Patent Grant
11440760
The present invention relates to a sheet conveyance apparatus for conveying sheets and an image forming apparatus equipped with the same.
Generally, an image forming apparatus such as a printer that is equipped with a skew correction unit provided upstream of an image forming position in a sheet conveyance direction to correct skewing of the sheet for improving image quality is known.
Hitherto, a skew correction unit including an engagement member having an abutment surface against which a leading edge of a sheet abuts, and a retention member that retains the engagement member and pivots integrally with the engagement member by the abutment surface being pushed by the sheet is proposed (refer to Japanese Patent Application Laid-Open Publication No. 2013-177244). After the retention member pivots integrally with the engagement member, when a leading edge of the sheet passes the abutment surface, the retention member returns to a standby position and the engagement member pivots relatively with respect to the retention member, and the engagement member slides against a surface of the sheet. Then, after a trailing edge of the sheet passes the engagement member, the engagement member returns to the standby position. As described, by configuring the skew correction unit with two members, an engagement member and a retention member, it becomes possible to reduce the amount of pivoting of the engagement member after the trailing edge of the sheet has passed the engagement member and to improve throughput.
Recently, there are increasing demands for printing labels, related, for example, to printing addresses and names on labels and adhering them on post cards to send direct mails, or to printing names, usage instructions and effects of medicine on labels in pharmacies. Such adhesive label sheets are integrated sheet materials, each composed of a label having an adhesive applied on one side and an adhesive release paper which is attached to an adhesive side of the label, having a drawback in that the adhesive may be exposed at an edge in which the label and the adhesive release paper are attached.
Therefore, in a state where the adhesive label sheet is conveyed to the skew correction unit disclosed in Japanese Patent Application Laid-Open Publication No. 2013-177244, there may be a case where the adhesive of the adhesive label sheet is adhered to an abutment surface of the engagement member. The adhesive adhered to the abutment surface is spread by a subsequent sheet and the like, especially at a portion of the engagement member that slides against the surface of the sheet, and causes the sheet to be adhered to the adhesive spread on the sliding surface portion, which may lead to conveyance failure such as jamming of sheets or damages such as bending of the sheet.
According to a first aspect of the present invention, a sheet conveyance apparatus includes a first conveyance portion configured to convey a sheet, an abutment member including an abutment surface against which a leading edge of the sheet conveyed by the first conveyance portion abuts, the abutment member configured to move from a standby position by the abutment surface being pressed by the sheet, a second conveyance portion configured to nip the sheet during a process in which the abutment member moves from the standby position and to convey the sheet being nipped, an urging member configured to urge the abutment member toward the standby position, and a rotary member supported rotatably on the abutment member, wherein the rotary member is in contact with the sheet being conveyed by the second conveyance portion, and the abutment member is separated from the sheet in a state where the rotary member is in contact with the sheet being conveyed by the second conveyance portion after the leading edge of the sheet being conveyed passes the abutment surface.
According to a second aspect of the present invention, a sheet conveyance apparatus includes a first roller pair configured to convey a sheet, an abutment member including an abutment surface against which a leading edge of the sheet conveyed by the first roller pair abuts, the abutment member configured to move from a standby position by the abutment surface being pressed by the sheet, a second roller pair configured to nip the sheet during a process in which the abutment member moves from the standby position and to convey the sheet being nipped, an urging member configured to urge the abutment member toward the standby position, and a rotary member supported rotatably on the abutment member, wherein the rotary member is in contact with the sheet being conveyed by the second roller pair, and the abutment member is positioned at a position where the abutment member does not intersect with a nip line of the second roller pair in a state where the rotary member is in contact with the sheet being conveyed by the second roller pair after the leading edge of the sheet being conveyed passes the abutment surface.
Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
General Arrangement
At first, a first embodiment of a present invention will be described. A printer 1 serving as an image forming apparatus according to a first embodiment is a laser beam printer adopting an electrophotographic system. The printer 1 includes, as illustrated in
The four process cartridges 20Y, 20M, 20C and 20K adopt a same configuration, except for the difference in the colors of the images being formed. Therefore, the configuration and image forming process of only the process cartridge 20Y will be described, and descriptions of process cartridges 20M, 20C and 20K will be omitted.
The process cartridge 20Y includes a photosensitive drum 2, a charge roller 3, a developing roller 5, and a cleaning blade 6. The photosensitive drum 2 is formed by coating an organic photoconductive layer on an outer circumference of an aluminum cylinder, and the photosensitive drum 2 is rotated by a drive motor not shown. Further, the image forming unit 50 includes an intermediate transfer belt 8 wound around a drive roller 9 and a tension roller 10, and primary transfer rollers 80a, 80b, 80c and 80d are provided on an inner side of the intermediate transfer belt 8. Further, a secondary transfer roller 11 is arranged to oppose to the drive roller 9 with the intermediate transfer belt 8 interposed therebetween, and the intermediate transfer belt 8 together with the secondary transfer roller 11 form a transfer nip N1 where image is transferred to the sheet S being conveyed.
The sheet feed unit 40 is provided at a lower portion of the printer 1, and includes a cassette 13 that supports sheets S, a pickup roller 14 that feeds sheets S supported on the cassette 13, and a separation roller 15. The sheet conveyance apparatus 7 includes a registration roller pair 30. The fixing unit 81 includes a fixing roller and a pressure roller that apply heat and pressure to the sheet.
Next, an image forming operation of the printer 1 configured as above will be described. If an image signal is entered to the scanner unit 4 from a personal computer and the like not shown, a laser beam corresponding to the image signal is irradiated from the scanner unit 4 to the photosensitive drum 2 of the process cartridge 20Y.
In this state, the surface of the photosensitive drum 2 is charged uniformly in advance to a predetermined polarity and potential by the charge roller 3, and by having a laser beam irradiated from the scanner unit 4, an electrostatic latent image is formed on the surface of the photosensitive drum 2. The electrostatic latent image formed on the photosensitive drum 2 is developed by the developing roller 5, and a yellow (Y) toner image is formed on the photosensitive drum 2.
Similarly, a laser beam is irradiated from the scanner unit 4 to the respective photosensitive drums of the process cartridges 20M, 20C and 20K, and toner images of magenta (M), cyan (C) and black (K) are formed on the respective photosensitive drums. Toner images of respective colors formed on the respective photosensitive drums are transferred from the primary transfer rollers 80a, 80b, 80c and 80d to the intermediate transfer belt 8, and the images are transferred to the transfer nip N1 on the intermediate transfer belt 8 rotated by the drive roller 9. The image forming process of each color is performed at such a timing that the toner image is superposed to a primarily transferred toner image formed upstream on the intermediate transfer belt 8. The toner remaining on the photosensitive drum 2 after the toner image has been transferred by the primary transfer roller 80a is collected by the cleaning blade 6.
In parallel with the image forming process, the sheet S stored in the cassette 13 of the sheet feed unit 40 is sent out by the pickup roller 14 and separated one sheet at a time by the separation roller 15. Skewing of the sheet S is corrected by a skew correction unit of the sheet conveyance apparatus 7 described later, and the sheet S is conveyed by a registration roller pair 30 at a predetermined conveyance timing in correspondence with a transfer timing of image at the transfer nip N1. The printer 1 includes a manual sheet feed tray 17 on which the sheet S is placed, and the sheet S placed on the manual sheet feed tray 17 may be fed by a manual sheet feed belt 18 and a separation roller 19.
Thereafter, a full-color toner image on the intermediate transfer belt 8 is transferred at the transfer nip N1 to the sheet S by secondary transfer bias applied to the secondary transfer roller 11. The toner remaining on the intermediate transfer belt 8 is cleaned by a cleaning device 12. Predetermined heat and pressure are applied at the fixing unit 81 to the sheet S on which the toner image has been transferred, and the toner is melted and fixed. The sheet S having passed the fixing unit 81 is guided by a guide member 82 to the sheet discharge roller pair 84 and discharged by the sheet discharge roller pair 84 to a sheet discharge tray 85.
If a duplex printing job of forming images on both sides of the sheet S is entered, the sheet S on which an image has been formed on the surface at the transfer nip N1 is guided by the guide member 82 to the inversion roller pair 86. Then, the sheet S is inverted by the inversion roller pair 86 and conveyed to a duplex conveyance path 87. The sheet S guided to the duplex conveyance path 87 is conveyed again to the sheet conveyance apparatus 7, where image is formed on a rear side of the sheet at the transfer nip N1, and the sheet is discharged by the sheet discharge roller pair 84 onto the sheet discharge tray 85.
Sheet Conveyance Apparatus
Next, the configuration of the sheet conveyance apparatus 7 will be described with reference to
As illustrated in
As illustrated in
As illustrated in
A first urging spring 73 serving as an urging member and first urging member is provided in a contracted state between the shutter member 70 and the retention member 72, and the shutter member 70 is urged toward a standby position illustrated in
Further, a second urging spring 71 serving as a second urging member is extended between the retention member 72 and a spring hook 74f of a sheet feed frame 74 (refer to
As illustrated in
Now, a distance between abutment surfaces 70a and 70a of the skew correction units 93F and 93R in the width direction is set as distance W1, and a distance between abutment surfaces 70a and 70a of the skew correction units 92F and 92R in the width direction is set as distance W2. If a sheet having a width wider than distance W1 is conveyed, the sheet contacts the abutment surfaces 70a and 70a of the skew correction units 93F and 93R before coming into contact with the skew correction units 91F, 91R, 92F and 92R, and skewing is corrected.
If a sheet having a width narrower than distance W1 and wider than distance W2 is conveyed, the sheet contacts the abutment surfaces 70a and 70a of the skew correction units 92F and 92R before coming into contact with the skew correction units 91F and 91R, and skewing is corrected. If a sheet having a width narrower than distance W2 is conveyed, the sheet contacts the abutment surfaces 70a and 70a of the skew correction units 91F and 91R without coming into contact with the skew correction units 92F, 92R, 93F and 93R, and skewing is corrected.
By arranging the skew correction units 91F, 91R, 92F, 92R, 93F and 93R as described, the leading edge of the sheet abuts against two abutment surfaces 70a and 70a that are as spaced apart in the width direction as possible corresponding to the size of the sheet being conveyed. Thereby, skewing of the sheet can be corrected highly accurately.
A photosensor 75 serving as a detection sensor is arranged at a position corresponding to the skew correction unit 91R arranged at the center side in the width direction. The photosensor 75 includes a light emitting unit 75a having a light source and a light receiving unit 75b capable of receiving light emitted from the light emitting unit 75a. The photosensor 75 outputs different signals depending on whether an optical path between the light emitting unit 75a and the light receiving unit 75b is opened or blocked.
A first flag 70f serving as a flag portion is provided at a lower portion of the shutter member 70 of the skew correction unit 91R, and a second flag 72f is provided at a lower portion of the retention member 72. The first flag 70f and the second flag 72f are configured to open and block the optical path of the photosensor 75 based on the pivoting positions of the shutter member 70 and the retention member 72. In other words, the position of the sheet being conveyed can be detected by a signal output from the photosensor 75 based on the operation of the first flag 70f and the second flag 72f.
In the present embodiment, the skew correction units 91F, 91R, 92F and 92R excluding the outermost skew correction units 93F and 93R adopt a same configuration. The only difference between the skew correction units 93F and 93R and the skew correction units 91F, 91R, 92F and 92R is that in the former units, a driven roller 79 is provided on the shutter member 70. The skew correction units 93F and 93R adopt a same configuration.
Generally, an adhesive label sheet in which a label having an adhesive applied on one side and an adhesive release paper attached to the adhesive side of the label are integrated have a standard size, and the adhesive label sheet serving as the sheet member used in the printer 1 according to the present embodiment has a width wider than distance W1. Therefore, skewing of the adhesive label sheet is corrected by the skew correction units 93F and 93R. In the process during which the adhesive label sheet passes the skew correction units 93F and 93R, as described later, the retention member 72 of the skew correction units 93F and 93R pivot. When the retention member 72 of the skew correction units 93F and 93R pivots, the retention member 72 of the skew correction unit 91R having the second flag 72f co-rotates with the connecting plate 72C. Further, the shutter member 70 of the skew correction unit 91R having the first flag 70f also pivots by being pushed by the adhesive label sheet being conveyed. Therefore, even according to an adhesive label sheet having a width wider than distance W1, the position of the adhesive label sheet can be detected by the photosensor 75.
As illustrated in
Operation of Skew Correction Unit
Next, the operation of the skew correction unit 93F in a state where an adhesive label sheet LS is conveyed will be described with reference to
In a state where a leading edge of the adhesive label sheet LS abuts against the abutment surface 70a, a loop is formed on the adhesive label sheet LS, and skewing of the adhesive label sheet LS is corrected by the leading edge of the sheet being aligned on the abutment surface 70a of the skew correction unit 93F and the abutment surface 70a of the skew correction unit 93R. Further, in a state where the adhesive label sheet LS is conveyed by the pre-registration roller pair 16, as illustrated in
During the process in which the shutter member 70 and the retention member 72 pivot integrally, the abutment surface 70a of the shutter member 70 retreats from the conveyance path CP, and the nip N2 of the registration roller pair 30 nips and conveys the adhesive label sheet LS. That is, during the process in which the shutter member 70 moves from the standby position, the nip N2 of the registration roller pair 30 nips the adhesive label sheet LS and conveys the adhesive label sheet LS being nipped. In this state, the skew correction unit 93F is at a second state where the retention member 72 is positioned at the second position and the shutter member 70 is positioned at the standby position, with the leading edge of the adhesive label sheet LS separated from the abutment surface 70a. While the skew correction unit 93F transits from the first state to the second state, the second flag 72f of the retention member 72 blocks the optical axis of the photosensor 75. Thereby, the photosensor 75 can detect the leading edge position of the sheet S.
The leading edge of the adhesive label sheet LS moves in sliding motion from the abutment surface 70a toward the driven roller 79, and the adhesive label sheet LS is conveyed in sliding motion against the driven roller 79. As described, in a state where the leading edge of the adhesive label sheet LS slides against the abutment surface 70a, the adhesive provided between the label and the adhesive release paper of the adhesive label sheet LS may adhere to the abutment surface 70a.
In a state where the leading edge of the adhesive label sheet LS passes the abutment surface 70a and the driven roller 79, as illustrated in
In a state where the skew correction unit 93F is in the third state, the first flag 70f of the shutter member 70 blocks the optical axis of the photosensor 75, and the photosensor 75 detects that the adhesive label sheet LS is being conveyed. The driven roller 79 slides against the adhesive label sheet LS conveyed by the registration roller pair 30 and rotates by friction. The driven roller 79 is composed of a resin material containing fluorine, which suppresses adhesion of the adhesive on the adhesive label sheet LS on the driven roller 79.
When the driven roller 79 slides against the surface of the adhesive label sheet LS, the driven roller 79 is arranged further toward the conveyance path CP than the shutter member 70, so that the shutter member 70 is separated from the adhesive label sheet LS. In other words, the shutter member 70 is positioned so as not to intersect with a nip line L1 of the nip N2 of the registration roller pair 30. At this moment, the leading edge of the adhesive label sheet LS has already passed the abutment surface 70a. Therefore, even if an adhesive is adhered to the abutment surface 70a or other portions of the shutter member 70, adhesion of the adhesive label sheet LS to the adhesive can be suppressed. Thereby, it becomes possible to prevent the adhesive label sheet LS from adhering to the shutter member 70 or the retention member 72 and causing the shutter member 70 or the retention member 72 to move integrally with the adhesive label sheet LS, so that the positions of the shutter member 70 and the retention member 72 can be stabilized. Therefore, the operations of the first flag 70f and the second flag 72f that are respectively arranged on the shutter member 70 and the retention member 72 are stabilized, and the position of the adhesive label sheet LS can be detected accurately by the photosensor 75 while preventing erroneous detection.
Moreover, conveyance failure such as jamming caused by the adhesive label sheet LS being adhered to the shutter member 70 or the retention member 72 or damaging of the adhesive label sheet LS can be reduced. Further, since the leading edge of the adhesive label sheet LS is transferred smoothly from the abutment surface 70a to the driven roller 79, the peeling of the adhesive release paper of the adhesive label sheet LS caused by the adhesive being attached to the abutment surface 70a can be suppressed, and a high quality printing can be achieved.
When the trailing edge of the adhesive label sheet LS passes the driven roller 79, the shutter member 70 returns to the standby position by the urging force of the first urging spring 73, and the skew correction unit 93F returns to the first state. In a state where the skew correction unit 93F is returned to the first state, the first flag 70f and the second flag 72f open the optical axis of the photosensor 75, and the photosensor 75 detects that the adhesive label sheet LS has passed the sheet conveyance apparatus 7.
Next, a second embodiment of the present invention is illustrated, wherein the second embodiment has configured the skew correction unit 93F of the first embodiment with a simpler configuration. Therefore, configurations similar to the first embodiment are either not shown or denoted with the same reference numbers.
Configuration of Skew Correction Unit
As illustrated in
Further, the shutter member 170 is urged toward the standby position by a spring not shown. The shutter member 170 is provided with a flag not shown, similar to the first embodiment, and a photosensor not shown has an optical path that is opened or blocked by the flag.
The driven roller 179 is arranged downstream in the sheet conveyance direction than the abutment surface 170a of the shutter member 170 positioned at the standby position, and at least a portion of the outer circumference surface is protruded to a second side toward the conveyance path CP than the abutment surface 170a (right side in the drawing). Further, the driven roller 179 is composed of a resin material containing fluorine, which suppresses adhesion of the adhesive on the adhesive label sheet LS on the driven roller 179.
Operation of Skew Correction Unit
Next, the operation of the skew correction unit 193F in a state where the adhesive label sheet LS is conveyed will be described. As illustrated in
Further, in a state where the adhesive label sheet LS is conveyed, as illustrated in
Until the trailing edge of the adhesive label sheet LS passes the driven roller 179, the shutter member 170 is retained at the retreated position. In a case where the shutter member 170 is positioned at the retreated position, the driven roller 179 slides against the surface of the adhesive label sheet LS, and the shutter member 170 is separated from the adhesive label sheet LS. In other words, the shutter member 170 is positioned so as not to intersect with the nip line L1 of the nip N2 of the registration roller pair 30. Therefore, even if the adhesive is adhered to the abutment surface 170a or other portions of the shutter member 170, the adhesive label sheet LS is suppressed from being adhered to the adhesive.
Thereby, it becomes possible to prevent the adhesive label sheet LS from being adhered to and co-rotating with the shutter member 170, and to stabilize the position of the shutter member 170. Thus, the operation of the flag not shown provided on the shutter member 170 can be stabilized, and the position of the adhesive label sheet LS can be detected highly accurately while preventing erroneous detection by the photosensor.
Moreover, conveyance failure such as jamming caused by the adhesive label sheet LS being adhered to the shutter member 170 or damaging of the adhesive label sheet LS thereby can be reduced. Further, since the leading edge of the adhesive label sheet LS is transferred smoothly from the abutment surface 170a to the driven roller 179, the peeling of the adhesive release paper of the adhesive label sheet LS caused by the adhesive attached to the abutment surface 170a can be suppressed, and a high quality print can be obtained.
In all the embodiments described earlier, the skew correction units 93F and 193F were equipped with a function to correct skewing of the sheet and detect the position of the sheet, but the present invention is not limited to this example, and the configuration may only have one of these two functions. The position of the sheet may be detected by a switch or other sensors, instead of the photosensor 75.
The driven rollers 79 and 179 are formed of a resin material containing fluorine, but the present invention is not limited thereto, and the driven rollers 79 and 179 can be formed of any material. Further, a plurality of driven rollers can be provided on a single shutter member. Even further, if a plurality of skew correction units are provided, the driven roller may be provided on skew correction units excluding the skew correction units arranged at outermost sides in the width direction.
The embodiments described above have been illustrated based on the printer 1 adopting an electrophotographic system, but the present invention is not limited thereto. For example, the present invention can be applied to an image forming apparatus adopting an inkjet system in which an image is formed on a sheet by discharging ink through a nozzle.
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. 2019-021749, filed Feb. 8, 2019, which is hereby incorporated by reference herein in its entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| JP2019-021749 | Feb 2019 | JP | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 4842944 | Kuge | Jun 1989 | A |
| 8387975 | Suzuki | Mar 2013 | B2 |
| 9388005 | Iizuka | Jul 2016 | B2 |
| 9586778 | Iizuka | Mar 2017 | B2 |
| 9938102 | Iizuka | Apr 2018 | B2 |
| 20180186588 | Iizuka | Jul 2018 | A1 |
| Number | Date | Country |
|---|---|---|
| H11-255378 | Sep 1999 | JP |
| 2013-177244 | Sep 2013 | JP |
| Number | Date | Country | |
|---|---|---|---|
| 20200255242 A1 | Aug 2020 | US |
