| 摘要 |
PURPOSE:To reduce errors of a current value and, at the same time, input errors of film sensitivity, especially for the film of usually used sensitivity, by providing plural adding means which superposed voltages upon each other in correspondence to film sensitivity steps and plural subtracting means which subtract voltages. CONSTITUTION:A constant-current source I0 supplies a constant current to a resistance 12. When any one of constant-current sources I1, I2, and I5 is actuated by means of the output pattern of a decoder 13, each of the constant-current sources supplies the resistance 12 with its peculiar current by superposing the current upon the current supplied from the constant-current source I0. When any one of constant-current sources I3, I4, and I6 is actuated, each of the constant-current sources supplies the resistance 12 with its intrinsic current by subtracting the current from the current supplied from the constant-current source I0. Therefore, an electric current is made to flow to the resistance 12 in correspondence to the sensitivity of a loaded film. Since the terminal level of the resistance 12 depends on the quantity of the electric current made to flow to the resistance 12, the terminal level of the resistance 12 is determined in correspondence to the DX code described on the cartridge of a DX film.
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