Position detecting device and electro-optical device

An electro-optical device comprising:

• a light guide plate that is configured to transmit therethrough light beams entering from a light incident face thereof and to emit the light beams from a light emitting face intersecting the light incident face;
• multiple light sources for position detection that are arranged along the light incident face and that discharge position detection light beams toward the light incident face;
• a photosensor that detects at least some of position detection light beams reflected by an object to be detected among the position detection light beams emitted from the light emitting face;
• a light source control unit that switches between a first driving mode and a second driving mode, the first driving mode being a mode in which discharged light intensities of the multiple light sources for position detection are gradually decreased toward one side of an arrangement direction of the multiple light sources for position detection and in which emitted light intensities of the position detection light beams emitted from the light emitting face exhibit a first light emission distribution tilted toward the one side of the arrangement direction, the second driving mode being a mode in which discharged light intensities of the multiple light sources for position detection are gradually decreased toward another side opposite the one side of the arrangement direction and in which emitted light intensities of the position detection light beams emitted from the light emitting face exhibit a second light emission distribution tilted toward the other side of the arrangement direction;
• a position information derivation unit that derives position information regarding the object to be detected along the arrangement direction on the basis of output components of the photosensor respectively attributable to the first light emission distribution and the second light emission distribution;
• and
• an electro-optical panel that has a display area arranged so as to overlap in plan view the light emitting face of the light guide plate.