| 摘要 |
<p>PURPOSE:To obtain proper exposure in a simple constitution by switching over a reference voltage for comparision and decision to the charging voltae correspoinding to a characteristic curve of correction quantity based on the difference between reflectances of the shutter screen surface and the film surface at the time of transit of the rear edge of a light screen at the center of a picture frame. CONSTITUTION:When the leading edge of a shutter screen runs, the output from measuring light is integrated by an operational amplifier 2, an integration condenser 3, etc. This integral voltage is compared with a reference voltage for decision based on the information voltage of film sensitivity. Then, when the rear edge of a light screen passes the center of a picture frame, a measuring quantity is changed correspondingly to the characteristic curve of correction quantity DELTAEV based on the difference between reflectances of the shutter screen surface and the film surface. At this point, analog switches 16 and 18 are closed and the voltage from a charging circuit 15 consisting of a condenser 13 and a resistor 14 that are of the time constant corresponding to the characteristic curve of correction quantity DELTAEV is applied to the reference voltage for decision from an amplifier 8 through an amplifier 21. Therefore, a correct measuring output is decided and a proper exposure control is performed in a simple constitution that has no use of two set light measuring circuits.</p> |
