Patent ID: 7525536

Claim:
A coordinate input device that detects a position on an input surface indicated by indication means and determines coordinates of the position, comprising: a light-projecting section that emits light in planar directions along the input surface; a reflective section that reflects emitted light from said light-projecting section; a detector section that receives the reflected light from the reflective section, pixel by pixel, and detects the light intensity distribution of the reflected light; a coordinate calculating section that calculates coordinates of the position indicated by the indication means, based on the light intensity distribution detected by said detector section; and a determining section that determines an input state of the indication means with respect to the input surface, based on a temporal change in the light intensity distribution, wherein said determining section determines whether the input state of the indication means is a pen-up state or a pen-down state, based on a temporal change in a first light-shading amount obtained by adding together differences between a light intensity distribution formed when a light-shaded portion shaded from light by the indication means exists on the input surface and a light intensity distribution formed when no light-shaded portion exists on the input surface, in a direction along a sequence of pixels, or based on a temporal change in a first width as a pixel range within which the differences exceed a predetermined level.