Optical scanner and image forming apparatus

Abstract

To provide an optical scanner that can be mounted in different image forming apparatuses, and that is inexpensive and can improve its assemblability.SOLUTION: An optical box has a plurality of reference surfaces that are attachment surfaces to an image forming apparatus, and a plurality of flat surfaces that are arranged on the front face and rear face of each of the plurality of reference surfaces with respect to a rotation axis direction of a rotary polygon mirror and are each in parallel with each of the plurality of reference surfaces.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an optical scanning device mounted in an electrophotographic image forming apparatus such as a copying machine or a printer, and to an image forming apparatus equipped with this optical scanning device. [Background technology]

[0002] One possible method for reducing the cost of image forming devices is to use a common housing (optical box) for the optical scanning device for different types of image forming devices. Patent Document 1 proposes using a laser scanner with the same housing for monochrome printers and color printers. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-21156 Summary of the Invention [Problem to be solved by the invention]

[0004] However, different types of image forming apparatuses may have different positional relationships between the photosensitive drums and the optical scanning devices within the image forming apparatuses, which can cause problems when assembling the image forming apparatuses.

[0005] 15 and 16 are cross-sectional and perspective views showing the process of assembling an optical scanning device 201, which has the same housing, into two types of image forming apparatuses 210 and 220. Note that in both Figures 15 and 16, components other than the image forming apparatus support portion 202 that supports the optical scanning device 201, the optical scanning device 201, and the photosensitive drum 203 are omitted. Compared to the first image forming apparatus 210, the second image forming apparatus 220 has the photosensitive drum 203 and the optical scanning device 201 in the up-down positional relationship reversed.

[0006] When the first image forming apparatus 210 is assembled on a manufacturing line, the optical scanning device 201 is attached to the support portion 202 of the first image forming apparatus 210 from above. Reference symbol PB denotes a positioned portion provided on the housing of the optical scanning device 201, and reference symbol PH denotes a positioning portion provided on the support portion 202. On the other hand, when the second image forming apparatus 220 is assembled on a manufacturing line, the optical scanning device 201 is attached to the support portion 202 from below. Alternatively, the optical scanning device 201 is attached to the support portion 202 from above with the main body frame to which the support portion 202 is fixed turned upside down.

[0007] When the optical scanning device 201 is attached from the underside of the support portion 202, the attachment position and the fixing points with springs, screws, etc. are hard to see for the assembly worker, and the work space is narrow, making it difficult for the assembly worker to access the fixing points, which makes assembly difficult. Also, when the main body frame of the image forming apparatus is turned upside down, the number of steps increases, which leads to increased costs.

[0008] SUMMARY OF THE INVENTION An object of the present invention is to provide an optical scanning device that can be mounted on different image forming apparatuses, is inexpensive, and can be easily assembled. [Means for solving the problem]

[0009] In order to solve the above-mentioned problems, the present invention provides an optical scanning device that is mounted on an image forming device that forms a toner image on a recording material, the optical scanning device having a light source, a deflection unit with a rotating polygon mirror that deflects a laser beam emitted by the light source, a lens that forms an image of the laser beam scanned by the deflection unit, and an optical box that houses the deflection unit and the lens, the optical box having a plurality of reference surfaces that are attachment surfaces to the image forming device, and a plurality of flat surfaces that are arranged directly behind each of the plurality of reference surfaces in the direction of the rotation axis of the rotating polygon mirror, and each of which is parallel to each of the plurality of reference surfaces. [Effects of the Invention]

[0010] As described above, according to the present invention, it is possible to provide an optical scanning device that can be mounted on different image forming apparatuses, is inexpensive, and allows for improved assembly. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. [Figure 2] FIG. 2 is a perspective view of the front side of the optical scanning device. [Figure 3] FIG. 2 is a perspective view of the rear side of the optical scanning device. [Figure 4] FIG. 4 is a partial enlarged view of FIGS. 2 and 3. [Figure 5] FIG. 2 is a plan view of the front surface side of the optical scanning device. [Figure 6] FIG. 2 is a plan view of the rear side of the optical scanning device. [Figure 7] FIG. 2 is a perspective view of a main body frame of the first image forming apparatus. [Figure 8] FIG. 2 is a perspective view of the first image forming apparatus with a scanner unit attached to a main body frame. [Figure 9] FIG. 2 is a cross-sectional view of the first image forming apparatus with a scanner unit attached to a main body frame. [Figure 10] FIG. 10 is a perspective view of a main body frame of the second image forming apparatus. [Figure 11] FIG. 10 is a perspective view of the second image forming apparatus with the scanner unit attached to the main body frame. [Figure 12] FIG. 10 is a cross-sectional view of the second image forming apparatus with the scanner unit attached to the main body frame. [Figure 13] FIG. 10 is a perspective view of a scanner unit and a main body frame of a first image forming apparatus according to a second embodiment. [Figure 14] FIG. 10 is a perspective view of a scanner unit and a main body frame of a second image forming apparatus according to a second embodiment. [Figure 15] 10A and 10B are explanatory diagrams illustrating how the scanner unit is attached to different types of image forming apparatuses. [Figure 16] 10A and 10B are explanatory diagrams illustrating how the scanner unit is attached to different types of image forming apparatuses. DETAILED DESCRIPTION OF THE INVENTION

[0012] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, with reference to the drawings, an embodiment of the present invention will be described in detail by way of example.

[0013] Example 1 (Image forming device) 1 is a cross-sectional view of an image forming apparatus 110 including an optical scanning device (scanner unit) 101 according to embodiment 1. Here, a laser beam printer will be exemplified as the image forming apparatus 110.

[0014] The optical scanning device 101 scans a photosensitive drum (photoconductor) 103 built in a process cartridge 102 with a laser beam corresponding to image information. An electrostatic latent image formed on the photosensitive drum 103 by this scanning is developed by a developing device (not shown) mounted in the process cartridge 102, and a toner image is formed on the photosensitive drum 103. The process cartridge 102 integrally includes the photosensitive drum 103 and a charger, developing device, etc. as process means acting on the photosensitive drum 103.

[0015] Meanwhile, recording materials P stacked on a stacking plate 104 are fed while being separated one by one by a feeding roller 105, and then conveyed further downstream by an intermediate roller 106. A toner image formed on a photosensitive drum 103 is transferred onto the conveyed recording material P by a transfer roller 107. The recording material P with this unfixed toner image formed thereon is conveyed further downstream, where the toner image is fixed to the recording material P by a fixing device 108 having a heating element therein. Thereafter, the recording material P is discharged to the outside of the image forming apparatus 110 by a discharge roller 109.

[0016] In this embodiment, the charger and developer as process means acting on the photosensitive drum 103 are integrally provided with the photosensitive drum 103 in the process cartridge 102, but each process means may also be configured separately from the photosensitive drum 103.

[0017] (Optical scanning device) 2, 3, and 4 are perspective views of the front side and rear side of the optical scanning device 101. Note that FIG. 4 is a partial enlarged view of FIGS. 2 and 3. Here, the Z direction is the direction of the rotation axis of the rotation axis of the rotating polygon mirror 4. Note that for the sake of explanation, the cover member 10 that covers the opening of the optical scanning device 101 is omitted in FIG. 2.

[0018] The optical scanning device 101 includes an optical box 9 that houses a laser unit (light source) 1, a deflection unit 5, an fθ lens 7, and a folding mirror 8, and a cover member 10 that covers the opening of the optical box. Inside the optical box 9, the laser unit 1, an anamorphic collimator lens 2, an aperture stop 3, a deflection unit 5 having a rotating polygonal mirror 4, a signal detection sensor 6, an fθ lens 7 (scanning lens), and a folding mirror 8 are housed.

[0019] The laser unit 1 has a semiconductor laser (not shown) and emits a laser beam. The anamorphic collimator lens 2 is a lens formed by integrally molding a collimator lens and a cylindrical lens. The deflection unit 5 has a rotary polygon mirror 4 that deflects and scans the laser beam L emitted by the laser unit 1, and a motor (not shown) that rotates the rotary polygon mirror 4.

[0020] The laser beam L emitted from the laser unit 1 is converted by the anamorphic collimator lens 2 into a substantially parallel or convergent beam in the main scanning direction, and into a convergent beam in the sub-scanning direction. The laser beam L then passes through an aperture stop 3, where its beam width is restricted, and is imaged as a focal line extending long in the main scanning direction on the reflecting surface of a rotating polygon mirror 4. The laser beam L is then deflected and scanned by rotating the rotating polygon mirror 4, and enters a signal detection sensor 6.

[0021] At this time, a signal is detected by the signal detection sensor 6, and this timing is used as the synchronization detection timing for the writing start position in the main scanning direction. Next, the laser beam L is incident on the fθ lens 7. The fθ lens 7 is a lens that focuses the laser beam L scanned by the deflection unit 5 onto the surface of the photosensitive drum 103. The fθ lens 7 is designed to focus the laser beam L to form a spot on the photosensitive drum 103 and to maintain a constant scanning speed of the spot. To obtain these characteristics of the fθ lens 7, the fθ lens 7 is made of an aspherical lens. After passing through the fθ lens 7, the laser beam L is reflected by the folding mirror 8, emitted from the exit port of the optical box 9, and imaged and scanned onto the photosensitive drum 103.

[0022] The laser beam is deflected and scanned by the rotation of the rotary polygon mirror 4, and main scanning is performed by the laser beam on the photosensitive drum 103, and sub-scanning is performed by rotating the photosensitive drum 103 about its cylindrical axis. In this way, an electrostatic latent image is formed on the surface of the photosensitive drum 103.

[0023] The optical box 9 has first reference surfaces 11a to 11d and second reference surfaces 12a to 12d. The first reference surfaces 11a to 11d and the second reference surfaces 12a to 12d are parallel to each other. When the optical box 9 is viewed in the Z-axis direction, first pressing portions 13a to 13d are provided near the rear sides of the first reference surfaces 11a to 11d, respectively, and second pressing portions 14a to 14d are provided near the rear sides of the second reference surfaces 12a to 12d, respectively. The optical box 9 also has a positioning hole 15 and an anti-rotation hole 16. The positioning hole 15 is a circular hole, and the anti-rotation hole 16 is an elongated hole. In the Z-axis direction, the first pressing portions 13a to 13d are lower than the second reference surfaces 12a to 12d, and the second pressing portions 14a to 14d are lower than the first reference surfaces 11a to 11d.

[0024] The optical scanning device 101 described above is positioned in the Z-axis direction by abutting the first reference surfaces 11a to 11d or the second reference surfaces 12a to 12d against a main body frame (described later) of the image forming device 110 (or the image forming device 111). This ensures the optical performance of the optical scanning device 101 in the image forming device 110 (or the image forming device 111). A first vector V1 that is perpendicular to the first reference surfaces 11a to 11d and points away from the first reference surfaces 11a to 11d faces in the -Z direction. A second vector V2 that is perpendicular to the second reference surfaces 12a to 12d and points away from the second reference surfaces 12a to 12d faces in the +Z direction.

[0025] The optical scanning device 101 is attached to the first image forming device 110 using first reference surfaces 11a to 11d and first pressing portions 13a to 13d. When the optical scanning device 101 is attached to the first image forming device 110, the first reference surfaces 11a to 11d correspond to the plurality of reference surfaces. The second reference surfaces 12a to 12d are disposed directly behind the plurality of reference surfaces 11a to 11d in the direction of the rotation axis of the rotary polygon mirror 4, and correspond to the plurality of planes parallel to the plurality of reference surfaces 11a to 11d, respectively.

[0026] Conversely, the optical scanning device 101 is attached to a second image forming device 111 (described later) using second reference surfaces 12a to 12d and second pressing portions 14a to 14d. When the optical scanning device 101 is attached to the second image forming device 111, the second reference surfaces 12a to 12d correspond to the plurality of reference surfaces. The first reference surfaces 11a to 11d are disposed directly behind the plurality of reference surfaces 12a to 12d in the direction of the rotation axis of the rotating polygon mirror 4, and correspond to the plurality of planes parallel to the plurality of reference surfaces 12a to 12d, respectively.

[0027] Fig. 5 is a diagram showing the front surface of optical scanning device 101 (the surface on which the surfaces on which optical elements such as rotating polygon mirror 4 are mounted are visible). Fig. 6 is a diagram showing the rear surface of optical scanning device 101. A rectangular area formed by connecting each of first reference surfaces 11a to 11d is designated as S1, and a rectangular area formed by connecting each of second reference surfaces 12a to 12d is designated as S2. When viewed in the direction of the rotation axis of rotating polygon mirror 4, laser unit 1, anamorphic collimator lens 2, rotating polygon mirror 4, fθ lens 7, and folding mirror 8 are arranged inside rectangles S1 and S2.

[0028] Next, a method for attaching the optical scanning device 101 to the first image forming apparatus 110 will be described. For the sake of explanation, in the following drawings, of the components of the image forming apparatus 110 described in FIG. 1, parts other than the optical scanning device 101, the main body frame 17 of the image forming apparatus 110, and the photosensitive drum 103 are omitted.

[0029] 7 is a perspective view of the main body frame 17 of the first image forming apparatus 110. The main body frame 17 of the first image forming apparatus 110 has side plates 18 and 19. Stays 20 and 21, to which the optical scanning device 101 is attached, are fixed to the side plates 18 and 19. The stay 20 has an abutment surface 20a, positioning portions 20b and 20c, spring hook portions 20d and 20e, a through hole 20h through which the laser beam emitted from the optical scanning device 101 passes, and a narrowing portion 20g for increasing the rigidity of the stay 20. The stay 21 has an abutment surface 21a and spring hook portions 21b and 21c.

[0030] Fig. 8 is a perspective view of the state in which the optical scanning device 101 is attached to the main body frame 17. Fig. 9 is a cross-sectional view of the state in which the optical scanning device 101 is attached to the main body frame 17.

[0031] The optical scanning device 101 is supported by the stays 20 and 21 with first reference surfaces 11a to 11d of the optical box 9 abutting against corresponding abutment surfaces 20a and 21a, respectively. Furthermore, the optical scanning device 101 is positioned on the main body frame 17 by fitting a positioning hole 15 of the optical box 9 with a positioning portion (protrusion) 20b of the stay 20 and inserting a positioning portion (protrusion) 20c of the stay 20 into an anti-rotation hole 16 of the optical box 9. That is, the optical box 9 is provided with holes 15 and 16 into which the positioning portions 20b and 20c are inserted to determine the position of the optical scanning device 101 in a plane direction perpendicular to the rotation axis direction of the rotating polygon mirror 4. The first reference surface 11a and the second reference surface 12a are provided around the hole 15, and the first reference surface 11b and the second reference surface 12b are provided around the hole 16. No holes are provided in the first reference surfaces 11c and 11d and the second reference surfaces 12c and 12d. In this manner, at least one of the plurality of reference surfaces 11a to 11d is provided around a hole.

[0032] In this state, wire springs 22 (fixing means for fixing the optical scanning device to the image forming apparatus) are attached to spring hooks 20d, 20e, 21b, and 21c of stays 20 and 21, respectively, and each wire spring 22 presses first pressing portions 13a to 13d of optical box 9. This fixes optical scanning device 101 to main body frame 17. With this configuration, laser beam L is irradiated onto photosensitive drum 103 arranged below optical scanning device 101 to scan the laser beam L for imaging.

[0033] Next, a method for attaching the optical scanning device 101 to the second image forming device 111 will be described. The second image forming device 111 differs from the first image forming device 110 mainly in the configuration of the main body frame, the attachment posture of the optical scanning device 101, and the arrangement of the photosensitive drum 103. For the sake of explanation, in the following drawings, of the components of the second image forming device 111, parts other than the optical scanning device 101, the main body frame 23 of the second image forming device 111, and the photosensitive drum 103 are omitted.

[0034] 10 is a perspective view of the main body frame 23 of the second image forming apparatus 111. The main body frame 23 of the second image forming apparatus 111 has side plates 24 and 25. A stay 26 to which the optical scanning device 101 is attached is fixed to the side plates 24 and 25. The stay 26 has contact surfaces 26a and 26b, positioning portions 26c and 26d, and spring hook portions 26e to 26h. The stay 26 does not have a through hole 20h through which the laser beam passes, as provided in the stay 20.

[0035] Fig. 11 is a perspective view of the state in which the optical scanning device 101 is attached to the main body frame 23. Fig. 12 is a cross-sectional view of the state in which the optical scanning device 101 is attached to the main body frame 23.

[0036] When the optical scanning device 101 is attached to the second image forming device 111, it is attached in a position rotated 180° around the Y′ axis compared to when it is attached to the first image forming device 110.

[0037] The second reference surfaces 12a to 12d of the optical box 9 are supported by the stay 26 by abutting against the corresponding abutment surfaces 26a and 26b. The optical scanning device 101 is positioned in the second image forming device 111 by fitting the positioning hole 15 of the optical box 9 into the positioning portion 26c of the stay 26 and inserting the positioning portion 26d of the stay 26 into the anti-rotation hole 16 of the optical box 9. In this state, the wire springs 22 are attached to the spring hooks 26e to 26h of the stay 26, respectively, and the wire springs 22 press against the second pressing portions 14a to 14d of the optical box 9, thereby fixing the optical scanning device 101 to the second image forming device 111. With this configuration, the laser beam L is used to form an image on the photosensitive drum 103 arranged above the optical scanning device 101.

[0038] As described above, the optical scanning device 101 can be attached to different image forming apparatuses by selectively using the first reference surfaces 11a to 11d and the second reference surfaces 12a to 12d. At the same time, the optical scanning device 101 can be attached from the upper side of the stay, regardless of the orientation of the optical scanning device 101 when attached to the image forming apparatus. Therefore, the orientation of the optical scanning device 101 when attached does not affect the attachment position, visibility of the fixing points, or accessibility to the fixing points. This improves the ease of assembly of the optical scanning device 101 in the image forming apparatus. Furthermore, since there is no need to turn the main body frame upside down during assembly, the number of assembly steps can be reduced, leading to cost savings.

[0039] Furthermore, when the optical scanning device 101 is viewed in the Z-axis direction, the first pressing portions 13a to 13d are disposed near the first reference surfaces 11a to 11d, and the second pressing portions 14a to 14d are disposed near the second reference surfaces 12a to 12d. This makes it possible to suppress deformation of the optical box 9, the anamorphic collimator lens 2, and the fθ lens 7 due to the pressing force of the wire spring 22. As a result, the optical scanning device 101 can maintain high optical performance.

[0040] Furthermore, when the optical scanning device 101 is viewed in the Z-axis direction, the laser unit 1, the anamorphic collimator lens 2, the rotating polygon mirror 4, the fθ lens 7, and the folding mirror 8 are arranged within rectangles S1 and S2. This makes it possible to suppress the amplitude of vibration of the optical scanning device 101 caused by vibration from the drive source inside the image forming apparatus. As a result, the optical scanning device 101 can maintain high optical performance.

[0041] As described above, according to this embodiment, it is possible to provide an optical scanning device that can be mounted on different image forming apparatuses, is inexpensive, and allows for improved assembly.

[0042] The dimensions, materials, shapes, relative positions, etc. of the components described in the examples may be changed as appropriate depending on the configuration and various conditions of the device to which the invention is applied, and therefore, unless otherwise specified, the scope of the invention is not intended to be limited to those. Specifically, although the first and second reference planes are provided in four locations each in this example, this is not limited thereto, and similar effects can be obtained even if each is provided in two, three, or five or more locations. Furthermore, although the first vector V1 and the second vector V2 are directed in opposite directions along the Z axis in this example, this is not limited thereto, and similar effects can be obtained as long as their Z-axis components are directed in opposite directions.

[0043] Example 2 Fig. 13 is a perspective view of the scanner unit and the main body frame of the first image forming apparatus of Example 2. Fig. 14 is a perspective view of the scanner unit and the main body frame of the second image forming apparatus of Example 2. The same functions and shapes as those of Example 1 are indicated by the same reference numerals, and the description thereof will be omitted.

[0044] In this embodiment, screws 27 are used to attach the optical scanning device 101 instead of the wire springs 22 used in the first embodiment.

[0045] In the optical box 9, the first pressing portions 13a to 13d are flush with the second reference surfaces 12a to 12d, and the second pressing portions 14a to 14d are flush with the first reference surfaces 11a to 11d. The first reference surfaces 11a to 11d face directly to the first pressing portions 13a to 13d, and the second reference surfaces 12a to 12d face directly to the second pressing portions 14a to 14d. This configuration also provides the same effects as the first embodiment. Additionally, because the reference surfaces and the pressing portions face directly to each other, deformation of the optical box 9 due to the pressing force of the screws 27 can be more effectively suppressed. As a result, deterioration in the optical performance of the optical scanning device 101 can be prevented.

[0046] Also, by using screws 27, which are general-purpose parts, instead of wire springs 22 that are individually made to fit the shape of the pressing portion, costs can be reduced. Furthermore, since screws 27 are easier to attach to the main body frame than wire springs 22, costs can be reduced by reducing the number of assembly steps. Furthermore, by providing a pressing force stronger than that of wire springs 22, the risk of optical scanning device 101 falling off the positioning portion due to excessive impact during transportation of the image forming apparatus can be more effectively reduced. [Explanation of symbols]

[0047] 9 Optical box 11a~11d First reference plane 12a~12d Second reference plane 13a to 13d First pressing portion 14a to 14d Second pressing portion 20, 21 First image forming apparatus 26 Second image forming apparatus

Claims

1. A light source and a deflection unit including a rotary polygon mirror that deflects the laser beam emitted by the light source; a lens for focusing the laser beam scanned by the deflection unit; an optical box that houses the deflection unit and the lens; An optical scanning device mounted in an image forming apparatus for forming a toner image on a recording material, An optical scanning device characterized in that the optical box has a plurality of reference surfaces which are mounting surfaces to the image forming device, and a plurality of flat surfaces which are arranged directly behind each of the plurality of reference surfaces in the direction of the rotation axis of the rotating polygon mirror and which are each parallel to each of the plurality of reference surfaces.

2. 2. An optical scanning device as described in claim 1, wherein, when viewed in the direction of the rotation axis, the rotation axis of the rotating polygon mirror and the lens are arranged within the area formed by connecting the plurality of reference surfaces and the area formed by connecting the plurality of planes.

3. 2. The optical scanning device according to claim 1, wherein pressing portions that are pressed by fixing means for fixing the optical scanning device to an image forming apparatus are provided in the vicinity of the plurality of reference surfaces of the optical box.

4. The optical scanning device described in claim 3, characterized in that the optical box has a hole into which a positioning portion for determining the position of the optical scanning device in a plane direction perpendicular to the rotation axis direction is inserted, and at least one of the multiple reference surfaces is provided around the hole.

5. A photoreceptor; an optical scanning device that scans the photosensitive member with a laser beam according to image information; An image forming apparatus for forming a toner image on a recording material, 5. An image forming apparatus, wherein the optical scanning device is the optical scanning device according to claim 1.

Images