Patent ID: 9255980
Filing Date: 2016-02-09
CPC Classification: G01S,G06F

Claim Text:
1. An optical position detection device comprising: a light source device adapted to emit detection light, and to vary emission intensity of the detection light from one side of a space where the detection light is emitted toward the other side when emitting the detection light; a light receiving section adapted to receive the detection light reflected in the space; and a position detection section adapted to detect a position of a target object in the space based on a detecting signal output from the light receiving section, wherein the light receiving section includes a first light receiving element having a light receiving surface pointed at the one side of the space and a second light receiving element having a light receiving surface pointed at the other side of the space at a position adjacent to the first light receiving element, an intersection angle between a normal direction with respect to the light receiving surface of the first light receiving element and a normal direction with respect to the light receiving surface of the second light receiving element is larger than 90° and smaller than 180°, the light source device reduces the emission intensity from the one side of the space toward the other side in a first period, and reduces the emission intensity from the other side of the space toward the one side in a second period having no overlap with the first period, the position detection section detects the position of the target object based on a drive current value in the light source device when a level of the detecting signal in the first period and a level of the detecting signal in the second period become equal to each other, the position detection section varies the drive current value in the first period and the drive current value in the second period based on a result of comparison between a level of the detecting signal in the first period and a level of the detecting signal in the second period when the light source device emits the detection light using a reference drive current value in the first period and the second period, and when the level of the detecting signal in the first period and the level of the detecting signal in the second period become equal to each other, the position of the target object is detected based on a comparison result between an adjustment amount of the drive current value in the first period from the reference drive current value and an adjustment amount of the drive current value in the second period from the reference drive current value.