Scanning optical device and image forming apparatus

Abstract

To provide a scanning optical device that performs positioning of a lens accurately at low cost, and has high accuracy and reliability.SOLUTION: A fixing member 9 has: a first portion 91 that has a part to be engaged 9c engaged with an engaging part 8d in a state in which a fθ lens 7 is fixed to an optical box 8, and extends toward a direction of a bottom face 8e; a second portion 92 that has a surface to be positioned 9a in contact with a positioning surface 8b and a pressing surface 9b in contact with a surface to be pressed 7b, and extends toward the bottom face 8e; and a third portion 93 that has a pressing surface 9d in contact with a surface to be pressed 7d, and extends toward the bottom face 8e.SELECTED DRAWING: Figure 3

Description

[Technical field]

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

[0002] In a scanning optical device used in an image forming device such as a conventional laser printer, a laser beam emitted from a light source is deflected and scanned by a reflecting surface of a deflector in response to an image signal. The deflected and scanned laser beam is focused on a photosensitive drum by a scanning lens such as an fθ lens to form an electrostatic latent image. The electrostatic latent image on the photosensitive drum is then visualized as a toner image by a process cartridge such as a developing device, which is transferred to a recording material such as recording paper and sent to a fixing device, where the toner on the recording material is heated and fixed to perform printing. For example, Patent Document 1 proposes a configuration of such a scanning optical device. The scanning lens used in the scanning optical device is pressed in the optical axis direction of the scanning lens by a separate metal leaf spring and is fixed to an optical box, which is a housing. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2005-181501 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the conventional configuration in which the scanning lens is fixed by a separate metal leaf spring, a process of bending the leaf spring in multiple directions is required, resulting in a complex shape, which increases the number of processing steps and increases the cost. In addition, if each part is deformed due to thermal expansion caused by temperature change, the distance between the optical box and the scanning lens varies. In addition, the pressing force of the leaf spring may change at the contact portion between the resin lens and the metal leaf spring. Specifically, if the pressing force becomes weak, the position of the scanning lens may shift when an impact is applied. On the other hand, if the pressing force becomes strong, the scanning lens may be deformed, resulting in a deterioration of optical performance.

[0005] The present invention has been made under these circumstances, and an object of the present invention is to provide a scanning optical device which can position lenses at low cost with high accuracy, and which is highly accurate and reliable. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems, the present invention has the following configuration.

[0007] (1) A scanning optical device comprising: a light source; a deflector that deflects and scans a light beam emitted from the light source; an optical member that guides the light beam scanned by the deflector to a scanned body; a housing having a bottom surface to which the deflector and the optical member are attached and a side wall that stands upright from the bottom surface and to which the light source is attached; and a fixing member that positions the optical member with respect to the housing and fixes a longitudinal end of the optical member, wherein the housing, the optical member, and the fixing member are made of resin, and the optical member has an incident surface on which the light beam deflected and scanned by the deflector is incident, an exit surface from which the incident light beam exits, and the optical member abuts against the bottom surface while being fixed by the fixing member, and has a first intersecting surface that intersects the incident surface and the exit surface, and a second intersecting surface that intersects the incident surface and the exit surface. and a second intersecting surface opposite to the first intersecting surface, the housing having a first abutment surface abutting the incident surface at an end in the longitudinal direction when the optical member is fixed by the fixing member, a side surface on the outer side of the housing at the side wall, and a second abutment surface on the inner side of the housing at the side wall, the side surface having a protrusion that protrudes outward from the housing, the fixing member having an engaged portion that engages with the protrusion when the optical member is fixed to the housing, the fixing member having a first portion extending toward the bottom surface, a first surface abutting the second abutting surface, and a second surface abutting the exit surface, the second portion extending toward the bottom surface, and a third surface abutting the second intersecting surface and extending toward the bottom surface.

[0008] (2) A scanning optical device comprising: a light source; a deflector that deflects and scans a light beam emitted from the light source; an optical member that guides the light beam scanned by the deflector to a scanned body; a housing having a bottom surface to which the deflector and the optical member are attached and a side wall that stands upright from the bottom surface and to which the light source is attached; a cover member that closes an opening formed by the side wall; and a fixing member that positions the optical member with respect to the housing and fixes a longitudinal end of the optical member, wherein the housing, the optical member, and the fixing member are made of resin, and the optical member has an incident surface on which the light beam deflected and scanned by the deflector is incident, an exit surface from which the incident light beam is emitted, and a first intersection point that intersects with the incident surface and the exit surface, the optical member being in contact with the bottom surface while being fixed by the fixing member, a first abutment surface that abuts on the incident surface at an end in the longitudinal direction when the optical element is fixed by the fixing member, and a second abutment surface on the inside of the housing at the side wall, the cover member having an inner surface that faces the inside when the opening is closed, the fixing member having a first surface that abuts on the second abutment surface and a second surface that abuts on the exit surface when the optical element is fixed to the housing, the fixing member having a first portion extending toward the bottom surface, a third surface that abuts on the second intersecting surface, a second portion extending toward the bottom surface, and a fourth surface that abuts on the inner surface, the third portion connecting the first portion and the second portion.

[0009] (3) An image forming apparatus comprising: a scanning optical device according to (1) or (2); and an image forming means for forming an image on a recording material based on a light beam emitted from the scanning optical device. Effect of the Invention

[0010] According to the present invention, it is possible to provide a scanning optical device that can perform lens positioning at low cost and with high accuracy, and that is highly accurate and reliable. [Brief description of the drawings]

[0011] [Figure 1] 1 is a cross-sectional view of an image forming apparatus including a scanning optical device according to the first and second embodiments. [Diagram 2] FIG. 1 is a perspective view of a scanning optical device according to a first embodiment of the present invention; [Diagram 3] FIG. 1 is a perspective view showing a fixing member according to a first embodiment; [Figure 4] FIG. 3 is an XZ cross-sectional view of the scanning optical device shown in FIG. 2 according to the first embodiment; [Diagram 5] FIG. 1 is a perspective view of a scanning optical device showing a modified example of the first embodiment; [Figure 6] FIG. 1 is a perspective view of a scanning optical device showing a modified example of the first embodiment; [Figure 7] FIG. 11 is an XZ sectional view of a scanning optical device according to a second embodiment of the present invention; [Figure 8] FIG. 11 is a cross-sectional view of a scanning optical device showing a modification of the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, the mode for carrying out the present invention will be described in detail by way of example with reference to the drawings. However, the dimensions, materials, shapes, relative positions, etc. of the components described in the embodiments are appropriately changed depending on the configuration of the device to which the invention is applied and various conditions, and therefore, unless otherwise specified, the scope of the invention is not limited to these. In addition, with regard to the configuration of the later embodiments, the same reference numerals as in the previous embodiment are used for the same configuration as in the previous embodiment, and the explanation in the previous embodiment is to be used. EXAMPLES

[0013] [Image forming equipment] 1 is a cross-sectional view of an image forming apparatus 110 including a scanning optical device 101 of the first embodiment. The image forming apparatus 110 includes the scanning optical device 101, which is an exposure means, and an image forming section, which is an image forming means. The scanning optical device 101 scans a photosensitive drum 103, which is an object to be scanned, with a light beam (e.g., laser light), and the image forming section (e.g., a process cartridge, which will be described later) forms an image on a recording material P such as recording paper based on the image formed on the photosensitive drum 103. Here, a printer will be exemplified as the image forming apparatus 110 for explanation.

[0014] In the image forming apparatus 110 (printer), a laser beam based on the obtained image information is emitted by a scanning optical device 101, and the laser beam is irradiated onto a photosensitive drum 103 built in a process cartridge 102. As a result, a latent image is formed on the photosensitive drum 103, and the latent image is visualized as a toner image by the process cartridge 102 using toner as a developer. The process cartridge 102 integrally includes the photosensitive drum 103, and charging means (e.g., a charging roller) and developing means (e.g., a developing roller) as process means acting on the photosensitive drum 103.

[0015] Meanwhile, the recording materials P stacked on a stacking plate 104 for stacking the recording materials P are fed while being separated one by one by a feeding roller 105, and then transported further downstream by an intermediate roller 106. The toner image formed on the photosensitive drum 103 is transferred onto the transported recording material P by a transfer roller 107. The recording material P on which the unfixed toner image has been formed is transported further downstream, where the toner image is fixed to the recording material P by a fixing device 108 having a heater therein. The recording material P is then discharged to the outside of the apparatus main body 110A by a discharge roller 109. In FIG. 1, the path along which the recording material P is transported is shown by a dashed line.

[0016] The image forming apparatus 110 includes a control unit 150. The control unit 150 includes a central processing unit (CPU) 151, a read only memory (ROM) 152, a random access memory (RAM) 153, and a timer 154. The CPU 151 includes an analog-digital conversion port. The control unit 150 executes a program stored in advance in the ROM 152 while using the RAM 153 as a temporary work area by the CPU 151, and controls the image forming apparatus 110. When controlling the image forming apparatus 110, the control unit 150 controls various timings while using the timer 154. The control unit 150 may include an application specific integrated circuit (ASIC) or a micro processing unit (MPU). The number of the CPU 151, the timer 154, the ROM 152, and the RAM 153 is not limited to one, and may be multiple. In addition, other storage media such as a hard disk and an optical disk may be used as the storage medium. The image forming apparatus to which the present invention can be applied is not limited to the image forming apparatus 110 of FIG. 1.

[0017] In the first embodiment, the charging means and the developing means as process means acting on the photosensitive drum 103 are integral with the photosensitive drum 103 in the process cartridge 102. However, each process means may be configured separately from the photosensitive drum 103.

[0018] [Scanning optical device] 2 is a perspective view of the scanning optical device 101. In the following description, the direction in which the laser light scans the photosensitive drum 103, in other words, the direction of the rotation axis of the photosensitive drum 103, is referred to as the main scanning direction. The direction perpendicular to the main scanning direction, in other words, the rotation direction of the photosensitive drum 103, is referred to as the sub-scanning direction. Furthermore, the main scanning direction is referred to as the Y direction, and in a virtual plane perpendicular to the Y direction, the direction of the rotation axis of the rotating polygon mirror 4 is referred to as the Z direction, and the direction perpendicular to the Y direction and the Z direction is referred to as the X direction. The X direction is also the direction of the optical axis of an fθ lens 7, which will be described later.

[0019] The scanning optical device 101 includes a laser unit 1 as a light source, a deflection device 5 (deflector), an optical box 8 as a resin housing that houses an fθ lens 7 as a resin optical member, and a cover member 12 (see FIG. 1) that covers the optical box 8. Inside the optical box 8, the laser unit 1, a composite anamorphic collimator lens 2, an aperture stop 3, a deflection device 5 having a rotating polygon mirror 4, a sensor 6, and an fθ lens 7 (scanning lens) are arranged. More specifically, the optical box 8 has a bottom surface 8e and an outer wall 8f that is a side wall erected from the bottom surface 8e. The deflection device 5, the fθ lens 7, the composite anamorphic collimator lens 2, and the like are arranged on the bottom surface 8e of the optical box 8. The laser unit 1 is arranged on the outer wall 8f of the optical box 8. The optical box 8 has an opening formed by the outer wall 8f, and the deflection device 5 and the like are arranged on the bottom surface 8e through the opening. The opening of the optical box 8 is closed by the cover member 12.

[0020] The laser unit 1 (semiconductor laser unit) is a unit that emits a laser beam. The composite anamorphic collimator lens 2 is a lens that is formed by integrally molding an anamorphic collimator lens that is an integrated collimator lens and a cylindrical lens, and a signal detection lens (hereinafter referred to as a BD lens) 2k. The deflection device 5 has a rotating polygon mirror 4 that deflects and scans the laser beam L, indicated by the two-dot chain line, emitted by the laser unit 1, and is a device that rotates and drives the rotating polygon mirror 4. The rotating polygon mirror 4 has multiple reflecting surfaces parallel to the Z direction, for example, four reflecting surfaces in FIG. 2, and reflects the laser light at each reflecting surface.

[0021] The laser beam L emitted from the laser unit 1 is converted by the composite anamorphic collimator lens 2 into a substantially parallel beam or a 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 the beam width is restricted, and is imaged in the shape of 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 the BD lens 2k of the composite anamorphic collimator lens 2. The laser beam L that has passed through the BD lens 2k enters a sensor 6.

[0022] At this time, the sensor 6 detects the laser beam L, and the sensor 6 outputs a signal (also called a BD signal) to the control unit 150. The timing at which the BD signal is output is set as the timing for synchronously detecting the writing position in the main scanning direction. Next, the laser beam L enters the fθ lens 7. The fθ lens 7 is a lens that focuses the beam (laser beam L) scanned by the deflection device 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 keep the scanning speed of the spot constant. In order to obtain such characteristics of the fθ lens 7, the fθ lens 7 is formed of an aspheric lens. The laser beam L that has passed through the fθ lens 7 is emitted from the exit of the optical box 8 and is scanned to form an image on the photosensitive drum 103.

[0023] The laser beam L is deflected and scanned by the rotation of the rotating polygon mirror 4, main scanning is performed on the photosensitive drum 103 by the laser beam, and sub-scanning is performed by the photosensitive drum 103 being rotated about its cylindrical axis. In this way, an electrostatic latent image is formed on the surface of the photosensitive drum 103. The fixing member 9 positions the fθ lens 7 with respect to the optical box 8, and fixes the end of the fθ lens 7 in the longitudinal direction (which is also the Y direction). The fixing member 9 will be described later. The optical box 8, the fθ lens 7, and the fixing member 9 are made of resin.

[0024] [Fixed part] The configuration of the fixing member 9 will be described in detail with reference to Fig. 3. Fig. 3 is a diagram showing the configuration of the fixing member 9 in Example 1. Fig. 3 shows the X, Y and Z directions in accordance with the state in which the fixing member 9 fixes both ends in the longitudinal direction of the fθ lens 7 in Fig. 2. Fig. 3(a) is a view looking down from diagonally above, and Fig. 3(b) is a view looking up from diagonally below.

[0025] The fixing member 9 has a first portion 91, a second portion 92, a third portion 93, a fourth portion 94, and a fifth portion 95. The first portion 91 is a portion that extends in a direction toward the bottom surface 8e of the optical box 8 when the fixing member 9 is attached to the optical box 8. The first portion 91 has an engaged portion 9c that engages with the optical box 8.

[0026] The second portion 92 extends in a direction toward the bottom surface 8e of the optical box 8 when the fixing member 9 is attached to the optical box 8, and extends in a direction substantially parallel to the first portion 91. The second portion 92 has a positioned surface 9a as a first surface and a pressing surface 9b as a second surface. The positioned surface 9a faces the first portion 91 and contacts the optical box 8. The pressing surface 9b is the surface of the second portion 92 opposite to the positioned surface 9a and presses the fθ lens 7. When the fixing member 9 is attached to the optical box 8, the positioned surface 9a and the pressing surface 9b are parallel to the YZ plane and perpendicular to the X direction.

[0027] The third portion 93 is a portion that extends in a direction toward the bottom surface 8e of the optical box 8 when the fixing member 9 is attached to the optical box 8. The length of the third portion 93 in the Z direction is shorter than those of the first portion 91 and the second portion 92. The second portion 92 has a pressing surface 9d, which is a third surface that presses the fθ lens 7 in the negative direction of the Z axis. When the fixing member 9 is attached to the optical box 8, the first portion 91, the second portion 92, and the third portion 93 are provided on the fixing member 9 in the order of the first portion 91, the second portion 92, and the third portion 93 from the outer wall 8f of the optical box 8 toward the inside of the optical box 8.

[0028] The fourth portion 94 is a portion that connects the first portion 91 and the second portion 92. A continuous rectangular hole 98 is provided in a part of the fourth portion 94 and a part of the first portion 91, and a part of the edge that forms the hole 98 serves as an engaged portion 9c. The fifth portion 95 is a portion that continues from the fourth portion 94 and connects the second portion 92 and the third portion 93. The fixing member 9 is made of resin and formed by injection molding.

[0029] [fθ lens] Fig. 4 shows an XZ cross-sectional view at the position of the fixing member 9 fixing the fθ lens 7 in the scanning optical device 101 shown in Fig. 2. In the first embodiment, the fθ lens 7, the optical box 8 and the fixing member 9 are all made of resin and have the same thermal expansion coefficient.

[0030] The fθ lens 7 has a positioned surface 7a that contacts the optical box 8 and a pressed surface 7b that contacts the fixed member 9. The fθ lens 7 has a shape that is long in the main scanning direction. The positioned surface 7a is an entrance surface on which the laser light deflected by the rotating polygon mirror 4 is incident. The pressed surface 7b is an exit surface from which the laser light incident on the fθ lens 7 is emitted. The fθ lens 7 has a positioned surface 7c that contacts the bottom surface 8e of the optical box 8 and a pressed surface 7d that contacts the fixed member 9. The positioned surface 7c is a first intersecting surface that intersects the positioned surface 7a and the pressed surface 7b, specifically, is substantially perpendicular to them. The pressed surface 7d is a second intersecting surface that intersects the positioned surface 7a and the pressed surface 7b. The pressed surface 7d is a surface on the opposite side to the positioned surface 7c, in other words, it faces the cover member 12.

[0031] Thus, the fθ lens 7 has a positioned surface 7a which is an entrance surface onto which the light beam deflected and scanned by the deflection device 5 enters, and a pressed surface 7b which is an exit surface from which the incident light beam exits. The fθ lens 7 further has a positioned surface 7c which is a first intersecting surface that intersects with the positioned surface 7a and the pressed surface 7b and comes into contact with the bottom surface 8e when the fθ lens 7 is fixed by the fixing member 9. The fθ lens 7 further has a pressed surface 7d which is a second intersecting surface that intersects with the positioned surface 7a and the pressed surface 7b and is on the opposite side to the positioned surface 7c.

[0032] [Optical box] More specifically, the outer wall 8f of the optical box 8 has a side surface 8g on the outside of the optical box 8 and a positioning surface 8b which is a second contact surface on the inside of the optical box 8. The optical box 8 has a positioning surface 8a which contacts the fθ lens 7 and a positioning surface 8b which contacts the fixed member 9. The positioning surface 8a is a first contact surface which contacts the positioned surface 7a (incident surface) when the fθ lens 7 is arranged in the optical box 8. The positioning surface 8b is a second contact surface which faces the pressed surface 7b (exit surface) with a gap of a distance S1 to be described later formed between the positioning surface 8b and the pressed surface 7b (exit surface) when the fθ lens 7 is not fixed by the fixed member 9. The positioning surface 8b contacts the positioned surface 9a of the fixed member 9 when the fθ lens 7 is fixed by the fixed member 9. The optical box 8 has a positioning surface 8c that comes into contact with the fθ lens 7, and an engagement portion 8d that protrudes in the X direction from the outer circumferential surface (outer wall 8f) of the optical box 8 and engages with the fixing member 9.

[0033] In this manner, the optical box 8 has a positioning surface 8a which is a first contact surface that contacts the positioned surface 7a at an end in the longitudinal direction with the fθ lens 7 fixed by the fixing member 9. The optical box 8 has a side surface 8g on the outer side of the outer wall 8f of the optical box 8, and a positioning surface 8b which is a second contact portion on the inner side of the outer wall 8f of the optical box 8. In addition, the side surface 8g has an engagement portion 8d which is a protrusion that protrudes outward from the optical box 8.

[0034] [Fixing method] A method for fixing the fθ lens 7 in the X direction (which is also the optical axis direction) will be described. After the fθ lens 7 is placed in the optical box 8, the fixing member 9 is attached to the optical box 8 in the assembly direction (-Z direction). As a result, the positioned surface 9a of the fixing member 9 comes into contact with the positioning surface 8b of the optical box 8, and the pressing surface 9b of the fixing member 9 presses the pressed surface 7b of the fθ lens 7. As a result, the fθ lens 7 is positioned with the positioned surface 7a abutting against the positioning surface 8a of the optical box 8. This completes the positioning in the X direction.

[0035] Next, a method for fixing the fθ lens 7 in the Z direction will be described. The fixing member 9 has an engaged portion 9c that engages with the optical box 8 and a pressing surface 9d that presses the fθ lens 7. The engaging portion 8d and the engaged portion 9c have a so-called snap-fit ​​structure.

[0036] After the fθ lens 7 is installed in the optical box 8, the fixing member 9 is assembled to the optical box 8 in the assembly direction (-Z direction), so that the pressing surface 9d of the fixing member 9 presses the pressed surface 7d of the fθ lens 7. As a result, the fθ lens 7 is positioned by having the positioned surface 7c abut against the positioning surface 8c of the optical box 8. The fixing member 9 is prevented from coming off in the +Z direction by the engagement of the engaged portion 9c of the fixing member 9 with the engagement portion 8d of the optical box 8. The fθ lens 7 is positioned in the Y direction by an engaged portion (not shown) of the fθ lens 7 engaging with an engaging portion (not shown) of the optical box 8.

[0037] The temperature inside the scanning optical device 101 changes due to temperature changes in the space in which the image forming device 110 is installed, temperature rise due to long-term printing, etc. When the temperature inside the scanning optical device 101 changes, the distance S1 between the pressed surface 7b of the fθ lens 7 and the positioning surface 8b of the optical box 8 in the X direction changes according to the thermal expansion coefficients of the fθ lens 7 and the optical box 8. Similarly, the distance S2 between the pressed surface 7d of the fθ lens 7 and the engagement part 8d of the optical box 8 in the Z direction changes. As described above, the fθ lens 7, the optical box 8, and the fixed member 9 are each made of resin and have similar thermal expansion coefficients. Therefore, the difference between the change in the distance S1 in the X direction and the change in the distance between the positioned surface 9a and the pressing surface 9b of the fixed member 9 is small. Similarly, the difference between the change in the distance S2 in the Z direction and the change in the distance between the engaged part 9c and the pressing surface 9d of the fixed member 9 is small. Therefore, the change in the pressing force of the fixing member 9 on the fθ lens 7 can be reduced in both the X direction and the Z direction, and the fθ lens 7 can be stably biased. This reduces the positional deviation and deformation of the fθ lens 7, and prevents the deterioration of the optical performance of the fθ lens 7. As a result, the scanning optical device 101 can form a stable latent image.

[0038] The fixing member 9 positions and fixes the fθ lens 7 in the Z direction as well as the X direction, thereby simplifying the assembly of the fθ lens 7, thereby reducing the number of assembly steps and improving productivity. In addition, the shape of the fixing member 9 is small and simple, which reduces the cost of parts and molds.

[0039] Furthermore, the engagement portion 8d of the optical box 8 is formed on the outer peripheral surface of the optical box 8 surrounding the fθ lens 7, and there is no need to provide a cut-off hole for the cavity core (cavity and core) inside the optical box 8. This makes it possible to prevent foreign matter from entering the optical box 8 from the outside, and there is no need to incur additional costs for a sealing member or the like for blocking the air passage to the inside of the optical box 8.

[0040] As described above, according to the first embodiment, in assembling the fθ lens, it is possible to reduce positional deviation and deformation with an inexpensive configuration and to realize a highly accurate and reliable scanning optical device.

[0041] [Fixing other optical elements] In addition, the configuration in which the fixing member 9 is applied to the fθ lens 7, which is a scanning lens, has been described, but the same effect can be obtained when the fixing member 9 is applied to another optical element such as the compound anamorphic collimator lens 2 as shown in FIG. 2. That is, in FIG. 4, the fθ lens 7 may be replaced with another optical element. The other optical element may have a surface in contact with the bottom surface 8e (positioning surface 8c) of the optical box 8 and a surface in contact with the positioning surface 8a erected in the Z direction from the bottom surface 8e of the optical box 8. The other optical element may have a surface (corresponding to the pressed surface 7b) opposite to the surface in contact with the positioning surface 8a in the X direction and a surface (corresponding to the pressed surface 7d) opposite to the surface in contact with the bottom surface 8e. The optical box 8 may have an engagement portion 8d that engages with the engaged portion 9c of the fixing member 9 at a position where the other optical element is set. As shown in FIG. 2, the compound anamorphic collimator lens 2 has one end in the longitudinal direction (X direction) fixed by the fixing member 9. In this manner, by fixing at least one end of the optical element in the longitudinal direction by the fixing member 9, it is possible to reduce positional deviation and deformation caused by temperature changes.

[0042] [Modification of Example 1] FIG. 5(a) is a perspective view of a scanning optical device 101 showing a first modified example of the first embodiment. FIG. 5(b) is a view of the fixed member 9A looking down from diagonally above, and FIG. 5(c) is a view of the fixed member 9A looking up from diagonally below. FIG. 6(a) is a perspective view of a scanning optical device 101 showing a second modified example of the first embodiment. FIG. 6(b) is a view of the fixed member 9B looking down from diagonally above, and FIG. 6(c) is a view of the fixed member 9B looking up from diagonally below. The same functions and shapes as those in the first embodiment are indicated by the same reference numerals, and the description will be omitted. These are modified examples of the engagement portion 8d of the optical box 8 described in the first embodiment.

[0043] (First Modification) The fixed member 9A in Fig. 5 has a first portion 91, a second portion 92, a third portion 93, a fourth portion 94, and a fifth portion 95, which are similar to the fixed member 9 in Fig. 3. Similarly, the first portion 91 has an engaged portion 9c, the second portion 92 has a positioned surface 9a and a pressing surface 9b, and the third portion 93 has a pressing surface 9d.

[0044] The fixing member 9A has a sixth portion 96 and a seventh portion 97. The sixth portion 96 is a portion that extends in a direction toward the bottom surface 8e of the optical box 8 when the fixing member 9A is attached to the optical box 8. The sixth portion 96 has an engaged portion 9e that engages with the optical box 8. The seventh portion 97 is a portion that connects the third portion 93 and the sixth portion 96. A continuous rectangular hole 99 is provided in a part of the seventh portion 97 and a part of the sixth portion 96, and a part of the hole 99 serves as the engaged portion 9e. The fixing member 9A is also made of resin formed by injection molding.

[0045] In FIG. 5(a), a plurality of engaging portions 8d of the optical box 8 are provided in the X direction in which the fixing member 9A presses the fθ lens 7. That is, the fixing member 9A has a second engaged portion 9e on the opposite side of the engaged portion 9c with respect to the pressing surface 9b in the X direction. The optical box 8 is provided with an engaging portion (not shown) similar to the engaging portion 8d, which engages with the engaged portion 9e of the fixing member 9A. As a result, the fθ lens 7 is sandwiched between the engaged portion 9c and the engaged portion 9e in the X direction. As shown in FIG. 5, the fixing member 9A having two engaged portions is attached so as to sandwich the short side direction perpendicular to the long side direction of the optical element (for example, the fθ lens 7). Even in this case, the same effect as in the above-mentioned embodiment 1 can be obtained.

[0046] In this manner, in the first modified example, when the engaging portion 8d is the first protruding portion and the engaged portion 9c is the first engaged portion, the optical box 8 has a side surface 8g' having an engaging portion 8d' that is a second protruding portion that protrudes on the opposite side to the side surface 8g. The fixing member 9A has an engaged portion 9e that is a second engaged portion that engages with the engaging portion 8d'. The side surface 8g' and the engaging portion 8d' are indicated by dashed lines in FIG. 4. In the first embodiment and the first modified example, the engaging portion 8d is provided on a side wall (side surface 8g) that is parallel to the longitudinal direction, and the first portion 91 is provided parallel to the second portion 92.

[0047] 5(a), one end of the fθ lens 7 in the longitudinal direction may be fixed by the fixing member 9 and the other end may be fixed by the fixing member 9A. In FIG. 5, the second portion 92 of the fixing member 9A is provided on the positive side in the X direction with respect to the third portion 93, but it may be provided on the negative side in the X direction or on both sides of the third portion 93.

[0048] (Second Modification) 6 shows a case where the engagement portion 8d of the optical box 8 is provided so as to protrude in the Y direction perpendicular to the X direction. The fixing member 9 and the fixing member 9A are provided in the order of a first portion 91, a second portion 92, and a third portion 93 from the outer wall 8f of the optical box 8 toward the inside of the optical box 8 in a state where the fixing member 9 and the fixing member 9A are attached to the optical box 8. Furthermore, the first portion 91 and the second portion 92 are provided so that the surface of the first portion 91 in which the hole 98 is provided is parallel to the positioned surface 9a and the pressing surface 9b.

[0049] On the other hand, the fixing member 9B in FIG. 6 has a first portion 91, a second portion 92, a third portion 93, and a fourth portion 94. Similarly, the first portion 91 has an engaged portion 9c, the second portion 92 has a positioned surface 9a and a pressing surface 9b, and the third portion 93 has a pressing surface 9d. However, in the fixing member 9B, the positioned surface 9a and the pressing surface 9b of the second portion 92 are not parallel to the surface on which the hole 98 of the first portion 91 is provided, but are perpendicular to it. In this way, the engaging portion 8d is provided on the side surface 8h, which is a side wall perpendicular to the longitudinal direction, and the first portion 91 is provided so as to be perpendicular to the second portion 92. Even in this case, the same effect as in the above-mentioned embodiment 1 can be obtained. In FIG. 6, the second portion 92 of the fixing member 9B is provided on the positive side of the X direction with respect to the third portion 93, but it may be provided on the negative side of the X direction or on both sides of the third portion 93.

[0050] The fθ lens 7 may be fixed at both ends in the longitudinal direction by fixing members 9B, or, as shown in Fig. 6(a), one end of the fθ lens 7 in the longitudinal direction may be fixed by fixing member 9 and the other end by fixing member 9B. Furthermore, one end may be fixed by fixing member 9A. Which of the fixing members 9, 9A, or 9B is used to fix the fθ lens 7 may be determined depending on the position and shape of the optical box 8 in which the fθ lens 7 is installed.

[0051] As described above, according to the first embodiment, it is possible to provide a scanning optical device that can perform lens positioning at low cost and with high accuracy, and that is highly accurate and reliable. EXAMPLES

[0052] [Fixed part] Fig. 7(a) is a partially enlarged cross-sectional view showing a fixing method of the fθ lens 7 in Example 2. Fig. 7(b) is a view of the fixing member 11 as viewed diagonally from above, and Fig. 7(b) is a view as viewed diagonally from below.

[0053] In the fixing members 9, 9A, and 9B of the first embodiment, the engaged portion 9c of the first portion 91 is engaged with the engaging portion 8d of the optical box 8 in a state in which the fixing members 9, 9A, and 9B are attached to the optical box 8. On the other hand, the fixing member 11 of FIG. 7 has a first portion 191, a second portion 192, and a third portion 193, and does not have the first portion 91 (and the sixth portion 96) having the engaged portion 9c that is a part of the edge portion forming the hole 98 (and the hole 99) of the first embodiment. In the fixing member 11 of the second embodiment, the third portion 193 has an abutment surface 11c that abuts against the cover member 12. The fixing members 9, 9A, and 9B of the first embodiment engage with the optical box 8 to position and support the fθ lens 7, but the fixing member 11 of the second embodiment positions and supports the fθ lens 7 by abutting against the cover member 12.

[0054] The fixing member 11 has a first portion 191. The first portion has a positioned surface 11a, which is a first surface that abuts against the positioning surface 10b, and a pressing surface 11b, which is a second surface that abuts against the positioned surface 7a, when the fθ lens 7 is fixed to the optical box 10, and extends toward the bottom surface (corresponding to the bottom surface 8e). The fixing member 11 has a second portion 192, which extends toward the bottom surface and has a pressing surface 11d, which is a third surface that abuts against the positioning surface 10c, when the fθ lens 7 is fixed to the optical box 10. The fixing member 11 has a third portion 193, which connects the first portion 191 and the second portion 192, and has an abutting surface 11c, which is a fourth surface that abuts against the abutting surface 12b, which is the inner surface of the cover member 12.

[0055] The cover member 12 is a member that closes an opening formed by an outer wall 10f, which is a side wall of the optical box 10. The cover member 12 has an abutment surface 12b that faces inward when the opening is closed. The abutment surface 12b is part of a recess, and the abutment surface 11c abuts against the abutment surface 12b, which is part of the recess. The optical box 10 has an engagement portion 10d that protrudes outward from the side surface 10g, and the cover member 12 has an engaged portion 12c that engages with the engagement portion 10d.

[0056] [Fixing method] The scanning optical device 101 of the second embodiment includes an fθ lens 7, an optical box 10, a fixing member 11, and a cover member 12. A method of fixing the fθ lens 7 in the X direction (optical axis direction) will be described.

[0057] The fθ lens 7 has a positioned surface 7a that contacts the optical box 10 and a pressed surface 7b that contacts the fixed member 11. The optical box 10 has a positioning surface 10a that is a first contact surface that contacts the fθ lens 7 and a positioning surface 10b that is a second contact surface that contacts the fixed member 11. The fixed member 11 has a positioned surface 11a that contacts the optical box 10 and a pressing surface 11b that presses the fθ lens 7. The fixed member 11 is made of resin and formed by injection molding. The details of the method for fixing the fθ lens 7 in the X direction are the same as in Example 1, so a description thereof will be omitted.

[0058] Next, a method of fixing the fθ lens 7 in the Z direction will be described. The fθ lens 7 has a positioning surface 7c that comes into contact with the optical box 10 and a pressing surface 7d that comes into contact with the fixed member 11. The optical box 10 has positioning surfaces 10a and 10c that come into contact with the fθ lens 7, and an engagement portion 10d that protrudes from the outer circumferential surface of the optical box 10 in the X direction and engages with the cover member 12. Thus, in the second embodiment, the engagement portion 10d of the optical box 10 engages with the cover member 12, not with the fixed member 11. The fixed member 11 has an abutment surface 11c that comes into contact with the cover member 12, and a pressing surface 11d that presses the fθ lens 7. The cover member 12 has an engaged portion 12c that comes into contact with the optical box 10 and an abutment surface 12b that comes into contact with the fixed member 11.

[0059] 7, the contact surface 12b of the cover member 12 forms a U-shaped recess with wall surfaces 12b1 and 12b2 parallel to the Z direction, forming the bottom surface of the recess. When the contact surface 11c of the fixing member 11 is in contact with the contact surface 12b of the cover member 12, the movement of the fixing member 11 in the X direction is restricted by the wall surfaces 12b1 and 12b2. Note that similar walls of the recess are formed in the Y direction, and the movement in the Y direction is similarly restricted.

[0060] After the fθ lens 7 is installed in the optical box 10, the fixing member 11 is assembled to the optical box 10 in the assembly direction (-Z direction), so that the pressing surface 11d of the fixing member 11 presses the pressed surface 7d of the fθ lens 7. As a result, the fθ lens 7 is positioned with the positioned surface 7c abutting against the positioning surface 10c of the optical box 10. In addition, the cover member 12 is assembled to the optical box 10 in this state, so that the abutting surface 12b of the cover member 12 abuts against the abutting surface 11c of the fixing member 11, preventing the fixing member 11 from coming off in the +Z direction. At the same time, the engaged portion 12c of the cover member 12 engages with the engaging portion 10d of the optical box 10, so that the cover member 12 is fixed in the Z direction. The fθ lens 7 is positioned in the arrow Y direction in the same configuration as in the first embodiment.

[0061] In the above-described scanning optical device 101, similarly to the first embodiment, when the temperature of the scanning optical device 101 changes, the change in the pressing force of the fixing member 11 on the fθ lens 7 can be reduced, and a stable bias can be applied. This reduces the positional deviation and deformation of the fθ lens 7, and prevents the deterioration of the optical performance of the fθ lens 7. As a result, the scanning optical device 101 can form a stable latent image.

[0062] Also, since the cover member 12 engages with the optical box 10 by the engaged portion 12c near the contact surface 12b with the fixed member 11, it has a function of preventing the fixed member 11 from coming off even when it is subjected to a strong impact or vibration. In addition, since the contact surface 12b of the cover member 12 with the fixed member 11 is provided with a step shape (the above-mentioned recess) in the Z direction and is contained within the thickness of the cover member 12, the entire scanning optical device 101 can be made thinner and more compact.

[0063] As described above, according to the second embodiment, it is possible to provide a scanning optical device that can perform lens positioning at low cost and with high accuracy, and that is highly accurate and reliable.

[0064] [Modification of Example 2] FIG. 8 is a partially enlarged cross-sectional view showing a fixing method of the fθ lens 7 showing a modified example of the second embodiment. The same functions and shapes as those of the second embodiment are indicated by the same reference numerals, and the description is omitted. In this modified example, instead of engaging the cover member 12 with the optical box 10 by snap-fitting as described in the second embodiment, a screw 13 is used. The cover member 12 is provided with a through hole 12d through which the screw 13 passes, near the abutment surface 12b. The optical box 10 is provided with a hole portion 10e through which the screw 13 is inserted, near the positioning surface 10a. Thus, the optical box 10 of the modified example has the hole portion 10e near the positioning surface 10a, which is the first abutment surface. The cover member 12 has a through hole 12d at a position corresponding to the hole portion 10e in a state where the opening is closed. The optical box 10 and the cover member 12 are fixed by inserting the screw into the through hole 12d and the hole portion 10e.

[0065] 8, even when the cover member 12 is fastened to the optical box 10 by the screws 13 near the contact surface 12b with the fixing member 11, the same effect as in the above-mentioned Example 2 can be obtained. Also, the fixing members 9, 9A, and 9B of Example 1 and the fixing member 11 of Example 2 may be used together.

[0066] As described above, even with the modified example, it is possible to perform lens positioning at low cost with high accuracy, and to provide a scanning optical device with high accuracy and reliability.

[0067] The disclosure of this embodiment includes the following configuration. (Configuration 1) A light source; a deflector for deflecting and scanning the light beam emitted from the light source; an optical member for guiding the light beam scanned by the deflector to a scanned object; a housing having a bottom surface to which the deflector and the optical member are attached, and a side wall extending from the bottom surface and to which the light source is attached; a fixing member that positions the optical member with respect to the housing and fixes an end portion of the optical member in a longitudinal direction; A scanning optical device comprising: the housing, the optical member, and the fixing member are made of resin, the optical member has an incident surface on which the light beam deflected and scanned by the deflector is incident, an exit surface from which the incident light beam exits, a first intersecting surface that abuts against the bottom surface in a state in which the optical member is fixed by the fixing member and that intersects with the incident surface and the exit surface, and a second intersecting surface that intersects with the incident surface and the exit surface and is opposite to the first intersecting surface, the housing has a first abutment surface that abuts on the incident surface at an end in the longitudinal direction in a state in which the optical member is fixed by the fixing member, a side surface on an outer side of the housing at the side wall, and a second abutment surface on an inner side of the housing at the side wall, the side surface has a protruding portion protruding outward from the housing, The fixing member has an engaged portion that engages with the protrusion when the optical member is fixed to the housing, a first portion extending toward the bottom surface, a first surface abutting the second abutment surface, a second surface abutting the exit surface, a second portion extending toward the bottom surface, and a third surface abutting the second intersecting surface, the third portion extending toward the bottom surface. (Configuration 2) When the protruding portion is a first protruding portion and the engaged portion is a first engaged portion, the housing has a second protruding portion protruding on an opposite side to the first contact surface, The above-mentioned scanning optical device, wherein the fixed member has a second engaged portion that engages with the second protruding portion. (Configuration 3) The protrusion is provided on a side wall parallel to the longitudinal direction, The above-mentioned scanning optical device, wherein the first portion is provided parallel to the second portion. (Configuration 4) The protrusion is provided on a side wall perpendicular to the longitudinal direction, The above-mentioned scanning optical device, wherein the first portion is arranged so as to be perpendicular to the second portion. (Configuration 5) A light source; a deflector for deflecting and scanning the light beam emitted from the light source; an optical member for guiding the light beam scanned by the deflector to a scanned object; a housing having a bottom surface to which the deflector and the optical member are attached, and a side wall extending from the bottom surface and to which the light source is attached; a cover member that closes an opening formed by the side wall; a fixing member that positions the optical member with respect to the housing and fixes an end portion of the optical member in a longitudinal direction; A scanning optical device comprising: the housing, the optical member, and the fixing member are made of resin, the optical member has an incident surface on which the light beam deflected and scanned by the deflector is incident, an exit surface from which the incident light beam exits, a first intersecting surface that abuts against the bottom surface in a state in which the optical member is fixed by the fixing member and that intersects with the incident surface and the exit surface, and a second intersecting surface that intersects with the incident surface and the exit surface and is opposite to the first intersecting surface, the housing has a first abutment surface that abuts on the incident surface at an end in the longitudinal direction in a state in which the optical member is fixed by the fixing member, and a second abutment surface on the side wall on an inner side of the housing, the cover member has an inner surface that is on the inside when the opening is closed, The fixing member has a first surface abutting the second abutment surface and a second surface abutting the exit surface when the optical member is fixed to the housing, a first portion extending toward the bottom surface, a third surface abutting the second intersecting surface and a second portion extending toward the bottom surface, and a fourth surface abutting the inner surface and a third portion connecting the first portion and the second portion. (Configuration 6) The inner surface has a recess, The aforementioned fourth surface is in contact with the recessed portion. (Configuration 7) the housing has a protrusion on the side wall protruding toward an outside of the housing, The above-mentioned scanning optical device, wherein the cover member has an engaged portion that engages with the protrusion. (Configuration 8) the housing has a hole in the vicinity of the first contact surface, the cover member has a through hole at a position corresponding to the hole portion when the cover member closes the opening, The above-mentioned scanning optical device, wherein the housing and the cover member are fixed to each other by inserting screws into the through holes and the holes. (Configuration 9) The above scanning optical device; an image forming means for forming an image on a recording material based on the light beam emitted from the scanning optical device; An image forming apparatus comprising: [Explanation of symbols]

[0068] 1 Laser unit 5 Deflection device 7 fθ lens 7a Positioning surface 7b Pressed surface 7c Positioning surface 7d Pressed surface 8 Optical box 8a, 8b, 8c Positioning surfaces 8d Engaging portion 9 Fixing member 9a Positioning surface 9b Pressing surface 9c Engaged portion 9d Pressing surface

Claims

1. A light source; a deflector for deflecting and scanning the light beam emitted from the light source; an optical member for guiding the light beam scanned by the deflector to a scanned object; a housing having a bottom surface to which the deflector and the optical member are attached, and a side wall extending from the bottom surface and to which the light source is attached; a fixing member that positions the optical member with respect to the housing and fixes an end portion of the optical member in a longitudinal direction; A scanning optical device comprising: the housing, the optical member, and the fixing member are made of resin, the optical member has an incident surface on which the light beam deflected and scanned by the deflector is incident, an exit surface from which the incident light beam exits, a first intersecting surface that abuts against the bottom surface in a state in which the optical member is fixed by the fixing member and that intersects with the incident surface and the exit surface, and a second intersecting surface that intersects with the incident surface and the exit surface and is opposite to the first intersecting surface, the housing has a first contact surface that contacts the incident surface at an end in the longitudinal direction in a state in which the optical member is fixed by the fixing member, a side surface on an outer side of the housing at the side wall, and a second contact surface on an inner side of the housing at the side wall, the side surface has a protruding portion protruding outward from the housing, The fixing member has an engaged portion that engages with the protrusion when the optical member is fixed to the housing, a first portion extending toward the bottom surface, a first surface abutting the second abutment surface, a second surface abutting the exit surface, a second portion extending toward the bottom surface, and a third surface abutting the second intersecting surface, the third portion extending toward the bottom surface.

2. When the protruding portion is a first protruding portion and the engaged portion is a first engaged portion, the housing has a second protruding portion protruding on an opposite side to the first contact surface, 2. The scanning optical device according to claim 1, wherein the fixed member has a second engaged portion that engages with the second protruding portion.

3. The protrusion is provided on a side wall parallel to the longitudinal direction, 2. The scanning optical device according to claim 1, wherein the first portion is provided parallel to the second portion.

4. The protrusion is provided on a side wall perpendicular to the longitudinal direction, 2. The scanning optical device according to claim 1, wherein the first portion is disposed so as to be perpendicular to the second portion.

5. A light source; a deflector for deflecting and scanning the light beam emitted from the light source; an optical member for guiding the light beam scanned by the deflector to a scanned object; a housing having a bottom surface to which the deflector and the optical member are attached, and a side wall extending from the bottom surface and to which the light source is attached; a cover member that closes an opening formed by the side wall; a fixing member that positions the optical member with respect to the housing and fixes an end portion of the optical member in a longitudinal direction; A scanning optical device comprising: the housing, the optical member, and the fixing member are made of resin, the optical member has an incident surface on which the light beam deflected and scanned by the deflector is incident, an exit surface from which the incident light beam exits, a first intersecting surface that abuts against the bottom surface in a state in which the optical member is fixed by the fixing member and that intersects with the incident surface and the exit surface, and a second intersecting surface that intersects with the incident surface and the exit surface and is opposite to the first intersecting surface, the housing has a first abutment surface that abuts on the incident surface at an end in the longitudinal direction in a state in which the optical member is fixed by the fixing member, and a second abutment surface on the side wall on an inner side of the housing, the cover member has an inner surface that is on the inside when the opening is closed, The fixing member has a first surface abutting the second abutment surface and a second surface abutting the exit surface when the optical member is fixed to the housing, a first portion extending toward the bottom surface, a third surface abutting the second intersecting surface, a second portion extending toward the bottom surface, and a fourth surface abutting the inner surface, connecting the first portion and the second portion.

6. The inner surface has a recess, 6. The scanning optical device according to claim 5, wherein the fourth surface abuts against the recess.

7. the housing has a protrusion on the side wall protruding toward an outside of the housing, 6. The scanning optical device according to claim 5, wherein the cover member has an engaged portion that engages with the protrusion.

8. the housing has a hole in the vicinity of the first contact surface, the cover member has a through hole at a position corresponding to the hole portion when the cover member closes the opening, 6. The scanning optical device according to claim 5, wherein the housing and the cover member are fixed to each other by inserting a screw into the through hole and the hole.

9. A scanning optical device according to any one of claims 1 to 8; an image forming means for forming an image on a recording material based on the light beam emitted from the scanning optical device; An image forming apparatus comprising:

Images