Optical scanning device and image forming apparatus

Abstract

This invention discloses an optical scanning device and an image forming apparatus. The optical scanning device includes a plurality of light source units and a housing of the optical scanning device. Each of the plurality of light source units includes a light source and a holder for holding the light source. The housing includes a plurality of mounting surfaces for holding a cylindrical portion of the holder. Each of the holders includes two protrusions at one end of the holder in a direction relative to the central axis of the cylindrical portion, which are perpendicular to the central axis of the cylindrical portion and extend away from each other in a direction when the light source unit is viewed in the axial direction of the central axis. Each of the protrusions is provided with a U-shaped cutout portion.

Description

Technical Field

[0001] The present invention relates to an optical scanning device and an image forming apparatus equipped with an optical scanning device. Background Technology

[0002] An optical scanning device installed in an electrophotographic image forming apparatus is known to have the following structure. The optical scanning device is equipped with a laser unit and an optical deflector. The laser unit consists of a laser diode as a light source, a collimating lens, and a holder for the laser diode and collimating lens. The optical deflector deflects the laser beam emitted from the laser unit. Furthermore, the optical scanning device is equipped with optical elements such as lenses and mirrors, such that the laser beam deflected by the optical deflector forms a latent image on the scanning surface. In the case of a color image forming apparatus that forms a color image on recording material, an optical scanning device with multiple laser diodes mounted in a housing is used. To achieve high image quality and high productivity, multiple laser diodes are used as the light source for the optical scanning device, wherein each laser diode has multiple light emission points.

[0003] For example, Japanese Patent Application Publication No. 2018-132643 discloses an optical scanning device in which four multi-beam laser diodes are mounted in a housing. As described in No. 2018-132643, the multi-beam laser diodes are mounted in the housing after adjusting the interval (hereinafter referred to as beam spacing) between the scanning positions on the photosensitive drum, which serves as the scanning surface of the laser beams emitted from each light source, according to the resolution of the image. The adjustment of the beam spacing of the laser beams emitted by the multi-beam laser diodes is performed by rotating the laser unit, which is mounted on the housing, by applying a torque to an adjustment protrusion on a holder, such that it can rotate about the optical axis of the collimating lens.

[0004] For example, Japanese Patent Application Publication No. 2004-37836 discloses a method for holding a laser unit within a housing so that it can be easily rotated about the optical axis of a lens. In Japanese Patent Application Publication No. 2018-132643, an intermediate member is required between the laser unit and the housing; however, in Japanese Patent Application Publication No. 2004-37836, the cylindrical laser unit is directly pushed against the mounting surface of the housing using an elastic member. The configuration proposed in Japanese Patent Application Publication No. 2004-37836 holds the laser unit directly to the housing without an intermediate member, which improves mounting accuracy and reduces product cost.

[0005] In recent years, as image forming apparatuses have become smaller, there has been a need for further miniaturization of optical scanning devices. However, the conventional method of holding the laser unit in a housing, as described above, has the following problems. In the configuration proposed in the aforementioned Japanese Patent Application No. 2018-132643, the two laser units are mounted at different positions along the optical axis of the lens, thus failing to contribute to the miniaturization of the optical scanning device.

[0006] Furthermore, Japanese Patent Application No. 2004-37836 does not mention a method for adjusting the beam spacing of a laser unit using a multi-beam laser diode. However, in practice, to reduce the size of optical scanning equipment, it is necessary to place the laser units closer together. However, when the holder of the laser unit holding the multi-beam laser diode and collimating lens has a protrusion for adjustment, the size of the protrusion and the position of the laser unit are limited by space constraints. For example, if the adjustment protrusion is shortened, a larger force must be applied to the adjustment protrusion to rotate the laser unit. As a result, the laser unit is subjected to a large force in a direction different from the force applied to the mounting surface during adjustment, which may cause the mounting posture to collapse and hinder precise adjustment of the beam spacing. Furthermore, if the pressure applied to the mounting surface increases, the holder of the laser unit may deform, and the beam angle of the laser beam may change.

[0007] The present invention was made under these circumstances and is intended to reduce the size of optical scanning devices. Summary of the Invention

[0008] According to one aspect of the present invention, an optical scanning device is provided for illuminating a scanning surface with a light beam, the optical scanning device comprising: a plurality of light source units, each of the plurality of light source units including a light source and a holder for holding the light source, the light source having a plurality of light emission points for emitting a light beam; and a housing of the optical scanning device for holding the plurality of light source units, the housing including a plurality of mounting surfaces for holding a cylindrical portion of the holder for holding each of the plurality of light source units, wherein each of the holders includes two protruding portions at one end of the holder in a direction relative to the central axis of the cylindrical portion, protruding perpendicularly to the central axis of the cylindrical portion and extending in a direction away from the central axis when the light source unit is viewed in the axial direction of the central axis, the protruding portions being provided with U-shaped cutout portions.

[0009] Further features of the invention will become clear from the following description of exemplary embodiments (with reference to the accompanying drawings). Attached Figure Description

[0010] Figure 1 This is a cross-sectional view illustrating the configuration of the image forming apparatus according to an embodiment.

[0011] Figure 2 This is a cross-sectional view illustrating the configuration of an optical scanning device according to an embodiment.

[0012] Figure 3 This is a perspective view of the laser unit in the embodiment.

[0013] Figure 4 This is a diagram illustrating a method for mounting a laser unit on the housing of an optical scanning device according to an embodiment.

[0014] Figure 5 This is a view of a laser unit installed in the housing of an optical scanning device according to an illustrated embodiment.

[0015] Figure 6 This is a diagram illustrating how the beam spacing of the laser unit in an embodiment can be adjusted. Detailed Implementation

[0016] The following is a detailed description of embodiments of the present invention with reference to the accompanying drawings.

[0017] [Example]

[0018] [Configuration of the image forming apparatus]

[0019] Figure 1 A cross-sectional view of the electrophotographic image forming apparatus 1 is shown. (As shown) Figure 1 As shown, four processing cartridges, PY, PM, PC, and PK, are arranged horizontally in the image forming apparatus. Processing cartridges PY, PM, PC, and PK contain toners of yellow (Y), magenta (M), cyan (C), and black (K), respectively. Because the toner capacity of processing cartridge PK is greater than that of the other processing cartridges PY, PM, and PC, its height (length along the Z-axis in the figure) is larger. In processing cartridges PY, PM, PC, and PK, the photosensitive drums 11 (11a, 11b, 11c, 11d) and developing rollers 12 (12a, 12b, 12c, 12d), which serve as image-carrying components, are integrally arranged. The developing rollers 12 develop the electrostatic latent image by attaching toner to the electrostatic latent image formed on the photosensitive drum 11 (on the photosensitive drum) to form a toner image. Figure 1 As shown, each of the processing boxes PY, PM, PC, and PK has the same configuration. The a, b, c, and d at the end of the code correspond to the processing boxes PY, PM, PC, and PK, respectively. In the following, the a, b, c, and d at the end are omitted unless they refer to a specific color member.

[0020] Optical scanning device 2 is located above processing cartridges PY, PM, PC, and PK in the figure. Optical scanning device 2 illuminates the photosensitive drum 11 of each processing cartridge PY, PM, PC, and PK with a laser beam (light beam) based on image information, forming an electrostatic latent image on the surface of the photosensitive drum 11. On the other hand, intermediate transfer belt unit 20 is located below processing cartridges PY, PM, PC, and PK in the figure. Intermediate transfer belt unit 20 consists of intermediate transfer belt 21, drive roller 22, tension roller 23, and driven roller 24. Figure 1 As shown, the intermediate transfer belt 21 is stretched by the drive roller 22, the tension roller 23 and the driven roller 24, and rotates in the direction of the arrow (clockwise) in the figure.

[0021] The primary transfer roller 25 is positioned below the photosensitive drums 11 of each processing cartridge (PY, PM, PC, and PK) in a position facing the photosensitive drums 11. The intermediate transfer belt 21 is pushed towards the photosensitive drums 11 by the primary transfer roller 25. The toner images on the photosensitive drums 11 of each processing cartridge (PY, PM, PC, and PK) are sequentially superimposed onto the intermediate transfer belt 21 and transferred to form a color image. The drive roller 22 contacts the secondary transfer roller 26 via the intermediate transfer belt 21, and the color image on the intermediate transfer belt 21 is transferred to the recording material S fed from the sheet feed tray 61.

[0022] The fixing unit 30 and the ejection unit 40 are located in the image forming apparatus 1. The fixing unit 30 has a fixing film 31 that heats and transfers a color image onto the recording material S and a pressure roller 32 that presses the recording material S. Each of these rollers rotates in the direction of the arrow in the figure to convey the recording material S. By doing so, the color image is fixed onto the recording material S. On the other hand, the ejection unit 40 has ejection rollers 41 and 42 and ejects the recording material S conveyed from the fixing unit 30 to a stacking tray 50, which is provided on the upper surface of the image forming apparatus 1 and has a beveled portion 51.

[0023] In each of the processing cartridges PY, PM, PC, and PK, the photosensitive drum 11 rotates during image formation, and the surface of the photosensitive drum 11 is charged to a uniform potential by a charging roller (not shown). Then, the photosensitive drum 11, charged to a uniform potential, is irradiated from the optical scanning device 2 using a laser beam (indicated by dashed lines in the figure) corresponding to the image information, and exposure is performed. As a result, an electrostatic latent image is formed on the surface of the photosensitive drum 11, and the formed electrostatic latent image is developed by the developing roller 12 to form a toner image for each color. The toner images on the photosensitive drum 11 are then sequentially superimposed and transferred onto an intermediate transfer belt 21 to form a color image.

[0024] On the other hand, the recording material S, which is a recording medium stacked in the sheet feeding tray 61 of the sheet feeding device 60, is fed by the sheet feeding roller 62, which rotates in the direction of the arrow in the figure (clockwise). The overlapping recording materials S are separated by the separating roller 63 and conveyed. Then, the recording material S is fed to the clamping portion where the drive roller 22 and the secondary transfer roller 26 contact each other, and in the clamping portion, the color image formed on the intermediate transfer belt 21 is transferred to the fed recording material S. Thereafter, the recording material S with the transferred color image is conveyed to the clamping portion where the fixing film 31 and the pressure roller 32 of the fixing unit 30 contact each other, and is heated and pressurized to fix the transferred color image onto the recording material S. The recording material S with the color image fixed is discharged by the discharge unit 40 to the stacking tray 50 and stacked in the inclined portion 51.

[0025] [Configuration of optical scanning equipment]

[0026] Figure 2 It shows the installation Figure 1 A cross-sectional view of the optical scanning device 2 on the image forming apparatus 1. The optical scanning device 2 is equipped with a laser unit (not shown) that emits laser light, an optical deflector SM that deflects the laser light, and an imaging lens and a mirror that guide the laser light deflected by the optical deflector SM to the photosensitive drum 11 of each processing box PY, PM, PC, and PK. In the optical scanning device 2, the optical deflector SM is placed at the center of the housing (also called the optical box) 201, as shown in the image forming apparatus 1. Figure 2 As shown in the figure, the optical deflector SM has a rotating polygonal mirror 200 that deflects a laser beam incident from a laser unit, a rotor portion 204 that serves as a driver portion for driving the rotating polygonal mirror 200, and a motor drive board 203 on which the rotor portion 204 is mounted.

[0027] exist Figure 2 In the optical deflector SM, on the left side, a first image forming lens N1, second image forming lenses N1a and N1b, and first and second reflectors M1a, M1b, and M2b are arranged, which transmit and reflect the laser beam. On the other hand, on the right side of the optical deflector SM, a first imaging lens N2, second imaging lenses N2c and N2d, and first reflectors M1c, M1d, and M2c are arranged, which transmit and reflect the laser beam. The optical deflector SM, each imaging lens, and each reflector are fixed inside the housing 201, and the interior of the housing 201 is sealed by attaching a housing cover 202 that seals the opening of the housing 201.

[0028] exist Figure 2On the front side of the optical scanning device 2 shown, there is a laser unit (not shown) that emits a laser beam to form an electrostatic latent image on the photosensitive drum 11 of each of the processing cartridges PY, PM, PC, and PK, and exposes the photosensitive drum 11. A laser unit is provided for each photosensitive drum 11 of the processing cartridges PY, PM, PC, and PK. The laser beam La emitted from the laser unit corresponding to the photosensitive drum 11a of the processing cartridge PY is deflected by the rotating polygonal mirror 200 of the optical deflector SM and enters the first imaging lens N1. The laser beam La passing through the first imaging lens N1 is reflected by the first reflecting mirror M1a. The laser beam La reflected by the first reflecting mirror M1a passes through the second imaging lens N1a, the exit port on the housing cover 202, and scans the photosensitive drum 11a.

[0029] The laser beam Lb emitted from the laser unit corresponding to the photosensitive drum 11b of the processing box PM is deflected by the rotating polygonal mirror 200 of the optical deflector SM and enters the first imaging lens N1. The laser beam Lb passing through the first imaging lens N1 is reflected by the first reflecting mirror M1b. The laser beam Lb reflected by the first reflecting mirror M1b is then reflected by the second reflecting mirror M2b. The laser beam Lb reflected by the second reflecting mirror M2b passes through the second imaging lens N1b, the exit port on the housing cover 202, and scans the photosensitive drum 11b.

[0030] A laser beam Lc emitted from the laser unit corresponding to the photosensitive drum 11c of the processing cartridge PC is deflected by the rotating polygonal mirror 200 of the optical deflector SM and enters the first imaging lens N2. The laser beam Lc passing through the first imaging lens N2 is reflected by the first reflecting mirror M1c. The laser beam Lc reflected by the first reflecting mirror M1c enters the second imaging lens N2c. The laser beam Lc passing through the second imaging lens N2c is reflected by the second reflecting mirror M2c, passes through the exit port provided on the housing cover 202, and scans the photosensitive drum 11c.

[0031] The laser Ld emitted from the laser unit corresponding to the photosensitive drum 11d of the processing box PK is deflected by the rotating polygonal mirror 200 of the optical deflector SM and enters the first imaging lens N2. The laser beam Ld passing through the first imaging lens N2 is reflected by the first reflecting mirror M1d. The laser beam Ld reflected by the first reflecting mirror M1d passes through the second imaging lens N2d and the exit port on the housing cover 202, and scans the photosensitive drum 11d.

[0032] [Laser unit configuration]

[0033] Figure 3This is a schematic diagram of laser unit 3, which is a light source unit having a light source that emits laser light. Laser unit 3 consists of a dual-beam laser diode (hereinafter referred to as the "light source") 301 with two light emission points, a collimating lens 302, and a holder 303. Holder 303 has an internally hollow cylindrical shape, and the collimating lens 302 is mounted on one end, while the other end has protrusions 304A and 304B for position adjustment. Protrusions 304A and 304B extend in a direction perpendicular to the cylindrical axis (which is the central axis of the holder 303, which is the cylindrical portion), as described below. The central portions of protrusions 304A and 304B, as protrusions, are provided with U-shaped cutouts for gripping (grasp) laser unit 3 using a beam spacing adjustment tool of laser unit 3, which will be described later. In addition, a through hole (not shown) is provided at the center of the end side of the retainer 303, which is provided with protrusions 304A and 304B, for press-fitting the light source 301.

[0034] The retainer 303 has cylindrical side portions 303A and 303B, which contact the mounting surface of the housing 201 of the optical scanning device 2 when the laser unit 3 is mounted on the housing 201. The light source 301 is pressed into and fixed to the retainer 303 from the front side in the depth direction. At this time, the light source 301 is fixed to the retainer 303 at a position where the beam spacing adjustment error, described later, is approximately a few degrees (e.g., approximately 2 or 3 degrees). The four terminals protruding from the light source 301 in the foreground direction in the figure are the lead terminals 301C of the light source 301. On the other hand, the collimating lens 302 is attached to the end opposite to the end of the retainer 303 where the light source 301 is pressed in, and is fixed with adhesive after the position of the light source 301 is adjusted.

[0035] [Mounting of the laser unit on the housing]

[0036] Next, the method of mounting the laser unit 3 to the housing 201 will be explained. Figure 4 This is a diagram of a laser unit 3 mounted on housing 201 that irradiates the photosensitive drum 11 of processing boxes PY, PM, PC and PK with a laser beam. Figure 4 The four laser units 3Y, 3M, 3C, and 3K shown represent laser units 3 that respectively illuminate the photosensitive drums 11 of the processing cartridges PY, PM, PC, and PK. Figure 4 Only the middle part is shown Figure 2 A portion of the housing 201 shown. To explain the configuration of the housing 201 for mounting the laser unit 3, Figure 4Laser unit 3Y removed from housing 201 and laser units 3M, 3C, and 3K mounted in housing 201 are shown. Figure 4 In this configuration, laser unit 3Y has a collimating lens 302 mounted on one end of holder 303, and light source 301 (not shown) is fixed to one end having protrusions 304A and 304B. Four lead terminals 301C of the light source protrude from control board 209. Control board 209 has through holes 210Y, 210M, 210C, and 210K, into which the lead terminals 301C of the light source 301 of laser units 3Y, 3M, 3C, and 3K are inserted.

[0037] The mounting portion of the laser unit 3Y in the mounting housing 201 has a trapezoidal shape, which consists of two opposing inclined planes (mounting surfaces) and a plane connecting these two inclined planes (mounting surfaces). More specifically, as... Figure 4 As shown, in the mounting portion of the laser unit 3Y mounted on the housing 201, mounting surfaces 205 and 206 are provided on the mounting portion of the cylindrical side portion 303A of the laser unit 3Y. On the other hand, mounting surfaces 207 and 208 are provided on the mounting portion of the cylindrical side portion 303B. When the laser unit 3Y is mounted on the housing 201, the cylindrical side portion 303A of the retainer 303 contacts the mounting surfaces 205 and 206, and the cylindrical side portion 303B contacts the mounting surfaces 207 and 208. The retainer 303 is then held in place by an elastic member (spring) 211 (participating in...). Figure 5 and Figure 6 The laser unit 3Y is pushed in the direction of the mounting surfaces 205, 206, 207, and 208 of the housing. The laser unit 3Y is held in the housing 201 such that the retainer 303 can rotate about a cylindrical axis by sliding the cylindrical side portions 303A and 303B on the mounting surfaces 205, 206, 207, and 208. When the laser unit 3Y is mounted on the housing 201, one of the protrusions 304A and 304B abuts against the housing 201, thereby positioning the laser unit 3Y in the direction of the cylindrical axis.

[0038] Here, we have used laser unit 3Y to explain how laser unit 3 is mounted on housing 201, but other laser units 3M, 3C, and 3K can be mounted on housing 201 in the same way. For example... Figure 4As shown, each mounting portion is arranged in a grid pattern, but the positions of the mounting portions to which the laser units 3 of housing 201 are mounted differ between laser units 3Y and 3C and laser units 3M and 3K. The mounting portions (mounting surfaces 205 to 208) of housing 201 to which laser units 3Y and 3C are mounted are located below laser units 3Y and 3C in the figure. On the other hand, the mounting portions (mounting surfaces 205 to 208) to which laser units 3M and 3K of housing 201 are mounted are located above laser units 3M and 3K in the figure.

[0039] After the beam spacing in the sub-scanning direction (rotation direction of the photosensitive drum), which will be described later, is adjusted to a predetermined range, each laser unit 3 attached to the housing 201 is fixed to the housing 201 using adhesive. After the four laser units 3 are fixed with adhesive, the control board 209 of the optical scanning device 2 is fixed to the housing 201, wherein the lead terminals 301C of the corresponding light sources 301 are inserted into the through holes 210 provided on the control board 209. Then, the lead terminals 301C of the light sources 301 are soldered to the control board 209.

[0040] [Laser Unit Layout Configuration]

[0041] Figure 5 It shows in Figure 4 The figure shows the laser units 3 (3Y, 3M, 3C, 3K) mounted on the housing 201 from the lead terminal 301C side of the light source 301 after removing the control board 209. Figure 5 As can be seen, the holder 303 of the laser unit 3 is pushed by the elastic member 211 in the directions of the mounting surfaces 205, 206, 207, and 208.

[0042] like Figure 5 As shown, by mounting four laser units 3Y, 3M, 3C, and 3K very close to each other in the Z and Y axes, the volume occupied by the laser unit 3 in the housing 201 can be reduced, and the optical scanning device 2 can be made smaller. Therefore, in this embodiment, the laser units 3Y, 3M, 3C, and 3K are arranged such that the straight line CS connecting the center of the cylindrical axis of the holder 303 of the laser units 3 adjacent to each other in the Z and Y axes forms a square or rectangle. Furthermore, in Figure 5In this case, the straight line L304 connecting the protrusions 304A and 304B of each laser unit 3 is inclined with respect to any one of the four straight lines CS. Specifically, the laser units are mounted in the housing 201 such that the straight line L304 connecting the protrusions 304A and 304B of each laser unit 3 is parallel to the straight line D passing through the centers of the cylindrical axes of the holders 303 of the laser units 3Y and 3K in the diagonal direction among adjacent laser units 3. As a result, the area enclosed by the laser units 3 can be effectively utilized as the placement area for the protrusions 304A and 304B for position adjustment, which will be described later, and a more compact size of the optical scanning device 2 can be achieved. Moreover, at this time, the following limitation is imposed on the length Lh from the center of the cylindrical axis of the holder 303 of the laser unit 3 to the tips of the protrusions 304A and 304B to prevent contact between the protrusion 304B of the laser unit 3Y and the protrusion 304A of the laser unit 3K. That is, in Figure 5 this case, if the length from the center QY of the cylindrical axis of the holder 303 of the laser unit 3Y to the center QK of the cylindrical axis of the holder 303 of the laser unit 3K is Ld, then the relationship that the length Lh is shorter than 1 / 2 (half) of the length Ld (Lh < Ld / 2) is established.

[0043] Each laser unit 3 can be mounted in the housing 201 such that the straight line L304 connecting the protrusions 304A and 304B is parallel to the straight line passing through the centers of the cylindrical axes of the holders 303 of the laser units 3C and 3M in the diagonal direction among adjacent laser units 3.

[0044] [Adjustment of Beam Spacing of Light Source]

[0045] Figure 6 is a schematic diagram explaining how to adjust the beam spacing of the laser unit 3. In Figure 6 this case, the laser unit 3 is mounted on the mounting portion of the housing 201, and the elastic member 211 pushes it in the direction of the mounting portion of the housing 201. Specifically, the cylindrical side portion 303B of the holder 303 of the laser unit 3 contacts the mounting surfaces 207 and 208 of the housing 201, and the cylindrical side portion 303A (not shown) contacts the mounting surfaces 205 (not shown) and 206 (not shown) of the housing 201. Then, by means of the elastic member 211, the cylindrical side portions 303A and 303B of the holder 303 of the laser unit 3 are pushed in the directions of the mounting surfaces 205, 206, 207, and 208 of the housing 201.

[0046] In this embodiment, the light source 301 is a multi-beam laser diode with two light emission points 301A and 301B. After adjusting the beam spacing (scan position interval) of the laser beams emitted from each light emission point of the light source 301 on the photosensitive drum 11 according to the image resolution, the laser unit 3 is fixed to the housing 201 using adhesive. The beam spacing is adjusted by rotating the elastic member 211 around the cylindrical axis of the retainer 303 and pushing it with a force Fs against the mounting surface 205 of the housing 201 (see [link to relevant documentation]). Figure 4 ), 206 (see Figure 4 The laser unit 3, consisting of 207 and 208, performs the adjustment. Specifically, the U-shaped cutouts 304AD and 304BD provided in the center of two opposing adjustment protrusions 304A and 304B are gripped by the adjustment tool J (the shaded circular portion in the figure), and the laser unit 3 is rotated by the adjustment tool J around the cylindrical axis of the retainer 303. By doing so, the positions of the two light emission points 301A and 301B of the light source 301, which are pressed and fixed to the retainer 303, are adjusted.

[0047] For example, suppose the two light emission points of light source 301 are located at positions 301A and 301B in the figure, and the desired light emission point positions are 301A' and 301B'. In this case, the laser unit 3 is rotated in the direction of the arrow (clockwise) in the figure using the adjustment tool J to adjust the beam spacing. The corresponding rotational torque M for protrusions 304A and 304B when rotating the laser unit 3 can be obtained as follows. That is, the rotational torque M is obtained by multiplying the distance Lj from the center Q of the cylindrical axis of the holder 303 to the contact point of the adjustment tool J with the protrusions 304A and 304B by the force Fj applied by the adjustment tool J to the protrusions 304A and 304B (rotational torque M = distance Lj × force Fj). If the laser unit 3 is miniaturized and the protrusions 304A and 304B are shortened, then the distance Lj will be shortened, but the required rotational torque M can be obtained by increasing the force Fj to that extent.

[0048] When the laser unit 3 rotates about the cylindrical axis of the holder 303, on the mounting surface 205 (see...) Figure 4 ), 206 (see Figure 4 ), 207, 208 and the cylindrical side portion 303A of the retainer 303 (see Figure 4Friction occurs between protrusions 304A and 304B. When the adjustment tool J applies a force Fj to protrusions 304A and 304B, a force is generated that attempts to move the laser unit 3 in a direction other than the rotational direction of the holder 303. For example, the force Fj on the protrusion 304A side generates a force in a direction away from the mounting surface 208 that moves the holder 303. To counteract this, if the pushing force Fs applied by the elastic member 211 is made stronger, the forces between the cylindrical side portions 303A and 303B of the holder 303 and the mounting surfaces 205, 206, 207, 208, and between the cylindrical side portions 303A and 303B and the elastic member 211, increase. As a result, movement of the laser unit 3 in the rotational direction is hindered. However, in this embodiment, when the laser unit 3 is rotated, the adjustment tool J not only grips protrusion 304A but also grips the oppositely arranged protrusions 304B, and can apply a force Fj in a direction opposite to each other. Therefore, it is possible to counteract the force that attempts to move the laser unit 3 in the rotational direction of the non-holder 303.

[0049] In this embodiment, the laser unit 3 is provided with opposing protrusions 304A and 304B around the cylindrical axis of the retainer 303 for position adjustment. For example, it is assumed that the distance Lj from the center Q of the cylindrical axis of the retainer 303 to the contact point of the adjustment tool J with the protrusions 304A and 304B (or the length Lh from the center Q of the cylindrical axis of the retainer 303 to the tips of the protrusions 304A and 304B) is shortened to reduce the size of the laser unit 3. This allows the laser unit 3 to be rotated while maintaining the posture of the retainer 303, which is pushed against the housing 201 by the elastic member 211, even when the force Fj required to rotate the retainer 303 increases.

[0050] exist Figure 6 In the illustration, to show how the beam spacing is adjusted, the holder 303 of the laser unit 3 is placed on the mounting surfaces 205, 206, 207, and 208 of the housing 201, such that the protrusions 304A and 304B are in the horizontal direction rather than in the vertical direction. Figure 5 In the diagonal direction shown. In Figure 6 To clearly explain the beam spacing adjustment, the angle to be adjusted is shown at a large scale. For example... Figure 5 As shown, laser unit 3 is installed such that protrusions 304A and 304B are in Figure 5 As shown in the diagonal direction, the angles of protrusions 304A and 304B remain almost unchanged before and after the beam spacing adjustment.

[0051] As described above, even if the protrusions 304A and 304B on the laser unit 3 are miniaturized, the optical scanning device 2 can also be miniaturized without degrading the beam spacing adjustment accuracy. In this embodiment, the collimating lens 302 is mounted on the laser unit 3. However, this is not limited to this configuration, and the collimating lens 302 can be fixed by attaching it to the housing 201 after the position relative to the light source 301 has been adjusted.

[0052] As described above, this embodiment allows us to miniaturize optical scanning devices.

[0053] While the invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be given the broadest interpretation in order to cover all such modifications and equivalent structures and functions.

Claims

1. An optical scanning device for illuminating a scanning surface with a light beam, the optical scanning device comprising: Four light source units, each of the four light source units including a light source and a holder for holding the light source, the light source having a plurality of light emission points for emitting a light beam; as well as The optical scanning device includes a housing for holding the four light source units, the housing comprising four mounting surfaces for holding the cylindrical portion of the holder of each of the four light source units. Each of the four retainers includes two protruding portions at one end of the four retainers in the direction relative to the central axis of the cylindrical portion, protruding perpendicularly to the central axis of the cylindrical portion and extending away from each other in a direction when the light source unit is viewed in the direction of the central axis. Each of the protruding portions is provided with a U-shaped cutout. When viewed in the direction of the central axis, each of the four retainers has the following shape: in which the centers of the two protruding portions and the cylindrical portion are aligned on a virtual straight line. When viewed along the central axis, the four light source units are arranged such that the four lines connecting the four centers of the four cylindrical portions form a rectangle. When viewed in the direction of the central axis, the four light source units are arranged such that each of the four virtual straight lines of the holders is substantially parallel to one of the two diagonals of the rectangle. The first length from the center of the cylindrical portion of each of the four retainers to the front end of one of the two protrusions of each of the four retainers is shorter than half the length of the diagonal, such that the two retainers on the diagonal do not interfere with each other.

2. The optical scanning device according to claim 1, wherein, The four light source units are positioned relative to the housing in the direction of the central axis by having one of the two protruding portions contact the housing.

3. The optical scanning device according to claim 1, wherein, The light source unit is fixed to one end of each of the four retainers, which provides the protruding portion, and the collimating lens is fixed to the other end of each of the four retainers.

4. The optical scanning device according to claim 1, wherein, The cut portion includes a tool entry section for adjusting the beam spacing of the plurality of light emission points.

5. An image forming apparatus for forming toner images on a recording material, the image forming apparatus comprising an image forming portion for overlaying toner images that are different in color onto the recording material, the image forming portion comprising: Four photosensitive components; An optical scanning device according to claim 1, used to illuminate each of the four photosensitive elements with a light beam in response to image information; as well as Four developing devices are used to develop latent images using different toners of different colors, the latent images being formed by the optical scanning device on the four photosensitive elements.

Images