JP2002182144A - Optical scanner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify a mass production stage by eliminating the need of the adjustment of an image position and to improve the image quality by stabilizing the diameter of a laser spot in the case of restraining the variance of the position of a laser beam radiated to a photoreceptor in an optical scanner using a reflection mirror. SOLUTION: A mirror holding member 31 is constituted so that angular moment of the reflection mirror 16 may not be generated by force F1 to restrain the mirror 16 and force F2 received by a frame body 11 from the member 31 as seen from the side surface in a width direction of the mirror 16. Then, it is constituted so that the direction F1 of the force to restrain the mirror 16 and the direction F2 of the force received by the frame body 11 from the member 31 may be mutually aligned and opposed to each other on the center line in the width direction of the mirror 16.

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 for an image information recording device that records an image by scanning a light beam, such as a digital copying machine and a facsimile device.

[0002]

2. Description of the Related Art Generally, in order to form an image by irradiating a photoreceptor with a laser beam, there are very many optical scanning devices that use a reflection mirror for bending an optical path. If you do not make the angle accuracy of this reflecting mirror high enough,
The position in the sub-scanning direction that irradiates the photoreceptor varies, so that the image position on the sheet varies. In such a case, the image position needs to be adjusted for each machine, and the mass production efficiency decreases. Further, when the irradiation position on the photoconductor changes, the optical path length changes and the beam spot diameter increases, which leads to deterioration in image quality.

[0003] Therefore, conventionally, the mirror holding seat surface formed on the frame of the optical scanning device has been extremely high in accuracy.
However, even with a highly accurate mounting surface, the mirror angle is often shifted when the mirror is mounted,
At present, the above problem has occurred.

In view of such a problem, Japanese Patent Laid-Open No. 2000-1
In Japanese Patent No. 31636, the shape of the mirror mounting seat surface,
It is stated that the angle accuracy of the mirror is increased by devising the position of the seat surface.

[0005]

However, in the above-mentioned prior art, as shown in FIG.
If a holding member such as a leaf spring 30 is used to hold the mirror 16 in 1a, there is a problem that the angle of the mirror 16 changes due to the influence of the leaf spring 30 pressing the mirror 16 as shown in FIG. .

Accordingly, the present invention can simplify the mass production process by eliminating the need for image position adjustment when suppressing the variation in the position of the laser beam applied to the photoreceptor in an optical scanning device using a reflection mirror. It is an object of the present invention to provide an optical scanning device capable of stabilizing a spot diameter and improving image quality.

[0007]

In order to achieve the above object, a first means is a light emitting means for emitting a light beam, a deflection scanning means for deflecting and scanning the light beam, and a rectangular reflecting surface for deflecting the light beam. An optical scanning device for fixing the reflection mirror with a holding member to a mounting seat formed to determine the mounting angle and position of the reflection mirror in a frame in which the reflection mirror and the reflection mirror are accommodated,
The holding member is configured so that a rotational moment of the reflection mirror is not generated by a force for holding down the mirror as viewed from a lateral side of the reflection mirror and a force that the frame receives from the holding member. It is characterized by.

The second means is that, in the first means, the holding member has a direction of a force for holding down the reflecting mirror and a force of a force received by the frame from the mirror holding member at a center line in a lateral direction of the reflecting mirror. It is characterized in that they are configured so as to face each other in the same direction.

A third means is the second means, wherein the holding member comprises a mirror-side pressing piece and a frame-side pressing piece, and the reflecting mirror and the frame are formed by the mirror-side pressing piece and the frame-side pressing piece. Are integrally and elastically held.

A fourth means is the third means, wherein the holding member includes a support piece for positioning following the mirror-side pressing piece and the frame-side pressing piece, and a cutout is formed in the supporting piece. It is characterized by having.

A fifth means is the fourth means, further comprising a pin fitted into the notch, for regulating rotation (movement) of the support piece in a direction perpendicular to a longitudinal direction.

The sixth means is characterized in that, in the fourth means, a bent portion is provided on the support piece to regulate the movement (position) in the longitudinal direction (direction parallel to) of the sandwiched reflecting mirror. I do.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a plan view showing an overall configuration of an embodiment of an optical scanning device according to the present invention, and FIG.
3 is an explanatory view showing variations in the sub-scanning direction of the reflection mirror of FIG. 1, FIG. 4 is a perspective view showing a mirror holding member according to the present invention, and FIG. FIG. 5 is an explanatory diagram illustrating an acting force by a mirror holding member of FIG. 4.

In FIGS. 1 and 2, a light source unit 12 for emitting a laser beam is attached to a frame 11, and the laser beam is collected in the sub-scanning direction in the traveling direction of the laser beam from the light source unit 12. A cylinder lens 13 that emits light and a deflection scanning unit 14 that deflects and scans a laser beam from the cylinder lens 13 are sequentially arranged. The deflection scanning unit 14 includes a polygon mirror 14a for reflecting a laser beam, and the polygon mirror 14a.
It is composed of a drive motor 14b for rotating and driving a.

Further, the frame 11 in the traveling direction of the laser beam L1 deflected and scanned by the deflection scanning unit 14 has:
Scanning lenses 15a and 15b including an fθ lens and a surface tilt correction lens for forming an image of the laser beam L1 on the photosensitive drum D (see FIG. 3);
Mirror 16 that reflects the laser beam L2 toward the photosensitive drum D by the reflecting surface 16a toward the photosensitive drum D, a light detection mirror 17 that reflects the laser beam L3 before irradiating the photosensitive drum, and a laser beam from the light detection mirror 17. A light detection unit 18 and the like for detecting L3 are arranged.

In the scanning optical device having such a configuration, the laser beam emitted corresponding to the information to be recorded from the light source unit 12 is condensed in the sub-scanning direction by passing through the cylinder lens 13 and is deflected. The light is reflected by the polygon mirror 14a of the unit 14. Then, the drive motor 14b of the deflection scanning unit 14 rotates the polygon mirror 14a, so that the polygon mirror 14a
Is deflected in the main scanning direction S.
Then, the laser beam L1 is scanned by the scanning lenses 15a and 15b.
Is transmitted, the image is formed on the surface of the photosensitive drum D, and the scanning speed in the main scanning direction S becomes constant on the surface of the photosensitive drum D.

During this time, the return reflecting mirror 16 reflects the laser beam L1 from the scanning lenses 15a and 15b toward the photosensitive drum D as a laser beam L2, and the laser beam L2 passes through an opening at the bottom of the frame 11. Irradiated on the photosensitive drum D. The laser beam L3 upstream in the main scanning direction S is reflected by the light detection mirror 17 and enters the light detection unit 18. Then, the light detection unit 18
A light detection sensor incorporated in the printer detects the laser beam L3 and outputs an electric signal for setting a writing start timing to a controller of the image forming apparatus.

FIG. 3 shows a change in the position of the beam L2 irradiating the photosensitive member D in the sub-scanning direction when a slight angular error of the reflection mirror 16 occurs. It is twice the amount of angle change. Here, it is general that the photosensitive member irradiation position is relatively long from the mirror reflection position. For example, if the width of the mirror 16 is 10 mm, the distance from the reflection point to the photosensitive member irradiation position is 150 mm, the height difference between the mounting seats is shifted by 0.05 mm, and the mirror 16 rotates as shown in FIG. The position will be shifted by about 3 mm.

In view of this, the mounting seat surface for holding the mirror 16 is formed with a very high precision so as to reduce the fluctuation of the beam irradiation position. However, as shown in FIG.
When a holding member such as a leaf spring 30 for holding the mirror 11 is used, the mirror mounting seat surface 1 of the frame 11 is moved by the mirror pressing force F1.
A bending moment acts around 1a, the shape of the mounting seat surface 11a is deformed as shown in FIG. 7, and the angle of the mirror 16 is changed.

Therefore, in this embodiment, a mirror holding member 31 having a shape as shown in FIG. 4 is used. The mirror holding member 31 is configured such that a rotation moment of the reflection mirror 16 is not generated by a force F1 for pressing the mirror 16 and a force F2 received by the frame member 11 from the holding member 31 when viewed from the lateral side of the reflection mirror 16 in the lateral direction. Have been. Further, the direction F1 of the force for holding down the reflecting mirror 16 and the direction F2 of the force received by the frame body 11 from the mirror holding member 31 coincide with each other at the center line in the lateral direction of the reflecting mirror 16 so as to face each other. .

That is, as shown in FIG.
The end of the reflection mirror 16, the mirror-side pressing piece 33 and the frame-side pressing piece 34 that elastically sandwich the frame are formed by bending one end of the support piece 35. In this case, FIG.
As can be seen from the partial cross-sectional view showing the mounted state of (a) and the explanatory view showing the state of the applied force in FIG.
1 receives a force F2 from the mirror holding member 31 perpendicular to the mounting seat surface (flat surface) 11a and a mirror pressing force F1.
In the case of being in a straight line, since a large bending moment is not generated in the frame 11, deformation of the mounting seat surface 11a can be prevented. Further, by configuring the mirror holding member 31 such that the positions where the forces F1 and F2 act on the mirror rotation axis, the mounting posture of the mirror 16 is further stabilized.

The mirror holding member 31 in FIG. 5A is in a cross-sectional view taken along line AA in FIG.
As shown in FIG. 4, a long groove-shaped notch 36 is provided in the upright piece 32 and the support piece 35 rising from the other end side of the support piece 35, and the reflection mirror 16 and the frame 1 are actually mounted.
Then, a pin is erected (fitted) from the notch 36 to the frame 11 side, and the supporting piece is brought into contact with the inner edge of the notch 36 or the pin and the upstanding piece 32. The movement or the position in the direction perpendicular to the direction parallel to the longitudinal direction of 35 is regulated.

By the method of attaching the mirror 16, the irradiation position of the beam L2 on the photosensitive member D is not varied, and the adjustment of the image position can be omitted in the mass production process, and the mass production efficiency is improved. Further, variation in the diameter of the beam L2 was suppressed, and the image quality was improved.

[0024]

As described above, according to the first aspect of the present invention, the force of the mirror holding member for holding down the mirror as viewed from the lateral side of the reflecting mirror and the force of the frame body received from the holding member are determined by the following. Since the configuration is such that the rotational moment of the reflection mirror is not generated, a large bending moment is not generated in the frame body, and therefore, the deformation of the mounting seat portion can be prevented. Therefore, the mass production process can be simplified by eliminating the need for image position adjustment, and the image quality can be improved by stabilizing the laser spot diameter.

According to the second aspect of the present invention, the direction of the force for holding down the reflecting mirror and the direction of the force received by the mirror holding member from the mirror holding member coincide with each other at the center line in the lateral direction of the reflecting mirror. Since the mirror holding stability is further improved, the above-described effect can be enhanced.

According to the third aspect of the present invention, the holding member includes the mirror-side pressing piece and the frame-side pressing piece, and the reflecting mirror and the frame are integrally formed by the mirror-side pressing piece and the frame-side pressing piece. Claim 2 has a simple structure because it is held elastically.
The effects of the described invention can be obtained.

According to the fourth aspect of the present invention, the holding member includes the support piece for positioning following the mirror-side pressing piece and the frame-side pressing piece, and the support piece is formed with a notch. The position can be regulated using the notch.

According to the fifth aspect of the present invention, a pin is fitted into the notch, and the movement of the support piece in the direction perpendicular to the longitudinal direction is regulated. The effect can be obtained.

According to the sixth aspect of the present invention, an upright piece is provided at an end of the support piece on a side different from the side on which the mirror-side pressing piece and the frame-side pressing piece are formed, thereby restricting the longitudinal movement of the sandwiched reflecting mirror. Therefore, it is possible to regulate the position of the holding member by using the upright pieces provided integrally with the holding member.

[Brief description of the drawings]

FIG. 1 is a plan view showing an overall configuration of an embodiment of an optical scanning device according to the present invention.

FIG. 2 is a sectional view taken along the line EE of FIG. 1;

FIG. 3 is an explanatory diagram showing variations in the sub-scanning direction of the reflection mirror of FIG. 1;

FIG. 4 is a perspective view showing a mirror holding member according to the present invention.

FIG. 5 is an explanatory diagram showing a holding state and an acting force by a mirror holding member of FIG. 4;

FIG. 6 is a side view showing a conventional mirror holding member.

FIG. 7 is an explanatory diagram showing variations in the sub-scanning direction of the reflection mirror by the mirror holding member of FIG. 6;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Frame 11a Mounting seat surface 16 Reflection mirror 31 Mirror holding member 32 Standing piece 33 Mirror side pressing piece 34 Frame side pressing piece 35 Supporting piece 36 Notch

 ────────────────────────────────────────────────── ─── Continued on the front page F term (reference) 2C362 AA43 AA45 BA87 BA90 DA03 2H043 CA04 CA07 CE00 2H045 CB22 DA02 DA41 5C051 AA02 CA07 DB22 DB24 DB30 DC07 DE21 FA01 5C072 AA03 BA02 BA17 DA02 DA04 DA21 HA02 HA09 HA13

Claims (6)

[Claims] 1. A reflection mirror mounted on a frame housing a light emitting means for emitting a light beam, a deflection scanning means for deflecting and scanning the light beam, and a reflection mirror for reflecting the light beam by a rectangular reflecting surface. In an optical scanning device for fixing the reflection mirror with a holding member to a mounting seat surface formed so as to determine an angle and a position, the holding member is a mirror viewed from a side surface of the reflection mirror in a lateral direction. A scanning optical device, wherein a rotation moment of the reflection mirror is not generated by a holding force and a force that the frame receives from a holding member. 2. The holding member is configured such that a direction of a force for suppressing the reflection mirror and a direction of a force received by the frame from the mirror holding member coincide with each other and are opposed to each other at a center line in a lateral direction of the reflection mirror. The optical scanning device according to claim 1, wherein: 3. The holding member includes a mirror-side pressing piece and a frame-side pressing piece, and the reflecting mirror and the frame are integrally and elastically held by the mirror-side pressing piece and the frame-side pressing piece. 3. The optical scanning device according to claim 2, wherein: 4. The holding member has a support piece for positioning following the mirror-side pressing piece and the frame-side pressing piece, and a cutout is formed in the supporting piece. The optical scanning device according to claim 1. 5. The optical scanning device according to claim 4, further comprising a pin that fits into the notch, and restricts movement of the support piece in a direction perpendicular to a longitudinal direction. 6. An upright piece is provided at an end of the support piece that is different from the mirror-side pressing piece and the frame-side pressing piece forming side.
5. The optical scanning device according to claim 4, wherein movement of the sandwiched reflection mirror in the longitudinal direction is restricted.