| 摘要 |
PURPOSE:To permit fast photographing by providing an aperture member, freely rotatably to the inner circumferential part of a toroidal coil, trisecting the winding of the toroidal coil and connecting the 1st and 2nd outputs changing according to the output of photometry and fixed 3rd output. CONSTITUTION:The winding L of the toroidal coil 1 is trisected and terminals 1a, 1b, 1c are provided. Output parts 11, 12, 13 are respectively connected to said terminals. The aperture member 3 is then freely rotatably provided concentrically with the coil 1. Magnetic pole plates 4a, 4b of a permanent magnet 4 are fixed to the outer circum ferential part of the member 3 and are disposed opposite to the inside circumferential part of the coil 1. The output part 11 rises in proportion to the output of the photomet ric part and is saturated at the prescribed voltage. The output part 12 maintains the prescribed voltage until the photometric part attains the prescribed voltage and falls in proportion to the prescribed voltage when said part exceeds the prescribed voltage. The output part 13 outputs the specified voltage lower than the prescribed voltage. The rotating angle of the magnetic field of the toroidal coils is controlled by 3 kinds of such output parts and the aperture member 3 is rotated to adjust the opening degree of the aperture and, therefore, the fast driving control is permitted.
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