| 摘要 |
PURPOSE:To decrease the number of parts, by attaching the first scale, on which patterns having an equal interval to one of two spindles, and attaching the second scale, which can obtain pulse signals used for addition and subtraction, to the other spindle. CONSTITUTION:First and second scales 14 and 15 are attached to first and second spindles 12 and 13, which are relatively moved with respect to a detector 11. Bright and dark patterns, which are continued at an equal interval, are applied on the scale 14. Bright and dark patterns A having an equal interval and bright and dark patterns B, which are deviated by a 1/4 pitch with respect to the patterns A and have an equal interval, are provided on the scale 15. The light beams, which are passed through the patterns A and B from a light emitting element 16, are converted into electric signals (a) and (b) by light receiving elements 17 and 18. The signals (a) and (b) are inputted to a counter 5 through an adding and subtracting discriminator 3. The relative moving distance of the scales 14 and 15 is computed and displayed on a display device 8. Thus one detector and one adding and subtracting discriminator can be omitted. |
