Optical scanning device and image forming apparatus equipped with the same

Abstract

To provide an optical scanner which can effectively prevent reduction in the strength of a housing and thus reduction in the accuracy of an optical member including an fθ lens even when a reference thickness is reduced, and an image formation apparatus having the same.SOLUTION: An optical scanner 100 comprises: a housing 120 in which side walls 123a-123d are erected from a bottom surface 122a so as to surround the bottom surface 122a; and an fθ lens 170 which is stored in the housing 120. An outer side surface 1231d of the side wall 123d being one of the side walls 123a-123d is provided with a positioning part 124 which is positioned with respect to an image formation apparatus body 11. The bottom surface 122a is provided with a first bottom surface rib 131 which extends in the oblique direction with respect to the side wall 123d provided with the positioning part 124 on the fθ lens 170 side from the positioning part 124 in the plan view.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to an optical scanning device and an image forming apparatus including the same, such as a copying machine, a multifunction machine, a printer, or a facsimile machine. [Background technology]

[0002] Background Art There has been known an optical scanning device that includes a box-shaped housing with side walls standing upright from a bottom surface so as to surround the periphery of the bottom surface, and an fθ lens housed in the housing (see, for example, Patent Document 1).

[0003] In such an optical scanning device, in order to reduce the cost of the housing (for example, a housing made of a resin material), it is possible to reduce the reference thickness (for example, the amount of resin). In this case, the strength of the housing is reduced, the housing is easily deformed, and the precision of the optical members including the fθ lens is deteriorated. Therefore, it is desirable to maintain the strength of the housing. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2004-12859 A [Patent Document 2] JP 2019-120796 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, when the reference thickness is reduced, simply forming a large number of ribs on the bottom surface of the housing, as in the optical scanning device described in Patent Document 1, requires material to mold the large number of ribs, resulting in unnecessary costs, and furthermore, it is not possible to prevent a decrease in the strength of the housing and, ultimately, a decrease in the accuracy of the optical components including the fθ lens.

[0006] Therefore, an object of the present invention is to provide an optical scanning device and an image forming apparatus equipped with the same that can effectively prevent a decrease in the strength of the housing and, ultimately, a decrease in the accuracy of optical components including an fθ lens even when the reference thickness is reduced. [Means for solving the problem]

[0007] In order to solve the above problems, the inventors of the present invention have made extensive research and have found the following: That is, in an optical scanning device including a housing having side walls erected from a bottom surface so as to surround the periphery of the bottom surface, and an fθ lens housed in the housing, by providing a positioning portion for positioning the housing relative to the image forming device body on the outer surface of one of the side walls, and providing a rib extending obliquely from the positioning portion to the fθ lens side on the bottom surface in a plan view, it is possible to effectively prevent a decrease in the strength of the housing and, in turn, a decrease in the accuracy of optical members including the fθ lens.

[0008] In addition, in the optical scanning device described in Patent Document 2, a positioning portion for positioning the device with respect to the image forming device body is provided on the outer surface of the side wall, and no rib is provided on the bottom surface.

[0009] The optical scanning device according to the present invention is based on such findings, and is an optical scanning device including a housing having side walls erected from a bottom surface so as to surround the periphery of the bottom surface, and an fθ lens accommodated in the housing, wherein a positioning portion for positioning the lens with respect to a main body of an image forming apparatus is provided on an outer surface of any one of the side walls, and a first bottom surface rib is provided on the bottom surface, the first bottom surface rib extending in an oblique direction from the positioning portion to the side wall on which the positioning portion is provided to the fθ lens side in a plan view, the positioning portion being a plurality of positioning portions, the first bottom surface rib being a plurality of first bottom surface ribs each extending in an oblique direction from the plurality of positioning portions to the side wall on which the positioning portion is provided to the fθ lens side in a plan view, and a virtual straight line extending from the first bottom surface rib passes through the positioning portion in a plan view. The outer surface of the side wall is provided with a plurality of outer surface ribs and a frame wall that protrudes from both side walls of a reflecting mirror that reflects light transmitted through the fθ lens and surrounds both ends in the main scanning direction, and the outer surface ribs on both side walls are connected to the frame wall. It is characterized by: Effect of the Invention

[0010] According to the present invention, even if the reference thickness is reduced, it is possible to effectively prevent a decrease in the strength of the housing, and in turn, a decrease in the accuracy of optical members including the fθ lens. [Brief description of the drawings]

[0011] [Figure 1] 1 is a cross-sectional view showing an image forming apparatus including an optical scanning device according to an embodiment of the present invention. [Diagram 2] 1 is a plan view illustrating a schematic configuration of an optical scanning device according to an embodiment of the present invention; [Diagram 3] 2 is a perspective view of the optical scanning device as viewed obliquely from above on the front side with the top cover removed. FIG. [Figure 4] 4 is a cross-sectional view of the optical scanning device taken along line AA in FIG. 3. [Diagram 5] FIG. 2 is a plan view showing a housing of the optical scanning device. [Figure 6A] FIG. 2 is a perspective view showing a housing of the optical scanning device. [Figure 6B] 1 is a perspective view showing an fθ lens provided in a housing of an optical scanning device. [Figure 6C] FIG. 6C is a perspective cross-sectional view of the housing and the fθ lens shown in FIG. 6B. [Figure 6D] FIG. 6D is a cross-sectional view showing a portion of the cross section shown in FIG. 6C. [Figure 7A] FIG. 6 is a cross-sectional view taken along line BB shown in FIG. 5. [Figure 7B] 6 is a cross-sectional view taken along line CC shown in FIG. 5. [Figure 8A] FIG. 2 is a front view showing a housing of the optical scanning device. [Figure 8B] FIG. 2 is a rear view showing a housing of the optical scanning device. [Figure 8C] FIG. 2 is a left side view showing a housing of the optical scanning device. [Figure 8D] FIG. 2 is a right side view showing a housing of the optical scanning device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following description, the same components are denoted by the same reference numerals. The names and functions of the components are also the same. Therefore, detailed description thereof will not be repeated.

[0013] (Image forming device) 1 is a cross-sectional view showing an image forming apparatus 1 equipped with an optical scanning device 100 according to the present embodiment. In the following description, the direction perpendicular to the main scanning direction X is defined as a width direction Y (sub-scanning direction) and the direction perpendicular to the main scanning direction X and the width direction Y is defined as a vertical direction Z.

[0014] Image data handled in the image forming apparatus main body 11 of the image forming apparatus 1 corresponds to a color image using each of the colors black (K), cyan (C), magenta (M), and yellow (Y), or corresponds to a monochrome image using a single color (e.g., black). For this reason, four developing devices 12, photoconductor drums 13, drum cleaning devices 14, and chargers 15 are provided in each case to form four types of toner images corresponding to the respective colors, and four image stations Pa, Pb, Pc, and Pd are configured corresponding to black, cyan, magenta, and yellow, respectively.

[0015] In each of the image stations Pa, Pb, Pc, and Pd, the drum cleaning devices 14-14 remove and collect residual toner on the surfaces of the photoconductor drums 13-13, and then the chargers 15-15 uniformly charge the surfaces of the photoconductor drums 13-13 to a predetermined potential. The optical scanning device 100 exposes the surfaces of the photoconductor drums 13-13 to light, and an electrostatic latent image is formed on the surfaces of the photoconductor drums 13-13. The developing device 12 develops the electrostatic latent image on the surfaces of the photoconductor drums 13-13 to form a toner image on the surfaces of the photoconductor drums 13-13. As a result, a toner image of each color is formed on the surface of each photoconductor drum 13-13.

[0016] Subsequently, while the intermediate transfer belt 21 is rotated, the belt cleaning device 22 removes and collects the residual toner on the intermediate transfer belt 21, and then the toner images of each color on the surface of each photosensitive drum 13-13 are sequentially transferred and superimposed onto the intermediate transfer belt 21 to form a color toner image on the intermediate transfer belt 21.

[0017] A nip area is formed between the intermediate transfer belt 21 and a transfer roller 23a of the secondary transfer device 23, and the recording paper transported through the paper transport path 31 is sandwiched and transported in the nip area, while the color toner image on the surface of the intermediate transfer belt 21 is transferred onto the recording paper. Then, the recording paper is sandwiched between the heating roller 24 and pressure roller 25 of the fixing device 17 and heated and pressurized, thereby fixing the color toner image on the recording paper.

[0018] The recording paper is pulled out from the paper feed cassette 18 by the pickup roller 33, transported through the paper transport path 31, passed through the secondary transfer device 23 and the fixing device 17, and discharged to the paper discharge tray 39 via the paper discharge rollers 36. On the paper transport path 31, there are arranged a registration roller 34 which temporarily stops the recording paper, aligns the leading edge of the recording paper, and then starts transporting the recording paper in accordance with the transfer timing of the toner image in the nip area between the intermediate transfer belt 21 and the transfer roller 23a, a transport roller 35 which promotes the transport of the recording paper, and the like.

[0019] (Optical scanning device) Next, an example of the optical scanning device 100 according to the present embodiment that is provided in the image forming apparatus 1 will be described below.

[0020] FIG. 2 is a plan view showing the optical scanning device 100 according to the present embodiment. FIG. 3 is a perspective view of the optical scanning device 100 with the top cover 121 removed, viewed from diagonally above the front side. FIG. 4 is a cross-sectional view of the optical scanning device 100 taken along the line AA shown in FIG. 3. FIG. 5 is a plan view showing the housing 120 in the optical scanning device 100. FIG. 6A is a perspective view showing the housing 120 in the optical scanning device 100. FIG. 6B is a perspective view showing the state in which the fθ lens 170 is provided in the housing 120 in the optical scanning device 100. FIG. 6C is a perspective view showing the housing 120 and the fθ lens 170 shown in FIG. 6B in cross section. FIG. 6D is a cross-sectional view showing a part of the cross section shown in FIG. 6C.

[0021] The optical scanning device 100 includes a rectangular top cover 121 (see FIG. 2) and a housing 120. The housing 120 is made of a resin material and has a bottom plate 122 and four side walls 123a to 123d (see FIG. 6) surrounding the bottom plate 122. The side walls 123a to 123d are the front, rear, left and right side walls, respectively. The housing 120 is closed by the top cover 121 and is dustproof. As shown in FIG. 2, the optical scanning device 100 guides light beams L to L emitted from a plurality of light emitting elements (semiconductor lasers) 151 to 151, which are light sources, to a reflecting surface of a deflector 140 (polygon mirror), and the light beams L to L are reflected and deflected by the reflecting surface of the deflector 140.

[0022] The reflected light beams L-L are guided to the photoconductor drums 13-13, which serve as scanned bodies, by the optical members provided within the housing 120. The optical scanning device 100 is configured to scan the corresponding photoconductor drums 13-13 with the light beams L-L.

[0023] From the light emitting elements 151 to the deflector 140, four collimator lenses 152, four first mirrors 153a, 153b, a cylindrical lens 154, and a second mirror 155 are arranged in this order from the light emitting elements 151 to the deflector 140.

[0024] The collimator lenses 152-152 convert the light beams L-L emitted from the light emitting elements 151-151 into parallel light. The three first mirrors 153b-153b reflect the light beams L-L incident from the three light emitting elements 151-151 through the respective collimator lenses 152-152 to the one first mirror 153a. The one first mirror 153a reflects the light beams L-L reflected by the three first mirrors 153b-153b to the cylindrical lens 154. The light beam L transmitted through the collimator lens 152 from the other one light emitting element 151 passes above the first mirror 153a and enters the cylindrical lens 154. The cylindrical lens 154 converges the light beam L only in the sub-scanning direction and collects it on the reflecting surface of the deflector 140 via the second mirror 155.

[0025] The deflector 140 rotates at high speed around a rotation axis G, and reflects the light beams L to L on each reflective surface to repeatedly deflect them in the main scanning direction X.

[0026] 4, in the optical scanning device 100, a plurality of reflecting mirrors 161-168 are provided in a housing 120 so as to guide the light beams L deflected by the deflector 140 to each of the photosensitive drums 13. In detail, in the optical path from the deflector 140 to each of the photosensitive drums 13, a common fθ lens 170, a plurality of reflecting mirrors 161-168, and a plurality of (four in this example) fθ lenses 110 are arranged in the order from the deflector 140 to each of the photosensitive drums 13.

[0027] The multiple reflecting mirrors 161-168 reflect the incident light beams L-L toward the respective photoconductor drums 13-13. As shown in FIG. 2, the top cover 121 is formed with four dustproof windows 121a-121a that allow the reflected light beams L-L to pass through. The dustproof windows 121a-121a are configured to close the opening of the top cover 121 by, for example, transparent glass. The light beams L-L that have passed through the dustproof windows 121a-121a are imaged on the photoconductor drums 13-13.

[0028] The fθ lens 170 is made of a resin material and extends in the main scanning direction X. The fθ lens 170 condenses the light beams L to L to have a predetermined beam diameter on the surface of each of the photoconductor drums 13 and emits them. The fθ lens 170 also converts the light beams L to L deflected at a constant angular velocity in the main scanning direction X by the deflector 140 so that they move at a constant linear velocity along the main scanning line on each of the photoconductor drums 13. As a result, the light beams L to L repeatedly scan the surfaces of each of the photoconductor drums 13 in the main scanning direction X.

[0029] A plurality of reflecting mirrors 161-168 provided on the optical path reflect the light beams L-L transmitted through the fθ lens 170 and make the light beams enter the plurality of fθ lenses 110-110, respectively. The plurality of fθ lenses 110-110 are made of a resin material and extend in the main scanning direction X. The plurality of fθ lenses 110-110 mainly focus the parallel light beams L-L in the sub-scanning direction and narrow the light beams to a predetermined beam diameter (spot diameter) on the surfaces of the respective photoconductor drums 13-13, and also emit the convergent light beams L-L to the respective photoconductor drums 13-13 in the main scanning direction X.

[0030] In the optical scanning device 100 described above, each of the light beams L-L is reflected and deflected by the reflecting surface of the deflector 140, passes through each of the optical paths, and is incident on each of the photoconductor drums 13-13, and repeatedly performs main scanning on the surface of each of the photoconductor drums 13-13. As each of the photoconductor drums 13-13 is rotationally driven, each of the light beams L-L scans the surface (circumferential surface) of each of the photoconductor drums 13-13, and an electrostatic latent image is formed on the surface of each of the photoconductor drums 13-13.

[0031] (About this embodiment) Figures 7A and 7B are cross-sectional views taken along lines BB and CC shown in Figure 5. Figures 8A to 8D are a front view, a rear view, a left side view, and a right side view, respectively, showing housing 120 of optical scanning device 100.

[0032] The optical scanning device 100 includes a housing 120 and an fθ lens 170. The housing 120 has side walls 123a to 123d standing upright from the bottom surface 122a of a bottom plate 122 so as to surround the periphery of the bottom surface 122a. That is, the bottom surface 122a and the side walls 123a to 123d are formed in a U-shape in cross section. The fθ lens 170 is accommodated in the housing 120.

[0033] An outer surface 1231d of one of the side walls 123a to 123d (123d in this example) is provided with one or more (two in this example) positioning portions 124 (124a, 124b) for positioning with respect to the image forming device body 11. That is, the positioning portions 124 (124a, 124b) position the optical scanning device body 101 with respect to the image forming device body 11. The bottom surface 122a is provided with a first bottom surface rib 131 (131a, 131b) extending in a diagonal direction from the positioning portion 124 to the fθ lens 170 side in a plan view with respect to the side wall 123d on which the positioning portion 124 is provided.

[0034] According to this embodiment, the first bottom rib 131 provided on the bottom surface 122a of the housing 120 extends in a diagonal direction from the positioning portion 124 to the sidewall 123d on which the positioning portion 124 is provided toward the fθ lens 170 in a plan view. This makes it possible to reinforce the housing 120. Therefore, even if the reference thickness is reduced, it is possible to effectively prevent a decrease in the strength of the housing 120 and, in turn, a decrease in the accuracy of the optical members including the fθ lens 170.

[0035] Here, the reference thickness can be the thickness of the main portion (the portion with the largest area) (specifically, the bottom plate 122 and the side walls 123a to 123d). In this example, the reference thickness is about 2.0 mm.

[0036] First Embodiment In this embodiment, the positioning portion 124 is a plurality of (two in this example) positioning portions 124a and 124b. The first bottom surface rib 131 is a plurality of first bottom surface ribs 131a and 131b each extending in a diagonal direction from the plurality of positioning portions 124a and 124b to the sidewall 123d on which the positioning portion 124 is provided toward the fθ lens 170 in a plan view.

[0037] In this way, the housing 120 can be further reinforced by the multiple first bottom ribs 131a, 131b, and the deterioration of the strength of the housing 120, and therefore the deterioration of the precision of the optical components including the fθ lens 170, can be more effectively prevented.

[0038] Specifically, the positioning portions 124a and 124b are protrusions extending outward in the width direction Y from the outer surface 1231d of the side wall 123d, and are arranged side by side at a distance in the main scanning direction X at the same position in the up-down direction Z (the direction of the rotation axis G of the deflector 140) on the outer surface 1231d of the side wall 123d. The positioning portions 124a and 124b are provided on both sides of the outer surface 1231d in the main scanning direction X. The first bottom surface ribs 131a and 131b are formed so that a virtual straight line α (α1, α2) (see FIG. 5) extending from the first bottom surface ribs 131a and 131b passes through the positioning portions 124a and 124b. The first bottom surface ribs 131a and 131b are extended from the positioning portions 124a and 124a toward the center in the main scanning direction X toward the fθ lens 170.

[0039] <Second embodiment> In this embodiment, first bottom surface ribs 131a, 131b extending from a plurality of (two in this example) positioning portions 124a, 124b intersect with each other.

[0040] In this manner, the housing 120 can be further reinforced by the first bottom ribs 131a, 131b extending from the multiple positioning portions 124a, 124b and intersecting each other, and thus the deterioration of the strength of the housing 120 and, ultimately, the deterioration of the accuracy of the optical components including the fθ lens 170 can be more effectively prevented.

[0041] <Third embodiment> In this embodiment, the first bottom rib 131 (131a, 131b) extends to an end (in this example, both side walls 123a, 123b) in a direction (main scanning direction X) along the outer surface 1231d on which the positioning portion 124 (124a, 124b) is provided on the bottom surface 122a of the housing 120.

[0042] In this way, the housing 120 can be further reinforced by the first bottom rib 131 (131a, 131b) extending to the end of the bottom surface 122a of the housing 120, and the deterioration of the strength of the housing 120 and, ultimately, the deterioration of the accuracy of the optical components including the fθ lens 170 can be more effectively prevented.

[0043] <Fourth embodiment> In this embodiment, a protrusion 125 protruding from the bottom surface 122a is provided on the bottom surface 122a of the housing 120. An fθ lens 170 is provided on the top surface 125b of the protrusion 125. More specifically, the protrusion 125 is connected to the side wall 123c opposite to the side wall 123d on which the positioning portion 124 is provided. The protrusion 125 forms a step that is higher by a predetermined height from the side on which the positioning portion 124 of the bottom surface 122a is provided. The protrusion 125 is provided on the side opposite to the side on which the positioning portion 124 is provided, relative to the center of the bottom surface 122a in the width direction Y of the housing 120.

[0044] Incidentally, when protrusion 125 is provided on bottom surface 122a of housing 120, the strength of protrusion 125 in housing 120 is greater than the strength of the parts other than protrusion 125.

[0045] In this regard, in the present embodiment, the first bottom surface rib 131 (131a, 131b) is connected to the side surface 125a of the protruding portion 125.

[0046] In this way, the housing 120 can be further reinforced by the first bottom rib 131 connected to the side surface 125a of the protrusion 125, and a decrease in the strength of the housing 120, and therefore a decrease in the accuracy of the optical components including the fθ lens 170, can be more effectively prevented.

[0047] In this embodiment, the protruding portion 125 is connected to the side walls 123a and 123b on both sides in a direction (main scanning direction X) along the outer surface 1231d on which the positioning portion 124 is provided.

[0048] In this way, the housing 120 can be further reinforced by the first bottom rib 131 connected to the side surface 125a of the protrusion 125, and a decrease in the strength of the housing 120, and therefore a decrease in the accuracy of the optical components including the fθ lens 170, can be more effectively prevented.

[0049] <Fifth embodiment> Incidentally, when no protrusion 125 is provided on the bottom surface 122a, in order to further reinforce the housing 120, it is preferable that the first bottom surface rib 131 (131a, 131b) extends to the diagonal corner portions β (βa, βb) (see FIG. 5) of the housing 120 in a plan view.

[0050] However, in this embodiment, since the protrusion 125 is provided on the bottom surface 122a of the housing 120, the first bottom surface rib 131 (131a, 131b) extends to the corner portion γ (γa, γb) (see FIG. 5) between the protrusion 125 and the side wall (123a, 123b) in a plan view. In detail, the first bottom surface rib 131 extends to the diagonal corner portion γ (γa, γb). In this example, the side wall constituting the corner portion γ (γa, γb) is the side wall 123a, 123b on both sides in the direction along the outer surface 1231d of the housing 120 (main scanning direction X).

[0051] In this way, the housing 120 can be further reinforced by the first bottom rib 131 (131a, 131b), which extends to the corner portion γ (γa, γb) between the protrusion 125 and the side wall (123a, 123b) in a planar view, and the deterioration of the strength of the housing 120 and, ultimately, the deterioration of the accuracy of the optical components including the fθ lens 170 can be more effectively prevented.

[0052] Sixth embodiment In this embodiment, the housing 120 has outer peripheral walls 126a-126d erected outward from the outer surfaces 1231a-1231d so as to surround the outer surfaces 1231a-1231d of the side walls 123a-123d. In the erecting direction (vertical direction Z) of the side walls 123a-123d from the bottom surface 122a of the housing 120, the outer peripheral wall 126a on the top side of the outer peripheral walls 126a-126d is provided with an erected wall 127 erected in the erecting direction. That is, the outer surfaces 1231a-1231d and the outer peripheral walls 126a-126d are formed in a U-shape in cross section.

[0053] In this way, by erecting the outer peripheral walls 126a to 126d from the outer surfaces 1231a to 1231d of the side walls 123a to 123d and erecting the upright wall 127 in the upright direction from the top-side outer peripheral wall 126a in the upright direction (vertical direction Z) from the bottom surfaces 122a of the side walls 123a to 123d, the strength of the side walls 123a to 123d can be improved.

[0054] In this example, the standing wall 127 stands upright from the outer edge 126a1 of the outer peripheral wall 126a. This can further improve the strength of the side walls 123a to 123d. This can more effectively prevent a decrease in the strength of the housing 120, and therefore a decrease in the accuracy of the optical members including the fθ lens 170.

[0055] Seventh embodiment In this embodiment, a plurality of outer surface ribs 132-132 intersecting with each other are provided in the outer peripheral wall 126a-126d of at least one (in this example, all) of the side walls 123a-123d surrounding the periphery of the bottom surface 122a. The plurality of outer surface ribs 132-132 are inclined with respect to the outer peripheral walls 126a-126d.

[0056] In this way, the strength of the side walls (123a to 123d) can be further improved by the multiple outer surface ribs 132-132 provided in the outer peripheral walls 126a to 126d and intersecting with each other, which can more effectively prevent a decrease in the strength of the housing 120 and, in turn, a decrease in the accuracy of the optical members including the fθ lens 170.

[0057] In this example, the outer surface ribs 132-132 are connected to the outer peripheral walls 126a-126d. In addition, both ends of the reflection mirrors 162, 165, 167, 168 in the main scanning direction X are protruded from the side walls 123a, 123b (see Figs. 8A and 8B) on both sides of the outer peripheral walls 126a-126d in the main scanning direction X. Therefore, the outer surfaces 1231a, 1231b of the side walls 123a, 123b are provided with frame walls 128-128 having a rectangular shape in a plan view in order to secure both ends of the reflection mirrors 162, 165, 167, 168 in the main scanning direction X. The outer surface ribs 132-132 on the side walls 123a, 123b are also connected to the frame walls 128-128.

[0058] Eighth embodiment In this embodiment, the optical scanning device 100 includes a plurality of fθ lenses 110-110 provided downstream of the fθ lens 170 in the traveling direction of the light beam L. A second bottom surface rib 133 is provided on the bottom surface 122a. The second bottom surface rib 133 is connected to both side walls 123a, 123b in a direction (main scanning direction X) along the outer surface 1231d so as to be aligned along the outer surface 1231d on which the positioning portion 124 (124, 124) is provided between adjacent fθ lenses 110, 110 among the plurality of fθ lenses 110-110.

[0059] This allows the second bottom rib 133 to be connected to the side walls 123a, 123b on both sides, thereby further reinforcing the housing 120 and more effectively preventing a decrease in the strength of the housing 120 and therefore a decrease in the precision of the optical members including the multiple fθ lenses 110-110.

[0060] In this embodiment, a third bottom rib 134 (see FIGS. 5 and 6) extending along the width direction Y is provided in the center in the direction (main scanning direction X) along the outer side surface 1231d on which the positioning portion 124 is provided.

[0061] The inclination angle of the first bottom rib 131 with respect to the side wall 123d and the inclination angle of the outer side rib 132 with respect to the outer peripheral wall 126a are not limited to, but may be, for example, about 30° to 60°. The heights of the first bottom rib 131, the second bottom rib 133, and the third bottom rib 134 are preferably as high as possible without blocking the light beam L, and may be, for example, about 10 mm to 20 mm, and more preferably about 15 mm to 20 mm, but are not limited to, for example. The height of the outer side rib 132 is preferably as high as possible without increasing the size of the device configuration, and may be, for example, about 10 mm to 20 mm, and more preferably about 15 mm to 20 mm, but are not limited to, for example. The thickness of the first bottom rib 131, the outer side rib 132, the second bottom rib 133, and the third bottom rib 134 is equal to or less than a reference thickness (e.g., 2 mm), and can be, but is not limited to, about the reference thickness (2 mm) to about 3 / 4 (1.5 mm) of the reference thickness. In a conventional housing, the height of the bottom rib is less than 10 mm, for example, about 4 mm to 5 mm.

[0062] In this example, the second bottom rib 133 is higher than the first bottom rib 131 and the third bottom rib .

[0063] In this embodiment, a plurality of fourth bottom surface ribs 135-135 (see FIGS. 5 and 6) are provided along the side walls (123a-123d) on the upper surface 125b of the protruding portion 125. In addition, a plurality of fifth bottom surface ribs 136-136 (see FIGS. 5 and 6) inclined relative to the side walls (123a-123d) are provided on the upper surface 125b of the protruding portion 125.

[0064] <Other embodiments> Although a plurality of positioning portions 124 are provided on the side wall 123d, only one positioning portion 124 may be provided. In this case, the positioning portion 124 extends obliquely from the positioning portion 124 to the fθ lens 170 side with respect to the side wall 123d in a plan view.

[0065] <Strength analysis simulation> Next, a simulation of strength analysis was performed on the housing 120 according to the present embodiment and a housing of a conventional configuration, which will be described below.

[0066] In this strength analysis simulation, a predetermined constant pressure was applied to the housing to distort it and measure the maximum deformation amount when the reference thickness of the housing of the conventional configuration was set to 2.5 mm and when the reference thickness of the housing of the conventional configuration and housing 120 according to this embodiment was set to 2.0 mm. As a result, when the reference thickness was set to 2.5 mm, the maximum deformation was 1.4 mm, whereas when the reference thickness was set to 2.0 mm from the viewpoint of cost reduction, the maximum deformation was 2.8 mm, and the strength was significantly reduced.

[0067] On the other hand, when the standard thickness of housing 120 in this embodiment was set to 2.0 mm, the maximum deformation was 1.6 mm, and the strength was maintained at the same level as that of a conventional housing with a standard thickness of 2.5 mm.

[0068] The present invention is not limited to the above-described embodiment, but can be embodied in various other forms. Therefore, the embodiment is merely illustrative in all respects and should not be interpreted as being restrictive. The scope of the present invention is defined by the claims, and is not limited in any way by the text of the specification. Furthermore, all modifications and changes within the scope of the claims are within the scope of the present invention. [Explanation of symbols]

[0069] 1. Image forming device 11 Image forming device main body 13 Photoconductor drum 100 Optical scanning device 110 Multiple fθ lenses 120 Case 122 Bottom plate 122a Bottom 1231a External surface 1231b External surface 1231c External surface 1231d External surface 123a side wall 123b side wall 123c side wall 123d side wall 124 Positioning part 124a Positioning part 124b Positioning part 125 Protrusion 125a side 125b top surface 126a Peripheral wall 126a1 Outer edge 126b Peripheral wall 126c outer wall 126d outer wall 127 Vertical Wall 131 First bottom rib 131a 1st bottom rib 131b First bottom rib 132 Outer surface rib 133 Second bottom rib 134 3rd bottom rib 135 4th bottom rib 136 5th bottom rib 140 Deflector 170 fθ lens L Light beam X main scanning direction Y Width direction Z vertical direction α Imaginary line β Corner part γ Corner part

Claims

1. An optical scanning device comprising: a housing having a side wall extending from a bottom surface so as to surround the periphery of the bottom surface; and an fθ lens housed in the housing, a positioning portion for positioning the image forming apparatus with respect to a main body of the image forming apparatus is provided on an outer surface of any one of the side walls; a first bottom surface rib is provided on the bottom surface, the first bottom surface rib extending in an oblique direction from the positioning portion to the fθ lens side in a plan view with respect to a side wall on which the positioning portion is provided, the positioning portion is a plurality of positioning portions, and the first bottom surface rib is a plurality of first bottom surface ribs each extending in a diagonal direction from the plurality of positioning portions to a side wall on which the positioning portions are provided toward the fθ lens in a plan view; a virtual straight line extending from the first bottom surface rib passes through the positioning portion in a plan view, An optical scanning device characterized in that the outer surface of the side wall is provided with a plurality of outer surface ribs and a frame wall surrounding both ends in the main scanning direction of a reflection mirror that reflects light that has passed through the fθ lens, and the outer surface ribs on both side walls are connected to the frame wall.

2. 2. The optical scanning device according to claim 1, The optical scanning device according to claim 1, wherein the first bottom ribs extending from the positioning portions intersect with each other.

3. 3. The optical scanning device according to claim 1, The optical scanning device according to claim 1, wherein the first bottom rib extends to an end of the bottom surface of the housing in a direction along the outer surface on which the positioning portion is provided.

4. An optical scanning device according to any one of claims 1 to 3, a protrusion protruding from the bottom surface of the housing; The fθ lens is provided on an upper surface of the protruding portion, The optical scanning device according to claim 1, wherein the first bottom rib is connected to a side surface of the protrusion.

5. 5. The optical scanning device according to claim 4, The optical scanning device according to claim 1, wherein the protrusion is connected to the side walls on both sides in a direction along the outer surface on which the positioning portion is provided.

6. 6. The optical scanning device according to claim 4, The optical scanning device according to claim 1, wherein the first bottom rib extends to a corner portion between the protrusion and the side wall in a plan view.

7. 7. An optical scanning device according to claim 1, the housing has an outer peripheral wall extending outward from the outer surface of the side wall so as to surround the outer surface of the side wall, An optical scanning device characterized in that, in a direction in which the side walls rise from the bottom surface of the housing, a top side of the outer peripheral wall is provided with an upright wall that rises in the upright direction.

8. 8. The optical scanning device according to claim 7, An optical scanning device, characterized in that a plurality of outer surface ribs intersecting each other are provided within the outer peripheral wall.

9. An optical scanning device according to any one of claims 1 to 8, a plurality of fθ lenses provided downstream of the fθ lens in a traveling direction of the light beam; An optical scanning device characterized in that the bottom surface is provided with a second bottom surface rib connected to the side walls on both sides in a direction along the outer surface so as to follow the outer surface on which the positioning portion is provided between adjacent fθ lenses among the plurality of fθ lenses.

10. 10. An image forming apparatus comprising the optical scanning device according to claim 1.

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