Patent ID: 7144112

Claim:
An optometric apparatus for subjectively examining visual functions of an eye of an examinee, the apparatus including: a rotary prism disposed in front of the eye, for adding prism power to the eye; rotation means including a pulse motor and a rotation transmitting mechanism for transmitting rotation of the pulse motor to the rotary prism, the rotation means being adapted for rotating the rotary prism to change the prism power to be added to the eye; the rotation transmitting mechanism including a gear mechanism having a predetermined speed reducing ratio, which transmits the rotation of the pulse motor to the rotary prism while reducing a rotation speed of the pulse motor so as to reduce a rotation step angle of the rotary prism with respect to a rotation step angle of the pulse motor so that a change step of the prism power is 0.05 prism diopter or less to make the prism power to be added to the eye appear to smoothly change, and command means for generating a command signal to start and stop the rotation of the rotary prism; and control means for driving the pulse motor to rotate at a speed of 5 to 100 pulses/sec. when the control means receives the rotation start command signal until when the control means receives the rotation stop command signal so that a change speed of the prism power is 0.1 to 1.0 prism diopter/sec. to make the prism power to be added to the eye appear to slowly change.