JP2006123474A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus wherein position adjustment can be easily carried out even after an exposure means for exposing an electrostatic latent image by scanning laser beams is installed, and a precision of an exposure position of the laser beams can be stably improved. <P>SOLUTION: A pair of position adjustment means 37 are fitted between a mounting bracket 33 with an exposure head 21 fixedly placed thereat, and a base frame 35 disposed at the side of its photoreceptor drum 19. The position adjustment means 37 are set at a starting end side Ls and an ending end side Le of an ejection region of the laser beams, respectively. The position adjustment means 37 consists of a position adjustment plate 38 fixed to the mounting bracket 33, and a cam member 39 set rotatably to the base frame 35. By rotating the cam members 39, the position adjustment plates are moved up and down, whereby an up-down position of the mounting bracket 33 is adjusted. Tilting of a scanning line S of the laser beams is adjusted accordingly. <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 machine.

  As an electrophotographic image forming apparatus, for example, a photosensitive drum is used as an image carrier, and the surface is charged and exposed to a laser beam to form an electrostatic latent image, and toner is attached to the electrostatic latent image. It is known that an image is formed such that the image is visualized and transferred to a sheet. In such an image forming apparatus, as improvement in image quality is required, it is important to improve the accuracy of the exposure position of the laser beam with respect to the photosensitive drum. However, the exposure position accuracy of the laser beam on the photosensitive drum falls due to the effects of the accuracy of parts of the exposure device that emits the photosensitive drum and laser light and the accumulation of errors during assembly. Will occur. Therefore, the mounting position is adjusted after the exposure apparatus is mounted to improve the accuracy of the laser beam exposure position on the photosensitive drum.

  As a method for adjusting the mounting position of the exposure device, for example, a position adjustment shim is added to the mounting position to make fine adjustments. It is necessary to check whether the accuracy has improved. Therefore, if the accuracy has not improved as expected, remove the fixed screw, replace it with a shim with a different thickness, and then fix the screw again. Annoying work must be done.

  As a method other than the case of adjusting the position using the shim, for example, in Patent Document 1, in the printer unit including the LSU and the photosensitive drum from above the frame body, the two rod-shaped members are the photosensitive drum. The LSU, which is provided in parallel with the drive shaft core and at an appropriate distance in the horizontal direction above the printer unit in the frame, is similarly positioned on the rod-like member, and is also positioned with high accuracy on the photosensitive drum. The point is described.

Patent Document 2 discloses a writing optical system unit that includes a laser light source and irradiates the surface of the photosensitive drum with light from the light source via a reflection mirror. The rotation of the unit frame is held in the image forming apparatus so as to be rotatable in a plane parallel to the axial direction of the body drum. The point controlled by the elastic member is described.
Japanese Patent Laid-Open No. 5-48786 JP 2003-94723 A

  In Patent Document 1, the LSU is positioned with high precision with respect to the photosensitive drum. However, after the LSU is assembled, the frame itself on which the LSU is assembled or the influence of the component accuracy on other parts, If the position of the LSU is shifted due to accumulated error, or if the position is shifted due to changes over time of the frame body due to vibration, the position adjustment means after assembly is not provided, so the accuracy of the exposure position of the LSU Cannot be easily adjusted when it falls. Further, in Patent Document 2, since the position of the optical system unit is adjusted using a cam, the entire unit is rotated. Therefore, fine adjustment is difficult, and the entire unit moves after adjustment. It is easy to go wrong.

  Therefore, the present invention can easily adjust the position of an exposure unit that scans a laser beam to form an electrostatic latent image, and can stably improve the accuracy of the exposure position of the laser beam. An object of the present invention is to provide a forming apparatus.

  An image forming apparatus according to the present invention forms an electrostatic latent image by scanning an image carrier, charging means for charging the surface of the image carrier, and laser light on the charged surface of the image carrier. An exposure unit; a developing unit that attaches toner to the electrostatic latent image formed on the surface of the image carrier to make a visible image; and controls each of the image carrier to rotate and control the image carrier to form an image on a sheet. In the image forming apparatus comprising the control means for controlling the means, they are respectively arranged at the start end side and the end end side of the laser light emission region of the exposure means and intersect a plane including the rotation center line of the image carrier. And a pair of position adjusting means for adjusting the scanning direction of the laser light so as to follow the rotation center line of the image carrier. Further, the position adjusting means includes a cam member rotatably attached to the main body frame, and a position adjusting member attached to the exposure means and having a hole portion loosely fitted to the cam member, The position adjusting member is moved by rotation of the cam member, and the exposure means is moved.

  By having the configuration as described above, the pair of position adjusting means are arranged on the start end side and the end end side of the laser light emission region of the exposure means, respectively, and therefore include the rotation center line of the image carrier of the exposure means. The movement adjustment in the direction intersecting the plane can be easily and accurately performed. That is, when the emission region of the laser beam emitted from the exposure unit is inclined with respect to the plane including the rotation center line of the image carrier, the position adjusting unit on the start side and the position adjusting unit on the end side are adjusted in opposite directions. By doing so, the tilt can be easily adjusted in a short time, and the adjustment work can be made more efficient. Moreover, since both the position adjusting means are operated in parallel, the adjustment can be performed with high accuracy.

  The position adjusting means includes a cam member rotatably attached to the main body frame, and a position adjusting member attached to the exposure means and having a hole portion loosely fitted to the cam member. The position can be continuously adjusted by rotating, and highly accurate position adjustment can be reliably performed with a simple configuration.

  Hereinafter, embodiments according to the present invention will be described in detail. The embodiments described below are preferable specific examples for carrying out the present invention, and thus various technical limitations are made. However, the present invention is particularly limited in the following description. Unless otherwise specified, the present invention is not limited to these forms.

  FIG. 1 is a schematic cross-sectional view of the entire image forming apparatus according to the present invention. A paper discharge tray 10 is provided in the upper part of the image forming apparatus 1, and a recording unit 2 and a paper supply unit 3 are arranged in the lower part thereof.

  In the paper feed unit 3, a paper feed cassette 11 is arranged, and a plurality of sheets of a predetermined size are stacked on the flapper 12. A pickup roller 13 is disposed at the right end of the paper feed cassette 11. The flapper 12 is urged upward by a spring member (not shown) so that the upper surface of the stacked paper comes into pressure contact with the pickup roller 13. When the pickup roller 13 is rotationally driven in this state, the sheets are fed one by one to the sheet conveyance path by the frictional force.

  The fed paper is first conveyed to the recording unit 2 by the feed roller 14 and the press roller 15. The recording unit 2 includes a developing unit 16, a cleaning mechanism 17, a corona charger 18, a photosensitive drum 19, a transfer roller 20, an exposure head 21, and a fixing roller 22 for recording on the conveyed paper. The cleaning mechanism 17 cleans the surface of the photoconductive drum 19 by capturing foreign particles such as residual toner and paper dust attached to the surface of the photoconductive drum 19 after the transfer with a cleaning roller. The corona charger 18 uniformly charges the surface of the photosensitive drum 19 by corona discharge from the discharge wire. An electrostatic latent image is formed on the uniformly charged photosensitive drum 19 by exposing the photosensitive drum 19 in accordance with an image recording signal. Then, the toner in the developing device 16 is transferred to the electrostatic latent image formed on the photosensitive drum 19 to visualize the electrostatic latent image. The transfer roller 20 is installed at a position facing the photosensitive drum 19 with the paper interposed therebetween, and a toner image formed on the surface of the photosensitive drum 19 is transferred to the paper when a predetermined voltage is applied. The transferred toner image is sandwiched between the fixing roller 22 and the press roller 23 and heated and pressed to be fixed on the paper. The fixed sheet is sandwiched between the sheet discharge roller 24 and the press roller 25 and is carried out to the sheet discharge tray 10.

  Further, a manual paper feed mechanism and a reverse conveyance mechanism are provided on the side surface of the apparatus main body, and when performing manual paper feed, the side cover 26 is opened and the paper is inserted into the paper feed roller 27. . The inserted paper is conveyed to the feed roller 14 and the press roller 15 by the paper feed roller 27 and recording operation is performed. Also, when performing reverse conveyance, the paper recorded on one side is once sandwiched between the paper discharge roller 24 and the press roller 25 and then conveyed, and then the paper discharge roller 24 is rotated in reverse to be conveyed to the reverse conveyance path. Then, the feed roller 28 and the press roller 29, and the feed roller 30 and the press roller 31 are transported downward by two pairs of transport rollers. Then, the sheet is conveyed again to the feed roller 14 and the press roller 15 and a recording operation is performed on the other side, and recording is performed on both sides of the sheet.

  FIG. 2 is a perspective view showing a mounting portion of the exposure head 21. In the exposure head 21, optical components such as a laser light source, a polygon mirror, and a plurality of lenses are arranged in a unit, and is placed and fixed in a mounting hole portion of a mounting bracket 33 formed with a metal plate. . On the side surface of the exposure head 21, three fixing portions 34 are formed so as to project horizontally, and are fixed by screws, pins or the like at the periphery of the mounting hole portion of the mounting bracket 33.

  On both sides of the mounting bracket 33, a fixing portion 36 bent vertically and a locking portion 47 protruding horizontally are formed. Two screw holes 36a and 36b are formed in the fixing portion 36 at a predetermined interval in the horizontal direction. The screw hole 36a is formed at a position far from the photosensitive drum 19, and the screw hole 36b is formed in the photosensitive drum. It is drilled at a position close to 19. As will be described later, a holding screw is screwed into the screw hole 36a so that the mounting bracket 33 is rotatably attached to a side frame (not shown). Further, a fixing screw is screwed into the screw hole 36b so that the mounting bracket 33 is fixed to the side frame.

  The locking portion 47 is formed in a flat rectangular shape so that it can be inserted into a locking hole (not shown) provided in the side frame of the main body frame. Further, the locking hole formed in the side frame is preferably formed to be large so that the locking portion 47 can move up and down.

  When attaching the mounting bracket 33 to the side frame, first, the locking portion 47 is inserted into the locking hole of the side frame, and a holding screw is screwed into the screw hole 36a to temporarily fix the mounting bracket 33 to the side frame. In this state, the mounting bracket 33 is rotatable about the screw hole 36a, and the tilt position of the exposure head 21 can be easily adjusted by the position adjusting means 37 as will be described later. Then, after the adjustment of the tilt position of the exposure head 21 by the position adjusting means 37 is completed, a fixing screw is screwed into the screw hole 36b to completely fix the mounting bracket 33 to the side frame.

  A base frame 35 which is a part of the main body frame is disposed above the exposure head 21 on the photosensitive drum 19 side. The base frame 35 is formed of a metal plate having an L-shaped cross section and is fixed to a side frame (not shown). The base frame 35 is arranged so that a vertical portion thereof is substantially along the side surface of the mounting bracket 33 on the photosensitive drum 19 side. It is installed. Further, the horizontal portion of the base frame 35 is provided so as to protrude toward the photosensitive drum 19 above the emission region of the laser beam from the exposure head 21.

  The optical path of the laser beam emitted from the exposure head 21 sequentially moves in the emission region from the start side Ls to the end side Le, and thereby the laser beam is irradiated along the scanning line S on the surface of the photosensitive drum 19. Is done. FIG. 3 is an explanatory diagram showing the relationship between the rotation center line P of the rotation axis of the photosensitive drum 19 and the scanning line S. In order to accurately form an electrostatic latent image on the surface of the photosensitive drum 19. Needs to be set so that the rotation center line P and the scanning line S are parallel or coincide with each other. As shown in FIG. 3, when the scanning line S is inclined at an angle θ with respect to the rotation center line P, the formed electrostatic latent image is also inclined with respect to the surface of the photosensitive drum 19. In order to adjust the inclination, position adjusting means 37 are provided on the start side Ls and the end side Le, respectively.

  The pair of position adjusting means 37 includes a position adjusting plate 38 whose lower portion is fixed to the mounting bracket 33, and a cam loosely fitted in a hole formed in the upper portion of the position adjusting plate 38 and rotatably attached to the base frame 35. It consists of a member 39.

  FIG. 4 is an enlarged cross-sectional view of the position adjusting means 37 portion on the end side Le viewed from the direction of the arrow when cut along a vertical plane at the position AA in FIG. FIG. 5 is an enlarged view of the position adjusting unit 37 on the end side Le in FIG. 2 as viewed from the photosensitive drum 19 side. The base frame 35 is shown so that the configuration of the position adjusting unit 37 can be easily understood. It is indicated by a one-dot chain line.

  The position adjusting plate 38 has a semicircular guide 46 extending on the top of a rectangular plate, and both ends are bent into an L-shaped cross section to form a reinforcing portion 45. A positioning hole 40 is formed in the lower part of the position adjustment plate 38 in the shape of an elongated groove, and a protrusion 41 provided on the mounting bracket 33 is inserted into the positioning hole 40 so that the position adjustment plate 38 is formed in the mounting bracket 33. Installed. A screw hole is formed below the positioning hole 40, and is fixed to the side plate formed on the photosensitive drum 19 side of the mounting bracket 33 with a screw 42. The guide portion 46 formed at the upper portion of the position adjusting plate 38 is provided with a guide hole 43 formed in a horizontally long oval shape.

  The cam member 39 includes a knob portion 39a formed in a cylindrical shape, a cylindrical cam portion 39b that protrudes eccentrically from the center of the knob portion 39a on the back surface of the knob portion 39a, and a knob portion 39a that protrudes from the cam portion 39b. A cylindrical insertion portion 39c formed concentrically with the center of the knob 39 and an operation portion 39d fixed to the periphery of the knob portion 39a and disposed along the central axis of the knob portion 39a. The cam member 39 is rotatably mounted by being inserted from the exposure head 21 side into an attachment hole 44 formed in the vertical portion of the base frame 35 with the insertion portion 39c. At that time, the guide hole 43 of the position adjusting plate 38 is loosely fitted in the cam portion 39b, and the semicircular outer periphery of the guide portion 46 is set so as to be in sliding contact with the operation portion 39d. Accordingly, when the operation portion 39d is rotated along the outer periphery of the guide portion 46, the entire cam member 39 is rotated, but the cam portion 39b is formed eccentrically with respect to the knob portion 39a and the insertion portion 39c. Therefore, the contact portion with the guide hole 43 moves up and down as it rotates.

  In FIG. 5, the contact portion between the cam portion 39b and the guide hole 43 is set at the highest position. However, when the operation portion 39d is rotated clockwise, the position of the contact portion gradually increases as shown in FIG. As shown in FIG. 7, when the operation unit 39d is rotated clockwise to the limit as shown in FIG. 7, the position of the contact portion is set to the lowest position. Therefore, by rotating the operation portion 39d, the position adjustment plate 38 continuously moves up and down, and the vertical position of the mounting bracket 33 to which the position adjustment plate 38 is fixed is adjusted.

  When the vertical position of the mounting bracket 33 is adjusted using the pair of position adjusting means 37, for example, when the scanning line S is inclined as shown in FIG. 3, the position adjustment of the start end side Ls is performed as shown in FIG. The operation portion 39d is adjusted so that the plate 38 is lowered, and the operation portion 39d is adjusted so that the position adjustment plate 38 on the end side Le is raised to a state indicated by a dotted line, so that the scanning line becomes the rotation center line. It can be easily adjusted along. Since the position adjustment plate 38 moves up and down continuously by the rotation of the operation portion 39d, fine adjustment is possible, and a pair of position adjustment means are provided on the start end side and the end end side of the laser light emission region. The adjustment work can be easily and accurately performed by adjusting both in parallel as compared with the case of using only one adjustment means.

  FIG. 9 shows an enlarged cross-sectional view on a plane passing through the screw holes 36 a and 36 b in a state where the fixing portion 36 of the mounting bracket 33 is fixed to the side frame 50. A holding screw 51 is screwed into the screw hole 36 a through an attachment hole 52 formed in the side frame 50. The attachment hole 52 is formed to have a larger diameter than the screw hole 36a, the fitting portion 53 of the holding screw 51 is fitted therein, and the screw portion 54 fixed to the fitting portion 53 is formed in the screw hole 36a. It is screwed. Therefore, the fixed portion 36 is not fixed to the mounting hole 52 but is rotatable.

  On the other hand, a fixing screw 55 is screwed into the screw hole 36b through an attachment hole 56 formed in the side frame 50. The fixing screw 55 is screwed into both the attachment hole 56 and the screw hole 36 b to fix the fixing portion 36 to the side frame 50.

  The mounting bracket 33 is temporarily fixed to the side frame 50 with the holding screw 51 in a rotatable state, and the mounting bracket 33 is completely attached to the side frame 50 with the fixing screw 55 after the tilt position adjustment by the position adjusting means 37 as described above. If the mounting bracket 33 is fixed, the mounting bracket 33 can be stably maintained in an adjusted state.

1 is a schematic sectional view of an entire image forming apparatus according to an embodiment of the present invention. It is a perspective view regarding the attachment part of an exposure head. It is explanatory drawing which shows the relationship between the axis line of the rotating shaft of a photoconductive drum, and a scanning line. It is an expanded sectional view of the position adjustment means part in the AA position of FIG. FIG. 3 is an enlarged view of a position adjusting unit viewed from the photosensitive drum side. FIG. 3 is an enlarged view of a position adjusting unit viewed from the photosensitive drum side. FIG. 3 is an enlarged view of a position adjusting unit viewed from the photosensitive drum side. It is explanatory drawing which shows adjustment operation | movement of a position adjustment means. It is sectional drawing which shows the fixed state in the fixing | fixed part of a mounting bracket.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Recording part 3 Paper feeding part
21 Exposure head
33 Mounting bracket
35 Base frame
36 Fixed part
36a Screw hole
36b screw hole
37 Position adjustment means
38 Position adjustment plate
39 Cam member
39a Knob
39b Cam part
39c plug
39d Operation unit
43 Guide hole
44 Mounting hole
45 Reinforcement
46 Guide section
47 Locking part
50 side frame
51 Retaining screw
55 Fixing screw

Claims (2)

  An image carrier, charging means for charging the surface of the image carrier, exposure means for scanning the charged surface of the image carrier with a laser beam to form an electrostatic latent image, and the surface of the image carrier A developing means for attaching a toner to the electrostatic latent image formed on the surface to make a visible image; and a control means for controlling the means so as to rotate the image carrier and form an image on a sheet. In the image forming apparatus, the exposure unit is moved in a direction that intersects a plane including the rotation center line of the image carrier and is disposed on each of the start end side and the end end side of the laser light emission region of the exposure unit. An image forming apparatus comprising a pair of position adjusting means for adjusting a scanning direction of a laser beam so as to be along a rotation center line of the image carrier.   The position adjusting means includes a cam member rotatably attached to a main body frame, and a position adjusting member attached to the exposure means and having a hole portion loosely fitted to the cam member. The image forming apparatus according to claim 1, wherein the position adjusting member is moved by the rotation of the lens and the exposure unit is moved.

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