| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide an optical instrument that can improve position detection accuracy by preventing miscounting of pulses, in a case of performing position detection by measuring pulses generated according to a driving state of an optical member. <P>SOLUTION: An optical instrument comprises: an encoder for generating a plurality of pulses having different phases according to a driving state of an optical member; a two-phase counter 302 for counting the pulses; single-phase counters 304, 318 for counting the pulses of respective phases; and a mode determination section 300 which changes a mode to a first mode for counting the pulses of the respective phases by the single-phase counters 304, 318 when a driving speed of the optical member detected by using any of the plurality of pulses exceeds a threshold value, and changes the mode to a second mode for counting the plurality of pulses by the two-phase counter 302 when the driving speed of the optical member is the threshold value or less. The optical member is driven and controlled based on a position detection signal obtained from outputs from the single-phase counters 304, 318 in the first mode and a position detection signal obtained from an output from the two-phase counter 302 in the second mode. <P>COPYRIGHT: (C)2013,JPO&INPIT</p> |
