| 摘要 |
PURPOSE:To reduce memory capacity to only necessary data capacity by confirming the effectiveness of data at the output stage of a photoelectric element and outputting only effective data to a computer. CONSTITUTION:Current signals IX1 and IX2 are voltage-converted and amplified by amplifiers 7 and 8 and then inputted to a subtracter 9 and an adder 10 at the same time, and their outputs are inputted to a divider 11 to perform position arithmetic. Position information obtained as the output of the divider 11 is inputted as the X coordinate of a light point to the computer. At this time, the output of the adder 10 is constant when the light point is on a PSD (position sensing device) and 0 when the light point disappears from on the PSD. For the purpose, the output of the adder 10 is supplied to a binarization circuit 14 to detect whether there is the light point on the PSD or not. Further, a gate circuit 13 which receives the output of the circuit 14 as a control input and the output of an A/D converter 12 as a signal input is provided to inhibit data from being expelled when there is no light point on the PSD.
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