Sheet Feeder

This application claims priority from Japanese Patent Application No. 2024-069554 filed on Apr. 23, 2024. The entire content of the priority application is incorporated herein by reference.

A sheet feeder that feeds a sheet such as a document is known.

A document conveyance device, which is an example of a sheet feeder, includes a document placement portion, a pickup roller, and a friction member.

The document placement portion supports sheets in a stacked state. The pickup roller is rotatable about a rotation axis extending in a width direction of the document placement portion. The pickup roller feeds the uppermost sheet in a feed direction perpendicular to the width direction while contacting a surface of the uppermost sheet supported by the document placement portion.

The friction member is a cork sheet and so on, and is provided at a position facing the pickup roller in the document placement portion. The friction member contacts a bottom surface of the lowermost sheet supported by the document placement portion and applies a frictional force to the lowermost sheet, thereby suppressing a failure in which the lowermost sheet is fed in a state of being overlapped with an upper sheet when the upper sheet is fed.

In the document conveyance device, sheets that are deformed by having a tendency to warp or by warping due to moisture may be supported on the document placement portion in a stacked state. In this case, it is difficult to correct the deformed sheet by a pressing force when the pickup roller feeds the uppermost sheet, and it is difficult for the friction member to contact the bottom surface of the lowermost sheet. As a result, in the document conveyance device, the frictional force is unlikely to act on the sheets in a stacked state, and thus multi-sheet feed in which multiple sheets are fed in a stacked state is likely to occur (hereinafter also referred to as “stacked multi-sheet feed”). In the stacked multi-sheet feed, all the sheets placed on the document placement portion (document tray) are fed all at once, for example. When the stacked multi-sheet feed occurs, the sheets are jammed in a stacked state on the downstream side of the pickup roller in the feed direction, and thus misfeed is likely to occur.

In order to suppress such a problem, it is conceivable to make the friction member protrude more than the document placement portion and be closer to the rotation axis of the pickup roller so that the friction member easily contacts the bottom surface of the lowermost sheet. However, in order to keep the maximum number of sheets to be stacked, it is necessary to raise the upper limit position of the pickup roller by the height of the protrusion, and it is difficult to realize a reduction in size in the height direction.

In view of the foregoing, an example of an object of this disclosure is to provide a sheet feeder configured to suppress stacked multi-sheet feed even when deformed sheets are supported on a sheet support surface in a stacked state and to realize a reduction in size in a height direction.

According to one aspect, this specification discloses a sheet feeder including a supply tray, a feed roller, and a friction member. The supply tray includes a sheet support surface configured to support sheets in a stacked state. Thus, the supply tray supports sheets in a stacked state. The feed roller is rotatable about a rotation axis extending in a width direction of the sheet support surface. The feed roller is configured to contact a top surface of an uppermost sheet supported by the sheet support surface and to feed the uppermost sheet in a feed direction perpendicular to the width direction. Thus, the feed roller feeds the uppermost sheet in the feed direction. The friction member is provided to face the feed roller on the sheet support surface. The friction member is configured to contact a bottom surface of a lowermost sheet supported by the sheet support surface and to apply a frictional force to the lowermost sheet. Thus, the friction member applies the frictional force to the lowermost sheet. The supply tray includes a first tray forming a first support surface and a second tray forming a second support surface. The first support surface is a part of the sheet support surface. The first support surface includes a downstream end of the sheet support surface in the feed direction. The second support surface is at least part of a remaining part of the sheet support surface. The second support surface is adjacent to the first support surface from upstream in the feed direction. The friction member includes a first surface and a second surface. The first surface is provided to face the feed roller. The first surface is configured to contact the bottom surface of the lowermost sheet. The first surface is configured to contact the feed roller when there is no sheet supported by the sheet support surface. The second surface is provided upstream of the first surface in the feed direction. The second surface is configured to contact the bottom surface of the lowermost sheet. The first surface is located farther from the rotation axis than the second support surface and the second surface are in a first direction. The first direction is parallel to a perpendicular line as viewed in the width direction. The perpendicular line is drawn from the rotation axis to the first surface in a state where the feed roller contacts the first surface. Thus, the second surface reliably contacts the bottom surface of the lowermost sheet, while reducing the size of the sheet feeder in the first direction.

In the sheet feeder of the present disclosure, the second support surface of the second tray and the second surface of the friction member are located upstream of the first surface of the friction member in the feed direction. The first surface is located farther from the rotation axis than the second support surface and the second surface are in the first direction.

That is, a portion of the sheet supported by the sheet support surface, which contacts the second support surface and the second surface, is one step higher than a portion of the sheet, which contacts the first surface, at the upstream in the feed direction.

Accordingly, when the sheets deformed by a curl developed over time or due to moisture are supported on the sheet support surface in a stacked state and the feed roller presses the uppermost sheet downward, the sheet is deformed along the step between the first surface and the second surface, and the second surface reliably contacts the bottom surface of the lowermost sheet.

As a result, the sheet feeder causes the friction member to apply the frictional force to the lowermost sheet with high reliability. This suppresses stacked multi-sheet feed in which sheets are fed in a stacked state, and further suppresses misfeed due to jamming of sheets in a stacked state at the downstream side of the feed roller in the feed direction caused by the stacked multi-sheet feed.

Further, the sheet feeder is likely to be more compact in the height direction, compared to a configuration in which the second surface is not provided and the first surface is located closer to the rotation axis than the second support surface is in the first direction to suppress the stacked multi-sheet feed.

Thus, the sheet feeder of the present disclosure suppresses the stacked multi-sheet feed even when the deformed sheets are supported on the sheet support surface in a stacked state, and realizes reduction in size in the height direction.

Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings.

As shown in, an image scanning apparatusof an embodiment is an example of one aspect of a sheet feeder of the present disclosure. In, an operation panelP side of the image scanning apparatusis a front side. A left side is the side that comes to the left when facing the operation panelP. A front-rear direction, a left-right direction, and an upper-lower direction shown inand the subsequent drawings are all shown in correspondence with the directions shown in.

An overall configuration of the image scanning apparatuswill be described. As shown in, the image scanning apparatusincludes a main bodyand a cover. The main bodyis a flat, substantially box-shaped body. The operation panelP such as a touch panel is located on a front surface of the main body. The main bodyhouses an image forming unit(print engine) in a lower portion thereof. The image forming unitforms an image on a sheet by an inkjet method, a laser method, and so on.

As shown in, the main bodyhouses an image scannerin an upper portion thereof. The image scannerincludes a document support surfaceA, a reading surfaceB, an image sensor (reading sensor)S, and a scan mechanism (not shown).

The document support surfaceA is an upper surface of a large-area platen glass located on the upper surface of the main body. The reading surfaceB is an upper surface of a platen glass that is located on the left side of the document support surfaceA on the upper surface of the main bodyand extends in the front-rear direction.

The document support surfaceA supports a document to be scanned. The document to be scanned is a sheet such as a paper sheet or an OHP sheet, a book, and so on. The reading surfaceB is used when a conveyance unitdescribed later operates.

The image sensorS is a well-known image sensor using a CIS (Contact Image Sensor), a CCD (Charge Coupled Device), and so on, and extends in an elongated shape in the front-rear direction. The image sensorS is located below the document support surfaceA and the reading surfaceB.

When the image scannerreads an image of a document supported on the document support surfaceA, the image sensorS reads the image of the document in a line shape in the front-rear direction, that is, in a main scanning direction while moving rightward from below the left end of the document support surfaceA, that is, in a sub-scanning direction by an operation of a scan mechanism (not shown). When the image sensorS moves to a position below the right end of the document support surfaceA, the image sensorS finishes reading (scanning) the image and returns to a standby position by the operation of the scan mechanism (not shown).

When the conveyance unitdescribed later is operated, the image sensorS is moved to a stationary reading position below the reading surfaceB by the operation of the scan mechanism (not shown) and is stopped.

As shown in, the coveris located above the main body. The rear end of the coveris connected to the rear end of the main bodyvia a hinge (not shown). The coveris swingable about a swing axis Xextending in the left-right direction.

As shown in, the coverhas a base member. The lower surface of the base memberforms the bottom surface of the cover. The bottom surface of the coverhas a size capable of covering the document support surfaceA and the reading surfaceB, and covers a document placed on the document support surfaceA.

The base memberis an integrally molded product made of a resin material. In the present embodiment, the base memberis manufactured by injection molding of a thermoplastic resin and so on.

Although not shown, the user swings the coverupward and rearward about the swing axis X, whereby the coveropens the document support surfaceA. In this state, the user places a document on the document support surfaceA and takes out the document.

As shown in, the coverincludes a supply trayand a discharge tray. The supply trayand the discharge trayare located at a right portion of the cover.

As shown in, an upper surface of a right portion of the base memberforms the discharge tray. The discharge traysupports a sheet SH that is conveyed and discharged by the conveyance unitdescribed later.

The supply trayis located above the discharge tray. The supply trayhas a sheet support surface. The sheet support surfacesupports the sheets SH to be scanned, in a stacked state.

In the present embodiment, a target from which an image is read using the document support surfaceA is referred to as a document, and a target from which an image is read while being supported by the sheet support surfaceand being conveyed by the conveyance unitis referred to as the sheet SH. The document and the sheet SH may be substantially the same.

The sheet support surfaceextends so as to be gently inclined downward to the left, and extends in the front-rear direction. The width direction of the sheet support surfaceis the front-rear direction. In the present embodiment, one side in the width direction is the front, and the other side in the width direction is the rear. In the drawings, “one side” means one side in the width direction and “the other side” means the other side in the width direction.

A feed direction DFis a direction in which the sheet SH supported on the sheet support surfaceis fed. The feed direction DFis a direction in which the sheet SH is fed along the sheet support surfaceso as to be gently inclined downward to the left, and is perpendicular to the width direction.

A downstream endD of the sheet support surfacein the feed direction DFis located between a left side surface of the coverand a central portion of the coverin the left-right direction.

As shown in, the coverincludes an upper chute. The upper chuteis located above a left portion of the base memberand below a left-end-side upper surface cover. The upper chuteextends in the left-right direction and the width direction. Although not shown, front and rear end portions of the upper chuteare assembled to front and rear end portions of the left portion of the base member, respectively.

The upper chuteintegrally includes a first trayand a guide portionA. The first trayis a right portion of the upper chute. The guide portionA is a left portion of the upper chute. The first trayextends so as to be gently inclined downward to the left. The guide portionA extends so as to be gently inclined upward to the left, and then is curved downward. The upper surface of the guide portionA constitutes a conveyance guide surfaceG.

The upper chuteis an integrally molded product made of a resin material. In the present embodiment, the upper chuteis manufactured by injection molding of a thermoplastic resin and so on.

A specific configuration of the supply traywill be described. The supply trayincludes the first traydescribed above, and a second trayand a sub-trayshown in.

The first trayhas an upper surface that constitutes a first support surface. The first support surfaceis a part of the sheet support surface, and includes a downstream endD of the sheet support surface.

As shown in, the first support surfaceincludes a central portionC in the width direction, and portionsA andB located on the outer sides in the width direction with respect to the central portionC.

As shown in, the central portionC of the first support surfaceis one step higher than the portionsA andB.

As shown in, the angle at which the central portionC is inclined downward to the left changes in a plurality of stages. The angle at which the portionsA andB are inclined downward to the left also changes in a plurality of stages along the central portionC.

As will be described in detail later, a friction member (friction sheet)is affixed to the central portionC.

As shown in, the second trayis located on the right side of the first tray. The second trayextends so as to be gently inclined downward toward the left, and extends in the width direction. Although not shown, front and rear end portions of the second trayare assembled to the front and rear end portions of the left portion of the base member, respectively, at positions further rightward than the first tray.

The second trayis an integrally molded product made of a resin material. In the present embodiment, the second trayis manufactured by injection molding of a thermoplastic resin and so on.

As shown in, a central portion of the upper surface of the second trayin the width direction constitutes a second support surface. The second support surfaceis a flat surface that is one step higher than portionsA andB located on the outer sides in the width direction with respect to the second support surface.

The second support surfaceis a part of a remaining portion of the sheet support surface. The second support surfaceis adjacent to the first support surfacefrom upstream in the feed direction DF. As shown in, an upstream end and a downstream end of the second support surfacein the feed direction DFare gently curved to prevent the sheet SH from being caught by the edges of the second support surface.

As shown in, the second traysupports a pair of side guidesA andB at the portionsA andB.

Each side guideA,B is of generally identical construction, with mirror image, and includes a guide wallW and a sheet edge support portionC.