| 摘要 |
PURPOSE:To simplify the constitution of the device by using a scale disc and the photosensor array having light-receiving elements arranged at an equal-angle pitch on the circumference. CONSTITUTION:The light from a light source 6 irradiates an equal-angle-pitch scale 2 on the disc 1 through a diffusing plate 5 and an image of the scale 2 is formed on the circular photosensor array 3 through the intermediary of a projection lens 4. The difference between the number of the light-receiving elements of the sensor array 3 and the total number of the bright-and-dark divisions of the equal-angle scale 2 is + or -2. The output of the sensor array 3 driven by a drive circuit 31 is given to a microprocessor (MP) 37 through a sample hold circuit 32 and a comparator 33. On the other hand, the output of the drive circuit 31 is inputted in a clock switching circuit 34 and counters 35 and 36, the content thereof is read out at proper timing by MP 37, the intermediate position of two variation signals of H and L of the output of the comparator 33 is operated and memorized, and based on this, the entire rotational angle is computed and indicated 38. Thus, the constitution is simplified. |
