Electronic storage, indicator and exposure time control device for photographic cameras

In an electronic device for storing and indicating illumination parameters and for controlling the exposure time for photographic cameras having means for measuring the exposure time and means for generating said time, the improvement comprising said means for measuring exposure time including an analog/digital converter with a digital support part having a plurality of first binary stages provided with outputs and throw switches, said throw switches having a first position for a zero voltage and a second position for a supply voltage to be presented at each output and having stages which correspond to different exposure times depending on exposure parameters and wherein said means for generating said exposure time comprise:

• a. a pulse generator emitting pulses at a frequency the numerical value of which constitutes a multiple of the reciprocal value of the shortest exposure time;
• b. a 4 to 16 decoder connected to the last four of said binary stages for selecting a supply voltage that corresponds to the prevailing object brightness, said decoder having outputs;
• c. AND gates having a first input connected to the outputs of said 4 to 16 decoder, said AND gates having outputs and second and third inputs;
• d. a chain of binary ratio reducers connected to said input of said AND gates;
• e. a pulse generating timer controlling said chain of binary ratio reducers and being itself controlled by the first three of said binary stages;
• f. an OR gate to which said outputs of said AND gates are connected;
• g. a solenoid connected to said OR gate for closing a camera shutter on the appearance of a first signal at the OR gate output;
• said 4 to 16 decoder selecting the supply voltage carrying output of said binary stages which is in accordance with the object brightness and connecting same to the respective connected AND gate, and when, after the corresponding time interval, the attached binary ratio reducer also supplies one signal to said AND gate the output of said AND gate carries a one signal to the OR gate whereupon the camera shutter is closed;
• and
• h. means for blocking said 4 to 16 decoder and means for providing a one signal directly to said third input of one of said AND gates.

In an electronic device for storing and indicating illumination parameters including an exposure meter for controlling the exposure time for photographic cameras having means for measuring the exposure time and means for generating said time, the improvement comprising said means for measuring exposure time including an analog/digital converter with a digital storage part having a plurality of first binary stages provided with outputs and throw switches having a first position for a zero voltage and a second position for a storage voltage to be present at each output and having a plurality of stages which correspond to different exposure times depending on exposure parameters, and wherein said means for generating said exposure time comprise:

• a. a pulse generator emitting pulses at a frequency the numerical value of which constitutes a multiple of the reciprocal values of the shortest exposure time;
• b. a 3 to 8 decoder connected to three of said binary stages for selecting a supply voltage that corresponds to the prevailing object brightness, said decoder having outputs;
• c. AND gates having a first input connected to said outputs of said 3 to 8 decoder, said AND gates having outputs and second and third inputs;
• d. a plurality of binary ratio reducers connected to said second input of said AND gates;
• e. a pulse generaor timer controlling said plurality of binary ratio reducers and being itself controlled by the first three of said binary stages;
• f. an additional frequency determining element in said pulse generating timer for increasing the pulse frequency by the factor 2.sup.8, said element being controlled by the last one of said binary stages;
• g. an OR gate to which said outputs of said AND gates are connected;
• h. a solenoid connected to said OR gate for closing a camera shutter on the appearance of one signal at the OR gate output, said 3 to 8 decoder selecting the supply voltage carrying output of said binary stages which is in accordance with the object brightness and conducting same to the respective connected AND gate, and when, after the corresponding time interval, the attached binary ratio reducer also supplies a one signal to said AND gate, the output of said AND gate carries one signal to the OR gate whereupon the camera shutter is closed, and when said time interval is longer the last binary stage reduces the pulse frequency of said pulse generating timer by the appropriate factor;
• and
• i. said means for measuring the exposure time including a switch and a potentiometer for separating said exposure meter from the device and connecting said potentiometer to said device for manual adjustment of said exposure time.