| 摘要 |
<p>PROBLEM TO BE SOLVED: To improve a detection resolution, to reduce useless space, to perform miniaturization and to improve position detection accuracy by using a lens for parallelizing a visual field angle and a prism for folding back an optical path and arranging a linear image sensor on the back side of a coordinate read surface. SOLUTION: A light source 101 is arranged on one side of the coordinate read surface so as to irradiate the finger of an operator from the back. The prism 141 is placed on the side opposing the side where the light source 101 is placed among the four sides of the coordinate read surface, reflects light from the light source 101 for two times and folds back the optical path. A convex lens 131 is arranged so as to converge the optical path folded back by the prism 141 to a pinhole 121. That is, at the time of viewing from the side of the linear image sensor 111 and the pinhole 121, the radially spread visual field angle is parallelized. It is desirable for earning an optical path length to arrange the linear image sensor 111 on the back side of the coordinate read surface and turn the surface of the photodetector to the prism 141.</p> |
