JP2017116601A - Optical scanner and image formation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical scanner and an image formation device with which it is possible to suppress a change in the posture of a rotary deflector.SOLUTION: In substantially the central portion of the scanner attachment part 182 of an optical housing that stores a light source and a rotary deflector such as a polygon scanner is formed an opening 80d that is opened in a rectangular shape. Inside the opening 80d is disposed a bearing support boss part such as a cylindrical bearing support part 80b which a bearing part for receiving the revolving shaft of a polygon mirror of the rotary deflector engages. A plurality of ribs 80e are included that extend in a direction orthogonal to the direction of the revolving shaft from the outer circumferential surface of the bearing support boss part parallel to the direction of the revolving shaft of the rotary deflector, and are connected to a boss part such as a fastening part 80c located in this direction of extension. Each of the ribs 80e extends in a direction inclined to the direction of the normal line of the outer circumferential surface of the bearing support boss part.SELECTED DRAWING: Figure 11

Description

  The present invention relates to an optical scanning device and an image forming apparatus.

  As an image forming apparatus such as a copying machine, a printer, or a facsimile, a latent image is formed on a latent image carrier by irradiating the latent image carrier with writing light according to image information by deflecting scanning. It is known that an image is developed to obtain an image. In general, an optical scanning apparatus that deflects and scans writing light is a latent image of writing light that is deflected and scanned by a polygon scanner that is a rotating deflector including a polygon mirror that is a rotating polygon mirror that deflects and scans writing light from a light source. An optical system component such as an imaging lens for imaging on the surface of the carrier is provided. These components are housed in a housing, and the housing is covered and sealed with a cover member or the like so that dust and dust do not adhere to optical system components such as an imaging lens.

  Patent Document 1 describes an optical scanning device in which a bearing support portion that supports a bearing that receives a rotation shaft of the polygon mirror is provided on a bottom surface portion of the housing. The bearing support portion is a cylindrical boss protruding outward from the outer surface of the bottom surface portion, and the bearing is supported by the bearing support portion by fitting the bearing into the bearing support portion. A plurality of ribs extending from the normal direction from the outer peripheral surface parallel to the rotation axis of the bearing support portion are provided on the outer surface of the bottom surface portion. These ribs extend straight, and are connected to bosses that protrude outward from the bottom surface located in the direction in which the ribs extend.

  When the writing light is deflected, the polygon mirror rotates at high speed, the bearing generates heat, and the bearing support portion is thermally expanded by the heat of the bearing. Due to the thermal expansion of the bearing support portion, the bearing support portion may fall down. As a result, the posture of the polygon scanner is changed, and optical performance may be deteriorated such that optical scanning cannot be performed at a predetermined position of the latent image carrier.

  In order to solve the above problems, the present invention provides a light source that emits light, a rotating deflector that reflects and deflects light emitted from the light source while rotating, and rotates the rotating deflector. A bearing support boss portion having a fitting hole for fitting with a bearing portion that receives the shaft, and an outer peripheral surface of the bearing support boss portion that is parallel to the rotation axis direction of the rotary deflector and perpendicular to the rotation axis direction A plurality of ribs extending in a direction and connected to a boss portion positioned in the extending direction; and a housing that houses the light source and the rotary deflector. The bearing support boss portion extends in a direction inclined with respect to the normal line direction of the outer peripheral surface.

  According to the present invention, it is possible to suppress a change in posture of the rotary deflector.

1 is a diagram schematically illustrating an image forming apparatus according to an embodiment. (A) is a perspective view of a process cartridge, (b) is sectional drawing of a process cartridge. 1 is a schematic configuration diagram of an optical writing device. The perspective view which looked at the optical writing device from the bottom. The perspective view which looked at the polygon scanner from the lower side. The perspective view which shows a mode that a polygon scanner is attached to an optical housing. The figure explaining attachment to the copying machine of an optical writing device. The top view which shows a support plate. The expansion perspective view near the 2nd positioning surface. The perspective view which shows the state by which the optical writing device was positioned and fixed to the support plate. The figure explaining the connection with the bearing support part of the rib of this embodiment. The figure which shows a deformation | transformation of each rib when a bearing support part thermally expands. The figure which shows the result of having simulated the deformation | transformation of the rib by the heat of a bearing part about a comparative example. The figure which shows the result of having simulated the deformation | transformation of the rib by the heat | fever of a bearing part about this embodiment. Schematic which shows the modification 1 of a rib. The schematic perspective view which shows the modification 2 of a rib. The schematic plan view which shows the modification 2 of a rib. The figure explaining the inclination angle with respect to the normal line direction of a rib, and the ease of rotating a bearing support part. FIG. 6 is a schematic configuration diagram of a modified image forming apparatus. FIG. 9 is a schematic cross-sectional view showing a configuration of a modified example of an optical writing device. Schematic when the optical writing apparatus of a modification is seen from the top.

FIG. 1 is a diagram showing an outline of an image forming apparatus according to an embodiment of the present invention.
An image reading apparatus 200 is attached to the upper part of the apparatus main body 100 of the copying machine as an image forming apparatus.

A process cartridge 1 is provided inside the apparatus main body 100.
FIG. 2A is a perspective view of the process cartridge, and FIG. 2B is a cross-sectional view of the process cartridge.
As shown in FIG. 2B, the process cartridge 1 includes a photosensitive member 10 that is a latent image carrier, a charging device 11 that is disposed around the photosensitive member 10 and that acts on the photosensitive member 10, and a developing device. 12 and a cleaning device 14. The process cartridge 1 is detachably attached to the apparatus main body 100. Since the photosensitive member 10, the charging device 11, the developing device 12, and the cleaning device 14 are unitized as the process cartridge 1, replacement and maintenance work is facilitated. Further, it is possible to maintain the positional accuracy between the members with high accuracy, and to improve the quality of the formed image.

  The charging device 11 serving as a charging unit applies a charging bias to apply a charge to the surface of the photoconductor 10 to uniformly charge the photoconductor 10, and an adhering material such as toner attached to the surface of the charging roller 11a. And a removing roller 11b to be removed.

  The developing device 12 as developing means has a first agent storage chamber V1 in which a first conveying screw 12b as developer conveying means is disposed. Further, it also has a second agent storage chamber V2 in which a second conveying screw 12c as a developer conveying means, a developing roller 12a as a developer carrying member, a doctor blade 12d as a developer regulating member, and the like are disposed. .

  In these two agent storage chambers V1 and V2, a developer which is a two-component developer including a magnetic carrier and a negatively chargeable toner is included. The first transport screw 12b is rotationally driven by a driving unit to transport the developer in the first agent storage chamber V1 to the front side in the drawing. Then, the developer transported to the front side end portion of the first agent storage chamber V1 in the drawing by the first transport screw 12b enters the second agent storage chamber V2.

  The 2nd conveyance screw 12c in the 2nd agent storage chamber V2 is rotated by a drive means, and conveys a developer to the back side in the figure. In this manner, the developing roller 12a is disposed in a posture parallel to the second conveying screw 12c above the second conveying screw 12c that conveys the developer. The developing roller 12a includes a magnet roller fixedly disposed in a developing sleeve made of a non-magnetic sleeve that is rotationally driven.

  A part of the developer conveyed by the second conveying screw 12c is pumped up to the surface of the developing roller 12a by the magnetic force generated by the magnet roller in the developing roller 12a. Then, after the layer thickness is regulated by a doctor blade 12d arranged so as to maintain a predetermined gap from the surface of the developing roller 12a, the layer thickness is regulated and conveyed to a developing region facing the photoconductor 10, and on the photoconductor 10 Toner is attached to the electrostatic latent image. By this adhesion, a toner image is formed on the photoreceptor 10. The developer that has consumed toner by development is returned to the second conveying screw 12c as the surface of the developing roller 12a moves. Then, the developer transported to the end of the second agent storage chamber V2 by the second transport screw 12c returns to the first agent storage chamber V1. In this way, the developer is circulated and conveyed in the developing device.

  Further, the developing device 12 includes a toner concentration sensor that detects the toner concentration of the developer in the first agent storage chamber V1. The toner concentration sensor measures the toner concentration of the developer from the magnetic permeability of the developer. When the toner concentration is low, the magnetic carrier is concentrated, so that the magnetic permeability is increased. When the value measured by the toner density sensor 124 exceeds the target value (threshold value), toner is supplied from the toner bottle 20 shown in FIG. 1, and the toner density is controlled to a constant density. The target value is determined based on the detection result obtained by detecting the toner adhesion amount of the toner pattern formed on the photoconductor 10 with an optical sensor.

  By such an operation, control is performed so that the reference pattern density on the photosensitive member is kept constant. However, when the toner in the toner bottle 20 runs out, the density reduction cannot be suppressed. In such a situation, the detection result of the toner pattern by the optical sensor is not improved despite the operation of supplying the toner from the toner bottle 20 for a predetermined period. Accordingly, when the toner pattern detection result by the optical sensor is not improved despite the operation of supplying the toner from the toner bottle 20, it is determined that the toner has run out (toner end) (or estimation determination). To do.

  In addition, after the toner end is determined, the toner bottle 20 is replaced, and when the toner end recovery for supplying the toner in the replaced toner bottle 20 to the developing device 12 is performed, the following operation is performed. That is, the developing roller 12a and the conveying screws 12b and 12c are rotated in order to satisfactorily mix the replenished toner and the developer. At this time, in order to prevent the developer on the developing roller 12a from sliding unevenly, the photosensitive member 10 is also driven to rotate.

  The cleaning device 14 serving as a cleaning unit includes a cleaning blade 14 a that contacts the surface of the photoconductor 10 and scrapes off transfer residual toner attached to the photoconductor 10. In addition, a toner collection coil 14b is provided that conveys the collected toner collected in the collection unit W and collected by the cleaning blade 14a. The collected toner conveyed by the toner collecting coil 14b is conveyed to the developing device 12 or the waste toner bottle 35 by the toner conveying device.

  A transfer device 17 as a transfer unit shown in FIG. 1 includes a transfer roller 16, and the transfer roller 16 is pressed against and brought into contact with the peripheral surface of the photoconductor 10. A fixing device 24 as a fixing unit is provided above the transfer device 17. The fixing device 24 includes a heating roller 25 and a pressure roller 26. Further, the apparatus main body 100 is provided with an optical writing device 21 serving as a latent image forming unit. The optical writing device 21 includes a light source, a scanning rotary polygon mirror, a polygon motor, an fθ lens, and the like. Further, the apparatus main body is provided with a plurality of sheet cassettes 22 for storing sheets S such as transfer paper and OHP film.

  When copying using the apparatus configured as described above, the user presses the start switch. Then, first, the contents of the original set on the image reading apparatus 200 are read. At the same time, the photosensitive member 10 is rotated by the photosensitive member driving motor, and the surface of the photosensitive member 10 is uniformly charged by the charging device 11 using the charging roller 11a. Next, a writing process is executed using the laser beam writing device 21 by irradiating laser light according to the content of the original read by the image reading device 200. Then, after forming an electrostatic latent image on the surface of the photoconductor 10, toner is attached using the developing device 12 to visualize (develop) the electrostatic latent image.

  At the same time as the user presses the start switch, the selected sheet S is sent out by the calling roller 27 from the multistage sheet cassette 22. Next, the sheet is separated one by one by the supply roller 28 and the separation roller 29 and sent to the supply path R1. The sheet S sent to the supply path R <b> 1 is conveyed by the sheet conveyance roller 30 and is abutted against the registration roller 23 and stopped. The transfer roller 16 is sent to a transfer nip formed in contact with the photoconductor 10 in accordance with the rotation timing of the toner image that is visualized on the photoconductor 10.

  The toner image on the photoreceptor 10 is transferred to the sheet S fed to the transfer nip by the transfer device 17. The residual toner on the photoconductor 10 after image transfer is removed and cleaned by the cleaning device 14, and the residual potential on the photoconductor 10 from which the residual toner has been removed is removed by the static eliminator. In preparation for the next image formation starting from the charging device 11.

  On the other hand, the sheet S after the image has been transferred is guided to the heat fixing device 24, passed between the heating roller 25 and the pressure roller 26, and conveyed to these rollers while applying heat and pressure to the toner. The image is fixed. Thereafter, the sheet S on which the image has been fixed is discharged onto the discharge stack unit 32 by the discharge roller 31 and stacked.

FIG. 3 is a schematic configuration diagram of the optical writing device 21.
The optical writing device 21 includes an LD unit 40, a collimating lens 52, an aperture 54, a cylindrical lens 53, a polygon scanner 50, a scanning lens (fθ lens) 43, a synchronizing mirror 62, a synchronizing lens 63, and the like. These are housed in an optical housing 80 as a housing. The optical housing 80 has a box shape with an open upper surface, and the upper surface is covered with a cover member 70 (see FIG. 4) to prevent dust from entering the optical writing device. The LD unit 40 is attached to the side surface of the optical housing 80. The collimating lens 52, the aperture 54, the cylindrical lens 53, the polygon scanner 50, the scanning lens (fθ lens) 43, the synchronization mirror 62, and the synchronization lens 63 are attached to a bottom surface portion 180 that is an attachment surface portion of the optical housing 80. The optical housing 80 is made of a thermoplastic resin containing glass fibers.

  The LD unit 40 includes an LD control substrate 42 to which a light source 41 composed of a semiconductor laser for irradiating the photoconductor 10 with a light beam L and a photo IC are fixed. The light source 41 and the photo IC are soldered to the LD control board 42.

  A polygon scanner 50 as a rotating deflector has a polygon mirror 49 which is a rotating polygon mirror having a regular polygonal prism shape. The polygon scanner 50 is fastened by screws in the soundproof wall 55 of the optical housing 80. The polygon mirror 49 has reflecting mirrors on its six side surfaces. In the present embodiment, the polygon mirror 49 has a regular hexagonal prism shape and has six reflecting mirrors on the side surface. However, the present invention is not limited to this.

  The light beam L emitted from the light source 41 of the LD unit 40 is converted into a parallel light beam by the collimating lens 52. Thereafter, after being shaped by the aperture 54, the light passes through the cylindrical lens 53 and is condensed in the sub-scanning direction (direction corresponding to the direction of movement of the photosensitive member surface on the photosensitive member surface). Then, the light enters the polygon mirror 49. The light beam L incident on the polygon mirror 49 is deflected in the main scanning direction (direction corresponding to the axial direction on the surface of the photosensitive member) while being reflected by the reflecting mirror of the polygon mirror 49. Next, the light beam deflected in the main scanning direction at a constant angular velocity by the polygon mirror 49 passes through the soundproof glass 51 and enters the scanning lens 43. The scanning lens 43 converts the moving speed in the deflection direction of the light beam deflected in the main scanning direction at a constant angular velocity by the polygon mirror 49 to a constant velocity. After passing through the scanning lens 43, it is folded back by the synchronization mirror 62, condensed by the synchronization lens 63, and enters the photo IC of the LD unit 40.

  When the photo IC detects the light beam L, a synchronization signal is output. Then, the light beam L based on the image data emitted from the light source 41 in synchronization passes through the collimating lens 52, the aperture 54, the cylindrical lens 53, the polygon mirror 49, and the scanning lens 43 in the same manner as described above. The light beam L passing through the scanning lens 43 passes through a dustproof glass provided so as to cover the opening formed on the side surface of the optical housing 80 and optically scans the surface of the photoreceptor 10.

  In addition, a second scanning lens may be disposed on the optical path of the light beam from the scanning lens 43 to the photoconductor 10. Further, a reflection mirror may be provided on the optical path of the light beam from the light source 41 to the polygon mirror of the polygon scanner 50.

FIG. 4 is a perspective view of the optical writing device 21 as viewed from below.
In the following description, the rotation axis direction of the polygon mirror 49 is set as the Z axis, the direction from the polygon mirror 49 toward the photoconductor 10 is set as the X axis, and the direction perpendicular to the Z-X plane is set as the Y axis.
The optical writing device 21 is a detachable unit that is detachably attached to the apparatus main body 100 of the copying machine. Specifically, in FIG. 1, it is configured to be detachable with respect to the apparatus main body in a direction perpendicular to the paper surface (Y-axis direction in FIG. 4).

  As shown in FIG. 4, on the lower surface of the optical housing 80, there are three receiving portions 81, 82, 83 as positioned portions, and projecting portions 85, 86 as positioned portions.

  The first receiving portion 81 is provided on the lower surface of a first fixing portion 87 (described later) provided at the center portion in the X direction at the end portion on the near side in the mounting direction of the optical writing device 21. The second receiving portion 82 is a lower surface of the second fixing portion 88 provided at one end in the X direction (on the opposite side to the light beam emitting side of the optical writing device 21) at the end on the back side in the mounting direction of the optical writing device 21. Is provided. The third receiving portion 83 is provided on the lower surface of the third fixing portion 89 provided at one end in the X direction (on the light beam emitting side of the optical writing device 21) at the end on the back side in the mounting direction of the optical writing device 21. ing. Each receiving portion 81, 82, 83 protrudes slightly from the lower surface of each fixed portion, and its top surface has a high degree of flatness. Further, the positions in the Z direction based on a certain portion of the optical writing device of each of the receiving portions 81, 82, 83 are the same position (the same height).

  The scanner mounting portion 182 of the optical housing 80 protrudes below the bottom surface portion 180 of the optical housing. In the substantially central portion of the scanner mounting portion 182, an opening 80 d that is opened in a rectangular shape is formed. Formed on the square of the opening 80d is a cylindrical fastening portion 80c having a thread groove formed on the inner peripheral surface for fixing the control substrate 50b of the polygon scanner 50.

  In addition, a cylindrical bearing support portion 80b into which a bearing portion 50a that receives the rotation shaft of the polygon mirror 49 of the polygon scanner 50 is fitted is formed in the opening 80d. The bearing portion 50a is fitted to the bearing support portion 80b, and the bottom surface of the bearing portion 50a is exposed. Further, a rib 80e extending from each fastening portion 80c toward the bearing support portion 80b and connected to the bearing support portion 80b is formed, and the bearing support portion 80b is connected to and supported by the optical housing 80 by the rib 80e. .

FIG. 5 is a perspective view of the polygon scanner 50 as viewed from below.
As shown in FIG. 5, the bearing portion 50a that receives the rotation shaft of the polygon mirror 49 of the polygon scanner 50 has a cylindrical shape with one end closed, and is attached to the control board 50b so as to penetrate the control board 50b. Yes. The control board 50b. An electric circuit is provided for controlling a motor for rotationally driving the polygon mirror.

FIG. 6 is a perspective view showing how the polygon scanner 50 is attached to the optical housing 80.
First, the polygon scanner 50 is positioned in the optical housing 80 by fitting the bearing portion 50a penetrating the control board 50b into the bearing support portion 80b serving as the bearing support boss portion. In the four corners of the control board 50b, through holes 500c through which the screws 50c pass are formed. The screws 50c are passed through the through holes 500c, and the screws 50c are fixed to the fastening portions 80c provided at the four corners of the opening 80d. As a result, the polygon scanner 50 is fastened to the optical housing 80. When the polygon scanner 50 is fastened to the optical housing 80, the opening 80d is covered with the control board 50b. Thereby, it is possible to suppress dust and dust from entering the optical housing from the opening 80d.

  Since the polygon mirror 49 rotates at high speed when deflecting and scanning the writing light, the lubricant in the bearing portion generates heat due to friction with the rotating shaft of the polygon mirror 49, and the bearing portion 50a generates heat. The electronic control component mounted on the control board 50b also generates heat. The inside of the optical scanning device becomes high temperature due to heat generated by the bearing portion 50a as the heat generating portion and the electronic control components of the control board. As a result, optical parts such as lenses and mirrors are thermally deformed, causing a magnification deviation and the like, which may cause a problem of degrading an image.

  However, in the present embodiment, the lower surface of the bearing portion 50a of the polygon scanner 50 is exposed to the outside from the bearing support portion 80b. Thereby, a part of the heat of the bearing portion 50 a is directly radiated to the outside of the optical housing 80. The control board 50b is also exposed to the outside from the opening 80d. Thereby, a part of the heat of the control board 50b is directly radiated to the outside of the optical housing. As a result, the temperature rise inside the optical housing can be satisfactorily suppressed.

FIG. 7 is a diagram for explaining attachment of the optical writing device 21 to the copying machine.
The optical writing device 21 is positioned and supported in the main body of the copying machine by a support plate 90. The support plate 90 is positioned and fixed to the front side plate 100a and the rear side plate 100b of the apparatus main body.

FIG. 8 is a plan view showing the support plate 90.
The support plate 90 has three positioning surfaces 91, 92, 93 and two positioning holes 95, 96. The first positioning surface 91 is provided at a location facing the first receiving portion 81 when the optical writing device 21 is mounted on the apparatus main body. The second positioning surface 92 is provided at a location facing the second receiving portion 82 when the optical writing device 21 is mounted on the apparatus main body. Further, the third positioning surface 93 is provided at a location facing the third receiving portion 83 when the optical writing device 21 is mounted on the apparatus main body. Each positioning surface 91, 92, 93 is provided so as to slightly protrude from the support plate 90, and each positioning surface 91, 92, 93 has a highly accurate flatness. Moreover, the height from the support plate 90 of each positioning surface 91,92,93 is the same.

  The first positioning hole 95 is provided at a position where the first protrusion 85 fits when the optical writing device 21 is mounted on the apparatus main body, and extends in the mounting direction (Y-axis direction) of the optical writing device 21. It has a hole shape. The second positioning hole 96 is provided at a position where the second protrusion 86 is fitted when the optical writing device 21 is mounted on the apparatus main body, and is approximately the same diameter (slightly larger) as the diameter of the second protrusion 86. It has a round hole shape with a diameter.

  When the optical writing device 21 is mounted on the apparatus main body, the receiving portions 81, 82, 83 of the optical housing 80 come into contact with the corresponding positioning surfaces 91, 92, 93 of the support plate 90. The heights in the Z direction of the receiving portions 81, 82, and 83 and the heights in the Z direction of the positioning surfaces 91, 92, and 93 are aligned, and the flatness of the contact portion is also increased. Therefore, the optical housing 80 is positioned with respect to the apparatus main body in the Z-axis direction by the contact portions 81, 82, 83 coming into contact with the corresponding positioning surfaces 91, 92, 93. Further, the optical writing device 21 is positioned with respect to the apparatus main body about the X-axis direction and the Y-axis direction by the contact portions 81, 82, 83 coming into contact with the corresponding positioning surfaces 91, 92, 93, respectively. The

  Further, as the optical writing device 21 is attached, the first protrusion 85 is fitted into the first positioning hole 95. By fitting the first protrusion 85 in the positioning hole 95, the optical writing device 21 is positioned in the X-axis direction with respect to the apparatus main body.

  Further, when the optical writing device 21 is attached to the apparatus main body, the second protrusion 86 is fitted into the second positioning hole 96. As described above, the second positioning hole 96 has substantially the same diameter as the diameter of the second protrusion 86. Therefore, when the second protrusion 86 is fitted in the second positioning hole 96, the optical writing device 21 is positioned in the Y-axis direction with respect to the apparatus main body. Further, the protrusions 85 and 86 are fitted in the corresponding positioning holes 95 and 96, respectively, so that the optical writing device 21 is positioned around the Z-axis direction with respect to the apparatus main body.

  Further, as shown in FIG. 8, the support plate 90 has a first leaf spring attachment portion 97 to which a leaf spring for fixing the first fixing portion 87 of the optical writing device 21 to the device main body is attached. Yes. Moreover, it has the 2nd leaf | plate spring attachment part 98 to which the leaf | plate spring for fixing the 2nd fixing | fixed part 88 to an apparatus main body is attached. The first leaf spring attaching portion 97 is provided so as to be adjacent to the back side of the first positioning surface 92 in the mounting direction of the optical writing device 21 (the direction of arrow M in the figure). The second leaf spring mounting portion 98 is provided so as to be adjacent to the back side of the second positioning surface 93 in the mounting direction of the optical writing device 21. Further, a screw hole 91 a is provided in the center of the first positioning surface 91.

  Further, an opening 99 is formed at a location facing the scanner mounting portion 182 (see FIG. 4) of the optical housing 80 when the optical writing device 21 of the support plate 90 is mounted on the apparatus main body.

FIG. 9 is an enlarged perspective view of the vicinity of the second positioning surface 92. (A) is a figure which shows a mode that the optical writer 21 is mounted | worn with the apparatus main body, (b) is a figure which shows a mode when the optical writer 21 is mounted | worn with the apparatus main body.
As shown in FIG. 9, a leaf spring 120 is attached to the second leaf spring attachment portion 98 of the support plate 90 shown in FIG. The tip of the leaf spring 120 is in contact with the second positioning surface 92.

  As shown in FIG. 9A, when the optical writing device 21 is attached to the apparatus main body, the second fixing portion 88 of the optical housing 80 enters between the leaf spring 120 and the second positioning surface 92. . As a result, as shown in FIG. 9B, the second fixing portion 88 is pressed and fixed to the second positioning surface 92 side by the leaf spring 120.

  Similarly to the second fixing portion 88, the third fixing portion 89 of the optical housing 80 is pressed and fixed to the third positioning surface 93 side by the leaf spring.

FIG. 10 is a perspective view showing a state in which the optical writing device 21 is positioned and fixed to the support plate 90.
The first fixing part 87 of the optical writing device 21 is provided with a screw through hole 87a (see FIG. 4). When the optical writing device 21 is positioned on the support plate 90, the screw 91b is inserted into the screw through hole 87a, and the screw 91b is screwed into the screw hole 91a shown in FIG. As described above, the first fixing portion 87 is fixed to the support plate 90.
Further, both ends in the X-axis direction of the support plate 90 are bent perpendicularly to the Z-axis direction, and side portions 98a and 98b are formed. One side surface 98b is formed with a beam passage opening 198b for allowing the light beam emitted from the optical writing device 21 to pass therethrough.

Next, features of the present embodiment will be described.
As described above, when the writing light is deflected and scanned, the polygon mirror 49 rotates at a high speed, so that the bearing portion 50a generates heat. The bearing support 80b is heated by the heat of the bearing 50a, and the bearing support 80b is thermally expanded. The bearing support portion 80b tends to spread outward due to thermal expansion of the bearing support portion 80b. In the present embodiment, the bearing support 80b is provided in the opening 80d, and the opening is formed so as to surround the bearing support 80b. As a result, the influence of the thermal expansion of the bearing support portion 80b hardly reaches the outside of the opening 80d, and the parts other than the scanner mounting portion 182 of the optical housing 80 are deformed by the influence of the thermal expansion of the bearing support portion 80b. Can be suppressed.

  Further, due to the thermal expansion of the bearing support 80b, the rib 80e having one end connected to the outer periphery of the bearing support 80b is pushed outward, and the influence of the thermal expansion of the bearing support 80b is connected to the other end of the rib. It extends to the fastening portion 80c. However, when the control board 50b of the polygon scanner 50 is fastened to the fastening portion 80c, the control board 50b functions as a reinforcing member. As a result, it is possible to suppress the fastening portion 80c from spreading due to the thermal expansion of the bearing support portion 80b, and the bearing support portion 80b is located outside the fastening portion 80c (on the side away from the bearing support portion 80b). It is possible to suppress the influence of thermal expansion. In particular, the reinforcement effect can be enhanced by making the control board 50b made of iron.

  However, the rib 80e is affected by the thermal expansion of the bearing support portion 80b, and a force that pushes it outward is applied. Although this force reaches the fastening portion 80c, as described above, the fastening portion 80c is reinforced by the control board 50b, and therefore hardly moves outward. Therefore, the rib 80e is deformed to absorb the thermal expansion of the bearing support portion 80b.

  At this time, if the rib 80e is deformed in the vertical direction (Z direction) which is the rotation axis direction of the polygon mirror 49, the bearing support portion 80b may be inclined. Specifically, if each rib 80e is deformed by the same amount in one of the vertical directions, the bearing support portion 80b will not tilt. However, structurally, if the length of each rib 80e differs, the deformation amount of each rib will differ. In this embodiment, the optical housing is molded by resin injection molding. However, if there is a weak portion of the rib due to insufficient filling or the like, the rib is deformed from the weak portion, and the deformation is different from other ribs. In some cases. Due to factors such as these, the bearing support portion 80b is inclined. When the bearing support portion 80b is inclined, the bearing portion 50a fitted to the bearing support portion 80b is inclined, the rotation axis of the polygon mirror 49 received by the bearing portion 50a is inclined, and the polygon mirror 49 is inclined. When the polygon mirror 49 is tilted, it becomes impossible to optically scan the specified position of the photoconductor 10, or the scanning line optically scanned onto the photoconductor is tilted with respect to the moving direction of the photoconductor surface, so that a good image can be formed. There is a risk of disappearing.

  Thus, in the present embodiment, the connection of the rib 80e to the bearing support portion 80b is devised so that the rib 80e is hardly deformed in the vertical direction due to the thermal expansion of the bearing support portion 80b.

FIG. 11 is a diagram illustrating the connection of the rib 80e of the present embodiment with the bearing support portion 80b.
As shown in FIG. 11, each rib 80e is connected to the outer peripheral surface of the bearing support portion 80b at an angle θ with respect to the normal direction of the outer peripheral surface of the cylindrical bearing support portion 80b. Further, each rib 80e is inclined at an angle θ in the clockwise direction in the figure with respect to the normal direction in the connection portion R of the rib 80e with the bearing support portion 80b.

FIG. 12 is a view showing deformation of each rib 80e when the bearing support portion 80b is thermally expanded.
When the bearing support portion 80b is thermally expanded, a force is applied to each rib 80e in a direction parallel to the bottom surface of the optical housing (parallel to the XY plane). This force is a bending force for bending the rib 80e. The rib 80e has an elongated shape and has low bending rigidity. Therefore, each rib 80e is easily bent in a direction parallel to the bottom surface of the optical housing, and absorbs thermal expansion of the bearing support portion 80b. Thereby, it can suppress that each rib 80e deform | transforms into an up-down direction with the thermal expansion of the bearing support part 80b.

  The rib 80e also rises in temperature due to the heat of the control board 50b and the heat conducted from the bearing support 80b, and expands due to thermal expansion. In the present embodiment, as described above, each rib is inclined in the same direction with respect to the normal direction. As a result, the elongation due to the thermal expansion of each rib is absorbed by the bearing support portion 80b rotating counterclockwise in the drawing as indicated by an arrow A in the drawing. Thereby, it can also suppress that each rib 80e deform | transforms into the up-down direction by the thermal expansion of each rib 80e.

FIG. 13 is a diagram showing a result of simulating rib deformation due to heat of the bearing portion 50a in the comparative example, and FIG. 13A is a perspective view of the comparative example showing a state before heat is applied to the bearing portion 50a. FIG. FIG.13 (b) is a perspective view of the comparative example which shows the result of having simulated the deformation | transformation by the heat of the bearing part 50a, and FIG.13 (c) is a comparative example which has shown the result of having simulated the deformation | transformation by the heat of the bearing part 50a. FIG.
In the comparative example shown in FIG. 13, each rib 80e is extended in the normal direction from the connecting portion with the bearing support portion 80b.
In this comparative example, each rib 80e was deformed downward (in a direction away from the polygon scanner 50) with respect to the state before heat is applied to the bearing portion 50a indicated by the chain line in FIG. This is because the rib 80e is extended in the normal direction from the connecting portion with the bearing support portion 80b. Therefore, when the bearing support portion 80b is thermally expanded, a force in the same direction as the rib extending direction is applied to each rib 80e. (Axial force) is applied. Since the rib 80e is a rigid body and has a high axial rigidity, the rib 80e hardly deforms in the extending direction of the rib and cannot absorb the thermal expansion of the bearing support portion 80b. Therefore, the rib 80e is buckled in a direction orthogonal to the extending direction of the rib and absorbs the thermal expansion of the bearing support portion 80b.

  The temperature of the bearing support 80b is higher on the upper side than the lower side, which is the outer side of the optical housing, and the thermal expansion amount is higher on the upper side. Accordingly, each rib 80e is shaped so as to be pushed obliquely downward from the bearing support portion 80b. As a result, it is considered that each rib 80e is deformed (buckled) to the lower side perpendicular to the extending direction of the rib and absorbed the thermal expansion of the bearing support portion 80b. Further, in order to absorb the elongation due to the thermal expansion of the rib 80e, it is considered that the rib 80e itself is further deformed downward, and the downward deformation example is increased.

  Further, since the lengths of the ribs are different from each other, the way of deformation and the amount of deformation are different from each other, and the bearing support portion 80b is inclined as shown in FIG.

FIG. 14 is a diagram showing the result of simulating the deformation of the rib due to the heat of the bearing portion in the present embodiment.
FIG. 14A is a perspective view showing a state before heat is applied to the bearing portion 50a, and FIG. 14B is a perspective view showing the result of simulating deformation when heat is applied to the bearing portion 50a. FIG. 14C is a side view showing the result of simulating deformation when heat is applied to the bearing portion 50a.
As shown in FIG. 14 (b), in this embodiment, the rib 80e is hardly deformed downward, and the bearing support portion 80b is not inclined as shown in FIG. 14 (c). I understand. As described above, since the rib 80e is connected to be inclined with respect to the normal direction, the rib 80e is pushed in a direction different from the extending direction of the rib due to thermal expansion of the bearing support portion 80b. The force for pushing the rib by the thermal expansion of the bearing support portion 80b is a bending force for bending the rib. Since the ribs 80e are elongated and have low bending rigidity, each rib 80e is bent in a direction parallel to the bottom surface of the optical housing (parallel to the XY plane) to absorb the thermal expansion of the bearing support 80b. To do. As a result, it is possible to suppress the downward deformation of the rib. Further, the elongation due to the thermal expansion of the rib itself can be absorbed by the rotation of the bearing support portion 80b, which is considered to have suppressed the downward deformation of the rib.

  In the present embodiment, the optical housing 80 is molded by injection molding, and a resin containing glass fiber melted from a space corresponding to each rib 80e of the mold into a space corresponding to the bearing support portion 80b. The bearing support 80b is formed by pouring. In the present embodiment, as shown in FIG. 11, the inclination direction of each rib 80e is the same direction. Therefore, the direction of the molten resin flowing into the space corresponding to the bearing support portion from the space corresponding to each rib of the mold can be made the same. As a result, the molten resin can be smoothly poured into the space corresponding to the bearing support portion of the mold, the glass fibers contained in the molten resin are aligned, and the bearing support portion can have desired dimensions and characteristics.

  Further, as shown in FIG. 11, the thickness of the rib 80e and the thickness of the bearing support portion 80b are the same in order to suppress the influence of sink marks and the like. Each rib 80e is connected to the bearing support portion 80b from the tangential direction. Specifically, the outer surface of the rib 80e is connected to the bearing support 80b from the tangential direction of the outer peripheral surface of the bearing support 80b, and the inner surface of the rib 80e is the bearing support 80b. It connects from the tangent direction of the internal peripheral surface of the support part 80b. As a result, the molten resin can be poured more smoothly into the space corresponding to the bearing support portion of the mold, and the glass fibers contained in the molten resin can be well aligned. Can be characteristic.

  Further, by connecting each rib 80e from the tangential direction to the bearing support portion 80b, it becomes easier to rotate the bearing support portion 80b due to the elongation due to the thermal expansion of each rib, and the elongation due to the thermal expansion of each rib is increased. It can absorb well. Thereby, it can suppress favorably that each rib 80e deforms in the up-and-down direction.

  Next, a modified example will be described.

[Modification 1]
FIG. 15 is a schematic view showing Modification 1 of the rib 80e.
In the first modification, the connecting portions R of the ribs 80e with the bearing support portions 80b are equally spaced.
In this way, by connecting the connecting portions R of the ribs 80e with the bearing support portions 80b at equal intervals, the resin flowing into the spaces corresponding to the bearing support portions from the spaces corresponding to the ribs of the mold is moved in the moving direction. The distance to move to the space corresponding to the downstream rib can be made equal.

  Further, when the bearing support portion 80b thermally expands, the rib 80e acts to suppress the thermal expansion. By making the connecting portions of the ribs 80e to the bearing support portions 80b equally spaced, the drag generated at each connecting portion R is balanced, and the center of the bearing support portion 80b is shifted when the bearing support portions 80b are thermally expanded. Can be suppressed. Thereby, the stress concerning the bearing part 50a of a polygon scanner can be suppressed.

[Modification 2]
FIG. 16 is a schematic perspective view showing Modification 2 of the rib 80e, and FIG. 17 is a schematic plan view showing Modification 2 of the rib 80e.
In the second modification, the rib 80e is inclined with respect to the rotation axis direction of the polygon scanner. Specifically, the rib is inclined with respect to the rotation axis direction so that the inclination angle θ with respect to the normal direction becomes smaller toward the upper side of the rib 80e on the polygon scanner side. That is, the upper side is connected to the bearing support 80b in a state of standing on the outer peripheral surface of the bearing support 80b.

  As described above, the upper side on the polygon scanner side has a higher temperature and a larger amount of thermal expansion than the lower side. Therefore, the amount of thermal expansion of the upper bearing support portion and the rib is larger than that of the lower side. When the inclination angle θ of the rib 80e is the same in the vertical direction, the upper side where the thermal expansion is larger has a larger amount of rotation of the bearing support portion 80b than the lower side, and the rib 80e is around the extending direction of the rib. It will be twisted. As described above, when the rib 80e is twisted, the rib 80e has a restoring force that tries to return the twist, and the bearing support portion 80b may fall down due to the restoring force that tries to return the twist.

FIG. 18 is a diagram illustrating the ease of rotation of the bearing support portion 80b depending on the inclination angle of the rib 80e with respect to the normal direction. 18A is a diagram for explaining the case where the inclination angle of the rib 80e is θ1, and FIG. 18B is a diagram for explaining the case where the inclination angle of the rib 80e is an inclination angle θ2 larger than the above θ1. is there.
As shown in FIG. 18, when the inclination angle is larger, the bearing support 80b is pushed in by the restoring force due to the bending deformation due to the thermal expansion of the bearing support 80b or the thermal expansion of the rib itself. When the rib is bent, as shown by the chain line in the figure, when the inclination angle of the rib is larger than when the inclination angle of the rib is small, the vicinity of the connection portion of the rib with the bearing support portion is more You can see that it is close to the surface. As a result, when the rib inclination angle is larger, the direction of pushing the bearing support portion of the rib can be made closer to the tangential direction of the bearing support portion. As a result, the tangential component, which is the force for rotating the bearing support portion, of the force for pushing the bearing support portion of the rib becomes larger than when the inclination angle of the rib is small.

  Therefore, by making the lower side inclination angle larger than the upper side, even if the amount of thermal expansion is smaller than the upper side, the force for rotating the bearing support portion 80b by the rib 80e can be made substantially the same as the upper side, and the vertical direction The bearing support portion can be rotated by approximately the same amount. Thereby, it can suppress that a rib twists around the extending direction of a rib, and can suppress the fall of a bearing support part.

  In addition, as a result of simulation, depending on conditions, contrary to the above, when the upper inclination angle of the rib 80e is larger than the lower inclination angle, the bearing support portion 80b is rotated approximately in the vertical direction. In some cases it was possible. This is because the larger the tilt angle, the smaller the amount of deformation when the bearing support portion 80b is thermally expanded than when the tilt angle is small. Therefore, the force with which the bearing support portion 80b of the rib is pushed back is weaker when the inclination angle is larger than when the inclination angle is small. Therefore, the larger the inclination angle, the larger the tangential component of the force that pushes back the bearing support portion 80b of the rib, but the pushing force is weak. As a result, the bearing support of the rib with the smaller inclination angle of the rib The force for rotating the portion 80b (the tangential component of the force pushing back the rib) may be larger. In this case, the rib is tilted in the opposite direction to the above, and the angle of inclination on the upper side of the rib is made larger than the angle of inclination on the lower side. The force for rotating the support portion 80b can be made substantially the same as the upper side. As a result, the bearing support portion can be rotated substantially in the same direction in the vertical direction, the rib can be prevented from being twisted around the extending direction of the rib, and the bearing support portion can be prevented from falling.

Next, a modified example of the image forming apparatus will be described.
FIG. 19 is a schematic configuration diagram of a modified image forming apparatus.
The image forming apparatus according to this modification is a full-color image forming apparatus in which a plurality of four drum-shaped photoconductors 10Y, 10C, 10M, and 10K serving as latent image carriers are arranged in tandem. These photoconductors are configured as a part of the process cartridges 1Y, 1C, 1M, and 1K as image forming means. These process cartridges 1Y, 1C, 1M, and 1K sequentially correspond to the respective colors of yellow, cyan, magenta, and black, and create images of these colors.

  In the image forming apparatus of the modification of FIG. 19, there is an intermediate transfer belt 161 as a surface moving member that is supported and rotated by three support rollers 161a, 161b, 161c and the like. The process cartridges 1Y, 1C, 1M, and 1K are arranged at intervals from the upstream side in the order of the movement direction of the intermediate transfer belt 161 indicated by an arrow along the lower extending line of the intermediate transfer belt 161. ing.

  When forming a full-color image, toner images of respective colors are formed on the photoreceptors 10Y, 10C, 10M, and 10K provided in the process cartridges 1Y, 1C, 1M, and 1K, as described later. Next, these different color toner images are transferred to the intermediate transfer belt 161 along with the movement of the intermediate transfer belt 161 by the function of the primary transfer roller 16 as a transfer means disposed opposite to each photoconductor with the intermediate transfer belt 161 in between. The images are sequentially transferred onto the transfer belt 161. Specifically, a portion on the intermediate transfer belt 161 where the primary transfer roller 16 is in contact is called a transfer position, and transfer is performed at this transfer position.

The four superimposed transfer toner images are collectively transferred to the recording material as the final recording medium at the nip portion between the support roller 161a and the secondary transfer roller 162, and after passing between the fixing pair rollers of the fixing device 24, the conveyance roller Then, the paper is discharged onto the paper discharge stack unit 32 from the pair of paper discharge rollers. Thus, a full color image is obtained on the recording material.
The intermediate transfer belt 161 is configured such that the photoreceptor 10K is always in contact with the primary transfer roller 16 in order to adapt to the black image one-color formation mode. The other photoconductors are configured such that the intermediate transfer belt 161 contacts and separates by the function of a movable tension roller. A cleaning device 171 for removing residual toner on the intermediate transfer belt 161 is provided on the roller 161b.

  In FIG. 19, the process cartridges 1Y, 1C, 1M, and 1K differ only in the color of the toner to be handled, and the mechanical configuration and the image forming process are common. Therefore, the constituent members other than the photosensitive member are denoted by the same reference numerals, and a configuration and an image forming process will be described for an arbitrary image forming apparatus, for example, the process cartridge 1Y.

  Around the photosensitive member 10Y of the process cartridge 1Y, in the order of the clockwise rotation in the drawing, a charging device 11 as a charging unit for charging the photosensitive member 10Y, an irradiation position of the writing light L, and a developing device as a developing unit 12, a primary transfer roller 16, a cleaning device 14, and the like are disposed.

The writing light L is emitted from the optical writing device 21A as an optical scanning means, and is equipped with a light source, a coupling lens, a scanning lens, a mirror, a polygon scanner, and the like. The writing light L for each color is emitted from the optical writing device 21A toward each photoconductor, and the writing light L is irradiated to the writing position on the photoconductor 10Y to form an electrostatic latent image. Details will be described later.
For example, the developing device 12 of the process cartridge 1Y contains a yellow developer, and the latent image is visualized with a yellow image. The other process cartridges also store the developer of each color, and the latent image is visualized with the color of the stored developer.

At the time of image formation, the photoconductor 10Y rotates and is uniformly charged by the charging device 11, and an electrostatic latent image is formed by irradiation of the writing light L including yellow image information at the writing position. The latent image is visualized with yellow toner while passing through the developing device.
The yellow toner image on the photoreceptor 10 </ b> Y is transferred to the intermediate transfer belt 161 by the primary transfer roller 16. The yellow toner image on the intermediate transfer belt 161 is sequentially transferred onto the cyan toner image by the process cartridge 1C, the magenta toner image by the process cartridge 1M, and the black toner image by the process cartridge 1K. Thereby, a full-color toner image is formed.

  The sheet S is sent out from the sheet cassette 22 and the registration roller at a timing so that the superimposed toner image reaches the secondary transfer roller 162 at the same timing as the secondary toner reaches the secondary transfer roller 162. Then, as described above, the images are collectively transferred at the nip portion between the support roller 161a and the secondary transfer roller 162.

On the other hand, after the toner is removed by the cleaning device 14 after the transfer, the charge is removed by the charge removal lamp and prepared for the next image formation. Similarly, with respect to the intermediate transfer belt 161, residual toner and the like are removed by the cleaning device 171.
In the image forming apparatus according to the modified example, a toner image on each photoconductor is temporarily transferred onto an intermediate transfer belt 161, and this overlapped toner image is collectively transferred onto a sheet-like medium. Instead, a recording paper conveyance belt as a surface moving member is provided, and the recording material is carried by the recording paper conveyance belt. In this conveyance process, a color toner image is sequentially transferred from each photoconductor onto the recording material. Also good.

Next, a modified optical writing device 21A used in the modified image forming apparatus will be described.
FIG. 20 is a schematic cross-sectional view showing a configuration of a modification of the optical writing device 21A.
FIG. 21 is a schematic view of a modified optical writing device 21A as viewed from above.
The optical writing device 21A of the modification shown in the figure is a tandem writing optical system and adopts a scanning lens system, but can be applied to either a scanning lens system or a scanning mirror system.
The optical writing device 21A according to the modification includes optical elements such as a polygon scanner 50, various reflection mirrors, and various lenses. The polygon scanner 50 is provided substantially at the center of the optical writing device 21 </ b> A, and is disposed in a sealed space surrounded by the soundproof glass 51, the soundproof wall, and the upper wall 142.

  As shown in FIG. 20, an M optical system and a K optical system are disposed on the right side of the polygon scanner 50 in the drawing. On the left side of the polygon scanner 50 in the drawing, an optical system for Y and an optical system for C are arranged. The Y optical system is configured to be point-symmetric with the K optical system about the rotation axis of the polygon scanner 50. The C optical system is configured to have a point-symmetric relationship with the M optical system about the rotation axis of the polygon scanner 50.

  Further, as shown in FIG. 21, LD units 40K, 40M, 40C, and 40Y, which are light beam emitting means for emitting light beams Lk, Lm, Lc, and Ly corresponding to the photoconductors 10K, 10M, 10C, and 10Y, are provided. I have. The LD unit 40 includes at least a semiconductor laser as a light source.

  The collimating lenses 52Y, 52M, 52C, 52K, the imaging lenses (cylinder lenses) 53K, 53M, 53C, 53Y and the reflection mirrors 45a, 45b are disposed on the optical path of the light beam from the LD unit 40 to the polygon scanner 50. ing. Further, scanning lenses (fθ lenses) 25a and 25b, first mirrors 46K, 46M, 46C, and 46Y, and second mirrors 47K, 47M, 47C, and 47Y, which are optical elements, are photoreceptors that are irradiated from the polygon scanner 50. It is arranged on up to 10 optical paths. Further, a long lens corresponding to each color may be disposed on the optical path from the polygon scanner 50 to the photosensitive member 10 that is the object to be irradiated.

  In the lower right part of FIG. 21, a tip beam detection unit 44MK is provided as a beam detection sensor for detecting the tips of the K-color and M-color light beams Lm and Lk. Further, a rear end beam detection unit 48MK as a beam detection sensor for detecting the rear ends of the K and M color light beams Lm and Lk is provided at the upper right in the drawing. In addition, a C and Y tip beam detection unit 44CY is provided at a position (upper left in the figure) that is point-symmetric with the M and K tip beam detection unit 44MK around the rotation axis of the polygon scanner 50. Similarly, the rear end beam detection unit for C and Y is located at a position (lower left in the figure) that is point-symmetric with the rear end beam detection unit 48MK for M and K around the rotation axis of the polygon scanner 50 as a rotary deflector. 48CY is provided.

  The light beam emitted from the K LD unit 40K passes through the aperture to form a light beam Lk having a predetermined shape. The light beam Lk that has passed through this aperture enters the cylindrical lens 53K and corrects the surface tilt of the light beam. The light beam Lk that has passed through the cylindrical lens 53K is reflected by the reflection mirror 45a, passes through the soundproof glass 51, and is incident on the side surface of the lower polygon mirror 49b that is the main scanning line deflecting means. When the light beam Lk is incident on the side surface of the lower polygon mirror 49b, the light beam is deflected and scanned in the main scanning line direction. The light beam Lk deflected and scanned by the polygon mirror 49b passes through the soundproof glass 51 again and is condensed by the scanning lens 43a (fθ lens). Prior to scanning on the photoconductor 10K, the K-color light beam Lk collected by the scanning lens 43a is reflected by the folding mirror 44a, enters the tip beam detection unit 44MK, and the light beam Lk is detected. When the tip beam detection unit 44MK detects the light beam Lk, a synchronization signal is output, and the output timing of the light source signal converted based on the image data is adjusted according to the synchronization signal.

  The light beam Lk emitted based on the input image data passes through the cylindrical lens 53K and the like, is scanned by the lower polygon mirror 49b, and enters the scanning lens 43a as described above. As shown in FIG. 2, the light beam Lk incident on the scanning lens 43a is applied to the photoconductor 10K through the first and second mirrors 46K and 47K and the dustproof glass 128K.

  Similarly to the K color, the light beam Lm emitted from the M LD unit 40M passes through the cylindrical lens 53M and is reflected by the reflecting mirror 45a and scanned by the upper polygon mirror 49a. The M-color light beam Lm scanned by the upper polygon mirror 49a enters the scanning lens 43a, enters the tip beam detection unit 44MK prior to scanning onto the photosensitive member 10M, and outputs a synchronization signal. . Then, the light beam Lm based on the image data emitted in synchronization is passed through the cylindrical lens 53M, the upper polygon mirror 49a, the scanning lens 43a, the first mirror 46M, the second mirror 47M, and the dust-proof glass 128M. The body 10M is irradiated.

  The light beam Lc emitted from the C LD unit 40C passes through the cylindrical lens 53C and the like, is reflected by the reflection mirror 45b, and is scanned by the upper polygon mirror 49a. The C-color light beam Lc scanned by the upper polygon mirror 49a enters the scanning lens 43b, enters the tip beam detection unit 44CY prior to scanning onto the photoreceptor 10C, and outputs a synchronization signal. . Then, the light beam Lc based on the image data emitted in synchronization is passed through the cylindrical lens 53C, the upper polygon mirror 49a, the scanning lens 43b, the first mirror 46C, the second mirror 47C, and the dust-proof glass 128C. The body 10C is irradiated.

  The light beam Ly emitted from the Y LD unit 40Y passes through the cylindrical lens 53Y and the like, is reflected by the reflecting mirror 45b, and is scanned by the lower polygon mirror 49b. The Y-color light beam Ly scanned by the lower polygon mirror 49b passes through the scanning lens 43b, and then enters the tip beam detection unit 44CY prior to scanning onto the photoreceptor 10Y, and a synchronization signal is output. Then, the light beam Lm based on the image data emitted in synchronization is passed through the cylindrical lens 53Y, the lower polygon mirror 49b, the scanning lens 43b, the first and second reflecting mirrors 46Y and 47Y, and the dust-proof glass 128Y. The body 10Y is irradiated.

  Also in the optical writing device 21A of this modified example, the portion facing the polygon scanner on the bottom surface of the optical housing 80 is configured as shown in FIG. Thereby, the heat of the control substrate of the polygon scanner and the bearing portion can be directly radiated to the outside, and the temperature rise in the optical housing can be suppressed. Further, the rib can be prevented from falling in the vertical direction due to the thermal expansion of the bearing support portion, and the polygon scanner can be prevented from being inclined. Thereby, it is possible to prevent the light beams of the respective colors from deviating from the prescribed positions of the photoreceptor, and it is possible to suppress color misregistration.

What was demonstrated above is an example, and there exists an effect peculiar for every following aspect.
(Aspect 1)
A light source 41 for irradiating light; a rotary deflector such as a polygon scanner 50 that reflects and deflects and scans light emitted from the light source 41; and a bearing portion 50a that receives a rotation axis of the rotary deflector. A bearing support boss portion such as a bearing support portion 80b having a fitting hole to be fitted and an outer peripheral surface of the bearing support boss portion parallel to the rotation axis direction of the rotation deflector extend in a direction orthogonal to the rotation axis direction. And an optical housing 80 having a plurality of ribs 80e connected to a boss portion such as a fastening portion 80c positioned in the extending direction and housing the light source 41 and the rotating deflector. The rib 80e extends in a direction inclined with respect to the normal direction of the outer peripheral surface of the bearing support boss portion.
In the optical scanning device described in Patent Document 1, the rib extends in the normal direction from the outer peripheral surface of a bearing support boss such as a cylindrical bearing support. For this reason, when the bearing support boss portion is thermally expanded due to heat generated by the bearing portion of the rotary deflector, a force is applied to each rib in the same direction as the rib extending direction (hereinafter referred to as α direction). The force applied to these ribs is an axial force. However, since the rib is a rigid body and has high shaft rigidity, the rib hardly deforms in the α direction and cannot absorb thermal expansion. Therefore, the rib absorbs thermal expansion of the bearing support boss portion by buckling in one of the two directions orthogonal to the α direction. The two directions orthogonal to the α direction are the rotation axis direction of the rotary deflector (hereinafter referred to as γ direction) and the direction orthogonal to both the X direction and the Z direction (hereinafter referred to as β direction).
However, in the configuration described in Patent Document 1, it is not generally determined whether the rib is deformed in the γ direction or the β direction, and the rib may be deformed in the γ direction (rotational axis direction). there were. If at least one of the plurality of ribs is deformed in the γ direction, the bearing support boss portion may be inclined, and the attitude of the rotary deflector may change.
On the other hand, in the aspect 1, the rib extends inclining with respect to the normal direction of the outer peripheral surface of the bearing support boss portion. Thereby, when the bearing support boss part is thermally expanded by the heat generation of the bearing part 50b, the force in the β direction is applied to each rib. The force applied to the rib is a bending force for bending the rib. Usually, since the rib has an elongated shape, the bending rigidity is low, the rib is easily bent in the β direction, and absorbs the thermal expansion of the bearing support boss portion. Thereby, it can suppress that a rib deform | transforms into the said (gamma) direction (rotation axial direction of a rotation deflector) by the thermal expansion of a bearing support boss | hub part, and can suppress that an attitude | position changes.

(Aspect 2)
In (Aspect 1), the inclination direction with respect to the normal direction of the rib 80e is the same direction.
According to this, as explained in the embodiment, the direction of the restoring force when the rib is bent and deformed by the thermal expansion of the bearing support boss portion such as the bearing support portion 80b, the direction of the rib when the rib is extended by the thermal expansion Can be in the direction of rotating the bearing support boss in one direction. As a result, the restoring force and thermal expansion of the rib when the rib is bent and deformed can be absorbed by the rotation of the bearing support boss, and the rib is deformed in the direction of the rotation axis of the rotary deflector such as the polygon scanner 50. Can be suppressed.
In addition, when the optical housing is molded by injection molding using glass fiber-containing thermoplastic resin, the direction of the molten resin flowing from the space forming the rib of the mold to the space forming the bearing support boss is the same. The direction of the glass fiber can be aligned, and the bearing support boss portion can be accurately formed.

(Aspect 3)
In (Aspect 1) or (Aspect 2), the rib 80e extends in a tangential direction from the outer peripheral surface of a bearing support boss such as the bearing support 80b.
According to this, as described in the embodiment, when the optical housing is molded by injection molding, the molten resin can be smoothly poured into the space corresponding to the bearing support boss portion of the mold, The contained glass fibers are aligned, and the bearing support bosses such as the bearing support 80b can be made to have desired dimensions and characteristics.
In addition, it becomes easy to rotate the bearing support boss portion due to the elongation and restoring force due to the thermal expansion of each rib, and the elongation and restoring force due to the thermal expansion of each rib can be absorbed by the rotation of the bearing support boss portion. . Thereby, it can suppress favorably that each rib 80e deforms in the up-and-down direction.

(Aspect 4)
In any one of (Aspect 1) to (Aspect 3), the periphery of a bearing support boss such as the bearing support 80b of the optical housing 80 is opened, and the bearing support boss is connected to the optical housing 80 by a rib 80e. .
According to this, as described in the embodiment, when the bearing support boss portion such as the bearing support portion 80b is opened, when the bearing support boss portion is thermally expanded, the opening is narrowed. It can suppress that the influence of the thermal expansion of a part affects the outer side of opening. Thereby, deformation of the optical housing can be suppressed.
Further, by connecting the bearing support boss portion to the optical housing with the rib, the rib and the bearing support boss portion can be integrally formed with the optical housing by injection molding, and the apparatus can be made inexpensive. Further, the bearing support boss portion can be provided at a predetermined position with respect to the optical housing.

(Aspect 5)
In any one of (Aspect 1) to (Aspect 4), the rotary deflector such as the polygon scanner 50 has a control board 50b for controlling the rotation of the rotary deflector, and the boss portion positioned in the extending direction of the rib is It is a fixing part such as a fastening part 80c to which the control board 50b is fixed.
According to this, as explained in the embodiment, the fixing portion such as each fastening portion 80c can be reinforced by the control board 50b. By connecting the rib 80e to the fixed portion reinforced by the control board 50b, even if the bearing support boss part such as the rib 80e bearing support part 80b is thermally expanded, the fixed part is controlled by the control board 50b. It can suppress that it moves outside by having been reinforced by. Thereby, it is possible to suppress the influence of the thermal expansion of the bearing support boss portion on the outer side (the side away from the bearing support boss portion) than the fixed portion.

(Aspect 6)
In any one of (Aspect 1) to (Aspect 5), the plurality of ribs 80e are arranged at equal intervals on the outer peripheral surface of the bearing support boss portion such as the bearing support portion 80b.
According to this, as described in the first modification, when a bearing support boss portion such as the bearing support portion 80b is thermally expanded, a drag force is exerted on the rib 80e to suppress the thermal expansion. By making the connection portions of the ribs 80e to the bearing support boss portions at equal intervals, the drag generated at each connection portion R is balanced, and the center of the bearing support boss portion is displaced when the bearing support boss portion is thermally expanded. The stress applied to the bearing portion 50a of the rotary deflector such as a polygon scanner can be suppressed.
When the optical housing is molded by injection molding, the distance that the resin that has flowed into the space corresponding to the bearing support from the space corresponding to each rib of the mold moves to the space corresponding to the rib on the downstream side in the flow direction The glass fibers contained in the resin can be easily aligned.

(Aspect 7)
In any one of (Aspect 1) to (Aspect 6), the rib 80e is inclined with respect to the rotation axis direction of the rotary deflector such as the polygon scanner 50.
According to this, as described in the modification example 2, the twist of the rib 80e can be suppressed, and the tilt of the bearing support boss portion such as the bearing support portion 80b can be suppressed.

(Aspect 8)
A latent image is formed on the surface of the latent image carrier by irradiating light on the surface of the latent image carrier such as the photoconductor 10 using an optical scanning unit such as the optical writing device 21 and developing the latent image. In the image forming apparatus that forms an image by finally transferring the image obtained in (1) onto a recording material, any one of (Aspect 1) to (Aspect 7) is used as the optical scanning unit.
According to this, a good image can be obtained by forming a good latent image on the surface of the latent image carrier of the photoreceptor 10.

1: Process cartridge 10: Each photosensitive member 12: Developing devices 21, 21A: Optical writing device 40: LD unit 41: Light source 43: Scanning lens 49: Polygon mirror 50: Polygon scanner 50a: Bearing portion 50b: Control board 50c: Screw 51: Soundproof glass 52: Collimating lens 53: Cylindrical lens 54: Aperture 55: Soundproof wall 62: Synchronous mirror 63: Synchronous lens 70: Cover member 80: Optical housing 80b: Bearing support portion 80c: Fastening portion 80d: Opening portion 80e : Rib 81: first receiving portion 82: second receiving portion 83: third receiving portion 85: first protruding portion 86: second protruding portion 87: first fixing portion 87a: screw through hole 88: second fixing portion 89 : Third fixing portion 90: Support plate 91 a: Screw hole 91 b: Screw 91: First positioning surface 92: Second positioning surface 93: Third positioning 95: The first positioning hole 96: second positioning hole 97: the first plate spring mounting portion 98: second plate spring mounting v part R: connection portions S: sheet theta: angle of inclination

JP 2006-53224 A

Claims (8)

A light source that emits light;
A rotating deflector that reflects and deflects the light emitted from the light source while rotating, and scans the light;
A bearing support boss having a fitting hole for fitting with a bearing that receives the rotation shaft of the rotation deflector, and the rotation shaft from the outer peripheral surface of the bearing support boss parallel to the rotation axis of the rotation deflector. An optical housing having a plurality of ribs extending in a direction perpendicular to the direction and connected to a boss portion positioned in the extending direction, and an optical housing for housing the light source and the rotating deflector In the device
The optical scanning device according to claim 1, wherein the rib extends in a direction inclined with respect to a normal direction of the outer peripheral surface of the bearing support boss portion. The optical scanning device according to claim 1,
An optical scanning device characterized in that an inclination direction with respect to a normal direction of the rib is the same direction. The optical scanning device according to claim 2,
The optical scanning device according to claim 1, wherein the rib extends in a tangential direction from the outer peripheral surface of the bearing support boss portion. The optical scanning device according to any one of claims 1 to 3,
An optical scanning device having an opening around the bearing support boss portion of the optical housing, wherein the bearing support boss portion is connected to the optical housing by the rib. The optical scanning device according to any one of claims 1 to 4,
The rotary deflector has a control board that controls the rotation of the rotary deflector,
The optical scanning device according to claim 1, wherein the boss portion positioned in the extending direction of the rib is a fixed portion to which the control substrate is fixed. The optical scanning device according to any one of claims 1 to 5,
An optical scanning device characterized in that a plurality of ribs are connected to the outer peripheral surface of the bearing support boss portion at equal intervals. The optical scanning device according to any one of claims 1 to 5,
An optical scanning device characterized in that the rib is inclined with respect to the rotation axis direction of the rotary deflector. A latent image is formed on the surface of the latent image carrier by irradiating light onto the surface of the latent image carrier using an optical scanning unit, and an image obtained by developing the latent image is finally recorded on a recording material. In an image forming apparatus that forms an image by transferring it to the top,
An image forming apparatus using the optical scanning device according to claim 1 as the optical scanning unit.

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