| 摘要 |
PURPOSE:To simplify the configuration of a circuit, and to raise an integration degree by fetching a binary-coding output through a constant-current circuit at a timing for reading an output pattern of a photodetector string, and detecting and controlling a ratio of its signal number. CONSTITUTION:Each analog output of a photodetector string 22 is digitized to 0/1 by a binary-coding circuit 23. The output of the photodetector string 22 is in a low level first, and an output of the binary-coding circuit train 23 is all ''0''. As the time elapses, each capacity is charged, and that which exceeds threshold voltage of the binary-coding circuit 23 is generated. By receiving it, an FET is turned on, input voltage VCO of a comparator 27 rises from an initial value, and when a ratio of ''0'' and ''1'' of the binary-coding circuit string 23 reaches a prescribed value, an output signal CONT of the comparator 27 is applied to a register 25, and its output is read, and processed by a logical circuit 26. As a result, the configuration of a circuit is simplified remarkably, and also the integration degree is raised. |
