JP2007199537A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus which makes discharge wire cleaning operation and blocking preventing operation compatible and quickly and effectively achieves both operations as a result. <P>SOLUTION: When a control part 102 judges that toner images are printed out on the prescribed number of paper sheets or more, cleaning operation of a discharge wire 46 is performed. At this time, when a cleaning member 48 is moved along the extending direction of the discharge wire 46, a discharge defect occurs on a portion where the cleaning member 48 is brought into contact with the discharge wire 46. Thereby, a charge defect portion of corona discharge is formed on the surface of a photosensitive drum 24. When toner T is supplied to the surface of the photosensitive drum 24, the toner T is stuck to the charge defect portion of the photosensitive drum 24 and the charge defect portion is blackened. When the photosensitive drum 24 is continued to be rotationally drive, the toner T constituting a black line on the charge defect portion of the photosensitive drum 24 is soon supplied to a gap formed between a cleaning blade 42 and the surface of the photosensitive drum 24 and blocking preventing operation is performed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus, and in particular, a discharge wire that corona discharges on the surface of a photosensitive drum, a cleaning member that cleans the discharge wire, and a cleaning blade that removes foreign matters such as toner adhering to the surface of the photosensitive drum. And an image forming apparatus.

  Conventionally, an image forming apparatus that can automatically clean a discharge wire is known (see Patent Document 1 below). According to this image forming apparatus, automatic cleaning of the discharge wire is performed while the image forming apparatus is not performing image formation, regardless of other controls. In this case, since the cleaning work is performed only for the discharge wire, the time is not effectively used, and a waste time is generated.

On the other hand, in an image forming apparatus that cleans the surface of a photosensitive drum with a cleaning blade, toner, carrier, paper dust, or the like adheres between the cleaning blade and the surface of the photosensitive drum, resulting in blocking phenomenon (the cleaning blade may be chattered or chipped In general, a so-called anti-blocking operation in which toner is supplied and filled in a gap formed between the cleaning blade and the surface of the photosensitive drum is generally performed. .
JP-A-8-15963 JP 9-34224 A

  By the way, in the conventional image forming apparatus, the technical idea relating the timing of the discharge wire cleaning operation and the timing of the anti-blocking operation for forcibly supplying and filling the toner between the cleaning blade and the photosensitive drum surface is as follows. I didn't find it.

  Therefore, in consideration of the above circumstances, the present invention associates the timing of the discharge wire cleaning work with the timing of the anti-blocking operation to achieve both the discharge wire cleaning work and the anti-blocking work in an effective manner in a short time. An object of the present invention is to provide an image forming apparatus capable of performing the above.

  According to a first aspect of the present invention, there is provided a photosensitive drum that is rotatably driven, a discharge wire that extends along an axial direction of the photosensitive drum, and corona discharges on a surface of the photosensitive drum, and a direction in which the discharge wire extends. A cleaning member that moves to clean the discharge wire, a blade that collects foreign matter on the surface of the photosensitive drum, a developing roller that supplies toner to the surface of the photosensitive drum, the surface of the photosensitive drum, and the developing roller A voltage applying unit that applies a predetermined developing bias voltage between the image forming apparatus and the image forming apparatus, wherein the predetermined developing bias voltage is applied by the voltage applying unit and the photosensitive drum is rotationally driven. And moving the cleaning member along the direction in which the discharge wire extends to form a poorly charged portion of the corona discharge on the surface of the photosensitive drum. The toner is supplied to the surface of the ram so that the toner adheres to the poorly charged portion of the photosensitive drum, and the toner in the poorly charged portion is supplied to a gap formed by the blade and the surface of the photosensitive drum. It is characterized by that.

  According to the first aspect of the present invention, when the cleaning member is moved along the extending direction of the discharge wire in a state where the predetermined developing bias voltage is applied by the voltage applying unit and the photosensitive drum is rotationally driven, A poorly charged portion of corona discharge is formed on the surface of the photosensitive drum. When toner is supplied to the surface of the photosensitive drum, the toner adheres to the poorly charged portion of the photosensitive drum. Since the photosensitive drum is rotationally driven, the toner adhering to the poorly charged portion is eventually supplied to the gap formed by the blade and the surface of the photosensitive drum (blocking prevention work). In this way, by effectively utilizing the charging failure that occurs during cleaning of the discharge wire, toner is adhered thereto, and this toner is supplied to the gap formed by the blade and the surface of the photosensitive drum, thereby cleaning the discharge wire. Can be associated with the timing of anti-blocking work. As a result, the time can be shortened by making both the cleaning operation and the blocking prevention operation of the discharge wire both independent and independent.

  According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the image forming apparatus further includes a printing unit that prints an image formed on the surface of the photosensitive drum on a sheet, and the image is printed on a predetermined number of sheets or more. When printing is performed by the printing unit, the cleaning member is moved along the direction in which the discharge wire extends to form a poorly charged portion of the corona discharge on the surface of the photosensitive drum, and on the surface of the photosensitive drum. Supplying the toner, causing the toner to adhere to the poorly charged portion of the photosensitive drum, and supplying the toner in the poorly charged portion to a gap formed by the blade and the surface of the photosensitive drum; To do.

  According to the second aspect of the present invention, when an image is printed on a predetermined number of sheets or more by the printing unit, the cleaning member is moved along the direction in which the discharge wire extends to corona discharge on the surface of the photosensitive drum. Is formed, the toner is supplied to the surface of the photosensitive drum, the toner adheres to the poorly charged portion of the photosensitive drum, and the toner of the poorly charged portion is supplied to the gap formed by the blade and the surface of the photosensitive drum. Is done. Thus, by using the number of printed sheets as a trigger, the timing of the discharge wire cleaning operation and the anti-blocking operation can be easily matched.

  According to a third aspect of the present invention, in the image forming apparatus according to the first aspect of the present invention, the image forming apparatus includes a printing unit that prints an image formed on the surface of the photosensitive drum on a sheet, and printing on the sheet by the printing unit. When the time has reached a predetermined time or more, the cleaning member is moved along the direction in which the discharge wire extends to form a poorly charged portion of the corona discharge on the surface of the photosensitive drum, and the surface of the photosensitive drum And supplying the toner to the poorly charged portion of the photosensitive drum, and supplying the toner in the poorly charged portion to a gap formed by the blade and the surface of the photosensitive drum. And

  According to the third aspect of the present invention, when the printing time on the paper by the printing unit exceeds a predetermined time, the cleaning member is moved along the direction in which the discharge wire extends so that the corona is placed on the surface of the photosensitive drum. A poorly charged portion of discharge is formed, toner is supplied to the surface of the photosensitive drum, the toner adheres to the poorly charged portion of the photosensitive drum, and the toner in the poorly charged portion is formed in a gap formed between the blade and the surface of the photosensitive drum. Supplied. Thus, by using the printing time by the printing unit as a trigger, it is possible to easily match the timing of the discharge wire cleaning operation and the blocking prevention operation.

  According to a fourth aspect of the present invention, in the image forming apparatus according to the first aspect, after the constituent members constituting the image forming apparatus are replaced, the cleaning member is moved along the direction in which the discharge wire extends. Forming a poorly charged portion of the corona discharge on the surface of the photosensitive drum, supplying the toner to the surface of the photosensitive drum, and attaching the toner to the poorly charged portion of the photosensitive drum; The toner is supplied to a gap formed by the blade and the surface of the photosensitive drum.

  According to the fourth aspect of the present invention, after the constituent members constituting the image forming apparatus are replaced, the cleaning member is moved along the direction in which the discharge wire extends, and the poorly charged portion of the corona discharge is formed on the surface of the photosensitive drum. Is formed, the toner is supplied to the surface of the photosensitive drum, the toner adheres to the poorly charged portion of the photosensitive drum, and the toner of the poorly charged portion is supplied to the gap formed by the blade and the surface of the photosensitive drum. Thus, by using the replacement timing of the constituent members constituting the image forming apparatus as a trigger, the timing of the discharge wire cleaning operation and the anti-blocking operation can be easily matched.

  A fifth aspect of the present invention is the image forming apparatus according to any one of the first to fourth aspects, further comprising a transfer roller that transfers the toner image formed on the surface of the photosensitive drum onto the sheet. A voltage having the same polarity as the toner adhered to the surface of the photosensitive drum is applied to the transfer roller.

  According to the fifth aspect of the present invention, when the voltage having the same polarity as the toner adhered to the surface of the photosensitive drum is applied to the transfer roller, the toner in the poorly charged portion of the photosensitive drum moves to the transfer roller side. Can be prevented. As a result, it is possible to prevent the amount of toner supplied to the gap formed between the blade and the surface of the photosensitive drum from being reduced, and to prevent the blocking prevention operation from being incomplete. Further, by preventing the toner in the poorly charged portion of the photosensitive drum from moving to the transfer roller side, it is possible to prevent the paper in contact with the transfer roller from being stained with toner.

  According to the present invention, the discharge wire cleaning work and the blocking prevention work can be effectively realized in a short time by associating the timing of the discharge wire cleaning work with the timing of the blocking prevention work.

  Next, an image forming apparatus according to an embodiment of the present invention will be described with reference to the drawings.

  As shown in FIGS. 1 to 3, the image forming apparatus 10 is a scanner, a printer, a copier, a facsimile, or a complex machine that combines these functions. The image forming apparatus 10 mainly includes an image forming unit 12, an exposure unit 14, a developing unit 16, and a fixing unit 18, and the units 12, 14, 16, and 18 are included in the paper feeding cassette 20. It is arranged above. In addition, a duct 22 used to discharge the atmosphere inside the image forming apparatus 10 to the outside is formed in the upper part inside the image forming apparatus 10.

  Here, an outline of the image forming process performed by the image forming apparatus 10 will be described. When the paper is fed from the paper feed cassette 20, the toner image formed on the surface of the photosensitive drum 24 of the image forming unit 12 is transferred to the paper. Next, the toner image transferred to the paper is fixed on the paper by the fixing unit 18. The paper on which the fixing process has been completed is discharged to the paper discharge tray 28 via the main conveyance path 26.

  When the double-sided printing process is performed on the paper, the paper on which the printing process on one side is completed is re-supplied to the image forming unit 12 via the reverse path 30. In the image forming unit 12, an image forming process is executed on the other side of the sheet.

  The image forming unit 12 is an element that forms a toner image and transfers the toner image onto paper fed from the paper feed cassette 20. As shown in FIG. 1, the image forming unit 12 mainly includes a photosensitive drum 24 that is rotatably provided and used as a photosensitive member, a charging unit 32 that applies a negative charge to the surface of the photosensitive drum 24, and a photosensitive member. And a cleaning unit 34 for cleaning the surface of the drum 24.

  The photosensitive drum 24 has a photoconductive film on its surface and is used as an electrophotographic photoreceptor. As shown in FIG. 1, the photosensitive drum 24 is disposed near the lower portion of the image forming unit 12. The photosensitive drum 24 is housed in the frame 36 so that the lower side thereof is exposed to the outside. Therefore, when the portion of the photosensitive drum 24 exposed from the frame 36 is in contact with the developing roller 38 and the transfer roller 40 of the developing unit 16, the toner supply and the transfer process can be performed.

  The cleaning unit 34 is housed in a frame 36 and includes a cleaning blade 42 that collects foreign matters such as toner, carrier, paper dust, and the like that remain without being transferred from the photosensitive drum 24. The collected foreign matter is transported to a waste toner tank 44 by a transport mechanism (not shown) and provided in the waste toner tank 44. Therefore, the image forming unit 12 can execute a good image forming process without being affected by foreign matters such as residual toner.

  As shown in FIGS. 2 and 3, the charging unit 32 includes a discharge wire 46 that corona discharges on the surface of the photosensitive drum 24, a cleaning member 48 that cleans the discharge wire 46, and a cleaning member 48 that extends from the discharge wire 46. A screw conveying mechanism 50 that moves along the direction, and is arranged at an upper position in the frame 52 so as to face the photosensitive drum 24. The screw conveying mechanism 50 as a moving means of the cleaning member 48 includes a rotation shaft 54 that is pivotally supported at both ends in the longitudinal direction in the frame 52, and is provided spirally on the rotation shaft 54 to rotate the cleaning member 48. A drive motor 58 that includes a screw blade 56 that feeds in the axial direction of the shaft 54 and transmits power to the rotary shaft 54 is provided on the apparatus body 11 side.

  As shown in FIG. 2, the drive motor 58 that is a drive source of the screw conveyance mechanism 50 is configured by a stepping motor that can rotate forward and backward, and the drive motor 58 is attached to the apparatus main body 11 via a bracket 60. ing. A reduction gear 62 and a transmission gear 64 are rotatably attached to the bracket 60, and a drive gear 68 is attached to an output shaft 66 of the drive motor 58. The drive gear 68 and the reduction gear 62 are connected to each other. The reduction gear 62 and the transmission gear 64 are engaged with each other.

  A transmission gear 70 is attached to one end in the longitudinal direction of the rotation shaft 54 of the screw transport mechanism 50. With the image forming unit 12 mounted on the apparatus main body 11, the transmission gear 64 and the screw on the apparatus main body 11 side. The transmission gear 70 of the rotation shaft 54 of the transport mechanism 50 is configured to mesh.

  With such a configuration, by providing the drive motor 58 for moving the cleaning member 48 in the image forming unit 12 on the apparatus main body 11 side, it is possible to make the photosensitive drum unit 12 compact and reduce the weight. it can.

  As shown in FIG. 3, the transmission gear 64 on the apparatus main body 11 side is configured to be slidable in the axial direction with respect to the rotating shaft 72, and a stopper 74 is attached to the outer end portion of the rotating shaft 72. An elastic member 76 such as a spring is externally fitted between the bracket 60 and the transmission gear 64 on the rotating shaft 72. As described above, the elastic member 76 is provided between the inner surface of the transmission gear 64 and the outer surface of the bracket 60, and the elastic member 76 is configured to absorb the assembly error. When mounted on the main body 11, the transmission gear 64 on the apparatus main body 11 side and the transmission gear 70 of the rotating shaft 54 of the screw conveying mechanism 50 are configured to reliably mesh with each other.

  As shown in FIG. 2, the discharge wire 46 is supported at both ends in the longitudinal direction of the frame 52, and is stretched above the photosensitive drum 24. The cleaning member 48 is configured to reciprocate along the direction in which the discharge wire 46 extends.

  As shown in FIG. 3, end blocks 78 that restrict the movement of the cleaning member 48 are provided at both ends of the moving path of the cleaning member 48, and the end blocks 78 are arranged at both ends in the longitudinal direction of the frame 52. And formed integrally with the frame 52. Then, as shown in FIG. 2, at the longitudinal end of the frame 52 (the end opposite to the drive motor 58), a position for detecting the presence or absence of the cleaning member 48 along the movement path of the cleaning member 48. A detection sensor 80 is provided. The cleaning member 48 uses this position detection sensor 80 as a home position and stands by at this home position before cleaning. The cleaning member 48 reciprocates several times along the direction in which the discharge wire 46 extends by forward and reverse rotation of the drive motor 58. After moving and cleaning the discharge wire 46, it is configured to wait again at the home position.

  As shown in FIG. 3, the cleaning member 48 includes a main body 82 that cleans the discharge wire 46 and a support portion 84 that supports the main body 82. The main body 82 is configured in a “gate” shape, and the discharge wire 46 is disposed between the inner peripheral portions surrounded by the “gate” character. Further, the distal end portion of the support portion 84 is engaged with the screw blade 56 of the screw conveyance mechanism 50.

  Further, the cleaning member 48 is provided with an elastic member 86 such as a spring at a side end portion facing the end block 78 on the drive motor 58 side (opposite side to the position detection sensor 80 side). The elastic member 86 has an axial length L1 longer than a distance L2 between the end block 78 on the drive motor 58 side and the rotation surface of the end of the screw blade 56 facing the end block 78. It is configured.

  As described above, the moving mechanism of the cleaning member 48 is configured. When the discharge wire 46 is cleaned by the cleaning member 48, the drive motor 58 is rotated in the forward direction to rotate the screw blades via the gears 68, 62, 64, 70. By rotating the rotation shaft 54 of 56 in the forward direction, the cleaning member 48 at the home position on the side of the position detection sensor 80 is pushed and guided by the screw blades 56 of the screw conveying mechanism 50 toward the drive motor 58. Then, the discharge wire 46 is cleaned.

  On the other hand, when the cleaning member 48 sent to the front side of the end block 78 on the drive motor 58 side by the screw blade 56 is turned back, the position detection sensor 80 of the cleaning member 48 is switched when the rotation direction of the drive motor 58 is switched to the reverse rotation. The end portion on the side is once disengaged from the engagement with the end portion on the drive motor 58 side of the screw blade 56. At this time, the elastic member 86 compressed between the end block 78 on the drive motor 58 side is the cleaning member 48. Acts as an auxiliary moving means for moving the cleaning member 48 and pushes the cleaning member 48 back to the position detection sensor 80 side. Then, the end of the cleaning member 48 on the drive motor 58 side is engaged with the end of the screw blade 56 on the drive motor 58 side, and then the cleaning member 48 is pressed by the screw blade 56 on the end of the drive motor 58 side. It is sent to the position detection sensor 80 side.

  Further, the exposure unit 14 includes a plurality of light emitting units (for example, LEDs (Light Emitting Diode): not shown) arranged in a substantially linear shape. As shown in FIG. 1, the exposure unit 14 is disposed obliquely below the photosensitive drum 24 so that the light emitting unit 88 is in contact with the surface of the photosensitive drum 24.

  Thus, when the lighting control (exposure processing) of each light emitting unit 88 is executed based on the image data printed on the paper, the negative portion of the surface of the photosensitive drum 24 irradiated with the light from the light emitting unit 88 is negatively affected. Are removed. That is, an electrostatic latent image corresponding to the image data is formed on the surface of the photosensitive drum 24.

  As shown in FIG. 1, the developing unit 16 mainly includes a supply roller 90 and a developing roller 38, and supplies non-magnetic toner to the surface of the photosensitive drum 24. That is, the supply roller 90 applies a negative charge of unused non-magnetic toner delivered from the toner tank 92 and supplies the negatively charged toner to the developing roller 38.

  The developing roller 38 supplies negatively charged toner to the photosensitive drum 24 on which the electrostatic latent image is formed. As a result, the toner supplied from the developing roller 38 to the photosensitive drum 24 adheres to the portion of the surface of the photosensitive drum 24 from which negative charges have been removed.

  The transfer roller 40 is disposed on the opposite side of the photosensitive drum 24 with the main conveyance path 26 interposed therebetween. A bias voltage is applied to the transfer roller 40, and the transfer roller 40 is positively charged. As a result, when the sheet passes between the photosensitive drum 24 and the transfer roller 40, the negatively charged toner on the surface of the photosensitive drum 24 tends to move to the transfer roller 40 side. Therefore, the toner image on the photosensitive drum 24 is transferred to the sheet. The sheet on which the toner image is transferred is conveyed to the fixing unit 18.

  As shown in FIG. 1, the fixing unit 18 mainly includes a heat roller 94 and a press roller 96. The heat roller 94 is made of a metal having good heat conductivity (for example, aluminum), and a heater 98 made of, for example, a halogen lamp is disposed therein. The press roller 96 is disposed on the opposite side of the heat roller 94 with the main conveyance path 26 interposed therebetween. Thus, when the sheet is conveyed to the nip portion between the heat roller 94 and the press roller 96, the sheet is heated and pressurized. Therefore, the toner image transferred to the paper is printed on the paper and fixed.

  As shown in FIG. 1, the power supply unit 100 is provided at the bottom of the apparatus main body 11 of the image forming apparatus 10. The power supply unit 100 manages power necessary for drive control of the image forming apparatus 10. A predetermined developing bias voltage is applied between the surface of the photosensitive drum 24 and the developing roller 38 by the power supply unit 100, and a voltage having the same polarity as the toner attached to the surface of the photosensitive drum 24 is applied to the transfer roller 40. The

  The power supply unit 100 incorporates a control unit 102. The control unit 102 controls driving of the entire image forming apparatus 10.

  Next, the operation of the image forming apparatus 10 according to the present embodiment will be described.

  As shown in FIG. 6, when the image forming apparatus 10 is on standby (step 10) and the control unit 102 determines that there is a print signal (step 12: YES), each unit 12, 14, 16, 18 Is controlled to start driving (step 14). At this time, a predetermined developing bias voltage is applied between the surface of the photosensitive drum 24 and the developing roller 38 by the power supply unit 100, and the photosensitive drum 24 is rotationally driven by the control unit 102. Then, a predetermined toner image is printed on the paper (step 16).

  Here, when the control unit 102 determines that a toner image has been printed on a predetermined number or more sheets (step 18: YES), a cleaning operation of the discharge wire 46 is executed (step 20). At this time, as shown in FIGS. 3 and 4, the cleaning member 48 is moved along the direction in which the discharge wire 46 extends, but when the cleaning member 48 is moved in the direction in which the discharge wire 46 extends, A charging failure occurs at a portion where the cleaning member 48 and the discharge wire 46 are in contact with each other. As a result, a poorly charged portion of corona discharge is formed on the surface of the photosensitive drum 24. When the toner T is supplied to the surface of the photosensitive drum 24, the toner T adheres to the poorly charged portion of the photosensitive drum 24, and the poorly charged portion becomes black. As a result of the cleaning member 48 moving along the direction in which the discharge wire 46 extends, the black line extends in the poorly charged portion on the surface of the photosensitive drum 24 so as to curve in the axial direction. When the photosensitive drum 24 continues to rotate, the toner T constituting the black line of the poorly charged portion of the photosensitive drum 24 is eventually supplied to the gap formed by the cleaning blade 42 and the surface of the photosensitive drum 24 (FIG. 5). reference). Thereby, the blocking prevention work is executed (step 22).

  As described above, by effectively utilizing the charging failure that occurs when the discharge wire 46 is cleaned, the toner is attached thereto, and this toner is supplied to the gap formed between the cleaning blade 42 and the surface of the photosensitive drum 24. The timing of the discharge wire 46 cleaning operation and the anti-blocking operation timing can be associated with each other. As a result, it is possible to shorten the time by making both the cleaning operation and the blocking prevention operation of the discharge wire 46 performed separately and by making both compatible.

  In particular, by using the number of printed sheets as a trigger, the timing of the discharge wire 46 cleaning operation and the anti-blocking operation timing can be easily matched.

  As shown in FIG. 6, after the blocking prevention work is finished, the rotation drive of the photosensitive drum 24 is stopped by the control unit 102 (step 24), and the image forming apparatus 10 is on standby again (step 10). ).

  In the above embodiment, the process using the number of printed sheets as a trigger has been described. However, the present invention is not limited to this. For example, the sheet by the printing unit (for example, each unit 12, 14, 16, 18, etc.) The timing of cleaning the discharge wire 46 by using, as a trigger, the printing time on the printer, the timing at which the constituent members constituting the image forming apparatus 10 (for example, the units 12, 14, 16, 18 etc.) are replaced, etc. And the timing of blocking prevention work can be more easily matched.

  Further, when the voltage having the same polarity as the toner attached to the surface of the photosensitive drum 24 is applied to the transfer roller 40 by the power supply unit 100, the toner in the poorly charged portion of the photosensitive drum 24 moves to the transfer roller 40 side. Can be prevented. Thereby, it is possible to prevent the amount of toner supplied to the gap formed between the cleaning blade 42 and the surface of the photosensitive drum 24 from being reduced, and it is possible to prevent the blocking prevention work from being incomplete. Further, by preventing the toner in the poorly charged portion of the photosensitive drum 24 from moving to the transfer roller 40 side, it is possible to prevent the paper that contacts the transfer roller 40 from being contaminated with toner in the subsequent image forming process.

1 is a cross-sectional view of an image forming apparatus according to an embodiment of the present invention. 1 is a perspective view of an image forming unit used in an image forming apparatus according to an embodiment of the present invention. FIG. 3 is a cross-sectional view illustrating a moving unit of a cleaning member that constitutes an image forming apparatus according to an embodiment of the present invention. 1 is a conceptual diagram illustrating a main part of an image forming apparatus according to an embodiment of the present invention. 3 is a conceptual diagram illustrating an example of an anti-blocking operation of the image forming apparatus according to the embodiment of the present disclosure. FIG. 5 is a flowchart illustrating an operation of the image forming apparatus according to the embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 12 Image forming unit (component, printing part)
14 Exposure unit (components, printing part)
16 Development unit (components, printing part)
18 Fixing unit (components, printing part)
24 Photosensitive drum 38 Developing roller 40 Transfer roller 42 Cleaning blade (blade)
46 Discharge wire 48 Cleaning member 100 Power supply part (voltage application part)

Claims (5)

A photosensitive drum that is rotatably driven, a discharge wire that extends along the axial direction of the photosensitive drum, and corona discharges on the surface of the photosensitive drum, and moves in the direction in which the discharge wire extends to clean the discharge wire. A cleaning member, a blade for collecting foreign matter on the surface of the photosensitive drum, a developing roller for supplying toner to the surface of the photosensitive drum, and a predetermined developing bias voltage between the surface of the photosensitive drum and the developing roller An image forming apparatus having a voltage applying unit for applying
In a state where the predetermined developing bias voltage is applied by the voltage application unit and the photosensitive drum is driven to rotate, the cleaning member is moved along the direction in which the discharge wire extends to move the cleaning drum onto the surface of the photosensitive drum. A poorly charged portion of corona discharge is formed, the toner is supplied to the surface of the photosensitive drum, the toner is attached to the poorly charged portion of the photosensitive drum, and the toner in the poorly charged portion is removed from the blade and the photosensitive member. An image forming apparatus, wherein the image forming apparatus is supplied to a gap formed by a surface of a drum. A printing unit for printing an image formed on the surface of the photosensitive drum on paper;
When the image is printed on a predetermined number of sheets or more by the printing unit, the cleaning member is moved along the direction in which the discharge wire extends so that the poorly charged portion of the corona discharge is formed on the surface of the photosensitive drum. Forming the toner on the surface of the photosensitive drum and attaching the toner to the poorly charged portion of the photosensitive drum, and forming the toner in the poorly charged portion with the blade and the surface of the photosensitive drum. The image forming apparatus according to claim 1, wherein the image forming apparatus is supplied to a gap. A printing unit for printing an image formed on the surface of the photosensitive drum on paper;
When the printing time on the paper by the printing unit is equal to or longer than a predetermined time, the cleaning member is moved along the direction in which the discharge wire extends to cause a defective charging portion of the corona discharge on the surface of the photosensitive drum. And supplying the toner to the surface of the photosensitive drum to attach the toner to the poorly charged portion of the photosensitive drum, and forming the toner of the poorly charged portion with the blade and the surface of the photosensitive drum. The image forming apparatus according to claim 1, wherein the image forming apparatus supplies the gap to the gap.   After replacing the constituent members constituting the image forming apparatus, the cleaning member is moved along the direction in which the discharge wire extends to form a poorly charged portion of the corona discharge on the surface of the photosensitive drum, and the photosensitive member The toner is supplied to the surface of the drum so that the toner adheres to the poorly charged portion of the photosensitive drum, and the toner in the poorly charged portion is supplied to a gap formed by the blade and the surface of the photosensitive drum. The image forming apparatus according to claim 1. A transfer roller for transferring a toner image formed on the surface of the photosensitive drum to the paper;
5. The image forming apparatus according to claim 1, wherein a voltage having the same polarity as the toner attached to the surface of the photosensitive drum is applied to the transfer roller.

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