SHEET FEEDING APPARATUS AND IMAGE FORMING APPARATUS

Abstract

Sheets fed out from a sheet feeding portion, which is brought into pressure contact with the sheets by the upward movement of a sheet stacking portion to feed out the sheets, are separated and conveyed one by one while being upwardly curved. During the sheet feeding operation, the sheet stacking portion is sequentially moved up, and when the sheet feeding operation is completed, the sheet stacking portion is moved down. Further, a remaining amount indicating member moved with the upward movement of the sheet stacking portion to indicate the remaining amount of sheets is held at a position before the sheet stacking portion is moved down, by a holding mechanism, when the sheet feeding operation is completed and the sheet stacking portion is moved down.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically illustrates the construction of an image forming apparatus provided with a sheet feeding apparatus according to an embodiment of the present invention.

FIG. 2 is a pictorial perspective view of the image forming apparatus.

FIG. 3 is a block diagram of the main body control portion of the image forming apparatus.

FIG. 4 is a front perspective view of a sheet feeding cassette provided in the sheet feeding apparatus.

FIG. 5 is a rear perspective view of the sheet feeding cassette.

FIG. 6 illustrates a construction for detecting the length of sheets stacked on the sheet feeding cassette.

FIG. 7 illustrates a construction for detecting the widthwise length of the sheets stacked on the sheet feeding cassette.

FIG. 8 is a first view illustrating a mechanism for pivotally moving a pressure lever provided in the sheet feeding cassette.

FIG. 9 is a second view illustrating the mechanism for pivotally moving the pressure lever provided in the sheet feeding cassette.

FIG. 10 is a first view illustrating the construction of a pressure drive unit provided on an image forming apparatus main body side.

FIG. 11 is a second view illustrating the construction of the pressure drive unit.

FIG. 12 is a third view illustrating the construction of the pressure drive unit.

FIG. 13 is a first view illustrating the operation of the pressure drive unit.

FIG. 14 is a second view illustrating the operation of the pressure drive unit.

FIG. 15 is a perspective view of a remaining amount indication holding mechanism provided in the sheet feeding cassette.

FIG. 16 shows a state in which the sheet feeding cassette of the remaining amount indication holding mechanism has been inserted into the apparatus main body.

FIG. 17 shows a state in which the cassette inner plate of the remaining amount indication holding mechanism has been lifted.

FIG. 18 shows a state in which the cassette inner plate of the remaining amount indication holding mechanism has been lowered.

FIG. 19 illustrates the construction of a cassette pulling-in mechanism provided in the sheet feeding apparatus.

FIG. 20 is a top plan view of the sheet feeding cassette.

FIG. 21 illustrates the operation of the cassette pulling-in mechanism.

FIG. 22 illustrates the state of the sheet feeding apparatus during sheet feeding.

FIG. 23 illustrates the state when the sheet feeding operation of the sheet feeding apparatus has been completed.

FIG. 24 illustrates the state when the sheet stacking plate of the sheet feeding apparatus has been lowered.

Claims

1. A sheet feeding apparatus comprising: a sheet containing portion having a sheet stacking portion movable up and down with sheets stacked thereon;a sheet feeding portion brought into pressure contact with the stacked sheets by an upward movement of the sheet stacking portion to feed out the sheets;a lifting and lowering mechanism configured to lift and lower the sheet stacking portion;a movable remaining amount indicating member configured to indicate the remaining amount of sheets according to a position of the sheet stacking portion; anda holding mechanism configured to hold the remaining amount indicating member at a position before the sheet stacking portion is lowered, when the sheet stacking portion is lowered.

2. A sheet feeding apparatus according to claim 1, wherein the holding mechanism is provided with an urging member for limiting a movement of the remaining amount indicating member by an urging force, and the urging force of the urging member is set to a magnitude at which the remaining amount indicating member can be moved in association with the upward movement of the sheet stacking portion when the sheet stacking portion is moved up.

3. A sheet feeding apparatus according to claim 2, wherein the holding mechanism is provided with a shaft for pivotally supporting the remaining amount indicating member, and a stopper portion provided on the shaft, and can hold the remaining amount indicating member by the urging member urging the remaining amount indicating member against the stopper portion.

4. A sheet feeding apparatus according to claim 3, wherein one end of the remaining amount indicating member is engaged with the sheet stacking portion and a pointer for indicating a remaining amount of sheets to an outside is provided at the other end of the remaining amount indicating member, and the pointer is moved according to the upward and downward movement of the sheet stacking portion to indicate the remaining amount of sheets.

5. A sheet feeding apparatus according to claim 2, wherein the urging force of the urging member is applied to the remaining amount indicating member in a state in which the sheet containing portion is mounted on the main body of the apparatus, and the sheet feeding apparatus comprises a releasing mechanism configured to release the urging force of the urging member when the sheet containing portion has been taken out of the apparatus main body.

6. A sheet feeding apparatus according to claim 5, wherein the holding mechanism is provided with a shaft for pivotally support the remaining amount indicating member, and a stopper portion provided on the shaft, and can hold the remaining amount indicating member by the urging member urging the remaining amount indicating member against the stopper portion, and the releasing mechanism has a remaining amount indicating cam slidably disposed on the shaft, and slidingly moves the remaining amount indicating cam so as to release the urging force of the urging member according to an operation of pulling out the sheet containing portion from the apparatus main body.

7. An image forming apparatus provided with an image forming portion for forming an image on a sheet fed out from a sheet feeding apparatus, the image forming apparatus comprising: a sheet containing portion having a sheet stacking portion movable up and down with sheets stacked thereon;a sheet feeding portion brought into pressure contact with the stacked sheets by the upward movement of the sheet stacking portion to feed out the sheets;a lifting and lowering mechanism configured to lift and lower the sheet stacking portion;a movable remaining amount indicating member configured to indicate the remaining amount of sheets according to a position of the sheet stacking portion; anda holding mechanism configured to hold the remaining amount indicating member at a position before the sheet stacking portion is lowered, when the sheet stacking portion is lowered.