Patent Application
20110074094
The present application claims priority from Japanese Patent Application No: 2009-227517, which was filed on Sep. 30, 2009, the disclosure of which is herein incorporated by reference in its entirety.
1. Field of the Invention
The present invention relates to a sheet feeder in which sheets are separated by separation protrusions when the sheets held on a holding portion are fed along an inclined member, and an image recording apparatus equipped with such a sheet feeder.
2. Discussion of Related Art
An image recording apparatus such as an ink-jet printer is equipped with a sheet feeder configured to feed recording sheets accommodated in a sheet tray to a sheet transfer path by a rotational force of a roller. The roller is rotated while being held in contact with an uppermost one of the recording sheets on the sheet tray, whereby the rotational force of the roller is transmitted to the uppermost sheet and the uppermost sheet is fed into the sheet transfer path from the sheet tray. As such a sheet feeder, there is known one having a structure in which metal separation protrusions are provided on an inclined guide surface that is disposed at one end of the sheet tray for preventing so-called multiple feeding of the recording sheets (i.e., multiple sheet feeding) in which a plurality of sheets on the sheet tray are fed at one time.
The separation protrusions described above are formed as follows. A metal plate punched into a suitable shape, and portions of the metal plate that give the separation protrusions are bent so as to stand from a main body of the metal plate. The separation protrusions are inserted through corresponding windows (openings) formed in a guide plate that provides the inclined guide surface, from the back side of the guide plate, whereby the separation protrusions protrude from the inclined guide surface.
For fixing the metal plate to a predetermined position of the guide plate, there is provided a cover that covers the entirety of the metal plate. The cover presses the metal plate onto a back surface of the guide plate opposite to the inclined guide surface and supports the periphery of the metal plate. Each of the cover and the guide plate is a molded product formed of a synthetic resin. The cover is fixed to the guide plate by engagement therewith. The cover that covers the metal plate has a larger size than the metal plate. Accordingly, the guide plate is designed to have a sufficiently larger size than the cover for permitting the cover to be fixed thereto such that the cover does not protrude upwardly from the inclined guide surface. It is, however, desirable that the guide plate has a minimum height dimension in view of demands for reduction in the thickness and the size of the image recording apparatus.
It is therefore an object of the invention to provide a sheet feeder in which an inclined member having separation protrusions for separating sheets has a reduced height and an image recording apparatus equipped with such a sheet feeder.
The above-indicated abject may be attained according to a principle of the invention, which provides a sheet feeder, comprising:
The above and other objects, features, advantages and technical and industrial significance of the present invention will be better understood by reading the following detailed description of an embodiment of the invention, when considered in connection with the accompanying drawings, in which:
There will be hereinafter described one preferred embodiment of the invention with reference to the drawings. It is to be understood that the embodiment described below may be otherwise modified without departing from the scope of the invention defined in the attached claims.
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In the present embodiment, the directions indicated by arrows 101, 102, 108 in the drawings are a width direction, a height direction, and a depth direction, of the printer 11, respectively. The direction 101 may also be referred to as “a sheet width direction” which is a width direction of each of the recording sheets that is fed. Further, the direction 103 may also be referred to as “a supply direction” in which each of the recording sheets in the sheet cassette 20 is sent.
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On the rear side of the sheet cassette 20, there is disposed an inclined member 24 that stands relative to the bottom plate 21. The inclined member 24 is disposed downstream of the recording sheets placed on the bottom plate 21 in the supply direction 103 and has a flat plate-like shape extending in the width direction 101. The inclined member 24 is inclined such that its upper end portion is located more downstream than its lower end portion in the sheet feed direction 104. Owing to the inclination of the inclined member 24, an inclined surface 26 with which the leading edge of each of the recording sheets comes into contact is formed so as to face the leading edge of each of the sheets on the bottom plate 21. The upper surface of the bottom plate 21 is substantially horizontal when the sheet cassette 20 is installed on the printer 11. The upper surface of the bottom plate 21 and the inclined surface 26 form a predetermined angle. The inclined member 24 will be explained in detail.
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The above-indicated supply portion 29 and sheet cassette 20 constitute a sheet feeder according to the invention.
A sheet transfer roller 41 and a pinch roller 42 are provided in the straight portion 33 of the sheet transfer path 23. These rollers 41, 42 are disposed on a more upstream side than the recording portion 25 in a direction in which the sheet is transferred. The sheet transfer roller 41 and the pinch roller 42 form a pair. The pinch roller 42 is movable so as to come into contact with and retract from the sheet transfer roller 41, and is biased by a spring for pressing contact. with the sheet transfer roller 41. The sheet transfer roller 41 is configured to be rotated by a drive force transmitted from a motor not shown. The recording sheet held by and between the sheet transfer roller 41 and the pinch roller 42 is transferred to the recording portion 25 by the rotation of the sheet transfer roller 41.
A sheet discharge roller 43 and a spur 44 are provided in the straight portion 33 of the sheet transfer path 23. The sheet discharge roller 43 and the spur 44 are disposed on a more downstream side than the recording portion 25 in the direction in which the sheet is transferred. The sheet discharge roller 43 and the spur 44 form a pair. The spur 44 is movable so as to come into contact with and retract from the sheet discharge roller 43, and is biased by a spring for pressing contact with the sheet discharge roller 43. The sheet discharge roller 43 is configured to be rotated by a drive force transmitted from a motor not shown. The rotation of the sheet discharge roller 43 is synchronism with the rotation of the sheet transfer roller 41. The recording sheet held by and between the sheet discharge roller 43 and the spur 44 is transferred to the sheet receiving tray 22 by the rotation of the sheet discharge roller 43.
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The carriage 46 is configured to reciprocate, together with the recording head 48, in the width direction 101, i.e., in a direction perpendicular to the sheet plane of
During the reciprocating movement of the carriage 46 in the width direction 101, minute ink droplets are selectively ejected from the recording head 48 toward the recording sheet on the platen 47. The ejected ink droplets are attached to the recording sheet, whereby an image is recorded on the recording sheet. The ink is supplied from an ink cartridge not shown to the recording head 48. The recording portion 25 is one kind of a recording device.
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The angle defined by the inclined surface 26 and the upper surface of the bottom plate 21 is determined to be a suitable value that permits the recording sheet to be flexed without stopping for changing the traveling direction of the sheet to the slantingly upward direction, when the recording sheet placed on the bottom plate 21 of the sheet cassette 20 is fed and its leading edge comes into contact with the inclined surface 26. Where the angle defined by the inclined surface 26 and the upper surface of the bottom plate 21 becomes large or becomes close to 90°, namely, where the inclined surface 26 is formed so as to become close to a vertical plane, the recording sheet tends to stop when its leading edge comes into contact with the inclined surface 26, thereby causing a risk of so-called sheet misfeeding or sheet feeding failure in which the recording sheet is not actually fed even though the sheet supply roller 30 operates to feed the sheet. On the other hand, when the angle defined by the inclined surface 26 and the upper surface of the bottom plate 21 becomes small or becomes close to 0°, the height of the inclined surface 26 decreases, resulting in a decrease of the number of the recording sheets that can be placed on the sheet cassette 20. Accordingly, the angle of the inclined surface 26 relative to the bottom plate 21 is suitably set such that the recording sheet can be smoothly guided while taking account of the number of the sheets placed on the sheet cassette 20.
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At a middle position of the spring plate member 60 in the width direction 101, six second separation protrusions 52 are formed by punching and bending. Each second separation protrusion 52 stands from a main body of the spring plate member 60 toward the inclined member 24 and is bent in a suitable direction. The amount by which each second separation protrusion 52 stands from the main body of the spring plate member 60 is determined depending upon the thickness of the inclined member 24. As shown in
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The recording sheets are inserted onto the bottom plate 21 of the sheet cassette 20 from the front side of the printer 11. The inserted recording sheets slide on the bottom plate 21 or on other recording sheets which have been already placed on. the bottom plate 21, so that the leading edges of the recording sheets come into contact with the inclined surface 26. When the recording sheets are loaded onto the sheet cassette 20 with a great force, the leading edges of the sheets tend to move in the slantingly upward direction along the inclined surface 26. However, the leading edges of the sheets come into contact with the second separation protrusions 52 disposed on the lower side of the specific position 105, whereby the sheets are prevented from moving toward the upper side of the specific position 105.
When the supply portion 29 operates, the uppermost one of the sheets stacked on the bottom plate 21 of the sheet cassette 20 is fed in the sheet feed direction 104 by the rotation of the sheet supply roller 30. On this occasion, the recording sheets under the uppermost sheet are sometimes fed in the sheet feed direction 104 together with the uppermost sheet, due to the friction, the static electricity, generated between the sheets, or the like. The leading edges of the thus fed recording sheets come into contact with at least one of the first separation protrusions 51 and the second separation protrusions 52 when the sheets are guided in the slantingly upward direction along the inclined surface 26.
The recording sheets are further moved or fed in the sheet feed direction 104 such that the leading edges thereof slide on at least one of the first separation protrusions 51 and the second separation protrusions 52. Each of the first separation protrusions 51 and each of the second separation protrusions 52 are inclined such that an angle defined by the upper surface of the bottom plate 21 and a contact surface of the first separation protrusion 51 or the second separation protrusion 52 with which the sheet comes into contact is made larger than an angle defined by the upper surface of the bottom plate 21 and the inclined surface 26. In other words, each first separation protrusion 51 and each second separation Protrusion 52 are formed so as to become close to a vertical plane. Accordingly, each of the first and second separation protrusion 51, 52 protrude from the inclined surface 26 toward the recording sheets on the bottom plate 21. Therefore, each of the first and second separation protrusion 51, 52 exhibits, with respect to the leading edges of the recording sheets, a braking action to hinder the feeding of the recording sheets in the sheet feed direction 104. According to the arrangement, the braking action of each first separation protrusion 51 or the braking action of each second separation protrusion 52 works on the recording sheets which are fed in the sheet feed direction 104 by a smaller force, namely, the recording sheets other than the uppermost sheet contacting the sheet supply roller 30, among the recording sheets to come into sliding contact with the first separation protrusions 51 or the second separation protrusions 52.
In an instance where the recording sheets other than the uppermost sheet cannot be completely stopped in spite of the above-described braking action of one first separation protrusion 51 or one second separation protrusion 52 on which the sheets have slid, and pass over that one first or second separation protrusion 51, 52 after all, the recording sheets subsequently come into contact with next first or second separation protrusion 51, 52 that is disposed immediately downstream of that one first or second separation protrusion 51, 52 in the sheet feed direction 104. In particular, the first separation protrusions 51 are provided on the inclined surface 26 such that any adjacent two first separation protrusions 51 partly overlap each other as described above. Accordingly, the leading edges of the recording sheets come into contact with the next first separation protrusion 51 without contacting the inclined surface 26 after having passed over that one first separation protrusion 51. Thus, the above-described braking action is always exhibited, with respect to the recording sheets, between any adjacent two first separation protrusions 51.
Unlike the lust separation protrusions 51, the second separation protrusions 52 do not overlap each other. However, when the leading edges of the recording sheets reach the next second separation protrusion 52 located immediately downstream of the one second separation protrusion 52 over which the leading edges of the recording sheets have passed, the above-described braking action is similarly exhibited. Should the leading edges of the recording sheets pass over all of the second separation protrusions 52, the first separation protrusions 51 are disposed on the downstream side of the second separation protrusions 52 in the sheet feed direction 104. Accordingly, every time when the leading edges of the recording sheets pass over each first separation protrusion 51, the recording sheets repeatedly undergo the braking action, whereby the leading edges of the recording sheets are separated.
In the illustrated embodiment, the first separation protrusions 51 and the second separation protrusions 52 are arranged in a row in the sheet feed direction 104 so as to protrude from the inclined surface 26, whereby the leading edges of the recording sheets are separated by the first separation protrusions 51 or the second separation protrusions 52. Accordingly, the arrangement prevents the multiple sheet feeding in which a plurality of sheets are fed at a time so as to overlap each other.
In the illustrated embodiment, the first separation protrusions 51 are disposed on the inclined member 24 so as to be located on the upper side of, namely, on the downstream side of the second separation protrusions 52. Accordingly, it is possible to reduce the area in which the second separation protrusions 52 are disposed, without lowering the sheet separation ability. The reduction in the area of the second separation protrusions 52 results in a reduction in the size of the spring plate member 60, so that the cover 57 that supports the elastic legs 61 of the spring plate member 60 can be downsized. Accordingly, the size of the inclined member 24 can be reduced in the height direction 102, leading to slimming down of the sheet cassette 20 and accordingly slimming down of the printer 11 as a whole.
Each of the first separation protrusions 51 is formed such that the distal end 53 of one first separation protrusion 51 is located more downstream in the sheet feed direction 104 than the proximal end 54 of another first separation protrusion 51 that is located immediately downstream of that one first separation protrusion 51 in the sheet feed direction 104. Accordingly, after the leading edges of the recording sheets have passed over the one first separation protrusion 51, the leading edges come into contact with the next first separation protrusion 51 located immediately downstream of the one first separation protrusion 51, without contacting the inclined surface 26. Therefore, the above-described braking action is always exhibited with respect to the recording sheets, resulting in improved sheet separation ability.
The first separation protrusions 51 are disposed on the upper side of, namely, on the downstream side of, the specific position 105 of the inclined surface 26 with which the uppermost one of the recording sheets comes into contact at a time when a maximum amount of the recording sheets are placed on the bottom plate 21 of the sheet cassette 20, and the second separation protrusions 52 are disposed on the lower side of, namely, on the upstream side of, the specific position 105. When the recording sheets are placed on the bottom plate 21 of the sheet cassette 20, the leading edges of the recording sheets that have contacted the inclined surface 26 come into contact with the second separation protrusions 52, so that the recording sheets are prevented from traveling in the sheet feed direction 104 along the inclined surface 26. Such an effect, in other words, the effect of preventing the leading edges of the recording sheets from jumping out of the sheet cassette 20 when the sheets are loaded on the sheet cassette 20, can be ensured for a long time period with high stability since each second separation protrusion 52 is formed of a metal that is hard to change with a lapse of time, as compared with a synthetic resin.
Since the first separation protrusions 51 and the second separation protrusions 52 are formed in one row along the sheet feed direction 104, the leading edge of each recording sheet that is fed on the inclined surface 26 comes into contact with the first and second separation protrusions 51, 52 constantly at the same position of the inclined surface 26 in the width direction 101. Accordingly, it is easy to design the layout of the first separation protrusions 51, the second separation protrusions 52, the sheet supply roller 30, and so on, so as to prevent skewing of the recording sheet due to contact with the first separation protrusions 51 and the second separation protrusions 52.
The plurality of second separation protrusions 52 are arranged in the sheet feed direction 104, so that the number of contact of the leading edge of the recording sheet with the second protrusions 52 increases. Accordingly, the sheet separation ability can be improved.
The first separation protrusions 51 and the second separation protrusions 52 may be disposed at mutually different positions on the inclined surface 26 in the width direction 101. Further, the row of the first separation protrusions 51 and the second separation protrusions 52 may be arranged in a plural number in the width direction 101.
While the plurality of first separation protrusions 51 are provided in the illustrated embodiment, the number of the first separation protrusion 51 may be at least one. Where the plurality of first separation protrusions 51 are provided, the first separation protrusions 51 may not overlap each other.
The positions of the respective first separation protrusions 51 may be on the upper side or on the lower side of the above-indicated position of the inclined surface 26 with which the leading edge of the uppermost one of the recording sheets come into contact at a time when a maximum amount of the recording sheets axe placed on the bottom plate 21 of the sheet cassette 20.
The inclined member 24 need not be formed integrally with the sheet cassette 20, provided that the inclined member 24 is disposed to face the leading edges of the recording sheets. Accordingly, the inclined member 24 may be provided on the printer 11 so as to be independently of the sheet cassette 20.
It is to be understood that the present invention may be otherwise embodied with various changes and modifications, which may occur to those skilled in the art, without departing from the scope of the invention defined in the attached claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2009-227517 | Sep 2009 | JP | national |
