| 摘要 |
PURPOSE:To make it possible to always set a reference value in constant timing, by operating a reference position signal from each displacement signal corresponding to the relative displacement of main and auxiliary slit plates and a reference signal. CONSTITUTION:An encoder 4 consists of a main slit plate 4a, an auxiliary slit plate 4b, a light emitting part 4c and a light receiving part 4d and the plate 4a has a constant pitch grid 14a while the plate 4b has grids 14b, 24b each having the same pitch as the grid 14a. An encoder 5 has a main slit plate 5a and an auxiliary plate 5b and the plate 5a has a constant pitch grid 15a while the plate 5a has grids 15b, 25a each having the same pitch as the grid 15a. Further, a main reference slit grid 35a is formed to the plate 5b and an auxiliary reference grid 35b is to the plate 5b at a position superposed to the grid 35a at a reference position. A signal processing part 6 operates an angle value and high and low graduated angle reading values on the signals from the encoders 4, 5 while an operation result is applied to a display device 7. |
