US Patent 9436318 Coordinate detecting apparatus, method of detecting coordinate, and electronic information board system

A coordinate detecting apparatus includes a light emitting element that is provided in a peripheral portion surrounding a surface of a display and emits a light in a direction parallel to the surface of the display; a light receiving element that is provided in the peripheral portion surrounding the surface of the display and receives the light emitted from the light emitting element; and a polarization unit that limits an oscillation direction of the light received by a light receiving surface of the light receiving element to a predetermined direction where only a real image is formed on the light receiving surface, wherein a coordinate of a touch position where an indicating unit touches the surface of the display is detected based on a light intensity distribution of the light received by the light receiving element.