JP2007164061A - Optical apparatus and imaging method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical apparatu which can make high in operating speed and high in image quality when being made in a multibeam process by using an optical modulator. <P>SOLUTION: A laser unit 301 has three semiconductor lasers arranged in a subscanning direction. Laser beams emitted from the respective semiconductor lasers are focused on the optical modulator 304 with a cylindrical lens 303. The plurality of laser beams focused on the optical modulator 304 are divided into seven laser beams which become spot light sources lined up in the subscanning direction with the optical modulator 304. The multibeam composed of seven laser beams is focused on a photoreceptor drum face 225 via a collimator lens 305, a diaphragm 306, a cylindrical lens 307, a polygon mirror 308 and an fθ lens 309. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical apparatus and an imaging method for condensing light rays and forming an image on a surface to be scanned.

  2. Description of the Related Art Conventionally, image forming apparatuses that form an electrostatic latent image by scanning a photosensitive member with a light beam modulated according to an image signal are widely used in devices such as printers and copiers. In recent years, these devices are required to have high resolution, high speed, and low price.

  Regarding the increase in resolution, the technical point is how to improve the resolution in the sub-scanning direction. Regarding the main scanning direction, the resolution is improved by light modulation (PMW modulation) within one pixel.

  However, regarding the sub-scanning direction, when the resolution is improved by using a laser (single beam laser) having only one light emitting point, the throughput is extremely deteriorated. For this reason, a multi-beam laser having a plurality of emission points is often used. However, when a plurality of light emitting points are used, a problem such as crosstalk occurs. Therefore, a certain distance is required between the light emitting points.

  That is, when a multi-beam laser is used, a plurality of light emitting points are arranged to be inclined with respect to the sub-scanning direction. At this time, the beam interval corresponding to the resolution on the surface to be scanned is set by precisely adjusting the angle. The adjustment of the beam interval requires higher precision as the resolution is improved. For this reason, it is difficult to improve the resolution in the sub-scanning direction compared to the main scanning direction.

  On the other hand, it is possible to increase various process speeds such as paper conveyance speed, drum rotation speed, polygon rotation speed, and the like. However, it is difficult to extremely increase various speeds related to image formation in an electrophotographic system that requires many physical conditions. In addition, obtaining a higher speed rotation for the polygon drive motor leads to higher cost of the drive motor and more complicated control. In addition, since it takes a long time from the stop to the stable drive, it tends to cause a delay in the first print time related to the performance of the product.

  As means for achieving such high resolution and high speed, the following image recording apparatuses have been proposed (see Patent Documents 1 and 2). This image recording apparatus has a configuration in which a laser beam generated from a laser light source is split using an optical modulator such as a diffraction element, and the plurality of light beams are independently modulated. As such an optical modulator, a grating light valve (registered trademark of Silicon Light Machine Co., Ltd.) is known. This grating light valve is abbreviated as GLV.

By using this optical modulator to convert the laser beam into multi-beams at arbitrary sub-scanning intervals, it is possible to simultaneously achieve high resolution and high speed. Also, if you want to reduce the price, you can realize an inexpensive image forming device with the same resolution as before by combining the multi-beam optical system and an inexpensive drive system driven at a low rotational speed. It is.
JP-A-9-174933 JP 2002-72117 A

  However, the above conventional example has the following problems. The one described in Patent Document 1 has a configuration in which a GLV array corresponding to the image width in the main scanning direction is used and the image is enlarged and projected onto the surface to be scanned. For this reason, the projection optical system tends to be large, and a wide illumination optical system for illuminating the entire GLV is required. Therefore, the size of the apparatus is increased and the cost is likely to increase.

  On the other hand, the one described in Patent Document 2 uses a GLV having a relatively small number of pixels and the projection optical system is also relatively compact, but the image width that can be projected at one time is narrow. Therefore, in synchronization with the rotation of the drum, the GLV and the projection optical system are moved in the main scanning direction, and an image is recorded in a spiral shape on the drum surface. With such a configuration, the increase in speed was severely inhibited, and image unevenness in the main scanning direction was easily noticeable.

  Accordingly, the present invention provides an optical device and an imaging method capable of achieving high speed and high image quality without causing an increase in size of the device when performing multi-beam using an optical modulator. With the goal.

  In order to achieve the above object, an optical device of the present invention is an optical device that focuses light rays and forms an image on a scanned surface, and is arranged in the sub-scanning direction with respect to the scanned surface, and It has a plurality of light sources to be emitted and a plurality of elements arranged at least in the sub-scanning direction, and independently modulates the light beams formed on the respective elements to divide the light beams from the plurality of light sources in the sub-scanning direction. An optical modulator, a first optical system for imaging light beams emitted from the plurality of light sources on each element of the optical modulator, and a plurality of light beams divided in the sub-scanning direction by the optical modulator. And a second optical system for focusing the light and forming an image on the surface to be scanned.

  The imaging method of the present invention is an imaging method in which a light beam is condensed and imaged on a scanned surface, and the light beam is emitted by a plurality of light sources arranged in a sub-scanning direction with respect to the scanned surface. The light beams emitted from the plurality of light sources by the first optical system are imaged on each element of an optical modulator having at least a plurality of elements arranged in the sub-scanning direction, and each element is formed by the optical modulator. The light beams formed on the light source are independently modulated to divide the light beams from the plurality of light sources in the sub-scanning direction, and the plurality of light beams divided in the sub-scanning direction are condensed by the second optical system, respectively. An image is formed on the scanning plane.

  According to the optical device of the first aspect of the present invention, an image having an accurate shape can be formed on the surface to be scanned. Therefore, when performing multi-beam using an optical modulator, high speed and high image quality can be achieved without increasing the size of the apparatus.

  According to the optical device of the third aspect, it is possible to achieve multi-beam using an optical modulator in both the main scanning direction and the sub-scanning direction. In addition, the amount of light per pixel can be increased by using multiple beams in the main scanning direction.

  Embodiments of an optical device and an imaging method of the present invention will be described with reference to the drawings. The optical device according to the present embodiment is applied to an optical unit mounted on an image forming apparatus.

[First Embodiment]
FIG. 1 is a diagram illustrating an internal configuration of an image forming apparatus on which the optical unit according to the first embodiment is mounted. The image forming apparatus 50 includes a color image reader unit (simply referred to as a reader unit) 10 located at the upper part and a color image printer part (simply referred to as a printer part) 20 located at the lower part.

  In the reader unit 10, an automatic document feeder (ADF) 102 is provided on a platen glass (platen) 101 on which a document is placed. Instead of the automatic document feeder 102, a configuration in which a specular pressure plate or a white pressure plate (not shown) is mounted may be used. In the reader unit 10 body, a carriage 114, a carriage 115, a lens 110, a CCD (charge coupled device) image sensor (simply referred to as a CCD) 111, and the like are provided.

  The carriage 114 accommodates light sources 103 and 104, reflectors 105 and 106, and a mirror 107. The light sources 103 and 104 illuminate the document. As the light source, a halogen lamp, a fluorescent lamp, a xenon lamp, or the like is used. Reflector umbrellas 105 and 106 collect the light from light sources 103 and 104, respectively, on the document. The mirror 107 reflects the reflected light from the document toward the carriage 115.

  The carriage 115 accommodates mirrors 108 and 109. The mirrors 108 and 109 reflect the reflected light or projection light from the original reflected by the mirror 107 toward the CCD 111. The lens 110 collects the light reflected by the mirror 109 on the CCD 111.

  The carriage 114 mechanically moves at a speed V in the sub-scanning direction Y orthogonal to the electrical scanning direction (main scanning direction X) of the CCD 111. Similarly, the carriage 115 mechanically moves in the sub-scanning direction Y at the speed V / 2. Thereby, the entire surface of the document is scanned.

  In addition, the reader unit 10 main body includes a substrate 112 on which the CCD 111 is mounted, a control unit 100 that controls the entire image forming apparatus, a digital image processing unit 113, an external interface (I / F) 116 with other devices, and the like. Is provided.

  On the other hand, the printer unit 20 performs an image forming operation in accordance with a control signal received via the printer control I / F 218 from the CPU in the control unit 100. The photosensitive drum 202 rotates counterclockwise, and the optical unit 201 forms an electrostatic latent image on the photosensitive drum 202. A rotating color developing unit 203 that develops the electrostatic latent image formed on the photosensitive drum 202 is provided to be rotatable about the rotating shaft 200. The rotating color developing device 203 includes developing devices 221, 222, 223, and 224 arranged around the rotating shaft 200. The developing units 221, 222, 223, and 224 correspond to black, yellow, magenta, and cyan colors, respectively.

  When a toner image is formed on the photosensitive drum 202, the rotary color developing device 203 is rotationally driven by a stepping motor (not shown). One of the developing units 221 to 224 is selectively moved to a developing position (position close to or in contact with the photosensitive drum 202) according to each separation color to be developed. An amount of toner corresponding to the electric charge charged on the photosensitive drum 202 is supplied from the developing units 221 to 224, and the electrostatic latent image on the photosensitive drum 202 is developed.

  Each of the developing devices 221 to 224 can be easily detached from the main body of the rotating color developing device 203. In the rotary color developing unit 203, positions corresponding to the respective colors of black, yellow, magenta, and cyan are designated in the clockwise direction. The developing devices 221 to 224 of the respective colors are mounted at designated color positions.

  When developing a black monochrome image, only the black developer 221 is used. The rotating color developing unit 203 is rotated until the sleeve (not shown) of the black developing unit 221 is opposed to the photosensitive drum 202, and the toner is supplied. On the other hand, when developing a full-color image, all the developing devices 221 to 224 are used. In order of black, yellow, magenta, and cyan, the rotating color developing unit 203 is rotated to the visualization position 226 where the sleeve of each developing unit faces the photosensitive drum 202, and toner is supplied.

  The toner image formed on the photosensitive drum 202 is transferred onto the intermediate transfer member 205 that rotates clockwise in synchronization with the counterclockwise rotation of the photosensitive drum 202. The transfer to the intermediate transfer member 205 is completed by one rotation of the intermediate transfer member 205 in the case of a black monochrome image, and is completed in four rotations in the case of a full color image. When an image having a specific sheet size, for example, A4 size or smaller, is formed, two images can be formed on the intermediate transfer member 205.

  On the other hand, in synchronization with the transfer of the toner image to the intermediate transfer member 205, a sheet (recording paper) transport operation is performed. The sheet is picked up by the pickup roller 211 (or pickup roller 212) from the upper cassette 208 (or lower cassette 209). Further, the sheet is conveyed by the sheet feeding roller 213 (or the sheet feeding roller 214), and is conveyed to the registration roller (registration R) 219 by the conveyance roller 215. The sheet is conveyed between the intermediate transfer member 205 and the transfer belt 206 at the timing when the transfer to the intermediate transfer member 205 is completed.

  Thereafter, the sheet is conveyed by the transfer belt 206 and pressed against the intermediate transfer member 205, and the toner image on the intermediate transfer member 205 is transferred to the sheet. The toner image transferred to the sheet is heated and pressed by the fixing roller and the pressure roller 207, and fixed on the sheet. The sheet on which the image is fixed is discharged from the face-up discharge port 217.

  Residual toner on the intermediate transfer member 205 remaining without being transferred to the sheet is cleaned by post-processing control in the latter half of the image forming sequence. That is, the residual toner is charged as waste toner to the reverse polarity of the original toner polarity by the cleaning device 230, and the residual toner having the reverse polarity is transferred again onto the photosensitive drum 202. Residual toner having a reverse polarity is scraped from the drum surface by a blade (not shown) provided around the photosensitive drum 202 and conveyed to a waste toner box 231 integrated as a photosensitive drum unit. In this way, the residual toner on the intermediate transfer member 205 is completely cleaned.

  Next, the optical unit 201 will be described. FIG. 2 is a diagram showing an optical arrangement of the optical unit 201 in the main scanning. FIG. 3 is a diagram showing an optical arrangement of the optical unit 201 in the sub-scanning.

  The optical unit 201 includes a semiconductor laser unit (light source) 301 including a semiconductor laser that emits monochromatic light, a collimator lens 302, a cylindrical lens 303, an optical modulator 304, a collimator lens 305, an aperture 306, a cylindrical lens 307, a polygon mirror 308, and the like. It comprises an fθ lens 309.

  In this embodiment, as the optical modulator 304, a grating light valve (registered trademark of Silicon Light Machines) also called GLV manufactured by Silicon Light Machines of the United States is used. FIG. 4 is a cross-sectional view showing a main part of the optical modulator 304. FIG. 5 is a plan view schematically showing a reflecting plate (ribbon) 51 in the optical modulator 304. FIG. 6 is an enlarged view showing a part of the reflector (ribbon) 51. FIG. 7 is a perspective view showing the reflection plate 51 for one pixel in the optical modulator 304 together with the support base 52.

  The optical modulator 304 is arranged in close proximity to the support base 52, thousands of reflective plates 51 arranged in a row on the support base 52, and parallel to the reflective plate 51 above the reflective plates 51. A protective glass 53.

  The reflection plate 51 is a general term for the fixed reflection plate 51a and the movable reflection plate 51b that are alternately arranged. The fixed reflector 51a has a structure in which the position of the surface is fixed. On the other hand, the movable reflecting plate 51b has a structure that descends according to the voltage to which the effective movable region L1 is applied in the entire length L2 of the surface thereof. The six reflecting plates 51 including the three fixed reflecting plates 51a and the three moving reflecting plates 51b constitute one element (pixel) and are used for modulation of the laser beam. That is, the three movable reflectors 51b are lowered in synchronization with each other.

  In the optical modulator 304 having such a structure, when no voltage is applied to each movable reflector 51b, the surfaces of all the fixed reflectors 51a and the surfaces of the movable reflectors 51b are arranged on the same plane. Yes. In this state, when a voltage is applied to the moving reflecting plate 51b, the moving reflecting plate 51b is lowered by a distance of 1/4 of the wavelength of the laser beam (see FIG. 7), and the same action as that of the reflective diffraction grating I do.

  For this reason, the optical modulator 304 reflects the 0th-order diffracted light of the incident laser beam when no voltage is applied to the movable reflecting plate 51b. Further, when a voltage is applied to the movable reflector 51b, two positive and negative first-order diffracted lights and higher-order diffracted lights are reflected.

  Therefore, when the laser beam is irradiated onto the rectangular region S indicated by the two-dot chain line in FIG. 5 on the surface of the reflecting plate 51, hundreds of laser beams that can be modulated independently of each other are obtained. This area S is an area suitable for reflection, and is included in the effective movable area L1 of the movable reflecting plate 51b.

  The lengths of these laser beams in the arrangement direction (sub-scanning direction) are defined by the total width of the six reflecting plates 51, as indicated by reference numeral A in FIG. Further, the length in the direction (main scanning direction) orthogonal to the arrangement direction of these laser beams is defined by the width of the rectangular region S as indicated by reference numeral B in FIG.

  Further, when the optical modulation elements are arranged in the sub-scanning direction as in this embodiment, it is desirable that a plurality of semiconductor lasers in the semiconductor laser unit 301 be provided in the sub-scanning direction.

  Regarding the main scanning direction, the imaging spot diameter on the photosensitive drum in the main scanning direction depends on the numerical aperture (NA) of the light beam condensed on the optical modulator 304 by the cylindrical lens 303 and the focal length of the fθ lens 309. ,It is determined. Therefore, in order to set the spot diameter to a desired value, the focal lengths of the collimator lens 302 and the cylindrical lens 303 are set to optimum values, and the numerical aperture of the speed of light collected on the optical modulator 304 is increased. .

  On the other hand, the numerical aperture (NA) of the light beam diffracted by each pixel of the optical modulator 304 in the sub-scanning direction depends on the pixel size of the optical modulator 304. For this reason, it tends to be difficult to set the imaging spot diameter on the photosensitive drum in the sub-scanning direction to a desired value.

  In order to improve the contrast on the surface of the photosensitive drum, it is preferable to configure one pixel of the optical modulator 304 with as many fixed ribbons and movable ribbons as possible. In other words, in order to obtain high image quality, the pixel size increases, so the numerical aperture (NA) of the light beam diffracted by each pixel decreases, and the imaging spot diameter in the sub-scanning direction on the surface of the photosensitive drum decreases. Is difficult.

  Therefore, in this embodiment, by arranging a plurality of semiconductor lasers as light sources in the sub-scanning direction, the numerical aperture (NA) of the light beam diffracted by each pixel of the optical modulator 304 is increased while improving the contrast. ing. For this reason, it is easy to reduce the imaging spot diameter in the sub-scanning direction on the photosensitive drum surface. The optical unit of this embodiment is composed of three semiconductor lasers arranged in the sub-scanning direction. However, the optical unit is not limited to such a configuration, and may have another configuration as long as a plurality of laser elements are arranged in the sub-scanning direction.

  FIG. 8 is a diagram showing the arrangement of the optical modulation elements in the optical modulator 304. The optical modulator 304 has seven pixels (optical modulation elements) arranged in the sub-scanning direction. Here, each pixel is indicated by numbers 1 to 7 in order. As described above, in each of the pixels 1 to 7, six elongated movable ribbons 51b and fixed ribbons 51a are alternately arranged.

  When a voltage is applied to the optical modulation element, the movable ribbon 51b is lowered (depressed) toward the substrate 52. Thereby, an optical path difference is generated between the reflected light from the upper surface of the fixed ribbon 51a and the reflected light from the upper surface of the movable ribbon 51b, and diffracted light is generated by the optical path difference. This diffracted light enters the subsequent optical system and forms an image on the photosensitive drum.

  The operation of the optical unit 201 having the above configuration will be described. A plurality of laser beams output from the laser unit 301 as a light source enter the collimator lens 302, and both the main scanning component and the sub-scanning component are emitted as substantially parallel light beams. The collimator lens 302 condenses the radially output laser light. Further, the laser light emitted from the collimator lens 302 may not be accurate parallel light.

  The laser beam condensed by the collimator lens 302 enters the cylindrical lens 303. The cylindrical lens 303 is a lens having a refractive power in the main scanning direction, and forms an image on the optical modulator 304 with the laser light emitted from the collimator lens 302.

  The laser light imaged on the optical modulator 304 by the cylindrical lens 303 is divided by the optical modulator 304 into laser light serving as seven point light sources in the sub-scanning direction. In FIG. 3, only light reflected by the optical modulation elements (pixels) 1 and 7 is drawn for simplification. As described above, the light incident on the optical modulator 304 and diffracted by each pixel can be substantially regarded as a point light source. Therefore, the laser light reflected by the optical modulator 304 can be regarded as a multi-beam composed of seven light beams.

  The light beams output as seven radiated lights from the optical modulator 304 enter the collimator lens 305. Similar to the collimator lens 302, the collimator lens 305 collects light traveling radially. The light beam condensed by the collimator lens 305 is incident on the cylindrical lens 307 after the beam width is limited by the stop 306.

  The cylindrical lens 307 has a refractive power only in the sub-scanning direction. Therefore, the light beam that has passed through the cylindrical lens 307 becomes a substantially parallel light beam only in the main scanning direction (see FIGS. 2 and 3). Here, the configuration in which the cylindrical lens 307 is arranged before the incidence of the polygon mirror 308 is for correcting the surface tilt of the polygon mirror, and is common in a scanning system using the polygon mirror. Further, the fθ lens 309 has a conjugative relationship between the condensing point condensed on the polygon mirror surface by the cylindrical lens 307 and the photosensitive drum surface 225 in the sub-scanning direction. Therefore, even if the reflection surface of the polygon mirror is inclined, the imaging spot on the photosensitive drum surface does not shift in the sub-scanning direction. The laser beam reflected by the polygon mirror 308 is converted into a constant velocity motion by the fθ lens 309 and forms an image on the photosensitive drum surface 225. Note that broken lines B and C in FIG. 2 schematically show the light beam scanned by the polygon mirror 308.

  Thus, according to the optical unit in the first embodiment, an accurate spot-shaped image can be formed on the photosensitive drum surface. Also, multi-beam can be achieved without changing the configuration of the image forming apparatus other than the optical unit. Therefore, when performing multi-beam using an optical modulator, high speed and high image quality can be achieved without increasing the size of the apparatus.

  In this embodiment, the optical modulator includes seven optical modulation elements (pixels) 1 to 7 in order to divide the laser light from the three point light sources into seven lights. It is not limited to the pixel arrangement / shape. FIG. 9 is a diagram showing an arrangement of other optical modulation elements in the optical modulator. This optical modulator has 14 optical modulation elements arranged in the sub-scanning direction. In this case, more multi-beams can be realized.

[Second Embodiment]
FIG. 10 is a diagram illustrating an optical arrangement of the optical unit 201 in the main scanning according to the second embodiment. FIG. 11 is a diagram showing an optical arrangement of the optical unit 201 in the sub-scanning. The same components as those in the first embodiment are denoted by the same reference numerals and the description thereof is omitted.

  The optical unit 201 of the second embodiment has a semiconductor laser unit 401 and an optical modulator 404 that are different from those of the first embodiment. The optical unit 401 (laser scanner unit) has nine semiconductor lasers. Since these semiconductor lasers irradiate the optical modulator with more light beams, the optical axis of the light beam emitted from the semiconductor laser is made parallel to the central axis of the collimator lens (the one-dot chain line in FIG. 11). Be placed.

  FIG. 12 is a diagram showing an arrangement of optical modulation elements in the optical modulator 404. This optical modulator 404 has a total of nine pixels 404a of three columns in the main scanning direction and three columns in the sub-scanning direction. Each pixel 404a is composed of a set of six reflectors, for example. In FIG. 11, only the light beams related to the two optical modulation elements located at both ends are drawn for simplification.

  Thus, according to the optical unit of the second embodiment, it is possible to achieve multi-beam using an optical modulator in both the main scanning direction and the sub-scanning direction. In addition, the amount of light per pixel can be increased by using multiple beams in the main scanning direction.

  The present invention is not limited to the configuration of the above-described embodiment, and any configuration can be used as long as the functions shown in the claims or the functions of the configuration of the present embodiment can be achieved. Is also applicable.

  For example, in the above embodiment, GLV (registered trademark) is used as the optical modulation element. However, the present invention is not limited to this, and any configuration may be used as long as the light modulation element can divide the light beam. May be.

  In this embodiment, a color copying machine is used as the image forming apparatus. However, an electrophotographic image forming apparatus may be used. For example, a facsimile apparatus or a printer apparatus can perform the same operation.

1 is a diagram illustrating an internal configuration of an image forming apparatus according to a first embodiment. It is a figure which shows the optical arrangement | positioning of the optical unit 201 in main scanning. It is a figure which shows the optical arrangement | positioning of the optical unit 201 in subscanning. 3 is a cross-sectional view showing a main part of an optical modulator 304. FIG. 3 is a plan view schematically showing a reflector (ribbon) 51 in the optical modulator 304. FIG. 4 is an enlarged view showing a part of a reflector (ribbon) 51. FIG. FIG. 6 is a perspective view showing a reflection plate 51 for one pixel in an optical modulator 304 together with a support base 52. FIG. 3 is a diagram illustrating an arrangement of optical modulation elements in an optical modulator 304. It is a figure which shows the arrangement | sequence of the other optical modulation element in an optical modulator. It is a figure which shows the optical arrangement | positioning of the optical unit 201 in the main scanning of 2nd Embodiment. It is a figure which shows the optical arrangement | positioning of the optical unit 201 in subscanning. FIG. 4 is a diagram showing an arrangement of optical modulation elements in an optical modulator 404.

Explanation of symbols

201 Optical unit 225 Photosensitive drum surface 301, 401 Semiconductor laser unit 302, 305 Collimator lens 303, 307 Cylindrical lens 304, 404 Optical modulator 404a Optical modulation element (pixel)

Claims (6)

An optical device that focuses light rays and forms an image on a scanned surface,
A plurality of light sources arranged in the sub-scanning direction with respect to the scanned surface and emitting light rays;
An optical modulator having at least a plurality of elements arranged in the sub-scanning direction, independently modulating light beams imaged on each element and dividing the light beams from the plurality of light sources in the sub-scanning direction;
A first optical system for imaging light beams emitted from the plurality of light sources on each element of the optical modulator;
An optical apparatus comprising: a second optical system that focuses each of the plurality of light beams divided in the sub-scanning direction by the optical modulator and forms an image on the surface to be scanned.   The second optical system includes a rotating polyhedron that is divided by the optical modulator and reflects a plurality of light beams condensed in the sub-scanning direction, and the scanned surface is reflected by the light beams reflected by the rotating polyhedron. The optical apparatus according to claim 1, wherein scanning is performed in a main scanning direction. The plurality of light sources are arranged in a sub-scanning direction and a substantially main scanning direction,
The optical modulator has a plurality of elements arranged in the sub-scanning direction and the main scanning direction, and independently modulates the light beam imaged on each element, so that the light beams from the plurality of light sources are in the sub-scanning direction. And dividing the light from the plurality of light sources imaged on each element in the main scanning direction,
The second optical system condenses each of the plurality of light beams divided in the main scanning direction and the sub-scanning direction by the optical modulator and forms an image on the surface to be scanned. 3. The optical device according to 1 or 2. The first optical system includes a first lens that collects light emitted from the plurality of light sources;
A second lens that forms an image of light emitted from the first lens on each element of the optical modulator with respect to a main scanning direction;
The second optical system includes a third lens that condenses a plurality of light beams emitted from the optical modulator in a main scanning direction and a sub scanning direction;
A diaphragm for limiting the width of the light beam that has passed through the third lens;
A fourth lens for condensing a plurality of light beams that have passed through the stop in the sub-scanning direction on the rotating polyhedron,
The optical apparatus according to claim 2, further comprising: a fifth lens that forms an image of the plurality of light beams reflected by the rotating polyhedron on the surface to be scanned. The electrostatic latent image formed on the image carrier is developed with a developer, and the developed image is mounted on an image forming apparatus that forms an image by transferring and fixing the developed image to a transfer target,
The optical apparatus according to claim 2, wherein the light beam is condensed to form an image on a surface to be scanned on the image carrier. An imaging method for condensing rays and forming an image on a scanned surface,
A light beam is emitted by a plurality of light sources arranged in the sub-scanning direction with respect to the scanned surface,
The light beams emitted from the plurality of light sources by the first optical system are imaged on each element of the optical modulator having a plurality of elements arranged at least in the sub-scanning direction,
The light beams imaged on each element by the optical modulator are independently modulated to divide the light beams from the plurality of light sources in the sub-scanning direction,
An image forming method comprising: condensing a plurality of light beams divided in the sub-scanning direction by the second optical system and forming an image on the surface to be scanned.

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