JP2005234110A - Optical scanner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce scanning line curvature happening in an optical scanner in which light is made diagonally incident in the subscanning direction of a deflector. <P>SOLUTION: The optical elements which are closest to a plane to be scanned among optical elements forming a scanning optical system have one and the same figure in a subscanning section. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical scanning device used in an image forming apparatus such as a laser printer or a digital copying machine.

  2. Description of the Related Art Conventionally, an optical scanning device used in an image forming apparatus such as a laser beam printer or a digital copying machine guides a light beam emitted from a light source to a deflecting element by incident optical means, and the light beam deflected by the deflecting element. Are imaged in a spot shape on the surface of the photosensitive drum, which is the surface to be scanned, by the scanning optical means, and the photosensitive drum surface is optically scanned with the luminous flux.

  In such an optical scanning device, the light beam emitted from the light source is converted into substantially parallel light by a collimator lens or the like, and the light beam converted into substantially parallel light for performing tilt correction is lined near the deflection surface by a cylindrical lens. An image is formed. The light beam deflected by the deflecting surface of the deflector scans the surface of the photosensitive drum with a scanning lens at a substantially constant speed to form a spot.

  In FIG. 8, reference numerals 1a, 1b, 1c, and 1d denote light source means, for example, semiconductor lasers. Reference numerals 2a, 2b, 2c and 2d denote cylindrical lenses which have a predetermined refractive power only in the sub-scanning direction. Each element such as the light source means 1 and the cylindrical lens 2 constitutes one element of the incident optical means 51.

  Reference numeral 3 denotes an optical deflector as a deflecting element, which is composed of, for example, a rotating polygon mirror, and is rotated at a constant speed in the direction of arrow A in the figure by driving means (not shown) such as a motor. Reference numeral 11 denotes three fθ lenses having fθ characteristics, which are located between the vicinity of the deflecting surfaces 3a and 3b of the optical deflector 3 and the vicinity of the photosensitive drum surfaces 100a, 100b, 100c and 100d as the scanned surfaces in the sub-scan section. Has a tilt correction function.

Further, in order to form a color image of two or more colors, a plurality of light beams are incident on a single deflector, and the plurality of light beams deflected by the deflector are respectively guided to different scanned surfaces, thereby deflecting. The number of vessels is not increased.
JP 2000-121977

  In the above conventional optical scanning device, the light beam is separated and incident in the sub-scanning direction on the deflecting surface of the deflector in order to separate the light beam, so that the deflector becomes large and the load on the motor (not shown) is large. Therefore, it was necessary to use an expensive motor. Further, since it is necessary to configure the scanning lens corresponding to the number of light beams, there is a problem that the apparatus becomes expensive.

  In order to solve these problems, as disclosed in Patent Document 1, a plurality of incident light beams are incident on the deflector obliquely in the sub-scanning direction, and the deflected light beams are separated by a folding mirror, respectively. It is known to scan on different scanned surfaces. However, the fθ lens described in Patent Document 1 has a thickness of 14 mm or more, a large optical performance deterioration when molded with plastic, and a lens having power in the sub-scanning direction. Since the light beam is incident at the oblique incident angle as described above, there is a problem in that the scanning line curvature on the surface to be scanned is generated as large as 50 μm or more, and image degradation is likely to occur.

  In the present invention, an incident light beam is incident on a deflector in a sub-scanning direction, and each optical element is arranged so that the incident light beam is deflected at substantially the same position on the deflection surface. An inexpensive optical scanning device that guides a plurality of light beams to different surfaces to be scanned is provided. In addition, by configuring the lens closest to the surface to be scanned with a lens formed symmetrically with the optical axis in the sub-scanning section, and disposing the lens in all of the plurality of optical paths corresponding to the plurality of light beams. It is possible to reduce the scanning line curvature and to align the direction of the scanning line curvature on the surface to be scanned, which occurs due to a lens manufacturing error (no color misregistration occurs). Furthermore, by forming at least one scanning lens with a plastic lens, it is possible to provide a color image forming apparatus that is inexpensive and has no color misregistration.

The first aspect of the present invention comprises a light source means, an incident optical system for guiding the light beam emitted from the light source to the deflecting means, and a scanning optical system for forming a spot on the surface to be scanned by the light beam deflected by the deflecting means. An optical scanning device,
The light beam emitted from the incident optical system is incident on the deflecting unit from an oblique direction in the sub-scanning section, and the optical element closest to the scanning surface of the scanning optical system is the optical element of the scanning optical system in the sub-scanning section. The configuration is symmetrical with respect to the optical axis.

A second invention of the present invention is a scanning having a light source means, an incident optical system for guiding a light beam emitted from the light source to the deflecting means, and an optical element for forming a spot on the surface to be scanned by the light beam deflected by the deflecting means. An optical scanning device comprising a plurality of optical systems and guiding the plurality of light beams onto a plurality of different scanned surfaces,
The plurality of light beams emitted from the incident optical system are incident on the deflecting unit from an oblique direction within the sub-scanning section, and are optically closest to the scanning surface among the respective optical elements constituting the plurality of scanning optical systems. The elements have the same shape in the sub-scan section.

  According to the present invention, as described above, the scanning line curve on the scanned surface is made by making the optical element closest to the scanned surface among the optical elements constituting the scanning optical system the same shape in the sub-scanning section. Is corrected.

(Example 1)
FIG. 1 is a sub-scan sectional view of the optical scanning device of the present invention. FIG. 2 is a cross-sectional view of the optical system main scanning in the optical apparatus of the present invention.

  91 is a light source such as a semiconductor laser, and 92 is a collimator lens that converts divergent light from the light source into a substantially parallel light beam.

  Reference numeral 93 denotes an aperture stop that adjusts the diameter of the passing light beam.

  Reference numeral 94 denotes a cylindrical lens as a second optical system, which has a predetermined refractive power only in the sub-scanning direction. After passing through the stop 93, a linear image is formed on the deflecting surface of the deflector within the sub-scanning section. As an image.

  Reference numeral 95 denotes a polygon mirror as a deflector, which rotates at a constant speed in the direction of an arrow.

  Reference numeral 96 denotes an fθ lens as a third optical system, and both 96a and 96b are constituted by an aspherical anamorphic lens in the main scanning plane, and the light beam deflected by the deflector 95 is used as a scanning surface. An image is formed on the drum surface, and the surface tilt of the deflector is corrected.

  FIG. 3 is an optical system sub-scan sectional view in the optical apparatus of the present invention.

  91 is a light source such as a semiconductor laser, and 92 is a collimator lens that converts divergent light from the light source into a substantially parallel light beam.

  Reference numeral 93 denotes an aperture stop that adjusts the diameter of the passing light beam.

  Reference numeral 94 denotes a cylindrical lens as a second optical system, which has a predetermined refractive power only in the sub-scanning direction. After passing through the stop 93, a linear image is formed on the deflecting surface of the deflector within the sub-scanning section. As an image.

  The light beam deflected by the deflecting surface 95A is imaged on a photosensitive drum surface as a scanned surface by an fθ lens 96 as a third optical system.

  As shown in FIG. 1, the optical scanning device of the present embodiment is configured by using a plurality of optical systems shown in FIGS. 2 and 3, but the optical characteristics are all the same.

  The fθ lens 96 in this embodiment is expressed using a function of the following formula.

The origin is the intersection of the fθ lens and the optical axis,
As shown in FIG. 2, on the scanning start side and the scanning end side with respect to the optical axis, the optical axis is the X axis, the direction perpendicular to the optical axis in the main scanning plane is the Y axis, and the optical axis is orthogonal to the sub scanning plane. The direction to be taken is the z axis, and can be expressed by the following continuous function.

  Scanning start side,

Scan end side,

R is a radius of curvature, and K, B4, B6, B8, and B10 are aspherical coefficients.

  In this embodiment, the shape in the main scanning direction is configured symmetrically with respect to the optical axis, that is, the aspheric coefficients on the scanning start side and the scanning end side are made to coincide.

  The sub-scanning direction is a scanning start side and a scanning end side with respect to the optical axis, and the curvature in at least one sub-scanning surface (a surface including the optical axis and perpendicular to the main scanning surface) of the fθ lens 96 is set. The lens is continuously changed in the effective portion of the lens, and the shape in the main scanning direction is configured symmetrically with respect to the optical axis.

  As shown in FIG. 3, the shape in the sub-scanning direction is such that the optical axis is the X-axis on the scanning start side and the scanning end side with respect to the optical axis, the Y-axis is the direction perpendicular to the optical axis in the main scanning plane, The direction orthogonal to the optical axis in the scanning plane is the Z axis, and can be expressed by the following continuous function.

  Scanning start side,

Scan end side,

(R ′ is the radius of curvature in the sub-scanning direction, and D ₂ , D ₄ , D ₆ , D ₈ , and D ₁₀ are coefficients)
The coefficient suffix S represents the scanning start side, and e represents the scanning end side.

  The sub-scanning direction radius of curvature is a radius of curvature in a cross section perpendicular to the shape (bus line) in the main scanning direction.

  In this embodiment, in order to correct focus correction (field curvature correction) in the sub-scanning direction and uniformity of magnification in the sub-scanning direction (fluctuation of spot diameter due to image height) in the fθ lens, the most scanning side is used. The sub-scanning curvature radius of the surface (r4 surface) on the scanning surface side of the lens (G2) is continuously changed. Usually, the sub-scanning curvature radius is changed by changing at least two planes, and both are corrected. However, in the present embodiment, since the uniformity of the magnification is corrected by the shape in the main scanning direction, The curvature of field is corrected by changing only one surface.

  In other words, in this embodiment, in the effective image area, the field curvature in the sub-scanning direction due to the image height is within ± 10%, and the magnification in the sub-scanning direction due to the image height is within ± 10%. The scanning line curvature that occurs because the light beam is incident on the deflection surface at an oblique incidence in the scanning direction is realized within ± 10%.

  Next, means and effects for achieving the object of the present invention will be described.

  The fθ lens 96 of the present embodiment is made of a plastic lens, and the shape in the main scanning direction is configured on the scanning start side and the end side so as to be advantageous in molding. Further, at least one surface has a continuously changing radius of curvature in the sub-scanning direction to correct field curvature, wavefront aberration, and spot diameter fluctuation. Further, in the present embodiment, the scanning line curvature and the deterioration of the wavefront aberration that occur because the light beam is incident on the deflection surface at an oblique incidence in the sub-scanning direction are corrected by the eccentricity of the G2 lens.

  Further, since the incident light beam from the light source is incident at an angle α (≠ 0) with respect to the optical axis in the main scanning section, the entrance / exit (sag) of the surface accompanying the rotation of the deflector 95 starts scanning. Therefore, in order to correct asymmetry, the curvature in the sub-scanning direction is changed asymmetrically with respect to the optical axis.

  The optical scanning / scanning apparatus of the present invention is the most deflector side so that two light beams incident on substantially the same position of the deflection surface at the same angle from two different directions pass through a symmetrical position across the optical axis of the lens. Lens (G1). Since the plurality of incident light beams are deflected at substantially the same position in the sub-scanning direction of the deflection surface, the deflection surface can be configured to be low. Further, since the G1 lens has a substantially flat radius of curvature in the sub-scanning direction and has almost no power in the sub-scanning direction, the optical performance is prevented from deteriorating due to the light beam passing off-axis.

  The light beam incident on the deflecting surface obliquely from below in FIG. 3 is reflected by the first folding mirror after passing through the G1 lens, passes through the lens (G2) closest to the surface to be scanned, and is reflected by the second folding mirror. Then, after passing through the dust-proof glass composed of a flat plate, the surface of the photosensitive drum as the surface to be scanned is scanned. 3 passes through the G1 lens, then passes through the G2 lens, is reflected by the third folding mirror, and scans the drum surface as the surface to be scanned.

  As shown in FIG. 6, in the G2 lens of FIG. 3, the point connecting the vertexes of the child plane in the generatrix direction is a straight line (indicated by a broken line in the figure), and this straight line is parallel to the normal line of the deflection surface. . Further, the optical axis of the G2 lens is parallel to the perpendicular bisector of the surface to be scanned in the main scanning section, and is shifted by Δ = 1.456 mm with respect to the optical axis of the G1 lens.

  As shown in FIG. 7, the shape of the G2 lens in the sub-scan section is formed symmetrically with the optical axis (plane vertex of the child line) in between. This has the advantage that if the optical axis is sandwiched and the shape is asymmetric, the bus bar can be prevented from being bent in the sub-scanning direction (lens is warped) during lens molding. Further, in an optical apparatus that deflects and scans four light beams with a single deflector as in this embodiment, a lens whose curvature radius in the sub-scanning direction changes asymmetrically with respect to the optical axis (in this embodiment Since the relationship between the scanning start side and the scanning end side of the G2 lens cannot be used by being reversed in the main scanning section, the lens is asymmetric in the sub-scanning section (the vertex of the child line plane is in the sub-scanning direction with respect to the lens center). In the case of a decentered lens), it is necessary to configure with two types of lenses having different decentering directions. In addition, if a G2 lens having a different shape is used in the apparatus, the optical characteristics deteriorate due to errors or variations in lens molding.

  Furthermore, in this embodiment, since the optical axes of the two fθ lenses are configured to be parallel and perpendicular to the deflection surface, the lens mounting accuracy when mounting to the optical box is inclined. It has the merit that it is higher than the system and the optical performance is hardly deteriorated.

  Table 1 shows the optical parameters of the present embodiment.

The fθ lens 96 has a positive meniscus shape with a convex surface facing the surface to be scanned, and has a curvature in at least one sub-scanning surface (a surface that includes the optical axis and is orthogonal to the main scanning surface) of 96a and 96b. In the effective portion of the lens, it is changed continuously and substantially symmetrically with respect to the optical axis, and the asymmetry of the field curvature and the variation of the spot diameter are corrected simultaneously.

  As shown in FIG. 3, the G2 lens is arranged with a decentering of 1.456 mm with respect to the optical axis of the G1 lens in the sub-scanning section, and the deterioration of wavefront aberration caused by oblique incidence and the scanning line on the scanned surface. Curvature is reduced. Further, the G2 lens is decentered downward with respect to the light beam incident from above in FIG. 3, and the same amount is decentered upward with respect to the light beam incident from below, as shown in FIG. The optical flux (scanning line curve) is corrected by the light fluxes passing through each passing through positions opposite to the optical axis of the G2 lens in the sub-scan section. With this arrangement, when the lens is along the sub-scanning direction due to manufacturing errors of the G2 lens, the scanning line curve direction on the surface to be scanned when aligned along the same direction may be aligned. Further, there is an advantage that no color shift occurs if the warp is the same amount.

  In the present embodiment, the sub-scanning curvature changing surface is composed of one surface, and the rough surface is changed substantially symmetrically with respect to the optical axis without having an extreme value off the axis, thereby favorably correcting the wavefront aberration. ing. Further, the fθ lens has a shape in the main scanning direction symmetrical with respect to the vertical bisector of the surface to be scanned 97 so as to be advantageous in molding, and the lens on the most deflector side has a curvature in the sub-scanning direction. The radius is infinite, and there is almost no power in the sub-scanning direction. The imaging performance in the sub-scanning direction is corrected only on the most non-scanning surface of the lens on the most non-scanning surface side. As shown in FIG. 4, the optical characteristics are well corrected in both the main scanning direction and the sub-scanning direction.

  In this embodiment, the fθ lens 76 is composed of two lenses. However, the fθ lens may be three or more, and the same effect can be obtained even when an optical element such as a diffraction element is used. Can be obtained. Furthermore, although a single beam laser is used as the light source, the same effect can be obtained by using a multi-beam laser having a plurality of light emitting points of two or more.

  That is, one or more lenses, a diffractive optical element, and a curved mirror may be arranged between the G1 lens 96a and the G2 lens 96b.

  As described above, in an optical scanning device that guides a plurality of light beams having an angle in the sub-scanning direction onto different surfaces to be scanned by a single deflector, the incident light beam is deflected at substantially the same position on the deflection surface. By reducing the height of the deflection surface, reducing the load on the motor, and configuring multiple lenses with the same shape for multiple incident light beams, optical performance caused by manufacturing errors, etc. It is possible to obtain a high-performance optical scanning device that prevents deterioration and has little color misregistration.

(Example 2)
The difference of the present embodiment from the first embodiment is that the G1 lens is composed of an aspheric lens made of a glass mold, and other configurations and effects are the same as those of the first embodiment.

  Among the fθ lenses 86 of the present embodiment, the G1 lens is made of a glass mold, and the shape in the main scanning direction is configured on the scanning start side and the end side so as to be advantageous for molding. Further, at least one surface has a continuously changing radius of curvature in the sub-scanning direction, and corrections for field curvature, wavefront aberration, and spot diameter variation are made. Further, since the sag amount is small as in the first embodiment, the curvature radius in the sub-scanning direction is changed substantially symmetrically with respect to the optical axis, and the change is an extreme value in order to satisfactorily correct the wavefront aberration. It changes without having two or more.

  In the present embodiment, the curvature radius in the sub-scanning direction of the lens on the most deflector side and the surface on the deflector side (r3 surface) of the lens on the most non-scanning surface side are set to | r | = 1000. In general, molding has a merit that it is difficult to form a flat surface, and the optical surface tends to be habitual, so that it is advantageous in molding to have a loose curvature (| r | ≧ 100). is there. Further, by using glass for the G1 lens, it is possible to reduce deterioration of optical performance due to environmental fluctuations (temperature, humidity). In this embodiment, since the power in the main scanning direction is substantially concentrated on the G1 lens, the optical characteristics in the main scanning direction are less susceptible to environmental changes.

  Also in the present embodiment, as in the first embodiment, the imaging performance in the sub-scanning direction is corrected only by the surface closest to the surface to be scanned, and the G2 lens of each of the four stations has the same shape. Scan line curve degradation caused by manufacturing errors is reduced.

  As described above, in this embodiment, the lens on the most non-scanning surface side is composed of an aspherical lens made of a glass mold, optical performance deterioration due to environmental changes is reduced, and a high-performance optical scanning device with less color misregistration. Can be obtained.

(Example 3)
The difference of this embodiment from Embodiment 1 is that a monolithic multi-beam laser having a plurality of light emitting points in the same chip is used as the light source. Other configurations and effects are the same as those of the first embodiment.

  The light source of the present embodiment is configured by four monolithic multi-beam lasers each having two laser chips arranged side by side, and two beams are substantially parallel on each of the four photosensitive drum surfaces. It is comprised so that it may scan.

  In the fΘ lens of this embodiment, since the lateral magnification in the sub-scanning direction is constant regardless of the image height, the interval between the two beams on the same photosensitive drum surface is constant. Further, at least one surface has a continuously changing radius of curvature in the sub-scanning direction, and corrections for field curvature, wavefront aberration, and spot diameter variation are made. Further, since the sag amount is small as in the first embodiment, the curvature radius in the sub-scanning direction is changed substantially symmetrically with respect to the optical axis, and the change is an extreme value in order to satisfactorily correct the wavefront aberration. It changes without having two or more.

  In the present embodiment, a monolithic multi-beam laser is used as a light source, and not only a higher-speed optical scanning device can be obtained, but also applied to an image forming apparatus having the same number of printed sheets as an optical scanning device configured with a single beam laser. In this case, the rotational speed of the polygon motor can be reduced, and an inexpensive motor can be used.

  As described above, in this embodiment, it is possible to obtain a high-performance optical scanning device in which the light source is constituted by a monolithic multi-beam laser and is faster and has less color misregistration.

[Image forming apparatus]
FIG. 9 is a cross-sectional view of the main part in the sub-scanning direction showing the embodiment of the image forming apparatus of the present invention. In FIG. 9, in FIG. 9, 60 is a color image forming apparatus, 11 is a scanning optical apparatus having any one of the configurations shown in the first to third embodiments, and 21, 22, 23, and 24 are each an image carrier. Each of the photosensitive drums 31, 32, 33, and 34 is a developing unit, and 51 is a conveyance belt.

  In the figure, R (red), G (green), and B (blue) color signals are input to the color image forming apparatus 60 from an external device 52 such as a personal computer. These color signals are converted into C (cyan), M (magenta), Y (yellow), and B (black) image data (dot data) by a printer controller 53 in the apparatus. These image data are respectively input to the scanning optical device 11. From these scanning optical devices, light beams 41, 42, 43, and 44 modulated according to each image data are emitted, and the photosensitive surfaces of the photosensitive drums 21, 22, 23, and 24 are caused by these light beams. Scanned in the main scanning direction.

  In this embodiment, the color image forming apparatus emits light beams corresponding to the respective colors of C (cyan), M (magenta), Y (yellow), and B (black) from one scanning optical device (11). Image signals (image information) are recorded on the drums 21, 22, 23, and 24, and color images are printed at high speed.

  In the color image forming apparatus according to the present embodiment, as described above, the single scanning optical device 11 uses the light beam based on the respective image data to convert the latent images of the respective colors onto the corresponding photosensitive drums 21, 22, 23, and 24. Is formed. Thereafter, a single full color image is formed by multiple transfer onto a recording material.

  As the external device 52, for example, a color image reading device including a CCD sensor may be used. In this case, the color image reading apparatus and the color image forming apparatus 60 constitute a color digital copying machine.

Sub-scan sectional view of the optical scanning device according to the first embodiment. Optical system main-scan sectional view of the first embodiment Optical system sub-scan sectional view of Example 1 The figure which shows the optical performance of the present Example 1 The figure which shows the main scanning cross section of the f (theta) lens of this invention The figure which shows the subscanning cross section of the f (theta) lens of this invention The schematic diagram which shows the beam passage position on the f (theta) lens of this invention Conventional optical scanning device Image forming apparatus of the present invention

Explanation of symbols

91 Light source such as semiconductor laser 92 Collimator lens 93 Aperture stop 94 Cylindrical lens 95 Polygon mirror 96 fθ lens

Claims (15)

An optical scanning device comprising: a light source means; an incident optical system that guides a light beam emitted from the light source to a deflection means; and a scanning optical system that forms a spot on the surface to be scanned by the light beam deflected by the deflection means,
The light beam emitted from the incident optical system is incident on the deflecting unit from an oblique direction in the sub-scanning section, and the optical element closest to the scanning surface of the scanning optical system is the optical element of the scanning optical system in the sub-scanning section. An optical scanning device having a symmetrical shape with respect to an optical axis.   The scanning optical system includes a plurality of optical elements, and the optical element closest to the scanned surface of the scanning optical system is eccentric with respect to the optical axis of the scanning optical system closest to the deflecting unit. The optical scanning device according to claim 1.   3. The optical scanning device according to claim 1, wherein an optical axis of the scanning optical system is disposed in parallel with a normal line of a deflection surface of the deflecting unit.   The optical scanning device according to claim 1, wherein at least one optical element of the scanning optical system is a plastic lens.   5. The optical scanning device according to claim 1, wherein the deflecting unit scans a plurality of light beams on different scanning surfaces.   6. The optical scanning device according to claim 1, wherein the light source means is constituted by a monolithic multi-beam laser.   The optical scanning device according to claim 1, the photosensitive member disposed on the surface to be scanned, and electrostatic formed on the photosensitive member by a light beam scanned by the optical scanning device. An image forming apparatus comprising: a developing device that develops a latent image as a toner image; a transfer device that transfers the developed toner image onto a transfer material; and a fixing device that fixes the transferred toner image onto the transfer material. .   An image forming apparatus comprising: the optical scanning device according to claim 1; and a printer controller that converts code data input from an external device into an image signal and inputs the image signal to the optical scanning device. A plurality of scanning optical systems having a light source means, an incident optical system that guides the light beam emitted from the light source to the deflecting means, and an optical element that forms a spot on the surface to be scanned. An optical scanning device that guides the luminous flux of light onto a plurality of different scanned surfaces,
The plurality of light beams emitted from the incident optical system are incident on the deflecting unit from an oblique direction within the sub-scanning section, and are optically closest to the scanning surface among the respective optical elements constituting the plurality of scanning optical systems. An optical scanning device characterized in that the elements have the same shape in the sub-scan section.   The optical scanning device according to claim 9, wherein the optical element closest to the surface to be scanned is a mold lens.   The plurality of light beams emitted from the incident optical system have different passing positions in the sub-scanning section of each optical element constituting the plurality of scanning optical systems corresponding to the plurality of light beams. The optical scanning device according to 9 or 10.   By making the optical element closest to the scanned surface among the respective optical elements constituting the plurality of scanning optical systems the same shape in the sub-scanning cross section, the scanning line curvature on the scanned surfaces can be reduced. The optical scanning device according to claim 9, wherein the optical scanning device is corrected.   13. The optical scanning device according to claim 9, wherein the light source means is composed of a monolithic multi-beam laser.   An optical scanning device according to any one of claims 9 to 13, a photosensitive member disposed on the surface to be scanned, and an electrostatic formed on the photosensitive member by a light beam scanned by the optical scanning device. An image forming apparatus comprising: a developing device that develops a latent image as a toner image; a transfer device that transfers the developed toner image onto a transfer material; and a fixing device that fixes the transferred toner image onto the transfer material. .   An image forming apparatus comprising: the optical scanning device according to claim 9; and a printer controller that converts code data input from an external device into an image signal and inputs the image signal to the optical scanning device.

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