Patent Grant
8973918
1. Field of the Invention
The present invention relates to a sheet conveying apparatus and an image forming apparatus, and more particularly, to the structure of a skew feeding correcting portion configured to correct skew feeding of a sheet.
2. Description of the Related Art
According to the related art, an image forming apparatus such as a copying machine, a printer, and a facsimile machine includes an image forming portion, and a sheet conveying apparatus configured to convey a sheet to the image forming portion by a conveyance roller. In the image forming apparatus according to the related art, due to deformation of the conveyance roller, misalignment of the conveyance roller, and the like, the sheet may sometimes be skewed when the sheet is conveyed. In the image forming apparatus, the position of the sheet with respect to the image forming portion significantly affects accuracy of an image forming position with respect to the sheet, and hence accurate alignment of the position of the sheet with respect to the image forming portion is an important factor to secure image quality.
In view of the above, in the image forming apparatus according to the related art, a skew feeding correcting portion is provided to the sheet conveying apparatus, and this skew feeding correcting portion corrects the skew feeding of the sheet, to thereby enhance the accuracy of the image forming position. As the skew feeding correcting portion described above, for example, there is known a skew feeding correcting portion including a shutter biased by a spring or the like in a direction opposite to a sheet conveying direction so as to bring a leading edge of the sheet into abutment against the shutter (Japanese Patent Application Laid-Open No. H09-183539 and International Patent WO2011/048668A). In the shutter-type skew feeding correcting portion described above, the leading edge of the sheet is brought into abutment against an abutment portion of a shutter member positioned perpendicularly to the sheet conveying direction, and the leading edge of the sheet is aligned with the abutment portion, to thereby correct the skew feeding of the sheet.
By the way, in recent years, there has been a users' demand to enhance productivity of the image forming apparatus and reduce operation sound. However, in the case where the skew feeding is corrected by bringing the sheet into abutment against the shutter member as in the sheet conveying apparatus according to the related art, when the leading edge of the conveyed sheet is brought into abutment against the shutter member, collision sound is generated. The collision sound becomes louder when the sheet conveying speed increases to enhance the productivity.
The present invention has been made in view of the above-mentioned circumstances, and it is therefore an object thereof to provide a sheet conveying apparatus and an image forming apparatus, which is configured to reduce collision sound to be generated due to abutment between a sheet and a shutter member.
According to one embodiment of the present invention, a sheet conveying apparatus configured to convey a sheet, comprises:
a skew feeding correcting portion configured to correct skew feeding of a sheet,
the skew feeding correcting portion including:
a rotary member pair configured to convey the sheet;
a shutter member configured to abut against a leading edge of a sheet being conveyed, and having a home position; and
a moving member arranged with a gap formed between the moving member and the shutter member positioned in the home position, such that the shutter member is moveable independently from the home position up to a point of engagement with the moving member, when the gap is closed, and such that the moving member is movable integrally with the shutter member while the gap is closed,
wherein the rotary member pair is arranged to nip a sheet during a period in which the shutter member is configured to move integrally with the moving member.
Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
Now, exemplary embodiments of the present invention will be described in detail with reference to the attached drawings.
The image forming portion 600B includes process cartridges 8 (8Y, 8M, 8C, and 8K) removably mounted to the printer main body 600A, and is configured to form toner images of four colors, specifically, yellow, magenta, cyan, and black, respectively. In this case, the process cartridges 8 include photosensitive drums 1 (1Y, 1M, 1C, and 1K) serving as image bearing members, charging rollers (2Y, 2M, 2C, and 2K), and developing rollers 3 (3Y, 3M, 3C, and 3K), respectively. Further, the image forming portion 600B includes a scanner unit 4 arranged below the process cartridges 8 in a vertical direction, and configured to radiate laser beams based on image information to form electrostatic latent images on the respective photosensitive drums 1.
Further, in
Further, the primary transfer rollers 7 are arranged to be opposed to the respective photosensitive drums 1 to form primary transfer portions T1 (T1Y, T1M, T1C, and T1K), and a bias applying unit (not shown) applies a transfer bias to the primary transfer rollers 7. Then, the primary transfer rollers 7 apply a primary transfer bias to the intermediate transfer belt 601, and hence the toner images of the respective colors on the photosensitive drums are sequentially transferred onto the intermediate transfer belt 601. In this manner, full-color images are formed on the intermediate transfer belt 601. Further, the secondary transfer opposing roller 602T and a secondary transfer roller 602 form a secondary transfer portion T2 configured to transfer, onto the sheets, the full-color images sequentially formed on the intermediate transfer belt 601.
The sheet feeding portion 600C includes a sheet feeding cassette 9 removably mounted to the printer main body 600A, a pickup roller 10 configured to feed sheets S contained in the sheet feeding cassette 9. The sheet conveying apparatus 100 includes a sheet separating portion 13 configured to separate the sheets S fed by the pickup roller 10 into each single sheet S, and a skew feeding correcting portion 12 configured to correct a leading edge of the sheet S passing through the sheet separating portion to become in parallel to a leading edge of an image region including the toner image on the intermediate transfer belt 601. Note that, after correcting the skew feeding of the sheet S, the skew feeding correcting portion 12 guides the sheet S into the secondary transfer portion T2 in synchronization with a timing when the toner images on the intermediate transfer belt 601 arrive at the secondary transfer portion T2.
Note that, in
Next, an image forming operation of the color laser printer 600 having the above-mentioned structure will be described. When image signals are input from a personal computer (not shown) or the like to the scanner unit 4, the scanner unit 4 irradiates the photosensitive drums 1 with laser beams corresponding to the respective image signals. At this time, the surfaces of the photosensitive drums 1 are uniformly charged at predetermined polarity and potential by the charging rollers 2 in advance, and electrostatic latent images are formed on the surfaces through the irradiation of the laser beams from the scanner unit 4. After that, those electrostatic latent images are developed and visualized by the developing rollers 3.
In this color laser printer 600, the scanner unit 4 first irradiates the photosensitive drum 1Y with a laser beam corresponding to an image signal of a yellow component of an original, to thereby form an electrostatic latent image for yellow on the photosensitive drum 1Y. Then, the developing roller 3Y develops the electrostatic latent image for yellow with yellow toner, to thereby visualize the electrostatic latent image as a yellow toner image. After that, along with rotation of the photosensitive drum 1Y, the yellow toner image arrives at the primary transfer portion T1Y formed through abutment between the photosensitive drum 1Y and the intermediate transfer belt 601, and then the yellow toner image on the photosensitive drum 1Y is transferred onto the intermediate transfer belt 601 due to the primary transfer bias applied to the primary transfer roller 7Y.
When a part of the intermediate transfer belt 601 which bears the yellow toner image then moves, a magenta toner image formed on the photosensitive drum 1M by a method similar to the above-mentioned method by the time of movement of the intermediate transfer belt 601 is transferred onto the intermediate transfer belt 601 while being superimposed on the yellow toner image. Similarly, along with the movement of the intermediate transfer belt 601, a cyan toner image and a black toner image are transferred at the respective primary transfer portions T1C and T1K while being superimposed on the yellow toner image and the magenta toner image. In this manner, full-color toner images are formed on the intermediate transfer belt 601.
Further, in parallel with the toner image forming operation, the sheets S contained in the sheet feeding cassette 9 are fed by the pickup roller 10, and then separated by the sheet separating portion 13 serving as a sheet conveying unit into each single sheet S to be conveyed. After that, the sheet S is conveyed to the skew feeding correcting portion 12, and the skew feeding is corrected by the skew feeding correcting portion 12. Then, the sheet S is conveyed to the secondary transfer portion T2 by the skew feeding correcting portion 12 so that the position of the full-color toner images on the intermediate transfer belt 601 is aligned with the position of the sheet S at the secondary transfer portion T2. Then, at the secondary transfer portion T2, a bias of a positive polarity is applied to the secondary transfer roller 602, and hence the four-color toner images on the intermediate transfer belt 601 are secondarily transferred onto the conveyed sheet S. Note that, after the toner images are secondarily transferred onto the sheet S, the toner remaining on the intermediate transfer belt 601 is removed by a transfer belt cleaning device 603, and the removed toner is collected into a waste toner collecting container (not shown).
After the toner images are transferred onto the sheet S, the sheet S is conveyed to the fixing portion 604, and is heated and pressurized by the heating roller 604a and the pressure roller 604b so that the full-color toner images are fixed onto the surface of the sheet S as a permanent image. After the full-color toner images are fixed as a permanent image as described above, in a case of forming an image on one side of the sheet S, the sheet S is then delivered by a sheet delivering portion 600E and stacked onto a sheet stacking portion 600F. In a case of forming images on both sides of the sheet S, on the other hand, the sheet S is conveyed by a duplex conveying portion 600G again to the image forming portion 600B, and after the images are formed on both sides of the sheet S, the sheet S is delivered and stacked onto the sheet stacking portion 600F.
Note that, in the embodiment, the conveying rotatable members 102 (102a to 102e) are rotatably supported by bearing portions (not shown) which are supported to be movable along a direction of the registration roller 101 with respect to a conveyance frame 201 serving as a main body of the sheet conveying apparatus 100. Further, the bearing portions (not shown) are biased toward the registration roller 101 by rotatable member pressing units 501 and rotatable member pressing springs 502 illustrated in
Note that, in
Note that, in
Note that, as illustrated in
As illustrated in
In general, in the color laser printer 600, as illustrated in
Next, a skew feeding correcting operation of the skew feeding correcting portion 12 having the above-mentioned structure will be described. First, as illustrated in
Subsequently, as illustrated in
When the shutter member 301A is rotated, the retaining surface 301a is moved to the position indicated by 301a′. At this time, the position of the retaining surface 301a is positioned on the upstream side of the nip portion N of the registration roller pair 101, 102 in the sheet conveying direction. When the rotation of the shutter member 301A is stopped by the regulating member 401, the sheet S receives a reaction force caused by a force for holding the shutter cam 303 biased by the shutter spring 305. The biasing force of the shutter spring 305 is set so that the whole shutter members 301 are not rotatable at the time when one shutter member 301A is pushed by the sheet S as described above.
Subsequently, when the sheet separating portion further conveys the sheet S to achieve a state illustrated in
The loop of the sheet S is larger on an Sr side in
When the sheet S is then aligned with the shutter members 301A to 301D, a force for rotating the shutter members 301A to 301D and the shutter cam 303 about the shutter shaft 302 in a direction indicated by the arrow z2 in
After the sheet S enters the nip portion N of the registration roller pair 101, 102 while rotating the shutter members 301A to 301D, the sheet S is nipped and conveyed by the registration roller pair 101, 102 which starts rotating at a predetermined timing. Note that, when the shutter members 301 are pushed by the sheet S and the shutter shaft 302 is rotated integrally with the shutter members 301, the shutter cam 303 is also rotated as illustrated in
Also, when forming the loop of the sheet S, it is desired to form a larger loop inside a sheet conveyance path which is formed by the conveyance frame 201 and a conveyance guide 202, to thereby enhance the skew feeding correcting performance. Therefore, as illustrated in
Subsequently, as illustrated in
However, at this time, peripheral surfaces 311b serving as abutment surfaces of the shutter members 301 are brought into contact with the sheet S that is being conveyed. In this case, the sheet S has higher stiffness through the loop formation, and when the peripheral surfaces 311b are brought into contact with the sheet S thus having higher stiffness, the shutter members 301 are stopped without rotating. Note that, even in the state in which the shutter members 301 are not rotated, as illustrated in
Thus, only the shutter cam 303 and the shutter shaft 302 are rotated by an amount corresponding to the gap angle α in a direction indicated by the arrow z5 in
Subsequently, the sheet S is further conveyed and a trailing edge of the sheet S passes through the sheet separating portion 13. Then, the stiffness of the sheet S becomes lower. When the stiffness of the sheet S becomes lower, the shutter members 301 are gradually rotated in a direction indicated by the arrow z6 in
When the trailing edge of the sheet S is completely separated from the shutter members 301, as illustrated in
Note that,
As described above, in the embodiment, when the leading edge of the sheet S is brought into contact with the retaining surface 301a, only the shutter member 301 is rotated by an amount corresponding to the gap angle α while canceling the gap “g”. Through the rotation of only the shutter member 301 described above, it is possible to absorb or reduce a shock received by the skew feeding correcting portion 12 through an intermediation of the shutter member 301. Thus, it is possible to reduce collision sound that is generated when the sheet S is brought into contact with the shutter member 301. That is, as in the embodiment, the regulating member 401 is arranged with the gap “g” formed between the regulating member 401 and the shutter member 301, and the shutter member 301 is brought into abutment against the regulating member 401 during a period in which the shutter member 301 is moved from the abutment position. Thus, it is possible to reduce the collision sound which is generated due to the abutment between the sheet S and the shutter member 301.
Further, in the embodiment, after the shutter member 301 is moved to the passage position, the peripheral surface 311b of the shutter member 301 is brought into contact with the sheet S, and then the shutter member 301 is stopped, but the shutter cam 303 and the shutter shaft 302 are rotated by an amount corresponding to the gap angle α. When the shutter member 301 is returned to the home position through the rotational operation of the shutter cam 303 and the shutter shaft 302, the gap angle α is secured constantly. Thus, it is possible to keep the state in which, even when a succeeding sheet S is subsequently conveyed and brought into abutment against the shutter member 301, the collision sound generated due to the abutment between the sheet S and the skew feeding correcting portion 12 is reduced constantly.
Further, in the embodiment, as described above, a larger loop is formed inside the sheet conveyance path R that is formed by the conveyance frame 201 and the conveyance guide 202, to thereby increase the stiffness of the sheet S. Thus, even in a case of conveying a sheet having low rigidity, such as a sheet having a basis weight of 60 g/m2 or less, it is possible to suppress deformation of the leading edge of the sheet when the sheet collides against the shutter member 301, and to enhance the sheet skew feeding correcting performance as well.
The above description is directed to the case where the regulating member 401 is provided on the shutter shaft 302 and the gap “g” is formed between the shutter member 301 and the regulating member 401 so that the shutter member 301 is rotatable by an amount corresponding to the gap angle α, but the present invention is not limited thereto. For example, as illustrated in
Further, as illustrated in
Next, a second embodiment of the present invention will be described.
In
Further, shutter members 171 (171A, 171B, 171C, and 171D) are fixed at the same phase to a shutter holding member 172. A shutter portion in this embodiment is constructed of the shutter members 171A, 171B, 171C, and 171D and the shutter holding member 172. The shutter holding member 172 is pivotably supported by the roller shaft 101f of the registration roller 101 through an intermediation of a pivotal movement regulating member 173 and a roller bearing 174 serving as the moving members.
The shutter holding member 172 includes a regulating portion 172a. As illustrated in
Further, during a period other than the period in which the sheet S is conveyed, the position of the shutter holding member 172 is kept by the pivotal movement regulating member 173 in such a posture that a retaining surface 171a of the shutter member 171 is positioned on the upstream side of the nip portion N of the registration roller pair 101, 102 in the sheet conveying direction. Note that, the pivotal movement regulating member 173 is biased in a direction indicated by the arrow z8 by a pivotal spring 177 serving as the biasing unit, and the posture in the home position is regulated by a stopper 181.
Next, a skew feeding correcting operation of the skew feeding correcting portion 12 having the above-mentioned structure will be described. First, as illustrated in
When the leading edge of the sheet S is brought into contact as described above, the shutter member 171A is pushed by the sheet S and pivoted in a direction indicated by the arrow z9 together with the shutter holding member 172. When the shutter holding member 172 is pivoted by an amount corresponding to the gap angle α, the regulating portion 172a abuts against the pivotal movement regulating member 173, and the regulating portion 172a and the pivotal movement regulating member 173 form the gap angle α therebetween on the opposite side to that before the pivotal movement. As a result, the pivotal movement is stopped in such a position that the retaining surface 171a is positioned in a position indicated by 171a′.
At this time, sliding resistance between the roller bearing 174 and the roller shaft 101f caused by the pivotal movement of the shutter holding member 172 is sufficiently smaller as compared to the biasing force of the pivotal spring 177, and hence there is no change in posture of the pivotal movement regulating member 173. Further, the retaining surface 171a′ is positioned on the upstream side of the nip portion N of the registration roller pair 101, 102 in the sheet conveying direction.
When the pivotal movement of the shutter holding member 172 is stopped by the pivotal movement regulating member 173, the sheet S receives a reaction force of the pivotal spring 177. The biasing force of the pivotal spring 177 is set so that the whole shutter members 171 are not rotatable at the time when one shutter member 171A is pushed by the sheet S as described above.
However, after that, the sheet S is further conveyed, and a predetermined loop is formed in the sheet S as described above. Then, the inclination of the leading edge of the sheet S is corrected, and the leading edge of the sheet S pushes up the shutter members 171. Thus, the sheet S enters the nip portion N of the registration roller pair 101, 102, and is conveyed by the registration roller pair 101, 102.
When the shutter members 171 are pushed up, the shutter holding member 172 is pushed up integrally with the shutter members 171, and further, the pivotal movement regulating member 173 is pivoted together with the shutter holding member 172 through an intermediation of the regulating portion 172a of the shutter holding member 172. Thus, during the conveyance of the sheet S, as illustrated in
When the sheet S then passes through the skew feeding correcting portion 12 as illustrated in
As described above, in the embodiment, after the leading edge of the sheet S is brought into contact with the retaining surface 171a, only the shutter holding member 172, that is, the shutter member 171 is pivoted by an amount corresponding to the gap angle α before the skew feeding correcting operation is started. Through the pivotal movement of the shutter holding member 172 described above, it is possible to absorb a shock received by the skew feeding correcting portion 12 through an intermediation of the shutter member 171 from the leading edge of the sheet S conveyed by the sheet separating portion 13. Thus, it is possible to reduce collision sound that is generated when the sheet S is brought into contact with the shutter member 171.
Note that, the above description is directed to the case where the shutter holding member 172 (shutter member 171) is pivoted about a fulcrum corresponding to the roller shaft 101f of the registration roller 101, but the present invention is not limited thereto. The shutter holding member 172 (shutter member 171) may be pivoted about a fulcrum corresponding to the rotatable member shaft 175 of the conveying rotatable member 102. That is, it is only necessary that the shutter holding member 172 (shutter member 171) be provided to be pivotable about any one of the shafts of the registration roller pair 101, 102.
Further, as illustrated in
Still further, as illustrated in
In the embodiment, the moving member movable integrally with the shutter member is arranged with the gap formed between the moving member and the shutter member, and the gap is canceled during a period in which the shutter member is moved from the abutment position to the passage position. Thus, it is possible to reduce the collision sound which is generated due to the abutment between the sheet and the shutter member.
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 and equivalent structures and functions.
This application claims the benefit of Japanese Patent Application No. 2012-283306, filed Dec. 26, 2012, which is hereby incorporated by reference herein in its entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2012-283306 | Dec 2012 | JP | national |
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| Number | Date | Country |
|---|---|---|
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| Entry |
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| Great Britain Search Report issued in counterpart Great Britain Application No. 1322880.4, dated Jul. 21, 2014. |
| Number | Date | Country | |
|---|---|---|---|
| 20140175737 A1 | Jun 2014 | US |
