Sheet feeding device and image forming apparatus

A sheet feeding device includes a container including a frame, an auxiliary frame member provided on the frame so as to be slidable relative to the frame, and a front cover that covers a front side of the auxiliary frame member, the container being detachably supported in a body of the sheet feeding device; a cover member that covers a top side of the container when the container is attached to the body; and a locking unit that prevents the container attached to the body from being detached from the body when the container is locked and that enables the container to be detached from the body when the container is not locked.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based on and claims priority under 35 USC 119 from Japanese Patent Application No. 2015-183573 filed Sep. 17, 2015.

BACKGROUND

Technical Field

The present invention relates to a sheet feeding device and an image forming apparatus.

SUMMARY

According to an aspect of the invention, there is provided a sheet feeding device including a container including a frame, an auxiliary frame member provided on the frame so as to be slidable relative to the frame, and a front cover that covers a front side of the auxiliary frame member, the container being detachably supported in a body of the sheet feeding device; a cover member that covers a top side of the container when the container is attached to the body; and a locking unit that prevents the container attached to the body from being detached from the body when the container is locked and that enables the container to be detached from the body when the container is not locked.

DETAILED DESCRIPTION

The present invention will be explained in further detail by describing an exemplary embodiment and examples with reference to the drawings. However, the present invention is not limited to the exemplary embodiment and examples.

It is to be noted that the drawings referred to in the following description are schematic, and that dimensional ratios, for example, are not equal to the actual dimensional ratios. Components other than those needed to be explained to facilitate understanding are omitted as appropriate in the drawings.

1. Overall Structure and Operation of Image Forming Apparatus

FIG. 1is a schematic sectional view illustrating the internal structure of an image forming apparatus1according to an exemplary embodiment.FIG. 2Ais a perspective view of the image forming apparatus1to which trays210are attached while auxiliary frame members212thereof are retracted.FIG. 2Bis a perspective view of the image forming apparatus1to which the trays210are attached while the auxiliary frame members212thereof are pulled out.

The overall structure and operation of the image forming apparatus1will be described with reference toFIG. 1.

The image forming apparatus1includes a control device10, sheet feeding devices20, photoconductor units30, developing units40, a transfer device50, and a fixing device60. An output tray1a, which receives sheets P having images recorded thereon, is provided on the top surface (Z-direction-side surface) of the image forming apparatus1.

The control device10includes an image-forming-apparatus controller11that controls the operation of the image forming apparatus1; a controller unit12that prepares image data corresponding to a print request; and an exposure controller13that controls the on-off state of exposure devices LH.

The controller unit12converts print information input thereto from an external information transmission device (for example, a personal computer) into image information used to form a latent image, and outputs drive signals to the exposure devices LH at a preset timing. Each of the exposure devices LH according to the present exemplary embodiment includes an LED head in which plural light emitting diodes (LEDs) are linearly arranged in a scanning direction.

The sheet feeding devices20are provided in a lower section of the image forming apparatus1. Each sheet feeding device20includes a tray210, which serves as a container and contains plural sheets P, which serve as recording media. The sheets P stacked on the trays210are drawn one at a time from the top toward the front side (in the X direction) by a sheet-drawing unit22, and then are transported to a nip portion of a pair of registration rollers23.

A second sheet feeding device20A is provided above the sheet feeding devices20. The second sheet feeding device20A transports sheets P drawn by a sheet drawing unit25toward the nip portion of the pair of registration rollers23along a sheet transport path27.

The sheet feeding devices20are stacked in the lower section of the image forming apparatus1and form a tray module. Each sheet feeding device20may be switched between a first state (seeFIG. 2A) in which the auxiliary frame member212of the tray210is retracted into a frame211and a second state (seeFIG. 2B) in which the auxiliary frame member212is pulled out.

The photoconductor units30are arranged next to each other above (on the Z-direction side of) the sheet feeding devices20. Each photoconductor unit30includes a rotatable photoconductor drum31, which serves as an image carrier. A charging roller32, an exposure device LH, a developing unit40, a first transfer roller52, and a cleaning blade34are arranged around the photoconductor drum31in that order in the rotation direction of the photoconductor drum31. A cleaning roller33, which cleans the surface of the charging roller32, is arranged so as to face the charging roller32and be in contact with the charging roller32.

The developing unit40includes a developing housing41that contains developer. The developing housing41houses a developing roller42arranged so as to face the photoconductor drum31, and a pair of augers44and45that are disposed behind and below the developing roller42and that stir and transport the developer toward the developing roller42. A layer regulating member47, which regulates the layer thickness of the developer, is disposed near the developing roller42.

Developing units40having substantially the same structure except for the color of the developer contained in the developing housing41are provided to form yellow (Y), magenta (M), cyan (C), and black (K) toner images.

The surface of each photoconductor drum31that rotates is charged by the charging roller32, and an electrostatic latent image is formed on the surface of the photoconductor drum31by latent-image forming light emitted from the exposure device LH. The electrostatic latent image formed on the photoconductor drum31is developed into a toner image by the developing roller42.

The transfer device50includes an intermediate transfer belt51, first transfer rollers52, and a second transfer roller53. The toner images of the respective colors formed on the photoconductor drums31of the photoconductor units30are transferred onto the intermediate transfer belt51in a superposed manner. The first transfer rollers52successively transfer the toner images of the respective colors formed by the photoconductor units30onto the intermediate transfer belt51(first transfer process). The second transfer roller53simultaneously transfers the toner images of the respective colors that have been transferred onto the intermediate transfer belt51in a superposed manner onto a sheet P (second transfer process).

The toner images of the respective colors formed on the photoconductor drums31of the photoconductor units30are successively electrostatically transferred onto the intermediate transfer belt51by the first transfer rollers52, which serve as electricity receiving members and receive a predetermined transfer voltage (first transfer process). Thus, a superposed toner image in which the toner images of the respective colors are superposed is formed.

The intermediate transfer belt51is moved so that the superposed toner image on the intermediate transfer belt51is transported to the region in which the second transfer roller53is disposed (second transfer region T). One of the sheet feeding devices20supplies a sheet P to the second transfer region T at the time when the superposed toner image reaches the second transfer region T. The second transfer roller53receives a predetermined transfer voltage so that the superposed toner image on the intermediate transfer belt51is transferred onto the sheet P fed from the pair of registration rollers23and guided by a transport guide.

The toner that remains on the surface of each photoconductor drum31is removed by the cleaning blade34and collected in a waste developer container. Then, the surface of the photoconductor drum31is charged again by the charging roller32. Substances that have not been removed by the cleaning blade34and adhered to the charging roller32are caught on the surface of the cleaning roller33that rotates while being in contact with the charging roller32, and are accumulated.

The fixing device60includes a heating module61and a pressing module62, and a fixing nip region N (fixing region) is formed in a region in which the heating module61and the pressing module62are pressed against each other.

The sheet P onto which the toner image has been transferred by the transfer device50is transported to the fixing device60along the transport guide in a state such that the toner image is not fixed. The sheet P transported to the fixing device60is pressed and heated by the pair of modules, which are the heating module61and the pressing module62, so that the toner image is fixed to the sheet P.

The sheet P to which the toner image is fixed is transported by a pair of transport rollers68and output from a pair of output rollers69to the paper output tray1aon the top surface of the image forming apparatus1.

2. Structure of Container and Attachment/Detachment Mechanism

FIG. 3Ais a perspective view of the tray210in a state in which the auxiliary frame member212is retracted.FIG. 3Bis a perspective view of the tray210in a state in which the auxiliary frame member212is pulled out.FIG. 4Ais a perspective view of the tray210in a state in which the auxiliary frame member212is retracted and a cover member215A is attached to the tray210.FIG. 4Bis a perspective view of the tray210in a state in which the auxiliary frame member212is pulled out and a cover member215B is attached to the tray210.FIG. 5Ais a perspective view illustrating the internal structure of the image forming apparatus1to which the tray210with the cover member215A is attached.FIG. 5Bis a perspective view illustrating the internal structure of the image forming apparatus1to which the tray210with the cover member215B is attached.

The structure of the container will now be described with reference to the drawings.

As illustrated inFIGS. 3A and 3B, the tray210, which serves as a container, includes the frame211, the auxiliary frame member212, a front cover213, a sheet-receiving plate214, a cover member215, and a retard roller22C.

The frame211has the shape of a box capable of receiving the sheets P, and supports the retard roller22C, which is a component of the sheet drawing unit22, in a front region in the direction in which the tray210is inserted into the body of the sheet feeding device20. The retard roller22C is in contact with a feed roller22B and separates the sheets P fed by a pick-up roller22A from each other.

The auxiliary frame member212includes side portions that may be slid into side portions of the frame211(see arrow R inFIG. 3B). The front cover213is provided at the front side of the auxiliary frame member212, and an oblong hole213ais formed at the front side of the front cover213. The hole213aextends through the front cover213and allows a hook portion113of a lock110, which will be described below, to be inserted therethrough. A guide pin213bprojects from the back side of the front cover213, and is fitted to a positioning hole102, which will be described below, in the body of the sheet feeding device20so that the tray210is positioned relative to the body.

The tray210is switchable between a first state in which the auxiliary frame member212is retracted into the frame211and a second state in which the auxiliary frame member212is pulled out. The tray210is set to the first state when, for example, A4 size sheets P (210 mm×297 mm) or letter size sheets P (8.5 inches×11 inches) are to be contained. The tray210is set to the first state when, for example, legal size sheets P (8.5 inches×14 inches) are to be contained.

The sheet-receiving plate214is provided on a bottom portion of the frame211in a swingable state. The sheet-receiving plate214swings upward or downward in accordance with the number of sheets P contained so that the sheet P at the top of the stack of sheets P on the sheet-receiving plate214is at a constant position relative to the pick-up roller22A.

As illustrated inFIGS. 4A and 4B, the cover member215is a rectangular plate member and may be a first cover member215A that covers an upper opening of the tray210when the auxiliary frame member212is retracted, or a second cover member215B that covers the upper opening of the tray210when the auxiliary frame member212is pulled out. The cover members215A and215B are selectively used depending on the state of the tray210.

Accordingly, as illustrated inFIGS. 2A and 2B, each tray210is disposed such that the front cover213thereof does not project from the front surface of the image forming apparatus1when the tray210is in the first state, and such that the front cover213thereof projects from the front surface of the image forming apparatus1when the tray210is in the second state.

As illustrated inFIGS. 4A and 4B, the cover member215is fitted to the top surfaces211aof side walls of the frame211so as to cover the upper opening of the frame211. The tray210to which the cover member215is fitted is attached to the body of the sheet feeding device20by being guided by guide surfaces201of the body of the sheet feeding device20. In this state, the cover member215is sandwiched between the top surfaces211aof the side walls of the frame211and the guide surfaces201, so that the contained sheets P cannot be accessed.

3. Container Lock Mechanism

FIG. 6Ais a partial perspective view of the body of the sheet feeding device20that receives the front cover213of the tray210.FIG. 6Bis a partial sectional view illustrating how the tray210is engaged with the body of the sheet feeding device20.FIG. 7is a perspective view of the image forming apparatus1in a state in which a second sheet feeding device20A is pulled out.FIG. 8Ais a perspective view of a relay member120viewed from a plate-member-112side.FIG. 8Bis a perspective view of the relay member120viewed from a hook-member-123side.FIG. 9Ais an exploded perspective view of the relay member120viewed from the plate-member-122side.FIG. 9Bis an exploded perspective view of the relay member120viewed from the hook-member-123side.FIG. 10Ais a front view of the relay member120viewed from the plate-member-122side.FIG. 10Bis a rear view of the relay member120viewed from the hook-member-123side.FIG. 10Cis a cross-sectional view of the relay member120.FIG. 10Dis a longitudinal sectional view of the relay member120.FIGS. 11A to 11Care perspective views illustrating how the relay member120is attached to the body of the sheet feeding device20.FIG. 12Ais a perspective view illustrating how the relay member120is connected to the front cover213viewed from the bottom side of the sheet feeding device20.FIG. 12Bis perspective view illustrating how the tray210is locked by the relay member120.FIG. 13is a perspective view of the image forming apparatus1in a state in which the second sheet feeding device20A is pulled out.

A container attachment/detachment mechanism will be described below with reference to the drawings.

3.1. Body of Sheet Feeding Device20

As illustrated inFIG. 6A, a bracket101is provided on the front surface of the body of the sheet feeding device20in a region adjacent to an opening1bthrough which the tray210is inserted or extracted. The bracket101is a component of a lock mechanism100, which serves as a locking unit. The bracket101is a metal plate member and is snap-fitted to the body of the sheet feeding device20. The bracket101has an oblong engagement hole101aat one side thereof. The hook portion113, which is formed on a rod112of the lock110, which will be described below, may be inserted into the engagement hole101athrough the hole213ain the front cover213.

As illustrated inFIGS. 6A and 6B, the positioning hole102is formed in a region adjacent to the bracket101. When the tray210is attached to the body of the sheet feeding device20, the guide pin213bformed on the back surface of the front cover213is fitted to the positioning hole102, so that the tray210is positioned relative to the body of the sheet feeding device20.

As a result, the hole213ain the front cover213and the engagement hole101ain the body of the sheet feeding device20are positioned so as to overlap and communicate with each other at a location adjacent to the positioning hole102.

The lock110, which is inserted into the hole213ain the front cover213of the tray210, includes a cylindrical head portion111. The hook portion113is formed integrally with the rod112, which projects from one end surface of the head portion111, at the distal end of the rod112.

A key hole114is formed in the other end surface of the head portion111. A key115is inserted into the key hole114, and is rotated so that the rod112is rotated together.

With this structure, in the case where the tray210is in the first state, the rod112of the lock110is inserted through the hole213aformed in the front cover213of the tray210and into the engagement hole101aformed in the bracket101on the body of the sheet feeding device20. Then, the key115is inserted into the key hole114and rotated so that the rod112is rotated together. Accordingly, the hook portion113engages with the inner wall of the bracket101so that the rod112cannot be extracted from the engagement hole101a.

As a result, the tray210is prevented from being moved in a direction away from the body of the sheet feeding device20. The tray210is secured to the bracket101and cannot be pulled out of the body of the sheet feeding device20.

In the case where the tray210cannot be pulled out of the body of the sheet feeding device20, even when the second sheet feeding device20A is pulled out of the image forming apparatus1as illustrated inFIG. 7, the sheets P contained in the tray210cannot be accessed since the cover member215is securely sandwiched between the top surfaces211aof the side walls of the frame211and the guide surfaces201so as to cover the upper opening of the tray210. As a result, the contained sheets P are protected from theft.

3.2. Relay Member

The relay member120includes a housing121, a plate member122, a hook member123, a holder124, and a spring125that serves as an urging member. When the tray210is used in the second state in which the auxiliary frame member212is pulled out, the relay member120is attached to the bracket101on the body of the sheet feeding device20so that the relay member120comes into contact with the front cover213.

The housing121includes a box-shaped body portion121aand a hollow cylindrical portion121battached to the body portion121aat one end thereof. The cylindrical portion121bsupports the holder124, which will be described below, in a rotatable manner and contains the spring125therein so that the holder124is supported in a movable manner.

The body portion121asupports the hook member123, which will be described below, in a movable manner. The body portion121ais open at the other end so that a hook portion123aformed at an end of the hook member123, which moves together with the holder124, projects from the open end (seeFIG. 8B).

The plate member122is made of a metal, and is snap-fitted to a projection formed on the holder124. An oblong lock hole122ais formed in a surface of the plate member122. The hook portion113formed on the rod112of the lock110, which will be described below, is inserted into the lock hole122athrough the hole213ain the front cover213.

The hook member123is a metal plate member, and includes the hook portion123a, which is hook-shaped, at an end thereof. The hook member123is fixed to the holder124, and is supported in the housing121such that the hook member123is movable together with the holder124.

The holder124includes a cylindrical body portion124a, in which the hook member123is secured, and a holding portion124bto which the plate member122having the lock hole122ais fixed. The holder124is supported such that the holder124is rotatable and movable in the housing121.

The holder124is urged by the spring125in the housing121in a direction in which the holding portion124bto which the plate member122is fixed projects from the cylindrical portion121bof the housing121.

Referring toFIGS. 11A to 11C, the holding portion124bis held and pressed (see arrow R1inFIG. 11A) so that the hook portion123aof the hook member123is inserted into the engagement hole101ain the bracket101on the body of the sheet feeding device20, and then the holding portion124bis rotated (see arrow R2inFIG. 11B). As a result, the spring125in the relay member120exerts an urging force so that the hook portion123aof the hook member123comes into close contact with bracket101on the body of the sheet feeding device20and engages with the bracket.

As illustrated inFIG. 10B, the body portion121aof the housing121has two receiving portions121cthat project radially inward. When the rod112of the lock110is rotated, plate surfaces123bof the hook member123that is also rotated come into contact with the receiving portions121cso that the hook member123stops rotating at a predetermined position. In the present exemplary embodiment, the plate surfaces123bof the hook member123come into contact with the receiving portions121cwhen the rod112rotates a quarter turn.

With this structure, when the tray210in the second state, in which the auxiliary frame member212is pulled out, is to be attached to the body of the sheet feeding device20, first, the relay member120is fixed to the body of the sheet feeding device20(seeFIG. 11C).

Next, the tray210is inserted into the body of the sheet feeding device20. Accordingly, plural ribs213cformed on the back side of the front cover213surrounds the holding portion124bof the relay member120(seeFIG. 12A) so that the holding portion124bis held in a non-rotatable manner. In this state, the hole213ain the front cover213and the lock hole122ain the plate member122overlap.

Then, as illustrated inFIG. 12B, the rod112of the lock110is inserted into the lock hole122ain the plate member122through the hole213ain the front cover213. Then, the key115is inserted into the key hole114and rotated so that the rod112is rotated together. Accordingly, the hook portion113engages with the inner wall of the plate member122, so that the rod112cannot be pulled out of the lock hole122a.

As a result, the tray210is prevented from being moved in a direction away from the body of the device. The tray210is secured to the plate member122and cannot be pulled out of the body of the sheet feeding device20.

In the case where the tray210cannot be pulled out of the body of the sheet feeding device20, even when the second sheet feeding device20A is pulled out of the image forming apparatus1as illustrated inFIG. 13, the sheets P contained in the tray210cannot be accessed since the cover member215is securely sandwiched between the top surfaces211aof the side walls of the frame211and the guide surfaces201so as to cover the upper opening of the tray210. As a result, the contained sheets P are protected from theft.