disorder of the direction of the bristles of the rotating brush. Is prevented.

  For example, the bristles of the rotating brush are pressed against the smooth surface of the sliding member to align the direction of the bristles of the rotating brush.

  Further, as the foamed elastic body, a continuous foamed foamed elastic body is used. In this continuous foamed foamed elastic body, each cell formed by continuous foaming is connected, so that dirt such as developer quickly circulates through each cell and absorbs more dirt such as developer. Is possible. Further, if the other surfaces except the contact surface between the rotating brush and the foamed elastic body and the discharge surface for discharging the developer that has entered the foamed elastic body are sealed, the developer attached to the hair of the rotating brush, etc. The dirt is absorbed from the contact surface of the foamed elastic body, circulates through each cell of the foamed elastic body, and further discharged from the discharge surface of the foamed elastic body. This makes it possible to remove a large amount of dirt such as developer from the hair of the rotating brush.

  According to the present invention, the rotating brush is in contact with the lower surface of the electrostatic latent image carrier. In this case, the developer such as the developer of the rotating brush is removed by each cell of the foamed elastic body without being against gravity, and the developer and the like is distributed to the discharge surface through each cell and discharged. And the removal efficiency of dirt is improved.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a side view showing an image forming apparatus to which the present invention is applied. The image forming apparatus 1 includes a document transport unit 2, a document reading device 3, a printing unit 4, a recording paper transport unit 5, a paper feed unit 6, and a paper discharge tray 7.

  When at least one document is set on the document set tray 11, the document transport unit 2 pulls out the document one by one from the document set tray 11 and transports the document when the leading edge of the document reaches the PS roller 12. Is temporarily stopped so that the leading edge of the document is parallel to the PS roller 12. Then, after synchronizing with the image recording operation by the printing unit 4, the clutch between the PS roller 12 and the drive shaft is turned on, the PS roller 12 is rotationally driven, and the original is re-conveyed by the PS roller 12. Is passed between the platen glass 8 a and the document pressing plate 9.

  In the document reading device 3, when the document is transported, the document is exposed by the first scanning unit 15, and the reflected light from the document is guided to the imaging lens 17 by the first and second scanning units 15, 16, thereby forming the imaging lens. The original image is formed on a photoelectric conversion element (hereinafter referred to as CCD) 18 by 17. The CCD 18 repeatedly scans and reads the document in the main scanning direction, and outputs image data indicating the document.

  When the document is placed on the platen glass 8b, the first and second scanning units 15 and 16 are moved while maintaining a predetermined speed relationship with each other, and the first scanning unit 15 moves the platen glass 8b onto the platen glass 8b. The original is exposed, reflected light from the original is guided to the imaging lens 17 by the first and second scanning units 15 and 16, and the original is imaged on the CCD 18 by the imaging lens 17.

  The image data output from the CCD 18 is subjected to various image processing by a control circuit such as a microcomputer and then output to the printing unit 4.

  The printing unit 4 records a document indicated by image data on a recording sheet, and includes a photosensitive drum 21, a brush charging device 22, a laser scanning unit (hereinafter referred to as LSU) 23, a developing unit 24, and a transfer unit 25. , A cleaning device 26, a static eliminator (not shown), a fixing device 27, and the like. The photosensitive drum 21 rotates in one direction. After the surface is cleaned by the cleaning device 26 and the static eliminator, the surface is uniformly charged by the brush charging device 22. The laser scanning unit 23 modulates the laser light according to the image data, and repeatedly scans the surface of the photosensitive drum 21 in the main scanning direction with the laser light to form an electrostatic latent image on the surface of the photosensitive drum 21. The developing device 24 supplies toner to the surface of the photosensitive drum 21 to develop the electrostatic latent image, and forms a visible image of the toner on the surface of the photosensitive drum 21. The transfer device 25 transfers the visible toner image on the surface of the photosensitive drum 21 onto the recording paper conveyed by the recording paper conveyance unit 5. The fixing device 27 heats and pressurizes the recording paper to fix the visible toner image on the recording paper. Thereafter, the recording sheet is further conveyed to the sheet discharge tray 7 by the recording sheet conveying unit 5 and discharged.

  The recording paper transport unit 5 includes a PS roller 28, a transport roller 29, a transport path 31, a reverse transport path 32, a paper discharge roller 33, a branch claw 34, and the like for transporting the recording paper. In the conveyance path 31, the recording paper is received from the paper feeding unit 6, and when the leading edge of the recording paper reaches the PS roller 28, the conveyance of the recording paper is temporarily stopped, and the leading edge of the recording paper is parallel to the PS roller 28. Thereafter, the recording paper is conveyed to the transfer unit 25 of the printing unit 4 by the PS roller 28, and the recording paper is further conveyed to the paper discharge unit 7. Further, when an image is also recorded on the back side of the recording paper, the branching claw 34 is rotated to switch the branch path between the transport path 31 and the reverse transport path 32, and then the recording paper is transferred from the transport path 31 to the reverse transport path 32. Transport in the opposite direction. In the reverse conveyance path 32, when the recording sheet is received from the conveyance path 31, the recording sheet is reversed to the reverse side and then returned to the PS roller 28 in the conveyance path 31. As a result, an image is also recorded on the back surface of the recording paper. A plurality of detection switches for detecting the passage of the recording paper are arranged in the transport paths 31 and 32, and control of the recording paper transport timing and the like is performed based on the detection of each detection switch.

  The paper feed unit 6 accommodates unused recording paper and supplies the unused recording paper to the recording paper transport unit 5, and includes a paper feed cassette 36. Recording paper is stacked and stored in the paper feed cassette 36, and the recording paper is pulled out one by one by a half-moon pickup roller 35 and conveyed. The recording paper is pulled out from the paper feed cassette 36 and conveyed to the PS roller 28.

  Next, the brush charging device 22 will be described in more detail. FIG. 2 is a side view showing the brush charging device 22. In this brush charging device 22, the bias voltage Vb of the bias voltage circuit 42 is applied to the rotating brush 41, the rotating brush 41 is pressed against the surface of the photosensitive drum 21, and the rotating brush 41 and the photosensitive drum 21 are moved in the respective arrow directions. The surface of the photosensitive drum 21 is charged by rotating the A and B at the same peripheral speed.

  The rotating brush 41 includes an elastic member 44 around a rotating shaft 43, the rotating shaft 43 and the elastic member 44 are arranged concentrically, and a brush cloth 45 is wound around the elastic member 44. The rotating shaft 43 is made of metal, and the elastic member 44 and the brush cloth 45 have conductivity. Therefore, the bias voltage Vb of the bias voltage circuit 42 can be applied to the brush cloth 45 through the rotating shaft 43 and the elastic member 44.

  The bias voltage circuit 42 outputs a DC voltage or a voltage obtained by superimposing an AC voltage on a DC voltage as the bias voltage Vb applied to the rotating brush 41.

  When the DC bias voltage Vb is used, the amount of ozone generated is small.

  Further, when the bias voltage Vb in which the direct current and the alternating current are superimposed is used, the amount of generated ozone is increased, and uneven charging on the surface of the photosensitive drum 21 can be further suppressed. This is because, even when sudden charge injection from the bristles of the rotating brush 41 to the surface of the photosensitive drum 21 occurs, the abdomen of the other hairs of the rotating brush 41 comes into contact with the place of sudden charge injection. This is because excess electric charge is discharged by application of an alternating voltage from another hair, and the potential at the portion becomes equal to the surrounding potential. The amplitude voltage of the AC voltage is preferably about twice or more than the DC voltage.

  Here, when the rotating brush 41 is pressed against the surface of the photosensitive drum 21 and the rotating brush 41 and the photosensitive drum 21 are rotated in the respective arrow directions A and B at the same peripheral speed, the rotating brush 41 and the photosensitive drum are rotated. 21, the outer periphery of the rotary brush 41 and the outer periphery of the photosensitive drum 21 move in the same direction at the same speed. The direction of the inclination of the bristles of the rotary brush 41 is set so that the bristles are ordered in the rotation direction of the surface of the photosensitive drum 21. For this reason, as shown in FIG. 3, the bristle portion of the rotary brush 41 slides on the surface of the photosensitive drum 21 without the tip of the rotary brush 41 hitting the surface of the photosensitive drum 21.

  As a result, the bristles of the rotating brush 41 are prevented from colliding with the surface of the photosensitive drum 21 to be disturbed, and the bristles of the rotating brush 41 slide on the surface of the photosensitive drum 21 and are blown away in the circumferential direction of the rotating brush 41. As a result, the bristles of the rotating brush 41 are always aligned in the circumferential direction.

  In this way, if the bristles of the rotating brush 41 are always aligned in the circumferential direction, the arrangement of the bristles will not appear as uneven charging on the surface of the photosensitive drum 21, and the surface of the photosensitive drum 21 will be uniformly charged. Is done. If the rotation of the bristles of the rotating brush occurs, the arrangement of the bristles appears as uneven charging on the surface of the photosensitive drum 21.

  In addition, since the bristles of the rotating brush 41 do not hit the surface of the photosensitive drum 21, no sudden charge injection from the bristles of the rotating brush 41 to the surface of the photosensitive drum 21 occurs. There is no occurrence of uneven charging on the surface of the drum 21. If the tip of the rotating brush hits the surface of the photosensitive drum 21, electric charge is suddenly injected from the tip of the rotating brush to the surface of the photosensitive drum 21, causing uneven charging on the surface of the photosensitive drum 21.

  FIGS. 4A and 4B show a gray image 51 of a certain gradation level recorded in a state where the hair of the rotary brush 41 slides on the surface of the photosensitive drum 21 as in this embodiment, and the rotary brush 41 A comparison is made with a gray image 52 of a constant gradation level recorded in a state where the hair tip abuts against the surface of the photosensitive drum 21. As is clear from this comparison, the gray image 51 according to this embodiment has a uniform gradation level, whereas the gray image 52 has a large number of lines. This is because the tip of the rotating brush abuts against the surface of the photosensitive drum 21, and charges are rapidly injected from the tip of the hair, resulting in linear charging unevenness on the surface of the photosensitive drum 21.

  In addition, when the tip of the rotating brush 41 or the abdomen of the hair slides on the surface of the photosensitive drum 21, the mechanical resistance between the rotating brush 41 and the photosensitive drum 21 is small, and the bristles of the rotating brush 41 and the photosensitive member. The surface of the drum 21 is not easily worn. Further, since the mechanical resistance between the rotating brush 41 and the photosensitive drum 21 is small, it is not necessary to increase the rotational torque of the photosensitive drum 21. Therefore, the rotation unevenness generated when the rotational torque of the photosensitive drum 21 is increased does not occur, and the banding 53 (streaky image unevenness) as shown in FIG. 5 does not occur.

  Furthermore, since the elastic member 44 is provided around the rotation shaft 43, when the rotary brush 41 is pressed against the photosensitive drum 21, not only the hair of the rotary brush 41 but also the elastic member 44 is elastically deformed. Due to the elastic deformation of the elastic member 44, the bristles of the rotating brush 41 are deformed more flexibly than when there is no elastic member 44, and contact the surface of the photosensitive drum 21 uniformly. As a result, the surface of the photosensitive drum 21 is more uniformly charged.

  Further, since the belt-like brush cloth 45 is spirally wound as shown in FIG. 6, the joint of the belt-like brush cloth 45 is spiral. For this reason, when the bristles of the rotating brush 41 are brought into contact with the photosensitive drum 21 and the rotating brush 41 and the photosensitive drum 21 are rotated, the influence of the joint of the brush cloth 45 on the surface of the photosensitive drum 21 is less likely to appear.

  Alternatively, in a state where the rotating brush 41 is not pressed against the photosensitive drum 21, it is considered that the density of the hair is lowered by the spiral seam, which causes uneven charging. However, in a state where the rotating brush 41 is pressed against the photosensitive drum 21, the hair of the rotating brush 41 is flexibly deformed by the elastic deformation of the elastic member 44, and the surrounding hair approaches the spiral seam. Even in the vicinity of the seam, the density of the hair increases, the hair of the rotating brush 41 uniformly contacts the surface of the photosensitive drum 21, and the surface of the photosensitive drum 21 is uniformly charged.

  Furthermore, since not only the hair of the rotating brush 41 but also the elastic member 44 is elastically deformed, the pressures of a large number of hairs contacting the surface of the photosensitive drum 21 are made uniform, and the arrangement of the hairs is prevented from being disturbed. Thereby, the uniform charging of the surface of the photosensitive drum 21 is continuously maintained.

  Moreover, since both the hair of the rotating brush 41 and the elastic member 44 are deformed, the load on the hair of the rotating brush 41 is reduced, and the hair of the rotating brush 41 is less likely to be wrinkled. In addition, even if the hair of the rotating brush 41 has a bedding, the recovery of the bedding is accelerated. Without the elastic member 44, it takes approximately half a day to recover the bedclothes, but with the elastic member 44, the recovery of the bedclothes is within 10 minutes.

  On the other hand, such a brush charging device 22 has a drawback that dirt such as residual developer on the photosensitive drum 21 adheres to the rotating brush 41 and the rotating brush 41 becomes dirty. If the rotating brush 41 is left unclean, uneven charging or scratches on the photosensitive drum 21 occur, leading to a reduction in image quality.

  Therefore, the cleaning device according to the first embodiment of the present invention is attached to the brush charging device 22 in order to clean the rotating brush 41.

  In the cleaning device of this embodiment, the sliding plate 47 is disposed on the left side of the rotating brush 41, the sliding plate 47 is pressed against the bristles of the rotating brush 41, and the bristles of the rotating brush 41 are aligned in a certain direction. In addition, the foamed elastic member 46 is disposed on the upper side of the rotating brush 41, the foamed elastic member 46 is pressed against the bristles of the rotating brush 41, and the developer, dirt, etc. attached to the bristles of the rotating brush 41 are removed.

  Here, the sliding plate 47 and the foamed elastic member 46 are sequentially arranged in the rotation direction of the rotating brush 41. For this reason, immediately after the bristles of the rotary brush 41 are pushed apart by the sliding plate 47 and the vicinity of the base of each hair is exposed, the foam elastic member 46 is pressed against the tip or the vicinity of the base of each hair, and the foam elastic body 46 removes stains such as developer adhering to the tip or root of each hair.

  The sliding plate 47 is a fluorine resin such as Teflon (registered trademark), and has a smooth surface 47a having a small friction coefficient.

  Since the friction coefficient of the smooth surface 47a of the sliding plate 47 is extremely small, a large number of hairs of the rotating brush 41 are pushed out without damaging or pulling out the hair of the rotating brush 41, thereby exposing the vicinity of the base of each hair. .

  Further, the smooth surface 47a of the sliding plate 47 aligns the bristles of the rotating brush 41 in the circumferential direction. As a result, uneven charging on the surface of the photosensitive drum 21 due to disturbance in the direction of the hair of the rotating brush 41 can be prevented.

  The foamed elastic member 46 is a sponge-like synthetic resin and includes single foaming and continuous foaming. Single foaming is a cell (bubble) that exists alone, and has no connection with other cells. Continuous foaming is a number of cells that are interconnected. There are a large number of cell holes in the pressure contact surface 46 a, the discharge surface 46 b, and the side surfaces 46 c of the foamed elastic member 46, that is, the outer peripheral surface of the foamed elastic member 46. It is connected to the cell (continuous foaming).

  The lower surface of the foamed elastic member 46 is a pressure contact surface 46 a that presses against the bristles of the rotating brush 41. The upper surface of the foamed elastic member 46 is a discharge surface 46b, and the developer recovery container 48 covers the discharge surface 46b. Both the pressure contact surface 46a and the discharge surface 46b of the foamed elastic member 46 are open. Further, each side surface 46 c of the foamed elastic member 46 is sealed with a casing 49.

  As the rotary brush 41 rotates, the pressure contact surface 46a of the foamed elastic member 46 is pressed against the tips or roots of a large number of hairs of the rotary brush 41, and the cell holes of the pressure contact surface 46a of the foamed elastic member 46 cause the rotary brush 41 to move. Dirt such as developer adhering to a large number of hairs is scraped off, and the scraped dirt such as developer is transferred to each cell hole of the pressure contact surface 46a, and each hair of the rotating brush 41 is cleaned.

  Here, the pressure contact surface 46a of the foamed elastic body 46 is formed by polishing or cutting. By this polishing or cutting, the cross-sectional shape of the edge 46e of the cell hole 46d exposed on the pressure contact surface 46a of the foamed elastic body 46 can be sharpened as shown in FIG. The sharpened edge 46e of each cell hole 46d makes it possible to satisfactorily scrape off dirt such as developer adhering to the bristles of the rotating brush 41.

  In this case, the direction of polishing or cutting with respect to the pressure contact surface 46a of the foamed elastic body 46 is made constant, the direction of the edge 46e of each cell hole 46d to be sharpened is aligned, and each sharpened as shown in FIG. The foamed elastic body 46 is arranged and pressed against the rotating brush 41 so that the direction of the edge 46e of the cell hole 46d is opposite to the moving direction A of the outer periphery of the rotating brush 41. Accordingly, it is possible to further improve the dirt scraping ability by the respective cell holes 46d of the pressure contact surface 46a of the foamed elastic body 46.

  Thus, when the cleaning of the bristles of the rotating brush 41 by the pressure contact surface 46a of the foamed elastic member 46 is continued, dirt such as developer continuously transfers to each cell hole of the pressure contact surface 46a, and the pressure contact surface 46a Each cell hole becomes full, and dirt such as developer in each cell hole on the pressure contact surface 46a enters and moves into many cells (continuous foaming) in the foamed elastic member 46. The dirt such as the developer in the foamed elastic member 46 reaches the discharge surface 46b or each side surface 46c of the foamed elastic member 46. Dirt such as developer that has reached the discharge surface 46 b of the foamed elastic member 46 is discharged into the developer recovery container 48 and recovered. Further, since the respective side surfaces 46c are sealed by the casing 49, dirt such as developer that has reached each side surface 46c of the foamed elastic member 46 avoids the respective side surfaces 46c and flows to the discharge surface 46b. It moves, finally reaches the discharge surface 46b, is discharged into the developer recovery container 48, and is recovered.

  Therefore, as the rotary brush 41 rotates, dirt such as developer adhering to the bristles of the rotary brush 41 is scraped off by the pressure contact surface 46a of the foamed elastic body 46, and dirt such as developer passes through the inside of the foamed elastic body 46. It moves to the developer collection container 48 and is collected.

  In this way, a large number of bristles of the rotating brush 41 are pushed apart by the sliding plate 47 to expose the vicinity of the base of each hair, and the foamed elastic body 46 scrapes off dirt such as developer adhering to the tip or the base of each hair. Thus, uneven charging on the surface of the photosensitive drum 21 due to contamination of the developer or the like attached to the bristles of the rotating brush 41 is prevented. Further, the sliding plate 47 aligns the bristles of the rotating brush 41 in a certain direction, and prevents uneven charging on the surface of the photosensitive drum 21 due to the disorder of the bristles of the rotating brush 41.

  By the way, according to experiments by the inventors of the present invention, the higher the cell membrane removal rate corresponding to the continuous foaming rate of the foamed elastic body 46, that is, the higher the probability that each cell of the foamed elastic body 46 communicates. It has been found that dirt such as developer quickly circulates through each cell of the foamed elastic body 46 and more dirt such as developer is absorbed.

  FIG. 8 shows experimental data in which the cell film removal rate of the foamed elastic body 46 is changed in stages, and the change in image quality associated with an increase in the number of recorded sheets is determined for each cell film removal rate. Note that “◯” indicates a good image quality, and “X” indicates a bad image quality.

  As is clear from this experimental data, for example, when the cell film removal rate of the foamed elastic body 46 is set to 10 to 20% and the probability that each cell of the foamed elastic body 46 communicates is kept low, the image forming apparatus The image quality becomes poor before the number of recorded sheets reaches 10,000. This suggests that the foamed elastic body 46 absorbs less dirt such as developer.

  When the cell film removal rate of the foamed elastic body 46 is set to 40% and the probability that each cell of the foamed elastic body 46 communicates is increased, the number of sheets recorded by the image forming apparatus reaches 10,000. Good image quality is maintained. This suggests that the foamed elastic body 46 absorbs a large amount of dirt such as developer.

  Furthermore, when the cell film removal rate of the foamed elastic body 46 is increased to more than 50% and the probability that each cell of the foamed elastic body 46 communicates is further increased, the number of sheets recorded by the image forming apparatus reaches 20000. In the case where the good image quality is maintained and the cell film removal rate is further increased to 60% to further increase the probability that each cell of the foamed elastic body 46 communicates, the number of sheets recorded by the image forming apparatus is reduced. Good image quality is maintained until reaching 30000 sheets. This suggests that the amount of dirt absorbed by the foamed elastic body 46 is increased.

  Accordingly, the higher the cell film removal rate corresponding to the continuous foaming rate of the foamed elastic body 46, the faster the dirt such as the developer flows through each cell of the foamed elastic body 46, and the more dirt such as the developer exists. It can be said that it is absorbed.

  Here, during one period of maintenance of the image forming apparatus, the cells of the foamed elastic body 46 can be continuously absorbed through the respective cells of the foamed elastic body 46 so that dirt such as developer adhering to the rotating brush 41 can be continuously absorbed. Set the film removal rate.

  In general, a period in which about 20,000 to 30,000 sheets are recorded by the image forming apparatus is often set as one period of maintenance of the image forming apparatus. More specifically, the amount of toner stored in the toner bottle 24a of the developing device 24 is set to an amount required to record about 20000 sheets or 30000 sheets. The life of the photosensitive layer of the photosensitive drum 21 is set to a length that can record about 20000 sheets or 30000 sheets.

  Therefore, the cell membrane removal rate of the foamed elastic body 46 is set to 60% or more or 80% or more based on the experimental data of FIG. When the cell film removal rate of the foamed elastic body 46 is set to 60% or more, good image quality can be reliably maintained until the number of sheets recorded by the image forming apparatus reaches 20000. Also, when the cell film removal rate of the foamed elastic body 46 is set to 80% or more, good image quality can be reliably maintained until the number of sheets recorded by the image forming apparatus reaches 30000 sheets.

  When the number of recorded sheets reaches 20000 or 30000, maintenance of the image forming apparatus is performed, and the foamed elastic body 46 is replaced together with the toner bottle 24a of the developing unit 24 or the photosensitive drum 21. Thereby, maintenance can be simplified.

  Furthermore, simultaneously with the replacement of the foamed elastic body 46, the rotary brush 41 may be replaced, or the brush charging device 22 itself may be replaced. Alternatively, if the brush charging device 22 is unitized with the photosensitive drum 21, the unit itself may be replaced.

  If the period during which about 10,000 sheets are recorded is set as the maintenance period of the image forming apparatus, the maintenance period becomes too short and the maintenance needs to be performed frequently. Further, if the period during which 40,000 sheets or more are recorded is set as the maintenance cycle of the image forming apparatus, the amount of toner stored in the toner bottle 24a of the developing device 24 is increased, and the life of each consumable part is increased. It is necessary to prolong the period, and there are many problems to be solved, which are not realistic.

  The cell membrane removal rate of the foamed elastic body 46 can be adjusted by the pressure treatment of the foamed elastic body 46. In this case, the cell membrane removal rate can be increased by increasing the pressing pressure of the foamed elastic body 46 or increasing the number of times of pressing.

  The cell membrane removal rate is adjusted by the solvent impregnation treatment of the foamed elastic body 46. In this case, the cell membrane removal rate can be increased by increasing the amount of the solvent impregnated into the foamed elastic body 46 or increasing the impregnation time.

  However, if the cell membrane removal rate of the foamed elastic body 46 is excessively increased, the strength and durability of the foamed elastic body 46 itself are lowered. It is necessary to keep the cell membrane removal rate below the level that can maintain high strength and durability.

  The cleaning device of the present invention is not limited to the above embodiment, and can be variously modified. For example, as shown in FIG. 9, a foamed elastic body 46 is provided on the downstream side in the rotational direction of the rotary brush 41 with respect to the contact portion with the surface of the photosensitive drum 21, and the rotational direction of the rotary brush 41 is downstream of the foamed elastic body 46. In addition, a sliding member 47 may be provided. In this case, the foamed elastic body 46 is pressed against the bristles of the rotating brush 41 to remove dirt such as a developer adhering to the bristles of the rotating brush 41. The hair of the rotating brush 41 can be aligned in a certain direction. As a result, uneven charging on the surface of the photosensitive drum 21 caused by dirt such as developer adhering to the hair of the rotating brush 41 is prevented, and uneven charging on the surface of the photosensitive drum 21 due to disorder of the direction of the hair of the rotating brush 41 is prevented. Is also prevented.

  FIG. 10 is a side view schematically showing Embodiment 2 of the image forming apparatus of the present invention. This image forming apparatus is for forming a color image, and includes four visible image forming units 60Y, 60M, 60C, and 60B, and a transfer fixing roller 61.

  In each of the visible image forming units 60Y, 60M, 60C, and 60B, the brush charging device 22, the laser scanning unit 63, the developing device 64, the transfer roller 65, and the cleaner 66 are disposed around the photosensitive drum 62. The developing devices 64 of the visible image forming units 60Y, 60M, 60C, and 60B store toners of yellow (Y), magenta (M), cyan (C), and black (B). In each visible image forming unit 60Y, 60M, 60C, 60B, the surface of the photosensitive drum 62 is uniformly charged by the brush charging device 22, and then the laser beam of the laser scanning unit 63 is modulated according to the image information. At the same time, the surface of the photosensitive drum 62 is irradiated with laser light to form an electrostatic latent image on the surface of the photosensitive drum 62, and toner is further adhered to the electrostatic latent image on the surface of the photosensitive drum 62 by the developing device 64. Thus, a toner image is formed on the surface of the photosensitive drum 62, and the toner image on the surface of the photosensitive drum 62 is transferred onto the intermediate transfer belt 67 by the transfer roller 65 to which a bias voltage having a polarity opposite to that of the toner is applied.

  Each visible image forming unit 60Y, 60M, 60C, 60B forms a toner image of each color on the surface of the photosensitive drum 62, and sequentially transfers the toner images of each color on the intermediate transfer belt 67. As a result, a single color toner image T is formed on the intermediate transfer belt 67. The color toner image T is transferred and fixed on the recording paper P by the transfer and fixing roller 61.

  In such a color image forming apparatus, it is necessary to provide as many brush charging devices 22 and photosensitive drums 62 as the number of toner colors. For example, if four colors are used, four sets of brush charging devices 22 and photosensitive members are used. It is necessary to provide the drum 62. Therefore, if a corona discharge charging device is used, a large amount of ozone is generated, and not only the odor of ozone but also deterioration of the photosensitive drum 62 due to ozone becomes a problem.

  However, since the brush charging device 22 is the same as the image forming apparatus of FIG. 1, the amount of ozone generated is extremely small.

  Further, since the brush charging device 22 is arranged below the photosensitive drum 21, the developer such as the developer of the rotating brush 41 is removed by each cell of the foamed elastic body 46 without resisting gravity, and the developer. Or the like can be circulated to the lower discharge surface 46b through each cell of the foamed elastic body 46 and discharged to the developer collecting container 48, and the removal efficiency of the stain is improved.

  In addition, this invention is not limited to the said Example, It can deform | transform variously. For example, the bristle of the brush cloth 45 is attached with a wrinkle that is inclined obliquely on the peripheral surface of the rotary brush 41. Instead, the bristle of the brush cloth 45 is provided radially with respect to the rotary shaft 43, and the rotary brush The outer periphery of the rotating brush 41 is moved in the same direction at the contact portion between the photosensitive drum 41 and the photosensitive drum 21 so that the peripheral speed of the rotary brush 41 is higher than that of the photosensitive drum 21. Also by this, the bristles of the rotating brush 41 are inclined so as to be in order in the rotation direction of the surface of the photosensitive drum 21, and the bristles of the brush cloth 45 are aligned and inclined in the circumferential direction of the rotating brush 41.

  Further, instead of winding and bonding the brush cloth 45 in a spiral shape, the brush cloth 45 may be wound around the elastic member 44 in a spiral manner and bonded as shown in FIG. In this case, since the bristles of the brush cloth 45 become radial with respect to the rotation shaft 43, the bristles of the brush cloth 45 can be easily aligned and inclined in the circumferential direction of the rotary brush 41.

  The cleaning device of the present invention can be applied not only to the rotating brush 41 of the brush charging device 22 but also to the cleaning brush of the cleaning device 26 and the static eliminating brush of the static eliminator (not shown) in the image forming apparatus 1. It can be applied regardless of the structure of the rotating brush.

1 is a side view showing an image forming apparatus to which the present invention is applied. FIG. 2 is a side view showing a brush charging device in the image forming apparatus of FIG. 1. FIG. 3 is an enlarged side view showing a contact state between a rotating brush and a photosensitive drum in the brush charging device of FIG. 2. (A) And (b) is a figure which compares and shows the gray image when using the brush charging device of FIG. 2, and the gray image when using the brush charging device of a comparative example. FIG. 6 is a diagram illustrating banding (streaky image unevenness) caused by rotation unevenness of a photosensitive drum. It is a perspective view which shows how to wind the brush cloth of the rotating brush in the brush charging device of FIG. It is sectional drawing which expands and shows the press-contact surface of a foaming elastic body. This is experimental data obtained by changing the cell film removal rate of the foamed elastic body step by step, and determining the change in image quality accompanying the increase in the number of recorded sheets for each cell film removal rate. It is a side view which shows the modification of the brush charging device of FIG. FIG. 6 is a side view schematically showing Embodiment 2 of the image forming apparatus of the present invention. It is a perspective view which shows the other winding method of the brush cloth of the rotating brush in the brush charging device of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Original conveyance part 3 Scanner part 4 Printing part 6 Paper feed part 7 Paper discharge apparatus 11 Original setting tray 12, 28 PS roller 15 First scanning unit 16 Second scanning unit 17 Imaging lens 18 CCD
21 Photosensitive drum 22 Brush charging device 23 Laser scanning unit 24 Developing device 25 Transfer device 26 Cleaning device 41 Rotating brush 42 Bias voltage circuit 43 Rotating shaft 44 Elastic member 45 Brush cloth

Claims (5)

In a rotating brush cleaning device for cleaning a rotating brush that is in contact with or slidably contacted with an electrostatic latent image carrier in order to apply an electric potential to the electrostatic latent image carrier,
A sliding member pressed against the bristles of the rotating brush on the downstream side in the rotation direction of the rotating brush from the contact portion with the electrostatic latent image carrier;
A foamed elastic body pressed against the bristles of the rotating brush on the downstream side of the rotating direction of the rotating brush with respect to the sliding member;
A rotary brush cleaning device comprising: 2. The rotary brush cleaning device according to claim 1, wherein the sliding member has a smooth surface, and the smooth surface is pressed against the bristles of the rotary brush to align the direction of the bristles of the rotary brush. 2. The rotary brush cleaning device according to claim 1, wherein the foamed elastic body is a continuous foamed foamed elastic body. 4. The rotating brush according to claim 3, wherein the foamed elastic body is sealed on a surface other than a contact surface with the rotating brush and a discharge surface for discharging the developer or the like that has entered the foamed elastic body. Cleaning device. 2. The rotary brush cleaning device according to claim 1, wherein the rotary brush contacts the lower surface of the electrostatic latent image carrier.

Images