Patent Application
20150042037
1. Field of the Invention
The present invention relates to a sheet stacking device, a sheet feeding device, and an image forming apparatus including the same.
2. Description of the Related Art
In a case of forming an image on an envelope whose sealing flap is folded and if a plurality of such envelopes is set while aligning with each other within a feed cassette, a height (thickness) of the envelopes on a side of a region where the flaps exist within the feed cassette becomes higher than a height of the envelopes on a side of a region where there is no flap. The more the number of stacked envelopes, the greater the difference of the heights becomes in this state, and an uppermost envelope is inclined remarkably.
With regard this problem, Japanese Patent Application Laid-open No. Hei. 11-35175 has proposed a sheet feeding device provided with an envelope pressing roller above set-up envelopes and configured to prevent an uppermost surface of the set-up envelope from inclining by pressing a region of the envelope where there is a flap, i.e., a bulge, by the envelope pressing roller.
However, because the sheet feeding device disclosed in Japanese Patent Application Laid-open No. Hei-11-35175 is configured to absorb a difference in a vertical direction between the bulge of the flap part of the sheet bundle (bundle of envelopes) and parts other than the flap part only by pressing by the roller, the set-up envelopes are tightened closely with each other and a friction force between the envelopes increases. Therefore, a conveyance load of the feed roller increases, possibly causing a feeding failure and others due to a slip of the feed roller.
According to a first aspect of the present invention, a sheet stacking device includes a base member and a sheet stacking portion on which a sheet is stacked. The sheet stacking portion is supported by the base member swingably in a first direction orthogonal to a second direction, and swings and changes an inclination angle for holding the stacked sheet.
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 of a first embodiment of the present invention will be described below with reference to
At first, a configuration of the printer 100 of the present embodiment will be schematically explained with reference to
As shown in
The printer body 101 includes a body-side sheet feed portion 10 feeding a sheet, a manual feed portion 20 configured to allow a sheet to be manually fed, an image forming portion 30 configured to be able to form an image on a sheet, a discharge roller pair 40 discharging the sheet on which the image has been formed out of the apparatus, and a control portion 50 controlling those units.
The body-side sheet feed portion 10 includes a fed sheet cassette 11 on which the sheet S to be fed is stacked and a feed portion 12 feeding the sheet S stacked on the fed sheet cassette 11 while separating one by one. Four stages of the body-side sheet feed portions 10 are provided in the present embodiment. The manual feed portion 20 includes a manual feed tray 21 on which a sheet S can be stacked and a manual feed portion 22 configured to be able to feed the sheet S stacked on the manual feed tray 21 to the printer body 101. The manual feed tray 21 is configured such that it can be stored in the printer body 101.
The image forming portion 30 includes four process cartridges 31Y, 31M, 31C, and 31K forming four color images of yellow (Y), magenta (M), cyan (C), and black (K). The image forming portion 30 also includes an exposure unit 32 exposing surfaces of photoconductive drums 33Y, 33M, 33C, and 33K described later. It is noted that because the four process cartridges 31Y through 31K are constructed in the same manner except of the colors of the images to be formed, only a configuration of the process cartridge 31Y will be explained and an explanation of the process cartridges 31M through 31K will be omitted here. The process cartridge 31Y includes the photoconductive drum 33Y, a charging roller charging the photoconductive drum 33Y, and a developing roller developing an electrostatic latent image formed on the photoconductive drum 33Y.
The image forming portion 30 also includes an intermediate transfer belt 34 on which toner images of the photoconductive drums 33Y through 33K are primarily transferred, and primary transfer rollers 35Y, 35M, 35C, and 35K primarily transferring the toner images on the photoconductive drums 33Y through 33K to the intermediate transfer belt 34. The image forming portion 30 also includes a secondary transfer portion 36 secondarily transferring the primarily transferred toner image to the sheet S and a fixing portion 37 heating and fixing the secondarily transferred toner image.
As shown in
The image reading unit 102 is disposed at an upper part of the printer body 101 and is provided above a discharge sheet stacking portion 104 described later through an intermediary of a discharge space above the discharge sheet stacking portion 104 formed above the printer body 101. It is noted that the image reading unit 102 is controlled by the control portion 50.
The sheet feeding device 200 is configured such that it can be removably attached to the printer body 101, and such that the sheet S stored therein can be fed to the printer body 101 by connecting it with the printer body 101. It is noted that the sheet feeding device 200 will be described later in detail.
Next, an image forming operation of the printer 100 (image forming control of the control portion 50) will be explained. In response to an input of image information from the image reading unit 102, an external personal computer or the like, the exposure unit 32 irradiates a laser beam to the photoconductive drum 33Y through 33K based on the inputted image information. At this time, the photoconductive drums 33Y through 33K have been charged in advance by the charging roller, and electrostatic latent images are formed on the photoconductive drum 33Y through 33K by the irradiation of the laser beam. The electrostatic latent images are developed by the developing rollers, and toner images of yellow (Y), magenta (M), cyan(C), and black (K) are formed on the photoconductive drum 33Y through 33K. The toner images of the respective colors formed on the photoconductive drum 33Y through 33K are superimposed and transferred sequentially to the intermediate transfer belt 34 by the primary transfer rollers 35Y through 35K. The four color toner images superimposed and transferred to the intermediate transfer belt 34 are conveyed by the intermediate transfer belt 34 to the secondary transfer portion 36.
In parallel with the image forming operation described above, the sheet S stacked in the fed sheet stacking portion 11 (referred to as a ‘fed sheet cassette’ hereinafter) is fed by the feed portion 12 one by one to the registration roller pair 103. Then, the registration roller pair 103 conveys the sheet S to the secondary transfer portion 36 with a predetermined conveying timing to transfer the toner images on the intermediate transfer belt 34. The sheet S on which the toner images have been transferred is conveyed to the fixing portion 37 to fix the toner images and is then discharged by the discharge roller pair 40 to and stacked on the discharge sheet stacking portion 104.
It is noted that in a case where images are to be formed on both surfaces of the sheet S, the sheet S in which the image has been formed on a first surface thereof is conveyed to a duplex conveying path 106 by a reverse conveying roller pair 105. The sheet S is then conveyed again to the image forming portion 30 through the duplex conveying path 106 to form an image on a second surface thereof.
Next, the sheet feeding device 200 described above will be specifically explained with reference to
As shown in
The feed unit body 201 is configured such that it can be connected to the printer body 101 and such that the sheet feeding device 200 is controlled by the control portion 50 by connecting the feed unit body 201 to the printer body 101. That is, each component of the sheet feeding device 200 described later is controlled by the control portion 50.
A storage box 202 is configured such that it can be stored within the feed unit body 201 and such that it can be drawn out of the feed unit body 201 by a pair of side rails 210 provided at both sides thereof. In the present embodiment, the storage box 202 is provided with the pair of side rails 210 at upstream and downstream sides of the sheet feeding direction (direction indicated by an arrow D in
The storage box 202 also includes side restricting plates (width direction restricting portion) 207a and 207b restricting a widthwise position of the sheet S orthogonal to the sheet feeding direction, and a rear-end restricting plate 208 located upstream in the sheet feeding direction and restricting a rear-end position of the sheet S. The storage box 202 also includes a tray (supporting portion) 209 capable of supporting the stored (stacked) sheet S and a lifter 211 lifting the tray 209.
As shown in
The side restricting plates 207a and 207b are supported in the storage box 202 so as to be movable in the width direction orthogonal to the sheet feeding direction and are configured to abut against widthwise both ends of the sheet S to restrict widthwise position of the sheet S. The rear-end restricting plate 208 is supported in the storage box 202 so as to be movable in a direction (direction of an arrow B shown in
The feeding roller 203, the feed roller 204 and the retard roller 205 are rubber rollers around which highly frictional members such as rubber are wrapped and are arranged as follows. That is, in a case where the feeding roller 203 sends out a plurality of sheets S stored in the storage box 202 for example, the retard roller 205 blocks the sheet other than the uppermost sheet from being fed and the feed roller 204 feeds only the uppermost sheet.
Next, a sheet feeding operation (a sheet feeding operation under control of the control portion 50) performed by the sheet feeding device 200 will be explained. When the sheet feeding device 200 is connected to the printer body 101, the sheet feeding device 200 is electrically connected with the printer body 101 and the sheet feeding device 200 can be controlled by the control portion 50. At first, from this state, the storage box 202 is drawn out of the feed unit body 201 to set the sheet S on the tray 209 of the storage box 202 from above. A work space for setting the sheet S is assured by drawing the storage box 202 out of the feed unit body 201. After setting the sheet S on the tray 209, the side restricting plates 207a and 207b and the rear-end restricting plate 208 are adjusted to a sheet size to restrict a feed position of the sheet S.
When the storage box 202 in which the sheet S has been set is stored in the feed unit body 201, the lifter 211 starts to lift the tray 209 and the feeding roller 203 stops at a predetermined position to feed an uppermost sheet S on the tray 209. The feeding roller 203 is provided with a height detecting sensor which outputs a detection signal when the uppermost sheet S pushes up the feeding roller 203 to the predetermined position due to the lift of the tray 209. Thereby, the control portion 50 controls the lifter 211 and stops the tray 209, so that the uppermost sheet S is kept at the predetermined position where the sheet S can be fed.
After that, when the feed of the sheet S is started and height of an uppermost sheet is lowered, the tray 209 rises again and the feeding roller 203 stops at the predetermined position. The sheet S is fed to the printer body 101 while repeating such operations and when the feed of a specified number of sheets S is finished, the feeding roller 203 stops.
Here, the sheet feeding device 200 is configured to be able to feed a sheet whose thickness is different, e.g., an envelope P provided with a flap, by using a removable swinging stacking portion 300. An operation of feeding an envelope P with a flap performed by using the swinging stacking portion 300 will be explained below with reference to
As shown in
The swing base 301 is provided with a plurality of projections 301a at an under surface thereof such that the projections 301a can fit into a plurality of positioning holes 209b (see
Formed on an upper surface side of the swing base 301 are depressions 304 and 305 formed at downstream and upstream sides in the sheet feeding direction and a crest portion 306 projecting upward between the depressions 304 and 305. A rib 307 projecting upward is formed at a downstream end in the sheet feeding direction of the depression 304, and a swing shaft 308 extending in parallel with the sheet feeding direction is fixed between the rib 307 and the crest portion 306. In the same manner, a rib not shown is formed at an upper stream end in the sheet feeding direction of the depression 305, and a swing shaft 309 (see
The downstream and upstream swinging plates 302 and 303 are formed substantially into rectangular parallelepiped shapes and supported turnably respectively by the swing shafts 308 and 309. That is, the downstream and upstream swinging plates 302 and 303 are supported respectively by the swing base 301 with a predetermined distance from the depressions 304 and 305 swingably in the width direction (in a direction of an arrow R in
Next, an operation performed when the envelope P is stacked on the swinging stacking portion 300 attached to the tray 209 will be explained with reference to
At first, the storage box 202 is drawn out of the feed unit body 201 and the swinging stacking portion 300 is attached to the predetermined position on the tray 209. Then, a plurality of envelopes P is set on the stacking surfaces 302a and 303a of the downstream and upstream swinging plates 302 and 303. After setting the plurality of envelopes P on the tray 209, the side restricting plates 207a and 207b and the rear-end restricting plate 208 are adjusted to the size of the envelopes to determine a feed position of the envelopes P.
When the storage box 202 in which the envelopes P have been set is stored in the feed unit body 201, the tray 209 starts to rise and the feeding roller 203 stops at a predetermined position for feeding an uppermost envelope P on the swinging stacking portion 300 as shown in
Here, if a large number of ordinary envelopes P with flaps is piled up while being aligned in the same direction, a height (level) of a region of the envelopes P where there exit flaps becomes higher than that of a region of the envelopes P where there exist no flap. It is because a thickness of the envelopes P of the region where there exist the flaps is thicker than a thickness of the envelopes P where there exists no flaps, and the more the number of envelopes P is piled up, the more the thickness increases. If the difference of the heights of the stacked envelopes P becomes significant, an inclination of an upper surface of the upper most envelope P increases. If the inclination of the uppermost envelope P increases, a relative angle of an upper surface of the uppermost envelope P with respect to a roller surface of the feeding roller 203 increases, and if the relative angle increases, an area of contact of the feeding roller 203 with the uppermost envelope P decreases. If the area of contact decreases, a feeding force of the feeding roller 203 drops.
Meanwhile, when such envelopes P are stacked on the swinging stacking portion 300, the downstream and upstream swinging plates 302 and 303 swing centering on the swing shaft 308 and 309 by own weight of the envelopes P as shown in
It is noted that even if the upper surface of the uppermost envelope P is inclined slightly from the horizontal level, the envelope P is inclined as a whole when the roller surface of the feeding roller 203 comes into contact with the envelope P and the upper surface of the envelope P is substantially horizontalized. This arrangement makes it possible to make the roller surface come into contact with the upper surface of the envelope P uniformly in an axial direction of the feeding roller 203. Then, because a pressure of contact is uniformly applied to the upper surface of the envelope P in the axial direction, the envelope P can be fed stably without skewing the envelop P.
It is noted that even if the envelopes P are disposed reversely in the width direction (the flapped region PH is positioned on the side restricting plate 207b side) as shown in
The downstream and upstream swinging plates 302 and 303 swing freely centering on the swing shafts 308 and 309 as described above, so that the flapped region PH naturally drops and the flap-less region PL rises even if the heights are extremely different due to the flaps of the envelopes P. Therefore, it is possible to keep the uppermost envelope P horizontal in a well-balanced manner. Thereby, the uppermost envelope P comes into contact correctly with the feeding roller 203, and the feeding roller 203 can feed the envelope P without causing a slip with the envelope P. It is noted that the term ‘horizontal’ mentioned here also includes a state close to horizontal.
Still further, because the tray 209 rises and the uppermost envelope P is pressed against the feeding roller 203 in feeding the envelope P, the downstream swinging plate 302 under the feeding roller 203 is horizontally corrected reliably with respect to the feeding roller 203. Meanwhile, because the upstream swinging plate 303 can swing independently from the downstream swinging plate 302, the upstream swinging plate 303 is less influenced by the horizontal correction made by the feeding roller 203 which is pressed against the envelope P. That is, the upstream swinging plate 303 is horizontally corrected based on a shape of a bundle of the envelopes P stacked right above the upstream swinging plate 303. That is, the downstream swinging plate 302 is horizontally corrected such that the feed by the feeding roller 203 is stabilized, and the upstream swinging plate 303 is horizontally corrected so as to stably support the envelopes P. This arrangement makes it possible to stably stack the envelopes P effectively by dividing roles and tendencies of the downstream and upstream swinging plates 302 and 303.
Still further, because the uppermost envelope P is substantially horizontalized, the flap-less region PL in the width direction can be positioned above the downstream wall surface 202a in the sheet feeding direction of the storage box 202. This arrangement makes it possible to prevent the feeding failure otherwise from occurring by the flap-less region PL colliding against the downstream wall surface 202a in the sheet feeding direction.
Still further, as shown in
Still further, because the swing base 301 is inclined upward toward the downstream side in the sheet feeding direction as shown in
Thus, the use of the swing base 301 which is inclined upward toward the downstream side in the sheet feeding direction enables to surpass the downstream wall surface 202a in the sheet feeding direction and to smoothly feed the envelope P.
It is noted that because the swinging stacking portion 300 is configured to be removable from the tray 209, the swinging stacking portion 300 may be detached from the tray 209 and a sheet may be stacked on the tray 209 in feeding the normal sheet S for example. It is possible to stack a larger amount of sheets S by removing the swinging stacking portion 300 from the tray 209.
As described above, it is possible to prevent the sheet feeding failure from occurring in the printer 100 of the present embodiment because the sheet is fed by attaching the swinging stacking portion 300 to the tray 209 in feeding the sheet whose thickness varies such as an envelope P.
Still further, because the structure of the swinging stacking portion 300 is simple and the swinging stacking portion 300 is configured to be used by attaching to the tray 209, it is possible to feed a sheet whose thickness varies such as the envelope P readily without increasing a cost.
Next, an image forming apparatus of a second embodiment of the present invention will be described with reference to
As shown in
In stacking the envelopes P on the swinging stacking portion 400 positioned on and fixed to the tray 209, there is a case where the side restricting plates 207a and 207b, and the rear-end restricting plate 208 are adjusted to sizes of the envelopes P in advance for example and where the envelopes P are inserted therein from above However, there is a case where it is difficult to insert the envelopes P from right above the tray 209 because the storage box 202 in which the tray 209 is stored is drawn out of the feed unit body 201 in use and because a top plate of the feed unit body 201 hinders the insertion of the envelopes P. Still further if the side restricting plates 207a and 207b and the rear-end restricting plate 208 are adjusted to the size of the envelope P in advance, there is no enough space which enables a user to hold the envelopes P in setting the envelopes P.
Then, as shown in
There is also a case of placing the envelopes P on the upstream swinging plate 403 and of setting the envelopes P in this state while sliding on the swinging stacking portion 400 by adjusting the rear-end restricting plate 208 to the size of the envelopes P. Because the downstream and upstream swinging plates 402 and 403 have the inclined surfaces 402b and 403b, respectively, also in this case, it is possible to set the envelopes P while smoothly sliding the envelopes P. Still further, it is possible to set the envelopes P while smoothly sliding the envelopes P by setting the upstream end in the sheet feeding direction of the inclined surface 402b to be lower than the apex surface 306a of the crest portion 306, i.e., by forming such that the height of the apex portion 306a of the crest portion 306 is positioned within a range of height of the inclined surface 402b of the downstream swinging plate 402.
While the first and second embodiments of the present invention have described, the present invention is not limited to the above-mentioned embodiments. The effects described in the embodiment of the present invention are merely enumeration of the most preferable effects brought about from the present invention, and the effects of the present invention are not limited to those described in the embodiments of the present invention.
For example, while the swinging stacking portion 300 is used as an attachment removably attached to the storage box 202 in the first embodiment, the present invention is not limited to such a configuration. The swinging stacking portion 300 may be integrated with the tray 209, and the same effects may be brought about even if the sheet feed unit has the storage box in which the swinging stacking portion is integrated with the tray.
Still further, while the first embodiment has described by attaching the swinging stacking portion 300 to the storage box 202 of the sheet feed unit 200, the present invention is not limited to such configuration. For example, the swinging stacking portion 300 may be attached to the body-side sheet feed portion 10 of the printer body 101, and what in which the sheet stacking portion is integrated with the feed sheet cassette maybe used as the body-side sheet feed portion 10. In the same manner, the swinging stacking portion 300 maybe attached to the manual feed tray 21 of the manual feed portion 20 and what in which the sheet stacking portion is integrated with the manual feed tray may be used as the manual feed portion 20. The same effects are brought about even if the sheet stacking portion is used as described above.
Still further, while the first embodiment has been described by using the swinging stacking portion 300 having the two swinging plates of the downstream and upstream swinging plates 302 and 303, the number of the swinging plates is not limited to two, but may be one or three or more.
While the first embodiment has been also described by using the swing base that causes the downstream and upstream swinging plates 302 and 303 to swing by own weight of the sheets, the present invention is not limited to such a configuration. For instance, it is possible to swing the downstream and upstream swinging plates 302 and 303 by using a driving source such as a motor and a solenoid. In this case, the motor or the solenoid is driven corresponding to a stacking amount of the sheets to cause the downstream and upstream swinging plates 302 and 303 to swing such that the uppermost sheet follow the roller surface of the feeding roller.
Still further, while the first embodiment has been explained by using a configuration of lifting the tray 209 by the winding unit to make a sheet come into contact with the feeding roller 203, the present invention is not limited to such a configuration. For instance, the present invention is applicable to a sheet feed unit configured to make a sheet come into contact with the feeding roller by swinging the feeding roller.
Still further, while the first embodiment has been explained by using the electro-photographic type image forming apparatus, the present invention is noted limited to such a case. For example, the present invention is applicable to an ink-jet type image forming apparatus of forming an image on a sheet by discharging ink droplets from a nozzle.
Still further, while the downstream and upstream swinging plates 302 and 303 are configured to be rotably supported respectively by the swing shafts 308 and 309 of the swing base 301 in the first embodiment, the swing shafts may be fixed to the downstream and upstream swinging plates 302 and 303. That is, it is possible to configure such that the swing shafts rotate together with the downstream and upstream swinging plates 302 and 303, and the swing shafts are rotatably supported by the swing base 301.
While the crest portion 306 is disposed between the downstream and upstream swinging plates 302 and 303 in the first embodiment, the present invention is not limited to such a configuration. For example, the crest portion 306 may be disposed on the downstream side in the sheet feeding direction of the downstream swinging plate 302 or the upstream side in the sheet feeding direction of the upstream swinging plate 303. The crest portion 306 may be formed so as not have the apex surface 306a and may be formed so as to incline downward from apex lines which are lines in parallel with the swing shafts 308 and 309 for example. Still further, the crest portion 306 may be formed so as to be symmetrical in the width direction and may be any shape as long as it is formed into a shape of a crest inclined downward in the width direction from the apex portion.
Still further, the inclined surfaces 402b and 403b of the downstream and upstream swinging plates 302 and 303 described in the second embodiment is not limited to be a flat surface and may be a curved surface. The inclined surface may be configured from a shape in which a plurality of flat planes or curved planes are combined.
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. 2013-162894, filed on Aug. 6, 2013, and Japanese Patent Application No. 2014-038069, filed on Feb. 28, 2014, which are hereby incorporated by reference herein in their entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2013-162894 | Aug 2013 | JP | national |
| 2014-038069 | Feb 2014 | JP | national |
