JP2000227569A - Light deflection type scanner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the deterioration of the quality of an image to be outputted by minimizing the positional fluctuation of a mirror while light is deflected for scanning. SOLUTION: The mirror 6 reflecting the light deflected by the polygon mirror 1 and transmitted through the mirrors 2 and 3 and an image forming element 5 is pressed to a supporting member and supported at a prescribed position by pressing and energizing the vicinities of both ends of the mirror 6 in the longitudinal direction by using leaf springs 7 and 8. Then, when pressing force by the springs 7 and 8 is defined as F (gf) and the mass of the mirror 6 is defined as M (g), the expression of F/M>14 is satisfied.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an optical deflection scanning device using a mirror.

[0002]

2. Description of the Related Art For example, in a light deflection scanning device used in a laser printer or the like, a mirror is usually used in an optical path from a light source to a photosensitive member as an image carrier. Such a mirror is supported by a configuration as shown in FIGS. 6 and 7, for example.

[0003] That is, for example, the mirror 53 has a substantially central portion mounted on the support members 61 and 62.
2 which is installed at an interval on the fixing portion 50 (FIG. 7) of the device.
Both ends of the reflection surface 53a are in contact with the respective end surfaces of the reflection surface pressing members 66 and 67, and both ends of the back surface 53b of the mirror 53 opposite to the reflection surface 53a are
The two leaf springs 68 are used to control the reflection surface pressing members 66 and 67, respectively.
Pressed to the side. The leaf spring 68 is fixed to the fixing portion 50 by a screw 60. Therefore,
The mirror 53 is turned on the reflecting surface 53 by the urging force of each leaf spring 68.
By pressing a on the end surfaces of the reflection surface pressing members 66 and 67, the inclination of the reflection surface 53a is determined, and the vertical position is determined in FIG.

However, when the mirror is supported by such a configuration, when a driving system provided near the mirror operates, vibration generated from the driving system is transmitted to the mirror, and the mirror is moved. It was easy to vibrate. If the mirror vibrates, the image formation position of the light reflected by the mirror on the photoreceptor is shifted with respect to the target position. As a result, uneven density occurs in an output image. In some cases, the image quality was reduced.

Therefore, in order to solve such a problem,
For example, in Japanese Patent No. 2806015, a temporary resonance frequency f of a reflection mirror provided in an optical path between a light source and a photosensitive member is disclosed.
There has been proposed a raster scanning apparatus in which the relationship between (Hz) and the sub-scanning speed V (mm / sec) of the photoconductor is f / V ≧ 2.

[0006]

However, the one described in Japanese Patent No. 2806015 is based on the premise that the supporting portion of the reflecting mirror is ideally supported, and therefore, is not practical. In some cases, this technology alone was not enough. For example, when the pressing force of the leaf spring pressing the reflecting mirror against the supporting member is small, the natural frequency of the mirror is sufficiently high, and even when the reflecting mirror itself does not resonate at a low frequency, the portion of the leaf spring is relatively large. Vibration occurs at a low frequency, and as a result, the image formation position of the reflected light from the reflection mirror also shifts, so that the image quality tends to deteriorate. FIG. 8 shows Patent No. 2806015
A model in the case where a vibration is generated as described in Japanese Patent Application Laid-Open Publication No. H10-260, FIG. FIG. 9 shows a behavior model of the reflection mirror when the pressing force of the leaf spring pressing the reflection mirror against the support member is small.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has as its object to suppress a change in the position of a mirror during light-deflection scanning, thereby suppressing a deterioration in quality of an output image. And

[0008]

In order to achieve the above object, the present invention provides a light source, an optical deflector for deflecting and scanning light emitted from the light source, and reflecting light deflected by the optical deflector. A light-deflecting scanning device having a mirror to be formed and an image-forming element for forming light from the mirror on an image carrier, wherein an elastic body that applies a pressing force to the mirror in a direction perpendicular to its reflection surface is provided. A supporting member for contacting the mirror pressed by the elastic body is provided, and the mirror is pressed against the supporting member by the pressing force of the elastic body so that the mirror is supported at a predetermined position; Is F (gf) and the mass of the mirror is M (g), so that the relationship of F / M> 14 is satisfied.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram showing an embodiment of a light deflection scanning device according to the present invention, and FIG. 2 is a perspective view showing the vicinity of a mirror of the light deflection scanning device together with an optical box. This optical deflection scanning device includes a light source (not shown), a polygon mirror 1 as an optical deflector for deflecting and scanning light emitted from the light source, and mirrors 2 and 3 for reflecting light deflected by the polygon mirror 1. An image forming element 5 for forming an image of the light from the mirror 3 on a photoreceptor 4 serving as an image carrier, and reflecting the light passing through the image forming element 5 to form an image on the photoreceptor 4. And a mirror 6.

The mirror 6 has an optical box 10 as shown in FIG.
The elastic members are provided in the vicinity of both ends in the longitudinal direction, and are pressed and urged by leaf springs 7 and 8 whose side shapes are clearly shown in FIG. The pressing force of each of the leaf springs 7 and 8 is applied to the mirror 6.
Acts on the reflecting surface 6a in the direction of arrow A perpendicular to the reflecting surface 6a.

The mirror 6 has a leaf spring 7 and an optical box 10
8 are pressed by the pressing force of the leaf springs 7 and 8 against the supporting portions 11 and 12 functioning as supporting members formed respectively corresponding to the supporting members 8 and 8 so as to be supported at a predetermined position (the position shown in FIG. 3). It has become. The pressing force of the leaf springs 7 and 8 is F (gf), and the mass of the mirror 6 is M (g).
, The relationship of F / M> 14 is satisfied.

The following describes the results of experiments conducted to find out that the relationship between the pressing force F by the leaf springs 7 and 8 and the mass M of the mirror 6 needs to satisfy F / M> 14. In the experiment, the primary resonance frequency f (Hz) of the mirror 6 and the sub-scanning speed V (mm / mm) of the photoconductor 4 were measured in a state where the pressing force for pressing the mirror 6 against the support portions 11 and 12 was sufficiently increased.
The material and the shape of the mirror 6 were set so that the relationship with sec) was f / V ≧ 2, and the mass M (g) of the mirror 6 was determined.

Then, the mirrors 6 are formed by the leaf springs 7 and 8.
The pressing force F (gf) of pressing the sample against the supporting portions 11 and 12 was appropriately changed, and the quality of an image output at that time was evaluated by sensory evaluation. In the sensory evaluation, in particular, a plurality of persons evaluated the density unevenness at a pitch of about 1 mm, which is considered to be the most visually noticeable, in seven steps, and the average value was used as an evaluation point. Then, those having an evaluation point of 5 to 7 points were regarded as good images, those having an evaluation point of less than 4 to 5 were regarded as acceptable ranges, and those having an evaluation point of less than 4 points were judged as defective.
The same printer was used to output the image to be evaluated, the same image file was used, and all the components other than the leaf springs 7 and 8 used the same optical deflection scanning device.

The measurement of the pressing force F by the leaf springs 7 and 8 was performed as follows. That is, with the mirror 6 and the leaf springs 7 and 8 assembled at predetermined positions as described with reference to FIGS. 2 and 3, as shown in FIG. Reflective surface 6a
Of the mirror 6 and the supporting portions 11 and 12 when the pressing force is gradually increased by pressing the central portion of the mirror with the force gauge 20 at a substantially right angle to the reflecting surface 6a. To read the value indicated by the force gauge 20,
This was set as the pressing force F.

FIG. 5 shows the results of an experiment performed under the above-described conditions. According to the results of the experiment, when the parameter F / M is larger than 14, a good image with less noticeable density unevenness (evaluation). (Point 5 or more) is obtained. The embodiment and the experimental result in the case where the mirror is supported by the two leaf springs and the two supporting portions have been described above. However, the optical deflection scanning device according to the present invention has a configuration other than the two leaf springs and the two supporting portions. The same can be applied to the above.

[0016]

As described above, according to the optical deflection scanning device according to the present invention, since the position fluctuation of the mirror during the optical deflection scanning can be suppressed to a small value, an image forming apparatus using this optical deflection scanning device can be used. It is possible to suppress a decrease in quality of an output image.

[Brief description of the drawings]

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

FIG. 2 is a perspective view showing the vicinity of a mirror of the light deflection scanning device together with an optical box.

FIG. 3 is a longitudinal sectional view showing a configuration of a portion supporting both ends in a longitudinal direction of a mirror provided in the optical deflection scanning device.

FIG. 4 is a perspective view for explaining a method of measuring a pressing force F by two leaf springs.

FIG. 5 is a diagram showing a relationship between a parameter F / M obtained by an experiment and a sensory evaluation result of an image.

FIG. 6 is a perspective view for explaining a mirror support structure in a conventional light deflection scanning device.

FIG. 7 is a side view showing, in an enlarged manner, a part of the support structure for supporting the mirror in a partially sectional state.

FIG. 8 is a schematic diagram showing a model in a case where vibration occurs as described in a conventional patent publication.

FIG. 9 is a schematic view showing a behavior model of the reflection mirror when the pressing force of the leaf spring pressing the reflection mirror against the support member is small in the apparatus described in the patent publication.

[Explanation of symbols]

 1: polygon mirror 2, 3, 6: mirror 4: photoconductor (image carrier) 5: imaging element 6a: reflection surface 7, 8: leaf spring (elastic body) 11, 12: support section (support member)

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Odanhei 1-3-6 Nakamagome, Ota-ku, Tokyo F-term in Ricoh Co., Ltd. (reference) 2C362 BA83 BA87 BA90 DA16 2H045 AA07 AA33 CB32 DA02 DA04

Claims (1)

[Claims] 1. A light source, an optical deflector for deflecting and scanning light emitted from the light source, a mirror for reflecting light deflected by the optical deflector, and transmitting light from the mirror onto an image carrier. An optical deflection scanning device comprising: an imaging element for forming an image; an elastic body that applies a pressing force to the mirror in a direction perpendicular to a reflection surface of the mirror, and abutting the mirror pressed by the elastic body. A supporting member for causing the mirror to be pressed against the supporting member by the pressing force of the elastic body so that the mirror is supported at a predetermined position; the pressing force of the elastic body is represented by F (gf); Wherein M / g is satisfied so that the relationship of F / M> 14 is satisfied.