JP3653059B2 - Document reader - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an original reading apparatus in which a light beam is folded using a mirror .
[0002]
[Prior art]
Many apparatuses such as a copying machine, a facsimile machine, and a printer use a light beam to read an image or record an image. In such a document reading apparatus , an optical system using a plurality of mirrors is used to increase the optical path length or greatly enlarge an image in a relatively narrow space, and the light beam is folded between them. Often to do.
[0003]
However, when such an optical system is adopted, when the mirror vibrates due to components such as a solenoid and a motor in the apparatus in which the optical system is accommodated or external force, the irradiation position of the light beam reflected thereby is fixed at a fixed position. However, problems such as deterioration of the quality of the formed image occur. Various proposals have been made to reduce or eliminate such problems.
[0004]
For example, in Japanese Utility Model Laid-Open No. 1-142913, a rigid plate is bonded to the back surface of a glass plate constituting a mirror in a laser beam optical system that reflects a laser beam on a mirror and irradiates a photosensitive member through an elastic bonding portion. doing. Thereby, since the rigidity of the mirror itself is increased, the occurrence of the vibration of the mirror can be suppressed even by the vibration of the motor or the like.
[0005]
However, in this prior art, if the flatness of the glass plate surface to which the rigid plate is bonded is poor, the rigid plate is bonded to this surface, so that the mirror surface, which is the opposite surface, is distorted. . Therefore, when the mirror surface is distorted, there is a problem in that the same distortion occurs in the image formed by reflection, resulting in deterioration of image quality. Japanese Patent Application Laid-Open No. 10-282399 proposes that image quality does not deteriorate even when the flatness of the surface opposite to the mirror surface is low.
[0006]
FIG. 4 shows a mirror of the optical system proposed in this publication. A reinforcing member 12 is bonded to one side surface along the longitudinal direction of the mirror 11 with a double-sided tape 13. It is also possible to adhere the reinforcing member 12 to the mirror 11 with an adhesive instead of the double-sided tape 13. Thus, if the reinforcing member 12 is bonded to one side or both sides of the side surface along the longitudinal direction of the mirror 11, the rigidity thereof is increased. Therefore, the natural vibration frequency of the mirror 11 can be increased, and the occurrence of vibration can be prevented. In Japanese Patent Laid-Open No. 4-149540, the center of the mirror is held by a support member to increase the rigidity.
[0007]
However, the conventional document reading apparatus shown in FIG. 4 requires the reinforcing member 12 having the same length as the mirror. Similarly to Japanese Utility Model Laid-Open No. 1-142913, if the flatness of the bonding surface of the reinforcing member 12 is not sufficiently high, the mirror surface is distorted by bonding, thereby deteriorating the image quality. In the technique described in Japanese Patent Application Laid-Open No. 4-149540, since the central portion of the mirror is supported by the support member, the support member may bend the mirror. For this reason, there exists a problem that the dimension management of a supporting member is difficult.
[0008]
FIG. 5 shows a main part of another document reading apparatus conventionally proposed. In this document reading apparatus proposed in Japanese Patent Laid-Open No. 11-187224, leaf springs 22 and 23 are arranged at both ends of the surface opposite to the reflecting surface of the mirror 21 to give an upward pressing force in the figure. On the other hand, two auxiliary projections 24 ₁ and 24 ₂ are arranged downward at one end on the reflective surface side, and three auxiliary projections 25 _{1 to} 25 ₃ are similarly arranged downward at the other end on the reflective surface side. doing. Then, pouring the three auxiliary protrusions 25 ₁ to 25 auxiliary protrusion 25 _1, 25 ₃ and the adhesive 26 in the gap of the mirror surface of a position close to both sides of the _three, the position of both the hardening of the adhesive 26 I try to fix the relationship. The adhesive 26 is of a type that initially has a predetermined viscosity enough to fill the gap, gradually cures with time, and does not easily shrink with curing. The adhesive 26 is cured while following the reflecting surface of the mirror 21 over time. Therefore, after curing, the adhesive 26 supports the side end portion without deforming the mirror 21. Accordingly, there is an effect that when vibration is generated in the twisting direction of the mirror, this can be efficiently suppressed.
[0009]
[Problems to be solved by the invention]
However, in the technique described in Japanese Patent Application Laid-Open No. 11-187224, both sides of the mirror surface are fixed, so that vibration in the twisting direction of the mirror 21 can be suppressed, but the longitudinal direction of the mirror It is impossible to suppress the vibration in the direction perpendicular to the mirror surface having the maximum amplitude at the center. For this reason, in particular, in a document reading apparatus using a folding mirror, when two opposing mirrors vibrate at the center in the longitudinal direction of the mirror, this causes the interval between the reflecting surfaces to fluctuate irregularly. Problems such as degradation of the quality of the image formed as in the prior art still remain.
[0010]
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an original reading apparatus capable of effectively attenuating vibration of a mirror by an optical system in which two mirrors are arranged opposite to each other so as to fold a light beam.
[0011]
[Means for Solving the Problems]
In the first aspect of the present invention, (a) a pair of mirrors arranged so that the reflecting surfaces are opposed to each other at a predetermined interval and the light beam is folded between these reflecting surfaces, and (b) the pair of mirrors One or more vibration suppressing members having one end fixed to one side and the other end slidably contacting the side surface of the other mirror are provided in the document reading apparatus .
[0012]
That is, in the first aspect of the present invention, one end of one or a plurality of vibration suppressing members is fixed to one of the pair of mirrors facing the reflecting surfaces, and the other end is slidably brought into contact with the side surface of the other mirror. Both mirrors that fold the light beam vibrate. When the distance between the two mirrors fluctuates with the amplitude or the like at the position of the vibration suppression member, the vibration suppression member slides on the side surface of the other mirror described above and is converted into frictional heat, thereby suppressing the vibration itself. become. The vibration suppressing member may be attached to a plurality of locations of the mirror, or may be attached to one location.
[0013]
In the invention described in claim 2, (a) a pair of mirrors arranged so that the reflecting surfaces are opposed to each other at a predetermined interval and the light beam is folded between the reflecting surfaces, and (b) the pair of mirrors One end is fixed to a surface other than the reflection surface corresponding to the outside of the folded light beam on one reflection surface , and the other end is slidable on a side surface located outside the region of the reflected light beam on the reflection surface of the other mirror. The document reading apparatus is provided with one or a plurality of vibration suppressing members made of a leaf spring brought into contact with the document reading device .
[0014]
That is, in the second aspect of the present invention, one end of one or a plurality of vibration suppression members made of a leaf spring is fixed to one of the pair of mirrors facing the reflecting surfaces, and the other end is slid on the side surface of the other mirror. By freely contacting, both mirrors that fold the light beam vibrate. Here, the vibration suppressing member is attached outside the region where the light beam is reflected by these mirrors, so that the attachment location itself does not adversely affect the vibration of the mirror. When the distance between the two mirrors fluctuates with the amplitude or the like at the position of the vibration suppression member, the vibration suppression member slides on the side surface of the other mirror described above and is converted into frictional heat, thereby suppressing the vibration itself. become. The vibration suppressing member may be attached to a plurality of locations of the mirror, or may be attached to one location.
[0015]
According to a third aspect of the present invention, in the document reading device according to the first or second aspect, the portion of the vibration suppressing member that contacts the side surface of the mirror forms an arc.
[0016]
That is, in the third aspect of the invention, the portion of the vibration suppression member that contacts the side surface of the mirror forms an arc, and this contact portion exerts a force in the direction perpendicular to the side surface of the mirror, so that vibration is effectively prevented. In addition to being attenuated, there is no possibility of bending the mirror by the contact of the vibration suppressing member.
[0017]
According to a fourth aspect of the present invention, in the document reading device according to the first or second aspect, the vibration suppressing member is in contact with one end of the mirror in the longitudinal direction.
[0018]
That is, in the invention according to claim 4, in general, attention is paid to the fact that the angular change is the maximum point in many vibration modes in the vicinity of the end of the elongated mirror, and the vibration suppressing member is located at one end in the longitudinal direction of the mirror. The contact is efficiently suppressed to suppress vibration.
[0019]
According to a fifth aspect of the invention, in the document reading device according to the first or second aspect, the vibration suppressing member is in contact with the maximum amplitude position of a specific vibration mode in the longitudinal direction of the mirror.
[0020]
That is, in the fifth aspect of the invention, the vibration suppressing member is brought into contact with the maximum amplitude position of the specific vibration mode so as to efficiently suppress the vibration.
[0021]
The invention according to claim 6 is the document reading apparatus according to claim 1 or 2, wherein a predetermined elastic member is interposed between the vibration suppressing member and the side surface of the mirror.
[0022]
That is, the invention according to claim 6 shows that the vibration suppressing member and the mirror do not need to be in direct contact with each other, and an elastic member may be interposed.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
[0024]
【Example】
Hereinafter, the present invention will be described in detail with reference to examples.
[0025]
FIG. 1 shows a main part of an original reading apparatus according to an embodiment of the present invention. In this document reading device 50, flat plate-like first and second mirrors 51 and 52 for folding a light beam are arranged so that their reflecting surfaces face each other and are parallel to each other. The first and second mirrors 51 and 52 are each fixed by a known fixing method that does not particularly deflect the mirror surface. As such a fixing method, for example, as described with reference to FIG. 5, both end portions on the opposite side of the reflecting surfaces of the respective mirrors 51 and 52 are pressed with leaf springs, and the both side portions on the reflecting surface side are combined. This is a technique in which a protrusion is applied to a point. A method for fixing the mirror may be other than this, and is not particularly limited.
[0026]
By the way, it is assumed that a linear image 53 is formed at a predetermined upper position in the drawing of the second mirror 52 in parallel with the mirror surface. In the figure, light rays 54 ₁ , 54 ₂ , and 54 ₃ that reach three points P ₁ , P ₂ , and P ₃ that are representative in this image 53 are shown. These light rays 54 ₁ , 54 ₂ , and 54 ₃ are reflected at the position 55 by other mirrors (not shown), and then enter the second mirror 52 first, and the first mirror 51 is expanded while widening the beam interval. Reflected. Then, the light is reflected so as to be folded back to the second mirror 52, and further reflected by the same folding, and then reflected by the second mirror 52 and then as a linear image 53, for example, on a photoconductor (not shown). An image will be formed.
[0027]
In a document reading apparatus having such an optical system, a leaf spring 56 is attached to the back surface of the second mirror 52 and has an L-shape and an arc portion 56A formed at the tip thereof. The arc portion 56 </ b> A is in contact with one side surface 51 </ b> A along the longitudinal direction of the first mirror 51.
[0028]
On the other hand, the attachment position of the leaf spring 56 in the second mirror 52 is a position outside the range of the region used for folding the light beam 54 by the second mirror 52. In the example shown in FIG. 1, the light ray 54 ₃ reaching the point P ₃ is sequentially reflected at three points A, B, and C in the figure of the second mirror 52. The light beams 54 ₁ and 54 ₃ positioned at both ends are widened in the direction in which the linear image 53 is formed after passing through an optical lens (not shown). Accordingly, the region located on the right side of the imaginary line connecting the three points A, B, and C is outside the region used for folding the light beam 54 by the second mirror 52. By attaching the leaf spring 56 at such a position, it is possible to minimize distortion applied to the reflection surface of the light beam 54 in a state where vibration is generated.
[0029]
FIG. 2 is a side view of the main part of the document reading apparatus shown in FIG. On the back surface of the second mirror 52, a fixing portion 56 </ b> B positioned in a substantially horizontal direction of the leaf spring 56 is fixed using fixing means such as an adhesive or a double-sided tape. The portion extending above the leaf spring 56 constitutes a free end. The tip portion forms an arc portion 56A having a predetermined radius, and the protruding portion is in sliding contact with one side surface 51A along the longitudinal direction of the first mirror 51.
[0030]
In such a document reading apparatus, it is assumed that vibrations occur suddenly in the first and second mirrors 51 and 52. When vibration occurs, the first and second mirrors 51 and 52 vibrate thereby, and the distance between them fluctuates irregularly according to the vibration mode. A circular arc portion 56 </ b> A of a leaf spring 56 whose lower part is fixed to the second mirror 52 is in slidable contact with the side surface 51 </ b> A of the first mirror 51. Therefore, when vibrations occur that cause the distance between the first mirror 51 and the second mirror 52 or the position of the mirrors 51 and 52 in the longitudinal direction to fluctuate between them, the arc portion 56A and the first mirror Sliding occurs between the side surface 51A and friction is generated. That is, when the interval or position between the first and second mirrors 51 and 52 is changed by vibration, thermal energy is generated by sliding between the arc portion 56A and the side surface 51A of the first mirror. By converting the vibration energy into heat energy, the vibration between the two is quickly attenuated.
[0031]
In particular, when the sizes of the first and second mirrors 51 and 52 are substantially equal, these mirrors 51 and 52 generally resonate like a tuning fork so as to cancel external forces generated by vibration. As a result, the amplitude of both may become very large. However, in the document reading apparatus 50 of this embodiment, if the distance or position between the first and second mirrors 51 and 52 is changed due to vibration, this is converted into energy by sliding friction and consumed, so that the amplitude is effective. Can be attenuated.
[0032]
The arc portion 56A is in contact with the side surface 51A of the first mirror by an arc. Therefore, in a normal state in which no vibration is generated, the leaf spring 56 only presses the first mirror 51 in the direction parallel to the mirror surface from the side surface 51A, and the first mirror 51 itself is bent. There is no. On the other hand, when the arc portion 56A of the L-shaped leaf spring 56 is eliminated and this portion is formed as a flat plate up to the tip portion and is in contact with the side surface 51A at an inclined angle, there is an effect of suppressing vibration. However, a force in a direction other than the direction parallel to the mirror surface is applied to the first mirror 51 at the contact position. For this reason, although there is a difference in degree, the first mirror 51 is bent.
[0033]
Modifications of the Invention
FIG. 3 shows a main part of an original reading apparatus according to a modification of the present invention. In FIG. 3, the same parts as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted as appropriate. In the document reading apparatus 50A of this modification, two leaf springs 56, 56 having the same shape are attached in the vicinity of both ends of the first and second mirrors 51, 52 so that they are upside down. As described above, it is also effective to arrange a plurality of leaf springs 56 so that each arc portion 56A is slidably brought into contact with the side surface 51A of the first mirror 51 or the side surface 52A of the second mirror 52.
[0035]
Here, the reason why the attachment position on the right side in the drawing of the leaf spring 56 in this modification is different from that in the embodiment in the longitudinal direction of the second mirror 52 will be described. In general, the vicinity of the end of the elongated mirror has a maximum angle change in many vibration modes. Therefore, if the leaf spring 56 is fixed in the vicinity of the end of the second mirror 52 as shown in FIG. 3, the contact portion between the side surface 51A of the first mirror 51 and the circular arc portion 56A is in the longitudinal direction of the mirror and in this direction. Relative movement in the orthogonal direction has the effect of dampening vibrations for all modes of the second mirror 52 as a result.
[0036]
On the other hand, in the embodiment shown in FIGS. 1 and 2, the leaf spring 56 is attached closer to the center of the second mirror 52 than in the modification shown in FIG. This is because a damping effect is obtained with respect to the primary vibration mode. In the case of this embodiment, the relative motion between the arc portion 56A of the leaf spring and the side surface 51A of the first mirror is in the thickness direction of the first mirror 51.
[0037]
In the embodiment and the modification, an arc portion is provided on the leaf spring attached to one mirror and is slidably brought into contact with the side surface of the other mirror. However, the present invention is not limited to this. First, it is natural that vibration can be suppressed even if a curved portion or a straight portion other than the arc portion is brought into contact with the leaf spring. Further, the contact portion between the leaf spring and the mirror does not need to be in direct contact. For example, a member having elasticity may be interposed between them.
[0038]
Further, in the embodiment and the modified example, one leaf spring is brought into contact with one vibration position, but one leaf spring is branched into a Y shape, for example, and is brought into contact with a plurality of vibration positions. May be. Of course, the number of leaf springs may be three or more.
[0039]
【The invention's effect】
As described above, according to the first or second aspect of the present invention, the vibration suppressing member is arranged so as to bridge the pair of mirrors configured to fold the light beam between the reflecting surfaces facing each other. Since the vibration is suppressed by changing the fluctuation of the relative interval into energy, the vibration can be quickly suppressed with a simple component structure without causing the mirror to bend.
[Brief description of the drawings]
FIG. 1 is a perspective view illustrating a main part of a document reading apparatus according to an embodiment of the present invention.
FIG. 2 is a side view of a main part of the document reading apparatus shown in FIG.
FIG. 3 is a perspective view showing a main part of a document reading apparatus according to a modification of the present invention.
FIG. 4 is a perspective view illustrating a state in which a mirror of a conventionally proposed document reading apparatus is fixed.
FIG. 5 is a perspective view illustrating a state in which a mirror of another document reading apparatus conventionally proposed is fixed.
[Explanation of symbols]
50, 50A document reading device 51 First mirror 51A, 52A (mirror side) 52 Second mirror 54 Light beam 56 Leaf spring 56A Arc portion

Claims (6)

A pair of mirrors arranged so that the reflecting surfaces face each other at a predetermined interval and the light beam is folded between these reflecting surfaces;
An original reading apparatus comprising: one or a plurality of vibration suppressing members having one end fixed to one of the pair of mirrors and the other end slidably contacting the side surface of the other mirror. A pair of mirrors arranged so that the reflecting surfaces face each other at a predetermined interval and the light beam is folded between these reflecting surfaces;
One end of the pair of mirrors is fixed to a surface other than the reflection surface corresponding to the outside of the reflected light beam on the reflection surface, and the other end is positioned outside the reflection light beam on the reflection surface of the other mirror. An original reading apparatus comprising: one or a plurality of vibration suppressing members made of a leaf spring that is slidably brought into contact with the side surface. The document reading apparatus according to claim 1, wherein the vibration suppressing member includes a circular arc at a portion that contacts the side surface of the mirror. 3. The document reading apparatus according to claim 1, wherein the vibration suppressing member is in contact with one end of the mirror in the longitudinal direction. 3. The document reading apparatus according to claim 1, wherein the vibration suppressing member is in contact with a maximum amplitude position of a specific vibration mode in a longitudinal direction of the mirror. 3. The document reading apparatus according to claim 1, wherein a predetermined elastic member is interposed between the vibration suppressing member and a side surface of the mirror.

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