JP4543711B2 - 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. The present invention relates to a cleaning device for forming a toner image on an image carrier based on an electrophotographic process and transferring the toner image to a recording medium or an intermediate transfer member.

  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 photosensitive member, 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 transfer residuals on the photosensitive member are 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.
Japanese Patent Publication No. 1-38314

  In the so-called W-ESB (Double-Eelectro Static Brush) type cleaning device as described above, a pair of cleaning brushes to which voltages of different polarities are applied are brought into sliding contact with the image bearing surface of the photosensitive member to thereby carry the image bearing. Residual toner remaining on the surface is removed or adsorbed electrostatically and mechanically. Here, the cleaning brush is usually configured by planting a large number of brush hairs at a constant density on the outer peripheral side of a brush metal core formed of a conductive metal material such as SUS. For example, a material whose electrical resistance is adjusted to a predetermined value by adding carbon black to a resin material such as nylon is molded.

  However, since the brush bristles of the cleaning brush are set on the assumption that the toner whose electric resistance has been removed from the photoreceptor adheres to the bristles (hereinafter referred to as “steady cleaning state”), cleaning is performed. At the start of use of the apparatus, since the electrical resistance between the brush bristles of the cleaning brush and the image bearing surface of the photoreceptor is suppressed as compared with the steady cleaning state, the surface potential of the brush bristles is lowered. As a result, at the start of use of the cleaning device, the strength of the electric field generated between the brush bristles of the cleaning brush and the image bearing surface of the photoreceptor cannot be secured sufficiently, and the cleaning performance of the cleaning device is lower than in the steady cleaning state. As a result, there arises a problem that cleaning defects are likely to occur.

  Another object of the present invention is to provide an image forming apparatus capable of effectively preventing a reduction in the cleaning ability of an image carrier by a pair of cleaning brushes at the start of use of the cleaning means in consideration of the above facts. There is to do.

An image forming apparatus according to claim 1 of the present invention, a image forming means for forming a toner image based on the image bearing member in an electrophotographic process, the recording medium the toner image carried by the developing means from the image carrier or A transfer means for transferring to the intermediate transfer member; and a cleaning means for removing and collecting the toner remaining on the surface of the image carrier after completion of the transfer of the toner image from the image carrier to the recording medium or intermediate transfer member. In the image forming apparatus, the bristle that extends radially outward from the outer peripheral side of the cylindrical brush metal core and is inclined backward in the rotational direction with respect to the radial direction is applied to the cleaning unit. A first cleaning brush that rotates while being in contact with the surface of the carrier, and an electrical resistance layer is provided on the outer peripheral side of the cylindrical brush core, and a roll surface comprising the outer peripheral surface of the resistance layer is disposed on the brush. Touching hair A first toner collecting roll that rotates while rotating, and is disposed on the downstream side of the first cleaning brush along the moving direction of the image carrier, and radially outward from the outer peripheral side of the cylindrical brush metal core. A second cleaning brush that extends and rotates while contacting the surface of the image carrier with brush hairs inclined backward in the rotational direction with respect to the radial direction, and on the outer peripheral side of the cylindrical brush core A second toner collecting roll which is provided with an electrical resistance layer and rotates while bringing a roll surface formed of an outer peripheral surface of the resistance layer into contact with the brush bristles; and a brush core of the first and second cleaning brushes And a cleaning power supply unit for applying a voltage of a predetermined potential to the roll cores of the first and second toner collecting rolls, and before transferring the cleaning unit, While stopping the movement, the image forming means forms a toner image on the image carrier, and the cleaning power supply unit applies a voltage having a polarity opposite to the charging polarity of the toner on which the toner image has been formed. A pre-cleaning operation in which the toner is transferred to the brush cores of the cleaning brush alternately, the toner is transferred from the image carrier to the brush bristles of the first and second cleaning brushes, and the toner is adsorbed and held by the brush bristles. It is characterized by comprising control means for executing .

In the image forming apparatus according to the first aspect, the control unit forms a toner image on the image carrier by the image forming unit while stopping the operation of the transfer unit before starting the use of the cleaning unit, and forms the toner image. A voltage having a polarity opposite to the charged polarity of the toner is applied to the brush cores of the first and second cleaning brushes by the cleaning power supply unit, and the toner is applied from the image carrier to the brush bristles of the first and second cleaning brushes. And the pre-cleaning operation for adsorbing and holding the toner to the brush bristles is performed, so that the brush bristles of the first and second cleaning brushes are more electrically than the bristles before the use of the cleaning means is started. Each of the toners having high resistance is attached, and this toner can form an electric resistance layer on the surface of the brush hair. Compared to the case where the resistance layer is not formed on the brush hairs of the first and second cleaning brushes at the start of use of the first and second cleaning brushes, the electricity between the brush hairs of the first and second cleaning brushes and the image carrier The resistance can be increased, and the brush power and the image carrier of the first and second cleaning brushes can be obtained by applying a predetermined voltage to the brush cores of the first and second cleaning brushes by the cleaning power supply unit. Can sufficiently secure the strength of the electric field generated between the two. As a result, according to the image forming apparatus of the first aspect, the toner (residual toner) removed and collected from the image carrier is attached to the brush hairs of the first and second cleaning brushes at the start of use of the cleaning unit. Even without this, the strength of the electric field generated between the bristles of the cleaning brush and the image carrier can be sufficiently secured, so that it is possible to effectively prevent the cleaning performance of the cleaning means from being deteriorated.

An image forming apparatus according to a second aspect of the present invention is the image forming apparatus according to the first aspect, wherein the bristles of the first and second cleaning brushes are more electrically connected to the bristles before the start of use of the apparatus. It is characterized in that fine particles of a resistor having a high resistance are adhered, and an electric resistance layer is formed on the surface of the bristles with the fine particles of the resistor. In the cleaning device according to claim 2, before the start of use of the device, the fine particles of the resistor having higher electrical resistance than the brush hair are respectively attached to the brush hairs of the first and second cleaning brushes. By forming an electrical resistance layer on the surface of the bristle with the fine particles of the body, compared to the case where the resistance layer is not formed on the bristle of the first and second cleaning brushes at the start of use of the device, Since the electrical resistance between the bristles of the second cleaning brush and the image carrier can be increased, when a voltage of a predetermined potential is applied to the brush cores of the first and second cleaning brushes, the brush Even if the toner transferred from the image carrier does not adhere to the hair, or even if the toner amount adheres to the brush hair and the toner amount is insufficient, the first and second cleaning brushes The intensity of an electric field generated between the sheet hair and the image bearing member can be sufficiently secured. As a result, according to the cleaning device of the first aspect, even during a period from the start of use of the device until a substantially constant amount of toner stably adheres to the bristles of the first and second cleaning brushes, Since the strength of the electric field generated between the brush bristles of the cleaning brush and the image carrier can be sufficiently secured, it is possible to effectively prevent the cleaning performance from being deteriorated.

The image forming apparatus according to claim 3 of the present invention is an image forming apparatus according to claim 1 or 2, wherein, as fine particles of the resistor forming the charge retention layer, forming a toner image on said image bearing member At least one of a toner and an external additive contained in the toner is used.

An image forming apparatus according to a fourth aspect is the image forming apparatus according to the first, second, or third aspect , wherein the image forming apparatus is disposed upstream of the first cleaning brush along the moving direction of the image carrier. The neutralization means for neutralizing the surface of the surface, wherein the neutralization means has a surface potential of the image bearing surface, the voltage applied by the first voltage application means to the brush core of the first cleaning brush, and the second The voltage applying means is an intermediate potential between the voltage applied to the brush core of the second cleaning brush, and the surface potential difference between the image carrying surface and the brush hairs of the first and second cleaning brushes is It is characterized by being below the discharge start voltage.

An image forming apparatus according to a fifth aspect is the image forming apparatus according to the fourth aspect , wherein the image forming apparatus is disposed adjacent to the upstream side of the charge eliminating unit along the moving direction of the image carrier and is disposed on the surface of the image carrying surface. Toner charging means for controlling the polarity and charging potential of the adhered toner, and the charge removing light emitted from the charge removing lamp used as the charge removing means is shielded, and the charge removing light is applied by the toner charging means on the surface of the image carrier. And a light shielding member for preventing entry into the toner charging region.

The image forming apparatus according to claim 6, in the image forming apparatus according to claim 5, the light shielding member shields the discharge from the discharge wire in the wire-discharge type charging device is used as the toner charging unit It is characterized in that it is provided integrally with a shield case.

The image forming apparatus according to claim 7 is the image forming apparatus according to any one of claims 1 to 6 , wherein the control unit further includes a toner image formed on the image carrier. When the toner image remains on the image carrier after passing through the transfer position by the transfer unit, the toner image is applied to the brush metal core of the first cleaning brush by the cleaning power supply unit as compared with the case where the toner image does not remain. The voltage is increased to increase the surface potential difference generated between the brush hair and the image carrying surface.

The image forming apparatus according to claim 8 is the image forming apparatus according to any one of claims 1 to 7 , wherein the control unit further includes a toner applied to the image carrier by the image forming unit. As the image formation increases, the potential of the voltage applied by the cleaning power supply unit to the brush cores of the first and second cleaning brushes and the roll cores of the first and second detoning rolls is gradually increased. It is characterized in that the pressure is increased.

An image forming apparatus according to claim 9 is the image forming apparatus according to any one of claims 1 to 8 , wherein the environmental sensor detects environmental conditions including temperature and humidity in an installation environment of the cleaning device. And the control means further includes brush metal cores of the first and second cleaning brushes and the first and second brushes by the cleaning power supply unit in accordance with environmental conditions detected by the environmental sensor. It is characterized in that the potential of the voltage applied to the roll core of the toner recovery roll is adjusted.

  Further, according to the image forming apparatus of the present invention, it is possible to effectively prevent the cleaning ability of the image carrier by the pair of cleaning brushes from being lowered at the start of use of the cleaning unit.

  Hereinafter, a laser printer according to an embodiment of the present invention and a cleaning device applied to the laser printer 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 or 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 FIG. 2, the image forming unit 104 is provided with a photosensitive drum 12 as a toner image carrier, and a cleaning device 10 is disposed on the outer peripheral side of the photosensitive drum 12. The outer peripheral surface of the photosensitive drum 12 is an image carrying surface 14 on which an image is formed based on an electrophotographic process, and the cleaning device 10 includes a so-called W- that includes two cleaning brushes 16 and 18. It is configured as an ESB (Double-Eelectro Static Brush) type cleaning device. An erase lamp 29, a charger 20, a surface potential meter 22, a developing device 24 (see FIG. 1) are provided on the outer peripheral side of the photosensitive drum 12 along the rotation direction (arrow RD direction) on the downstream side of the cleaning device 10. A carrier catch roll 26 and a primary transfer roll 28 are arranged in order. Here, the erase lamp 29 irradiates the image carrying surface 14 of the photosensitive drum 12 that has been cleaned by the cleaning device 10 to remove static electricity from the image carrying surface 14, and the charger 20 It is charged to a predetermined image forming start potential (for example, 400V to 800V).

  In the laser printer 100, laser scanners (not shown) are arranged above the image forming units 104Y, 104M, 104C, and 104K, respectively. These laser scanners have a Y component, an M component, a C component, or a K component. Photosensitive drums in the respective image forming units 104Y, 104M, 104C, and 104K charged to an image forming start potential by laser beams LY, LM, LC, and LK (see FIG. 1) modulated based on image information corresponding to the components. The twelve image bearing surfaces 14 are scanned to form an electrostatic latent image on the image bearing surface 14.

  In the image forming unit 104, the developing device 24 is charged with normal polarity (in this embodiment, negative (-) polarity), and the toner is thinned and attached to the roll surface of the developing roll 24. 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 transferred to 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, 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 completed is removed and collected by the cleaning device 10. 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.

  The cleaning device 10 of the image forming unit 104 is provided with a housing 30 that is supported so as to face the photosensitive drum 12. The housing 30 faces the image carrying surface 14 of the photosensitive drum 12. An opening 32 that opens 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 image forming apparatus can be transmitted to the shaft portions 38 of the pair of brush cores 34. This motor transmits torque to the brush mandrel 34 when the cleaning device 10 is operated, and rotates 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 °, preferably 30 °, but is particularly limited as long as it is within the above range. is not. 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 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 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 cleaning device 10 is provided with a pair of scrapers 66 in the housing 30, and these scrapers 66 are constituted by leaf springs having flexibility and conductivity. The proximal end side is connected and fixed to the housing 30, and the distal end portion is brought into pressure contact with the roll surface 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, in the cleaning device 10, a static elimination lamp 78 is disposed on the upstream side of the housing 30, and a pre-cleaning corotron 80 that is a discharge type charger is located on the upstream side of the static elimination lamp 78. Is arranged. 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, when the cleaning device 10 is operated, the pre-cleaning corotron 80 charges the toner (hereinafter referred to as “residual toner”) remaining on the image bearing surface 14 after the transfer is completed to the negative polarity side, The distribution of the charging polarity 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. At this time, if the charge removal light F is applied to the charged area on the image bearing surface 14 by the pre-cleaning corotron 80, the residual toner adhering to the charge area is discharged by the charge removal light F and at the same time the pre-cleaning. Since the toner is charged so as to be shifted to the negative polarity by corona discharge from the corotron 80, a phenomenon occurs in which the shift amount of the residual toner to the negative polarity side is excessive, and electrostatic adsorption from the image carrying surface 14 occurs. The force becomes excessive on a part of the residual toner, and it becomes difficult to reliably remove such residual toner from the image bearing surface 14 by the cleaning device 10.

  In the cleaning apparatus 10 according to the present embodiment, a shielding portion 86 is integrally formed on the casing 84 of the pre-cleaning corotron 80, and the neutralizing light F from the neutralizing lamp 78 is caused to be charged by the shielding portion 86. Therefore, the phenomenon that the amount of shift of the residual toner toward the negative polarity side is excessively prevented is reliably prevented. The shielding portion for shielding the static elimination light F is not necessarily formed integrally with the casing 84, and is disposed between the static elimination lamp 78 and the pre-cleaning corotron 80 as an independent component. Also good.

  As shown in FIG. 2, the cleaning device 10 is provided with a power supply box 88 above the housing 30. A high-voltage power supply unit 90 is disposed in the power supply box 88. The high-voltage power supply unit 90 is a voltage supplied with a high-voltage power supply by a high-voltage power supply unit (not shown) provided on the apparatus main body side of the image forming apparatus. An adjustment circuit is provided, and this voltage adjustment circuit applies a voltage having a predetermined voltage value to 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. .

  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.

  In the laser printer 100 configured as described above, at least the photosensitive drum 12 and the cleaning device 10 are integrated as a process cartridge 132, and the process cartridge 132 (see FIG. 2) is configured as a replaceable part. Has been. That is, at least the photosensitive drum 12 and the cleaning device 10 need to be replaced with new ones at regular intervals in order to maintain an image formed by the laser printer 100 with high image quality. In order to easily replace a plurality of parts in the image forming unit 104 having a long life, in a short time, a plurality of parts including at least the photosensitive drum 12 and the cleaning device 10 are integrated as a process cartridge 132 so that they can be replaced at the same time. Yes.

  The cleaning device 10 according to the present embodiment is attached to the cleaning brushes 16 and 18 before being assembled as the process cartridge 132 in the production line or before the cleaning brushes 16 and 18 are assembled to the housing 30 of the cleaning device 10. In this method, a precleaning agent comprising fine particles of a resistor having a higher electrical resistance than the brush bristles 36 is supplied. As a result, the pre-cleaning agent is uniformly attached to the surfaces of the brush bristles 36 of the cleaning brushes 16 and 18, respectively, and an electrical resistance layer is temporarily formed on the surfaces of the brush bristles of the cleaning brushes 16 and 18 by this pre-cleaning agent. Form.

  Here, as the precleaning agent, for example, a toner contained in the developer of the laser printer 100, an external additive externally added to the toner, and a mixture obtained by appropriately mixing these can be used. Such a toner can be obtained, for example, by kneading 6 wt% cyanine blue (Daiichi Seika) in 94 wt% polyester and pulverizing it to a required particle size. As the external additive, for example, an inorganic fine powder such as silica, alumina, titanium oxide and the like, and a silane coupling agent such as dialkyldihalonogenated silane and a hydrophobizing agent such as dimethyl silicone oil are reacted at a high temperature. It is necessary to use a toner having a particle size that is at least smaller than the particle size of the toner. As the precleaning agent, a toner and an external additive as described above are used as raw materials and the particle size distribution thereof is adjusted to be in the range of 100 nm to 5 μm.

  In the production line of the cleaning device 10, the pre-cleaning agent manufactured as described above is filled in a cloth pouch, the pouch is struck against the cleaning brush 16, and cleaning is performed with the pre-cleaning agent leaking from the stitches of the pouch. The entire brush 16 is dusted, and the precleaning agent is attached to the brush bristles 36 of the cleaning brushes 16 and 18. According to such a method, the pre-cleaning agent can be adhered substantially uniformly from the front end portion to the base end portion of the brush bristles 36 of the entire cleaning brush 16, 18.

  Next, the operation of the cleaning device 10 according to the present embodiment configured as described above will be described in detail.

  In the laser printer 100, as described above, while rotating the photosensitive drum 12, a toner image is formed on the image carrying surface 14 of the photosensitive drum 12 based on a known electrophotographic process, and this toner image is transferred to a transfer roll. The image is transferred to a recording medium by 28. The cleaning device 10 starts to operate in synchronization with the start of image formation by the laser printer 100, starts driving the pre-cleaning corotron 80 and the static elimination lamp 78, and sets the cleaning brushes 16 and 18 and the detoning rolls 40 and 42 respectively to the predetermined values. The high voltage power supply unit 90 applies specified voltages to the cleaning brushes 16 and 18, the detoning rolls 40 and 42, and the scraper 66, respectively. 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 have a brush core. 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. In comparison, a high potential can be stably obtained as the surface potential.

  First, the cleaning device 10 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 is negative. Then, the surface potential of the image bearing surface 14 of the photosensitive drum 12 is changed to the brush core metal 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. 34 is an intermediate potential between the voltage VB2 applied to 34 and the voltage VB2 applied to the brush metal core 34 of the cleaning brush 18, and the surface potential difference between the image bearing surface 14 and the bristles 36 of the cleaning brushes 16 and 18. Irradiates the photosensitive drum 12 with the static elimination light F so that the voltage becomes equal to or lower 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 cleaning device 10 mainly contacts the residual toner adhering to the image carrying surface 14 of the photosensitive drum 12 by bringing the brush bristles 36 of the cleaning brush 16 disposed on the upstream side into sliding contact with the image carrying surface 14. The negatively charged residual toner is electrostatically adsorbed from the image bearing surface 14 to the surface of the brush bristles 36. 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 cleaning device 10 sensitizes the brush bristles 36 of the cleaning brush 18 disposed on the downstream side of the cleaning brush 16 to slide in contact with the image carrying surface 14. Of the residual toner adhering to the image bearing surface 14 of the body 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.

  Next, the operation of the cleaning device 10 of the present embodiment configured as described above will be described.

  In the cleaning device 10 of the present embodiment, before being attached to the laser printer 100 as a part of the process cartridge 132, the pre-cleaning agent having higher electrical resistance than the brush bristles 36 is applied to the brush bristles 36 of the cleaning brushes 16 and 18. And an electrical resistance layer is temporarily formed on the surface of the brush bristles 36 by this pre-cleaning agent, so that the resistance layer is applied to the brush bristles 36 of the cleaning brushes 16 and 18 at the start of use of the cleaning device 10. Compared with the case where no brush is formed, the electrical resistance between the brush bristles 36 of the cleaning brushes 16 and 18 and the image carrying surface 14 of the photosensitive drum 12 can be increased. 34, when voltages VB1 and VB2 having predetermined potentials are respectively applied to Even if the toner transferred from the photosensitive drum 12 does not adhere to the brush hair 36, or even if the toner amount adheres to the brush hair 36 and the toner amount is insufficient, the brush hair 36 of the cleaning brushes 16 and 18 and the photosensitive member. The intensity of the electric field generated between the drum 12 and the image bearing surface 14 can be sufficiently secured.

  As a result, according to the cleaning device 10 according to the present embodiment, the cleaning brush 16 is also used during a period from the start of use until a substantially constant amount of toner stably adheres to the bristles 36 of the cleaning brushes 16 and 18. , 18 brush bristles 36 and the image carrying surface 14 can be sufficiently secured to effectively prevent the deterioration of the cleaning performance. In the cleaning device 10 according to the present embodiment, since the toner and the external additive are used as the precleaning agent, the precleaning agent does not adversely affect the image forming process in the laser printer 100.

  In the cleaning device 10 according to the present embodiment, the brush bristles 36 of the cleaning brushes 16 and 18 are respectively rotated in the direction of rotation (in the direction of the arrow RB in FIGS. 3 and 4) in the rear direction (forward direction). Just tilted. 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.

  In the laser printer 100 according to the first embodiment of the present invention, the cleaning apparatus 10 is configured as a part of the process cartridge 132, and the process cartridge 132 can be replaced with the apparatus main body. Even when the apparatus 10 is replaceable with respect to the apparatus main body, the pre-cleaning agent is supplied to the cleaning brushes 16 and 18 of the cleaning apparatus 10 before being attached to the laser printer 100, so that the cleaning apparatus Needless to say, the same effects can be obtained as when 10 is configured as part of the process cartridge 143.

(Second Embodiment)
FIG. 5 shows a 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 the present embodiment, the same reference numerals are assigned to the parts common to the laser printer 100 according to the first embodiment, and the description thereof is omitted.

  As shown in FIG. 5, the laser printer 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. Yes. 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 the control unit 138 is shown. The laser printer is provided with an environmental sensor 140 in the vicinity of each image forming unit 104 inside the laser printer. The environmental sensor 140 detects the temperature and humidity in the vicinity of the image forming unit 104 at a constant cycle, and detects the detection. A detection signal corresponding to the value is output to the control unit 138.

  In the laser printer configured as described above, at least the photosensitive drum 12 and the cleaning device 10 are integrated as a process cartridge 143, and the process cartridge 143 is configured as a replaceable part for the apparatus main body. ing. That is, at least the photosensitive drum 12 and the cleaning device 10 need to be replaced with new ones at regular intervals in order to maintain an image formed by the laser printer with high image quality. In order to easily replace a plurality of components in the image forming unit 104 having a plurality of components in a short time, a plurality of components including at least the photosensitive drum 12 and the cleaning device 10 are integrated as a process cartridge 143 so that they can be replaced at the same time.

  Here, the process cartridge 143 according to the present embodiment is different from the process cartridge 132 according to the first embodiment in that the pre-cleaning agent is not supplied to the cleaning brushes 16 and 18 in the cleaning device 10 in the production line. The only reason is that the electrical resistance layer is not formed by the pre-cleaning agent on the brush bristles 36 of the cleaning brushes 16 and 18, and the process cartridge 132 and the process cartridge 143 are configured in common for the other points. Yes.

  However, in the laser printer according to the present embodiment, an unused process cartridge is used instead of forming a resistance layer with the pre-cleaning agent on the cleaning brushes 16 and 18 before starting the use of the process cartridge 143 as in the first embodiment. When the printer 143 is installed in the laser printer, the control unit 138 supplies toner to the cleaning brushes 16 and 18 of the cleaning device 10 before the image forming operation on the recording paper P actually starts. A pre-cleaning operation is performed.

  Next, a pre-cleaning operation executed by the image forming unit 104 of the laser printer according to this embodiment will be described.

  When the process cartridge 143 in the image forming unit 104 of the laser printer is replaced with a new one, the controller 136 issues a pre-cleaning start command to the control unit 138 before starting the actual image forming operation on the recording paper P. In addition to outputting, the movement of the intermediate transfer belt 102 is started, and the movement of the intermediate transfer belt 102 is continued until the pre-cleaning operation is completed.

  Upon receiving the pre-cleaning start command, the control unit 138 starts rotating the photosensitive drum 12 while stopping the application of the transfer voltage to the transfer roll 28 and starts charging the image bearing surface 14 by the charger 20. Next, the control unit 138 outputs image information corresponding to the test pattern image to the laser scanner 142, and causes the laser scanner 142 to form an electrostatic latent image corresponding to the test pattern image on the image bearing surface 14 of the photosensitive drum 12. . The control unit 138 starts the operation of the developing device 24 in synchronization with the movement of the electrostatic latent image to the developing position, and the developing device 24 develops the electrostatic latent image on the image carrying surface 14 into a toner image. The toner image moves to the cleaning device 10 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 test pattern image, an image having the maximum width among the image sizes that can be formed by the laser printer and having a relatively high image density is selected. Specifically, the test pattern image (toner image), those that developed mass is set in the range of ^{0.05mg / cm 2 ~0.2mg / cm 2} , the image density is set to about 30% preferable. The control unit 138 controls the image forming unit 104 so that the test pattern image as described above is continuously formed on the image bearing surface 14 of the photosensitive drum 12 for 1.5 min to 3 min.

The control unit 138 starts the operation of the cleaning device 10 in synchronization with the start of scanning of the image bearing surface 14 by the laser scanner 142, starts driving the pre-cleaning corotron 80 and the charge-removing lamp 78, and the cleaning brushes 16, 18 and While rotating the detoning rolls 40 and 42 in predetermined directions, the high pressure power supply unit 90 causes the brush core metal 34 of the cleaning brush 16 to rotate.
The specified voltages VB1, VR1, and VS1 are applied to the roll core metal 48 and the scraper 66 of the detoning roll 40, respectively, and the brush core metal 34 of the cleaning brush 18, the roll core metal 48 of the detoning roll 42, and the scraper 66 are applied. Specified voltages VB2, VR2, and VS2 are applied.

  In the timing chart of FIG. 6A, the ON and OFF timings of the applied voltages VB1, VR1, and VS1 and the applied voltages VB2, VR2, and VS2 are shown. When the formation of the test pattern image on the image bearing surface 14 is started, the control unit 138 performs a cycle in which the voltages VB1, VR1, VS1 and the voltages VB2, VR2, VS2 are alternately turned on and off at a period of time T. Repeat until after formation. Here, T is appropriately set within a range of 1 second to 3 seconds, and voltages VB1, VR1, VS1 and voltages VB2, VR2, VS2 are set to + 260V, respectively. As a result, when the voltages VB1, VR1, and VS1 are on, the negative polarity toner that has formed the toner image on the image bearing surface 14 is transferred to the brush bristles 36 of the cleaning brush 16, and this toner is transferred to the brush bristles 36. When the voltages VB2, VR2, and VS2 are on, the toner that has formed a toner image on the image bearing surface 14 is transferred to the brush bristles 36 of the cleaning brush 18 when the voltages VB2, VR2, and VS2 are on. It is adsorbed and held on the surface. At this time, voltages VR1 and VR2 having the same potential as the cleaning brushes 16 and 18 are applied to the detoning rolls 40 and 42, respectively. As a result, the toner adsorbed on the brush bristles 36 of the cleaning brushes 16 and 18 is not transferred to the detoning rolls 40 and 42 unlike the normal cleaning, and most of the toner remains attached to the brush bristles 36. .

  When the trailing edge of the test pattern image formed on the image carrying surface 14 passes through the cleaning device 10, the control unit 138 stops the rotation of the photosensitive drum 12 and stops the operation of the cleaning device 10, thereby forming an image. The pre-cleaning operation by the unit 104 is completed to prepare for a normal image forming operation on the recording paper P.

In the laser printer according to the present embodiment, the control unit 138 forms a toner image on the image carrying surface 14 by the developing device 24 while stopping the operation of the transfer roll 28 before starting the use of the cleaning device 10. Voltages VB1 and VB2 having a polarity opposite to the charging polarity of the toner forming the toner are alternately applied to the brush cores 34 of the cleaning brushes 16 and 18 by the high-voltage power supply unit 90, and the brushes of the cleaning brushes 16 and 18 from the image bearing surface 14 are applied. By performing a pre-cleaning operation for transferring the toner to the bristles 36 and adsorbing and holding the toner on the bristles 36,
Prior to the actual use of the cleaning device 10 to remove and collect residual toner, toner having a higher electrical resistance than the brush bristles 36 is attached to the brush bristles 36 of the cleaning brushes 16 and 18, respectively. Since an electrical resistance layer can be formed on the surface of the brush bristles 36 with toner, when the actual use of the cleaning device 10 is started, a resistance layer is not formed on the brush bristles 36 of the cleaning brushes 16 and 18 with toner. In comparison, the electrical resistance between the brush bristles 36 of the cleaning brushes 16 and 18 and the image carrying surface 14 can be increased, and the high voltage power supply unit 90 applies a predetermined potential to the brush metal core 34 of the cleaning brushes 16 and 18. If a voltage is applied, the brush bristles 36 of the cleaning brushes 16 and 18 and the image carrying surface 14 are interposed. The strength of Jill electric field can be sufficiently secured.

  As a result, according to the laser printer according to the present embodiment, the toner (residual toner) removed and collected from the image carrying surface 14 does not adhere to the brush bristles 36 of the cleaning brushes 16 and 18 at the start of use of the cleaning device 10. However, since the strength of the electric field generated between the brush bristles 36 of the cleaning brushes 16 and 18 and the image carrying surface 14 can be sufficiently secured, it is possible to effectively prevent the cleaning performance of the cleaning device 10 from being deteriorated. it can.

  In the image forming unit 104 according to the present embodiment, the high-voltage power supply unit 90 applies positive voltages VB1, VR1, VS1 to the cleaning brush 16 and the detoning roll 40 during normal image formation, and the cleaning brush 18 The negative voltages VB2, VR2, and VS2 are applied to the detoning roll 42. Due to the function of the high-voltage power supply unit 90, when the polarity of the voltage applied to the cleaning brush 18 and the detoning roll 42 by the high-voltage power supply unit 90 cannot be reversed during the pre-cleaning operation, the toner image is formed on the image carrying surface 14. After the toner having formed thereon is adsorbed and held by the brush bristles 36 of the upstream cleaning brush 16, the toner of the cleaning brush 16 may be transferred to the brush bristles 36 of the downstream cleaning brush 16.

  In this case, as shown in the timing chart of FIG. 6B, when the control pattern 138 starts to form a test pattern image on the image bearing surface 14, the control unit 138 applies positive voltages VB1, VR1, and VS1, respectively. This is turned on, and a sufficient amount of toner is adsorbed and held on the bristle 36 of the cleaning brush 16 from the image bearing surface 14. The toner adsorbed on the brush bristles 36 of the cleaning brush 16 is charged with a reverse polarity (+ polarity) due to the phenomenon of charge injection from the bristles 36. Therefore, after the toner charged to the reverse polarity is generated by the cleaning brush 16, if a positive voltage VB2, VR2, VS2 is turned on, a part of the toner is transferred from the cleaning brush 16 to the cleaning brush 18, and the cleaning brush The 18 bristles 36 can adsorb and hold toner. Here, the voltages VB1, VR1, and VS1 are appropriately selected from the range of + 500V to + 800V, and the voltages VB2, VR2, and VS2 are appropriately selected from the range of −350V to −500V. The

  According to the laser printer of this embodiment, even when the above-described control is performed as the pre-cleaning operation, the toner (residual toner) removed and collected from the image carrying surface 14 at the start of use of the cleaning device 10 is the cleaning brush. Even if it does not adhere to the bristles 36 and 18, the strength of the electric field generated between the bristles 36 of the cleaning brushes 16 and 18 and the image carrying surface 14 can be sufficiently secured. It is possible to effectively prevent the cleaning performance due to the deterioration.

  In the laser printer according to the present embodiment, the toner image formed on the image bearing surface 14 of the photosensitive drum 12 due to the occurrence of clogging of the recording paper P in the paper feeding / conveying mechanism 110 (see FIG. 1) is transferred to the intermediate transfer belt. When untransferred toner image that cannot be transferred to 102 occurs, a toner image cleaning operation for cleaning the untransferred toner image from the photosensitive drum 12 of the image forming unit 104 is executed.

  When executing the toner image cleaning operation, the control unit 138 increases the voltage applied to the cleaning brush 16 and the detoning roll 40 by the high-voltage power supply unit 90 by a predetermined voltage value, respectively, as compared with the normal cleaning operation. Meanwhile, the image bearing surface 14 of the photosensitive drum 12 is cleaned by the cleaning device 10.

  At this time, the high voltage power supply unit 90 adds a value (preferably +50 V) set in the range of 300 V to 400 V to the voltage VB1 (+250 V to +400 V) applied to the brush metal core 34 of the cleaning brush 16 during the normal cleaning operation. Applied to the roll core metal 48 and the scraper 66 of the detoning roll 40, and voltages VS1 (+ 650V to + 800V) and VS1 (+ 650V to + 800V) respectively set in the range of 700V to 800V. The voltages VR1 ′ and VS1 ′ obtained by adding are applied. As a result, the surface potential difference between the brush bristles 36 of the cleaning brush 16 and the image carrying surface 14 is increased and the surface potential difference between the cleaning brush 16 and the detoning roll 40 is maintained at substantially the same value as compared with normal cleaning. Is done.

  Further, the control unit 138 rotates the photosensitive drum 12 over two rotations while maintaining the setting condition of the toner image cleaning operation, and performs the cleaning operation by the cleaning device 10 as many times as the rotation number of the photosensitive drum 12. repeat. At this time, the control unit 138 increases or decreases the number of repetitions of the toner image cleaning operation according to, for example, the image size and image density formed on the image carrying surface 14.

  In the laser printer according to the present embodiment, when the toner image formed on the image bearing surface 14 by the control unit 138 passes through the transfer roll 28 and remains on the image bearing surface 14, the toner image Compared with the case where the image does not remain on the image bearing surface 14, the voltage applied to the cleaning brush 16 and the detoning roll 40 is increased by the high-voltage power supply unit 90, and the surface potential difference generated between the brush bristles 36 and the image bearing surface 14. And the surface potential difference between the cleaning brush 16 and the detoning roll 40 is maintained substantially the same as that during normal cleaning, so that the toner on which the toner image is formed on the image carrying surface 14 is removed from the upstream cleaning brush 16. Thus, it can be efficiently removed from the image bearing surface 14.

  As a result, according to the cleaning device 10 according to the present embodiment, when the toner image cleaning operation is executed, the toner image is not transferred due to a paper jam or the like, and a large amount of toner remains on the image carrying surface 14. Even in this case, the toner can be removed and collected evenly from the image bearing surface 14 in a short time, so that the cleaning time after the toner image is not transferred can be shortened, and the image quality of the image formed immediately after the toner image is not transferred is generated. Can be prevented from lowering due to the influence of residual toner.

  In the laser printer according to the present embodiment, the voltage applied to the roll metal core 48 and the scraper 66 of the detoning roll 40 is slid to increase the voltage applied to the brush metal core 34 of the cleaning brush 16 to increase the voltage. However, when the initial surface potential difference between the cleaning brush 16 and the detoning roll 40 is sufficiently large, a potential difference of a certain level (for example, 400 V) can be secured even after the voltage applied to the brush core 34 of the cleaning brush 16 is increased. It is not always necessary to increase the voltage applied to the roll core metal 48 and the scraper 66 of the detoning roll 40.

  In the laser printer according to this embodiment, as the number of toner image formations on the photosensitive drum 12 in the image forming unit 104 increases, the high voltage power supply unit 90 applies the toner to the brush cores 34 of the cleaning brushes 16 and 18. A cleaning voltage aging correction operation for gradually increasing the potentials of the voltages VB1 and VB2 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 according to this 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 cores 34 and 34 of the cleaning brushes 16 and 18 to move. 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, worn, etc. as the number of cleanings increases. Even if the contact pressure and the contact area of the brush 16 with the image carrying surface 14 are reduced, it is possible to compensate for the reduction in the cleaning ability caused by these, so that the cleaning ability of the cleaning device 10 is deteriorated with time. Can be effectively prevented.

  In the laser printer according to the present embodiment, the control unit 138 applies 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 according to the temperature and humidity detected by the environmental sensor 140. While adjusting VB2, the environmental correction operation of the cleaning voltage for adjusting 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 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 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 in the air. The moisture absorption phenomenon that absorbs the moisture is likely 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 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 cleaning device 10 can be maintained substantially constant without being affected by environmental conditions.

  In the laser printer according to the second embodiment of the present invention, the cleaning apparatus 10 is configured as a part of the process cartridge 143, and the process cartridge 143 can be replaced with the apparatus main body. Even when the apparatus 10 is replaceable with respect to the main body of the apparatus, the cleaning apparatus 10 performs the pre-cleaning operation, the toner image cleaning operation, the cleaning voltage aging correction operation, or the cleaning voltage environment correction operation. Needless to say, the same effects as those of the process cartridge 143 can be obtained.

1 is a side view showing a schematic configuration of a laser printer according to a first embodiment of the present invention. It is side surface sectional drawing which shows the structure of the image formation unit in the laser printer shown by FIG. FIG. 3 is a side cross-sectional view illustrating a configuration of a cleaning brush and a detoning roll disposed on the upstream side in the cleaning device illustrated 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 cleaning device illustrated in FIG. 2. 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 a timing chart which shows the on / off timing of the voltage application to the cleaning brush and the detoning roll at the time of the pre-cleaning operation of the laser printer according to the second embodiment of the present invention.

Explanation of symbols

10 Cleaning device 12 Photosensitive drum (image carrier)
14 Image bearing surface 16 Cleaning brush (first cleaning brush)
18 Cleaning brush (second cleaning brush)
36 Brush hair (cleaning brush)
40 Detoning roll (first toner collecting roll)
42 Detoning roll (second toner collecting roll)
48 roll core metal 66 scraper 78 static elimination lamp 80 pre-cleaning corotron 86 shielding part 90 high voltage power supply unit (first voltage application means, second voltage application means, cleaning power supply part)
102 Intermediate transfer belt (intermediate transfer member)
104 Imaging unit (imaging means)
132 process cartridge 136 controller (control means)
138 Control unit (control means)
140 Environmental sensor 143 Process cartridge

Claims (9)

An image forming unit that forms a toner image on an image carrier based on an electrophotographic process; 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,
While the cleaning means is extended radially outward from the outer peripheral side of the cylindrical brush metal core, brush hair inclined in the rotational direction rearward relative to the radial direction is brought into contact with the surface of the image carrier. An electric resistance layer is provided on the outer peripheral side of the rotating first cleaning brush and the cylindrical brush core, and the first rotating brush rotates while the roll surface formed of the outer peripheral surface of the resistance layer is in contact with the brush bristles. 1 toner collecting roll and a downstream side of the first cleaning brush along the moving direction of the image carrier, extending radially outward from the outer peripheral side of the cylindrical brush core, A second cleaning brush that rotates while bringing the bristles inclined rearward in the rotational direction with respect to the radial direction into contact with the surface of the image carrier, and an electrical resistance layer on an outer peripheral side of the cylindrical brush metal core And the resistance A second toner recovery roll that rotates while contacting a roll surface of the outer peripheral surface of the brush with the brush bristles, a brush metal core of the first and second cleaning brushes, and a first toner recovery roll and a second toner recovery roll. While providing a cleaning power supply unit for applying a voltage of a predetermined potential to the roll mandrel,
Before starting the use of the cleaning means, the transfer means is stopped, and a toner image is formed on the image carrier by the image forming means, and a voltage having a polarity opposite to the charged polarity of the toner that formed the toner image is formed. Is alternately applied to the brush cores of the first and second cleaning brushes by the cleaning power supply unit, and the toner is transferred from the image carrier to the brush hairs of the first and second cleaning brushes. An image forming apparatus comprising control means for performing a pre-cleaning operation for adsorbing and holding toner on the bristles . Before starting to use the apparatus, the fine particles of the resistor having a higher electrical resistance than the brush hair are attached to the brush hairs of the first and second cleaning brushes, and the surface of the brush hair is caused by the fine particles of the resistor. The image forming apparatus according to claim 1 , wherein an electrical resistance layer is formed on the image forming apparatus . The at least one of a toner that forms a toner image on the image carrier and an external additive contained in the toner is used as the fine particles of the resistor that forms the charge retention layer. 2. The image forming apparatus according to 2. Disposed on the upstream side of the first cleaning brush along the moving direction of the image carrier, and has a charge eliminating means for neutralizing the surface of the image bearing surface,
The neutralization means includes a surface potential of the image bearing surface, the voltage applied by the first voltage application means to the brush core of the first cleaning brush, and the second voltage application means of the second cleaning brush. an intermediate potential between the voltage applied to the brush core metal, moreover claims, characterized in that the surface potential of the image bearing surface and the bristles of the first and second cleaning brushes than the discharge start voltage The image forming apparatus according to any one of claims 1 to 3 . A toner charging unit disposed adjacent to the upstream side of the charge eliminating unit along the moving direction of the image carrier and controlling the polarity and charging potential of the toner attached to the surface of the image carrying surface;
A light shielding member that shields the static elimination light emitted from the static elimination lamp used as the static elimination means and prevents the static elimination light from entering the toner charging area by the toner charging means on the surface of the image carrier;
The image forming apparatus according to claim 4, further comprising: 6. The image forming apparatus according to claim 5, wherein the light shielding member is provided integrally with a shield case for shielding discharge from a discharge wire in a wire discharge charger used as the toner charging unit. Equipment . The control means further compares the case where the toner image formed on the image carrier remains on the image carrier after passing through the transfer position by the transfer means compared to the case where the toner image does not remain. 2. The surface potential difference generated between the brush hair and the image bearing surface is increased by boosting the voltage applied to the brush core of the first cleaning brush by the cleaning power supply unit. Item 7. The image forming apparatus according to Item 6 . The control means further includes the brush cores of the first and second cleaning brushes and the first and second cleaning brushes by the cleaning power supply as the toner image formation on the image carrier by the image forming means increases. The image forming apparatus according to any one of claims 1 to 7, wherein the potential of the voltage applied to the roll cored bar of the second detoning roll is gradually increased . An environmental sensor for detecting environmental conditions including temperature and humidity in the installation environment of the cleaning device;
The control means further includes a brush metal core of the first and second cleaning brushes and a first and a second toner collecting roll of the first and second cleaning brushes by the cleaning power supply unit in accordance with the environmental condition detected by the environmental sensor. The image forming apparatus according to claim 1 , wherein the potential of the voltage applied to each of the roll cores is adjusted .

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