Sheet Feed Cassette Monitor That Highly Accurately Detects Open/Close State of Sheet Feed Cassette and Presence/Absence State of Paper Sheet, Image Forming Apparatus, and Sheet Feed Cassette Monitoring Method

摘要

A sheet feed cassette monitor includes an actuator with another end portion, a detecting circuit, a plurality of protrusions, a signal monitoring circuit, and a signal determining circuit. When the one end portion is in contact with a paper sheet, the other end portion swings in a first direction. When the one end portion is not in contact with the paper sheet, the other end portion swings in a second direction opposite direction to the first direction. The detecting circuit detects the swinging of the other end portion on the actuator. The plurality of protrusions are convexly installed in an asymmetric manner with respect to a putting-in/taking-out direction of the feed cassette. The signal determining circuit determines a presence/absence state of the paper sheet housed in the sheet feed cassette and an open/close state of the sheet feed cassette based on a pattern of change in the monitored signal.