JPH09288245A - Optical scanner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical scanner capable of surely adjusting the attitude of a cylindrical lens so that the face top of the lens may be parallel to a main scanning surface. SOLUTION: In the scanner, the cylindrical lens 11 is held by a lens holder 12. The cylindrical lens 11 is supported by attitude adjustment screws 141 to 144 and springs 161 to 164 in the lens holder 12. And also, by adjusting each screwing amount of the screws 141 to 144, the cylindrical lens 11 is shifted on a surface which is orthogonal to the optical axis of the light emitted from a semiconductor laser, then, the cylindrical lens 11 is arranged so that the face top H of the lens 11 may be parallel to the main scanning surface.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a laser printer,
The present invention relates to an optical scanning device used in a copying machine or the like.
More specifically, the present invention relates to a mounting technology for a cylindrical lens used in such an optical scanning device.

[0002]

2. Description of the Related Art As an optical scanning device for forming an image of light emitted from a laser light source on a photosensitive drum of a laser printer or a copying machine using a deflector, as shown in FIG. On the optical path leading to the body drum 25,
A configuration in which a collimator lens 22, a cylindrical lens 11, a polygon mirror 23, and an fθ lens 24 are arranged is known. In the optical scanning device 20a configured in this way, after the light emitted from the semiconductor laser 21 is converted into parallel light by the collimator lens 22,
It is adapted to enter the cylindrical lens 11. The cylindrical lens 11 is a convex lens,
The anamorphic optical system is arranged so as to have no power in the main scanning direction A and have power only in the sub-scanning direction perpendicular to the main scanning direction. Therefore, the light emitted from the cylindrical lens 11 is reflected by the polygon mirror 23.
After being linearly imaged on each of the reflecting surfaces 231 of the above, it is reflected by the polygon mirror 23, is imaged on the photosensitive drum 25 (scanned surface) via the fθ lens 24, and in the direction indicated by the arrow A. To be scanned.

In such an optical scanning device 20a, when the reflecting surface 231 of the polygon mirror 23 is tilted due to a manufacturing error, a mounting error, a vibration during rotation, or the like, a laser beam is radiated on the photosensitive drum 25. A deviation in the sub-scanning direction occurs at the image forming position, and the pitch of the scanning lines becomes uneven. Since such a defect causes a reduction in printing quality in a laser printer or the like, the problem caused by the surface tilt of the reflecting surface 231 is reduced to that of the cylindrical lens 11 and the fθ lens 24 of the reflecting surface 231 of the polygon mirror 23. Reflection points in the sub-scanning direction and the photosensitive drum 25
It is solved by arranging so as to satisfy the conjugate relation with the upper photosensitive surface. Here, the cylindrical lens 11 must be arranged so that its top and the main scanning surface (the surface including the main scanning direction A and the optical axis of the light emitted from the semiconductor laser 21) are parallel to each other. Since an abnormality occurs in the upper spot shape, with respect to the cylindrical lens 11, the parallelism and verticality of the outer peripheral end faces are accurately obtained, and the outer peripheral end faces are aligned with the reference plane on the device side, so that the semiconductor laser The posture of the cylindrical lens 11 in the in-plane direction orthogonal to the optical axis of the laser light emitted from the lens 21 is adjusted.

[0004]

However, in the conventional structure in which the posture of the cylindrical lens 11 is determined with the outer peripheral end face of the cylindrical lens 11 as a reference, the parallelism and verticality of the outer peripheral end face of the cylindrical lens 11 are reduced. Since the end faces and the top of the cylindrical lens 11 are not always parallel or perpendicular to each other with high precision even if the degree of precision is increased, the top of the cylindrical lens 11 is made parallel to the main scanning surface. However, there is a problem in that it cannot be reliably arranged.

[0005] In view of the above problems, an object of the present invention is to provide:
An object of the present invention is to provide an optical scanning device capable of surely setting the posture of a cylindrical lens so that its top is parallel to the main scanning surface.

[0006]

In order to solve the above problems, according to the present invention, at least a laser light source, a deflector arranged on the optical axis of laser light emitted from the laser light source, and the deflector are provided. And a laser light source disposed between the laser light source and a cylindrical lens for linearly focusing the laser light emitted from the laser light source on the reflecting surface of the deflector, and the laser light reflected by the reflecting surface. In an optical scanning device configured to form an image on a surface to be scanned, for adjusting the attitude of the cylindrical lens in an in-plane direction orthogonal to the optical axis of the laser light emitted from the laser light source. It is characterized by having a lens attitude adjusting means.

In the present invention, since the lens attitude adjusting means for adjusting the attitude of the cylindrical lens in the in-plane direction orthogonal to the optical axis of the laser light emitted from the laser light source is provided, the cylindrical lens is used as the device. After mounting on top, the posture of the cylindrical lens can be adjusted so that the top of the surface and the main scanning surface (the surface including the main scanning direction and the optical axis of the light emitted from the laser light source) are parallel. Therefore, since an appropriate spot can be formed on the surface to be scanned such as the photosensitive drum, a high quality image or high quality printing can be performed in a laser printer or a copying machine. Moreover, unlike the case where the outer peripheral end surface of the cylindrical lens is accurately finished in advance and the attitude of the cylindrical lens is determined with the outer peripheral end surface as a reference, the attitude of the cylindrical lens is properly adjusted after mounting the cylindrical lens on the device. Because it will be corrected to the state,
It is not affected by the parallelism or verticality of the outer peripheral edge of the cylindrical lens. Therefore, the manufacturing cost of the cylindrical lens can be reduced because the finishing accuracy of the cylindrical lens is not required.

In the present invention, the lens attitude adjusting means determines the attitude of the cylindrical lens in an in-plane direction orthogonal to the optical axis of the laser light emitted from the laser light source, in the axial direction of the lens and the axial direction of the lens. It is preferable that it is configured so that it can be adjusted in each of the directions orthogonal to.

As such lens attitude adjusting means,
For example, a lens holder that holds the cylindrical lens via the outer peripheral end surface of the cylindrical lens can be used. In this case, with respect to the lens holder, a posture adjusting screw capable of adjusting a screwing amount in the axial direction of the cylindrical lens, a spring for pressing the cylindrical lens toward the posture adjusting screw, and a cylindrical lens A posture adjusting screw capable of adjusting the screwing amount in a direction orthogonal to the axial direction and a spring for pressing the cylindrical lens toward the posture adjusting screw are provided, and the cylindrical lens is fixed by these springs and the posture adjusting screw. Hold. Also, the lens holder
By adjusting the screwing amount of each of the posture adjusting screws, the posture of the cylindrical lens in the in-plane direction orthogonal to the optical axis of the laser light emitted from the laser light source can be adjusted to the axial direction of the lens and the axial direction of the lens. It can be adjusted from each of the directions orthogonal to each other.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

(Overall Configuration of Optical Scanning Device) FIG. 1 is a schematic configuration diagram of an optical scanning device (scanning optical system) to which the present invention is applied, and FIG. 2A is a diagram showing the light on the main scanning surface of this optical scanning device. 2B is an explanatory diagram schematically showing the state of light on the sub-scanning surface of the optical scanning device of the present example. Since the optical scanning device of this example has the same basic configuration as the conventional optical scanning device described with reference to FIG. 5, parts having common functions are designated by the same reference numerals. Detailed description is omitted.

In FIG. 1, the optical scanning device 20 of this example is
An optical scanning device used in a laser printer, a copier, or the like, and a collimator lens 22 and a convex cylindrical lens unit 10 are provided in an optical path from a semiconductor laser 21 which is a laser light source to a photosensitive drum 25 (scanned surface). , A polygon mirror 23 (deflector) that rotates around an axis 232, and an fθ lens 24 are arranged in this order.

In the optical scanning device 20, as shown in FIGS.
As also shown in FIG. 3, laser light (divergent light) directly modulated according to the recording information to be recorded on the printer or the like is emitted from the semiconductor laser 21, and this laser light is collimated by the collimator lens 22.
After being converted into parallel light by, the light enters the cylindrical lens 11. Here, the cylindrical lens 11
Has its convex surface 111 disposed on the side of the collimator lens 22, has no power in the main scanning direction A on the photoconductor drum 25 with respect to the light emitted from the collimator lens 22, and the main scanning is performed. An anamorphic optical system having power only in the sub-scanning direction orthogonal to the direction A is configured. For this reason, the cylindrical lens 11 is not shown in FIG.
As can be seen from (a), in the main scanning direction A on the photosensitive drum 25, the laser light is emitted toward the polygon mirror 23 with a diameter that is almost the same. Further, as can be seen from FIG. 2B, the cylindrical lens 11 emits laser light so as to converge on the reflection surface 231 of the polygon mirror 23 in the sub scanning direction. Therefore, the outgoing light incident on the reflection surface 231 of the polygon mirror 23 becomes a point image when viewed in the sub-scanning direction, and forms a linear image in the main scanning direction. Therefore, the light reflected by the reflecting surface 231 of the polygon mirror 23 forms an image on the photosensitive drum 25 via the fθ lens 24, which is a scanning lens, and is scanned in the direction of arrow A.

In the optical scanning device 20 configured as described above, the top of the cylindrical lens 11 is not parallel to the scanning surface (the surface including the main scanning direction A and the optical axis of the light emitted from the semiconductor laser 21). When a predetermined spot shape cannot be obtained on the photoconductor drum 25, the printing quality is degraded by a laser printer or the like.

(Lens posture adjusting means) Therefore, in the present invention, as described in detail below, the posture of the cylindrical lens 11 in the in-plane direction orthogonal to the optical axis of the laser light emitted from the laser light source is adjusted. The lens posture adjusting means for this is configured. The configuration of the lens attitude adjusting means will be described in detail below with reference to FIGS. 3 and 4.

FIG. 3 is an enlarged explanatory view showing the periphery of the cylindrical lens unit of the optical scanning device according to this embodiment, and FIG.
4A is a front view of a cylindrical lens unit used therein, and FIG. 4B is a cross-sectional view taken along the line CC ′ of FIG. 4A. In FIGS. 4A and 4B, among the three directions orthogonal to each other, the Z direction is the optical axis direction of the laser light emitted from the semiconductor laser 21, and the X direction is the axial direction of the cylindrical lens 11 (top surface). Direction / main scanning direction), and the Y direction is a sub-scanning direction orthogonal to the ZX plane (main scanning surface), and the XY plane is in a plane orthogonal to the optical axis of the laser light emitted from the laser light source. Corresponds to the direction.

As shown in FIG. 3, in this example, a lens holder 12 for holding the cylindrical lens unit 10 is used as the lens attitude adjusting means. The cylindrical lens unit 10 together with the lens holder 12 is used in the cylindrical lens unit 10. 10 is mounted on the frame 18 of the optical scanning device 20 or the like. In FIG. 3, the semiconductor laser 21 and the collimating lens 2 are shown.
2 and 2 are shown as a unit and the semiconductor laser collimating lens unit 26 is used.

The lens holder 12 used here has a rectangular main body frame 13, and the concave portion on one side thereof serves as a lens housing portion 131 for housing the cylindrical lens 11. That is, as shown in FIGS. 4A and 4B, in the lens holder 12, on the back surface side of the lens housing portion 131, the upper end side lens support portion 132 that projects right below from the upper frame portion of the main body frame 13, A lower end side lens support portion 133 is formed which projects right above from a lower frame portion of the main body frame 13,
The flat surface 112 of the cylindrical lens 11 is supported by the upper end side lens support portion 132 and the lower end side lens support portion 133. Therefore, the lens storage unit 131
In, the cylindrical lens 11 is arranged in the in-plane direction (in the XY plane) orthogonal to the optical axis of the laser light emitted from the semiconductor laser 21. In the body frame 13, an opening 134 is secured between the upper end side lens support portion 132 and the lower end side lens support portion 133, and this opening 134 serves as an optical path of the lens holder 12.

In the lens holder 12, two posture adjusting screws 141 and 142 are fixed to the upper frame portion of the main body frame 13 at positions separated by a predetermined distance so as to penetrate the upper frame portion from above. Here, the shaft end portions of the posture adjusting screws 141 and 142 abut on the upper end surface 113 of the cylindrical lens 11 via the spacer 151. On the other hand, in the lower frame portion of the main body frame 13, springs 161 and 162 for pressing the cylindrical lens 11 from the lower end surface 114 thereof toward the posture adjusting screws 141 and 142 are located at predetermined positions. It is fixed. Therefore, the cylindrical lens 11 is held by the lens holder 12 in a state of being sandwiched by the attitude adjusting screws 141 and 142 and the springs 161 and 162 in the Y direction. Therefore, for example, when the attitude adjusting screw 142 is tightened, the spring 162 contracts and the cylindrical lens 11 is drawn in a plane orthogonal to the optical axis of the laser light emitted from the semiconductor laser 21. The posture changes to the state of falling to the right. That is, in the cylindrical lens 11, the surface apex H ′ inclined when viewed from the main scanning surface (ZX plane) is the surface apex H.
Is corrected in a direction parallel to the main scanning plane (ZX plane). That is, the cylindrical lens 1
In a direction (Y) orthogonal to the axial direction of the lens.
Direction).

Further, in the lens holder 12, the main body frame 13
Two posture adjusting screws 143, 144 are fixed to the left frame portion at a position spaced apart by a predetermined distance so as to penetrate the left frame portion from the left side. Here, the posture adjusting screws 143, 144
The axial end portion of the is abutted against the left end surface 115 of the cylindrical lens 11 via a spacer 152. On the other hand, in the right frame portion of the main body frame 13, the cylindrical lens 11 is attached from the right end surface 116 to the posture adjusting screws 143, 14.
The springs 163 and 164, which are pressed toward the direction 4, are fixed at predetermined positions. Therefore, the cylindrical lens 11 has the posture adjusting screw 143,
It is held by the lens holder 12 while being sandwiched by 144 and the springs 163 and 164. Therefore, for example, when the attitude adjusting screw 143 is tightened, the spring 16
When 3 is contracted, the cylindrical lens 11 changes its posture to the right downward direction toward the drawing in the plane orthogonal to the optical axis of the laser light emitted from the semiconductor laser 21. That is, in the cylindrical lens 11, the surface apex H ′ that is inclined when viewed from the main scanning surface (ZX plane) is
The top of the surface H is corrected in a direction parallel to the main scanning surface (ZX plane) as shown by a dotted line. That is, the attitude of the cylindrical lens 1 can be adjusted from the axial direction (X direction) of the lens.

As described above, in the cylindrical lens unit 10 of this example, the attitude of the cylindrical lens 11 can be adjusted from the main scanning direction (X direction) and the sub scanning direction (Y direction).

(Method of Use and Effect) When the cylindrical lens 11 is mounted on the frame of the device through the lens holder 12 in the optical scanning device 20 having the above-described structure, the surface apex H of the cylindrical lens 11 and If the scanning surface (ZX surface) is not parallel, a predetermined spot shape cannot be obtained on the photosensitive drum 25, and the printing quality is degraded in a laser printer or the like. In such a case, the screwing amount is adjusted by tightening or loosening appropriate screws of the posture adjusting screws 141 to 144, and the top H of the cylindrical lens 11 is adjusted to the main scanning plane (ZX surface). Parallel to. As a result, an appropriate spot can be formed on the photosensitive drum 25, so that a high quality image or high quality printing can be performed in a laser printer or a copying machine. Moreover, unlike the conventional case where the outer peripheral end surface of the cylindrical lens 11 is accurately finished in advance and the posture of the cylindrical lens 11 is determined with the outer peripheral end surface as a reference, the cylindrical lens 11 is mounted on the device, Since the posture is corrected, the finish accuracy such as the parallelism and verticality of the outer peripheral end surface of the cylindrical lens 11 is not affected.
Therefore, the manufacturing cost of the cylindrical lens 11 can be reduced because the outer peripheral end surface of the cylindrical lens 11 is not required to have an excessive finishing precision. Further, even if the finished state of each cylindrical lens 11 is different, the posture can be adjusted to an optimum state for each individual cylindrical lens 11.

In the cylindrical lens unit 10 of the optical scanning device 20 of this example, after adjusting the inclination of the cylindrical lens 11, each posture adjusting screw 141 is adjusted.
~ 144 may be fixed with an adhesive to prevent loosening of the screws. Further, in this example, the lens holder 12 that is separate from the apparatus main body is used, but a part of the frame forming the optical scanning device 20 may be processed and used as the lens holder 12.

[0024]

As described above, in the optical scanning device according to the present invention, the lens attitude adjustment for adjusting the attitude of the cylindrical lens in the in-plane direction orthogonal to the optical axis of the laser light emitted from the laser light source. It is characterized by having means. Therefore, according to the present invention, after the cylindrical lens is mounted on the apparatus, the posture of the cylindrical lens can be adjusted so that the top of the cylindrical lens and the main scanning surface are parallel to each other. Therefore, since an appropriate spot can be formed on the surface to be scanned such as the photosensitive drum, a high quality image or high quality printing can be performed in a laser printer or a copying machine. In addition, since the attitude of the cylindrical lens is adjusted after it is mounted, it is not affected by the finishing accuracy such as the parallelism or verticality of the outer peripheral end surface of the cylindrical lens. Therefore, the manufacturing cost of the cylindrical lens can be reduced because the outer peripheral end surface of the cylindrical lens is not required to have an excessive finishing precision.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an optical scanning device according to an embodiment of the present invention.

2A is an explanatory view schematically showing the state of light in the main scanning direction of the optical scanning device shown in FIG. 1, and FIG. 2B is a schematic diagram showing the state of light in the sub-scanning direction. FIG.

FIG. 3 is an explanatory view showing, in an enlarged scale, the periphery of a cylindrical lens unit used in the optical scanning device shown in FIG.

4A is a front view showing the cylindrical lens unit shown in FIG. 3, and FIG. 4B is a sectional view taken along line CC ′ of FIG.

FIG. 5 is a schematic configuration diagram of a conventional optical scanning device.

[Explanation of symbols]

 10 Cylindrical lens unit 11 Cylindrical lens 12 Lens holder 141-144 Posture adjustment screw 161-164 Spring 20 Optical scanning device 21 Semiconductor laser (laser light source) 22 Collimator lens 23 Polygon mirror (deflector) 231 Reflection surface 24 fθ lens 25 Photoconductor Drum (scanned surface) A Main scanning direction H Cylindrical lens top

Claims (3)

[Claims] 1. A laser light source, a deflector arranged on the optical axis of laser light emitted from the laser light source, and a deflector arranged between the deflector and the laser light source. And a cylindrical lens that linearly images the emitted laser light on the reflecting surface of the deflector,
In an optical scanning device configured to form an image of the laser light reflected by the reflecting surface on a surface to be scanned, the optical scanning device in the in-plane direction orthogonal to the optical axis of the laser light emitted from the laser light source. An optical scanning device comprising a lens attitude adjusting means for adjusting the attitude of a cylindrical lens. 2. The lens attitude adjusting means according to claim 1, wherein the attitude of the cylindrical lens in the in-plane direction orthogonal to the optical axis of the laser light emitted from the laser light source is the axial direction of the lens. An optical scanning device, which is configured to be adjustable from respective directions orthogonal to the axial direction. 3. The lens attitude adjusting means according to claim 2, further comprising a lens holder that holds the cylindrical lens via an outer peripheral end surface of the cylindrical lens, the lens holder being screwed in an axial direction of the cylindrical lens. A posture adjusting screw that can adjust the amount, a spring that presses the cylindrical lens toward the posture adjusting screw, and a posture adjusting screw that can adjust the screwing amount in a direction orthogonal to the axial direction of the cylindrical lens,
While holding the cylindrical lens by a spring that presses the cylindrical lens toward the attitude adjusting screw, the laser light emitted from the laser light source is adjusted by adjusting the screwing amount of each of the attitude adjusting screws. It is characterized in that the posture of the cylindrical lens in an in-plane direction orthogonal to the axis can be adjusted from each of the axial direction of the lens and the direction orthogonal to the axial direction. Optical scanning device.