Patent ID: 7712256

Claim:
An opening and closing apparatus comprising: a fixed body; an opening portion formed in said fixed body and having a peripheral edge; a movable body movable between a full-close position covering said opening portion and a full-open position not covering said opening portion, the movable body also movable to a first change position placed between the full-open position and full-close position, wherein the movable body includes a front side, a rear side, a top side, and a bottom side, the front side being the side of the movable body positioned closest to the peripheral edge and wherein the front side of the movable body and the peripheral edge contact each other when the movable body is in the full-close position; a detecting sensor, said detecting sensor having a sensor electrode provided on at least one end portion of the movable body, the at least one end portion positioned at the front side of the movable body, and wherein the detecting sensor outputs an electrostatic capacity detection signal in correspondence to a change of an electrostatic capacity between said sensor electrode and a conductive foreign material moving close to the sensor electrode; a judging portion adapted to judge whether or not a foreign material exists between said movable body and the peripheral edge of said opening portion by comparing a threshold value with a detection value determined from the electrostatic capacity detection signal; a position detecting portion adapted to output a position detection signal corresponding to a position of said movable body; a threshold value change portion adapted to begin to change said threshold value on the basis of said position detection signal when the signal indicates that said movable body is positioned at the first change position as said movable body is being moved towards the full-close position, wherein a change in the threshold value over time defines a change rate of the threshold value, and wherein said threshold value change portion alters the change rate when said movable body reaches the first change position as the movable body is being moved towards the full-close position.