Patent Application
20090243184
The present application claims priority from Japanese Patent Application No. 2008-093411, which was filed on Mar. 31, 2008, the disclosure of which is incorporated herein by reference in its entirety.
1. Field of the Invention
The invention relates generally to sheet feed devices which comprise a tray for storing a stack of sheets therein, a feed roller configured to move toward and away from a bottom surface of the tray and to feed a sheet from the stack in the tray, and a separation member configured to separate the sheet fed by the feed roller from the stack of sheets. The invention also relates to image recording apparatus comprising such sheet feed devices.
2. Description of Related Art
A known sheet feed device, e.g., the sheet feed device described in Japanese Laid-Open Patent Application Publication No. 2006-206220, is used in a known image recording apparatus, such as a printer, a facsimile device, or both. The known sheet feed device includes a feed roller positioned at a free end of a pivotable arm, a tray for storing a stack of sheets therein, an inclined separation plate positioned at a downstream end of the tray in a sheet feed direction, and a substantially U-shaped feed path extending between the separation plate and a recording unit. As the feed roller rotates while contacting an uppermost sheet of the stack in the tray, the separation plate separates the uppermost sheet from the stack in the tray, and the uppermost sheet is fed via the U-shaped feed path to the recording unit.
In a known inkjet recording apparatus, the separation plate has a plurality of separation portions positioned in the sheet feed direction, and a roller positioned on each lateral side of the highest one of the separation portions, e.g. the most downstream one of the separation portions. The distance by which each separation portion projects from the inclined surface of the separation plate is substantially equal to the distance by which each roller projects from the inclined surface of the separation surface.
In such sheet feed device, however, a sheet surface may be damaged by some of the separation portions positioned lower than the rollers especially when a sheet having a relatively high rigidity is fed from a relatively low stack of sheets in the tray.
Therefore, a need has arisen for sheet feed devices and image recording apparatus that overcome these and other shortcomings of the related art. A technical advantage of the invention is that a sheet is fed from a stack of sheets in a tray toward a feed path while a surface of the sheet is prevented from being damaged by any of separation portions of a separation plate.
According to an embodiment of the invention, a sheet feed device comprises a tray comprising a holding surface configured to hold a plurality of sheets, a feed unit configured to contact a particular sheet of the plurality of sheets, and to feed at least the particular sheet from the tray in a sheet feed direction, and a separation plate positioned at a downstream end of the tray in the sheet feed direction. The separation plate comprises an inclined surface that is inclined with respect to the holding surface of the tray, a plurality of separation portions configured to separate the particular sheet fed by the feed unit from other sheets of the plurality of sheets held by the tray, wherein at least one of the separation portions projects a first distance from the inclined surface, and the plurality of separation portions is positioned at predetermined intervals in the sheet feed direction, and a particular projection positioned on the inclined surface and configured to project a second distance from the inclined surface, wherein the second distance is greater than the first distance, and the plurality of separation portions comprises a first separation portion positioned upstream of the particular projection in the sheet feed direction, and a second separation portion positioned downstream of the particular projection in the sheet feed direction.
According to another embodiment of the invention, an image forming apparatus comprises a sheet feed device comprising a tray comprising a holding surface configured to hold a plurality of sheets, a feed unit configured to contact a particular sheet of the plurality of sheets, and to feed at least the particular sheet from the tray in a sheet feed direction, and a separation plate positioned at a downstream end of the tray in the sheet feed direction. The separation plate comprises an inclined surface that is inclined with respect to the holding surface of the tray, a plurality of separation portions configured to separate the particular sheet fed by the feed unit from other sheets of the plurality of sheets held by the tray, wherein at least one of the plurality of separation portions projects a first distance from the inclined surface, and the plurality of separation portions is positioned at predetermined intervals in the sheet feed direction, and a particular projection positioned on the inclined surface and configured to project a second distance from the inclined surface, wherein the second distance is greater than the first distance. The image recording apparatus also comprises a recording unit configured to record an image on the particular sheet fed by the sheet feed device, and a sheet discharge unit configured to discharge the particular sheet with an image recorded thereon from the recording unit. The plurality of separation portions comprises a first separation portion positioned upstream of the particular projection in the sheet feed direction, and a second separation portion positioned downstream of the particular projection in the sheet feed direction.
Other advantages of the invention will be apparent to persons of ordinary skill in the art in view of the following detailed description of the invention and the accompanying drawings.
For a more complete understanding of the invention, and the needs satisfied thereby, reference now is made to the following descriptions taken in connection with the accompanying drawings.
Embodiments of the invention may be understood by referring to
An image reading device 5 is positioned, on an upper portion of the housing 2, for reading a document during a copying and/or a facsimile operation of the image recording apparatus 1. The image reading device 5 is vertically pivotable about a pivot located at one end of the housing 2. A glass plate is positioned at the top of the image reading device 5, and is covered by a document cover 6 which is vertically pivotable about a pivot located at a rear end of the image reading device 5. A document is positioned on the glass plate by opening the document cover 6 upward. A scanner, e.g., a contact image sensor, reads an image of the document while reciprocating under the glass plate in a Y-axis direction.
An operation panel 7 is positioned at the top of the housing 2 and in front of the document cover 6, and comprises a plurality of operation buttons and a display device 8, e.g., a liquid crystal display. The operation buttons comprise a start button (not shown) and a stop button (not shown) and are selected to execute various operations. The display device 8 displays setting conditions of the image recording apparatus 1 and operation messages.
A memory slot 11 for receiving external memories is positioned at the front of the housing 2, on an upper side of the opening 2a. The external memories may be, for example, a Compact Flash®, a Smart Media®, a Memory Stick®, a SD card®, and/or a xD card®. Data stored in an external memory inserted in the memory slot 11 may be read into an internal memory of the image recording device 1, and may be printed on a sheet by a recording unit 10.
As shown in
In order to reciprocally move the carriage 13, a timing belt (not shown) is positioned on an upper surface of the second guide member 16. The timing belt extends in the Y-axis direction and is wound around pulleys (not shown). A carriage motor (not shown) configured to drive the timing belt is fixed to a lower surface of the second guide member 16.
A platen 17 has a flat shape and extends in the Y-axis direction to face an underside of the recording head 14 on the carriage 13. The platen 17 is fixed above a bottom plate of the main frame between the first guide member 15 and the second guide member 16.
As shown in
Recording mediums stored in the feed tray 3, which are referred to as “sheets”, include plain paper, thick paper, e.g., postcards and envelops, specialized paper, e.g., glossy paper, and resin films.
Referring to
A pendulum-type feed unit 20 feeds a sheet from the feed tray 3, via a U-shaped feed path 40, to the recording unit 10. The U-shaped feed path 40 changes the sheet feed direction. The feed unit 20 feeds the sheet from the feed tray 3 to the U-shaped feed path 40 in a first direction along the X-axis, and feeds the sheet from the U-shaped feed path 40 to the recording unit 10 in a second direction opposite the first direction.
As shown in
The discharge tray 33, which may be made of synthetic resin by injection molding, is connected to the opposed side plates of the outer storing portion 3d, via a pivot 33a, so as to be vertically pivotable. The discharge tray 33 is placed horizontally on the opposed side plates of the outer storing portion 3d, and is extendable together with the outer storing portion 3d from the opening 2a.
The inner storing portion 3b of the feed tray 3 comprises a pair of side guides 41. The side guides 41 extend in the sheet feed direction (X-axis direction), and position and guide side edges of the sheets stored in the inner storing portion 3b. The outer storing portion 3d of the feed tray 3 comprises a tail guide (not shown) that is movable in the X-axis direction so as to contact trailing edges of the sheets.
The side guides 41 are positioned on the bottom plate 3a between the opposed side plates 3c and are slidable in the Y-axis direction such that the distance therebetween is increased and decreased. Each of the side guides 41 comprises a slider 43 and a stopper 42, and one of the side guides 41 comprises a lock member (not shown) with a handle.
Each slider 45 is slidable along an upper surface of the bottom plate 3a and supports a lower surface of the sheets. The stopper stands upright, and contacts the side edges of the sheets.
Racks 46 connected to the side guides 41 engage a pinion 47 positioned at a widthwise center (center in the Y-axis direction) of the feed tray 3. Thus, the distance between the side guides 41 are adjusted, such that a widthwise centerline of the feed tray 3 aligns with a widthwise centerline of the sheets.
The lock member is configured to engage one of teeth formed in the upper surface of the bottom plate 3a. When the handle is operated, the lock member is released from the bottom plate 3a.
As shown in
A pair of friction members, e.g., cork plates, is fixed to an upper surface of the bottom plate 3a of the feed tray 3 to receive the pair of feed rollers 20a when the arm 20c pivots downward. This prevents two or more sheets from being fed together by the feed rollers 20a when only a small number of sheets are left in the feed tray 3.
Separation portions 23 are positioned on an inner surface 21a of the inclined separation plate 21 at a central portion of the inclined separation plate 21 in the Y-axis direction, e.g., in a widthwise direction of the sheet. The separation portions 23 are positioned at intervals, in the sheet feed direction from an upstream side (side closer to the bottom plate 3a ) toward a downstream side (side remoter from the bottom plate 3a) and project from the inner surface 21a.
As shown in
As shown in
As shown in
When the separation member 22 is inserted into the case 29, such that the separation portions 23 are fitted into the holes 27, and the supporting member 28 is attached to the case 29, the elastic legs 26 may be supported by the supporting member 28. Consequently, as shown in
As shown in
Moreover, if the U-shaped feed path 40 has a relatively small radius of curvature, then when an uppermost sheet P is fed by the feed rollers 20a and the separation portions 23 from the stack, e.g., the plurality of sheets, which is within the maximum stacking height H2, a surface of the upper most sheet P may be pressed against the separation portions 23 positioned at a predetermined height from the upper surface of the bottom plate 3a. In this instance, separation portions 23 may scratch or otherwise damage a calendered or coated surface of the sheet P.
In order to prevent damage to the surface of the sheet P by the separation portions, projections 50 may be formed on the upper surface 21a of the inclined separation plate 21 at positions downstream of the maximum stacking height H2 in the sheet feed direction. The separation portions 23 project from the upper surface 21a by a distance T1, and the projections 50 project from the upper surface 21a by a distance T2 that is greater than the distance T1. The projections 50 may be formed integrally with the inclined separation plate 21 when the inclined separation plate 21 is made of synthetic resin by injection molding. The maximum stacking height H2 may be selected relative to one or more of the angle of inclination of the inclined separation plate 21 with respect to the bottom plate 3a, the projected distance of the separation portions 23, the radius of curvature of the U-shaped feed path 40, the sheet drawing force of the rollers 20a, and the like.
As shown in
Each of the projections 50 has a substantially triangular cross-section as viewed from a side of the inclined separation plate 21, e.g., as viewed from a direction perpendicular to the sheet feed direction. The projection 50 may have a trapezoidal cross-section as viewed from the side of the inclined separation plate 21. In other words, the projection 50 may have a substantially triangular outline or may have a substantially trapezoidal outline as viewed from the side of the inclined separation plate 21. The sixth separation portion 23 may be aligned with the associated projection 50, e.g., within the outline of the associated projection 50, as viewed from the side of the inclined separation plate 21. Moreover, the eighth separation portion 23 also may be aligned with the associated projection 50, e.g., within the outline of the associated projection 50, as viewed from the side of the inclined separation plate 21.
The projection 50 has a first sloping surface, e.g., first slope 50a, positioned upstream in the sheet feed direction and a second sloping surface, e.g., second slope 50b, positioned downstream in the sheet feed direction. The inclination of the first sloping surface, e.g., first slope 50a, with respect to the upper surface 21a is relatively slight while the inclination of the second slop 50b with respect to the upper surface 21a is relatively steep. In an embodiment of the invention, an angle formed between the first sloping surface, e.g., first slope 50a, and the upper surface 21a may be greater than an angle formed between the second sloping surface, e.g., second slope 50b, and the upper surface 21a. Accordingly, a contact angle of the leading edge of the sheet P with the first sloping surface, e.g., first slope 50a, may be relatively small, e.g., slightly greater than a contact angle of the leading edge of the sheet P with the upper surface 21a. This configuration may reduce a resistance to feed of the sheet P and may allow the sheet P to be guided smoothly toward the feed path 40.
In addition, a distance by which the projection 50 located upstream in the sheet feed direction projects from the upper surface 21a may be greater than a distance by which the projection 50 located downstream projects from the upper surface 21a. A bent surface of the sheet P may contact the upstream projections 50 earlier than the bent surface of the sheet P may contact the downstream projections 50, and the upstream projections 50 may prevent the bent surface from contacting the separation portions 23 positioned downstream of the position at which the sheet P is stacked in the feed tray 3.
As shown in
In an embodiment of the invention, e.g., in the embodiments shown in
Similarly to the embodiment shown in
In embodiments in which two or more projections 50, 51, 54, 55 are formed along the row of separation portions 23, the projections 50, 51, 54, 55 may be formed such that at least one separation portion 23 is interposed between adjacent two projections 50, 51, 54, 55, as viewed from a side of the inclined separation plate 21, e.g., as viewed from a direction perpendicular to the sheet feed direction.
In an embodiment of the invention, feed tray 3 may be a center registration type feed tray, in which the widthwise center of the sheets guided by the pair of side guides 41 remains at the same position regardless of the size of sheet guided, the projections 50-55 may be formed at a central portion of the inclined separation plate 21 in the Y-axis direction, e.g., in a widthwise direction of the sheet.
In each of the embodiments shown in
In embodiments, e.g., in the above-described embodiments, in which the inclined separation plate 21 comprises synthetic resin, the projections 50-55 may be integrally and simultaneously formed with the inclined separation plate 21 by injection molding.
While the invention has been described in connection with preferred embodiments, it will be understood by those of ordinary skill in the art that other variations and modifications of the preferred embodiments described above may be made without departing from the scope of the invention. Other embodiments will be apparent to those skilled in the art from a consideration of the specification or practice of the invention disclosed herein. It is intended that the specification and the described examples only are considered as exemplary of the invention, with the true scope of the invention being defined by the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2008-093411 | Mar 2008 | JP | national |
