Patent Application
20210087004
The present invention relates to a sheet feeding apparatus for feeding a sheet and an image forming apparatus with the sheet feeding apparatus.
An image forming apparatus such as a printer having a cassette in which sheets are stacked and can be withdrawn from the main body of the apparatus is generally known. This type of image forming apparatus is equipped with rollers that convey sheets from the cassette. For example, the feeding rollers include a pickup roller that picks up the sheets out of the cassette, a feed roller that separates and feeds the picked-up sheets one by one and a retard roller. These feeding rollers should be regularly replaced, otherwise they cannot be used due to wear caused by the contact with the sheet or other rollers.
Conventionally, a cantilevered feeding roller is used and the cantilevered feeding roller is slid out of the shaft that supports the cantilevered feeding roller (see Japan Patent Application Laid-Open Publication No. 2004-299825) when removing the feeding roller from the main body of the apparatus for replacement. When replacing the feeding roller, a user releases the engagement of a claw portion formed at the side surface portion of the feeding roller from the shaft.
In recent years, the reduction of the diameter of feeding rollers is required due to the need for the downsizing of an image forming apparatus. In the vicinity of the feeding rollers mounted on the main body of the apparatus, a shaft supporting the feeding roller, a frame supporting the shaft, and a conveyance guide for guiding the conveyance of the sheet are provided, and are located in close proximity to the feeding rollers (see Japan Patent Application Laid-Open Publication No. 2004-299825). Furthermore, the position of a claw member in a rotational direction of a feeding roller is not restricted when the feeding roller is replaced.
In such a case, when a user replaces a feeding roller, it may be difficult to release the engagement of the claw member of the feeding roller because of the smaller space for pinching the claw member depending on the rotational position of the claw member of the feeding roller.
Therefore, an object of the present invention is to provide a sheet feeding apparatus that does not impair the workability of changing the feeding rollers.
To accomplish the above object, a sheet feeding apparatus according to the present invention, comprising:
a sheet feeding cassette configured to accommodate a sheet;
a feeding roller configured to feed the sheet stacked on the sheet feeding cassette;
a feeding roller shaft configured to axially support the feeding roller such that the feeding roller is rotatable around the feeding roller shaft;
a feeding guide configured to guide the sheet fed by the feeding roller; and
a feeding frame configured to support the feeding roller shaft and the feeding guide,
wherein the feeding roller includes a core portion configured to rotatably support the feeding roller when the feeding roller is fitted to the feeding roller shaft, and a roller portion provided on an outer periphery of the core portion, the roller portion rotating integrally with the core portion and abutting on the sheet,
wherein the core portion includes an engaging portion configured to engage with the feeding shaft to restrict a movement of the feeding roller in an axial direction when the feeding roller is fitted to the feeding roller shaft,
wherein the feeding roller shaft includes an engaging groove with which the engaging portion engages when the feeding roller is fitted to the feeding roller shaft, and
wherein the core portion includes a protrusion extending in the axial direction at an opposing position to the engaging portion when the feeding roller is viewed from the axial direction of feeding roller shaft when the feeding roller is fitted to the feeding roller shaft.
According to the present invention, the workability of changing the feeding rollers can be improved.
Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, in the following description, the positional relationship of up, down, left, right, and front and back is expressed based on the state of the image forming apparatus viewed from the front side (from a viewpoint of
[Image forming apparatus]
The printer 201 (image forming apparatus) according to the first embodiment is an electrophotographic system full-color laser beam printer. As shown in
The image forming portion 201B is of a four-drum full-color type and is equipped with the laser scanner 210, the four process cartridges 211, and the intermediate transfer unit 201C. These process cartridges form yellow (Y), magenta (M), cyan (C) and black (K) toner images, respectively. Each process cartridge 211 includes the photosensitive drum 212, the charger 213, the developing device 214, the cleaner (not shown), and the like. The toner cartridges 215 containing toners of respective colors are detachably attached to the printer body 201A above the image forming portion 201B. The intermediate transfer unit 201C has the intermediate transfer belt 216 wound around the driving roller 216a, the tension roller 216b, and the like. The intermediate transfer belt 216 is disposed above the four process cartridges 211. The intermediate transfer belt 216 is disposed so as to be in contact with all the photosensitive drums 212 of the process cartridges 211, and is rotationally driven in the counterclockwise direction (direction of the arrow Q) by the drive roller 216a driven by a drive unit (not shown). The intermediate transfer unit 201C is equipped with the primary transfer rollers 219 that abut the inner peripheral surface of the intermediate transfer belt 216 at positions facing the photosensitive drums 212. Nip portions between the intermediate transfer belt 216 and the photosensitive drums 212 are formed as the primary transfer portions T1. Further, the image forming portion 201B is equipped with the secondary transfer roller 217 that abuts on the outer peripheral surface of the intermediate transfer belt 216 at a position facing the drive roller 216a. As a nip portion between the secondary transfer roller 217 and the intermediate transfer belt 216, the secondary transfer portion T2 is formed, where the toner image borne on the intermediate transfer belt 216 is transferred to the sheet P.
In each process cartridges 211 configured as described above, negatively charged toner images of respective colors are formed on the surfaces of the photosensitive drums 212 after the electrostatic latent images are formed on the surfaces of the photosensitive drums 212 by the laser scanners 210 and the toner is supplied from the developing devices 214. These toner images are multiply transferred (primary transfer) to the intermediate transfer belt 216 sequentially at respective primary transfer portions T1 by applying positive transfer bias voltages to the primary transfer rollers 219 to form a full color toner image on the intermediate transfer belt 216. In parallel with this process of forming the toner image, the sheet P fed from the sheet feeding portion 201E is conveyed to the registration roller pair 240 where the skew feeding correction for the sheet P is performed. The registration roller pair 240 conveys the sheet P to the secondary transfer portion T2 at a timing matched with the transfer timing of the full-color toner image formed on the intermediate transfer belt 216. The toner image borne on the intermediate transfer belt 216 is secondarily transferred to the sheet P at the secondary transfer portion T2 by applying a positive transfer bias voltage to the secondary transfer roller 217. The sheet P on which the toner image is transferred is heated and pressurized at the fixing portion 220 so that the color image is fixed to the sheet P. The sheet P to which the image has been fixed is discharged onto the discharge tray 230 by the discharge roller pair 225 and stacked.
When images are formed on both sides of the sheet P, after the sheet P passes through the fixing portion 220, the sheet P is switched back by the reverse roller pair 222 that is capable of rotating in forward and reverse directions and that is provided in the reverse conveying portion 201D. The sheet P is then conveyed again to the image forming portion 201B via the re-conveyance passage R, where the image is formed on the back surface of the sheet.
[Cassette feeding apparatus]
The cassette feeding apparatuses 100A, 100B, 100C and 100D as sheet feeding apparatuses will be described below. These cassette feeding apparatuses 100A, 100B, 100C, 100D have the same configuration, only the uppermost cassette feeding apparatus 100A will be described, and description of the other cassette feeding apparatuses 100B, 100C, 100D will be omitted. As shown in
The feeding unit 2 has feeding rollers for feeding the sheet. The feeding rollers include the pickup roller 4, the feed roller 5, and the retard roller 6, which will be described later. The feeding unit 2 has the pickup roller 4 that picks up a sheet stacked on the cassette 3, and the feed roller 5 that feeds the sheet picked up by the pickup roller 4. Further, the feeding unit 2 includes the retard roller 6, the conveyance guide 8, the downstream conveyance guide 11, and the separating mechanism 30 (see
The roller guide 9 made of a thin plate material such as a stainless-steel plate or a resin sheet is supported by the conveyance guide 8 within the width of the retard roller 6. The roller guide 9 is arranged close to the separation nip N. The sheet P picked up by the pickup roller 4 is guided by the roller guide 9 and the downstream conveyance guide 11 at the upstream and downstream sides of the separation nip N at least within the width of the retard roller 6. Further, the feeding unit 2 has the upper conveyance guide 16 that faces the cassette guide 7 and the downstream conveyance guide 11. The upper conveyance guide 16 is slidably supported by the frame 2A (see
[Retard roller]
As shown in
The pickup roller 4 and the feed roller 5 are also the feeding rollers and configured to be removable like the retard rollers 6. The configurations for removing the pickup roller 4 and the feed roller 5 are the same as those for the retard roller 6 respectively. Therefore, reference numerals are added to the members having equivalent functions in
[Separating mechanism]
As shown in
[Conveyance guide]
Next, the configuration of the conveyance guide 8 will be described in detail with reference to
[Removal of roller]
Next, the procedure for removing the pickup roller 4, the feed roller 5, and the retard roller 6, which are feeding rollers in the case where they are exchanged and maintained will be described. First, as shown in
Due to the limited space around the feeding rollers in the case where the pickup roller 4, the feed roller 5, and the retard roller 6, which are the feeding rollers, are removed, the replacement work may be difficult. This will be described in detail with reference to
Therefore, in the present embodiment, as described above, the ribs 4f, 5f and 6f, which are protrusions for a user to rotate the feeding rollers are provided on the core portions of respective feeding rollers (see
Next, the retard roller 6 is exemplified as the feeding roller and a description will be made with
The retard roller 6, which is a feeding roller, is mounted on the support shaft 6a of the retard roller 6 such that the retard roller 6 can be detached from the support shaft 6a in the direction of arrow A shown in
For example, as shown in
Further, for the operating force by a user for rotating the pickup roller 4 and the feed roller 5 by pinching the engagement releasing portions 4b and 5b, the present embodiment is configured as follows. As shown in
When replacing the feeding rollers, a user fits the rollers to be attached to the support shafts of the respective rollers and push the rollers from the front to the back of the apparatus. This attaching operation will be described next, taking the retard roller 6 as an example. The retard roller 6 should be pushed until the engaging portion 6h of the retarded roller 6 is engaged with the engaging groove 6c of the support shaft 6a. However, when the end surface 6i of the core portion 6A is pushed by a user, the tip of the support shaft 6a sticks out in the front direction from the end surface 6i of the core portion 6A. As a result, the end surface 6i of the core portion 6A cannot be pushed into the engagement groove 6c of the support shaft 6a until the installation is completed, which may cause an incomplete engagement of the engaging portion 6h of the retard roller 6 with the engaging groove 6c of the support shaft 6a. Particularly, when a roller is used, which has a small diameter aiming at space-saving, the above-mentioned engagement failure is likely to occur. If the feeding roller is improperly assembled as described above, the roller may come off during operation of the apparatus and a jam may occur. Therefore, in the present embodiment, as described above, the ribs 4f, 5f and 6f which are the protrusions are provided so as to protrude further in the axial direction from the end surfaces 4i, 5i and 6i of the core portions 4A, 5A and 6A than the tips of the support shafts. In addition, the engagement releasing portion 6b and the grip portion 6g of the core portion 6A are also provided so as to protrude further in the axial direction from the end surface 6i of the core portion 6A than the tip of the support shaft 6a. Therefore, when mounting the retard roller 6, a user can push the retard roller 6 using any of the tip of the rib 6f, the tip of the engagement releasing portion 6b and the tip of the grip portion 6g. This ensures the completion of the engagement of the engaging portion 6h of the retard roller 6 with the engaging groove 6c of the support shaft 6a without being interfered with the tip of the support shaft 6a.
As described above, during replacement of a feeding roller, a user can easily move the engagement releasing portion to a position where the user can easily operate the engagement releasing portion by pinching the rib (protrusion) provided on the opposing side to the engagement releasing portion provided on the core portion of a feeding roller and rotating the feeding roller. Thus, even if the diameter of the feeding roller is reduced, the workability of replacing the feeding roller can be significantly improved.
Also, a one-way clutch is provided between the feeding roller and the shaft. As a result, when the engagement releasing portion is pinched and the feeding roller is rotated, the feeding roller can idle around the shaft by the effect of the one-way clutch. Therefore, the feeding roller can be rotated with a weaker force.
Further, a rib (protrusion) provided on the opposite side to the engagement releasing portion of the core portion further protrudes in the axial direction from the end surface of the core portion than the tip of the shaft. Therefore, when mounting the feeding roller, a user can push the feeding roller by using the above-described tip of the rib. This ensures the completion of the engagement of the engaging portion of the roller with the engaging groove of the support shaft without being interfered with the tip of the support shaft.
The above-mentioned embodiment has one rib as a protrusion provided in the rotational direction of the feed roller. However, the present invention is not limited to this configuration. For example, as shown in
In any of the above configurations, during the replacement of the retarded roller 6, even if the engagement releasing portion 6b or the grip portion 6g is in a phase where it is difficult to pinch the engagement releasing portion 6b or the grip portion 6g with fingers, a user can easily move the engagement releasing portion 6b to a position where the user can easily operate it by pinching the above-described rib 6f and rotating the retard roller 6. As a result, the workability of replacing the retard roller 6 can be improved. Further, when mounting the retard roller 6, the roller can be pushed in until the mounting is completed by using the rib 6f described above. Therefore, the engaging portion of the core portion of the roller can be reliably engaged with the engaging groove of the support shaft. As a result, it is possible to provide a sheet feeding apparatus without mounting failures.
Further, in the above-described embodiment, the printer including the reading apparatus is exemplified as the image forming apparatus, but the present invention is not limited to this configuration. For example, the image forming apparatus can be a single-purpose printer or any other image forming apparatus. The above described image forming apparatus with an intermediate transfer member, transfers toner images of respective colors to the intermediate transfer member in a sequentially superimposed manner, and transfers the toner images borne on the intermediate transfer member to a sheet at one time. However, the present invention is not limited to this configuration. An image forming apparatus can be adopted, which has a sheet supporting member and transfers toner images of respective colors onto the sheet supported on the sheet supporting member in a sequentially superimposed manner. The same effect can be obtained by applying the present invention to the sheet feeding apparatus used in these image forming apparatuses.
Further, in the above-described embodiment, the sheet feeding apparatus integrally provided in the image forming apparatus is exemplified. However, the present invention is not limited to this configuration. A sheet feeding device can be used, which is attachable to and detachable from the image forming apparatus. The same effect can be obtained by applying the present invention to these sheet feeding apparatuses.
While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications, equivalent structures and functions.
This application claims the benefit of Japanese Patent Application No. 2019-171372, filed Sep. 20, 2019, which is hereby incorporated by reference herein in its entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2019-171372 | Sep 2019 | JP | national |
