A sheet feeding apparatus includes a sheet presence/absence detection sensor configured to detect presence or absence of a sheet on a stacking device, a sheet surface detection sensor configured to detect that a stacking tray is raised to enable a sheet to be fed, a separation cam, and a control unit. The control unit is configured to determine that the mounting state of a feeding holder to a holder support unit is defective when the sheet surface detection sensor detects that the sheet can be fed when the sheet presence/absence detection sensor detects absence of a sheet before sheet feeding processing by a pickup roller.

A feeding device includes a stacking member, a raising device, a feeding member, an interlocking device including a sheet contact portion, a switching device, a holding member, and a movement device. The feeding member is movable between contact and retracting positions, and rotates in contact with a sheet stacked on the stacking member in a state of being located at the contact position. The sheet contact portion contacts the stacked sheet, and moves by being pressed against the stacked sheet where the raising device raises the stacking member. The switching device switches the raising device between a permitted state and a regulated state. The movement device moves the feeding member to the retracting position above the contact position by moving the holding member. The raising device does not change from the regulated state to the permitted state when the movement device moves the feeding member to the retracting position.

A feeding device includes a stacking member, a raising device, a feeding member, an interlocking device including a sheet contact portion, a switching device, a holding member, and a movement device. The feeding member is movable between contact and retracting positions, and rotates in contact with a sheet stacked on the stacking member in a state of being located at the contact position. The sheet contact portion contacts the stacked sheet, and moves by being pressed against the stacked sheet where the raising device raises the stacking member. The switching device switches the raising device between a permitted state and a regulated state. The movement device moves the feeding member to the retracting position above the contact position by moving the holding member. The raising device does not change from the regulated state to the permitted state when the movement device moves the feeding member to the retracting position.

A detector includes a first member that makes contact with an upper surface of a paper sheet stored in a sheet feeding cassette, and a second member that supports the first member such that it is capable changing postures, while also movably supporting the first member in an up-and-down direction to coincide with the upper surface of a paper sheet stored in the sheet feeding cassette. The first member has a guide portion that makes contact with the sheet feeding cassette and/or a paper sheet stored in the sheet feeding cassette. The first member changes postures with respect to the second member as a result of the guide portion making contact with the sheet feeding cassette and/or a paper sheet stored in the sheet feeding cassette.

A detector includes a first member that makes contact with an upper surface of a paper sheet stored in a sheet feeding cassette, and a second member that supports the first member such that it is capable changing postures, while also movably supporting the first member in an up-and-down direction to coincide with the upper surface of a paper sheet stored in the sheet feeding cassette. The first member has a guide portion that makes contact with the sheet feeding cassette and/or a paper sheet stored in the sheet feeding cassette. The first member changes postures with respect to the second member as a result of the guide portion making contact with the sheet feeding cassette and/or a paper sheet stored in the sheet feeding cassette.

A holding member is configured to hold a feed member and movable up and down. A lever member is configured to pivot on a pivot shaft and includes a contact portion configured to be in contact with the holding member. An elastic member is connected to the lever member and configured to urge the holding member downward through the lever member. The elastic member is disposed such that, when viewed in an axial direction of the pivot shaft of the lever member, a distance from the pivot shaft to a line of action of a force applied by the elastic member to the lever member in a case where the feed member is located at a first position is shorter than a distance from the pivot shaft to the line of action in a case where the feed member is located at a second position below the first position.

A sheet member supply device (40) of an image forming apparatus (1) includes a sheet member stacking plate (43) in which sheet members (S) are stacked on the upper surface, a pickup roller (51) which makes contact with, from above, the uppermost layer of the sheet members (S) stacked on the sheet member stacking plate (43), a stacking plate displacement mechanism (44) which displaces the sheet member stacking plate (43) upward, a motive power transmission mechanism (60) which transmits motive power obtained from a drive source (45) to the stacking plate displacement mechanism (44) and a paradox planetary gear mechanism (65) which is provided in the motive power transmission mechanism (60). In this way, with a simple configuration, it is possible to reduce the unintentional downward displacement of the stacking plate.

A sheet feeding apparatus includes a sheet stacking portion, a lift plate, an actuating segment, driving unit, a sheet feeding portion, a first detecting portion, a remaining amount detection portion. The remaining amount detection portion includes a detection piece, a link mechanism, a second detecting portion, a controller. The link mechanism couples together the driving shaft and the detection piece at a coupling position attained by pivoting the lift plate through a predetermined angle from a lower limit position in rotation direction, so as to let the driving shaft and the detection piece rotate together. The second detecting portion senses whether or not the detection piece is present. The controller determines the remaining quantity level of the stacked sheets according to whether or not the second detecting portion is detecting the detection piece being present.

A sheet feeding apparatus includes a sheet stacking portion, a lift plate, an actuating segment, driving unit, a sheet feeding portion, a first detecting portion, a remaining amount detection portion. The remaining amount detection portion includes a detection piece, a link mechanism, a second detecting portion, a controller. The link mechanism couples together the driving shaft and the detection piece at a coupling position attained by pivoting the lift plate through a predetermined angle from a lower limit position in rotation direction, so as to let the driving shaft and the detection piece rotate together. The second detecting portion senses whether or not the detection piece is present. The controller determines the remaining quantity level of the stacked sheets according to whether or not the second detecting portion is detecting the detection piece being present.

A controller controls a floating unit and a conveyor to convey a sheet to a supply destination, and performs a following control of acquiring a detection value of a detector which detects an output signal acquired due to an input to a side of a sheet stack, during floating of sheets floated by the floating unit each time a sheet is conveyed by the conveyor and lifting a stacking tray upon the acquired detection value being less than a threshold value. The controller controls the floating unit and the conveyor to perform a feeding retry upon an occurrence of empty feeding in the conveyor, and determines the threshold value such that a target position for a height position of an upper surface of the sheet stack in the following control is a position where empty feeding is more likely to occur than multiple sheet feeding in the conveyor.