Image reading device and image forming device

Abstract

To improve the read image quality by reducing the image shake in the time of reading even in such a structure that scans an image reading unit by using a bearing.SOLUTION: A first fitting part 100 slides by supporting the weights of a bearing part 7 and an image reading unit in line contact with a first guide shaft 67, and has a first contact surface 101 and a second contact surface 102 which are arranged on the mutually-opposite sides with a center line of the first guide shaft 67 held therebetween in the main-scanning direction X. When the minimum angle of the angles formed by the first contact surface 101 and the vertical direction Z is θ1, the force acting in the vertical direction Z on the first guide shaft 67 from the first contact surface 101 with the weights of the bearing part 7 and the image reading unit is F1, and the force acting in the main-scanning direction X on the first guide shaft 67 from the first contact surface 101 with the rotation moment generated in the bearing part 7 when a second timing belt 63 moves the image reading unit is F2, the relationship of F1>F2×tanθ1 is satisfied.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to an image reading device that reads an image formed on a document, and an image forming apparatus that uses the same. [Background technology]

[0002] Image reading devices have been widely used in image forming devices such as copiers, facsimile machines, and multifunction peripherals. One known example of this type of image reading device is one in which an image reading unit movably mounted below the platen glass scans and reads an image on a document placed on the platen glass (see Patent Document 1). This image reading device includes a bearing below the image reading unit, which is slidably attached to a guide shaft mounted on the body of the image reading device, allowing the image reading unit to scan along the guide shaft. The bearing of this image reading device also has a contact surface for sliding against the guide shaft. The contact surface is inclined at approximately 45° with respect to the horizontal. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-274628 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the image reading device described in Patent Document 1, the bearing contact surface is inclined at approximately 45 degrees from the horizontal, which causes the following problem. Specifically, the drive belt (drive unit) connected to move the image reading unit is attached horizontally offset relative to the bearing, which generates a rotational moment in the bearing during movement. This rotational moment urges the bearing contact surface horizontally, and depending on the magnitude of the rotational moment, the bearing may float upward along the contact surface. This creates a problem in that vibrations caused by the up-and-down movement can cause blurring of the read image, defocusing the read image, and other image defects.

[0005] An object of the present invention is to provide an image reading device and an image forming device that can improve the read image quality during reading even when the image reading unit supported by a bearing is moved by a drive unit. [Means for solving the problem]

[0006] The image reading device of the present invention includes a document glass table, an image reading unit that is movable relative to the document glass table and reads an image formed on a document placed on the document glass table while moving, a bearing portion attached to the image reading unit, a guide shaft that guides the image reading unit in a sub-scanning direction by contacting and sliding with the bearing portion, and a drive portion that is connected to a connecting portion of the image reading unit at a position parallel to the guide shaft and on one side of the main scanning direction, and that moves the image reading unit by supplying an external force to the connecting portion based on a drive force of a drive source, the bearing portion contacting and sliding with the guide shaft, and having a first sliding portion and a second sliding portion that are disposed at different positions in the sub-scanning direction, the first sliding portion being a front sliding portion. The guide shaft is in line contact with the guide shaft and slides while supporting the weight of the bearing portion and the image reading unit, and has a first contact surface and a second contact surface that are arranged on opposite sides of a center line of the guide shaft in the main scanning direction of the image reading unit, the first contact surface is provided at an angle with respect to a vertical direction, and when the minimum angle formed by the first contact surface and the vertical direction is θ1, a force acting in the vertical direction from the first contact surface to the guide shaft due to the weight of the bearing portion and the image reading unit is F1, and a force acting in the main scanning direction from the first contact surface to the guide shaft due to a rotational moment generated in the bearing portion when the drive unit moves the image reading unit is F2, the relationship F1>F2×tan θ1 is satisfied. The first sliding portion is disposed on the same side of the center line of the guide shaft as the first contact surface in the main scanning direction, and has a third contact surface that abuts against an end of the guide shaft in the main scanning direction. It is characterized by:

[0007] An image reading device of the present invention includes a document glass table, an image reading unit that is movable relative to the document glass table and reads an image formed on a document placed on the document glass table while moving, a bearing portion attached to the image reading unit, a guide shaft that guides the image reading unit in a sub-scanning direction by contacting and sliding with the bearing portion, and a drive portion that is connected to a connecting portion of the image reading unit at a position parallel to the guide shaft and on one side of the main scanning direction, and that moves the image reading unit by supplying an external force to the connecting portion based on a drive force of a drive source, and the bearing portion contacts and slides with the guide shaft and moves at the same position in the sub-scanning direction. the first sliding portion is in line contact with the guide shaft and slides while supporting the weight of the bearing portion and the image reading unit, and has a first contact surface and a second contact surface that are arranged on opposite sides of the center line of the guide shaft in the main scanning direction of the image reading unit, and the first contact surface is inclined with respect to the vertical direction so that a force acting upward in the vertical direction on the first contact surface due to a rotational moment generated in the bearing portion when the drive portion moves the image reading unit is smaller than a force acting downward in the vertical direction on the first contact surface due to the weight of the bearing portion and the image reading unit. The first sliding portion is disposed on the same side of the center line of the guide shaft as the first contact surface in the main scanning direction, and has a third contact surface that abuts against an end of the guide shaft in the main scanning direction. It is characterized by:

[0008] Furthermore, an image forming apparatus of the present invention is characterized by comprising the image reading device described above, and an image forming section that forms an image on a recording material based on the image read by the image reading device. [Effects of the Invention]

[0009] According to the present invention, even in a configuration in which the image reading unit supported by the bearing is moved by the drive unit, it is possible to improve the quality of the read image during reading. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a perspective view showing an image reading apparatus according to an embodiment; [Figure 2] FIG. 1 is a perspective view showing a reader according to an embodiment. [Figure 3] FIG. 2 is a plan view showing a drive mechanism of the image reading unit according to the embodiment. [Figure 4] FIG. 2 is a front view showing the image reading unit according to the embodiment. [Figure 5] FIG. 2 is a perspective view showing a bearing portion according to the embodiment. [Figure 6] FIG. 4 is a bottom view showing the bearing portion according to the embodiment. [Figure 7] FIG. 2 is a front view showing a bearing portion according to the embodiment. [Figure 8] FIG. 4 is an explanatory diagram showing the force relationship at a first contact point according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] An embodiment of the present invention will be described in detail below with reference to Figs. 1 to 8. In this embodiment, an image reading device 1 is mounted on an image forming device 10. The image forming device 10 includes an image forming section 11 that forms an image on a recording material based on an image read by the image reading device 1.

[0012] [Image reader] 1 to 3, the schematic configuration of an ADF 3 (Automatic Document Feeder) and a reader 31 that constitute an image reading device 1 will be described. As shown in FIG. 1, the image reading device 1 is provided with an ADF 3 that separates and feeds a plurality of original documents and reads images printed on the original documents. The ADF 3 is provided with a feed tray 32 on which an original document to be fed is placed, and a discharge tray 33 that separates, feeds, conveys, and discharges the original documents placed on the feed tray 32. A reader 31 is provided below the ADF 3. As shown in FIG. 2, the reader 31 can read an image of an original document conveyed by the ADF 3 through a flow reading glass 40, or can read an image of a thick original document such as a book placed on a platen glass 41 by opening the ADF 3.

[0013] 3, an image reading unit 5 having sensors and capable of reading a line image one line at a time is movably provided inside the reader 31. In this embodiment, the direction in which the sensors that read the line image in the image reading unit 5 are arranged is referred to as the main scanning direction X, the direction in which the image reading unit 5 moves is referred to as the sub-scanning direction Y, and the vertical direction is referred to as the up-down direction Z. Furthermore, both the main scanning direction X and the sub-scanning direction Y are horizontal directions.

[0014] When the ADF 3 is closed, the image reading unit 5 reads the surface of the document transported by the ADF 3 through the flow reading glass 40, or when the ADF 3 is open, the image reading unit 5 reads the image of the document placed on the document glass 41. When reading the surface of the document transported by the ADF 3, the image reading unit 5 stands still at a predetermined flow reading position facing the flow reading glass 40. On the other hand, when reading the image of the document placed on the document glass 41, the image reading unit 5 is guided by a first guide shaft 67 and a second guide shaft 68 provided inside the reader 31 and reads the image by scanning from a standby position. In other words, the image reading unit 5 is movable relative to the document glass 41 and reads the image formed on the document placed on the document glass 41 while moving.

[0015] [Reader drive configuration] Next, the drive configuration of the reader 31 will be described with reference to Figures 3 and 4. Inside the reader 31, power is transmitted from a motor pulley 60 attached to the shaft of a motor 6, which is an example of a drive source, via a first timing belt 61 to a two-stage pulley 62 so as to achieve a required speed ratio. Power is transmitted from the two-stage pulley 62 to a second timing belt 63 connected to the image reading unit 5. The second timing belt 63 is positioned by a first idler pulley 64, a second idler pulley 65, and a tensioner pulley 66 so that the sub-scanning direction of the image reading unit 5 and the movement direction of the second timing belt 63 are parallel to each other.

[0016] The image reading unit 5 is guided in the sub-scanning direction Y and supported in the vertical direction Z by a first guide shaft 67 and a second guide shaft 68 provided inside the reader 31. In this embodiment, the first guide shaft 67 and the second guide shaft 68 are both cylindrical or columnar metal shafts. A bearing portion 7 having a fitting portion that fits with the first guide shaft 67 is provided on the underside of the image reading unit 5 at a position corresponding to the first guide shaft 67. Furthermore, a slider member 8 that slides on the second guide shaft 68 is provided on an end of the image reading unit 5 in the main scanning direction X at a position corresponding to the second guide shaft 68. That is, the first guide shaft 67, which is an example of a guide shaft, guides the image reading unit 5 in the sub-scanning direction Y by sliding with the bearing portion 7 in contact with it. In this embodiment, the bearing portion 7 and the slider member 8 are formed of a highly slidable resin such as POM so that they can slide smoothly on the first guide shaft 67 and the second guide shaft 68. However, the material is not limited to a highly slidable resin such as POM, and the material may be other materials.

[0017] [Bearing part] Next, the configuration of the bearing 7 will be described in detail with reference to Figures 5 to 7. As shown in Figure 5, the bearing 7 is provided with a connecting portion 70 for transmitting the power of the second timing belt 63, which is a drive transmission means, to the image reading unit 5. By engaging and connecting the second timing belt 63 to this connecting portion 70, it becomes possible to scan the image reading unit 5 in the sub-scanning direction Y in synchronization with the movement of the second timing belt 63. That is, the second timing belt 63, which is an example of a drive portion, is connected to the connecting portion 70 at a position parallel to the first guide shaft 67 and on one side of the main scanning direction X, and supplies an external force to the connecting portion 70 based on the driving force of the motor 6, thereby moving the image reading unit 5.

[0018] The bearing 7 is provided with a first fitting portion 100, which is an example of a first sliding portion, and a second fitting portion 200, which is an example of a second sliding portion, in order to facilitate attachment and detachment of the image reading unit 5. That is, the bearing 7 has the first fitting portion 100 and the second fitting portion 200, which come into contact with and slide on the first guide shaft 67. The first fitting portion 100 has a first contact surface 101, a second contact surface 102, and a third contact surface 103 with respect to the first guide shaft 67, and the second fitting portion 200 has a first contact surface 201, a second contact surface 202, and a third contact surface 203 with respect to the first guide shaft 67.

[0019] Furthermore, each contact surface of the first fitting portion 100 and the second fitting portion 200 has a plurality of contact portions that make point contact or line contact with the first guide shaft 67, but for the sake of explanation in this embodiment, they are assumed to be flat. The first fitting portion 100 and the second fitting portion 200 are arranged at different positions a predetermined distance apart in the sub-scanning direction Y, and in this embodiment, they are arranged on both sides of the connecting portion 70.

[0020] When the first fitting portion 100 and the second fitting portion 200 are installed on the first guide shaft 67, two of their respective multiple contact surfaces are disposed above the center line of the first guide shaft 67 in the up-down direction Z. In this embodiment, as shown in Fig. 7, the first fitting portion 100 has, with respect to the first guide shaft 67, a first contact point T1 that contacts the first contact surface 101, a second contact point T2 that contacts the second contact surface 102, and a third contact point T3 that contacts the third contact surface 103. Note that the first contact point T1, the second contact point T2, and the third contact point T3 are all actually straight lines parallel to the sub-scanning direction Y and are also contact lines.

[0021] Here, since the first fitting portion 100 and the second fitting portion 200 are arranged on either side of the connecting portion 70 in the sub-scanning direction Y, the rotation moment M acts in the opposite direction when the image reading unit 5 moves in the Y1 direction of the sub-scanning direction Y (see FIG. 6) during document reading. Therefore, the first contact point T1 and the second contact point T2 are formed so as to be reversed in the left-right direction in FIG. 7 between the first fitting portion 100 and the second fitting portion 200.

[0022] The first fitting portion 100 will be described below, but the second fitting portion 200 has a similar configuration except that it is rotationally symmetrical in Fig. 6 and is reversed left and right in Fig. 7, so a detailed description will be omitted. The first fitting portion 100 has a first contact surface 101 and a second contact surface 102 that contact the outer circumferential surface of the first guide shaft 67, a third contact surface 103, a cylindrical surface 104, and a guide surface 105 that is disposed on the first guide shaft 67 with a gap S therebetween. The cylindrical surface 104 has a shape that connects the upper ends of the first contact surface 101 and the second contact surface 102 in a substantially cylindrical shape.

[0023] The first contact surface 101 and the second contact surface 102 are in line contact with the first guide shaft 67 and slide while supporting the weight of the bearing portion 7 and the image reading unit 5, and are arranged on opposite sides of the center line of the first guide shaft 67 in the main scanning direction X of the image reading unit 5. The first contact surface 101 and the second contact surface 102 are provided so as to be inclined with respect to the up-down direction Z. Note that the first contact surface 101 and the second contact surface 102 are also provided so as to be inclined with respect to the main scanning direction X.

[0024] The third contact surface 103 and the guide surface 105 are arranged on opposite sides of the center line of the first guide shaft 67 in the main scanning direction X so as to sandwich the first guide shaft 67, and are spaced apart at a distance wider than the diameter of the first guide shaft 67 in the main scanning direction X. The third contact surface 103 is arranged on the same side of the center line of the first guide shaft 67 as the first contact surface 101 in the main scanning direction X, and abuts against the end of the first guide shaft 67 in the main scanning direction X. The first contact surface 101 and the second contact surface 102 are formed continuously at both circumferential ends of the cylindrical surface 104, and protrude toward the first guide shaft 67 beyond the circumferential surface. When installed on the first guide shaft 67, the first contact surface 101 and the second contact surface 102 are located above the center line of the first guide shaft 67 in the up-down direction Z.

[0025] When attaching the image reading unit 5 to the first guide shaft 67, it is placed from above so that the first contact surface 101 and the second contact surface 102 are in contact with the first guide shaft 67. At this time, the contact line between the first contact surface 101 and the first guide shaft 67 is defined as a first contact point T1, and the contact line between the first contact surface 102 and the second contact surface 102 is defined as a second contact point T2.

[0026] 6, since the connecting portion 70 is disposed at a predetermined distance from the first guide shaft 67 in the main scanning direction X, a rotational moment M is generated in the bearing portion 7 when the image reading unit 5 moves in the Y1 direction. At this time, a force F2 in the main scanning direction X acts on the first fitting portion 100, and a force F20 in the main scanning direction X, which is opposite to F2, acts on the second fitting portion 200. As a result, as shown in FIG. 7, a force F1 in the vertical direction Z and a force F2 in the main scanning direction X act on the first fitting portion 100 at the first contact point T1. The force F1 is a force acting in the vertical direction Z from the first contact surface 101 on the first guide shaft 67 due to the weight of the bearing portion 7 and the image reading unit 5. Force F2 is a force that acts in the main scanning direction X from the first contact surface 101 on the first guide shaft 67 due to a rotational moment M that is generated in the bearing portion 7 when the second timing belt 63 moves the image reading unit 5 in the Y1 direction. A force F4 in the vertical direction Z acts on a second contact point T2 that is located on the opposite side to the side on which force F2 acts. Furthermore, similar forces act on the second fitting portion 200 symmetrically about the center line of the first fitting portion 100 and the first guide shaft 67.

[0027] That is, the first contact point T1 of each of the first fitting portion 100 and the second fitting portion 200 is positioned so as to receive a rotation moment M acting about the connecting portion 70 when the image reading unit 5 moves in the Y1 direction during image reading. In this embodiment, as shown in Fig. 7, the first contact point T1 of the first fitting portion 100 is positioned so as to satisfy F1 > F2 × tan θ1, where θ1 is the angle formed between the horizontal direction and a perpendicular line L1 to a tangent plane P1 to the first guide shaft 67. Here, the angle θ1 is the minimum angle formed between the first contact surface 101 and the vertical direction Z.

[0028] The relationship of these forces will be described with reference to FIG. 8. In FIG. 8, the first contact point T1 of the first fitting portion 100 will be described. However, regarding the second fitting portion 200, since it is rotationally symmetric in the state shown in FIG. 6, the description thereof will be omitted because it is the same in other respects. As shown in FIG. 8, in the tangential direction of the first contact point T1, a downward F1×cosθ1 and an upward F2×sinθ1 act. At this time, if F1×cosθ1 < F2×sinθ1 (F1 < F2×tanθ1), the image reading unit 5 will operate so as to float upward. As a result, when the image reading unit 5 moves in the Y1 direction during image reading, horizontal blur and the like are likely to occur, making it difficult to stably read an image.

[0029] Therefore, in the present embodiment, by arranging the first contact point T1 so as to satisfy F1 > F2×tanθ1, it is possible to prevent the image reading unit 5 from operating so as to float when moving in the Y1 direction during image reading. Also, in the second fitting portion 200, the first contact point T1 is arranged so as to satisfy F1 > F2×tanθ1. When there are two or more fitting portions on the side where the rotational moment of the sliding portion between the bearing portion 7 and the first guide shaft 67 acts, it is preferable that each fitting portion satisfies F1 > F2×sinθ1. However, in this case, if the floating of the image reading unit 5 as a whole can be prevented, it is not necessary for some fitting portions to satisfy F1 > F2×sinθ1.

[0030] Also, the magnitude of the force F1 may also have a component in the vertical direction Z of the rotational moment M, but mainly changes depending on the weight of the image reading unit 5 and the distance from the center of gravity G in a predetermined direction of the first guide shaft 67. That is, the closer the distance from the center of gravity G, the greater the tendency for the force F1 to be larger. Also, the magnitude of the force F2 increases in proportion to the distance from the connecting portion 70 to the first contact point T1. For this reason, although the optimum value of the angle θ1 varies depending on the conditions, it is desirable to make it as small as possible (make it a steep slope) because the floating caused by the rotational moment M can be suppressed. In the present embodiment, when at least the force F1 is greater than or equal to the force F2, it is preferable that the angle θ1 is less than 45°.

[0031] That is, the force acting upward in the vertical direction Z on the first contact surface 101 due to the rotational moment M generated in the bearing 7 when the second timing belt 63 moves the image reading unit 5 is defined as F2×tan θ1. Also, the force acting downward in the vertical direction Z on the first contact surface 101 due to the weight of the bearing 7 and the image reading unit 5 is defined as force F1. The first contact surface 101 is provided at an incline with respect to the vertical direction Z so that F2×tan θ1 is smaller than force F1.

[0032] 6, the distances in the sub-scanning direction Y between the first fitting portion 100 and the second fitting portion 200 relative to the connecting portion 70 are defined as N1 and N2, respectively. If the distances N1 and N2 are not the same, the generated forces F2 and F20 will not be the same, so the angle θ1 of the first contact surface 101 of the first fitting portion 100 and the angle θ1' of the first contact surface 201 of the second fitting portion 200 can be set to different angles accordingly. When unifying θ1 and θ1', it is preferable to set them to match the more stringent condition.

[0033] On the other hand, if θ1 is made small, there is a risk that the image reading unit 5 will be significantly misaligned in the vertical direction Z from its designed position if the positional relationship with the second contact point T2 in the main scanning direction X is displaced due to dimensional tolerances. A significant misalignment in the vertical direction Z changes the distance from the image reading unit 5 to the document surface, potentially resulting in a loss of focus. For this reason, in this embodiment, the second contact point T2 of the first fitting portion 100 is positioned so that θ2 > θ1 is satisfied, where θ2 is the angle formed by the perpendicular line L2 to the tangent plane P2 to the first guide shaft 67 and the main scanning direction X. In other words, the angle θ2 is the minimum angle formed by the second contact surface 102 and the vertical direction Z.

[0034] That is, it is desirable to make θ1 a small angle and make the surface resemble a vertical wall in order to suppress horizontal moments. However, if the shape is symmetrical with respect to the main scanning direction X, such that θ2 = θ1, there is a risk that the contact position with the first guide shaft 67 will be significantly misaligned in the height direction due to deviations in the distance between the first contact point T1 and the second contact point T2 in the main scanning direction X caused by dimensional tolerances. For this reason, the angle of θ2 is made larger than θ1 so that the second contact surface 102 presses the first guide shaft 67 downward, thereby ensuring the position of the bearing portion 7 in the up-down direction Z.

[0035] Furthermore, the distance in the main scanning direction X between the third contact surface 103 and the guide surface 105 is set to be wider than the diameter of the first guide shaft 67 in the main scanning direction X. This is because if the distance in the main scanning direction X between the third contact surface 103 and the guide surface 105 were narrower than the diameter of the first guide shaft 67, the rotation moment M generated when the image reading unit 5 moves in the Y1 direction would become larger. In order to suppress an increase in the rotation moment M, it is necessary to make the distance between the third contact surface 103 and the guide surface 105 larger than the diameter of the first guide shaft 67.

[0036] Here, when the first guide shaft 67 is provided between the third contact surface 103 and the guide surface 105, a gap occurs, but it is necessary to provide the gap S between the guide surface 105 and the first guide shaft 67. In other words, if a gap exists between the third contact surface 103 and the first guide shaft 67, if the force F2 is greater than expected when the image reading unit 5 starts to move, the image reading unit 5 may be displaced in the main scanning direction X, causing the image reading unit 5 to lift up. For this reason, the gap S is provided on the guide surface 105 side, and the third contact surface 103 is kept in contact with the first guide shaft 67 in the main scanning direction X. As a result, even if a force F2 greater than expected is generated, the third contact surface 103 abuts against the first guide shaft 67, dispersing the force F2, thereby preventing the image reading unit 5 from lifting up.

[0037] As described above, according to the image reading device 1 of this embodiment, θ1 is positioned so that the force F2 generated by the rotation moment M during scanning of the image reading unit 5 satisfies F1>F2 tan θ1 at the first contact point T1. This makes it possible to suppress vibration (rattle) of the image reading unit 5 due to the rotation moment M. This suppresses blurring and out-of-focus of the read image, and improves the read image quality during reading, even in a configuration in which the image reading unit 5 supported by the bearing portion 7 is moved by the second timing belt 63.

[0038] Furthermore, there is no need to add components to prevent lifting or lateral displacement, and furthermore, it is possible to suppress the increase in sliding load that occurs due to the increase in contact surface caused by increasing the configuration, and there is no need to increase the output of the motor 6. As a result, it is possible to reduce vibrations that occur during scanning of the image reading unit 5 due to play caused by the gap S in the past, and reduce image defects such as image blur at low cost.

[0039] Furthermore, according to the image reading device 1 of this embodiment, by arranging the second contact point T2 so that θ2>θ1 is satisfied, it is possible to reduce machine differences in the height direction due to dimensional tolerances.

[0040] Furthermore, according to the image reading device 1 of this embodiment, a third contact point T3 is provided by providing a third contact surface 103 that contacts the first guide shaft 67 in the main scanning direction X. This makes it possible to distribute the force F2 even when the force F2 is greater than expected, thereby preventing the image reading unit 5 from shifting in the main scanning direction X and upward, thereby achieving more stable scanning.

[0041] Incidentally, the image reading device 1 of the present embodiment has been described above in terms of the case where the second contact point T2 is arranged so as to satisfy θ2>θ1, but this is not limitative, and for example, θ2=θ1 may be acceptable.

[0042] Furthermore, the image reading device 1 of the present embodiment described above is described as being provided with the third contact surface 103 that contacts the first guide shaft 67 in the main scanning direction X, but is not limited to this. For example, if there is no need to consider the force F2 becoming greater than expected, the third contact surface 103 may be omitted. [Explanation of symbols]

[0043] 1...image reading device, 5...image reading unit, 6...motor (drive source), 7...bearing portion, 10...image forming device, 11...image forming portion, 41...platen glass, 63...second timing belt (drive portion), 67...first guide shaft (guide shaft), 70...connecting portion, 100...first fitting portion (first sliding portion), 101...first contact surface, 102...second contact surface, 103...third contact surface, 200...second fitting portion (second sliding portion), X...main scanning direction, Y...sub-scanning direction, Z...up and down direction (vertical direction)

Claims

1. The manuscript glass and an image reading unit that is movable relative to the platen glass and reads an image formed on a document placed on the platen glass while moving; a bearing portion attached to the image reading unit; a guide shaft that guides the image reading unit in the sub-scanning direction by contacting and sliding with the bearing portion; a drive unit that is connected to a connection portion of the image reading unit at a position parallel to the guide shaft and on one side in the main scanning direction, and that moves the image reading unit by supplying an external force to the connection portion based on a drive force of a drive source; the bearing portion has a first sliding portion and a second sliding portion that come into contact with and slide on the guide shaft and are disposed at different positions in the sub-scanning direction, the first sliding portion is in line contact with the guide shaft and slides while supporting the weight of the bearing portion and the image reading unit, and has a first contact surface and a second contact surface that are disposed on opposite sides of the guide shaft in the main scanning direction of the image reading unit, the first contact surface is provided at an angle with respect to the vertical direction, where θ1 is the minimum angle between the first contact surface and the vertical direction, F1 is the force acting in the vertical direction from the first contact surface to the guide shaft due to the weight of the bearing portion and the image reading unit, and F2 is the force acting in the main scanning direction from the first contact surface to the guide shaft due to a rotational moment generated in the bearing portion when the drive portion moves the image reading unit, the relationship F1>F2×tan θ1 is satisfied, the first sliding portion is disposed on the same side in the main scanning direction as the first contact surface with respect to the center line of the guide shaft, and has a third contact surface that abuts against an end of the guide shaft in the main scanning direction. An image reading device characterized by:

2. the second contact surface is provided at an angle with respect to the vertical direction, When the minimum angle between the second contact surface and the vertical direction is θ2, The relationship θ2>θ1 is satisfied.

2. The image reading device according to claim 1, wherein:

3. θ1 is less than 45°; 3. The image reading device according to claim 1, wherein the image reading device is a scanning device.

4. The manuscript glass and an image reading unit that is movable relative to the platen glass and reads an image formed on a document placed on the platen glass while moving; a bearing portion attached to the image reading unit; a guide shaft that guides the image reading unit in the sub-scanning direction by contacting and sliding with the bearing portion; a drive unit that is connected to a connection portion of the image reading unit at a position parallel to the guide shaft and on one side in the main scanning direction, and that moves the image reading unit by supplying an external force to the connection portion based on a drive force of a drive source; the bearing portion has a first sliding portion and a second sliding portion that come into contact with and slide on the guide shaft and are disposed at different positions in the sub-scanning direction, the first sliding portion is in line contact with the guide shaft and slides while supporting the weight of the bearing portion and the image reading unit, and has a first contact surface and a second contact surface that are disposed on opposite sides of the guide shaft in the main scanning direction of the image reading unit, the first contact surface is inclined with respect to the vertical direction so that a force acting upward in the vertical direction on the first contact surface due to a rotational moment generated in the bearing portion when the drive portion moves the image reading unit is smaller than a force acting downward in the vertical direction on the first contact surface due to the weight of the bearing portion and the image reading unit; the first sliding portion is disposed on the same side in the main scanning direction as the first contact surface with respect to the center line of the guide shaft, and has a third contact surface that abuts against an end of the guide shaft in the main scanning direction. An image reading device characterized by:

5. The second sliding portion is formed so that, when viewed from one side of the sub-scanning direction, the cross-sectional shape of the second sliding portion cut by a virtual plane parallel to the main scanning direction and the vertical direction is a shape obtained by inverting, in the main scanning direction, the cross-sectional shape of the first sliding portion cut by a virtual plane parallel to the virtual plane.

5. The image reading device according to claim 1, wherein the image reading device is a scanning device.

6. The image reading device according to any one of claims 1 to 5, an image forming unit that forms an image on a recording material based on the image read by the image reading device, An image forming apparatus characterized by:

Images