Patent Application
20130049288
1. Field of the Invention
The present invention relates to a sheet feeding apparatus and an image forming apparatus, and more particularly, to a sheet feeding apparatus separating sheets one by one and feeding the sheets, and an image forming apparatus including the sheet feeding apparatus.
2. Description of the Related Art
Recently, in an image forming apparatus, a roller main body of a sheet feeding apparatus feeding a sheet is desired to have a configuration allowing a user and the like to easily replace the roller main body, and various types of the image forming apparatus including a replaceable roller main body are being provided (See U.S. Pat. No. 6,300,970 and Japanese Patent Laid-Open No. 2002-104675).
Here, a replaceable feeding roller of an image forming apparatus in the related art will be described with reference to
When the roller main body 100 is fitted in the roller holder 103 having the above-described configuration, the roller main body 100 is moved in a direction of an arrow S2 illustrated in
On the other hand, when the roller main body 100 mounted in the roller holder 103 is detached, the snap-fit between the ribs 101b and 101b and the holes 103b and 103b is released by causing the snap-fit portions 103d and 103d of the roller holder 103 to fall outward. Then, after the roller main body 100 is rotated on the boss 101a in a direction of an arrow R1 illustrated in
Incidentally, in the related art, when the roller main body 100 is rotated in the direction of the arrow R2 to attach the roller main body 100 to the roller holder 103, the roller main body 100 needs to be rotated while being pressed so as to prevent the boss 101a from deviating from the recesses 103a and 103a. In particular, when the roller main body 100 is rotatably held in a predetermined range, the roller holder 103 needs to be pressed with one hand, and the roller main body 100 needs to be mounted in the roller holder 103 with the other hand. As described above, workability has been poor when replacing a roller in a conventional roller configuration, which corresponds to an issue.
Accordingly, the invention is intended to provide a sheet feeding apparatus in which replacement of a feeding roller is simplified with a simple configuration, and an image forming apparatus including the sheet feeding apparatus.
According to the present invention, there is provided a sheet feeding apparatus including a feeding roller that presses a sheet corresponding to an uppermost surface of sheets stacked on a sheet stacking portion and discharges the sheet, wherein the feeding roller includes a roller main body including a roller core having a segment of a circle as a cross-sectional surface orthogonal to an axial direction, and an elastic member wound around a roller surface of the roller core, and a roller holder that supports the roller main body from both sides in the axial direction so that the elastic member of the roller main body protrudes to an outer circumstance. The roller main body includes a shaft portion protruding from each of both side surfaces of an end portion of the roller core, and a locking portion formed on each of the both side surfaces of the roller core. The roller holder includes a supporting portion that detachably and rotatably supports the shaft portion, and a locked portion that fixes the roller main body to the roller holder by locking the locking portion of the roller main body that rotates using the shaft portion mounted on the supporting portion as a rotation fulcrum. The supporting portion includes a rotation sliding contact portion that rotatably slides the shaft portion, and a guiding path portion that guides the shaft portion to the rotation sliding contact portion, and the guiding path portion is formed to have a width smaller than a maximum diameter of the shaft portion.
According to the invention, by attaching a roller main body to a roller holder in a state in which deviation is prevented, and then rotating a feeding roller to fix the feeding roller to the roller holder, it is possible to easily replace the roller main body without degrading the quality of the replacement of the roller main body.
Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
Hereinafter, an image forming apparatus including a sheet feeding portion as a sheet feeding apparatus according to an embodiment of the invention will be described with reference to the drawings. The image forming apparatus according to an embodiment of the invention is an electrophotographic image forming apparatus including a sheet feeding portion that feeds sheets while separating the sheets one by one such as a copying machine, a printer, a facsimile, a multifunction peripheral (MFP) thereof, and the like. In the following embodiments, a laser beam printer 1 will be described later as an example of the electrophotographic image forming apparatus.
A laser beam printer 1 according to a first embodiment of the invention will be described with reference to
As illustrated in
The sheet feeding portion 71 includes a sheet tray 2 as a sheet stacking portion that stacks the sheets S, a feeding roller 70 that feeds the sheets S, and a separation pad 4 that separates the sheets S one by one. As illustrated in
The cam 10 is in sliding contact with a cam follower 8a provided on an elevating plate 8 that lifts and lowers the sheet tray 2, and is configured to rotate in response to the feeding roller 70 (feeding shaft 24) rotating by a driving force transmitted from a drive motor 75. When the cam 10 rotates, the elevating plate 8 urged in an upward direction by the feeding spring 9 is lifted and thus, an uppermost surface of the sheets S on the sheet tray 2 is pressed by the roller main body 3 via a cam follower 8a, and the sheets S are discharged while being separated one by one by the separation pad 4. The sheets S discharged by the roller main body 3 are conveyed, by a pair of conveying rollers 5, to the transfer portion 73 configured by a nip between a photosensitive drum 6 and a transfer roller 7 described later. Here, the feeding roller 70 will be described in detail.
An image starts to be formed by the image forming portion 72 concurrently with the feeding of the sheets S. The image forming portion 72 includes a laser scanner 11 and a process cartridge 12, the laser scanner 11 draws an electrostatic latent image on the photosensitive drum 6 inside the process cartridge 12, and the electrostatic latent image is visualized through a toner development using a developing device inside the process cartridge 12. The visualized toner image is transferred as a non-fixed image on the sheets S conveyed to the transfer portion 73 by the pair of conveying rollers 5. The sheet S on which the non-fixed image is transferred is sent to a fixing device 13 of the fixing portion 74 to fix the non-fixed image, and the non-fixed image is thermally fixed on the sheets S. The sheets S on which the thermal fixation of the non-fixed image is completed are sent to a pair of discharge rollers 14, and discharged to a discharge tray 15. Thus, the image forming process using the laser beam printer 1 is completed.
Subsequently, the feeding roller 70 according to the first embodiment will be described with reference to
As illustrated in
The roller main body 3 has a substantially semilunar shape including an arc portion and a circle-segment portion as a whole, and as illustrated in FIG. 4A, is attached to the roller holders 23 and 23 so that the arc portion protrudes from an outer circumference of the roller holders 23 and 23. The roller main body 3 rotates in a direction of an arrow A1 illustrated in
The roller main body 3 includes a roller core 21 in which a cross-sectional surface perpendicular to an axial direction is an arc shape, and a rubber member 22 as an elastic member having an endless shape that is wound around a roller surface (circumference surface) of the roller core 21. The roller core 21 includes bosses 21a and 21a as a shaft portion, ribs 21b and 21b as a locking portion, and ribs 21c and 21c as a locking portion on each of the both side surfaces perpendicular to the roller surface. The bosses 21a and 21a protrude to an end portion (hereinafter, referred to as a leading end portion) that comes into contact with the sheets S when the roller main body 3 initially rotates in the direction of the arrow A1. According to the first embodiment, the bosses 21a and 21a include arc portions 21d and 21d, and linear portions 21e and 21e as a chamfered portion chamfered so that a diameter in a direction perpendicular to an axial direction is smaller than a width of a guiding path portion described later, and are formed in a cylindrical shape having a substantially oval shape as a cross-sectional surface.
The ribs 21c and 21c are provided at another end portion (hereinafter, referred to as a feeding rear end portion) that comes in contact with the sheets S when the roller main body 3 initially rotates in the direction of the arrow A1. The ribs 21c and 21c are formed so that the roller main body 3 rotated in a direction of an arrow B2 illustrated in
The rubber member 22 is wound around the roller core 21 so as to cover the roller surface of the roller core 21, and a portion positioned at the arc portion of the roller main body 3 comes in contact with the sheets S to discharge the sheets S. Further, when the roller main body 3 is mounted on the roller holders 23 and 23, the rubber member 22 positioned at the circle-segment portion is elastically deformed by coming into contact with the feeding shaft 24, thereby urging the roller main body 3 in a direction of an arrow B1 of
As illustrated in
The groove portions 23a and 23a are formed so as to detachably and rotatably support the bosses 21a and 21a. The groove portions 23a and 23a include rotation sliding contact portions 23f and 23f that rotatably slide the bosses 21a and 21a, and guiding path portions 23e and 23e that may guide the bosses 21a and 21a to the rotation sliding contact portions 23f and 23f. The rotation sliding contact portions 23f and 23f are formed in an arc shape, and formed to have a diameter equal to or greater than a diameter (maximum diameter) of the arc portions 21d and 21d of the bosses 21a and 21a. The guiding path portions 23e and 23e are formed as a linear groove having a width smaller than the diameter of the arc portions 21d and 21d, and formed to be equal to or greater than a width (length in a radial direction) between the linear portions 21e of the bosses 21a and 21a.
The recesses 23c and 23c are formed to have a recess shape that may lock the ribs 21c and 21c. The snap-fit portion 23d is formed to be elastically deformable in a direction of arrows D1 and D2 illustrated in
Subsequently, a method of attaching and detaching the roller main body 3 to and from the roller holder 23 according to the first embodiment will be described with reference to
First, a case of attaching the roller main body 3 to the roller holder 23 will be described. When the roller main body 3 is attached to the roller holder 23, positioning is first performed such that the linear portions 21e and 21e of the bosses 21a and 21a of the roller core 21 are substantially parallel to the guiding path portions 23e and 23e of the groove portions 23a and 23a as illustrated in
As illustrated in
When the roller main body 3 is further rotated in the direction of the arrow B2, the snap-fit portions 23d and 23d are respectively pushed out in the directions of the arrows D1 and D2 illustrated in
As described above, locating in a vertical direction during an attachment of the roller main body 3 to the roller holder 23 is performed by fitting the bosses 21a and 21a in the groove portions 23a and 23a, engaging the ribs 21b and 21b with the rectangle holes 23b and 23b, and locking the ribs 21c and 21c in the recesses 23c and 23c. Further, locating in a horizontal direction during an attachment of the roller main body 3 to the roller holder 23 is performed by fitting the bosses 21a and 21a in the groove portions 23a and 23a, and locking the ribs 21c and 21c in the recesses 23c and 23c.
Subsequently, a case of detaching the roller main body 3 from the roller holder 23 will be described. When the roller main body 3 is detached from the roller holder 23, the snap-fit portions 23d and 23d are first respectively pushed out in the directions of the arrows D1 and D2 illustrated in
As described above, the feeding roller 70 of the laser beam printer 1 according to the first embodiment employs a configuration in which the bosses 21a and 21a are enabled to be temporarily joined to the groove portions 23a and 23a so as to be rotatable while the bosses 21a and 21a are prevented from detaching. In particular, by rotating the roller main body 3 after inserting the bosses 21a and 21a into the rotation sliding contact portions 23f and 23f through the guiding path portions 23e and 23e, the roller main body 3 is prevented from deviating from the groove portions 23a and 23a. Thus, when the roller main body 3 is mounted, the roller main body 3 may be temporarily joined to the roller holder 23 concurrently with the locating of the roller main body 3. As such, for example, since the bosses 21a and 21a do not deviate from the groove portions 23a and 23a when the roller main body 3 is rotated in the direction of the arrow B1 or the arrow B2, the roller main body 3 may not be pressed while being rotated. As a result, the roller main body 3 is prevented from deviating during an operation and thus, the roller main body 3 may be easily mounted in the roller holder 23. Accordingly, replacement of the roller main body 3 is simplified.
Subsequently, a laser beam printer 1A according to a second embodiment of the invention will be described with reference to
Referring to
Here, when a feeding is initiated, a reactive force P due to a contact with sheets S is applied to a leading end portion 30a of the roller main body 30 in a direction α illustrated in
First, as illustrated in
Here, in the first embodiment, a guiding direction of the guiding path portions 23e and 23e corresponding to an opening direction of the groove portion 23a provided in the roller holder 23 is formed to be substantially parallel to a vertical direction orthogonal to a horizontal axis illustrated in
In the second embodiment, the angle α is set to about 88 degrees with respect to the horizontal axis illustrated in
In this instance, a method of attaching and detaching the roller main body 30 to and from the roller holder 33 according to the second embodiment is similar to the first embodiment, and description thereof will not be made.
As described above, in the feeding roller 70A of the laser beam printer 1A according to the second embodiment, a guiding direction of the guiding path portions 33e and 33e of the roller holder 33 is formed to be inclined by a predetermined angle (α−β) with respect to the direction α in which the reactive force P from the sheets S is applied. Thus, reinforcement and the like may not be performed for the reactive force P from the sheets S due to a contact with the sheets S, and the roller main body 3 may be prevented from easily deviating from roller holder 33.
Subsequently, a laser beam printer 1B according to a third embodiment of the invention will be described with reference to
As illustrated in
Here, the roller holder 43 includes recesses 43g and 43h for forming an idling section Ar of an angle θ in a rotating direction, and the recesses 43g and 43h are formed to correspond to (control an operation of) the projections 51a and 51b of the serration members 51 and 51. That is, the roller holder 43 is rotatably formed in the idling section Ar formed by the recesses 43g and 43h and the projections 51a and 51b.
As illustrated in
As illustrated in
On the other hand, in a case in which the angle β is set to be less than the angle γ, when the bosses 41a and 41a are inserted into the groove portions 43a and 43a, the roller holder 43 rotates in a direction of an arrow A2 in the idling section Ar. Thus, the bosses 41a and 41a are difficult to be inserted in the groove portions 43a and 43a, and the replacement of the roller main body 40 may be complicated.
Considering the above description, the angle β needs to be set to satisfy an inequality β≧γ. Further, as in the second embodiment, considering a reactive force P applied to the roller main body 40, the angle β needs to be set to satisfy an inequality γ≦β<α. In this instance, in order to prevent the groove portions 43a and 43a from deforming, reinforcement of the roller holder 43 may be enhanced. However, since an extra cost and space for the reinforcement is needed, it is preferable to set the angle β based on the consideration.
By setting the angle β to satisfy the inequality γ≦β<α, the roller holder 43 is prevented from rotating in the idling section Ar, the groove portions 43a and 43a are prevented from being deformed by the reactive force P applied to the roller main body 40 from the sheets S, and the roller main body 40 is prevented from wobbling and deviating.
Subsequently, a laser beam printer 1C according to a fourth embodiment will be described with reference to
As illustrated in
The roller holders 63 and 63 include groove portions 63a and 63a, recesses 63c and 63c, and snap-fit portions 63d and 63d. The groove portions 63a and 63a include rotation sliding contact portions 63f and 63f that rotatably sliding the bosses 61a and 61a, and guiding path portions 63e and 63e that guide the bosses 61a and 61a to rotation sliding contact portions 63f and 63f. The rotation sliding contact portions 63f and 63f are formed in an arc shape, and formed to have a diameter substantially equal to a diameter of the bosses 61a and 61a so that the bosses 61a and 61a may be rotated. The guiding path portions 63e and 63e are formed to have a width smaller than the diameter of the bosses 61a and 61a, and formed to be elastically deformable so as to spread more than the diameter of the bosses 61a and 61a.
As described above, in the feeding roller 70C of the laser beam printer 1C according to the fourth embodiment, by forming the guiding path portions 63e and 63e to be elastically deformable, the bosses 61a and 61a may be mounted in rotation sliding contact portions 63f and 63f by press fitting. Thus, the bosses 61a and 61a may be easily mounted in the rotation sliding contact portions 63f and 63f. As a result, the roller main body 60 is prevented from deviating during an operation, and the roller main body 60 may be easily mounted on the roller holder 63 and 63. In other words, replacement of the roller main body 60 may be simplified.
Hereinabove, embodiments of the invention have been described. However, the invention is not limited to the above-described embodiments. Further, effects disclosed in the embodiments of the invention are merely given as most excellent effects obtained from the invention, and effects of the invention are not limited to the effects disclosed in the embodiments of the invention.
For example, the embodiments have been described using the laser beam printer 1 as an example of an electrophotographic image forming apparatus, and the invention is not limited thereto. A sheet feeding apparatus according to the invention may be used for an image forming apparatus employing an ink-jet method, a thermal transfer method, and the like.
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 modifications, equivalent structures and functions.
This application claims the benefit of Japanese Patent Application No. 2011-180629, filed Aug. 22, 2011, which is hereby incorporated by reference herein in its entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2011-180629 | Aug 2011 | JP | national |
