Method and apparatus for detecting positions of light emitting elements

Abstract

A method and apparatus for detecting positions which can accurately detect the position of light emitting elements and improves the ease in operation are disclosed. Light emitting elements of a PLZT shutter array that are arranged in one dimension are lighted. A light receiving element transfer system makes a light receiving element or receiver scan along an imaging face of the PLZT shutter array by sampling analog data which has been taken in by the light receiving element so that a data series can be obtained. A minimal value of the data series is determined to be a threshold. Then by comparing the threshold and the data series sequentially from the beginning, the first place where the threshold is exceeded is detected. A maximum value within a searching range of one cycle from this first place is detected. The position of the maximum value is considered to be a beginning or first light emitting element position among the lighted light emitting elements. Subsequently each light emitting element is detected by detecting a maximum value within one cycle of searching range after a half cycle following the preceding light emitting element. Each detected maximum value position is considered to be a light emitting element position.