JP5293317B2 - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of arranging a photoreceptor unit and a developing unit with a high degree of position precision. <P>SOLUTION: A pressure-welding member 15 of the developing unit 10 is pressure-welded to a member to be pressure-welded 25 of the photoreceptor unit 20. In this case, the moving direction D is deviated from a line L that connects the center axis 21a of a photoreceptor drum 21 and the center axis 11a of a developing roller 11. The moving direction D is in one of the two regions divided by the line L that connects the center axis 21a of the photoreceptor drum 21 and the center axis 11a of the developing roller 11. The region is on the side where a section in which the photoreceptor unit 20 faces the developing unit 10 is located. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to an image forming apparatus. More specifically, the present invention relates to an image forming apparatus that improves the positional accuracy of the relative position between the developing unit and the photosensitive unit.

  In an image forming apparatus, the positional relationship between a photosensitive drum and a developing member such as a developing roller is important. This is because the gap between the photosensitive member and the developing member directly affects the developing electric field. Therefore, if the accuracy of the parallelism between the photosensitive member and the developing member is low, the distance from the developing member is wide at one end in the longitudinal direction of the photosensitive member (the width direction of the image) and narrow at the other end. It will be. This may cause a difference in density between one end and the other end in the width direction of the image.

  For example, Japanese Patent Application Laid-Open No. H10-228707 discloses an improvement in positional accuracy between the photosensitive drum and the developing member. In Patent Document 1, positioning is performed by inserting into a centering shaft, connecting shaft couplings, or the like (see paragraphs [0050] to [0052] of Patent Document 1).

JP 2002-123063 A

  By the way, conventionally, a photosensitive member and a developing member may be detachable as a single process cartridge (see Patent Document 1). However, the lifetimes of the photosensitive member and the developing member are different. For this reason, the photosensitive member and the developing member have become independent units. When separated as described above, there arises a problem that it is difficult to attach the photosensitive unit and the developing unit with high positional accuracy. This is because if the reproducibility of the gap between the photosensitive member and the developing member is poor, the density of the image changes before and after the developing unit is attached or detached.

  In the invention described in Patent Document 1, it is possible to improve the positional accuracy of the image forming apparatus main body and the photosensitive unit, and the image forming apparatus main body and the developing unit. However, the relative positions of the photosensitive unit and the developing unit cannot be determined with high accuracy. For this reason, when the photosensitive unit and the developing unit are independent units, a system in which one unit is pressed against the other unit may be used. Thereby, the positional accuracy of the relative position between the photosensitive member and the developing member is improved to some extent. But that is not always enough.

  If the reproducibility of the magnitude and direction of the force that presses the developing unit against the photosensitive unit is poor, the positional relationship between the photosensitive unit and the developing unit may change before and after replacement of the unit. Further, when the image forming apparatus is repeatedly used, the relative positional relationship between the photosensitive unit and the developing unit may change. This is because the force applied when opening and closing the toner discharge port shutter (see 17 in FIG. 5) provided in the developing unit in the direction of the arrow in FIG. 5 is transmitted to the press contact portion. However, the developing device described in Patent Document 1 does not take into account a positional shift due to opening / closing of the discharge port shutter. Therefore, such a problem cannot be solved.

  The present invention has been made to solve the above-described problems of the prior art. That is, an object of the present invention is to provide an image forming apparatus in which the photosensitive unit and the developing unit can be arranged with high positional accuracy.

  The image forming apparatus of the present invention, which has been made for the purpose of solving this problem, includes a photosensitive unit having a photosensitive member and a developing unit having a developing member for applying a developer to the photosensitive member so as to be detachable from the main body. In the image forming apparatus, a support member that causes the developing member to face the photoconductor with a gap in a state where both the photoconductor unit and the developing unit are mounted on the main body, and at least a portion that is provided on the photoconductor unit and faces the developing unit And a pressure contact member having a cylindrical surface coaxial with the photosensitive member, and a rotation unit mounted on the developing unit so as to be rotatable with respect to the rotation axis of the development member, and pressed against the pressure contact member by the support member, At least the surface of the portion to be pressed against the member to be pressed has a pressing member having a cylindrical surface coaxial with the developing member. Of the cylindrical surface of the member to be pressed and the radius of the cylindrical surface of the member to be pressed are larger than the sum of the radius of the developing member and the radius of the photosensitive member, and the center axis of the photosensitive member is the same as that when the pressing member contacts the member to be pressed. The moving direction of the pressure contact member by the support member is deviated by an angle not exceeding 10 ° with respect to the direction of the straight line connecting the center of the pressure contact member and the center of the photosensitive member when the pressure contact member is in contact with the pressure contact member. It is arrange | positioned in the position used as the direction. Such an image forming apparatus has high positional accuracy of the relative position between the photosensitive member and the developing member. Even if the photosensitive unit or the developing unit is replaced, the reproducibility of the relative position is good.

The image forming apparatus according to the rotatably supports the support member, the photosensitive member and the developing member and having parallel support members rotating shaft, the central axis of the photosensitive member, the center of the pressing member by the rotation of the support member the arc is drawn with respect to the tangential direction at the time when pressing member is in contact with the pressure-contacted member, that is disposed at a position shifted to the opposite side of the supporting member axis of rotation. Therefore, positional accuracy of the relative position between the photosensitive member and the developing member is not high. Even if the photosensitive unit or the developing unit is replaced, the reproducibility of the relative position is good.

In the image forming apparatus described above, the support member is formed with a first pressing surface and a second pressing surface that press the pressing member toward the pressed member by rotation of the supporting member. and the second pressing surface, that are inclined in opposite directions with respect to the tangential direction of the arc drawn by the center of the pressing member by the rotation of the support member. Therefore, the moving direction as described above is, you more stable.

The image forming apparatus according to the present invention, by pressing the portion of the support member includes a state pressing that presses the pressing member to be pressed member by a support member, the slider to take a release state for releasing the pressing, the support the members, that have pressed portion is formed to receive the pressing by the slider. Therefore, the force pressing member is pressed against the pressure-contacted member you stable. Even if the photosensitive unit or the developing unit is replaced, the reproducibility of the relative position is good.

  According to the present invention, there is provided an image forming apparatus capable of arranging a photoconductor unit and a developing unit with high positional accuracy.

1 is a schematic configuration diagram for explaining an image forming apparatus according to the present invention. 1 is a schematic configuration diagram for explaining an image forming unit of an image forming apparatus according to the present invention. It is a perspective view for demonstrating the photoconductor unit of this invention. It is a projection view from the front for explaining the photosensitive unit of the present invention. It is a perspective view for demonstrating the image development unit of this invention. It is a projection view from the front for explaining the developing unit of the present invention. It is sectional drawing which shows the HH cross section of FIG. It is a front view for demonstrating the press-contact member and support member of this invention. FIG. 4 is a front projected view for explaining a case where the photosensitive unit and the developing unit are mounted on the image forming apparatus main body of the present invention. FIG. 4 is a conceptual diagram for explaining a gap interval between a photosensitive drum and a developing roller. FIG. 6 is a front view for explaining a moving direction of the developing unit in the present invention. FIG. 4 is a conceptual diagram for explaining a moving direction of a developing unit in the present invention. FIG. 5 is a front projection view for explaining a case where the photosensitive unit and the developing unit according to the present invention are attached and detached. It is a front view for demonstrating another moving direction of the image development unit in this invention.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the best mode for embodying the present invention will be described in detail with reference to the accompanying drawings. In the present embodiment, the present invention is embodied in an image forming apparatus.

1. Image Forming Apparatus The image forming apparatus 100 according to the present embodiment is a so-called tandem type color copier having an intermediate transfer belt 101 as schematically shown in FIG. The intermediate transfer belt 101 is an endless belt member. Both ends of the intermediate transfer belt 101 are supported by rollers 102 and 103 and rotate in the direction of arrow A in the drawing. Along the lower portion of the intermediate transfer belt 101 in the figure, image forming portions 1Y, 1M, 1C, and 1K for each color of yellow (Y), magenta (M), cyan (C), and black (K) are arranged.

  The image forming units 1Y, 1M, 1C, and 1K for the respective colors have the same configuration. Each has a photoreceptor unit 20, an exposure device 30, and a developing unit 10. The photoreceptor unit 20 has a photoreceptor drum 21 that carries an electrostatic latent image. The exposure device 30 is for drawing an electrostatic latent image on the photosensitive drum 21. The developing unit 10 is for applying toner to the electrostatic latent image on the photosensitive drum 21 for development. Further, a primary transfer device 111 is disposed at a position facing the photosensitive drum 21 with the intermediate transfer belt 101 interposed therebetween. In FIG. 1, the reference numerals of these devices are shown as representatives by the image forming unit 1Y.

  In FIG. 1, a paper feeder 112 that accommodates the paper P is disposed below. A paper feed roller 113 that feeds the paper P is provided above the paper feed device 112. The sheet P is sent upward from the sheet feeding device 112 along the sheet conveyance path 114. A secondary transfer device 115 is disposed at a position facing the roller 103 with the sheet conveyance path 114 interposed therebetween. Further, a fixing device 130 is disposed on the downstream side (upper side in the drawing). The fixing device 130 has a roller pair of a pressure roller 131 and a heating roller 132.

  A paper discharge roller 116 and a paper discharge tray 117 are arranged further downstream of the sheet conveying path 114 from the fixing device 130. A folding roller 119 and a folding tray 120 are disposed further above the paper discharge roller 116. The folding roller 119 is connected to the paper transport path 118 in addition to the paper transport path 114. The paper transport path 118 is a transport path used when performing duplex printing.

  Next, a basic operation of the image forming apparatus 100 of this embodiment will be briefly described. When the image forming apparatus 100 receives an image formation instruction, the image forming apparatus 100 generates image data of each color from the image signal. The generated image data of each color is sent to the corresponding image forming units 1Y, 1M, 1C, and 1K. The image forming units 1Y, 1M, 1C, and 1K for each color form toner images based on the image data as described later.

  The formed toner images are sequentially transferred to the intermediate transfer belt 101 by the primary transfer device 111 and superimposed. The toner image superimposed on the intermediate transfer belt 101 is transferred to the first surface of the paper P by the secondary transfer device 115. The sheet P carrying the toner image is further conveyed and reaches the fixing device 130, and is heated and pressurized by the fixing device 130. As a result, the toner image is fixed on the paper P. The paper P on which the toner image is fixed is discharged to a paper discharge tray 117 by a paper discharge roller 116. The above is the basic operation of the image forming apparatus 100.

2. Image forming unit The image forming units 1Y, 1M, 1C, and 1K have the same configuration. Therefore, the image forming unit 1 will be described below without distinguishing by color. As shown in FIG. 2, the image forming unit 1 of the present embodiment includes a photoconductor unit 20, an exposure device 30, and a developing unit 10. The exposure device 30 is for drawing an electrostatic latent image on the surface of the photosensitive drum 21 as described above. The photosensitive unit 20 and the developing unit 10 can be independently replaced.

  The photoconductor unit 20 includes a photoconductor drum 21, a charging device 22, and a cleaner 23. The photosensitive drum 21 is an image carrier for carrying a toner image. The charging device 22 is for uniformly charging the photosensitive drum 21 before exposure. The cleaner 23 is for collecting the development residual toner from the photosensitive drum 21.

  The developing unit 10 is a developing device that includes a developing roller 11, transport rollers 12 and 13, and a regulation blade 14. The developing roller 11 is a developing member for applying toner to the electrostatic latent image on the photosensitive drum 21. The conveying rollers 12 and 13 are for stirring the toner in the developing device and supplying the toner to the developing roller 11. The regulating blade 14 is a member that regulates the thickness of the toner layer on the surface of the developing roller 11.

  Here, the basic operation of the image forming unit 1 will be briefly described. The photosensitive drum 21 rotates in the direction of arrow B in FIG. And the process shown below is given with the rotation. First, the charging device 22 uniformly charges the surface of the photosensitive drum 21. On the downstream side, the exposure device 30 draws an electrostatic latent image on the surface of the photosensitive drum 21. Further downstream, the developing roller 11 rotating in the direction of arrow C in FIG. 2 applies toner to the electrostatic latent image formed on the surface of the photosensitive drum 21. As a result, a toner image is formed on the surface of the photosensitive drum 21. As described above, this toner image is transferred to the transfer belt 101 by the primary transfer device 111 of FIG.

3. Photoconductor Unit The photoconductor unit 20 will be described with reference to FIGS. FIG. 3 is a perspective view of the photoconductor unit 20. As shown in FIG. 3, the photoconductor unit 20 includes pressure-contact members 25 at two locations on both sides in the longitudinal direction of the photoconductor drum 21. The pressed member 25 is a member that is pressed by a pressing member 15 described later when the developing unit 10 is pressed against the photosensitive unit 20. The material of the pressure contact member 25 is, for example, hard plastic.

  FIG. 4 shows a projection view from the front of the photosensitive unit 20. An end portion of the pressure contact member 25 at a position where the photosensitive drum 21 faces the developing roller 11 is a pressure contact end portion 25b. The shape of the pressure contact end portion 25 b is a convex surface that is a part of a cylindrical surface having a radius slightly larger than the radius of the photosensitive drum 21, centered on the center 21 a of the photosensitive drum 21. That is, the convex surface of the pressure contact end portion 25b is coaxial with the photosensitive drum 21, and forms a part of a slightly larger diameter cylindrical surface. Further, the pressure contact member 25 is fixed so as not to rotate with respect to the photoreceptor unit 20.

4). Developing Unit The developing unit 10 will be described with reference to FIGS. FIG. 5 is a perspective view of the developing unit 10. FIG. 6 shows a projection view from the front of the developing unit 10. As shown in FIGS. 5 and 6, the developing unit 10 includes a pressure contact member 15 and a support member 16 in addition to the developing roller 11 and the like. As shown in FIG. 5, the pressure contact members 15 are arranged at two places on both sides in the longitudinal direction of the developing roller 11. The support member 16 is disposed at two locations corresponding to the pressure contact member 15. However, the support member 16 on the right side in FIG. 5 is hidden behind other members and does not appear in the figure. Further, the developing unit 10 has a toner outlet shutter 17. The toner discharge port shutter 17 is a member that closes the toner discharge port for collecting the development residual toner.

  FIG. 7 shows a HH cross section of FIG. For reference, the pressed member 25 is virtually drawn. Further, the rotation shaft 11b of the developing roller 11 shown in FIG. 7 extends on both sides in the longitudinal direction of the developing roller 11 itself. And the pressure contact member 15 is attached to the both ends of the rotating shaft 11b via the bearing 19. FIG. For this reason, the developing roller 11 is rotatable with respect to the pressure contact member 15.

  The pressure contact member 15 is a member that presses the pressure contact member 25 of the photosensitive unit 20 when the developing unit 10 is pressed against the photosensitive unit 20. The shape of the pressure contact member 15 is a cylindrical shape. The central axis of the pressure contact member 15 is coaxial with the central axis of the developing roller 11. The radius of the pressure contact member 15 is the same as the radius of the developing roller 11. That is, the cylindrical surface of the pressure contact member 15 is overlapped with a surface obtained by extending the cylindrical surface of the developing roller 11 in the axial direction.

  The support member 16 is a member for pressing the pressure contact member 15 against the pressure contact member 25. Further, as will be described later, the support member 16 determines the direction in which the pressure contact member 15 presses the pressure contact member 25 of the photosensitive unit 20. The material of the support member 16 is a metal. As will be described later, since the support member 16 is subjected to a pressure contact force and a rotational moment, it is preferable that the support member 16 is not easily deformed. Further, as shown in FIG. 6, the support member 16 can be rotated by a certain angle with respect to the main body of the developing unit 10 with the rotation shaft 18 as a central axis. The support member 16 is an integral member in which both the left and right sides are connected by a rotation shaft 18. That is, the rotation shaft 18 is arranged in parallel to the longitudinal direction of the developing unit 10. Therefore, the two pressing members 15 shown in FIG. 5 can be pressed against the pressed member 25 with a single support member 16.

  FIG. 8 shows the pressing unit 15 and the support member 16 extracted from the developing unit 10. A recess 16 a is formed in the support member 16. The recess 16a is provided on the support member 16 on the front side (left side in FIG. 5), and is not necessary for the support member 16 on the back side (right side in FIG. 5). The concave portion 16a is a pressed portion that is pressed by a developing unit press-contact slider 151 described later. A V-shaped member 16 b is fixed to the support member 16. The V-shaped member 16b is for pressing the pressure contact member 15 and for determining the moving direction D of the pressure contact member 15. The V-shaped member 16b is provided on both the left and right support members 16. Both are arranged at the same angle with respect to the rotation shaft 18. As will be described later, the moving direction D is configured to be substantially on the bisector of the angle formed by the first surface 16c and the second surface 16d of the V-shaped member 16b.

  As shown in FIG. 7, the second surface 16 d of the V-shaped member 16 b of the support member 16 is in contact with the pressure contact member 15. The support member 16 is positioned between the developing roller 11 and the bearing 19, but does not interfere with the rotating shaft 11 b, the bearing 19, and the pressure contact member 15. Further, a through hole sufficiently larger than the rotating shaft 11b may be provided in the support member 16, and the rotating shaft 11b may be passed through the through hole. Actually, since the V-shaped member 16b is in contact with the pressure contact member 15, the rotating shaft 11b does not interfere with the through hole and does not interfere with the pressure contact.

5. Relative Position of Photoreceptor Unit and Development Unit FIG. 9 is a projection view seen from the same direction as FIG. 1 when the photoreceptor unit 20 and the development unit 10 are mounted on the main body of the image forming apparatus 100. In FIG. 9, the developing roller 11 is located behind the press contact member 15 in the drawing. When viewed from the front, the developing roller 11 overlaps with the pressure contact member 15 and does not appear directly in FIG.

  As shown in FIG. 9, the pressure contact member 15 of the developing unit 10 is in pressure contact with the pressure contact member 25 of the photoreceptor unit 20. At this time, the pressure contact end portion 15 b of the pressure contact member 15 is in contact with the pressure contact end portion 25 b of the pressure contact member 25. Here, the center 15 a of the pressure contact member 15 is common to the center 11 a of the developing roller 11. And the radius is the same. The shape of the pressure contact end portion 25 b is a convex surface that is a part of a cylindrical surface having a radius slightly larger than the radius of the photosensitive drum 21, centered on the center 21 a of the photosensitive drum 21.

  For this reason, when the pressing member 15 and the pressed member 25 come into contact with each other, the photosensitive drum 21 and the developing roller 11 face each other with a slight gap. The gap S is obtained by subtracting the sum of the radius of the developing roller 11 and the radius of the photosensitive drum 21 from the sum of the radius of the pressure contact member 15 and the radius of the pressure contact member 25.

The relationship is shown in FIG. FIG. 10 is a conceptual diagram in which the section II in FIG. 9 is simplified in order to explain the gap interval S between the photosensitive drum 21 and the developing roller 11. The sum of the radius Ra of the pressure contact member 15 and the radius Rb of the pressure contact member 25 is calculated as follows: the radius Ro of the photosensitive drum 21, the radius Rd of the developing roller 11, and the gap S between the photosensitive drum 21 and the developing roller 11. Equal to the sum.
Ra + Rb = Ro + Rd + S (1)
Ra: Radius of the pressure contact member
Rb: radius of the arc shape of the pressed member
Ro: Radius of the photosensitive drum
Rd: radius of developing roller
S: Interval between the photosensitive drum and the developing roller

  Therefore, the sum of the radius Ro of the photosensitive drum 21, the radius Rb of the developing roller 11, and the gap S between the photosensitive drum 21 and the developing roller 11 is constant. Therefore, the radius Ra of the pressure contact member 15 and the radius Rb of the pressure contact member 25 may be changed within a range satisfying the expression (1). For example, the arc-shaped radius Rb of the pressure contact member 25 is made equal to the radius Ro of the photosensitive drum 21, and the radius Ra of the pressure contact member 15 is increased by that amount instead.

  In this embodiment, the photosensitive drum 21 and the developing roller 11 are directly positioned. For this reason, the accuracy of the relative position between the photosensitive drum 21 and the developing roller 11 in this embodiment is higher than that which indirectly provides the position accuracy. The case where the positional accuracy is indirectly determined here means that the photosensitive drum 21 and the main body of the image forming apparatus 100 are positioned, and the developing roller 11 and the main body of the image forming apparatus 100 are positioned. Further, in this embodiment, the pressure contact member 15 and the pressure contact member 25 are provided in two locations and are in pressure contact with each other, so that the parallelism is also high.

  And since the substantially same location of the press-contact member 15 and the press-contact member 25 contacts before and after replacement | exchange, the reproducibility of the space | interval S of this clearance gap is good. Furthermore, since the moving direction D is determined as will be described later, there is almost no difference in the gap interval before and after the replacement of the photosensitive unit 20 or the developing unit 10.

6). Pressing Method As shown in FIG. 9, the image forming apparatus 100 includes a developing unit pressing slider 151 and a developing unit pressing spring 152 in addition to those described above. The development unit pressure slider 151 is for pushing the support member 16 of the development unit 10. The developing unit pressure contact slider 151 can take a pressing state in which the pressure contact member 15 is pressed against the pressure contact member 25 via the support member 16 and a released state in which the pressure is released. The developing unit pressure contact slider 151 is rotatable by a certain angle in the direction of arrow E in the drawing. The developing unit pressure contact slider 151 is formed with a convex portion 151a that is an arc-shaped convex surface. The convex portion 151 a has a shape that fits just into the concave portion 16 a of the support member 16. In FIG. 9, the convex portion 151a is just fitted in the concave portion 16a.

  The development unit pressure contact spring 152 is for pressing the development unit pressure contact slider 151 and pressing the convex portion 151a against the concave portion 16a. As a result, the developing unit pressure contact slider 151 pushes the support member 16a. However, the force of the developing unit pressure contact spring 152 is a force that can be manually pushed back.

  The developing unit pressure contact slider 151 presses the support member 16 of the developing unit 10 in the state of FIG. For this reason, a rotational moment (torque) about the center 18 a of the rotation shaft 18 is applied to the support member 16. Due to the rotational moment, the two parts of the V-shaped member 16b, that is, one part of the first surface 16c and one part of the second surface 16d press the pressing member 15.

  That is, the first surface 16c of the V-shaped member 16b is a first pressing surface for pressing the pressure contact member 15 with the contact surface. The second surface 16d of the V-shaped member 16b is a second pressing surface for pressing the pressure contact member 15 with the contact surface. The first surface 16c pushes the pressure contact member 15 vertically. The second surface 16d also pushes the pressure contact member 15 vertically. That is, the pressure contact member 15 is pushed by both the first surface 16c and the second surface 16d. The direction in which the pressure contact member 15 is pressed is the direction of the resultant force received from these two points. The direction is a moving direction D described below.

7). Movement Direction Next, the movement direction D will be described with reference to FIGS. 11 and 12. FIG. 11 is a diagram in which the pressing member 15 and the pressed member 25 are extracted from FIG. 9 in order to explain the moving direction D. FIG. 12 is a further simplified view of FIG. As shown in FIG. 11, the V-shaped member 16 b of the support member 16 presses the pressure contact member 15 at two locations of the first surface 16 c and the second surface 16 d.

  The moving direction D shown in FIG. 11 is the traveling direction at the moment when the pressure contact member 15 contacts the pressure contact member 25 during pressure contact. The pressing member 15 moves toward the pressed member 25 while drawing an arc centered on the center 18 a of the central shaft 18. The direction is the tangential direction of the arc centered on the center 18a. The moving direction D is the traveling direction of the pressure contact member 15 at the moment when the center 15a of the pressure contact member 15 contacts the pressure contact member 25 in an arc. Line L indicates the center 15a of the pressure contact member 15 (center 11a of the developing roller 11) and the center 25a of the pressure contact member 25 (center 21a of the photosensitive drum 21) at the moment when the pressure contact member 15 contacts the pressure contact member 25. Is a line connecting A line M is a line connecting the center 15 a of the pressure contact member 15 (the center 11 a of the developing roller 11) and the center 18 a of the rotation shaft 18 at the moment when the pressure contact member 15 contacts the pressure contact member 25.

  As shown in FIG. 12, the moving direction D and the line M are orthogonal. This is because the moving direction D is a tangential direction when the arc pressure contact member 15 drawn by the center 15a of the pressure contact member 15 contacts the pressure contact member 25, and the line M is a normal direction. Then, the direction of the pressing force is the direction of the moving direction D. The moving direction D and the bisector of the angle formed by the first surface 16c and the second surface 16d of the V-shaped member 16b are configured to substantially overlap. That is, the pressure contact member 15 is disposed so that the magnitudes of the forces received from the first surface 16c and the second surface 16d of the V-shaped member 16b are substantially equal. Specifically, the angle formed by the first surface 16c of the V-shaped member 16b and the moving direction D is substantially equal to the angle formed by the second surface 16d and the moving direction D. The first surface 16c and the second surface 16d are inclined in opposite directions with respect to the moving direction D. The angle formed by the moving direction D and the line L is preferably within 10 °.

  Here, the moving direction D of the pressure contact member 15 is configured not to coincide with a line L connecting the center 21 a of the photosensitive drum 21 and the center 11 a of the developing roller 11. The reason is described below. It is assumed that the moving direction D and the line L are configured to coincide with each other. Then, there are the following harmful effects. However, in actual products, variations occur within the tolerance range. Therefore, when the pressure contact member 15 is pressed against the pressure contact member 25, the pressure contact member 15 is displaced in the upper left direction or the lower right direction in FIG. As a result, the relative positional relationship between the photosensitive drum 21 and the developing roller 11 changes every time it is replaced.

  In this embodiment, the pressure contact end portion 15 b of the pressure contact member 15 presses the pressure contact end portion 25 b of the pressure contact member 25 in the direction of movement D. At this time, at the location where the pressure contact end portion 15b and the pressure contact end portion 25b are in contact, the component of the force with which the pressure contact end portion 15b presses the pressure contact end portion 25b is the normal direction of the contact surface (line L Can be decomposed into a tangential direction (a direction perpendicular to the line L). The force component in the tangential direction (direction perpendicular to the line L) acts in the direction of the arrow F in the figure.

  For this reason, when the pressure contact member 15 is pressed against the pressure contact member 25, the pressure contact member 15 is shifted slightly from the pressure contact member 25 by the force in the direction of the arrow F and stops. This deviation does not change with each press contact. Therefore, the positional accuracy of the relative position between the photosensitive drum 21 and the developing roller 11 is high. Then, at the time of press contact, no force is applied in the direction of the arrow F, and no force is applied in the opposite direction. Therefore, the reproducibility of the relative position between the photosensitive drum 21 and the developing roller 11 is good.

  As described above, the accuracy and reproducibility of the relative position between the photosensitive drum 21 and the developing roller 11 can be achieved by pressing the developing unit 10 against the photosensitive unit 20 in the moving direction D. It is more improved. In other words, the moving direction D of the pressure contact member 15 is configured to deviate from the line L connecting the center 21a of the photosensitive drum 21 and the center 11a of the developing roller 11, so that the photosensitive drum 21 and the developing roller 11 The positional accuracy of the relative position between the two is improved.

  In this embodiment, the photosensitive drum 21 and the developing roller 11 are directly positioned. For this reason, the accuracy of the relative position between the photosensitive drum 21 and the developing roller 11 in this embodiment is higher than that which indirectly provides the position accuracy. The case where the positional accuracy is indirectly determined here means that the photosensitive drum 21 and the main body of the image forming apparatus 100 are positioned, and the developing roller 11 and the main body of the image forming apparatus 100 are positioned. Further, in this embodiment, the pressure contact member 15 and the pressure contact member 25 are provided in two locations and are in pressure contact with each other, so that the parallelism is also high.

  And since the substantially same location of the press-contact member 15 and the press-contact member 25 contacts before and after replacement | exchange, the reproducibility of the space | interval S of this clearance gap is good. Since the moving direction D is determined as described above, there is almost no difference between the gaps before and after the photoconductor unit 20 or the developing unit 10 is replaced.

  At this time, the moving direction D is in one of the two areas divided by the line L connecting the central axis 21a of the photosensitive drum 21 and the central axis 11a of the developing roller 11. This area is an area on the side where the photosensitive unit 20 and the developing unit 10 face each other (see FIG. 9).

  Further, the moving direction D is an angular range formed by a line connecting the center 15a of the press contact member 15 and the center 25a of the pressed member 25 and a line connecting the center 15a of the press contact member 15 and the center 18a of the rotary shaft 18. Is in. However, the moving direction D is close to the direction of the line L. Further, the center 15a of the pressure contact member 15 and the center 11a of the developing roller 11 are the same, and the center 25a of the pressure contact member 25 and the center 21a of the photosensitive drum 21 are the same.

8). Attachment / Removal of Development Unit First, the case where the development unit 10 is detached from the image forming apparatus 100 will be described with reference to FIGS. FIG. 9 is a diagram showing a state where both the developing unit 10 and the photosensitive unit 10 are mounted on the main body of the image forming apparatus 100 as described above. FIG. 13 is a diagram illustrating a case where the developing unit 10 is separated from the state of FIG. 9 in a direction away from the photosensitive unit 20.

  First, from the state shown in FIG. 9, the development unit pressure contact slider 151 is slid in the direction in which the development unit pressure spring 152 is contracted. Next, the developing unit pressure contact slider 151 is separated from the support member 16 by rotating in the direction of arrow E in FIG. That is, the convex portion 151 a of the developing unit pressure contact slider 151 is separated from the concave portion 16 a of the support member 16. As a result, the force acting on the support member 16 by the developing unit pressure contact slider 151 is eliminated. At the same time, the support member 16 does not press the pressure contact member 15. Then, the pressure contact with the pressure contact member 25 by the pressure contact member 15 is released.

  Next, the developing unit 10 is retracted in the direction away from the photosensitive unit 20, that is, in the direction of arrow G in FIG. Thereby, as shown in FIG. 13, the photoconductor unit 20 and the developing unit 10 are in a separated state. Subsequently, the developing unit 10 is pulled out in the direction perpendicular to the paper surface in FIG. Thereby, the developing unit 10 is taken out.

  Note that the developing unit 10 is mounted on the image forming apparatus 100 by performing the steps in the reverse order of the above procedure. Further, the replacement of the photoconductor unit 20 is similarly performed by taking the photoconductor unit 20 in and out in a direction perpendicular to the paper surface in FIG. 1 with the developing unit 10 separated as shown in FIG. be able to.

9. In this embodiment, the moving direction D is one of the two areas divided by the line L connecting the center 21a of the photosensitive drum 21 and the center 11a of the developing roller 11, and the photosensitive unit 20 And an area on the side where the developing unit 10 faces (see FIG. 11). However, the moving direction D may be on the side where there is no place where the photosensitive unit 20 and the developing unit 10 face each other as shown in FIG. Even if it does in this way, it is because it does not change that the press-contact member 15 stops at the almost same position whenever it presses.

  In this embodiment, the diameter of the pressure contact member 15 is the same as the diameter of the developing roller 11. However, the diameter of the pressure contact member 15 may be larger than the diameter of the developing roller 11. Moreover, you may make it small. If the sum of the radius Ra of the pressure contact member 15 and the radius Rb of the pressure contact member 25 is constant, the respective values may be changed (see Expression (1)). However, it is desirable that the pressure contact member 15 is close to the diameter of the developing roller 11. The shape may be other shapes. For example, a disk shape, a ring shape, etc. are mentioned. That is, the surface of the portion pressed against the pressure contact member 25 may be a cylindrical surface shape coaxial with the developing roller 11.

  In this embodiment, a member fixed to the bearing 19 is used as the pressure contact member 15. However, the bearing itself may be used as the pressure contact member 15. In that case, the radius of the bearing may be the same as the radius of the developing roller 11. This is because the bearing is coaxial with the developing roller 11 and is rotatable with respect to the developing roller 11.

  The material is preferably a metal because it is not desirable to be easily deformed. Further, it may be a hard plastic. The shape of the pressure contact member 15 is assumed to be a cylindrical shape. However, as long as the portion of the support member 25 that contacts the V-shaped member 25b and the press contact end portion 15b have an arc shape, other shapes may be used. As long as the gap S between the photosensitive drum 21 and the developing roller 11 is reproduced, the radius may be changed. That is, the sum of the radius of the cylindrical surface shape of the pressure contact member 15 and the radius of the cylindrical surface shape of the pressure contact member 25 may be larger than the sum of the radius of the developing roller 11 and the radius of the photosensitive drum 21.

  In this embodiment, hard plastic is used as the pressure contact member 25. However, it may be a metal. Other materials may be used as long as the members have hardness that does not easily deform. In addition, an arc-shaped member was used as the pressure contact member 25. However, the pressure contact member 25 may have a cylindrical shape or a columnar shape. That is, the surface of the portion facing the developing unit may be a cylindrical surface coaxial with the photosensitive drum 21. This is because no problem occurs at the contact point with the pressure contact member 15. The support member 16 can also be installed on the main body of the image forming apparatus 100. This is because the support member 16 is provided for causing the developing roller 11 to face the photosensitive drum 21 with a gap.

10. Summary As described above in detail, the developing unit 10 and the image forming apparatus 100 according to the present embodiment directly position the photosensitive drum 21 and the developing roller 11. For this reason, the accuracy of the relative position between the photosensitive drum 21 and the developing roller 11 in this embodiment is higher than that which indirectly provides the position accuracy. The case where the positional accuracy is indirectly determined here means that the photosensitive drum 21 and the main body of the image forming apparatus 100 are positioned, and the developing roller 11 and the main body of the image forming apparatus 100 are positioned. Further, in this embodiment, the pressure contact member 15 and the pressure contact member 25 are provided in two locations and are in pressure contact with each other, so that the parallelism is also high.

  And since the press-contact member 15 and the to-be-contacted member 25 contact in the substantially same location, the reproducibility of the space | interval S of this clearance gap is good. Since the moving direction D is deviated from the line L, there is almost no difference between the gaps before and after the replacement of the photosensitive unit 20 or the developing unit 10. In addition, the force for pressing the photoreceptor unit 20 is stabilized. As a result, the risk of the positional relationship being lost due to the force generated by opening and closing the toner outlet shutter 17 is reduced. Thereby, the image forming apparatus 100 with high positional accuracy between the photoconductor unit 20 and the developing unit 10 is realized.

  Note that this embodiment is merely an example, and does not limit the present invention. Therefore, the present invention can naturally be improved and modified in various ways without departing from the gist thereof. For example, the developing member is not limited to the developing roller. It does not depend on the type of toner. The image forming apparatus 100 is not limited to a color copier. That is, it is not limited to color. Moreover, it is not restricted to a copier. The present invention can be applied to a printer, a FAX, and other apparatuses that form images. The developing unit 10 may be brought into pressure contact with the photosensitive unit 20 by parallel movement instead of rotational movement. The developing unit pressure contact slider 151 and the development unit pressure spring 152 may be attached to the photoconductor unit 20. Further, the support member 16 and the rotating shaft 18 may be attached to the photoreceptor unit 20 or the main body of the image forming apparatus 100.

DESCRIPTION OF SYMBOLS 10 ... Developing unit 11 ... Developing roller 15 ... Pressure contact member 16 ... Supporting member 16b ... V-shaped member 16c ... First surface 16d ... Second surface 17 ... Toner discharge port shutter 18 ... Rotating shaft 19 ... Bearing 20 ... Photoconductor unit 21 ... photosensitive drum 25 ... pressed member 30 ... exposure apparatus 100 ... image forming apparatus 151 ... developing unit pressing slider 152 ... developing unit pressing springs 11a, 15a, 18a, 21a, 25a ... center D ... moving direction L ... developing roller A line M connecting the center and the center of the photosensitive drum. A line connecting the center of the developing roller and the rotation center of the rotation pressure contact.

Claims (2)

A photoreceptor unit having a photoreceptor;
In an image forming apparatus provided with a developing unit having a developing member for applying a developer to the photosensitive member so as to be detachable from the main body,
A support member that causes the developing member to face the photoconductor with a gap in a state where the photoconductor unit and the developing unit are both mounted on a main body;
A pressure-contact member provided in the photosensitive unit, wherein at least a part of the surface facing the developing unit has a cylindrical surface coaxial with the photosensitive unit;
The developing unit is rotatably attached to a rotation shaft of the developing member, and is pressed against the pressure contact member by the support member, and at least a surface of a portion pressed against the pressure contact member is the development member. A pressure contact member having a cylindrical surface shape coaxial with the member ;
A support member rotating shaft parallel to the photosensitive member and the developing member, which rotatably supports the support member ;
The sum of the radius of the cylindrical surface shape of the pressure contact member and the radius of the cylindrical surface shape of the pressure contact member is greater than the sum of the radius of the developing member and the radius of the photoconductor,
The central axis of the photoreceptor is
The direction of movement of the pressure contact member by the support member when the pressure contact member contacts the pressure contact member,
With respect to the direction of a straight line connecting the center of the pressure contact member and the center of the photoconductor when the pressure contact member is in contact with the pressure contact member,
It is located at a position that is shifted by an angle not exceeding 10 ° ,
With respect to the tangential direction of the arc drawn by the center of the pressure contact member by the rotation of the support member when the pressure contact member is in contact with the pressure contact member,
Arranged at a position shifted to the opposite side of the support member rotation axis;
The support member is formed with a first pressing surface and a second pressing surface that push the pressing member toward the pressed member by rotation of the supporting member,
The image forming apparatus, wherein the first pressing surface and the second pressing surface are inclined in directions opposite to each other with respect to a tangential direction of an arc drawn by a center of the pressing member by rotation of the support member. . A photoreceptor unit having a photoreceptor;
In an image forming apparatus provided with a developing unit having a developing member for applying a developer to the photosensitive member so as to be detachable from the main body,
A support member that causes the developing member to face the photoconductor with a gap in a state where the photoconductor unit and the developing unit are both mounted on a main body;
A pressure-contact member provided in the photosensitive unit, wherein at least a part of the surface facing the developing unit has a cylindrical surface coaxial with the photosensitive unit;
The developing unit is rotatably attached to a rotation shaft of the developing member, and is pressed against the pressure contact member by the support member, and at least a surface of a portion pressed against the pressure contact member is the development member. A pressure contact member having a cylindrical surface shape coaxial with the member ;
A supporting member rotating shaft parallel to the photosensitive member and the developing member, which rotatably supports the supporting member;
A slider that takes a pressing state in which the pressing member is pressed against the pressed member by the supporting member and a released state in which the pressing is released by pressing a part of the supporting member ;
The sum of the radius of the cylindrical surface shape of the pressure contact member and the radius of the cylindrical surface shape of the pressure contact member is greater than the sum of the radius of the developing member and the radius of the photoconductor,
The central axis of the photoreceptor is
The direction of movement of the pressure contact member by the support member when the pressure contact member contacts the pressure contact member,
With respect to the direction of a straight line connecting the center of the pressure contact member and the center of the photoconductor when the pressure contact member is in contact with the pressure contact member,
It is located at a position that is shifted by an angle not exceeding 10 ° ,
With respect to the tangential direction of the arc drawn by the center of the pressure contact member by the rotation of the support member when the pressure contact member is in contact with the pressure contact member,
Arranged at a position shifted to the opposite side of the support member rotation axis;
An image forming apparatus , wherein the support member is formed with a pressed portion that is pressed by the slider .

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