Patent Application
20110074092
The present application claims priority from Japanese Patent Application No. 2009-227261, 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 a plurality of sheets which are fed at one time are separated by separation protrusions when the sheets held on a holding portion are fed along a guide 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 an image recording portion 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 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 feeding only one of the recording sheets on the sheet tray.
The separation protrusions described above are formed as follows. A metal plate is 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. The protrusion amount by which each separation protrusion protrudes from the inclined guide surface is determined by considering an ability of the separation protrusions for separating the recording sheets, i.e., the sheet separation ability. The separation protrusions are formed such that portions of one metal plate that give the separation protrusions are cut and bent so as to protrude from the inclined guide surface. Accordingly, there is a limit to a reduction of the pitch at which the separation protrusions are arranged.
It is therefore an object of the invention to provide a sheet feeder in which separation protrusions are arranged at a reduced pitch and an image recording apparatus equipped with such a sheet feeder.
The above-indicated object may be attained according to a principle of the invention, which provides a sheet feeder, comprising:
a holding portion having a holding surface on which a plurality of sheets are held in a stack;
a supply portion configured to supply the plurality of sheets sequentially from an uppermost one of the plurality of sheets held on the holding portion;
an inclined member disposed downstream of the holding portion in a direction in which the sheets are supplied by the supply portion and having an inclined surface that faces a leading edge of each of the sheets held on the holding portion while inclining relative to the holding surface, the inclined member being configured to guide said each of the sheets supplied from the holding portion in a sheet feed direction in which said each of the sheets is fed along the inclined surface;
a plurality of first separation protrusions which are provided on and integrally with the inclined member and each of which protrudes from the inclined surface such that a distal end thereof is located more downstream in the sheet feed direction than a proximal end thereof, the plurality of first separation protrusions being arranged in the sheet feed direction; and
a plurality of second separation protrusions which are formed of a metal and each of which protrudes from the inclined surface through a corresponding one of openings that is formed in the inclined member at a position in the sheet feed direction between corresponding adjacent two of the plurality of first separation protrusions, the plurality of second separation protrusions being arranged in the sheet feed direction.
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 embodiments 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.
As shown in
In the present embodiment, the directions indicated by arrows 101, 102, 103 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.
As shown in
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 so as to face the leading edge of each of the recording sheets placed on the bottom plate 21 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.
As shown in
As shown in
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.
As shown in
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.
As shown in
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.
As shown in
Each first separation protrusion 51 protrudes from the inclined surface 26 toward the recording sheets on the bottom plate 21 of the sheet cassette 20 and has two arms at its proximal end 54 that are integrally connected to each other at its distal end 53. 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, 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 are prevented from jumping out of the sheet cassette 20 by contacting at least one of the first separation protrusions 51 and the second separation protrusions 52.
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 separation protrusions 51, 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 some of the separation protrusions 51, 52. Each of the first and second separation protrusion 51, 52 exhibits a braking action to hinder the feeding of the recording sheets in the sheet feed direction 104 owing to the inclinations thereof. According to the arrangement, the braking action of each of the separation protrusions 51, 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 separation protrusions 51, 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 in the sheet feed direction 104 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 first 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. In the present embodiment, in particular, 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, each of the second separation protrusions 52 formed of a metal protrudes from the inclined surface 26 by a desired amount while the first separation protrusions 51 are disposed such that one first separation protrusion 51 is disposed between corresponding adjacent two of the second separation protrusions 52. Accordingly, it is possible to improve the separation ability to separate the recording sheets supplied from the sheet cassette 20.
In the illustrated embodiment, the first separation protrusions 51 are formed integrally with the inclined member 24 formed of a synthetic resin. Accordingly, each of the recording sheets is prevented from being damaged when the sheet slides on the first separation protrusions 51. The second separation protrusions 52 formed of a metal have a high degree of durability with respect to the sliding contact with the recording sheet, ensuring stabilized sheet separation ability for a long period of time.
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, the sheet separation ability can be improved by decreasing distances between any adjacent two first separation protrusions 51, thereby enhancing the ability of the first separation protrusions 51 for preventing multiple sheet feeding.
The protrusion amount L2 by which each second separation protrusion 52 protrudes from the inclined surface 26 is made smaller than the protrusion amount L1 by which each first separation protrusion 51 protrudes from the inclined surface 26, whereby the recording surface of each of the recording sheets that are fed along the inclined surface 26 slides mainly on the first separation protrusions 51 and is hard to contact the second separation protrusions 52. The arrangement reduces a risk that the recording surface of each recording sheet is damaged when the sheet supplied from the sheet cassette 20 is fed along the inclined surface 26.
There will be next explained a modified embodiment with reference to
As shown in
On opposite sides of the row of the second separation protrusions 52 in the width direction 101, first separation protrusions 61, 62 are provided. While the reference numerals are partly omitted in
Each of the second separation protrusions 52 is disposed such that any one of the second separation protrusions 52 is sandwiched between a corresponding one of the first separation protrusions 61 and a corresponding one of the first separation protrusions 62 disposed in the staggered fashion in the sheet feed direction 104 described above. When the layout of the first separation protrusions 61, 62 and the second separation protrusions 52 is explained focusing on the positions of the respective top ends of the first separation protrusions, 61, 62 and the second separation protrusions 52, it can be said that a sequence of one first separation protrusion 61, one second separation protrusion 52, and one first separation protrusion 62 is repeated in the sheet feed direction 104.
The first separation protrusions 61, 62 are disposed on opposite sides of the row of the second separation protrusions 52 in the width direction as described above, thereby decreasing the pitch at which the first separation protrusions 61, 62 and the second separation protrusions 52 are arranged in the sheet feed direction 104. Further, the extension direction of the first separation protrusion 61 and the extension direction of the first separation protrusion 62 intersect the sheet feed direction 104, thereby increasing a distance by which the leading edge of the recording sheet slides on each of the first separation protrusions 61, 62.
In the modified embodiment of
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.
The shape of each of the first separation protrusions 61, 62 may be suitably changed. Moreover, the first separation protrusions 61 may not overlap each other in the sheet feed direction 104 and the first separation protrusions 62 may not overlap each other in the sheet feed direction 104, as long as each of the first separation protrusions 61, 62 is disposed so as to be located intermediate between corresponding adjacent two second separation protrusions 52.
The protrusion amount L1 of the first separation protrusions 51 and the protrusion amount L2 of the second separation protrusions 52 may be suitably determined respectively depending upon the rigidity of the first separation protrusions 51 and the rigidity of the second separation protrusions 52, etc. For instance, the protrusion amount L1 and the protrusion amount L2 may be equal to each other (L1=L2), or the protrusion amount L2 may be larger than the protrusion amount L1 (L1<L2).
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 |
|---|---|---|---|
| 2009-227261 | Sep 2009 | JP | national |
