JPS6478110A - Semiconductor position detector for range finding - Google Patents

Abstract

PURPOSE:To discriminate the super-closest focusing distance or the infinity without deteriorating the position detecting capacity by forming a photodetecting area for detecting the super-closest focusing side, for generating a photovoltaic current to only one electrode of both electrodes, at the outside of one electrode. CONSTITUTION:A position detector has a photodetecting area 13 for range finding corresponding to an interlocking range of electrodes 11, 12 and a photographic lens, and also, a photodetecting area 14 for detecting the super-closest focusing side, for using the electrode 12 as a common electrode is formed. A spot of a reflected light from an object which exists in a super-closest focusing distance is made incident on the area 14, and photodetected thereby. In this case, a photovoltaic current all appears at the electrode 12 side, and does not appear at the electrode 11 side. Accordingly, it is known that the spot does not exist in the area 13 but exists in the area 14 (when the object exists in the infinity, the photovoltaic current does not appear in any electrode), and it can be known exactly that the object exists at the upper- closest focusing distance side. In this regard, since the area 14 is narrow, all of spots of the reflected light from the object cannot be photodetected, and become a loss by its portion, but since the reflected light at the time of the super-closest focusing distance is intense, this loss does not become a problem.