Device for controlling exposure time in a camera

Claim 1

In a device for controlling exposure time in an automatic exposure camera which device includes: a. a power source; b. a photoelectric converter circuit including a photoconductive element having a resistance value determined by the intensity of light from an object to be photographed, and an impedance element connected in series with said photoconductive element, said photoelectric converter circuit being connected with said power source; c. a first switch connected in series with and between said photoelectric converter circuit and said power source to make and break the connection therebetween; d. a storage capacitor for storing a voltage divided by said photoconductive element and said impedance element when said first switch is closed; e. a second switch connected between the point of connection between said photoconductive element and said impedance element and one end of said capacitor, said second switch being adapted to open after said first switch is closed, the voltage stored in said storage capacitor becoming independent of any variation in the resistance value of said photoconductive element after said second switch is opened; f. a magnet driving circuit including a magnet for controlling the exposure time of the camera''s shutter in accordance with the voltage stored in said storage capacitor, said magnet driving circuit being connected with said power source in parallel relationship with said photoelectric converter circuit; and g. a third switch connected between said magnet driving circuit and said power source to make and break the connection therebetween, said third switch being adapted to close after said second switch is opened; the improvement comprising: a compensation circuit connected with said power source in parallel relationship with said photoelectric converter circuit and said magnet driving circuit, said compensation circuit including a resistor; the other end of said storage capacitor being connected with said compensation circuit so as to apply to said storage capacitor part of a voltage drop caused across said resistor by a voltage drop occurring in said power source when said third switch is closed.