JP5240036B2 - Optical scanning apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to an optical scanning device incorporated in an image forming apparatus such as a digital copying machine, a laser printer, a facsimile, or a composite machine thereof, and more particularly, to a lens system that forms an image on a scanned medium with light that has been deflected and scanned. The present invention relates to an optical scanning device provided and a scanning line tilt adjustment of an image forming apparatus provided with the optical scanning device.

  In an image forming apparatus such as a digital copying machine, a laser printer, a facsimile machine, or a complex machine of these, light from a light source is emitted as one of means for forming an electrostatic latent image on a photoconductor as an image carrier. 2. Description of the Related Art An optical scanning device is used that deflects and scans with a deflecting device, forms an electrostatic latent image on the photoconductor by forming an image on the photoconductor that is a scanned medium through a lens system. However, it has been conventionally known that a horizontal line printing inclination due to a scanning line inclination occurs due to a manufacturing error of components of the optical scanning device or mounting variations.

As a so-called skew correction method for correcting the scanning line inclination, for example, in Japanese Patent Laid-Open No. 10-133130, skew correction is performed by changing the installation angle of the folding mirror.
As other methods, in Patent Document 2 (Japanese Patent Laid-Open No. 2008-256862) and Patent Document 3 (Japanese Patent Laid-Open No. 2005-189791), only a long lens that is close to the scanning medium among the Fθ lenses is light-transmitted. The scanning line is corrected by turning around the axis.
Further, in Patent Document 4 (Japanese Patent Laid-Open No. 11-268336), skew correction is performed by tilting the entire optical scanning device.
Further, in Patent Document 5 (Japanese Patent Laid-Open No. 7-120692), the focal position shift of the photosensitive drum surface is adjusted by adjusting the interval between the rotating polygon mirror surface and the photosensitive drum surface so as to be fixed. .

As described above, proposals have conventionally been made to adjust the inclination of the horizontal line of a printed matter by adjusting the inclination of the scanning line, but not all the problems have been solved.
For example, in the configuration of the optical scanning device disclosed in Patent Document 1, the installation angle of the folding mirror is changed in order to correct the scanning line inclination. However, in this case, since the optical path length to the scanned medium changes, the imaging position changes. Therefore, there is a problem that the spot diameter on the scanned medium increases. In particular, when scanning with a high-definition spot, a slight increase in the spot diameter may cause a large increase in the spot diameter.

  In the configurations shown in Patent Documents 2 and 3, only the long lens closest to the scanning medium of the Fθ lens system is rotated about the optical axis in order to correct the scanning line inclination. However, in this case, since the arrangement of the Fθ lens system with other lenses changes, there is a problem that the aberration increases and the spot diameter increases. In particular, when the number of scanning beam light sources is five and arranged in one row, or when the number of light sources is nine and arranged in 3 × 3 rows, the magnification ratio in the sub-scanning direction is the scanning position. If they differ, there is a problem that a difference in scanning interval is large, and print quality deteriorates due to uneven pitch.

  A specific example of this pitch unevenness is shown in FIG. FIG. 9 is a schematic diagram when horizontal lines are printed by an optical scanning device using three-beam scanning. The scanning center portion has a spacing P0, but the end portion has P1 due to the difference in sub-scanning direction magnification ratio. The interval P2 with the next scan is obtained by 3P0-2P1. If the difference between P1 and P2 is large, large pitch unevenness occurs. Since P2 is nP0− (n−1) P1 when the number of light sources is n, the difference between P1 and P2 increases as n increases even if there is a difference in the same magnification ratio in the sub-scanning direction. If there were many, it was a problem.

  In the configuration disclosed in Patent Document 4, the entire scanning optical system is tilted in order to correct the scanning line tilt. However, in this case, since an adjustment mechanism is provided outside the scanning optical system, a space for it is necessary. In addition, when the scanning width is as wide as about 500 mm, the scanning optical system is large, and it is difficult to adjust the entire scanning optical system by tilting it, and it is difficult to hold it with high precision. This is a problem because it requires a special mechanism. Further, in this case, since the reference of the scanning optical system changes, there is a problem that the position adjustment of the scanning light beam needs to be performed on the actual machine and the productivity is deteriorated.

  In the configuration shown in Patent Document 5, the focal position shift related to the spot in the sub-scanning direction caused by the assembly error of the optical scanning optical device is performed by moving the rotary polygon mirror position, and the scan line inclination is adjusted. is not. Further, the cause of the increase in the spot diameter in Patent Documents 2 and 3 is not due to the focal position shift, but due to the increase in the sub-scanning direction magnification ratio and aberration described above. The increase in spot diameter and pitch unevenness cannot be solved.

The present invention has been made in view of the above circumstances, and provides an optical scanning device having a configuration in which spot diameter increase and pitch unevenness do not occur even when the scanning line inclination is adjusted, and an image forming apparatus including the optical scanning device. For the purpose.
Note that the present invention is an invention relating to the adjustment of the scan line inclination, and does not adjust the overall curve of the scan line, that is, the so-called bow.

In order to achieve the above object, the present invention employs the following solutions.
The first means of the present invention includes a plurality of light sources, a first lens system that guides light from the light sources, a light deflector that deflects and scans light from the first lens system, and the light deflector And a second lens system for forming an image of the light deflected and scanned on the scanned medium by rotating the lens except the spherical lens constituting the second lens system about the optical axis. It has a means to fix.

The second means of the present invention is the optical scanning device according to claim 1 , wherein the arrangement of the light sources is one row, and the fixed position of the second lens system is a position where the scanning line inclination is substantially zero. The arrangement angle of the light sources is changed, and the scanning interval is fixed at a predetermined interval .

Third means of the present invention is to provide an optical scanning apparatus according to claim 1 Symbol placement, arrangement of the light source in two dimensions, the second scan line tilt the fixing position of the lens system is a position at which the outline 0 Then, the magnification of the first optical system is changed, and the scanning interval is fixed at a predetermined interval.
The fourth means of the present invention includes a plurality of light sources, a first lens system that guides light from the light sources, a light deflecting device that deflects and scans light from the first lens system, and the light. In an optical scanning device having a second lens system that forms an image of light deflected and scanned by the deflection device on a scanned medium,
The second lens system has means for rotating and fixing about the center of the optical axis, and the center of rotation of the second lens system is the scanning center and the lower part of the lens .

The fifth means of the present invention includes a plurality of light sources, a first lens system that guides light from the light sources, a light deflecting device that deflects and scans light from the first lens system, and the light deflecting device. And a second lens system for forming an image of the light deflected and scanned on the scanned medium by rotating the lens except the spherical lens constituting the second lens system about the optical axis. and means for securing is, is characterized in that the rotational center of the second lens system to scan the center a and lens bottom.
According to a sixth means of the present invention, in the optical scanning device according to any one of the first to third means, the rotation center of the second lens system is the lens center. is there.

  According to a seventh aspect of the present invention, there is provided an image forming apparatus, and the optical scanning of any one of the first to sixth means is used as a means for forming an electrostatic latent image on an image carrier that is a scanned medium. A device is provided.

  The eighth means of the present invention includes an image carrier that is a scanned medium, a charging device that charges the image carrier, and electrostatic information corresponding to image information to be recorded by scanning light from a light source. An optical scanning device for forming a latent image on the image carrier, a developing device for forming a toner image by attaching toner to the electrostatic latent image, and recording the toner image directly or via an intermediate transfer medium In an image forming apparatus comprising a transfer device for transferring onto a medium and a fixing device for fixing the transferred toner image on a recording medium, any one of the first to sixth means is used as the optical scanning device. An optical scanning device is provided.

According to the optical scanning device of the first aspect of the present invention, Ri by have a means for fixing by rotating the lens except the spherical lenses of the second lens system schematic optical axis center, run査線Even if the tilt is adjusted, there is an effect that the spot diameter does not increase and pitch unevenness does not occur.In addition, since the number of lenses rotated around the optical axis can be reduced, the structure can be simplified, and the optical axis is centered. Since the number of rotating lenses can be reduced, the structure can be simplified.

According to the optical scanning device of the second means of the present invention, in addition to the effect of the first means, even if the scanning interval is slightly changed after adjusting the scanning line inclination, the light source arrangement is two-dimensional. There is an effect that the scanning interval can be adjusted to an appropriate value.
According to the optical scanning device of the third means of the present invention, in addition to the effect of the first means, the light source array is two-dimensional even if the scanning interval slightly changes after adjusting the scanning line inclination. In this case, if the magnification of the first optical system is changed, the scanning interval can be adjusted to an appropriate value.

According to the optical scanning device of the fourth and fifth means of the present invention, in addition to the effect of any one of the first to third means, the rotation center of the second lens system is at the scanning center and at the lower part of the lens. By doing so, there is an effect that the rotation mechanism can be simplified.
According to the optical scanning device of the sixth means of the present invention, in addition to the effect of any one of the first to third means, the rotation center of the second lens system is set to the center of the second lens. By doing so, there is an effect that an increase in spot diameter and scanning pitch unevenness can be minimized.

  According to the image forming apparatus of the seventh or eighth means of the present invention, since the optical scanning device of any one of the first to sixth means is provided, the spot diameter can be adjusted even if the scanning line inclination is adjusted. There is an effect that it is possible to obtain an image forming apparatus with little increase and uneven scanning pitch.

1 is a perspective view of an optical scanning device according to a first embodiment of the present invention. It is a top view of the optical scanning device concerning the 1st example of the present invention. 1 is a schematic configuration diagram of an image forming apparatus using an optical scanning device according to a first embodiment of the present invention. It is a schematic block diagram of the scanning-line inclination adjustment mechanism of the optical scanning device based on 1st Example of this invention. It is a figure which shows the spot arrangement | sequence on a photoconductor in case a light source arrangement | sequence is one-dimensional. It is a schematic block diagram of the scanning-line inclination adjustment mechanism of the optical scanning device based on 2nd Example of this invention. It is a perspective view of the optical scanning device concerning the 3rd example of the present invention. It is a figure which shows the spot arrangement | sequence on a photoreceptor in case a light source arrangement | sequence is two-dimensional. It is a figure which shows the mode of horizontal line printing when a subscanning direction magnification ratio differs in a scanning direction. It is a table | surface which shows the structural example of a 2nd lens system. It is Numerical formula 1 which shows the shape of the resin both-sides aspherical lens of a 2nd lens system. It is Numerical formula 2 which shows the shape of the resin-made both-sides aspherical lens of a 2nd lens system. It is a table | surface which shows the coefficient of an aspherical shape. It is the figure which showed the relationship between the RMS spot diameter when not adjusting scanning line inclination, and image height. It is a figure showing the relationship between the RMS spot diameter and the image height when only one resin-made aspherical lens on both sides is rotated about the optical axis to adjust the scanning line tilt. It is the figure which showed the relationship between the RMS spot diameter and image height at the time of rotating the whole 2nd lens system centering on an optical axis center, and adjusting a scanning line inclination. It is the figure which showed the bending condition of the scanning line at the time of rotating only a single resin both-sides aspheric lens centering on an optical axis, and adjusting a scanning line inclination. It is the figure which showed the bending condition of the scanning line at the time of rotating the whole 2nd lens system centering on an optical axis center, and adjusting a scanning line inclination.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. The following explanation is an example as a preferred form of the present invention, and the present invention is not limited to this example.

[First embodiment]
The configuration of the first embodiment of the present invention will be described with reference to FIGS. 1, 2, 3, 4, and 5. FIG. FIG. 1 is a perspective view of an optical scanning device according to a first embodiment of the present invention. FIG. 2 is a plan view of the optical scanning device according to the first embodiment of the present invention. FIG. 3 is a schematic configuration diagram of an image forming apparatus using the optical scanning device. FIG. 4 is a schematic configuration diagram of the scanning line tilt adjusting mechanism of the optical scanning device according to the first embodiment of the present invention, and is a view of the lens base 1 as viewed from the folding mirror 28 side. FIG. 5 is a diagram showing a spot arrangement on an image carrier (specifically, a photoconductive photoconductor) 18 as a scanned medium.

First, a schematic configuration of an image forming apparatus according to an embodiment of the present invention will be described with reference to FIG.
The image carrier for forming the toner image is a drum-shaped photoconductor 18 in the illustrated example, and this photoconductor 18 is rotated clockwise at a constant peripheral speed by a motor (not shown). The photosensitive member 18 is uniformly charged to a specific polarity by the charging device 10 and then exposed to light from an optical scanning device 11 described later to form an electrostatic latent image corresponding to recorded image information. A developing device 12 is disposed downstream of the exposure position in the photoconductor rotation direction, and a toner image is formed on the photoconductor 18 by the developing device 12.

  The printing paper 13 that is a recording medium is conveyed by a conveying device 14 such as a conveying roller pair. Thereafter, the transfer device 15 charges the back surface of the printing paper 13 with a polarity opposite to that of the toner, and transfers the toner image on the photoconductor 18 onto the printing paper 13. After the transfer, the toner on the photoreceptor 18 that has not been transferred is removed by the cleaning device 16. The printing paper 13 having the toner image transferred from the photoreceptor 18 is conveyed to the fixing device 17. The fixing device 17 includes a heat roller 17a that is controlled to be heated to a constant temperature, and a pressure roller 17b that is in contact with the heat roller 17a. When passing through the nip portion between the heat roller 17 a and the pressure roller 17 b of the fixing device 17, the toner image held on the printing paper 13 is heated, pressurized and melted and fixed on the printing paper 13. After the fixing process, the printing paper 13 is discharged and stored in a paper discharge tray or a post-processing device outside the image forming apparatus.

Next, the optical scanning device 11 will be described. 1 and 2 are schematic configuration diagrams showing the internal configuration of the optical scanning device 11. A light beam 21 emitted from a light source device 20 having a plurality of light source elements (for example, a plurality of semiconductor laser elements or a semiconductor laser array in which a plurality of light emitting elements are arranged in one row or two-dimensionally) is a first lens. Lenses 25a and 25b constituting an Fθ lens system which is a second lens system, which passes through a cylindrical lens 23 having a predetermined curvature only in the sub-scanning direction constituting the system and is deflected and scanned by a rotary polygon mirror 24 which is an optical deflection device. , 25c, reflected by the folding mirror 28, and imaged on the photosensitive member 18 which is the medium to be scanned to form an electrostatic latent image. The arrow direction X in FIG. 2 indicates the light scanning direction (referred to as main scanning direction).
A part of the light beam deflected and scanned by the rotating polygon mirror 24 is guided to the optical sensor 27 by the mirror 26, and intensity modulation of the light beam 21 emitted from the light source device 20 is started by the signal.
1 and 2 show only the cylindrical lens 23 as the first lens system, an optical element that changes the magnification of a collimating lens, a coupling lens, a zoom lens, which will be described later, or the like as necessary. Is provided.

  FIG. 1 is a perspective view of a scanning line inclination adjusting unit (scanning line inclination adjusting mechanism) of the optical scanning apparatus 11 according to the first embodiment of the present invention, and FIG. A scanning line inclination adjusting mechanism) is shown in plan view. FIG. 4 is a schematic configuration diagram of the scanning line inclination adjusting mechanism as viewed from the folding mirror 28 side in FIGS. 1 and 2. The scanning line inclination adjusting unit (scanning line inclination adjusting mechanism) according to the present invention adjusts the scanning line inclination, but also has a function of adjusting the scanning line bending as described later.

  The scanning line tilt adjusting mechanism shown in FIGS. 1, 2, and 4 is means for rotating and fixing the second lens system about the optical axis. In this scanning line tilt adjusting mechanism, the lenses 25a, 25b, and 25c constituting the second lens system (Fθ lens system) are held by the lens base 1, and the lens base 1 is parallel to the light beam at the scanning center. Two shafts 5 are provided at the center of the lens base 1. The two shafts 5 of the lens base 1 are rotatably supported by a bearing 2 fixed to the optical base 6, and the optical axes of the lenses 25a, 25b, and 25c, in which the lens base 1 is an approximate Fθ lens system. It is configured to be able to rotate around the vicinity. Further, an adjustment screw 3 is provided for adjusting the rotation of the lens base 1, and the adjustment screw 3 is configured to penetrate the hole of the lens base 1 and enter the screw hole in the optical base 6. On the other hand, a spring 4 is mounted on the opposite side of the adjustment screw 3 so that a force that attracts the lens base 1 and the optical base 6 works. In this configuration, when the adjustment screw 3 is tightened, the adjustment screw 3 side changes downward and the opposite side changes upward. In accordance with this movement, the entire second lens system (Fθ lens system) is rotated about the optical axis center, and the scanning line on the photosensitive member 18 is also tilted, so that the scanning line tilt can be adjusted. The adjustment position of the adjustment screw 3 may be fixed at a position where the inclination of the scanning line on the photoconductor 18 is approximately zero.

  The light source elements in the light source device 20 of the present embodiment are arranged in a line, and the light spots are arranged in a line on the photoconductor 18 that is a scanned medium. FIG. 5 shows a state in which five light spots 50 are arranged on the photosensitive member 18. When the light source element is rotated about the optical axis, the arrangement angle θ of the light spot 50 on the photoconductor 18 changes, and the scanning interval d changes accordingly. Therefore, the scanning interval d can be adjusted by changing the array angle θ. Therefore, after the scan line inclination adjustment, if the scan interval changes, readjustment may be performed in this way.

In the present invention, since the mounting position and angle of the folding mirror 28 are not changed, the optical path length from the second lens system (Fθ lens system) to the photosensitive member 18 does not change, so that the focal position shift does not occur. The upper spot diameter does not increase. However, when only one of the lenses 25a, 25b, and 25c constituting the second lens system (Fθ lens system) is rotated around the optical axis to adjust the inclination of the scanning line, at the scanning end portion In the second lens system (Fθ lens system), a position shift in the sub-scanning direction with another lens occurs, and aberration and magnification change depending on the image height. As a result, the spot diameter increases and scanning pitch unevenness occurs.
Therefore, in the present invention, the entire second lens system (Fθ lens system) is rotated around the optical axis by the above-described scanning line tilt adjusting mechanism to adjust the scanning line tilt, and is thereby fixed. In the entire scanning range, there is no relative displacement between the lenses 25a, 25b, and 25c in the second lens system. For this reason, since the aberration and magnification do not change with the image height, an increase in spot diameter and uneven scanning pitch do not occur.

Here, a specific example of the second lens system used in the optical scanning device of the present embodiment will be shown. It is assumed that the number of light sources examined here is 5, the element spacing is 60 μm, the arrangement of one row and the print dot density is 1200 dpi. 1 and 2, three lenses 25a, 25b, and 25c are shown as the second lens system, but in the following specific example, the second lens system has a five-lens configuration.
FIG. 10 is a table showing a configuration example of the second lens system (5 lens configuration). The surface number (1) in the table of FIG. 10 is the reflecting surface of the rotating polygon mirror 24, and the surface numbers (2) and (3) are the entrance / exit surfaces of the window of the rotating polygon mirror 24. Surface numbers (4) to (13) are the surfaces of the lenses constituting the second lens system, and surface numbers (4) and (5) are the entrance / exit surfaces of the spherical lens A on both sides, and the surface number (6). (7) is the entrance / exit surface of the spherical lens B on both sides, and the surface numbers (8) and (9) are the entrance / exit surfaces of the toric lens. The entrance side of the surface number (8) is the plane and the surface number (9) is exited. The side is a toric surface. Surface numbers (10) and (11) are the entrance and exit surfaces of the cylinder lens. The entrance side of the surface number (10) is the cylinder surface in the sub-scanning direction, and the exit side of the surface number (11) is a plane. Surface numbers (12) and (13) are the entrance and exit surfaces of both aspherical lenses, and have negative refractive power in the sub-scanning direction. The surface number (14) is the photoreceptor 10.

As the glass materials for the double-sided spherical lens A, the double-sided spherical lens B, the toric lens, and the cylinder lens, the aspherical lenses of both sides such as S-PHM52, S-TIH6, S-BSM18, and S-BSL7 manufactured by OHARA INC. Examples of the resin material include ZEONEX E48R.
The entrance / exit surfaces (surface numbers (12) and (13)) of both aspherical lenses made of resin are shown in FIG. 11 where x is the main scanning direction, y is the sub-scanning direction, and z is the optical axis direction. It is an aspherical surface expressed by Equation 1 and Equation 2 in FIG. Here, r _x and r _y are the radii of curvature of the bus (main scanning direction) and the child line (sub scanning direction), respectively, and k _y is the conic constant in the sub scanning direction (where k _y = 0). The first term on the right side of Equation 1 represents a basic toric shape, and the second term on the right side represents an additional function for adding an optical axis asymmetric component to the basic shape. P _{mn in} Equation 1 is a constant given in the table of FIG. 13. From this, the generating lines of the entrance and exit surfaces (surface numbers (12) and (13)) of the aspherical lenses on both sides are non-circular arcs symmetric to the optical axis. A curve and a child line in an arbitrary yz section are non-circular curves having an asymmetrical optical axis.

  In the specific example of the second lens system described above, only one resin-side aspherical lens made of resin is rotated about the optical axis to adjust the scanning line inclination, and the entire second lens system is adjusted to the optical axis. The result of comparison with the case of adjusting the scanning line inclination by turning to the center is shown below. In both cases, the scanning line inclination is corrected to be equivalent to ± 0.25 mm, and in this state, the cylindrical lens 23 is rotationally adjusted around the optical axis so that the RMS spot diameter is minimized.

  FIG. 14 is a diagram showing the relationship between the RMS spot diameter and the image height when the scanning line inclination is not adjusted. FIG. 15 is a diagram showing the relationship between the RMS spot diameter and the image height when only one resin-made aspheric lens on both sides is rotated about the optical axis and the scanning line is tilted. FIG. 16 is a diagram showing the relationship between the RMS spot diameter and the image height when the entire second lens system is rotated about the optical axis and the scanning line inclination is adjusted. From these results, it can be seen that the amount of increase in spot diameter is smaller when the entire second lens system is rotated about the optical axis to adjust the scan line inclination.

  FIG. 17 is a diagram showing the bending of the scanning line when only one resin-made aspherical lens on both sides is rotated about the optical axis to adjust the scanning line inclination. FIG. 18 is a diagram showing the curve of the scanning line when the entire second lens system is rotated about the optical axis to adjust the scanning line inclination. From these results, it can be seen that the scanning line bending is less when the entire second lens system is rotated about the optical axis as in the present embodiment to adjust the scanning line inclination. Therefore, the scanning line inclination adjusting mechanism of this embodiment also has a function of adjusting the scanning line bending.

  On the other hand, a bow, which is an overall curve of the scanning line, is generated by warping of the folding mirror 28 or the like. In this embodiment, the flatness of the folding mirror 28 is set to a predetermined value or less, so that the bow is suppressed to such an extent that the printing quality is not affected. Therefore, no adjustment for bow is necessary. In addition, since the present embodiment assumes a monochrome machine and does not perform color superposition, even if the entire scanning line of one optical scanning device is bent, the influence on the print quality is small.

[Second embodiment]
FIG. 6 shows a scanning line tilt adjusting mechanism of the optical scanning device 11 according to the second embodiment of the present invention as viewed from the folding mirror 28 side. The basic configuration of the optical scanning device 11 is the same as that shown in FIGS.
This embodiment is characterized in that the lower center portion of the lens base 1 has a convex cylindrical shape 7, and the center of the cylindrical shape 7 is near the optical axis of the lenses 25a, 25b, 25c of the second lens system. The structure is as follows. Further, since the cylindrical receiving portion 8 is also a concave shape having the same radius of curvature as the cylindrical shape 7, the center of rotation of the lens base 1 is approximately the optical axis of the lenses 25a, 25b, 25c. Other configurations are the same as those of the first embodiment. In this configuration, since the displacement in the scanning direction of the lens with respect to the light beam is small, the amount of increase in the spot diameter is small, and the scanning line inclination adjusting mechanism is smaller in the occurrence of displacement in the sub-scanning direction magnification ratio.

[Third embodiment]
FIG. 7 shows a perspective view of an optical scanning device 11 provided with a scanning line inclination adjusting unit (scanning line inclination adjusting mechanism) according to a third embodiment of the present invention. In the embodiment shown in FIG. 7, the scanning line inclination adjusting mechanism is means for rotating and fixing the lenses 25b and 25c except the spherical lens 25a constituting the second lens system about the optical axis. That is, in this scanning line inclination adjusting mechanism, the lenses 25b and 25c of the second lens system (Fθ lens system) are fixed to the lens base 1, and the spherical lens 25a included in the second lens system (Fθ lens system) is used as the lens. It is characterized by being mounted on the optical base 6 without being mounted on the base 1. Since the spherical lens 25a is the same even if it is rotated about the optical axis, it does not have to be placed on the lens base 1 with the scanning line bending adjustment mechanism. Therefore, as shown in FIG. 7, by fixing the spherical lens 25a on the optical base 6, the size of the lens base 1 can be reduced, and the spherical surface when the rotation angle is increased during the rotation adjustment. It is possible to prevent the deflected light beam from coming off the lens 25a. The configuration and operation of the scanning line tilt adjustment mechanism are the same as those in FIG. 4 or FIG.

[Fourth embodiment]
In each of the above embodiments, a large number of light sources have been considered as a one-row array (one-dimensional array), but the same applies to a case where a large number of light sources are arranged in a two-dimensional array. FIG. 8 is a diagram showing a spot arrangement on the photoconductor 18 when nine light source elements are arranged in a 3 × 3 two-dimensional arrangement. When the light source unit in which nine light source elements are arranged in a 3 × 3 two-dimensional array is rotated about the optical axis, the array angle θ of the light spot 50 on the photosensitive member 18 changes. Accordingly, the scanning interval d1, d2 also changes. d1 decreases as θ increases, and d2 increases. Therefore, it is only possible to adjust the scanning intervals d1 and d2 equally by changing the array angle θ.

Therefore, in this embodiment, in order to adjust the scanning interval when the light sources are two-dimensionally arranged, an optical element for changing the magnification such as a zoom lens is provided in the first lens system (not shown).
That is, when the light source array is a two-dimensional array, the fixed position of the second lens system is set to a position where the scan line tilt is substantially 0 by the scan line tilt adjusting mechanism described in the first to third embodiments. After that, the magnification of the first lens system is changed by an optical element that changes the magnification, such as a zoom lens, and the scanning interval is fixed at a predetermined interval. By doing so, it is possible to adjust to an appropriate value even when the scanning interval changes after adjusting the scanning line inclination.

1: Lens base 2: Bearing 3: Adjustment screw 5: Shaft 4: Spring 6: Optical base 7: Cylindrical shape 8: Cylindrical receiving portion 10: Charging device 11: Optical scanning device 12: Developing device 13: Printing paper (recorded) Medium)
14: Conveying device 15: Transfer device 16: Cleaning device 17: Fixing device 17a: Heat roller 17b: Pressure roller 18: Photoconductor (image carrier (scanned medium))
20: Light source device 21: Light beam 23: Cylindrical lens 24: Rotating polygon mirror (light deflection device)
25a: Spherical lens 25b, 25c: Lens 26: Mirror 27: Optical sensor 28: Folding mirror 40: Horizontal line printing 50: Light spot

JP-A-10-133130 JP 2008-256862 A JP 2005-189791 A JP-A-11-268336 Japanese Patent Laid-Open No. 7-120692

Claims (8)

A plurality of light sources, a first lens system that guides light from the light sources, a light deflector that deflects and scans light from the first lens system, and light that is deflected and scanned by the light deflector In an optical scanning device having a second lens system that forms an image on a medium,
An optical scanning device comprising means for rotating and fixing a lens except the spherical lens constituting the second lens system about an optical axis. The optical scanning device according to claim 1 ,
Position where the array of the light sources is in a row and the fixed position of the second lens system is a position where the scan line inclination is substantially 0, and then the array angle of the light sources is changed so that the scanning interval becomes a predetermined interval An optical scanning device characterized by being fixed by The optical scanning apparatus according to claim 1 Symbol placement,
After the light source array is two-dimensional and the fixed position of the second lens system is set to a position where the scan line inclination is substantially 0, the magnification of the first optical system is changed, and the scanning interval is a predetermined interval. An optical scanning device characterized by being fixed at a position. A plurality of light sources, a first lens system that guides light from the light sources, a light deflector that deflects and scans light from the first lens system, and light that is deflected and scanned by the light deflector In an optical scanning device having a second lens system that forms an image on a medium ,
An optical scanning device comprising means for rotating and fixing the second lens system about the center of the optical axis, wherein the center of rotation of the second lens system is the scanning center and the lower part of the lens . A plurality of light sources, a first lens system that guides light from the light sources, a light deflector that deflects and scans light from the first lens system, and light that is deflected and scanned by the light deflector In an optical scanning device having a second lens system that forms an image on a medium ,
Means for rotating and fixing the lens except the spherical lens constituting the second lens system about the optical axis, and the center of rotation of the second lens system is at the scanning center and at the lower part of the lens; An optical scanning device characterized by the above. In the optical scanning device according to any one of claims 1 to 3 ,
An optical scanning device characterized in that the center of rotation of the second lens system is the lens center.   An image forming apparatus comprising the optical scanning device according to claim 1 as means for forming an electrostatic latent image on an image carrier that is a scanned medium. An image carrier that is a scanned medium, a charging device that charges the image carrier, and an electrostatic latent image corresponding to image information to be recorded by scanning the light from the light source on the image carrier. An optical scanning device for forming, a developing device for forming a toner image by attaching toner to the electrostatic latent image, a transfer device for transferring the toner image onto a recording medium directly or via an intermediate transfer medium, An image forming apparatus including a fixing device that fixes a transferred toner image on a recording medium.
An image forming apparatus comprising the optical scanning device according to claim 1 as the optical scanning device.

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