| 摘要 |
1,159,857. Photo-electric camera control. SOC. D'OPTIQUE PRECISION ELECTRONIQUE ET MECANIQUE. Sept. 13, 1967 [Sept. 20, 1966] No.41801/67. Heading G1. [Also in Division G3] In an automatic camera diaphragm control system a photo-resistor fed with a constant current receives light through the diaphragm and controls the diaphragm opening to maintain its illumination constant; the value of the constant current is adjustable according to film speed. In Fig. 2 a photo-resistor 9 is fed with constant current from transistor 13. One of transistors 21 and 22 conducts depending upon the direction of the voltage excursion across photo-resistor 9 from a nominal value set by resistor 9 and operates motor 11 to adjust the diaphragm opening and return the photo-resistor voltage back to the nominal value. Transistor 13 may be replaced by a field effect transistor, Fig. 3 (not shown), when the stabilizing thermistor 15 becomes unnecessary. |
