JP4915839B2 - Optical scanning apparatus and image forming apparatus - Google Patents

Description

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

  Conventionally, as an image forming apparatus that forms a multicolor image using the Carlson process, for example, latent images corresponding to black, yellow, magenta, and cyan component images are formed on the surfaces of four photosensitive drums, respectively. Image formation in which a multicolor image is formed by superimposing and fixing toner images obtained by visualizing these latent images with corresponding color toners onto a sheet as a recording medium via a transfer member An apparatus is known (see, for example, Patent Document 1). This type of image forming apparatus is often used for simple printing as an on-demand printing system, and demands for improved productivity and higher image quality are increasing.

  However, if the processing speed is increased to improve productivity, the amount of heat generated from the operating part of the apparatus increases, which is caused by temperature changes and temperature spots inside the apparatus between the scanning optical systems of each photosensitive drum. There may be a disadvantage that the positional deviation with time occurs, and the overlay accuracy of the toner image is lowered.

  Therefore, a method for preventing image quality deterioration by detecting a pattern corresponding to each color formed on the transfer body and correcting the transfer position of the toner image for each color based on the detection result has been proposed. (For example, refer to Patent Document 2 and Patent Document 3). However, the above method needs to be performed by interrupting normal processing, for example, between jobs. If correction is frequently performed by this method, the operation rate of the apparatus is lowered and productivity is lowered.

  Recently, multi-beam scanning devices are becoming mainstream as a means for improving the productivity of image forming apparatuses by increasing the processing speed of the optical scanning device (see, for example, Patent Document 4). The multi-beam scanning device can improve the scanning speed without increasing the rotational speed of a deflecting means such as a polygon mirror by scanning the surface to be scanned with a plurality of beams at once.

JP 2002-341273 A JP 2001-253113 A JP 2003-154703 A JP 2003- 211728 A

  SUMMARY OF THE INVENTION The present invention has been made under such circumstances, and a first object thereof is to provide an optical scanning device capable of reducing the positional deviation of a beam spot on a surface to be scanned in a short time during a job. It is in.

  A second object of the present invention is to provide an image forming apparatus capable of improving image quality without causing a decrease in productivity.

The invention according to claim 1 is an optical scanning device that scans a surface to be scanned with light beams emitted from a plurality of light sources, and scans the surface to be scanned with a plurality of light beams in a main scanning direction . A scanning optical system; receiving a light beam scanned by the scanning optical system; and a width in the main scanning direction at both ends in the sub-scanning direction orthogonal to the main scanning direction and a central part in the sub-scanning direction A photodetector having a light-receiving surface whose difference from the width in the main scanning direction is larger than the width in the main scanning direction at both ends in the sub-scanning direction ; and sequentially driving the plurality of light sources for each scan. Accordingly, the light beams emitted from the plurality of light sources are sequentially incident on the photodetectors by comparing the detection times of the signals sequentially output from the photodetectors. The sub-scanning direction with respect to the photodetector An optical scanning device comprising a; position and processing device for detecting a.

The invention according to claim 2 is an optical scanning device that scans a surface to be scanned with light beams emitted from a plurality of light sources, and scans the surface to be scanned with a plurality of light beams in a main scanning direction. A scanning optical system; receiving a light beam scanned by the scanning optical system; and a width in the main scanning direction at both ends in the sub-scanning direction orthogonal to the main scanning direction and a central part in the sub-scanning direction A photodetector having a light receiving surface whose difference from the width in the main scanning direction is not more than the width in the main scanning direction at both ends in the sub scanning direction; and sequentially driving the plurality of light sources for each scanning. Accordingly, the light beams emitted from the plurality of light sources are sequentially incident on the photodetectors by comparing the detection times of the signals sequentially output from the photodetectors. Of the sub-scanning direction with respect to the photodetector An optical scanning device including a; processing unit and for detecting the location.

According to the optical scanning device of the first and second aspects, it is possible to reduce the beam spot position deviation on the surface to be scanned.

The optical scanning device according to claim 1 or 2, as the optical scanning apparatus according to claim 3, wherein the light receiving surface, and the end of the main scanning direction one-is orthogonal to the main scanning direction be able to.
4. The optical scanning device according to claim 1, wherein the shape of the light receiving surface passes through the center thereof and is parallel to the main scanning direction as in the optical scanning device according to claim 4. Can be line symmetrical.

In the optical scanning apparatus according to any one of claims 1-4, as an optical scanning apparatus according to claim 5, wherein the sub-scanning direction width of the light receiving surface, one scanning of the scanning surface it can be greater than the maximum write width of the sub-scanning direction for scanning at.

Each optical scanning device according to any one of claims 1 to 5 , wherein each beam spot of a light beam emitted from the plurality of light sources is the surface to be scanned as in the optical scanning device according to claim 6. it can be be formed at predetermined intervals in the sub-scanning direction above.

  In this case, as in the optical scanning device according to claim 7, the processing device can store detection times of signals sequentially output from the detector.

Each optical scanning device according to any one of claims 1 to 7 , wherein the processing device drives the light source at the same timing for each scanning as in the optical scanning device according to claim 8. It can be.

In the optical scanning apparatus according to any one of claims 1 to 7, as an optical scanning apparatus according to claim 9, wherein the processing unit, the main scanning direction of the light source to the light source for each one scanning It can be driven at a timing according to the arrangement position.

In the optical scanning device according to any one of claims 1 to 9, as an optical scanning apparatus according to claim 10, wherein the processing device, based on the detection time of the signals sequentially outputted from the detector Te, among the plurality of light sources, that the light beam from the light source in the middle relates the sub-scanning direction, and to correct such that the center position regarding the sub-scanning direction of the light receiving surface of the photodetector it can.

  Each optical scanning device of Claim 1-10 WHEREIN: As the optical scanning device of Claim 11, the said scanning optical system is the some optical element which shapes the light beam inject | emitted from these light sources, Deflection means for collectively deflecting the respective light beams emitted from the plurality of light sources, and the plurality of optical elements may be accommodated in a single housing.

  Each optical scanning device of Claims 1-11 WHEREIN: Like the optical scanning device of Claim 12, the said photodetector can be accommodated in the said housing.

  According to a thirteenth aspect of the present invention, an image that forms a multicolor image by superimposing and fixing a toner image formed on the basis of a latent image for each color obtained from information on the multicolor image on a recording medium. An optical scanning device according to any one of claims 1 to 12, a plurality of photosensitive members on which latent images corresponding to respective colors are respectively formed by the optical scanning device; A developing unit that visualizes the latent images formed on the surface to be scanned; and a transfer unit that superimposes and fixes the toner images of the respective colors visualized by the developing unit on the recording medium. An image forming apparatus.

According to this, without reducing the productivity, it is possible to improve the image quality.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a schematic configuration of a printer 10 as an image forming apparatus according to an embodiment.

  The printer 10 is a tandem type color printer that prints a multicolor image by superimposing and transferring, for example, black, yellow, magenta, and cyan toner images on plain paper (paper) using the Carlson process. is there. As shown in FIG. 1, the printer 10 includes an optical scanning device 100, four photosensitive drums 30A, 30B, 30C, and 30D, a transfer belt 40, a misregistration detection device 45, a paper feed tray 60, and a paper feed roller 54. A first registration roller pair 56, a second registration roller pair 52, a fixing roller 50, a paper discharge roller 58, a control device (not shown) for comprehensively controlling the respective parts, and a substantially rectangular parallelepiped housing for housing the components. 12 etc. are provided.

  The housing 12 is formed with a paper discharge tray 12a on which the printed paper is discharged on the upper surface, and the optical scanning device 100 is disposed below the paper discharge tray 12a.

  The optical scanning device 100 scans the photosensitive drum 30A with a light beam of a black image component modulated based on image information supplied from a host device (such as a personal computer), and cyan for the photosensitive drum 30B. The light beam of the image component is scanned, the light beam of the magenta image component is scanned on the photosensitive drum 30C, and the light beam of the yellow image component is scanned on the photosensitive drum 30D. The configuration of the optical scanning device 100 will be described later.

  The four photosensitive drums 30A, 30B, 30C, and 30D are cylindrical members each having a photosensitive layer having a property that becomes conductive when irradiated with a light beam. Below the scanning device 100 are arranged at equal intervals along the X-axis direction.

  The photosensitive drum 30A is disposed at the −X side end inside the housing 12 with the Y-axis direction as the longitudinal direction, and is rotated clockwise in FIG. 1 (the direction indicated by the arrow in FIG. 1) by a rotation mechanism (not shown). It is like that. In the vicinity thereof, a charging charger 32A is arranged at the 12 o'clock (upper) position in FIG. 1, a toner cartridge 33A is arranged at the 2 o'clock position, and a cleaning case 31A is arranged at the 10 o'clock position. .

  The charging charger 32A is arranged with a predetermined clearance with respect to the surface of the photosensitive drum 30A with the longitudinal direction as the Y-axis direction, and charges the surface of the photosensitive drum 30A with a predetermined voltage.

  The toner cartridge 33A includes a cartridge main body filled with black image component toner, a developing roller charged with a voltage having a polarity opposite to that of the photosensitive drum 30A, and the toner filled in the cartridge main body is passed through the developing roller. The toner is supplied to the surface of the photosensitive drum 30A.

  The cleaning case 31A includes a rectangular cleaning blade whose longitudinal direction is the Y-axis direction, and is arranged so that one end of the cleaning blade is in contact with the surface of the photosensitive drum 30A. The toner adsorbed on the surface of the photosensitive drum 30A is peeled off by the cleaning blade as the photosensitive drum 30A rotates, and is collected in the cleaning case 31A.

  The photosensitive drum 30B is arranged at a predetermined interval on the + X side of the photosensitive drum 30A, and is rotated clockwise (in the direction indicated by the arrow) in FIG. 1 by a rotating mechanism (not shown). A charging charger 32B, a toner cartridge 33B, and a cleaning case 31B are arranged around the photosensitive drum 30A in the same positional relationship as the above-described photosensitive drum 30A.

  The charging charger 32B is configured in the same manner as the above-described charging charger 32A, and charges the surface of the photosensitive drum 30B with a predetermined voltage.

  The toner cartridge 33B includes a cartridge main body filled with cyan image component toner, a developing roller charged with a voltage having a polarity opposite to that of the photosensitive drum 30B, and the toner filled in the cartridge main body is passed through the developing roller. The toner is supplied to the surface of the photosensitive drum 30B.

  The cleaning case 31B is configured similarly to the cleaning case 31A and functions in the same manner.

  The photosensitive drum 30C is arranged at a predetermined interval on the + X side of the photosensitive drum 30B, and is rotated clockwise (in the direction indicated by the arrow) in FIG. 1 via a rotation mechanism (not shown). Around the periphery, a charging charger 32C, a toner cartridge 33C, and a cleaning case 31C are arranged in the same positional relationship as the photosensitive drum 30A.

  The charging charger 32C is configured similarly to the above-described charging charger 32A, and charges the surface of the photosensitive drum 30C with a predetermined voltage.

  The toner cartridge 33C includes a cartridge main body filled with magenta image component toner, a developing roller charged with a voltage having a polarity opposite to that of the photosensitive drum 30C, and the toner filled in the cartridge main body via the developing roller. The toner is supplied to the surface of the photosensitive drum 30C.

  The cleaning case 31C is configured similarly to the cleaning case 31A and functions in the same manner.

  The photosensitive drum 30D is arranged at a predetermined interval on the + X side of the photosensitive drum 30C, and is rotated clockwise (in the direction indicated by the arrow) in FIG. 1 by a rotating mechanism (not shown). Around the periphery, a charging charger 32D, a toner cartridge 33D, and a cleaning case 31D are arranged in the same positional relationship as the above-described photosensitive drum 30A.

  The charging charger 32D is configured in the same manner as the charging charger 32A described above, and charges the surface of the photosensitive drum 30D with a predetermined voltage.

  The toner cartridge 33D includes a cartridge body filled with yellow image component toner, a developing roller charged with a voltage having a polarity opposite to that of the photosensitive drum 30D, and the toner filled in the cartridge body is passed through the developing roller. The toner is supplied to the surface of the photosensitive drum 30D.

  The cleaning case 31D is configured similarly to the cleaning case 31A and functions in the same manner.

  Hereinafter, the photosensitive drum 30A, the charging charger 32A, the toner cartridge 33A, and the cleaning case 31A are collectively referred to as a first station, and the photosensitive drum 30B, the charging charger 32B, the toner cartridge 33B, and the cleaning case 31B are collectively referred to as a second station, The photosensitive drum 30C, the charging charger 32C, the toner cartridge 33C, and the cleaning case 31C are collectively referred to as a third station, and the photosensitive drum 30D, the charging charger 32D, the toner cartridge 33D, and the cleaning case 31D are collectively referred to as a fourth station. .

  The transfer belt 40 is an endless annular member, a driven roller 40a disposed below the photosensitive drum 30A, a driven roller 40c disposed below the photosensitive drum 30D, and a position slightly lower than these driven rollers 40a and 40c. The upper end surface is wound around the driving roller 40b disposed in the contact roller 40b so as to be in contact with the lower end surfaces of the photosensitive drums 30A, 30B, 30C, and 30D. The drive roller 40b rotates counterclockwise (in the direction indicated by the arrow in FIG. 1) by rotating counterclockwise in FIG. A transfer charger 48 to which a voltage having a polarity opposite to that of the above-described charging chargers 32A, 32B, 32C, and 32D is applied is disposed near the + X side end of the transfer belt 40.

  The misregistration detection device 45 is arranged on the −X side of the transfer belt 40, and as can be understood by combining FIG. 1 and FIG. 2, which is a perspective view showing the optical scanning device 100 in the housing 12, An LED 42a that illuminates the side end, a photosensor 41a that receives the reflected light, an LED 42b that illuminates the center of the transfer belt 40, a photosensor 41b that receives the reflected light, and an −Y side end of the transfer belt 40 are illuminated. LED42c which performs and photosensor 41c which receives the reflected light are provided.

  Then, as shown in FIG. 2, the detection patterns of the three toner images formed along the Y-axis direction on the transfer belt 40 are illuminated by the LEDs 42a, 42b, and 42c, respectively, and the reflected light is photosensor 41a. , 41b, 41c, based on the time difference between detection signals obtained by receiving light respectively, the Y-axis direction resist and magnification, the X-axis direction resist and tilt, and the toner image pattern formed at the first station. It is detected as a relative positional deviation as a reference. The relative positional deviation from the first station is detected when the toner image formed at each station is overlapped with the toner image formed at the other station. This is because the optical scanning device 100 is controlled to overlap. Further, since the configuration of the positional deviation detection device 45 is disclosed in Japanese Patent No. 3644923 and is well known, detailed description thereof is omitted here.

  Returning to FIG. 1, the paper feed tray 60 is disposed below the transfer belt 40. The paper feed tray 60 is a substantially rectangular parallelepiped tray, and a plurality of sheets 61 to be printed are stacked and stored therein. A rectangular paper feed port is formed near the + X side end of the upper surface of the paper feed tray 60.

  The paper feed roller 54 takes out the paper 61 one by one from the paper feed tray 60 and guides it to a gap formed by the transfer belt 40 and the transfer charger 48 via a registration roller 56 composed of a pair of rotating rollers.

  The fixing roller 50 is composed of a pair of rotating rollers. The fixing roller 50 overheats and pressurizes the paper 61 and guides it to the paper discharge roller 58 via the registration roller 52.

  The paper discharge roller 58 includes a pair of rotating rollers, and sequentially stacks the derived paper 61 on the paper discharge tray 12a.

  Next, the configuration of the optical scanning device 100 will be described. 2 and 3, the optical scanning device 100 includes a polygon mirror 104, an fθ lens 105, a reflection mirror 106B, a reflection mirror 106A, and an fθ lens 105 that are sequentially arranged in the −X direction of the polygon mirror 104. , A toroidal lens 107B sequentially disposed in the −X direction of the reflection mirror 108B, the reflection mirror 108A, the toroidal lens 107A, and an fθ lens 305 disposed in the + X direction of the polygon mirror 104. , A reflection mirror 306C, a reflection mirror 306D, a reflection mirror 308C disposed below the fθ lens 305, a reflection mirror 308D sequentially disposed in the + X direction of the reflection mirror 308C, and a toroidal lens 307C. Furthermore, two optical systems of an incident optical system 200A that scans the first station and the second station and an incident optical system 200B that scans the third station and the fourth station are provided.

  As representatively shown in the incident optical system 200B of FIG. 2, the incident optical systems 200A and 200B include a light source unit 201, a light beam splitting prism 202, a set of liquid crystal elements 203A and 203B, a set of cylinder lenses 204A, 204B is provided.

  FIG. 4 shows the configuration of the light source unit 201 together with the light beam splitting prism 202. As shown in FIG. 4, the light source unit 201 includes a rectangular plate-like substrate 150 whose longitudinal direction is the x-axis direction, a laser array 152, a branch mirror 153, A coupling lens 154, a converging lens 156, and a light receiving element 157 are provided.

  4 and 5, the laser array 152 is a surface-emitting type semiconductor laser array in which light sources are arranged as secondary sources, and is centered on the y axis with respect to the substrate 150 (from the front of FIG. 5). It is fixed in a state where it is rotated by an angle γ in the clockwise direction. On the surface of the laser array 152 on the -y side, as shown in FIG. 5, 28 light emitting sources arranged in a matrix of 4 rows and 7 columns with d between rows and between columns show the polarization direction in the row direction, for example. It is formed in a state of being aligned. As a result, 28 lines are simultaneously scanned for each station by one scan. If the sub-scan magnification of the entire optical system is βs, the line pitch is p, and the number of columns of the matrix is n, the angle γ is expressed by the following equation (1).

  sinγ = (cosγ) / n = p / d · βs (1)

  Instead of fixing the laser array 152 in a state rotated by the rotation angle γ as described above, the row direction of the light emission source forms an angle γ with respect to the main scanning direction at the stage of the processing process of the laser array 152. In this manner, each light emitting source may be formed.

  Returning to FIG. 4, the branch mirror 153 is disposed on the −y side of the light source unit 201, transmits the light beam emitted from the laser array 152, and branches a part thereof in the + x direction. As described above, since the laser array 152 is rotated by the angle γ, the light beam has a P-polarized component and an S-polarized component with respect to the branch mirror 153. Here, the branching mirror 153 branches the P-polarized component of the light beam in the + x direction.

  The converging lens 156 condenses the light beam branched in the + x direction by the branch mirror 153 onto the light receiving element 157.

  The beam splitting prism 202 divides the light beam incident from the laser array 152 through the coupling lens 154 into two parts in the vertical direction and emits the light beam at a predetermined interval in the sub-scanning direction.

  Returning to FIG. 2, the liquid crystal elements 203 </ b> A and 203 </ b> B are arranged adjacent to the vertical direction of the exit surface of the light beam splitting prism 202, and the light beam is transmitted in the sub-scanning direction according to a voltage signal from an optical axis variable control circuit 415 described later. To deflect.

  The cylinder lenses 204A and 204B are arranged adjacent to each other in the vertical direction corresponding to each light beam divided into two by the light beam splitting prism 202, and one of them is attached so as to be rotatable around the optical axis. The focal line can be adjusted to be parallel. Then, each incident light beam is condensed on the polygon mirror 104. The cylinder lenses 204A and 204B have a positive curvature at least in the sub-scanning direction, and once the beam is converged on the reflection surface of the polygon mirror 104, the cylinder lenses 204A and 204B are deflected by the toroidal lenses 107A to 107D described later. A surface tilt correction optical system having a conjugate relationship in the sub-scanning direction with the surfaces of the photosensitive drums 30A to 30D is formed.

  The polygon mirror 104 is composed of a pair of regular quadrangular columnar members having light beam deflection surfaces formed on the side surfaces, and the respective members are arranged adjacent to each other in the vertical direction in a state of being shifted by 45 degrees from each other. Yes. Then, it is rotated at a constant angular velocity in the direction of the arrow shown in FIG. 2 by a rotation mechanism (not shown). Therefore, the light beam branched into two in the vertical direction by the light beam splitting prism 202 of the incident optical systems 200A and 200B and condensed on the deflection surface of the polygon mirror 104 is alternately deflected by the upper and lower stages of the polygon mirror 104. .

  The fθ lenses 105 and 305 have an image height proportional to the incident angle of the light beam, and move the image surface of the light beam deflected at a constant angular velocity by the polygon mirror 104 at a constant speed with respect to the Y axis.

  The reflection mirrors 106A, 106B, 306C, and 306D have the longitudinal direction as the Y-axis direction, fold back the light beam that passes through the fθ lenses 105 and 305, and guide the light beams to the toroidal lenses 107A, 107B, 307C, and 307D, respectively.

  2 and 3, the toroidal lens 107A is stably supported by a support plate 110A whose longitudinal direction is the Y-axis direction and both ends are fixed to the housing 12, and is folded back by the reflection mirror 106A. The formed light beam is imaged on the surface of the photosensitive drum 30A through the reflection mirror 108A having the longitudinal direction in the Y-axis direction.

  The toroidal lenses 107B, 307C, and 307D have a longitudinal direction as the Y-axis direction, one end (+ Y side) is fixed to the housing 12, and the other end (−Y side) is a drive mechanism that includes, for example, a rotary motor and a feed screw mechanism. 112B, 312C, and 312D (not shown in FIG. 2, refer to FIG. 3) are stably supported by support plates 110B, 310C, and 310D, respectively. The light beams folded back by the reflection mirrors 106B, 306C, and 306D are respectively connected to the surfaces of the photosensitive drums 30B, 30C, and 30D via the reflection mirrors 108B, 308C, and 308D having the Y-axis direction as the longitudinal direction. Image.

  Photodetectors 141A and 141B are arranged in the vicinity of + Y side (light beam incident side) end portions of the toroidal lenses 107A and 107B, respectively, and in the vicinity of the −Y side (light beam incident side) end portions of the toroidal lenses 107C and 107D. Are respectively provided with photodetection sensors 141C and 141D.

  As shown in FIG. 8A as an example, the light receiving surface of the light detection sensor 141A includes a rectangular portion having a longitudinal direction as the Y-axis direction (main scanning direction) and a width in the main scanning direction as H1, and a rectangular portion. When the light beam is scanned prior to the scanning of the photosensitive drum 30A, for example, during the incidence of the light beam, It outputs a signal that turns on and turns off otherwise.

  The light detection sensors 141B to 141D also have a configuration equivalent to that of the light detection sensor 141A, and output a signal that is turned on while the light beam is incident and turned off otherwise.

  Photodetection sensors 142A and 142B are arranged near the −Y side ends of the toroidal lenses 107A and 107B, respectively, and photodetection sensors 142C and 142D are arranged near the + Y side ends of the toroidal lenses 107C and 107D, respectively. . Each of the light detection sensors 142 </ b> C to 142 </ b> D outputs a signal that is turned on while the light beam is incident and turned off otherwise.

  Next, the operation of the scanning optical system of the optical scanning device 100 configured as described above and the Carlson process will be described. A plurality of light beams emitted from the light source unit 201 of the incident optical system 200A are divided into two in the vertical direction by the light beam splitting prism 202 and transmitted through the liquid crystal elements 203A and 203B, respectively, so that the position correction in the sub-scanning direction is performed. Thereafter, the light is condensed on the deflection surface of the polygon mirror 104 by the cylinder lenses 204A and 204B. Then, the light beam deflected by the polygon mirror 104 enters the fθ lens 105.

  The upper light beam incident on the fθ lens 105 is reflected by the reflection mirror 106B and incident on the toroidal lens 107B. Then, the light is condensed on the surface of the photosensitive drum 30B by the toroidal lens 107B via the reflection mirror 108B. The lower light beam incident on the fθ lens 105 is reflected by the reflection mirror 106A and enters the toroidal lens 107A. Then, the light is condensed on the surface of the photosensitive drum 30B by the toroidal lens 107A via the reflection mirror 108A. The polygon mirror 104 has a phase difference of 45 degrees between the upper and lower deflection surfaces as described above. Accordingly, the scanning of the photosensitive drum 30B by the upper light beam and the scanning of the photosensitive drum 30A by the lower light beam are alternately performed in the −Y direction.

  On the other hand, a plurality of light beams emitted from the light source unit 201 of the incident optical system 200B are divided into two in the vertical direction by the light beam splitting prism 202 and transmitted through the liquid crystal elements 203A and 203B, thereby correcting the position in the sub-scanning direction. Then, the light is condensed on the deflection surface of the polygon mirror 104 from the cylinder lenses 204A and 204B. Then, the light beam deflected by the polygon mirror 104 enters the fθ lens 305.

  The upper light beam incident on the fθ lens 305 is reflected by the reflection mirror 306C and incident on the toroidal lens 307C. Then, the light is condensed on the surface of the photosensitive drum 30C by the toroidal lens 307C via the reflection mirror 308C. The lower light beam incident on the fθ lens 305 is reflected by the reflection mirror 306D and incident on the toroidal lens 307D. Then, the light is condensed on the surface of the photosensitive drum 30D by the toroidal lens 307D via the reflection mirror 308D. The polygon mirror 104 has a phase difference of 45 degrees between the upper and lower deflection surfaces as described above. Therefore, the scanning of the photosensitive drum 30C by the upper light beam and the scanning of the photosensitive drum 30D by the lower light beam are alternately performed in the + Y direction.

  The photosensitive layers on the respective surfaces of the photosensitive drums 30A, 30B, 30C, and 30D are charged with a predetermined voltage by the charging chargers 32A, 33B, 33C, and 32D, so that charges are distributed at a constant charge density. As described above, when each of the photosensitive drums 30A, 30B, 30C, and 30D is scanned, the photosensitive layer where the light beam is condensed becomes conductive, and charge transfer occurs in that portion, and the potential is increased. Becomes zero. Therefore, by scanning the photosensitive drums 30A, 30B, 30C, and 30D rotating in the directions of the arrows in FIG. 1 with the light beams modulated based on the image information, the respective photosensitive drums 30A, 30B, and 30C are scanned. , 30D can form an electrostatic latent image defined by the charge distribution.

  When electrostatic latent images are formed on the surfaces of the photosensitive drums 30A, 30B, 30C, and 30D, the developing rollers of the toner cartridges 33A, 33B, 33C, and 33D shown in FIG. Toner is supplied to each surface of 30D. At this time, since the developing rollers of the toner cartridges 33A, 33B, 33C, and 33D are charged by voltages having a polarity opposite to that of the photosensitive drums 30A, 30B, 30C, and 30D, the toner adhering to the developing rollers is the photosensitive drums 30A, 30B, and 30D. It is charged with the same polarity as 30C and 30D. Therefore, the toner does not adhere to the portions of the surfaces of the photosensitive drums 30A, 30B, 30C, and 30D where the electric charges are distributed, and the toner adheres only to the scanned portions, whereby the photosensitive drums 30A, 30B, and 30C. , A toner image in which the electrostatic latent image is visualized is formed on the surface of 30D. The toner image is transferred to the transfer belt 40.

  For example, when the photosensitive drums 30 </ b> A to 30 </ b> D are scanned, the misregistration detection device 45 performs detection at a predetermined timing such as when the power is turned on, when the standby state is restored, or when a predetermined number of prints have elapsed. The degree of overlapping of the color images is detected, and the toroidal lenses 107B, 107C, and 107D are driven via the drive mechanisms 112B, 112C, and 112D based on the detection results, and the toner images transferred at the second to fourth stations are detected. The inclination is matched with the inclination of the toner image formed at the first station.

  Next, the control circuit of the light source unit 201 of the optical scanning device 100 configured as described above will be described by taking the control circuit 400 of the light source unit 201 of the incident optical system 200A as a representative. As shown in FIG. 6, the control circuit 400 includes a high-frequency clock generation circuit 401, a counter 403, a comparison circuit 404, a pixel clock generation circuit 405, an image processing circuit 407, a frame memory 408, line buffers 4101 to 41028, and a write control circuit. 411, a light source driving circuit 413, and an optical axis variable control circuit 415.

  The high-frequency clock generation circuit 401 measures the detection time difference of the synchronization signals from the photodetection sensors 142A and 142B, and compares it with a predetermined reference value so as to cancel the magnification shift in the main scanning direction. VCLK is output.

  The counter 403 counts the clock signal VCLK generated by the high frequency clock generation circuit 401 and supplies the count value to the comparison circuit 404.

  The comparison circuit 404 uses the count value supplied from the counter 403, the preset value L set in advance based on the duty ratio stored in the memory 406, and the transition timing of the pixel clock as the scanning position and the scanning optical system. The design phase data HN (N = 1, 2, 3,...) Determined from the characteristics is compared. When the count value matches L, the control signal sig_L is output. When the count value matches the phase data HN, the control signal sig_H is output and a reset signal is supplied to the counter 403.

  The pixel clock generation circuit 405 outputs a pixel clock signal PCLK that becomes 1 when the control signal sig_L supplied from the comparison circuit 404 falls and becomes 0 when the control signal sig_H falls.

  Hereinafter, a method for generating the pixel clock signal will be described with reference to FIG. FIG. 7A shows a clock signal VCLK having a wavelength T generated by the high frequency clock generation circuit 401. The clock signal VCLK is counted by the counter 403 every cycle, and the count value cont is supplied to the comparison circuit 404. The comparison circuit 404 compares the count value cont with the set value L and the phase data H stored in the memory 406. Here, assuming that the duty ratio is 50%, the setting value L is 3, and the phase data HN is 7, the comparison circuit 404 raises the control signal sig_H when the count value cont becomes 3, and the count value cont When cont changes from 3, the control signal sig_H falls. When the count value cont becomes 7, the control signal sig_L is raised, and when the count value cont changes from 7, the control signal sig_H is lowered. The pixel clock signal generation circuit 405 sets the pixel clock signal PCLK to 0 when the control signal sig_H falls, and sets the pixel clock signal PCLK to 1 when the control signal sig_L falls. By repeating the above operation, the pixel clock signal generation circuit 405 generates the pixel clock signal PCLK obtained by dividing the clock signal VCLK by 8. In this embodiment, the pixel clock signal divided by 8 is used as a basic pixel clock signal, and phase modulation can be performed with a resolution of 1/8 clock.

  Next, a case where the phase of the pixel clock signal VCLK is delayed by 1/8 clock will be described with reference to FIG. 7B as an example. FIG. 7B shows a clock signal VCLK generated by the high-frequency clock generation circuit 401 and having a wavelength T, and a count value cont from the counter 403. When the phase data HN is changed to 6, the comparison circuit 404 raises the control signal sig_H when the count value cont becomes 3, and lowers the control signal sig_H when the count value cont changes from 3. When the count value cont becomes 6, the control signal sig_L is raised, and when the count value cont changes from 6, the control signal sig_H is lowered. The pixel clock signal generation circuit 405 sets the pixel clock signal PCLK to 0 when the control signal sig_H falls, and sets the pixel clock signal PCLK to 1 when the control signal sig_L falls. By repeating the above operation, the phase of the pixel clock signal PCLK can be delayed by 1/8 clock. In other words, in the present embodiment, by arbitrarily setting the value of the phase data L, PCLK can be phase-modulated with a resolution of 1/8 clock.

  Returning to FIG. 6, the frame memory 408 temporarily stores the raster-expanded image data supplied from the host apparatus 414.

  The image processing circuit 407 reads the data stored in the frame memory 408, creates pixel data for each light emitting source of the laser array 152, and supplies it to the line buffers 4101 to 41028 corresponding to the respective light emitting sources.

  The write control circuit 411 monitors the signals from the light detection sensors 141A and 141B, reads out the pixel data for each light source using the falling of the signal as a trigger (synchronization), and is supplied from the pixel clock generation circuit 405. Superimposed on the clock signal PCLK, independent modulation data is generated for each light source and supplied to the light source driving circuit 413.

  The light source driving circuit 413 drives one of the light sources of the laser array 152 in synchronization with the rotation of the polygon mirror 104, for example, and causes a light beam to enter the light detection sensor 141A or 141B as described later. Next, the light emission source to be driven first is selected, and the light emission source is sequentially driven based on the modulation data supplied from the writing control circuit 411 with this as the base point. Further, the intensity of the light beam emitted from the light source is constantly monitored via the light receiving element 157.

  The optical axis variable control circuit 415 detects the positional deviation of the beam spot in the sub-scanning direction of the light beam based on the pulse width (ON time) of the signals from the light detection sensors 141A and 141B, and this positional deviation is canceled. Thus, the liquid crystal elements 203A and 204A are controlled. Hereinafter, a method for detecting the positional deviation of the beam spot in the sub-scanning direction will be described by taking the light detection sensor 141A as a representative.

  As shown in FIG. 8A, consider a case where the light detection sensor 141A is scanned using a laser array 152 'having light sources G1 to G7 arranged at equal intervals in the sub-scanning direction. When the center of the light detection sensor 141A coincides with the center of the laser array 152 ′, when the light source G3, the light source G4, and the light source G5 of the laser array 152 ′ are sequentially driven to scan the light detection sensor 141A in the + Y direction, Three signals as shown in FIG. 8B are output from the light detection sensor 141A. Here, signal 3 is a signal when scanning is performed by driving the light source G3, signal 4 is a signal when scanning is performed by driving the light source G4, and signal 5 is a signal when scanning is performed by driving the light source G5. Signal.

  As described above, since the light receiving surface of the photodetector 141A has the largest width in the main scanning direction near the center, the on-time of the signal corresponding to the light source scanned near the center of the light receiving surface is maximized. In FIG. 8B, the on time t4 of the signal 4 is longer than the on time t3 of the signal 3 and the on time t5 of the signal 5. Therefore, in this case, the optical axis variable control circuit 415 can determine that the position of the light source G4 and the center position of the light detection sensor 141A substantially coincide with each other in the sub-scanning direction.

  On the other hand, as shown in FIG. 9A, the light source G3 and the light source G4 of the laser array 152 ′ in a state where the center position of the laser array 152 ′ is shifted in the + Z direction with respect to the center position of the light detection sensor 141A. When the light source G5 is sequentially driven to scan the light detection sensor 141A in the + Y direction, the light detection sensor 141A outputs three signals as shown in FIG. 9B. In this case, the ON time t5 of the signal 5 is longer than the ON time t3 of the signal 3 and the ON time t4 of the signal 4. Therefore, the optical axis variable control circuit 415 can determine that the position of the light source G5 and the center position of the light detection sensor 141A substantially coincide with each other in the sub-scanning direction.

  For example, when controlling the light source G4 corresponding to the center of the laser array 152 ′ and the center of the light detection sensor 141A in the sub-scanning direction, the laser array 152 ′ is driven or a light beam from the light source is emitted. And the optical path may be corrected so that the light beam from the light source G4 scans the center of the light receiving surface of the light detection sensor 141A.

  Next, as shown in FIG. 10, a case where the light detection sensor 141 </ b> A is scanned with G <b> 3, G <b> 4, and G <b> 5 among the light sources G <b> 1 to G <b> 7 in the first row of the laser array 152 provided in the light source unit 201 will be described.

  Each light source of the laser array 152 is arranged in a matrix with a distance d from the light sources adjacent to each other. Therefore, it is necessary to sequentially drive the light sources G3, G4, and G5 in consideration of the distance d · cos γ in the main scanning direction of the light sources G3, G4, and G5. FIG. 11 shows a drive signal 3 for driving the light source G3 output from the light source drive circuit 413, a drive signal 4 for driving G4, and a drive signal 5 for driving G5.

  As shown in FIG. 11, each of the driving signal 1, the driving signal 2, and the driving signal 3 has the same ON time as T0, but the rising timing is shifted by dt corresponding to the distance d · cos γ between the light sources. . However, in this case as well, each signal when the light sources G3, G4, and G5 scan the photodetection sensor 141A is out of phase according to the distance d · cosγ between the light sources as shown in FIG. The light sources G3, G4, and G5 have the same shape as when there is no distance in the main scanning direction.

  Therefore, the optical axis variable control circuit 411 compares the detection time width t4 of the detection signal 4 of the light source G4 with the detection time widths t3 and t5 of the detection signals 3 and 4 of the light sources G3 and G5. The amount of deviation of the light source G4 with respect to the light detection sensor 141A in the sub-scanning direction can be detected.

  As a result, for example, in the scanning device 100, the liquid crystal elements 203A and 203B are controlled so that the detection time width t4 of the detection signals 4 from all the light detection sensors 141A to 141D becomes the longest time width. It is possible to hold a scanning position where the resist in the scanning direction does not shift.

  Of the light receiving surface of the light detection sensor 141A, the width H1 of the rectangular portion in the main scanning direction is such that the scanned light beam is detected depending on the scanning speed (linear speed) of the light beam, the sensitivity of the light detection sensor 141A, and the like. By setting the width to be sufficiently larger than the possible width, synchronization detection signals of a plurality of light sources can be acquired. The width H2 of the triangular portion in the main scanning direction is increased to such an extent that the difference in detection time width between adjacent light sources in the sub-scanning direction can be detected, thereby accurately detecting the sub-scanning positions of a plurality of light sources. Can be done well. For example, in FIG. 11, the width H2 of the triangular portion may be increased so that the difference between the detection time widths t3, t4, and t5 of the detection signals from the light sources G3, G4, and G5 is sufficiently large. As a result, it is possible to detect misalignment of the plurality of light sources in the sub-scanning direction by the light detection sensor 141A and to correct the sub-scanning misalignment based on the detection signal.

  In the optical scanning device 100 having the control circuit 400 configured as described above, when image information from the host device 414 is received, the light source unit 201 is driven by the modulation data based on the image information, and the first station and the second station In the third station and the fourth station, toner images of the respective color image components are formed on the transfer belt 40 so as to overlap each other. Then, as shown in FIG. 1, the toner image is transferred to a sheet 61 taken out from the sheet feed tray 60 by a transfer charger 48 and fixed by a fixing roller 50. The paper 61 on which the image is formed in this manner is discharged by the paper discharge roller 58 and sequentially stacked on the paper discharge tray 12a.

  As described above, according to the optical scanning device 100 of the present embodiment, the light receiving surfaces of the light detection sensors 141A, 141B, 141C, and 141D that receive the light beam deflected by the polygon mirror 104 are, for example, FIG. ), The width in the main scanning direction is different between the central portion in the sub-scanning direction and the other portions. As a result, the time during which the light beam is incident on the light receiving surface is different in that the scanning position is different between the central portion in the sub-scanning direction and the other portions as shown in FIGS. 8B and 9B, for example. Become. Accordingly, it is possible to detect the positional deviation of the light beam in the sub-scanning direction based on the difference in time during which the light beam is incident on the light detection sensors 141A, 141B, 141C, and 141D. For example, the positional deviation of the beam spot of the light beam detected for each scan is corrected by driving the liquid crystal elements 203A and 203B by the light source driving circuit 413 shown in FIG. Therefore, it is possible to effectively reduce the positional deviation of the beam spot on the scanned surface of the photosensitive drums 30A to 30D.

  In addition, signals from the light detection sensors 141A, 141B, 141C, and 141D are supplied to the write control circuit 411 as synchronization detection signals. As a result, it is possible to detect synchronization in the main scanning direction by the light detection sensors 141A, 141B, 141C, and 141D, and it is not necessary to newly provide a light receiving element for detecting a displacement, and even during a job. Since it is possible to detect the positional deviation of the light beam, it is possible to maintain the scanning accuracy without stopping the processing.

  Further, in the optical scanning device 100 according to the present embodiment, the case where the width of the light receiving surface at the center in the sub-scanning direction is larger than the width at both ends in the sub-scanning direction has been described, as shown in FIG. However, the width is not limited to this, and the width of the central portion in the sub-scanning direction may be smaller than the width of both end portions in the sub-scanning direction. In short, it is sufficient if the light receiving surface of the light detection sensor is scanned so as to have a difference in the time during which the light beam is incident according to the position in the sub-scanning direction.

  Further, in the optical scanning device 100 according to the present embodiment, as shown in FIG. 11, the drive signals for driving the respective light sources are generated at different timings as shown in FIG. When cos γ is small, each light source may be driven based on the same timing, for example, the drive signal 4. In short, when the rise time T0 of the drive signal is large enough to include the detection time shift between the light detection sensors 141A, 141B, 141C, 141D of the light sources farthest in the main scanning direction, The light source may be driven. In this case, for example, by using only the drive signal 4 as the drive signals for all of the plurality of light sources, the light source drive circuit 413 that generates the drive signals can be simplified.

  In addition, there is a method of generating the rise time of the drive signal based on, for example, a clock signal PCLK that is a timing clock for writing image data.

  Further, in the optical scanning device 100 according to the present embodiment, the laser array 152 in which 28 light sources are formed is used. However, for example, when there are as few as 4 to 8 light sources, the entire difference amount of the detection signals is increased. Therefore, even if the width h1 of the triangular portion is smaller than the width h1 of the rectangular portion of the light receiving surface of the light detection sensor, the positional deviation amount of the beam spot in the sub-scanning direction is compared by comparing the detection time width of the light detection signal. Can be detected. On the other hand, when the number of light sources is 10 or more, for example, by making the width h1 of the triangular portion larger than the width h1 of the rectangular portion, it is possible to detect a difference in sub-scanning position deviation of the plurality of light sources.

  Further, as shown in FIG. 8, one end in the main scanning direction of the light receiving surfaces of the light detection sensors 141A, 141B, 141C, and 141D is shaped to be perpendicular to the main scanning direction. For this reason, when a plurality of light sources pass through this surface, the synchronization detection timing is the same even if the sub-scanning position is different for any light source. Therefore, it becomes possible to measure the drive timing of the other light source by the drive signal of any one light source.

  In addition, when the shape of the light receiving surface of the light detection sensor is axisymmetric with respect to the main scanning axis, the detection time width of the detection signal when detecting a light beam shifted in the vertical direction with respect to the center of the sub scanning direction When the amount of positional deviation of the light beam from the center position in the sub-scanning direction is the same, it is equivalent. For this reason, when comparing the detection time widths in the vicinity of the center in the sub-scanning direction, it is possible to roughly find the positional deviation amount of each light source. Therefore, for example, by driving a plurality of light sources in the sub-scanning direction and comparing the time widths, it is possible to detect an approximate positional deviation in the sub-scanning direction, and to reduce the number of detections and the detection time. Is possible.

  The width of the light detection sensor 141A in the sub-scanning direction is the sub-scanning detection width wpdl, the interval between the adjacent sub-scanning directions of the plurality of light sources is dl, and the interval of the sub-scanning direction when all the light sources are turned on in the sub-scanning direction of the plurality of light sources is wldl. Then, when N light sources are arranged in the sub-scanning direction, a relationship of wldl = dl × (N−1) is established. FIG. 12 shows an example in the case of N = 8. For example, when a 600 dpi pixel is formed by eight light sources G1 to G8 in the sub-scanning direction, dl is about 42.3 μm and wldl is about 296.1 μm (= 42.3 × 7). Similarly, when a 1200 dpi pixel is formed with eight light sources G1 to G8 in the sub-scanning direction, dl is about 21.2 μm and wldl is about 148.4 μm (= 21.2 × 7). When the relationship of wpdl> wldl is established, even if a positional deviation of the light source occurs in the sub-scanning direction, the light detection sensor 141A can be scanned with high accuracy so long as it is within the range of wpdl-wldl. It is possible to detect misalignment in the sub-scanning direction.

  For example, when the laser array on which the light source is formed has an inclination at the attachment position, the sub-scanning position of the light source changes as in patterns A, B, and C as shown in FIG. Even when tilting occurs, if the scanning range falls within the sub-scanning direction range of the light detection sensor 141A, the light beams from all the light sources scan the light receiving surface of the light detection sensor 141A. By correcting the tilt of the laser array in accordance with the amount of sub-scanning position deviation or by tilting the beam emission axis using a liquid crystal element, it is possible to correct the position deviation in the sub-scanning direction.

  Also, each light source emits light, and the time width of the signal detected by the light detection sensor is stored in a memory provided for each light source by replacing the sub-scanning position signal with a numerical value such as a clock signal count number, for example. Is read from the memory at the time of scanning, and the sub-scanning position shift amount is obtained by signal comparison, thereby enabling highly accurate sub-scanning position shift detection. In addition, when the time when the light sources emit light within one scanning time to obtain the synchronization detection signal and the sub-scanning position detection signal is the synchronization detection time, the light detection sensor is scanned within this synchronization detection time, thereby detecting the synchronization. A signal and a sub-scanning position detection signal can be acquired.

  Further, the printer 10 as the image forming apparatus according to the present embodiment includes the optical scanning device 100. Therefore, even when a longer processing time is required depending on the contents of the job, the positional deviation of the toner image is corrected without stopping the processing of the image forming apparatus 10. Therefore, it is possible to improve the image quality without causing a decrease in productivity.

  In the above embodiment, correction of the beam spot of the light beam is performed by the liquid crystal elements 203A and 203B. However, the present invention is not limited to this. For example, the correction may be performed by changing the angle of the laser array 152.

  In the above embodiment, the case where the optical scanning device 100 of the present invention is used in a printer has been described. However, the image forming apparatus other than the printer, for example, a copier, a facsimile, or a multifunction machine in which these are integrated. Is preferred.

1 is a diagram illustrating a schematic configuration of a printer 10 according to an embodiment of the present invention. 1 is a perspective view showing an optical scanning device 100. FIG. 1 is a side view showing an optical scanning device 100. FIG. 2 is a perspective view illustrating a schematic configuration of a light source unit 201. FIG. 2 is a plan view showing a laser array 152. FIG. 2 is a block diagram of a control circuit 400 of the optical scanning device 100. FIG. 7A and 7B are diagrams for explaining a method of generating a pixel clock signal. FIGS. 8A and 8B are diagrams (No. 1 and No. 2) for explaining a method of detecting a positional shift by the photodetection sensor 141A. FIGS. 9A and 9B are diagrams (No. 3 and No. 4) for explaining a method of detecting a positional shift by the photodetection sensor 141A. It is FIG. (5) for demonstrating the detection method of position shift by the photon detection sensor 141A. It is FIG. (6) for demonstrating the detection method of position shift by the photon detection sensor 141A. It is a figure for demonstrating the modification of the detection method of position shift by 141 A of optical detection sensors.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Printer, 12 ... Housing, 30A-30B ... Photosensitive drum, 40 ... Transfer belt, 50 ... Fixing roller, 45 ... Position shift detector, 100 ... Optical scanning device, 104 ... Polygon mirror, 105, 305 ... f (theta) lens, 106A, 106B, 108A, 108B, 306C, 306D, 308C, 308D ... reflection mirror, 107A, 107B, 307C, 307D ... toroidal lens, 201 ... light source unit, 202 ... beam splitting prism, 202A, 202B ... liquid crystal element, 204A, 204B... Cylinder lens, 141A, 141B, 141C, 141D, 142A, 142B, 142C, 142D... Photodetection sensor, 152... Laser array, 400... Control circuit, 413.

Claims (13)

An optical scanning device that scans a surface to be scanned with light beams emitted from a plurality of light sources,
A scanning optical system that scans the scanned surface with a plurality of light beams in a main scanning direction;
A light beam scanned by the scanning optical system is received, and the width in the main scanning direction at both ends in the sub scanning direction orthogonal to the main scanning direction and the width in the main scanning direction at the center in the sub scanning direction. A photodetector having a light receiving surface whose difference from the width is larger than the width in the main scanning direction at both ends in the sub-scanning direction;
By sequentially driving the plurality of light sources for each scan, a light beam from the driven light source is sequentially incident on the photodetector, and detection times of signals sequentially output from the photodetector are compared. And a processing device that detects positions of the light beams emitted from the plurality of light sources in the sub-scanning direction with respect to the photodetector . An optical scanning device that scans a surface to be scanned with light beams emitted from a plurality of light sources,
A scanning optical system that scans the scanned surface with a plurality of light beams in a main scanning direction;
A light beam scanned by the scanning optical system is received, and the width in the main scanning direction at both ends in the sub scanning direction orthogonal to the main scanning direction and the width in the main scanning direction at the center in the sub scanning direction. A photodetector having a light receiving surface whose difference from the width is equal to or less than the width in the main scanning direction at both ends in the sub-scanning direction;
By sequentially driving the plurality of light sources for each scan, a light beam from the driven light source is sequentially incident on the photodetector, and detection times of signals sequentially output from the photodetector are compared. And a processing device that detects positions of the light beams emitted from the plurality of light sources in the sub-scanning direction with respect to the photodetector . The optical scanning device according to claim 1, wherein the light receiving surface has one end in the main scanning direction orthogonal to the main scanning direction. 4. The optical scanning device according to claim 1, wherein the shape of the light receiving surface is line symmetric with respect to an axis passing through the center and parallel to the main scanning direction. The sub-scanning direction width of the light receiving surface, the according to any one of claims 1 to 4, characterized in that greater than the maximum write width of the sub-scanning direction of scanning during one scanning surface to be scanned Optical scanning device. Each beam spot of the light beam emitted from the plurality light sources, any one of claim 1 to 5, characterized in that said is formed at predetermined intervals in the sub-scanning direction on the surface to be scanned The optical scanning device described. The processing apparatus includes an optical scanning apparatus according to any one of claims 1 to 6, characterized in that storing a detection time of the signals sequentially output from said detector. The processing apparatus includes an optical scanning apparatus according to any one of claims 1 to 7, characterized in that driving at the same timing for every one scanning of the light source. The processing apparatus includes an optical scanning apparatus according to any one of claims 1-7, characterized in that for driving the light source at a timing corresponding to the main scanning direction of the position of the light source for each one scanning . The processing unit, based on the detection time of the signals sequentially outputted from the detector, the plurality of light sources, the light beam from the light source in the middle relates the sub-scanning direction, the light-receiving surface of the photodetector the optical scanning apparatus according to any one of claims 1-9, characterized in that the corrected so that the center position in the sub-scanning direction.   The scanning optical system includes a plurality of optical elements that shape light beams emitted from the plurality of light sources, and a deflecting unit that collectively deflects the light beams emitted from the plurality of light sources, The optical scanning device according to claim 1, wherein the plurality of optical elements are accommodated in a single housing.   The optical scanning device according to claim 1, wherein the photodetector is housed in the housing. An image forming apparatus for forming a multicolor image by superimposing and fixing a toner image formed on the basis of a latent image for each color obtained from information on a multicolor image on a recording medium,
An optical scanning device according to any one of claims 1 to 12;
A plurality of photoreceptors on which latent images corresponding to a plurality of colors are respectively formed by the optical scanning device;
Developing means for visualizing the latent images formed on the scanned surfaces of the photoreceptor;
An image forming apparatus comprising: a transfer unit configured to superimpose and fix the toner image of each color visualized by the developing unit on the recording medium.

Images