JP4432554B2 - Image forming apparatus - Google Patents

Description

  The present invention removes and collects the toner remaining on the surface of the image carrier after the transfer of the toner image from the image carrier carrying the toner image formed based on the electrophotographic process to the recording medium or the intermediate transfer member. A toner image is formed on the image carrier based on the cleaning device and the electrophotographic process, and the toner image is transferred to a recording medium or an intermediate transfer member, and then the toner remaining on the image carrier is removed and collected by the cleaning device. The present invention relates to an image forming apparatus.

  In an image forming apparatus such as an electrophotographic copying machine, a laser printer, a facsimile machine, or a multi-function machine, a rotating photoreceptor is charged by a charger and then exposed by a writing means to form an electrostatic latent image. The electrostatic latent image is developed by developing means to create a toner image. Then, the toner image is transferred directly or via an intermediate transfer member to a transfer medium such as recording paper, and the transferred toner image is fixed by a fixing device to form an image. On the other hand, so-called residual toner remaining on the photoreceptor without being transferred is removed and collected by a cleaning device, and the process proceeds to a new image forming process.

  As a cleaning device for removing the residual toner, for example, there is a device described in Patent Document 1. In the cleaning device of Patent Document 1, a pair of cleaning brushes each formed in a roll shape and having the bristles in contact with the photoreceptor, and a pair of toner collecting rolls each having a roll surface in contact with the pair of cleaning brushes (Detoning roll) is provided, and in this cleaning device, a pair of cleaning brushes are rotated, voltages having different polarities are applied to the cleaning brushes, and the residual transfer on the photosensitive member is caused by the brush bristles of the cleaning brushes. The toner is electrostatically adsorbed while mechanically scraping off the toner. At this time, a voltage higher than that of the cleaning brush is applied to the detoning roll, so that the toner adhering to the cleaning brush is attracted to the roll surface of the detoning roll. The toner adsorbed on the detoning roll in this way is scraped off into the toner collection chamber by the scraper and collected as waste toner. In this cleaning device, for example, a positive (+) polarity voltage is applied to a cleaning brush arranged upstream in the rotation direction of the photosensitive member, and the negative (−) polarity is charged from above the photosensitive member. The negatively charged voltage is applied to the cleaning brush disposed on the downstream side, and the positively charged toner is adsorbed from the photosensitive member.

  As a cleaning device other than the so-called W-ESB (Double-Estatic Static Brush) type cleaning device using a pair of cleaning blades as described above, a cleaning blade supported so as to be in pressure contact with a photosensitive member, There is a blade-type cleaning device provided with a disturb brush that is disposed upstream of the cleaning blade along the body moving direction and has the bristles in contact with the photoreceptor. In this blade type cleaning device, the residual toner adhering to the photosensitive member is stirred by the bristles of the rotating disturb brush, and the residual toner is mechanically scraped off from the photosensitive member by the cleaning blade. The residual toner thus scraped off is scraped into the toner recovery chamber and recovered as waste toner.

  The above-described W-ESB type cleaning device mainly uses an electrostatic attraction force for residual toner on the photosensitive member while bringing the tip of the cleaning brush into contact with the photosensitive member with a relatively small contact pressure during cleaning. Therefore, the amount of wear over time with respect to the photoreceptor can be made extremely small as compared with the blade type. Therefore, when a W-ESB type cleaning device is used as a cleaning device for a photoconductor, it is used for a photoconductor such as a photoconductor drum or a photoconductor belt, compared with a case where a blade type cleaning device is used. There is an advantage that the wear accompanying the increase in time (number of times of image formation) can be reduced and the life of the photoreceptor can be extended.

On the other hand, in a blade type cleaning device, the tip of the cleaning blade is always brought into pressure contact with the photosensitive member with a relatively large contact pressure, and the residual toner on the photosensitive member is scraped off by this cleaning blade. It is possible to maintain a high removal capability for residual toner adhering to the photoreceptor without being greatly affected by the density of the toner. Therefore, the blade-type cleaning device is suitable as a cleaning device for an image forming apparatus that forms many high-quality images at a high density or high image density.
Japanese Patent Publication No. 1-38314

  However, since the W-ESB type cleaning apparatus slides the brush bristles of the pair of cleaning blades to the photosensitive member during cleaning, when this W-ESB type cleaning apparatus is used for an image forming apparatus, it is long-term. When the brush blade of the cleaning blade causes minute scratches (scratch marks) on the surface of the photoconductor to increase, and when a high-quality image is formed in halftone as the number of image formation on the photoconductor increases. In such an image, there is a possibility that a minute image defect occurs due to the effect of the scratch mark in the image, and the image quality is deteriorated.

  On the other hand, when a blade-type cleaning device is used in an image forming apparatus, a small amount of toner remaining on the photoconductor after completion of transfer, that is, if it is continuously used at a low image density, friction between the cleaning blade and the photoconductor The resistance increases, the phenomenon that the cleaning of the photosensitive member becomes incomplete due to turning or chipping at the tip of the cleaning blade, so-called poor cleaning is likely to occur, and compared with a W-ESB type cleaning device, Since the amount of wear of the photoconductor increases as the number of image formation increases, the life of the photoconductor is shortened.

  In view of the above fact, an object of the present invention is to provide an image forming apparatus that can be used with either a pair of cleaning brushes or cleaning blades to remove toner remaining on an image carrier after completion of transfer of a toner image. May be offered.

  An image forming apparatus according to claim 3 of the present invention is provided with an intermediate transfer member for carrying a toner image, an image carrier, an image forming means for forming a toner image on the image carrier, Transfer means for transferring the toner image carried by the image forming means from the image carrier to the intermediate transfer member; and after the transfer of the toner image from the image carrier to a recording medium or intermediate transfer member, the image carrier. A plurality of image forming units each having a cleaning unit that removes and collects toner remaining on the surface of the image forming unit, and forms toner images of different colors on the image carrier by the plurality of image forming units. An image forming apparatus capable of forming a color toner image on the intermediate transfer member by transferring and superimposing the toner image on the intermediate transfer member, wherein a plurality of the image forming units are used as the cleaning unit. One of the brush cleaning device and the blade cleaning device can be selectively used, and the brush cleaning device includes a first cleaning brush that rotates while bringing the bristles into contact with the surface of the image carrier. A second cleaning brush which is disposed downstream of the first cleaning brush along the moving direction of the image carrier and rotates while bringing the bristles into contact with the surface of the image carrier; A cleaning power supply unit that applies voltages having different polarities to the brush core metal of the cleaning brush and the brush core metal of the second cleaning brush, and the brush hairs of the first and second cleaning brushes. A toner recovery member for recovering the toner from the brush bristles, the blade cleaning Location is characterized by comprising a cleaning blade to scrape off the toner from the image bearing member in pressure contact with the surface of the image bearing member.

An image forming apparatus according to claim 1 of the present invention includes an image bearing member, a developing means for forming a toner image on said image bearing member, a recording medium the toner image carried by the developing unit from the image carrier or Transfer means for transferring to an intermediate transfer member, and cleaning means for removing and collecting toner remaining on the surface of the image carrier after completion of transfer of the toner image from the image carrier to a recording medium or intermediate transfer member. In the image forming apparatus, the cleaning unit includes a first cleaning brush that rotates while bringing the bristles into contact with the surface of the image carrier, and the first cleaning brush along a moving direction of the image carrier. A second cleaning brush that is disposed on the downstream side of the image carrier and rotates while bringing the bristle into contact with the surface of the image carrier, the brush core metal of the first cleaning brush, and the second A cleaning power supply unit that applies voltages having different polarities to the brush core of the leaning brush, and the toner adsorbed from the image carrier by the bristles of the first and second cleaning brushes are collected from the bristles. A toner collecting member; a cleaning position disposed downstream of the second cleaning brush along the moving direction of the image carrier; and a standby position that is in pressure contact with the surface of the image carrier; and a standby position that is separated from the image carrier. Formed on the image carrier by the developing means, a blade driving mechanism that moves the cleaning blade to either the cleaning position or the standby position according to external control, and the developing means. And determining the image density of the toner image, and adjusting the cleaning blade according to the image density determination value. A cleaning selection means for moving or retaining the one of the cleaning position and the standby position by the serial blade drive mechanism, characterized by comprising a.

  In the image forming apparatus according to the fourth aspect, the cleaning unit includes the first and second cleaning brushes for cleaning the image carrier, and the cleaning position that presses the surface of the image carrier and the image carrier are separated from each other. A cleaning blade that can be moved to and from the standby position, and a blade drive mechanism that moves the cleaning blade to either the cleaning position or the standby position in accordance with external control. If the blade is held in the standby position, the cleaning means can function as a brush cleaning device, and the first and second cleaning brushes can clean the image carrier to remove residual toner from the image carrier. To move the cleaning blade to the standby position. If moved to the cleaning position, the cleaning means can function as a blade cleaning device without replacing the cleaning means, and the residual toner can be removed from the image carrier by cleaning the image carrier with the cleaning blade. The cleaning blade is moved to a position corresponding to a user's request, a request based on the image quality or image density of the image formed on the image carrier, a request for the life required for the image carrier, among the standby position and the cleaning position. If moved, the cleaning means can function as either a brush cleaning device or a blade cleaning device in accordance with these requirements.

  Here, when the cleaning unit functions as a brush cleaning device, the cleaning unit slides the tip ends of the pair of cleaning brushes against the image carrier at a relatively small contact pressure during cleaning, Since the residual toner on the image carrier is adsorbed to the brush hair mainly by electrostatic attraction, the amount of wear over time on the image carrier can be reduced compared to the case where it functions as a blade cleaning device. It becomes easy to extend the life of the image carrier.

  When the cleaning means functions as a blade cleaning device, the cleaning means presses the tip of the cleaning blade against the image carrier with a relatively large contact pressure, and the residual toner on the image carrier by the cleaning blade. Since the toner is scraped off and removed, it is possible to maintain a high removal capability for the residual toner adhering to the image carrier without being greatly affected by the density of the residual toner on the image carrier after the transfer is completed. It is possible to effectively prevent the image quality of the toner image formed on the image carrier from being deteriorated due to the influence of the toner remaining on the image carrier after the cleaning is completed.

An image forming apparatus according to a second aspect of the present invention includes an image carrier, a developing unit that forms a toner image on the image carrier, and a toner image carried by the developing unit from the image carrier to a recording medium or Transfer means for transferring to an intermediate transfer member, and cleaning means for removing and collecting toner remaining on the surface of the image carrier after completion of transfer of the toner image from the image carrier to a recording medium or intermediate transfer member. In the image forming apparatus, the cleaning unit includes a first cleaning brush that rotates while bringing the bristles into contact with the surface of the image carrier, and the first cleaning brush along a moving direction of the image carrier. A second cleaning brush that is disposed on the downstream side of the image carrier and rotates while bringing the bristle into contact with the surface of the image carrier, the brush core metal of the first cleaning brush, and the second A cleaning power supply unit that applies voltages having different polarities to the brush core of the leaning brush, and the toner adsorbed from the image carrier by the bristles of the first and second cleaning brushes are collected from the bristles. A toner collecting member; a cleaning position disposed downstream of the second cleaning brush along the moving direction of the image carrier; and a standby position that is in pressure contact with the surface of the image carrier; and a standby position that is separated from the image carrier. A cleaning blade that is movable between the blade, a blade drive mechanism that moves the cleaning blade to either the cleaning position or the standby position in accordance with external control, and a toner image on the image carrier by the developing means When the count value reaches a predetermined threshold value, The cleaning blade is moved from the standby position to the cleaning position by the blade driving mechanism, and is formed on the image carrier by the developing means in a state where the cleaning blade is held at the cleaning position. And cleaning selection means for returning the cleaning blade from the cleaning position to the standby position when the toner image is formed a predetermined number of times.

  As described above, according to the image forming apparatus of the present invention, any of the pair of cleaning brushes and cleaning blades can be used to remove the toner remaining on the image carrier after completion of the transfer of the toner image.

  Hereinafter, a laser printer according to an embodiment of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 shows a schematic configuration of a laser printer according to the first embodiment of the present invention, and FIG. 2 shows a configuration of an image forming unit in the laser printer shown in FIG. The laser printer 100 is capable of forming a color image and a single color image on a recording medium such as recording paper based on a so-called electrophotographic process.

  As shown in FIG. 1, the laser printer 100 is provided with an endless intermediate transfer belt 102 stretched by a plurality of rolls 103, and four in the horizontal portion on the upper side of the intermediate transfer belt 102. The image forming units 104 </ b> Y, 104 </ b> M, 104 </ b> C, and 104 </ b> K are sequentially arranged along the moving direction (arrow M direction) of the intermediate transfer belt 102. The image forming units 104Y, 104M, 104C, and 104K respectively correspond to a yellow (Y) component, a magenta (M) component, a cyan (C) component, and a black (K) component in a color image formed by the laser printer 100. And having the same configuration and function except that toner images are formed using toners of different colors (Y, M, C, and K). For this reason, in the following description, when it is not necessary to distinguish the four image forming units 104Y, 104M, 104C, and 104K, they are simply referred to as “image forming unit 104”.

  As shown in FIGS. 2 and 5, the image forming unit 104 is provided with a photosensitive drum 12 as a toner image carrier, and a brush cleaning device 10 (see FIG. 2) on the outer peripheral side of the photosensitive drum 12. 1) and a blade cleaning device 210 (see FIG. 5).

  Here, the brush cleaning device 10 is configured as a so-called W-ESB (Double-Eelectro Static Brush) type including a pair of cleaning brushes 16 and 18 for removing residual toner from the photosensitive drum 12. The blade cleaning device 210 is configured as a so-called blade type having a cleaning blade 212 for removing residual toner from the photosensitive drum 12. Further, in the laser printer 100 according to the present embodiment, either the brush cleaning device 10 or the blade cleaning device 210 is assembled to the image forming unit 104 according to the judgment of a device administrator such as a maintenance operator, an operator, or a user. In other words, the brush cleaning device 10 and the blade cleaning device 210 are compatible.

  The photosensitive drum 12 has an outer peripheral surface serving as an image bearing surface 14 on which an image (toner image) is formed based on an electrophotographic process. On the outer peripheral side of the photosensitive drum 12, FIGS. As shown in FIG. 1, an erase lamp 29, a charger 20, a surface potential meter 22, a developer 24 (see FIG. 1), a carrier catch on the downstream side of the cleaning devices 10 and 210 along the rotation direction (arrow RD direction). A roll 26 and a primary transfer roll 28 are arranged in order. Here, the erase lamp 29 irradiates the image bearing surface 14 of the photosensitive drum 12 that has been cleaned by the brush cleaning device 10 with the charge-removing light to remove the charge from the image bearing surface 14, and the charged region is discharged to the charger. 20 is charged to a predetermined image forming start potential (for example, 400 V to 800 V).

  In the laser printer 100, laser scanners 142 are arranged above the image forming units 104Y, 104M, 104C, and 104K, respectively, and these laser scanners correspond to Y component, M component, C component, or K component. The image of the photosensitive drum 12 in each of the image forming units 104Y, 104M, 104C, and 104K charged to the image forming start potential by the laser beams LY, LM, LC, and LK (see FIG. 1) modulated based on the image information to be performed. The carrying surface 14 is scanned to form an electrostatic latent image on the image carrying surface 14.

  In the image forming unit 104, the developing device 24 is charged with normal polarity (in this embodiment, negative (−) polarity) to deposit the toner on the roll surface of the developing roll 25, and this toner is applied to the developing roll. The electrostatic latent image is developed into a toner image by selectively attaching toner from 25 to the exposed area or non-exposed area of the electrostatic latent image formed on the photosensitive drum 12, and this toner image is developed into the primary transfer roll 28. Is transferred from the photosensitive drum 12 to the intermediate transfer belt 102. At this time, the primary transfer roll 28 causes an electrostatic attraction force to act on the toner image on the image carrying surface 14 via the intermediate transfer belt 102 to transfer the toner image (toner) onto the intermediate transfer belt 102.

  In the laser printer 100, when forming a color image, the Y component formed on the photosensitive drum 12 of each of the image forming units 104Y, 104M, 104C, and 104K through the process (electrophotographic process) described above, The toner images of the M component, C component, and K component are sequentially transferred to the intermediate transfer belt 102, and these toner images are superimposed on the intermediate transfer belt 102, thereby forming a full-color toner image on the intermediate transfer belt 102. .

  As shown in FIG. 1, the laser printer 100 is provided with a secondary transfer roll 106 on the downstream side of the image forming unit 104 along the moving direction of the intermediate transfer belt 102. A belt cleaning device 108 is provided between the image unit 104 and the image unit 104. Further, the laser printer 100 is provided with a paper feed transport mechanism 110, a paper discharge transport mechanism 112, and a fixing device 114 below the intermediate transfer belt 102.

  Here, in conjunction with image formation on the intermediate transfer belt 102, the paper feeding / conveying mechanism 110 separates one recording paper P from a bundle of recording paper P stored in the stacker 116, and this recording paper P is removed. The sheet is conveyed along the guide plate 118 to a secondary transfer position between the secondary transfer roll 106 and the intermediate transfer belt 102. The paper discharge transport mechanism 112 receives the recording paper P discharged from the secondary transfer position by the guide plate 120 and transports the recording paper P to the fixing device 114 by the transport belt 122. The fixing device 114 holds the recording paper P conveyed by the paper discharge conveyance mechanism 112 in a pressurized state between the pressure roll 124 and the heating roll 126 heated to a predetermined temperature, Discharge from the nip. As a result, the toner image on the recording paper P is fixed by heat and pressure applied by the rolls 124 and 126. The recording paper P on which the toner image is fixed is discharged and stacked on a recording paper P stacking unit (not shown) such as a paper discharge tray.

  As shown in FIG. 1, the belt cleaning device 108 is provided with a housing 128 and a cleaning blade 130 made of an elastic material such as urethane rubber. It is supported so as to be pressed against the belt 102. The belt cleaning device 108 scrapes off the toner (residual toner) remaining in the area where the toner image on the intermediate transfer belt 102 has been transferred, into the housing 128 by the cleaning blade 130. The residual toner is discharged from the housing 128 by a toner conveying mechanism (not shown) such as an auger and stored as waste toner in a cartridge-structured container such as a toner tank.

  On the other hand, in the image forming unit 104, the toner (residual toner) remaining on the image carrying surface 14 of the photosensitive drum 12 after the transfer of the toner image by the transfer roll 28 is removed and collected by one of the cleaning devices 10 and 210. At this time, the residual toner on the image bearing surface 14 has a distribution in which the charging potential is broader than that before transfer due to the influence of corona discharge from the transfer roll 28, and the toner charged to positive (+) polarity, negative (-). A state in which a polar charge and a charge substantially neutralized are mixed.

  First, the configuration of the brush cleaning device 10 will be described. As shown in FIG. 2, the brush cleaning device 10 is provided with a housing 30 that is supported so as to face the photosensitive drum 12. The housing 30 has an image bearing surface of the photosensitive drum 12. An opening 32 that opens to face 14 is formed. In the housing 30, a pair of cleaning brushes 16 and 18 are disposed near the opening 32. Here, along the rotation direction of the photosensitive drum 12, one cleaning brush 16 is disposed on the upstream side in the housing 30, and the other cleaning brush 18 is disposed on the downstream side in the housing 30. The outer shapes of the cleaning brushes 16 and 18 are formed in a substantially roll shape.

  As shown in FIGS. 3 and 4, the cleaning brushes 16 and 18 are each provided with a brush cored bar 34 on the inner peripheral side, and extend radially outward from the outer peripheral side of the brushed cored bar 34. A large number of brush bristles 36 are provided. The brush mandrel 34 is formed in a cylindrical shape using a conductive metal material such as SUS as a raw material, and shaft portions 38 each having a diameter smaller than the center side are provided coaxially at both axial end portions thereof. ing. The pair of shaft portions 38 of the brush metal core 34 are rotatably supported by bearings (not shown) attached to the housing 30. As a result, the cleaning brushes 16 and 18 are rotatably supported by the housing 30, respectively, and are brought into pressure contact with the image carrying surface 14 of the photosensitive drum 12 while bending the tip of the brush bristles 36.

  Torque from a motor (not shown) provided on the main body side of the laser printer 100 can be transmitted to the shaft portions 38 of the pair of brush cores 34. This motor transmits torque to the brush mandrel 34 during operation of the brush cleaning device 10 to rotate the cleaning brushes 16 and 18 in a predetermined direction (arrow RB direction). At this time, the cleaning brushes 16 and 18 move in a direction opposite to the image bearing surface 14 (against direction) at a contact portion with the photosensitive drum 12 where the tip of the brush bristles 36 rotates in the direction of the arrow RD.

  As shown in FIGS. 3 and 4, the brush bristles 36 of the cleaning brushes 16 and 18 are rotated in the rotational direction of the cleaning brushes 16 and 18 (in the direction of the arrow RB) with respect to the radial direction centered on the axis of the brush metal core 34. ) It is attached to the brush metal core 34 so as to incline backward by a predetermined tilt angle θB.

Here, the inclination angle θB of the brush bristles 36 in each of the cleaning brushes 16 and 18 is set in a range of 5 ° to 45 °, and preferably 30, but is not particularly limited as long as it is within the above range. Such brush bristles 36 are obtained by, for example, cutting a pile fabric in which the bristles 36 are planted on one side at a constant density into a strip shape and winding the fabric spirally around the outer peripheral surface of the brush core metal 34. Provided. At this time, the tilt angle θB of the brush bristles 36 can be adjusted by adjusting the inclination angle of the pile fabric brush core bar 34 with respect to the axial direction. The brush bristles 36 are made of nylon in which carbon black is dispersed. The amount of carbon black added is adjusted so that the volume resistance is 10 ⁴ to 10 ⁸ Ω · cm when a voltage of 150 V is applied. Yes.

  As shown in FIG. 2, in the brush cleaning device 10, a pair of detoning rolls 40 and 42 are disposed in the housing 30. Here, one detoning roll 40 has its roll surface 44 in contact with the brush bristles 36 of the upstream cleaning brush 16, and the other detoning roll 42 has its roll surface 44 on the downstream cleaning brush. 18 brush bristles 36 are in contact.

  As shown in FIGS. 3 and 4, the detoning rolls 40, 42 are each provided with a roll core 48 on the inner peripheral side, and constant on the outer peripheral side of these roll cores 48 along the radial direction. A resistance layer 62 made of phenol resin having a thickness of 5 mm is provided. The roll metal core 48 is formed in a cylindrical shape using a conductive metal material such as SUS as a raw material, and axial portions 52 each having a diameter smaller than that of the center side are provided coaxially at both axial ends thereof. Yes. The pair of shaft portions 52 in the roll metal core 48 are rotatably supported by bearings (not shown) attached to the housing 30. Thereby, the detoning rolls 40 and 42 are rotatably supported by the housing 30, respectively. Further, a groove 54 extending in the axial direction on the outer peripheral surface is formed in the roll metal core 48 over the entire length of the roll metal core 48.

  Torque from a motor (not shown) provided on the main body side chassis of the laser printer 100 can be transmitted to the shaft portions 52 of the pair of roll cores 48. This motor rotates the detoning rolls 40 and 42 in a predetermined direction (arrow RR direction) in synchronization with the rotation of the cleaning brushes 16 and 18 when the brush cleaning device 10 is operated. At this time, the detoning rolls 40 and 42 move in a direction opposite to the tip of the bristle 36 (agenst direction) at a contact portion with the detoning rolls 40 and 42 whose roll surface 44 rotates in the arrow RB direction. To do.

The detoning rolls 40 and 42 are fitted with a pipe material 60 formed in a cylindrical shape made of phenol resin on the outer peripheral side of the roll core metal 48, and a resistance layer 62 is constituted by the pipe material 60. ing. As shown in FIGS. 3 and 4, the detoning rolls 40 and 42 are provided with an intermediate conductive layer 64 interposed between the outer peripheral surface of the roll core metal 48 and the inner peripheral surface of the resistance layer 62. ing. Here, the intermediate conductive layer 64 is made of a conductive adhesive in which carbon black is dispersed in a thermosetting resin. After the conductive adhesive is filled in the groove portion 54 of the roll core 48, the conductive layer 64 is electrically conductive. It is formed by curing the adhesive material. The intermediate conductive layer 64 fixes the resistance layer 62 (pipe material 60) to the roll core metal 48 and electrically connects the roll core metal 48 to the resistance layer 62. The components of the resistance layer 62 in the detoning rolls 40 and 42 are adjusted so that the volume resistance is 10 ⁵ to 10 ⁸ Ω · cm when a voltage of 500 V is applied.

  As shown in FIG. 2, the brush cleaning device 10 is provided with a pair of scrapers 66 in a housing 30, and these scrapers 66 are constituted by leaf springs having flexibility and conductivity. The base end side is connected and fixed to the housing 30, and the distal end portions are pressed against the roll surfaces 44 of the detoning rolls 40 and 42. The scraper 66 is supported so as to be inclined in the counter direction with respect to the moving direction of the roll surface 44 of the rotating detoning rolls 40 and 42. These scrapers 66 scrape off the toner adhering to the roll surfaces 44 of the detoning rolls 40 and 42 into the housing 30.

  The housing 30 has a bowl-shaped toner reservoir 70 formed at the lower end thereof, and the toner scraped off from the detoning rolls 40 and 42 by the scraper 66 falls into the toner reservoir 70. A screw shaft auger 72 is disposed in the toner reservoir 70, and this auger 72 rotates in synchronization with the rotation of the detoning rolls 40 and 42. As a result, the toner dropped into the toner reservoir 70 is discharged from the housing 30 while being stirred by the auger 72 and transferred to a waste toner tank (not shown). The housing 30 is provided with a plate-like sealing material 74 having elasticity at the peripheral edge of the opening 32, and this sealing material 74 has its tip end in close contact with the image carrying surface 14 of the photosensitive drum 12. ing. Thus, the toner scraped off from the image bearing surface 14 by the cleaning brushes 16 and 18 is sealed so as not to flow out of the housing 30 to the outside.

  As shown in FIG. 2, the brush cleaning device 10 is provided with a static elimination lamp 78 on the upstream side of the housing 30, and a pre-cleaning roller which is a discharge type charger on the upstream side of the static elimination lamp 78. A tron 80 is provided. The pre-cleaning corotron 80 is provided with a casing 84 so as to cover the discharge wire 82 stretched along the axial direction. The casing 84 has a cross-sectional shape of the image carrying surface 14 of the photosensitive drum 12. It is formed in a substantially U-shape opening toward the top. As a result, the casing 84 shields the periphery of the discharge wire 82 so that corona discharge occurs only between the discharge wire 82 and the image bearing surface 14. Further, the casing 84 is integrally formed with a shielding portion 86 extending toward the image carrying surface 14 at the downstream end, and the shielding portion 86 is formed from the upstream end portion of the casing 84. Compared to the distance to the image bearing surface 14, the distance from the downstream end portion of the casing 84 to the image bearing surface 14 is made sufficiently narrow. As a result, the static elimination light F emitted from the static elimination lamp 78 is shielded by the shielding portion 86, and the static elimination light F is prevented from being applied to the charged region by the pre-cleaning corotron 80 on the image bearing surface 14.

  Here, the pre-cleaning corotron 80 charges the toner (hereinafter referred to as “residual toner”) remaining on the image bearing surface 14 after completion of the transfer to the negative polarity side when the brush cleaning device 10 is operated, and the residual. The distribution of the charging polarity of the toner is shifted to the negative polarity side as a whole. The neutralization lamp 78 irradiates the image carrying surface 14 with static elimination light, thereby neutralizing the charge on the image carrying surface 14 and facilitating removal of residual toner from the image carrying surface 14.

  As shown in FIG. 2, the brush cleaning device 10 is provided with a power supply box 88 above the housing 30. In the power supply box 88, a high voltage power supply unit 90 is accommodated, and a shield substrate 92 is disposed so as to be interposed between the cleaning brushes 16 and 18 and the high voltage power supply unit 90. The high voltage power supply unit 90 is provided with a voltage adjustment circuit to which high voltage power is supplied by a high voltage power supply unit (not shown) provided on the apparatus main body side of the image forming apparatus. , 18, the roll core metal 48 of the detoning rolls 40, 42, and the scraper 66 are each applied with a voltage having a predetermined voltage value. The shield substrate 92 shields and absorbs electromagnetic noise generated from the cleaning brushes 16 and 18 to which a high voltage is applied. The controller 136 and the control unit 138 (control unit) in the laser printer 100 are affected by the influence of the electromagnetic noise. (See FIG. 2).

  Here, the voltage applied to the brush cores 34 of the cleaning brushes 16 and 18 by the high voltage power supply unit 90 is applied to VB1 and VB2, and the voltage applied to the roll cores 48 of the detoning rolls 40 and 42 is applied to VR1 and VR2 and the scraper 66. Assuming that the voltages to be applied are VS1 and VS2, the following relationships (1) and (2) are established for these voltages.

| VB1 | <| VR1 | = | VS1 | (1)
| VB2 | <| VR2 | = | VS2 | (2)
Specifically, in the present embodiment, applied voltages to the respective members are VB1 = + 250V to + 400V, VR1 = VS1 = + 650V to + 800V, VB2 = −350V to −500V, VR2 = VS2 = −750V to −900V. It is set as appropriate within the range.

  The neutralizing lamp 78 is applied to the brush core metal 34 of the cleaning brush 18 and the voltage VB <b> 2 applied to the brush core metal 34 of the cleaning brush 16 by the high-voltage power supply unit 90. The neutralizing light applied to the photosensitive drum 12 so that the surface potential difference between the image bearing surface 14 and the brush bristles 36 of the cleaning brushes 16 and 18 is equal to or lower than the discharge start voltage DV. The light intensity and light quantity of F are set.

  Specifically, the static elimination lamp 78 eliminates the electric charge so that the surface potential of the image bearing surface 14 becomes −100V to 0V. Here, the discharge start voltage DV is about 500V, and the surface potential of the brush bristles 36 of the cleaning brushes 16 and 18 is closer to 0V than the applied voltages VB1 and VB2. The surface potential difference with the 18 bristle 36 is surely smaller than 500V.

  Next, the configuration of the blade cleaning device 210 will be described. In the blade cleaning device 210, parts having the same configuration and operation as those of the brush cleaning device 10 are denoted by the same reference numerals and description thereof is omitted.

  As shown in FIG. 5, the blade cleaning device 210 is provided with a plate-like cleaning blade 212 that protrudes from the opening 32 of the housing 30 toward the photosensitive drum 12, and the cleaning blade 212 is The photosensitive drum 12 is disposed in the vicinity of the downstream end of the opening 32 along the rotation direction of the photosensitive drum 12, and the front end thereof is supported by the housing 30 so as to be in pressure contact with the image bearing surface 14 of the photosensitive drum 12. . Here, the cleaning blade 212 is formed of a material having sufficient elasticity, for example, urethane rubber, and scrapes off residual toner adhering to the image carrying surface 14 when the photosensitive drum 12 rotates from the image carrying surface 14.

  In the blade cleaning device 210, a disturb brush 214 is disposed on the upstream side of the cleaning blade 212. The disturb brush 214 has an outer shape formed in a substantially roll shape. Like the cleaning brushes 16 and 18, a brush core bar 216 is provided on the inner peripheral side, and from the outer peripheral side of these brush core bars 216. A large number of brush bristles 218 extending outward in the radial direction are provided. The brush bristles 218 are made of an insulating material having elasticity. The brush metal core 216 is rotatably supported by bearings (not shown) attached to the housing 30 via shaft portions provided at both ends in the axial direction. As a result, the disturb brush 214 is rotatably supported by the housing 30 and is brought into pressure contact with the image carrying surface 14 of the photosensitive drum 12 while the tip of the brush bristles 36 is bent.

  Torque from a motor (not shown) provided on the main body side of the laser printer 100 can be transmitted to the brush cored bar 216 of the disturb brush 214. When the photosensitive drum 12 rotates, this motor transmits torque to the brush core 216 to rotate the disturb brush 214 in a predetermined direction (arrow RF direction). At this time, the disturb brush 214 moves the tip of the bristle 218 in the same direction as the image carrying surface 14 at the contact portion with the photosensitive drum 12 rotating in the arrow RD direction. As a result, the disturb brush 214 agitates the residual toner on the image carrying surface 14 by sliding the brush bristles 218 against the image carrying surface 14 on the upstream side of the cleaning blade 212 when the photosensitive drum 12 rotates. The toner is in a state where it can be easily peeled off from the image carrying surface 14.

  As shown in FIG. 5, in the blade cleaning device 210, the static elimination lamp 78 provided in the brush cleaning device 10 is omitted, and only the pre-cleaning corotron 80 is disposed on the upstream side of the housing 30. Has been. Here, as in the case of the brush cleaning device 10, the pre-cleaning corotron 80 is a toner (hereinafter referred to as “residual toner”) that remains on the image carrying surface 14 after the transfer is completed when the blade cleaning device 210 is operated. .) To the negative polarity side, and the charge polarity distribution of the residual toner is shifted to the negative polarity side as a whole. In the blade cleaning device 210, the high-voltage power supply unit 90 is not housed in the power supply box 88, and only the shield substrate 92 is disposed. In place of the high voltage power supply unit 90, a noise filter substrate may be inserted.

  In the laser printer 100 configured as described above, a part of each image forming unit 104 is configured as a replaceable cartridge part. As the cartridge part, two types of process cartridges 132 and process cartridges having different configurations are used. Any of 220 can be used selectively. Here, the process cartridge 132 (see FIG. 2) includes at least the photosensitive drum 12 and the brush cleaning device 10 as components, and these components are integrated. The process cartridge 220 includes at least the photosensitive drum 12 and the blade cleaning device 210 as components, and these components are integrated.

  That is, in the laser printer 100, at least the photosensitive drum 12 and the cleaning devices 10 and 210 are replaced with new ones at regular intervals in order to maintain an image (toner image) formed by each image forming unit 104 with high image quality. In the laser printer 100, in order to easily replace a plurality of components in the image forming unit 104 having a certain lifetime in a short time, a plurality of components including at least the photosensitive drum 12 and the cleaning devices 10 and 210 are provided. The process cartridges 132 and 220 are integrated so that they can be replaced at the same time.

  As shown in FIGS. 2 and 5, the laser printer 100 is provided with a controller 136 for controlling the entire apparatus, and a control unit 138 for controlling the image forming unit 104 according to the control from the controller 136. Is provided. There are a total of four control units 138 corresponding to the Y, M, C, and K image forming units 104Y, 104M, 104C, and 104K (see FIG. 1). Only one control unit 138 is shown. The laser printer 100 is provided with an environmental sensor 140 in the vicinity of each image forming unit 104 inside the laser printer 100, and the environmental sensor 140 detects the temperature and humidity in the vicinity of the image forming unit 104 at a constant cycle. A detection signal corresponding to the detection value is output to the control unit 138.

  As shown in FIGS. 2 and 5, the process cartridges 132 and 220 are each provided with a data memory unit 144 containing a storage element such as a ROM. The data memory unit 144 includes a connector 146 as an interface with the control unit 138. The connector 146 is linked to the mounting operation of the image forming unit 104 of the process cartridges 132 and 220 on the unit main body side. It is connected to a socket 148 provided at 138 and is detached from the socket 148 of the control unit 138 in conjunction with the removal operation from the unit main body side of the image forming unit 104 of the process cartridges 132 and 220.

  Here, the storage element of the memory unit 144 stores at least cleaning setting data corresponding to the type of the cleaning device disposed in the process cartridges 132 and 220, and the control unit 138 is connected via the socket 148 and the connector 146. Then, the cleaning setting data is read from the storage element of the memory unit 144 and the type of the cleaning device arranged in the process cartridges 132 and 220 is determined based on the cleaning setting data. The cleaning control condition for the photosensitive drum 12 is set according to the type of the cleaning device. As a result, the control unit 138 automatically sets different control conditions for cleaning when the brush cleaning device 10 is used as the cleaning device and different control conditions for cleaning when the blade cleaning device 210 is used. Can be changed.

  Specifically, in the laser printer 100 according to the present embodiment, when the brush cleaning device 10 is used as a cleaning device, this is not performed when the blade cleaning device 210 is used by the control unit 138, which will be described later. The temporal correction control and the environmental correction control are performed, and when the blade cleaning device 210 is used, the control unit 138 performs toner band control, which will be described later, which is not performed when the brush cleaning device 10 is used. .

  Next, the operation of the laser printer 100 according to the present embodiment when the brush cleaning device 10 is used as a cleaning device will be described in detail.

  In the laser printer 100, as described above, a toner image is formed on the image carrying surface 14 of the photosensitive drum 12 based on a known electrophotographic process while rotating the photosensitive drum 12, and this toner image is transferred to a transfer roll. The image is transferred to the intermediate transfer belt 102 by 28. The brush cleaning device 10 starts to operate in synchronization with the start of image formation by the laser printer 100, starts to drive the pre-cleaning corotron 80 and the static elimination lamp 78, and moves the cleaning brushes 16 and 18 and the detoning rolls 40 and 42. A specified voltage is applied to the cleaning brushes 16 and 18, the detoning rolls 40 and 42, and the scraper 66 by the high-voltage power supply unit 90 while rotating in predetermined directions. At this time, the high-voltage power supply unit 90 applies the voltage VB1 to the brush bristles 36 of the upstream cleaning brush 16 via the brush core 34, and the brush bristles 36 of the downstream cleaning brush 18 are applied to the brush bristles 36. The voltage VB2 is applied through the gold 34.

  In addition, the voltage VR1 is applied to the resistance layer 62 of the detoning roll 40 through the roll core metal 48, and the voltage VS1 is applied to the resistance layer 62 of the detoning roll 42 through the scraper 66. The voltage VR2 is applied through the core metal 48, and the voltage VS1 is applied through the scraper 66. Thereby, since the voltage of the same electric potential is applied to the resistance layer 62 of the detoning rolls 40 and 42 from the inner peripheral surface and the outer peripheral surface, respectively, the voltage is applied to the resistance layer 62 only through the roll core metal 48. As compared with the above, a high potential can be stably obtained as the surface potential.

  The brush cleaning device 10 first charges the residual toner remaining on the image bearing surface 14 to the negative polarity side after the transfer is completed by the corona discharge from the pre-cleaning corotron 80, and the distribution of the charging polarity of the residual toner as a whole. After shifting to the negative polarity side, the surface potential of the image bearing surface 14 on the photosensitive drum 12 is changed to the brush of the cleaning brush 16 by the high voltage power supply unit 90 by irradiating the image bearing surface 14 with the neutralizing light from the neutralizing lamp 78. It is an intermediate potential between the voltage VB2 applied to the core metal 34 and the voltage VB2 applied to the brush core metal 34 of the cleaning brush 18, and the image carrier surface 14 and the bristles 36 of the cleaning brushes 16, 18 The static elimination light F is irradiated to the photosensitive drum 12 so that the surface potential difference becomes equal to or less than the discharge start voltage DV.

  Specifically, the static elimination lamp 78 eliminates the electric charge so that the surface potential of the image bearing surface 14 becomes −100V to 0V. Here, the discharge start voltage DV is about 500V, and the surface potential of the brush bristles 36 of the cleaning brushes 16 and 18 is closer to 0V than the applied voltages VB1 and VB2. The surface potential difference with the 18 bristles 36 is surely a value sufficiently smaller than 500V. As a result, the occurrence of a discharge phenomenon from the brush bristles 36 of the cleaning brushes 16 and 18 to the image carrying surface 14 is prevented, and the surfaces of the brush bristles 36 of the cleaning brushes 16 and 18 become potentials corresponding to the applied voltages VB1 and VB2, respectively. It is reliably maintained. As a result, an electric field having a sufficient strength is always generated between the bristles 36 of the cleaning brushes 16 and 18 and the image carrying surface 14, and the residual toner adhering to the image carrying surface 14 is reliably adsorbed by the cleaning brushes 16 and 18. it can. Further, the occurrence of a discharge phenomenon from the brush bristles 36 of the cleaning brushes 16 and 18 to the image carrying surface 14 is prevented, and the surfaces of the brush bristles 36 of the cleaning brushes 16 and 18 are surely set to potentials corresponding to the applied voltages VB1 and VB2, respectively. Maintained.

  Next, the brush cleaning device 10 causes the bristle 36 of the cleaning brush 16 disposed on the upstream side to slidably contact the image carrying surface 14, so that the residual toner adhered to the image carrying surface 14 of the photosensitive drum 12. The residual toner charged mainly negatively is electrostatically adsorbed on the surface of the brush bristles 36 from the image bearing surface 14. The residual toner adsorbed on the brush bristles 36 of the cleaning brush 16 is transferred to the roll surface 44 of the detoning roll 40 by an electrostatic force and adsorbed on the roll surface 44. The residual toner is scraped off from the roll surface 44 to the toner reservoir 70 by the scraper 66 and discharged from the housing 30 by the auger 72.

  After removing the negative-polarity residual toner from the image carrying surface 14, the brush cleaning device 10 slides the brush bristles 36 of the cleaning brush 18 disposed on the downstream side of the cleaning brush 16 to the image carrying surface 14. Of the residual toner adhering to the image bearing surface 14 of the photosensitive drum 12, the residual toner mainly charged positively is electrostatically adsorbed onto the brush bristles 36 from the image bearing surface 14. The residual toner adsorbed on the brush bristles 36 of the cleaning brush 18 is transferred to the roll surface 44 of the detoning roll 42 by an electrostatic force and adsorbed on the roll surface 44. The residual toner is scraped off from the roll surface 44 to the toner reservoir 70 by the scraper 66 and discharged from the housing 30 by the auger 72. The residual toner, in which a small amount of charge contained in the residual toner is substantially neutralized, is mechanically scraped off from the image carrying surface 14 by the brush bristles 36 of the pair of cleaning brushes 16 and 18, respectively, and the action of gravity, etc. The toner drops into the toner reservoir 70.

  In the laser printer 100 according to the present embodiment, when the brush cleaning device 10 is used as a cleaning device, in addition to the normal cleaning operation as described above, the toner image on the photosensitive drum 12 in the image forming unit 104 is displayed. As the number of formations increases, cleaning voltage aging correction control for gradually increasing the potentials of the voltages VB1 and VB2 applied to the brush cores 34 of the cleaning brushes 16 and 18 by the high-voltage power supply unit 90 is executed. Specifically, the control unit 138 counts the number of times of toner image formation (number of times of image formation) on the image bearing surface 14 of the photosensitive drum 12 at the time of image formation, and the accumulated value of the number of image formation times is a drum cycle. Every time the rotation speed increases by 1000, the absolute value of the voltages VB1 and VB2 applied to the brush cores 34 of the cleaning brushes 16 and 18 by the high-voltage power supply unit 90 is increased by a value set within a range of 0.1V to 0.25V. At the same time, the absolute values of the voltages VR1 and VR2 and the voltages VS1 and VS2 applied to the roll core metal 48 and the scraper 66 of the detoning rolls 40 and 42 are increased by the same value as the voltages VB1 and VB2.

  In the laser printer 100 according to the present embodiment, as the control unit 138 increases the formation of the toner image on the photosensitive drum 12 in the image forming unit 104, the high pressure power supply unit 90 causes the brush core metal 34 of the cleaning brushes 16 and 18. Further, by gradually increasing the potentials of the voltages applied to the roll core metal 48 and the scraper 66 of the detoning rolls 40 and 42, the cleaning brushes 16 and 18 are deteriorated and worn as the number of cleanings increases. Even if the contact pressure and the contact area of the cleaning brush 16 to the image bearing surface 14 are reduced, it is possible to compensate for the deterioration of the cleaning ability caused by these, so that the cleaning ability of the brush cleaning device 10 is improved over time. It can prevent effectively that it falls.

  In the laser printer according to the present embodiment, when the brush cleaning device 10 is used as a cleaning device, the control unit 138 responds to the temperature and humidity detected by the environment sensor 140 in addition to the normal cleaning operation. The voltages VB1 and VB2 applied to the brush cores 34 of the cleaning brushes 16 and 18 are adjusted by the high-voltage power supply unit 90, and the voltages VR1 and VR2 applied to the roll cores 48 and the scraper 66 of the detoning rolls 40 and 42 are adjusted. An environmental correction operation of the cleaning voltage for adjusting the voltages VS1 and VS2 is executed.

  For example, when the temperature detected by the environmental sensor 140 is 26 ° C. or higher and the relative humidity is 55% or higher, the control unit 138 sets the imaging unit 104 under high temperature / high humidity environmental conditions. The voltage VB1 applied to the brush metal core 34 of the cleaning brushes 16 and 18 by the high-voltage power supply unit 90 with respect to a voltage applied under an environmental condition (normal temperature or normal humidity) other than this condition. VB2 is decreased, and the voltages VR1 and VR2 and the voltages VS1 and VS2 applied to the roll core metal 48 and the scraper 66 of the detoning rolls 40 and 42 are decreased. Specifically, the control unit 138 reduces the voltages VB1, VB2, VR1, VR2, VS1, and VS2 by 10 V to 50 V, respectively, under normal temperature or normal humidity conditions under high temperature / high humidity environmental conditions. Let

  Here, when the brush cleaning device 10 using the cleaning brushes 16 and 18 is used in a high-temperature and high-humidity environment, the brush bristles 36 of the cleaning brushes 16 and 18 formed using a resin material as a base material are used. A moisture absorption phenomenon that absorbs moisture in the air tends to occur, and the electrical resistance of the brush bristles 36 itself decreases due to such a moisture absorption phenomenon. Therefore, when the environmental correction operation of the cleaning voltage as described above is not executed, the intensity of the electric field generated between the brush bristles 36 of the cleaning brushes 16 and 18 and the image carrying surface 14 of the photosensitive drum 12 is sufficiently increased. As a result, the cleaning performance of the brush / cleaning device 10 is deteriorated, and cleaning failure is likely to occur.

  On the other hand, in the laser printer according to the present embodiment, the control unit 138 uses the high-voltage power supply unit 90 to remove the brush cores 34 and the detoning rolls according to the temperature and humidity detected by the environmental sensor 140. By adjusting the potential applied to each of the roll cores 48 and the scraper 66 of 40 and 42, the cleaning ability of the brush cleaning device 10 can be maintained substantially constant without being affected by environmental conditions.

  In the brush cleaning device 10 according to the present embodiment, the brush bristles 36 in the cleaning brushes 16 and 18 are respectively tilted in a predetermined direction toward the rotation direction (in the direction of the arrow RB in FIGS. 3 and 4) rearward (forward direction). It is inclined by an angle θB. Thereby, compared with the case where the bristles have a tilt angle toward the rotation direction (arrow RB direction) forward (reverse eye direction), the contact area between the bristles 36 and the image carrying surface 14 is sufficiently secured, The contact pressure of the brush bristles 36 on the image bearing surface 14 of the photosensitive drum 12 can be set low, and the occurrence of flicking (bounce-up) on the bristles 36 when the brush bristles 36 move away from the image carrying surface 14 can be suppressed.

  As a result, the external pressure in the toner can be reduced because the pressure applied when the toner held by the brush bristles 36 and held by the brush bristles 36 is pressed against the image carrying surface 14 can be reduced. Filming caused by pressing the agent against the image bearing surface 14 can be more effectively suppressed, and the occurrence of flickering of the brush bristles 36 is suppressed, so that the toner is adsorbed from the image bearing surface 14 and then cleaned. Since the amount of toner adhered to the brush bristles 36 of the brushes 16 and 18 and acting as an electrical resistance layer can be stabilized, the surface potential of the cleaning brushes 16 and 18 can also be stabilized.

  Next, the operation of the laser printer 100 according to the present embodiment when the blade cleaning device 210 is used as the cleaning device will be described in detail.

  In the laser printer 100, a toner image is formed on the image carrying surface 14 of the photosensitive drum 12 based on a known electrophotographic process while rotating the photosensitive drum 12, and this toner image is transferred to an intermediate transfer belt by a transfer roll 28. Transfer to 102. The blade cleaning device 210 starts operating in synchronization with the start of image formation by the laser printer 100, starts driving the pre-cleaning corotron 80, and rotates the disturb brush 214 in a predetermined direction.

  The blade cleaning device 210 first charges the residual toner remaining on the image bearing surface 14 to the negative polarity side after the transfer is completed by corona discharge from the pre-cleaning corotron 80, and the distribution of the charging polarity of the residual toner as a whole. Shift to the negative polarity side. At this time, the control unit 138 increases the voltage value applied to the discharge wire 82 of the pre-cleaning corotron 80 by about 2% as compared with the case where the brush cleaning device 10 is used, and shifts the residual toner to the negative polarity side. Slightly increase.

  Next, the blade cleaning device 210 mechanically agitates the residual toner adhering to the image carrying surface 14 of the photosensitive drum 12 by sliding the brush bristles 36 on the image carrying surface 14 of the disturb brush 214 to make a residual toner. Then, the toner remaining on the image carrying surface 14 is mechanically scraped off by the cleaning blade 212. At this time, since the cleaning blade 212 is in pressure contact with a relatively large pressing force, the cleaning blade 212 can reliably scrape off the residual toner adhering to the image bearing surface 14. In the blade cleaning device 210, the toner falls to the residual toner toner reservoir 70 scraped off from the image bearing surface 14 by the cleaning blade 212, and is discharged from the housing 30 by the auger 72.

  In the laser printer 100 according to the present embodiment, when the blade cleaning device 210 is used as a cleaning device, the control unit 138 controls the photosensitive drum 12 in each image forming unit 104 in addition to the normal cleaning operation as described above. The toner band control is executed to form a toner band image having a predetermined image density between the plurality of toner images formed on the image carrying surface 14 at a predetermined timing.

  That is, as a problem when the blade cleaning device 210 is used, when the amount of residual toner attached on the image bearing surface 14 of the photosensitive drum 12 becomes very small, the cleaning blade 212 and the image bearing surface 14 The frictional resistance of the cleaning blade 212 becomes excessive and the tip of the cleaning blade 212 is chipped and turned up easily. Here, chipping means that a part of the front end portion of the cleaning blade 212 is peeled off by the image carrying surface 14 and is lost. It is said that it is in a state of being fixed to the surface 14 and is temporarily bent in the moving direction following the image bearing surface 14, and plastic deformation occurs in this bent portion. The toner band control is performed to prevent the cleaning blade 212 from being chipped and turned up.

  The control unit 138 counts the number of times that the toner image has been formed (number of times of image formation) on the image bearing surface 14 of the photosensitive drum 12 and accumulates the number of pixels in the colored portion in the toner image formed over the past 100 times. When the value is 3% or less of the cumulative value of the total number of pixels included in the image formation area of the toner image on the image bearing surface 14, the area between the normal toner images formed on the photosensitive drum 12 (inter A toner band image having a predetermined image density is formed in the image area), and the toner band image passes through a transfer position by the transfer roll 28 so that the toner band image is not transferred from the photosensitive drum 12 to the intermediate transfer belt 102. In some cases, the control (toner band control) for interrupting the application of the transfer voltage to the transfer roll 28 is executed, and the toner formed over the past 100 times. Cumulative value of the number of pixels colored portion when more than 3% of the cumulative value of the total number of pixels included in the imaging region does not perform the toner band control in.

  When executing the toner band control, the control unit 138 charges the inter-image area corresponding to the inter-image on the image bearing surface 14 of the photosensitive drum 12 by the charger 20 and image information corresponding to the toner band image. Is output to the laser scanner 142, and the laser scanner 142 forms an electrostatic latent image corresponding to the toner band image in the inter image area of the image bearing surface 14. The control unit 138 starts the operation of the developing device 24 in synchronization with the movement of the electrostatic latent image formed in the inter-image area to the development position, and the electrostatic latent image on the image bearing surface 14 is transferred to the toner band by the developing device 24. Develop to image. The toner band image is transferred to the blade cleaning device 210 while being held on the image carrying surface 14 without being transferred to the intermediate transfer belt 102 by the transfer roll 28.

  Here, as the toner band image, an image having a maximum width of image sizes that can be formed by the laser printer 100 and having a size along the moving direction of the photosensitive drum 12 of about 40 mm is selected. The image density of the toner band image is set according to the environmental condition detected by the environmental sensor 140, either high image density (50% to 60%) or low image density (30% to 40%). Specifically, the control unit 138 selects a high image density as the image density of the toner band image when the temperature detected by the environmental sensor 140 is 26 ° C. or higher and the relative humidity is 55% or higher. When the temperature detected by the environmental sensor 140 is 26 ° C. or lower or the relative humidity is 55% or lower, a low image density is selected as the image density of the toner band image. By performing control according to such environmental conditions, it is possible to effectively prevent the cleaning blade 212 from being chipped and turned up, which is more likely to occur under high temperature and high humidity conditions.

  Next, the operation of the laser printer 100 of the present embodiment configured as described above will be described.

  In the laser printer 100 according to the first embodiment of the present invention, one of the brush cleaning device 10 and the blade cleaning device 210 can be selectively used as a cleaning device for residual toner adhering to the photosensitive drum 12. Therefore, the residual toner can be removed from the image bearing surface 14 of the photosensitive drum 12 by one arbitrarily selected from the brush cleaning device 10 and the blade cleaning device 210. A suitable one of the brush cleaning device 10 and the blade cleaning device 210 is selected in accordance with the image quality and image density of the image formed on the photosensitive drum 12, the life required for the photosensitive drum 12, and the like. One of the cleaning devices 10 and 210 removes the photosensitive drum 12. It can be training.

  Here, when the brush cleaning device 10 is used as the cleaning device, the brush cleaning device 10 images the tips of the brush bristles 36 of the pair of cleaning brushes 16 and 18 with a relatively small contact pressure during cleaning. Since the residual toner on the image carrying surface 14 is mainly adsorbed and removed by the brush bristles 36 by electrostatic attraction force while being brought into sliding contact with the carrying surface 14, it is compared with the case where the blade cleaning device 210 is used. Since the amount of wear over time on the image bearing surface 14 can be reduced, the life of the photosensitive drum 12 can be easily extended.

  When the blade cleaning device 210 is used as the cleaning device, the blade cleaning device 210 brings the tip of the cleaning blade 212 into pressure contact with the image carrying surface 14 with a relatively large contact pressure, and the cleaning blade 212 allows the image to be imaged. Since the residual toner on the carrying surface 14 is scraped off and removed, the toner adheres on the image carrying surface 14 without being significantly affected by the density (attachment amount) of the residual toner on the image carrying surface 14 after the transfer is completed. Since the residual toner can be removed with high removal capability, the amount of toner remaining on the image bearing surface 14 after the completion of cleaning can be made extremely small, and the image quality of the toner image formed on the image bearing surface 14 is lowered due to the influence of the residual toner. Can be effectively prevented.

  In the laser printer according to this embodiment, the cleaning for setting the cleaning operation for the photosensitive drum 12 by one of the brush cleaning device 10 and the blade cleaning device 210 arranged as the cleaning device in the process cartridges 132 and 220 is also set. A memory unit 144 that holds setting data is provided. When the process cartridges 132 and 220 are mounted on the unit body side of the image forming unit 104, the control unit 138 that controls each image forming unit 104 can access the memory unit 144. Accordingly, the control unit 138 reads the cleaning setting data from the storage element of the memory unit 144, and the cleaning device disposed in the process cartridges 132 and 220 based on the cleaning setting data. Since the type can be determined and the cleaning control condition for the photosensitive drum 12 can be set according to the type of the cleaning device, the control unit 138 uses the brush cleaning device 10 as the cleaning device. And the control conditions at the time of cleaning when the blade cleaning device 210 is used can be automatically changed to different ones.

  In the laser printer 100 according to this embodiment, the memory unit 144 includes an electronic storage element such as a ROM. However, instead of the memory unit 144, for example, the type of the cleaning device and When a plurality of concave and convex memory portions corresponding to the cleaning setting data are arranged in the process cartridges 132 and 220, and the process cartridges 132 and 220 are mounted on the main body side of the image forming unit 104, a plurality of memory portions in the memory portion are arranged. A detection switch that mechanically reads the concavo-convex pattern may be arranged, and the control unit 138 may determine the type of the cleaning device and the cleaning setting data based on a signal from the detection switch.

  In the laser printer 100 according to this embodiment, one of the brush cleaning device 10 and the blade cleaning device 210 is used as a cleaning unit for each of the plurality of image forming units 104C, 104M, 104Y, and 104K that form toner images of different colors. Is selectively usable, the image of the photosensitive drum 12 is selected by one of the image forming units 104C, 104M, 104Y, 104 selected from the brush cleaning device 10 and the blade cleaning device 210. Since the residual toner can be removed from the carrying surface 14, for example, brush cleaning is performed according to the average image density of the toner images formed by the image forming units 104C, 104M, 104Y, and 104 for each print color (toner color). Device 10 and blade cleaner A suitable device from the image forming device 210 is selected as a cleaning device for each of the image forming units 104C, 104M, 104Y, and 104, and the photosensitive drum 12 in the image forming units 104C, 104M, 104Y, and 104 is cleaned by the selected cleaning device. it can.

  Specifically, the image forming units 104C, 104M, 104Y, and 104 having a low average image density do not use the brush cleaning device 210 that easily damages the cleaning blade 212 when forming a low-image-density toner image. By using the cleaning device 10 as a cleaning device, it is possible to stably remove residual toner from the image bearing surface 14 of the photosensitive drum 12 over a long period of time while extending the life of the photosensitive drum 12.

  Further, in the image forming units 104C, 104M, 104Y, and 104 having a high average image density, the blade cleaning device 210 that can exhibit a high cleaning ability even when a toner image having a high image density is formed is used as a cleaning device. It is possible to effectively prevent the image quality of the toner image from being deteriorated due to the influence of the toner remaining on the image bearing surface 14 of the photosensitive drum 12.

  In the laser printer 100 according to the first embodiment of the present invention, the brush cleaning device 10 and the blade cleaning device 210 are respectively configured as part of the process cartridges 132 and 220, and the process cartridges 132 and 220 are the devices. The brush cleaning device 10 and the blade cleaning device 210 may be configured to be replaceable with respect to the unit main body side of the image forming unit 104 in this case. If the brush cleaning device 10 and the blade cleaning device 210 are each provided with a memory unit that holds cleaning setting data, the control unit 138 controls the cleaning when the brush cleaning device 10 is used as the cleaning device. conditions Automatically it becomes possible to change the control condition at the time of cleaning in the case of using a blade cleaning device 210 different from each other.

(Second Embodiment)
FIG. 6 shows the configuration of an image forming unit and a control unit in a laser printer according to the second embodiment of the present invention. Note that the configuration and image forming operation of the laser printer according to the second embodiment are basically the same as those of the laser printer 100 according to the first embodiment shown in FIG. For this reason, in the laser printer according to this embodiment, the same reference numerals are given to the same parts as those of the laser printer 100 according to the first embodiment, and the description thereof is omitted.

  As shown in FIG. 6, the laser printer is provided with a controller 230 for controlling the entire apparatus, and a control unit 232 for controlling the image forming unit 104 according to the control from the controller 230. Yes. A total of four control units 232 are provided corresponding to the Y, M, C, and K image forming units 104Y, 104M, 104C, and 104K (see FIG. 1). Only the control unit 232 is shown. In the image forming unit 104, a cleaning device 234 is disposed on the outer peripheral side of the photosensitive drum 12.

  Here, the cleaning device 234 includes both of a pair of cleaning brushes 16 and 18 and a cleaning blade 236 for removing residual toner from the photosensitive drum 12. (Double-Eelectro Static Brush) type cleaning device and blade type cleaning device are configured to function as both types.

  As shown in FIG. 7, the cleaning device 234 is provided with a plate-like cleaning blade 236 that protrudes from the opening 32 of the housing 30 toward the photosensitive drum 12, and the cleaning blade 236 is a photosensitive blade. It is arranged on the downstream side of the cleaning blade 236 along the rotation direction of the body drum 12. The cleaning device 234 includes a standby position (FIG. 7A) where the cleaning blade 236 is separated from the image carrying surface 14 of the photosensitive drum 12, and a cleaning position where the cleaning blade 236 is in pressure contact with the image carrying surface 14 (see FIG. 7B). A blade drive mechanism 238 for moving to either of them is provided.

  The blade drive mechanism 238 is provided with a support plate 240 that is connected to the base end of the cleaning blade 236 and supports the cleaning blade 236 in a cantilevered state, and the support plate 240 is driven in a driving direction that is substantially parallel to the height direction ( An elevating guide 242 that is slidably supported between the standby position and the cleaning position along the direction of arrow D) is provided. The lift guide 242 is integrally formed with a spring storage portion 244 having a substantially U-shaped cross section that opens upward at the lower end portion of the lift guide 242, and between the spring storage portion 244 and the support plate 240. Is provided with a coil spring 246, and this coil spring 246 always urges the support plate 240 to the upper side (standby position side).

  Further, the blade drive mechanism 238 is provided with a disc-shaped eccentric cam 248 and a motor unit 250 connected to the eccentric cam 248 so as to be in pressure contact with the upper surface portion of the support plate 240. Here, the motor unit 250 sets the eccentric cam 248 to the standby position according to the drive signal from the control unit 232 (see FIG. 7A) and the second phase corresponding to the cleaning position (FIG. 7B). ). At this time, when the eccentric cam 248 rotates from the first phase to the second phase, the support plate 240 moves from the standby position against the urging force of the coil spring 246 by the applied pressure from the outer peripheral surface (cam surface) of the eccentric cam 248. When the eccentric cam 248 is lowered to the cleaning position and the eccentric cam 248 rotates from the second phase to the first phase, the distance between the cam surface of the eccentric cam 248 and the support plate 240 is narrowed, and the support plate 240 is biased by the coil spring 246. As a result, the cleaning position is raised to the standby position.

  In the laser printer according to the present embodiment configured as described above, a part of each image forming unit 104 is configured as a replaceable process cartridge 252, and this process cartridge 252 (see FIG. 6) is at least photosensitive. The body drum 12 and the cleaning device 234 are included as components, and these components are integrated. That is, in the laser printer, it is necessary to replace at least the photosensitive drum 12 with a new one at regular intervals in order to maintain an image (toner image) formed by each image forming unit 104 with high image quality. In the laser printer according to the present invention, in order to easily replace a plurality of components in the image forming unit 104 having a certain lifetime in a short time, a plurality of components including at least the photosensitive drum 12 and the cleaning device 234 are integrated as a process cartridge 252. And these can be exchanged at the same time.

  In the laser printer according to this embodiment, the control unit 232 determines whether the cleaning device 234 functions as a brush cleaning device or a blade cleaning device, and executes control suitable for each cleaning device. .

  Specifically, the control unit 232 counts the number of times of toner image formation (number of times of image formation) on the image bearing surface 14 of the photoconductive drum 12 and the colored portion in the toner image formed over the past 100 times. When the cumulative value of the number of pixels is 3% or less of the cumulative value of the total number of pixels included in the image forming area of the toner image on the image bearing surface 14, the cleaning device 234 functions as a brush cleaning device. In the case where the cumulative value of the number of pixels of the colored portion in the toner image formed over the past 100 times exceeds 3% of the cumulative value of the total number of pixels included in the image forming area of the toner image. Then, control for causing the cleaning device 234 to function as a blade cleaning device is executed.

  In this embodiment, whether the cleaning device 234 functions as a brush cleaning device or a blade cleaning device (accumulated value of the number of pixels in the colored portion / cumulative value of the total number of pixels) = 3% However, the threshold value may be corrected according to the temperature and humidity detected by the environmental sensor 140. That is, since the cleaning blade 236 is likely to be chipped and turned up under high temperature and high humidity conditions, the threshold value increases as the temperature or humidity increases, and decreases as the temperature or humidity decreases. You may correct | amend so that.

  First, the control by the control unit 232 and the cleaning operation by the cleaning device 234 when the cleaning device 234 functions as a brush cleaning device will be described in detail. In this case, the control unit 232 applies predetermined voltages VB1 and VB2 to the brush metal cores 34 of the cleaning brushes 16 and 18 by the high-voltage power supply unit 90 while holding the cleaning blade 236 at the standby position by the blade drive mechanism 238, respectively. At the same time, voltages VR1 and VR2 and voltages VS1 and VS2 are applied to the roll core metal 48 and the scraper 66 of the detoning rolls 40 and 42, respectively. Here, the setting values of the voltages VB1 and VB2, the voltages VR1 and VR2, and the voltages VS1 and VS2 are the same as those in the first embodiment, and thus the description thereof is omitted. When the cleaning operation by the cleaning device 234 is started, the control unit 232 operates the cleaning device 234 as follows.

  That is, the cleaning device 234 first charges the residual toner remaining on the image bearing surface 14 to the negative polarity side after the transfer is completed by corona discharge from the pre-cleaning corotron 80, and the distribution of the charging polarity of the residual toner as a whole. After shifting to the negative polarity side, the surface potential of the image bearing surface 14 on the photosensitive drum 12 is changed to the brush of the cleaning brush 16 by the high voltage power supply unit 90 by irradiating the image bearing surface 14 with the neutralizing light from the neutralizing lamp 78. It is an intermediate potential between the voltage VB2 applied to the core metal 34 and the voltage VB2 applied to the brush core metal 34 of the cleaning brush 18, and the image carrier surface 14 and the bristles 36 of the cleaning brushes 16, 18 The static elimination light F is irradiated to the photosensitive drum 12 so that the surface potential difference becomes equal to or less than the discharge start voltage DV.

  Next, the brush cleaning device 10 causes the bristle 36 of the cleaning brush 16 disposed on the upstream side to slidably contact the image carrying surface 14, so that the residual toner adhered to the image carrying surface 14 of the photosensitive drum 12. The residual toner charged mainly negatively is electrostatically adsorbed on the surface of the brush bristles 36 from the image bearing surface 14. The residual toner adsorbed on the brush bristles 36 of the cleaning brush 16 is transferred to the roll surface 44 of the detoning roll 40 by an electrostatic force and adsorbed on the roll surface 44. The residual toner is scraped off from the roll surface 44 to the toner reservoir 70 by the scraper 66 and discharged from the housing 30 by the auger 72.

  After removing the negative-polarity residual toner from the image carrying surface 14, the brush cleaning device 10 slides the brush bristles 36 of the cleaning brush 18 disposed on the downstream side of the cleaning brush 16 to the image carrying surface 14. Of the residual toner adhering to the image bearing surface 14 of the photosensitive drum 12, the residual toner mainly charged positively is electrostatically adsorbed onto the brush bristles 36 from the image bearing surface 14. The residual toner adsorbed on the brush bristles 36 of the cleaning brush 18 is transferred to the roll surface 44 of the detoning roll 42 by an electrostatic force and adsorbed on the roll surface 44. The residual toner is scraped off from the roll surface 44 to the toner reservoir 70 by the scraper 66 and discharged from the housing 30 by the auger 72. The residual toner, in which a small amount of charge contained in the residual toner is substantially neutralized, is mechanically scraped off from the image carrying surface 14 by the brush bristles 36 of the pair of cleaning brushes 16 and 18, respectively, and the action of gravity, etc. The toner drops into the toner reservoir 70.

  When the cleaning device 234 functions as a brush / cleaning device, the control unit 232 operates in addition to the normal cleaning operation as described above, as in the case of the laser printer 100 according to the first embodiment. As the number of toner image formations on the photosensitive drum 12 in the image unit 104 increases, the potentials of the voltages VB1 and VB2 applied to the brush cores 34 of the cleaning brushes 16 and 18 by the high-voltage power supply unit 90 are gradually increased. The cleaning voltage aging correction control is executed, and the voltages VB1 and VB2 applied to the brush cores 34 of the cleaning brushes 16 and 18 are adjusted by the high voltage power supply unit 90 according to the temperature and humidity detected by the environmental sensor 140. In addition, the detoning rolls 40 and 42 Environmental correction operation of the cleaning voltage to adjust the voltage VR1, VR2 and voltage VS1, VS2 applied to Le metal core 48 and the scraper 66 is performed.

  Next, the control by the control unit 232 and the cleaning operation by the cleaning device 234 when the cleaning device 234 functions as a blade cleaning device will be described in detail. In this case, the control unit 232 moves the cleaning blade 236 from the standby position to the cleaning position by the blade drive mechanism 238, and then has a resistance element (not shown) having a resistance value of 1 MΩ to 100 MΩ built in the high voltage power supply unit 90. The brush metal core 34 of the cleaning brushes 16 and 18, the roll metal core 48 of the detoning rolls 40 and 42, and the scraper 66 are respectively grounded. When the cleaning operation by the cleaning device 234 is started, the control unit 232 operates the cleaning device 234 as follows.

  The cleaning device 234 starts operating in synchronization with the start of image formation by the laser printer 100, starts driving the pre-cleaning corotron 80, and rotates the cleaning brushes 16 and 18 in a predetermined direction. The blade cleaning device 210 first charges the residual toner remaining on the image bearing surface 14 to the negative polarity side after the transfer is completed by corona discharge from the pre-cleaning corotron 80, and the distribution of the charging polarity of the residual toner as a whole. Shift to the negative polarity side. At this time, the control unit 138 increases the voltage value applied to the discharge wire 82 of the pre-cleaning corotron 80 by about 2% as compared with the case where the brush cleaning device 10 is used, and shifts the residual toner to the negative polarity side. Is slightly increased, and the static elimination lamp 78 is kept off.

  Next, the cleaning device 234 mechanically agitates the residual toner adhering to the image carrying surface 14 of the photosensitive drum 12 by bringing the bristles 36 of the cleaning brushes 16 and 18 into sliding contact with the image carrying surface 14, thereby After the toner is easily peeled off from the image carrying surface 14, the residual toner adhering to the image carrying surface 14 is mechanically scraped off by the cleaning blade 236. At this time, the cleaning blade 236 has its tip end pressed with a relatively large pressing force, so that the residual toner adhering to the image bearing surface 14 can be surely scraped off evenly. In the cleaning device 234, the toner falls to the residual toner toner reservoir 70 scraped off from the image bearing surface 14 by the cleaning blade 236, and is discharged from the housing 30 by the auger 72.

  Next, the operation of the laser printer according to this embodiment configured as described above will be described.

  In the laser printer according to the first embodiment of the present invention, the cleaning device 234 includes a pair of cleaning brushes 16 and 18 for cleaning the image bearing surface 14 of the photosensitive drum 12 and presses against the image bearing surface 14. A cleaning blade 236 that is movable between the cleaning position and a standby position that is separated from the image bearing surface 14, and a blade drive that moves the cleaning blade 236 to either the cleaning position or the standby position in accordance with control from the control unit 232. By providing the mechanism 238, the cleaning device 234 can be moved to the W by holding the cleaning blade in the standby position by the blade driving mechanism 238 and applying a predetermined voltage to the cleaning brushes 16 and 18 and the detoning rolls 40 and 42. -ESB type The pair of cleaning brushes 16 and 18 can function as a brush / cleaning device to remove residual toner from the image bearing surface 14, and the blade driving mechanism 238 moves the cleaning blade 236 from the standby position to the cleaning position. , 18 and the detoning rolls 40 and 42 are grounded, so that the cleaning device 234 functions as a blade cleaning device without replacing the cleaning device 234, and residual toner is removed from the image bearing surface 14 by the cleaning blade 236. Can be removed.

  Here, when the cleaning device 234 functions as a brush cleaning device, the tips of the bristle 34 of the pair of cleaning brushes 16 and 18 are slidably contacted with the image bearing surface 14 with a relatively small contact pressure during cleaning. Since the residual toner on the image carrying surface 14 is mainly adsorbed and removed by the brush bristles 34 by electrostatic attraction force, the image bearing surface 14 is compared with the case where the blade cleaning device 210 is used. Since the amount of wear over time can be reduced, the life of the photosensitive drum 12 can be easily extended.

  When the cleaning device 234 functions as a blade cleaning device, the tip of the cleaning blade 236 is brought into pressure contact with the image carrying surface 14 with a relatively large contact pressure, and the residual on the image carrying surface 14 by the cleaning blade 236. Since the toner is scraped off and removed, the residual toner adhering to the image carrying surface 14 has a high removal ability without being greatly affected by the density (attachment amount) of the residual toner on the image carrying surface 14 after the transfer is completed. Therefore, the amount of toner remaining on the image bearing surface 14 after the cleaning is completed can be made extremely small, and the image quality of the toner image formed on the image bearing surface 14 is effectively lowered due to the influence of the residual toner. Can be prevented.

  As a result, according to the laser printer of this embodiment, the number of toner image formations (number of image formations) on the image bearing surface 14 of the photosensitive drum 12 is counted, and the toner images formed over the past 100 times are counted. When the cumulative value of the number of pixels in the colored portion is 3% or less of the cumulative value of the total number of pixels included in the image forming area of the toner image on the image bearing surface 14, the cleaning device 234 functions as a brush cleaning device. In addition, when the cumulative value of the number of pixels of the colored portion in the toner image formed over the past 100 times exceeds 3% of the cumulative value of the total number of pixels included in the image forming area of the toner image, the cleaning device By making the H.234 function as a blade cleaning device, a cleaning blade is used when forming a toner image with a low image density under image forming conditions with a low average image density. 36, the cleaning device 234 can function as a brush cleaning device, so that the life of the photosensitive drum 12 can be extended and stable from the image carrying surface 14 of the photosensitive drum 12 over a long period of time. In an image forming condition in which residual toner can be removed and an average image density is high, a cleaning blade 236 that can exhibit a high cleaning ability even when a high image density toner image is formed is used, and the cleaning device 234 is used as a blade cleaning device. Therefore, it is possible to effectively prevent the image quality of the toner image from being deteriorated due to the influence of the toner remaining on the image bearing surface 14 of the photosensitive drum 12 after cleaning.

(Modification of the second embodiment)
Next, a modified example of the control of the cleaning operation by the control unit in the laser printer according to the second embodiment of the present invention will be described.

  The control unit 232 holds the cleaning blade 236 at the standby position and causes the cleaning device 234 to function as a brush cleaning device. ) Is counted, and when the count value reaches a threshold value (N times) appropriately set within the range of 50 to 100 times, the count value is reset to 0 and the cleaning blade 236 is cleaned from the standby position. Move to position.

  Next, the control unit 232 moves the cleaning blade 236 to the cleaning position, and then the number of times (M times) that the toner image is set on the image bearing surface 14 of the photosensitive drum 12 within a range of 1 to 10 times. Until the toner image is formed, the cleaning device 234 functions as a blade cleaning device, and M times of toner image formation is completed on the image bearing surface 14 of the photosensitive drum 12, and the cleaning of the area where the toner image is transferred is completed. Later, the cleaning blade 236 is returned to the standby position, and the cleaning device 234 is made to function again as a brush cleaning device.

  In the laser printer according to the second embodiment of the present invention, when the cleaning device 234 is intermittently functioned as a blade cleaning device as described above, only the brush cleaning device is used for a long period of time. Since the generation of scratch marks on the image bearing surface 14 of the photosensitive drum 12 due to sliding contact with the cleaning blade 236 can be effectively prevented over a long period of time, the scratch marks on the image bearing surface 14 are caused. It is possible to effectively prevent deterioration of image quality in the resulting high density image (toner image) over a long period of time.

  That is, by causing the cleaning device 234 to intermittently function as a blade cleaning device, the image carrying surface 14 of the photosensitive drum 12 can be worn substantially uniformly by contact with the cleaning blade 236, so that the cleaning blade 236 If a wear amount corresponding to the surface roughness (Rz = 1 μm to 2 μm) of the scratch mark is intentionally generated on the image bearing surface 14, when the cleaning device 234 is used as a blade cleaning device, The generated scratch mark can be eliminated.

  In addition, since the cleaning blade 236 is used only intermittently, it is possible to prevent the cleaning blade 236 from being damaged or turned over for a long period of time, and the life of the cleaning device 234 itself can be made sufficiently long. .

  In the laser printer according to the second embodiment of the present invention, the cleaning device 234 is configured as a part of the process cartridge 252, and the process cartridge 252 can be replaced with the unit body side of the image forming unit 104. However, the cleaning device 234 may be replaced with the main body side of the image forming unit 104 as a single unit.

1 is a side view showing a schematic configuration of a laser printer according to a first embodiment of the present invention. FIG. 2 is a side cross-sectional view illustrating a part of the configuration of an image forming unit and a control unit when a brush cleaning device is applied to the laser printer shown in FIG. FIG. 3 is a side cross-sectional view showing a configuration of a cleaning brush and a detoning roll disposed on the upstream side in the brush cleaning device shown in FIG. 2. FIG. 3 is a side cross-sectional view illustrating a configuration of a cleaning brush and a detoning roll disposed on the downstream side in the brush cleaning device illustrated in FIG. 2. FIG. 2 is a side sectional view in which a part of the configuration of an image forming unit and a control unit in the case where a blade cleaning device is applied to the laser printer shown in FIG. 1 is a block diagram. It is side surface sectional drawing which made a part block diagram which shows the structure of the image formation unit and control part in the laser printer which concerns on the 2nd Embodiment of this invention. It is side surface sectional drawing which shows the structure of the cleaning apparatus shown by FIG.

Explanation of symbols

10 Brush cleaning device 12 Photosensitive drum (image carrier)
14 Image bearing surface 16, 18 Cleaning brush 24 Developer 40 Detoning roll 42 Detoning roll 90 High voltage power supply unit 100 Laser printer (image forming apparatus)
DESCRIPTION OF SYMBOLS 102 Intermediate transfer belt 104 Image forming unit 132 Process cartridge 136 Controller 138 Control unit 142 Laser scanner 144 Data memory unit 210 Blade cleaning device 212 Cleaning blade 220 Process cartridge 230 Controller 232 Control unit 234 Cleaning device 236 Cleaning blade 238 Blade drive mechanism 252 Process cartridge

Claims (2)

An image bearing member, a developing means for forming a toner image on the image bearing member, a transfer unit that transfers the recording medium or an intermediate transfer member the toner image carried by the developing unit from the image bearing member, said image bearing An image forming apparatus comprising: cleaning means for removing and collecting toner remaining on the surface of the image carrier after completion of transfer of the toner image from the body to the recording medium or the intermediate transfer body,
The cleaning means includes
A first cleaning brush that rotates while bringing the bristles into contact with the surface of the image carrier;
A second cleaning brush disposed downstream of the first cleaning brush along the moving direction of the image carrier and rotating while bringing the bristles into contact with the surface of the image carrier;
A cleaning power supply unit that applies voltages having different polarities to the brush metal core of the first cleaning brush and the brush metal core of the second cleaning brush;
A toner collecting member for collecting the toner adsorbed from the image carrier by the bristles of the first and second cleaning brushes from the bristles;
It is arranged downstream of the second cleaning brush along the moving direction of the image carrier, and is movable between a cleaning position that is pressed against the surface of the image carrier and a standby position that is separated from the image carrier. A cleaning blade,
A blade drive mechanism for moving the cleaning blade to either the cleaning position or the standby position in accordance with external control;
The image density of the toner image formed on the image carrier is determined by the developing means, and the cleaning blade is moved to one of the cleaning position and the standby position by the blade driving mechanism according to the determination value of the image density. Or cleaning selection means for holding;
An image forming apparatus comprising: An image carrier, a developing unit that forms a toner image on the image carrier, a transfer unit that transfers the toner image carried by the developing unit from the image carrier to a recording medium or an intermediate transfer member, and the image carrier. An image forming apparatus comprising: cleaning means for removing and collecting toner remaining on the surface of the image carrier after completion of transfer of the toner image from the body to the recording medium or the intermediate transfer body,
The cleaning means includes
A first cleaning brush that rotates while bringing the bristles into contact with the surface of the image carrier;
A second cleaning brush disposed downstream of the first cleaning brush along the moving direction of the image carrier and rotating while bringing the bristles into contact with the surface of the image carrier;
A cleaning power supply unit that applies voltages having different polarities to the brush metal core of the first cleaning brush and the brush metal core of the second cleaning brush;
A toner collecting member for collecting the toner adsorbed from the image carrier by the bristles of the first and second cleaning brushes from the bristles;
It is arranged downstream of the second cleaning brush along the moving direction of the image carrier, and is movable between a cleaning position that is pressed against the surface of the image carrier and a standby position that is separated from the image carrier. A cleaning blade,
A blade drive mechanism for moving the cleaning blade to either the cleaning position or the standby position in accordance with external control;
The number of toner image formations on the image carrier by the developing unit is counted, and when the count value reaches a predetermined threshold value, the count value is reset and the cleaning blade is put on standby by the blade driving mechanism. When the toner image formed on the image carrier by the developing means is formed a predetermined number of times while the cleaning blade is held at the cleaning position and moved from the position to the cleaning position, the cleaning is performed. Cleaning selection means for returning the blade from the cleaning position to the standby position;
An image forming apparatus comprising:

Images