Patent Application
20210188574
The present invention relates to a sheet feeding apparatus for feeding sheets, and an image forming apparatus equipped with the sheet feeding apparatus.
Hitherto, there has been proposed a sheet feeding apparatus having a pickup roller for feeding sheets that have been supported on a manual feed tray, and a conveyance roller and a separation roller that separate one sheet fed by the pickup roller from other sheets (refer to Japanese Patent Application Laid-Open Publication No. 2018-62399). The sheet feeding apparatus includes a return claw that is supported rotatably and designed to stand by at a standby position. The sheet having been separated by the conveyance roller and the separation roller is returned to the manual feed tray by the return claw pivoting from the standby position. Thereby, multiple feeding of sheets is reduced and feeding performance is improved.
Further, the return claw includes an abutting surface against which a leading edge of the sheet supported on the manual feed tray abuts when the return claw is at the standby position. The abutting surface regulates the position of the leading edges of the sheets set on the manual feed tray.
However, the abutting surface of the return claw described in Japanese Patent Application Laid-Open Publication No. 2018-62399 has a leading edge portion that is curved so that the sheet separated by the conveyance roller and the separation roller is returned to the manual feed tray without fail. Thus, the sheets inserted to the manual feed tray are aligned against the abutting surface to be set on the tray, so that there was a drawback in the setting property of sheets.
According to one aspect of the present invention, a sheet feeding apparatus includes a sheet supporting portion configured to support a first sheet and a second sheet that are superposed in a stacking direction, a rotary feeding member configured to feed the first sheet supported on the sheet supporting portion, a separation portion configured to separate the second sheet fed by following the first sheet from the first sheet, a return portion configured to return the second sheet, separated by the separation portion from the first sheet, toward the sheet supporting portion, and a regulating portion comprising a regulating surface configured to regulate a position of leading edges of the first sheet and the second sheet supported on the sheet supporting portion, the regulating portion being configured to move between a regulating position configured to regulate the position of leading edges of the first sheet and the second sheet by the regulating surface, and an allowing position being configured to allow feeding of the first sheet and the second sheet supported on the sheet supporting portion, the regulating surface being extended in the stacking direction in a state where the regulating portion is positioned at the regulating position.
Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
Now, a first embodiment according to the present invention will be described. A printer 100 serving as an image forming apparatus according to a first embodiment is a laser beam printer adopting an electrophotographic system. As illustrated in
In a state where an image forming command is output to the printer 100, an image forming process by the image forming unit 20 is started based on image information entered from an external computer and the like connected to the printer 100. The image forming unit 20 includes a photosensitive drum 102 serving as an image bearing member, a developing roller 113, a laser scanner 103, and a transfer roller 106. The laser scanner 103 irradiates laser light 112 toward the photosensitive drum 102 based on the entered image information. In this state, the photosensitive drum 102 is charged in advance by a charging roller not shown, and electrostatic latent image is formed on the photosensitive drum 102 by having the laser light 112 irradiated thereto. Thereafter, the electrostatic latent image is developed by the developing roller 113, and a toner image is formed on the photosensitive drum 102.
In parallel with the image forming process described above, the sheet S is fed by the sheet feeding apparatus 10. The sheet S fed by the sheet feeding apparatus 10 is conveyed by a conveyance roller pair 105 toward the transfer roller 106. A toner image formed on the photosensitive drum 102 is transferred to the sheet S by having transfer bias applied to the transfer roller 106.
The sheet S to which the toner image has been transferred by the transfer roller 106 is heated and pressed by the fixing unit 30. The fixing unit 30 for fixing the toner image is composed of a heating roller 107 having a heater embedded therein, and a pressure roller 108 urged toward the heating roller 107. The sheet S is discharged by the sheet discharge roller pair 109 to a sheet discharge tray 114.
If images are to be formed on both sides of the sheet S, the sheet discharge roller pair 109 subjects the sheet S having an image formed on a first side to switch-back and guides the sheet S to a duplex conveyance path 41. The sheet S having passed through the duplex conveyance path 41 and having an image formed on a second side by the transfer roller 106 is discharged from the apparatus by the sheet discharge roller pair 109.
Next, the configuration of the sheet feeding apparatus 10 will be described in detail. As illustrated in
The sheet S supported on the supporting tray 110 has its leading edge position regulated by the leading edge regulating portion 118 and its trailing edge position regulated by the trailing edge regulating plate 11. The trailing edge regulating plate 11 is supported movably in a sheet feeding direction FD with respect to the supporting tray 110, and the position of the trailing edge regulating plate 11 is determined by a user in correspondence to the size of the sheet S.
The feeding portion 50 includes a feeding roller 104 that contacts a stacked sheet S and feeds the same, a conveyance roller 115 that conveys the sheet S fed by the feeding roller 104, and a separation roller 116 that forms a separation nip 117 with the conveyance roller 115. Further, the feeding portion 50 includes a feeding holder 129 that is supported swingably around a conveyance roller shaft 115a (refer to
The return claw 119 serving as a return portion returns the sheet separated from an uppermost sheet by the separation nip 117 toward the supporting tray 110 serving as a sheet supporting portion. Thereby, multiple feeding of sheets S is reduced, and stable feeding performance is obtained.
In the present embodiment, the separation nip 117 for separating a sheet from other sheets is formed by the conveyance roller 115 and the separation roller 116, but the present invention is not limited thereto. For example, a separating pad can be adopted instead of the separation roller 116. In addition, a configuration of a torque limiter or a retard roller is adopted in the separation roller 116.
Next, the drive transmission portion 60 will be described in detail. As illustrated in
The drive transmission portion 60 includes a chipped tooth gear 123 that is rotated by the second drive gear 122, a solenoid unit 65 that positions the chipped tooth gear 123 at a standby position, and a separation gear 124 and a conveyance gear 125 that are meshed with the chipped tooth gear 123.
The chipped tooth gear 123 includes a gear portion 123a having a plurality of gear teeth and a chipped tooth portion 123b where the gear teeth are not formed, wherein the chipped tooth portion 123b is opposed to an output gear 122a of the second drive gear 122 in a state where the chipped tooth gear 123 is positioned at the standby position. The separation gear 124 and the conveyance gear 125 are meshed with the gear portion 123a of the chipped tooth gear 123. The separation gear 124 includes the same number of teeth as the gear portion 123a of the chipped tooth gear 123.
The solenoid unit 65 includes an engagement claw 66 engageable with an engagement portion 123c formed on a part of a circumference surface of the chipped tooth gear 123, a spring 67 that urges the engagement claw 66 toward a direction to engage with the engagement portion 123c, and a solenoid 68. By energizing the solenoid 68, the engagement claw 66 is moved to swing away from the engagement portion 123c against the urging force of the spring 67.
In a state where an image forming job is entered to the printer 100, the motor 120 is driven, and the pinion gear 120a, the first drive gear 121 and the second drive gear 122 are rotated. In this state, the chipped tooth gear 123 is positioned at a standby position illustrated in
When the solenoid 68 of the solenoid unit 65 is energized, the engagement claw 66 is separated from the engagement portion 123c of the chipped tooth gear 123 against the urging force of the spring 67. Then, the chipped tooth gear 123 is rotated for a predetermined angle by a spring not shown provided in the chipped tooth gear 123, and the gear portion 123a meshes with the output gear 122a of the second drive gear 122. Thereby, the chipped tooth gear 123 rotates by the driving force of the second drive gear 122, and the separation gear 124 and the conveyance gear 125 meshed with the chipped tooth gear 123 rotate. When the chipped tooth gear 123 rotates once and returns to the standby position, the engagement claw 66 urged by the spring 67 is engaged with the engagement portion 123c and the chipped tooth gear 123 is retained at the standby position.
As described, since the solenoid 68 is energized in a state where the motor 120 is driven, the chipped tooth gear 123 is controlled to rotate once. The separation gear 124 and the conveyance gear 125 are rotated only while the chipped tooth gear 123 is rotating.
As illustrated in
Next, the peripheral configuration and lifting and lowering operation of the feeding roller 104 will be described. As illustrated in
In a state where the feeding holder 129 is positioned at a lifted position, the contact portion 129a is in contact with a cam surface 130a of the feeding cam 130. The feeding holder 129 is urged downward by a feeding spring 131. That is, in a state where the feeding holder 129 is positioned at the lifted position, the contact portion 129a is pressed against the cam surface 130a by the urging force of the feeding spring 131. In a state where the feeding holder 129 is positioned at the lifted position, the feeding roller 104 retained by the feeding holder 129 is separated from the sheet S supported on the supporting tray 110 (refer to
When the chipped tooth gear 123 rotates and the feeding cam 130 is rotated therewith, the engagement between the cam surface 130a of the feeding cam 130 and the contact portion 129a is cancelled, and the feeding holder 129 pivots downward around the conveyance roller shaft 115a by the feeding spring 131. Thereby, the feeding roller 104 retained by the feeding holder 129 contacts the sheet S, and the sheet S is fed by the feeding roller 104 that serves as a rotary feeding member.
When the feeding cam 130 is rotated further, the contact portion 129a is engaged again with the cam surface 130a, and the feeding holder 129 is pivoted to the lifted position. In a state where the feeding holder 129 is positioned at the lifted position, the chipped tooth gear 123 is stopped at the standby position by the solenoid unit 65. That is, in a state where the chipped tooth gear 123 and the feeding cam 130 rotate once, the feeding roller 104 is transited from a separated state to a contact state and then again to the separated state with respect to the sheet S.
Next, a peripheral configuration of the separation roller 116 and a separation operation with respect to the conveyance roller 115 will be described. As illustrated in
A holder shaft 132b is rotatably supported on the conveyance guide 135, and the holder shaft 132b supports the separation roller holder 132 such that the separation roller holder 132 pivots integrally with the holder shaft 132b. The separation roller holder 132 is pivotable to a separation position, that is, position illustrated in
Further, a separation nip guide 134 is fixed to the conveyance guide 135, and the separation nip guide 134 includes an inclined plane 134a that is formed approximately flush with the inclined plane 135a of the conveyance guide 135. The inclined plane 134a guides the sheet S fed by the feeding roller 104 (refer to
Meanwhile, as illustrated in
In a state where the separation roller 116 is positioned at the separation position, the lever portion 132a contacts the cam surface 136a of the separation cam 136. The separation spring 133 urges the holder shaft 132b in a clockwise direction of
In a state where the chipped tooth gear 123 and the separation gear 124 rotate and the separation cam 136 is rotated therewith, the engagement between the cam surface 136a of the separation cam 136 and the lever portion 132a is cancelled, and the separation roller holder 132 pivots upward around the holder shaft 132b by the separation spring 133. Thereby, the separation roller 116 retained by the separation roller holder 132 contacts the conveyance roller 115 and the separation roller 116 is positioned at the contact position.
When the separation cam 136 rotates further, the lever portion 132a is reengaged with the cam surface 136a, and the separation roller 116 pivots to the separation position. In a state where the separation roller 116 is positioned at the separation position, the chipped tooth gear 123 is stopped at the standby position by the solenoid unit 65. That is, in a state where the chipped tooth gear 123 and the separation cam 136 rotate once, the separation roller 116 swings from the separation position to the contact position and then again to the separation position.
Next, the configuration and operation of the return claw 119 will be described.
As illustrated in
The positions of the claw portions 139a and 139b are determined with respect to the pivot shaft 140 in the axial direction, and the claw portions 139a and 139b are supported movably in the radial direction orthogonal to the axial direction. A spring 137a is disposed in a compressed manner between the base unit 138a and the claw portion 139a, and the spring 137a urges the claw portion 139a outward in the radial direction with respect to the pivot shaft 140. Similarly, a spring 137b is disposed in a compressed manner between the base unit 138b and the claw portion 139b, and the spring 137b urges the claw portion 139b outward in the radial direction with respect to the pivot shaft 140.
Meanwhile, as illustrated in
As illustrated in
In a state where the chipped tooth gear 123 and the separation gear 124 rotate and the return claw cam 144 is rotated therewith, the engagement between the cam surface 144a of the return claw cam 144 and the cam follower 140a is cancelled, and the return claw 119 pivots in the counterclockwise direction around the pivot shaft 140 by the return claw spring 141. Thereby, the return claw 119 moves to the retreated position. That is, the return claw 119 pivots downstream in the sheet feeding direction FD by moving from the standby position to the retreated position, where it is retreated from the conveyance path through which the sheet S passes.
More specifically, in the retreated position, the return claw 119 is retreated in an opposite direction from the feeding roller 104 with respect to the inclined plane 135a of the conveyance guide 135. Thereby, the sheet S conveyed by the feeding roller 104 and the separation nip 117 is conveyed smoothly without being obstructed by the return claw 119 positioned at the retreated position.
When the return claw cam 144 rotates further, the cam follower 140a is reengaged with the cam surface 144a, and the return claw 119 swings to the standby position. In a state where the return claw 119 is positioned at the standby position, the chipped tooth gear 123 is stopped at the standby position by the solenoid unit 65. That is, in a state where the chipped tooth gear 123 and the separation cam 136 rotate once, the return claw 119 pivots from the standby position to the retreated position and then again to the standby position.
Next, the operation of the return claw 119 during conveyance of a sheet will be described with reference to
As illustrated in
When the return claw 119 pivots from the retreated position to the standby position, the claw portions 139a and 139b receive force toward the inner side in the radial direction of the pivot shaft 140 from the first sheet S1. Therefore, the claw portions 139a and 139b move so as to compress the springs 137a and 137b. While the first sheet S1 passes the leading edge portions 146a and 146b of the claw portions 139a and 139b, the leading edge portions 146a and 146b slide against the surface of the first sheet S1 and the position of the claw portions 139a and 139b is maintained.
When the trailing edge of the first sheet S1 passes the leading edge portions 146a and 146b of the claw portions 139a and 139b, the claw portions 139a and 139b are returned by the springs 137a and 137b to the position illustrated in
Next, the configuration and operation of the leading edge regulating portion 118 will be described.
The leading edge regulating members 152 and 153 serving as regulating members respectively include regulating surfaces 152a and 153a that extend in the stacking direction SD and regulate the leading edge position of the sheet S supported on the supporting tray 110 (refer to
Meanwhile, as illustrated in
As illustrated in
In a state where the chipped tooth gear 123 rotates and the leading edge regulating cam 143 rotates therewith, as illustrate in
More specifically, the retreated position is a position of the leading edge regulating portion 118 where the regulating surfaces 152a and 153a are aligned against the inclined plane 135a of the conveyance guide 135. In a state where the leading edge regulating portion 118 is positioned at the retreated position, the regulating surfaces 152a and 153a may either be retreated as a whole toward the inner side of the conveyance guide 135 with respect to the inclined plane 135a or be slightly protruded toward the feeding roller 104. In any case, the leading edge regulating portion 118 is positioned at the retreated position to allow the conveyance of the sheet S.
When the leading edge regulating cam 143 rotates further, the cam follower 151a is reengaged with the cam surface 143a, and the leading edge regulating portion 118 pivots to the standby position. In a state where the leading edge regulating portion 118 is positioned at the standby position, the chipped tooth gear 123 stops at the standby position by the solenoid unit 65. That is, in a state where the chipped tooth gear 123 rotates once, the leading edge regulating portion 118 pivots from the standby position to the retreated position and then again to the standby position.
Next, an operation timing of the return claw 119 and the leading edge regulating portion 118 will be described. For example, if a certain amount of sheets S is conveyed by the feeding roller 104 in a state where the return claw 119 is positioned at the standby position, the sheet S may be scraped against the leading edge portions 146a and 146b of the return claw 119, which may cause the sheet S to be damaged.
Therefore, the timing at which the return claw 119 pivots from the standby position to the retreated position will be set as follows. An ideal conveyance distance of the sheet S by the feeding roller 104 when there is no slippage between the sheet S and the feeding roller 104 immediately after starting of conveyance operation is referred to as distance A. A distance from the regulating surfaces 152a and 153a of the leading edge regulating portion 118 positioned at the standby position to the leading edge portions 146a and 146b of the return claw 119 positioned at the standby position is referred to as distance B.
According to the present embodiment, in a case where distance A<distance B, the energization timing of the solenoid 68 is controlled so that the return claw 119 pivots from the standby position to the retreated position. Thereby damages to the sheet S can be reduced.
Further, the leading edge regulating portion 118 pivots from the standby position to the retreated position before the feeding roller 104 contacts the sheet S on the supporting tray 110. Even further, if the distance from the regulating surfaces 152a and 153a of the leading edge regulating portion 118 positioned at the standby position to the separation nip 117 is referred to as distance C, in a case where distance A<distance C, the separation roller 116 moves from the separation position to the contact position.
Moreover, if the distance from the regulating surfaces 152a and 153a of the leading edge regulating portion 118 positioned at the standby position to the nip of the conveyance roller pair 105 is referred to as distance D, in a case where distance A>distance D, the separation roller 116 moves from the contact position to the separation position. After the separation nip 117 has been cancelled, the return claw 119 and the leading edge regulating portion 118 return from the retreated position to the standby position. The operation timings of the return claw 119 and the leading edge regulating portion 118 are not necessarily the same, and they can be set differently.
The timings at which the return claw 119, the leading edge regulating portion 118 and the separation roller 116 are operated and the lifting and lowering of the feeding roller 104 are determined by the energization timing of the solenoid 68 and the shapes of the return claw cam 144, the leading edge regulating cam 143, the separation cam 136 and the feeding cam 130. The operation timings can be set arbitrarily.
The trailing edge regulating plate 11 includes a regulating surface 11a that is extended in the stacking direction SD and that regulates the position of trailing edges ST of the sheet bundle SB. As described above, in a state where the leading edges SL of the sheet bundle SB are aligned against the inclined planes 134a and 135a, the trailing edges ST of the sheet bundle SB are also dispersed in the sheet feeding direction FD. Then, a space SP is formed between the trailing edge ST of the sheet bundle SB and the regulating surface 11a extending in the stacking direction SD, and the sheet bundle SB tends to be deviated. Therefore, the position of the leading edges of the sheet become unstable, and the feeding performance is deteriorated.
Thus, the sheet feeding apparatus 10 of the present embodiment is provided with the leading edge regulating portion 118. The leading edge regulating portion 118 includes regulating surfaces 152a and 152b that extend in the stacking direction SD at the standby position. The sheets S supported on the supporting tray 110 are set in a state where the leading edges of the sheets are abutted against the regulating surfaces 152a and 152b, so that the setting property of sheets can be improved.
Further, the sheet feeding apparatus 10 includes the return claw 119, and the return claw 119 returns the sheet retained at the separation nip 117 toward the supporting tray 110. Thereby, multiple feeding of the sheets S can be reduced and the feeding performance can be improved. As described, improvement of both the feeding performance and the setting performance of the sheets S are realized.
Next, a second embodiment of the present invention will be described. The configuration of the leading edge regulating portion 118 of the first embodiment has been changed according to the second embodiment. Similar configurations as the first embodiment are either not shown or denoted with the same reference numbers in the drawings.
As illustrated in
Meanwhile, the leading edge regulating portion 218 does not include a cam follower 151a (refer to
As illustrated in
The claw portions 139a and 139b are positioned in the axial direction with respect to the pivot shaft 140 and supported movably in the radial direction orthogonal to the axial direction. A spring 137a is disposed in a compressed manner between the base unit 138a and the claw portion 139a, and the spring 137a urges the claw portion 139a outward in the radial direction with respect to the pivot shaft 140. Similarly, a spring 137b is disposed in a compressed manner between the base unit 138b and the claw portion 139b, and the spring 137b urges the claw portion 139b outward in the radial direction with respect to the pivot shaft 140. The drive configuration of the return claw 219 is similar to that of the first embodiment.
The leading edge regulating members 152 and 153 are respectively arranged such that at least a portion thereof overlaps with the claw portions 139a and 139b in an axial direction AD of the pivot shaft 151. The claw portions 139a and 139b are respectively provided with contact portions 240a and 240b that come into contact with the leading edge regulating members 152 and 153. The leading edge regulating members 152 and 153 are urged by a leading edge regulating spring 242 serving as an urging portion attached to the pivot shaft 151 so as to contact the contact portions 240a and 240b.
That is, in a state where the return claw 219 is positioned at the standby position, the contact portions 240a and 240b regulate pivoting of the leading edge regulating portion 218 to the retreated position. Further, the leading edge regulating portion 218 serving as a regulating portion is allowed to pivot from the standby position to the retreated position by the return claw 219 pivoting from the standby position to the retreated position.
As illustrated in
When the return claw 219 pivots from the retreated position to the standby position, the leading edge regulating portion 218 is pressed by the contact portions 240a and 240b against the urging force of the leading edge regulating spring 242. Thereby, the leading edge regulating portion 218 is returned to the standby position.
In the present embodiment, the leading edge regulating portion 218 is urged downstream in the sheet feeding direction FD by the leading edge regulating spring 242, but the present invention is not limited thereto. For example, a configuration without the leading edge regulating spring 242 can be adopted where the leading edge regulating portion 218 is pressed and pivoted by the leading edge of the sheet S conveyed by the feeding roller 104.
According to the above-described configuration, the sheets S supported on the supporting tray 110 can be set in a state where the leading edges of the sheets S are abutted against the regulating surfaces 152a and 152b, so that the setting property can be improved. Further, the return claw 219 returns the sheet retained at the separation nip 117 toward the supporting tray 110. Thereby, multiple feeding of sheets S can be reduced and the feeding performance can be improved. As described, improvement of both the feeding performance and the setting performance of the sheets S is realized.
The leading edge regulating members 152 and 153 of the leading edge regulating portion 218 are respectively arranged such that at least a portion of the leading edge regulating members 152 and 153 is overlapped with the claw portions 139a and 139b in the axial direction AD. Therefore, a recessed portion 135b (refer to
All the embodiments described above have been described based on the sheet feeding apparatus 10 that feeds sheets supported on the supporting tray 110, but the present invention is not limited thereto. For example, as illustrated in
In all the embodiments described above, the sheet S is fed by the feeding roller 104, but the present invention is not limited thereto. For example, a belt that attracts the sheets S by electrostatic force of negative pressure can be used instead of the feeding roller 104 to feed the sheets S.
Further, in all the embodiments described above, the sheets S are set on the supporting tray 110, but the present invention is not limited thereto. For example, the supporting tray 110 can be detachably mounted to the printer body, or the supporting tray 110 can be replaced with a cassette that is detachably mounted to the printer body to store sheets.
In the second embodiment, the contact portions 240a and 240b are provided on the claw portions 139a and 139b, but the present invention is not limited thereto. For example, the contact portions 240a and 240b can be provided on the pivot shaft 140 of the return claw 219.
All the embodiments have been described based on the printer 100 or 200 adopting the electrophotographic system, but the present invention is not limited thereto. For example, the present invention is applicable to an image forming apparatus that adopts an ink-jet system in which image is formed on sheets by discharging ink through nozzles.
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. 2019-231458, filed Dec. 23, 2019, which is hereby incorporated by reference herein in its entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2019-231458 | Dec 2019 | JP | national |
