JP2010109427A - Image reading apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image reading apparatus that minimizes deterioration in the image quality due to temperature variations. <P>SOLUTION: A circuit board 72, mounted with an image sensor 71, is fixed to a support member 52 with a screw 82, at one position of intersection with an optical axis L of a lens unit 60 that allows the circuit board 72 to be extend due to swelling, accompanying the rise in temperature in the image reading apparatus, thereby preventing bending in the circuit board 72. Consequently, displacement of the image sensor 71 along the optical axis L is eliminated, and displacement of an imaging element on the image sensor 71, in a plane orthogonal to the optical axis L accompanying expansion of the circuit board 72, is minimized and restrains the image reading range of the image sensor 71 from deviating from a normal range, and reduces the deterioration in the image quality accompanying the rise in the temperature. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image reading apparatus, and more particularly to a structure that suppresses a positional deviation in the optical axis direction from an imaging position of a solid-state imaging device in the image reading apparatus.

  In general, in an image reading apparatus that optically reads a document such as a copying machine or an image scanner, the document is illuminated with an exposure lamp, and reflected light from the document surface is provided with an imaging lens composed of a plurality or a single lens. An image is formed on the light receiving surface of an image sensor (solid-state image sensor) via the image sensor, and image data of the document is acquired by taking out a signal from the image sensor.

  For example, as shown in FIG. 12, the image sensor 271 is mounted on a plate-like circuit board 272 so that the image sensor 271 is orthogonal to the optical axis L. A configuration is disclosed in which a pair of support members 252 erected on a base 251 at both ends in the longitudinal direction of the circuit board 272 are fixed by screws 282 while being maintained (see Patent Document 1).

However, the above configuration has the following problems.
That is, when the temperature inside the image reading apparatus rises due to heat generated by the image sensor 271 and the mounted components on the circuit board 272, heat generated by the exposure lamp, and temperature change in the surrounding environment, the circuit board 272 and the base 251 Thermal expansion. However, there is a difference in the coefficient of linear expansion between the material of the circuit board 272 (for example, a glass fiber cloth impregnated with epoxy resin) and the material of the base 251 (for example, iron), and the former is usually the latter. Therefore, the extension amount in the longitudinal direction of the circuit board 272 exceeds the extension amount in the direction connecting the pair of support members 252 of the base 251, and the circuit board 272 is bent.

As a result, as shown in FIG. 13, the image sensor 271 mounted on the circuit board 272 is displaced by a distance β in the optical axis L direction of the lens. Due to this displacement, the imaging position deviates from the light receiving surface of the image sensor 271, and the reflected light from the original does not form an image accurately on the image sensor 271, causing deterioration in image quality.
The circuit board 272 may bend in a direction approaching the imaging lens as shown in the figure, or may be bent in a direction away from the image forming lens. Although it cannot be said, there is no change in the positional deviation on the optical axis between the imaging position and the light receiving surface of the image sensor 271 even when the distance is long.

In order to solve this problem, Patent Document 2 discloses that one end of the circuit board 272 in the longitudinal direction or the lateral direction is outside the range where the image sensor 271 is projected onto the circuit board 272 along the optical axis L, such as a screw. A structure is disclosed in which a long hole extending in the longitudinal direction or the short side direction is provided at the other end of the circuit board 272 and is fastened and supported by a stepped screw while being fixed by a screw. By adopting such a configuration, the circuit board 272 can be prevented from extending in the longitudinal direction or the short direction of the circuit board 272 due to a temperature change through the long hole, and the circuit board is not bent.
Japanese Patent Laid-Open No. 10-294827 JP 2005-176267 A

  However, even if the configuration described in Patent Document 2 is adopted, there are the following problems. That is, when the circuit board 272 is fixed at one end in the longitudinal direction and supported at the other end, when the temperature inside the image reading apparatus rises and the circuit board 272 expands in the longitudinal direction, the circuit board is accordingly accompanied. The position of the image sensor 271 mounted on the 272 is also displaced in the longitudinal direction, and the position of the read image is shifted in the main scanning direction. In the worst case, the edge portion of the original image is cut off, There is a possibility that an image in a range to be read cannot be read.

  When the circuit board is fixed at one end in the short direction and supported at the other end, the displacement of the mounting position of the image sensor 271 is small compared to the case in the longitudinal direction. Depending on the distance and the amount of temperature rise, the image sensor 271 may shift from the normal image reading position as the circuit board 272 extends in the short direction (sub-scanning direction), and the original image may not be read accurately. Exists.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an image reading apparatus that can suppress image quality deterioration and reading position shift due to temperature changes as much as possible.

  In order to solve the above problems, an image reading apparatus according to the present invention receives reflected light from a document surface on a light receiving surface of a solid-state imaging device mounted on a circuit board via an imaging lens and receives image data. In the image reading device to be generated, the circuit board is fixed at one point from the back surface of the circuit board in a state where the light receiving surface of the mounted solid-state imaging device is orthogonal to the optical axis of the imaging lens. The fixed position on the circuit board is within a range in which the mounted solid-state imaging device is projected onto the circuit board along the optical axis.

  With the above configuration, there is no part that restricts the expansion of the circuit board due to temperature change, and it is possible to prevent image quality deterioration caused by the displacement of the solid-state image sensor in the optical axis direction due to the bending of the circuit board. By fixing the circuit board within the range projected onto the circuit board along the optical axis, the distance from the fixed position to the image sensor at the farthest position can be made shorter than before, and the expansion of the circuit board As a result, the displacement of the solid-state imaging device on the plane orthogonal to the optical axis is reduced, and the deviation of the reading position can be reduced.

Here, the fixed position on the circuit board may be substantially coincident with a position where the center position of the light receiving surface of the solid-state imaging device is projected onto the circuit board along the optical axis.
Furthermore, the position where the circuit board is fixed to the support member may be substantially on the optical axis of the imaging lens.
Thereby, the displacement of the solid-state imaging device on the plane orthogonal to the optical axis accompanying the expansion of the circuit board becomes symmetric with respect to the fixed position, and the displacement of the end of the solid-state imaging device can be reduced as much as possible.

Moreover, it is good also as providing the rotation control means which controls the rotation centering | focusing on the said fixed position of the said circuit board.
This restricts the force that the circuit board tries to rotate around the fixed position, making it easier to position the circuit board during assembly, and causing the circuit board to rotate around the fixed position due to vibration during use. Can be prevented.

Further, the rotation restricting means includes an elongated hole provided in one of the support member and the circuit board and an engaging pin provided in the other and engaging with the elongated hole, and substantially extending in the longitudinal direction of the elongated hole. The fixed position may exist on the line.
Thereby, since the rotation restricting means does not restrict the expansion of the circuit board around the fixed position, the position of the circuit board in the rotation direction can be stabilized without causing the circuit board to bend. There is.

Further, here, at the fixed position, there is provided an attitude adjustment member that is interposed between the support member and the circuit board and adjusts the inclination of the light receiving surface of the solid-state imaging device with respect to a plane perpendicular to the optical axis. It may be characterized by.
Thereby, at the time of attachment, it is possible to finely adjust so that the light receiving surface of the solid-state imaging device is in a plane perpendicular to the optical axis.

Here, the circuit board is fixed to the support member via a screw at the fixing position, and the posture adjusting member includes two wedge-shaped members having through holes into which the screw is loosely inserted. It is good also as a characteristic that it combines so that may contact | connect.
Accordingly, there is an effect that the inclination with respect to the plane orthogonal to the optical axis when the circuit board is attached can be easily finely adjusted while the number of parts is small.

The posture adjusting member may be made of a highly heat conductive material.
Thereby, the heat which a solid-state image sensor and a circuit board generate | occur | produce can move to an attitude | position adjustment member easily, and the effect which suppresses the temperature rise of a circuit board is acquired.
Furthermore, the support member may be made of a highly heat conductive material.
As a result, the heat generated by the solid-state imaging device and the circuit board is easily transferred to the support member through the attitude adjustment member, and the support member serves as a heat dissipation member, thereby increasing the temperature of the circuit board more effectively. There is an effect that can be suppressed.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments according to the present invention will be described below with reference to the drawings, taking as an example a case where the embodiments are applied to an image reading apparatus. In the drawings shown below, the dimensions and ratios of the respective constituent elements are appropriately different from the actual ones in order to make the respective constituent elements recognizable on the drawings.
<Embodiment 1>
(1. Overall configuration of image reading apparatus)
FIG. 1 is a schematic diagram showing an overall configuration of an image reading apparatus 1 according to an embodiment of the present invention.

  As shown in FIG. 1, the image reading apparatus 1 includes a document pressing plate 2 and an image reading unit 3, and the image reading unit 3 is provided in a box-shaped machine frame 32 in which a platen glass 31 is fitted on the upper surface. A unit 33, a folding mirror unit 34, a control unit 40, an image reading unit 50, and the like are provided. The scanner unit 33 includes an exposure lamp 331 and a folding mirror 332. The folding mirror unit 34 includes folding mirrors 341 and 342. On the upper surface of the machine frame 32, a document pressing plate 2 for pressing a document placed on the platen glass 31 from above is pivotally supported so as to be openable and closable with respect to the machine frame 32.

  An original placed on the platen glass 31 is irradiated by an exposure lamp 331 through the platen glass 31. The reflected light from the document is reflected in the horizontal direction by the folding mirror 332, further reflected by the folding mirrors 341 and 342, and enters the image reading unit 50. The image reading unit 50 includes a lens unit 60, an image sensor 71, and the like, which are covered with a cover 100.

  When performing document reading, the scanner unit 33 is moved in the direction of arrow A in the figure by a drive mechanism (not shown) to scan the document image (this scanning method is generally referred to as “mirror scan method”). "). At this time, the folding mirror unit 34 is moved in the same direction as the scanner unit 33 at a speed that is half of the moving speed thereof, so that the document surface to the lens unit 60 in the image reading unit 50 is moved. With the optical path length kept constant, the reflected light from the document can be imaged on the light receiving surface of the image sensor 71 in the image reading unit 50.

As a driving mechanism of the scanner unit 33, for example, the scanner unit 33 is slidably held on two or more rails arranged in parallel with the direction of the arrow A, and is stretched on a pulley. A known drive system is used in which the scanner unit 33 is connected to a part of the wire, and the wire is driven by the scanner motor M.
Reflected light from the document incident on the image sensor 71 is converted into an electrical signal, A / D converted by the control unit 40 to become a multi-value digital signal, and further subjected to processing such as shading correction, density conversion, and edge enhancement. Is stored in the image memory in the control unit 40.
(2. Configuration of the image reading unit 50)
2 and 3 are schematic views showing the configuration of the image reading unit 50. FIG.

2 is a cross-sectional view taken along a vertical plane including the optical axis L, and FIG. 3 is a cross-sectional view taken along a horizontal plane including the optical axis L. As shown in FIGS. 2 and 3, the image reading unit 50 has a structure in which a base 51 is covered with a cover 100, and reflected light from a document is located near the end of the base 51 in the X ′ direction. Is provided with a lens unit 60.
The lens unit 60 includes a plurality of imaging lenses 61 and a lens bracket 62 that holds them. The lens bracket 62 is fixed at a predetermined position on the base 51.

The cover 100 is made of a resin material or a metal material such as iron, and has an opening at the end face in the X ′ direction so that the reflected light of the document from the folding mirror unit 34 can enter the lens unit 60.
An imaging unit 70 is disposed at a predetermined distance from the lens unit 62 at a later stage in the traveling direction of the reflected light of the lens unit 60. The imaging unit 70 has a configuration in which an image sensor 71 having an imaging element is mounted on a circuit board 72 and the circuit board 72 is fixed to a support member 52 attached to the base 51. As the image sensor 71, an imaging device such as a CCD image sensor or a CMOS image sensor is used.

The circuit board 72 is formed of a plate-shaped resin material (for example, a glass fiber cloth impregnated with an epoxy resin). A circuit pattern formed using copper foil is provided on the circuit board 72, and an image sensor 71 and electronic components for driving the image sensor 71 are mounted on the circuit pattern. .
4 is a perspective view showing a state in which the imaging unit 70 is fixed to the support member 52, and FIG. 5 is a cross-sectional view of the horizontal plane including the optical axis L. As shown in FIG. A round hole 73 is formed at a substantially central position of the circuit board 72, and a nut member 81 is fitted from the side on which the image sensor 71 of the round hole 73 is mounted, and the flange 81 a contacts the circuit board 72. Installed in contact. Then, the light receiving surface of the image sensor 71 is mounted on the circuit board 72 in such a state that the center of the light receiving surface of the image sensor 71 is substantially on the central axis of the screw hole of the nut member 81 from above.

The distal end portion of the nut member 81 is fitted into a circular hole 53 provided in a support member 52 erected at a predetermined distance from the lens unit 60 in the base 51, and a circuit is formed using an appropriate jig. The circuit board 72 is fixed to the support member 52 by tightening the screw 82 in the screw hole of the nut member 81 in a state where the longitudinal direction of the board 72 is maintained parallel to the base 72.
In the present embodiment, instead of the round holes 73 and 53 of the circuit board 72 and the support member 52, a through hole having a polygonal cross section is provided, and the shape of the cross section of the nut member 81 is also fitted thereto. By adopting the polygon to be used, it is possible to avoid the rotation of the nut member 81 at the time of screw tightening, and the attachment work is facilitated.

Further, the thickness of the flange 81a may be suppressed to a size that does not interfere with the back surface of the individual imaging element 71, and a part or all of the flange 81a may be immersed in the circuit board 72 in some cases. By doing so, it is possible to reduce the risk of the flange 81a of the nut member 81 coming into contact with the image sensor 71 to cause breakage, deformation, distortion or the like.
As described above, by fixing the circuit board 72 to the support member 52 at almost one position on the optical axis L, even if the circuit board expands / contracts due to a temperature change, other expansion / contraction is restricted. Therefore, the circuit board 72 expands and contracts freely in a plane parallel to the main surface thereof, and does not bend in the direction of the optical axis L.

Accordingly, the distance from the lens unit 60 to the image sensor 71 does not change, and the image formation position does not deviate from the image sensor 71 and image quality does not deteriorate. Furthermore, since there is only one fixed part, there are effects of simplifying the mounting process and reducing the number of parts.
In the present embodiment, the fixing position (round hole 73) of the circuit board 72 is configured to substantially coincide with the projection position on the circuit board 72 at the center of the light receiving surface of the image sensor 71. Such an effect is obtained. The center of the light receiving surface means the intersection of the center line in the longitudinal direction of the light receiving surface and the center line in the short direction.

(1) Since the distance from the farthest image sensor of the image sensor 71 as viewed from the fixed position of the circuit board 72 (hereinafter referred to as “outermost image sensor”) can be minimized. In addition, the amount of displacement of the outermost imaging pixel due to thermal expansion can be minimized, and occurrence of errors in the reading range can be suppressed as much as possible.
(2) Since the fixed position can be approximated to the center of gravity of the combined member of the image sensor 71 and the circuit board 72, the left and right moments around the fixed position caused by gravity can be made substantially equal. It is difficult for the circuit board to rotate.

(3) Even if the circuit board 72 is slightly rotated around the screw 82 due to vibration or the like, the distance to the fixing position by the screw 82 of the outermost image sensor is short, so the circuit board 72 is rotated. The amount of displacement in the plane orthogonal to the optical axis L of the outermost imaging element can be minimized.
(4) Usually, the image sensor 71 is provided with lead pins symmetrically with respect to the center in the longitudinal direction as shown in FIG. 3, so that the circuit board is symmetrical in the longitudinal direction with the fixed position as a starting point. When the thermal expansion occurs, a force is applied to the longitudinal direction of the solid-state image sensor 71 so as to displace it almost equally in the opposite direction to the center, and the displacement of the lead pin is absorbed by the elasticity of the lead pin. It can be considered that the 71 main body is hardly displaced.

Furthermore, since the circuit board 71 is held at a fixed position on the optical axis L of the imaging lens 61, the displacement amount of the image sensor can be maintained symmetrically across the optical axis L, and the read image is further deteriorated. Inconspicuous.
However, the fixing position 80 on the circuit board 72 by the nut member 81 and the screw 82 does not necessarily coincide with the position where the center of the image sensor 71 is projected onto the circuit board 72 along the optical axis L. 71 may be within a range projected onto the circuit board 72 in a direction parallel to the optical axis L. By doing in this way, compared with the case where a fixed position is outside the projection range of the image sensor 71 as in the prior art, the distance from the fixed position 80 of the outermost image sensor of the image sensor 71 is reduced, and the circuit board. This is because the displacement of the image sensor 71 due to the thermal expansion of 72 is also reduced.

<Embodiment 2>
In the first embodiment, the configuration in which the image sensor 71 is held on the support member 52 at a predetermined point on the back surface of the circuit board 72 has been described.
In the present embodiment, this will be further developed, and a configuration provided with an attitude adjustment unit that adjusts the inclination of the circuit board 72 when attached to a surface perpendicular to the optical axis L will be described. In addition, in order to avoid duplication of description, the description is abbreviate | omitted about the thing with the same content as Embodiment 1, and shall attach | subject the same code | symbol about the same component.

As shown in FIG. 6, the posture adjustment unit 90 has a shape obtained by cutting a cylinder along a plane that obliquely intersects the central axis thereof, and has wedge-shaped posture adjustment members 91 and 92 each having a through hole 911 and a through hole 921. Consists of.
The posture adjusting members 91 and 92 have wedge surfaces 912 and 922, respectively.
In FIG. 6, the angles formed by the wedge surfaces 912 and 922 with respect to the end surfaces 913 and 923 are exaggerated for easy understanding. However, in reality, the angles are so small as to interpolate an assembly error in the manufacturing stage. If it is.

  FIG. 7 is a cross-sectional view of a horizontal plane including the optical axis L in the mounting portion of the circuit board 72 in the present embodiment. As shown in the figure, the posture adjustment unit 90 is used by being loosely inserted between the circuit board 72 and the support member 52 and at the tip of the screw 82 and the nut member 81. In the case of the figure, the main surface of the support member 52 is perpendicular to the optical axis L, and there is no need to adjust the inclination, and the posture adjustment members 91 and 92 are arranged so that the end surfaces 913 and 923 are parallel to each other. The relative position in the rotation direction is adjusted.

  As shown in FIG. 8, when the main surface of the support member 52 is inclined by α with respect to a plane orthogonal to the optical axis L (XX ′ direction), the posture adjustment is performed at the assembly stage of attaching the image sensor 71. By rotating the members 91 and 92 relatively, as shown in FIG. 9, as shown in FIG. 9, the intersection angle between the surface in contact with the circuit board 72 and the surface in contact with the support member 52 (that is, the angle between the end surfaces 913 and 923). ) Is adjusted to α, and the posture of the circuit board 72 is adjusted so as to eliminate the tilt angle α. The posture adjustment of the circuit board 72 that eliminates the angle α is, for example, an image of reflected light from a manuscript (for example, a chart in which black lines or black dots are drawn at both ends of the reading area) in which the image formation state can be easily confirmed. This is performed by detecting the imaging state from the intensity distribution of the light received by the sensor 71 and received by the image pickup devices at both ends of the image sensor 71 and adjusting the posture of the circuit board 72 so that there is no difference at both ends. be able to.

At this time, since the central axes of the through holes 911 and 921 of the posture adjusting members 91 and 92 are inclined with respect to each other, the inner diameters of the posture adjusting members 91 and 92 are slightly larger than the outer diameter of the nut member 81, The member 81 and the screw 82 are allowed to penetrate both.
In FIG. 9, the angle α is exaggerated for easy visual recognition. However, in practice, the angle α is usually a minute one or less.

  Further, when the posture adjusting members 91 and 92 have the same center axis and are in contact with each other, that is, when the posture adjusting unit 90 is in a completely cylindrical state, the height of the posture adjusting unit 90 is high. Therefore, the resistance to the tightening force caused by the screwing of the nut member 81 and the screw 82 is minimized. Therefore, in a state in which the posture adjusting members 91 and 92 are relatively rotated to cause a shift in the central axis, a force is applied to cancel the shift and return to the original position. Therefore, in order to maintain the state in which the posture of the circuit board 72 is adjusted so as to eliminate the inclination angle α, some means for stopping the force to return to the original is necessary. Therefore, in the present embodiment, the posture adjusting members 91 and 92 are arranged so that the wedge surfaces 912 and 921 that are in contact with each other are rough surfaces so that a large frictional resistance is generated between the wedge surfaces 912 and 922. Then, by inserting a spring washer 84 (see FIG. 8) and keeping the urging force at a certain level or more, the posture adjusting members 91 and 92 are prevented from shifting and returning to the original rotational position. .

In the above embodiment, the outer shape of the posture adjustment unit 90 is a cylindrical shape. However, the outer shape is not limited to this. For example, it is easy to hold and rotate the outer peripheral surface of the cylinder so that it can be easily held and rotated from outside. Protrusions or depressions may be provided in the part, or a polygonal column shape or a gear shape may be used.
Furthermore, by using a material having a relatively high thermal conductivity member, for example, a metal or a filler mixed with a filler such as metal or carbon having an effect of improving thermal conductivity, in the posture adjustment unit 90, The effect of suppressing the temperature rise of the circuit board 72 by conducting the heat of the circuit board 72 to the support member 52 through the attitude adjustment unit 90 can also be expected.

At that time, similarly, a material having high thermal conductivity, for example, a resin mixed with metal or a metal filler is used for the support member 52, so that the heat of the circuit board 72 has a larger heat capacity via the posture adjustment unit 90. Conducting to the support member 52, and further the role of the support member 52 as a heat radiating member makes it possible to more effectively suppress the temperature rise of the circuit board 72.
<Modification>
As described above, the present invention has been described based on the embodiment. However, the present invention is not limited to the above-described embodiment, and the following modifications can be implemented.
(1) In each of the above embodiments, a rotation restricting member may be provided so that the circuit board 72 does not rotate with respect to the support member 52.

FIG. 10 is a perspective view when viewed from the support member 52 side for showing a modification of the first embodiment in this case, and FIG. 11 is a plane parallel to the base 51 including the optical axis L in FIG. It is a figure which shows a cross section.
As shown in both figures, a long hole 54 extending in the straight line direction is provided on a straight line passing through the center of the round hole 53 of the support member 52 and parallel to the longitudinal direction of the circuit board 72, and It is good also as a structure which engages with the rotation control pin 83 standingly arranged by.

With such a configuration, the rotation of the circuit board 72 around the fixed position 80 can be restricted, and the position of the circuit board 72 is further stabilized. In addition, positioning during assembly is facilitated and work efficiency is improved.
The position where the long hole 54 is provided is not necessarily limited to that shown in FIG. 10, and the fixing position 80 (the center of the round hole 53) may exist on the extended line of the long diameter.

With such a configuration, the circuit board 72 can be freely expanded and contracted with the fixed position 80 as a base point, and the rotation can be restricted without causing the circuit board 72 to bend.
In the above modification, the elongated hole 54 is oval. However, the present invention is not limited to this as long as the rotation restricting pin 83 can move smoothly in the elongated hole 54. For example, the elongated hole 54 may be an elongated rectangle. Further, the rotation restricting pin 83 is not limited to a cylindrical shape as long as it can move smoothly in the long hole 54, and may have another cross-sectional shape, for example.

Further, the rotation restricting pin 83 may be provided on the support member 52 side. In that case, a long hole is provided on the circuit board 72 side, and the rotation restricting pin 83 is inserted into the support member 52 from the surface of the support member 52 opposite to the surface in contact with the circuit board 72.
The rotation restricting pin 83 may be merely fitted into the circuit board 72 or a hole provided in the support member 52, but may be adhered to the circuit board 72 with an adhesive or the like. 72 or the support member 52 may be integrated. Furthermore, when the rotation restricting pin 83 is inserted from the circuit board 72 side, the rotation restricting pin 83 may be integrated with the nut member 81.
(2) In each of the above embodiments, the nut member 81 is inserted into the circular holes 73 and 53 provided in the circuit board 72 and the support member 52, and the screw 82 is screwed into the nut member 81. Although the circuit board 72 is fixed to the support member 52, the present invention is not limited to this, and the following may be employed. That is, without using the nut member 81, a convex portion having a screw hole at the center is provided integrally with the circuit board 72 on the surface opposite to the surface on which the image sensor 71 of the circuit board 72 is mounted, The convex portion may be inserted into a round hole 53 provided in the support member 52 and fixed by a screw 82.

Further, the screw 82 is inserted into the circular hole 53 provided in the support member 52, and the screw 82 is inserted into the hole provided in the portion of the circuit board 72 where the circuit pattern is not printed. The protruding portion of the screw 82 protruding on the surface opposite to the surface in contact with the support member 52 of 72 may be fixed by another screw such as a nut. In this case, it is preferable to use sufficiently small screws so that the protruding portion of the screw 82 and another screw such as a nut do not touch the image sensor 71 and cause damage, deformation, distortion, or the like. A part of the circuit board 72 may be immersed in the circuit board 72.
(3) In each of the above embodiments, an example using the mirror scan method has been described. Needless to say, the reading apparatus is not limited to this, and at least a condenser lens and an image sensor are provided. The present invention can be generally applied to an image reading apparatus that receives reflected light from a surface on a light receiving surface of an image sensor via a condenser lens. For example, a so-called sheet-through scanning image reading apparatus that reads an image through a specific area on a platen glass without moving a light source, a folding mirror, or the like, or an optical source such as a light source and a lens or a folding mirror The same effect can be obtained even when the element and the image sensor are housed in a single casing to form a unit, and the unit and the image sensor are moved to read an original so as to be applied to a so-called unit scan type image reading apparatus.

  In addition, an image forming apparatus that forms an image on a sheet based on image data, for example, a copier, a facsimile machine, a multi-function multifunction peripheral (MFP), and the like includes an image reading unit that reads an original image. In the case of the image reading unit, the image reading apparatus described above can be applied as the image reading unit. Furthermore, the contents of the above embodiment and the above modification examples may be combined within a possible range.

  The image reading apparatus of the present invention is useful as a technique for preventing image sensor displacement in the optical axis direction and minimizing displacement in a plane perpendicular to the optical axis to minimize image quality degradation. .

1 is a schematic diagram illustrating an overall configuration of an image reading apparatus 1 according to an embodiment of the present invention. 3 is a schematic sectional view in the vertical direction showing the configuration of the image reading unit 50 of the image reading apparatus 1 in Embodiment 1. FIG. 2 is a schematic cross-sectional view in the horizontal direction showing the configuration of the image reading unit 50 of the image reading apparatus 1 according to Embodiment 1. FIG. FIG. 6 is a perspective view showing a manner of fixing the circuit board 72 to the support member 52 in the first embodiment. 3 is a schematic cross-sectional view in the horizontal direction illustrating the configuration of the imaging unit 70 of the image reading apparatus 1 according to Embodiment 1. FIG. FIG. 6 is a perspective view showing the configuration and configuration of a posture adjustment unit 90 in a second embodiment. 6 is a schematic cross-sectional view in the horizontal direction showing the configuration of the imaging unit 70 of the image reading apparatus 1 according to Embodiment 2. FIG. FIG. 9 is a horizontal schematic cross-sectional view showing a configuration of an image pickup unit 70 of the image reading apparatus 1 showing a state after adjusting a tilt when the circuit board 72 is attached in the second embodiment. In Embodiment 2, it is a perspective view which shows the state which rotated the attitude | position adjustment unit 90 and produced the inclination. FIG. 11 is a perspective view showing a manner of fixing the circuit board 72 to the support member 52 in Modification (1). In modification (1), it is horizontal sectional drawing which shows the aspect of fixation to the supporting member 52 of the circuit board 72. FIG. FIG. 6 is a horizontal cross-sectional view of an image reading unit 50 illustrating a configuration in which a circuit board 272 is fixed to a support member 252 at two locations in the prior art. FIG. 6 is a horizontal sectional view of the image reading unit 50 showing a state in which the circuit board 272 expands and bends due to a temperature rise and the image sensor 271 is displaced by β in the optical axis L direction in the prior art. .

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image reading apparatus 2 Document holding plate 3 Image reading part 31 Platen glass 32 Machine frame 33 Scanner unit 331 Exposure lamps 332, 341, 342 Folding mirror 34 Folding mirror unit 40 Control part 50 Image reading units 51, 251 Bases 52, 252 Support member 53, 73 Round hole 54 Long hole 60, 260 Lens unit 61, 261 Imaging lens 62, 262 Lens bracket 70 Imaging unit 71, 271 Image sensor 72, 272 Circuit board 80, 280 Fixed position 81 Nut member 81a Flange 82 , 282 Screw 83 Rotation regulating member 84 Spring washer 90 Attitude adjustment unit 91, 92 Attitude adjustment member 911, 921 Through hole 912, 922 Wedge surface 913, 923 End surface 100 Cover

Claims (9)

An image reading device that receives reflected light from a document surface via an imaging lens on a light receiving surface of a solid-state imaging device mounted on a circuit board and generates image data,
A support member that holds the circuit board fixed at one point from the back surface of the circuit board in a state where the light receiving surface of the mounted solid-state imaging device is orthogonal to the optical axis of the imaging lens;
An image reading apparatus characterized in that the fixing position of the support member with respect to the circuit board is within a range in which the mounted solid-state imaging device is projected onto the circuit board along the optical axis. 2. The image reading apparatus according to claim 1, wherein the fixed position on the circuit board substantially coincides with a position where the center position of the light receiving surface of the solid-state imaging device is projected onto the circuit board along the optical axis. . The image reading apparatus according to claim 1, wherein a position at which the circuit board is fixed to the support member is substantially on an optical axis of the imaging lens. The image reading apparatus according to claim 1, further comprising a rotation restricting unit that restricts the circuit board from rotating about the fixed position.   The rotation restricting means includes an elongated hole provided in one of the support member and the circuit board, and an engagement pin provided in the other and engaging with the elongated hole, on a substantially extended line in the longitudinal direction of the elongated hole. The image reading apparatus according to claim 4, wherein the fixed position exists. An attitude adjustment member that is interposed between the support member and the circuit board at the fixed position and adjusts an inclination of a light receiving surface of the solid-state imaging device with respect to a plane perpendicular to the optical axis. Item 4. The image reading apparatus according to any one of Items 1 to 3. The circuit board is supported by the support member via a screw at the fixed position,
The image reading apparatus according to claim 6, wherein the posture adjusting member is formed by combining two wedge-shaped members having through holes into which the screws are loosely inserted so that the wedge surfaces are in contact with each other. The image reading apparatus according to claim 6, wherein the posture adjusting member is made of a highly heat conductive material. The image reading apparatus according to claim 1, wherein the support member is made of a high thermal conductivity material.

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