JPH11218706A - Scanning optical device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid the problem caused by the vibration of a foldover mirror and to improve the picture quality by making the shape of a foldover mirror cover section so that the vibration is reduced by varying the shape of the section based on the vibration mode using a simple structure. SOLUTION: The foldover mirror cover section, which covers a foldover mirror, is composed of a portion of the optical box that forms an opening section 9 to emit laser beams. A portion of an arm section 11b is separated with the width of 1 to 10 mm so that the section 11b becomes discontinuous in the longitudinal direction. Having the constitution described above, the vibration mode of the section 11b is varied by cutting the transfer path of the vibration and the vibration of the cover section is reduced. Thus, the trouble caused by the vibration of the mirror is avoided. There exists no limitation on the shape of the arm section separation provided that the discontinuity in the longitudinal direction is made within the width of 1 to 10 mm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanning optical device used for a laser beam printer, a laser facsimile, and the like.

[0002]

2. Description of the Related Art In a scanning optical apparatus used in a laser beam printer, a laser facsimile, or the like, a photosensitive member is scanned with a light beam deflected by a deflector to form an electrostatic latent image. The electrostatic latent image is visualized into a toner image by a developing device, the toner image is transferred to a recording sheet, and then the toner is heated and fixed on a recording sheet after the transfer of the toner image by a fixing device. Printing is performed.
FIG. 4 is a plan view for explaining the configuration of a conventional scanning optical device used in a laser beam printer to scan a photosensitive member with a light beam, and a deflecting surface (a light beam deflected by a deflecting / reflecting surface of a deflector). The ray bundle surface formed over time, X
FIG. 3 is a diagram for explaining a function in a (Y plane). FIG.
FIG. 6 is a diagram for explaining functions in a cross section including the optical axis of the θ lens and orthogonal to the deflection surface (Z-axis direction). The scanning optical device is housed in a scanner main body (optical box) 11, and FIG. 4 is a plan view showing the scanning optical device with its lid 11a removed.
The scanning optical device includes a semiconductor laser device 1, a collimator lens 2 that converts a light beam generated from the semiconductor laser device 1 into a parallel light beam, a cylindrical lens 3 that condenses the parallel light beam from the collimator lens 2 into a linear shape, and the cylindrical lens. 3, a rotating polygon mirror 4 having a deflecting / reflecting surface 4a in the vicinity of a line image of a light beam formed by the light source 3, a motor 5 for driving the rotating polygon mirror 4 to rotate, an Fθ lens 12; Folding mirror 8 for changing the optical box, and the optical box 11 provided so as to form an opening through which a light beam generated from the semiconductor laser device 1 is emitted.
And an arm portion 11b, which is a part thereof. The light beam deflected and reflected by the deflecting reflection surface 4a is F
After passing through the opening 9 of the optical box 11 through which the laser beam is emitted through the θ lens 12 and the folding mirror 8,
Is irradiated.

The Fθ lens 12 is designed so that the light beam reflected by the deflecting / reflecting surface 4a is condensed so as to form a spot on the photoreceptor, and the scanning speed of the spot is kept constant. I have. In order to obtain such characteristics of the Fθ lens 12, the Fθ lens 12 is composed of two lenses, a spherical lens 6 and a toric lens 7. The rotation of the rotary polygon mirror 4 causes main scanning by the light beam on the photoreceptor 10, and performs sub-scanning by rotating the photoreceptor 10 about the axis of the cylinder. Thus, an electrostatic latent image is formed on the surface of the photoconductor 10. Around the photoconductor 10, a corona discharger for uniformly charging the surface of the photoconductor, a developing device for visualizing an electrostatic latent image formed on the surface of the photoconductor into a toner image, A transfer corona discharger (both not shown) for transferring the toner image to the recording paper is arranged, and by these operations, the recording information corresponding to the luminous flux generated by the semiconductor laser device 1 is printed on the recording paper. .

The folding mirror 8 is a rod-like member elongated in the Y-axis direction, and both ends thereof are pressed against a mirror support (not shown) of the optical box 11 by a plate spring or the like (not shown). The reason why only both ends of the folding mirror 8 are fixed to the mirror support by a leaf spring or the like is to prevent the effective portion of the reflection surface of the folding mirror 8 from being deformed by the pressing force of the leaf spring or the like.

[0005]

However, according to the above prior art, as described above, the folding mirror that folds the scanning light of the rotary polygon mirror toward the photoconductor is fixed at both ends only by leaf springs or the like. Vibration easily occurs because of the long rod-like body. Since the folding mirror reflects the scanning light directly to the photoreceptor, the vibration of the folding mirror causes a large defect in the electrostatic latent image and causes a significant deterioration in image quality.
Therefore, in order to improve the image quality, it is necessary to further reduce the vibration of the folding mirror.

Accordingly, the present invention solves the above-mentioned problems of the prior art, and reduces vibration of the return mirror cover with a simple configuration, avoids troubles due to the return mirror vibration, and greatly improves image quality. It is an object of the present invention to provide a scanning optical device that can contribute.

[0007]

According to the present invention, in order to achieve the above-mentioned object, a scanning optical device is constituted as follows. That is, the scanning optical device of the present invention comprises a laser emitting unit, a rotating polygon mirror, a motor for driving the rotating polygon mirror, and a scanning light scanned in a predetermined scanning direction by the rotating polygon mirror on the photosensitive member. In a scanning optical device having a folding mirror that reflects toward the optical axis and an optical system that forms the scanning light on the photoconductor and housing them in an optical box, a folding mirror cover unit that covers the folding mirror is provided. A part of the optical box configured to form an opening for emitting a laser beam, wherein the shape of the folding mirror cover is shaped to reduce vibration by changing a vibration mode. I have. Further, in the scanning optical device according to the present invention, the shape for reducing the vibration of the return mirror cover is formed by dividing the return mirror cover so that a part in the longitudinal direction is discontinuous. It is characterized by. Further, the scanning optical device of the present invention is characterized in that the divided shape is formed near the center in the longitudinal direction of the folding mirror cover. The scanning optical device according to the present invention is characterized in that the divided shape is formed with a width of 1 to 10 mm. Further, the scanning optical device of the present invention is characterized in that the shape for reducing the vibration of the folding mirror cover is formed by reducing the thickness of a part of the folding mirror cover. Further, the scanning optical device according to the present invention is characterized in that the shape for reducing the material thickness is formed by changing a part of the outer shape of the folding mirror cover. Further, the scanning optical device of the present invention has a shape that changes a part of the outer shape of the folding mirror cover portion,
It is characterized in that it is formed near the center in the longitudinal direction of the folding mirror cover. Further, the scanning optical device according to the present invention is characterized in that the shape for reducing the material thickness is formed by reducing a part of the material thickness inside the folding mirror cover portion.

[0008]

DETAILED DESCRIPTION OF THE INVENTION As described above, the present invention relates to a folding mirror cover portion (hereinafter, referred to as a folding mirror cover portion) formed by a part of the optical box which forms an opening for emitting a laser beam. By making the shape of the arm portion) such that the vibration is reduced by changing the vibration mode, it is possible to avoid the trouble of the vibration of the return mirror and to prevent the deterioration of the image quality due to the vibration of the return mirror. That is, in the related art, vibration is generated by a motor that rotationally drives a rotary polygon mirror, and the vibration generated by the motor is transmitted to both ends of the arm unit, and the vibration is often greatest near the center of the arm unit. The state is fed back to both ends of the arm,
The vibration of the entire arm was to be increased. And there is a support of the folding mirror at both ends of the arm portion, and when the vibration of the folding mirror support increases, the vibration of the folding mirror also increases, which causes the deterioration of the image quality, but according to the present invention, With the above configuration, it is possible to avoid a trouble due to the vibration of the folding mirror.

[0009]

Embodiments of the present invention will be described below. [Embodiment 1] FIG. 1 is a plan view showing Embodiment 1 of the present invention. In the conventional example, as shown in FIGS. 4 and 5, the arm portion 11b prevents the user from touching the folding mirror 8, protects the folding mirror 8, or emits a laser beam. The folding mirror 8 is provided so as to form the opening 9.
It was a long rod-like body as in. In this embodiment shown in FIG. 1, the arm portion 11b is partially cut off at a width of 1 to 10 mm so as to be discontinuous in the longitudinal direction of the arm portion.

With this configuration, the vibration mode of the arm portion 11b is changed by cutting off the transmission path of the vibration, and the vibration of the folding mirror support (not shown) is reduced. Thereby, the vibration of the folding mirror 8 can be reduced, and the trouble due to the vibration of the folding mirror 8 can be avoided. The shape of the partial arm cut may be any shape as long as it is within a width of 1 to 10 mm that is discontinuous in the longitudinal direction. In FIG. 1, the dividing position is divided near the center of the arm portion, but may be divided at any position in the Y direction.

[Embodiment 2] FIG. 2 is a plan view showing Embodiment 2 of the present invention. Instead of dividing the arm portion 11b over the entire surface in the X direction as in Embodiment 1, for example, an The outer shape of the optical box is changed so that the thickness of a part of the arm portion 11b is made smaller than the others. Thereby, if the original purpose of the arm portion 11b is deviated, the return mirror is protected by the lid 11a of the optical box 11. With such a configuration, when the vibration of the arm portion 11b is large, the material thickness is conventionally increased as a measure to increase the rigidity of the arm portion 11b, but the present invention reduces the vibration mode by reducing the material thickness. And the vibration of the arm 11b is reduced. Therefore, the same function and effect as those of the first embodiment can be obtained.
The location, shape, and amount of the material thickness of the arm 11b need not be the shape shown in FIG. 2 depending on how much the vibration mode of the arm 11b is changed. For example, the outer shape of the optical box 11 in the XY plane is not changed as shown in FIG.
The material thickness inside 1b may be reduced in the Z direction.

[0012]

As described above, according to the present invention,
The shape of the folded mirror cover formed by a part of the optical box, which forms an opening for emitting a laser beam, is changed to a shape that reduces vibration by changing the vibration mode, so that the rotating polygonal surface is formed. It is possible to realize a scanning optical device which can avoid troubles caused by the vibration of the return mirror which reflects the scanning light of the mirror toward the photoconductor and greatly contributes to improvement of image quality and the like. Further, according to the present invention, with a simple configuration, it is possible to avoid a trouble due to the vibration of the folding mirror, and it is possible to further reduce the material cost of the optical box and reduce the cost.

[Brief description of the drawings]

FIG. 1 is an explanatory partial plan view of a first embodiment of the present invention.

FIG. 2 is an explanatory partial plan view of a second embodiment of the present invention.

FIG. 3 is an explanatory partial plan view of another modification of the second embodiment of the present invention.

FIG. 4 is a plan view illustrating a configuration of a conventional example.

FIG. 5 is an explanatory sectional view of a conventional example.

[Explanation of symbols]

 1: Semiconductor laser device 4: Rotating polygon mirror 5: Motor for rotating the rotating polygon mirror 8: Folding mirror 9: Opening 11b: Arm

Claims (8)

[Claims] 1. A laser emitting means, a rotating polygon mirror, a motor for rotating the rotating polygon mirror, and a folding back for reflecting scanning light scanned in a predetermined scanning direction by the rotating polygon mirror toward a photosensitive member. In a scanning optical device having a mirror and an optical system for forming an image of the scanning light on a photoconductor, and storing them in an optical box, a folding mirror cover unit that covers the folding mirror emits a laser beam. A scanning optical device, comprising a part of the optical box that forms an opening for reducing the vibration by changing the vibration mode. 2. The method according to claim 1, wherein the shape for reducing the vibration of the folding mirror cover portion is formed by dividing a part of the folding mirror cover portion in the longitudinal direction so as to be discontinuous. Item 2. The scanning optical device according to Item 1. 3. The scanning optical device according to claim 1, wherein the divided shape is formed near a center in a longitudinal direction of the folding mirror cover. 4. The scanning optical device according to claim 2, wherein the divided shape is formed with a width of 1 to 10 mm. 5. The scanning optical system according to claim 1, wherein the shape for reducing the vibration of the return mirror cover is formed by reducing the thickness of a part of the return mirror cover. apparatus. 6. The scanning optical apparatus according to claim 5, wherein the shape for reducing the material thickness is formed by changing a part of the outer shape of the folding mirror cover. 7. The scanning device according to claim 6, wherein a shape that changes a part of an outer shape of the folding mirror cover is formed near a center in a longitudinal direction of the folding mirror cover. Optical device. 8. The scanning optical apparatus according to claim 5, wherein the shape for reducing the material thickness is formed by reducing a part of the material thickness inside the folded mirror cover.