Patent Application
20240425312
This application claims priority to Japanese Patent Application No. 2023-101179 filed on Jun. 20, 2023, the entire contents of which are incorporated by reference herein.
The present disclosure relates to sheet feeders capable of pulling out and feeding a sheet from a multi-purpose tray or a sheet supply cassette and image forming apparatuses including the sheet feeders and particularly relates to a technique for reducing the load on a pick-up roller in pulling out a sheet from the multi-purpose tray.
An image forming apparatus is an apparatus that forms an image on a recording paper sheet and includes a sheet supply cassette capable of supplying recording paper sheets or a multi-purpose tray for manual feed of a recording paper sheet. The multi-purpose tray is provided in the interior of the apparatus body. When a recording paper sheet is manually placed on the multi-purpose tray, a pick-up roller pulls out and feeds the recording paper sheet from the multi-purpose tray.
There is known a sheet conveying device in which a manual feed unit is mounted over a sheet supply cassette, a manual feed conveyance path for use in conveying a sheet pulled out from the manual feed unit is merged downstream with a cassette conveyance path for use in conveying a sheet pulled out from the sheet supply cassette, and the sheet in the cassette is pulled out by a sheet feed unit provided in the cassette conveyance path. Furthermore, this sheet conveying device is designed to allow a conveyance roller provided at the manual feed unit to convey a sheet from the manual feed conveyance path to the cassette conveyance path, then stop the conveyance roller based on detection of a leading end of the sheet by a leading-end detecting device disposed between the conveyance roller and the sheet feed unit, move the leading end of the sheet before the sheet feed unit, allow the conveyance roller to convey the sheet again, and allow the sheet feed unit to pull out the sheet from the manual feed unit.
A technique improved over the aforementioned techniques is proposed as one aspect of the present disclosure.
A sheet feeder according to an aspect of the present disclosure includes a sheet supply cassette, a multi-purpose tray, a guide roller, an elastic support member, and a pick-up roller. The sheet supply cassette supplies a sheet accommodated therein. The multi-purpose tray is provided above the sheet supply cassette and receives a sheet for manual feed placed thereon. The guide roller is provided at an end of the multi-purpose tray to come into contact with the sheet protruding from the end of the multi-purpose tray. The elastic support member is provided at the end of the multi-purpose tray and supports the guide roller elastically and movably in directions toward and away from the sheet supply cassette. The pick-up roller is disposed apart from the end of the multi-purpose tray movably in the directions toward and away from the sheet supply cassette and, when moved toward the sheet supply cassette, the pick-up roller pulls out the sheet protruding across an upper side of a peripheral surface of the guide roller from the end of the multi-purpose tray while being pressed against a leading end portion of the sheet. A position of the pick-up roller to be pressed against the leading end portion of the sheet is located closer to the sheet supply cassette than the upper side of the peripheral surface of the guide roller.
An image forming apparatus according to another aspect of the present disclosure includes: the sheet feeder according to the one aspect of the present disclosure; and an image forming device that forms an image on a sheet pulled out and fed from the multi-purpose tray or the sheet supply cassette of the sheet feeder.
Hereinafter, a description will be given of an embodiment of the present disclosure with reference to the drawings. Hereinafter, directions of rotation and right, left, upward and downward directions may be shown, but they are shown only as examples in the drawings unless otherwise stated.
As shown in
The image forming device forms an image shown by image data, based on an electrophotographic process using a toner, on the recording paper sheet P pulled out and fed from the sheet supply cassette 11 or the multi-purpose tray 12 by the sheet feed device 13 of the sheet feeder 10. The recording paper sheet with an image formed thereon is subjected to fixation processing of the fixing device and then ejected to the sheet output tray 3.
A sidewall 2A of the apparatus body 2 of the image forming apparatus 1 is supported on the apparatus body 2 by a pin 2B provided at a lower end portion of one side surface of the sidewall 2A and is movable to open and close with respect to the apparatus body 2 by the pin 2B.
When the sidewall 2A is opened, an opening 2D leading to the interior of the apparatus body 2 becomes open. The sidewall 2A is made open in an inclined position where its end close to the apparatus body 2 is located lower than the other end. A recording paper sheet P is placed on the upper surface of the opened and inclined sidewall 2A and introduced from the sidewall 2A onto the multi-purpose tray 12.
As shown in
A recording paper sheet P for conveyance through manual feed is inserted from the sidewall 2A by the user and thus placed on the multi-purpose tray 12. The placed recording paper sheet P is introduced from the sidewall 2A to a conveyance path 17 on the multi-purpose tray 12, inserted between the driven rollers 15 and the conveyance rollers 16, and conveyed via a distal end of the multi-purpose tray 12 to the sheet feed device 13 by counterclockwise rotation of the conveyance rollers 16 in
The sheet supply cassette 11 is internally provided with a tray 24 on which a stack of recording paper sheets P are to be placed, and a separating pad 25 is fixed on a distal end portion of the upper surface of the tray 24. An innermost end of the tray 24 is supported, pivotally about a pin provided at the innermost end thereof, on the inside surface of the sheet supply cassette 11 to allow the distal end of the tray 24 to move up and down (in directions toward and away from the pick-up roller 21). An arm 28 is provided under the tray 24. A lower end of the arm 28 is supported pivotally about a pin provided at the lower end thereof to allow its upper end to move up and down. When the arm 28 is pivotally moved upward by an unshown mechanism and the upper end (the distal end) of the arm 28 thus lifts the tray 24 from below, the tray 24 pivotally moves about the pin located at the innermost end thereof, the distal end of the tray 24 moves close to the pick-up roller 21, and the tray 24 thus becomes inclined.
Furthermore, the support portion 31 is supported rotatably about the shaft 22A of the feed roller 22 on the shaft 22A and pivotally moved within a certain range of angles by an unshown mechanism. When, as shown in
A shaft 23A of the retard roller 23 is supported rotatably at a fixed position of a frame of the sheet feeder 10. The retard roller 23 always abuts on the lower side of the peripheral surface of the feed roller 22.
On the other hand, a guide roller 41 is provided at a distal end of the guide plate 14 of the multi-purpose tray 12 and projects beyond the distal end of the guide plate 14 toward the sheet feed device 13.
The spring member 42 includes: two arms 42A; a connecting portion 42B connecting between respective root ends of the arms 42A; and respective bearings 42C formed by bending respective distal end portions of the arms 42A into loops.
The connecting portion 42B of the spring member 42 is fitted into a groove between two raised portions 14C provided on the underside surface of the guide plate 14 of the multi-purpose tray 12, the arms 42A of the spring member 42 are passed along the respective inside surfaces of two small walls 14D provided on the underside surface of the guide plate 14 of the multi-purpose tray 12 and are engaged with respective pawls 14E formed on the inside surfaces of the small walls 14D, and, thus, the spring member 42 is seated to the distal end portion of the guide plate 14 of the multi-purpose tray 12.
Furthermore, both ends of the shaft 41A of the guide roller 41 are inserted into the respective looped bearings 42C located at the distal ends of the arms 42A of the spring member 42 and, thus, the guide roller 41 is rotatably supported by the bearings 42C.
Moreover, each of the arms 42A is elastically upwardly and downwardly deformable in a range from a portion thereof engaged with the pawl 14E of the small wall 14D to the bearing 42C located at the distal end of the arm 42A. Therefore, the guide roller 41 is supported rotatably, upwardly and downwardly movably, and elastically by the spring member 42. In other words, each arm 42A acts as an example of the elastic support member defined in CLAIMS to support the guide roller 41 elastically and movably in directions toward and away from the sheet supply cassette 11.
Suppose that, in the structure described so far, a recording paper sheet P is placed on the multi-purpose tray 12 as shown in
Furthermore, as shown in
Since, in this manner, the guide roller 41 follows the downward inclination of the recording paper sheet P and is pushed down and back by the recording paper sheet P and the recording paper sheet P then slides on the upper side of the peripheral surface of the guide roller 41 to rotate the guide roller 41, the pressing force of the recording paper sheet P on the multi-purpose tray 12 is reduced and the frictional force given to the multi-purpose tray 12 by the recording paper sheet P during conveyance of the recording paper sheet P by the pick-up roller 21 is thus reduced. Therefore, the conveyance of the recording paper sheet P on the multi-purpose tray 12, the pullout of the recording paper sheet P from the multi-purpose tray 12 by the pick-up roller 21, and the conveyance of the recording paper sheet P by the feed roller 22 can be smoothly performed and, thus, the load on the pick-up roller 21 and the feed roller 22 during conveyance of the recording paper sheet P and even the load on the recording paper sheet P can be reduced.
If, in the absence of the guide roller 41, the pick-up roller 21 is pressed against the leading end portion of the recording paper sheet P, the recording paper sheet P inclines downward and comes into direct contact with the distal end of the guide plate 14 of the multi-purpose tray 12. In this case, during pullout of the recording paper sheet P on the multi-purpose tray 12 by the pick-up roller 21, the recording paper sheet P comes into direct contact with the distal end of the guide plate 14, which interferes smooth conveyance of the recording paper sheet P on the multi-purpose tray 12, smooth pullout of the recording paper sheet P by the pick-up roller 21, and smooth conveyance of the recording paper sheet P by the feed roller 22, thus increases the load on the pick-up roller 21 and the feed roller 22 and even the load on the recording paper sheet P, and makes the feed and conveyance of the recording paper sheet P unstable.
When no recording paper sheet P is placed on the multi-purpose tray 12, the pick-up roller 21 becomes opposed to the leading end of an uppermost one of recording paper sheets P on the tray 24 of the sheet supply cassette 11. When, in this state, the support portion 31 is rotated counterclockwise about the shaft 22A as shown in
Next, a description will be given of a drive system and a control system of the sheet feeder 10.
The first one-way clutch 51 transmits forward rotation of the output shaft of the conveyance motor 50 to a first gear unit 53 and, in response, the first gear unit 53 rotates the conveyance rollers 16 counterclockwise in
The second one-way clutch 52 transmits backward rotation of the output shaft of the conveyance motor 50 to a second gear unit 54 and, in response, the second gear unit 54 rotates the pick-up roller 21 and the feed roller 22 counterclockwise in
Therefore, when the output shaft of the conveyance motor 50 is rotating forward, the conveyance rollers 16 are rotating counterclockwise in
Furthermore, as described previously, the support portion 31 supports the shaft 21A of the pick-up roller 21, the shaft 22A of the feed roller 22, and the shaft of the gear 34, is supported rotatably about the shaft 22A of the feed roller 22 by the shaft 22A, and is pivotally moved within a certain range of angles. When, as shown in
The first sheet sensor 61 is provided upstream of the conveyance rollers 16 of the multi-purpose tray 12 in the direction of conveyance of a recording paper sheet P as shown in
The second sheet sensor 62 is provided between the guide roller 41 of the multi-purpose tray 12 and the pick-up roller 21 of the sheet feed device 13 as shown in
In a ready state, the controller 60 stops the conveyance motor 50 to stop the conveyance rollers 16, the pick-up roller 21, and the feed roller 22, and controls the angle of rotation of the cam motor 56 and stops the cam motor 56 with the pick-up roller 21 away from the separating pad 25.
When a recording paper sheet P is introduced into the conveyance path 17 on the multi-purpose tray 12, the leading end of the recording paper sheet P is detected by the first sheet sensor 61. In response to a detection output of the first sheet sensor 61 indicating that the first sheet sensor 61 has detected the leading end of the recording paper sheet P, the controller 60 rotates the conveyance motor 50 forward to rotate the conveyance rollers 16. Therefore, when the leading end of the recording paper sheet P reaches a first one of the conveyance rollers 16, the one conveyance roller 16 conveys the recording paper sheet P. Subsequently, when the leading end of the recording paper sheet P reaches the other conveyance roller 16, the other conveyance roller 16 conveys the recording paper sheet P to the sheet feed device 13.
When the leading end of the recording paper sheet P reaches between the guide roller 41 of the multi-purpose tray 12 and the pick-up roller 21 of the sheet feed device 13, the second sheet sensor 62 detects the leading end of the recording paper sheet P. In response to a detection output of the second sheet sensor 62 indicating that the second sheet sensor 62 has detected the leading end of the recording paper sheet P, the controller 60 rotates the conveyance motor 50 a certain angle of forward rotation from the time of detection of the leading end of the recording paper sheet P by the second sheet sensor 62 and then stops the conveyance motor 50 to stop the conveyance rollers 16. Thus, the leading end of the recording paper sheet P is stopped below the pick-up roller 21 and the pick-up roller 21 becomes opposed to the leading end of the recording paper sheet P conveyed from the multi-purpose tray 12.
Subsequently, the controller 60 rotates the conveyance motor 50 backward to rotate the pick-up roller 21 and the feed roller 22. Concurrently, the controller 60 rotates the cam motor 56 to move the pick-up roller 21 toward the separating pad 25 and press the pick-up roller 21 against the leading end portion of the recording paper sheet P.
The recording paper sheet P is pulled out by the pick-up roller 21 and conveyed through between the feed roller 22 and the retard roller 23 to the conveyance roller 27.
Subsequently, the second sheet sensor 62 detects the trailing end of the recording paper sheet P. In response to a detection output of the second sheet sensor 62 indicating that the second sheet sensor 62 has detected the trailing end of the recording paper sheet P, the controller 60 rotates the conveyance motor 50 backward for a certain period of time from the time of detection of the trailing end of the recording paper sheet P by the second sheet sensor 62, then stops the conveyance motor 50 to stop the conveyance rollers 16, the pick-up roller 21, and the feed roller 22, controls the angle of rotation of the cam motor 56 to move the pick-up roller 21 away from the separating pad 25, and stops the cam motor 56 to return to the ready state.
As thus far described, in this embodiment, the guide roller 41 is provided at the distal end of the multi-purpose tray 12 and supported elastically and movably in upward and downward directions by the spring member 42. In pulling out a recording paper sheet P on the multi-purpose tray 12 by the pick-up roller 21, the guide roller 41 is pushed down and back against the biasing forces of the arms 42A of the spring member 42 by the recording paper sheet P and the recording paper sheet P slides on the upper side of the peripheral surface of the guide roller 41 to rotate the guide roller 41. Thus, the conveyance of the recording paper sheet P on the multi-purpose tray 12, the pullout of the recording paper sheet P by the pick-up roller 21, and the conveyance of the recording paper sheet P by the feed roller 22 can be smoothly performed and the load on the recording paper sheet P and the load on the pick-up roller 21 and the feed roller 22 can be reduced.
Since, in the sheet conveying device disclosed in BACKGROUND, the manual feed unit is mounted over the sheet supply cassette, a large level difference is present between the manual feed conveyance path and the cassette conveyance path at the point of merge between them, a sheet is conveyed from the manual feed unit to the sheet feed unit while being largely bent and the sheet comes into hard contact with a guide located at the distal end of the manual feed unit, which invites a problem in that the load of sheet conveyance by the sheet feed unit increases and the feed and conveyance of the sheet become unstable.
Unlike the conventional sheet conveying device, in the above embodiment, in pulling out a sheet from the multi-purpose tray and conveying it, the load of conveyance of the sheet can be reduced as described above.
Although in the above embodiment the printer is taken as an example of the image forming apparatus according to the present disclosure, it is merely illustrative and the image forming apparatus according to the present disclosure may be a multifunction peripheral, a copier, a facsimile machine or other types of image forming apparatuses.
The structure of the above embodiment described with reference to
While the present disclosure has been described in detail with reference to the embodiments thereof, it would be apparent to those skilled in the art that the various changes and modifications may be made therein within the scope defined by the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2023-101179 | Jun 2023 | JP | national |
