JP2009093061A - Image reading device and image forming device with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image reading device which ensures the positional accuracy of an image sensor, even if a temperature varies, and improves productivity by eliminating complicated parts assembly, and to provide an image forming device with the same. <P>SOLUTION: The image reading device 80 includes: a circuit board 81 with an image sensor 74; a holding member 85 which comprises a material, which is different in thermal expansion coefficient from the circuit board 81, and holds the circuit board 81; and an imaging lens 73 which forms an optical image on the image sensor 74. The holding member 85 includes: a board-holding part 85g which holds the circuit board 81 with its vertical displacement to the optical axis Z possible under the condition that a screw 86 is inserted into a long hole 81d via an elastic washer 87 to fit in the screw hole 85h; and sensor-contacting parts 85e, 85f which make the image sensor 74 come into contact, via elastic parts 90a, 91b, in the vertical direction to the optical axis. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image reading apparatus that optically reads a document and an image forming apparatus such as a copying machine, a facsimile, and a printer including the image reading apparatus.

  In general, in an image reading apparatus that optically reads a manuscript such as a copying machine or an image scanner, reflected light from the manuscript obtained by an illumination lamp is electrically converted by an image sensor having an image sensor such as a CCD (Charge Coupled Device). The document is converted into a signal and read. As a method of mounting this image sensor on an image reading device, for example, as described in Patent Document 1, first, the image sensor is mounted on a plate-like circuit board, and this circuit board is mounted on a holding member such as a bracket. A method of mounting in an image reading apparatus by fixing with a fastening member such as a screw is mainly used.

  By the way, in the image reading apparatus, the internal temperature changes due to heat generated by the image sensor and the mounted parts on the circuit board and the temperature change of the surrounding environment. When a temperature change occurs inside the apparatus in this way, as described in Patent Document 1, if the circuit board on which the image sensor is mounted is fixed to the holding member, the circuit layer of the board or the material of the board itself Contracts or expands, and the circuit board is deformed or bent due to the difference in thermal expansion coefficient between the members. When the circuit board is deformed or bent, the image sensor mounted on the circuit board moves in the optical axis direction of the lens along with the deformation or the bend. Specifically, when the temperature rises due to heat generated by components mounted on the circuit board, the circuit board deforms in a direction away from the lens, and when the temperature decreases, the circuit board moves in a direction in which the image sensor approaches the lens. There is a tendency to deform. If the circuit board is deformed in this way and the position of the image sensor is changed, the reflected light from the original does not form an image accurately on the image sensor, resulting in a problem that the image quality is deteriorated.

  Therefore, in Patent Document 2, in order to prevent the image sensor from moving in the optical axis direction of the lens due to such deformation of the circuit board, the circuit board including the image sensor is screwed on one end side in the longitudinal direction. It is fixed to the holding member, and is held by the holding member so that it can be displaced by a screw and a long hole on the other end side. As a result, when the circuit board expands and contracts when a temperature change occurs, the long hole moves in the longitudinal direction along with the expansion and contraction, and the circuit board can be prevented from being bent. The image sensor is prevented from moving in the optical axis direction of the lens.

  However, in recent years, it has become necessary to reduce the size of image reading apparatuses and to increase the definition of image reading. Accordingly, it is necessary to reduce the size of an image sensor and increase the number of pixels in the image sensor of the image sensor. In the prior art described above, the long hole of the circuit board moves in the longitudinal direction against the expansion and contraction of the circuit board due to the temperature change, but the image sensor provided on the circuit board also moves in the longitudinal direction. As a result, the image sensor is displaced on the imaging plane with respect to the lens, and the small and high-definition image sensor has a problem that the read image output from each pixel of the image sensor is disturbed. .

  Further, in Patent Document 3, in order to prevent the image sensor from moving in the lens optical axis direction due to heat generation of the mounted components on the image sensor and the circuit board, and expansion and contraction due to the temperature change of the surrounding environment, The image sensor is urged in the direction of the optical axis by the elastic member on the opposite surface of the holding member that is fixedly held by the holding member, and pressed and held.

  However, in the above-described conventional technology, since the holding member is provided between the circuit board and the image sensor, complicated assembly is performed. That is, the image sensor is pressed and held on the holding member by the elastic member, the circuit board is then faced to the holding member, the terminal extending from the image sensor is inserted into the hole of the circuit board, and the circuit board is held by a screw or the like. After fixing to the member, the terminal of the image sensor protruding from the circuit board fixed and held is fixed by a conductive adhesive member. In this configuration, in order to electrically connect the image sensor to the circuit board, the image sensor and the circuit board are assembled by interposing the holding member in the electric parts, such as the mounting of the electric parts and the assembly of the mechanical parts. Since these processes are mixed, there is a problem that assembly and mounting become complicated and the arrangement of circuit patterns on the circuit board is restricted.

Japanese Patent Laid-Open No. 10-294827 (paragraph [0003], FIG. 15) Japanese Patent Laying-Open No. 2005-176267 (paragraph [0023], FIGS. 1 and 3) JP 2002-171387 A (paragraphs [0021]-[0029], FIG. 2)

  The present invention has been made to solve the above-described problems, and ensures the positional accuracy of the image sensor even when there is a temperature change, and improves productivity by eliminating complicated parts assembly. An object of the present invention is to provide an image reading apparatus and an image forming apparatus that enable the above.

  To achieve the above object, the present invention provides an image reading apparatus including a circuit board provided with an image sensor, a holding member that holds the circuit board, and an imaging lens that forms an optical image on the image sensor. A fastening member for fastening the circuit board and the holding member, a holding elastic member having a biasing force in the optical axis direction of the imaging lens, and a first elastic member having a biasing force in a direction perpendicular to the optical axis. The holding member includes a substrate holding part that holds the circuit board in a direction perpendicular to the optical axis by the holding elastic member and the fastening member, and the image sensor is perpendicular to the optical axis by the first elastic member. And a sensor abutting portion that abuts in any direction.

  According to this configuration, even if the temperature environment of the apparatus changes and the member expands and contracts, the image sensor maintains the state in contact with the sensor contact portion of the holding member. Is merely displaced in a direction perpendicular to the optical axis with respect to the holding member, and there is no possibility that the image sensor is displaced on the image plane.

  According to this configuration, the circuit board on which the image sensor is mounted is held on the holding member by the fastening member and the holding elastic member, and the image sensor is assembled so as to contact the holding member via the first elastic member. In addition, the mounting of the electrical components and the assembly of the mechanical components are performed in separate processes, and there is no possibility that the arrangement of the circuit pattern on the circuit board is restricted.

  According to a second aspect of the present invention, the image sensor includes an image pickup device in which pixels are arranged in a longitudinal direction. According to this configuration, when the temperature environment of the apparatus changes, the circuit board expands and contracts in the longitudinal direction.

  In the invention of claim 3, the first elastic member has an urging force in the longitudinal direction, and the sensor abutting portion causes the image sensor to abut in the longitudinal direction by the first elastic member. It is a feature. According to this configuration, even if the member expands or contracts due to a temperature change, the image sensor maintains the state in contact with the sensor contact portion of the holding member. The image sensor is not displaced in the longitudinal direction only by displacement in the longitudinal direction.

  According to a fourth aspect of the present invention, the first elastic member has a biasing force in a direction perpendicular to the longitudinal direction, and the sensor contact portion causes the image sensor to be perpendicular to the longitudinal direction by the first elastic member. And a second elastic member having an urging force in the optical axis direction, and the second elastic member makes contact in the optical axis direction. According to this configuration, even if the member expands or contracts due to a temperature change, the image sensor maintains the state in contact with the sensor contact portion of the holding member. By only displacing in the direction perpendicular to the longitudinal direction, there is no possibility that the image sensor is displaced in the direction perpendicular to the longitudinal direction. In addition, even if the circuit board is bent due to the expansion and contraction of the member, the image sensor may maintain the state in contact with the sensor contact portion of the holding member, and thus the image sensor may move in the optical axis direction. Absent.

  According to a fifth aspect of the present invention, the fastening member is a screw, the board holding portion is provided with a screw hole, the circuit board is provided with a long hole extending in a longitudinal direction, and the screw is the holding elastic member. It is characterized by being attached to the long hole and the screw hole. According to this configuration, the circuit board is held by the holding member so as to be displaceable in a direction perpendicular to the optical axis.

  Further, in the invention of claim 6, the holding member, the screw, and the holding elastic member are made of a conductive member, and a ground portion formed by a circuit pattern is formed around the elongated hole on the circuit board. It is characterized by being provided. According to this configuration, the ground portion is electrically connected to the holding member via the elastic washer and the screw.

  Further, the present invention is an image forming apparatus equipped with the image reading apparatus having the above-described configuration.

  According to the first aspect of the present invention, even when the temperature environment of the apparatus changes and the member expands and contracts, the image sensor maintains the state of contacting the sensor contact portion of the holding member. Therefore, the position accuracy of the image sensor can be ensured because there is no possibility that the image sensor is displaced on the imaging surface only by the circuit board being displaced in the direction perpendicular to the optical axis with respect to the holding member. it can.

  According to the first aspect of the present invention, the circuit board on which the image sensor is mounted is held on the holding member by the fastening member and the holding elastic member, and the image sensor is brought into contact with the holding member via the first elastic member. In order to assemble in this way, mounting of electrical parts and assembly of mechanical parts are performed in separate processes, and there is no risk of complicated assembly processes. Further, there is no possibility that the arrangement of the circuit pattern on the circuit board is restricted.

  According to the second aspect of the present invention, when the temperature environment of the apparatus changes, the circuit board expands and contracts in the longitudinal direction, but there is no possibility that the image sensor is displaced in the longitudinal direction.

  According to the third aspect of the present invention, even if the member expands or contracts due to a temperature change, the image sensor maintains the contact state with the sensor contact portion of the holding member. Since only the substrate is displaced in the longitudinal direction with respect to the holding member, there is no possibility that the image sensor is displaced in the longitudinal direction, so that the positional accuracy of the image sensor can be ensured in the pixel array direction of the image sensor.

  According to the fourth aspect of the present invention, even if the member expands or contracts due to a temperature change, the image sensor maintains the state in contact with the sensor contact portion of the holding member. Since the substrate is only displaced in the direction perpendicular to the longitudinal direction with respect to the holding member, there is no possibility that the image sensor is displaced in the direction perpendicular to the longitudinal direction, and the positional accuracy of the image sensor can be ensured. In addition, even if the circuit board bends due to expansion or contraction of the member due to temperature change, the image sensor moves in the optical axis direction because the image sensor is kept in contact with the sensor contact portion of the holding member. Therefore, the optical image of the imaging lens is accurately formed on the image sensor.

  According to the invention described in claim 5, the circuit board can be displaced in a direction perpendicular to the optical axis with a simple configuration by attaching the screw to the elongated hole and the screw hole via the holding elastic member. It can be easily assembled to be held by the holding member.

  According to the invention described in claim 6, the ground portion is electrically connected to the holding member via the elastic washer and the screw, and noise generated from the circuit board can be reduced.

  According to the seventh aspect of the present invention, if the image forming apparatus is provided with the image reading apparatus, the positional accuracy of the image sensor is ensured even when there is a temperature change, and complicated parts assembly is performed. It is possible to provide an image forming apparatus that can improve productivity by eliminating the above.

  Embodiments of the present invention will be described below with reference to the drawings, but the present invention is not limited to these embodiments. The embodiment of the present invention shows the most preferable form of the invention, and the use of the invention and the terms shown here are not limited thereto.

  FIG. 1 is a cross-sectional view illustrating an image forming apparatus according to an embodiment of the present invention. The image forming apparatus 100 includes a paper feeding unit 1 disposed at a lower portion of the apparatus main body, a paper transporting unit 2 disposed on the right side and above the paper feeding unit 1, and an upper side of the paper transporting unit 2. The disposed image forming unit 3, the fixing unit 4 disposed downstream of the image forming unit 3 in the sheet conveying direction, and the image disposed above the image forming unit 3 and the fixing unit 4. A reading unit 5 and a document feeding unit 6 disposed above the image reading unit 5 are provided. The image reading unit 5 is an example of the image reading apparatus of the present invention.

  The paper feeding unit 1 is configured to feed a stack of papers stacked on a paper feeding cassette 11 detachably attached to the apparatus main body by a rotation operation of a paper feeding roller 12 having an arc outer peripheral part. Are fed to the paper transport unit 2 one by one from the topmost sheet by feeding the paper by the paper feeding unit 13 provided at the upper right end of each paper feed cassette 11. It is supposed to be.

  The sheet conveying unit 2 conveys the sheet fed from the sheet feeding unit 1 toward the image forming unit 3 by the conveying roller pair 21 and the registration roller pair 22, and further, the image forming unit 3 transfers the image at the fixing unit 4. The formed paper is discharged onto the discharge tray 24 by the discharge roller pair 23.

  The image forming unit 3 forms a predetermined toner image on a sheet by an electrophotographic process, and a photoconductive drum 31 having a photoconductivity supported rotatably and around the photoconductive drum 31. A charging unit 32, an exposure unit 33, a developing unit 34, a transfer unit 35, a cleaner 36, and a charge eliminating unit 37 are provided.

  The charging unit 32 includes a charging wire to which a high voltage is applied, and applies a predetermined potential to the surface of the photosensitive drum 31 by corona discharge from the charging wire. The exposure unit 33 irradiates the photosensitive drum 31 with laser light output from a laser emitter based on image data of a document read by the image reading unit 5 described later via a polygon mirror and a reflecting mirror. The surface of the photosensitive drum 31 is selectively attenuated to form an electrostatic latent image on the surface of the photosensitive drum 31. The developing unit 34 develops the electrostatic latent image with toner and forms a toner image on the surface of the photosensitive drum 31. The transfer unit 35 transfers the toner image on the surface of the photosensitive drum 31 onto a sheet. The cleaner 36 removes toner remaining on the surface of the photosensitive drum 31 after transfer. The static elimination unit 37 removes residual charges on the surface of the photosensitive drum 31.

  The fixing unit 4 fixes the toner image on the sheet by heating the sheet on which the toner image has been transferred in the image forming unit 3 between the heating roller 41 and the pressure roller 42.

  The document feeder 6 automatically conveys the documents placed on the document tray 61 one by one in response to an input instruction to start copying (copying), and the document discharge tray after exposure scanning of the document. (Not shown) A so-called sheet-through type document reading is performed to be discharged upward.

  The image reading unit 5 irradiates light on a document transferred by the document feeding unit 6 or a document placed on a contact glass, and reads the image information of the document by converting the reflected light into an electric signal. At the same time, image data corresponding to the document image is generated.

  FIG. 2 is a schematic cross-sectional view illustrating an image reading unit of the image forming apparatus. The image reading unit 5 includes a contact glass 8 on which the document P is placed, a scanner unit 7 that reads image information of the document P, and generates image data from the read image of the document P.

  The scanner unit 7 includes a first moving carriage 71 disposed above the scanner unit 7, a second moving carriage 72 disposed on the left side of the first moving carriage 71, and appropriate positions below the scanner unit 7. The image pickup unit 80 and the like disposed in FIG.

  The first moving carriage 71 and the second moving carriage 72 are connected to a scanning mechanism section (not shown), and the scanning mechanism section moves in the arrow direction (left-right direction) shown in FIG. 2 at a predetermined speed. The entire surface of the document P placed on the contact glass 8 can be scanned to read image information on the entire surface of the document.

  The first moving carriage 71 includes a frame 75 connected to the scanning mechanism unit, a light source 76 such as an exposure lamp that irradiates light on the document P placed on the contact glass 8, and light from the contact glass 8. A reflection mirror 78 that reflects toward the second moving carriage 72 is included.

  The second moving carriage 72 is provided with a pair of reflecting mirrors 72a and 72b arranged facing each other in the vertical direction, and the light from the reflecting mirror 78 of the first moving carriage 71 is sequentially reflected by the reflecting mirrors 72a and 72b. To the imaging unit 80.

  The imaging unit 80 includes an imaging lens 73 and an image sensor 74 disposed on the right side of the imaging lens 73.

  The image forming lens 73 has a plurality of lenses for forming an image of the reflected light from the original P incident through the reflection mirror 72 b of the second moving carriage 72, and is positioned at a predetermined position of the image pickup unit 80. Fixed.

  The image sensor 74 has an image sensor such as a CCD arranged in the longitudinal direction (the depth direction in FIG. 2) on the optical axis Z of the imaging lens 73, and is imaged on the image sensor by the imaging lens 73. The optical image of the original P is converted into an electric signal.

  In the image reading unit 5 configured as described above, light is emitted to the contact glass 8 by the light source 76, and reflected light from the document P on the contact glass 8 is reflected by the reflection mirror 78 of the first moving carriage 71, The reflected light is sequentially reflected by the reflection mirrors 72 a and 72 b of the second moving carriage 72, and an optical image of the document P is formed on the image sensor 74 via the imaging lens 73. Thereby, a part of the document P is read. Then, when the first moving carriage 71 and the second moving carriage 72 move at a predetermined speed, the entire surface of the document P is scanned, and the entire surface of the document P is read to form a read image.

  Next, the imaging unit 80 will be described in detail. FIG. 3 is a perspective view showing the imaging unit.

  As shown in FIG. 3, the imaging unit 80 includes an imaging lens 73 that forms an image of reflected light from the document P, an image sensor 74 that reads an image of the document P, a circuit board 81 on which the image sensor 74 is mounted, A holding member 85 that holds the image sensor 74 and the circuit board 81 and a bracket 78 that holds the holding member 85 are provided.

  The imaging lens 73 includes a plurality of lenses and a lens frame that fixes and holds these lenses, and is fixed to a lens bracket 78a formed of an L-shaped metal plate. The lens bracket 78a is fixed at a predetermined position on the base 78b, an opening is provided in the standing wall portion of the lens bracket 78a (not shown), and light from the imaging lens 73 is received by the image sensor 74. It is like that.

  The holding member 85 is formed of an inverted L-shaped metal plate and holds the circuit board 81 on which the image sensor 74 is mounted. In addition, the holding member 85 is fixedly held on a sensor bracket 78c formed of a metal plate by two screws 91 above the holding member 85. The sensor bracket 78c is fixed at a predetermined position on the base 78b so that the imaging lens 73 and the image sensor 74 are in an imaging relationship. The sensor bracket 78c is provided with a rectangular opening 78c1 larger than the image sensor 74 so that light from the imaging lens 73 is received by the image sensor 74.

  FIG. 4 is a perspective view of the circuit board on which the image sensor is mounted as viewed from the imaging lens side. The circuit board 81 is made of, for example, a plate-like resin material. A circuit pattern formed using copper foil is provided on the circuit board 81, and the image sensor 74 is mounted on the circuit pattern at the approximate center of the circuit board 81, and for driving the image sensor 74. The electronic component (not shown) is mounted on this circuit pattern. The circuit board 81 is provided with two long holes 81d for holding the circuit board 81 to the holding member 85 by a fastening member such as a screw. The two long holes 81d are long in the longitudinal direction X shown in FIG. 4, and are provided so that the longitudinal direction X of the two long holes 81d coincides with the longitudinal direction X of the image sensor 74. The image sensor 74 is provided in parallel on both sides in the longitudinal direction X. The shape of the two long holes 81d is not limited to the shape shown in FIG. 4, and may be, for example, a rectangle.

  The image sensor 74 includes a line sensor in which pixels of an image sensor such as a CCD that receives light from the imaging lens 73 are arranged in the longitudinal direction X. Covered with a package made of synthetic resin. Further, the image sensor 74 is provided with a terminal 74a for outputting an electrical signal and receiving a drive signal for driving the CCD. By soldering the terminal 74a to the circuit board 81, the circuit board is provided. 81.

FIG. 5 is a perspective view seen from the imaging lens side showing a state where the circuit board is attached to the holding member. The holding member 85 is a member formed by subjecting a metal plate to sheet metal processing such as bending into a substantially inverted L shape. The holding member 85 is provided with two screw holes 85 h in the vicinity of both end portions in the longitudinal direction X of the holding member 85 in order to hold the circuit board 81 using a fastening member such as a screw. Further, the holding member 85 is provided with an opening 85b for guiding the image sensor 74 at substantially the center of the holding member 85, and two openings 85c are provided near both sides in the longitudinal direction X of the opening 85b.

  Two surfaces of the holding member 85 between the opening 85b and the two openings 85c each form a sensor contact surface 85d, and each sensor contact surface 85d is on the light receiving surface side in the optical axis Z direction. In contact with the package of the image sensor 74. One opening 85c (the right opening in FIG. 5) is provided with a bent portion, and a sensor abutting portion 85e is formed on an end surface of the bent portion. This sensor abutting portion 85 e abuts on the package of the image sensor 74 in the longitudinal direction X. Further, two projecting portions as sensor contact portions 85f are provided above the opening 85b, and each sensor contact portion 85f contacts the package of the image sensor 74.

  The holding member 85 is provided with leaf springs 89 and 90 in the vicinity of each opening 85c, a leaf spring 91 is provided below the opening 85b, and each leaf spring 89 to 91 is fixed to the holding member 85 with positioning pins and screws. Retained.

  The plate spring 89 is formed with two elastic portions 89c having an urging force in the optical axis Z direction, and each elastic portion 89c extends from the opening 85c to the back side of the holding member 85 (the depth side in FIG. 5). Due to the biasing force, the package of the image sensor 74 is elastically brought into contact with the contact surface 85d. FIG. 6 is a perspective view showing the contact state. When the terminal 74 a of the image sensor 74 is electrically connected to the circuit board 81, a gap is formed between the image sensor 74 and the circuit board 81. In addition, each elastic part 89c is arranged in the gap and is in contact with the package of the image sensor 74.

  As shown in FIG. 5, the leaf spring 90 includes two elastic portions 90c having an urging force in the optical axis Z direction and an elastic portion 90a having an urging force in the longitudinal direction X between the two elastic portions 90c. Is formed. The two elastic portions 90c extend from the opening 85c to the back side (the depth side in FIG. 5) of the holding member 85, and the urging force causes the package of the image sensor 74 to elastically contact the contact surface 85d. Yes. The elastic portion 90a elastically contacts the package of the image sensor 74 with the contact surface 85e by the biasing force. FIG. 7 is a perspective view showing the contact state, and each elastic portion 90c is arranged in a gap formed between the image sensor 74 and the circuit board 81, and contacts the package of the image sensor 74. The elastic portion 90 c is in contact with the package side surface of the image sensor 74.

  As shown in FIG. 5, the leaf spring 91 is formed with an elastic portion 91b having an urging force in the vertical direction of the image sensor 74, and the elastic portion 91b urges the two packages of the image sensor 74 by the urging force. It is elastically brought into contact with the contact surface 85f. The elastic portions 90a and 91b constitute the first elastic member, and the elastic portions 89c and 90c constitute the second elastic member.

  FIG. 8 is a cross-sectional view showing a configuration in which the circuit board is held on the holding member by the fastening member. The circuit board 81 is elastically held by the holding member 85 by a fastening member 86 that is mounted from the depth side of the paper surface shown in FIG.

The screw 86 as a fastening member includes a screw portion 86a in which a thread is cut, a step portion 86b having an outer diameter larger than that of the screw portion 86a, and a head portion 86c having a driver slot. The screw portion 86 a is screwed into the screw hole 85 h of the holding member 85 so that the circuit board 81 is held by the holding member 85. The stepped portion 86b can be displaced in the longitudinal direction X between the circuit board 81 and the holding member 85 even if the outer diameter thereof is within the long hole 81d of the circuit board 81 and the member expands or contracts due to temperature change. The size (the vertical direction in FIG. 8) is larger than the thickness of the circuit board 81, and the elastic washer 87 and the washer 88 can be sandwiched between the circuit board 81 and the head 86c. It has become. In the direction perpendicular to the longitudinal direction X, the width of the long hole 81d is larger than the outer diameter of the stepped portion 86b, and a gap is provided between the long hole 81d and the stepped portion 86b. Thus, even if the member expands and contracts, the circuit board 81 and the holding member 85 can be displaced in the direction perpendicular to the longitudinal direction X.

  The elastic washer 87 has a corrugated cross section, and is fitted into the stepped portion 86b between the washer 88 in contact with the circuit board 81 and the head portion 86c of the screw 86, and the screw 86 is a screw of the holding member 85. When screwed into the hole 85h, an urging force is applied in the optical axis Z direction. By this urging force, the circuit board 81 is elastically held by the board holding portion 85g of the holding member 85 that contacts the circuit board 81. The biasing force is set to a predetermined strength based on the height of the stepped portion 86b of the screw 86 and the elastic force of the elastic washer 87. Therefore, even if the member expands or contracts due to a temperature change, the circuit board. 81 and the holding member 85 can be displaced in the direction perpendicular to the optical axis Z. The elastic washer 87 may be a holding elastic member, and its cross section may be a dish shape, an arc shape, or the like that applies an urging force in the optical axis Z direction instead of the corrugated shape. Further, the washer 88 can be omitted when the screw fastening force is stabilized by the elastic washer 87.

  On the circuit board 81, a ground part 81a is formed around the long hole 81d using a copper foil, and the ground part 81a is connected to a circuit pattern on which the image sensor 74 and its driving electronic components are mounted. Since the ground portion 81 a is provided at a portion pressed against the circuit board 81 and the washer 88 formed of a metal material by the screw 86, the ground portion 81 a is interposed via the washer 88, the elastic washer 87, and the screw 86. , And electrically connected to the holding member 85, noise generated from the circuit board 81 is reduced.

  When the circuit board 81 on which the image sensor 74 is mounted is attached to the holding member 85, as shown in FIG. 5, the image sensor 74 is first aligned with the opening 85b of the holding member 85, and then the circuit board 81 is held to the holding member 85. When facing each other, the long holes 81d face the screw holes 85h.

  Next, as shown in FIG. 8, with each long hole 81d facing each screw hole 85h, a washer 88 and an elastic washer 87 are placed in the long hole 81d on the circuit board 81, and a step portion 86b of the screw 86 is placed. When the screw portion 86a is screwed into the screw hole 85h of the holding member 85 until the step portion 86b contacts the substrate holding portion 85g of the holding member 85, the biasing force of the elastic washer 87 The circuit board 81 is elastically held by the board holding portion 85g of the holding member 85.

  Next, as shown in FIG. 5, when the leaf spring 90 is attached to the holding member 85 with a screw or the like, the image sensor 74 elastically contacts the sensor contact portion 85e by the urging force of the elastic portion 90a and is elastic. Due to the urging force of the portion 90c, it elastically contacts the left sensor contact portion 85d. Next, when the leaf spring 89 is attached to the holding member 85 with screws or the like, the image sensor 74 elastically contacts the right sensor contact portion 85d by the urging force of the elastic portion 89c. As a result, the image sensor 74 elastically contacts the holding member 85 in the longitudinal direction X and elastically contacts the optical axis Z direction. Next, when the leaf spring 91 is attached to the holding member 85 with a screw or the like, the image sensor 74 elastically contacts each sensor contact portion 85f by the urging force of the elastic portion 91b. As a result, the image sensor 74 elastically contacts the holding member 85 in the vertical direction.

  When the circuit board 81 is attached to the holding member 85 as described above, even if the temperature environment of the apparatus changes and the member expands or contracts, the image sensor 74 is connected to each sensor contact portion 85e of the holding member 85, Since the state in contact with 85f is maintained, the circuit board 81 is merely displaced in the direction perpendicular to the optical axis Z such as the longitudinal direction X or the vertical direction of the circuit board 81 with respect to the holding member 85. There is no possibility that the image sensor 74 will be displaced on the image plane. In addition, even if the circuit board 81 is bent due to expansion or contraction of the member due to temperature change, the image sensor 74 maintains the state of being in contact with each sensor contact portion 85d of the holding member 85. Does not move in the direction of the optical axis Z.

  According to the above embodiment, the image reading apparatus 80 includes the circuit board 81 including the image sensor 74, the holding member 85 that holds the circuit board 81 made of a material having a different thermal expansion coefficient from the circuit board 81, and the image. An imaging lens 73 that forms an optical image on the sensor 74 is provided. In addition, the image reading device 80 includes a screw 86 for fastening the circuit board 81 and the holding member 85, an elastic washer 87 having a biasing force in the optical axis Z direction of the imaging lens 73, and a biasing force in a direction perpendicular to the optical axis Z. The holding member 85 includes a screw 86 inserted into the elongated hole 81d through the elastic washer 87 and screwed into the screw hole 85h, thereby allowing the circuit board 81 to be perpendicular to the optical axis Z. A substrate holding portion 85g that holds the substrate in a displaceable manner, and sensor contact portions 85e and 85f that contact the image sensor 74 in a direction perpendicular to the optical axis Z by elastic portions 90a and 91b.

  According to this configuration, even if the temperature environment of the apparatus changes and the member expands or contracts, the state in which the image sensor 74 is in contact with the sensor contact portions 85e and 85f of the holding member 85 is maintained. Therefore, the image sensor 74 can be moved on the image plane only by moving the circuit board 81 in the direction perpendicular to the optical axis Z such as the longitudinal direction X or the direction perpendicular to the longitudinal direction X with respect to the holding member 85. Since there is no possibility of causing a positional shift, the positional accuracy of the image sensor 74 can be ensured.

  Further, according to this configuration, the circuit board 81 on which the image sensor 74 is mounted is held by the holding member 85 by the screw 86 and the elastic washer 87, and the image sensor 74 is held by the holding member 85 and each plate having the elastic portions 90a and 91b. In order to assemble so as to be brought into contact with each other via the springs 90 and 91, the mounting of the electrical parts and the assembly of the machine parts are performed in separate processes, and there is no possibility of a complicated assembly process. Further, there is no possibility that the arrangement of the circuit pattern on the circuit board 81 is restricted.

  Further, according to this configuration, the screw 86 is attached to the long hole 81d and the screw hole 85h via the elastic washer 87, so that the circuit board 81 is perpendicular to the optical axis Z to the holding member 85 by a simple configuration. It can be easily assembled so that it can be displaced in the direction.

  Further, according to the above-described embodiment, the image sensor 74 includes the imaging element that arranges the pixels in the longitudinal direction X, the elastic portion 90c has a biasing force in the longitudinal direction X, and the sensor contact portion 85e is elastic. By causing the image sensor 74 to abut in the longitudinal direction X by the portion 90c, the state in which the image sensor 74 abuts on the sensor abutting portion 85e of the holding member 85 is maintained even if the member expands or contracts due to a temperature change. is doing. For this reason, the circuit board 81 is only displaced in the longitudinal direction X with respect to the holding member 85, and there is no possibility that the image sensor 74 is displaced in the longitudinal direction X. The positional accuracy of the sensor 74 can be ensured.

  Further, according to the above embodiment, the elastic portion 90c having an urging force in the optical axis Z direction is provided, the elastic portion 91b has an urging force in a direction perpendicular to the longitudinal direction X, and the sensor contact portion 85f is an image. The sensor 74 is contacted in the direction perpendicular to the longitudinal direction X by the elastic portion 91b, and the sensor contact portion 85d is contacted in the optical axis Z direction by the elastic portion 90c. As a result, even if the member expands or contracts due to a temperature change, the circuit board 81 is held by the holding member 85 because the image sensor 74 is kept in contact with the sensor contact portion 85f of the holding member 85. On the other hand, only by displacing in the direction perpendicular to the longitudinal direction X, the image sensor 74 is not likely to be displaced in the direction perpendicular to the longitudinal direction X, and the positional accuracy of the image sensor 74 can be ensured. Further, even if the circuit board 81 is bent due to the expansion and contraction of the member, the image sensor 74 maintains the state of being in contact with the sensor contact portion 85d of the holding member 85. Since there is no fear of moving in the direction, the optical image of the imaging lens 73 is accurately formed on the image sensor 74.

  Further, according to the above embodiment, the holding member 85, the screw 86, and the elastic washer 87 are made of a conductive member, and the ground portion 81a formed in a circuit pattern around the long hole 81d on the circuit board 81. Is provided, the ground portion 81a is electrically connected to the holding member 85 via the elastic washer 87 and the screw 86, and noise generated from the circuit board 81 can be reduced.

  Further, according to the above-described embodiment, if the image forming apparatus 100 includes the image reading device 80, the positional accuracy of the image sensor 74 is ensured even when there is a temperature change, and complicated component assembly is performed. Thus, it is possible to provide the image forming apparatus 100 that can improve the productivity.

  The present invention can be used in an image reading apparatus that optically reads a document and an image forming apparatus such as a copying machine, a facsimile, and a printer including the image reading apparatus.

1 is a cross-sectional view showing an image forming apparatus according to an embodiment of the present invention. 1 is a schematic cross-sectional view showing an image reading unit of an image forming apparatus according to an embodiment of the present invention. These are the perspective views which show the imaging unit of the image reading part which is embodiment of this invention. These are the perspective views which show the circuit board of the image reading part which is embodiment of this invention. These are perspective views which show the state which attached the circuit board to the holding member of the image reading part which is embodiment of this invention. These are perspective views which show the state which makes a 1st elastic member contact | abut to the image sensor of the image reading part which is embodiment of this invention. These are perspective views which show the state which makes the 1st and 2nd elastic member contact | abut to the image sensor of the image reading part which is embodiment of this invention. These are sectional drawings which show the state which hold | maintains a circuit board to a holding member with the fastening member of the image reading part which is embodiment of this invention.

Explanation of symbols

5 Image reading unit (image reading device)
73 imaging lens 74 image sensor 78 bracket 80 imaging unit 81 circuit board 81a ground part 81d long hole 85 holding member 85b, 85c opening 85d, 85e, 85f sensor contact part 85g board holding part 85h screw hole 86 screw (fastening member)
87 Elastic washer (holding elastic member)
88 Washers 89, 90, 91 Leaf springs 89c, 90c Elastic part (second elastic member)
90a, 91b Elastic part (first elastic member)
100 Image forming apparatus

Claims (7)

In an image reading apparatus including a circuit board including an image sensor, a holding member that holds the circuit board, and an imaging lens that forms an optical image on the image sensor,
A fastening member for fastening the circuit board and the holding member; a holding elastic member having a biasing force in the optical axis direction of the imaging lens; and a first elastic member having a biasing force in a direction perpendicular to the optical axis, The holding member includes a substrate holding portion that holds the circuit board in a direction perpendicular to the optical axis by the holding elastic member and the fastening member, and a direction perpendicular to the optical axis by the first elastic member. An image reading apparatus comprising: a sensor abutting portion that abuts on the sensor.   The image reading apparatus according to claim 1, wherein the image sensor includes an image sensor that arranges pixels in a longitudinal direction.   The said 1st elastic member has urging | biasing force in a longitudinal direction, and the said sensor contact part makes the said image sensor contact | abut in a longitudinal direction by the said 1st elastic member. Image reading device.   The first elastic member has a biasing force in a direction perpendicular to the longitudinal direction, and the sensor abutting portion abuts the image sensor in a direction perpendicular to the longitudinal direction by the first elastic member, and light The image reading apparatus according to claim 3, further comprising: a second elastic member having an urging force in the axial direction, wherein the second elastic member makes contact with the second elastic member in the optical axis direction.   The fastening member is a screw, the holding member is provided with a screw hole, the circuit board is provided with a long hole extending in a longitudinal direction, and the screw is inserted into the long hole and the screw hole via the holding elastic member. The image reading apparatus according to claim 2, wherein the image reading apparatus is mounted.   The holding member, the screw, and the holding elastic member are made of a conductive member, and a ground portion formed by a circuit pattern is provided around the elongated hole on the circuit board. The image reading apparatus according to claim 5.   An image forming apparatus on which the image reading apparatus according to claim 1 is mounted.

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