| 摘要 |
PURPOSE:To prevent the disturbance of a speed signal due to the disturbance of an electric pulse accompanied by vibration, by suppressing conversion output response when the length of the gap between a slit plate and a light receiving element changes so as to exceed a predetermined range. CONSTITUTION:The value of the gap length (g) between a slit disc and a light receiving element accompanied by the vibration of an encoder 10 is converted to the magnitude of inductance corresponding to said value by a gap sensor 9 and said magnitude is converted to a gap length signal of voltage having the magnitude corresponding thereto by a converter 19. A level judge circuit 20 compares said signal with the upper and lower limit value signals of the gap length (g) and, when the gap length (g) is within a tolerant range, the movable contact 21a of a change-over switch 21 is connected to a fixed contact 21b and, when said gap length (g) exceeds the tolerant range, the contact 21a is connected to a fixed contact 21c. The contact 21b outputs the speed signal outputted from a converter 14 as a speed feedback signal as it is and the contact 21c outputs the same as the speed feedback signal through a filter circuit 22. By this method, a speed signal not disturbing speed control can be outputted. |
