Patent Application
20190367301
The present disclosure relates to a sheet conveyance apparatus that conveys sheets and to an image forming apparatus including the sheet conveyance apparatus.
There is a conventional image forming apparatus such as a printer, a copying machine, or a facsimile in which a sheet stored in a sheet supplying cassette is conveyed by a feed roller included in a sheet conveyance apparatus and then the sheet is conveyed to an image forming unit. The sheet conveyance apparatus includes a separation unit that separates sheets one by one when two or more sheets are conveyed by the feed roller.
As an example of the separation unit, there is a retard separation type of separation unit that includes a conveyance roller rotating in a forward rotation direction, which is the same direction as the direction in which the corresponding feed roller rotates, and a retard roller functioning as a separation member that comes into contact with the conveyance roller with a predetermined pressure. The retard roller is provided with driving force via a torque limiter and can rotate in the forward and reverse rotation directions.
In the retard separation type of separation unit, when two or more sheets are inserted into a separation nip portion formed by the retard roller and the conveyance roller of the separation unit, the retard roller rotates in the forward rotation direction. As a result, the sheet being in contact with the conveyance roller is conveyed toward the corresponding image forming unit, and the sheet being in contact with the retard roller is conveyed toward the corresponding sheet supplying cassette. Consequently, the two or more sheets can be prevented from being conveyed with overlaps. The retard separation type of separation unit utilizes the friction between a surface of the sheet and a surface of the retard roller. However, since this friction gradually wears down the surface of the retard roller and deteriorates the separation performance, the retard roller needs to be replaced regularly.
Japanese Patent Application Laid-Open No. 2015-75497 discusses improving the replacement performance of the retard roller. According to this technique, a retard roller is attached to a free end of a drive shaft supported at only one end. With this configuration, a user can replace the retard roller by removing the retard roller from the free end of the drive shaft.
However, with the configuration discussed in Japanese Patent Application Laid-Open No. 2015-75497, when a user replaces the retard roller, it is difficult for the user to hold the retard roller, which may deteriorate the replacement performance of the retard roller. For example, when replacing a retard roller configured to have a smaller diameter or when an access path to a retard roller in a sheet conveyance apparatus is narrow, it is difficult for the user to hold the retard roller.
The present disclosure is directed to a sheet conveyance apparatus having a separation member with replacement performance.
According to an aspect of the present invention, a sheet conveyance apparatus includes a storage unit configured to store a sheet, a conveyance member configured to convey a sheet, a support shaft portion having one end as a fixed end that is fixed to a main body of the sheet conveyance apparatus and the other end as a free end that is not fixed to the main body, and a separation unit configured to pinch and convey a sheet with the conveyance member and to separate a plurality of sheets stored in and fed from the storage unit one by one, wherein the separation unit includes a separation member that is supported by the support shaft portion and rotatable with the support shaft portion, and a holding member capable of holding the separation member, wherein, by moving the holding member in an axial direction of the support shaft portion, the separation unit is removed from the sheet conveyance apparatus with the holding member holding the separation member.
Further features of the present invention will become apparent from the following description of embodiments with reference to the attached drawings.
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Each of the following embodiments will be described based on an example in which a laser beam printer is used as an image forming apparatus including a sheet conveyance apparatus according to the corresponding embodiment. However, the components described in the following embodiments are only examples. Unless otherwise specified, the description of the components will not limit the scope of the present invention.
The feed unit 4 includes a feed roller 41 that feeds a sheet S stored in the sheet supplying cassette 3, a conveyance roller 42 which functions as a conveyance member that conveys the sheet S fed by the conveyance feed roller 41, and a separation unit 43. When a plurality of sheets S is conveyed by the feed roller 41 from the sheets S stored in the sheet supplying cassette 3, the conveyance roller 42 and the separation unit 43 separate the conveyed sheets S and convey only one sheet toward the image forming unit 5. The configuration of the feed unit 4 that feeds the sheets S will be described in detail below.
The image forming unit 5 includes a photosensitive drum 50 that functions as an image bearing member, an exposure unit 51, a developing unit 52, and a transfer roller 53. When a control unit (not illustrated) such as a controller receives an image signal, an image forming operation is started, and the photosensitive drum 50 is rotated. When rotated, the photosensitive drum 50 is electrically charged evenly by a charging unit (not illustrated) and is exposed by the exposure unit 51 in accordance with the image signal. As a result, an electrostatic latent image is formed on the surface of the photosensitive drum 50. Next, this electrostatic latent image is developed by the developing unit 52, and as a result, a toner image is formed on the surface of the photosensitive drum 50. The transfer roller 53 comes into contact with the photosensitive drum 50 and forms a transfer nip portion with the photosensitive drum 50. After the toner image formed on the surface of the photosensitive drum 50 is transferred onto the sheet S fed by the feed unit 4 at the transfer nip portion, the fixing unit 6 applies heat and pressure to fix the toner image on the sheet S. In this way, an image is formed on a sheet S in the image forming unit 5. Then, the sheet S passes through the fixing unit 6, and the sheet S that has undergone printing processing is discharged onto the sheet discharge tray 7.
Hereinafter, a configuration of the feed unit 4 of the image forming apparatus 1 according to the present embodiment and an operation of separating and conveying the sheets S one by one by the separation unit 43 will be described in detail with reference to
The feed roller 41 and the conveyance roller 42 can rotate by receiving driving force of a driving source (not illustrated). When the feed roller 41 is into contact with the topmost sheet S stacked on the stacking plate 30, the feed roller 41 is urged with predetermined pressure by an urging unit such as a spring (not illustrated).
In addition, the feed unit 4 includes a first sheet detection member 44 that can move when coming into contact with a sheet S. The feed unit 4 also includes a sensor (not illustrated) that can sense rotation of the first sheet detection member 44. When the first sheet detection member 44 comes into contact with a sheet S stacked on the stacking plate 30 and moves upward in
Next, a configuration of the separation unit 43 will be described with reference to
As illustrated in
In addition, as illustrated in
When a sheet S is conveyed by the conveyance roller 42 and the separation unit 43, the retard roller 43a is supported by a retard roller support shaft 23 inserted into the through-hole a2, and the retard roller 43a is urged against the conveyance roller 42. In this state, when the retard roller 43a is lifted in the direction indicated by an arrow N in
To remove the retard roller 43a from the holder 43c, first, the retard roller 43a is pulled in the direction indicated by the arrow N. Consequently, the shaft portions a1 and a3 come into contact with the upper ends of the holding portions c1 and c1′, respectively, in the direction indicated by the arrow N. When the retard roller 43a is pulled further in the direction indicated by the arrow N, the holding portions c1 and c1′ are elastically deformed, and the retard roller 43a can be removed from the holder 43c. Thus, the retard roller 43a is detachably held in the holder 43c in such a manner that the retard roller 43a is not easily detached from the holder 43c even when the separation unit 43 is turned upside down. The holder 43c is made of synthetic resin by using injection molding.
Next, an operation of separating sheets S by the separation unit 43 will be described with reference to
Based on a signal for feeding a sheet S, the feed roller 41 and the conveyance roller 42 start to rotate (forward rotation) in a direction in which the sheet S is conveyed to the image forming unit 5, and the retard roller 43a starts to rotate by the driving force transferred from the retard roller support shaft 23. While the retard roller support shaft 23 normally receives the driving force that rotates (forward rotation) the retard roller support shaft 23 in the same direction as that of the rotation of the conveyance roller 42, the torque limiter 24 changes the rotation direction of the retard roller 43a, depending on the sheet pinching state at the separation nip portion N. Hereinafter, the rotation direction of the retard roller 43a will be described with reference to
As illustrated in
In contrast, when sheets S are fed with overlaps by the feed roller 41 and a plurality of sheets S is pinched at the separation nip portion N, the separation unit 43 separates the sheets S and conveys only one sheet S as follows. The following case assumes that a first sheet S1 and a second sheet S2 are pinched at the separation nip portion N, as illustrated in
The retard roller 43a wears down and deteriorates as it separates and conveys the sheets S. Consequently, the friction coefficient of the retard roller 43a is decreased. When the retard roller 43a deteriorates, the performance of separating the sheets S may be decreased. Accordingly, a user or a serviceperson (hereinafter, referred to as a user) needs to replace the retard roller 43a regularly.
Next, replacement of the retard roller 43a according to the present embodiment will be described with reference to
In
As illustrated in
Next, a configuration of slidably supporting the separation unit 43 will be described. As illustrated in
When the user slides the separation unit 43 in the direction indicated by the arrow L in
As illustrated in
In addition, in the present embodiment, when a new retard roller 43a is attached to the separation unit 43, the user places the new retard roller 43a in the space formed by the separation nip guide 43b and the holder 43c by holding the shaft portions a1 and a3 on the sides of the new retard roller 43a. An elastic portion such as rubber is formed on the surface of the retard roller 43a, and the retard roller 43a may be deteriorated by sebum of the user. Thus, when the user replaces an old retard roller 43a by a new retard roller 43a, the user should avoid touching the elastic portion of the new retard roller 43a as much as possible. By attaching the new retard roller 43a to the separation unit 43 while holding the shaft portions a1 and a3 on the sides of the new retard roller 43a, the user can avoid touching the elastic portion of the new retard roller 43a. Other than rubber, for example, urethane or sponge can be used for the elastic portion formed on the surface of the retard roller 43a. The above description is also applied to these cases.
When the user attaches the separation unit 43, to which a new retard roller 43a has been attached, to the feed unit 4, the user can do the opposite of the above operation of removing the separation unit 43. More specifically, by using the space created by the movement of the guide 25 upon removal of the separation unit 43, the user places the separation unit 43 on the upper guide portion 22a of the frame 22. Next, the user slides the separation unit 43 in the direction opposite to the direction indicated by the arrow L in
As described above, according to the present embodiment, by sliding the separation unit 43, the user can integrally attach and detach the retard roller 43a, the separation nip guide 43b, and the holder 43c as the separation unit 43 to and from the feed unit 4. With this configuration, the user can easily replace the retard roller 43a. Accordingly, the replacement performance of the retard roller 43a can be refined.
In addition, according to the present embodiment, the user can attach and detach the retard roller 43a to and from the separation unit 43 by holding the shaft portions a1 and a3 formed on the sides of the retard roller 43a. In this way, when the user replaces the retard roller 43a, a hand of the user does not touch the elastic portion of the new retard roller 43a. Thus, deterioration of the new retard roller 43a can be prevented.
The present embodiment has been described based on an example in which the user first removes the separation unit 43 from the feed unit 4 and next replaces the retard roller 43a. However, the user may remove an old separation unit 43 from the feed unit 4 to replace it by a new separation unit 43. As described above, since the user can attach and detach the separation unit 43 to and from the feed unit 4 when replacing the retard roller 43a, a hand of the user does not touch the elastic portion of the new retard roller 43a.
In addition, the present embodiment has been described assuming that the user holds the shaft portions a1 and a3 of the retard roller 43a when attaching and detaching the retard roller 43a to and from the separation unit 43. However, the user may hold other portions, as long as the user does not touch the elastic portion of the retard roller 43a. For example, the user may attach and detach the retard roller 43a to and from the separation unit 43 by holding resin portions on the sides of the retard roller 43a.
Next, a configuration of a fixing portion that fixes the separation unit 43 attached to the feed unit 4 to the feed unit 4 will be described with reference to
The holder 43c of the separation unit 43 has the engaging portion c3 as illustrated in
Consequently, the separation unit 43 is detached from the feed unit 4. In this way, the separation unit 43 can be fixed to the frame 22 of the feed unit 4.
The fixing portion may have a different configuration. For example, the lower guide portion 22b may be provided with a depressed portion as the engaged portion. In this case, when the engaging portion c3 elastically deforms and moves in the depressed portion, the separation unit 43 is fixed to the feed unit 4. The fixing portion may have any configuration, as long as the user can fix the separation unit 43 to the frame 22 by sliding the separation unit 43.
Next, a configuration in which the guide 25 moves with the separation unit 43 will be described. As illustrated in
In addition, when the user slides the separation unit 43 in the direction indicated by the arrow L in
A different configuration may be used to move the guide 25 with the separation unit 43. For example, a hole may be provided in the guide 25 as a fitting portion, and a protruding portion may be provided on the holder 43c of the separation unit 43 as a fitted portion that fits with the fitting portion of the guide 25. With this configuration, as with the above configuration according to the present embodiment, by fitting the hole with the protruding portion, the guide 25 can move with the separation unit 43. Any configuration of coupling the guide 25 and the separation unit 43 may be used, as long as the guide 25 moves with the separation unit 43.
While the separation unit 43 and the guide 25 are configured to move together according to the present embodiment, the embodiments are not limited to this configuration. The user may slide the guide 25 in the direction opposite to the direction indicated by the arrow L in
Regarding the movement of the guide 25, the user may manually move the guide 25 in the direction indicated by the arrow L in
According to the present embodiment, the motor M as a driving source is connected to the retard roller support shaft 23 via the torque limiter 24, and when the retard roller support shaft 23 rotates upon receiving the driving force transferred from the motor M, the retard roller 43a rotates along with the retard roller support shaft 23. However, the embodiments are not limited to this configuration. The motor M as a driving source may not be connected to the retard roller support shaft 23. In this case, because of the torque limiter 24 arranged at the fixed end of the retard roller support shaft 23, when no sheet S is pinched at the separation nip portion N and when the conveyance roller 42 is not rotated, the retard roller 43a is not rotated and is stopped at the separation nip portion N.
Thus, when a single sheet S is pinched at the separation nip portion N, since the retard roller 43a receives the driving force from the conveyance roller 42 via the sheet S, the frictional force that occurs between the retard roller 43a and the sheet S is increased. Thus, the retard roller 43a rotates with the rotation of the conveyance roller 42, and the sheet S at the separation nip portion N is conveyed toward the image forming unit 5. In contrast, when two sheets S are fed with overlaps by the feed roller 41 to the separation nip portion N, the frictional force that occurs between the two sheets S is relatively smaller than the frictional force that occurs when a single sheet S is pinched at the separation nip portion N. Thus, since the retard roller 43a does not rotate, the sheet S on the conveyance roller 42 is conveyed toward the image forming unit 5, and the sheet S on the retard roller 43a is not conveyed but stopped at the separation nip portion N.
When the motor M as a driving source is not connected to the retard roller support shaft 23, sheets S can be separated in accordance with the above operation at the separation nip portion N with a simple configuration. The torque limiter 24 may be arranged inside the retard roller 43a. Alternatively, the torque limiter 24 is not necessarily arranged at the retard roller support shaft 23.
The present embodiment has been described assuming that the user replaces the retard roller 43a by removing the separation unit 43 from the feed unit 4 first and removing the retard roller 43a from the separation unit 43 next. However, the embodiments are not limited to such configuration. The present invention is applicable to any roller that easily deteriorates by abrasion and needs to be replaced, as the retard roller 43a does. By arranging a mechanism for attaching and detaching a holder that holds such a roller, as in the present embodiment, beneficial effects similar to those according to the present embodiment can be obtained.
According to the first embodiment, the guide 25 as a guiding member of the feed unit 4 is configured to slide. More specifically, when removing the separation unit 43 from the feed unit 4, the user slides the separation unit 43, and the guide 25 is moved in conjunction with the sliding of the separation unit 43. Meanwhile, as illustrated in
As illustrated in
As described above, according to the present embodiment, only by pulling the sheet supplying cassette 203 from the image forming apparatus 1, the user can ensure the space for sliding the separation unit 243 in the direction indicated by the arrow L in
As described above, the configuration according to the present embodiment can also provide beneficial effects similar to those provided according to the first embodiment.
The above embodiments have been described based on examples in which the present disclosure is applied to electrophotographic image forming apparatuses. However, the embodiments are not limited to the above embodiments. For example, an embodiment is applicable to non-electrophotographic image forming apparatuses, such as inkjet image forming apparatuses.
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.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2016-213532 | Oct 2016 | JP | national |
This application is a continuation of U.S. patent application Ser. No. 15/796,024, filed on Oct. 27, 2017, which claims priority from Japanese Patent Application No. 2016-213532, filed Oct. 31, 2016, all of which are hereby incorporated by reference herein in their entirety.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 15796024 | Oct 2017 | US |
| Child | 16542160 | US |
