JP3387396B2 - Image reading device - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a copying machine having an image sensor which is driven by a high frequency pulse signal, a facsimile, relates to an image reading equipment such as a scanner, in particular, thereby reducing the electromagnetic noise leakage It relates to an image reading equipment.

[0002]

2. Description of the Related Art FIG. 7 shows a conventional image reading apparatus. As shown in FIG. 7 (a), this image reading apparatus has a box-shaped apparatus main body 2 made of metal, which has a transparent document placing table 1 on the upper portion thereof. Light source 3 generated
A reflector 4 for irradiating the original P on the original table 1 with the light generated by the light source 3, and the mirror 5 for the light scattered by the original P.
A, 5B, 5C and the image sensor 7 for forming an image via the lens 6 are arranged. The image sensor 7 is, for example,
A solid-state image sensor such as a one-dimensional CCD is used, and is driven by applying a high-frequency clock pulse signal in order to sequentially read information on sensor pixels arranged in one dimension.

The image sensor 7 is provided on a first circuit board 8A for driving the image sensor 7, and the first circuit board 8A is provided.
Is attached to the apparatus main body 2 by a support member (not shown). On the bottom portion 2a of the device body 2, the second circuit board 8 for subjecting the signal from the first circuit board 8A to predetermined processing is provided.
B is attached by a fixture 9 having conductivity, the first circuit board 8A and the second circuit board 8B are arranged so as to be orthogonal to each other, and both are connected by a connection cable 10.

In the image reading apparatus having the above structure, the light source 3, the reflector 4 and the mirrors 5A, 5B and 5C are shown in FIG.
(a) A two-dimensional image can be read from the manuscript P by moving in the scanning direction X as shown by the middle broken line. In addition, the drive circuit that drives the image sensor 7 and the processing circuit that processes the signal obtained from the image sensor 7 are respectively the first
Since the circuit board 8A and the second circuit board 8B are separately mounted, the device can be downsized, the optical system can be simplified, and the position of the image sensor 7 can be easily adjusted.

FIG. 7 (b) shows a state of occurrence of electromagnetic noise in the image reading apparatus shown in FIG. 7 (a). It is known that in an image reading apparatus including an image sensor, the image sensor is driven by a high-frequency pulse signal, so that unnecessary electromagnetic noise is generated from a circuit around the image sensor.
In the case of the structure shown in FIG. 7A, since the first circuit board 8A is attached separately from the metal device body 2, the structure shown in FIG.
As shown in (b), the noise current on the first circuit board 8A and the connection cable 10 is coupled to the surrounding metal device main body 2 and the second circuit board 8B through the space to generate the noise current loop 11A. , 11B, and the standing wave current 12 generated on the noise current loops 11A, 11B and the connection cable 10 serves as a main noise radiation source.

An example of a conventional image reading apparatus that has been made to cope with such electromagnetic noise is, for example, Japanese Patent Laid-Open No. 4-2.
82, 955, JP-A-8-32762, and JP-A-9-149218.

The image reading apparatus disclosed in Japanese Unexamined Patent Publication No. 4-282955 is a transparent original placing table coated with a transparent conductive material. As a result, it is possible to prevent leakage of unnecessary radio waves generated from the traveling body including the image sensor, the drive circuit, the sensor output processing circuit, and the like.

The image reading apparatus disclosed in Japanese Patent Application Laid-Open No. 8-32762 covers an optical system including an image sensor with a shield case, and the shield case is provided with an opening for securing an optical path of the optical system. A cylindrical component is projected in the opening, the width of the opening is set to 1/2 or less of the wavelength of the highest frequency required to block noise, and the length of the tubular component is set to 1 of the wavelength of the highest frequency required to block noise. / 8 or more. As a result, the tubular component acts as a kind of high-pass filter, and it is possible to prevent radio waves having a frequency equal to or lower than the required maximum frequency for blocking high-frequency electromagnetic noise from leaking from the opening.

The image reading apparatus disclosed in Japanese Patent Application Laid-Open No. 9-149218 covers an optical system including an image sensor with a shield case, and the shield case is provided with an opening for securing an optical path of the optical system. An electromagnetic radiation screen is provided in the opening. This can reduce or prevent leakage of electromagnetic radiation through the opening.

[0010]

However, Japanese Unexamined Patent Publication (Kokai) No. 4-2.
According to the conventional image reading apparatus disclosed in Japanese Patent No. 82955, in order to read an image from the original on the original placing table,
Since it is essential that the document placing table has transparency and it is difficult to completely shield the document placing table, it is impossible to prevent electromagnetic wave noise from leaking. In addition, JP-A-8-3276
According to the conventional image reading apparatus disclosed in Japanese Patent Application Laid-Open No. 2 and Japanese Patent Application Laid-Open No. 9-149218, it is essential to secure the optical path of the optical system even if the optical system including the image sensor is covered with the shield case. Since it is difficult to completely shield the electromagnetic noise, it cannot be prevented.

Accordingly, the present invention is to provide an image reading equipment which thereby reducing the electromagnetic noise leakage.

[0012]

In order to achieve the above-mentioned object, the present invention provides an image light obtained by optical scanning.
Input through the academic system, convert the image light into image signal
An image sensor for outputting and mounting the image sensor
By driving the image sensor with a high-frequency pulse signal,
Circuit for processing the image signal output from the image sensor
A circuit board and a circuit board, and the image sensor
Circuit board according to the driving of the image signal and the processing of the image signal
A mirror image current that cancels the noise current generated along the
A first circuit board having a metal surface, the circuit board having the image sensor mounted thereon, and a drive circuit for driving the image sensor with the high-frequency pulse signal; and the image signal from the image sensor. A second circuit board that is subjected to a predetermined process, and a connecting portion that connects the first circuit board and the second circuit board, and the metal surface has a single surface. The image reading device is characterized in that the circuit board and the second circuit board are closely arranged on the same plane parallel to the single surface.

To achieve the above object, the present invention provides an image sensor for inputting image light obtained by optical scanning through an optical system, converting the image light into an image signal and outputting the image signal. with mounting the image sensor, drives the image sensor with a high frequency pulse signal, and a circuit board for processing the image signal output from the image sensor, the circuit
The image sensor is placed close to the substrate and
Generated along the circuit board as the image signal is processed
Equipped with a metal surface through which a mirror image current that cancels the noise current flows,
The circuit board is mounted with the image sensor,
First circuit having a drive circuit for driving the image sensor
The substrate and the image signal from the image sensor are subjected to predetermined processing.
A second circuit board for processing, the first circuit board, and
The metal surface is provided with a connecting portion for connecting to a second circuit board.
Is a first surface orthogonal to the optical scanning direction, and
A second surface parallel to the direction of optical scanning,
A circuit board is disposed adjacent to the first surface and has a second surface.
The circuit board is arranged close to the second surface.
An image reading device is provided.

[0014]

1 shows an image reading apparatus according to a first embodiment of the present invention. As shown in FIG. 1 (a), this image reading apparatus has a box-shaped apparatus main body 2 made of metal and having a transparent original placing table 1 on the upper portion thereof. A light source 3 which is generated, and a reflector 4 which irradiates the document P on the document mounting table 1 with the light generated by the light source 3.
Mirrors 5A, 5 for guiding the light scattered by the document P to the lens 6
B and 5C, a mirror 5D that reflects light passing through the lens 6 downward by 90 ° in a direction orthogonal to the scanning direction X, and an image sensor 7 that forms an image of the light reflected by the mirror 5D. . The image sensor 7 uses, for example, a solid-state image sensor such as a one-dimensional CCD, and is driven by applying a high-frequency clock pulse signal in order to sequentially read information on sensor pixels arranged one-dimensionally.

The mirror 5D has an optical path of 90 degrees or 9 degrees.
Anything can be used as long as it refracts at an angle near 0 degree, but a plane mirror or a plane prism is typically used. Furthermore, it is also possible to use a non-planar mirror or a non-planar prism in which the mirror 5D has a part or all of the condensing action of the lens 6. Further, the insertion position of the mirror 5D is best between the image sensor 7 and the lens 6 as shown in FIG. 1, but may be in front of the lens 6. That is,
The lens 6 may be arranged between the mirror 5D and the image sensor 7. The mirrors 5A, 5B and 5C are movable, whereas the mirror 5D is fixed at least during use.

An image sensor 7 is provided on the bottom 2a of the apparatus main body 2.
The first circuit board 8A for driving the image sensor 7 and the second circuit board 8B for subjecting a signal from the first circuit board 8A to a predetermined process are electrically conductive by the fixture 9 It is installed. First circuit board 8A
And the second circuit board 8B are arranged in parallel with the inner surface of the bottom portion 2a and on the same plane, and both are arranged in the flexible cable 1
Connected by 1. On the first circuit board 8A,
A drive circuit for driving the image sensor 7 is mounted, and an amplifier circuit for amplifying a signal from the image sensor 7 and an A / D converter for the output signal of the amplifier circuit are mounted on the second circuit board 8B.
A D converter and a correction circuit for correcting the output signal of the AD converter are mounted. In addition to the drive circuit, the amplifier circuit and the A circuit may be provided on the first circuit board 8A depending on the application.
A D converter may be mounted and the correction circuit may be mounted on the second circuit board 8B.

The fixture 9 includes a bottom portion 2a of the apparatus main body 2 and a first portion 2a.
And a predetermined distance G between the second circuit board 8A and 8B
The smaller the distance G, the greater the effect of suppressing the radiation noise, and when the distance is halved, the radiation reduction of 6 dB is expected. Therefore, the distance G is preferably 20 mm or less, more preferably 5 mm or less (0
(including mm), the effect of suppressing radiation noise can be increased. The fixture 9 may be columnar or sheet-shaped. It is preferable to electrically connect the grounds of the circuit boards 8A and 8B to the metal device main body 2 by using the metal fixture 9. As a result, the circuit board 8
It is possible to stabilize the potentials of the ground surfaces of A and 8B. The fixture 9 electrically insulates the grounds of the circuit boards 8A and 8B from the bottom 2a of the apparatus body 2 by a method such as partially or entirely insulating, or separating the connection pattern. Alternatively, a method of connecting via a specific circuit element such as a resistor or a capacitor can be adopted. Accordingly, when the ground noise of the circuit boards 8A and 8B is large, it is possible to prevent the noise from propagating to the bottom portion 2a of the apparatus body 2 and being radiated.

Further, the fixture 9 of the first circuit board 8A is
It has a mechanism that allows three-dimensional minute movement of the first circuit board 8A so that the optical position of the image sensor 7 can be adjusted. Further, the flexible cable 11 also has the flexibility to accommodate the position adjustment of the first circuit board 8A.
In addition, without adjusting the position of the first circuit board 8A, the mirror 5
By adjusting the positions of the optical elements such as D and the lens 6, some or all of the adjusting elements may be substituted.

Next, the effect of the above structure will be described with reference to FIG.

FIG. 1B shows a state of generation of electromagnetic noise in this image reading apparatus. (A) The first circuit board 8 as well as the second circuit board 8B
Since the bottom portion 2a of the metallic device body 2 is provided close to A and the flexible cable 11, the mirror image current 13 corresponding to the noise current 12 flowing through the circuit boards 8A and 8B is provided as shown in FIG. Is the bottom 2 of the device body 2.
The noise current 12 cancels out by flowing on the inner surface of a, and the radiation noise is reduced. (B) Since the first circuit board 8A and the second circuit board 8B are no longer orthogonal to each other due to the action of the mirror 5D, the boards 8A, 8
Between B, the noise current loop 11 as shown in Fig. 7 (b)
Since A and 11B are not generated, the volume of the space in which the noise current flows is significantly reduced as compared with the conventional case, and thus noise emission is reduced. (C) Since the first circuit board 8A, the second circuit board 8B, and the flexible cable 11 are integrated circuit boards, the length of the flexible cable 11 is shorter than that of the conventional one.
In addition, it becomes difficult for the ground connection failure and the impedance discontinuity, which have conventionally occurred in the connector of the connection cable, to occur. Therefore, it is possible to suppress the generation of standing waves and the generation of radiation noise due to these. The electromagnetic noises leaking from the device body 2 can be significantly reduced by the above (a), (b), and (c). (D) Since the insertion position of the mirror 5D is between the image sensor 7 and the lens 6, the device can be made thin.

FIG. 2 shows an image reading apparatus according to the second embodiment of the present invention. This image reading apparatus is one in which the first circuit board 8A, the second circuit board 8B and the flexible cable 11 of the first embodiment shown in FIG. 1 are formed as an integrated circuit board 18, and the others are the same. The configuration is similar to that of the first embodiment. The position of the image sensor 7 is adjusted by moving the entire circuit board 18. The integrated circuit board 18 means a circuit board which cannot be separated nondestructively,
In addition to an integrated board consisting of the same structure, circuit boards with partially different numbers of layers and materials, rigid flexible circuit boards with mixed rigid and flexible parts, and bonding or soldering multiple separated circuit parts It includes a circuit board integrated by attachment.

According to the second embodiment, although the size of the board 18 to be moved at the time of adjusting the optical position of the image sensor 7 becomes large, the connecting portion for connecting the circuit boards can be completely removed, so that the connecting portion can be completely removed. It is possible to further reduce the radiation noise due to

FIG. 3 shows an image reading apparatus according to the third embodiment of the present invention. This image reading device uses a connection cable 10 instead of the flexible cable 11 of the first embodiment shown in FIG. 1, and is otherwise configured similarly to the first embodiment.

According to the third embodiment, since the connecting portion between the circuit boards 8A and 8B is longer than that in the first embodiment, the effect of reducing the radiation noise from the connecting portion is reduced, but the manufacturing process is reduced. The cost can be reduced. Further, although this device largely reduces the noise emission from the circuit system from the beginning, the noise emission may be further reduced by using a shield together. Even when a shield is used, the noise emission of the circuit system is originally small due to this configuration, so that an inexpensive shield system is sufficient and other noise reducing components can be eliminated.

FIG. 4 shows an image reading apparatus according to the fourth embodiment of the present invention. This image reading apparatus includes a mirror 5D, a lens 6, a first circuit board 8A, and a mirror 5D according to the first embodiment.
The second circuit board 8B, the fixture 9 and the flexible cable 11 are provided in a shield case 14 having a light transmitting portion 14a.
Are covered with the other parts, and the other parts have the same structure as the first embodiment.

According to the fourth embodiment, the leakage of electromagnetic noise can be further reduced.

FIG. 5 shows an image reading apparatus according to the fifth embodiment of the present invention. In this image reading apparatus, as shown in FIG. 5 (a), a partition section 2b having a light transmitting section 2b is provided in the apparatus body 2, and an image sensor 7 is provided between the bottom section 2a and the partition section 2c. Circuit board 8A and second circuit board 8B are arranged, and first and second circuit boards 8A, 8
B is attached to the partition portion 2c by a fixture 9, and the other configurations are similar to those of the first embodiment.

According to this fifth embodiment, FIG.
As shown in, the mirror image current 13 corresponding to the noise current 12 flowing through the circuit boards 8A and 8B flows on the lower surface of the partition portion 2c and cancels the noise current 12, so that the radiation noise is reduced. Further, since the optical system and the circuit system are separated via the partition 2b, the mirror 5D and the lens 6 can be easily fixed. Moreover, since the structure is simpler than that of the shield case 14 as shown in FIG. 4, the manufacturing cost is low, and since the area of the light transmitting portion 2b can be made small, radiation leakage is reduced, and further, the device can be made thin. And so on.

FIG. 6 shows an image reading apparatus according to the sixth embodiment of the present invention. As shown in FIG. 6 (a), this image reading apparatus does not include the mirror 5D, and the first circuit board 8A is replaced with the second circuit board 8B, as in the conventional configuration shown in FIG. 7 (a). It is arranged in a direction orthogonal to each other, a vertical partition 2d is provided in the device body 2 in the vicinity of the first circuit board 8A, and the first circuit board 8A is attached to the vertical partition 2d by a fixture 9. Is configured similarly to the third embodiment.

According to this sixth embodiment, FIG. 6 (b)
As shown in FIG. 5, the mirror image current 13 corresponding to the noise current 12 flowing through the circuit boards 8A and 8B is generated by the vertical partition 2d.
Since the noise current 12 is canceled by flowing on the surface on the right side of and the inner surface of the bottom portion 2a, the radiation noise is reduced.
Further, since the mirror 5D is unnecessary, the cost can be reduced.

The present invention is not limited to the above embodiment, and various modifications can be made. For example, a metal surface
In the above embodiment, the flat surface is described, but it may be a surface having irregularities, or a non-metallic member may be partially provided with a linear or planar conductor on the surface or inside thereof.

[0032]

As described above, according to the present invention, the first circuit board having the drive circuit for driving the image sensor and the image circuit are provided.
A metal surface is disposed in proximity to a second circuit board that performs a predetermined process on the image signal from the image sensor, and a mirror image current that cancels a noise current generated along the first and second circuit boards is passed through the metal surface. and so, since to prevent the occurrence of radiation noise from the original, it is possible to provide a small image reading equipment of leakage conventionally electromagnetic noise.

[Brief description of drawings]

FIG. 1A is a configuration diagram of an image reading apparatus according to a first embodiment of the present invention, and FIG. 1B is a diagram showing a generation state of electromagnetic noise.

FIG. 2 is a configuration diagram of an image reading apparatus according to a second embodiment of the present invention.

FIG. 3 is a configuration diagram of an image reading apparatus according to a third embodiment of the present invention.

FIG. 4 is a configuration diagram of an image reading apparatus according to a fourth embodiment of the present invention.

FIG. 5A is a configuration diagram of an image reading apparatus according to a fifth embodiment of the present invention, and FIG. 5B is a diagram showing a generation state of electromagnetic noise.

FIG. 6A is a configuration diagram of an image reading apparatus according to a sixth embodiment of the present invention, and FIG. 6B is a diagram showing a generation state of electromagnetic noise.

FIG. 7A is a configuration diagram of a conventional image reading apparatus, and FIG. 7B is a diagram showing a generation state of electromagnetic noise.

[Explanation of symbols]

1 Document placing table 2 device body 2a bottom 2b Light transmission part 2c partition 2d vertical partition 3 light sources 4 reflector 5A, 5B, 5C, 5D Mirror 6 lenses 7 Image sensor 8A First circuit board 8B Second circuit board 9 Fixture 10 connection cable 11 Flexible cable 14 Shield case 14a Light transmission part 18 circuit board G distance P manuscript

Claims (9)

(57) [Claims] 1. Image light obtained by optical scanning is optically converted.
Input through the system, convert the image light into an image signal and output.
With an image sensor that applies force and the image sensor
Drive the image sensor with a high-frequency pulse signal,
Circuit board for processing the image signal output from the image sensor
A plate and the circuit board, which is arranged in proximity to the circuit board,
On the circuit board with driving and processing of the image signal
A mirror image current that cancels the noise current generated along
A metal surface is provided, and the circuit board mounts the image sensor,
A first circuit board having a drive circuit that drives the image sensor with the high-frequency pulse signal; and a second circuit board that performs a predetermined process on the image signal from the image sensor,
A connection part for connecting the first circuit board and the second circuit board; the metal surface has a single surface; and the first circuit board and the second circuit board, Japanese that are arranged close on a single plane parallel to the same plane
Image reading apparatus according to symptoms. 2. Image light obtained by optical scanning is optically converted.
Input through the system, convert the image light into an image signal and output.
With an image sensor that applies force and the image sensor
Drive the image sensor with a high-frequency pulse signal,
Circuit board for processing the image signal output from the image sensor
A plate and the circuit board, which is arranged in proximity to the circuit board,
On the circuit board with driving and processing of the image signal
A mirror image current that cancels the noise current generated along
A metal surface is provided, and the circuit board mounts the image sensor,
A first circuit board having a drive circuit for driving the image sensor, a second circuit board that performs a predetermined process on the image signal from the image sensor, the first circuit board, and the second circuit. A first surface that is orthogonal to the optical scanning direction, and a second surface that is parallel to the optical scanning direction; and The circuit board is arranged close to the first surface, and the second circuit board is arranged close to the second surface.
An image reading device characterized by the above . Wherein said first circuit board, the second circuit board and the connection unit, an image reading apparatus according to claim 1 or 2, wherein the structure formed as a circuit board for integrated. Wherein said connecting portion includes an image reading apparatus according to claim 1 or 2 wherein the structure is a flexible cable. 5. The first circuit board and the second circuit
Substrate, wherein the structure that is attached by fasteners to provide a predetermined distance between the metal surface to claim 1 or 2
The image reading device described. 6. The structure in which the predetermined distance is 20 mm or less.
The image reading device according to claim 5. 7. The fixture is made of metal, and the first circuit board and the second circuit board have a ground and a metal surface of the first circuit board and the second circuit board. Claim 5 of the structure electrically connected
The image reading device described. 8. The fixture is made of an insulating member, and the first circuit board and the second circuit board have a ground and a metal surface of the first circuit board and the second circuit board. 5. The structure according to claim 5, wherein is electrically insulated.
The image reading device described. Wherein said optical system includes an image reading apparatus according to claim 1 or 2 wherein the configuration with refraction member that refracts the image light in a direction perpendicular to the direction of the optical scanning.