Sheet feeding or delivering – Feeding – Separators
Reexamination Certificate
1999-08-10
2001-09-04
Ellis, Christopher P. (Department: 3651)
Sheet feeding or delivering
Feeding
Separators
C271S121000, C271S127000
Reexamination Certificate
active
06283468
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
The invention relates to a sheet feeding device for an image forming apparatus, and specifically relates to a sheet feeding device being capable of preventing overlapped feeding.
2. Description of Related Art
A sheet feeding device for feeding a sheet of printing medium, such as paper, into the inside of electronic apparatuses, is provided for electronic apparatuses having an image forming apparatus, such as a printer, a copier, or a facsimile device. In the feeding device, there has been known a feeding device provided with a frictional separating device for separating sheets of paper or the like, one at a time to feed the paper from a paper supplying roller. A separating piece then separates the sheets of paper one at a time through contact with the supplying roller.
The paper, which is fed one at a time by the frictional separating device, is fed in the paper transferring direction by the rotation of the supplying roller with a fixed pressure received from the sheet supplying roller and the separation piece. The paper is transferred to the inside of the electronic apparatus by the transferring roller provided in the lower stream side of the paper transferring direction. In the sheet feeding device of this structure, because of the back tension generated between the paper supplying roller and the transferring roller in supplying paper, paper is fed to the transferring roller side more than a predetermined transferring amount at the moment that the rear end of the paper is released from being held by the supplying roller and the separation piece. This back tension causes deterioration of the accuracy of transferring paper.
Therefore, the above-described deterioration of the accuracy of transferring paper is prevented by decreasing the pressure generated between the paper supplying roller and the separation piece, thereby decreasing the back tension between the paper supplying roller and the transferring roller.
However, by decreasing the pressure generated between the paper supplying roller and the separation piece, a great amount of paper may easily enter between the paper supplying roller and the separation piece and cause overlapped feeding, wherein a plurality of papers are unnecessarily transferred into the inside of the electronic apparatuses with the paper that is to be fed.
SUMMARY OF THE INVENTION
One aspect of the invention is to provide a sheet feeding device for selectively switching the pressure generated between the paper supplying roller and the separation piece with a simple structure, and thereby being capable of preventing overlapped feeding of paper by increasing the pressure in separating sheets of paper, and also being capable of preventing the deterioration of the accuracy of paper transfer by decreasing the pressure to decrease the back tension between the paper supplying roller and the transferring roller in transferring paper with the transferring roller.
Another aspect of the invention is to provide a sheet feeding device being capable of preventing overlapped feeding of paper that can be caused by decreasing the pressure in transferring the paper with the transferring roller.
To achieve the above-described aspect, the sheet feeding device of the invention may comprise a paper supporting part for storing a plurality of paper and being capable of positioning movably between a first position and a second position, a paper supplying roller provided in a lower side of the paper supporting part for supplying a paper in a predetermined direction, a separation piece for separating the stored papers one at a time with the paper supplying roller, an urging device for urging or pressing the separation piece toward the paper supplying roller, a switch for switching the urging force from the urging device between a first urging condition and a second urging condition that has a larger urging force than the first urging condition.
The urging device may comprise a first urging part for urging the separation piece with a predetermined urging force toward the paper supplying roller and a second urging part that is different from the first urging part. The switch may comprise a second urging part switch for switching the position of the second urging part from a position being cooperative with the first urging part, to a position being non-cooperative with the first urging part, so that the separation piece is urged only by an urging force of the first urging part in the first urging condition, and urged by an urging force of both the first urging part and the second urging part in the second urging condition.
In the structure, because the urging device may comprise two urging parts including the first urging part and the second urging part, the urging force for urging the separation part is switched between a large urging force and a small urging force by switching between a first urging condition using only the first urging part, and a second urging condition using both the first urging part and the second urging part.
The switching of the urging condition is operated in a condition that the first urging part can be always urged toward the paper supplying roller with a predetermined urging force and the switching of the urging condition is operated by only the movement of the second urging part by the second urging part switch. For example, when the paper is separated one at a time by the separation piece, the second urging part switch moves the second urging part in a position to be cooperative with the first urging part, and when the paper is transferred after the separation of the paper by the separation piece, the second urging part switch switches the second urging part to a position of being non-cooperative with the first urging part. Thus, the urging force for urging the separation piece toward the paper supplying roller is switched between the paper separating operation and the paper transferring operation. Therefore, the paper separating operation and the paper transferring operation can be carried out easily and accurately.
To achieve the above-described aspect, another sheet feeding device of the invention may comprise a paper supplying roller rotatable around a first axis for supplying paper in a predetermined direction, a separation piece for separating sheets of paper one at a time by contacting the paper supplying roller, an urging part for urging the separation piece toward the paper supplying roller, a separation piece moving away part for moving the separation piece away from the paper supplying roller against an urging force of the urging part, a second axis extended parallel to the first axis, and a pair of paper feeding back levers rotatable around the second axis in a vicinity of the separation piece, wherein after the rotation of the paper supplying roller stops by stopping an operation of the first axis, an operation of the second axis starts, and thereby the paper feeding back lever is rotated toward an upper stream side of the paper transferring direction so as to move the separation piece away from the paper supplying roller via the separation piece moving away part and the paper is fed back to the upper stream side of the paper transferring direction.
In the structure, during the separation of the separation piece and the paper supplying roller, the paper held between the separation piece and the paper supplying roller is fed back to the upper stream side of the paper transferring direction by the rotation of the paper feeding back lever. Thereby, the paper held between the separation piece and the paper supplying roller can be fed back to the upper stream side of the paper transferring direction without causing any burden on the paper.
Because the paper held by the separation piece and the paper supplying roller is removed, the sheets of paper are not piled between the separation piece and the paper supplying roller, and therefore, overlapped feeding can be well prevented. Because it is not necessary to increase the pressure power between the separation piece and the paper supplying rol
Bower Kenneth W
Brother Kogyo Kabushiki Kaisha
Ellis Christopher P.
Oliff & Berridg,e PLC
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