SHORT DISTANCE VISUAL ACUITY TESTER

摘要

PURPOSE: A short distance visual acuity tester is provided to control automatically an angle of a reflective mirror according to the height of eyes of a testee without a high priced PSD(Position Sensitive Detector) sensor. CONSTITUTION: An infrared generation portion is installed at the same height as eyes of a testee in order to generate infrared rays. A knob(36) has a predetermined hole(34) to receive light. An infrared reception portion(32) is mounted in the inside of the knob(36) and located at an end portion of the hole(34). A predetermined hole(34) is formed in the knob(36). A motor(38) is used for driving and rotating the knob(36). A half mirror driving portion converts a rotary movement of the motor(38) to a rectilinear movement. The half mirror driving portion includes a screw(40) and a screw nut(42). The first bevel gear(44) is installed at a predetermined position of the screw(40). The second bevel gear(48) is connected to the first bevel gear(44) by a shaft(46).