Image forming device

Abstract

To provide an image forming device equipped with a paper feed cassette whose drawing is restricted during an image forming operation.SOLUTION: An image forming device includes: a paper feed cassette 5 that can be drawn out from a device body; a drive source that generates a drive force for driving an image forming part that forms an image on a paper fed from the paper feed cassette 5; and a restriction mechanism that restricts a drawing of the paper feed cassette 5. The restriction mechanism includes: a restriction member 43 which is supported by the device body and movable between a restriction position where the restriction member engages with the paper feed cassette 5, and restricts the drawing of the paper feed cassette 5 and an open position in which the restriction member is separated from the paper feed cassette 5 and the paper feed cassette 5 is allowed to be drawn; a drive gear 41 that rotates by the drive force generated by the drive source to move the restriction member 43 from the open position to the restriction position; and an engagement member 81 that moves the restriction member from the restriction position to the open position when the drive source stops.SELECTED DRAWING: Figure 7B

Description

Technical Field

[0001] The present invention relates to an image forming apparatus including a paper feed cassette that houses paper on which an image is formed.

Background Art

[0002] Image forming apparatuses such as multifunction printers and printers include a paper feed cassette that can be pulled out from the apparatus main body. In such an image forming apparatus, if the paper feed cassette is accidentally pulled out from the apparatus main body during an image forming operation, the image forming operation is interrupted, the conveyance of paper stops, and paper jams may occur. For this reason, a regulating mechanism for restricting the pulling out of the paper feed cassette may be provided in the image forming apparatus.

[0003] The image forming apparatus described in Patent Document 1 includes a bottom member provided in a media storage tray (corresponding to a paper feed cassette) on which a recording medium is placed and moves in the vertical direction, and a locking means for restricting the movement of the media storage tray in the pulling out direction. The bottom member moves upward when feeding the recording medium. The bottom member is disposed at a position where it interferes with the locking means when moving in the vertical direction, and interferes with the locking means when descending to release the restriction of the media storage tray.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the media storage tray described in Patent Document 1 above, when the paper feeding of the recording medium ends and the bottom member descends, the media storage tray becomes pullable. However, when the recording medium is full or the like, the moving distance of the bottom member becomes short. For this reason, it may become difficult for the bottom member to interfere with the locking means so as to release the regulation of the movement of the media storage tray.

[0006] Therefore, in view of the above circumstances, an object of the present invention is to provide an image forming apparatus including a paper feeding cassette that is restricted from being pulled out during an image forming operation and can be pulled out when necessary other than during the image forming operation.

Means for Solving the Problems

[0007] To achieve the above object, an image forming apparatus of the present invention includes a paper feeding cassette that is provided to be pullable from a device main body and stores paper on which an image is to be formed, a drive source that generates a driving force for driving an image forming unit that forms an image on the paper fed from the paper feeding cassette, and a regulating mechanism that restricts pulling out of the paper feeding cassette from the device main body. The regulating mechanism includes a regulating member that is supported by the device main body, engages with the paper feeding cassette, and is movable between a regulating position that restricts pulling out of the paper feeding cassette and an open position that is separated from the paper feeding cassette and permits pulling out of the paper feeding cassette, a driving member that is driven by the driving force generated by the drive source and moves the regulating member from the open position to the regulating position, and a biasing member that moves the regulating member from the regulating position to the open position when the drive source stops.

[0008] In the present invention, the driving member may be a driving gear that rotates by the driving force generated by the drive source.

[0009] The image forming apparatus according to the first embodiment of the present invention may be characterized in that the regulating member moves along a circumferential direction centered on the rotation axis of the driving gear.

[0010] In the image forming apparatus according to the first embodiment of the present invention, the paper feed cassette has a notch, and the restricting member includes a lock gear that meshes with the drive gear, a link shaft that is rotatably supported by the rotation shafts of the drive gear and the lock gear, and that connects the two rotation shafts in a state where the drive gear and the lock gear are meshed with each other, and a lock shaft provided coaxially with the rotation shaft of the lock gear. When the drive gear rotates in one direction by the drive source, the lock gear rotates in a direction opposite to the one direction and moves in the one direction along the circumferential direction centered on the rotation shaft of the drive gear, and the lock shaft enters the notch, whereby the pulling out of the paper feed cassette from the apparatus main body may be restricted.

[0011] In the image forming apparatus according to the first embodiment of the present invention, the biasing member is a torsion coil spring having a coil portion and two arm portions. The coil portion is externally fitted to the rotation shaft of the drive gear, one of the arm portions is fixed to the apparatus main body, and the other arm portion is fixed to the link shaft. When the drive source stops driving and the drive gear stops rotating, the link shaft is biased by the torsion coil spring and rotates about the rotation shaft of the lock gear, and the lock shaft moves away from the notch, which may be a feature.

[0012] In the image forming apparatus according to the first embodiment of the present invention, the link shaft may be provided with a restricting piece that abuts against the apparatus main body and restricts rotation in the one direction along the circumferential direction from a predetermined position.

[0013] In the image forming apparatus according to the second embodiment of the present invention, the restricting member may move along a direction parallel to the rotation shaft of the drive gear.

[0014] In the image forming apparatus according to the second embodiment of the present invention, the paper feed cassette has a notch, the drive gear has a drive sprocket gear that rotates by a driving force generated by the drive source, and the restricting member includes a driven sprocket gear that meshes with the drive sprocket gear of the drive gear, and a lock shaft that is movably provided integrally with the driven sprocket gear along the axial direction of the rotation axis of the driven sprocket gear and is rotatable relative to the driven sprocket gear. When the drive sprocket gear rotates in one direction by the drive source, the driven sprocket gear moves in one direction along the axial direction of the rotation axis while rotating in a direction opposite to the one direction, and the lock shaft moves in the one direction together with the driven sprocket gear and is inserted into the opening of the paper feed cassette, whereby the pulling out of the paper feed cassette from the apparatus main body may be restricted.

[0015] In the image forming apparatus according to the second embodiment of the present invention, a cover plate is provided on one direction side along the axial direction of the rotation axis of the driven sprocket gear, and the biasing member is a coil spring externally fitted to the lock shaft. The coil spring is disposed between the driven sprocket gear and the cover plate and biases the driven sprocket gear in the other direction opposite to the one direction.

[0016] In the image forming apparatus according to the second embodiment of the present invention, stoppers for positioning the lock shaft at a position where it enters the notch of the paper feed cassette and at a position separated from the notch may be provided.

Effects of the Invention

[0017] According to the present invention, when the paper feed cassette is housed in the apparatus main body and the image forming operation is executed, the pulling out of the paper feed cassette is automatically restricted. On the other hand, when the image forming operation stops, the paper feed cassette can be pulled out. Therefore, it is possible to reduce paper jams and poor paper conveyance caused by pulling out the paper feed cassette during the image forming operation.

Brief Description of the Drawings

[0018]

Figure 1

Figure 2

Figure 3A

Figure 3B

Figure 4

Figure 5A

Figure 5B

Figure 6A

Figure 6B

Figure 6C

Figure 7A

Figure 7B

Figure 8

Figure 9

Figure 10A

Figure 10B

Figure 11A

Figure 11B

Mode for Carrying Out the Invention

[0019] Hereinafter, an image forming apparatus according to an embodiment of the present invention will be described with reference to the drawings.

[0020] First, with reference to FIG. 1, the overall configuration of the image forming apparatus 1 will be described. FIG. 1 is a side view schematically showing the internal configuration of the image forming apparatus 1 according to an embodiment of the present invention. Fr, Rr, L, and R in each figure indicate the front side, rear side, left side, and right side of the image forming apparatus 1, respectively.

[0021] The image forming apparatus 1 includes a substantially rectangular parallelepiped-shaped apparatus main body 3 having a hollow portion. At the lower part of the apparatus main body 3, a cassette accommodating portion 7 is formed in which a paper feed cassette 5 is removably accommodated. An opening 7a communicating with the cassette accommodating portion 7 is formed in the front side plate of the apparatus main body 3. The paper feed cassette 5 is accommodated in the cassette accommodating portion 7 through the opening 7a. A discharge tray 9 is formed on the upper surface of the apparatus main body 3. In the hollow portion of the apparatus main body 3, a paper feed unit 11, an image forming unit 13, a fixing unit 15, and a discharge unit 17 are provided in order along the paper conveyance path P.

[0022] The paper feed unit 11 is disposed above the front end portion of the cassette accommodating portion 7, and includes a pickup roller, and a paper feed roller and a separation roller that are disposed downstream of the pickup roller and are in contact with each other to form a separation nip. The image forming unit 13 is disposed behind the paper feed unit 11, and includes a photosensitive drum rotatably supported, a charging device, a developing device, a transfer roller, a cleaning device, and an exposure device that are sequentially disposed along the rotation direction around the photosensitive drum. The fixing unit 15 includes a heating roller heated by a heat source and a pressure roller pressed against the heating roller. The discharge unit 17 includes a pair of discharge rollers.

[0023] Next, the image forming operation will be briefly described. First, in the paper feed unit 11, the pickup roller rotates and the paper is fed out from the paper feed cassette 5. The fed paper is separated one by one at the separation nip and then conveyed to the image forming unit 13 along the conveyance path P. In the image forming unit 13, the photosensitive drum is charged by the charging device. The charged photosensitive drum is exposed based on the image data from the exposure device to form an electrostatic latent image. The electrostatic latent image is developed into a toner image by the developing device. The toner image is transferred onto the paper passing between the photosensitive drum and the transfer roller. The toner remaining on the photosensitive drum is removed by the cleaning device.

[0024] Thereafter, the sheet is conveyed to the fixing unit 15 along the conveyance path P, and passes between the heating roller and the pressure roller, so that the toner image is heated and pressed and fixed on the sheet. The sheet on which the toner image is fixed is conveyed to the discharge unit 17 along the conveyance path P, and is discharged to the discharge tray 9 by the discharge roller pair of the discharge unit 17.

[0025] The pickup roller of the paper feeding unit 11, the photosensitive drum of the image forming unit 13, the pressure roller of the fixing unit 15, the discharge roller of the discharge unit 17, etc. are driven to rotate by the main motor 19 as a drive source provided in the apparatus main body 3. That is, the above-described image forming operation is executed by driving the paper feeding unit 11, the image forming unit 13, the fixing unit 15, and the discharge unit 17 with the driving force generated when the main motor 19 is driven. In other words, when the main motor 19 stops driving, the image forming operation is not executed.

[0026] Furthermore, the image forming apparatus 1 includes a regulating mechanism 21 (not shown in FIG. 1) that regulates the pulling out of the paper feed cassette 5 from the cassette housing portion 7 during the above-described image forming operation.

[0027] Next, the regulating mechanism 21 according to the first embodiment will be described with reference to FIG. 2. FIG. 2 is a perspective view showing the regulating mechanism 21.

[0028] First, the paper feed cassette 5 will be described with reference to FIG. 2. The paper feed cassette 5 has a shallow tray shape with an open upper surface, and has a bottom plate 31, a front plate 33, and left and right side plates 35. A cover plate 37 is attached to the outside (front side) of the front plate 33. As shown in FIG. 1, the paper feed cassette 5 is housed in the cassette housing portion 7 through the lower part of the paper feeding unit 11. When the paper feed cassette 5 is housed in the cassette housing portion 7, the opening 7a is closed by the cover plate 37.

[0029] The paper feed cassette 5 is provided with a lift plate (not shown) on which the paper is placed. The lift plate is disposed on the bottom plate 31 and is rotatably supported so that the front end portion thereof inclines upward. When the lift plate inclines upward, the front end portion of the placed paper abuts against the pickup roller of the paper feed unit 11. Thereafter, as the pickup roller rotates, the paper is fed.

[0030] At the front end portion of the right side plate 35, a notch 39 extending downward from the upper edge is formed behind the paper feed unit 11. By engaging the regulating mechanism 21 provided in the apparatus main body 3 with this notch 39, the pulling out of the paper feed cassette 5 from the cassette housing portion 7 is regulated.

[0031] Next, with reference to FIG. 2, FIGS. 3A, 3B, and FIG. 4, the regulating mechanism 21 will be described. FIGS. 3A, 3B, and FIG. 4 are perspective views showing the regulating mechanism 21. As shown in FIGS. 3A and 3B, the regulating mechanism 21 includes a drive gear 41 driven by the drive of the main motor 19, and a regulating member 43 driven by the drive gear 41 to move.

[0032] First, the drive gear 41 will be described. As shown in FIG. 2, the main motor 19 is supported on the outer surface (opposite side to the cassette housing portion 7) of the right side plate 3a of the apparatus main body 3, behind the paper feed unit 11. The drive shaft 19a of the main motor 19 penetrates the right side plate 3a and protrudes to the inner side (the side of the cassette housing portion 7) of the right side plate 3a. A gear is formed along the circumferential direction at the end portion of the protruding drive shaft 19a. Further, as shown in FIGS. 3A and 3B, an idle gear 45 and a drive gear 41 are rotatably supported on the inner surface of the right side plate 3a.

[0033] As shown in FIG. 3A, the idle gear 45 is a two-stage gear having a small-diameter upper-stage gear and a large-diameter lower-stage gear, and is disposed in front of the main motor 19. The lower-stage gear of the idle gear 45 meshes with the gear of the drive shaft 19a of the main motor 19.

[0034] As shown in FIGS. 3A and 3B, the drive gear 41 is a two-stage gear having upper and lower gears of the same diameter, located in front of the idle gear 45 and behind the paper feed unit 11. The lower gear of the drive gear 41 meshes with the upper gear of the idle gear 45.

[0035] Next, the regulating member 43 will be described with reference to FIGS. 3A and 3B and FIGS. 5A and 5B. FIG. 5A is an exploded perspective view showing the regulating member 43, and FIG. 5B is a perspective view showing the regulating member 43. The regulating member 43 includes a lock gear 51 that meshes with the upper gear of the drive gear 41, a link shaft 53 that connects the rotation shaft 51a of the lock gear 51 and the rotation shaft 41a of the drive gear 41, and a lock shaft 55 provided coaxially with the rotation shaft 51a of the lock gear 51.

[0036] As shown in FIG. 5A, the lock gear 51 is a gear having teeth that can mesh with the upper gear of the drive gear 41, and the rotation shaft 51a is formed in a cylindrical shape.

[0037] The link shaft 53 is a rectangular parallelepiped member having a predetermined length and thickness. Axial holes 61 and support holes 63 that penetrate in the thickness direction are formed at both longitudinal ends of the link shaft 53. The distance between the two holes 61 and 63 is equal to the distance between the rotation shaft 51a of the lock gear 51 and the rotation shaft 41a of the drive gear 41 when the lock gear 51 and the upper gear of the drive gear 41 are meshed (see FIGS. 3A and 3B). As shown in FIGS. 5A and 5B, a regulating piece 65 extending longitudinally from one side surface is formed at the end of the link shaft 53 on the side of the axial hole 61 (see also FIG. 4). Further, a protruding piece 67 extending in a direction orthogonal to the axial direction of the two holes 61 and 63 is formed on one bottom surface of the link shaft 53.

[0038] The lock shaft 55 has a large-diameter portion 71, a medium-diameter portion 73, and a small-diameter portion 75 formed coaxially. As shown in FIG. 5B, the small-diameter portion 75 of the lock shaft 55 is rotatably inserted into the rotation shaft 51a of the lock gear 51 through the support hole 63 of the link shaft 53, and the medium-diameter portion 73 is rotatably inserted into the support hole 63 of the link shaft 53. The large-diameter portion 71 of the lock shaft 55 extends coaxially with the rotation shaft 51a of the lock gear 51.

[0039] As shown in FIGS. 3A and 3B, the link shaft 53 is arranged in a posture where the regulating piece 65 faces forward and the protruding piece 67 faces the right side plate 3a. The rotation shaft 41a of the drive gear 41 is rotatably inserted into the shaft hole 61 of the link shaft 53, and the lock gear 51 meshes with the upper-stage gear of the drive gear 41. The large-diameter portion 71 of the lock shaft 55 protrudes into the cassette housing portion 7 along the direction of the rotation shaft 51a of the lock gear 51.

[0040] In this way, the lock gear 51 and the upper-stage gear of the drive gear 41 are connected by the link shaft 53 in a meshed state. Therefore, when the drive gear 41 rotates in one direction, the lock gear 51 rotates in a direction opposite to the rotation direction of the drive gear 41 and moves in the rotation direction of the drive gear 41 along the circumferential direction centered on the rotation shaft 41a of the drive gear 41. That is, the lock shaft 55 moves along the circumferential direction centered on the rotation shaft 41a of the drive gear 41.

[0041] As shown in FIG. 3B, the link shaft 53 is maintained in a posture inclined obliquely upward rearward from the rotation shaft 41a of the drive gear 41 by the torsion coil spring 81. At this time, the height of the lock shaft 55 is higher than the height of the right side plate 35 of the paper feed cassette 5 housed in the cassette housing portion 7.

[0042] The coil portion of the torsion coil spring 81 is externally fitted to the rotating shaft 41a of the drive gear 41. One arm portion of the torsion coil spring 81 is fixed to the link shaft 53, and the other arm portion is fixed to the paper feeding unit 11 adjacent to the drive gear 41 (see also FIGS. 7A and 7B). As a result, the link shaft 53 is maintained in a posture inclined obliquely upward rearward from the rotating shaft 41a of the drive gear 41 with respect to the paper feeding unit 11, that is, the apparatus main body 3 (see FIGS. 3A and 3B). This posture is defined as the initial posture of the link shaft 53.

[0043] Further, when the link shaft 53 is rotated counterclockwise in FIGS. 3A and 3B about the rotating shaft 41a of the drive gear 41 against the biasing force of the torsion coil spring 81, eventually, as shown in FIG. 4, the regulating piece 65 of the link shaft 53 comes into contact with the lower surface of the paper feeding unit 11 from below, and the rotation of the link shaft 53 is regulated. In this state, the link shaft 53 rotates to a substantially horizontal posture.

[0044] The operation of regulating the pulling out of the paper feed cassette 5 by the regulating mechanism 21 according to the first embodiment having the above configuration will be described with reference to FIGS. 6A to 6C, 7A, and 7B. FIGS. 6A to 6C are side views showing the regulating mechanism 21, and FIGS. 7A and 7B are perspective views showing the regulating mechanism 21.

[0045] In a state where the paper feed cassette 5 is not housed in the cassette housing portion 7, as shown in FIG. 6A, the regulating member 43 is maintained in the initial posture by the torsion coil spring 81. That is, the link shaft 53 is inclined obliquely upward rearward from the rotating shaft 41a of the drive gear 41, and the lock shaft 55 (large diameter portion 71) protrudes into the cassette housing portion 7.

[0046] In this state, as shown in FIG. 7A, the paper feed cassette 5 is housed in the cassette housing portion 7. Since the height of the lock shaft 55 is higher than the right side plate 35 of the paper feed cassette 5, the paper feed cassette 5 does not interfere with the lock shaft 55.

[0047] After the image forming operation is executed, the main motor 19 starts to be driven. When the main motor 19 starts to be driven as described above, the photosensitive drum of the image forming unit 13, the pressure roller of the fixing unit 15, the discharge roller of the discharge unit 17, etc. start to rotate. Also, when the main motor 19 is driven, the drive gear 41 rotates in the counterclockwise direction in FIG. 6A via the idle gear 45 (see arrow A). Then, the lock gear 51 that meshes with the drive gear 41 and is connected via the link shaft 53 rotates in the clockwise direction opposite to the rotation direction of the drive gear 41 (see arrow B), and moves in the counterclockwise direction, the same as the rotation direction of the drive gear 41, along the circumferential direction centered on the rotation axis 41a of the drive gear 41. That is, the lock shaft 55 moves in the counterclockwise direction around the rotation axis 41a of the drive gear 41 (see arrow C), and the link shaft 53 rotates in the counterclockwise direction.

[0048] Eventually, as shown in FIGS. 6B and 7B, when the link shaft 53 rotates to a posture that extends substantially horizontally rearward from the rotation axis 41a of the drive gear 41, the lock shaft 55 enters the notch 39 formed in the right side plate 35 of the paper feed cassette 5. As a result, the paper feed cassette 5 cannot be pulled out from the cassette housing portion 7 by the restricting member 43 provided in the apparatus main body 3. In this way, the restricting member 43 moves from the open position (see FIGS. 6A and 7A) where it is separated from the paper feed cassette 5 and permits the pulling out and mounting of the paper feed cassette 5, to the restricting position (see FIGS. 6B and 7B) where it engages with the paper feed cassette 5 and restricts the pulling out of the paper feed cassette 5. Also, the drive gear 41 is an example of a drive member that is driven by the driving force generated by the main motor 19 in the present invention and moves the restricting member 43 from the open position to the restricting position.

[0049] Also, when the lock shaft 55 enters the notch 39 in this way, the movement of the lock gear 51 is restricted. However, since the drive gear 41 continues to rotate, the lock gear 51 continues to rotate while its movement is restricted. Note that since the lock shaft 55 is rotatable with respect to the lock gear 51, it enters the notch 39 without rotating.

[0050] Also, the rotation of the link shaft 53 is restricted by the regulating piece 65 of the link shaft 53 abutting against the paper feeding unit 11 (see FIG. 4).

[0051] In this way, during the driving of the main motor 19, that is, during the image forming operation, the lock shaft 55 remains inserted into the notch 39, and the pulling out from the cassette housing portion 7 of the paper feeding cassette 5 is restricted.

[0052] When the image forming operation is completed or stopped, the driving of the main motor 19 stops, and the rotation of the driving gear 41 also stops. Then, the rotation of the lock gear 51 also stops via the idle gear 45. On the other hand, since the link shaft 53 is rotatable with respect to the rotation shaft 41a of the driving gear 41, the link shaft 53 is urged by the torsion coil spring and returns to the initial posture. That is, as shown in FIG. 6C, while the lock gear 51 meshes with the driving gear 41 and rotates in the clockwise direction (see arrow D), it moves in the clockwise direction along the circumferential direction centered on the rotation shaft 41a of the driving gear 41. That is, the lock shaft 55 moves in the clockwise direction along the circumferential direction centered on the rotation shaft 41a of the driving gear 41 (see arrow E). As a result, the lock shaft 55 moves from the restricted position (see FIGS. 6B and 7B) to the release position (see FIGS. 6A and 7A), and the pulling out from the cassette housing portion 7 of the paper feeding cassette 5 becomes possible.

[0053] Also, there may be a case where the main motor 19 is driven even when the paper feeding cassette 5 is pulled out, such as during manual paper feeding. In such a case, similar to when the paper feeding cassette 5 is accommodated, the driving gear 41 rotates by the driving of the main motor 19 and the link shaft 53 rotates from the initial posture. However, the rotation of the link shaft 53 is restricted by the regulating piece 65 of the link shaft 53 abutting against the paper feeding unit 11 (see FIG. 4). That is, since the link shaft 53 does not rotate from the predetermined posture, the link shaft 53 and the lock shaft 55 do not interfere with the adjacent members.

[0054] As described above, according to the first embodiment of the present invention, when the paper feed cassette 5 is housed in the cassette housing portion 7 and the image forming operation is executed, the pulling out of the paper feed cassette 5 is automatically restricted. On the other hand, when the image forming operation stops, the paper feed cassette 5 can be pulled out. Therefore, it is possible to reduce paper jams and paper conveyance failures caused by pulling out the paper feed cassette 5 during the image forming operation.

[0055] Specifically, when the paper feed cassette 5 is housed in the cassette housing portion 7 and the image forming operation is executed, the restricting member 43 supported by the apparatus main body 3 engages with the notch 39 of the paper feed cassette 5 housed in the cassette housing portion 7, and the pulling out of the paper feed cassette 5 from the cassette housing portion 7 is restricted. The restricting member 43 moves by starting the drive of the main motor 19 and engages with the notch 39 of the paper feed cassette 5. When the drive of the main motor 19 stops, the restricting member 43 is automatically separated from the notch 39 of the paper feed cassette 5 by the torsion coil spring 81. Since the restricting member 43 moves in response to the drive of the main motor 19 in this way, the movement of the restricting member 43 can be surely associated with the image forming operation.

[0056] Further, even when the main motor 19 is driven in a state where the paper feed cassette 5 is not housed in the cassette housing portion 7, the movement of the restricting member 43 from the predetermined position is restricted, so that the restricting member 43 does not interfere with the adjacent members.

[0057] Next, the restricting mechanism 21 according to the second embodiment will be described with reference to FIGS. 8 and 9. FIG. 8 is a plan view showing the paper feed cassette 5 and the restricting mechanism 21, and FIG. 9 is a perspective view showing the paper feed cassette 5 and the restricting mechanism 21. In FIG. 9, the cover plate is not shown. The configuration of the paper feed cassette 5 is the same as that of the first embodiment. The restricting mechanism 21 is also composed of a drive gear 41 driven by the drive of the main motor 19 and a restricting member 43 that is driven by the drive gear 41 and moves, as in the first embodiment.

[0058] First, the drive gear 41 will be described. - The main motor 19 is supported on the outer surface (the side opposite to the cassette storage section 7) of the right side plate 3a of the apparatus main body 3, behind the paper feed section 11. The drive shaft 19a of the main motor 19 penetrates the right side plate 3a and protrudes to the inner side (the side of the cassette storage section 7) of the right side plate 3a. A gear is formed along the circumferential direction at the end of the protruding drive shaft 19a. Further, the drive gear 41 is rotatably supported on the inner surface of the right side plate 3a, behind the main motor 19.

[0059] The drive gear 41 is a two-stage gear having a large-diameter lower-stage gear 41b and a drive hub gear 41c having a smaller diameter than the lower-stage gear 41b. The lower-stage gear 41b of the drive gear 41 meshes with the gear of the drive shaft 19a.

[0060] Next, the regulating member 43 will be described with reference to FIGS. 10A and 10B. FIG. 10A is a perspective view showing the regulating member 43, and FIG. 10B is a perspective view showing the lock shaft 93. As shown in FIG. 10A, the regulating member 43 is composed of a driven hub gear 91 and a lock shaft 93.

[0061] The driven hub gear 91 is a hub gear that can mesh with the drive hub gear 41c of the drive gear 41. The driven hub gear 91 has a cylindrical rotating shaft 91a.

[0062] The lock shaft 93 will be described with reference to FIG. 10B. The lock shaft 93 has, in order from the front end side to the rear end side, a front end side small diameter portion 101, a large diameter portion 103, a middle diameter portion 105, a rear end side small diameter portion 107, and a D cut portion 109. The middle diameter portion 105 has an outer diameter equal to the inner diameter of the rotation shaft 91a of the driven spur gear 91 and a length equal to that of the rotation shaft 91a. At the boundary between the front end side small diameter portion 101 and the large diameter portion 103, a front end side end face 111 is formed, and at the boundary between the large diameter portion 103 and the middle diameter portion 105, a central side end face 113 is formed. Further, a rear end side end face 115 is formed at the boundary between the rear end side small diameter portion 107 and the D cut portion 109. Also, a central side groove 117 along the circumferential direction is formed at the boundary between the middle diameter portion 105 and the rear end side small diameter portion 107. Further, a rear end side groove 119 along the circumferential direction is also formed at the end of the D cut portion 109.

[0063] The lock shaft 93 is passed through the rotation shaft 91a of the driven spur gear 91 from the rear end side (the side of the D cut portion 109), and the rotation shaft 91a of the driven spur gear 91 is fitted into the middle diameter portion 105 of the lock shaft 93. The end face on the front end side of the driven spur gear 91 abuts against the central side end face 113 of the lock shaft 93. Also, a front end side stopper 121 is engaged with the central side groove 117 of the lock shaft 93. Thereby, the driven spur gear 91 is supported so as not to be movable and rotatable with respect to the lock shaft 93, and the regulating member 43 is constituted.

[0064] The regulating member 43 configured as described above is disposed between the right side plate 3a of the apparatus main body 3 and a cover plate 3b provided in parallel with the right side plate 3a inside the right side plate 3a (on the side of the cassette accommodating portion 7) as shown in FIGS. 8 and 9, and the driven spur gear 91 is supported in a state of meshing with the driving spur gear 41c of the driving gear 41. Specifically, openings arranged coaxially along a direction perpendicular to the right side plate 3a are formed in the right side plate 3a and the cover plate 3b. The opening of the right side plate 3a has a cross-sectional shape equivalent to the cross-sectional shape of the D cut portion 109 of the lock shaft 93, and the opening of the cover plate 3b has a diameter equivalent to the diameter of the front end side small diameter portion 101 of the lock shaft 93.

[0065] The small-diameter portion 101 at the tip side of the lock shaft 93 is inserted into the opening of the cover plate 3b and protrudes from the opening into the cassette housing portion 7. On the other hand, the D-cut portion 109 of the lock shaft 93 is inserted into the opening of the right side plate 3a and protrudes outward from the opening. The rear end side stopper 123 is engaged with the rear end side groove 119 of the D-cut portion 109 protruding from the opening. By supporting the lock shaft 93 in this way, the regulating member 43 is movable along a direction perpendicular to the right side plate 3a. Further, the rotation of the lock shaft 93 is restricted by the D-cut portion 109 of the lock shaft 93 and the D-shaped opening of the right side plate 3a.

[0066] Also, between the cover plate 3b and the driven spur gear 91, a coil spring 125 is externally fitted to the lock shaft 93 (the tip side small-diameter portion 101 and the large-diameter portion 103). The coil spring 125 biases the driven spur gear 91, that is, the regulating member 43, outward (the side opposite to the cassette housing portion 7) with respect to the cover plate 3b. The regulating member 43 moves along the axial direction of the rotation shaft 91a until the rear end side end face 115 of the lock shaft 93 abuts against the right side plate 3a. Even when the regulating member 43 is biased by the coil spring 125, the small-diameter portion 101 at the tip side of the lock shaft 93 remains inserted into the opening of the cover plate 3b.

[0067] On the other hand, when the regulating member 43 is pushed inward (the side of the cassette housing portion 7) against the biasing force of the coil spring 125, the small-diameter portion 101 at the tip side of the lock shaft 93 protrudes from the opening into the cassette housing portion 7, and the tip side end face 111 of the lock shaft 93 abuts against the cover plate 3b. The lock shaft 93 is movable in the direction of the cassette housing portion 7 until the rear end side stopper 123 abuts against the right side plate 3a or until the tip side end face 111 abuts against the cover plate 3b.

[0068] The operation of restricting the pulling out of the paper feed cassette 5 by the restricting mechanism 21 according to the second embodiment having the above configuration will be described with reference to FIGS. 11A and 11B. FIGS. 11A and 11B are cross-sectional views showing the regulating member 43.

[0069] As shown in FIG. 11A, when the paper feed cassette 5 is not housed in the cassette housing portion 7, the regulating member 43 is biased outward by the coil spring 125, the rear end side end surface 115 of the lock shaft 93 abuts against the right side plate 3a, and the small diameter portion 101 on the front end side slightly protrudes from the opening of the cover plate 3b into the cassette housing portion 7. Specifically, the small diameter portion 101 on the front end side protrudes to such an extent that it does not reach the right side plate 35 of the paper feed cassette 5 when the paper feed cassette 5 is housed in the cassette housing portion 7. The driven bevel gear 91 meshes with the drive bevel gear 41c of the drive gear 41.

[0070] When the paper feed cassette 5 is housed in the cassette housing portion 7 and the image forming operation is executed, the main motor 19 starts to be driven. When the main motor 19 is driven, the drive gear 41 rotates, and the driven bevel gear 91 of the regulating member 43 that meshes with the drive bevel gear 41c of the drive gear 41 rotates. Due to the rotation of both bevel gears 41c and 91, a thrust force is generated along the axial direction of the rotation shaft 91a on the driven bevel gear 91, and the driven bevel gear 91 moves in the direction of the cassette housing portion 7 with respect to the drive bevel gear 41c against the biasing force of the coil spring 125.

[0071] Then, the lock shaft 93 moves together with the driven bevel gear 91 (see arrow F in FIG. 11B), and eventually, the small diameter portion 101 on the front end side of the lock shaft 93 enters the notch 39 formed in the right side plate 35 of the paper feed cassette 5. As a result, the paper feed cassette 5 cannot be pulled out from the cassette housing portion 7 by the regulating member 43 provided in the apparatus main body 3. In this way, the regulating member 43 moves from the release position (see FIG. 11A) where it is separated from the paper feed cassette 5 and permits the pulling out of the paper feed cassette 5 to the regulating position (see FIG. 11B) where it engages with the paper feed cassette 5 and restricts the pulling out of the paper feed cassette 5.

[0072] As described above, the regulating member 43 moves inward until the tip-side end face 111 of the lock shaft 93 abuts against the cover plate 3b. Since the drive gear 41 continues to rotate while the image forming operation is being executed, the driven crossbar gear 91 that meshes with the drive crossbar gear 41c also continues to rotate, generating a thrust force toward the cassette housing portion 7. However, since the movement of the lock shaft 93 is regulated as described above, the driven crossbar gear 91 does not move inward and continues to rotate with respect to the lock shaft 93.

[0073] The lock shaft 93 moves in the direction of the cassette housing portion 7 from the position where the rear-end side end face 115 abuts against the right side plate 3a (see FIG. 11A) to the position where the tip-side end face 111 abuts against the cover plate 3b (see FIG. 11B). That is, the tip-side end face 111 of the lock shaft 93 is an example of a stopper that positions the lock shaft 93 in the present invention at the position where it enters the notch 39, and the rear-end side end face 115 of the lock shaft 93 is an example of a stopper that positions the lock shaft 93 in the present invention at a position separated from the notch 39. Alternatively, the lock shaft 93 moves in the direction of the cassette housing portion 7 until the rear-end side stopper 123 abuts against the right side plate 3a. Therefore, the rear-end side stopper 123 is also an example of a stopper that positions the lock shaft 93 in the present invention at the position where it enters the notch 39.

[0074] Thus, while the main motor 19 is driving, that is, during the image forming operation, the lock shaft 93 remains inserted into the notch 39, and the drawing out of the paper feed cassette 5 from the cassette housing portion 7 is regulated.

[0075] When the image forming operation ends or stops, the driving of the main motor 19 stops, the rotation of the driving spur gear 41c stops, and the rotation of the driven spur gear 91 also stops. Then, since the thrust applied to the driven spur gear 91 disappears, the driven spur gear 91 is biased by the coil spring 125 and moves outward (to the side opposite to the cassette housing portion 7). At this time, the driven spur gear 91 meshes with the driving spur gear 41c and moves while rotating with respect to the driving spur gear 41c. As a result, the regulating member 43 moves from the regulating position (see FIG. 11B) to the open position (see FIG. 11A), and the feeding cassette 5 can be pulled out from the cassette housing portion 7.

[0076] Also, when the main motor 19 is driven even in a state where the feeding cassette 5 is pulled out, such as during manual feeding, the driving gear 41 rotates by the driving of the main motor 19 and the regulating member 43 moves to the regulating position, similar to the case when the feeding cassette 5 is housed. However, as described above, the movement of the lock shaft 93 is restricted by the contact of the tip end side end surface 111 of the lock shaft 93 with the cover plate. Also, the movement of the lock shaft 93 is restricted by the contact of the rear end side stopper 123 fixed to the lock shaft 93 with the right side plate 3a. Therefore, the lock shaft 93 is maintained at the regulating position. Also, when the driving of the main motor 19 stops, it is biased by the coil spring 125 as described above and moves to the open position.

[0077] As described above, also according to the second embodiment of the present invention, when the feeding cassette 5 is housed in the cassette housing portion 7 and the image forming operation is executed, the pulling out of the feeding cassette 5 is automatically restricted. On the other hand, when the image forming operation stops, the feeding cassette 5 can be pulled out. Therefore, paper jams and paper conveyance failures caused by the feeding cassette 5 being pulled out during the image forming operation can be reduced.

[0078] Specifically, a regulation member 43 supported by the apparatus main body 3 engages with a notch 39 of a paper feed cassette 5 accommodated in the cassette accommodation section 7, thereby regulating the pulling out of the paper feed cassette 5 from the cassette accommodation section 7. In the first embodiment, the regulation member 43 moves along the circumferential direction centered on the rotation axis 51a of the lock gear 51 of the drive gear 41. However, in the second embodiment, the regulation member 43 moves along the axial direction of the rotation axis 91a of the driven hub gear 91 parallel to the rotation axis 41a of the drive gear 41. Therefore, according to the space that can be secured depending on the dimensions of the cassette accommodation section 7 and the configuration of the paper feed section 11, etc., the regulation member 43 of the first embodiment or the second embodiment can be selected.

[0079] In the second embodiment, the notch 39 of the paper feed cassette 5 may have an opening shape.

[0080] Furthermore, the description of the above embodiments of the present invention describes preferred embodiments in the image forming apparatus and the paper feed cassette according to the present invention, and thus may be subject to various technically preferable limitations. However, the technical scope of the present invention is not limited to these aspects unless there is a description specifically limiting the present invention.

Explanation of Reference Numerals

[0081] 1 Image forming apparatus 3 Apparatus main body 5 Paper feed cassette 13 Image forming section 19 Main motor (drive source) 21 Regulation mechanism 39 Notch 41 Drive gear 43 Regulation member 51 Lock gear 53 Link shaft 55 Lock shaft 65 Regulation piece 81 Torsion coil spring (biasing member) 91 Driven hub gear 93 Lock shaft 111 Tip side end face (stopper) 115 Rear end side end face (stopper) 123 Rear end side stopper (stopper) 125 Coil spring (biasing member)

Claims

1. A paper feed cassette provided so as to be pullable out from the apparatus main body and accommodating paper on which an image is to be formed, A drive source that generates a driving force for driving an image forming unit that forms an image on the paper fed from the paper feed cassette, A regulating mechanism that regulates the pulling out of the paper feed cassette from the apparatus main body, and comprising: The regulating mechanism is: A regulating member supported by the apparatus main body, engaging with the paper feed cassette, and movable between a regulating position for regulating the pulling out of the paper feed cassette and an open position spaced apart from the paper feed cassette for permitting the pulling out of the paper feed cassette, A driving member driven by the driving force generated by the drive source to move the regulating member from the open position to the regulating position, An urging member that moves the regulating member from the regulating position to the open position when the drive source stops, and the image forming apparatus is characterized by comprising these.

2. The image forming apparatus according to claim 1, wherein the driving member is a driving gear that rotates by the driving force generated by the drive source.

3. The image forming apparatus according to claim 2, wherein the regulating member moves along a circumferential direction centered on the rotation axis of the driving gear.

4. The paper feed cassette has a notch, The regulating member is: A lock gear that meshes with the driving gear, A link shaft rotatably supported by the rotation shafts of the driving gear and the lock gear and connecting both rotation shafts in a state where the driving gear and the lock gear are meshed with each other, A lock shaft provided coaxially with the rotation axis of the lock gear, and comprising: When the driving gear rotates in one direction by the drive source, the lock gear rotates in a direction opposite to the one direction and moves in the one direction along the circumferential direction centered on the rotation axis of the driving gear, and the lock shaft enters the notch, whereby the pulling out of the paper feed cassette from the apparatus main body is regulated. The image forming apparatus according to claim 3 is characterized by this.

5. The urging member is a torsion coil spring having a coil portion and two arm portions, The coil portion is externally fitted to the rotation axis of the driving gear, one of the arm portions is fixed to the apparatus main body, and the other arm portion is fixed to the link shaft. When the drive source stops driving and the drive gear stops rotating, the link shaft is biased by the torsion coil spring and rotates about the rotation axis of the lock gear, and the lock shaft moves away from the notch. The image forming apparatus according to claim 4, characterized in that.

6. The image forming apparatus according to claim 4, wherein the link shaft includes a regulating piece that abuts against the apparatus main body and regulates rotation in the one direction along the circumferential direction from a predetermined position.

7. The image forming apparatus according to claim 2, wherein the regulating member moves along a direction parallel to the rotation axis of the drive gear.

8. The paper feed cassette has a notch, The drive gear has a drive hub gear that rotates by a driving force generated by the drive source, The regulating member, A driven hub gear that meshes with the drive hub gear of the drive gear, A lock shaft that is movably integrated with the driven hub gear on the rotation axis of the driven hub gear and is rotatable with respect to the driven hub gear. When the drive hub gear rotates in one direction by the drive source, the driven hub gear rotates in a direction opposite to the one direction and moves in one direction along the axial direction of the rotation axis. The lock shaft moves in the one direction together with the driven hub gear and is inserted into the opening of the paper feed cassette, thereby restricting the paper feed cassette from being pulled out from the apparatus main body. The image forming apparatus according to claim 7, characterized in that.

9. A cover plate provided on one direction side along the axial direction of the rotation axis of the driven hub gear, The biasing member is a coil spring externally fitted to the lock shaft, The coil spring is disposed between the driven hub gear and the cover plate, and biases the driven hub gear in the other direction opposite to the one direction. The image forming apparatus according to claim 8, characterized in that.

10. The image forming apparatus according to claim 8, further comprising stoppers for positioning the lock shaft at a position where it enters the notch of the paper feed cassette and a position where it is separated from the notch, respectively.

Images