Sheet storage device and image forming device including the same

Abstract

To suppress the unintended lowering of a lift plate on which a sheet is placed.SOLUTION: A sheet storage device includes: a lift plate; a push-up member; a transmission mechanism which at least includes a first gear, a second gear engaged with the first gear, and a third gear engaged with the second gear, and which transmits the power of a motor to the push-up member; and a rotation restriction member. The first gear includes a support part. The rotation restriction member includes: an annular part in which the support part is fitted and which can slide in the direction rotating with respect to the outer peripheral surface of the support part; and a protrusion part protruding outward in the radial direction from the annular part and capable of engaging with the second gear. The protrusion part has a shape which cannot pass a gap between the second gear and the annular part, and is positioned further on the downstream side, than the gap, in the rotation direction of the second gear in the case of rotating by the power of the motor.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a sheet storage device and an image forming apparatus including the same. [Background technology]

[0002] A conventional sheet storage device includes a lift plate that can be raised and lowered. Sheets are placed on the lift plate. The lift plate rises to hold the height position of the top sheet on the lift plate at a predetermined position. Such a sheet storage device is disclosed in, for example, Patent Document 1.

[0003] A conventional sheet storage device includes a feed roller that contacts a sheet at a predetermined position from above. The feed roller rotates while in contact with the sheet, thereby feeding the sheet. If the top sheet on the lift plate is not at the predetermined position, the feed roller rotates idly and the sheet is not fed. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 8-217266 Summary of the Invention [Problem to be solved by the invention]

[0005] For example, the lift plate is connected to a gear train including multiple gears. The lift plate is raised by transmitting the power of a motor through the gear train. If the lift plate is unintentionally lowered due to the weight of the lift plate and the weight of the sheets on the lift plate, a feeding failure such as a failure to feed the sheets from the sheet storage device occurs.

[0006] The present invention has been made to solve the above-mentioned problems, and aims to provide a sheet storage device that can prevent the lift plate on which the sheets are placed from unintentionally descending, and an image forming apparatus equipped with the same. [Means for solving the problem]

[0007] In order to achieve the above object, a sheet storage device according to a first aspect of the present invention includes a lift plate on which a sheet is placed, a push-up member rotatably supported below the lift plate and configured to push up the lift plate by rotating in a lift-up direction when the power of a motor is transmitted to the push-up member, a transmission mechanism including at least a first gear rotated in one direction by the power of the motor, a second gear meshing with the first gear, and a third gear meshing with the second gear, and configured to transmit the power of the motor to the push-up member, and a rotation restricting member that restricts the rotation of the push-up member in a direction opposite to the lift-up direction. The first gear has a cylindrical support part with the central axis of the first gear as the cylindrical axis. The rotation restricting member has an annular part into which the support part is fitted and which is slidable in a rotating direction relative to the outer circumferential surface of the support part, and a protruding part that protrudes radially outward from the annular part and is engageable with the second gear. The protrusion has a shape that prevents it from passing through the gap between the second gear and the annular portion in a direction perpendicular to the axial direction, and is located downstream of the gap in the direction of rotation of the second gear when rotated by the power of the motor.

[0008] An image forming apparatus according to a second aspect of the present invention includes the sheet storage device described above, and transports a sheet to print an image on the sheet. Effect of the Invention

[0009] According to the configuration of the present invention, it is possible to prevent the lift plate on which the sheet is placed from lowering unintentionally. [Brief description of the drawings]

[0010] [Figure 1] 1 is a schematic diagram of an image forming apparatus including a sheet storage device according to an embodiment. [Diagram 2] 1 is a plan view of a gear train connected to a push-up member of a sheet storage device according to an embodiment, as viewed from an axial direction. [Diagram 3] 2 is a perspective view of a first gear and its periphery of the sheet storage device according to the embodiment. FIG. [Figure 4] 4 is a cross-sectional perspective view of a first gear and its periphery of the sheet storage device according to the embodiment. FIG. [Diagram 5] 4 is a perspective view of a rotation restricting member of the sheet storage device according to the embodiment. FIG. [Figure 6] 2 is a perspective view of a rotation restricting member and its periphery in the sheet storage device according to the embodiment. FIG. [Figure 7] 11A and 11B are diagrams illustrating a state in which the switching mechanism of the sheet storage device according to the embodiment transmits power of a motor. [Figure 8] 11A and 11B are diagrams illustrating a state in which the switching mechanism of the sheet storage device according to the embodiment cuts off the power transmission of the motor. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] 1 to 8, a sheet storage device 100 according to an embodiment of the present invention and an image forming apparatus 1000 including the same will be described below. The image forming apparatus 1000 is installed on a floor surface. The direction perpendicular to the floor surface (flat surface) on which the image forming apparatus 1000 is installed corresponds to the up-down direction.

[0012] <Configuration of Image Forming Apparatus> The image forming apparatus 1000 of this embodiment is a printer. The image forming apparatus 1000 is capable of executing a print job. The image forming apparatus 1000 prints an image on a sheet S by executing the print job. The printing method of the image forming apparatus 1000 is, for example, an electrophotographic method. Note that the printing method of the image forming apparatus 1000 may also be an inkjet method.

[0013] The image forming apparatus 1000 includes a sheet storage device 100. The sheet storage device 100 stores sheets S to be used in a print job. For example, the sheets S are paper (i.e., made of paper). The image forming apparatus 1000 transports the sheets S stored in the sheet storage device 100 along a transport path, and prints an image on the sheets S during transport. In FIG. 1, the transport path for the sheets S is diagrammatically indicated by a dashed arrow. The direction indicated by the arrow is the sheet transport direction.

[0014] Hereinafter, the direction perpendicular to the sheet conveying direction and perpendicular to the up-down direction may be referred to as the width direction. In Fig. 1, the direction perpendicular to the paper surface is the width direction. For example, Fig. 1 corresponds to a view of the image forming apparatus 1000 seen from the front. In other words, the width direction is also the front-rear direction.

[0015] The image forming apparatus 1000 includes a feed roller 1001. The feed roller 1001 is supported rotatably about an axis extending in the width direction. The feed roller 1001 feeds the sheet S stored in the sheet storage device 100 to a conveying path. The feed roller 1001 comes into contact with the sheet S stored in the sheet storage device 100 from above and rotates. This causes the sheet S to be fed from the sheet storage device 100 to the conveying path.

[0016] The image forming apparatus 1000 includes a pair of registration rollers 1002. The pair of registration rollers 1002 is supported rotatably around an axis extending in the width direction. The pair of registration rollers 1002 includes a pair of rollers that are in pressure contact with each other. The pair of registration rollers 1002 nip the sheet S fed from the feed roller 1001 and rotate. In this way, the pair of registration rollers 1002 transport the sheet S. One of the pair of registration rollers 1002 is a drive roller that is rotated by power transmitted from a motor M, and the other is a driven roller that is rotated by the one registration roller.

[0017] The image forming apparatus 1000 includes an image forming unit 1003. The image forming unit 1003 includes a photosensitive drum 1003a and a transfer roller 1003b. The photosensitive drum 1003a and the transfer roller 1003b are each supported so as to be rotatable about an axis extending in the width direction. The photosensitive drum 1003a and the transfer roller 1003b are in pressure contact with each other. The photosensitive drum 1003a and the transfer roller 1003b nip the sheet S sent from the pair of registration rollers 1002 and rotate. In this way, the image forming unit 1003 transports the sheet S.

[0018] The image forming unit 1003 further includes a charging device, an exposure device, and a developing device, although not shown. The charging device charges the peripheral surface of the photoconductor drum 1003a. The exposure device forms an electrostatic latent image on the peripheral surface of the photoconductor drum 1003a. The developing device develops the electrostatic latent image on the peripheral surface of the photoconductor drum 1003a into a toner image. The photoconductor drum 1003a nips the sheet S between itself and the transfer roller 1003b, and transfers the toner image to the sheet S by rotating together with the transfer roller 1003b.

[0019] The image forming apparatus 1000 includes a pair of fixing rollers 1004. The pair of fixing rollers 1004 is supported so as to be rotatable around an axis extending in the width direction. The pair of fixing rollers 1004 includes a heating roller and a pressure roller. The heating roller has a built-in heater. The pressure roller is in pressure contact with the heating roller, and the pair of fixing rollers 1004 nips and rotates the sheet S sent from the image forming unit 1003. That is, the pair of fixing rollers 1004 applies heat and pressure to the sheet S. As a result, the pair of fixing rollers 1004 fixes the toner image transferred to the sheet S to the sheet S. The sheet S is then discharged to the discharge tray ET.

[0020] <Configuration of the Sheet Storage Device> The sheet storage device 100 includes a sheet cassette CA. Sheets S are stored in the sheet cassette CA. The sheet cassette CA is detachable from the main body of the image forming apparatus 1000. When the sheets S are removed from the sheet cassette CA due to the execution of a print job, the sheet cassette CA is pulled out from the main body of the apparatus, and after the sheets S are stored in the sheet cassette CA, the sheet cassette CA is returned to the main body of the apparatus.

[0021] The sheet storage device 100 includes a lift plate 101. The lift plate 101 is disposed in a sheet cassette CA. By storing a sheet S in the sheet cassette CA, the sheet S is placed on the lift plate 101. The lift plate 101 is rotatable about an axis extending in the width direction. The lift plate 101 rotates around an end portion on the upstream side in the sheet feeding direction as a fulcrum such that an end portion on the downstream side in the sheet feeding direction swings up and down. In FIG. 1, the direction from the left side to the right side of the drawing is the sheet feeding direction.

[0022] During execution of a print job, the lift plate 101 repeatedly rotates in a direction in which the end portion on the upstream side in the sheet feeding direction rises and stops rotating. This allows the lift plate 101 to maintain contact of the feed roller 1001 with the uppermost sheet S on the lift plate 101. Even if the number of sheets S on the lift plate 101 decreases, the lift plate 101 rises, thereby maintaining a state in which the sheets S can be fed from the sheet cassette CA to the conveying path.

[0023] The sheet storage device 100 includes a push-up member 102. The push-up member 102 is disposed in the sheet cassette CA. The push-up member 102 is supported below the lift plate 101 so as to be rotatable around an axis extending in the width direction. The push-up member 102 rotates with an end portion on the upstream side in the sheet feeding direction as a fulcrum so as to swing an end portion on the downstream side in the sheet feeding direction up and down. The push-up member 102 pushes up the lift plate 101 by rotating in the lift-up direction. Note that the push-up member 102 may rotate with an end portion on the downstream side in the sheet feeding direction as a fulcrum so as to swing an end portion on the upstream side in the sheet feeding direction up and down. Regardless of the rotating direction of the push-up member 102, the push-up member 102 can push up the lift plate 101.

[0024] The sheet storage device 100 receives the power of a motor M that rotates the pair of registration rollers 1002. The push-up member 102 rotates in the lift-up direction by the power of the motor M being transmitted thereto. However, this is not limited thereto. The push-up member 102 may rotate in the lift-up direction by the power of a dedicated lift-up motor (not shown) being transmitted thereto.

[0025] <Rotation of the lift-up member in the lift-up direction> The sheet storage device 100 includes a gear train that transmits the power of the motor M to the rotation shaft 102a of the push-up member 102. The gear train of the sheet storage device 100 will be described below with reference to Figs. 2 to 4. All of the gears of the sheet storage device 100 are rotatable around an axis that extends in the width direction. That is, all of the gears of the sheet storage device 100 have an axial direction that is the width direction.

[0026] In the following description, the rotation direction of each gear of the sheet storage device 100 is based on the case viewed from one side of the axial direction. In the following description, the counterclockwise direction may be simply referred to as one direction and the clockwise direction may be simply referred to as the other direction with respect to the rotation direction of each gear of the sheet storage device 100.

[0027] The sheet storage device 100 includes a first gear 1 made of resin. Specifically, the sheet storage device 100 includes a cylindrical member 10 made of resin that is integrally formed with the first gear 1. The cylindrical member 10 (i.e., the first gear 1) is supported rotatably about the axis of a shaft 10A extending in the width direction. The cylindrical member 10 is a stepped cylindrical member. The cylindrical member 10 has a small diameter portion and a large diameter portion whose outer diameter is larger than that of the small diameter portion. The first gear 1 is provided on the outer circumferential surface of the small diameter portion of the cylindrical member 10.

[0028] The cylindrical member 10 has a large diameter portion on one side in the axial direction (i.e., the cylinder axis direction) relative to a small diameter portion where the first gear 1 is provided. In other words, the first gear 1 has a cylindrical portion (i.e., a large diameter portion) with an outer diameter larger than that of the first gear 1 on one side in the axial direction. The cylindrical portion on one side in the axial direction of the first gear 1 serves as a support portion 11, as will be described in detail later.

[0029] The first gear 1 rotates in one direction by the power of the motor M. When the first gear 1 rotates in one direction, the push-up member 102 rotates in the lift-up direction.

[0030] The sheet storage device 100 includes a second gear 2 made of resin. The second gear 2 meshes with the first gear 1. For example, the second gear 2 has its rotation axis lower than the rotation axis of the first gear 1 (i.e., the shaft 10A). When the first gear 1 receives power from a motor M and rotates in one direction, the second gear 2 rotates in the other direction.

[0031] The second gear 2 is a stepped gear. The second gear 2 is a two-stage gear. The second gear 2 has a portion that meshes with the first gear 1 as an input gear 21. The second gear 2 has a portion that meshes with a third gear 3 (described later) as an output gear 22. A cylindrical boss portion protrudes from the input gear 21 toward one side in the axial direction, and the output gear 22 is provided on the outer circumferential surface of the boss portion. In other words, the outer diameter of the input gear 21 is larger than the outer diameter of the output gear 22.

[0032] The sheet storage device 100 includes a transmission mechanism (reference numerals omitted) including a plurality of gears. The transmission mechanism transmits the power of the motor M to the rotating shaft 102a of the push-up member 102, thereby rotating the push-up member 102 in the lift-up direction. The transmission mechanism includes at least a third gear 3 made of resin that meshes with the second gear 2. The third gear 3 meshes with an output gear 22. When the second gear 2 rotates in the other direction, the third gear 3 rotates in one direction.

[0033] The transmission mechanism includes a fourth gear 4 and a fifth gear 5, each made of resin. The fourth gear 4 meshes with the third gear 3. When the third gear 3 rotates in one direction, the fourth gear 4 rotates in the other direction. The fifth gear 5 meshes with the fourth gear 4. When the fourth gear 4 rotates in the other direction, the fifth gear 5 rotates in one direction. The number of gears constituting the transmission mechanism is not particularly limited.

[0034] The rotation shaft 102a of the push-up member 102 is connected to the fifth gear 5 via a resin gear (not shown). This allows the power of the motor M to be transmitted to the rotation shaft 102a of the push-up member 102. By transmitting the power of the motor M, the push-up member 102 rotates in the lift-up direction and pushes up the lift plate 101.

[0035] The sheet storage device 100 also includes a switching mechanism 7. The switching mechanism 7 switches between transmitting and blocking the power from the motor M to the first gear 1. When the power is transmitted from the motor M to the first gear 1, the first gear 1 rotates in one direction. When the power transmission from the motor M to the first gear 1 is blocked, the first gear 1 does not rotate in one direction. If the first gear 1 does not rotate in one direction, the push-up member 102 does not rotate in the lift-up direction, and the lift plate 101 does not rise.

[0036] The configuration of the switching mechanism 7 is not particularly limited as long as it is possible to switch between transmitting and blocking power from the motor M to the first gear 1. For example, the switching mechanism 7 includes a planetary gear mechanism. The configuration of the switching mechanism 7 will be described below. Note that the configuration of the switching mechanism 7 described below is one example. A mechanism including an electromagnetic clutch can also be used as the switching mechanism 7.

[0037] The switching mechanism 7 has a planetary gear mechanism connected to the first gear 1. Specifically, the switching mechanism 7 includes an internal gear 71. The internal gear 71 is supported rotatably around the axis of the shaft 10A. The internal gear 71 is provided on the inner circumferential surface of a large diameter portion of the cylindrical member 10 having the first gear 1. In other words, the cylindrical member 10 has the internal gear 71 integrally therewith. Note that since the internal gear 71 is the same member as the cylindrical member 10, the internal gear 71 is made of resin.

[0038] The switching mechanism 7 includes a resin sun gear 72. The sun gear 72 is supported rotatably about the axis of the shaft 10A. The sun gear 72 is disposed inside the internal gear 71 (i.e., inside the large diameter portion of the cylindrical member 10).

[0039] The switching mechanism 7 includes a plurality of planetary gears 73 each made of resin. The plurality of planetary gears 73 are disposed inside the internal gear 71 (i.e., inside the large diameter portion of the cylindrical member 10) so as to surround the sun gear 72. The plurality of planetary gears 73 mesh with the sun gear 72 and also mesh with the internal gear 71.

[0040] The switching mechanism 7 includes a planetary carrier 74 made of resin. The planetary carrier 74 is supported rotatably around the axis of the shaft 10A. The planetary carrier 74 rotatably supports a plurality of planetary gears 73. This allows the plurality of planetary gears 73 to revolve around the sun gear 72 while rotating on their own axes. The revolution of the plurality of planetary gears 73 around the sun gear 72 causes the planetary carrier 74 to rotate.

[0041] The planetary carrier 74 has a power input gear 730 integrally therewith. The power input gear 730 is rotatable around the axis of the shaft 10A. The power input gear 730 is disposed on one side in the axial direction with respect to the cylindrical member 10 (its large diameter portion). Of the planetary carrier 74, the portion supporting each planetary gear 73 is disposed inside the cylindrical member 10, while the portion having the power input gear 730 is disposed outside the cylindrical member 10. Since the power input gear 730 is the same member as the planetary carrier 74, the power input gear 730 is made of resin.

[0042] The power input gear 730 meshes with the drive gear 700 (see FIG. 2). The drive gear 700 is attached to the rotation shaft of the drive roller of the pair of registration rollers 1002 and rotates together with the drive roller. In other words, the drive gear 700 is the gear on the upstream side in the power transmission direction from the motor M to the rotation shaft 102a of the push-up member 102.

[0043] Here, the sun gear 72 has integrally therewith an engagement rotor 720 that is rotatable around the axis of the shaft 10A. The engagement rotor 720 rotates together with the sun gear 72. Because the sun gear 72 is integral with the engagement rotor 720, the sun gear 72 does not rotate when the engagement rotor 720 is in a non-rotatable state.

[0044] The engagement rotor 720 is disposed on one side in the axial direction with respect to the power input gear 730. The engagement rotor 720 has a boss portion that extends to the inside of the large diameter portion of the cylindrical member 10. The sun gear 72 is provided on the outer circumferential surface of the boss portion extending from the engagement rotor 720. As a result, the sun gear 72 is disposed inside the large diameter portion of the cylindrical member 10 and meshes with the multiple planetary gears 73. Note that since the engagement rotor 720 is the same member as the sun gear 72, the engagement rotor 720 is made of resin.

[0045] The engaging rotor 720 has a plurality of protrusions 721 on its outer circumferential surface that protrude radially outward. The plurality of protrusions 721 are arranged at intervals from one another in the rotational direction of the engaging rotor 720. In other words, the engaging rotor 720 has projections and recesses on its outer circumferential surface. In yet other words, the outer circumferential surface of the engaging rotor 720 is engageable with the claw member 75 described below.

[0046] During rotation of the power input gear 730, the engagement rotor 720 becomes non-rotatable (i.e., the sun gear 72 becomes non-rotatable), causing the first gear 1 to rotate in one direction. That is, the power of the motor M is transmitted to the first gear 1, causing it to rotate in one direction. As a result, the second gear 2 rotates in the other direction, and the third gear 3 rotates in one direction, causing the push-up member 102 to rotate in the lift-up direction. As a result, the lift plate 101 rises.

[0047] During rotation of the power input gear 730, the engagement rotor 720 becomes rotatable (i.e., the sun gear 72 becomes rotatable), and thus the power of the motor M is not transmitted to the first gear 1. In other words, the transmission of power from the motor M to the first gear 1 is interrupted. As a result, power for rotating the push-up member 102 in the lift-up direction is not transmitted to the rotating shaft 102a of the push-up member 102. At this time, the rotation of the first gear 1 is not locked, and it becomes rotatable in the other direction opposite to the one direction.

[0048] In this configuration, when it is desired to raise the lift plate 101 (i.e., when it is desired to rotate the push-up member 102 in the lift-up direction), it is sufficient to make the engagement rotor 720 non-rotatable. When it is desired to stop the lift plate 101 from rising (i.e., when it is desired to stop the rotation of the push-up member 102 in the lift-up direction), it is sufficient to make the engagement rotor 720 rotatable.

[0049] Therefore, the switching mechanism 7 includes a claw member 75. The claw member 75 has a claw 750 that can engage with the engagement rotating body 720 (the unevenness on the outer circumferential surface thereof). The claw member 75 is supported rotatably in a direction approaching the engagement rotating body 720 and a direction moving away from the engagement rotating body 720.

[0050] Claw member 75 engages with engagement rotating body 720 by rotating in a direction approaching engagement rotating body 720. When claw 750 engages with any of the multiple protrusions 721, claw member 75 is brought into engagement with engagement rotating body 720. When claw member 75 rotates in a direction away from engagement rotating body 720, the engagement between engagement rotating body 720 and claw member 75 is released.

[0051] The switching mechanism 7 also includes a solenoid 76. The solenoid 76 includes a movable body 761 and a tension coil spring 762. The movable body 761 is connected to the claw member 75. When the position of the movable body 761 is displaced, the claw member 75 approaches the engagement rotating body 720 or moves away from the engagement rotating body 720. One end of the tension coil spring 762 is connected to the movable body 761.

[0052] The solenoid 76 generates a magnetic force to displace the position of the movable body 761 against the tensile force of the tension coil spring 762, and moves the claw member 75 in a direction approaching the engagement rotor 720. In other words, the solenoid 76 generates a magnetic force to engage the claw member 75 with the engagement rotor 720.

[0053] On the other hand, when the claw member 75 is moved in a direction away from the engagement rotor 720, the solenoid 76 stops generating a magnetic force. As a result, the claw member 75 moves in a direction away from the engagement rotor 720 due to the tensile force of the tension coil spring 762. In other words, the engagement between the engagement rotor 720 and the claw member 75 is released.

[0054] When the claw member 75 engages with the engagement rotor 720, the engagement rotor 720 becomes unrotatable, and the sun gear 72 becomes unrotatable. As a result, the first gear 1 rotates in one direction (i.e., the direction that rotates the push-up member 102 in the lift-up direction).

[0055] On the other hand, by releasing the engagement between the engagement rotor 720 and the pawl member 75, the engagement rotor 720 becomes rotatable, and the sun gear 72 becomes rotatable. As a result, the first gear 1 does not rotate in one direction. In other words, the power of the motor M is not transmitted to the first gear 1. At this time, the first gear 1 becomes rotatable in the other direction opposite to the one direction.

[0056] <Limiting rotation in the opposite direction to the lift-up direction of the lift-up member> The sheet storage device 100 includes a rotation restricting member 8 as shown in Fig. 5 and Fig. 6. The rotation restricting member 8 is made of resin. The rotation restricting member 8 restricts the rotation of the push-up member 102 in the direction opposite to the lift-up direction. The rotation restricting member 8 is supported by a cylindrical member 10. The rotation restricting member 8 restricts the rotation of the second gear 2 when the power transmission from the motor M to the first gear 1 is interrupted, thereby restricting the rotation of the push-up member 102 in the direction opposite to the lift-up direction.

[0057] The rotation restricting member 8 has an annular portion 81. The annular portion 81 is annular when viewed from the axial direction (i.e., the width direction). When viewed from the axial direction, the inner edge of the annular portion 81 is circular. The outer shape of the annular portion 81 when viewed from the axial direction is not particularly limited. For example, the annular portion 81 is annular when viewed from the axial direction.

[0058] The large diameter portion of the cylindrical member 10 is fitted into the annular portion 81, so that the rotation restricting member 8 is supported by the cylindrical member 10. In this configuration, the large diameter portion of the cylindrical member 10 serves as a support portion that supports the rotation restricting member 8. In the following description, the large diameter portion of the cylindrical member 10 is given the reference symbol 11 and is referred to as the support portion 11 (see FIGS. 3 and 4).

[0059] The large diameter portion of the cylindrical member 10 is a part of the first gear 1. That is, the first gear 1 has a cylindrical support portion 11 with its central axis serving as the cylindrical axis. The first gear 1 has the support portion 11 on one side in the axial direction.

[0060] Furthermore, the rotation restricting member 8 has a protruding portion 82 that protrudes radially outward from the annular portion 81. Radially outward is the direction from the inside to the outside of the annular portion 81 (i.e., the annular body). The protruding portion 82 has a plurality of protrusions that can engage with the output gear 22 of the second gear 2. The second gear 2 has a cylindrical engaging portion with its central axis as a cylindrical axis and with projections and recesses on its outer circumferential surface. The output gear 22 corresponds to the "engaging portion."

[0061] The rotation restricting member 8 is rotatable about the axis of the first gear 1. Specifically, the annular portion 81 is slidable about the axis of the first gear 1 relative to the outer circumferential surface of the support portion 11. A lubricant such as grease may be provided between the outer circumferential surface of the support portion 11 and the inner circumferential surface of the annular portion 81.

[0062] The annular portion 81 is disposed at a distance from the output gear 22 (its tip) in a direction perpendicular to the axial direction. That is, when viewed from the axial direction, there is a gap G between the output gear 22 and the annular portion 81. As a result, even if the annular portion 81 slides against the outer circumferential surface of the support portion 11 so as to rotate, the annular portion 81 does not interfere with the output gear 22.

[0063] However, the protruding portion 82 has a shape that prevents it from passing through the gap G in the direction perpendicular to the axial direction between the output gear 22 and the annular portion 81. As a result, the rotation restricting member 8 rotates about the axis of the first gear 1 as the annular portion 81 slides against the outer circumferential surface of the support portion 11, but stops rotating when the protruding portion 82 reaches the gap G.

[0064] Here, when viewed from the axial direction, the protruding portion 82 is located downstream of the gap G between the output gear 22 and the annular portion 81 in the rotation direction of the output gear 22 when rotated by the power of the motor M. This allows the rotation restricting member 8 to function to restrict the rotation of the push-up member 102 in the direction opposite to the lift-up direction.

[0065] A specific description will be given below with reference to Figures 7 and 8. In Figures 7 and 8, the rotation directions of the second to fifth gears 2 to 5 are indicated by bold arrows. Note that the first gear 1 is not shown in Figures 7 and 8.

[0066] When the power of the motor M is transmitted to the rotary shaft 102a of the push-up member 102 to rotate the push-up member 102 in the lift-up direction, the claw member 75 engages with the engagement rotor 720 as shown in Fig. 7. Therefore, the engagement rotor 720 stops rotating.

[0067] At this time, the first gear 1 rotates in one direction (counterclockwise). The second gear 2 rotates in the other direction (clockwise). The third to fifth gears 3 to 5 rotate in the directions of the corresponding arrows. As a result, the power of the motor M is transmitted to the rotating shaft 102a of the push-up member 102, and the push-up member 102 rotates in the lift-up direction. The lift plate 101 rises.

[0068] On the other hand, when the transmission of power from the motor M to the rotation shaft 102a of the push-up member 102 is interrupted, the engagement between the engagement rotor 720 and the claw member 75 is released as shown in Fig. 8. Therefore, the engagement rotor 720 is rotatable.

[0069] At this time, the first gear 1 stops rotating. As the first gear 1 stops rotating, the second gear 2 also stops rotating. The third to fifth gears 3 to 5 also stop rotating. As the engagement between the engagement rotor 720 and the claw member 75 is released, the first gear 1 becomes rotatable in the other direction.

[0070] Here, when the engagement between the engagement rotor 720 and the claw member 75 is released, the push-up member 102 tries to rotate in the direction opposite to the lift-up direction due to the weight of the lift plate 101 and the weight of the sheet S on the lift plate 101. At this time, the second to fifth gears 2 to 5 each try to rotate in the direction of the arrow in FIG. 8. The first gear 1 is in a state in which it can rotate in the other direction. Therefore, when the second gear 2 tries to rotate in one direction (the direction of the arrow in FIG. 8), the first gear 1 tries to rotate in the other direction.

[0071] If the second gear 2 rotates in one direction, the lift plate 101 moves down. As a result, the feed roller 1001 does not contact the sheet S on the lift plate 101, causing a feeding failure of the sheet S from the sheet storage device 100 to the conveying path.

[0072] Therefore, in this embodiment, the rotation restricting member 8 is disposed on the support portion 11 of the first gear 1. In this configuration, when the second gear 2 rotates in one direction (i.e., when the second gear 2 rotates in the opposite direction to the rotation direction when the second gear 2 rotates by the power of the motor M), the output gear 22 and the protruding portion 82 of the rotation restricting member 8 are engaged with each other, and in this state, the rotation restricting member 8 rotates around the axis of the first gear 1 with respect to the outer circumferential surface of the cylindrical member 10. After that, the protruding portion 82 reaches the gap G between the output gear 22 and the annular portion 81, but the protruding portion 82 cannot pass through the gap G. In other words, the rotation restricting member 8 stops rotating when the protruding portion 82 reaches the gap G. At this time, since the output gear 22 and the protruding portion 82 are engaged with each other, the second gear 2 does not rotate in one direction any further. If the second gear 2 does not rotate, the third to fifth gears 3 to 5 do not rotate either.

[0073] In this embodiment, this makes it possible to prevent the push-up member 102 from rotating in the direction opposite to the lift-up direction. In other words, it is possible to prevent the lift plate 101 on which the sheet S is placed from lowering unintentionally. As a result, it is possible to prevent abnormalities from occurring in the feeding of the sheet S from the sheet storage device 100.

[0074] In this embodiment, the rotation restricting member 8 is composed of only the components shown in FIG. 5. This makes it possible to prevent the structure from becoming complicated. For example, by arranging a worm wheel in the gear train, it is possible to brake the first gear 1 by utilizing friction loss. However, when a worm wheel is arranged in the gear train, the axial direction is changed, so the number of parts increases, the structure becomes complicated, and this leads to increased costs. Also, the drive loss increases when the push-up member 2 is rotated in the lift-up direction. On the other hand, by using the rotation restricting member 8, these inconveniences can be prevented.

[0075] In this embodiment, the rotation restricting member 8 is supported by fitting the support portion 11 into the annular portion 81. Here, the annular portion 81 is slidable in the direction of rotation relative to the outer circumferential surface of the support portion 11. In this configuration, when the first gear 1 rotates in one direction by the power of the motor M, the annular portion 81 displaces the rotation position in the direction in which the protrusion 82 moves away from the gap G due to frictional resistance between the annular portion 81 and the outer circumferential surface of the support portion 11 and the force received from the second gear 2. The force received by the annular portion 81 from the second gear 2 is the force of the output side gear 22 to rotate the protrusion 82. As a result, the rotation of the first gear 1 in one direction is not hindered by the protrusion 82.

[0076] In this embodiment, the output gear 22 of the second gear 2 functions as an engagement portion that engages with the protruding portion 82. This eliminates the need to provide a separate engagement portion that engages with the rotation restricting member 8. The shape of the engagement portion that engages with the protruding portion 82 is not particularly limited as long as it is capable of engaging with the protruding portion 82. In other words, the engagement portion does not have to be a gear.

[0077] The embodiments disclosed herein are illustrative in all respects and should not be considered as limiting. The scope of the present invention is indicated by the claims, not by the description of the above embodiments, and further includes all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0078] 1 First Gear 2 2nd Gear 3 Third Gear 7 Switching mechanism 8 Rotation restriction member 11 Support part 21 Input gear 22 Output gear 81 Circular section 82 Protrusion 100 Sheet storage device 101 Lift Board 102 Push-up member 1000 Image forming device G Gap Medium Motor S Seat

Claims

1. A lift plate on which the sheet is placed; a push-up member that is rotatably supported below the lift plate and that pushes up the lift plate by rotating in a lift-up direction when power from a motor is transmitted thereto; A first gear that rotates in one direction by the power of the motor; A second gear that meshes with the first gear; a transmission mechanism including at least a third gear that meshes with the second gear and transmits the power of the motor to the push-up member; a rotation restricting member that restricts rotation of the push-up member in a direction opposite to the lift-up direction, the first gear has a cylindrical support portion whose cylindrical axis coincides with a central axis of the first gear, The rotation restricting member is an annular portion into which the support portion is fitted and which is slidable in a rotational direction relative to an outer circumferential surface of the support portion; a protruding portion protruding radially outward from the annular portion and capable of engaging with the second gear, A sheet storage device, wherein the protrusion has a shape that prevents it from passing through a gap between the second gear and the annular portion in a direction perpendicular to the axial direction, and is located downstream of the gap in the rotation direction of the second gear when rotated by the power of the motor.

2. a switching mechanism for switching between transmission and interruption of power from the motor to the first gear, The sheet storage device according to claim 1 , wherein when the transmission of power from the motor is interrupted, the first gear is allowed to rotate in another direction opposite to the one direction.

3. The sheet storage device of claim 2, wherein when the transmission of power from the motor to the first gear is cut off, causing the second gear to rotate in a direction opposite to the direction of rotation when rotated by the power of the motor, the rotation restricting member rotates with the protrusion engaged with the second gear, and stops rotating when the protrusion reaches the gap.

4. 2. The sheet storage device of claim 1, wherein when the first gear rotates in the one direction, the annular portion displaces its rotational position in a direction in which the protrusion moves away from the gap due to frictional resistance between the annular portion and the outer peripheral surface of the support portion and force received from the second gear.

5. the second gear is a stepped gear, an input gear that meshes with the first gear; an output gear that meshes with the third gear, The sheet storage device according to claim 1 , wherein the protrusion is engageable with the output gear.

6. The sheet storage device according to any one of claims 1 to 5 is provided. an image forming apparatus that conveys the sheet and prints an image on the sheet;

Images