| 摘要 |
PURPOSE:To attain high precision of position and a high-quality speed signal without using any expensive interrupter, by arranging plural photodetectors so that phase differences are equal. CONSTITUTION:A light emitting element and a photodetector are arranged in a position 3 of interrupters (light shielding plates having lattice-shaped patterns) 1 and 2, and the quantity of light transmitted through two interrupters 1 and 2 is detected to obtain a position signal. This position signal is counted to obtain the extent of movement of a moving mechanism part 4 to which one interrupter 2 is attached. Plural pairs, for example, two pairs of interrupters 1 and 2 are so arranged that phase differences are equal to each other. Position signals A--B are obtained from detection signals A and B (the signal B has the phase shifted by 90 deg.) from two pairs of interrupters and signals obtained by inverting phases of these signals in inverting amplifiers 8 and 9. Switches 14-17 are opened and closed by signals (b), (c), (e), and (f) obtained by passing these position signals through comparators 10-13, and a position signal equal to the signal obtained by interrupters having 1/4 lattice intervals is obtained in an output terminal 18. |
