Image reading device and image forming device

Abstract

To prevent a movement of an optical scanning unit from being hindered by a step generated between a contact glass for a stationary document and a contact glass for a moving document, and prevent the occurrence of damage to a component and out-of-step due to overload caused by an impact of collision with the step.SOLUTION: In an image reading device, an operation reading unit comprises a contact glass for a stationary document 7, a contact glass for a moving document 104, and an optical scanning unit 40. The optical scanning unit 40 has a close-contact image sensor 200, a carriage 201 that holds the image sensor 200 movably in a sub scanning direction, a pair of end slide members that are disposed at both ends in a longitudinal direction of a surface opposite to a reading surface, and a pair of center slide members 203 that are disposed at both ends in a moving direction across the image sensor at the center side in the longitudinal direction. When the optical scanning unit 40 is at a home position before the start of scanning, any one of the center slide members 203 is at a position overlapping the contact glass for the stationary document 7 when seen in the vertical direction.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to an image reading device and an image forming device. [Background technology]

[0002] There are known image reading devices that are switchable between a transported document reading mode, in which an image of a document is read while the document is automatically transported, and a placed document reading mode, in which an image of a document placed on a flat contact glass is read from below. Such image reading devices include those that are used as standalone image reading devices and those that are installed in image forming devices such as facsimiles, copiers, or multifunction devices that combine printer and scanner functions.

[0003] One image reading method uses a contact image sensor (hereinafter referred to as "CIS"), which has a shallow focal depth and therefore requires accurate positioning relative to the contact glass, which is the document reading surface. A known configuration for positioning a CIS is to pressurize both ends of an optical scanning unit equipped with a CIS upward with a pressing member such as a spring, and the optical scanning unit is brought into contact with the underside of the contact glass via an abutment member (also called a sliding member (slide shoe)) (see, for example, Patent Document 1).

[0004] There is a clearance between the contact glass and the CIS in areas other than where it makes contact with the contact glass. This can cause the contact glass to bend when a user tries to scan a thick or heavy document. This is especially true when the contact glass is wide, such as in devices that can handle A3 paper. If the amount of bending becomes too great, the document will move outside the effective focal range of the CIS, resulting in a decrease in image quality.

[0005] To address this problem, Patent Document 1 discloses a technology in which a member that contacts the contact glass is also arranged within (inside) the main scanning reading range, thereby reducing deflection and maintaining the CIS within the effective focal range throughout the entire reading range. Summary of the Invention [Problem to be solved by the invention]

[0006] In such an image reading device, when the contact glass for the stationary document is bent due to the weight of the document placed on it, a step is created between the contact glass for the moving document and the contact glass for the stationary document, which is not bent.

[0007] In a configuration in which a sliding member is provided at the center of the optical scanning unit, as in Patent Document 1, if there is a step between the two contact glasses, the sliding member or the housing may collide with the step when the optical scanning unit is moved, which may result in damage to parts, loss of synchronization due to overload on the conveying motor, a decrease in MTF (Modulation Transfer Function), etc.

[0008] Therefore, the present invention aims to provide an image reading device in which the step between the contact glass for a stationary document and the contact glass for a moving document does not hinder the movement of the optical scanning unit, and which can prevent damage to parts due to impact from colliding with the step or loss of synchronization due to overload. [Means for solving the problem]

[0009] In order to solve the above problem, the image reading device of the present invention comprises a contact glass for a stationary document which is a reading surface for a document placed on it, a contact glass for a moving document which is a reading surface for a document transported by an automatic document transport unit, and an optical scanning unit which moves back and forth in the sub-scanning direction in the reading area of ​​the contact glass for the stationary document to read the document, and during automatic document transport, moves to the reading area of ​​the contact glass for the moving document and reads the document in a fixed state, the optical scanning unit having a contact type image sensor, a carriage which holds the image sensor movably in the sub-scanning direction, a pair of end sliding members arranged at both ends in the longitudinal direction of a surface facing the reading surface, and a pair of central sliding members arranged on both sides in the moving direction via the image sensor at the center in the longitudinal direction, and when the optical scanning unit is in a home position before starting scanning, One of the pair of central sliding members located on the stationary document contact glass side is When viewed vertically, the stationary document contact glass and the contact glass for the moving document. It is characterized in that it is located at a position overlapping with [Effects of the Invention]

[0010] According to the present invention, an image reading device can be provided in which the step between the contact glass for a stationary document and the contact glass for a moving document does not hinder the movement of the optical scanning unit, and which can prevent damage to parts due to impact from colliding with the step or loss of synchronization due to overload. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic diagram illustrating an example of a color copying machine as an image forming apparatus according to an embodiment of the present invention. [Figure 2] 2 is a perspective view showing a schematic configuration of a scanning and reading unit that constitutes the color copying machine of FIG. 1, as an example of an image reading apparatus according to an embodiment of the present invention. FIG. [Figure 3] FIG. 2 is a schematic diagram showing an example of an optical scanning unit 40. [Figure 4] 1A is a perspective view showing an example of a central sliding member, and FIG. 1B is a side view showing the same; [Figure 5]10A and 10B are explanatory diagrams showing an example of a mode in which a central sliding member is attached to an optical scanning unit. [Figure 6] 10 is a diagram illustrating the horizontal separation distance between the end of the image sensor and the end of the stationary document contact glass. FIG. [Figure 7] FIG. 3 is a cross-sectional view taken along line XX in FIG. 2. [Figure 8] 8A and 8B are enlarged views of a portion of FIG. 7, in which FIG. 8A is an explanatory view showing a state where there is no step on the reading surface, and FIG. 8B is an explanatory view showing a state where there is a step on the reading surface. DETAILED DESCRIPTION OF THE INVENTION

[0012] The image reading device and image forming device of the present invention will be described below with reference to the drawings. Note that the present invention is not limited to the following embodiments, and other modifications, additions, corrections, deletions, and other changes can be made within the scope of what a person skilled in the art can conceive. Any aspect that achieves the functions and effects of the present invention is included in the scope of the present invention.

[0013] [Image forming apparatus] Fig. 1 is a schematic diagram showing an example of a color copier 1 as an image forming apparatus according to an embodiment of the present invention. Fig. 2 is a schematic perspective view of a scanning and reading unit 4 constituting the color copier 1 of Fig. 1, which is an example of an image reading apparatus according to the present invention. In FIG. 1, the color copier 1 of this embodiment is configured to include an automatic document feeder (hereinafter also referred to as "ADF") 2, a paper feeder 3, a scanning and reading unit 4 as an image reading device according to the present invention, and an image forming unit 5.

[0014] The ADF2 includes a first document tray 11 and a paper feed section 13 consisting of various rollers, etc., which separates documents one by one from a stack of documents placed on the first document tray 11 and transports them toward a moving document contact glass (hereinafter also referred to as the "DF contact glass") 104. The ADF 2 is equipped with a paper discharge section 9 consisting of various rollers, etc., and when the document on the DF contact glass 104 is read by the optical scanning unit 40 of the scanning reading section 4, the document is discharged to a paper discharge tray 12 by the paper discharge section 9.

[0015] The ADF 2 is attached to the scanning and reading unit 4 via an opening and closing mechanism such as a hinge so as to be able to open and close freely. The ADF2 also functions as a document pressing section that presses and fixes a document against the stationary document contact glass 7 (hereinafter also referred to as the "FB contact glass") when the optical scanning unit 40 moves in the scanning direction (sub-scanning direction) indicated by arrow B in Figure 1 to read a document placed on the FB contact glass 7. The FB contact glass 7 is provided on the upper part of the housing 4a of the scanning and reading unit 4, and forms the upper surface of the housing 4a.

[0016] 2, the scanning and reading unit 4 includes an optical scanning unit 40 as an image reading unit in a housing 4a. The optical scanning unit 40 holds a light source and a contact image sensor (hereinafter also referred to as "CIS") 200 whose longitudinal direction (direction of arrow A) is the main scanning direction. The optical scanning unit 40 is moved back and forth in the sub-scanning direction (direction of arrow B) by a driving means provided in the scanning reading section 4, thereby reading a two-dimensional color image of a document placed on the FB contact glass 7. The FB contact glass 7 is provided on the upper part of the housing 4a of the scanning and reading unit 4, and forms the upper surface of the housing 4a.

[0017] The driving means is composed of a wire fixed to the optical scanning unit 40, a plurality of driven pulleys and a driving pulley bridged by the wire, and a motor that rotates the driving pulley, and any known means can be used.

[0018] The paper feed unit 3 includes paper feed cassettes 21 and 22 that store recording paper as recording media of different paper sizes, and a paper feed means 23 consisting of various rollers that transport the recording paper stored in the paper feed cassettes 21 and 22 to the image forming position of the image forming unit 5.

[0019] The image forming unit 5 constitutes an image forming means and includes an exposure device 31, a plurality of photosensitive drums 32, developing devices 33 having toner of different colors disposed around each photosensitive drum 32, a transfer belt 34, and a fixing device 35. The colors of toner stored in each developing device 33 are cyan (C), yellow (Y), magenta (M), black (Bk), etc.

[0020] The image forming section 5 forms images in different colors on a plurality of photosensitive drums 32 based on image information read by the optical scanning unit 40 of the scanning and reading section 4 and separated by color, and performs primary transfer by overlapping the toner on the photosensitive drums 32 onto the transfer belt 34. Then, the toner on the transfer belt 34 is secondarily transferred onto the recording paper supplied from the paper feed section 3. Thereafter, the toner of the toner image transferred onto the recording paper is melted by the fixing device 35, thereby fixing the color image onto the recording paper.

[0021] Furthermore, the color copier 1 may have a function of transmitting an image read by an image transmitting / receiving device to a destination device.

[0022] [Image reading device] An image reading apparatus according to an embodiment of the present invention will now be described. As shown in Figure 2, the image reading device 4 of this embodiment is equipped with a contact glass for stationary documents (FB contact glass) 7, which is the reading surface for documents placed on it, a contact glass for moving documents (DF contact glass) 104, which is the reading surface for documents transported by an automatic document feeder (ADF), and an optical scanning unit 40 that moves back and forth in the sub-scanning direction in the reading area of ​​the contact glass for stationary documents 7 to read the document, and during automatic document transport, moves to the reading area of ​​the contact glass for moving documents 104 and reads the document in a fixed state.

[0023] FIG. 3 is a schematic diagram showing an example of the optical scanning unit 40. As shown in FIG. The optical scanning unit 40 has a contact-type image sensor (CIS) 200, a carriage 201 that holds the image sensor 200 so that it can move in the sub-scanning direction, a pair of end sliding members 202 arranged at both ends of the longitudinal direction of the surface facing the reading surface, and a pair of central sliding members 203 arranged on both sides of the movement direction (direction of arrow B in the figure) via the image sensor 200 at the center of the longitudinal direction.

[0024] The optical scanning unit 40 is pressed against the contact glass, which is the reading surface, by a spring (not shown) attached to the carriage 201. When the end sliding member (end slide shoe) 202 abuts against the contact glass, accurate positioning of the image sensor 200 and smooth scanning operation become possible. Furthermore, a central sliding member (central slide shoe) 203 provides a certain clearance between the contact glass. Although not shown, the mechanism for moving the carriage 201 includes a guide rod, a bearing that fits with the guide rod, a timing belt that transmits drive from a drive source (motor), and the like.

[0025] An example of a central sliding member is shown in Fig. 4. Fig. 4(A) is a perspective view, Fig. 4(B) and Fig. 4(D) are front and rear side views of the optical scanning unit 40 in the short direction when attached, and Fig. 4(C) is a side view of the optical scanning unit 40 in the long direction when attached. FIG. 5 shows an example of a mode in which the central sliding member is attached to the optical scanning unit.

[0026] As shown in FIG. 4C, the surface of the central sliding member 203 that faces the reading surface (contact glass) is inclined downward with respect to the horizontal plane as it approaches the outside of the optical scanning unit 40. In the following description, this surface will be referred to as the "inclined surface 301."

[0027] 5(A), the image sensor 200 of the optical scanning unit 40 has a hole 306 and a notch 307 at the attachment position of the central sliding member 203. The central sliding member 203 also has a boss 302 that fits into the hole 306 and a claw-like portion 303 that engages with the notch 307, as shown in FIG. 5B shows the attached state of the central sliding member 203. The central sliding member 203 is positioned and fixed in the horizontal direction relative to the optical scanning unit 40 by the boss 302 and the claw-like portion 303.

[0028] The central sliding member 203 also has an extension 304 that extends outward from the carriage 201 and is bent downward at the extension end, with the bent inner surface coming into contact with the outer surface of a frame 308 of the carriage 201 . 5(B), the central sliding member 203 is attached so as to be displaceable in the up and down direction. For example, when pressure is applied to the surface (inclined surface 301) facing the reading surface (contact glass), the central sliding member 203 can be displaced in the direction of the pressure. The carriage 201 has a convex portion 309 on the outer surface of the frame, and the extension portion 304 of the central sliding member 203 has a groove portion 305 that slidably engages with the convex portion 309 .

[0029] 6 to 8 show a schematic diagram of the optical scanning unit 40 in a state where it is in a home position before starting scanning. In the image reading device of this embodiment, when the optical scanning unit 40 is in the home position before scanning starts, one of the central sliding members 203 is positioned so as to overlap the stationary document contact glass 7 when viewed vertically. That is, when the optical scanning unit 40 is at the home position, at least a part of the surface of the central sliding member 203 that faces the reading surface is recessed inside the edge of the contact glass 7 for stationary documents. Furthermore, when the optical scanning unit 40 is in the home position before scanning begins, it is preferable that one of the pair of central sliding members 203 located on the side of the contact glass for stationary documents is positioned so as to overlap both the contact glass for stationary documents 7 and the contact glass for moving documents 104 when viewed vertically.

[0030] The image reading device of this embodiment has a significant advantage, particularly when the area where a step may occur between the end of the stationary document contact glass 7 and the end of the moving document contact glass 104 is within the acceleration area caused by the drive source that drives the optical scanning unit 40. This prevents the accelerating optical scanning unit from colliding with the step and receiving an impact after starting to move, and prevents damage to parts and loss of synchronization due to overload.

[0031] FIG. 6 is a diagram illustrating the horizontal separation distance L between the end of the image sensor 200 and the end of the stationary document contact glass 7. As shown in FIG. In this embodiment, when the optical scanning unit 40 is in the home position before scanning begins, it is preferable that the horizontal separation distance L between the end of the image sensor 200 on the front side of the scanning direction and the end 7a of the contact glass 7 for stationary documents is shorter than the total horizontal length of the surface (inclined surface 301) facing the reading surface of the central sliding member 203.

[0032] If the distance L between the end of the image sensor 200 and the end of the contact glass 7 for stationary documents is relatively large, and the inclined surface 301 of the central sliding member 203 is positioned so that it extends all the way to the bottom of the contact glass 7 for stationary documents, the end 7a of the contact glass 7 for stationary documents, which has been displaced downward due to bending, will come into contact with the end 311 of the inclined surface 301, and the position of the image sensor 200 may become unstable due to the influence of the moment. Furthermore, if the inclined surface 301 of the central sliding member 203 is made long enough to extend beyond the end 7a of the stationary document contact glass 7 and into the bottom of the stationary document contact glass 7, stability may not be achieved unless an extension portion 304 is provided as shown in Figure 6.

[0033] Therefore, as shown in Figures 4 and 5, the central sliding member 203 is configured to be positioned and fixed horizontally relative to the optical scanning unit 40 by a boss 302 and a claw-shaped portion 303, and is supported by the carriage 201 by an extension portion 304.Furthermore, by having a groove-shaped portion 305 that slidably engages with a convex portion 309 provided on the carriage 201, the central sliding member 203 can be displaced in the vertical direction, thereby stably maintaining the posture of the attached image sensor 200.

[0034] Fig. 7 is a cross-sectional view taken along line XX in Fig. 2, showing the reading surface and the optical scanning unit 40. Fig. 8 is a partially enlarged view of Fig. 7, where Fig. 8(A) is an explanatory diagram showing a state where there is no step on the reading surface, and Fig. 8(B) is an explanatory diagram showing a state where there is a step on the reading surface.

[0035] FIG. 2 is a schematic diagram of the scanning and reading unit 4 constituting the image forming apparatus of FIG. 1, which is an image reading apparatus of this embodiment. 2, in the image reading device of this embodiment, the contact glass 7 for stationary documents and the contact glass 104 for moving documents are attached to a resin frame 204. There are no particular limitations on the attachment method, and examples include a method of attaching them using double-sided tape. Because the contact glass 7 for stationary documents and the contact glass 104 for moving documents are independent members, a step is likely to occur between their ends in the sub-scanning direction.

[0036] As shown in Figure 8(A), when there is no bending in the contact glass 7 for stationary documents, there is a clearance 206 between the inclined surface 301 of the central sliding member 203 and the contact glass 7 for stationary documents, and the inclined surface 301 and the contact glass 7 for stationary documents are not in contact.

[0037] 8(B), when a heavy document is placed on the contact glass 7 for stationary documents or when the user presses the document, the contact glass 7 for stationary documents bends and its end portion is displaced downward. This causes the inclined surface 301 of the central sliding member 203 to come into contact with the end portion of the contact glass 7 for stationary documents. When the inclined surface 301 of the central sliding member 203 is pressed by the contact glass 7 for stationary documents, the central sliding member 203 is displaced downward, in the direction of the pressure.

[0038] As described above, with the configuration shown in Figures 4 and 5, the central sliding member 203 is supported by both the image sensor 200 and the carriage 201, and is therefore capable of vertical displacement while maintaining its horizontal position. Therefore, even if the optical scanning unit 40 comes into contact with the edge of the stationary document contact glass 7, which is bent and has a step, when it moves, it can slide through smoothly, so movement is not hindered even within the acceleration range of the drive source, preventing damage to parts due to the impact of a collision and loss of synchronization due to an overload on the motor. Also, by providing the central sliding member 203, it is possible to prevent a significant shift in focus due to a change in the distance between the stationary document contact glass 7 and the image sensor 200, and it is also possible to prevent a decrease in MFT (contrast reproducibility).

[0039] Although the example has been described in which the surface of the central sliding member 203 facing the stationary document contact glass 7 is the inclined surface 301, the present invention is not limited to this, and the facing surface may be flat. [Explanation of symbols]

[0040] 1. Image forming device 2 ADF 4. Image reading device (scanning unit) 7. Contact glass for stationary documents 40 Optical scanning unit 104 Contact glass for moving originals 200 image sensors 201 Carriage 202 End sliding member 203 Central sliding member 301 Slope [Prior art documents] [Patent documents]

[0041] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-143377

Claims

1. a contact glass for a stationary document that is a reading surface for a document to be placed on the contact glass; a moving document contact glass that is a reading surface for a document transported by an automatic document transport unit; an optical scanning unit that reads an original by reciprocating in a sub-scanning direction in a reading area of ​​the stationary original contact glass, and that moves to the reading area of ​​the movable original contact glass and reads the original in a fixed state during automatic original transport; the optical scanning unit includes a contact-type image sensor, a carriage that holds the image sensor movably in a sub-scanning direction, a pair of end sliding members disposed at both ends in the longitudinal direction of a surface that faces the reading surface, and a pair of center sliding members disposed on both sides in the movement direction via the image sensor at a center side in the longitudinal direction; An image reading device characterized in that, when the optical scanning unit is in a home position before scanning begins, one of the pair of central sliding members located on the side of the stationary document contact glass is in a position overlapping both the stationary document contact glass and the moving document contact glass when viewed vertically.

2. A contact glass for a stationary document that is a reading surface for a document to be placed on it; a moving document contact glass that is a reading surface for a document transported by an automatic document transport unit; an optical scanning unit that reads an original by reciprocating in a sub-scanning direction in a reading area of ​​the stationary original contact glass, and that moves to the reading area of ​​the movable original contact glass and reads the original in a fixed state during automatic original transport; the optical scanning unit includes a contact-type image sensor, a carriage that holds the image sensor movably in a sub-scanning direction, a pair of end sliding members disposed at both ends in the longitudinal direction of a surface that faces the reading surface, and a pair of center sliding members disposed on both sides in the movement direction via the image sensor at a center side in the longitudinal direction; An image reading device characterized in that, when the optical scanning unit is in a home position before scanning begins, one of the central sliding members is positioned so as to overlap the stationary document contact glass when viewed vertically, and the horizontal distance between the end of the image sensor on the front side of the scanning direction and the end of the stationary document contact glass is shorter than the total horizontal length of the surface of the central sliding member facing the reading surface.

3. 2. The image reading device according to claim 1, wherein when the optical scanning unit is in a home position before scanning starts, the horizontal separation distance between the end of the image sensor on the front side in the scanning direction and the end of the stationary document contact glass is shorter than the total horizontal length of the surface of the central sliding member facing the reading surface.

4. 4. The image reading device according to claim 1, wherein the surface of the central sliding member facing the reading surface is inclined downward with respect to a horizontal plane as it approaches the outside of the optical scanning unit.

5. the image sensor has a hole and a notch at a mounting position of the central sliding member; the central sliding member has a boss that fits into the hole and a claw-shaped portion that engages with the notch, 5. The image reading device according to claim 1, wherein the central sliding member is positioned and fixed horizontally relative to the optical scanning unit by the boss and the claw-like portion.

6. 6. The image reading device according to claim 1, wherein the central sliding member is displaceable in the direction of pressure when a pressure is applied to a surface facing the reading surface.

7. 7. An image reading device according to claim 1, wherein the central sliding member has an extension portion that extends outside the carriage and is bent downward at the extension end, with the bent inner surface abutting against the outer surface of the frame of the carriage.

8. 8. The image reading device according to claim 7, wherein the carriage has a convex portion on an outer surface of a frame, and the extension of the central sliding member has a groove portion that slidably engages with the convex portion.

9. An image reading device as described in any one of claims 1 to 8, characterized in that the area where a step may occur between the end of the contact glass for a stationary document and the end of the contact glass for a moving document is within an acceleration area caused by a drive source that scans the optical scanning unit.

10. An image forming apparatus comprising the image reading device according to any one of claims 1 to 9.

Images