1. Filed of the Invention
The present invention relates to a sheet-feeding mechanism used in image forming apparatuses such as a copying machine, a printer, and a facsimile machine. The present invention relates also to a sheet-feeding device and an image forming apparatus provided with the sheet-feeding mechanism.
2. Description of the Related Art
In conventional image forming apparatuses such as a copying machine and a printer, a sheet-feeding device is provided for feeding sheets which are subjected to image forming.
As shown in
Further, under the image forming section 130, there are provided a plurality of sheet-feeding devices 120 in a stacked state.
Each sheet-feeding device 120 includes a tray 125 for holding sheets, and a sheet-feeding mechanism 200, which is indicated by surrounding dotted lines in
Next,
Further, the pick-up roller 211 is accommodated in a housing 210, which is made of resin, together with a feeding roller 212 which will be described herebelow. The housing 210 is mounted on a housing upper surface, which is not illustrated, of the sheet-feeding device 120 through an elastic member 213, and rotated about a rotational axis of the feeding roller 212 downward in the drawing by a pressure exerted by the elastic member 213. This causes the pick-up roller 211 to come in contact with a surface of sheets held on the inclining tray 125.
Next, the retard roller 215 is provided on a side of the housing of the sheet-feeding device 120 so as to face the feeding roller 212 provided in the housing 210. The elastic member 217 exerts a biasing force to cause the retard roller 215 to move toward the surface of the feeding roller 212, so that the retard roller 215 is pressed against the feeding roller 212 at a predetermined nip pressure.
The feeding roller 212 is a roller which is constantly rotated by an unillustrated external drive source and causes the pick-up roller 211 to be rotated in a rotational direction which is the same as the rotational direction of the feeding roller 212, through an intermediate gear 214.
Further, the retard roller 215 normally rotates in the opposite direction with respect to the rotational direction of the feeding roller 212, and it rotates in a forward direction in accordance with a load exerted to an unillustrated torque limiter. Further, before a nip portion N formed by the feeding roller 212 and the retard roller 215, a part of a housing wall surface of the sheet-feeding device 120 is provided as a cover 216.
As shown in
The feeding roller 212 and the retard roller 215 are mechanisms for preventing multi-feeding of the sheets. In other words, as shown in
For example, when two stacked sheets 300a and 300b are conveyed to the nip portion N formed between the feeding roller 212 and the retard roller 215, the upper sheet 300a comes in contact with the surface of the feeding roller 212 rotating in a conveying direction and is sent to inside. On the other hand, rotation of the retard roller 215 in the opposite direction with respect to the rotational direction of the feeding roller 212 pushes back the lower sheet 300b toward the opposite direction with respect to the conveying direction of the sheet 300a indicated by an arrow in
When only the sheet 300a is fed by the pick-up roller 211, the feeding roller 212 and the retard roller 215 exert a force to the sheet in opposite directions. However, when a load which is greater than a predetermined amount of load is applied to the torque limiter, the retard roller 215 is rotated in the opposite direction, in other words, a direction of following the rotational direction of the feeding roller 212. Thus, the sheet 300a is sent toward the conveying direction of the arrow shown in
In the operation of the sheet-feeding mechanism 200, it is required that the feeding roller 212 assuredly separates the upper sheet 300a and the sheet 300b. In such technology as disclosed in Japanese Patent Unexamined Publication H11-59937 (hereinafter, referred to as “patent document 1”), as shown in
In the retard roller 450, fine irregularity is formed on the surface of the projecting portion 452 so that the friction coefficient of the surface of the projecting portion 452 is greater than that of the surface of the main body 451.
According to such configuration, the sheet to be conveyed is sandwiched between the belts 400 and the main body 451 of the retard roller 450, and the sheet to be pushed back comes in contact with the projecting portion 452 at the clearance between the belts 400, so that separability to separate the sheet to be conveyed to the image forming section 130 from other sheet is improved.
However, in the conventional sheet-feeding mechanism shown in
The projecting portion 452 as a part of the retard roller 450 is rotated in the opposite direction with respect to the conveying direction of the sheet, and the surface is in a rough state having irregularity. Therefore, it was likely that, when the sheet to be conveyed collides with the projecting portion 452, the end portion and the surface is damaged or deformed.
Further, the sheet is sandwiched between the belt 400 and the retard roller 450. The surface of the projecting portion 452 of the retard roller 450 is rough due to irregularity formed thereon and is rotated in such a state of being fitted between the belts 400. It was likely that the surface of the sheet is damaged when it comes in contact with the surface of the projecting portion 452, and as shown in
The present invention was made in view of the problems described above, and its object is to provide a sheet-feeding mechanism capable of improving separability with respect to other sheet without damaging sheets, and a sheet-feeding device and an image forming apparatus provided with the sheet-feeding mechanism.
For the purpose of achieving the object described above, a sheet-feeding mechanism according to an aspect of the present invention includes: a feeding roller which rotates in a sheet-conveying direction, at least a surface of the feeding roller being flexible; and a retard roller having a plurality of press-contact rollers which come in press-contact with the feeding roller at a predetermined pressure to form a plurality of press-contact surface, and a hardness of the feeding roller and a hardness of the retard roller are different from one another.
According to the configuration described above, a sheet-feeding mechanism capable of improving separability with respect to other sheets without damaging the sheet, and a sheet-feeding device and an image forming apparatus provided with the sheet-feeding mechanism can be provided.
These and other objects, features and advantages of the present invention will become apparent upon reading of the following detailed description along with the accompanied drawings.
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
In each of
The feeding roller 10 has a configuration which is similar to that of the feeding roller 212 of the conventional sheet-feeding mechanism 200 shown in
The retard roller 20 includes a pair of press-contact rollers 21 which come in contact with a surface of the contact member 12 of the feeding roller 10, a connecting shaft 22 for connecting the press-contact rollers 21, a rotational shaft 23 provided coaxially with the connecting shaft 22 and to which a rotational drive force is transmitted through an unillustrated torque limiter. Normally, a rotational drive force in a counter-clockwise direction (in
In the example shown in
In each of the drawings, sizes of parts of the rollers are shown in an exaggerated manner for easiness in description.
By setting overall sizes of the feeding roller 10 and the retard roller 20 to be the same as those of the conventional sheet-feeding mechanism 200, other configurations of the sheet-feeding mechanism which are the same as those shown in
In the configuration described above, the feeding roller 10 corresponds to the feeding roller of the present invention, and the retard roller 20 corresponds to the retard roller of the present invention. The feeding roller and the retard roller constitute the sheet-feeding mechanism of the present invention. Further, the press-contact rollers 21 correspond to the press-contact rollers of the present invention.
A basic operation of the sheet-feeding mechanism 1, which has the configuration described above, in accordance with the embodiment of the present invention is similar to that of the conventional sheet-feeding mechanism. Referring to
When only one sheet is sent to the feeding roller 10, a force in opposite directions is applied to the sheet by the feeding roller 10 and the retard roller 20. However, transmission of a rotational torque exerted to the retard roller 20 is shut off by a load which is greater than a predetermined amount applied to the retard roller 20, and then the retard roller 20 is rotated in a direction of following the rotation of the feeding roller 10 (the retard roller 20 rotates in a clockwise direction:
On the other hand, when two or more sheets in a stacked state are guided to a clearance defined between the feeding roller 10 and the retard roller 20, the uppermost sheet comes in contact with the surface of the feeding roller 10 rotating in the conveying direction and is sent to an inner side. On the other hand, the sheet on the lower side is pushed back to the direction opposite to the conveying direction of the sheet indicated by the arrow N in the drawing due to rotation of the retard gear 20 in the opposite direction with respect to the sheet-conveying direction (counter-clockwise direction in
The sheet-feeding mechanism 1 in accordance with the first embodiment of the present invention is so configured as to have the feeding roller 10 and the retard roller 20 having the plurality of press-contact rollers 21 as shown in
On the other hand, since an external force is not exerted to a portion of the contact member 12 between the press-contact surfaces 311, the portion is so deformed as to bulge toward the connecting shaft 22 to form the bulging portion 312. At borders between the bulging portion 312 and the press-contact surfaces 311, end portions of the press-contact rollers 21 are in press contact so that edge portions 313 are formed.
The sheets 310a and 310b are guided to a position between the feeding roller 10 and retard roller 20 and urged to come in press-contact by the bulging portion 312 and the pair of edge portions 313 on opposite sides thereof. Therefore, a cross-sectional shape of the sheets 310a and 310b viewed from the sheet-conveying direction becomes a wave-like shape. At this time, the sheet 310b in contact with the retard roller 20 is deformed along the bulging portion 312 and fitted between the press-contact surfaces 311, so that a retaining force is improved. On the other hand, the sheet 310a in contact with the feeding roller 10 is pressed toward the press-contact surfaces 311 including the edge portions 313, so that a contact with respect to the surface of the contact member 12 becomes stronger.
Thus, the sheet in contact with the feeding roller 10 and the sheet in contact with the retard roller 20 are strongly retained by the rollers respectively, so that effect of improving separability can be achieved.
Further, when three or more sheets are guided in a stacked state, separability may be improved in accordance with the following reasons.
In the configuration of the present embodiment, the bulging portion 312 and the pair of edge portions 313 cause the stacked sheets 310a-310e to come in press-contact. Therefore, a cross-sectional shape of the sheets 310a-310e viewed from the sheet-conveying direction has a wave-like shape along the shape formed by the bulging portion 312 and the edge portions 313. At this time, it is considered that the sheets 310a-310e are banded together and integrated by the pressure from the rollers and formation of the wave-like shape.
The banded sheets 310a-310e receive a force in opposite directions from the feeding roller 10 and the retard roller 20. The sheets 310b-310e, which are other than the sheet 310a in direct and close contact with the feeding roller 10, are separated from the sheet 310a and put back to the tray 126 similarly to the sheet 310b shown in
As described above, in the first embodiment, the sheets 310b-310d which should follow the rotation of the retard roller 20 are more likely to be integrally retained with respect to the sheet 310a which should follow the rotation of the feeding roller 10. Therefore, even when three or more sheets, while in a stacked state, are guided to a position between the rollers, favorable separability can be secured.
In the description above, the bulging portion 312 is shown in an exaggerated manner. However, if the sheet is deformed within about 1 mm with respect to the surfaces of the press-contact surfaces 311, the sheet can be deformed to have a suitable wave-like shape, so that the effect of improving separability as described above can be acquired.
Next,
As described above, according to the sheet-feeding mechanism in accordance with the present embodiment, separability can be improved while preventing the sheet from colliding with the retard roller to be damaged.
Further,
The sheet-feeding mechanism in accordance with the second embodiment has a feature that the guide member 40 is provided between the retard roller 20 and the press-contact roller 21. As shown in
Further, the guide member 40 achieves an effect of restricting the sheet-feeding direction of the sheet on a more rear side than the conventional cover 216.
Regarding the size of the guide member 40, when the feeding roller 10 and the retard roller 20 have sizes which are similar to those of the first embodiment, it is necessary that the guide member 40 has a width which can be accommodated within 4 mm (in other words, smaller than 4 mm) clearance of the pair of press-contact rollers 21. However, for the purpose of improving the effect of restricting the sheet-conveying direction, it is preferable that it has a wider width. For example, the contact member 12 of the feeding roller 10 has an outer diameter of 20 mm and an entire length of 24 mm, similarly to the first embodiment. On the other hand, the retard roller 20 includes a pair of press-contact rollers 21 each having an outer diameter of 20 mm and an entire length of 8 mm, and the press-contact rollers 21 are arranged with a clearance of 8 mm therebetween. Accordingly, the guide member 40 having a width of smaller than 8 mm can be used. Setting the entire length of each press-contact roller to be shorter than 8 mm is not so preferable since it may cause the effect of conveying and separating the sheet to be reduced.
In the configuration described above, the guide member 40 is a member which is separate from the cover 216. However, the guide member 40 may be molded integrally with the cover 216.
Further, in the description above, the retard roller 20 has a configuration in which the pair of press-contact rollers 21 are arranged symmetrically. However, the plurality of press-contact rollers according to the present invention may be three or more.
Further, in the configuration described above, the overall sizes of the feeding roller 10 and the retard roller 20 are the same. However, it may be so configured that the diameters are different from one another. Especially, making the diameter of the feeding roller 10 be larger than the diameter of the press-contact rollers 21 of the retard roller makes a possibility that the conveyed sheet comes in contact with the feeding roller 10 be higher, so that guiding to the press-contact portion can be made easier.
Further, in the configuration described above, the contact member 12 of the feeding roller 10 and the retard roller 20 are both made of rubber. However, as long as the feeding roller is made of material having elasticity, it is not limited to the rubber. Further, according to the configuration described above, the press-contact rollers 21 are made of rubber having a hardness which is higher than that of the contact member 12. However, it may be made of metal or resin. In other words, regarding the feeding roller and the retard roller according to the present invention, as long as areas sandwiched by the press-contact surface of the feeding roller are deformed due to a difference in a hardness between the press-contact rollers and the feeding roller, the feeding roller and the press-contact rollers are not limited by particular structure and material.
In each of the embodiments, the sheet-feeding mechanism 1 is mainly described. However, the present invention may be realized as a sheet-feeding device provided with the sheet-feeding mechanism according to the present invention. In this instance, pick-up roller 211 corresponds to the pick-up roller according to the present invention, and the tray 125 corresponds to the tray according to the present invention, and other structures such as the bottom surface 126 and the cover 216 correspond to the housing according to the present invention.
Further, in the image forming apparatus shown in
Hereinafter, a third embodiment according to the present invention will be described with reference to the drawings.
In
The feeding roller 10c includes a pair of press-contact rollers 11c, a connecting shaft 12c for connecting the press-contact rollers 11c, and a rotational shaft 13c provided coaxially with the connecting shaft 12c and to which a rotational drive force is transmitted from outside. The press-contact roller 11c are rollers which come in contact with the surface of the contact member 22c of the retard roller 20c, and is made of elastic material such as silicon rubber.
Further, the retard roller 20c includes a rotational shaft 21c to which a rotational drive force is transmitted from outside through an unillustrated torque limiter, a contact member 22c which is provided around the rotational shaft and comes in direct contact with the sheet, and a projecting portion 23c which is provided on an outer periphery of the contact member 22. As material of the contact member 22c, similarly to the press-contact roller 11c, an elastic member such as rubber is used. The press-contact rollers 11c and the contact member 22c may be made of the same kind of material.
Further, as shown in
Further, as material of the projecting portion 23c, polyoxymethylene (POM) material is used. The POM material has excellent rub resistance, and has a surface having a smoothness which is higher as compared to rubber material of the contact member 22c and the press-contact rollers 11c.
In the example shown in
By setting the overall sizes of the feeding roller 10c and the retard roller 20c to be the same as those of the conventional sheet-feeding mechanism 200, other configurations of the sheet-feeding mechanism may be the same as the parts shown in
Further, in the configuration described above, the feeding roller 10c corresponds to the feeding roller according to the present invention, and the retard roller 20c corresponds to the retard roller according to the present invention. The feeding roller 10c and the retard roller 20c constitute the sheet-feeding mechanism according to the present invention. Further, the press-contact rollers 11c correspond to the press-contact roller according to the present invention. Further, the contact member 22c corresponds to the press-contact portion according to the present invention, and the projecting portion 23c corresponds to the projecting portion according to the present invention.
A basic operation of the sheet-feeding mechanism 1 in accordance with the embodiment of the present invention having such configuration as described above is similar to the operation of the conventional sheet-feeding mechanism. Referring to
If only one sheet is sent to the feeding roller 10c, a force in opposite directions is applied to the sheet by the feeding roller 10c and the retard roller 20c. However, transmission of a rotational torque with respect to the retard roller 20c is shut down by a load greater than a predetermined amount applied to the torque limiter. Accordingly, the retard roller 20c is rotated in a direction of following the rotation of the feeding roller 10c (the retard roller 20c rotates in a clockwise direction:
On the other hand, when two or more sheets are guided to a clearance defined between the feeding roller 10c and the retard roller 20c in a stacked state, the uppermost sheet comes in contact with the surface of the feeding roller 10c rotating in the conveying direction and then is sent to inside. On the other hand, rotation of the retard roller 20c in the opposite direction with respect to the sheet-conveying direction (the retard roller 20c rotates in the counter-clockwise direction in
According to the basic operation described above, the sheet-feeding mechanism 1 in accordance with the third embodiment of the present invention has a configuration in which, as shown in
Further, into the area defined between the press-contact rollers 11c adjacent to each other, an outer peripheral portion of the projecting portion 23c projects, so that a main surface is formed which comes close to the feeding roller 10c more than the press-contact surfaces 311c do.
The press-contact surfaces 311c as nip portions formed by the pair of press-contact rollers 11c and the contact member 22c comes in press-contact with the sheets 310a and 310b guided between the feeding roller 10c and retard roller 20c. On the other hand, since the sheets 310a and 310b are pushed toward the feeding roller 10c along the shape of the main surface of the projecting portion 23c, a cross-sectional shape of the sheet viewed from the conveying direction is deformed to be a wave-like shape. At this time, the sheet 310b which comes in contact with the retard roller 20c is deformed along the projecting portion 23c and fitted between the press-contact rollers 11c. Accordingly, a retaining force applied by the retard roller 20c improves. On the other hand, the sheet 310a which comes in contact with the feeding roller 10c is pressed against the press-contact surfaces 311c including edge portions 312c of the press-contact rollers 11c. Accordingly, a contact with respect to the surface of the contact member 22c becomes stronger.
Thus, the sheet in contact with the feeding roller 10c and the sheet in contact with the retard roller 20c are strongly retained by respective rollers, so that the effect of improving separability can be achieved.
If three or more sheets are guided in stack, it is considered that separability may be improved on the following reasons.
In the configuration of the present embodiment, the projecting portion 23c and the pair of press-contact rollers 11c cause the stacked sheets 310a-310d to come in press-contact with each other. Accordingly, a cross-sectional shape of the sheets viewed from the sheet-conveying direction is deformed to be a wave-like shape along the shape formed by the projecting portion 23c and the edge portions 312c of the press-contact rollers 11c. At this time, it is considered that the sheets 310a-310d are banded and integrated by pressure from the rollers and deformation into a wave-like shape.
The banded sheets 310a-310d receive from the feeding roller 10c and the retard roller 20c a force in opposite directions. The sheets 310b-310d, which are other than the sheet 310a in close contact with the press-contact rollers 11c of the feeding roller 10c, are separated from the sheet 310a and put back to the tray 126 while retaining the state of being banded by the deformation, similarly to the case of the sheet 301b shown in
In other words, as shown in
As described above, in the present embodiment, the sheets 310b-310d which should follow the rotation of the retard roller 20c are more likely to be integrally retained with respect to the sheet 310a which should follow the rotation of the feeding roller 10c. Therefore, even when three or more sheets, while in a stacked state, are guided to a position between the rollers, favorable separability can be secured.
In the description above with reference to
Next,
However, the projecting portion 23c of the retard roller 20c in accordance with the present embodiment is made of POM material having more excellent smoothness as compared to the press-contact rollers 11c or the like, and surface machining such as irregularity is not applied unlike the technology disclosed in the patent document 1. Thus, even if the end portion of the sheet comes in contact at the angle of the conveying direction C, the sheet is conveyed around the surface of the projecting portion 23c and guided along the outer side of the rotating retard roller to the nip portion N.
Further, since the surface of the projecting portion 23c is smooth, even in a state where the sheet is fitted between the feeding roller 10c and the retard roller 20c, a contact with the projecting portion 23c makes it possible to reduce a possibility of causing a damage on the surface of the sheet.
As described above, according to the sheet-feeding mechanism of the present embodiment, separability can be improved while preventing damage on the sheet due to collision with the retard roller 20c.
In the description above, the pair of press-contact rollers 11c as the feeding roller 10c are arranged symmetrically, and the projecting portion 23c of the retard roller 20c is provided therebetween. However, a configuration of the press-contact roller and the projecting portion in accordance with the present invention is not limited to the example shown in
Further, in the description above, the projecting portion 23c of the retard roller 20c is formed coaxially with the contact member 22c and having a cylindrical shape. However, the projecting portion 23 may have a configuration in which the edge portions to come in contact with the surface of the sheet is taken off as shown in
Further, in the description above, the feeding roller 10c includes the plurality of press-contact rollers 11c, and the projection 23c is provided on the retard roller 20c. However, according to the present invention, the retard roller may include a plurality of press-contact rollers, and the projecting portion may be provided on the feeding roller.
In
The configuration above corresponds to a configuration in which configurations of the feeding roller 10c and the retard rollers 20c shown in
Especially in this configuration, as shown in
Further, in the configuration above, the press-contact rollers 11c of the feeding roller 10c and the contact member 22c of the retard roller 20c are made of the same kind of material (rubber). However, it may be the different kinds of material.
Further, the projecting portions 23c and 53 are made of POM material. However, as long as the smoothness is higher than the surfaces of the contact member 22c and the press-contact roller 11c, materials such as polyethylene (PE), polycarbonate (PC), polypropylene (PP), nylon 6, and ABS, or metal material such as stainless steel (SUS) may be used, and it is not limited by particular composition.
Further, in each of the embodiments above, the sheet-feeding mechanism 1 is mainly described. However, the present invention may be realized as a sheet-feeding device provided with the sheet-feeding mechanism in accordance with the present invention. At this time, the pick-up roller 211 corresponds to the pick-up roller of the present invention, and the tray 125 corresponds to the tray according to the present invention, and other structures such as the bottom surface 126, the cover 216, and the like correspond to the housing according to the present invention.
Further, in the image forming apparatus shown in
The present invention achieves an effect of improving separability of sheets from one another without damaging the sheet, and it is useful in the sheet-feeding mechanism, and the sheet-feeding device and the image forming apparatus provided with the sheet-feeding mechanism.
The following is a summary of the aforementioned description:
A-1:
The sheet-feeding mechanism in accordance with the first and second embodiments of the present invention includes: a feeding roller which rotates in a sheet-conveying direction, at least a surface of the feeding roller being flexible; and a retard roller having a plurality of press-contact rollers which come in press-contact with the feeding roller at a predetermined pressure to form a plurality of press-contact surface, and a hardness of the feeding roller and a hardness of the retard roller are different from one another.
According to the configuration described above, a sheet-feeding mechanism capable of improving separability with respect to other sheets without damaging the sheet, and a sheet-feeding device and an image forming apparatus provided with the sheet-feeding mechanism can be provided.
A-2:
It is preferable that a portion of the feeding roller corresponding to an axial clearance between the first press-contact roller and the second press-contact roller, which are adjacent to each other, is so deformed as to bulge toward an axis of the retard roller due to a difference in the hardness between the feeding roller and the press-contact roller.
A-3:
It is preferable that a hardness of the feeding roller is smaller than a hardness of the retard roller.
A-4:
It is preferable that the axial clearance faces an axially mid portion of the feeding roller.
A-5:
It is preferable that the sheet-feeding mechanism further includes: a guide member which is so provided as to extend from the sheet-conveying side toward the axial clearance, the guide member being adapted for guiding a sheet to the press-contact surface.
A-6:
A cover portion may be further provided on the sheet-conveying side of the retard roller, and the guide member can be provided as a separate member to the cover portion.
A-7:
A cover portion may be further provided on the sheet-conveying side of the retard roller, and the guide member can be formed integrally with the cover portion.
A-8:
It is preferable that an outer diameter of the feeding roller is substantially equal to an outer diameter of the press-contact roller of the retard roller.
A-9:
It is preferable that the feeding roller is supported by a first shaft, and the retard roller is supported by a second shaft, and when the plurality of press-contact rollers and the feeding roller are in contact with each other, a space is defined between the first shaft and the second shaft in a view from the sheet conveying direction, and the guide member extends into the space.
A-10:
Further, it is preferable that the sheet-feeding mechanism further includes: a first elastic member for urging the feeding roller toward the retard roller; and a second elastic member for urging the retard roller toward the feeding roller, and a sum of biasing force applied by the first elastic member and the second elastic member to cause the feeding roller and the retard roller to come in press-contact with each other is so set as to cause an axially mid portion of the first shaft of the feeding roller to bulge toward the second shaft more greatly than the contact portion with respect to the retard roller.
A-11
Further, the present invention includes a sheet-feeding device including: a housing; a tray for holding sheets; a sheet-feeding mechanism defined in any of the items A1-A10 defined above; and a pick-up roller for conveying sheets held on the tray to the sheet-feeding mechanism.
A-12
Further, the present invention includes an image forming apparatus including: the sheet-feeding device according to the present invention defined in the item A11 above; an image forming section for forming an image onto a sheet conveyed from the sheet-feeding mechanism of the sheet-feeding device; and an image fixing section for fixing the image formed on the sheet.
B-1
The sheet-feeding mechanism in accordance with the third embodiment of the present invention includes: a feeding roller which rotates in a sheet-conveying direction; and a retard roller which domes in press-contact with the feeding roller at a predetermined pressure, and any one of the feeding roller and the retard roller has a plurality of press-contact rollers which are arranged along on a common rotational axis at a predetermined interval, and the feeding roller or the retard roller having no press-contact roller includes a press-contact portion which comes in press-contact with the plurality of press-contact rollers directly and a projecting portion having a diameter larger than that of the press-contact portion and positioned between the plurality of press-contact rollers, and a surface of the projecting portion has a smoothness which is higher than that of the surface of the press-contact portion.
B-2:
Further, in the configuration above, the feeding roller may include the plurality of press-contact rollers, and the retard roller may be provided with the press-contact portion and the projecting portion.
B-3
Further, in the configuration of the item B-2, the feeding roller may include the pair of press-contact rollers, and the projecting portion of the retard roller may be positioned at an axial mid portion of the retard roller.
B-4:
Further, in the sheet-feeding mechanism mentioned in the item B-1, the retard roller may include the plurality of press-contact rollers, and the feeding roller may include the pressed contact portion and the projecting portion.
B-5
A sheet-feeding device can be provided which includes: a housing; a tray for holding sheets; the sheet-feeding mechanism (third embodiment) of the present invention mentioned in any of the items B1-B4; and a pickup roller for conveying sheets held on the tray to the sheet-feeding mechanism.
B-6
Further, an image forming apparatus can be provided which includes: the sheet-feeding device defined in the item B5; an image forming section for forming an image onto a sheet conveyed from the sheet-feeding mechanism of the sheet-feeding device; and an image fixing section for fixing the image formed on the sheet.
According to the configuration described above, a sheet-feeding mechanism capable of improving separability with respect to other sheets without damaging the sheet, and a sheet-feeding device and an image forming apparatus provided with the sheet-feeding mechanism.
The present invention achieves an effect of improving separability of sheets from one another without damaging the sheet, and it is useful in the sheet-feeding mechanism, and the sheet-feeding device and the image forming apparatus provided with the sheet-feeding mechanism.
This application is based on Japanese Patent Application Serial No. 2007-183367 and Serial No. 2007-183548 filed in Japan Patent Office both on Jul. 12, 2007, the contents of which are hereby incorporated by reference.
Although the present invention has been fully described by way of example with reference to the accompanying drawings, it is to be understood that various changes and modifications will be apparent to those skilled in the art. Therefore, unless otherwise such changes and modifications depart from the scope of the present invention hereinafter defined, they should be construed as being included therein.
Number | Date | Country | Kind |
---|---|---|---|
2007-183367 | Jul 2007 | JP | national |
2007-183548 | Jul 2007 | JP | national |
Number | Name | Date | Kind |
---|---|---|---|
4387889 | Koyama et al. | Jun 1983 | A |
4451027 | Alper | May 1984 | A |
4801134 | Yokoyama et al. | Jan 1989 | A |
4974680 | Nishida et al. | Dec 1990 | A |
5435540 | Martin et al. | Jul 1995 | A |
5558322 | Nakatomi | Sep 1996 | A |
6059280 | Yamauchi et al. | May 2000 | A |
6099179 | Higashi et al. | Aug 2000 | A |
RE38212 | Westcott et al. | Aug 2003 | E |
6942210 | Kawasumi | Sep 2005 | B2 |
20060103709 | Burdenko et al. | May 2006 | A1 |
20090212494 | Maeyama | Aug 2009 | A1 |
Number | Date | Country |
---|---|---|
58167337 | Oct 1983 | JP |
11-59937 | Mar 1999 | JP |
2000302305 | Oct 2000 | JP |
2002114421 | Apr 2002 | JP |
2003341630 | Dec 2003 | JP |
2009280355 | Dec 2009 | JP |
Number | Date | Country | |
---|---|---|---|
20090014945 A1 | Jan 2009 | US |