JP4764322B2 - Sheet feeding apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to a sheet feeding apparatus and an image forming apparatus, and more particularly to a configuration that regulates an intermediate plate provided in a sheet storage portion of a cassette at a lowered position.

  2. Description of the Related Art Today, image forming apparatuses such as printers and copiers are widely used in which an image is formed by feeding a sheet to an image forming unit using a sheet feeding device. In such a sheet feeding apparatus, for example, there is an apparatus in which a sheet feeding cassette is detachably attached to an image forming apparatus main body in order to facilitate storage and replacement of sheets. In the sheet feeding apparatus having this configuration, after the sheet feeding cassette is mounted on the image forming apparatus main body, the sheet stored in the sheet feeding cassette is fed to the image forming unit by a pickup roller.

  By the way, as such a paper feed cassette mounted on the image forming apparatus main body, there is a paper cassette that includes a middle plate that supports a sheet and is rotatable in the vertical direction. The intermediate plate is urged toward the pickup roller by a spring so that the sheet is pressed against the pickup roller when the sheet is fed to obtain a feeding pressure necessary for feeding the sheet.

  In addition, when replenishing or replacing sheets in the sheet cassette, the sheet cassette is pulled out from the image forming apparatus main body, the middle plate is pushed down against the urging force of the spring, and the lock mechanism is used in the lowered position. Some restrict the plate (hereinafter referred to as “lock”). With this configuration, it is possible to easily replenish or replace sheets in the paper feed cassette.

  The lock of the intermediate plate by the lock mechanism is released when the paper feed cassette is mounted on the image forming apparatus main body. As a result, when the paper feeding cassette is inserted into the image forming apparatus main body, the intermediate plate is raised to the pickup roller side by the spring, and the sheet can be fed.

  However, since the position of the lock mechanism is a position that can be easily operated by the user, the user accidentally unlocks the lock mechanism when the sheet is replenished or replaced, and the middle plate is It may jump up. Further, in order to fix the middle plate at the lowered position (lock position), it is necessary to push down the middle plate once to the lowered position before stacking sheets, which causes trouble.

  Therefore, conventionally, for example, as shown in FIG. 6, a lock mechanism 50 for locking the middle plate 102 provided in the paper feeding cassette 100 in the lowered position is positioned below the middle plate 102 and the cassette of the paper feeding cassette 100. It is provided at a substantially central portion of the main body 101. And by providing the lock mechanism 50 in such a position, it can prevent that a user operates the lock mechanism 50 accidentally (for example, refer patent document 1).

  When the lock mechanism 50 is provided at such a position, the lock release member 60 is provided on the bottom plate 70 of the lower part of the image forming apparatus main body 200 in order to unlock the lock mechanism 50.

  FIG. 7 is a diagram showing details of such a locking mechanism 50. The lock mechanism 50 is rotatably provided in the paper feed cassette 100, and locks the middle plate 102 at the pushed-down position by being locked to the locked portion 102a of the middle plate 102. In FIG. 7, the paper feed cassette 100 moves from the right side to the left side in the drawing and is mounted on the cassette mounting unit 201 shown in FIG.

  When the paper feed cassette 100 is mounted on the cassette mounting portion 201 of the image forming apparatus main body 200, the release lever 51 provided on the lock mechanism 50 is an unlock member provided on the bottom plate 70 located below the apparatus main body 200. 60 abuts.

  Here, when the unlocking member 60 abuts in this way, the locking mechanism 50 rotates in the direction of the arrow shown in FIG. 7, thereby releasing the lock of the intermediate plate 102. As a result, the intermediate plate 102 is raised by the urging force of the spring 103 and is urged toward the pickup roller 203 shown in FIG. 6 provided in the image forming apparatus main body 200, so that the sheet can be fed. Move to position.

  On the other hand, as shown in FIG. 6, a guide portion 65 having an inclined surface 66 is disposed on the side surface on the entrance side of the cassette mounting portion 201 in the image forming apparatus main body 200. When the paper feeding cassette 100 is attached to or detached from the cassette mounting portion 201, a sliding contact portion (not shown) protruding sideways from the middle plate 102 of the paper feeding cassette 100 comes into sliding contact with the inclined surface 66. Accordingly, the intermediate plate 102 is pushed down along the inclined surface 66 in accordance with the attachment / detachment to the image forming apparatus main body 200.

  For example, when the paper feed cassette 100 is pulled out from the image forming apparatus main body 200, the intermediate plate 102 descends against the urging force of the spring 103 along the inclined surface 66 of the guide member 65 shown in FIG. Then, before the sheet feeding cassette 100 is pulled out, the middle plate 102 is fixed at a position where it is pushed down by the lock mechanism 50. Thus, by locking the middle plate 102 in conjunction with the pulling-out operation of the paper feed cassette 100, it is not necessary to push down the middle plate 102 for stacking sheets, and operability can be improved.

  By the way, the lock mechanism 50 is movable to the position where the intermediate plate 102 shown in FIG. 7 is locked and the position where the intermediate plate 102 is unlocked by moving in the arrow direction. Furthermore, when it moves to the lock position, it abuts against the abutting portion 55 of the paper feed cassette body 101 as shown in FIG. 7, and cannot move in the direction opposite to the lock release position.

  With this configuration, when the lock mechanism 50 moves to the lock position, the urging force of the spring 103 acts on the lock mechanism 50 and becomes a force for locking the intermediate plate 102. 50 can lock.

Japanese Patent Laid-Open No. 06-9077

  By the way, in recent years, according to various types of sheets to be used, paper cassettes are provided in multiple stages in an image forming apparatus. In such an image forming apparatus, for example, a lower sheet cassette (not shown) is mounted below the sheet cassette 100 shown in FIG. 6, and sheets stored in the lower sheet cassette are not shown. It is fed by the lower pickup roller.

  For this reason, the sheet feeding cassette 100 is provided with a cassette conveying path 101A for conveying a sheet fed from the lower sheet feeding cassette. In addition, a bottom plate (a partition plate that divides the upper cassette mounting portion and the lower cassette mounting portion) 70 of the image forming apparatus main body 200 receives sheets from the lower paper feeding cassette in the cassette conveyance path of the upper paper feeding cassette 100. An opening 70a for sending to 101A is provided.

  In this configuration, it is necessary to provide the lock release member 60 before and after the opening 70 a in the mounting direction of the paper feed cassette 100. Specifically, the position at which the lock release member 60 abuts the lock mechanism 50 immediately before the paper feed cassette 100 is completely mounted (hereinafter referred to as the back side position) or the cassette insertion port 202 side of the cassette mounting portion 201. It is necessary to provide either.

  Here, when the lock release member 60 is provided at the back side position of the cassette mounting portion 201, the spring 103 is released when the lock of the intermediate plate 102 is released when the paper feed cassette 100 is mounted on the image forming apparatus main body 200. As a result, the intermediate plate 102 is suddenly pushed upward. When the intermediate plate 102 is pushed up suddenly in this way, an upward inertia force acts on the sheet, so that when the sheet hits the pickup roller 203, a large force is applied to the sheet. The posture when loading is disturbed.

  Here, if the posture at the time of stacking is disturbed in this way, the sheet feeding performance deteriorates, and it causes a feeding failure such as skew feeding or non-feeding of the sheet. Sometimes it was necessary to start over. Further, when the sheet suddenly hits the pickup roller 203, a collision sound may be generated, or the paper feed cassette 100 or the pickup roller 203 may be damaged.

  On the other hand, when the lock release member 60 is provided on the cassette insertion port side of the cassette mounting portion 201 indicated by the broken line in FIG. 6, the lock of the intermediate plate 102 is released at an early stage when the paper feed cassette is mounted (inserted). be able to. In this case, the intermediate plate 102 can be gently raised along the inclined surfaces 66 of the guide members 65 provided at both ends of the cassette mounting portion 201, so that the sheet suddenly moves with respect to the pickup roller 203. You will no longer be hit by.

  However, when the lock release member 60 is provided at such a position, the lock mechanism 50 cannot rotate in the direction opposite to the direction indicated by the arrow in FIG. The release lever 51 is caught by the lock release member 60. If the lock release member 60 is caught in this way, the paper feed cassette 100 cannot be pulled out.

  Therefore, in a conventional apparatus configured to provide the sheet feeding cassette 100 with the cassette conveyance path 101A and send sheets from the lower sheet feeding cassette to the image forming unit via the cassette conveyance path 101A, the lock mechanism 50 of the intermediate plate 102 is provided. It could not be provided under the middle plate 102.

  Accordingly, the present invention has been made in view of such a current situation, and is capable of reliably locking and unlocking the intermediate plate, as well as sheet feeding that can prevent feeding failure and damage to parts. An object of the present invention is to provide an apparatus and an image forming apparatus.

  The present invention includes a sheet storage portion, a middle plate rotatably provided in the sheet storage portion, and a biasing unit that biases the middle plate toward a sheet feeding portion for feeding a sheet. In the sheet feeding apparatus in which the cassette having the detachable structure is provided on the apparatus main body, a lock mechanism for restricting the intermediate plate at a position lowered against the urging force of the urging means is provided on the apparatus main body. A lock releasing portion that releases the restriction of the intermediate plate by the lock mechanism in accordance with the mounting of the cassette on the apparatus main body, and the lock mechanism is a rotatable lock that restricts the intermediate plate. And a lock release lever for rotating the lock member in a restriction release direction by rotating in unison with the lock member in contact with the lock release portion, and the cassette is the device main body. When attached to The lock release lever rotates in contact with the lock release portion, and when the cassette is pulled out by rotating the lock member in the restriction release direction to release the restriction of the intermediate plate, However, the lock release lever rotates independently in a state where the intermediate plate is maintained at the position where the intermediate plate is regulated.

  According to the present invention, when the cassette is pulled out, the lock release member can be independently rotated to maintain the regulation of the intermediate plate by the lock member. Regulation and deregulation are possible. As a result, the regulation and deregulation of the intermediate plate can be performed reliably, and feeding failure and component damage can be prevented.

  The best mode for carrying out the present invention will be described below in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are intended to limit the technical scope of the present invention only to those unless otherwise specified. It is not a thing.

  FIG. 1 is a schematic diagram showing an overall configuration of a laser printer which is an example of an image forming apparatus according to an embodiment of the present invention.

  In FIG. 1, 10 is a printer, and 10A is a laser printer main body (hereinafter referred to as a printer main body). The printer main body 10A includes an image forming unit 10B that forms an image on a sheet, a sheet feeding device 10C that feeds the sheet, and a sheet fed from the sheet feeding device 10C to the image forming unit 10B. A sheet conveying device 12 is provided. Further, a fixing device 19 for fixing the image formed on the sheet is provided.

  Here, the image forming unit 10B includes a photosensitive drum 17 which is an image carrier that carries a toner image. The photosensitive drum 17 is rotated counterclockwise by a rotating means (not shown).

  The image forming unit 10B also includes a charging device 17a that uniformly charges the surface of the photosensitive drum, and a scanner unit 10F that irradiates a laser beam based on image information to form an electrostatic latent image on the photosensitive drum. ing. Further, a developing device 17b or the like that visualizes a toner image by attaching toner to the electrostatic latent image is provided.

  A transfer roller 18 is provided inside the endless transfer / conveyance belt 12a for conveying a sheet, which will be described later, together with the photosensitive drum 17 so as to sandwich the transfer / conveyance belt 12a. Here, the transfer roller 18 is connected to a power supply for transfer bias (not shown), and positive charges are applied from the transfer roller 18 to the sheet via the transfer conveyance belt 12a. By applying the transfer bias in this way, the negative toner images on the photosensitive drum are sequentially transferred onto the sheet in contact with the photosensitive drum 17.

  The sheet feeding device 10C is an example of a cassette that stores a plurality of sheets S and is detachably mounted on a cassette mounting portion 10D provided at the bottom of the printer main body 10A that constitutes the sheet feeding device main body. A paper cassette 1 is provided. The paper feed cassette 1 is mounted on the cassette mounting portion 10D of the printer main body 10A from the right side to the left side in FIG. Further, a pickup roller 11 that is a sheet feeding unit that feeds the sheet S stored in the sheet feeding cassette 1 is provided.

  The sheet feeding cassette 1 is provided with a cassette main body 1A constituting a sheet storage portion and a rotatable main body 2A in the cassette main body 1A. It is provided to be movable. The intermediate plate 2 is urged upward by a spring 3 such as a compression spring so as to press the sheet S against the pickup roller 11.

  A lower cassette mounting portion 10E is disposed below the cassette mounting portion 10D. A lower paper feed cassette 20 is detachably provided in the lower cassette mounting portion 10E. The configuration of the lower sheet cassette 20 and the configuration of a feeding mechanism such as a pickup roller for feeding sheets from the lower sheet cassette 20 are the same as those of the sheet feeding cut 1 and the sheet feeding apparatus 10C. Illustration and description are omitted.

  At the time of image formation, the sheet S is separated and fed one by one from the sheet feeding cassette 1 or the lower sheet feeding cassette 20 by the pickup roller 11 and the separating unit 11a. The sheet is conveyed to the sheet conveying device 12 at a predetermined timing.

  The sheet conveying device 12 includes a transfer conveying belt 12a serving as a sheet carrier that is stretched over a driving roller 12b and driven rollers 12c to 12e and is disposed to face the photosensitive drum 17. Here, the transfer conveyance belt 12a electrostatically attracts the sheet to the outer peripheral surface facing the photosensitive drum 17, and is circulated clockwise by the driving roller 12b so as to bring the sheet into contact with the photosensitive drum 17. It has become.

  The sheet is conveyed to the transfer position by the transfer conveyance belt 12a by being electrostatically attracted to the transfer conveyance belt 12a that circulates in this way, and the toner image on the photosensitive drum 17 is transferred.

  Reference numeral 14 denotes an electrostatic attraction roller which is disposed at the most upstream position of the transfer conveyance belt 12a and is in pressure contact with the driven roller 12e via the transfer conveyance belt 12a. The electrostatic adsorption roller 14 presses the sheet S to the outer periphery of the transfer conveyance belt 12a and applies a voltage between the sheet S and the transfer conveyance belt 12a, thereby electrostatically adsorbing the sheet S to the transfer conveyance belt 12a. I have to.

  The fixing device 19 applies heat and pressure to the image formed on the sheet to fix the toner image, and includes a fixing roller 19a and a pressure roller 19b incorporating a heating source. The pressure roller 19a is brought into pressure contact with the fixing roller 19b, and a nip is formed at a contact portion between the pressure roller 19b and the fixing roller 19a.

  Next, an image forming operation of the printer 10 configured as described above will be described.

  First, the charging device 17a applies a uniform charge to the peripheral surface of the photoconductive drum 17, and the scanner unit 10F exposes the peripheral surface of the photoconductive drum 17 according to an image signal to perform the peripheral surface of the photoconductive drum 17. An electrostatic latent image is formed thereon. Further, the latent image is developed by the developing device 17b, whereby a toner image is formed on the surface of the photosensitive drum.

  In parallel with the toner image forming operation, the sheet S accommodated in the paper feeding cassette 1 or the lower paper feeding cassette 20 is picked up by the pick-up roller 11, and is then applied to the resist roller pair 16 that is stopped. The leading edge of the sheet S hits to form a loop. Then, the skew of the sheet S is corrected by forming the loop in this way.

  Thereafter, at the timing when the leading edge of the toner image on the photosensitive drum 17 is rotated and conveyed to the contact point (transfer position) with the transfer conveyance belt 12a, the print start position of the sheet S coincides with the contact point. Thus, the registration roller pair 16 starts to rotate.

  As the registration roller pair 16 rotates, the sheet S is conveyed to the nip between the electrostatic adsorption roller 14 and the transfer conveyance belt 12a, and is adsorbed to the transfer conveyance belt 12a by the electrostatic adsorption roller 14. Thereafter, the photosensitive drum 17 and the transfer conveyance belt 12a are conveyed to a transfer portion where they are in pressure contact with each other.

  Next, the toner image on the photosensitive drum 17 is formed on the sheet by the action of the transfer roller 18 which is arranged in the transfer unit and is applied with a voltage having a polarity opposite to that of the toner. Transcribed.

  Then, the sheet S on which the toner image is transferred in this way is separated from the transfer conveyance belt 12a by the curvature of the driving roller 12b and is carried into the fixing device 19. Thereafter, in the fixing device 19, the toner image is fixed on the sheet S, and the sheet S on which the toner image is fixed is discharged to the sheet discharge tray 15 by the fixing discharge roller pair 21.

  Incidentally, as shown in FIG. 2, guide members 45 having inclined surfaces 46 are provided opposite to both side walls on the entrance side of the cassette insertion slot 45a of the cassette mounting portion 10D for detachably mounting the paper feed cassette 1. It has been. The paper feed cassette 1 is mounted on the cassette mounting portion 10D from the direction of the arrow shown in FIG.

  When the paper cassette 1 is attached or detached, a sliding contact portion (not shown) of the intermediate plate 2 urged upward by the spring 3 comes into contact with the inclined surface 46, as will be described later. The middle plate 2 moves in the vertical direction along the inclined surface 46 with the attachment / detachment. A sliding contact portion (not shown) is provided so as to protrude from the intermediate plate 2 to the side of the sheet feeding cassette 1 at a position where the sliding contact portion can be brought into sliding contact with the inclined surface 46.

  On the bottom plate 70 of the cassette mounting portion 10D, a sheet fed by a lower pickup roller (not shown) from a lower paper cassette 20 disposed on the lower side of the paper cassette 1 is fed to a cassette conveyance path 1B of the paper cassette 1. An opening 70a is provided for sending to

  On the lower side of the middle plate 2 in the cassette body 1A, a lock mechanism 30 is disposed at a position corresponding to the center portion in the width direction perpendicular to the sheet feeding direction of the middle plate 2. The lock mechanism 30 can lock the intermediate plate 2 in the lowered position (lock position) against the spring 3 when sheets are stacked.

  Further, the cassette mounting portion 10D is provided with an unlocking member 40 that is a lock releasing means for unlocking the middle plate 2 of the paper feeding cassette 1 on the cassette insertion port side of the cassette mounting portion 10D than the opening 70a. It has been. As will be described later, when the paper feed cassette 1 is attached to the cassette attachment portion 10D, the lock of the middle plate 2 of the paper feed cassette 1 is released by the lock release member 40.

  Next, the lock mechanism 30 will be described.

  As shown in FIG. 3, the lock mechanism 30 is a lock member 32 that locks the intermediate plate 2, and a lock release member that is provided separately from the lock member 32 and that unlocks the intermediate plate 2 by the lock member 32. The lock release lever 31 is provided. The lock member 32 and the lock release lever 31 are rotatably attached to the shaft 30a.

  The locking member 32 is provided on the claw portion 32a which is a locking portion for locking the locked portion 2a protruding from the bottom surface of the intermediate plate 2 and locking the intermediate plate 2, and the sheet feeding cassette body 1A. An abutting portion 32b that abuts against the abutting portion 35 that is a limiting portion is provided.

  Further, the lock member 32 can be moved to a position where the middle plate 2 is locked by the claw portion 32a to be locked, and a position where the lock member 32 is rotated in the direction of the arrow in FIG. ing. The lock member 32 is configured such that the abutting portion 32b abuts against the abutting portion 35 provided in the sheet feeding cassette body 1A at the position where the intermediate plate 2 shown in FIG. 3 is locked. Thereby, the lock member 32 cannot be rotated in the direction opposite to the arrow (clockwise in FIG. 3).

  With this configuration, when the claw portion 32 a is locked to the locked portion 2 a protruding from the bottom surface of the intermediate plate 2, the urging force of the spring 3 acts as a force for locking the intermediate plate 2. Therefore, the intermediate plate 2 can be reliably locked and the locked state can be maintained.

  Further, the configuration of the lock mechanism 30 will be described with reference to FIG.

  A first biasing member 37, which is a torsion coil spring that biases the shaft 30 a of the lock mechanism 30 in a direction in which the abutting portion 32 b of the lock member 32 abuts against the abutting portion 35 (clockwise direction in FIG. 3). Is provided. Then, by urging the lock member 32 by the first urging member 37 in this way, the lock member 32 is always kept on the middle plate 2 except for the movement of the middle plate 2 to the unlock position by the lock release lever 31 described later. It can be maintained in the locked position. Thereby, the middle plate 2 can be reliably locked.

  Further, the lock release lever 31 is connected to the lock release member 40 provided in the cassette mounting portion 10D when the paper feed cassette 1 is mounted to the cassette mounting portion 10D, as shown in FIG. Touch. As a result, the lock release lever 31 rotates in the direction of the arrow in FIG. 3 (counterclockwise direction), which is the lock release direction.

  Here, as shown in FIG. 4, the lock release lever 31 is provided with an engaging portion 36 that engages with the lock member 32. When the lock release lever 31 rotates in the direction of the arrow in FIG. When pressed by the engaging portion 36, the lock member 32 also rotates integrally. When the lock member 32 is rotated in the direction of the arrow in this manner, the engagement with the middle plate 2 of the claw portion 32a is released, whereby the middle plate 2 is rotated upward by the biasing force of the spring 3, and the sheet The uppermost surface moves to a sheet feeding position where the pickup roller 11 can feed.

  Further, as shown in FIG. 4, a second biasing member 38, which is a torsion coil spring that biases the release lever 31 in the direction in which the engaging portion 36 is engaged with the lock member 32, is provided on the shaft 30 a of the lock mechanism 30. Is provided.

  When the lock member 32 is in a position to lock the middle plate 2 by the second urging member 38, the release lever 31 is always directed downward, so that the paper feed cassette 1 is mounted. At this time, the release lever 31 can reliably contact the lock release member 40. In the present embodiment, the first and second urging members 37 and 38 are separate parts. However, the same urging member may be used, and in this case, the number of parts can be reduced.

  Next, the operation of the lock mechanism 30 configured as described above will be described.

  When the paper feed cassette 1 is mounted on the cassette mounting portion 10D, as shown in FIG. 5A, the lock release lever 31 comes into contact with the lock release member 40 provided on the bottom surface of the cassette mounting portion 10D, thereby moving the arrow A. Rotate in the direction (counterclockwise).

  Here, when the lock release lever 31 rotates in this way, the lock member 32 is pressed via the engaging portion 36, and the lock member 32 also rotates in the direction of arrow A. As a result, the locking of the intermediate plate 2 is performed. Canceled.

  When the paper cassette 1 is mounted in this way, when the lock by the lock member 32 is released, the intermediate plate 2 moves in the direction of arrow B from the spring 3, and a slide (not shown) provided on the intermediate plate 2. The contact portion comes into pressure contact with the inclined surface 46 of the guide member 45 shown in FIG. Then, when the sheet feeding cassette 1 is inserted in this state, the intermediate plate 2 eventually extends along the downstream portion 46a (see FIG. 2) inclined upward toward the downstream side in the mounting direction of the inclined surface 46. Move upward.

  In the present embodiment, since the lock release member 40 is provided on the cassette insertion port side of the cassette mounting portion 10D, the angle of the downstream portion 46a of the inclined surface 46 of the guide member 45 becomes gentle. For this reason, the intermediate plate 2 gradually moves (rotates) upward, so that the sheets stacked on the intermediate plate 2 slowly come into contact with the pickup roller 11. In addition, by slowly contacting the sheet with the pickup roller 11 in this manner, it is possible to prevent the sheet stacking state from being disturbed, the occurrence of collision noise, breakage, and the like.

  On the other hand, when the paper cassette 1 is pulled out, the middle plate 2 that has been moved to the feeding position with the lock member 32 unlocked as the paper cassette 1 moves in the pulling direction is used as a guide member. It gradually descends against the urging force of the spring 3 along the inclined surface 46 of 45.

  Eventually, the locked portion 2a of the intermediate plate 2 comes into pressure contact with the claw portion 32a of the lock member 32 from above, so that the lock member 32 counters the first biasing member 37 in the counterclockwise direction (in FIG. 5). It rotates in the direction of the arrow (a). Thereafter, when the intermediate plate 2 further descends, the locked portion 2a of the intermediate plate 2 passes through the claw portion 32a of the lock member 32, and when the locked portion 2a of the intermediate plate 2 passes in this way, the lock member 32 is rotated upward by the urging force of the first urging member 37.

  As a result, the claw portion 32 a of the lock member 32 is positioned above the locked portion 2 a of the intermediate plate 2. When the sheet feeding cassette 1 is further pulled out in this state, the intermediate plate 2 eventually moves upward along a portion 46b (see FIG. 2) inclined upward on the upstream side in the mounting direction of the inclined surface 46, and is locked. The claw portions 32a of the 32 are engaged and locked.

  After that, when the sheet feeding cassette 1 is further pulled out, the release lever 31 and the lock release member 40 provided on the cassette insertion port side of the cassette mounting portion 10D, as shown in FIG. It contacts and rotates in the reverse direction (the reverse direction to the release position) when the paper feed cassette is mounted.

  However, in the present embodiment, the release lever 31 is provided separately from the lock member 32, and the lock member 32 does not rotate because the abutment portion 32b abuts against the abutment portion 35. For this reason, only the release lever 31 rotates independently of the lock member 32.

  As a result, the sheet cassette 1 can be pulled out in a state where the middle plate 2 is rotated downward and locked, and subsequent stacking and storage or replacement of sheets becomes easy. The release lever 31 is released from contact with the lock release member 40 until the paper cassette 1 is pulled out, and returns to the position shown in FIG. 3 by the urging force of the second urging member 38.

  As described above, when the paper feed cassette 1 is stored, the release lever 31 is rotated together with the lock member 32 to lock the intermediate plate 2 by the lock member 32 regardless of the position of the lock release member 40. It can be canceled. Further, when the paper feeding cassette 1 is pulled out, the lock lever 32 can be held (maintained) by moving the release lever 31 alone.

  Thereby, the middle plate 2 can be reliably locked and unlocked by the lock mechanism 30, and feeding failure and damage to parts can be prevented. Furthermore, the operability of the user's paper feed cassette 1 can be improved.

1 is a schematic diagram illustrating an overall configuration of a laser printer that is an example of an image forming apparatus according to an embodiment of the present invention. 2A and 2B are diagrams illustrating a configuration of a cassette mounting portion provided in a printer main body of the laser printer and a paper feeding cassette that is detachably mounted on the cassette mounting portion. The figure explaining the state which locked the intermediate plate provided in the said paper feed cassette with the locking mechanism. The figure explaining the structure of the said locking mechanism. The figure explaining operation | movement of the lock mechanism at the time of attaching or detaching the said paper feed cassette. 2A and 2B are diagrams illustrating a configuration of a cassette mounting portion provided in a conventional image forming apparatus and a paper feeding cassette that is detachably mounted on the cassette mounting portion. The figure explaining the state which locked the intermediate plate provided in the said conventional paper feed cassette with the locking mechanism.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Paper feed cassette 1A Cassette main body 2 Middle plate 2a Locked part 3 Spring 10 Printer 10A Laser printer main body 10B Image forming part 10C Sheet feeding apparatus 10D Cassette mounting part 11 Pickup roller 30 Lock mechanism 31 Lock release lever 32 Lock member 32a Claw part 32b Abutting part 35 Abutting part 36 Engaging part 37 First urging member 38 Second urging member 40 Unlocking member 45 Guide member 46 Inclined surface S Sheet

Claims (7)

A cassette having a sheet storage unit, a middle plate rotatably provided in the sheet storage unit, and a biasing unit that biases the middle plate toward a sheet feeding unit for feeding sheets. In the sheet feeding apparatus provided detachably on the apparatus body,
A lock mechanism for regulating the intermediate plate at a position lowered against the urging force of the urging means;
A lock release portion that is provided in the apparatus main body, and that releases the restriction of the intermediate plate by the lock mechanism according to the mounting of the cassette to the apparatus main body,
The lock mechanism is configured to turn the lock member in a restriction release direction by rotating the lock member integrally with the lock member in contact with the lock release portion and the turnable lock member for restricting the intermediate plate. When the cassette is mounted on the apparatus main body, the lock release lever abuts on the lock release portion and rotates to rotate the lock member in the regulation release direction. Then, when the regulation of the intermediate plate is released and the cassette is pulled out, the lock release lever rotates independently while the lock member is maintained at a position for regulating the intermediate plate. Sheet feeding device.   The sheet storage portion is provided with a limiting portion that restricts rotation of the lock member due to the urging force of the urging means when the lock member restricts the intermediate plate, and the lock plate includes the intermediate plate. When the intermediate plate is restricted, a contact portion that contacts the restriction portion is provided, and the lock release lever is engaged with the lock member when moving in the restriction release direction. The sheet feeding apparatus according to claim 1, wherein an engaging portion is provided.   The lock mechanism includes a first urging member that urges the lock member in a direction in which the abutment portion of the lock member abuts on the restriction portion, the lock release lever, and an engagement of the lock release lever. The sheet feeding apparatus according to claim 2, further comprising: a second urging member that urges the joint portion in a direction in which the joint portion is engaged with the lock member.   4. The sheet feeding apparatus according to claim 3, wherein the first urging member and the second urging member are constituted by the same urging member.   5. The lock member according to claim 1, wherein the lock member is provided below the intermediate plate and at a central portion in a width direction orthogonal to the sheet feeding direction of the intermediate plate. The sheet feeding apparatus according to the description.   The apparatus body is provided with a guide member configured to lower the intermediate plate to a position regulated by the lock mechanism against the biasing force of the biasing means when pulling out the cassette. The sheet feeding apparatus according to claim 1, wherein the sheet feeding apparatus is a sheet feeding apparatus.   An image forming apparatus comprising: an image forming unit; and a sheet feeding device according to claim 1 for feeding a sheet to the image forming unit.

Images