Image forming apparatus

摘要

An image forming apparatus includes: a sheet storage portion having a sheet stacking portion, a sheet feed portion, a drive portion configured to be capable of switching a lifting speed when lifting the sheet stacking portion between a first lifting speed and a second lifting speed, a height detecting portion configured to be capable of detecting the fact that the sheet reaches a decelerating position for switching the lifting speed of the sheet stacking portion from the first lifting speed to the second lifting speed, a time counting portion, and a control unit. The control unit computes the sheet stacking amount of the sheet stacking portion by using a relationship among the lifting time from a start of the lifting operation of the sheet stacking portion until the sheet reaches a decelerating position, the first lifting speed, and a heightwise position of the decelerating position when the sheet stacked on the sheet stacking portion is lifted to the decelerating position at the first lifting speed by the drive portion and then is lifted to a feeding position at the second lifting speed.

主权项

1. An image forming apparatus comprising:
a sheet storage portion drawably mounted on an apparatus body and having a sheet stacking portion configured to stack sheets and to be movable upward and downward; a sheet feed portion provided above the sheet storage portion and configured to feed the sheets; a drive portion configured to lift the sheet stacking portion until the sheets stacked on the sheet stacking portion reach a feeding position allowing the sheet feed portion to feed the sheets and configured to switch a lifting speed when lifting the sheet stacking portion to the feeding position between a first lifting speed and a second lifting speed slower than the first lifting speed; a height detecting portion configured to detect the fact that the sheets reach a decelerating position where the lifting speed of the sheet stacking portion is switched from the first lifting speed to the second lifting speed during a period from a start of lifting of the sheet stacking portion until the sheets stacked on the sheet stacking portion reach the feeding position, the height detecting portion configured to detect the fact that the sheet stacked on the sheet stacking portion reaches the decelerating position and the feeding position; a time counting portion configured to count a lifting time of the sheet stacking portion; and a control unit configured to compute a sheet stacking amount of the sheet stacking portion by using the lifting time from the start of lifting of the sheet stacking portion until the sheets stacked on the sheet stacking portion reach the decelerating position counted by the time counting portion and the first lifting speed in a case that the sheets are lifted to the decelerating position by the drive portion at the first lifting speed and then are lifted to the feeding position at the second lifting speed, wherein the control unit computes the sheet stacking amount of the sheet stacking portion by using lifting time from a start of the lifting operation of the sheet stacking portion counted by the time counting portion until the sheet reaches the feeding position and the second lifting speed in a case that the lifting speed of the sheet stacking portion is set at the second lifting speed in response to the height detecting portion detecting the sheet stacked on the sheet stacking portion being positioned at the decelerating position before the lifting operation of the sheet stacking portion is started by the drive portion.