| 摘要 |
1,244,736. Exposure control. EASTMAN KODAK CO. Sept. 18, 1968 [Sept. 18, 1967], No. 44334/68. Heading G2A. An exposure control circuit has a transducer 3 for controlling the diaphragm aperture according to the intensity of the lighting of an object area viewed by a photo-sensitive cell 2, and a shunt 6 connected across the transducer having a resistance dependent upon the output of the cell to control the flow of current through the transducer so that the latter regulates the admission of radiation to the medium in accordance with the logarithm of the illumination on the photo-cell. The shunt 3 is preferably a transistor, the base 6b being connected via a variable resistance 10 to a variable tapping 7 of a potentiometer 5. The transducer 3, which may be part of a galvanometer arrangement, is connected to the photosensitive cell through amplifying transistor 4, alternatively transistor 4 may be omitted, Fig. 2 (not shown). The photo-sensitive cell may be a photo-conductor as shown, or it may be a photo-voltaic cell, photo-diode, photo-transistor or a photo-sensitive field effect transistor. Vacuum tubes may be used in place of transistors. |
