| 摘要 |
PURPOSE:To make a linear scale unnecessary, by a method wherein the recessed and projected surfaces of a stator are detected by two sets of detectors, which are fixed in the moving direction of a movable piece with a predetermined space, to detect the moving direction and the moving amount of the movable piece. CONSTITUTION:Light emitting devices 3a, 3b and photo detectors 4a, 4b of respective optical systems are fixed to a movable piece 1 so that the space between intermediate points is (2+1/4) times with respect to the pitch between recess and projection in a stator 2. Signals, outputted by respective photo detectors 4a, 4b, are inputted into a signal separating circuit 6. The signal separating circuit 6 determines a line to output the signal thereof based on whether the relative phase of two signals, inputted simultaneously, is 90 deg. or 270 deg.. Pulses, outputted from two lines of the signal separating circuit 6 in proportion to the moving amount of a movable piece 1, are counted by an incremented and decremented counter 7 whereby the position of the movable piece 1 may be detected. |
