JP2006053304A - Optical scanning device and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical scanning device for preventing curvature of a scanning line while suppressing vibration of a mirror, and also to provide an image forming apparatus. <P>SOLUTION: The optional scanning device suppresses the vibration of the mirror 50 by pushing a substantially center part of the mirror 50. But, since the mirror is deflected and a beam of the center part as shown in Figure 2-A is moved like a dotted line, the scanning line of a recording medium 95 as shown in Figure 2-C is recess-curved to an ideal line. The optical scanning device suppresses the vibration of the mirror 52 by pulling the substantially center part of a lengthwise direction of the mirror 52 as shown in Figure 2-B. The influence to the scanning line due to deflection of the mirror 52 can be projection-curved to the ideal line as shown in Figure 2-D. The optical scanning device combining the above two cancels curvature of the scanning line as shown in Figure 2-E, and obtains an ideal scanning line by simultaneously taking out effects of Figure 2-C and Figure 2-D. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical scanning device and an image forming apparatus.

  In recent years, there has been a demand for a high-resolution image forming apparatus, and it has become necessary to reduce the vibration of the reflecting mirror of the optical scanning apparatus, which causes a reduction in image quality. That is, the generation of banding due to the vibration of the reflecting mirror (Banding) is a problem, and a technique for suppressing the vibration by pressing the back surface of the mirror has been known. In this case, since the mirror bends when the mirror is pressed, as a means for solving the problem, there has been proposed a method of pressing the substantially central portion of the mirror at the back surface at two points and further pressing through rubber (for example, Patent Document 1). reference).

  However, it is possible to prevent the vibration of the mirror by pushing the back surface of the mirror, but this is insufficient to satisfy the recent demand for high image quality (scanning line linearity).

That is, as shown in FIG. 15, it is possible to suppress vibrations by pushing the back surface of the mirror 102, but this makes it possible to form an ideal scan line shape drawn on the photosensitive member 104 → paper P (shown by a solid line in the figure). ), The so-called BOW (shown by a broken line in the figure) is generated.
JP-A-10-136169 (FIG. 3, pages 2 to 3)

  In consideration of the above-described facts, an object of the present invention is to provide an optical scanning device and an image forming apparatus that prevent the scanning line from being curved while suppressing the vibration of the mirror.

  The optical scanning device according to claim 1, a light source that emits a light beam, a deflecting device that deflects the emitted light beam in a main scanning direction, and an optical that forms an image of the deflected light beam on a surface to be scanned. An optical scanning device comprising at least two reflecting mirrors provided between a deflecting device and a surface to be scanned, the reflecting mirror being curved by a correcting means for pressing or pulling the reflecting mirror, and scanning It is characterized in that the curve of the line is canceled and corrected.

  In the invention with the above configuration, at least two reflecting mirrors are provided between the deflecting device and the surface to be scanned, and vibration of the reflecting mirror is prevented by pressing or pulling one reflecting mirror, whereby the reflecting mirror is curved. By pressing or pulling the other reflecting mirror so as to cancel the bending of the scanning line generated in step 1, the entire bending of the scanning line of the optical scanning device can be made as small as possible while preventing vibration of the other reflecting mirror. .

  The optical scanning device according to claim 2, a light source that emits a light beam, a deflection device that deflects the emitted light beam in a main scanning direction, and an optical that forms an image of the deflected light beam on a surface to be scanned. An optical scanning device including at least two reflecting mirrors provided between the deflecting device and the surface to be scanned, a support means for supporting the reflecting surface side of the reflecting mirror, and a back surface of the reflecting mirror. Pressing means for pressing, and the reflecting means is bent by the support means and the pressing means to correct the curvature of the scanning line.

  In the invention of the above configuration, by supporting the reflecting surface of the reflecting mirror and pressing the back of the reflecting surface, the reflecting mirror and the pressing member can be made into a support structure with a compact and simple configuration, which is excellent in economic efficiency and maintainability. The curvature of the scanning line of the optical scanning device can be minimized as much as possible while preventing the reflection mirror from vibrating while using a compact optical scanning device.

  The optical scanning device according to claim 3 is a light source that emits a light beam, a deflecting device that deflects the emitted light beam in the main scanning direction, and an optical that forms an image of the deflected light beam on a surface to be scanned. And at least two reflecting mirrors provided between the deflecting device and the surface to be scanned, one of the reflecting mirrors supporting the reflecting surface side and the first supporting means. The first reflecting means for pressing between the supporting means from the back surface is provided, and the other reflecting mirror includes the second supporting means for supporting the reflecting surface side and the second pressing means for pressing the outside of the second supporting means from the back surface. The reflecting mirror is bent by the first and second pressing means to cancel and correct the curve of the scanning line.

  In the invention having the above configuration, vibration is prevented by pressing the back of the reflecting surface, and while the pressing member is made compact and simple, one reflecting mirror is pressed between the supports to form a concave curve, and the other reflecting mirror is supported. The curve of the scanning line can be made as small as possible by causing the convex curve by pressing the outside and canceling the curvature of the scanning line of the optical scanning device.

  According to a fourth aspect of the present invention, at least one of the reflecting mirrors is a cylindrical mirror.

  In the invention with the above configuration, the cylindrical mirror is pressed against the reflecting surface by pressing and bending the tangential direction, and the same effect as that obtained by bending in the normal direction can be obtained by pressing the side and back surfaces of the cylindrical mirror. By doing so, it is possible to minimize the curvature of the scanning line of the optical scanning device while preventing vibration.

  According to a fifth aspect of the present invention, there is provided an optical scanning device including a pressing member that presses a side surface of the cylindrical mirror.

  In the invention of the above configuration, the cylindrical mirror is pressed against the reflecting surface by pressing the side surface of the cylindrical mirror by utilizing the same effect as the bending in the tangential direction with respect to the reflecting surface. Thus, it is possible to minimize the curvature of the scanning line of the optical scanning device while preventing vibration.

  The optical scanning device according to claim 6 is a light source that emits a light beam, a deflection device that deflects the emitted light beam in a main scanning direction, and an optical that forms an image of the deflected light beam on a surface to be scanned. And at least three reflecting mirrors are provided between the deflecting device and the surface to be scanned, and two reflecting mirrors closer to the surface to be scanned are pressed among the reflecting mirrors. Alternatively, the two reflecting mirrors close to the surface to be scanned are curved by correction means for pulling, and the curvature of the scanning line is canceled and corrected.

  In the invention of the above configuration, the reflecting mirror close to the surface to be scanned is longer and more likely to vibrate, so the two reflecting mirrors close to the surface to be scanned that are likely to vibrate for a long time are suppressed by pressing or pulling means, Further, by canceling the curvature of the scanning lines, an optical scanning device with a simple configuration and high image quality can be achieved efficiently.

  The optical scanning device according to claim 7 is characterized in that at least one of the support means and the pressing means can adjust a pressing force or a traction force.

  In the invention with the above configuration, the bending of the reflecting mirror can be adjusted so that the bending of the scanning line is eliminated by making it possible to adjust the pressing force or the traction force of at least one reflecting mirror.

  9. The optical scanning device according to claim 8, wherein a plurality of light sources for emitting a light beam, a rotary polygon mirror and a deflecting device for deflecting the emitted light beam in a main scanning direction, and a surface to be scanned with the deflected light beam. And an optical system that forms an image on top, wherein at least two reflecting mirrors are provided between the deflecting device and the surface to be scanned for each of the light beams.

  In the invention of the above configuration, the amount of curvature is adjusted for each color scanning line so that the color misregistration caused in the color image forming apparatus due to the difference in the amount of curvature of the scanning line between the colors is reduced. It can be an optical scanning device.

  An image forming apparatus according to a ninth aspect uses the optical scanning device according to any one of the first to seventh aspects.

  In the invention having the above-described configuration, a high-quality image forming apparatus can be obtained by using an optical scanning device in which at least two reflecting mirrors are arranged so as to cancel each other and cancel out the curvature of the scanning lines.

  Since the present invention is configured as described above, an optical scanning apparatus and an image forming apparatus that can prevent the scanning line from being curved while suppressing the vibration of the mirror can be obtained.

FIG. 1 shows an optical scanning device according to a first embodiment of the present invention.
[First embodiment]
An image forming apparatus according to a first embodiment of the present invention and an optical scanning device applied thereto will be described. First, the optical scanning device will be described, and further, the structure of the holding unit, which is a main part of the present invention, will be described.

  FIG. 1 shows an optical scanning device according to this embodiment. The optical scanning device will be described below. The light beam emitted from the laser light source 1 passes through the collimator lens 2, the slit 3, and the cylindrical lens 4 and is deflected by the rotating polygon mirror 36. As shown in FIG. 7, the beam L deflected by the reflecting surface of the rotary polygon mirror 36 is scanned in the main scanning direction so as to scan the photosensitive member at a constant speed by the two Fθ lenses 38. Further, the beam L that has passed through the Fθ lens 38 is folded back by the mirrors 50 and 52 to form an image on the photosensitive member 24.

  Next, the principle that can suppress the vibration of the mirror and reduce the curvature of the scanning line will be described.

  As described above, the vibration of the mirror 50 can be suppressed by pushing the substantially central portion of the mirror 50. However, since the mirror is bent and the central beam is moved as shown by a dotted line as shown in FIG. 2-A, the scanning line of the recording medium 95 is concavely curved with respect to the ideal line as shown in FIG. 2-C. End up.

On the other hand, as shown in FIG. 2-B, the vibration of the mirror 52 can be suppressed by pulling the substantially central portion in the length direction of the mirror 52. The influence of the deflection of the mirror 52 on the scanning line is shown in FIG. Thus, it can be a convex curve with respect to the ideal line. In the scanning device combining the above two, by simultaneously producing the effects of FIGS. 2-C and 2-D, it is possible to cancel the curvature of the scanning line as shown in FIG. You can get a line.
(Description of holding structure)
8 to 10 show a mirror holding structure according to this embodiment.

  Parts not related to holding of the mirrors 50 and 52 are not shown. Both end portions of the mirror 50 are supported on the reflecting surface side by support portions 70 and 72 constituted by a part of the casing, and the pressing holding portion 81 is an elastic member and is fastened to a part of the casing with screws. The vibration of the mirror 50 is suppressed by pressing the substantially central portion and both ends of the mirror 50 in the length direction.

  Since the mirror 50 is bent by this pressing, the scanning line is curved as shown in FIG. On the other hand, both end portions of the mirror 52 are supported on the reflecting surface by a support portion constituted by a part of the casing, and the holding portion 82 pulls the substantially central portion in the length direction of the mirror 52 to suppress the vibration of the mirror 52. Since the pulling pressure causes the mirror 52 to bend, the scanning line can be curved in the direction opposite to that shown in FIG.

The pressing members 84 and 85 press both end portions of the mirror 52 against the support portions 73 and 75. On the other hand, a nut 92 is embedded in the bracket 74. When the screw 90 is turned, the ring 91 moves to the bracket 74 side, and the holding portion 82 is pulled toward the bracket side following that, so that the mirror 52 is bent. The pressing force of the pressing members 84 and 85 presses the support members 73 and 75 and the mirror 52 so as not to be separated even when the mirror 52 is pulled by the holding portion 82.
The scanning lines due to the curvature of the mirror 50 and the mirror 52 are curved in directions that cancel each other, and as a result, the curvature is as small as possible as shown in FIG. In the above description, the operation has been described by applying the pushing / pulling pressure to the substantially central part of the mirrors 52 and 75. However, it goes without saying that the same effect can be obtained even if the pushing / pulling pressure is applied near the support side.
Another embodiment of the holding structure will be described. Although the mirror 52 is pulled by the holding portion 62 in the substantially central portion in the length direction to suppress the vibration of the mirror 52, a portion for chucking the mirror is necessary to pull the pressure, resulting in a wider width of the mirror. . Moreover, the attraction | suction structure has the subject which becomes complicated compared with a press structure. In order to solve this problem, as shown in FIG. 11-A, the reflecting surfaces at both ends of the mirror 52 are supported by the supporting members 76 and 77, and the outside of the supporting position is pressed by the elastic members 86 and 87. Thus, the same effect can be obtained with a simple configuration.

[Second Embodiment]
An optical scanning device according to a second embodiment of the present invention will be described.

  FIG. 3 shows an optical member and an optical system according to this embodiment. The optical scanning device will be described below.

  Since the configuration from the laser light source to the deflector is the same as that of the first embodiment, a description thereof will be omitted. As shown in FIG. 3A, the beam L deflected by the reflecting surface of the rotary polygon mirror 36 is scanned in the main scanning direction so as to scan the photosensitive member 24 at a constant speed by the two-sheet Fθ lens 38. The Further, the beam L that has passed through the Fθ lens 38 is folded back by mirrors 51 and 53 to form an image on the photosensitive member 24. The mirrors 51 and 53 are pressed substantially at the center.

  As shown in FIG. 3A, the vibration of the mirror 53 can be suppressed by pushing the substantially central portion in the length direction of the mirror 53. However, the mirror is deflected, and the central beam shifts as shown by a dotted line, and the scanning line of the recording medium 95 is convexly curved with respect to the ideal line as shown in FIG. On the other hand, the vibration of the mirror 51 can be suppressed by pushing the substantially central portion in the length direction of the mirror 51 as shown in FIG. The influence of the scanning line due to the deflection of the mirror 51 can be a concave curve with respect to the ideal line as shown in FIG.

  In the optical scanning device combining the above two, by simultaneously producing the effects shown in FIGS. 3-C and 3-D, it is possible to cancel the curvature of the scanning line as shown in FIG. 3-E. The structure for pushing the substantially central part of the mirrors 51 and 53 is the same as that shown in FIG.

[Third embodiment]
An optical scanning device according to a third embodiment of the present invention will be described.

  FIG. 4 shows an optical member and an optical system according to this embodiment.

  The optical scanning device will be described below. Since the configuration from the laser light source to the deflector is the same as that of the first embodiment, a description thereof will be omitted. As shown in FIG. 4A, the beam L deflected by the reflecting surface of the rotary polygon mirror 36 is scanned in the main scanning direction so as to scan the photosensitive member 24 at a constant speed by the two-sheet Fθ lens 38. The Further, the beam L that has passed through the Fθ lens 38 is folded back by the cylindrical mirror 54 and the mirror 55 and is imaged on the photosensitive member 24. Along the cylindrical mirror 54 and the mirror 55, the substantially central portion in the length direction is pressed.

  As shown in FIG. 4A, the vibration of the mirror 55 can be suppressed by pushing the substantially central portion in the length direction of the mirror 55. However, this causes the mirror 55 to bend, and the central beam shifts as shown by a dotted line, so that the scanning line of the recording medium 95 is convexly curved with respect to the ideal line as shown in FIG.

  On the other hand, as shown in FIG. 4-B, the vibration of the cylindrical mirror 54 can be suppressed by pushing the substantially central portion on the side surface side of the cylindrical mirror 54. The influence of the scanning line due to the bending of the cylindrical mirror 54 can be a concave curve with respect to the ideal line as shown in FIG.

  In the optical scanning device combining the above two, by simultaneously producing the effects shown in FIGS. 4-C and 4-D, it is possible to cancel the curvature of the scanning line as shown in FIG. 4-E.

  The pressing structure of the cylindrical mirror 54 is shown in FIG. The back surfaces of both ends of the cylindrical mirror 54 can be pressed against the support members 76 and 77 by the pressing members 86 and 87, and the vibration of the cylindrical mirror 54 can be suppressed by the pressing member 83 on the substantially central side surface of the cylindrical mirror 54. The structure for pushing the substantially central portion of the mirror 55 is the same as that shown in FIG.

[Fourth embodiment]
An image forming apparatus according to a fourth embodiment of the present invention and an optical scanning device applied thereto will be described.

  FIG. 13 shows an image forming apparatus according to this embodiment.

  As shown in FIG. 13, the image forming apparatus 90 includes electrophotographic units 12Y, 12C, 2M, and 4D that form toner images of four colors Y (yellow), M (magenta), C (cyan), and K (black). 12K, transfer devices 20Y, 14C, 14M, and 14K, which will be described later, each toner image is accumulated, and a transfer device 20 that transfers the color toner image to the paper supplied from the tray 18, and a color toner image transferred onto the paper The image forming apparatus is basically composed of a fixing device 22 that melts and fixes the image, and the process creates an image in one cycle. An optical scanning device 28CK and an optical scanning device 28YM are provided. Data is transferred as a digital signal from an image control unit (not shown) to a laser light source (not shown), and a light beam emitted from the laser light source is converted into a collimator lens and a cylindrical lens group. Then, the light beam deflected by the optical deflector is reflected or passed through the optical member, and irradiates the photosensitive members 24Y and 24M charged by the charging devices 26Y and 26M, respectively. The exposed photoreceptors 24Y, 24M, 24C, and 24K are developed by the developing devices 30Y, 30M, 30C, and 30K, and Y, M, C, and K color images are transferred to the intermediate transfer belt 16 and transferred by the transfer device 20. It is transferred to the paper P and melted and fixed by the fixing device 22.

  The diameter of the K (black) photoreceptor 24K is set larger than the diameter of the photoreceptors 24Y to 24C, and only the K photoreceptor 24K deteriorates early in the morning due to the output of a monochrome image that is used more frequently than the color image. To prevent it from happening.

  The optical scanning device 28 will be described along the optical path of the YC beam L (YC) with reference to FIG. Note that description of the configuration until the beam LY irradiated from a light source (LD) (not shown) is incident on the rotary polygon mirror will be omitted.

  The beam L (YC) deflected by the reflecting surface of the rotary polygon mirror 36 is scanned in the main scanning direction so as to scan on the photosensitive member at a constant speed by the two Fθ lenses 38. Further, the beam L (YC) that has passed through the Fθ lens 38 is folded back by the cylindrical mirror 187, the reflection mirror 142, and the cylindrical mirror 184, passes through the dust-proof glass, and then forms an image on the photoreceptor 24YC. Usually, the mirror closer to the photoconductor 24 has a longer length, and as a result, tends to vibrate. Therefore, a pressing member is provided at a substantially central portion of the downstream mirror in the length direction on the optical path. That is, the substantially central side surface portion of the cylindrical mirror 184 is pressed to suppress vibration, and the configuration thereof is the same as the configuration shown in FIG.

  In a color image forming apparatus having a plurality of photoconductors as in this embodiment, the scanning line curve of the optical scanning device causes a positional shift for each color image, that is, a color shift, which causes deterioration in image quality. It is necessary to minimize the scanning line curvature. The holding structure of the mirror 142 for that purpose is shown in FIG. Both ends of the mirror 142 are the same as the structure described in the first embodiment.

  FIG. 14 shows the details of the pressing holding portion at the substantially central portion in the length direction of the mirror 142. The holding member 76 is a part of the housing or a member fastened to the housing. The holding member 76 is threaded and a screw 92 having a round tip is incorporated. It is possible to adjust the bending amount of the mirror by adjusting the pushing amount of the screw 92.

  Next, a description will be given along the optical path of the MK beam L (MK). As shown in FIG. 6, the beam L (MK) deflected by the rotating polygonal mirror 36 is reflected by the cylindrical mirror 186, the reflection mirror 148, the cylindrical mirror 185, and the reflection mirror 152 through the Fθ lens 38, and becomes dust-proof glass. After passing, the structure reaches the photosensitive member 24MK. The cylindrical mirror 185 is pressed substantially at the center side surface, and the configuration thereof is the same as the configuration shown in FIG. The reflection mirror 152 is pressed substantially at the center. The configuration is the same as the holding configuration of the mirror 142.

  There are two types of optical systems, L (YC) and L (MK). The difference is that the L (MK) beam has a reflection mirror 152 disposed after the cylindrical mirror 185, and the L (YC) beam Is a configuration in which a cylindrical mirror 184 is arranged as a final optical component. The difference between M and K is that the position of the mirror 152 is different. The cylindrical mirrors 184 and 185 have a function of correcting surface tilt of the rotary polygon mirror and scanning deviation in the sub-scanning direction.

1 is a perspective view showing an optical scanning device according to a first embodiment of the present invention. It is a front view of the optical scanning device concerning the 1st form of the present invention. It is a front view of the optical scanning device concerning the 2nd form of the present invention. It is a front view of the optical scanning device concerning the 3rd form of the present invention. It is a perspective view which shows the mirror holding mechanism of the optical scanner which concerns on this invention. It is a front view which shows the optical scanning device of this invention. It is a front view which shows the optical scanning device which concerns on the 1st form of this invention. It is a perspective view which shows the mirror holding mechanism of the optical scanner which concerns on this invention. It is a perspective view which shows the mirror holding mechanism of the optical scanner which concerns on this invention. It is sectional drawing which shows the mirror holding mechanism of the optical scanning device concerning this invention. It is a perspective view which shows the mirror holding mechanism of the optical scanner which concerns on this invention. It is a perspective view which shows the mirror holding mechanism of the optical scanner which concerns on this invention. 1 is a front view of an image forming apparatus according to the present invention. It is sectional drawing which shows the mirror holding mechanism of the optical scanning device which concerns on this invention. It is a front view of the conventional optical scanning device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 12 Electrophotographic unit 14 Transfer device 16 Intermediate transfer belt 18 Tray 20 Transfer device 22 Fixing device 24 Photoconductor 26 Charger 28 Optical scanning device 30 Developing device 34 Housing 36 Rotating polygon mirror 38 Fθ lens 40 Reflective mirror 50 Reflective mirror 70 Support member 79 Support member 80 Press member 80 Press member 90 Image forming apparatus

Claims (9)

A light source that emits a light beam;
A deflecting device for deflecting the emitted light beam in the main scanning direction;
An optical system for imaging the deflected light beam on the surface to be scanned;
An optical scanning device comprising:
Providing at least two reflecting mirrors between the deflecting device and the surface to be scanned;
An optical scanning device characterized in that the reflecting mirror is bent by a correction means for pressing or pulling the reflecting mirror to cancel and correct the curve of the scanning line. A light source that emits a light beam;
A deflecting device for deflecting the emitted light beam in the main scanning direction;
An optical system for imaging the deflected light beam on the surface to be scanned;
An optical scanning device comprising:
Providing at least two reflecting mirrors between the deflecting device and the surface to be scanned;
A supporting means for supporting the reflecting surface side of the reflecting mirror, and a pressing means for pressing the back surface of the reflecting mirror,
An optical scanning apparatus characterized in that the reflecting mirror is curved by the support means and the pressing means to cancel and correct the curvature of the scanning line. A light source that emits a light beam;
A deflecting device for deflecting the emitted light beam in the main scanning direction;
An optical system for imaging the deflected light beam on the surface to be scanned;
An optical scanning device comprising:
Providing at least two reflecting mirrors between the deflecting device and the surface to be scanned;
One of the reflecting mirrors includes first pressing means for pressing between the first supporting means and the first supporting means for supporting the reflecting surface side from the back surface,
The other reflecting mirror includes second supporting means for supporting the reflecting surface side and second pressing means for pressing the outside of the second supporting means from the back surface,
An optical scanning device characterized in that the reflecting mirror is curved by the first and second pressing means to cancel and correct the curvature of the scanning line. 4. The optical scanning device according to claim 1, wherein at least one of the reflecting mirrors is a cylindrical mirror. The optical scanning device according to claim 4, further comprising a pressing member that presses a side surface of the cylindrical mirror. A light source that emits a light beam;
A deflecting device for deflecting the emitted light beam in the main scanning direction;
An optical system for imaging the deflected light beam on the surface to be scanned;
An optical scanning device comprising:
Providing at least three reflecting mirrors between the deflecting device and the surface to be scanned;
The two reflecting mirrors close to the scanned surface are curved by correction means that presses or pulls the two reflecting mirrors close to the scanned surface among the reflecting mirrors, and the curvature of the scanning line is canceled and corrected. An optical scanning device. The optical scanning device according to claim 1, wherein at least one of the support unit and the pressing unit is capable of adjusting a pressing force or a traction force. A plurality of light sources emitting a light beam;
A rotating polygon mirror and a deflecting device for deflecting the emitted light beam in the main scanning direction;
An optical system for imaging the deflected light beam on the surface to be scanned;
An optical scanning device comprising:
7. The optical scanning device according to claim 1, wherein at least two reflecting mirrors are provided between the deflecting device and the surface to be scanned for each light beam. An image forming apparatus using the optical scanning device according to claim 1.

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