Optical scanning apparatus and image forming apparatus equipped therewith

Abstract

We can provide an optical scanning device that can improve assembly workability, and an image forming apparatus equipped therewith. [Solution] The circuit board has mounting holes through which the terminals of a laser diode, extending in the direction opposite to the laser beam emission direction, are inserted. The peripheral wall portion has a guide member. The guide member protrudes from the outer peripheral surface and is inserted into a board insertion hole formed in the circuit board. The tip of the guide member is located on the opposite side of the laser beam emission direction from the tip of the laser diode terminal.

Description

Technical Field

[0001] The present invention relates to an optical scanning device and an image forming apparatus including the same.

Background Art

[0002] A conventional optical scanning device is disclosed in Patent Document 1. This optical scanning device includes a light source unit, a polygon mirror, and a housing unit. The light source unit emits laser light. The polygon mirror rotates about a rotation axis extending in the vertical direction and reflects the laser light emitted from the light source unit to scan the circumferential surface of an image carrier in the main scanning direction. The housing unit houses the polygon mirror. The housing unit has a bottom wall portion and a peripheral wall portion. The bottom wall portion extends in a direction intersecting the rotation axis of the polygon mirror. The peripheral wall portion projects from the peripheral edge portion of the bottom wall portion and surrounds the polygon mirror from the radially outer side.

[0003] The light source unit has a laser diode and a circuit board. The laser diode has a plurality of light emitting points that emit laser light and is fixed to the outer peripheral surface of the peripheral wall portion. The circuit board has the laser diode mounted thereon.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] According to the above conventional optical scanning device, when mounting the laser diode on the circuit board after performing the optical axis adjustment and position adjustment of the laser diode, it is difficult to position the laser diode and the circuit board, and there is a possibility that the assembly workability may decrease.

[0006] In view of the above-mentioned problems, the present invention aims to provide an optical scanning device capable of improving assembly workability and an image forming apparatus equipped therewith. [Means for solving the problem]

[0007] To achieve the above objective, the first configuration of the present invention comprises a light source unit, a polygon mirror, and a housing. The light source unit emits laser light. The polygon mirror rotates around a rotation axis extending in the vertical direction to reflect the laser light emitted from the light source unit, causing the peripheral surface of the image carrier to scan in the main scanning direction. The housing houses the polygon mirror and the laser diode. The housing has a bottom wall and a peripheral wall. The bottom wall extends in a direction intersecting the rotation axis of the polygon mirror. The peripheral wall protrudes from the peripheral edge of the bottom wall and surrounds the polygon mirror from the radial outside. The laser diode has multiple light-emitting points that emit laser light and is fixed to the outer peripheral surface of the peripheral wall. The circuit board has mounting holes through which the terminals of the laser diode, which extend in the direction opposite to the direction of laser light emission, are inserted. The peripheral wall has a guide member. The guide member protrudes from the outer peripheral surface and is inserted into a substrate insertion hole formed in the circuit board. The tip of the guide member is located on the opposite side of the laser beam emission direction from the tip of the laser diode's terminal. [Effects of the Invention]

[0008] According to the first configuration of the present invention, it is possible to provide an optical scanning apparatus capable of improving assembly workability and an image forming apparatus equipped therewith. [Brief explanation of the drawing]

[0009] [Figure 1] A schematic cross-sectional view showing the internal structure of an image forming apparatus 100 according to one embodiment of the present invention. [Figure 2] Top view of optical scanning device 5 according to one embodiment of the present invention [Figure 3] Side cross-sectional view showing the internal configuration of the optical scanning device 5 according to one embodiment of the present invention. [Figure 4] An exploded perspective view showing the light source unit 26 of the optical scanning device 5 of the present invention. [Figure 5] A perspective view showing an enlarged view of the area around the light source unit 26 of the optical scanning device 5 of the present invention. [Figure 6] A perspective view showing an enlarged view of the area around the light source unit 26 of the optical scanning device 5 of the present invention. [Figure 7] A perspective view showing an enlarged view of the area around the light source unit 26 of the optical scanning device 5 of the present invention. [Figure 8] A perspective view showing an enlarged view of the area around the light source unit 26 of the optical scanning device 5 of the present invention. [Figure 9] A magnified perspective view showing the area around the laser diode 261a of the optical scanning device 5 of the present invention. [Figure 10] A magnified side cross-sectional view showing the area around the laser diode 261a of the optical scanning device 5 of the present invention. [Figure 11] A magnified side cross-sectional view showing the area around the guide member 3931 of the optical scanning device 5 of the present invention. [Modes for carrying out the invention]

[0010] [1. Configuration of the image forming apparatus 100] Embodiments of the present invention will be described below with reference to the drawings. Figure 1 is a schematic cross-sectional view showing the overall configuration of an image forming apparatus 100 on which the optical scanning device 5 of the present invention is mounted. For convenience of explanation, the vertical direction is defined as the up-down direction (Z1-Z2 direction) in the installed state in which the image forming apparatus 100 is usable (the state shown in Figure 1). The front-to-back direction (Y1-Y2 direction) is defined with the front side of the image forming apparatus 100 shown in Figure 1 being the front (front). The left-to-right direction (X1-X2 direction) is defined with reference to the front of the image forming apparatus 100 in the installed state. In this embodiment, the left-to-right direction (X1-X2 direction) is orthogonal to the up-to-down direction (Z1-Z2 direction) and the front-to-back direction (Y1-Y2 direction).

[0011] The image forming apparatus 100 is a tandem-type color printer and includes image forming units Pa, Pb, Pc, and Pd, an optical scanning device 5, photoreceptor drums (image carriers) 1a to 1d, charging devices 2a to 2d, developing devices 3a to 3d, primary transfer rollers 6a to 6d, secondary transfer roller 9, paper cassette 16, fixing device 13, image density sensor 50, and control unit 90.

[0012] Four image forming units, Pa, Pb, Pc, and Pd, are arranged in order from the upstream side in the transport direction (right side in Figure 1) within the main body of the image forming apparatus 100. The image forming units Pa to Pd are provided to correspond to images of four different colors (yellow, magenta, cyan, and black), and each sequentially forms images of yellow, magenta, cyan, and black through the processes of charging, exposure, development, and transfer, respectively.

[0013] The photoreceptor drums 1a to 1d use organic photoreceptors (OPC photoreceptors) with an organic photosensitive layer, or amorphous silicon photoreceptors with an amorphous silicon photosensitive layer. The photoreceptor drums 1a to 1d are arranged in tandem, corresponding to the yellow, magenta, cyan, and black colors.

[0014] A developing device 3a, a charging device 2a, and a cleaning device 7a are arranged around the photoreceptor drum (image carrier) 1a. Similarly, developing devices 3b to 3d, charging devices 2b to 2d, and cleaning devices 7b to 7d are arranged around each of the photoreceptor drums 1b to 1d. In addition, a light scanning device 5 is arranged below the developing devices 3a to 3d.

[0015] The developing devices 3a to 3d are arranged to face the photoreceptor drums (image carriers) 1a to 1d and have developing rollers (developer carriers) 21a to 21d. The developing devices 3a to 3d apply a predetermined developing voltage to the developing rollers (developer carriers) 21a to 21d to attach toner to the electrostatic latent images formed on the photoreceptor drums (image carriers) 1a to 1d, thereby forming toner images. The developing devices 3a to 3d face the photoreceptor drums 1a to 1d respectively and supply toner to the photoreceptor drums 1a to 1d. The developing devices 3a to 3d have containers 4a to 4d, which contain toners of magenta, cyan, yellow, and black colors.

[0016] The charging devices 2a to 2d are arranged upstream of the developing devices 3a to 3d with respect to the rotation direction of the photoreceptor drums 1a to 1d and face the surfaces of the photoreceptor drums 1a to 1d respectively. The charging devices 2a to 2d uniformly charge the surfaces of the photoreceptor drums 1a to 1d respectively.

[0017] The cleaning devices 7a to 7d remove the developer (toner) and the like remaining on the photoreceptor drums 1a to 1d.

[0018] In this embodiment, the optical scanning device 5 is arranged below the photoreceptor drums la to 1d. Based on image data such as characters and patterns input from a personal computer or the like to the image input unit, the optical scanning device 5 irradiates (optically scans) light onto the surfaces of the photoreceptor drums 1a to 1d that are uniformly charged by the charging devices 2a to 2d. Thereby, an electrostatic latent image is formed on the surfaces of the photoreceptor drums 1a to 1d.

[0019] The intermediate transfer belt (belt) 8 is provided adjacent to each image forming unit Pa to Pd. The toner images formed on the photoreceptor drums 1a to 1d are sequentially primary transferred and superimposed onto the intermediate transfer belt 8 while moving while contacting the respective photoreceptor drums 1a to 1d.

[0020] The toner image, which has been primarily transferred onto the intermediate transfer belt 8, is then secondarily transferred onto a sheet of paper P (recording medium), which is an example of a recording medium, by the secondary transfer roller 9. Furthermore, after the toner image has been fixed onto the sheet of paper P, which has the toner image secondarily transferred onto it, the sheet of paper P is discharged from the main body of the image forming apparatus 100.

[0021] The paper P on which the toner image is secondarily transferred is housed in a paper cassette 16 located at the bottom of the main body of the image forming apparatus 100, and is transported via the paper feed roller 12a and the pair of registration rollers 12b to the nip section between the secondary transfer roller 9 and the drive roller 11 of the intermediate transfer belt 8. A blade-shaped belt cleaner 19 is also positioned downstream of the secondary transfer roller 9 to remove any remaining toner or other debris from the surface of the intermediate transfer belt 8.

[0022] When image data is input from a higher-level device such as a personal computer, the charging devices 2a to 2d first uniformly charge the surfaces of the photoreceptor drums 1a to 1d. Next, the light scanning device 5 irradiates the drums with light according to the image data, forming an electrostatic latent image on each photoreceptor drum 1a to 1d corresponding to the image data. The developing devices 3a to 3d are each filled with a predetermined amount of two-component developer containing yellow, magenta, cyan, and black toner, respectively. If the proportion of toner in the two-component developer filled in each developing device 3a to 3d falls below a specified value due to the formation of the toner image described later, toner is replenished from containers 4a to 4d to each developing device 3a to 3d. The toner in the developer is supplied onto the photoreceptor drums 1a to 1d by the developing devices 3a to 3d and adheres electrostatically. This forms a toner image corresponding to the electrostatic latent image formed by exposure from the light scanning device 5.

[0023] Then, the primary transfer rollers 6a to 6d apply an electric field at a predetermined transfer voltage between the primary transfer rollers 6a to 6d and the photoreceptor drums 1a to 1d, and the yellow, magenta, cyan, and black toner images on the photoreceptor drums 1a to 1d are primary transferred onto the intermediate transfer belt 8. These four-color images are formed in a predetermined positional relationship for the formation of a predetermined full-color image. Subsequently, in preparation for the formation of a new electrostatic latent image, any toner remaining on the surface of the photoreceptor drums 1a to 1d after the primary transfer is removed by the cleaning devices 7a to 7d.

[0024] The intermediate transfer belt 8 is stretched between the upstream driven roller 10 and the downstream drive roller 11. As the drive roller 11 rotates due to a belt drive motor (not shown), the intermediate transfer belt 8 begins to rotate clockwise. At a predetermined timing, the paper P is transported from the registration roller pair 12b to the nip section (secondary transfer nip section) between the drive roller 11 and the adjacent secondary transfer roller 9, and the full-color image on the intermediate transfer belt 8 is secondary transferred onto the paper P. The paper P, on which the toner image has been secondary transferred, is then transported to the fuser 13.

[0025] The image density sensor 50 faces the driven roller 10 with the intermediate transfer belt 8 in between. The image density sensor 50 is, for example, a specular reflection type sensor that detects reflected light. The image density sensor 50 converts the measurement result into an electrical signal and outputs it to the control unit 90, which will be described later. The image density sensor 50 can be any sensor that can detect density information of the toner image, for example, a sensor that can detect density from an image obtained by imaging the toner image.

[0026] The paper P, transported to the fixing device 13, is heated and pressurized by the fixing belt 21 and pressure rollers 22, fixing the toner image to the surface of the paper P and forming a predetermined full-color image. The paper P, on which the full-color image has been formed, is then directed in different directions by the branching section 30, which branches in multiple directions, and is discharged into the discharge tray 17 by the discharge roller pair 15 (or after being sent to the double-sided transport path 18 where images are formed on both sides).

[0027] The control unit 90 comprehensively controls the image forming apparatus 100. Specifically, the control unit 90 controls the image forming section. The image forming section includes a light scanning device 5, photosensitive drums (image carriers) 1a to 1d, charging devices 2a to 2d, and developing devices 3a to 3d.

[0028] [2. Configuration of the optical scanning device] Figure 2 is a top view of the optical scanning device 5, showing it with the cover 391 removed. Figure 3 is a side cross-sectional view showing the internal configuration of the optical scanning device 5. Note that a portion of Figure 3 schematically shows the configuration of each component and does not precisely show the shape and positional relationship of each component.

[0029] In the following explanation, the main scanning direction (Y1-Y2 direction) refers to the longitudinal direction of the reflective mirrors 52a to 52d. The main scanning direction (Y1-Y2 direction) also coincides with the direction in which the rotation axes of the photoreceptor drums 1a to 1d extend and the front-to-back direction of the image forming apparatus 100. The sub-scanning direction (Z1-Z2 direction) is the direction parallel to the rotation axis J of the polygon mirror 45 and coincides with the up-and-down direction of the image forming apparatus 100. The left-to-right direction (X1-X2 direction) is the direction perpendicular to the main scanning direction (Y1-Y2 direction) and the sub-scanning direction (Z1-Z2 direction) and coincides with the parallel direction of the reflective mirrors 52a to 52d.

[0030] The optical scanning device 5 outputs (irradiates) multiple (four in this embodiment) laser beams D1 to D4, which are modulated according to each image signal, to the photoreceptor drums 1a to 1d, exposing each surface of the photoreceptor drums 1a to 1d and forming an electrostatic latent image by attenuating the charge.

[0031] The optical scanning device 5 comprises a housing 39, a light source unit 26, a collimator lens 41, a cylindrical lens (not shown), a first aperture 43 and a second aperture 44, a polygon mirror 45, a plurality of scanning lenses 49a and 49b, output mirrors 51a to 51d, and reflection mirrors 52a to 52d.

[0032] The housing 39 has a lid 391 and a housing 392. The lid 391 covers the open top surface of the housing 392. The housing 392 is formed in a substantially rectangular shape when viewed from above. The housing 392 houses a collimator lens 41, a cylindrical lens (not shown), a first aperture 43 and a second aperture 44, a polygon mirror 45, a plurality of scanning lenses 49a, 49b, output mirrors 51a to 51d, and reflection mirrors 52a to 52d.

[0033] The housing portion 392 has a bottom wall portion 392a and a peripheral wall portion 392b. The bottom wall portion 392a extends in a direction intersecting the rotation axis J of the polygon mirror. In this embodiment, the bottom wall portion 392a extends in a direction perpendicular to the rotation axis J of the polygon mirror 45. The peripheral wall portion 392b protrudes upward Z1 from the peripheral edge of the bottom wall portion 392a, and its upper end contacts the lid portion 391. The peripheral wall portion 392b surrounds the collimator lens 41, the cylindrical lens (not shown), the first aperture 43 and the second aperture 44, the polygon mirror 45, the plurality of scanning lenses 49a, 49b, the exit mirrors 51a to 51d, and the reflection mirrors 52a to 52d from the radial outside.

[0034] The light source unit 26 has multiple light-emitting points that emit laser light, and has multiple laser diodes 261a fixed to the outer surface of the peripheral wall portion 392b. Multiple laser diodes 261a are arranged in a row. Each laser diode 261a has a multi-beam structure capable of outputting multiple laser beams, and has two or more light-emitting elements made of semiconductor lasers, and these multiple laser diodes can be made to emit light individually. In this way, by making the laser diodes 261a multi-beam, the optical scanning device 5 can achieve both high speed and high resolution in the formation of electrostatic latent images.

[0035] In this embodiment, laser diodes 261a and collimator lenses 41 are provided in four locations each, corresponding to the image forming sections Pa to Pd. Each laser diode 261a emits laser beams D1 to D4 corresponding to the image forming sections Pa to Pd, respectively (see Figure 3). The collimator lens 41 converts the laser beams D1 to D4 emitted from the laser diodes 261a into approximately parallel beams (parallel beams).

[0036] The polygon mirror 45 reflects multiple laser beams D1 to D4 emitted from each laser diode 261a, scanning the scanning surfaces of the photoreceptor drums (image carriers) 1a to 1d corresponding to each laser diode 261a. This allows a single polygon mirror 45 to scan multiple photoreceptor drums 1a to 1d, reducing the number of parts and lowering the manufacturing cost of the optical scanning device 5. Furthermore, the polygon mirror 45 is covered by a mirror cover 45a (see Figure 3). This prevents fine particles from adhering to the mirror surface of the polygon mirror 45 and reducing its reflectivity.

[0037] The cylindrical lens (not shown) has a predetermined refractive power only in the sub-scanning direction of the laser beams D1 to D4, and focuses the laser beams D1 to D4.

[0038] The first aperture 43 and the second aperture 44 are positioned between the collimator lens 41 and the cylindrical lens (not shown). The first aperture 43 and the second aperture 44 regulate the optical path width of the laser light D1 to D4 that passes through the collimator lens 41 and enters the cylindrical lens. In this embodiment, four first apertures 43 are provided, each corresponding to a laser diode 261a. In addition, one second aperture 44 is provided in common to each light source unit 26 (light source). This reduces the number of parts in the second aperture 44 and thus reduces the manufacturing cost of the optical scanning device 5.

[0039] The scanning lenses 49a and 49b are lenses having fθ characteristics. Scanning lens 49a is provided in one location common to each photoreceptor drum 1a to 1d. Scanning lens 49b is provided in four locations corresponding to each photoreceptor drum 1a to 1d (see Figures 2 and 3). Scanning lenses 49a and 49b are positioned between each photoreceptor drum 1a to 1d and the polygon mirror 45, and the laser light D1 to D4 reflected by the polygon mirror 45 is imaged onto the scanning surface of the corresponding photoreceptor drum (image carrier) 1a to 1d.

[0040] The laser beams D1 to D4 are deflected and scanned in the main scanning direction (X1-X2 direction) by the polygon mirror 45. The laser beams D1 to D4 scanned by the polygon mirror 45 are guided to the output mirrors 51a to 51d via optical elements such as scanning lenses 49a and 49b and reflection mirrors 52a to 52c. The laser beams D1 to D4 reflected by the output mirrors 51a to 51d are then irradiated onto the photosensitive drums 1a to 1d of the image forming section Pa to Pd, respectively.

[0041] [3. Configuration of Light Source Unit 26] Figure 4 is an exploded perspective view showing the light source unit 26 of the optical scanning device 5 in disassembled form. Figures 5 to 8 are enlarged perspective views showing the area around the light source unit 26 of the optical scanning device 5. Figure 5 omits the circuit board 262, the grounding cover 263, and the protective cover 264. Figure 6 omits the circuit board 262 and the protective cover 264. Figure 7 omits the protective cover 264. Figure 9 is an enlarged perspective view showing the area around the laser diode 261a. Figure 10 is an enlarged side cross-sectional view showing the area around the laser diode 261a.

[0042] The light source unit comprises a laser diode 261a, a bracket 261b, a circuit board 262, a grounding cover 263, and a protective cover 264. Each laser diode 261a is held by the bracket 261b and fixed to the peripheral wall portion 392b. Each laser diode 261a has a plurality of terminals 261c that are inserted into the circuit board 262.

[0043] The bracket 261b is made of metal and has a retaining hole 261d for holding the laser diode 261a. The laser diode 261a is held within the retaining hole 261d. In this embodiment, the laser diode 261a is lightly press-fitted into the periphery of the retaining hole 261d. By forming the bracket 261b from metal, the heat from the laser diode 261a is efficiently dissipated to the peripheral wall portion 392b via the bracket 261b.

[0044] Furthermore, by fixing the laser diode 261a to the bracket 261b through light press-fitting, the laser diode 261a can be rotated circumferentially with respect to the optical axis, making optical axis adjustment easy. In addition, the direction of the laser beam emitted from the laser diode 261a can be easily fine-tuned with respect to the collimator lens 41. Moreover, by fine-tuning and moving the laser diode 261a in the main scanning direction (Y1-Y2), the laser diode 261a can be fixed in an appropriate position relative to the focal position of the collimator lens 41.

[0045] Furthermore, the peripheral wall portion 392b of the housing portion 392 has light incidence holes 392c formed therein, in which each laser diode 261a is positioned (see Figure 10). In this embodiment, the light incidence holes 392c penetrate the peripheral wall portion 392b in the main scanning direction (Y1-Y2). The bracket 261b is fixed to the outer circumferential surface of the peripheral wall portion 392b with the laser diodes 261a inserted into the light incidence holes 392c formed in the peripheral wall portion 392b.

[0046] The bracket 261b is screwed to the peripheral wall portion 392b via screws 63 at two points on either side of the retaining hole 261d. By removing the screws 63, the laser diode 261a can be easily removed from the peripheral wall portion 392b, allowing for maintenance and replacement of the laser diode 261a alone.

[0047] The circuit board 262 and protective cover 264 are positioned by guide members 3931 that protrude from the outer circumferential surface of the peripheral wall portion 392b. The circuit board 262 and ground cover 263 are guided by cover guide members 3933 that protrude from the outer circumferential surface of the peripheral wall portion 392b. In this embodiment, guide members 3931 are provided in two locations, and cover guide member 3933 is provided in one location.

[0048] The circuit board 262 is fixed to the peripheral wall portion 392b from the outside of the laser diode 261a. The circuit board 262 also has mounting holes 262a through which the terminals 261c of the laser diode 261a, which extend in the opposite direction to the laser beam emission direction, are inserted. The circuit board 262 has a board insertion hole 2621 through which the guide member 3931 is inserted, a board guide hole 2623 through which the cover guide member 3933 is inserted, and a board screw hole 2625. There are two board insertion holes 2621 and one board guide hole 2623.

[0049] The circuit board 262 is a component on which various electronic components can be mounted, and is a printed wiring board having an electrically insulating substrate body and conductive wiring formed on the surface or inside the substrate body. In this embodiment, the circuit board 262 is rectangular in shape. The circuit board 262 also mounts integrated circuits (ICs) that constitute driver circuits and signal processing circuits, etc.

[0050] The grounding cover 263 is a metal plate that is placed between the circuit board 264 and the peripheral wall portion 392b and grounded. The grounding cover 263 has a notch 2631, a grounding cover insertion hole 2633, an opening 2634, and a grounding cover screw hole 2635. There are two notches 2631 and one grounding cover insertion hole 2633.

[0051] The notch 2631 is formed by cutting out the periphery of the grounding cover 263, through which the guide member 3931 is inserted. The grounding cover insertion hole 2633 is formed at the corner of the grounding cover 263, through which the cover guide member 3933 is inserted. The opening 2634 has a laser diode 261a positioned inside, and when the grounding cover 263 is fixed to the outer surface of the peripheral wall portion 392b, the terminal 261c of the laser diode 261a is exposed to the outside of the grounding cover 263 through the opening 2634.

[0052] The protective cover 264 is a metal plate that covers and protects the circuit board from the outside. The protective cover 264 has protective cover insertion holes 2641 and protective cover screw holes 2645. The protective cover insertion holes 2641 are through which the guide member 3931 is inserted. There are two protective cover insertion holes 2641.

[0053] The circuit board 262, the grounding cover 265, and the protective cover 264 are integrally fixed to the peripheral wall portion 392b by screwing them together using the screw holes 2625 on the circuit board, the screw holes 2635 on the grounding cover, and the screw holes 2645 on the protective cover. In this embodiment, they are screwed in at four locations.

[0054] [4. Configuration of guide member 3931] Figure 11 is a magnified side cross-sectional view showing the area around the guide member 3931. The guide member 3931 protrudes from the outer circumferential surface of the peripheral wall portion 392b and is inserted into the notch 2631 of the grounding cover 263, the board insertion hole 2621 of the circuit board 262, and the protective cover insertion hole 2641 of the protective cover 264. This facilitates the positioning of the grounding cover 263, the circuit board 262, and the protective cover 264, improving the assembly workability of the optical scanning device 5.

[0055] Furthermore, in this embodiment, multiple guide members 3931 are provided, and multiple notches 2631, substrate insertion holes 2621, and protective cover insertion holes 2641 are provided corresponding to the guide members 3931. The multiple guide members 3931 allow the circuit board 262 and protective cover 264 to be guided stably and positioned easily. At this time, the multiple guide members 3931 also function as rotation stoppers for the circuit board 262 and protective cover 264.

[0056] Furthermore, the tip of the guide member 3931 is located at Y2, opposite to the direction of laser emission, from the tip of the terminal 261c of the laser diode 261a. As a result, when inserting the terminal 261c of the laser diode 261a into the mounting hole 262a of the circuit board 262, the guide member 3931 is inserted into the board insertion hole 2621 of the circuit board 262. Therefore, the terminal 261c of the laser diode 261a can be easily inserted into the mounting hole 262a, improving the workability when mounting the laser diode 261a. This further improves the assembly workability of the optical scanning device 5.

[0057] Furthermore, even when the guide member 3931 is inserted into the board insertion hole 2621 of the circuit board 262 after the laser diode 261a has been positioned relative to the optical system of the polygon mirror 45, the terminal 261c of the laser diode 261a can be easily inserted into the mounting hole 262a.

[0058] Furthermore, the guide member 3931 has a small-diameter portion 3931a and a large-diameter portion 3931b. The small-diameter portion 3931a is located at the tip of the guide member 3931 and has an outer diameter smaller than the inner diameter of the substrate insertion hole 2621. The large-diameter portion 3931b is located at the base of the guide member 3931 and has an outer diameter larger than the small-diameter portion 3931a.

[0059] As a result, when inserting the terminal 261c of the laser diode 261a into the mounting hole 262a, the small-diameter portion 3931a is positioned in the substrate insertion hole 2621. At this time, the inner diameter of the substrate insertion hole 2621 is larger than the outer diameter of the small-diameter portion 3931a, creating a gap between the guide member 3931 and the periphery of the substrate insertion hole 2621. This allows the terminal 261c to be easily inserted into the mounting hole 262a while moving the circuit board 262. Therefore, the workability during mounting of the laser diode 261a is further improved. In this embodiment, the cover guide member 3933 is inserted through the substrate guide hole 2623 of the circuit board 262. Therefore, the circuit board 262 moves while rotating around the cover guide member 3933.

[0060] Furthermore, in this embodiment, the outer diameter of the large-diameter portion 3931b is approximately the same as the inner diameter of the substrate insertion hole 2621. As a result, when the circuit board 262 is further pushed in after the terminal 261c has been inserted into the mounting hole 262a, the large-diameter portion 3931b is inserted into the substrate insertion hole 2621. This adjusts the position of the circuit board 262 as the substrate insertion hole 2621 passes through the small-diameter portion 3931a, and the position of the circuit board 262 is determined when the substrate insertion hole 2621 is inserted into the large-diameter portion 3931b. Therefore, the assembly workability of the optical scanning device 5 is further improved. Note that the outer diameter of the large-diameter portion 3931b may be slightly smaller than the inner diameter of the substrate insertion hole 2621.

[0061] Furthermore, in this embodiment, the outer diameter of the small-diameter portion 3931a is approximately the same as the inner diameter of the protective cover insertion hole 2641. After the large-diameter portion 3931b is inserted into the substrate insertion hole 2621, the small-diameter portion 3931a is inserted into the protective cover insertion hole 2641. At this time, the position of the protective cover 264 is determined. Therefore, the assembly workability of the optical scanning device 5 is further improved. In addition, the guide member 3931 can be used as a common positioning member for the circuit board 262 and the protective cover 264, thereby saving space and reducing manufacturing costs. Note that the outer diameter of the small-diameter portion 3931a may be slightly smaller than the inner diameter of the protective cover insertion hole 2641.

[0062] Furthermore, the present invention is not limited to the embodiments described above, and various modifications are possible without departing from the spirit of the invention. For example, in this embodiment, four laser diodes 261a are provided corresponding to the image forming sections Pa to Pd, but in a monochrome image forming apparatus 100, only one laser diode 261a is needed. Also, the order of the colors of the laser beams D1 to D4 is not particularly limited.

[0063] Furthermore, in this embodiment, the tip of the laser diode 261a is positioned inside the light incident hole 392c, but the laser diode 261a does not need to be positioned inside the light incident hole 392c as long as the laser light emitted from the laser diode 261a passes through the light incident hole 392c.

[0064] Furthermore, in this embodiment, the laser diode 261a is held by the bracket 261b and fixed to the peripheral wall portion 392b. However, a holding hole for holding the laser diode 261a may be formed in the circuit board 262, and the circuit board 262 may hold the laser diode 261a. In this case, the bracket 261b can be omitted, thereby reducing manufacturing costs. [Industrial applicability]

[0065] This invention can be used in optical scanning devices that form a latent image on a scanned surface by exposure scanning. [Explanation of Symbols]

[0066] 1a~1d Photoconductor drum 2a~2d Charging device 3a~3d developing device Containers 4a-4d 5. Optical scanning device 6a~6d Primary transfer roller 7a~7d Cleaning equipment 8. Intermediate transfer belt 9. Secondary transfer roller 10 Driven rollers 11 Drive rollers 12a Paper feed roller 12b Resist Roller 13 Fixing device 15 Discharge roller pair 16 paper cassettes 17. Discharge tray 18-sided transport path 19 Belt Cleaner 21 Fixing belt 22 Pressure rollers 26 Light source units 30 Branching point 39 cabinets 41 Collimator lens 43. First Aperture 44. Second Aperture 45 Polygon Mirror 45a Mirror Cover 49a Scanning lens 49a, 49b scanning lenses 49b Scanning lens 50 Image density sensor 51a~51d Output mirror 52a~52d Reflective mirrors 63 screws 90 Control Unit 100 Image forming apparatus 261a Laser Diode 261b Bracket 261c terminal 261d Retaining hole 262 Circuit boards 262a Mounting hole 263 Ground cover 264 Protective Cover 264 Circuit boards 265 Ground cover 391 Lid 392 Storage Unit 392a Bottom wall 392b Peripheral wall part 392c Light entrance hole 2621 Circuit board insertion holes 2623 PCB guide holes 2625 PCB screw holes 2631 Notch 2633 Grounding cover insertion hole 2634 Opening 2635 Grounding cover screw hole 2641 Protective cover insertion hole 2645 Protective cover screw holes 3931 Guide member 3931a Small diameter section 3931b Large diameter section 3933 Cover guide member D1~D4 Laser light J rotation axis P paper Pa~Pd Image Forming Unit

Claims

1. A light source unit that emits laser light, A polygon mirror rotates around a rotation axis extending in the vertical direction to reflect the laser light emitted from the light source unit and scans the circumferential surface of the image carrier in the main scanning direction, The system comprises the aforementioned polygon mirror and a housing section for housing it. The aforementioned housing section is The bottom wall portion extends in a direction intersecting the rotation axis of the polygon mirror, It has a peripheral wall portion that protrudes from the peripheral edge of the bottom wall portion and surrounds the polygon mirror from the radially outer side, The aforementioned light source unit is A laser diode having multiple light-emitting points that emit the aforementioned laser light, and fixed to the outer surface of the peripheral wall portion, The circuit board has mounting holes through which the terminals of the laser diode, which extend in the direction opposite to the direction of emission of the laser light, are inserted. The aforementioned peripheral wall portion is It has a guide member that protrudes from the outer surface and is inserted into a substrate insertion hole formed in the circuit board, An optical scanning device wherein the tip of the guide member is located on the opposite side of the laser beam emission direction from the tip of the terminal of the laser diode.

2. The guide member is A small-diameter portion is positioned at the tip and has an outer diameter smaller than the inner diameter of the substrate insertion hole, The optical scanning device according to claim 1, wherein the device is positioned at the base and has an outer diameter larger than the small diameter portion.

3. The aforementioned light source unit is The circuit board further has a protective cover that covers and protects it from the outside, The guide member is inserted through the protective cover insertion hole formed in the protective cover. The optical scanning apparatus according to claim 2, wherein the outer diameter of the small-diameter portion is substantially the same as the inner diameter of the protective cover insertion hole.

4. Multiple guide members are provided, and multiple substrate insertion holes are provided corresponding to the guide members. Multiple laser diodes are arranged in a row. One of the substrate insertion holes is a round hole, The optical scanning apparatus according to claim 1 or claim 2, wherein the other substrate insertion hole is an elongated hole that is long in the parallel direction of the laser diode.

5. The aforementioned light source unit is The circuit board further comprises a grounding cover disposed between the peripheral wall portion and grounded, The aforementioned peripheral wall portion is The optical scanning apparatus according to claim 1 or claim 2, further comprising a cover guide member that protrudes from the outer peripheral surface and is inserted into a ground cover insertion hole formed in the ground cover.

6. The aforementioned light source unit is The bracket further has a retaining hole for holding the laser diode, The optical scanning apparatus according to claim 1 or claim 2, wherein the bracket is fixed to the outer surface of the peripheral wall portion with the laser diode inserted into the light incident hole formed in the peripheral wall portion.

7. The optical scanning apparatus according to claim 1 or claim 2, wherein the circuit board has a holding hole for holding the laser diode, and the laser diode is fixed to the outer surface of the peripheral wall with the laser diode inserted into a light incidence hole formed in the peripheral wall.

8. The image carrier having a photosensitive layer formed on its surface, A charging device for charging the image carrier to a predetermined surface potential, An optical scanning apparatus according to claim 1 or 2, wherein the surface of the image carrier charged by the charging device is exposed to attenuate the charge and an electrostatic latent image is formed, An image forming apparatus equipped with [a specific feature].

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