| 摘要 |
PURPOSE:To enable a periodically fluctuating light to be accurately measured, in a digital photometry, by forming a synchronizing signal from the periodically fluctuating light. CONSTITUTION:The light from a TV picture surface 1 is photoelectrically converted 4 through an optical chopper 2, smoothed 6, V/F-converted 7 and counted 9 through gate 8 to obtain a picture data. The opening and closing positions of the chopper 2 are detected 15, and said detection signals are differentiated 17 and 18 to from an trigger signal for a mono-stable oscillator 20. The output thereof is used to reset the counter 9 and a synchronizing signal counter 12. The output of a TV picture synchronizing signal detector 10 is shaped 11 into a square wave and counted 12. Said count value is decoded 13 to trigger an FF14. The output thereof is applied to the AND gate 8. Accordingly, the light pulse component synchronized with the TV synchronizing signal is applied to the counter 9. |
