| 摘要 |
PURPOSE:To enable to perform a high-precise and steady self-measurement, which is reduced in a zero drift, in a wide range and high-speed photometry though bringing of an amplifying range into a self-switching operation, by alining in parallel two operational amplifiers at an initial stage. CONSTITUTION:A photoelectric conversion element 1 is connected beween current input ends of each of two operation amplifiers 2 and 3 which are constituted to perform a current-voltage conversion. A range decision circuit 4 is conncted to the operational amplifier 3 to install a switch circuit 5 for switching the degree of amplification of the operational amplifier 2 corresponding to the output. If, for example, a photoelectromotive force is generated in the photoelectric conversion element 1, photocurrents, being different in polar phases and equilizing in an absolute value, are inputted to the operational amplifiers 2 and 3. The output of the operational amplifiers 3 produces a range signal by means of a range decision circuit 4 to be outputted to a switch circuit 5 where the degree of amplification of the operational amplifier 2 is switched. |
