JP2012203055A - Optical scanning device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thin optical scanning device without increasing cost.SOLUTION: An optical scanning system A comprises: two scanning lenses (2105a, 2105b); one reflection mirror 2106A reflecting two light fluxes through the two scanning lenses; a separation mirror 2107b separating the light path of a light flux LBb from the path of a light flux LBa; a light guide mirror 2108a guiding the light flux LBa to a photoreceptor drum 2030a; and light guide mirrors (2108b, 2109b) guiding the light flux LBa to the photoreceptor drum 2030a. The incident positions of the light flux LBb in the separation mirror 2107a, the light flux LBb in the light guide mirror 2109b and the light flux LBa in the light guide mirror 2108a are the same in a z-axis direction.

Description

  The present invention relates to an optical scanning device and an image forming apparatus, and more particularly to an optical scanning device that scans a surface to be scanned with light and an image forming apparatus including the optical scanning device.

  In electrophotographic image forming apparatuses used in laser printers, laser plotters, digital copying machines, plain paper facsimiles, or multi-function machines including these, in recent years, colorization and speeding up have progressed, and photoconductors that are image carriers. A tandem type image forming apparatus having a plurality of drums (usually four) is widely used. Along with this, there has been an increasing demand for downsizing and high image quality of image forming apparatuses. Accordingly, various studies have been made on further downsizing and improvement in scanning accuracy of the optical scanning device constituting a part of the image forming apparatus.

  For example, Patent Document 1 discloses a structure in which a light beam is reflected two or more times on the optical path that is guided by a plane mirror and a cylindrical mirror to reach a plurality of photosensitive members, and the corresponding reflection angle is set for each light beam. In the sub-scan section including the rotation axis of the deflector, the adjacent optical paths of the light beams divided in the optical path are parallel to each other at equal intervals, and in the sub-scan section including the rotation axis of the deflector. A light beam scanning device is disclosed in which a normal surface of a reflecting surface of a plane mirror that performs optical path division and a straight line connecting rotation axes of a plurality of photosensitive members are substantially parallel.

  Further, in Patent Document 2, a plurality of scanning beams are folded back by the same reflecting surface of at least one mirror, and any one or more optical axes of the scanning lens are substantially arranged with respect to the scanning plane formed by the optical deflector. An optical scanning device arranged in parallel or substantially vertically is disclosed.

  Further, Patent Document 3 discloses a multi-beam scanning optical system including a multi-sided long mirror that reflects a plurality of beams or beam groups in different directions on a plurality of reflecting surfaces.

  Patent Document 4 discloses an optical scanning device in which the scanning optical system is an overfilled optical system, and a plurality of beams are incident on the same deflection surface at an angle with respect to each other in the sub-scanning direction.

  In Patent Document 5, M light beams from the light source means are deflected and scanned in the main scanning direction, and M scanning light beams are guided in the sub scanning direction different from the main scanning direction. An image forming apparatus including an optical scanning unit that selectively switches a latent image carrier irradiated with M scanning light beams among the latent image carriers is disclosed.

  Patent Document 6 discloses n sets of scanning imaging optical systems that guide light beams, which are deflected by a polygon mirror optical deflector, to corresponding optical scanning positions to form light spots, and an optical path selection means for selecting an optical scanning optical path for each of the n sets of light beams, and the polygon mirror type optical deflector rotates the polygon mirror having N (≧ 2) planes of deflection reflection surfaces as a rotation axis. Q-stages are stacked in the direction, and the polygon mirrors of each stage rotate by a predetermined angle relative to the rotation direction, so that the deflecting reflection surfaces deviate from each other by a predetermined angle (≠ 0) in the rotation direction, An optical scanning device is disclosed in which the polygon mirror type optical deflector also serves as an optical path selection unit, and the predetermined angle is smaller than (360 / N) degrees.

  However, the light beam scanning device disclosed in Patent Document 1 has a disadvantage that it is difficult to reduce the thickness. In addition, since a cylindrical mirror is used, there is a disadvantage that the cost is increased.

  Further, the optical scanning device disclosed in Patent Document 2 has a disadvantage that the degree of freedom of the optical path layout is small. In addition, it is difficult to reduce the number of folding mirrors. Further, since the scanning optical system is composed of two scanning lenses, there is a disadvantage that it is difficult to reduce the thickness.

  In addition, the multi-beam scanning optical system disclosed in Patent Document 3 has a disadvantage in that the cost is increased because a multi-sided long mirror is used.

  Further, the image forming apparatus disclosed in Patent Document 5 has a disadvantage that it is difficult to reduce the thickness.

  Further, in the optical scanning devices disclosed in Patent Document 4 and Patent Document 6, since a field angle that can be scanned by one deflecting / reflecting surface is narrow, a desired scanning width (writing width) is scanned on the surface to be scanned. To this end, it is necessary to increase the focal length in the main scanning direction of the scanning optical system. In that case, there is a disadvantage that the optical path length of the scanning beam from the deflection reflection surface to the surface to be scanned becomes long. In order to rotate the polygon mirror at high speed, it is desirable to reduce the inscribed circle radius of the polygon mirror. However, if the inscribed circle radius is reduced, the width of the deflecting / reflecting surface (the length in the direction perpendicular to the rotation axis) is reduced, which necessitates further increasing the optical path length.

  The optical path of the scanning beam can be bent by a folding mirror or the like. However, if the optical path length of the scanning beam is long, it is difficult to make the scanning optical system compact. As a result, it is difficult to reduce the thickness. In addition, the folding mirror is a relatively expensive part, and its performance (surface accuracy, reflectance, etc.) depends on the beam characteristics (scanning line shape, field curvature, scanning line length, shading, etc.) on the scanned surface. Affect. Therefore, there has been a demand to reduce the number of folding mirrors as much as possible.

  The present invention has been made under such circumstances, and a first object of the invention is to provide an optical scanning device that can be reduced in thickness without increasing the cost.

  A second object of the present invention is to provide an image forming apparatus that can be reduced in size without increasing the cost.

  From a first viewpoint, the present invention is an optical scanning device that individually scans a plurality of scanned surfaces with light in a first direction, and includes a plurality of light beams including a first light beam and a second light beam. An illumination system that emits light, an optical deflector that deflects a plurality of light beams from the illumination system, and a scanning optical system that individually collects the plurality of light beams deflected by the light deflector on a corresponding scanned surface The scanning optical system includes a separation mirror that separates the optical path of the first light flux from the optical path of the other light flux, and a light guide mirror that guides the second light flux to a corresponding scanned surface, The incident position of the first light beam in the separation mirror and the incident position of the second light beam in the light guide mirror are the same with respect to a second direction orthogonal to the first direction. This is an optical scanning device.

  According to this, it is possible to reduce the thickness without increasing the cost.

  According to a second aspect of the present invention, there is provided an image forming apparatus comprising: a plurality of image carriers; and the optical scanning device of the present invention that scans the plurality of image carriers with a light beam modulated in accordance with image data. It is.

  According to this, it is possible to reduce the size without increasing the cost.

1 is a diagram illustrating a schematic configuration of a color printer according to an embodiment of the present invention. It is a figure for demonstrating the optical scanning apparatus 2010A. It is a figure for demonstrating the optical scanning device 2010B. It is a figure for demonstrating the optical system A before a deflector. It is a figure for demonstrating the optical system B before a deflector. 2 is a diagram for explaining a scanning optical system A. FIG. 2 is a diagram for explaining a scanning optical system B. FIG. 5 is a diagram for explaining specific numerical examples in the scanning optical system A. FIG. It is a figure for demonstrating the attachment state to the optical housing of the cylindrical lens in the scanning optical system A, and a scanning lens. It is a figure for demonstrating an example of the magnitude | size of a cylindrical lens and an intermediate member. It is a figure for demonstrating an example of the magnitude | size of a scanning lens. It is a figure for demonstrating the attachment state to the optical housing of the cylindrical lens and scanning lens in the scanning optical system. It is a figure for demonstrating an inclination adjustment mechanism and a pushing mechanism. It is a figure for demonstrating the positional relationship of the optical scanning device 2010A and the optical scanning device 2010B. It is a figure for demonstrating the change of the width | variety regarding the subscanning corresponding direction of the light beam deflected by the polygon mirror. FIGS. 16A to 16D are diagrams for explaining an example 1 of scanning line bending on the surface of each photosensitive drum. FIG. 17A to FIG. 17D are diagrams for explaining a state in which the scanning line curve in Example 1 is corrected by the push-in mechanism. FIGS. 18A to 18D are diagrams for explaining an example 2 of scanning line bending on the surface of each photosensitive drum. FIG. 19A to FIG. 19D are diagrams for explaining a state in which the scanning line bending in Example 2 is corrected by the push-in mechanism. FIG. 20A is a diagram for explaining the color misregistration when the scanning line curve in Example 2 is corrected by the push-in mechanism, and FIG. 20B is the color misregistration when the writing start timing is further adjusted. It is a figure for demonstrating. FIGS. 21A to 21D are diagrams for explaining an example 3 of scanning line bending on the surface of each photosensitive drum. 22 (A) to 22 (D) are diagrams for explaining a state in which the scanning line curve in Example 3 is corrected by the push-in mechanism. FIG. 23A is a diagram for explaining the color misregistration when the scanning line bending in Example 3 is corrected by the push-in mechanism, and FIG. 23B is a color misregistration when the writing start timing is further adjusted. It is a figure for demonstrating. 24A to 24D are diagrams for explaining Example 1 of the scanning line inclination on the surface of each photosensitive drum. FIGS. 25A to 25D are diagrams for explaining states in which the scanning line inclination of Example 1 is corrected by the inclination adjustment mechanism. FIGS. 26A to 26D are diagrams for explaining Example 2 of the scanning line inclination on the surface of each photosensitive drum. FIGS. 27A to 27D are diagrams for explaining states in which the scanning line inclination of Example 2 is corrected by the inclination adjusting mechanism. FIG. 28A is a diagram for explaining color misregistration when the scan line tilt in Example 2 is corrected by the tilt adjusting mechanism, and FIG. 28B is a color when the write start timing is further adjusted. It is a figure for demonstrating deviation | shift. It is a figure for demonstrating the modification of the scanning optical system. FIG. 2 is a diagram (No. 1) for explaining an optical scanning device 2010 in which a scanning optical system A and a scanning optical system B are opposed to each other with a polygon mirror interposed therebetween. FIG. 10 is a diagram (No. 2) for explaining the optical scanning device 2010 in which the scanning optical system A and the scanning optical system B are opposed to each other with a polygon mirror interposed therebetween.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a schematic configuration of a color printer 2000 as an image forming apparatus according to an embodiment.

  The color printer 2000 is a tandem multicolor printer that forms a full-color image by superimposing four colors (black, magenta, cyan, and yellow), and includes two optical scanning devices (2010A and 2010B), four Photosensitive drums (2030a, 2030b, 2030c, 2030d), four cleaning units (2031a, 2031b, 2031c, 2031d), four charging devices (2032a, 2032b, 2032c, 2032d), and four developing rollers (2033a, 2033b, 2033c, 2033d), four toner cartridges (2034a, 2034b, 2034c, 2034d), transfer belt 2040, transfer roller 2042, fixing roller 2050, paper supply roller 2054, registration roller pair 2056, paper discharge roller La 2058, the paper feed tray 2060, a discharge tray 2070, and a like communication control unit 2080, and a printer controller 2090 for totally controlling the above elements.

  The communication control device 2080 controls bidirectional communication with a host device (for example, a personal computer) via a network or the like.

  The printer control device 2090 includes a CPU, a ROM described in a program written in code readable by the CPU, various data used when executing the program, a RAM as a working memory, an analog data An AD conversion circuit for converting the signal into digital data. Then, the printer control device 2090 sends black image information and magenta image information from the host device to the optical scanning device 2010A, and sends cyan image information and yellow image information to the optical scanning device 2010B.

  The photosensitive drum 2030a, the charging device 2032a, the developing roller 2033a, the toner cartridge 2034a, and the cleaning unit 2031a are used as a set and form an image forming station (hereinafter also referred to as “K station” for convenience) that forms a black image. Constitute.

  The photosensitive drum 2030b, the charging device 2032b, the developing roller 2033b, the toner cartridge 2034b, and the cleaning unit 2031b are used as a set, and form an image forming station (hereinafter also referred to as “M station” for convenience) that forms a magenta image. Constitute.

  The photosensitive drum 2030c, the charging device 2032c, the developing roller 2033c, the toner cartridge 2034c, and the cleaning unit 2031c are used as a set, and form an image forming station (hereinafter also referred to as “C station” for convenience) that forms a cyan image. Constitute.

  The photosensitive drum 2030d, the charging device 2032d, the developing roller 2033d, the toner cartridge 2034d, and the cleaning unit 2031d are used as a set, and form an image forming station (hereinafter also referred to as “Y station” for convenience) that forms a yellow image. Constitute.

  Each photosensitive drum has a photosensitive layer formed on the surface thereof. That is, the surface of each photoconductive drum is a surface to be scanned. Each photosensitive drum is rotated in the direction of the arrow in the plane of FIG. 1 by a rotation mechanism (not shown).

  Here, in the XYZ three-dimensional orthogonal coordinate system, the direction along the longitudinal direction (rotation axis direction) of each photosensitive drum is defined as the Y-axis direction, and the direction along the arrangement direction of the four photosensitive drums is defined as the X-axis direction. explain.

  Each charging device uniformly charges the surface of the corresponding photosensitive drum.

  The optical scanning device 2010A irradiates the surface of the charged photosensitive drum 2030a with the light beam modulated based on the black image information, and the charged photosensitive drum 2030b with the light beam modulated based on the magenta image information. Irradiate the surface. The optical scanning device 2010B irradiates the surface of the charged photoconductor drum 2030c with a light beam modulated based on cyan image information, and the charged photoconductor drum 2030d with the light beam modulated based on yellow image information. Irradiate the surface.

  As a result, on the surface of each photosensitive drum, the charge disappears only in the portion irradiated with light, and a latent image corresponding to the image information is formed. The latent image formed here moves in the direction of the corresponding developing roller as the photosensitive drum rotates. The configuration of each optical scanning device will be described later.

  As each developing roller rotates, the toner from the corresponding toner cartridge is thinly and uniformly applied to the surface thereof. Then, when the toner on the surface of each developing roller comes into contact with the surface of the corresponding photosensitive drum, the toner moves only to a portion irradiated with light on the surface and adheres to the surface. In other words, each developing roller causes toner to adhere to the latent image formed on the surface of the corresponding photosensitive drum so as to be visualized. Here, the toner-attached image (hereinafter referred to as “toner image”) moves in the direction of the transfer belt 2040 as the photosensitive drum rotates.

  Each toner image is sequentially transferred and superimposed on the transfer belt 2040 at a predetermined timing.

  Recording paper is stored in the paper feed tray 2060. A paper feed roller 2054 is disposed in the vicinity of the paper feed tray 2060, and the paper feed roller 2054 takes out the recording paper one by one from the paper feed tray 2060 and conveys it to the registration roller pair 2056. The registration roller pair 2056 feeds the recording paper toward the gap between the transfer belt 2040 and the transfer roller 2042 at a predetermined timing. As a result, the toner image on the transfer belt 2040 is transferred to the recording paper. Here, the recording sheet on which the toner image is transferred is sent to the fixing roller 2050.

  In the fixing roller 2050, heat and pressure are applied to the recording paper, whereby the toner is fixed on the recording paper. Here, the recording paper on which the toner is fixed is sent to a paper discharge tray 2070 via a paper discharge roller 2058 and is sequentially stacked on the paper discharge tray 2070.

  Each cleaning unit removes toner (residual toner) remaining on the surface of the corresponding photosensitive drum. The surface of the photosensitive drum from which the residual toner has been removed returns to the position facing the corresponding charging device again.

  Next, the configuration of the optical scanning device 2010A and the optical scanning device 2010B will be described. The optical scanning device 2010A and the optical scanning device 2010B are arranged side by side along the X-axis direction.

  In the following, for convenience, the direction corresponding to the main scanning direction is abbreviated as “main scanning corresponding direction”, and the direction corresponding to the sub scanning direction is abbreviated as “sub scanning corresponding direction”.

  As shown in FIG. 2 as an example, the optical scanning device 2010A includes a light source 2200A, a pre-deflector optical system A, a polygon mirror 2104A, a scanning optical system A, and a scanning control device A (not shown). The light source 2200A and the pre-deflector optical system A constitute an illumination system in the optical scanning device 2010A.

  The optical scanning device 2010B has the same configuration as the optical scanning device 2010A. As shown in FIG. 3 as an example, the light source 2200B, the pre-deflector optical system B, the polygon mirror 2104B, the scanning optical system B, and the scanning control. A device B (not shown) is provided. The light source 2200B and the pre-deflector optical system B constitute an illumination system in the optical scanning device 2010B.

  Each light source has a semiconductor laser (LD) and emits a light beam in a direction orthogonal to the Z-axis.

  Each polygon mirror has a four-stage mirror having a two-stage structure in the Z-axis direction, and each mirror serves as a deflection reflection surface. Here, the -Z side four-sided mirror is referred to as a first or lower four-sided mirror, and the + Z side four-sided mirror is referred to as a second or upper four-sided mirror. Each four-sided mirror rotates around an axis parallel to the Z-axis direction.

  As shown in FIG. 4 as an example, the pre-deflector optical system A includes a coupling lens 2201A, an aperture plate 2202A, a beam splitting member 2203A, and two cylindrical lenses (2204a and 2204b).

  As shown in FIG. 5 as an example, the pre-deflector optical system B includes a coupling lens 2201B, an aperture plate 2202B, a light beam splitting member 2203B, and two cylindrical lenses (2204c and 2204d).

  The coupling lens 2201A converts the light beam emitted from the light source 2200A into a substantially parallel light beam. The coupling lens 2201B makes the light beam emitted from the light source 2200B a substantially parallel light beam.

  The aperture plate 2202A has an aperture and shapes the light beam that has passed through the coupling lens 2201A. The aperture plate 2202B has an aperture and shapes the light beam that has passed through the coupling lens 2201B.

  Each light beam dividing member transmits a half of the incident light beam and reflects the remainder to the −Z side, and a mirror disposed in parallel with the half mirror surface on the optical path of the light beam reflected by the half mirror surface And has a surface. Therefore, each light beam splitting member separates the incident light beam with respect to the Z-axis direction and divides the light beam into two parallel light beams.

  The beam splitting member 2203A splits the beam that has passed through the opening of the aperture plate 2202A into two beams. The beam splitting member 2203B splits the beam that has passed through the opening of the aperture plate 2202B into two beams.

  Each cylindrical lens has an optical surface that converges the light beam in the sub-scanning corresponding direction (here, the same as the Z-axis direction).

  The cylindrical lens 2204a forms an image of the + Z side light beam (referred to as a light beam LBa) of the two light beams from the light beam splitting member 2203A in the vicinity of the second-stage deflection reflection surface of the polygon mirror 2104A in the Z-axis direction.

  The cylindrical lens 2204b forms an image of the −Z side light beam (referred to as the light beam LBb) of the two light beams from the light beam splitting member 2203A in the vicinity of the first-stage deflecting / reflecting surface of the polygon mirror 2104A in the Z-axis direction.

  The cylindrical lens 2204c forms an image of the + Z side light beam (referred to as a light beam LBc) of the two light beams from the light beam splitting member 2203B in the vicinity of the second-stage deflection reflection surface of the polygon mirror 2104B in the Z-axis direction.

  The cylindrical lens 2204d forms an image of the −Z side light beam (referred to as a light beam LBd) of the two light beams from the light beam splitting member 2203B in the vicinity of the first-stage deflecting / reflecting surface of the polygon mirror 2104B in the Z-axis direction.

  The two light beams from the pre-deflector optical system A are incident on the polygon mirror 2104A from a direction parallel to the plane orthogonal to the Z axis, and are deflected to the + X side. Here, the light beam LBa from the pre-deflector optical system A is deflected by the upper four-surface mirror of the polygon mirror 2104A, and the light beam LBb is deflected by the lower four-surface mirror of the polygon mirror 2104A. The two light beams deflected by the polygon mirror 2104A enter the scanning optical system A while maintaining a parallel state.

  The two light beams from the pre-deflector optical system B are incident on the polygon mirror 2104B from a direction parallel to the plane orthogonal to the Z axis, and are deflected to the + X side. Here, the light beam LBc from the pre-deflector optical system B is deflected by the upper four-surface mirror of the polygon mirror 2104B, and the light beam LBd is deflected by the lower four-surface mirror of the polygon mirror 2104B. The two light beams deflected by the polygon mirror 2104B enter the scanning optical system B while maintaining a parallel state.

  As shown in FIG. 6 as an example, the scanning optical system A has two scanning lenses (2105a, 2105b), a folding mirror 2106A, a separation mirror 2107b, and three light guide mirrors (2108a, 2108b, 2109b). ing.

  The separation mirror 2107b and the three light guide mirrors (2108a, 2108b, 2109b) are arranged between the polygon mirror 2104A and the folding mirror 2106A in the X-axis direction.

  As shown in FIG. 7 as an example, the scanning optical system B includes two scanning lenses (2105c, 2105d), a folding mirror 2106B, a separation mirror 2107d, and three light guide mirrors (2108c, 2108d, 2109d). ing.

  The separation mirror 2107d and the three light guide mirrors (2108c, 2108d, 2109d) are arranged between the polygon mirror 2104B and the folding mirror 2106B in the X-axis direction.

  In each scanning optical system, one scanning lens is provided for one light beam, and each scanning lens is made of resin, and the light beam deflected at a constant angular velocity by a polygon mirror is applied to the surface of the corresponding photosensitive drum at a constant speed. The light beam is converted into a light beam for scanning and condensed on the surface of the photosensitive drum.

  The folding mirror 2106A folds the light beam LBa that has passed through the scanning lens 2105a and the light beam LBb that has passed the scanning lens 2105b in a direction inclined with respect to both the X-axis direction and the Z-axis direction in the XZ plane.

  The angle formed between the incident light beam and the reflected light beam in the folding mirror 2106A is set to be 45 ° or less (see FIG. 8). Thereby, the dimension of the optical housing in the Z-axis direction can be reduced, that is, the thickness can be reduced.

  The light guide mirror 2108a is disposed on the optical path of the light beam LBa folded back by the folding mirror 2106A, and reflects the light beam LBa toward the photosensitive drum 2030a.

  Therefore, the light beam LBa deflected by the polygon mirror 2104A is applied to the photosensitive drum 2030a through the scanning lens 2105a, the folding mirror 2106A, and the light guide mirror 2108a.

  The separation mirror 2107b separates the optical path of the light beam LBb folded by the folding mirror 2106A from the optical path of the light beam LBa folded by the folding mirror 2106A.

  The light guide mirror 2108b is disposed on the optical path of the light beam LBb via the separation mirror 2107b, and the light guide mirror 2109b is disposed on the optical path of the light beam LBb via the light guide mirror 2108b.

  Therefore, the light beam LBb deflected by the polygon mirror 2104A is irradiated onto the photosensitive drum 2030b through the scanning lens 2105b, the folding mirror 2106A, the separation mirror 2107b, the light guide mirror 2108b, and the light guide mirror 2109b.

  In the scanning optical system A, the incident position of the light beam in the light guide mirror 2108a, the incident position of the light beam in the separation mirror 2107b, and the incident position of the light beam in the light guide mirror 2109b are the same in the Z-axis direction.

  The light guide mirror 2108c is disposed on the optical path of the light beam LBc folded back by the folding mirror 2106B, and reflects the light beam LBc toward the photosensitive drum 2030c.

  Therefore, the light beam LBc deflected by the polygon mirror 2104B is applied to the photosensitive drum 2030c through the scanning lens 2105c, the folding mirror 2106B, and the light guide mirror 2108c.

  The separation mirror 2107d separates the optical path of the light beam LBd folded by the folding mirror 2106B from the optical path of the light beam LBc folded by the folding mirror 2106B.

  The light guide mirror 2108d is disposed on the optical path of the light beam LBd via the separation mirror 2107d, and the light guide mirror 2109d is disposed on the optical path of the light beam LBd via the light guide mirror 2108d.

  Therefore, the light beam LBd deflected by the polygon mirror 2104B is irradiated onto the photosensitive drum 2030d through the scanning lens 2105d, the folding mirror 2106B, the separation mirror 2107d, the light guide mirror 2108d, and the light guide mirror 2109d.

  In the scanning optical system B, the incident position of the light beam in the light guide mirror 2108c, the incident position of the light beam in the separation mirror 2107d, and the incident position of the light beam in the light guide mirror 2109d are the same in the Z-axis direction.

  The light spot on each photosensitive drum moves in the longitudinal direction of the photosensitive drum as the corresponding polygon mirror rotates. The moving direction of the light spot on each photosensitive drum is the “main scanning direction”, and the direction along the rotational direction of the photosensitive drum is the “sub-scanning direction”.

  In each scanning optical system, the folding mirror is shared by two stations.

  One light guide mirror is disposed on the optical path of the light beam LBa that is folded by the folding mirror 2106A and travels toward the photosensitive drum 2030a, and two light guide mirrors are disposed on the optical path of the light beam LBb that travels toward the photosensitive drum 2030b. Has been placed.

  One light guide mirror is disposed on the optical path of the light beam LBc that is folded by the folding mirror 2106B and travels toward the photosensitive drum 2030c, and two light guide mirrors are disposed on the optical path of the light beam LBd that travels toward the photosensitive drum 2030d. Has been placed.

  The cylindrical lens 2204a and the cylindrical lens 2204b are arranged in the Z-axis direction, the optical axis direction, and the optical axis so that the optical performance (beam spot diameter, beam spot position, etc.) on the surface of the corresponding photosensitive drum is the designed optical performance. The surrounding mounting posture is adjusted, and as an example, as shown in FIG. 9, they are integrated via an intermediate member. The end surface on the + Z side of the cylindrical lens 2204a is bonded and fixed to a receiving portion provided on the upper cover of the optical housing 2300A. A specific numerical example is shown in FIG.

  The scanning lens 2105a and the scanning lens 2105b are lenses having the same shape, and are stacked in two steps in the Z-axis direction and bonded to each other. The two scanning lenses may be integrally formed. The + Z side end surface of the scanning lens 2105a is adhered and fixed to a mounting surface provided on the upper lid of the optical housing 2300A as shown in FIG. 9 as an example. Specific numerical examples are shown in FIG.

  As an example, the cylindrical lens 2204c and the cylindrical lens 2204d are adjusted in the Z-axis direction, the optical axis direction, and the mounting posture around the optical axis so that the optical performance on the surface of the corresponding photosensitive drum becomes the designed optical performance. As shown in FIG. 12, they are integrated via an intermediate member. The end surface on the + Z side of the cylindrical lens 2204c is bonded and fixed to a receiving portion provided on the upper cover of the optical housing 2300B.

  The scanning lens 2105c and the scanning lens 2105d are lenses having the same shape, and are stacked in two steps in the Z-axis direction and bonded to each other. The two scanning lenses may be integrally formed. Then, the + Z side end surface of the scanning lens 2105c is bonded and fixed to a mounting surface provided on the upper lid of the optical housing 2300B as shown in FIG. 12 as an example.

  In each optical scanning device, the receiving portion may be integrally formed with the optical housing, or may be attached to the optical housing as a separate member by a method such as adhesion. In addition, the shape of the receiving portion is a “convex shape” with respect to the inner surface of the optical housing, but may be a “concave shape”.

  By the way, in the optical scanning device 2010A, for example, when the temperature inside the device rises with operation, each scanning lens thermally expands, and the optical axis position (hereinafter referred to as “optical axis height”) in the Z-axis direction changes. To do. In particular, the change of the optical axis height in the scanning lens 2105b which is far from the mounting surface is large. If the optical axis height of the scanning lens changes in this way, the position of the light spot on the surface of the photosensitive drum changes with respect to the sub-scanning direction, which is not preferable.

  In the present embodiment, in order to avoid this, the receiving portion of the optical housing and the Z axis of the intermediate member are arranged so that the optical axis heights of the cylindrical lens and the scanning lens corresponding thereto change in the same direction and with the same size. The direction dimension (height) and the material of the intermediate member are set. Here, since the optical axis height of the scanning lens 2105b changes in the −Z direction due to thermal expansion, at least one of the receiving portion and the intermediate member is also changed so that the optical axis height of the cylindrical lens 2204b also changes in the −Z direction. The height and material are set.

For example, when the material of each scanning lens is a cycloolefin resin (linear expansion coefficient: 6 × 10 ⁻⁵ / ° C.) and the dimension in the Z-axis direction is 10 mm, when the ambient temperature rises by 20 ° C., the scanning lens The change amount of the optical axis height in 2105a is 5 [mm] × 6 × 10 ⁻⁵ [/ ° C.] × 20 [° C.] = 6.0 [μm]. Further, the change amount of the optical axis height in the scanning lens 2105b is 15 [mm] × 6 × 10 ⁻⁵ [1 / ° C.] × 20 [° C.] = 18.0 [μm]. At this time, if the magnification of the scanning optical system A in the sub-scanning corresponding direction is five times, the position of the light spot on the surface of the photosensitive drum 2030a changes by 30 μm in the sub-scanning direction, and the light spot on the surface of the photosensitive drum 2030b. The position changes by 90 μm in the sub-scanning direction.

Therefore, the material of the receiving part is ABS resin (linear expansion coefficient: 13 × 10 ⁻⁵ / ° C.), the dimension of the receiving part in the Z-axis direction is 2 mm, and the material of the intermediate member is polypropylene resin (linear expansion coefficient: 13 × 10 ⁻⁵ / ° C.), and the dimension of the intermediate member in the Z-axis direction was 4 mm. The material of each cylindrical lens is glass (linear expansion coefficient: 1 × 10 ⁻⁵ / ° C.), and the dimension of each cylindrical lens in the Z-axis direction is 6 mm.

In this case, the change amount of the optical axis height in the cylindrical lens 2204a is (2 [mm] × 13 × 10 ⁻⁵ [/ ° C.] + 3 [mm] × 1 × 10 ⁻⁵ [/ ° C.]) × 20 [° C. ] = 5.8 [μm], and the change amount of the optical axis height in the cylindrical lens 2204b is (2 [mm] × 13 × 10 ⁻⁵ [/ ° C.] + 6 [mm] × 1 × 10 ⁻⁵ [/ [° C.] + 4 [mm] × 13 × 10 ⁻⁵ [/ ° C.] + 3 [mm] × 1 × 10 ⁻⁵ [/ ° C.)) × 20 [° C.] = 17.4 [μm].

  The difference between the change amount of the optical axis height in the scanning lens 2105a and the change amount of the optical axis height in the cylindrical lens 2204a is 0.2 μm, and the change amount of the optical axis height in the scanning lens 2105b and the optical axis in the cylindrical lens 2204b. The difference in the amount of change in height is 0.6 μm. As described above, the difference between the change amount of the optical axis height in the scanning lens and the change amount of the optical axis height in the corresponding cylindrical lens can be reduced to a level that can be regarded as substantially zero.

  Each folding mirror is provided with an inclination adjusting mechanism for correcting the inclination of the scanning line on the surface of the photosensitive drum, and a push-in mechanism for correcting the bending of the scanning line (see Japanese Patent Application Laid-Open No. 2009-014832). ing. Hereinafter, when it is not necessary to distinguish between the folding mirror 2106A and the folding mirror 2106B, they are collectively referred to as “folding mirror 2106”.

  As shown in FIG. 13 as an example, the folding mirror 2106 is held by a holder 301 having a U-shaped cross-sectional shape.

  The tilt adjustment mechanism is attached to one end portion in the longitudinal direction of the folding mirror 2106. The tilt adjusting mechanism includes a tilt adjusting pulse motor 315, a motor holder 316, a tilt adjusting adjuster (not shown), and the like. The motor holder 316 is fixed to the optical housing. The tilt adjustment adjuster is screwed to the threaded portion of the rotation shaft of the tilt adjusting pulse motor 315, and the top thereof is in contact with the mirror surface of one side end of the folding mirror 2106. Therefore, the tilt of the folding mirror 2106 can be adjusted by rotating the tilt adjusting pulse motor 315.

  The pushing mechanism is attached to the center of the back surface of the holder 301. The pushing mechanism includes a bending adjustment pulse motor 325, a motor holder 326, a bending adjustment adjuster (not shown), and the like. The motor holder 326 is fixed to the optical housing. The bend adjustment adjuster is screwed to the screw portion of the rotating shaft of the bend adjustment pulse motor 325, and the top portion thereof is in contact with the back surface of the central portion in the longitudinal direction of the folding mirror 2106. Therefore, the pushing amount of the folding mirror 2106 can be adjusted by rotating the bending adjustment pulse motor 325.

  The tilt adjusting pulse motor 315 and the bending adjusting pulse motor 325 in the folding mirror 2106A are driven and controlled by the scanning control device A. The tilt adjusting pulse motor 315 and the bending adjusting pulse motor 325 in the folding mirror 2106B are driven and controlled by the scanning control device B.

  In each optical scanning device, the polygon mirror is arranged on the −X side, and the two light beams from the deflector optical system are deflected to the + X side (see FIG. 14). That is, in the optical scanning device 2010A and the optical scanning device 2010B, the positional relationship between the polygon mirror and the folding mirror is the same. In this case, in each optical scanning device, even if the temperature in the optical housing rises due to the heat generation of the polygon mirror and the curvature and assembly posture of the folding mirror change, scanning on the four photosensitive drums. Since the direction of change in line bending is the same, the occurrence of color misregistration in the output image can be reduced.

  Further, there is a difference between the number of light guide mirrors arranged on the optical path of the light beam LBa folded by the folding mirror 2106A and the number of light guide mirrors arranged on the optical path of the light beam LBb folded by the folding mirror 2106A. It is set to be an odd number. In this case, the direction of change in the scanning line curve on the photosensitive drum 2030a and the direction of change in the scanning line curve on the photosensitive drum 2030b can be made the same.

  Similarly, the difference between the number of light guide mirrors arranged on the optical path of the light beam LBc folded by the folding mirror 2106B and the number of light guide mirrors arranged on the optical path of the light beam LBd folded by the folding mirror 2106B. Is set to be an odd number. In this case, the direction of change of the scanning line curve on the photosensitive drum 2030c and the direction of change of the scanning line curve on the photosensitive drum 2030d can be made the same.

  In each optical scanning device, one folding mirror is shared by two stations, and a separation mirror and a plurality of light guiding mirrors are disposed between the polygon mirror and the folding mirror in the X-axis direction. . Thereby, the dimension regarding the X-axis direction of each optical scanning device can be made small.

  By the way, when the light beam incident on the polygon mirror is deflected in a direction inclined with respect to the plane orthogonal to the Z axis, optical characteristics (imaging performance, light spot shape, scanning line shape, In order to properly adjust the magnification error, the length of the scanning line, etc., each station requires two or more scanning lenses.

  On the other hand, in this embodiment, the two light beams incident on each polygon mirror are both deflected in a direction parallel to the plane orthogonal to the Z axis. In this case, appropriate optical characteristics can be obtained on the surface to be scanned even if there is only one scanning lens at each station.

  In this case, as shown in FIG. 15 as an example, in the optical scanning device A, the light beam LBa deflected by the polygon mirror 2104A is incident on the scanning lens 2105a as a divergent light beam in the Z-axis direction and scanned as a convergent light beam. The light is emitted from the lens 2105a. That is, the width in the Z-axis direction of the light beam LBa deflected by the polygon mirror 2104A and directed to the photosensitive drum 2030a is maximized by the scanning lens 2105a. Accordingly, the distance (reference numeral H in FIG. 15) between the light beam LBa from the folding mirror 2106A toward the light guide mirror 2108a and the separation mirror 2107b is widened, and the incident position of the light beam on the light guide mirror 2108a and the separation mirror 2107b in the Z-axis direction. The incident position of the light beam in can be made the same. As a result, the dimension of the optical scanning device A in the Z-axis direction can be reduced, that is, the thickness can be reduced. Similarly, the optical scanning device B can be thinned.

  By the way, due to manufacturing errors of the scanning lens and various mirrors and assembly errors of the respective optical elements with respect to the optical housing, scanning line abnormalities such as scanning line bending and scanning line inclination occur on the surface to be scanned. When this scanning line abnormality occurs, a color shift occurs in the output image.

  Here, correction of the bending of the scanning line will be described. For easy understanding, it is assumed that the inclination of the scanning line is 0 in all the photosensitive drums. Further, the scan line curve at the photoconductor drum 2030a is "scan line curve K", the scan line curve at the photoconductor drum 2030b is "scan line curve M", and the scan line curve at the photoconductor drum 2030c is " The scanning line curve C "and the scanning line curve on the photosensitive drum 2030d are called" scanning line curve Y ".

1. When the scanning line bend K is +40 μm (upward convex), the scanning line bend M is +40 μm (upward convex), the scanning line bend C is −20 μm (downward convex), and the scanning line bend Y is −20 μm (downward convex) (FIG. 16). (See (A) to FIG. 16D).

  At this time, the color shift in the output image is +40 − (− 20) = 60 μm.

  In this case, since the scanning line bend K and the scanning line bend M have the same sign and size, the bending adjustment adjuster in the pushing mechanism of the folding mirror 2106A is moved in the pushing direction, and the reflecting surface side of the folding mirror 2106A is convex. By deforming into the shape, the scanning line bend K and the scanning line bend M can both be substantially zero (see FIGS. 17A and 17B).

  Similarly, since the scanning line bend C and the scanning line bend Y have the same sign and size, the bending adjustment adjuster in the push-in mechanism of the folding mirror 2106B is moved in the pulling direction so that the reflecting surface side of the folding mirror 2106A is concave. By deforming into the shape, the scanning line bend C and the scanning line bend Y can both be substantially zero (see FIGS. 17C and 17D).

  As a result, the color shift of 60 μm that occurs at the center in the main scanning direction before correction can be reduced to zero.

2. When the scan line curve K is +40 μm (upward convex), the scan line curve M is +20 μm (upward convex), the scan line curve C is 0 μm (straight line), and the scan line curve Y is −40 μm (downward convex) (FIG. 18A). ) To FIG. 18D).

  At this time, the color shift in the output image is +40 − (− 40) = 80 μm.

  In this case, since the scanning line bend K and the scanning line bend M have the same sign but different sizes, the folding mirror 2106A is pushed so that the scan line bend K is +10 μm and the scan line bend M is −10 μm. The bending adjustment adjuster in the mechanism is moved in the pushing direction (see FIGS. 19A and 19B). That is, the scanning line curve K and the scanning line curve M are changed in the same direction (-direction) by the same amount (30 μm).

  Similarly, since the scanning line bend C and the scanning line bend Y have different sizes, the bend adjustment adjuster in the push-in mechanism of the folding mirror 2106B is adjusted so that the scan line bend C is +20 μm and the scan line bend Y is −20 μm. It is moved in the pulling direction (see FIGS. 19C and 19D). That is, the scanning line curve C and the scanning line curve Y are changed in the same direction (+ direction) by the same amount (20 μm).

  Thereby, the deviation of the bending of the four scanning lines can be set to +20 − (− 20) = 40 μm, and the color shift of 80 μm generated in the central portion in the main scanning direction before correction is reduced to 40 μm. (See FIG. 20A).

  Further, the color shift can be set to 20 μm by shifting the writing start timing so that the color shift is minimized (see FIG. 20B).

3. When the scanning line bend K is +50 μm (upward convex), the scanning line bend M is −10 μm (downward convex), the scanning line bend C is +30 μm (upward convex), and the scanning line bend Y is −50 μm (downward convex) (FIG. 21). (See (A) to FIG. 21D).

  At this time, the color shift in the output image is +50 − (− 50) = 100 μm.

  In this case, since the scanning line bending K and the scanning line bending M have different signs and sizes, the bending adjustment in the push-in mechanism of the folding mirror 2106A is performed so that the scanning line bending K is +30 μm and the scanning line bending M is −30 μm. The adjuster is moved in the pushing direction (see FIGS. 22A and 22B). That is, the scanning line bend K and the scanning line bend M are changed in the same direction (− direction) by the same amount (20 μm).

  Similarly, since the scanning line bending C and the scanning line bending Y have different signs and sizes, the bending adjustment in the push-in mechanism of the folding mirror 2106B is performed so that the scanning line bending C is +40 μm and the scanning line bending Y is −40 μm. The adjuster is moved in the pulling direction (see FIGS. 22C and 22D). That is, the scanning line curve C and the scanning line curve Y are changed in the same direction (positive direction) by the same amount (10 μm).

  Thereby, the deviation of the bending of the four scanning lines can be set to +40 − (− 40) = 80 μm, and the 100 μm color shift generated in the central portion in the main scanning direction before correction is reduced to 80 μm. (See FIG. 23A).

  Further, by shifting the writing start timing so that the color shift is minimized, the color shift can be 40 μm (see FIG. 23B).

  Next, correction of the inclination of the scanning line will be described. In order to make the explanation easy to understand, it is assumed that the curve of the scanning line is 0 in all the photosensitive drums. The inclination of the scanning line on the photosensitive drum 2030a is “scanning line inclination K”, the inclination of the scanning line on the photosensitive drum 2030b is “scanning line inclination M”, and the inclination of the scanning line on the photosensitive drum 2030c is “ The scanning line inclination C ”and the inclination of the scanning line on the photosensitive drum 2030d are referred to as“ scanning line inclination Y ”.

1. When the scanning line inclination K is +40 μm (upward to the right), the scanning line inclination M is +40 μm (upward to the right), the scanning line inclination C is −20 μm (downward to the right), and the scanning line inclination Y is −20 μm (downward to the right) (FIG. 24). (See (A) to FIG. 24 (D)).

  At this time, the color shift occurring at the right end of the output image is +40 − (− 20) = 60 μm.

  In this case, since the scan line tilt K and the scan line tilt M have the same sign and size, the scan line tilt K and the scan line are moved by moving the tilt adjustment adjuster in the tilt adjustment mechanism of the folding mirror 2106A in the pushing direction. Both of the inclinations M can be substantially 0 (see FIGS. 25A and 25B).

  Similarly, since the scan line tilt C and the scan line tilt Y have the same sign and size, the scan line tilt C and the scan line are moved by moving the tilt adjustment adjuster in the tilt adjustment mechanism of the folding mirror 2106B in the pulling direction. Both of the inclinations Y can be set to substantially 0 (see FIGS. 25C and 25D).

  Thereby, the deviation of the inclinations of the four scanning lines can be set to 0, and the 60 μm color shift generated at the right end portion of the output image before correction can be set to 0.

2. When the scanning line inclination K is +40 μm (upward to the right), the scanning line inclination M is +20 μm (upward to the right), the scanning line inclination C is 0 μm (horizontal), and the scanning line inclination Y is −40 μm (downward to the right) (FIG. 26A ) To FIG. 26 (D)).

  At this time, the color shift occurring at the right end of the output image is +40 − (− 40) = 80 μm.

  In this case, since the scanning line inclination K and the scanning line inclination M have the same sign but different sizes, the inclination of the folding mirror 2106A so that the scanning line inclination K becomes +10 μm and the scanning line inclination M becomes −10 μm. The tilt adjustment adjuster in the adjustment mechanism is moved in the pushing direction (see FIGS. 27A and 27B). That is, the scanning line inclination K and the scanning line inclination M are changed in the same direction (downward to the right) by the same amount (30 μm).

  Similarly, since the scanning line inclination C and the scanning line inclination Y are different in size, the inclination adjustment adjuster in the inclination adjustment mechanism of the folding mirror 2106B so that the scanning line inclination C is +20 μm and the scanning line inclination Y is −20 μm. Is moved in the pulling direction (see FIGS. 27C and 27D). That is, the scanning line inclination C and the scanning line inclination Y are changed in the same direction (upward to the right) by the same amount (20 μm).

  Thereby, the deviation of the inclination of the four scanning lines can be set to +20 − (− 20) = 40 μm, and the color shift of 80 μm generated at the right end portion of the output image before correction can be reduced to 40 μm. This is possible (see FIG. 28A).

  Further, the color shift can be set to 20 μm by shifting the writing start timing so that the color shift is minimized (see FIG. 28B).

  As described above, the optical scanning device 2010A according to the present embodiment includes the light source 2200A, the pre-deflector optical system A, the polygon mirror 2104A, the scanning optical system A, and the like. The scanning optical system A includes two scanning lenses (2105a and 2105b) individually corresponding to the two light beams, one folding mirror 2106A for folding the two light beams through the two scanning lenses, and the light beam LBb. Are separated from the optical path of the light beam LBa, a light guide mirror 2108a for guiding the light beam LBa to the photosensitive drum 2030a, and a light guide mirror (2108b, 2109b) for guiding the light beam LBb to the photosensitive drum 2030b. ing.

  The incident position of the light beam LBb on the separation mirror 2107b, the incident position of the light beam LBb on the light guide mirror 2109b, and the incident position of the light beam LBa on the light guide mirror 2108a are the same in the Z-axis direction. In this case, the thickness can be reduced without increasing the cost.

  The optical scanning device 2010B according to the present embodiment includes the light source 2200B, the pre-deflector optical system B, the polygon mirror 2104B, the scanning optical system B, and the like. The scanning optical system B includes two scanning lenses (2105c and 2105d) individually corresponding to the two light beams, one folding mirror 2106B for folding the two light beams through the two scanning lenses, and the light beam LBd. A separation mirror 2107d for separating the optical path of the light beam LBc from the optical path of the light beam LBc, a light guide mirror 2108c for guiding the light beam LBc to the photosensitive drum 2030c, and a light guide mirror (2108d, 2109d) for guiding the light beam LBd to the photosensitive drum 2030d. ing.

  The incident position of the light beam LBd on the separation mirror 2107d, the incident position of the light beam LBd on the light guide mirror 2109d, and the incident position of the light beam LBc on the light guide mirror 2108c are the same in the Z-axis direction. In this case, the thickness can be reduced without increasing the cost.

  In each optical scanning device, the folding mirror is provided with an inclination adjusting mechanism for correcting the inclination of the scanning line on the surface of the photosensitive drum and a pushing mechanism for correcting the bending of the scanning line. As a result, the adjustment process can be simplified and color misregistration in the output image can be reduced.

  Further, in each optical scanning device, the two scanning lenses are integrated, the + Z side end face is fixed to the optical housing, and the two cylindrical lenses are integrated via an intermediate member, and the + Z side end face is attached to the optical housing. It is fixed. In this case, when the ambient temperature rises, the change in the optical axis height of the scanning lens in the Z-axis direction and the change in the optical axis height of the cylindrical lens in the Z-axis direction can be substantially matched. It becomes possible to suppress a change in the position of the light spot on the surface of the photosensitive drum in the sub-scanning direction.

  In each optical scanning device, the positional relationship between the polygon mirror and the folding mirror is the same. In this case, even if the optical housing is deformed due to the heat generated by the polygon mirror and the curvature and the mounting posture of the folding mirror are changed, the difference in scanning line bending between the photosensitive drums is small. Color shift can be reduced.

  The color printer 2000 according to the present embodiment includes the optical scanning device 2010A and the optical scanning device 2010B. As a result, the size can be reduced without increasing the cost.

  The mechanism for correcting the inclination of the scanning line on the surface of the photosensitive drum and the mechanism for correcting the bending of the scanning line are not limited to the above embodiment.

  In the above embodiment, a case is described in which the folding mirror is provided with an inclination adjusting mechanism for correcting the inclination of the scanning line on the surface of the photosensitive drum and a pushing mechanism for correcting the bending of the scanning line. However, the present invention is not limited to this, and either the tilt adjustment mechanism or the push-in mechanism may be provided in the folding mirror. For example, only the pushing mechanism may be provided on the folding mirror, and the tilt adjusting mechanism may be provided on the light guide mirror. Alternatively, only the push-in mechanism may be provided on the folding mirror, and a mechanism for tilting the entire optical scanning device may be provided as the tilt adjustment mechanism.

  In the above embodiment, the light guide mirror 2108b of the scanning optical system A may be omitted as shown in FIG. 29 as an example. Similarly, the light guide mirror 2108d of the scanning optical system B may be omitted. In this case, all the three mirrors excluding the folding mirror can be set to the same position (height) in the Z-axis direction, so that it is possible to further reduce the thickness.

  Further, in the above embodiment, as shown in FIGS. 30 and 31 as an example, the scanning optical system A and the scanning optical system B are arranged to face each other with respect to the X-axis direction with one polygon mirror 2104 interposed therebetween, It may be accommodated in one optical housing. In this optical scanning device 2010, the incident position of the light beam LBb on the separation mirror 2107b, the incident position of the light beam LBb on the light guide mirror 2109b, the incident position of the light beam LBa on the light guide mirror 2108a, the incident position of the light beam LBd on the separation mirror 2107d, The incident position of the light beam LBd in the optical mirror 2109d and the incident position of the light beam LBc in the light guide mirror 2108c are the same in the Z-axis direction. Also in this case, the thickness can be reduced without increasing the cost.

  Moreover, in the said embodiment, each light source may have one light emission part, and may have a some light emission part. When each light source has a plurality of light emitting portions, so-called “multi-beam scanning” is possible in which one photosensitive drum is simultaneously scanned with a plurality of light spots.

  In the above embodiment, the case where the optical scanning device 2010 is used in a printer has been described. However, the present invention is also suitable for an image forming apparatus other than a printer, for example, a copier, a facsimile, or a multifunction machine in which these are integrated. .

  As described above, the optical scanning device of the present invention is suitable for reducing the thickness without increasing the cost. Further, the image forming apparatus according to the present invention is suitable for downsizing without increasing the cost.

  315: Pulse motor for tilt adjustment, 325: Pulse motor for curve adjustment, 2000: Color printer (image forming apparatus), 2010 ... Optical scanning device, 2010A ... Optical scanning device, 2010B ... Optical scanning device, 2030a-2030d ... Photoconductor Drum (image carrier), 2104 ... polygon mirror (optical deflector), 2104A ... polygon mirror (optical deflector), 2104B ... polygon mirror (optical deflector), 2105a to 2105d ... scanning lens, 2106A, 2106B ... folding mirror 2107b, 2107d: separation mirror, 2108a, 2108b, 2108d, 2109b, 2109d ... light guide mirror, 2200A, 2200B ... light source, 2300A, 2300B ... optical housing.

Japanese Patent No. 4447450 JP 2007-199407 A JP 2003-270570 A JP 2003-295079 A JP 2004-255726 A Japanese Patent No. 4445234

Claims (17)

An optical scanning device that individually scans a plurality of scanned surfaces with light in a first direction,
An illumination system that emits a plurality of light beams including a first light beam and a second light beam;
An optical deflector for deflecting a plurality of light beams from the illumination system;
A scanning optical system that individually collects the plurality of light beams deflected by the optical deflector onto a corresponding scanned surface;
The scanning optical system includes a separation mirror that separates an optical path of the first light flux from an optical path of another light flux, and a light guide mirror that guides the second light flux to a corresponding scanned surface. The optical scanning device characterized in that the incident position of the first light beam and the incident position of the second light beam in the light guide mirror are the same in a second direction orthogonal to the first direction.   The scanning optical system includes a folding mirror that turns back the optical paths of the plurality of light beams deflected by the optical deflector, and the separation mirror is disposed on the optical path of the first light flux that is turned back by the folding mirror. 2. The optical scanning device according to claim 1, wherein the light guide mirror is disposed on an optical path of the second light flux folded back by the folding mirror. 3.   The optical scanning device according to claim 2, wherein the folding mirror folds the optical paths of the plurality of light beams in a direction inclined with respect to both the first direction and the second direction.   The optical scanning device according to claim 2, wherein the scanning optical system includes a plurality of scanning lenses, and one scanning lens corresponds to one light beam in the plurality of light beams.   5. The optical scanning device according to claim 4, wherein the plurality of scanning lenses are arranged on an optical path of a corresponding light beam between the optical deflector and the folding mirror.   6. The optical scanning device according to claim 4, wherein each of the plurality of scanning lenses has an optical surface for converging a light beam at least in the second direction. The plurality of scanning lenses are integrated, and one end face of the second direction is fixed to the optical housing,
The illumination system includes a plurality of optical elements having an optical surface for converging a light beam at least in the second direction, and the plurality of optical elements are integrated so that the end surface on the one side in the second direction is The optical scanning device according to claim 4, wherein the optical scanning device is fixed to the optical housing.   The optical scanning device according to claim 7, wherein the plurality of optical elements are integrated via an intermediate member.   9. The scanning optical system according to claim 1, further comprising an even number of light guide mirrors for guiding the first light beam separated by the separation mirror to a corresponding scanned surface. The optical scanning device described.   With respect to a direction orthogonal to both the first direction and the second direction, an even number of light guide mirrors for guiding the first light beam to the corresponding scanned surface, and the second light beam The optical scanning device according to claim 9, wherein any of the light guide mirrors guided to the scanning surface is disposed between the optical deflector and the folding mirror.   The incident position of the first light beam in one light guide mirror of the even number of light guide mirrors that guide the first light beam to the corresponding scanned surface is the first position in the separation mirror with respect to the second direction. The optical scanning device according to claim 9, wherein the position is the same as the incident position of the light beam. The optical deflector has a rotating polygon mirror,
The first light beam and the second light beam are incident on the optical deflector from a direction parallel to a plane orthogonal to a rotation axis of the rotary polygon mirror. The optical scanning device according to Item. The plurality of light beams include a third light beam and a fourth light beam,
A second scanning optical system facing the scanning optical system across the optical deflector with respect to a direction orthogonal to both the first direction and the second direction;
The second scanning optical system has a separation mirror that separates the optical path of the third light flux from the optical path of another light flux, and a light guide mirror that guides the fourth light flux to a corresponding scanned surface,
The incident position of the first light beam in the separation mirror that separates the optical path of the first light beam from the optical path of the other light beam, and the second light beam in the light guide mirror that guides the second light beam to the corresponding scanned surface. The incident position of the third light beam in the separation mirror that separates the optical path of the third light beam from the optical path of the other light beam, and the light guide mirror that guides the fourth light beam to the corresponding scanned surface. The optical scanning device according to claim 1, wherein an incident position of the fourth light beam is the same with respect to the second direction. The optical deflector has a rotating polygon mirror,
The optical scanning device according to claim 13, wherein the third light beam and the fourth light beam are incident on the optical deflector from a direction parallel to a plane orthogonal to a rotation axis of the rotary polygon mirror. . A plurality of image carriers;
An image forming apparatus comprising: at least one optical scanning device according to any one of claims 1 to 12 that scans the plurality of image carriers with a light beam modulated in accordance with image data. The at least one optical scanning device is a plurality of optical scanning devices;
16. The image forming apparatus according to claim 15, wherein the plurality of optical scanning devices have the same positional relationship between the optical deflector and the folding mirror. A plurality of image carriers;
15. An image forming apparatus comprising: the optical scanning device according to claim 13 or 14, wherein the plurality of image carriers are scanned with a light beam modulated in accordance with image data.

Images