| 摘要 |
<p>PURPOSE: To detect the interception of a radiant light beam independently of the state of peripheral light by providing a circuit element which modulates a reference signal and coherent radiant light and demodulates the output signal of a coherent detector by the same reference signal. CONSTITUTION: When X and Y correlation signals 84 and 86 are lower than reference levels of comparators 88 and 90, binary counted values corresponding to specific X and Y light emitting elements which radiate the beams intercepted by a stylus 12 are outputted. Binary counted values appearing on output conductors 98 and 100 of X and Y latch circuits 56 and 58 are encoded and are sent to a computer. The computer performs information processing and changes the display in accordance with the result. When the relatively wide stylus 12 intercepts at least one of beams sent in X and Y directions, binary counted values of all intercepted beams are alternately supplied to the computer. The position of the center of the stylus 12 is calculated based on these counted values.</p> |
