JP2583154B2 - Optical system mirror holding device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved technique of a mirror holding device of an optical system in an image reading apparatus such as an electrostatographic copying machine or a printer.

[Conventional technology]

For example, one of the exposure devices provided in an electrostatographic copying machine includes a light source for irradiating a document surface on a contact glass and a first light source.
A first mirror frame having a mirror and a second mirror frame having second and third right-angle mirrors for reflecting light reflected from the first mirror twice are provided so as to be reciprocally movable in the document scanning direction. In addition, there is a so-called optical system movable exposure apparatus provided with a fourth mirror that reflects the light transmitted through the imaging lens unit by reflecting the third mirror toward the surface of the photoconductor.

In order to increase the parallelism of the mirror in such an optical system and prevent image blurring, means for urging and holding the two ends in the longitudinal direction of the mirror at a total of three points are employed.

As an example of the mirror holding means, a mirror holding member provided with a mirror insertion hole is provided at a portion corresponding to both sides of the mirror, and a mirror inserted into the mirror insertion hole is provided in a mirror holding member near the mirror insertion hole. A first projection that supports one end in the longitudinal direction of the mirror at one point in the middle portion in the width direction, and a second projection and a third projection that support the other end in the longitudinal direction of the mirror at two points in the width direction. There is a type provided with a first urging means for urging toward the first projection and a second urging means for urging toward the second and third projections.

For example, in the holding device for the fourth mirror, the mirror holding members for holding both ends in the longitudinal direction of the mirror are configured to be individually changeable in posture around an axis parallel to the rotation axis of the photoconductor. By changing the reflection angle of the fourth mirror by the operation of changing the attitude of the mirror holding member, the position of the latent image of the scanned image on the surface of the photoconductor can be adjusted in the rotation direction of the photoconductor.

[Problems to be solved by the invention]

However, when adjusting the mirror reflection angle, it has been extremely difficult to change the attitude of the mirror holding members individually without breaking the balance of the resolving power in the rotation axis direction of the photoconductor.

In addition, since the center of the angle change is located at a position distant from the mirror, the optical path length changes greatly with the above angle adjustment, and it is difficult to form a latent image of a predetermined magnification on the surface of the photoconductor. was there.

The present invention has been made in view of such circumstances, and can easily form a latent image of a predetermined magnification on the surface of a photoreceptor without losing the balance of resolution by a rational improvement technique, It is another object of the present invention to provide a mirror holding device of an optical system which can prevent a situation in which a mirror is lifted from a mirror holding member or a mirror edge is broken.

[Means for solving the problem]

In order to achieve the above object, a mirror holding device for an optical system according to the present invention includes a mirror configured to bias and support both longitudinal ends of the mirror at three points in a thickness direction as described at the beginning. In the holding device, the mirror holding member is provided with a mirror support protrusion for supporting the bottom surface of the mirror at one point at an intermediate portion in the thickness direction, and the second and third protrusions for supporting the other end of the mirror at two points. One of the projections on the side remote from the mirror support projection is configured to be freely changeable in the projection projection direction.

[Action]

The mirror holding device of the optical system according to the present invention configured as described above, by changing the position of only one of the two protrusions at the other end in the longitudinal direction of the mirror in the protrusion projecting direction, makes the mirror in the longitudinal direction of the mirror. The reflection angle of the mirror is changed around the first protrusion with one end following. In addition, the configuration in which the bottom portions at both ends in the longitudinal direction of the mirror are supported at one point by the mirror support protrusions is conventionally used when the position of one protrusion on the side remote from the mirror support protrusions is changed to change the reflection angle of the mirror. Unlike the configuration in which the bottom surface of the mirror is supported by the flat edge of the mirror insertion hole provided in the mirror supporting member, the one mirror edge moves so as to rub the flat edge of the mirror insertion hole, and the other. Well prevents the mirror edge from rising from the flat edge.

〔Example〕

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 2 shows an electrostatographic copying machine as an example of an image forming apparatus, in which a copying machine main body 3 provided with a document table 1 and a document holder 2 on an upper portion.
A charging device 5, a developing device 6, a transfer device 7, a sheet separating device 8, and a cleaning device 9 are arranged around the photosensitive member 4, and An optical system movable exposure device 10 is provided in the space, and a paper feed transport device 12 that transports the paper in the cassette case 11 to the transfer device 7 and a paper discharge transport device that transports the separated paper to the fixing device 13. 14, and the paper after fixing
A pair of paper discharge rollers 16 for discharging paper to 15 are provided.

The optical system movable type exposure apparatus 10 includes a first optical traveling body 19 having a light source 17 for projecting an original on the original table 1 and a first mirror 18 for reflecting light reflected from the original table 1 again. , The first
Second reflection of the reflected light from the mirror 18 twice
And a second optical traveling body 22 having third mirrors 20, 21 reciprocally movable in the original scanning direction, and a fourth mirror for reflecting light reflected by the third mirror 21 toward the surface of the photoreceptor. 23, an imaging lens unit 24 is provided in the optical path from the third mirror 21 to the fourth mirror 24, and the first optical traveling body 19 is connected to the second optical traveling body 22.
And a driving device (not shown) of a known configuration for reciprocating in the document scanning direction at twice the speed of the original.

FIG. 1 shows a holding device 25 for the fourth mirror 23. As shown in FIGS. 3 to 5, the mirror holding device 25 has a vertical plate portion 26a having a mirror insertion hole a formed therein. The pair of mirror holding members 26
At the portions corresponding to both ends in the longitudinal direction of the mirror 23, they are fixed by screws, spot welding, or the like, and the mirror insertion hole a of the one mirror holding member 26 is inserted into the mirror insertion hole a. A first projection c for supporting the surface on one end side of the mirror 23 at one point in the width direction intermediate portion is formed, and a mirror insertion hole a of the other mirror holding member 26 is inserted through the mirror insertion hole a. A second projection d is formed to support the back surface at the other end of the four mirror 23 at one point on the lower side in the width direction.

At the lower end of each mirror insertion hole a of the mirror holding member 26, a mirror support projection f for supporting the bottom surface of the fourth mirror 23 at the middle in the thickness direction is formed.

A projection mounting plate 28 is bent and connected to the other mirror holding member 26 toward the back side of the fourth mirror 23, and the projection mounting plate 28 is inserted through the mirror insertion hole a. A screw-type third projection e for supporting the rear surface of the other end of the fourth mirror 23 at a point on the upper side in the width direction is screwed, and the third projection e and the second projection d allow the The back surface at the other end of the four mirror 23 is supported at two points in the width direction.

Further, a first urging means 29 for urging one end in the longitudinal direction of the fourth mirror 23 toward the first protrusion c in the mirror insertion hole of the mirror holding member 26, A second end urging the other end in the direction toward the second and third protrusions d and e.
A biasing means 30 is provided to bias and hold both ends in the longitudinal direction of the fourth mirror 23 at a total of three points.

According to the above configuration, since the fourth mirror 23 is supported at three points, its parallelism is enhanced, and image blur is prevented.

As shown in FIG. 6, one third projection e, which is to support two points on the other end side in the longitudinal direction of the fourth mirror 23 and is apart from the mirror support projection f, is repositioned in the projection projection direction. By doing so, the one mirror in the longitudinal direction of the fourth mirror 23 follows the urging force of the first and second urging means 29, 30 so that the reflection angle of the fourth mirror 23 becomes It is changed around the first protrusion c that supports one end of 23 at one point.

Thus, when viewed in the longitudinal direction of the fourth mirror 24, one end in the longitudinal direction of the fourth mirror 23 follows the movement of the other end in the longitudinal direction, centering around the reflection point of the incident light on the fourth mirror 23. Since the reflection angle of the fourth mirror 23 is changed, the balance of the resolving power in the rotation axis direction of the photoconductor 4 is not lost, and the optical path length from the lens unit 24 to the photoconductor surface is almost changed. Without this, a latent image of a predetermined magnification with excellent resolution is formed on the surface of the photoconductor.

Further, since the bottom surface of the fourth mirror 23 is supported at one point by the mirror support protrusion f, even if the reflection angle of the fourth mirror 23 is repeatedly changed, the lifting of the fourth mirror 23 and the damage of the mirror edge are effective. Is prevented.

That is, conventionally, generally, the bottom surface of the fourth mirror 23 is supported by the flat edge of the mirror insertion hole a. However, when such a structure is adopted in the mirror holding device 25 according to the present invention, The fourth mirror 23 is pressed by the third projection e against the urging means 29, and the reflection angle of the fourth mirror 23 is set to the first angle.
When changing around the projection c, one mirror edge moves so as to rub against the flat edge of the mirror insertion hole a, and the other mirror edge comes up from the flat edge.

In this way, there is a concern that the one mirror edge may be moved by rubbing the flat edge, thereby damaging the mirror edge. If the fourth mirror 23 is moved in the returning direction around the first protrusion c for adjusting the angle, there is a disadvantage that the entire bottom surface of the mirror is raised.

However, in the configuration of the present invention, the mirror bottom surface is configured to be supported at one point by the mirror support protrusion f, so that the floating of the fourth mirror 23 and the breakage of the mirror edge are effectively prevented.

In the above configuration, according to the present invention, the first and second urging means 29 and 30 have the same configuration, and the urging directions thereof are different from each other, so that the first and second urging means 29 and 30 are disposed between the mirror insertion hole a and the fourth mirror 23. A specific structure of the second urging means 30 with respect to the other end of the mirror will be described mainly with reference to FIG.

The second biasing means 30 is configured to bend the single leaf spring 31 twice in the same direction, for example, at 90 degrees and 95 degrees, and to move the mirror holding portion h (see FIG. 1) which extends freely in the free state. At the same time, the first retaining portion j that engages with the edge of the hole i formed near the second projection d of the mirror holding member 26 is provided on one spring plate portion 31a that forms the mirror holding portion h. And the tip of the one spring plate portion 31a is inclined outward to facilitate insertion of the tip into the hole i and insertion of the mirror 23 into the mirror holding portion h. .

Then, the other spring plate portion 31b forming the mirror holding portion h is bent in a substantially U-shape toward the side opposite to the bending direction thereof, and a spring is formed on the substantially U-shaped portion 31c. At the same time, outwardly projecting portions m and n are bent and connected to the middle portion and the tip portion of the other spring plate portion 31b to be opposite to the second projection d of the mirror insertion hole a. Second side fitting edge
A retaining portion r is formed.

Further, the substantially U-shaped portion 31c having the spring property is
Between the two-point support portions formed by the second and third protrusions d and e, the fourth mirror 23 is partially divided in the width direction. More specifically, as shown in FIGS. The slits t are formed in the substantially U-shaped portion 31c of the portion corresponding to the first projection c when viewed in the longitudinal direction, and the urging portions 30A, 30B which bend and deform separately on both sides in the width direction of the fourth mirror 23. It is composed.

The attachment of the fourth mirror 23 to the mirror holding member 26 by the second urging means 30 having the above configuration and the first urging means 29 having the same configuration is performed, for example, as follows.

First, a state in which a substantially U-shaped portion 31c is located on the mirror insertion hole a in which the first protrusion c supporting the one end in the longitudinal direction of the fourth mirror 23 is formed, opposite to the first protrusion c. Thus, the substantially U-shaped portion 31c of the first urging means 29 is inserted from the outside of the mirror holding member 26, and the first retaining portion j of the first urging means 29 is formed near the first projection c. The second retaining portion r is fitted to the edge of the hole i.
The first projection c is fitted to the edge on the opposite side to
The first urging means 29 is attached to the mirror holding member 26 on which the projection c is formed.

Then, one end in the longitudinal direction of the fourth mirror 23 is inserted between the other spring plate portion 31b forming the mirror holding portion h of the first urging means 29 and the first protrusion c, and One end of the fourth mirror 23 in the longitudinal direction is biased and held toward the first projection c.

Next, in a state where the substantially U-shaped portion 31c is located on the opposite side to the second protrusion d that supports the other end in the longitudinal direction of the fourth mirror 23, the fourth mirror 23 is placed on the mirror holding portion h. In a state where the other end in the longitudinal direction of 23 is inserted, the substantially U-shaped portion 31c of the second urging means 30 is inserted into the mirror insertion hole a from outside the mirror holding member 26, and the 2 urging means 30
The first retaining portion j is fitted to the edge of the hole i formed near the second projection c, and the second retaining portion r is connected to the edge of the mirror insertion hole a opposite to the second projection d. And the other end in the longitudinal direction of the fourth mirror 23 is connected to the second and third mirrors.
The projections d and e are biased and held.

By the way, the other end of the fourth mirror 23 in the longitudinal direction is
And the second urging means 30 for urging toward the third protrusions d and e,
When one leaf spring 31 is bent in a substantially U-shape and the second urging means 30 is provided between two points of the second and third projections d and e, the fourth When the position of the third protrusion e is changed in a direction against the second urging means 30 for changing the reflection angle of the mirror 23, the stress is applied to the second protrusion d of the second urging means 30. Also transmitted to the corresponding portion, the substantially U-shaped portion 31c corresponding to the second protrusion d is bent, and as a result,
The fourth mirror 23 rises slightly from the second protrusion d, and the reflection angle of the fourth mirror 23 cannot be adjusted as predetermined.

In this regard, if the spring constant of the leaf spring 31 is reduced, the second biasing means 30 bends in accordance with the change in the reflection angle of the fourth mirror 23, thereby eliminating the lifting of the fourth mirror 23. However, in this case, there is a disadvantage that the fourth mirror 23 is easily displaced due to the vibration of the body.

Therefore, in the present invention, the substantially U-shaped portion 31 of the second urging means 30 is used.
A slit t is formed in c to form biasing portions 30A and 30B divided on both sides in the width direction of the fourth mirror 23.
By means of 0A and 30B, the fourth mirror 23 is separately biased toward the second and third protrusions d and e on both sides in the width direction.

According to such a configuration, when the reflection angle of the fourth mirror 23 is changed, if the position of the third protrusion e is changed in a direction against the second urging means 30, the stress corresponds to the third protrusion e. The fourth mirror 23 is absorbed by the urging portion 30B and is not transmitted to the urging portion 30A corresponding to the second protrusion d, so that the fourth mirror 23 is effectively prevented from rising from the second protrusion d.

Alternatively, two urging means are provided on both sides in the width direction at the other end in the longitudinal direction of the fourth mirror 23, and the other end in the longitudinal direction of the fourth mirror 23 is separately provided with the second and third protrusions d, Even if biased toward e, it is possible to prevent the fourth mirror 23 from floating from the second projection d, but this increases the number of parts and is disadvantageous in terms of cost, and is small. A cumbersome operation of interposing the urging means 29 in a narrow portion is required, and there is a disadvantage that the workability of assembling is deteriorated.

In this regard, according to the present invention, a slit t is formed in the substantially U-shaped portion 31c so that one second urging means 30 has apparently two urging portions 30A and 30B. As a result, workability is improved.

The second biasing means 30 is composed of a single leaf spring 31. For example, this is replaced with a rubber plate, and this rubber plate corresponds to the first protrusion c when viewed in the longitudinal direction of the mirror 23. Deformation such as partial division at the site is possible, that is, the urging member constituting the second urging means 30 can be variously selected.

Further, in the embodiment, the first and second urging means 29 and 30 have the same configuration, but the first urging means 29 can be implemented in a non-divided configuration.

Further, in the embodiment, the mirror holding device 25 for the fourth mirror 23 has been described, but the first to third mirrors 1
8, 20, 21 can be the object of the present invention,
Alternatively, two points, that is, one point on the surface on one end in the longitudinal direction and the back on the other end in the longitudinal direction of the fourth mirror 23 are biased and held. Needless to say, the present invention can be implemented by urging and holding two points and one point on the back surface on the other end side in the longitudinal direction, or by holding and holding three points on the front side or the back side.

〔The invention's effect〕

As described above, the mirror holding device of the optical system according to the present invention employs a simple improvement technique in which only one of the two protrusions supporting the other end of the mirror is changed in the protrusion protrusion direction. The reflection angle of the mirror can be changed by a simple operation without breaking the balance of the resolving power in the direction of the rotation axis, and almost without changing the optical path length that leads to a change in the magnification of the latent image. By supporting the bottoms of both ends in the longitudinal direction of the mirror at one point by the mirror supporting projections, it is possible to effectively prevent the mirror from being lifted or the mirror edge from being damaged when the reflection angle of the mirror is changed, and as a result, Without disturbing the balance of the resolution in the direction of the rotation axis of the photosensitive member, and without substantially changing the optical path length leading to a change in the magnification of the latent image, and
There is an advantage that the effect that the reflection angle of the mirror can be changed with a simple operation can be more effectively exerted.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a mirror holding device, FIG. 2 is a vertical side view of an electrostatographic copying machine as an example of an image forming apparatus, and FIG. 3 is a vertical cross section showing a holding structure at the other end in the longitudinal direction of the mirror. FIG. 4 is a side view showing a holding structure at one end in the longitudinal direction of the mirror. FIG. 5 is a longitudinal plan view of the other end in the longitudinal direction of the mirror mainly showing the second urging means. It is explanatory drawing of a reflection angle change of a mirror. 23 mirror 26 mirror holding member 29 first urging means 30 second urging means c first projection d second projection e third projection , F... Mirror support projections.

Claims (2)

(57) [Claims] A mirror holding member is provided at a portion corresponding to both ends of the mirror in order to hold both ends in the longitudinal direction of the mirror in the optical system, and one of the mirror holding members is provided on one of the mirror holding members.
A second projection for supporting one end of the mirror in the longitudinal direction at one point in the middle portion in the width direction, and supporting the other end of the mirror at two points in the width direction on the other end of the mirror holding member; And a third projection, and a first biasing means for biasing the mirror toward the first projection and a second biasing means for biasing the mirror toward the second and third projections. In the holding device, the mirror holding member is provided with a mirror support protrusion for supporting the bottom surface of the mirror at one point at an intermediate portion in the thickness direction, and the second and third protrusions for supporting the other end of the mirror at two points. A mirror holding device for an optical system, wherein one of the protrusions on the side remote from the mirror support protrusion is configured to be freely changeable in the protrusion protrusion direction. 2. The mirror according to claim 2, wherein said second urging means is constituted by one urging member, and said urging member is partially divided at a portion corresponding to said first projection in a longitudinal direction of said mirror. 3. The mirror holding device for an optical system according to claim 1, wherein the first and second projections are individually biased toward the second and third projections.