Optical scanning apparatus and image forming apparatus equipped therewith

Abstract

To provide an optical scanner which can inhibit deterioration of assemblability with a simple structure, and to provide an image formation device including the optical scanner.SOLUTION: An optical scanner includes a light source, a deflector, an optical element, an imaging lens, a fixing structure, and a housing. The optical element is formed with a reflection surface. The fixing structure has a first support wall part, a second support wall part, and a biasing member. The first support wall part has a support protrusion part protruding along a thickness direction toward a back surface and having a tip part which contacts with the back surface and an inclined surface extending from the tip part to the opposite side of the second support wall part. A first angle between a first straight line extending in a vertical direction orthogonal to a bottom surface of the housing and a surface of the optical element is smaller than a second angle between the first straight line and the inclined surface. The second angle is smaller than 90 degrees.SELECTED DRAWING: Figure 4

Description

Technical Field

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

Background Art

[0002] Conventionally, there is an electrophotographic image forming apparatus provided with an optical scanning device that scans a light beam emitted from a light source on the surface (scanning surface) of a photoreceptor drum to form an electrostatic latent image (Patent Document 1).

[0003] The optical scanning device of Patent Document 1 includes a light source, a deflector, an optical element, a plurality of imaging lenses, a fixing structure, and a housing. The deflector deflects the light beam emitted from the light source. The optical element is a mirror capable of reflecting the light beam emitted from the light source. A reflecting surface for reflecting the light beam deflected by the deflector is formed on one surface in the thickness direction of the optical element. The imaging lens forms an image of the light beam on the photoreceptor. The fixing structure fixes the optical element. The housing houses the light source, the deflector, the optical element, and the fixing structure. The light beam emitted from the light source is deflected by the deflector, then reflected by the reflecting surface of the optical element, and imaged on the scanning surface of the photoreceptor drum.

[0004] The above fixing structure includes a biasing member such as a leaf spring, a first support wall portion, and a second support wall portion. The first support wall portion is in a wall-like rib shape facing the back surface (the surface opposite to the reflecting surface in the thickness direction) of the optical element in the thickness direction of the optical element. The first support wall portion has a support protrusion protruding toward the back surface of the optical element (see FIG. 6 of Patent Document 1). The second support wall portion is in a wall-like rib shape facing one end surface in the width direction of the optical element. The end surface and the second support wall portion are in contact. The optical element is pressed against the first support wall portion by the biasing force of the biasing member. The tip of the support protrusion is in contact with the back surface of the optical element. By this contact between the tip and the back surface, and the contact between the end surface and the second support wall portion, the optical element is positioned in the thickness direction and the width direction. By this positioning, the reflection angle of the reflecting surface with respect to the light beam is defined. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2012-159529 [Overview of the project] [Problems that the invention aims to solve]

[0006] Incidentally, the optical element described above is inserted between the first support wall and the biasing member along the width direction and fixed to the housing. Therefore, when inserting the optical element, the side of the optical element may come into contact with a support projection protruding from the first support wall and get stuck, potentially preventing the optical element from being inserted to the correct position (the position where it contacts the second support wall). In this case, it is necessary to pull the optical element out from between the first support wall and the biasing member and reinsert it. Consequently, the optical scanning device described above suffers from poor assembly.

[0007] The present invention aims to provide an optical scanning apparatus that can suppress deterioration of assembly ease through a simple configuration, and an image forming apparatus equipped therewith. [Means for solving the problem]

[0008] To achieve the above objective, the first configuration of the present invention is an optical scanning device comprising a light source, a deflector, an optical element, an imaging lens, a fixed structure, and a housing. The deflector deflects a light beam emitted from the light source. The optical element has a reflective surface formed on one side in the thickness direction that reflects the light beam deflected by the deflector. The imaging lens forms an image of the light beam onto a photoreceptor. The fixed structure has a first support wall portion facing the back surface of the optical element in the thickness direction, a second support wall portion that contacts one end surface in the width direction of the optical element perpendicular to the thickness direction, and a biasing member that biases the optical element toward the first support wall portion. The optical element is fixed in the thickness direction and width direction by being sandwiched between the biasing member and the first support wall portion. The housing houses the light source, deflector, optical element, imaging lens, and fixed structure. The first support wall portion has a support projection that protrudes toward the rear surface along the thickness direction and has a tip portion that abuts against the rear surface, and an inclined surface that extends from the tip portion toward the opposite side of the second support wall portion. The first angle between the first straight line extending perpendicularly to the bottom surface of the housing and the surface of the optical element is smaller than the second angle between the first straight line and the inclined surface. The second angle is less than 90 degrees. [Effects of the Invention]

[0009] According to the first configuration of the present invention, when inserting the optical element between the first support wall and the biasing member, even if the optical element comes into contact with the support projection, the optical element will be inserted all the way in along the inclined surface (to the position where it contacts the second support wall). As a result, the optical element is less likely to get caught on the support projection, and deterioration of assembly can be suppressed. Therefore, it is possible to provide an optical scanning device that can suppress deterioration of assembly with a simple configuration. [Brief explanation of the drawing]

[0010] [Figure 1] A schematic cross-sectional view showing the internal structure of the image forming apparatus 100 according to an embodiment of the present invention. [Figure 2] A schematic side cross-sectional view showing the configuration of the optical scanning device 5. [Figure 3] Plan view of the folded mirror 50a fixed to the mirror fixing structure 52, as seen from the reflective surface 51 side. [Figure 4] Cross-sectional view showing the cross-section of the folded mirror 50a cut along the AA section line shown in Figure 3. [Figure 5] Enlarged view of the area around the contact end face 61 [Figure 6] Cross-sectional view showing a modified example of the optical scanning device 5 according to an embodiment of the present invention. [Figure 7] Cross-sectional view showing a further modification of the optical scanning device 5 according to an embodiment of the present invention. [Modes for carrying out the invention]

[0011] Embodiments of the present invention will be described below with reference to the drawings. Figure 1 is a schematic cross-sectional view showing the internal structure of an image forming apparatus 100 according to an embodiment of the present invention. Inside the main body of the image forming apparatus 100 (here, a color printer), 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). These image forming units Pa to Pd are provided to correspond to images of four different colors (cyan, magenta, yellow, and black), and sequentially form images of cyan, magenta, yellow, and black through the processes of charging, exposure, development, and transfer, respectively.

[0012] These image forming units Pa to Pd are equipped with photoreceptor drums 1a, 1b, 1c, and 1d, each carrying a visible image (toner image) of a different color. Furthermore, an intermediate transfer belt 8, which rotates clockwise in Figure 1, is provided adjacent to each image forming unit Pa to Pd. The toner images formed on these photoreceptor drums 1a to 1d are sequentially transferred and superimposed onto the intermediate transfer belt 8, which moves in contact with each photoreceptor drum 1a to 1d. Subsequently, the toner images transferred onto the intermediate transfer belt 8 are secondarily transferred onto a sheet of paper S (recording medium), which is an example of a recording medium, by a secondary transfer roller 9. Furthermore, the sheet of paper S on which the toner images have been secondarily transferred is discharged from the main body of the image forming apparatus 100 after the toner images have been fixed in the fixing device 13. The image forming process for each photoreceptor drum 1a to 1d is performed while the photoreceptor drums 1a to 1d are rotated counterclockwise in Figure 1 by a main motor (not shown).

[0013] The paper S 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. The intermediate transfer belt 8 is made of a dielectric resin sheet, and a seamless belt is mainly used. In addition, a blade-shaped belt cleaner 19 is positioned downstream of the secondary transfer roller 9 to remove toner and other residues remaining on the surface of the intermediate transfer belt 8.

[0014] Next, the image forming sections Pa to Pd will be described. Around and below the rotatably arranged photoreceptor drums 1a to 1d are charging devices 2a, 2b, 2c, and 2d for charging the photoreceptor drums 1a to 1d, a light scanning device 5 for exposing image information to each photoreceptor drum 1a to 1d, developing devices 3a, 3b, 3c, and 3d for forming toner images on the photoreceptor drums 1a to 1d, and cleaning devices 7a, 7b, 7c, and 7d for removing residual developer (toner) etc. on the photoreceptor drums 1a to 1d.

[0015] 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 optical 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 cyan, magenta, yellow, and black toners, 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 the toner 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 optical scanning device 5.

[0016] Then, an electric field is applied at a predetermined transfer voltage between the primary transfer rollers 6a to 6d and the photoreceptor drums 1a to 1d by the primary transfer rollers 6a to 6d, and the cyan, magenta, yellow, and black toner images on the photoreceptor drums 1a to 1d are primarily transferred onto the intermediate transfer belt 8. These four-color images are formed with a predetermined positional relationship determined in advance for a predetermined full-color image formation. Thereafter, in preparation for the subsequent formation of a new electrostatic latent image, toner and the like remaining on the surfaces of the photoreceptor drums 1a to 1d after the primary transfer are removed by the cleaning devices 7a to 7d.

[0017] The intermediate transfer belt 8 is stretched between the upstream driven roller 10 and the downstream driving roller 11. When the intermediate transfer belt 8 starts to rotate in the clockwise direction as the driving roller 11 rotates by a belt driving motor (not shown), the sheet S is conveyed from the registration roller pair 12b to the nip portion between the driving roller 11 and the secondary transfer roller 9 provided adjacent thereto at a predetermined timing, and the full-color image on the intermediate transfer belt 8 is secondarily transferred onto the sheet S. The sheet S onto which the toner image has been secondarily transferred is conveyed to the fixing device 13.

[0018] The sheet S conveyed to the fixing device 13 is heated and pressurized by the fixing belt 21 and the pressure roller 22, and the toner image is fixed on the surface of the sheet S, and a predetermined full-color image is formed. The sheet S on which the full-color image has been formed is diverted in the conveyance direction by the branching portion 30 branched in a plurality of directions, and is discharged to the discharge tray 17 by the discharge roller pair 15 as it is (or after being sent to the duplex conveyance path 18 and having images formed on both sides).

[0019] Next, the optical scanning device 5 according to the first embodiment of the present invention will be described in detail while referring to FIGS. 2 and 3. FIG. 2 is a side cross-sectional view schematically showing the configuration of the optical scanning device 5. As shown in FIG. 2, the optical scanning device 5 includes a housing 39, a light source unit 26 housed in the housing 39, a first imaging lens 41 (optical element), second imaging lenses 42a to 42d (optical elements), a polygon mirror 45 (deflector), folding mirrors 50a to 50h (optical elements), and a mirror fixing structure 52 (fixing structure). The optical scanning device 5 performs optical scanning on each of the photoreceptor drums 1a to 1d. Here, only the optical scanning on the photoreceptor drum 1a will be described, and the description of the photoreceptor drums 1b to 1d will be omitted because they are the same as the photoreceptor drum 1a.

[0020] The light source unit 26 (light source) has a laser diode (not shown) and emits a light beam LB from the laser diode. The light beam LB emitted from the laser diode passes through a collimator lens and a cylindrical lens (both not shown) and is imaged on the deflection surface 62 of the polygon mirror 45.

[0021] The polygon mirror 45 is a regular prism (here, a regular hexagonal prism) having deflection surfaces 62 formed on each side surface. Each deflection surface 62 is a mirror surface and can reflect and deflect the light beam LB emitted from the light source unit 26. The polygon mirror 45 is rotatably supported about a central axis (not shown) extending along the vertical direction (the paper surface direction of FIG. 2). The polygon mirror 45 is connected to a polygon motor (not shown) and rotates by the rotational driving force of the polygon motor.

[0022] The first imaging lens 41, the second imaging lenses 42a to 42d, and the folding mirrors 50a to 50h are positioned between the polygon mirror 45 and the photoreceptor drum 1a. The folding mirrors 50a to 50h have a mirror-finished reflective surface 51 formed on one side of their thickness direction. The light beam LB, deflected by the polygon mirror 45, passes through the first imaging lens 41 and is reflected and deflected by the folding mirrors 50e to h. The light beam LB, deflected by the folding mirror 50e, passes through the second imaging lens 42a and is reflected and deflected by the folding mirror 50a, and is imaged onto the outer surface of the photoreceptor drum 1a. Similarly, the light beam LB deflected by the folding mirrors 50f and g also passes through the second imaging lenses 42b and 42c and is reflected by the folding mirrors 50b and c, and is imaged onto the outer surface of the photoreceptor drums 1b and 1c. The light beam LB reflected by the folding mirror 50h passes through the first imaging lens 41, then through the second imaging lens 42d, and is reflected by the folding mirror 50h, deflected, and then imaged onto the photoreceptor drum 1d.

[0023] The folding mirrors 50a to 50h are fixed inside the housing 39 by a plurality of mirror fixing structures 52 formed inside the housing 39. The folding mirrors 50a to 50h are fixed to the housing 39 with their reflective surfaces 51 positioned at a predetermined first angle θ1 (the angle made between the bottom surface 40 of the housing 39 and a first straight line L1 perpendicular to it, and the size of the angle located counterclockwise from the first straight line L1). Note that in Figure 2, the mirror fixing structures 52 supporting the folding mirrors 50e to 50h are omitted. Details of how the folding mirrors 50a to 50h are fixed by the mirror fixing structures 52 will be described later.

[0024] The polygon mirror 45 rotates at a constant speed in the clockwise direction shown by the polygon motor. This rotation causes the light beam LB to scan the scanned surface of the photoreceptor drum 1a at a constant speed in the main scanning direction (direction of the paper shown in the illustration). As a result, a scanning line extending linearly in the main scanning direction is formed on the scanned surface of the photoreceptor drum 1a (not shown). One scanning line is drawn for each deflection surface 62. As the polygon mirror 45 rotates, the light beam LB is sequentially imaged onto adjacent deflection surfaces 62. At this time, the photoreceptor drum 1a is rotating, and multiple scanning lines are formed in the sub-scanning direction, forming an electrostatic latent image.

[0025] Next, the structure for fixing the folding mirrors 50a to 50h to the housing 39 will be described in detail. Figure 3 is a plan view of the folding mirror 50a fixed to the mirror fixing structure 52, as seen from the reflective surface 51 side. Figure 4 is a cross-sectional view showing the folding mirror 50a cut along the AA section line shown in Figure 3. Hereinafter, the direction parallel to the longitudinal direction of the folding mirror 50a (the left-right direction shown in Figure 3) will be simply referred to as the "longitudinal direction." The direction parallel to the thickness direction of the folding mirror 50a (the direction perpendicular to the plane of the paper in Figure 3) will be simply referred to as the "thickness direction." The direction parallel to the width direction of the folding mirror 50a (the up-down direction shown in Figure 3), which is perpendicular to the longitudinal direction and the thickness direction, will be simply referred to as the "width direction." Note that only the folding mirror 50a will be described here, and the other folding mirrors 50b to 50h and the mirror fixing structure 52 that supports them have a common configuration, so their description will be omitted.

[0026] As shown in Figure 3, the mirror fixing structure 52 is provided at a position that overlaps with both ends of the folded mirror 50a in the longitudinal direction. As shown in Figure 4, the mirror fixing structure 52 comprises a first support wall 53, a second support wall 54, and a leaf spring 46 (biasing member).

[0027] The first support wall 53 is adjacent to the folded mirror 50a in the thickness direction. The second support wall 54 is adjacent to the folded mirror 50a in the width direction. The second support wall 54 is connected to one end of the first support wall 53 in the width direction (the lower end shown in Figure 4).

[0028] The first support wall portion 53 has a support projection 56. The support projection 56 protrudes in the thickness direction toward the back surface 55 of the folded mirror 50a (the surface opposite to the reflective surface 51 of the folded mirror 50a in the thickness direction). The tip portion 58 of the support projection 56 is formed in a planar shape parallel to the back surface 55 (see Figure 5). The tip portion 58 is in surface contact with the back surface 55.

[0029] An inclined surface 59 is formed on the support projection 56. The inclined surface 59 is connected to the end of the tip portion 58 in the width direction that is furthest from the bottom surface 40 of the housing 39 (further from the second support wall portion 54). The inclined surface 59 extends away from the back surface 55. The inclined surface 59 is inclined at a predetermined second angle θ2 (the angle it makes with the first straight line L1, and the size of the angle located counterclockwise from the first straight line L1).

[0030] Preferably, the first support wall portion 53 of the mirror fixing structure 52 located on one side in the longitudinal direction is provided with two support protrusions 56, and the first support wall portion 53 of the mirror fixing structure 52 located on the other side in the longitudinal direction is provided with one support protrusion 56 (see Figure 3).

[0031] The second support wall portion 54 has a positioning projection 60 that protrudes upward. At the tip of the positioning projection 60, a contact end surface 61 is formed that faces the side surface 57 (one (downward) end surface in the width direction) of the folded mirror 50a in the width direction. The contact end surface 61 is in contact with the side surface 57. The contact end surface 61 is inclined at a predetermined angle with respect to the first straight line L1.

[0032] The leaf spring 46 is formed by bending a springy metal plate into a predetermined shape (V-shape in side view). The leaf spring 46 has a fixed portion 47 fixed to the housing 39, a bent portion 48 connected to the fixed portion 47, and a contact portion 49 connected to the bent portion 48. The fixed portion 47 is fixed to the housing 39 by a so-called snap-fit ​​structure. The bent portion 48 curves upward in an arc from the lower end of the fixed portion 47. The contact portion 49 is a rectangular plate-like body extending upward from the end of the bent portion 48 (the end opposite to the fixed portion 47). The contact portion 49 faces the reflective surface 51 in the thickness direction. The contact portion 49 has a contact projection 44 that protrudes toward the reflective surface. The contact projection 44 bulges toward the first support wall portion 53 in an arc shape.

[0033] The folding mirror 50a is inserted between the contact portion 49 of the leaf spring 46 and the first support wall portion 53. When the folding mirror 50a is inserted, the contact projection 44 contacts the reflective surface 51, and the contact portion 49 elastically deforms, moving away from the first support wall portion 53, starting from the bent portion 48. The elastic force generated by this elastic deformation causes the contact projection 44 to press (bias) the folding mirror 50a toward the first support wall portion 53 along the thickness direction. The folding mirror 50a is held between the contact projection 44 and the support projection 56 by this pressing force of the leaf spring 46. The folding mirror 50a is held at both ends in the longitudinal direction between the leaf spring 46 and the first support wall portion 53 and fixed to the housing 39 at a first angle θ1.

[0034] The second angle θ2 is greater than the first angle θ1 and less than 90 degrees (preferably 80 degrees or less (more preferably 70 degrees or less)). It is even more preferable that the second angle θ2 is 10 degrees or more greater than the first angle θ1. Specifically, if the first angle θ1 is 30 degrees, it is preferable that the second angle θ2 is 40 degrees or more and less than 90 degrees.

[0035] Figure 5 is an enlarged view of the area around the contact end face 61. As shown in Figure 5, it is preferable that the imaginary second straight line L2, which is parallel to the width direction and passes through the center of the folded mirror 50a in the thickness direction, is located on the back surface 55 side of the folded mirror 50a, rather than the center P1 of the contact end face 61 in the width direction.

[0036] Incidentally, in conventional optical scanning devices 5, the folding mirrors 50a to 50h generally do not have the inclined surface 59 described above formed on the positioning projection 60, or the second angle θ2 is 90 degrees or more due to manufacturing constraints. In such optical scanning devices 5, when inserting the folding mirrors 50a to 50h between the first support wall 53 and the leaf spring 46, the tips of the folding mirrors 50a to 50h (around the corner between the side surface 57 and the back surface 55) may come into contact with and get caught on the support projection 56 protruding from the first support wall 53. If this occurs, it becomes difficult to insert the folding mirrors 50a to 50h any further, and they cannot be positioned in the appropriate location (where the side surface 57 and the contact end surface 61 abut). In such cases, it is necessary to pull out the folding mirrors 50a to 50h once and reinsert them between the first support wall 53 and the leaf spring 46, taking care not to get caught on the support projection 56. Therefore, the conventional optical scanning device 5 suffered from poor assembly.

[0037] As described above, the optical scanning device 5 of the above embodiment has an inclined surface 59 formed so as to be connected to the tip 58 of the support projection 56. Therefore, if the tip of the folding mirror 50a to 50h in the insertion direction (around the corner between the side surface 57 and the back surface 55) comes into contact with the support projection 56 when inserting the folding mirrors 50a to 50h between the leaf spring 46 and the first support wall 53, the tip of the folding mirror 50a to 50h will come into contact with the inclined surface 59. Here, as described above, the second angle θ2 of this inclined surface 59 is set to be greater than the first angle θ1 and less than or equal to 90 degrees. The inclined surface 59 is inclined at the second angle θ2 described above. Therefore, if one tries to insert the folding mirrors 50a to 50h further in from this state, the tip of the folding mirror 50a to 50h will slide on the inclined surface 59 and go over the tip 58. Therefore, the folded mirrors 50a to 50h can be inserted between the leaf spring 46 and the first support wall 53 until the side surface 57 contacts the contact end surface 61. Thus, it is no longer necessary to pull out and reinsert the folded mirrors 50a to 50h, and deterioration of the assembly of the optical scanning device 5 can be suppressed. As a result, it is possible to provide an optical scanning device 5 that can suppress deterioration of assembly with a simple configuration, and an image forming apparatus 100 equipped therewith.

[0038] Furthermore, the mirror fixing structure 52 is positioned to overlap both ends of the folded mirrors 50a to 50h in the longitudinal direction. This allows the folded mirrors 50a to 50h to be more firmly fixed to the housing 39.

[0039] Furthermore, as described above, it is preferable that the first support wall portion 53 of the mirror fixing structure 52 located on one side in the longitudinal direction is provided with two support protrusions 56, and the first support wall portion 53 of the mirror fixing structure 52 located on the other side in the longitudinal direction is provided with one support protrusion 56. In this way, when the folded mirrors 50a to 50h are pressed against the positioning protrusions 60 and positioned in the thickness direction, the folded mirrors 50a to 50h are positioned on a plane including these three positioning protrusions 60. Therefore, the folded mirrors 50a to 50h can be stably positioned with respect to the thickness direction.

[0040] Furthermore, as described above, it is preferable that the second straight line L2 is located on the back surface 55 side of the folded mirrors 50a to 50h, rather than on the widthwise center P1 of the contact end face 61. In this case, the contact position in the thickness direction between the folded mirrors 50a to 50h and the second support wall 54 is located relatively far from the back surface 55. Therefore, when the folded mirrors 50a to 50h are pressed by the leaf spring 46, it is possible to suppress the folding mirrors 50a to 50h from tipping towards the reflective surface 51 side due to this pressing force. Consequently, the leaf spring 46 can be fixed to the housing 39 more stably.

[0041] Furthermore, as mentioned above, by adopting a configuration in which the tip portion 58 is formed in a flat shape, it becomes easier to measure the dimensions of the tip portion 58 and its position inside the housing 39, making dimensional control easier and improving ease of assembly. Also, when inserting the folded mirrors 50a to 50h all the way in, the tip portion 58 and the back surface 55 slide against each other. At this time, the contact area between the tip portion 58 and the back surface 55 is relatively large, so the back surface 55 is less likely to be scratched by contact with the tip portion 58.

[0042] Furthermore, the present invention is not limited to the above embodiments, and various modifications are possible without departing from the spirit of the invention. For example, as shown in Figure 6, the inclined surface 59 of the optical scanning device 5 of the above embodiment can be configured such that the second inclination angle θ of the support projection 56 on one side in the width direction (the side closer to the second support wall 54) and the support projection 56 on the other side in the width direction (the side further from the second support wall 54) are different. In this case, the second angle θ2' of the inclined surface 59 of the support projection 56 on one side can be larger than the second angle θ2 of the inclined surface 59 of the support projection 56 on the other side.

[0043] Of the pair of support protrusions 56, the support protrusion 56 on one side is located further in the insertion direction than the support protrusion 56 on the other side, making it more likely to catch when inserting the folding mirrors 50a to 50h. Therefore, by making the second angle θ2' larger than the second angle θ2 as described above, it is possible to effectively suppress the catching of the folding mirrors 50a to 50h on the support protrusion 56 on one side when inserting them.

[0044] Furthermore, the folded mirrors 50a to 50h in the above embodiment may be any optical elements having a reflective surface capable of reflecting the light beam LB. For example, a prism can be used as such an optical element. Also, the first imaging lens 41 and the second imaging lenses 42a to 42d can be fixed in the same configuration as the mirror fixing structure 52.

[0045] Furthermore, the leaf spring 46 may be an elastic member such as a coil spring, as long as it has a biasing force that biases the folded mirrors 50a to 50h toward the first support wall portion 53.

[0046] Furthermore, although the tip portion 58 is described as being formed in a planar shape, a configuration in which the tip is formed in an angular shape can also be adopted, as shown in Figure 7. In this case, the tip portion 58 will be in line contact with the back surface 55. This makes it possible to position the folding mirrors 50a to 50h with a more precise setting of the first angle θ1. [Industrial applicability]

[0047] The present invention can be used in an optical scanning device that arranges a folding mirror inside the housing to deflect the light beam at multiple points and form an image on the scanning surface of a photoreceptor drum. It can also be used for other mirrors that deflect the light beam, such as a mirror for detecting the scanning start timing. By using the present invention, it is possible to provide an optical scanning device in which a folding mirror can be fixed to the housing with a simple structure, and an image forming apparatus equipped therewith. [Explanation of symbols]

[0048] 5. Optical scanning device 26 Light source unit (light source) 39 cabinets 40 Bottom 45 Polygon Mirror (Declining Device) 46. ​​Leaf spring (biasing member) 50a~50h Folding mirror (optical element) 51 Reflective surface 52 Mirror fixing structure 53 1st support wall section 54 Second support wall section 55 Back 56 Support protrusion 58 Tip 59 Slope 100 Image forming apparatus L1 1st straight line L2 2nd straight line LB Light Beam P1 center θ1 1st angle θ2, θ2´ 2nd angle

Claims

1. Light source and A deflector that deflects the light beam emitted from the light source, A plurality of optical elements arranged in the optical path of the light beam, A fixing structure that fixes at least one of the multiple optical elements as the object to be fixed, in the thickness direction and the sub-scanning direction of the optical beam, A housing that houses the light source, the deflector, the optical element, and the fixed structure, In an optical scanning device equipped with, The aforementioned fixed structure is A first support wall portion facing the back surface of the object to be fixed in the thickness direction, A second support wall portion that contacts one end face of the fixed object in the aforementioned sub-scanning direction, A biasing member that biases the object to be fixed toward the first support wall, The biasing member and the first support wall portion hold the object to be fixed, The first support wall portion has a support projection that protrudes toward the back surface along the thickness direction and has a tip portion that abuts against the back surface, and an inclined surface that extends from the tip portion toward the side opposite to the second support wall portion. The first angle between the first straight line extending vertically perpendicular to the bottom surface of the housing and the surface of the object to be fixed is smaller than the second angle between the first straight line and the inclined surface. The second angle is less than 90 degrees. Multiple optical elements are, A reflecting mirror that reflects the light beam deflected by the deflector, An imaging lens for forming an image of the aforementioned light beam onto a photoreceptor, Includes, The aforementioned fixing structure uses the folding mirror or the imaging lens among the plurality of optical elements as the object to be fixed. The first support wall portion has a pair of support protrusions aligned in the sub-scanning direction, An optical scanning device characterized in that the second angle of the inclined surface connected to one of the pair of support protrusions in the sub-scanning direction is greater than the second angle of the inclined surface connected to the other of the pair of support protrusions in the sub-scanning direction.

2. The optical scanning apparatus according to claim 1, characterized in that the second angle is 10 degrees or more greater than the first angle.

3. The second support wall portion has a positioning surface that contacts the end face on one side of the object to be fixed, The optical scanning apparatus according to claim 1 or 2, characterized in that the second straight line parallel to the sub-scanning direction that passes through the center of the thickness direction of the fixed object is located on the back side of the positioning surface with respect to the thickness direction.

4. The optical scanning apparatus according to any one of claims 1 to 3, characterized in that the second angle is 70 degrees or less.

5. The optical scanning apparatus according to any one of claims 1 to 4, wherein the fixing structure is arranged in pairs on both ends of the main scanning direction of the object to be fixed, the fixing structure arranged on one end of the main scanning direction has a pair of support protrusions, and the fixing structure arranged on the other end of the main scanning direction has a single support protrusion.

6. The optical scanning apparatus according to any one of claims 1 to 5, characterized in that the fixed object is the folding mirror.

7. The optical scanning device according to any one of claims 1 to 6, characterized in that the tip portion is formed in a planar shape parallel to the back surface.

8. An image forming apparatus comprising an optical scanning device according to any one of claims 1 to 7.

Images