SHORT-DISTANCE VISUAL ACUITY TESTER AND ALIGNING METHOD OF ITS ORIGIN POINT

摘要

PURPOSE: A short-distance visual acuity tester and an aligning method of its origin point are provided to achieve improved reliability of initial operation of the tester, while allowing the origin to be adjusted in a convenient manner. CONSTITUTION: A short-distance visual acuity tester comprises a visual acuity testing chart(62) operating by a first stepping motor(61); one or more masks(63) operating by a second stepping motor, and which permits only a predetermined part of the visual acuity testing chart to be shown; a position sensor(64) for detecting the absolute position of the chart or mask when a power is applied; a control unit(66) for controlling detection operation of the movement of the chart or mask, and the absolute position detection operation of the position sensor; and a memory(67) for storing origin adjustment data related to driving signals of first and second stepping motors for moving the chart and mask to their original positions when a power is applied.