Patent Grant
10029869
Field of the Invention
The present invention relates to a sheet conveyance apparatus for conveying a sheet and an image forming apparatus including the sheet conveyance apparatus.
Description of the Related Art
Conventionally, a sheet conveyance apparatus, which is applicable to an image forming apparatus, used for conveying sheets has been provided with a sheet detection unit for detecting a position of a conveyed sheet. As the sheet detection unit, there is a type of the sheet detection unit in which the conveyed sheet pushes a detection member to rotate it so that the detection member blocks an optical path of a photo-interrupter.
Japanese Patent Application Laid-Open No. 2004-115255 discusses a configuration in which a rotation shaft of a detection member is rotatably supported between a pair of receiving members. The rotation shaft of the detection member is inserted into each of the opening portions formed with end portions of each of the pair of receiving members, so that the detection member is fixed between the receiving members. Each of the opening portions is set to be narrower than the diameter of the rotation shaft of the detection member to prevent the rotation shaft of the detection member from coming off. When the detection member is attached, the pair of receiving members is elastically deformed to temporarily expand each of the opening portions, and the rotation shaft of the detection member is inserted thorough each of the expanded opening portions.
However, in the configuration discussed in Japanese Patent Application Laid-Open No. 2004-115255, if each opening portion is temporarily expanded to attach the detection member (i.e., rotation member), there may be a following problem. Specifically, when the receiving members are elastically deformed to attach the detection member, the receiving members may be plastically deformed to change the size thereof so as to expand the portion for supporting the rotation shaft. As a result, a gap may be generated between each receiving member and the rotation shaft of the detection member, and the smooth rotation of the detection member cannot be achieved.
The present invention is directed to a sheet conveyance apparatus and an image forming apparatus capable of achieving smooth rotation of a member pushed and rotated by a sheet.
According to an aspect of the present invention, a sheet conveyance apparatus includes a conveyance unit configured to convey a sheet, a rotation unit including a shaft portion and configured to rotate by being pushed by a sheet conveyed by the conveyance unit, a sensor configured to generate a signal according to a position of the rotation unit in a rotational direction, a first supporting portion configured to rotatably support the shaft portion, a second supporting portion configured to rotatably support the shaft portion, an elastic portion connected to the shaft portion, and configured to extend in an axial direction of the shaft portion, and be elastically deformable in a direction intersecting with the axial direction of the shaft portion, a regulation portion configured to regulate the rotation unit supported by the first supporting portion and the second supporting portion at the shaft portion of the rotation unit from moving in the axial direction of the shaft portion by contacting the elastic portion.
Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
An image forming apparatus 1 includes an image forming station for yellow (Y), an image forming station for magenta (M), an image forming station for cyan (C), and an image forming station for black (Bk). These image forming stations have a similar configuration to each other. Therefore, as long as it is not particularly needed, descriptions of components thereof are made as a singular form. Each image forming station includes a photosensitive drum 11, a charging roller 12, and a developing unit 14.
A surface of the photosensitive drum 11 serving as an image bearing member is uniformly charged by the charging roller 12. Then, a latent image is formed thereon with a laser scanner 13 driven based on a transmitted image information signal. The latent image is visualized as a toner image by the developing unit 14, to which toner is supplied from a container 19 storing toner. Each of the toner images formed on the photosensitive drums 11 is sequentially transferred onto an intermediate transfer belt 61 by a predetermined pressure and an electrostatic load bias applied by a primary transfer roller 17, which is a part of a transfer unit 60. After the transfer of the toner images, a small amount of toner remaining on the photosensitive drum 11 is removed and collected by a photosensitive drum cleaner 15, and then, the photosensitive drum is ready for the next image forming.
On the other hand, sheets are fed from a sheet feed cassette 20 one by one, and conveyed by a pre-registration roller pair 23 serving as a conveyance unit for conveying a sheet. The sheet conveyed by the pre-registration roller pair 23 is guided by a conveyance guide 22, to arrive at a registration roller pair 21. A first sheet detection unit 101 is arranged at a position between the pre-registration roller pair 23 and the registration roller pair 21 to detect a position of a sheet.
The registration roller pair 21, in synchronization with the toner image on the intermediate transfer belt 61, conveys a sheet to between a transfer drive roller 62 for driving the intermediate transfer belt 61 in the transfer unit 60 and an outer secondary transfer roller 35 serving as an outer transfer roller. A color toner image on the intermediate transfer belt 61 is transferred to a sheet at a nip portion formed between the transfer drive roller 62 and the outer secondary transfer roller 35, which are disposed to face each other, by applying a predetermined pressure and an electrostatic load bias to the sheet.
The toner image transferred onto the sheet is fixed thereon by heat and pressure applied by a fixing device (fixing unit) 40. Then, the sheet is discharged by a discharge roller pair 41 onto a discharge tray 50.
Each image forming unit for forming an image on a sheet is configured of the image forming station, the transfer unit 60, and the fixing unit 40.
A second sheet detection unit 102 and a third sheet detection unit 103 for detecting a sheet are respectively arranged on a downstream side of the fixing unit 40 in the sheet conveyance direction, and on an upstream side of the discharge roller pair 41 in the sheet conveyance direction.
Signals output from the first sheet detection unit 101, the second sheet detection unit 102, and the third sheet detection unit 103 are transmitted to a control unit 104 that controls the sheet conveyance. The control unit 104 controls the sheet conveyance based on the signals output from the first, the second, and the third detection units 101, 102, 103. For example, if any one of the first, the second, and the third detection units 101, 102, 103 continues to detect a sheet for a longer time period than a predetermined time period, the control unit 104 determines that the sheet is retained at a position of the corresponding detection unit (retention jam). On the other hand, if no sheet detection unit detects the sheet at a timing at which the sheet is supposed to reach there, the control unit determines that a not-arrived jam occurs. In these cases, the control unit 104 stops the sheet conveyance and displays a warning on an operation unit 105 for prompting a user to remove the jammed sheet.
<Schematic Configuration of Sheet Detection Unit>
Referring to
The first sheet detection unit 101 includes a detection member 80, a sensor (photo-interrupter) 90, and a supporting member 70. The detection member 80 is a rotation member to be rotated when pressed by a conveyed sheet. The sensor 90 generates a signal corresponding to a position of the detection member 80 in a rotational direction. The supporting member 70 rotatably supports the detection member 80.
As illustrated in
The detection member 80 is urged by a force received from the spring 91 to rotate in an urging direction 96 illustrated in
When the conveyed sheet pushes the contact portion 88, the detection member 80 is rotated in an opposite direction of the urging direction 96 against the urging force of the spring 91. When the detection member 80 is rotated by the pushing of the conveyed sheet, the light-shielding portion 82 blocks the light from a light emitting element in the sensor 90. On receiving a signal from the sensor 90, the control unit 104 detects the presence of a sheet (arrival of a sheet).
<Configuration for Supporting Detection Member>
Next, the configuration for supporting the detection member 80 will be described in detail.
As illustrated in
The plate-like shape first supporting wall portion 77 is provided with a first supporting opening portion 72 as a first opening portion into which the rotation shaft 87 of the detection member 80 is inserted and supported. The second supporting wall portion 97 is provided with a second supporting opening portion 71 as a second opening portion into which the rotation shaft 87 of the detection member 80 is inserted and supported.
The rotation shaft 87 of the detection member 80 includes a large-diameter portion 81, a small-diameter portion 86, and an elastic portion 83 (refer to
The large-diameter portion 81, the small-diameter portion 86, the light-shielding portion 82, and the contact portion 88 of the rotation shaft 87 included in the detection member 80 configure a rotation unit to be rotated by the pushing of a sheet. In the present exemplary embodiment, the elastic portion 83 is directly connected to the shaft portion (large-diameter portion 81 and small-diameter portion 86), supported by the first supporting wall portion 77 and the second supporting wall portion, of the detection member 80. It is easy to deform the elastic portion 83 in an intersecting direction intersecting with the axial direction than the shaft portion (large-diameter portion 81 and small-diameter portion 86). In other word the amount of the deformation of the elastic portion 83 in the intersecting direction per unit length in the state that a force is applied to the elastic portion 83 in the intersecting direction is larger than the amount of the deformation of the shaft portion in the intersecting direction per unit length in the state that the same force is applied to the shaft portion in the intersecting direction.
As illustrated in
The light-shielding portion 82 and the contact portion 88 of the detection member 80 are provided between the first supporting opening portion 72 and the second supporting opening portion 71 in the axial direction of the detection member 80. With this configuration, the positional accuracy of the position of the light-shielding portion 82 becomes high to reduce unstable detection of the sheet.
The detection member 80 includes the small-diameter portion 86 at one end portion thereof, and the second supporting opening portion 71 supports the small-diameter portion 86. A boundary portion 92 between the large-diameter portion 81 and the small-diameter portion 86 (i.e., step portion between the large-diameter portion 81 and the small-diameter portion 86) is in contact with a side surface 36 of the second supporting wall portion 97 (i.e., second regulation portion) (see
The supporting member 70 is further provided with a regulation wall portion 73 serving as a regulation portion. The regulation wall portion 73 contacts the end portion of the elastic portion 83 (i.e., the end portion of the rotation shaft 87) to regulate the detection member 80 from moving in the rotational axis direction. The regulation wall portion 73 is a plate-like shape portion protruding from the base portion 700 of the supporting member 70, extending to intersect with the axial line of the rotation shaft 87 of the detection member 80. The position of the detection member 80 in the axial direction is regulated by a regulation surface 73a of the regulation wall portion 73 contacting the end portion of the elastic portion 83. Herein, in the axial direction, the direction toward the elastic portion 83 from the small-diameter portion 86 is referred to as a first direction. In the axial direction, the direction toward the small-diameter portion 86 from the elastic portion 83 is referred to as a second direction. The regulation surface 73a regulates the detection member 80 from moving in the first direction by contacting a portion of the rotation shaft 87 positioned on the first direction side of the large-diameter portion 81 (i.e., the end portion of the elastic portion 83).
The end portion of the regulation wall portion 73 is provided with a taper portion 84 inclining with respect to the regulation surface 73a. One end portion 31 of the taper portion 84 is provided at a position further separated from the base portion 700 of the supporting member 70 than the line (i.e., axial line) made by connecting the center of the first supporting opening portion 72 and the center of the second supporting opening portion 71, in a perpendicular direction to the axial line.
The taper portion 84 inclines in such a manner that another end portion 32 is further separated from the base portion 700 of the supporting member 70 than the one end portion 31. In other words, the taper portion 84 inclines in such a manner that with the increasing distance from the first supporting opening portion 72 in the axial direction, the distance between the taper portion 84 and the base portion 700 of the supporting member 70 increases in the radial direction of the rotation shaft from the line made by connecting the centers of the first supporting opening portion 72 and the second supporting opening portion 71. Further, a protruding portion 85 is provided on the regulation wall portion 73. The protruding portion 85 is configured to protrude from the one end portion 31 of the taper portion 84 in a direction perpendicular to the regulation surface 73a.
In addition, the supporting member 70 illustrated in
As described above, each of the first supporting opening portion 72 and the second supporting opening portion 71 is configured in a closed (with no cut portion) circular shape (refer to
<Attaching Method of the Detection Member 80>
Referring to
To attach the detection member 80 to the supporting member 70, first, as illustrated in
Then, as illustrated in
Then, the detection member 80 is moved in the C direction (second direction) illustrated in
The light-shielding portion 82 for blocking light emitted from the light emitting element in the sensor 90 is provided between the first supporting opening portion 72 and the second supporting opening portion 71. Therefore, even if the elastic portion 83 deforms slightly, the deformation rarely affects the detection accuracy of sheet presence/absence.
Since the end portion of the detection member 80 is regulated from moving to the upper side of the taper portion 84 by the protruding portion 85 provided on the one end portion 31 of the taper portion 84, the detection member 80 can be prevented from coming off from the supporting member 70.
In the present exemplary embodiment, the detection member 80 is regulated from moving in the C direction illustrated in
Further, if the detection member 80 is pushed in the direction opposite to the C direction, since the movement of the detection member 80 is regulated by the regulation wall portion 73, the small-diameter portion 86 does not come off from the second supporting opening portion 71.
In addition, the exemplary embodiment has been described assuming that the first supporting opening portion 72 and the second supporting opening portion 71 each have a circular shape, and the rotation shaft 87 has a columnar shape. However, as illustrated in
In the present exemplary embodiment described above, the small-diameter portion 86 is provided at the end portion opposite to the elastic portion 83 of the rotation shaft 87. However, as illustrated in
Further, the portion small in diameter extends as the elastic portion 83 to the end of the rotation shaft 87. However, as illustrated in
Further, in the present exemplary embodiment described above, the elastic portion 83 extends directly from the shaft supported by the first supporting wall portion 77 and the second supporting wall portion. However, the elastic portion may not directly extend from the shaft portion (not connected directly to the shaft), as long as the elastic portion extends in the axial direction and elastically deformable in the direction intersecting with the axial direction. For example, as illustrated in
A first comparative example of a supporting method of the detection member will be described with reference to
However, with the first comparative example, the detection member 180 may come off from the opening portion 76, when the detection member 180 is pushed in a direction opposite to the A direction. Generally, a portion of the detection member to be pushed by a conveyed sheet protrudes in a conveyance path. Therefore, a user may be able to touch the protruding portion at a time of jam recovery. Accordingly, when the user has touched the detection member, the detection member may come off.
Further, in the first comparative example, since the pair of receiving members 75 is elastically formed. However, when the pair of receiving members 75 is elastically deformed to expand the opening portion 76 to attach the detection member 80 thereto, the pair of receiving members 75 may be plastically deformed to cause a gap between the rotation shaft of the detection member 180 and the receiving members 75 with ease. As a result, as illustrated in
In the present exemplary embodiment, the detection member 80 is attached by inserting the rotation shaft 87 of the detection member 80 into the first supporting opening portion 72 and the second supporting opening portion 71 each having no cut portion. Therefore, the chance of the detection member 80 coming off from the first supporting opening portion 72 and the second supporting opening portion 71 is lower than that in the first comparative example. Further, in the present exemplary embodiment, the gap of the rotation shaft 87 of the detection member 80 with respect to the first supporting opening portion 72 and the second supporting opening portion 71 can be reduced. According to the present exemplary embodiment, the detection member can be rotated more smoothly than in the first comparative example in which the receiving members 75 are elastically deformed to expand the opening portion 76. Further, in the present exemplary embodiment, silence during rotation of the rotation shaft 87 can be enhanced. Because, in the present exemplary embodiment, since the detection member 80 is attached by inserting the rotation shaft 87 into the first supporting opening portion 72 and the second supporting opening portion 71, the gap between the rotation shaft and the supporting member, which is generated due to the plastic deformation of the supporting portion in the first comparative example, is not generated.
However, in the second comparative example, when the phase of the opening portion 276 and the phase of two-way taking shape 278 of the detection member 280 match with each other, the detection member 280 may come off from the retaining portion 275. Therefore, there may be a restriction for a rotation angle of the detection member 280. More specifically, in a case where the detection member 280 rotates more than 90 degrees, the phases of the opening portion 276 and the two-way taking shape 278 match with each other at a point. In this case, there is no removal prevention part, and the detection member 280 may come off from the retaining portion 275.
In the present exemplary embodiment, the detection member 80 is attached by inserting the rotation shaft 87 of the detection member 80 into the first supporting opening portion 72 and the second supporting opening portion 71 each having no cut portion. Therefore, the chance of the detection member 80 coming off from the first supporting opening portion 72 and the second supporting opening portion 71 is lower than that in the second comparative example.
Compared with the third comparative example, the present exemplary embodiment can provide a low-cost apparatus.
In addition, the present exemplary embodiment is applicable to the supporting method of a detection member that performs a reciprocating rotation operation, and among others, operating noise during rotation can be reduced. Therefore, it is useful for an apparatus in which the detection member is disposed at a position near the outside thereof such as near an outer casing.
As an example of the image forming unit for forming an image on a sheet, an electrophotographic method image forming unit is used. However, the present exemplary embodiment is applicable to an image forming apparatus including an ink-jet method image forming unit.
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. 2015-010363, filed Jan. 22, 2015, which is hereby incorporated by reference herein in its entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2015-010363 | Jan 2015 | JP | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 3545742 | Muller | Dec 1970 | A |
| 7495922 | Ploeg | Feb 2009 | B2 |
| 8388247 | Ichikawa | Mar 2013 | B2 |
| 8608153 | Ro | Dec 2013 | B2 |
| 20130161893 | Ro | Jun 2013 | A1 |
| 20150360894 | Takahashi | Dec 2015 | A1 |
| Number | Date | Country |
|---|---|---|
| 1122752 | May 1996 | CN |
| 1583535 | Feb 2005 | CN |
| S61-064650 | Apr 1986 | JP |
| H04-329753 | Nov 1992 | JP |
| 2004-115255 | Apr 2004 | JP |
| 2006-164581 | Jun 2006 | JP |
| Number | Date | Country | |
|---|---|---|---|
| 20160214816 A1 | Jul 2016 | US |
