JP2007093792A5 - - Google Patents

Description

Image forming apparatus

  The present invention relates to an image forming apparatus such as a copying machine, a facsimile machine, and a printer. In particular, the present invention is improved so that the peripheral surface of a transfer roller as a component can be appropriately cleaned. The present invention relates to an image forming apparatus.

  The image forming apparatus irradiates a light beam based on image information onto a peripheral surface of a photosensitive drum (image carrier) rotating around an axis, on which a uniform charge is formed by a charger, thereby causing an electrostatic latent image. An image is formed, and toner is supplied from the developing device to the electrostatic latent image to form a toner image (developer image) on the peripheral surface of the photosensitive drum, and the toner image is transferred to a sheet (transfer material). It is made like that.

  The sheet is supplied between the photosensitive drum and a transfer roller whose peripheral surface is charged with a polarity opposite to that of the toner image disposed opposite to the peripheral surface of the photosensitive drum. The toner image is peeled off from the circumferential surface of the photosensitive drum by an electrostatic attraction force and is reliably transferred onto the paper. The sheet after the transfer process is introduced into a fixing device, where the developer image is fixed by heating, and is then led to the outside.

  By the way, various fillers are added to the paper, and when the paper is conveyed by the transfer roller, these fillers are scattered with the generation of the paper dust and adhere to the peripheral surface of the transfer roller together with the paper dust. . When such paper dust or filler adheres to the peripheral surface of the transfer roller, the resistance value of the transfer roller fluctuates. As a result, the electrostatic attraction force decreases, so that the toner image on the peripheral surface of the photoconductive drum is reliably attached to the paper. Not only does this cause a problem that a so-called halftone image is formed without being transferred but white spots and black spots are formed, and there is a problem that the back side of new paper is contaminated with deposits, so-called back stains occur. Were present. Furthermore, the transfer roller has a short life when paper dust or filler is attached thereto, which causes an inconvenience of increasing maintenance costs due to replacement with a new one.

In order to eliminate such inconvenience, Patent Document 1 discloses that the transfer roller is rotated in a state where the contact of the transfer roller with the photosensitive drum is temporarily released, and a brush is applied to the peripheral surface of the rotating transfer roller. In which the peripheral surface of the transfer roller is cleaned by abutting the surface. It is described that by adopting such a measure, foreign matter adhering to the peripheral surface of the transfer roller can be efficiently removed, so that a high-quality transfer image can always be obtained.
JP-A-5-333714

  However, in the method of cleaning the peripheral surface of the transfer roller described in Patent Document 1 with a brush, a mechanism for rotating the transfer roller in a state where the transfer roller is separated from the photosensitive drum in order to perform a cleaning process. It has to be provided, and the structure for that purpose becomes complicated, and there is a problem that the parts cost and the assembling cost increase.

  The present invention has been made in view of such a situation, and in particular, the transfer roller adhered to the peripheral surface of the transfer roller without providing a mechanism for separating the transfer roller from the photosensitive drum or a mechanism for rotating the separated transfer roller. An object of the present invention is to provide an image forming apparatus configured to reliably remove deposits such as paper dust and filler.

The image forming apparatus of the present invention includes an image bearing member on which the developer image is formed on the surface, the peripheral surface in contact with the surface of the image bearing member, to a transfer material the toner image on the surface of the image bearing member A transfer roller that forms a transfer nip portion to be transferred, a registration roller pair that is disposed upstream of the transfer nip portion in the conveyance direction of the transfer material, and that registers the transfer material ; and a housing that houses the transfer roller the a cleaning member for cleaning processing peripheral surface of the transfer roller in the housing, wherein the housing, the transfer material and abutting the guide section to be conveyed toward the transfer nip from the registration roller pair And is supported to be swingable about a swing shaft extending in a direction parallel to the rotation shaft of the transfer roller, and the cleaning member is in contact with the peripheral surface of the transfer roller by swinging of the housing From the contact roller and the transfer roller Is possible posture changed between the between the remote position, in the state where both the registration roller pair and the image carrier is the transfer material to rotate is being conveyed, the cleaning member takes the remote position, In a state where the registration roller pair is stopped and the image carrier is rotating, an increase in the tension of the transfer material sandwiched between the registration roller pair and the transfer nip portion causes a push on the guide portion. Pressure is applied to swing the housing, and the cleaning member takes the contact posture .

According to this configuration, the developer material on the surface of the image carrier is transferred to the transfer material by supplying the transfer material to the transfer nip portion formed by the image carrier and the transfer roller .

  The cleaning member provided so as to clean the peripheral surface of the transfer roller in the housing that houses the transfer roller includes a contact posture that contacts the peripheral surface of the transfer roller by changing the posture of the housing, and the transfer roller. Since the installation position is set so that the posture is changed between the separation posture and the separation posture separated from the transfer member, the cleaning member is separated from the peripheral surface of the transfer roller by changing the posture of the housing without providing a special structure. The posture is changed from the posture to the abutting posture, and the peripheral surface of the rotating transfer roller is cleaned by the cleaning member.

  As described above, the cleaning member can be cleaned of the peripheral surface of the transfer roller only by changing the posture of the housing, and a conventional mechanism that requires a mechanism for separating the transfer roller from the image carrier or a mechanism for rotating the transfer roller is required. Compared to brush-type cleaning, this contributes to a reduction in equipment costs.

The housing includes a guide portion that comes into contact with the transfer material to be subjected to the transfer process, and the housing is configured to be swingable by pressure applied from the guide portion. a contacting posture where the cleaning member is in contact with the peripheral surface of the transfer roller, attitude change between the remote position spaced from the transfer roller.

For this reason , when the transfer roller is subjected to a cleaning process, a transfer material that is not subjected to the transfer process is used to set the pressure applied from the transfer material to the guide portion of the casing to a predetermined pressure. The cleaning member can be brought into contact with the peripheral surface of the transfer roller by the movement, whereby the peripheral surface of the transfer roller is cleaned.

  As described above, the housing is particularly cleaned by changing the posture between the contact posture in which the cleaning member is in contact with the peripheral surface of the transfer roller and the separated posture separated from the transfer roller by the pressure from the transfer material. The cleaning member can be brought into and out of contact with the transfer roller without providing a member for bringing the member into contact with the transfer roller.

Incidentally, the housing has been conventionally swingable around the center of the transfer roller. The reason is that the tension relationship of the paper between the registration roller pair that registers the trailing edge of the paper and the image carrier and the transfer roller holding the paper due to the difference in the type of paper (for example, thin paper and thick paper). This may cause subtle changes and transfer defects (transfer deviations) may occur. However, in order to prevent such inconvenience, the housing can be swung to prevent transfer defects depending on the type of paper. It was done. In the present invention, the conventional swinging structure of the casing is applied to change the posture of the cleaning member.

Further , a registration roller pair for registering a transfer material is provided on the upstream side of the contact position between the image carrier and the transfer roller, and both the registration roller pair and the image carrier rotate so that the transfer material is In the transported state, the cleaning member takes the separation posture, and in a state where the registration roller pair is stopped while the image carrier is rotating, the cleaning member is sandwiched between the registration roller pair and the transfer nip portion. As the tension of the transfer material is increased, a pressing force acts on the guide portion, the housing swings, and the cleaning member takes the contact posture.

  According to this configuration, the transfer material is supplied between the image carrier and the transfer roller via the registration roller pair for the transfer process, and as a result, the transfer material is subjected to the transfer process. In this state, the cleaning member is separated from the peripheral surface of the transfer roller, since a large part of the housing does not receive a large force from the transfer material. Therefore, the peripheral surface of the transfer roller is not cleaned by the cleaning member.

  On the other hand, if the driving of the registration roller pair is stopped in a state where the rotation of the transfer roller and the movement of the image carrier are continued, the upstream side stops the movement even though the downstream side of the transfer material is going to advance. As a result, a large tension acts on the transfer material, so that the housing changes its posture by this tension, and the cleaning member abuts from a separated posture separated from the peripheral surface of the transfer roller by changing the posture of the housing. The posture is changed to the contact posture.

  Then, the rotation of the transfer roller is continued in a state where the cleaning member is set to the contact posture, so that the peripheral surface of the transfer roller is rubbed by the cleaning member, and is thereby adhered to the peripheral surface of the transfer roller. Deposits such as paper dust and filler are removed and cleaned.

  Thus, the posture of the housing is changed by the relaxation and tension of the transfer material by driving and stopping the pair of registration rollers in a state where the transfer material is held, and the transfer roller of the cleaning member is changed by changing the posture of the housing. Since the separation and contact with the peripheral surface is intended, the peripheral surface of the transfer roller is simply controlled by controlling the driving of existing equipment without introducing a complicated mechanism for cleaning the peripheral surface of the transfer roller. Surface deposits are removed.

According to the present invention, the cleaning member can be subjected to the cleaning process of the peripheral surface of the transfer roller only by changing the posture of the housing that supports the transfer roller. Compared with the conventional brush-type cleaning process that requires a mechanism to reduce the cost of the equipment, it is possible to remove paper dust and fillers adhering to the peripheral surface of the transfer roller Therefore, it is possible to reliably eliminate the occurrence of an image defect in the transferred image and the occurrence of the back image due to the presence of the adhered matter.

In addition , since the posture of the housing is changed between a contact posture in which the cleaning member is in contact with the peripheral surface of the transfer roller and a separation posture in which the housing is separated from the transfer roller by pressure from the transfer material. The cleaning member can be brought into and out of contact with the transfer roller without providing a member for bringing the member into contact with the transfer roller.

Further , the posture of the housing is changed by the relaxation and tension of the transfer material by driving and stopping the pair of registration rollers in a state where the transfer material is sandwiched, and the transfer roller peripheral surface of the cleaning member is changed by changing the posture of the housing Therefore, without introducing a complicated mechanism for the cleaning process of the peripheral surface of the transfer roller, the drive of the existing device is simply controlled without introducing a complicated mechanism. Adherents can be reliably removed, which can contribute to a reduction in apparatus cost.

  First, a printer as an example of an image forming apparatus according to the present invention will be described with reference to FIG. FIG. 1 is a front cross-sectional view illustrating an outline of the internal structure of an embodiment of a printer 10 according to the present invention. As shown in this figure, the printer (image forming apparatus) 10 is fed out from a sheet storage unit 12 that stores a sheet (transfer material) P to be used for printing processing, and a sheet bundle P1 stored in the sheet storage unit 12. An image forming unit 13 that performs an image transfer process on each sheet P and a fixing unit 14 that performs a fixing process on the sheet P subjected to the transfer process by the image forming unit 13 include an apparatus main body. 11, and a paper discharge unit 15 for discharging the paper P subjected to fixing processing by the fixing unit 14 is provided at the top of the apparatus main body 11.

  A predetermined number (one in this embodiment) of paper cassettes 121 is provided in the paper storage unit 12 so as to be detachable from the apparatus main body 11. At the downstream end (left side in FIG. 1) of the paper cassette 121, a pickup roller 122 that feeds the paper P one by one from the paper bundle P1 is provided. The paper P fed out of the paper cassette 121 by driving the pickup roller 122 is supplied to the image forming unit 13 through the paper feed conveyance path 123 and the registration roller pair 124 provided at the downstream end of the paper feed conveyance path 123. It is supposed to be paper.

  The image forming unit 13 performs a transfer process on the paper P based on image information transmitted from a computer or the like, and rotates around a drum shaft 131a (FIG. 3) extending in the front-rear direction (direction orthogonal to the paper surface of FIG. 1). A charging device 132, an exposure device 133, and a developing device from the upper right position in FIG. 1 of the photosensitive drum 131 in the clockwise direction along the peripheral surface of the photosensitive drum (image carrier) 131 that is rotatably provided on the photosensitive drum 131. The device 134, the transfer roller device 30, and the cleaning device 135 are provided.

  In the present embodiment, the photosensitive drum 131, the charging device 132, and the cleaning device 135 are housed in a predetermined unit body 21 and unitized as the photosensitive unit 20. Accordingly, by inserting / removing the unit main body 21 to / from the apparatus main body 11, the photosensitive drum 131, the charging device 132, and the cleaning device 135 are entirely attached to and detached from the apparatus main body 11. Incidentally, since the unit main body 21 is integrated with the apparatus main body 11 in a state of being mounted at a predetermined position in the apparatus main body 11, it can be regarded as a part of the apparatus main body 11.

  The photosensitive drum 131 is for forming an electrostatic latent image and a toner image (developer image) along the electrostatic latent image on the peripheral surface, and an amorphous silicon layer is laminated on the peripheral surface. This makes it suitable for forming these images.

  The charging device 132 forms a uniform charge on the peripheral surface of the photosensitive drum 131 rotating clockwise around the drum center, and applies a charge to the peripheral surface of the photosensitive drum 131 by corona discharge. It is supposed to be. The charging device 132 will be described in detail later with reference to FIGS.

  The exposure device 133 irradiates the peripheral surface of the rotating photosensitive drum 131 with a laser beam to which intensity is applied based on image data transmitted from an external device such as a computer, and thereby the photosensitive drum 131 is irradiated with the laser beam. An electrostatic latent image is formed on the peripheral surface of the photosensitive drum 131 by erasing the charge on the peripheral surface irradiated with the laser beam.

  The developing device 134 supplies toner to the peripheral surface of the photosensitive drum 131 to attach the toner to a portion where the electrostatic latent image is formed on the peripheral surface, and thereby the toner image is formed on the peripheral surface of the photosensitive drum 131. Is formed.

  The transfer roller device 30 transfers the positively charged toner image formed on the peripheral surface of the photosensitive drum 131 to the paper P with respect to the paper P sent to the position immediately to the left of the photosensitive drum 131. Therefore, a negative charge having a polarity opposite to that of the toner image is applied to the paper P. Accordingly, the sheet P that has reached the lower left position of the photosensitive drum 131 is pressed and held between the transfer roller device 30 and the photosensitive drum 131, and the toner image on the circumferential surface of the photosensitive drum 131 that is positively charged is negatively charged. The sheet P is peeled off toward the surface of the paper P, whereby the transfer process is performed on the paper P. The transfer roller device 30 will be described in detail later with reference to FIGS.

  The cleaning device 135 scatters when the toner remaining on the peripheral surface of the photosensitive drum 131 after the transfer process and various discharge products adhering to a charging wire 132c described later are cleaned by the charging device 132. Then, it is for removing and adhering things adhering to the peripheral surface of the photosensitive drum 131. The cleaning device 135 is provided with a rubbing roller 135 a that rubs against the peripheral surface of the photosensitive drum 131, and residual toner and discharge products that adhere to the peripheral surface of the photosensitive drum 131 by the rotation of the rubbing roller 135 a. Are scraped off (that is, the peripheral surface of the photosensitive drum 131 is polished).

  Incidentally, the cleaning process of the circumferential surface of the photosensitive drum 131 by the cleaning device 135 is performed constantly every time the image forming process is performed as long as the printer 10 is in operation, and the accumulated time of the image forming process is set in advance. The cleaning process of the present invention in which the polishing process is performed on the peripheral surface of the photosensitive drum 131 only when the set reference time is exceeded has a complementary relationship.

  The peripheral surface of the photosensitive drum 131 cleaned by the cleaning device 135 goes to the charging device 132 again for the next image forming process.

  The fixing unit 14 performs a fixing process by heating the toner image of the paper P subjected to the transfer process by the image forming unit 13. The fixing roller 141 applies heat to the paper P, and the left side of the fixing roller 141. And a pressurizing member 142 arranged to face each other.

  Then, the sheet P after the transfer process is sent toward a nip portion formed between the fixing roller 141 and the pressure member 142, and passes through the nip portion to obtain heat from the fixing roller 141. The fixing process is performed. The paper P subjected to the fixing process is discharged to the paper discharge unit 15 through the paper discharge conveyance path 143.

  The paper discharge unit 15 is formed by recessing the top of the apparatus main body 11, and a paper discharge tray 151 for receiving the discharged paper P is provided at the bottom of the concave recess.

  In the present embodiment, the blower 16 including the filter 161 for taking in outside air at the upper right position in FIG. 1 in the apparatus main body 11 and the outside air taken in via the filter 161 by the blower 16 are photosensitive. A blower duct 17 is provided for guiding the body unit 20. The outside air blown toward the photoconductor unit 20 through the blower duct 17 by driving the blower 16 penetrates the photoconductor unit 20, thereby removing moisture accumulated in the photoconductor unit 20 and discharging products. In the case where the inside of the photoconductor unit 20 is overheated by a heater (not shown) provided in the photoconductor drum 131, the inside of the photoconductor unit 20 is cooled, and in addition, discharge products are generated. Scattered matter such as dust generated by cleaning the attached charging wire 132c is caused to accompany the air current and discharged from the inside of the photoreceptor unit 20 to the outside.

  In addition, the power source device 18 that transforms the voltage of power supplied from an external commercial power source or rectifies the current and distributes the power to various locations at various places in the apparatus main body 11 and various types of image forming processing are provided. Control means 40 comprising a microcomputer for controlling the operation of the device is provided. A power switch 181 for turning on / off the supply of power from a commercial power source to the power supply device 18 is provided at an appropriate position on the upper surface of the apparatus main body 11, and image forming processing is executed in the vicinity of the power switch 181. A start key 182 is provided. When the start key 182 is pushed, a voltage transformed to a high voltage by the power supply device 18 is applied to a charging wire 132c (to be described later) of the charging device 132.

  2 is a perspective view showing an embodiment of the photoconductor unit 20. FIG. 2A is a partially cutaway overall perspective view of the photoconductor unit 20, and FIG. 2B is a front plate 22 of the photoconductor unit 20. FIG. It is the perspective view which looked at from the inner surface side. 3 is a cross-sectional view taken along line AA in FIG. 2 to 3, the XX direction is referred to as the left-right direction, and the Y-Y direction is referred to as the front-rear direction. In particular, the -X direction is leftward, the + X direction is rightward, the -Y direction is frontward, and the + Y direction is It is called the back.

  First, as shown in FIG. 2A, the photoconductor unit 20 includes a photoconductor drum 131, a charging device 132, and a unit body 21 having a box shape elongated in the front-rear direction. It is formed by mounting the cleaning device 135.

  The unit main body 21 includes a front plate 22 having a rectangular shape, a rear plate 23 arranged to face the front plate 22 at the rear, and a right side plate 24 installed between the front plate 22 and the right upper portion of the rear plate 23. The left side plate 25 (FIG. 3) installed between the upper left portions of the front plate 22 and the rear plate 23, the bottom plate 26 installed between the lower right portions of the front plate 22 and the rear plate 23, and the upper surface opening are closed. The top plate 27 is provided. Between the right side plate 24 and the bottom plate 26, there are provided a plurality of support columns 28 provided at equal pitches over the entire length in the front-rear direction, so that the unit main body 21 is strong in strength. .

  Further, the left position of the lower surface of the unit main body 21 with respect to the bottom plate 26 is opened, so that the peripheral surface of the photosensitive drum 131 can come into contact with the peripheral surface of the transfer roller 31 of the transfer roller device 30. At the same time, the light beam from the exposure device 133 (FIG. 1) can be applied to the peripheral surface of the photosensitive drum 131.

  At the right side of the top plate 27, a lattice window 271 is formed in which notch holes are formed in a lattice shape at an equal pitch over the entire length in the front-rear direction, and a blow duct is formed from the blower 16 (FIG. 1). The outside air (indicated by an arrow in FIG. 1) fed through 17 is supplied into the unit main body 21 through the lattice window 271, and after cooling the inside of the unit main body 21, it passes through the gaps at various places. 11 is exhausted.

  The photosensitive drum 131 is rotatably supported around a drum shaft 131a (FIG. 3) installed between the lower left portion of the front plate 22 and the rear plate 23, and is driven by a drum motor (not shown) in FIG. It can be rotated clockwise.

  As shown in FIG. 3, the cleaning device 135 is provided in the unit main body 21 at a position directly above the photosensitive drum 131, and the rubbing roller 135 a rubs the peripheral surface of the photosensitive drum 131 on the peripheral surface of the photosensitive drum 131. By driving and rotating in the same direction (clockwise in FIG. 3), the peripheral surface of the photosensitive drum 131 is polished to remove residual toner, discharge products, and the like attached thereto.

  The charging device 132 is provided in a state extending in the front-rear direction at a substantially central position of the unit main body 21 with the discharge surface facing the peripheral surface of the photosensitive drum 131. The charging device 132 includes a shield case 132a that is long in the front-rear direction and has an opening surface that faces the peripheral surface of the photosensitive drum 131, and a spiral rod that is built in the shield case 132a so as to extend in the front-rear direction. 132b, a plurality of charging wires 132c stretched to extend in the front-rear direction at the opening surface, and screwed to the spiral rod 132b and moved back and forth by rotation around the axis of the spiral rod 132b. And a wiping member 132d for cleaning the charging wire 132c. The spiral rod 132b can be rotated around its axis by driving a drive mechanism (not shown).

  In the charging device 132, the shield case 132 a is interlocked with the driving mechanism by the operation of a position changing mechanism (not shown), and the charging wire 132 c is close to the peripheral surface of the photosensitive drum 131 and the peripheral surface of the photosensitive drum 131. The position is changed between the separated position and the separated position.

  In the present embodiment, the distance between the charging wire 132c and the peripheral surface of the photosensitive drum 131 is set to 0.5 to 0.6 mm while the shield case 132a is positioned at the close position. The distance between the charging wire 132c and the peripheral surface of the photosensitive drum 131 is approximately 5.0 mm in a state where the shield case 132a is set at the separation position. The cleaning operation for the charging device 132 by the wiping member 132d is executed only in a state where the charging device 132 is set at the separation position.

  The transfer roller device 30 transfers a positively charged toner image formed on the peripheral surface of the photosensitive drum 131 to the paper P with respect to the paper P sent to the left position of the photosensitive drum 131. Thus, a negative charge having a polarity opposite to that of the toner image is applied to the paper P. As shown in FIGS. 2 and 3, the transfer roller device 30 accommodates and supports a transfer roller 31 disposed so that the peripheral surface thereof faces the peripheral surface of the photosensitive drum 131, and the transfer roller 31. And a cleaning plate (cleaning member) 33 that cleans and cleans the peripheral surface of the transfer roller 31.

  The transfer roller 31 includes a transfer roller shaft 311 parallel to the drum shaft 131a of the photosensitive drum 131, and a transfer roller body 312 made of a dielectric material that is concentrically and externally fitted to the transfer roller shaft 311. In the state where the printer 10 is set to the normal operation mode, a negative voltage is applied from the power supply device 18 (FIG. 1). Accordingly, when the sheet P is passed between the peripheral surface of the transfer roller main body 312 and the peripheral surface of the photosensitive drum 131 in a close contact state, a toner image made of a positively charged toner becomes a negatively charged sheet. The toner image formed on the peripheral surface of the photosensitive drum 131 is electrostatically adsorbed on the surface side of P, whereby the toner image formed on the peripheral surface of the photosensitive drum 131 is transferred to the paper P.

  Both ends of the transfer roller shaft 311 are pivotally supported by a frame (not shown) of the apparatus main body 11 so as to be rotatable about the axis, and the transfer roller main body 312 is driven and rotated around the axis by the drive motor. The transfer roller shaft 311 is integrally rotated.

  The roller support container 32 includes a bottom plate 321 formed long in the front-rear direction (a direction orthogonal to the paper surface in FIG. 3), a left plate 322 erected from the left edge of the bottom plate 321, and the right edge And a pair of front and rear side plates 324 covering the front and rear ends of the container, which is an open top type container.

  The roller support container 32 passes through the transfer roller shaft 311 in a state where it is to the right of a center line (perpendicular line passing through the center of gravity) extending in the vertical direction of the pair of front and rear side plates 324, and a portion above the center of gravity is in sliding contact. As a result, the balance is achieved in a state of being slightly rotated counterclockwise around the transfer roller shaft 311 from the upright posture S0 (a posture standing straight, see FIG. 4B). When the paper P passes through the nip N between the photosensitive drum 131 and the transfer roller 31, the roller support container 32 is pressed by the paper P at the upper edge of the right side plate 323 as shown in FIG. The balance is set so that the posture is set to the upright posture S0. In the present embodiment, the guide portion according to the present invention is formed by the upper edge of the right side plate 323.

  The cleaning plate 33 abuts on the peripheral surface of the transfer roller main body 312 rotating around the transfer roller shaft 311 to perform a cleaning process on the peripheral surface, and is made of a hard synthetic resin. The front and rear dimensions are set to be substantially the same as the front and rear dimensions of the transfer roller 31, the vertical dimension is set to be longer than the diameter of the transfer roller 31, and the upper edge is a view of the apparatus main body 11. In a state of being fixed to a substantially frame, it is hung toward the left position from the transfer roller 31 in the roller support container 32. The cleaning plate 33 is separated from the peripheral surface of the transfer roller 31 (see FIGS. 4A and 4B), and the lower plate is in contact with the peripheral surface of the transfer roller 31 (FIG. 4). (See (c))).

  In the state where the roller support container 32 is set in the upright posture S0, the cleaning plate 33 set in the separated posture is positioned between the inner surface of the left side plate 322 and the peripheral surface of the transfer roller 31. Thus, the shape of the inner space is set.

  And in the position corresponding to the lower edge part of the cleaning board 33 in the inner surface side of the roller support container 32, it is long in the front-back direction (direction orthogonal to the paper surface of FIG. 3) where the cross-sectional shape exhibited a triangular shape in front view. The interference projection 34 is projected.

  The interference protrusion 34 is provided slightly below the position of the axis O of the transfer roller 31 in a state where the roller support container 32 is set in the upright posture S0. The interference projection 34 is formed with an inclined surface 341 whose right surface is inclined downward toward the right. The inclined surface 341 is inclined so that the distance from the axis O of the transfer roller 31 gradually decreases as it goes downward. The length of the cleaning plate 33 is set so that the lower edge portion of the cleaning plate 33 is positioned at the uppermost position of the interference projection 342 in a state where the roller support container 32 is set in the upright posture S0. ing.

  In the present embodiment, the auxiliary guide 35 is provided at the lower left position of the photosensitive drum 131 so as to face the right side plate 323 of the roller support container 32, and is conveyed upward by driving the registration roller pair 124. The sheet P collides with the guide surface of the auxiliary guide 35 and is then guided to the guide surface of the auxiliary guide 35 and the right side plate 323 of the roller support container 32, thereby causing the photosensitive drum 131 and the transfer roller 31 to move. It is surely sent to the nip portion N between them.

  4A and 4B are explanatory views for explaining the action of the cleaning process of the peripheral surface of the transfer roller 31 of the transfer roller device 30 by the cleaning plate 33. FIG. 4A shows the nip between the photosensitive drum 131 and the transfer roller 31. FIG. A state in which the paper P is not fed into the portion N, (B) is a state in which the paper P is passing through the nip portion N in the transfer mode, and (C) is a cleaning process for the peripheral surface of the transfer roller 31. The state where both the photosensitive drum 131 and the transfer roller 31 are driven in a state where the nip portion N of the paper P is blocked is shown.

  First, as shown in FIG. 4A, in a state where the sheet P does not exist in the nip portion N between the photosensitive drum 131 and the transfer roller 31, the roller support container 32 receives a force from the sheet P. Accordingly, the roller support container 32 slightly rotates counterclockwise around the axis O of the transfer roller 31 from the upright posture S0 ((B) in FIG. 4), and the center of gravity passes through the axis O. The posture is set to the left leaning posture S1 tilted to the left while being positioned on the vertical line. In the state where the roller support container 32 is set to the left inclined posture S <b> 1, the cleaning plate 33 is set to the separated posture, and the lower end portion thereof is detached from the interference protrusion 34.

  Next, at the time of the transfer process in which the paper P is fed to the nip portion N by driving the registration roller pair 124, both the photosensitive drum 131 and the transfer roller 31 are directed in opposite directions, and the peripheral speed is higher than that of the registration roller pair 124. Since the sheet P is rotated slightly earlier and acts to lift the sheet P upward, the sheet P existing between the nip portion N of the photosensitive drum 131 and the transfer roller 31 and the nip portion of the registration roller pair 124 is used. The tension acts, and the upper edge of the right side plate 323 of the roller support container 32 is pressed slightly to the left by this tension.

  As a result of this pressing, the roller support container 32 is slightly rotated clockwise around the axis O, and the roller support container 32 has an interference protrusion at the lower end edge of the cleaning plate 33 as shown in FIG. The posture is set to the upright posture S0 in contact with the top of the 34 inclined surfaces 341. Incidentally, adjustment of the tension generated in the sheet P so that the roller support container 32 is in the upright posture S0 is performed by adjusting the peripheral speeds of the photosensitive drum 131 and the transfer roller 31 in relation to the peripheral speed of the registration roller pair 124. Done.

  Next, when the peripheral surface of the transfer roller 31 is cleaned, as shown in FIG. 4C, the sheet P has reached the nip portion N of the photosensitive drum 131 and the transfer roller 31, and the photosensitive member. The registration roller pair 124 is stopped while the rotation of the drum 131 and the transfer roller 31 is continued. By doing so, the paper P receives an upward force while slipping from the photosensitive drum 131 and the transfer roller 31 in a state where the conveyance of the paper P is blocked, so that the tension increases. In order to strongly press the upper edge portion of the plate 323 toward the left, the roller support container 32 is set in a right inclined posture S2 that rotates clockwise around the axis O and tilts to the right.

  When the roller support container 32 is set to the right tilting posture S2, the lower edge of the cleaning plate 33 interferes with the inclined surface 341 of the interference projection 34 as shown in FIG. The lower portion of the plate 33 is curved toward the axis O of the transfer roller shaft 311, and the posture is set to a contact posture in contact with the peripheral surface of the transfer roller 31. By continuing the rotation of the transfer roller 31 in this state, the peripheral surface of the transfer roller 31 is rubbed by the cleaning plate 33, so that the adhered foreign matter is removed.

  When the cleaning process of the peripheral surface of the transfer roller 31 by the contact with the cleaning plate 33 is completed, the driving of the registration roller pair 124 is resumed. As a result, the paper P that has slipped between the photosensitive drum 131 and the transfer roller 31 is conveyed and carried out toward the paper discharge tray 151.

  In the present embodiment, such a cleaning process of the peripheral surface of the transfer roller 31 is performed by pressing an operation key (not shown) provided at an appropriate position of the apparatus main body 11 in anticipation of a timing when the image forming process is not performed by the user. This is done by operating. That is, when the user pushes the operation key, the downstream end of the sheet P is sent to the nip portion N via the registration roller pair 124 based on a control signal from a predetermined control means. The drive is stopped and the drive of the transfer roller 31 and the photosensitive drum 131 is continued, and this state is continued for a preset time.

  Therefore, until the time elapses, the paper P continues to be in a tension state. Therefore, the cleaning plate 33 is in contact with the peripheral surface of the transfer roller 31 by changing the posture of the roller support container 32 to the right tilting posture S2. As a result, the peripheral surface of the transfer roller 31 is rubbed by the cleaning plate 33, and deposits such as paper dust and filler are removed.

  When the predetermined time elapses, the driving of the registration roller pair 124 is resumed by a control signal from the control means, so that the paper P is discharged to the outside through a normal transport route.

  In this embodiment, the transfer roller 31 is used in addition to the cleaning device 135 in order to remove and clean the discharge products adhering to the peripheral surface of the photosensitive drum 131, and the function of the transfer roller 31. Thus, the discharge products adhering to the peripheral surface of the photosensitive drum 131 are removed in earnest. This is because the cleaning device 135 mainly focuses on the removal of residual toner remaining on the photosensitive drum 131, and this alone ensures the discharge product from the peripheral surface of the photosensitive drum 131. Therefore, the transfer roller 31 having a peripheral surface opposed to the peripheral surface of the photosensitive drum 131 is used.

  Specifically, the driving time of the photosensitive drum 131 is integrated, and when the driving time exceeds a preset reference time and the timing when the image forming process is not performed is aimed at. An operation for removing the discharge product from the photosensitive drum 131 is executed. This removal operation is performed as follows. That is, first, a so-called solid black electrostatic latent image is formed on the peripheral surface of the rotating photosensitive drum 131 by light irradiation from the exposure device 133, and then the solid black electrostatic latent image is developed from the developing roller 134a of the developing device 134. Toner is supplied toward the latent image to form a positively charged solid black toner image on the peripheral surface of the photosensitive drum 131.

  Subsequently, the positively charged solid black toner image is transferred to the peripheral surface of the transfer roller 31 to which a negative bias voltage is applied. By continuing the rotation of the photosensitive drum 131 and the transfer roller 31 in this state, the peripheral surface of the photosensitive drum 131 is polished, thereby removing the discharge products adhering to the peripheral surface of the photosensitive drum 131. I am doing so.

  Usually, since the toner contains an abrasive, the peripheral surface of the photosensitive drum 131 is brought into contact with the peripheral surface of the transfer roller 31 by rotating the transfer roller 31 and the photosensitive drum 131 at a predetermined peripheral speed difference. The discharge product adhered to the peripheral surface of the photosensitive drum 131 is removed by polishing with the uniformly applied abrasive.

  Then, after such a polishing process is performed for a predetermined time, a positive bias voltage is applied to the transfer roller 31, thereby charging the transfer roller 31 positively that was electrostatically attracted to the peripheral surface of the transfer roller 31. The toner is returned to the peripheral surface of the photosensitive drum 131 again. The toner returned to the peripheral surface of the photosensitive drum 131 is collected by the cleaning device 135.

  In the present embodiment, a series of discharge product removal processing from the circumferential surface of the photosensitive drum 131 is automatically executed under the control of the control means 40 provided at an appropriate position of the apparatus main body 11. Yes. FIG. 5 is a block diagram showing an embodiment of discharge product removal control by the control means 40. FIG. 6 is an explanatory view showing the states of the peripheral surfaces of the photosensitive drum 131 and the transfer roller 31 in the process of this control. FIG. 6A shows the positively charged toner supplied from the developing roller 134a. In the state (b) being electrostatically supplied to the peripheral surface of the transfer roller 31 through the peripheral surface of 131, the periphery of the photosensitive drum 131 is caused by the abrasive in the toner adsorbed on the peripheral surface of the transfer roller 31. A state in which the surface is being polished, (C) shows a state in which the toner on the peripheral surface of the transfer roller 31 is being collected by the cleaning device 135 via the peripheral surface of the photosensitive drum 131.

  As shown in FIG. 5, the control means 40 includes a central processing unit (CPU) 41 as a central processing unit, a read only memory (ROM) 42 that is a read-only storage device attached to the CPU 41, and a CPU 41. And a RAM (Random Access Memory) 43 configured to be readable and writable for various types of data generated temporarily. The ROM 42 stores a program for executing the control. The RAM 43 is used as an area for temporarily writing and reading data used in the control operation.

  The CPU 41 determines whether or not it is time to remove the discharge product adhering to the peripheral surface of the photosensitive drum 131 when the printer 10 is set to the normal operation mode. 411, an image forming operation determining unit 412 that determines whether the printer 10 is performing an image forming operation, and the determination results of the removal timing determining unit 411 and the image forming operation determining unit 412. A control signal output unit 413 that outputs a control signal to various places to switch the operation from the normal operation mode to the discharge product removal mode is provided.

  The removal timing discriminating unit 411 determines whether or not the timing for removing the discharge products adhering to the peripheral surface of the photosensitive drum 131 has come depending on whether or not the total drive time of the exposure device 133 exceeds a preset reference time. It is a thing which discriminates.

  In order to make this determination, the ROM 42 stores the exposure time (reference time (T0)) of the exposure device 133 that is a determination criterion for removing the discharge products on the peripheral surface of the photosensitive drum 131. Further, the exposure device 133 outputs the time point when the irradiation of light to the peripheral surface of the photosensitive drum 131 is started and the time point when the light irradiation is finished to the removal timing determination unit 411 one by one.

  The removal timing discriminating unit 411 to which these irradiation start time and irradiation end time signals are input calculates the driving time (T1) of the photosensitive drum 131 one by one based on a timer 432 provided in the RAM 43. . This calculation result is accumulated in a drive time storage unit (integration unit) 431 provided in the RAM 43 and stored as a total drive time (ΣT1). The removal timing discriminating unit 411 discriminates whether or not the total driving time (ΣT1) exceeds the reference time (T0) every time a signal at the end of irradiation is input from the photosensitive drum 131, and the discrimination result is obtained. The image is output to the image forming operation determination unit 412 and the control signal output unit 413.

  The image forming operation determination unit 412 obtains a signal indicating whether the image forming process is being executed from the movement of the photosensitive drum 131. That is, a signal that the photosensitive drum 131 is being driven from the photosensitive drum 131 (specifically, a signal from a drive motor that drives the photosensitive drum 131) is input to the image forming operation determination unit 412. The image forming operation determination unit 412 outputs a command signal indicating that to the control signal output unit 413, while a signal that the photosensitive drum 131 is not being driven is displayed in the image forming operation determination unit 412. Is input to the control signal output unit 413, a command signal indicating that is output to the control signal output unit 413.

  The control signal output unit 413 is configured such that the printer 10 is in a non-operating state by a signal from the image forming operation determination unit 412 and the total drive time (ΣT1) is a reference time (T0) by a signal from the removal timing determination unit 411. Is exceeded (ΣT1> T0), a control signal for driving and rotating the photosensitive drum 131 is output, and a solid black is applied to the peripheral surface of the photosensitive drum 131 toward the exposure device 133. In addition to these, a control signal for driving the developing device 134 is output after a control signal for positively charging the developing roller 134 a is output to the power supply device 18. ing.

  Therefore, based on the control signal, the developing roller 134a rotates counterclockwise around the roller center in a state where the toner T on the peripheral surface is positively charged, as shown in FIG. In addition, the positively charged toner T on the peripheral surface is applied to the entire peripheral surface of the photosensitive drum 131 rotating clockwise around the drum shaft 131a, and is also applied to the peripheral surface of the transfer roller 31 that is negatively charged. It is adsorbed electrostatically.

  Then, when the preset time has elapsed, the drive rotation of the developing roller 134a is stopped by the control signal (stop signal) from the control signal output unit 413, so that the positively charged toner T is shown in FIG. As shown in FIG. 3, all are electrostatically adsorbed on the peripheral surface of the transfer roller 31. In this state, the transfer roller 31 continues to rotate in a direction opposite to that of the photosensitive drum 131 at a speed slightly higher than the peripheral speed of the photosensitive drum 131. Polishing is performed by the abrasive contained in T, and the attached discharge product is removed.

  The control signal output unit 413 outputs a control signal to the power supply device 18 so that a positive bias voltage is applied to the developing roller 134a for a preset time (reference time A) in the polishing mode operation. It is made like that. In order to perform such control, the ROM 42 stores the reference time A, and the control signal output unit 413 refers to the reference time A stored in the ROM 42 until the time elapses. Control is performed to apply a bias voltage toward the developing roller 134a.

  The control signal output unit 413 outputs a control signal toward the power supply device 18 so that a negative bias voltage is applied to the transfer roller 31 for a preset time (reference time B) in the polishing mode operation. It is made like that. In order to perform such control, the ROM 42 stores the reference time B, and the control signal output unit 413 refers to the reference time B stored in the ROM 42 until the time elapses. Control is performed so as to apply a negative bias voltage toward the transfer roller 31.

  When the reference time B elapses, the power supply device 18 applies a positive bias voltage toward the transfer roller 31 based on a control signal from the control signal output unit 413. Also at this time, the control signal output unit 413 outputs a control signal toward the power supply device 18 so that a bias voltage is applied to the transfer roller 31 for a preset time (reference time C). In order to perform such control, the ROM 42 stores the reference time C, and the control signal output unit 413 refers to the reference time C stored in the ROM 42 until the time elapses. Control is performed so that a bias voltage is applied toward the developing roller 134a.

  By such control, the positively charged toner T electrostatically adsorbed on the peripheral surface of the transfer roller 31 is electrostatically repelled as shown in FIG. Transition to the circumference. The toner T transferred to the peripheral surface of the photosensitive drum 131 is collected by the cleaning device 135 in accordance with the rotation of the photosensitive drum 131.

  FIG. 7 is a flowchart showing an embodiment of a flow of discharge product removal processing control by the control means 40. This control is started when the power switch 181 is turned on, and when the start key 182 is turned on (YES in step S1), an image forming process is executed (step S2).

  When the image forming process is completed, it is determined whether or not the total drive time (ΣT1) of the exposure apparatus 133 accumulated in the RAM 43 exceeds a preset reference time (T0) (ΣT1> T0). If it is determined by the determination unit 411 (step S3) and does not exceed (NO in step S3), the driving of the photosensitive drum 131, the developing roller 134a, and the transfer roller 31 is stopped (step S4), and then the process returns to step S1. On the other hand, if it exceeds (YES in step S3), control from the control signal output unit 413 is performed in a state where the driving of the photosensitive drum 131, the developing roller 134a, and the transfer roller 31 is continued (step S5). A positive bias voltage is applied to the developing roller 134a by the signal (step S6).

  In step S7, the control signal output unit 413 determines whether or not the bias voltage application time Ta to the developing roller 134a exceeds a preset reference time A. If the reference time A is exceeded (in step S7). If YES, step S9 is executed after the application of the bias voltage to the developing roller 134a is stopped (step S8). On the other hand, if the reference time A is not exceeded, the process goes to step S9 without passing through step S8. Skipped.

  In step S9, a negative bias voltage is applied to the transfer roller 31 by the control signal output unit 413. Subsequently, in step S10, whether or not the negative bias voltage application time Tb exceeds a preset reference time B is determined. If the reference time B is not exceeded (NO in step S10), the process returns to step S7. If the reference time B is exceeded, a positive bias voltage is applied to the transfer roller 31 (step S7). S11).

  Subsequently, in step S12, the control signal output unit 413 determines whether or not the positive bias voltage application time Tc exceeds a preset reference time C. If the reference time C is not exceeded (NO in step S12). ), The process returns to step S11. On the other hand, if the reference time B is exceeded, it is determined in step S13 whether or not the power switch 181 is turned off. If it is not OFF (NO in step S13), the process returns to S1.

  By controlling the application and release of a series of bias voltages to the developing roller 134a and the transfer roller 31 as described above, the toner T containing an abrasive is transferred from the peripheral surface of the developing roller 134a to the peripheral surface of the photosensitive drum 131. Is transferred to the peripheral surface of the transfer roller 31 (see (a) of FIG. 6), and the peripheral surface of the photosensitive drum 131 is subsequently moved by the abrasive contained in the toner T transferred to the peripheral surface of the transfer roller 31. When the polishing is completed, the toner T on the peripheral surface of the transfer roller 31 is transferred again to the peripheral surface of the photosensitive drum 131 and is collected by the cleaning device 135. (See (c) in FIG. 6).

  As described above in detail, the printer 10 according to the present invention includes the photosensitive drum 131 on which a toner image is formed by supplying a developer from a predetermined developing device, and the peripheral surface of the photosensitive drum 131. The transfer roller 31 is disposed opposite to the surface of the photosensitive drum 131, and a predetermined sheet P is sandwiched between the peripheral surface of the rotating transfer roller 31 and the surface of the moving photosensitive drum 131 so as to pass through. The toner image on the surface of the body drum 131 is configured to be transferred to the paper P.

  According to such a configuration, the photosensitive drum 131 having a toner image formed on the surface by supplying a developer from a predetermined developing device, and the transfer roller whose peripheral surface is arranged to face the surface of the photosensitive drum 131. The sheet P is supplied between the sheet 31 and the sheet P so that the sheet P is sandwiched between the peripheral surface of the rotating transfer roller 31 and the surface of the rotating photosensitive drum 131. As a result, the toner image on the surface of the photosensitive drum 131 is transferred onto the paper P.

  The cleaning plate 33 provided so as to clean the peripheral surface of the transfer roller 31 in the roller support container 32 that houses the transfer roller 31 contacts the peripheral surface of the transfer roller 31 by changing the posture of the roller support container 32. Since the installation position is set so as to change the posture between the contacted contact posture and the separated posture separated from the transfer roller 31, the posture of the roller support container 32 can be changed without providing a special structure. The posture of the cleaning member is changed from the separated posture separated from the peripheral surface of the transfer roller 31 to the abutting posture, so that the peripheral surface of the rotating transfer roller 31 is cleaned by the cleaning plate 33. Become.

  In this way, the cleaning plate 33 can be cleaned on the peripheral surface of the transfer roller 31 only by changing the posture of the roller support container 32 that supports the transfer roller 31, and the transfer roller 31 is separated from the photosensitive drum 131. Compared to the cleaning process using the conventional brush method that requires a mechanism to rotate and a mechanism to rotate, the deposits such as paper dust and filler adhered to the peripheral surface of the transfer roller 31 while contributing to the reduction of the apparatus cost. It becomes possible to remove the image, and the presence of the deposit can surely eliminate the occurrence of an image defect of the transfer image and the occurrence of the back image.

  In the present embodiment, a pair of registration rollers 124 for registering the paper P is provided on the upstream side of the nip portion N where the photosensitive drum 131 and the transfer roller 31 are in contact with each other. (I.e., the upper edge portion of the right side plate 323) is pivotally supported around the transfer roller shaft 311 of the transfer roller 31 in contact with the paper P to be subjected to the transfer process, and the registration roller pair 124. The cleaning plate 33 is set to the separated posture while the photosensitive drum 131 is performing the transfer process on the paper P by the movement of the photosensitive drum 131 in synchronization with the rotation of the rotation of the paper P. The cleaning plate 33 is configured to be set in a contact position by increasing the tension.

  According to such a configuration, the sheet P is supplied between the photosensitive drum 131 and the transfer roller 31 via the registration roller pair 124 for the transfer process, and thus the sheet P is subjected to the transfer process. Since no large tension is generated on the paper P, the roller support container 32, a part of which is in contact with the paper P, does not receive a large force from the paper P. The posture is set to be separated from the peripheral surface of the roller 31, and the peripheral surface of the transfer roller 31 is not cleaned by the cleaning plate 33.

  On the other hand, when the driving of the registration roller pair 124 is stopped in a state where the rotation of the transfer roller 31 and the movement of the photosensitive drum 131 are continued, although the downstream side of the paper P is about to move forward, the upstream side Since a large tension acts on the paper P because the movement is stopped, the posture of the roller support container 32 is changed by this tension, and the cleaning plate 33 is moved around the transfer roller 31 by the change of the posture of the roller support container 32. The posture is changed from a separated posture separated from the surface to a contact posture in contact.

  The rotation of the transfer roller 31 is continued while the cleaning plate 33 is set to the contact posture, so that the peripheral surface of the transfer roller 31 is rubbed by the cleaning plate 33, thereby the transfer roller 31. Deposits such as paper dust and filler adhering to the peripheral surface are removed and cleaned.

  In this way, the posture of the roller support container 32 is changed by the relaxation and tension of the paper P due to the driving and stopping of the registration roller pair 124 in a state where the paper P is sandwiched, and the posture of the roller support container 32 is changed. Since the cleaning plate 33 is separated from and contacted with the peripheral surface of the transfer roller 31, the existing apparatus is simply driven without introducing a complicated mechanism for cleaning the peripheral surface of the transfer roller 31. The deposits on the peripheral surface of the transfer roller 31 can be reliably removed only by controlling, which can contribute to the reduction of the apparatus cost.

The present invention is not limited to the above embodiment, and includes the following contents.
(1) In the above embodiment, the printer 10 is employed as the image forming apparatus. However, the present invention is not limited to the printer 10 as an image forming apparatus. There may be.
(2) In the above embodiment, the photosensitive drum 131 is described as an example of the image carrier. However, the present invention is not limited to the photosensitive drum 131 as the image carrier. A so-called transfer belt that is stretched between at least a pair of rollers and circulates may be employed as the image carrier. In this case, a toner image is formed on the surface of the transfer belt.
(3) In the above-described embodiment, a printer (image forming apparatus) 10 that employs a single photosensitive drum 131 that employs a so-called monotone printing is employed. It is not limited to being for printing, and may be for color printing provided with a plurality of photosensitive drums for each color.
(4) In the above embodiment, the control by the control means 40 for cleaning the peripheral surface of the photosensitive drum 131 using the transfer roller 31 has been described in detail with reference to FIGS. Equivalent control may be applied to the cleaning process of the peripheral surface of the transfer roller 31.

  In this case, the ROM 42 stores the accumulated reference exposure time of the photosensitive drum 131 for performing the cleaning process on the transfer roller 31, and the removal timing determination unit 411 determines the exposure time from the exposure device 133. Each time a signal is input, it is accumulated, and when this accumulated value exceeds the reference exposure time, the sheet P is fed out from the sheet cassette 121 toward the control signal output unit 413 and the registration roller pair 124 and the nip portion. In order to output a control signal to be maintained in a tension state with N, a command signal is output to the control signal output unit 413.

  Therefore, the control signal output unit 413 that has received this command signal outputs a control signal for feeding the paper P toward the pickup roller 122 and also toward the registration roller pair 124, the photosensitive drum 131, and the transfer roller shaft 311. Then, a control signal for driving these is output, and then a control signal for stopping the driving of the registration roller pair 124 is output when the leading edge of the paper P reaches the nip portion N. With the output of the control signal from the control signal output unit 413, the sheet P is in a tension state between the nip portion N and the registration roller pair 124 as shown in FIG. The cleaning plate 33 comes into contact with the peripheral surface of the rotating transfer roller 31 by changing the posture to the right tilting posture S2 by the rotation of the support container 32 around the transfer roller shaft 311, and the transfer roller 31 is cleaned by rubbing by this. Will be given.

  When a preset time elapses, the registration roller pair 124 is re-driven by a control signal from the control signal output unit 413, whereby the paper P is carried out to the outside. Thereafter, the registration roller pair 124, the photosensitive drum 131, and the transfer roller 31 are stopped by a stop signal from the control signal output unit 413, and a series of cleaning processes of the transfer roller 31 is completed.

It is explanatory drawing of front sectional view which shows the outline | summary of the internal structure of one Embodiment of the printer which concerns on this invention. FIG. 2 is a perspective view showing an embodiment of the photoreceptor unit, where (a) is a partially cutaway overall perspective view of the photoreceptor unit, and (b) is a perspective view of the front plate of the photoreceptor unit as viewed from the inner surface side. It is. It is the sectional view on the AA line of FIG. It is explanatory drawing for demonstrating the effect | action of the cleaning process of the surrounding surface of the transfer roller of the transfer roller apparatus by a cleaning board, (A) is not sending paper in the nip part N of a photoconductive drum and a transfer roller. The state (b) is a state in which the sheet is passing through the nip portion N in the transfer mode, and (c) is a state in which the passage of the sheet P to the nip portion N is prevented due to the cleaning process of the peripheral surface of the transfer roller. FIG. 4 shows a state in which both the photosensitive drum and the transfer roller are driven. It is a block diagram which shows one Embodiment of the discharge product removal control by a control means. FIG. 4B is an explanatory diagram illustrating the states of the peripheral surfaces of the photosensitive drum and the transfer roller in the control process. The state in which the peripheral surface is being electrostatically supplied, (b) is the state in which the peripheral surface of the photosensitive drum is being polished by the abrasive in the toner adsorbed on the peripheral surface of the transfer roller, The respective states show that toner on the peripheral surface of the transfer roller is being collected by the cleaning device via the peripheral surface of the photosensitive drum. It is a flowchart which shows one Embodiment of the flow of the discharge product removal process control by a control means.

10 Printer (image forming device)
DESCRIPTION OF SYMBOLS 11 Apparatus main body 12 Paper storage part 121 Paper cassette 122 Pickup roller 123 Paper feed conveyance path 124 Registration roller pair 13 Image formation part 131 Photosensitive drum (image carrier)
131a drum shaft 132 charging device 132a shield case 132b spiral rod 132c charging wire 132d wiping member 133 exposure device 134 developing device 134a developing roller 135 cleaning device 135a rubbing roller 14 fixing unit 141 fixing roller 142 pressure member 143 discharge conveyance path DESCRIPTION OF SYMBOLS 15 Paper discharge part 151 Paper discharge tray 16 Blower 161 Filter 17 Air duct 18 Power supply 181 Power switch 182 Start key 20 Photosensitive unit 21 Unit main body 22 Front plate 23 Rear plate 24 Right side plate 25 Left side plate 26 Bottom plate 27 Top plate 271 Grid Window 28 Post 30 Transfer roller device 31 Transfer roller 311 Transfer roller shaft 312 Transfer roller body 32 Roller support container (housing)
321 Bottom plate 322 Left side plate 323 Right side plate (guide portion) 324 Front and rear side plates 33 Cleaning plate (cleaning member) 34 Interference projection 341 Inclined surface 342 Interference projection 35 Auxiliary guide 40 Control means 41 CPU 411 Removal timing discrimination portion 412 Image formation operation discrimination portion 413 Control signal output unit 42 ROM 43 RAM
431 Drive time storage unit (integration unit)
432 Timer N Nip part O Axis center P Paper (transfer material)
P1 Paper bundle S0 Erect posture S1 Left tilt posture S2 Right tilt posture

Claims (1)

An image carrier on which a developer image is formed;
Circumferential surface in contact with the surface of the image bearing member, a transfer roller for forming a transfer nip for transferring the transfer material a developer image on the surface of the image bearing member,
A registration roller pair that is disposed upstream of the transfer nip portion in the conveyance direction of the transfer material, and that registers the transfer material;
A housing for housing the transfer roller;
And a cleaning member for cleaning processing peripheral surface of the transfer roller in the housing,
The housing includes a guide portion that comes into contact with the transfer material conveyed from the pair of registration rollers toward the transfer nip portion, and swings about a swing shaft that extends in a direction parallel to the rotation axis of the transfer roller. Supported movably,
The cleaning member can be changed in posture between a contact posture in contact with the peripheral surface of the transfer roller by swinging the housing and a separation posture separated from the transfer roller ,
In a state where both the registration roller pair and the image carrier rotate and the transfer material is conveyed, the cleaning member takes the separation posture,
In a state where the registration roller pair is stopped and the image carrier is rotating, an increase in the tension of the transfer material sandwiched between the registration roller pair and the transfer nip portion causes a push on the guide portion. An image forming apparatus, wherein the housing is swung by pressure and the cleaning member takes the contact posture .