Field of the Invention
The present invention relates to a feeding apparatus and an image forming apparatus.
Description of the Related Art
An image forming apparatus such as a printer and a copying machine conventionally includes a feeding apparatus for feeding sheets one by one. As a feeding apparatus, a configuration including a stacking plate serving as a sheet stacking unit and a feed roller for feeding sheets on the stacking plate is known.
The feeding apparatus includes a sheet surface detection mechanism for detecting the height of the topmost surface of the sheets on the stacking plate. Japanese Patent Application Laid-Open No. 2011-57386 and Japanese Patent Application Laid-Open No. 2009-202967 discuss configurations in which the sheet surface detection mechanism is arranged in a position downstream of the feed roller.
Japanese Patent No. 4612893 discusses a configuration in which a lifter mechanism for lifting up the stacking plate is mechanically operated based on the height of the topmost surface of the sheets on the stacking plate.
However, Japanese Patent Application Laid-Open No. 2011-57386 and Japanese Patent Application Laid-Open No. 2009-202967 do not discuss a sheet surface detection position in a width direction orthogonal to a feeding direction. Consequently, with the configurations discussed in Japanese Patent Application Laid-Open No. 2011-57386 and Japanese Patent Application Laid-Open No. 2009-202967, it is sometimes been not possible to appropriately detect the sheet surface if the sheets stacked on the stacking plate are curled (wavy) in the width direction. Appropriately controlling the height of the topmost surface of the sheets on the stacking plate is also important in a configuration that mechanically controls the lifter mechanism, like the configuration discussed in Japanese Patent No. 4612893.
The present invention is directed to a feeding apparatus and an image forming apparatus capable of appropriately controlling the height (position) of the topmost surface of the sheets stacked on the stacking plate.
According to an aspect of the present invention, a feeding apparatus for feeding a sheet includes a stacking member configured to stack a sheet, a vertically movable feed roller configured to feed the sheet stacked on the stacking member, a vertically movable contact member including a sheet contact portion configured to make contact with the sheet stacked on the stacking member, and a lifting unit configured to lift up the stacking member, the lifting unit being configured to stop lifting up of the stacking member as the sheet contact portion is pressed to lift up by the sheet stacked on the stacking member. The feed roller is pressed to move upward by the sheet stacked on the stacking member while the lifting unit lifts up the stacking member. At least a part of the sheet contact portion is arranged downstream of a position where the feed roller makes contact with the sheet in a feeding direction of the sheet by the feed roller, and inside an area where the feed roller makes contact with the sheet in an axial direction of the feed roller.
Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
A first exemplary embodiment to which an exemplary embodiment of the present invention is applied will be described below with reference to the drawings. Common elements in the drawings will be designated by the same reference numerals.
An image forming apparatus 100 includes a cartridge 7 in which a photosensitive drum 1 serving as an image bearing member is included. An exposure unit 2 which emits laser based on image information to form an image on the photosensitive drum 1 is arranged near the photosensitive drum 1. A transfer roller 5 is provided which transfers a toner image on the photosensitive drum 1 to a sheet. The transfer roller 5 and the photosensitive drum 1 constitute a transfer unit for transferring the toner image to a sheet S.
Sheets S stacked on a sheet stacker (stacking member) 14 arranged in a feed cassette 8 are fed by a feed roller 20. A fed sheet S passes a contact portion between a conveyance roller 21 and a separation roller (separation member) 27 which is arranged in a position opposed to the conveyance roller 21. The sheet S is conveyed by a registration roller pair 3 and 4 to the transfer unit in time with the toner image. The transfer unit transfers the toner image to a surface of the sheet S. A fixing unit 10 fixes the toner image on the sheet S. The sheet S is then discharged by a discharge roller pair 11 and 12 to a discharge tray 13.
In the present exemplary embodiment, an electrophotographic image formation process using the transfer unit and the fixing unit 10 is employed for an image forming unit for forming an image on the sheet S. However, the present invention should not be limited thereto. For example, in an exemplary embodiment of the present invention, the image forming unit for forming an image on the sheet S may use an inkjet image formation process in which liquid ink is discharged from a nozzle to form an image on a sheet.
<Basic Configuration and Operation of Feeding Apparatus 70>
Next, a basic configuration and operation of a feeding apparatus 70 according to the first exemplary embodiment will be described.
The feeding apparatus 70 illustrated in
The feed roller 20 and the conveyance roller 21 are held by a roller holder (holding member) 48. The feed roller 20 and the conveyance roller 21 are arranged on a center side of the sheets S stacked on the stacking member 14 in an axial direction of the feed roller 20. The roller holder 48 is configured to be swingable about a conveyance roller fulcrum 21a relative to a not-illustrated feeding frame. A conveyance gear 42 is arranged coaxially with the conveyance roller 21. A feed gear 41 is arranged coaxially with the feed roller 20. An idler gear 43 is interposed between the conveyance gear 42 and the feed gear 41.
A coupling shaft 44 for transmitting the driving force of the motor M1 to the conveyance gear 42 is arranged on the not-illustrated feeding frame. With such a configuration, the driving force generated by the motor M1 is transmitted to the feed roller 20 and the conveyance roller 21.
The feeding apparatus 70 includes the motor (driving source) M1 which generates the driving force for rotating the conveyance roller 21 and the feed roller 20. The driving force of the motor M1 rotates the coupling shaft 44, whereby the conveyance gear 42 coupled with the coupling shaft 44 is rotated.
As illustrated in
<Detailed Configuration and Operation of Feed Roller Unit 45>
Next, a configuration and operation of the feed roller unit 45 will be described with reference to
The feeding apparatus 70 includes a sheet detection unit that detects the sheets S stacked on the sheet stacker 14. The sheet detection unit includes the first lever 40 (contact member) and a second lever (moving member) 46. The first lever 40 is configured to be vertically movable, and moves up when pressed by the sheets S stacked on the sheet stacker 14. The second lever 46 rotates in contact with the first lever 40. A sensor 47 detects the rotation of the second lever 46, so that the sheet detection unit can detect the amount (height) of sheets S stacked on the sheet stacker 14. As illustrated in
As illustrated in
If sheets S are set on the sheet stacker 14, the sector gear 24 and the lifter plate 23 operating integrally with the sector gear 24 are rotated in a counterclockwise direction in
As illustrated in
At the point when the sheets S are set on the sheet stacker 14 (the sheet stacker 14 is not lifted up), the flag portion 46b of the second lever 46 is biased upward by a second lever spring 51 to be in the second position where the light of the sensor 47 is blocked. The CPU 110 then drives the motor M2 to rotate the sheet stacker 14 upward as the sheet stacker 14 is loaded into the main body of the feeding apparatus 70.
Next, the topmost surface of the sheets S comes into contact with the feed roller 20 and the sheet contact portion 40a of the first lever 40. The feed roller 20 and the first lever 40 are pushed up by the sheets S. The lever contact portion 40b of the first lever 40 makes contact with the second lever 46, so that the second lever 46 rotates about the rotation center 46a, and the flag portion 46b rotates as well. If the flag portion 46b moves to the first position where the light of the sensor 47 is transmitted, the CPU 110 stops driving the motor M2. This completes the lift-up of the sheet stacker 14, and the sheets S on the sheet stacker 14 come to a position where the feed roller 20 is able to feed the sheets S.
In the foregoing description, the lift-up operation of the sheet stacker 14 is controlled based on the detection result of the turn ON/OFF of the optical sensor 47 by the second lever 46. However, the present invention should not be limited thereto. For example, like the configurations discussed in Japanese Patent Application Laid-Open No. 2009-12925 and Japanese Patent Application Laid-Open No. 2014-105099, without providing an optical sensor, the lift-up operation of the sheet stacker 14 may be mechanically performed according to the position of the sheets S on the sheet stacker 14. More specifically, for example, the first lever 40 and the second lever 46 which move up and down according to the position of the sheets S on the sheet stacker 14 may be configured to disconnect or connect a drive transmission unit between the motor M2 and the lifter plate 23. If the position of the sheets S on the sheet stacker 14 lowers, the sheet contact portion 40a also lowers. In accordance with this motion, the drive transmission unit is mechanically connected to start lifting up the sheet stacker 14. If the lift-up operation is completed and the position of the sheets S on the sheet stacker 14 is lifted up, the sheet contact portion 40a is also lifted up. In accordance with this motion, the drive transmission unit is disconnected to stop lifting up the sheet stacker 14.
As illustrated in
Next, an operation for feeding the sheets S will be described.
The CPU 110 drives the motor M1 to rotate the conveyance roller 21 and the feed roller 20 based on a feed start signal from a computer or the image forming apparatus 100. Sheets S fed by the feed roller 20 are separated one by one by the conveyance roller 21 and the separation roller 27, and fed to the registration roller pair 3 and 4.
As illustrated in
If a certain number of sheets S are fed and the position of the flag portion 46b of the second lever 46 reaches the second position, the CPU 110 drives the motor M2 to rotate the sheet stacker 14 until the position of the flag portion 46b reaches the first position. The feeding apparatus 70 repeats the foregoing operation during the feeding operation of the sheets S, so that the height of the sheets S on the sheet stacker 14 is controlled to be within a predetermined range.
As the feeding of the sheets S is repeated in the foregoing feeding operation, the feed roller 20 wears off gradually. The sheet contact portion 40a of the first lever 40 also wears off together. In the present exemplary embodiment, the sheet contact portion 40a is configured to have a width narrower than that of the feed roller 20 so that the positional relationship between the sheet contact portion 40a and the feed roller 20 will not change along with the progress of wear.
Next, a configuration for attaching and detaching the feed roller unit 45 according to the present exemplary embodiment to/from the image forming apparatus 100 will be described with reference to
As illustrated in
As illustrated in
When attaching a new feed roller unit 45 to the image forming apparatus 100, the user can put the feed roller unit 45 on the slide shaft 49 and slide the slide shaft 49 in the Y direction to engage the feed roller unit 45 with the coupling shaft 44.
As described above, the present exemplary embodiment includes the first lever 40 which lifts up in contact with the sheets S and the second lever 46 which lifts up in contact with the first lever 40, as the mechanism for appropriately adjusting the sheet surface (height) of the sheets S stacked on the sheet stacker 14. The roller holder 48 holds the first lever 40. In such a manner, the sheet contact portion 40a of the first lever 40 can be located, in the feeding direction, between the position where the feed roller 20 makes contact with a sheet S and the position where the conveyance roller 21 makes contact with the sheet S without increasing the size of the image forming apparatus 100. The sheet contact portion 40 can also be located within the area of the feed roller 20 in the axial direction of the feed roller 20. In other words, the area where the feed roller 20 makes contact with the sheet S and the area where the sheet contact portion 40a makes contact with the sheet S overlap in the axial direction of the feed roller 20.
As described above, according to the present exemplary embodiment, the feed roller 20 and the first lever 40 can be simultaneously replaced. The positional relationship between the portion where the feed roller 20 makes contact with the sheet S and the sheet contact portion 40a of the first lever 40 can thus be maintained identical before and after the replacement of the roller unit 48.
Consequently, according to the present exemplary embodiment, the orientation (position) of the leading edge of the sheet S fed out by the feed roller 20 can be maintained substantially constant. This can suppress variations of the sheet feeding performance. Further, the present exemplary embodiment also has high usability and serviceability because the individual components (the feed roller 20 and the first lever 40) do not need to be separately replaced or subjected to maintenance.
Next, a second exemplary embodiment to which an exemplary embodiment of the present invention is applied will be described. In the following description of the second exemplary embodiment, a description of configurations and operations common to the first exemplary embodiment will be omitted.
<Basic Configuration and Operation>
A basic configuration and a basic operation of the second exemplary embodiment are similar to those of the first exemplary embodiment. A description thereof is thus omitted.
<Detailed Configuration and Operation>
A characteristic configuration of the second exemplary embodiment will be described with reference to
The configuration for attaching and detaching the feed roller unit 45 is similar to that of the first exemplary embodiment. More specifically, in the second exemplary embodiment, the feed roller 20, the first lever 40, and the roller 40c integral with the first lever 40 are integrated as the feed roller unit 45. The feed roller 20, the first lever 40, and the roller 40c can thus be simultaneously detached from the image forming apparatus 100.
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. 2014-054175 filed Mar. 17, 2014, which is hereby incorporated by reference herein in its entirety.
Number | Date | Country | Kind |
---|---|---|---|
2014-054175 | Mar 2014 | JP | national |
Number | Name | Date | Kind |
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5123637 | Musaka | Jun 1992 | A |
5722653 | Seidl | Mar 1998 | A |
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Number | Date | Country |
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06056305 | Mar 1994 | JP |
2009-012925 | Jan 2009 | JP |
2009-202967 | Sep 2009 | JP |
4612893 | Jan 2011 | JP |
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2014-105099 | Jun 2014 | JP |
Number | Date | Country | |
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20150259163 A1 | Sep 2015 | US |