Image reading device and image forming apparatus

Abstract

To provide an image reading device that prevents rotation of a bearing member relative to a holding member that holds a reading unit to improve image reading accuracy, and an image forming apparatus.SOLUTION: An image reading device 101 comprises: a document platen glass 301; a reading unit 401; a shaft 400; a holder 402 that has a hole part 402a formed therein and holds the reading unit 401; and a bearing member 403 that has a hole part 403a formed therein and is attached to the holder 402. The image reading device 101 further comprises: a screw 407 that fixes the bearing member 403 to the holder 402; and a sheet metal 406 that has a screw hole part 406a with which the screw 407 is screwed formed therein. With the holder 402 being sandwiched by the sheet metal 406 and the bearing member 403, the screw 407 inserted into the hole part 402a and the hole part 403a is screwed with the screw hole part 406a, and thereby the bearing member 403 is fixed to the holder 402.SELECTED DRAWING: Figure 8

Description

Technical Field

[0001] The present invention relates to an image reading device that reads an image of a sheet and an image forming device including the same.

Background Art

[0002] Conventionally, image forming devices such as copiers, facsimile machines, and multifunction devices are provided with an image reading device that reads an image of a document. Such an image reading device is known to read an image of a document placed on a contact glass while an image sensor held by a holding member moves along a guide member (shaft) extending in the sub-scanning direction (Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, a bearing member that fits and slides on a shaft is assembled to a holding member that holds an image sensor. Here, when the bearing member is attached to the holding member, the bearing member may be fixed in a rotated state with respect to the holding member due to the torque generated when tightening the screw. In such a case, there is a problem that the image sensor is held obliquely with respect to the moving direction, and the image reading accuracy deteriorates.

[0005] Therefore, an object of the present invention is to provide an image reading device and an image forming device capable of improving image reading accuracy by suppressing rotation of a bearing member with respect to a holding member.

Means for Solving the Problems

[0006] In order to solve the above problems, one aspect of the present invention includes a transparent member on which a sheet is placed, a reading unit having light receiving elements arranged in the main scanning direction and configured to read an image of the sheet placed on the transparent member, a shaft member extending in the sub-scanning direction, a holding member having a first hole and configured to movably hold the reading unit along the shaft member, a bearing member having a second hole, attached to the holding member, and configured to slide on the shaft member, a screw for fixing the bearing member to the holding member, and a sheet metal having a screw hole into which the screw is screwed. With the holding member sandwiched between the sheet metal and the bearing member, the bearing member is fixed to the holding member by screwing the screw inserted into the first hole and the second hole into the screw hole. An image reading apparatus characterized by the above is provided.

Advantages of the Invention

[0007] According to the present invention, it is possible to provide an image reading apparatus and an image forming apparatus capable of improving the reading accuracy of an image by suppressing rotation of the bearing member with respect to the holding member.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

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Figure 10

Best Mode for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, the following embodiments are merely examples of embodying the present invention and do not limit the technical scope of the present invention.

[0010] <Regarding the Image Forming Apparatus> First, the image forming apparatus 100 according to the present embodiment will be described with reference to FIG. 1. FIG. 1 is a schematic cross-sectional view of the image forming apparatus 100 as seen from the front.

[0011] As shown in FIG. 1, the image forming apparatus 100 includes an image forming apparatus main body 104 and an image reading apparatus 101 provided above the image forming apparatus main body 104. The image forming apparatus 100 forms a toner image on a sheet P in accordance with the image data read by the image reading apparatus 101 or an image signal from a host device such as a personal computer communicably connected to the image forming apparatus 100. Examples of the sheet P as a recording medium include sheet materials such as plain paper, plastic film, and cloth.

[0012] Inside the image forming apparatus main body 104, there are provided four laser scanners 107 to 110 corresponding to YMCK colors, which are image forming units using the electrophotographic method, four image forming units 111 to 114, and a fixing unit 118. The laser scanners 107 to 110 irradiate a laser toward the photoreceptors of the corresponding image forming units 111 to 114 in accordance with the input image signal. These image forming units 111 to 114 are arranged along the intermediate transfer belt 115.

[0013] In the image forming unit 111, a yellow toner image is formed, and the formed yellow toner image is primarily transferred to the intermediate transfer belt 115. In the image forming unit 112, a magenta toner image is formed, and the formed magenta toner image is primarily transferred onto the yellow toner image being transferred to the intermediate transfer belt 115 in an overlapping manner. In the image forming unit 113, a cyan toner image is formed, and the formed cyan toner image is primarily transferred onto the yellow and magenta toner images being transferred to the intermediate transfer belt 115 in an overlapping manner. In the image forming unit 114, a black toner image is formed, and the formed black toner image is primarily transferred onto the yellow, magenta, and cyan toner images being transferred to the intermediate transfer belt 115 in an overlapping manner.

[0014] A paper feed cassette 105 is arranged at the lower part of the main body 104 of the image forming apparatus so as to be pullable forward. The image forming apparatus 100 feeds the paper P accommodated in the paper feed cassette 105 by a pickup roller 106 toward a secondary transfer nip portion where the intermediate transfer belt 115 and the secondary transfer unit 116 are in contact with each other. When transporting the paper P, the image forming apparatus 100 transports the paper P in synchronization with the toner image on the intermediate transfer belt 115. Then, the multi-color toner image on the intermediate transfer belt 115 is transferred onto the paper P by the action of a secondary transfer bias voltage applied to the secondary transfer unit 116 at the secondary transfer nip portion.

[0015] The paper P onto which the toner image has been secondarily transferred by the secondary transfer unit 116 is transported to a fixing unit 118 by a transport belt 117. Then, the paper P is heated and pressed by the fixing unit 118 so that the toner image is fixed, and after the toner image is fixed on the surface, it is discharged to a paper discharge tray 119.

[0016] In this embodiment, the image forming apparatus 100 includes electrophotographic image forming means, but the image forming means is not limited to this, and other image forming means such as an inkjet method may be used.

[0017] <Regarding the image reading device> Next, the image reading apparatus 101 will be described. FIG. 2 is a perspective view of the image reading apparatus 101. FIG. 3 is a perspective view of the reader 103. FIG. 4 is a perspective view showing the internal configuration of the reader 103. FIG. 5 is a perspective view of the reading unit 401 and the shaft 400. FIG. 6 is a perspective view of the reading unit 401.

[0018] As shown in FIG. 2, the image reading apparatus 101 includes an automatic document feeder (hereinafter referred to as ADF) 102 and a reader 103. Such an image reading apparatus 101 is capable of performing a continuous reading in which the image of a document is read while the document is being conveyed by the ADF 102, and a fixed reading in which the image of a document placed on the reader 103 is read. Here, the document is a sheet on which an image is read by the image reading apparatus 101.

[0019] As shown in FIG. 2, the ADF 102 includes a document tray 200 (loading tray) on which documents are loaded, a conveying unit 202 that conveys the documents, and a discharge tray 201 from which the documents whose images have been read are discharged. The conveying unit 202 includes a plurality of rollers such as a pickup roller that feeds the documents loaded on the document tray 200, a separation roller that separates the documents one by one, and a conveying roller that conveys the separated documents. In the case of continuous reading, the documents set on the document tray 200 are conveyed by the conveying unit 202 and the image is read by the reading unit 401 described later, and then discharged to the discharge tray 201. Note that the ADF 102 may have a reading unit different from the reading unit 401 inside, and the reading unit 401 reads the image on the front surface of the document, and the ADF 102 may be configured such that another reading unit provided inside reads the image on the back surface of the document.

[0020] As shown in FIG. 3, the reader 103 has a transparent platen glass 301, a transparent jogging glass 302, and a cover 303 which is the exterior of the reader 103. The platen glass 301 is an example of a transparent member on which the document is placed. Further, as shown in FIG. 4, the reader 103 has a shaft 400, a reading unit 401, a holder 402, a bearing member 403, a motor 404, a timing belt 405, and a cable 408. Each of the above-described members provided in the reader 103 is housed in a frame 409, and the upper part of the frame 409 is covered by the platen glass 301, the jogging glass 302, and the cover 303. Note that the frame 409 may be made of resin or metal.

[0021] The reading unit 401 is a contact image sensor (hereinafter referred to as CIS), which is a scanning device for an equal magnification optical system. As shown in FIG. 6, the reading unit 401 includes a lens 600, a light source 601 composed of an LED array arranged in the main scanning direction, a plurality of light receiving elements arranged in the main scanning direction, and a case 602 that houses these. The reflected light emitted from the light source 601 and reflected by the document is imaged on each light receiving element via the lens 600 and is photoelectrically converted by the light receiving elements. The image data of the document read by the reading unit 401 is sent to a control board (not shown) via the cable 408. A plurality of protrusions 603 are formed on both end portions in the longitudinal direction and the side surfaces in the sub-scanning direction of the case 602. By engaging these protrusions 603 with a plurality of groove portions 604 formed in the holder 402, the reading unit 401 is positioned in the holder 402.

[0022] The shaft 400 is a metal shaft member extending in the sub-scanning direction orthogonal to the main scanning direction. Both ends of the shaft 400 in the axial direction (sub-scanning direction) are supported by the frame 409. The holder 402 holds the reading unit 401 movably along the shaft 400 in the axial direction (sub-scanning direction). The holder 402 is composed of a first wall portion 605 and a second wall portion 606 facing the case 602 of the reading unit 401 in the sub-scanning direction, and a bottom surface 607 facing the case 602 in the vertical direction (see Fig. 9). A bearing member 403 that fits and slides on the shaft 400 is attached to the lower surface of the bottom surface 607 of the holder 402. Although details will be described later, the bearing member 403 is fixed to the holder 402 by a sheet metal 406 and a plurality of screws 407. A bearing groove 403b into which the shaft 400 fits is formed in the bearing member 403 so as to extend in the sub-scanning direction (see Fig. 10). In the present embodiment, the holder 402 and the bearing member 403 are formed of a resin material.

[0023] As shown in Fig. 4, a motor 404 is disposed on one side of the reader 103 in the sub-scanning direction. A drive pulley 404a is provided on the motor shaft of the motor 404, and a driven pulley 404b is provided on the side of the reader 103 opposite to the motor 404 in the sub-scanning direction. A timing belt 405 is attached to the drive pulley 404a and the driven pulley 404b so as to extend along the shaft 400, and the timing belt 405 can be rotated by the motor 404. A belt clamping portion 403c for clamping the timing belt 405 is formed in the bearing member 403 (see Fig. 10). The belt clamping portion 403c sandwiches the timing belt 405 between two opposing surfaces with unevenness formed thereon. Thereby, the holder 402 and the reading unit 401 can be moved in the sub-scanning direction as the timing belt 405 rotates.

[0024] At both ends of the reading unit 401 in the main scanning direction, sliding members 410 that slide on the platen glass 301 are provided. The reading unit 401 is biased toward the platen glass 301 by a spring (not shown) disposed between the reading unit 401 and the holder 402. Therefore, when the reading unit 401 moves in the sub-scanning direction along the shaft 400, the sliding member 410 slides on the lower surface of the platen glass 301.

[0025] In this way, the image reading apparatus 101 can read an image of a document placed on the platen glass 301 while the reading unit 401 moves in the sub-scanning direction along the shaft 400. Here, the ADF 102 is rotatably provided with respect to the reader 103 by a hinge (not shown). The ADF 102 functions as a pressing portion that presses the document placed on the platen glass 301 so as not to move when in a closed state with respect to the reader 103.

[0026] <Attachment of the bearing member> Next, the attachment of the bearing member 403 to the holder 402 will be described. FIG. 7 is a perspective view of an assembly jig 700 for attaching the bearing member 403 to the holder 402. FIG. 8 is a cross-sectional view showing a fastening portion of the holder 402 and the bearing member 403. FIG. 9 is a perspective view showing a fastening portion of the holder 402 and the bearing member 403. FIG. 10 is a perspective view of the bearing member 403.

[0027] As shown in FIG. 9, on the surface (the upper surface of the bottom surface 607) of the holder 402 opposite to the bearing member 403, a sheet metal 406 for fixing the bearing member 403 to the holder 402 is arranged. The sheet metal 406 is a metal plate-like member in which screw hole portions 406a into which screws 407 are screwed are formed at three locations. The screw 407 is a screw having a head portion 407a and a screw portion 407b. Three hole portions 403a into which the screw 407 is inserted are formed in the bearing member 403. Further, three hole portions 402a into which the screw 407 is inserted are formed in the holder 402 at three positions corresponding to the hole portions 403a of the bearing member 403. The hole portion 402a formed in the holder 402 is an example of a first hole portion, and the hole portion 403a formed in the bearing member 403 is an example of a second hole portion. As shown in FIG. 8, with the bottom surface 607 of the holder 402 sandwiched between the sheet metal 406 and the bearing member 403, the screw 407 inserted into the hole portion 402a and the hole portion 403a is screwed into the screw hole portion 406a, whereby the bearing member 403 is fixed to the holder 402. Here, screwing means that the screw is inserted while rotating so as to be in a state of meshing with the screw hole.

[0028] The hole portion 402a of the holder 402 and the hole portion 403a of the bearing member 403 are larger than the outer shape of the screw 407 and have a gap with the screw portion 407b of the screw 407 in a state where the screw 407 is inserted. That is, the hole portion 402a of the holder 402 and the hole portion 403a of the bearing member 403 are formed with a larger hole diameter than the screw hole portion 406a of the sheet metal 406.

[0029] On the surface (the upper surface of the bottom surface 607) where the sheet metal 406 of the holder 402 is disposed, a protruding portion 402b protruding toward the sheet metal 406 is formed. Further, on the surface of the bearing member 403 that abuts against the holder 402, a protruding portion 403d protruding toward the holder 402 is formed. The protruding portion 403d of the bearing member 403 is an example of a first protruding portion, and the protruding portion 402b of the holder 402 is an example of a second protruding portion. In the holder 402, a through hole 402c is formed separately from the three hole portions 402a. In the sheet metal 406, a through hole 406b and a through hole 406c are formed separately from the three screw hole portions 406a. The through hole 402c formed in the holder 402 is an example of a third hole portion. Further, the through hole 406c formed in the sheet metal 406 is an example of a fourth hole portion, and the through hole 406b is an example of a fifth hole portion. Before the bearing member 403 is fastened to the holder 402, the protruding portion 402b is inserted into the through hole 406b, and the protruding portion 403d is inserted into the through holes 402c and 406c, whereby the bearing member 403 and the holder 402 can be temporarily assembled. In the temporarily assembled state, the bearing member 403 can rotate about the protruding portion 403d with respect to the holder 402. With such a configuration, it is possible to adjust the angle of the bearing member 403 with respect to the holder 402 in the temporarily assembled state and fix the bearing member 403.

[0030] The assembly jig 700 shown in FIG. 7 can hold the temporarily assembled holder 402 and bearing member 403 at an arbitrary angle. Incidentally, in the manufacturing process of the reading unit 401, the reading area (main scanning direction) of the reading unit 401 may be slightly inclined with respect to the longitudinal direction of the case 602. That is, the relationship between the reading area of the reading unit 401 and the case 602 varies from one individual to another. Therefore, it is necessary to adjust the angle of the bearing member 403 with respect to the holder 402 according to the angle between the reading area of the reading unit 401 and the longitudinal direction of the case 602.

[0031] First, the operator measures in advance the angular variation of the reading area of the reading unit 401 with respect to the case 602 using a measuring instrument. Then, the holder 402 and the bearing member 403 are held at an angle corresponding to the individual reading unit 401 by the assembly jig 700. Thereafter, the holder 402 and the bearing member 403 are fixed by sandwiching them between the head 407a of the screw 407 and the mounting sheet metal 406. Thereby, it is possible to assemble the reading area of the reading unit 401 and the axial direction of the shaft 400 to be perpendicular. In order to improve the image reading accuracy, it is required to configure the main scanning direction of the reading unit 401 to be perpendicular to the axial direction of the shaft 400. In particular, in models corresponding to originals of A3 (the length in the main scanning direction is 250 mm) or more, since the contribution of this angular error to the image reading accuracy is large, high-precision assembly is emphasized.

[0032] If the bearing member 403 is fixed to the holder 402 without using the sheet metal 406, the screw 407 is configured to be screwed into the screw hole portions formed in the holder 402 and the bearing member 403. In such a case, when the screw 407 is screwed into the screw hole portions formed in the holder 402 and the bearing member 403, the holder 402 and the bearing member 403 rotate relative to each other due to the rotational torque of the screw 407. Therefore, there is a problem that the axial direction of the shaft 400 and the reading area of the reading unit 401 are not perpendicular, and the image reading accuracy decreases.

[0033] On the other hand, in the present embodiment, with the holder 402 sandwiched between the sheet metal 406 and the bearing member 403, the screw 407 inserted into the hole portion 402a and the hole portion 403a is screwed into the screw hole portion 406a, so that the bearing member 403 is fixed to the holder 402. That is, the holder 402 and the bearing member 403 are fixed by being sandwiched between the screw 407 and the sheet metal 406. Thereby, it is possible to suppress the rotation of the bearing member 403 relative to the holder 402 due to the rotational torque of the screw 407, and it is possible to improve the image reading accuracy.

[0034] Furthermore, in the present embodiment, the hole portion 402a of the holder 402 and the hole portion 403a of the bearing member 403 are larger than the outer shape of the screw 407 and have a gap with the screw 407 in a state where the screw 407 is inserted. That is, the hole diameter of the hole portion 402a of the holder 402 and the hole portion 403a of the bearing member 403 is larger than the screw hole portion 406a of the sheet metal 406. Thereby, it is possible to suppress the rotational torque of the screw 407 from being transmitted to the holder 402 and the bearing member 403, and it is possible to further improve the image reading accuracy.

[0035] Furthermore, in the present embodiment, the protruding portion 402b is inserted into the through hole 406b, and the protruding portion 403d is inserted into the through holes 402c and 406c, so that the bearing member 403 and the holder 402 can be temporarily assembled. Therefore, it is possible to adjust the angle of the bearing member 403 with respect to the holder 402 in the temporarily assembled state and then fix the bearing member 403.

Description of Reference Numerals

[0036] 100 Image forming apparatus 101 Image reading apparatus 102 ADF 103 Reader 400 Shaft 401 Reading unit 402 Holder 403 Bearing member 404 Motor 406 Sheet metal 407 Screw

Claims

1. A transparent member on which a sheet is placed, A reading unit having light receiving elements arranged in the main scanning direction, for reading an image of a sheet placed on the transparent member, A shaft member extending in the sub-scanning direction, A holding member having a first hole, for holding the reading unit movably along the shaft member, A bearing member having a second hole, attached to the holding member and sliding on the shaft member, A screw for fixing the bearing member to the holding member, A sheet metal having a screw hole into which the screw is screwed, Comprising, With the holding member sandwiched between the sheet metal and the bearing member, the screw inserted into the first hole and the second hole is screwed into the screw hole, whereby the bearing member is fixed to the holding member, An image reading apparatus characterized by this.

2. The diameter of the first hole and the second hole is larger than that of the screw hole, The image reading apparatus according to claim 1, characterized by this.

3. The bearing member has a first protruding portion protruding from the surface in contact with the holding member, The holding member has a third hole into which the first protruding portion is inserted, The sheet metal has a fourth hole into which the first protruding portion is inserted, The image reading apparatus according to claim 1, characterized by this.

4. The holding member has a second protruding portion protruding from the surface in contact with the sheet metal, The sheet metal has a fifth hole into which the second protruding portion is inserted, The image reading apparatus according to claim 3, characterized by this.

5. The holding member and the bearing member are formed of a resin material, The image reading apparatus according to claim 1, characterized by this.

6. A motor, A belt rotatably provided by the motor, Comprising, The bearing member has a clamping portion for clamping the belt, The reading unit is movable in the sub-scanning direction by the rotation of the belt, The image reading apparatus according to claim 1, characterized by this.

7. Having a pressing portion provided rotatably for pressing a sheet placed on the transparent member, The image reading apparatus according to claim 1, characterized by this.

8. The pressing portion has a stacking tray on which sheets are stacked, a conveying portion for conveying the sheets stacked on the stacking tray, and a discharge tray for discharging the sheets discharged from the conveying portion, The reading unit reads an image of a sheet conveyed by the conveying portion. The image reading apparatus according to claim 7, characterized by the above.

9. An image reading apparatus according to any one of claims 1 to 7, and an image forming unit configured to form an image on a recording medium based on the image read by the reading unit. An image forming apparatus characterized by the above.

Images