JP2004020871A - Picture reader and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a picture reader obtaining a good image by preventing a distortion of a read picture due to oscillation of a mirror on a scanner without causing any problems such as deterioration in the flatness of a mirror reflecting surface, complication or enlargement of the device. <P>SOLUTION: In the picture reader reading a picture of an original by exposing and scanning with the scanner, a second mirror 2 and a third mirror 3 supproted on a second scanner 1, oscillation preventing members 4 and 5 which are of lengths reaching both ends of the mirror at least in the longitudinal direction, a rigid member abutted to both end parts of the reflecting side of the mirror and a plate state spring members 6 and 7 supporting the mirror and the oscillation preventing member by being brought into a pressurized contact with a position which is the same as the mirror at least in the longitudinal direction against an abutting position of the rigid member are provided. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image reading apparatus that reads an original using a scanning body, and can be used in an image forming apparatus such as a copying machine, a scanner, and a facsimile.
[0002]
[Prior art]
In an image reading apparatus that reads an original using a scanning body, when a mirror on the scanning body vibrates and a speed fluctuation of a mechanical system occurs, the interval between halftone dots changes, and a band-like density appears in a halftone portion of an image. There is a problem that banding in which unevenness appears appears and vertical lines of an image are wavy, so-called vertical line fluctuations occur.
[0003]
Therefore, in an image reading apparatus that reads an image of a document by exposing and scanning with a scanning body, the thickness of the mirror is increased as an easy method in order to prevent distortion of the read image due to vibration of the mirror on the scanning body. There is a method of increasing the rigidity of the mirror by doing so. As described above, if the thickness of a 5 mm-thick mirror generally used in an image reading apparatus is increased to, for example, 8 mm, the cost of the 5 mm-thick mirror is significantly increased. For this reason, methods for preventing vibration without increasing the thickness of the mirror on the scanning body have been conventionally studied.
[0004]
For example, JP-A-2001-22009, JP-A-2001-83633, JP-A-2002-72055, JP-A-5-297260, and JP-A-5-297260 disclose vibrations without increasing the thickness of the mirror. The inventions described in JP-A-319077, JP-A-10-206617, JP-A-11-52494, JP-A-11-187224 and the like are known.
[0005]
In the invention described in Japanese Patent Application Laid-Open No. 2002-72055, a plate-like member or a U-shaped plate-like member is attached to the back surface of a mirror to obtain a vibration-proof effect without increasing the mass of the entire mirror.
[0006]
In addition, the invention described in Japanese Patent Application Laid-Open No. 2001-83633 supports the vicinity of both ends in the longitudinal direction of the mirror and also supports the mirror in the center to prevent the mirror from generating vibration.
[0007]
Further, the invention described in Japanese Patent Application Laid-Open No. 7-319077 supports the vicinity of both ends in the longitudinal direction of the mirror, and prevents vibration of the mirror by biasing the vicinity of the center with an elastic foam.
[0008]
In addition, the invention described in Japanese Patent Application Laid-Open No. 5-297260 discloses a method in which a rigid body is rigidly supported at a position within a range of 0.15 to 0.3 times the longitudinal length from both longitudinal ends of the mirror. , To prevent the mirror from vibrating.
[0009]
Further, the invention described in Japanese Patent Application Laid-Open No. H10-206617 is to prevent the occurrence of vibration without deteriorating the flatness of the reflection surface by attaching plate glass to the reflection surface side of the mirror having a high flatness. is there.
[0010]
Further, the invention described in Japanese Patent Application Laid-Open No. 11-187224 is to prevent the vibration by supporting both end portions of the mirror with at least two support portions, and bonding at least one of them. is there.
[0011]
Further, the invention described in Japanese Patent Application Laid-Open No. 11-52494 prevents a mirror from falling off or a position shift due to vibration or impact by interposing a slip prevention means between a mirror and a leaf spring-like elastic fixing member. Things.
[0012]
Further, the invention described in Japanese Patent Application Laid-Open No. 2001-22009 discloses a method of attaching a vibration damping member to the back surface of a mirror by acrylic bonding or ultraviolet curing bonding, and a method of interposing an elastic member between the mirror and the vibration damping member. This is to reduce the occurrence of vibration.
[0013]
[Problems to be solved by the invention]
However, according to Japanese Patent Application Laid-Open No. 2002-72055, when a plate member having high rigidity is attached to a part of the back surface of the mirror in the longitudinal direction, the plate member is processed into a U-shaped cross-sectional shape in order to increase the rigidity of the plate member. In order to obtain processing accuracy such as flatness of the mirror bonding surface, a high degree of difficulty is required. Further, when the processing accuracy cannot be obtained, the mirror follows the rigidity of the plate-shaped member, and the flatness of the reflection surface is deteriorated.
[0014]
Further, according to JP-A-2001-83633 and JP-A-7-319077, since the vicinity of the center of the mirror is pressed by a separate member, a bow-like warp is generated in the mirror, and the flatness of the reflection surface is deteriorated. there were.
[0015]
Further, according to Japanese Patent Application Laid-Open No. 5-297260, in order to rigidly support the mirror, the size and weight of the supporting member are increased. Further, according to Japanese Patent Application Laid-Open No. H10-206617, it is necessary to increase the width of the mirror in the widthwise direction of the reflecting surface, which leads to an increase in the size of the device. The invention described in Japanese Patent Application Laid-Open No. H11-187224 prevents the mirror from being twisted at the support portions at both ends in the longitudinal direction, and cannot prevent the mirror from vibrating near the center in the longitudinal direction. That is, according to JP-A-5-297260, JP-A-10-206617, and JP-A-11-187224, there is a problem that the device becomes large and complicated.
[0016]
According to Japanese Patent Application Laid-Open No. H11-52494, an elastic member is interposed between the mirror and the pressing member, and the displacement in the mirror longitudinal direction can be prevented. There is a problem that the vibration preventing effect cannot be obtained.
[0017]
Japanese Patent Application Laid-Open No. 2001-22009 discloses that the mirror and the vibration-proof member are bonded, but the mirror bonded with the vibration-proof member is supported at the end of only the mirror. Since only the mirror has a low rigidity portion to be supported, it is difficult to prevent bow-shaped vibration due to insufficient rigidity.
[0018]
Therefore, the present invention prevents distortion of the read image due to the vibration of the mirror on the scanning body without causing problems such as deterioration of the flatness of the mirror reflection surface, complexity of the apparatus, and enlargement of the image, and improves the quality of the image. It is an object of the present invention to provide an obtained image reading device and an image forming device.
[0019]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 is an image reading apparatus that reads an image of a document by exposing and scanning with a scanning body,
A mirror supported on the scanning body,
A vibration isolating member having a length that is superimposed on the back surface of the mirror and that reaches at least both ends in the longitudinal direction of the mirror;
A rigid member fixed on the scanning body and in contact with both end portions of the mirror on the reflection surface side;
An elastic member that supports the mirror and the vibration isolating member by pressing the mirror against at least the same position in the longitudinal direction with respect to the contact position of the rigid member is provided.
[0020]
According to a second aspect of the present invention, there is provided the image reading apparatus according to the first aspect, wherein the mirror and the vibration isolating member are bonded with a double-sided tape.
[0021]
The invention according to claim 3 is the image reading device according to claim 1, wherein the mirror and the vibration isolating member are bonded with an adhesive.
[0022]
According to a fourth aspect of the present invention, in the image reading apparatus according to any one of the first to third aspects, the vibration isolating member is made of a material having a thermal expansion coefficient substantially equal to a thermal expansion coefficient of the mirror. Device.
[0023]
According to a fifth aspect of the present invention, there is provided an image forming apparatus including the image reading device according to any one of the first to fourth aspects.
[0024]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram showing a schematic configuration of an image reading apparatus according to an embodiment of the present invention.
As shown in FIG. 1, the image reading apparatus includes a glass document table 32 on which a document 31 is placed, a first scanning body 33 that slides on a pair of slide tables (not shown), and a first scanning body. A light source 34 for document illumination supported on the body 33, a first mirror 30 supported on the first scanning body 33 and reflecting light reflected from the document in a predetermined direction, and a half of the first scanning body 33 The second scanning body 1 that slides on another pair of slide tables (not shown) at the speed described above, and the second mirror on the second scanning body 1 that sequentially reflects reflected light from the first mirror 30 in a predetermined direction. The optical system includes a second mirror 3, a third mirror 3, a lens 37 that receives reflected light from the third mirror 3 and forms an image, and a CCD 38 that converts the image light formed by the lens 37 into an electric signal. .
[0025]
In this image reading apparatus, a document 31 is placed on a glass document table 32, and a light source 34 on a first scanning body 33 which slides on a pair of slide tables emits light to illuminate the document. The reflected light from the document 31 radiated by the light source 34 passes through the document table 32 and enters the first mirror 30 on the first scanning body 33.
[0026]
The light incident on the first mirror 30 is sequentially reflected by the second mirror 2 and the third mirror on the second scanning body 1 moving at half the speed of the first scanning body 33 and enters the lens 37. The light incident on the lens 37 is imaged on the CCD 38, and the imaged light is converted into an electric signal by the CCD 38 and output.
[0027]
2 is a perspective view schematically showing a second scanning body provided in the image reading apparatus of FIG. 1, FIG. 3 is a front view of a mirror mounting portion provided in the second scanning body of FIG. 2, and FIG. 4 is a second scanning of FIG. It is sectional drawing perpendicular to a mirror surface which shows the mirror attachment part of the 2nd mirror side provided in a body.
As shown in FIG. 2, the second scanning body includes a base member 8 and vertical brackets 9 and 10, which are rigid members fastened to the base member 8.
[0028]
As shown in FIG. 3, a rectangular opening 9a in the present embodiment is formed at an upper portion of the vertical bracket 9 so as to be inclined in the second mirror mounting direction. In the present embodiment, a single contact portion 9b, which is a rigid member with which the reflection surface side of the second mirror 2 contacts, is provided in the opening 9a.
[0029]
In the present embodiment, a rectangular opening 9c is formed in the lower part of the vertical bracket 9 so as to be inclined in the third mirror mounting direction. Like the opening 9a, the opening 9c is provided with one contact portion 9d which is a rigid member with which the reflection surface side of the third mirror comes into contact in the present embodiment.
[0030]
In the present embodiment, a rectangular opening 10a (see FIG. 4) is formed on the upper part of the vertical bracket 10 so as to be inclined in the second mirror mounting direction. In the present embodiment, two contact portions 10b, which are rigid members with which the reflection surface side of the second mirror 2 contacts, are provided in the opening 10a.
[0031]
In the present embodiment, a rectangular opening (in FIG. 3, overlapping with the opening 9 c) is formed at a lower portion of the vertical bracket 10 so as to be inclined in the third mirror mounting direction. Like the opening 9a, the opening 9c is provided with two contact portions 10d, which are rigid members that contact the reflection surface side of the third mirror 3, in the present embodiment. That is, both the second mirror 3 and the third mirror 3 are supported at three points on the reflection surface side.
[0032]
As shown in FIGS. 3 and 4, a vibration isolating member 4 having substantially the same length as the longitudinal direction of the second mirror 2 is provided on the surface opposite to the reflection surface of the second mirror 2, that is, on the back surface side. . Here, the term “substantially the same length” includes the same operation and effect as in the case of the same length, that is, a range in which distortion of a read image due to mirror vibration can be prevented. This anti-vibration member 4 may be longer than the second mirror 2. Then, one end is inserted into the opening 9a of the vertical bracket 9 and the other end is inserted into the opening 10a of the vertical bracket 10 in a state where the second mirror 2 and the vibration isolator 4 overlap each other. A plate-like spring member 6 is inserted between the opening 9a and one end of the vibration-proof member 4, and a plate-like spring member is provided between the opening 10a and the other end of the vibration-proof member 4. 11 is inserted. By the pressurization of the plate-like spring members 6 and 11, the vibration isolating member 4 is urged against the back surface of the second mirror 2 by elastic pressure. The reflection surface side of the second mirror 2 is in contact with the contact portion 9b in the opening 9a and the contact portion 10b in the opening 10a, and the reflection surface is positioned with high precision.
[0033]
As described above, in the image reading apparatus of the present embodiment, the anti-vibration member 4 having at least substantially the same length as the longitudinal direction of the second mirror is pressed and overlapped on the back surface side of the second mirror. The rigidity of the second mirror 2 is uniformly increased in the longitudinal direction because the rigid member is in pressure contact with the rigid member abutting on both ends on the reflection surface side of the second mirror 2 in the longitudinal direction. It is possible to prevent any vibration.
[0034]
In the present embodiment, the vibration isolating member 4 is made of the same optical glass material as the second mirror 2, and thus has the same thermal expansion coefficient as the second mirror.
[0035]
On the second mirror 2 and the third mirror 3 of the second scanning body 1, anti-vibration members 4 and 5 having substantially the same length as the mirror which is a feature of the present invention are superimposed, as shown in FIG. The second mirror 2 and the vibration isolating member 4 are pressed against the vertical brackets 9 and 10 fastened to the base member 8, and are pressed by the plate-like spring members 6 and 7. Pressurized by a plate-shaped spring member.
[0036]
Further, as shown in FIG. 3, the number of support points on the vertical bracket 9 side is one, and the number of support points on the vertical bracket 10 side is two. Thus, one mirror supports a total of three points. .
[0037]
FIG. 4 shows details of a method of supporting the second mirror 2 and the vibration isolating member 4 on the vertical brackets 9 and 10. In a state where the mirror 2 and the vibration isolating member 4 are overlapped with each other, the plate-shaped spring member 6 presses the vertical bracket 9 against the vertical bracket 9. The pressure position is substantially the same in the mirror longitudinal direction. Further, in the present embodiment, the abutting position of the vertical bracket 9 and the pressing position of the plate-shaped spring member 6 are substantially the same in the mirror short direction.
[0038]
When the anti-vibration members 4 and 5 are superimposed on the mirrors 2 and 3, respectively, they may be joined using a double-sided tape.
[0039]
Further, when the vibration isolating members 4 and 5 are respectively superimposed on the mirrors 2 and 3, they may be joined using an adhesive.
[0040]
Further, a material having substantially the same thermal expansion coefficient as the second mirror 2, for example, glass of the same material as the second mirror 2 is used for the vibration isolation member 4. The vibration isolating member 5 is made of a material having substantially the same thermal expansion coefficient as the third mirror 3, for example, glass of the same material as the third mirror 3. The term "substantially the same coefficient of thermal expansion" as used herein means the same operation and effect as when the warpage of the thermal expansion with respect to the change in the operating temperature is the same, that is, the range in which the distortion of the read image due to the vibration of the mirror can be prevented. Shall be considered.
[0041]
In the above embodiment, when the second scanning body 1 scans at the time of reading an image, the anti-vibration members 4 and 5 are in contact with the second mirror 2 and the third mirror 3 over substantially the entire surface in the longitudinal direction, and the support position Are the same in the longitudinal direction, it is possible to effectively prevent the bow-shaped vibrations due to insufficient rigidity of the second mirror 3 and the third mirror 3. In addition, there is an effect that the cost is lower than the method of increasing the thickness of the mirror. Further, the second mirror 2, the third mirror 3, and the vibration isolating members 4, 5 can be respectively recycled.
[0042]
In addition, by attaching the anti-vibration members 4 and 5 to the second mirror 2 and the third mirror 3 with double-sided tape, respectively, there is an effect that the mirror and the anti-vibration member are integrated to attenuate the vibration. Further, at the time of assembling, it is possible to attach the mirror and the vibration isolating member and then assemble them to the vertical bracket, which also has the effect of improving workability.
[0043]
Further, by attaching the anti-vibration members 4 and 5 to the second mirror 2 and the third mirror 3 with an adhesive, respectively, there is an effect that the mirror and the anti-vibration member are integrated to attenuate the vibration. Further, at the time of assembling, it is possible to attach the mirror and the vibration isolating member and then assemble them to the vertical bracket, which also has the effect of improving workability.
[0044]
Also, by attaching the anti-vibration members 4 and 5 to the second mirror 2 and the third mirror 3 with a double-sided tape or an adhesive, the respective mirrors and the anti-vibration member are integrated to attenuate the vibration. In addition to the effect, since the mirror and the vibration isolator have substantially the same coefficient of thermal expansion, the flatness of the mirror reflecting surface is not deteriorated even when a large temperature change occurs. .
[0045]
FIG. 5 is a diagram showing a schematic configuration of a digital copying machine as an example of an image forming apparatus that can use the image reading apparatus of the present invention.
As shown in FIG. 5, this digital copying machine includes a scanner 51 to which the image reading apparatus of the present invention is applied, and converts a reflection image of a document placed on a glass platen of the scanner 51 into an electric signal. Then, the latent image is formed by exposing the photosensitive member surface 53 at the writing section 52. The toner supplied from the developing unit 54 adheres to the exposed portion to form a toner image. The toner image on the photoreceptor surface 53 is transferred to a sheet conveyed from a sheet feeding unit 56 by a transfer unit 57. Thereafter, the transfer paper is heated and pressed by the fixing unit 58, so that the transferred toner image is fixed on the paper and discharged to the outside of the machine.
The present invention is not limited to the above embodiment. That is, various modifications can be made without departing from the gist of the present invention.
[0046]
【The invention's effect】
As described above, according to the present invention, it is possible to prevent the distortion of the read image due to the vibration of the mirror on the scanning body without causing problems such as deterioration of the flatness of the mirror reflecting surface, complexity of the device, and size increase. And a good image can be obtained.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a schematic configuration of an image reading apparatus according to an embodiment of the present invention.
FIG. 2 is a perspective view schematically showing a second scanning body provided in the image reading apparatus of FIG.
FIG. 3 is a front view of a mirror mounting portion provided in a second scanning body of FIG. 2;
FIG. 4 is a cross-sectional view perpendicular to the mirror surface, showing a mirror mounting portion on a second mirror side provided in the second scanning body of FIG. 2;
FIG. 5 is a diagram illustrating a schematic configuration of a digital copying machine as an example of an image forming apparatus that can use the image reading apparatus of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 2nd scanning body 2 2nd mirror 3 3rd mirror 4, 5 Anti-vibration member 6, 7 Plate spring member 8 Base member 9, 10 Vertical bracket 9b, 9d, 10b, 10d Contact part (rigid member)

Claims (5)

In an image reading device that reads an image of a document by exposing and scanning with a scanning body,
A mirror supported on the scanning body,
A vibration isolating member having a length that is superimposed on the back surface of the mirror and that reaches at least both ends in the longitudinal direction of the mirror;
A rigid member fixed on the scanning body and in contact with both end portions of the mirror on the reflection surface side;
An image reading apparatus, comprising: an elastic member that presses at least the same position in the longitudinal direction of the mirror with respect to the contact position of the rigid member to support the mirror and the vibration isolating member. 2. The image reading device according to claim 1, wherein the mirror and the vibration isolating member are bonded with a double-sided tape. 2. The image reading device according to claim 1, wherein the mirror and the vibration isolating member are bonded with an adhesive. The image reading apparatus according to claim 1, wherein the vibration isolating member is made of a material having a coefficient of thermal expansion substantially equal to a coefficient of thermal expansion of the mirror. An image forming apparatus comprising the image reading device according to claim 1.

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