JP2001166396A - Image reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image reader where an image is read by optically scanning an original image and forming image light arriving from the original image into the image on a line image sensor, and where the position of the line image sensor is easily set at the time of assembling the image reader and the transmission of vibration to the line image sensor is restrained, so that image is read excellently all the more. SOLUTION: In this image reader, the image is read by optically scanning the original image and forming the image light arriving from the original image into the image on the line image sensor 52. In the reader, the sensor 52 is mounted and fixed on a sensor supporting member 30, and the member 30 is supported and fixed on a pair of illumination unit slide rails 20 being the component member of the image reader and holds a vibration absorbing body (liquid 41 and weight 42) for absorbing vibration energy exerted on the member 30 and moving with respect to the member 30.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an image reading apparatus.

[0002]

2. Description of the Related Art Generally, in an image reading apparatus mounted on a digital copying machine or the like, an original image is optically scanned, and image light coming from the original image is formed on a line image sensor. And read the image. The scanning of the original image is performed by scanning the original in the main scanning direction and the sub-scanning direction crossing the direction, and the image light arriving by this scanning is formed on the line image sensor by the imaging lens, and the image is read. Can be

In such an image reading apparatus, for example, the vibration of the image forming unit in the copying machine when the image reading apparatus is mounted on the copying machine, such as the vibration of the apparatus main body due to the image reading operation, etc. When transmitted to the image sensor and the line image sensor vibrates, an image reading defect occurs, which causes an image defect when reproducing the read image.

For example, when the line image sensor vibrates in the sub-scanning direction, a line image fluctuates in an image picked up by the line image sensor, a pitch between lines of a line pair pattern changes, and image density unevenness occurs. Image quality may deteriorate. Although depending on the optical magnification in the image reading device and the pixel size of the line image sensor, this deterioration in image quality is evident when the line image sensor vibrates at a relatively low frequency of 100 Hz or less. On the other hand, image noise due to relatively high-frequency vibration is not so noticeable at a level recognized by humans. Therefore, it is particularly required to suppress relatively low frequency vibrations applied to the line image sensor.

In the field of a conventional image reading apparatus, vibration of a line image sensor is generally suppressed as follows. For example, an illumination unit for illuminating a document, a pair of illumination unit slide rails respectively supporting both end portions of the illumination unit and forming sliding surfaces of both end portions of the illumination unit, an imaging lens and a line image sensor (CC)
D) including the lens-CCD unit and the lens-CC
A mounting plate that holds the D unit and bridges the pair of lighting unit slide rails, and scans the document while the lighting unit moves parallel to the document along the lighting unit slide rail, In an image reading apparatus in which image light reflected on a document surface is guided to the lens-CCD unit, and a document image is read by a line image sensor (CCD) via a lens of the lens-CCD unit, the mounting plate is illuminated with the illumination. In fixing to the unit slide rail with a screw or the like, the vibration from the device main body of the line image sensor or the like is suppressed by stopping through a vibration absorbing member made of an elastic material such as rubber. Further, when vibration is transmitted from the device body or the like to the mounting plate, the amplitude is largest at the center of the mounting plate between the pair of lighting unit slide rails,
By connecting the central portion of the mounting plate to a stronger bottom plate of the device housing, for example, the bottom surface of the optical base plate, through a vibration absorbing member made of an elastic body, it is possible to prevent vibration from being transmitted to the line image sensor. Proposed.

FIGS. 5A and 5B are partial side views of an example of a conventional image reading apparatus. In the apparatus shown in FIG. 5A, a lens-CCD unit 5 including an imaging lens 51 'and a line image sensor (CCD) 52' is provided.
0 'is held on a mounting plate 30', and the mounting plate 30 'is bridged over a pair of lighting unit slide rails 20', and a vibration absorbing member formed of an elastic body with screws S 'at both ends thereof. Each of them is fixed via a corresponding 40. Further, in the device shown in FIG.
The central portion of 0 'is coupled to the bottom surface of the optical base plate 61' via a vibration absorbing member 40 'made of an elastic body.

[0007]

However, FIG. 5 (A)
5B, the mounting plate 30 'is fixed to the illumination unit slide rail 20' and the bottom surface of the optical base plate 61 'via the vibration absorbing members 40 and 40'. It is difficult to ensure the accuracy of the height of the lens 51 ', that is, the lens 5'
It is difficult to match the position of the optical axis 1 ', and it is difficult to set the position of the lens-CCD unit 50'. Further, for example, when the mounting plate 30 'is elastically supported by using the vibration absorbing members 40 and 40' made of rubber or the like, although it is effective in reducing the vibration at a relatively high frequency, the vibration is reduced at a relatively low frequency. In this case, it is necessary to take measures such as increasing the number of support points of the mounting plate 30 'and increasing rigidity. Further, in the conventional image reading apparatus shown in FIG. 5B, the mounting plate 30 'and the optical base plate 61' are based on factors such as variations in parts of the mounting plate 30 'or adjustment of the position of the lens 51'. 2
Since the tension applied to the vibration absorbing member 40 'changes due to the change in the distance between the members, the vibration absorbing member 40'
Therefore, there is a problem that the vibration absorbing effect varies, and the vibration absorbing member 40 'cannot cut the target vibration frequency band.

In addition to the above-described configuration, a configuration in which an optical member is elastically movably supported by a member filled with a viscous body in an optical device (for example, JP-A-9-171627, JP-A-8-31162, Patent No. 279131
No. 6) has been proposed. Applying such a configuration to the support mechanism of the line image sensor in the image reading apparatus, that is, elastically supporting the line image sensor with a member filled with a viscous body so as to absorb vibration in the sub-scanning direction can be considered. In this case, the vibration at a relatively low frequency can be attenuated, but after all, the line image sensor is elastically supported so as to be movable in the sub-scanning direction, so that the above-described image deterioration, that is, the fluctuation of the line image, Image deterioration such as pitch fluctuation of line pair patterns and uneven image density is likely to occur.

Accordingly, the present invention relates to an image reading apparatus which optically scans a document image and forms an image light coming from the document image on a line image sensor to read the image. It is an object of the present invention to provide an image reading apparatus which can easily set a position at the time of assembling or the like and suppresses transmission of vibration to a line image sensor and can read an image accordingly.

[0010]

According to the present invention, there is provided an image reading apparatus for optically scanning a document image, forming an image light coming from the document image on a line image sensor, and reading the image. Wherein the line image sensor is mounted and fixed to a sensor support member, and the sensor support member is supported and fixed to an image reading device component member and absorbs vibration energy applied to the sensor support member. Provided is an image reading device, wherein a movable vibration absorber is held on a support member.

In the image reading apparatus according to the present invention, an original image is optically scanned, and image light coming from the original image is focused on a line image sensor to read the image. This image reading device can be mounted on, for example, a digital copying machine. In the image reading device of the present invention, the line image sensor is mounted and fixed on a sensor support member,
The sensor support member is supported and fixed to an image reading device constituent member. The sensor support member holds a vibration absorber movable with respect to the sensor support member for absorbing vibration energy applied to the sensor support member.

According to the image reading apparatus of the present invention,
The line image sensor is mounted and fixed to the sensor support member without using a vibration absorbing member employed in a conventional image reading device as shown in FIG. 5, and this sensor support member is used as a component of the image reading device. Since the line image sensor is supported and fixed, it is easy to secure the position accuracy of the line image sensor, and the position setting of the line image sensor at the time of assembling the image reading device is easy.

In addition, for example, when an image reading device is mounted on a copying machine, for example, when the image reading device is installed in a copying machine, the vibration of the image forming unit in the copying machine, etc., is caused by the image reading device. Is transmitted to the sensor support member via the component member, the sensor support member holds the vibration absorber that is movable with respect to the sensor support member. The vibration energy is converted into the vibration energy by the shaking of the vibration absorber (converted into the vibration energy of the vibration absorber while being offset by the inertial force of the vibration absorber). The vibration of the sensor is suppressed.

As described above, according to the image reading apparatus of the present invention, it is easy to set the position of the line image sensor at the time of assembling the image reading apparatus, and to suppress the transmission of vibration to the line image sensor, thereby improving the image quality. Can be read. The following cases can be exemplified as aspects of the image reading apparatus according to the present invention. That is, (a) the sensor supporting member includes a hollow box, and the vibration absorber is housed in the hollow box, and is displaceable with respect to the box by vibration energy applied to the sensor supporting member. Case.

In this case, examples of the vibration absorber include a fluid (a liquid such as water, a granular material such as beads, or a powder) contained in the hollow box. In addition, a weight that is included in the hollow box body and that can move independently while being in contact with the hollow box body may be used as the vibration absorber. According to this image reading device, the vibration energy applied to the sensor support member causes the vibration absorber, for example, a fluid such as a liquid, a granular material, or a powder, or a weight that fluctuates, to oscillate. As a result, the vibration is absorbed by the vibration absorber, and the vibration of the line image sensor is suppressed. (B) The case where the vibration absorber is a weight supported by the sensor support member via an elastic member.

In this case, examples of the elastic member include a rubber member, a spring such as a plate spring and a wound spring, a damper, and a combination of two or more thereof. According to this image reading device, the vibration energy applied to the sensor support member is caused to oscillate by the weight via the elastic member, for example, a rubber member, a spring such as a plate spring or a coil spring, a damper, or a combination of two or more thereof. By being crushed, the weight is absorbed by the weight, and the vibration of the line image sensor is suppressed.

In any case, the image reading apparatus according to the present invention includes an illumination unit for illuminating a document, and a pair of illumination unit slide rails respectively supporting both ends of the illumination unit and forming sliding surfaces at both ends of the unit. May be provided. In such an image reading device,
The sensor support member may be supported and fixed to the image reading device constituent member, wherein the sensor support member is bridged and fixed to the pair of illumination unit slide rails, and the sensor support member is a bottom plate of the device housing. For example, a configuration in which the optical base plate is supported and fixed to the bottom surface of the optical base plate can be exemplified.

In the case where the sensor support member is bridged and fixed to the pair of lighting unit slide rails,
The sensor support member may hold the vibration absorber at any position such as at a substantially central portion or both end portions between the pair of lighting unit slide rails. When vibration is transmitted to the sensor support member from above, the amplitude is largest at the center of the sensor support member between the pair of lighting unit slide rails, so that the vibration absorber absorbs the vibration energy of the sensor support member. It is advantageous above.

In any case, in the image reading apparatus according to the present invention, the position where the sensor support member holds the vibration absorber may be, for example, from the viewpoint of suppressing transmission of vibration to the line image sensor. ,
It is preferable that the line image sensor is mounted and fixed at substantially the same position as the line image sensor, in other words, at the substantially same position as the holding position of the vibration absorber on the sensor support member. However, it is not limited thereto.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an exploded perspective view showing a schematic configuration of a part of an image reading apparatus according to an embodiment of the present invention. The image reading apparatus includes a document table (not shown), and an illumination unit 10 for illuminating a document on the document table is disposed below the document table.
Further, a pair of illumination unit slide rails 20 are provided at both ends 11 of the illumination unit 10, and the sensor support member 30 and the lens-CCD unit 50 are disposed between the pair of illumination unit slide rails 20. I have.
Further below the optical base plate 61 is provided. The image reading device is mounted on a digital copying machine here.

The illumination unit 10 is driven in a sub-scanning direction (Y direction in the drawing) in parallel with the document table along the illumination unit slide rail 20 by a driving device (not shown). Thus, the original can be scanned in the sub-scanning direction Y, and the image light reflected on the original surface can be guided to the lens-CCD unit 50. The pair of lighting unit slide rails 20 and the optical base plate 61 are respectively connected to the device housing 60.
(Not shown in FIG. 1, see FIG. 2).

A pair of lighting unit slide rails 20
Support both ends 11 of the lighting unit 10 and constitute a sliding surface 21 of both ends 11 of the unit. The sensor support member 30 includes a hollow box 31 located at a substantially central portion between the pair of rails 20. The hollow box 31 is fixed to the sensor support member 30 with screws S1. The hollow box 31 contains a vibration absorber.

As the vibration absorber, a liquid such as water,
In addition to particles such as beads or a fluid such as powder, a weight can be employed. FIG. 2 is a cross-sectional view along the main scanning direction (X direction in the figure) of the hollow box 31 and the vibration absorber accommodated therein, and FIG. 2A shows an example of the vibration absorber in the hollow box 31. 2B shows a state in which a liquid (here, water) 41 is stored, and FIG. 2B shows a state in which a weight 42 which is another example of the vibration absorber is stored in the hollow box 31.

As shown in FIG. 2A, a liquid 41 is contained in the hollow box 31 as a vibration absorber as described above. The liquid 41 can be displaced with respect to the box 31 by vibration energy applied to the sensor support member 30.
Therefore, the liquid 41 is shaken by the vibration energy applied to the sensor support member 30, the vibration energy of the sensor support member 30 is converted into the vibration energy of the liquid 41 in the box 31, and the vibration energy of the sensor support member 30 is reduced. Consumed. As a result, the liquid 41 is supplied to the sensor support member 30.
Can absorb vibration energy applied to

As shown in FIG. 2B, the hollow box 31 contains a weight 42 as a vibration absorber as described above. The weight 42 can be displaced with respect to the box 31 by vibration energy applied to the sensor support member 30.
That is, the weight 42 is smaller in size than the hollow space of the hollow box 31, and has a contact surface 42 a with the inner bottom surface 31 a of the hollow box 31. Therefore, the weight 42 is not restrained in the hollow box 31 and the sensor support member 30
The weight 42 is shaken in the box body 31 by the vibration energy applied to the sensor body 30, and the vibration energy applied to the sensor support member 30 at this time is changed to the vibration energy of the weight 42, whereby the vibration applied to the sensor support member 30 by the weight 42 Can absorb energy.

As shown in FIG. 1, the sensor support member 30
Are supported and fixed to the image reading device constituent members.
That is, in this case, a bridge is provided between the pair of lighting unit slide rails 20 and fixed by the screw S2. The vibration absorber accommodated in the hollow box 31 is held at a substantially central portion between the pair of lighting unit slide rails 20.

The lens-CCD unit 50 is mounted on the sensor support member 30 at the vibration absorber holding position.
It is installed in. The lens-CCD unit 50 is an example of an imaging lens 51 and a line image sensor C
The sensor support member 30 includes a screw S3
Has been fixed by. The imaging lens 51 can form image light from the illumination unit 10 on the CCD 52. The CCD 52 is provided on a CCD substrate 53, and is fixed to the unit 50 via the CCD substrate 53. The CCD 52 reads the image light from the imaging lens 51 in the main scanning direction X and can photoelectrically convert the image light into an electric signal corresponding to the light intensity.

According to the image reading apparatus described above,
When reading the document image, the illumination unit 10 scans the document while moving parallel to the document along the illumination unit slide rail 20. The image light reflected on the document surface
The lens-CCD unit 50 guides the image forming lens 51
Is read as an original image by the CCD 52 via the.

According to the image reading apparatus shown in FIG. 1, the line image sensor 52 does not pass through the vibration absorbing member employed in the conventional image reading apparatus shown in FIG.
Since the sensor support member 30 is mounted and fixed on the sensor support member 30 and is supported and fixed on an image reading device constituent member (here, a pair of illumination unit slide rails 20), a line image sensor (here, the CCD 5) is provided.
2) It is easy to secure the position accuracy, and accordingly, the position setting at the time of assembling the image reading device of the CCD 52 is easy.

Also, the vibration of the apparatus main body due to the image reading operation and the like, for example, the vibration due to the operation of the image forming unit in the copying machine, and the like are caused by the constituent members of the image reading apparatus (here, a pair of illumination unit slide rails 20 and the like). 2), the sensor support member 30 is movable with respect to the sensor support member 30 (the liquid 41 in the example of FIG. In the example of ()), since the weight 42) is held, the vibration energy applied to the sensor support member 30 is changed to the vibration energy of the vibration absorbers 41 and 42 by the vibration of the vibration absorbers 41 and 42, and The vibration energy of the support member 30 is consumed. Thereby, the vibration absorbers 41 and 42 can absorb the vibration energy applied to the sensor support member 30, and thus, the transmission of the vibration to the CCD 52 can be suppressed.

As described above, according to the image reading apparatus shown in FIG. 1, it is easy to set the position of the CCD 52 at the time of assembling the image reading apparatus or the like, and the vibration can be suppressed from being transmitted to the CCD 52, so that the image can be read better. FIG. 3 is a side view of an image reading apparatus according to another embodiment of the present invention as viewed from a lighting unit side. FIG. 4 is a side view of an image reading apparatus according to still another embodiment of the present invention as viewed from a lighting unit side. Note that FIG.
In FIG. 4 and FIG. 4, the illumination unit is not shown.

In the image reading apparatus shown in FIGS. 3 and 4, both the sensor supporting member 30 and the vibration absorbers 41 and 42 are replaced with the sensor supporting member 30a, the elastic member 70 and the vibration absorbing element in the image reading apparatus shown in FIG. A body 43 is provided. The other points are the same as those of the apparatus of FIG. 1, and the parts having the same configuration and operation are denoted by the same reference numerals.
Hereinafter, the image reading apparatus shown in FIGS. 3 and 4 will be described focusing on differences from the apparatus shown in FIG.

In the image reading apparatus shown in FIGS. 3 and 4, the weight 43 is supported by the sensor supporting member 30a via the elastic member 70 as a vibration absorber. In the image reading device shown in FIG. 3, the elastic member 70 includes a wrap spring 70a and a damper 70b. The coil spring 70a and the damper 70b each have a sensor support member 30a.
And the other end is connected to the weight 43.
Therefore, the weight 43 is shaken by the vibration energy applied to the sensor support member 30a via the coil spring 70a and the damper 70b, and the vibration energy of the sensor support member 30a is changed to the vibration energy of the weight 43, and the vibration of the sensor support member 30a is changed. Energy is consumed. Thereby, the weight 43 can absorb the vibration energy applied to the sensor support member 30a. Here, as the elastic member 70, a coil spring 70a and a damper 70b are used in combination, but only one of them may be used. Further, as the spring member, a leaf spring or the like may be used in addition to the wound spring.

In the image reading apparatus shown in FIG. 4, the elastic member 70 comprises a rubber member 70c. The rubber member 70c is connected to the sensor support member 30a on the one hand, and is connected to the weight 43 on the other hand. Therefore, the weight 43 is generated by the vibration energy applied to the sensor support member 30a.
Is shaken via the rubber member 70c, the vibration energy of the sensor support member 30a is changed to the vibration energy of the weight 43, and the vibration energy of the sensor support member 30a is consumed. Thereby, the weight 43 is connected to the sensor support member 30.
Vibration energy applied to a can be absorbed.

In the image reading apparatus shown in FIGS. 3 and 4, the sensor support member 30a is bridged between the pair of illumination unit slide rails 20 and fixed by screws S2. The vibration absorber 43 is held at a substantially central portion between the pair of lighting unit slide rails 20 via an elastic member 70. The lens-CCD unit 50
It is mounted on the sensor support member 30a and is fixed by screws S3.

According to the image reading apparatus shown in FIGS. 3 and 4, in the apparatus shown in FIG. 3, the weight 43 is shaken by the vibration energy applied to the sensor support member 30a via the wrap spring 70a and the damper 70b. In the apparatus shown in FIG. 4, the weight 43 is shaken by the vibration energy applied to the sensor support member 30a via the rubber member 70c, so that the weight 43 can absorb the vibration energy applied to the sensor support member 30a. Has the same advantages as the image reading apparatus shown in FIG.

In the image reading apparatus shown in FIGS. 1, 3 and 4, the sensor supporting members 30 and 30a have a lens at a substantially central portion between the pair of illumination unit slide rails 20.
The vibration absorbers 41 and 4 corresponding to the CCD unit 50
Although 2 and 43 are held, the invention is not limited to this, and may be held at both ends between the slide rails 20, for example. The sensor support members 30 and 30a are bridged and fixed to the pair of lighting unit slide rails 20. The sensor support members 30 and 30a are supported and fixed to the bottom plate of the device housing 60, here, the bottom surface of the optical base plate 61. May be.

In the image reading apparatus shown in FIG. 1, the line image sensor 52 may be directly fixed to the hollow box 31. When the sensor support member 30 is supported and fixed to the bottom surface of the optical base plate 61, the lens-CCD unit 50 may be supported and fixed to the bottom surface of the optical base plate 61 via the hollow box 31.

[0039]

As described above, according to the present invention, there is provided an image reading apparatus which optically scans a document image, forms an image light coming from the document image on a line image sensor, and reads the image. It is possible to provide an image reading apparatus that can easily set the position of the line image sensor at the time of assembling the image reading apparatus or the like, and that can suppress the transmission of vibration to the line image sensor and read an image accordingly.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view illustrating a schematic configuration of a part of an image reading apparatus according to an embodiment of the invention.

FIG. 2 is a cross-sectional view along a main scanning direction of a hollow box body and a vibration absorber accommodated therein, and FIG. 2A shows a liquid (here, water) which is an example of the vibration absorber in the hollow box body. FIG. 7B shows a state in which a weight, which is another example of the vibration absorber, is housed in the hollow box body.

FIG. 3 is a side view of an image reading apparatus according to another embodiment of the present invention as viewed from a lighting unit side.

FIG. 4 is a side view of an image reading apparatus according to still another embodiment of the present invention as viewed from a lighting unit side.

FIG. 5A is a side view of a part of an example of a conventional image reading device, and FIG. 5B is a side view of a part of another example of a conventional image reading device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Illumination unit 11 Both ends 20 and 20 'of illumination unit 10 A pair of illumination unit slide rails 21 Slide surface 30 Sensor support member 30a Sensor support member 30' Mounting plate 31 Hollow box body 40, 40 'Vibration absorption member 41 Liquid 42, 43 Weight 50, 50 'Lens-CCD unit 60 Device housing 51, 51' Imaging lens 52, 52 'CCD 60 Device housing 61, 61' Optical base plate 70 Elastic member 70a Winding spring 70b Damper 70c Rubber member S ', S1, S2, S3 Screw

Claims (8)

[Claims] 1. An image reading apparatus for optically scanning a document image, forming an image light coming from the document image on a line image sensor, and reading the image, wherein the line image sensor is mounted and fixed to a sensor support member. Has been
The sensor support member is supported and fixed to an image reading device component member and holds a movable vibration absorber with respect to the sensor support member for absorbing vibration energy applied to the sensor support member. Image reading device. 2. The sensor supporting member includes a hollow box, and the vibration absorber is housed in the hollow box and is displaceable with respect to the box by vibration energy applied to the sensor supporting member. The image reading device according to claim 1. 3. The image reading apparatus according to claim 2, wherein said vibration absorber is a fluid contained in said hollow box. 4. The image reading apparatus according to claim 2, wherein said vibration absorber is a weight which is included in said hollow box and is movable independently while being in contact with said hollow box. 5. The image reading apparatus according to claim 1, wherein said vibration absorber is a weight supported by said sensor support member via an elastic member. 6. An illumination unit for illuminating a document, and a pair of illumination unit slide rails respectively supporting both ends of the illumination unit and forming sliding surfaces of both ends of the unit, wherein the sensor support member is provided. The image reading device according to claim 1, wherein the image reading device is bridged and fixed to the pair of lighting unit slide rails. 7. The image reading apparatus according to claim 6, wherein said sensor support member holds said vibration absorber at a substantially central portion between said pair of illumination unit slide rails. 8. The image reading apparatus according to claim 1, wherein said line image sensor is mounted and fixed at substantially the same position as the holding position of said vibration absorber on said sensor support member.