Patent ID: 7167248

Claim:
A reflection-type optical sensor for detecting an object, the sensor comprising: a light-emitting element having a central axis extending in a predetermined direction that extends substantially normal to a surface of an object to be detected and having a light-emitting portion that emits a detecting light onto the surface of the object, the detecting light traveling toward the surface of the object to define an irradiated region on the object; a light-receiving element having a central axis extending parallel with the central axis of the light-emitting element and having a light-receiving portion that receives a reflected light that has reflected off a detecting region on the object, the detecting region and the irradiated region overlapping at an overlapping region on the surface of the object, the irradiated region having a remaining irradiated region other than the overlapping region of the irradiated region, the detecting region having a remaining detecting region other than the overlapping region of the detecting region; and a restricting member having a restricting portion defining an opening that allows a part of the detecting light and a part of the reflected light to pass therethrough, the restricting portion restricting a size of the opening to reduce an area of the overlapping region on the surface of the object, the irradiated region corresponding to an area on the object that is projected by the detecting light through the opening, the detecting light reflected from the irradiated region having an overlapping light that is reflected from the overlapping region of the irradiated region and a remaining detecting light that is reflected from the remaining irradiated region, the light receiving portion receiving through the opening the overlapping light that is reflected from the overlapping region, and the restricting portion preventing the remaining detecting light from reaching the light receiving portion.