JP2005338530A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To electrifier so as to generate no looseness in the crossing axial direction, in the rotating direction of a photoreceptor drum. <P>SOLUTION: In the image forming apparatus, the photoreceptor drum 2 is mounted rotatably on an image forming apparatus body 1, and the electrifier 33 is arranged at a prescribed interval from the photoreceptor drum 2. A positioning member 5 for the electrifier, mounted on the electrifier 33, positions the electrifier 33 on the image forming apparatus body 1. An urging member 16, arranged in between the positioning member 5 for the charging body and the image forming apparatus body 1 urges the positioning member 5 for the electrifier about a shaft different in the rotating shaft direction of the photoreceptor drum 2 to the image forming apparatus body 1. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus such as a copying machine, a printer, and a facsimile apparatus using an electrophotographic system.

In general, an image forming apparatus using an electrophotographic system includes an image forming apparatus main body, a photosensitive drum, and a charging device. The photosensitive drum is rotatably mounted on the main body of the image forming apparatus, and is rotated by a driving unit. This photosensitive drum has a photosensitive layer on the outer peripheral surface. The charging device has a charger that uniformly charges the outer peripheral surface of the photosensitive drum. As the charger, a non-contact type charger that is arranged at a predetermined interval from the photosensitive drum and charges the photosensitive drum is known. When the photosensitive drum is charged using such a non-contact type charger, the surface potential of the photosensitive drum is greatly influenced by the interval between the charger and the surface of the photosensitive drum. If there is a left / right difference in the distance between the charger and the surface of the photosensitive drum in the axial direction of the photosensitive drum, a difference in the surface potential of the photosensitive drum will occur, resulting in the density of the image formed on the photosensitive drum. There may be a difference between the left and right. Therefore, in order to minimize the difference in image density in the axial direction of the photosensitive drum, an adjustment unit that can adjust the distance between the photosensitive drum and the charger may be used. As such an adjusting means, an image forming apparatus including a support member that supports one end of the charger and a screw that adjusts the position of the support member has been proposed (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 2002-6593 (FIG. 3)

  In an image forming apparatus having a conventional adjusting means, the distance between the charger and the photosensitive drum can be adjusted by adjusting the position of the support member by rotating the screw of the image forming apparatus main body from above with a screwdriver or the like. ing. However, since an operation unit or the like is provided above the screw, in order to engage the driver or the like with the screw, it is necessary to once pull out the image forming unit provided with the charger from the image forming apparatus main body. Further, the adjustment of the distance between the charger and the photosensitive drum cannot be normally performed in one operation, and the adjustment needs to be repeated many times. For this reason, during the adjustment work, the image forming unit has to be pulled out from the image forming apparatus many times, and the adjustment work is troublesome. Furthermore, since the accuracy of adjusting the distance between the charger and the photosensitive drum is determined by the pitch of the screw, a special screw must be used to improve the adjustment accuracy, and fine adjustment using such a screw is required. Was very poor for the operator.

  In order to solve such problems, the inventor disclosed in Japanese Patent Application No. 2004-020155, an image forming apparatus having an adjusting unit that can quickly adjust the balance (left-right difference) of the surface potential of the photosensitive drum. Proposed. In this image forming apparatus, the moving member is fixed to the charger. The moving member is formed with a plurality of protrusions, and the image forming apparatus main body is formed with a plurality of long holes in the vertical direction in which the plurality of protrusions can be fitted. The protrusion of the moving member is slidable in the vertical direction within the elongated hole of the image forming apparatus main body. Thus, the moving member is slidable in the vertical direction with respect to the image forming apparatus main body. In this state, the distance between the charger and the photosensitive drum can be adjusted by moving the moving member in the vertical direction by the adjusting means. The adjusting means includes a plurality of gears, an adjusting panel for operating the plurality of gears, and a shaft portion that is moved up and down by the plurality of gears. In this adjustment means, when the operator rotates the adjustment panel in the forward direction, the plurality of gears rotate in conjunction with each other, and the shaft portion pushes the moving member upward from below. On the other hand, a compression coil spring is disposed between a contact plate provided in the main body of the image forming apparatus and a spring receiving portion provided in the moving member (positioning member for charger), and the moving member is moved by the compression coil spring. The image forming apparatus main body is biased downward. In this state, when the operator reversely rotates the adjustment panel of the adjusting means, the plurality of gears reversely rotate in conjunction with each other, and the shaft portion moves downward from above. At this time, since the moving member is urged downward with respect to the image forming apparatus main body by the compression coil spring, the moving member is pushed down from the upper side to the lower side as the shaft portion moves from the upper side to the lower side. Thus, by moving the moving member fixed to the charger by the adjusting means up and down, the charger can be moved up and down, and the operator can quickly balance the surface potential of the photosensitive drum (difference between right and left). Can be adjusted.

  In such an image forming apparatus, in order to mount the moving member on the image forming apparatus main body, a long hole for fitting the protrusion of the moving member is formed in the image forming apparatus main body. When a long hole is formed in the image forming apparatus main body, in general, in consideration of a dimensional error in manufacturing the moving member or the image forming apparatus main body, the long hole in the direction orthogonal to the interval adjustment direction (vertical direction) is used. The dimension is often formed to be larger than the dimension of the protrusion in the direction orthogonal to the interval adjustment direction (vertical direction). When the long holes are formed in this way, when adjusting the interval between the charger and the photosensitive drum, the moving member, that is, the charger, excludes the interval adjustment direction (vertical direction) with respect to the image forming apparatus body. There is a risk of rattling in the axial direction that is different from the rotational axis direction of the photosensitive drum. That is, there is a possibility that the distance between the charger and the surface of the photosensitive drum is slightly changed. Note that the moving member is always urged downward with respect to the image forming apparatus main body by a compression coil spring disposed between the contact plate provided on the image forming apparatus main body and the spring receiving portion provided on the moving member. Therefore, the moving member, that is, the charger is considered so as not to rattle in the interval adjustment direction (vertical direction) with respect to the image forming apparatus main body.

  SUMMARY OF THE INVENTION An object of the present invention is to prevent the charger from rattling in the axial direction that is different from the rotational axis direction of the photosensitive drum.

  An image forming apparatus according to a first aspect includes an image forming apparatus main body, a photosensitive drum, a charging device, and an urging member. The photosensitive drum is rotatably mounted on the image forming apparatus main body. The charging device includes a charger and a charger positioning member. The charger is for charging the photosensitive drum, and is arranged at a predetermined interval from the photosensitive drum. The charger positioning member is attached to the charger and positions the charger on the main body of the image forming apparatus. The urging member is disposed between the charger positioning member and the image forming apparatus main body. The biasing member biases the charger positioning member around an axis different from the rotation axis direction of the photosensitive drum with respect to the image forming apparatus main body.

  In this image forming apparatus, the photosensitive drum is rotatably mounted on the image forming apparatus main body, and the charger is disposed at a predetermined interval from the photosensitive drum. The charger positioning member mounted on the charger positions the charger on the image forming apparatus main body. An urging member disposed between the charger positioning member and the image forming apparatus main body applies the charger positioning member to the image forming apparatus main body about an axis different from the rotation axis direction of the photosensitive drum. It is fast.

  Here, the urging member urges the charger positioning member around the axis different from the rotation axis direction of the photosensitive drum with respect to the image forming apparatus main body. Thus, even if there is a gap in the axial direction that is different from the rotation axis direction of the photosensitive drum between the charger positioning member and the image forming apparatus main body, the gap is closed by the biasing force of the biasing member. It is possible to prevent the charging member positioning member from rattling in the axial direction which is different from the rotational axis direction of the photosensitive drum. That is, it is possible to prevent the charger from rattling in the axial direction that is different from the rotational axis direction of the photosensitive drum.

  In an image forming apparatus according to a second aspect, in the image forming apparatus according to the first aspect, the charger positioning member has at least one protrusion. Further, the image forming apparatus main body has a through hole into which the protrusion of the positioning member can be fitted. Here, the charger positioning member is fixed to the image forming apparatus main body by at least one screw member in a state where the protrusion is fitted in the through hole of the image forming apparatus main body. In this case, the charging member positioning member has a protruding portion of the charging member positioning member fitted in the through-hole of the image forming apparatus main body, and a gap that may be generated between the charging member positioning member and the image forming apparatus main body is a biasing member. Since it is fixed to the main body of the image forming apparatus by at least one screw member in a state where it is closed by the biasing force, the charger positioning member is positioned so that the charging member positioning member does not rattle in the axial direction that is different from the rotational axis direction of the photosensitive drum. The member can be fixed to the image forming apparatus main body.

  In the image forming apparatus according to claim 3, in the image forming apparatus according to claim 2, the urging member rotates the charging member positioning member in the tightening rotation direction of the screw member, and tightens the protrusion of the charging member positioning member. It is made to contact | abut to the internal peripheral surface of the through-hole of a rotation direction. In this case, the protrusion of the charger positioning member is brought into contact with the inner peripheral surface of the through hole facing the tightening rotation direction of the screw member by the urging force of the urging member. The screw member can be rotated and tightened in contact with the peripheral surface. As a result, when the charging member positioning member is fixed to the image forming apparatus main body by the screw member, the charging member positioning member is image-formed so that the charging member positioning member does not rattle in the axial direction that is different from the rotation axis direction of the photosensitive drum. It can be securely fixed to the apparatus body.

  An image forming apparatus according to a fourth aspect is the image forming apparatus according to any one of the first to third aspects, further comprising an interval adjusting unit. The interval adjusting means is for adjusting the interval between the photosensitive drum and the charger. The interval adjusting means engages with the charger positioning member and moves the charging device in a direction away from the photosensitive drum and a direction close to the photosensitive drum.

  In this image forming apparatus, the interval adjusting unit is engaged with the charger positioning member, and the charging device having the charger positioning member is moved in a direction away from the photosensitive drum and a direction close to the photosensitive drum. Even when the image forming apparatus includes such an interval adjusting unit, the urging member urges the charger positioning member in the axial direction that is different from the rotation axis direction of the photosensitive drum with respect to the image forming apparatus main body. By doing so, it is possible to prevent the charger from rattling in the axial direction that is different from the rotational axis direction of the photosensitive drum.

  According to the present invention, the urging member urges the charger positioning member in the axial direction which is different from the rotation axis direction of the photosensitive drum with respect to the image forming apparatus main body. Thus, even if there is a gap in the axial direction that is different from the rotation axis direction of the photosensitive drum between the charger positioning member and the image forming apparatus main body, the gap is closed by the biasing force of the biasing member. It is possible to prevent the charging member positioning member from rattling in the axial direction which is different from the rotational axis direction of the photosensitive drum. That is, it is possible to prevent the charger from rattling in the axial direction that is different from the rotational axis direction of the photosensitive drum.

[Overview of image forming apparatus]
FIG. 1 is a schematic cross-sectional view of a tandem color printer which is an embodiment of an image forming apparatus. The image forming apparatus is transported by image forming units 102M, 102Y, 102C, and 102B for each color for forming a color image, toner containers 103M, 103Y, 103C, and 103B for each color, and a transport belt 104 that transports paper. First to fourth transfer rollers 105M, 105Y, 105C, and 105B for transferring the toner images of the respective colors to the paper, and a paper feed mechanism 106 that feeds the paper to the image forming units 102M, 102Y, 102C, and 102B A fixing unit 107 for fixing the toner image transferred onto the paper and a discharge unit 108 are provided.

  The image forming units 102M, 102Y, 102C, and 102B form toner images of magenta, yellow, cyan, and black, respectively, and are sequentially arranged in the horizontal direction along the conveyance belt 104 from the upstream side in the conveyance direction of the paper. Has been placed. Each of these image forming units 102M, 102Y, 102C, and 102B has a photosensitive drum 2 having a photosensitive layer made of amorphous silicon or the like as an image carrier, and a charging device 3 is provided around each photosensitive drum 2. The exposure unit 112 and the developing device 113 are sequentially arranged.

  The conveyor belt 104 is circulated and driven between a driving roller 120 and a driven roller 121. The transport belt 104 sucks and transports the paper transported from the paper feed mechanism 106 via the paper feed transport path 122 in a substantially horizontal direction.

  The first to fourth transfer rollers 105M, 105Y, 105C, and 105B are disposed so as to face the photosensitive drums 2 of the image forming units 102M, 102Y, 102C, and 102B via the transport belt 104. Each of the first to fourth transfer rollers 105M, 105Y, 105C, and 105B is movable between an upper transfer position and a lower release position by a solenoid 123. Here, when the first to fourth transfer rollers 105M, 105Y, 105C, and 105B are moved upward and disposed at the transfer position, the sheet on the conveyance belt 104 is in contact with the photosensitive drum 2. On the other hand, when the first to fourth transfer rollers 105M, 105Y, 105C, and 105B move downward and are disposed at the release position, the sheet on the conveyor belt 104 and the photosensitive drum 2 are separated from each other.

  The paper feed conveyance path 122 includes a guide member serving as a conveyance guide and a plurality of roller pairs. On the most downstream side of the paper feed conveyance path 122, toner image formation and paper conveyance are performed. A registration roller pair 125 for synchronization is provided. A suction roller 126 is provided between the registration roller pair 125 and the first transfer roller 105M. In this example, the suction roller 126 is disposed above the driven roller 121 on which the conveyance belt 104 is hung, so as to face the driven roller 121. At this position, the suction roller 126 applies a bias voltage for suction to the leading end portion or the entire surface of the paper, so that the paper is attracted to the transport belt 104.

  The fixing unit 107 includes a heating roller having a heater therein and a pressure roller pressed against the heating roller. A paper discharge conveyance path 127 is provided between the fixing unit 107 and the discharge unit 108. Similarly to the paper feed conveyance path 122, the paper discharge conveyance path 127 includes a guide member and a plurality of roller pairs. The discharge unit 108 is formed on the upper surface of the apparatus, and the sheet that has passed through the fixing unit 107 is conveyed upward via the sheet discharge conveyance path 127 and discharged to the upper surface of the apparatus.

[Charging device and members and means related to charging device]
2 to 5 are schematic diagrams for explaining the charging device 3 arranged around the photosensitive drum 2, the biasing members 15 and 16 and the interval adjusting means 4 related to the charging device 3. FIG.

  The photosensitive drum 2 is rotatably mounted on the image forming apparatus main body 1 of the image forming apparatus.

  The charging device 3 is movable in the adjustment direction A with the one end portion as a fulcrum. Here, the other end side of the charging device 3 is disposed on the front panel side of the color printer. The charging device 3 can be inserted into and removed from the image forming apparatus main body 1 as an image forming unit by opening the front panel of the color printer.

  As shown in FIG. 2, the charging device 3 includes a charger 33 and a charger positioning member 5. The charger 33 is for charging the photosensitive drum 2, and is arranged at a predetermined interval from the photosensitive drum 2. The charger 33 has a shield case 6 and a charge wire W stretched in the shield case 6. The shield case 6 includes a case body 6a and an end block 6b. The case body 6a is formed in a U-shaped box shape having an opening on the photosensitive drum 2 side so that the corona discharge of the charge wire W can be discharged only in the direction of the photosensitive drum 2 from the opening surface. It has become. The case body 6a is formed by molding a conductive material such as aluminum, iron or stainless steel into a U-shaped cross section. The end block 6b is attached to both ends in the longitudinal direction of the case body 6a. The charge wire W is formed of, for example, a minute diameter tungsten, and is stretched in the longitudinal direction while being insulated from the shield case 6. Further, when a high voltage is applied to the charge wire W, corona discharge is generated.

  As shown in FIGS. 2 to 4, the charger positioning member 5 is for positioning the charger 33 on the image forming apparatus main body 1, and is attached to the charger 33. For example, the charger positioning member 5 is fixed to the end block 6b via the fixing member 7 with the three first screws 8. Accordingly, the charger positioning member 5 can move within a predetermined range together with the charger 33 with respect to the image forming apparatus main body 1. The charger positioning member 5 includes a flange portion 9 formed in a substantially rectangular plate shape, a mounting portion 10 protruding from the flange portion 9, a contact portion 18 provided below the mounting portion 10, a flange The first and second spring receiving portions 13 and 14 provided in the portion.

  As shown in FIGS. 3 and 4, the flange portion 9 is formed in a substantially rectangular plate shape so as to spread from the mounting portion 10 in the left-right and downward directions. The flange portion 9 is provided with at least one protrusion portion 12. For example, as shown in FIG. 4, two protrusions 12 are provided on the left side of the flange 9, and one protrusion 12 is provided on the right end. These protrusions 12 are fitted into first through holes 22 formed in the image forming apparatus main body 1 and are movable in the interval adjustment direction A with respect to the image forming apparatus main body 1. Specifically, these protrusions 12 are fitted into elongated holes 22 formed in the image forming apparatus main body 1 and are movable in the interval adjustment direction A with respect to the image forming apparatus main body 1.

  As shown in FIG. 4, first and second spring receiving portions 13 and 14 are formed at the substantially central portion of the lower portion of the flange portion 9 and the left end portion of the flange portion 9. The first spring receiving portion 13 includes a bottom portion 13a with which one end (lower end portion) of a first coil spring 15 to be described later contacts, a protruding portion 13c fitted to the inner peripheral portion of the first coil spring 15, and both sides of the bottom portion 13a. The side portion 13b is formed. The second spring receiving portion 14 includes a bottom portion 14a with which one end (lower end portion) of a second coil spring 16 to be described later contacts, and a first locking portion 14c with which one end (lower end portion) of the second coil springs 15 and 16 is engaged. And side portions 14b formed on both sides of the bottom portion 14a. A first locking hole is formed in the first locking portion 14c.

  A female screw hole 24 is formed between the two protrusions 12 provided on the left side of the flange portion 9 as shown in FIG. The second screw 25 is inserted into the second through hole 23 formed in the image forming apparatus main body 1 at a position facing the female screw hole 24, and the second screw 25 is screwed into the female screw hole 24 formed in the flange portion. By combining, the flange portion 9 is fixed to the image forming apparatus main body 1. Further, a plate-like second contact plate 21 formed integrally with the image forming apparatus main body 1 is disposed above the second spring receiving portion 14 formed at the left end portion of the flange portion 9. The lower surface of the two contact plate 21 faces the second spring receiving portion 14. A second locking portion 21 a that locks the other ends (upper end portions) of the second coil springs 15 and 16 is formed on the lower surface of the second contact plate 21. A second locking hole is formed in the second locking portion 21a.

  The attachment portion 10 and the contact portion 18 provided on the lower side of the attachment portion 10 are formed in a T shape in a plan view of FIG. The mounting portion 10 has three screw holes 10a penetrating in the vertical direction. A first screw 8 is inserted into each of the three screw holes 10a, and the first screw 8 is screwed into a fixing member 7 fixed to the end block 6b. As a result, the charger positioning member 5 is fixed to the fixing member 7, and the charger positioning member 5 is moved in the vertical direction together with the charger 33 by the interval adjusting means 4 described later. The abutting portion 18 is provided at the center in the left-right direction of the charger positioning member 5 below the attachment portion 10. The contact portion 18 is formed integrally with the lower surface of the mounting portion 10 and the wall portion 10b formed downward from the lower surface. The contact portion 18 is formed to have a thickness dimension larger than the diameter of a shaft portion 31 to be described later, and a flat contact surface 18 a is provided on the lower end surface of the contact portion 18. . As shown in FIG. 2, a plate-like first contact plate 20 formed integrally with the image forming apparatus main body 1 is disposed between the contact portion 18 and the first spring receiving portion 13. The lower surface of the first contact plate 20 faces the first spring receiving portion 13.

  The biasing member includes a first biasing member 15 and a second biasing member 16. The first and second urging members 15 and 16 are, for example, first and second coil springs 15 and 16, and are disposed between the charger positioning member 5 and the image forming apparatus main body 1. As shown in FIG. 2, the first coil spring 15 is disposed between the charger positioning member 5 and the image forming apparatus main body 1 between the one end portion of the photosensitive drum 2 and the interval adjusting unit 4. Specifically, the first coil spring 15 is mounted in an elastically compressed state between the first contact plate 20 and the first spring receiving portion 13. At this time, the upper end portion of the first coil spring 15 is in contact with the lower surface of the first abutting plate 20, and the lower end portion of the first coil spring 15 is in contact with the bottom portion 13 a of the first spring receiving portion 13 and fitted into the protrusion 13 c. Has been. In this state, the charging member positioning member 5 is urged by the repulsive force of the first coil spring 15 in the downward direction of FIG.

  As shown in FIG. 3, the second coil spring 16 is disposed between the charger positioning member 5 and the image forming apparatus main body 1 on the left outer side of the protrusion 12 formed on the charger positioning member 5. Yes. The second coil spring 16 biases the charger positioning member 5 about an axis different from the rotation axis direction of the photosensitive drum 2 with respect to the image forming apparatus main body 1. Specifically, the second coil spring 16 is provided on the left outer side of the two protrusions 12 provided on the left side of the flange portion 9 and the second contact plate 21 formed on the image forming apparatus main body 1 and the charger. It is mounted in an elastically stretched state between the second spring receiving portion 14 formed on the positioning member 5. At this time, the upper end portion of the second coil spring 16 is inserted into the second locking hole of the second locking portion 21 a on the lower surface of the second backing plate 21, and the lower end portion of the second coil spring 16 is the bottom portion of the second spring receiving portion 14. It is inserted through the first locking hole of the first locking portion 14c of 14a. In this state, the charging member positioning member 5 is rotated in the tightening rotation direction of the second screw 25 by the tensile force of the second coil spring 16, and the two protrusions 12 provided on the left side of the flange portion 9 are tightened and rotated. It is made to contact | abut to the internal peripheral surface of the 1st through-hole 22 of a direction. Here, the tightening rotation direction of the second screw 25 is a clockwise direction. Specifically, due to the biasing force of the second coil spring 16 mounted between the second contact plate 21 and the second spring receiving portion 14, the charger positioning member 5 causes the shaft portion 31 of the interval adjusting means 4 to be described later. It is rotated clockwise with the contact surface 18a with which one end of the contact is made as a fulcrum. Here, an axis that rotates the charging member positioning member 5 clockwise, that is, an axis that passes through a portion serving as a fulcrum of the contact surface 18 a is an axis different from the rotation axis direction of the photosensitive drum 2. Thus, each of the two protrusions 12 provided on the left side of the flange portion 9 can be brought into contact with the inner peripheral surface of the first through hole 22 in the tightening rotation direction of the second screw 25. That is, the protrusion 12 above the left side can be brought into contact with the first through hole 22, that is, the inner right side surface of the long hole 22, and the protrusion 12 below the left side can be brought into contact with the first through hole 22, ie, the long hole 22. It can be brought into contact with the inner peripheral left side surface.

  The interval adjusting unit 4 is for adjusting the interval between the photosensitive drum 2 and the charger 33. With this distance adjusting means 4, the operator can easily adjust the distance between the photosensitive drum 2 and the charger 33 from the end face side (front panel side of the image forming apparatus) of the image forming unit. The interval adjusting means 4 is engaged with the charger positioning member 5. The interval adjusting unit 4 moves the charging device 3 in a direction away from the photosensitive drum 2 and a direction close to the photosensitive drum 2 (interval adjusting direction A).

  As shown in FIGS. 2, 3, and 5, the interval adjusting means 4 includes a casing 50, a shaft portion 31, a first gear member 30, a second gear member 40, a support mechanism 45, and a positioning member. 51. The casing 50 is formed in a substantially box shape, and accommodates the shaft portion 31, the first gear member 30, the second gear member 40, the support mechanism 45, and the positioning member 51 inside. The casing 50 is attached to the image forming apparatus main body 1 by an engaging claw portion 52 formed in the image forming apparatus main body 1 that can be engaged with the casing 50 (see FIG. 2). A support portion 53 that rotatably supports the lower end portion 31 b of the shaft portion 31 is formed on the inner bottom surface portion of the casing 50. The support portion 53 is formed in a ring shape and has a required height in the vertical direction of FIG. In addition, a housing part 50 a for housing the positioning member 51 is formed in the upper part of the casing 50.

  The shaft portion 31 has an axial center directed in the adjustment direction A, and is formed in a columnar shape that is long in the rotation axis direction of the first gear member. The lower end portion 31 b of the shaft portion 31 is rotatably supported by the support portion 53 of the casing 50, and the upper end portion 31 a of the shaft portion 31 protrudes from the upper portion of the casing 50. The upper end portion 31 a of the shaft portion 31 has a flat upper end surface, and supports the charger positioning member 5 by contacting the contact surface 18 a of the charger positioning member 5. The upper end surface of the upper end portion 31a of the shaft portion 31 is a contact surface of the charger positioning member 5 by a first coil spring 15 to be described later that biases the charger positioning member 5 in the direction toward the gap adjusting means 4 (downward). It is always in contact with 18a. Further, on the outer peripheral surface of the shaft portion 31, a male screw portion 31 c is formed in a range from the upper end portion 31 a to the upper end surface of the first gear member 30.

  The first gear member 30 is formed integrally with the shaft portion 31. The first gear member has a diameter larger than the diameter of the second gear member 40. The outer peripheral portion of the first gear member is a helical gear formed at an angle of 45 °. The second gear member 40 meshes with the first gear member 30 in a state where the axis is orthogonal to the adjustment direction A. The support mechanism 45 is for supporting the first gear member 30 so as to be slidable in the adjustment direction A when the first gear member 30 rotates.

  The second gear member 40 is rotatably supported in the casing 50, and an adjustment panel 42 is fixed to one end (the right end in FIG. 2). On the outer peripheral surface of the second gear member 40, a 45 ° hubus gear that can mesh with the hubus gear formed on the outer peripheral surface of the first gear member 30 is formed. Further, the number of teeth of the second gear member 40 is larger than the number of teeth of the first gear member 30, and the amount of rotation of the first gear member 30 can be finely adjusted by rotating the second gear member 40. it can. This facilitates fine adjustment of the slide amount of the shaft portion 31. The adjustment panel 42 is formed in a circular plate shape having substantially the same thickness as the casing 50. As shown in FIGS. 2 and 5, the adjustment panel 42 is attached to the second gear member 40 so that the front surface is substantially flush with the front surface of the casing 50. As shown in FIG. 5, on the front side of the adjustment panel 42, a cross-shaped recess 42a is formed at the center.

  The positioning member 51 is formed in a plate shape having a predetermined thickness, and a hole 51a for inserting the shaft portion 31 is formed at the center thereof. A female screw part 51 b is formed in the hole 51 a, and the female screw part 51 b is screwed into the male screw part 31 c of the shaft part 31. The pitch of the male screw portion 31c and the female screw portion 51b is formed so that the sliding amount of the shaft portion 31 and the sliding amount of the first gear member 30 due to the meshing of the first and second gear members 30 and 40 coincide. . In a state where the positioning member 51 is housed in the housing portion 50 a of the casing 50, the positioning member 51 cannot move in the adjustment direction A. That is, the thickness of the positioning member 51 is formed to be substantially the same as the height in the vertical direction inside the accommodating portion, and is almost between the upper surface and the lower surface of the positioning member 51 and the inner upper surface and the inner lower surface of the accommodating portion. There is no gap.

  The operator can adjust the slide amount of the shaft portion 31 by rotating the adjustment board by fitting a driver or the like into the recess 42 a of the adjustment board 42. Specifically, when the operator rotates the adjustment panel 42, the second gear member 40 rotates according to the amount of rotation of the adjustment panel 42. Then, the first gear member 30 having the shaft portion 31 that is different from the rotation shaft of the second gear member 40 rotates. Then, the first gear member 30 slides in the adjustment direction A while rotating, and the shaft portion 31 moves in the adjustment direction A. At this time, since the upper end portion 31a of the shaft portion 31 is in contact with the contact surface 18a of the contact portion 18 of the charger positioning member 5, the charger positioning member 5 is moved by rotating the adjustment panel 42. It is moved in the adjustment direction A (vertical direction in FIGS. 2 and 3). Thereby, the interval between the photosensitive drum 2 and the charger 33 is adjusted.

  In the present embodiment, the second coil spring 16 biases the charger positioning member 5 around an axis different from the rotation axis direction of the photosensitive drum 2 with respect to the image forming apparatus main body 1. As a result, even if there is a gap in the axial direction between the charging member positioning member 5 and the image forming apparatus main body 1 that is different from the rotation axis direction of the photosensitive drum 2, this gap is caused by the biasing force of the second coil spring 16. Since the charging member positioning member 5 is closed, the charging member positioning member 5 can be prevented from rattling in the axial direction which is different from the rotational axis direction of the photosensitive drum 2. That is, it is possible to prevent the charger 33 from rattling in the axial direction that is different from the rotational axis direction of the photosensitive drum 2.

  Further, the charging member positioning member 5 has the protrusion 12 of the charging member positioning member 5 fitted in the first through hole 22 of the image forming apparatus main body 1, and the charging member positioning member 5 is interposed between the charging member positioning member 5 and the image forming apparatus main body 1. Since the gap that may be generated is closed to the image forming apparatus main body 1 by the second screw 25 in a state where the gap is closed by the urging force of the second coil spring 16, the charger positioning member 5 is misaligned in the rotation axis direction of the photosensitive drum 2. The charger positioning member 5 can be fixed to the image forming apparatus main body 1 so as not to rattle in the axial direction.

  Further, due to the urging force of the second coil spring 16, the two protrusions 12 on the left side of the charger positioning member 5 are brought into contact with the inner peripheral surface of the first through hole 22 facing the tightening rotation direction of the second screw 25. Therefore, the second screw 25 can be rotated and tightened in a state where the two protrusions 12 on the left side of the charger positioning member 5 are in contact with the inner peripheral surface of the first through hole 22. As a result, when the charger positioning member 5 is fixed to the image forming apparatus main body 1 by the second screw 25, the charger positioning member 5 is charged so as not to rattle in the axial direction that is different from the rotational axis direction of the photosensitive drum 2. The device positioning member 5 can be securely fixed to the image forming apparatus main body 1.

[Other Embodiments]
(A) In the above embodiment, an example in which the image forming apparatus is a color printer has been described. However, the present invention can also be applied to an image forming apparatus such as a copying machine, a printer, or a facsimile.

  (B) In the said embodiment, although the example in case the 2nd coil spring 16 is arrange | positioned at the left end part of the flange part 9 was shown, the position which arrange | positions the 2nd coil spring 16 is not limited to the said embodiment, and charging Any method may be used as long as the protrusion 12 of the device positioning member 5 can be brought into contact with the inner peripheral surface of the first through hole 22 facing the rotational direction of the second screw 25. For example, the second contact plate 21 and the second spring receiving portion 14 may be provided at the right end portion of the flange portion 9, and the second coil spring 16 may be disposed at the right end portion of the flange portion 9. In this case, the second coil spring 16 is disposed between the second contact plate 21 and the second spring receiving portion 14 in an elastically compressed state. Thereby, the effect similar to the said embodiment can be acquired.

  (C) In the above embodiment, an example in which the first coil spring 15 and the second coil spring 16 are disposed between the charger positioning member 5 and the image forming apparatus main body 1 has been described. If the upper end surface of the upper end portion 31a of the shaft portion 31 can always be brought into contact with the contact surface 18a of the charger positioning member 5, the first coil spring 15 is not necessarily arranged. For example, in the above-described embodiment, the second coil spring 16 rotates the charger positioning member 5 clockwise with the contact surface 18a with which one end of the shaft portion 31 of the distance adjusting unit 4 contacts as a fulcrum. . In consideration of this, a force is acting on the contact surface 18a serving as a fulcrum in the direction toward the distance adjusting means 4, so that the upper end surface of the upper end portion 31a of the shaft portion 31 is connected to the positioning member 5 for the charger. The contact surface 18a can always be in contact with the contact surface 18a. If the spring constant of the second coil spring 16 is relatively large so that such a state can be stably maintained, the first coil spring 15 can be formed by the second coil spring 16 without necessarily arranging the first coil spring 15. Can play the role of

1 is a schematic cross-sectional configuration diagram of a color printer in which this embodiment is adopted. FIG. 3 is a cross-sectional view of the vicinity of the adjusting unit of the image forming apparatus as viewed from the side. FIG. 3 is a cross-sectional view taken along the line BB in FIG. The perspective view of a moving member. The perspective view of a preparation means.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus main body 2 Photoconductor 3 Charging apparatus 33 Charger 4 Space | interval adjustment means 5 Charging device positioning member 16 2nd coil spring (biasing member)
12 Protrusion 22 Long hole, 1st through hole (through hole)
25 Second screw (screw member)

Claims (4)

An image forming apparatus main body;
A photosensitive drum rotatably mounted on the image forming apparatus main body;
A charging device that is disposed at a predetermined interval from the photosensitive drum and has a charger for charging the photosensitive drum, and a charger positioning member that is mounted on the charger and positions the charger on the image forming apparatus main body. Equipment,
The charging member positioning member is disposed between the charging member positioning member and the image forming apparatus main body, and biases the charging member positioning member about an axis different from the rotation axis direction of the photosensitive drum with respect to the image forming apparatus main body. A force member;
An image forming apparatus comprising: The charger positioning member has at least one protrusion, and the image forming apparatus main body has a through hole into which the protrusion can be fitted.
2. The image forming apparatus according to claim 1, wherein the charger positioning member is fixed to the image forming apparatus main body with at least one screw member in a state where the protrusion is fitted in the through hole.   The biasing member rotates the charging member positioning member in a tightening rotation direction of the screw member, and abuts the protrusion on an inner peripheral surface of the through hole in the tightening rotation direction. The image forming apparatus described. A direction for adjusting a distance between the photosensitive drum and the charger, and a direction in which the charging device is separated from the photosensitive drum by being engaged with the charging member positioning member and a direction in which the charging device is close to the photosensitive drum 4. The image forming apparatus according to claim 1, further comprising an interval adjusting unit that is moved to each other.

Images