Sheet feeding apparatus and image forming apparatus

摘要

A sheet feeding apparatus includes a stacking portion, a lifting portion, a feeding portion, and a control portion. The sheet feeding apparatus further includes a first height detecting portion configured to output a signal corresponding to a position in a height direction of the topmost sheet of sheets stacked on the stacking portion, a sheet presence detecting portion configured to output a signal corresponding to presence or absence of the sheets stacked on the stacking portion, and a second height detecting portion configured to output a signal corresponding to a position in a height direction of the stacking portion. The control portion performs control for sheet feeding operation using the signal from the sheet presence detecting portion if the position of the stacking portion is above a predetermined height based on the signal from the second height detecting portion and, if the position of the stacking portion is below the predetermined height, the control portion performs control for sheet feeding operation not using the sheet presence detecting portion.

主权项

1. A sheet feeding apparatus comprising:
a stacking portion on which sheets are stacked, the stacking portion being movable up and down; a lifting portion which lifts the stacking portion; a feeding portion which abuts against a topmost sheet of the sheets stacked on the stacking portion, and feeds the topmost sheet; a first height detecting portion which outputs a signal corresponding to a position in a height direction of the topmost sheet of the sheets stacked on the stacking portion; a sheet presence detecting portion which is disposed contactably with the topmost sheet of the sheets stacked on the stacking portion and outputs a signal corresponding to presence or absence of sheets stacked on the stacking portion; a second height detecting portion which outputs a signal corresponding to a position in a height direction of the stacking portion independent of the position of the topmost sheet in the height direction; and a control portion controlling the lifting portion to perform a lifting operation such that the position of the topmost sheet is kept within a predetermined range by lifting the stacking portion based on the signal from the first height detecting portion, wherein the control portion performs a predetermined control based on the signal from the sheet presence detection portion in a state in which the position of the stacking portion is detected to be above a predetermined height based on the signal from the second height detecting portion, and does not perform the predetermined control in a case in which the position of the stacking portion is detected to be below the predetermined height, in a state in which the stacking portion is positioned at a position such that the topmost sheet is positioned within the predetermined range.