| 摘要 |
PURPOSE:To remove the influence of ambient light and to detect the incident position of specific light accurately by flickering the light detected by a photodetection panel at a specific frequency, discriminating the photodetection signal of the flickering light with a frequency discriminator and comparing the same with a reference value. CONSTITUTION:Laser light is flickered at a specific frequency and a frequency discrimination part 13 and an amplifier means 14 are provided between a selection part 2 for the photodetection signal and a comparison means 3. When light Y is made incident to a photodetector 1, a photodetection signal A' is outputted. The signal A' is selected in the part 2, and is delivered as a selected photodetection signal B' to the part 13, from which only the synchronizing signal is outputted and the light signal of such a DC component as ambient light is removed. The selected photodetection signal E obtained in such a way is amplified to an amplified photodetection signal F with the means 14, and is compared with a reference voltage C in the means 3. If said signal exceeds the voltage C, a compared signal D' indicating that the selected photodetector detects the light is obtained, whereby the incident position of the light Y is detected accurately. |
