Exposure control apparatus for photographic camera

Claim 1

An exposure control apparatus for a photographic camera having an exposure time control circuit comprising: a first photoconductive element adapted to directly receive the light coming from the object to be photographed, a first capacitor connected in series with said first photoconductive element, a first switching transistor adapted to have its switching action controlled by the charge voltage of said first capacitor, and an electromagnet connected to the output side of said first transistor for holding the shutter in the open state, wherein said exposure control apparatus further includes a second photoconductive element adapted to receive the light passing through the objective lens system, a third photoconductive element adapted to directly receive the light coming from the object to be photographed, a second capacitor for storing a voltage having a magnitude corresponding to the ratio of resistance value between said second and third photoconductive elements, a sawtooth voltage generating circuit, a second switching transistor adapted to have its switching action controlled by the comparison of the voltage stored by said second capacitor and the sawtooth voltage produced by said sawtooth voltage generating circuit, and a transistor adapted to be rendered conductive whenever said second switching transistor is rendered nonconductive to thereby charge said first capacitor via said first photoconductive element.