Metering device

A metering device comprising:

• a photoelectric converter circuit for generating a first voltage corresponding to the brightness of a subject to be photographed, said photoelectric converter circuit including a photoelectric converter element and a first conductor element for logarithmically converting the output of said photoelectric converter element;
• a voltage generating circuit comprising a constant current source including a second semiconductor element for providing a constant current to said second semiconductor element, a resistor, and said constant current source flowing to said resistor a current proportional to an absolute temperature, said voltage generating circuit being effective to generate a second voltage which is the sum of the voltage produced in said second semiconductor element and the voltage produced in said resistor;
• a differential amplifier for amplifying the voltage difference between said first and second voltage;
• a voltage generating circuit for generating a third voltage proportional to the absolute temperature;
• a comparator circuit for comparing the output voltage of said differential amplifier with said third voltage;
• and
• means for equalizing the output voltge of said differential amplifier and said third voltage by the output of said comparator circuit.

A metering device comprising:

• a photoelectric converter circuit for generating a first voltage corresponding to the brightness of a subject to be photographed, said photoelectric converter circuit including a photoelectric converter element and a first conductor element for logarithmically converting the output of said photoelectric converter element;
• a voltage generating circuit including a second semiconductor element and a current source for providing a current proportional to an absolute temperature to a resistor connected in series to said second semiconductor element, said voltage generating circuit being effective to generate a second voltage comprising the sum of the voltage generated in said resistor and said second conductor element;
• a differential amplifier for amplifying the voltage difference between said first and second voltage;
• a time-voltage converter circuit including an integrating capacitor adapted to operate in response to opening of a camera shutter to thereby convert time into a logarithmic function and put out a third voltage proportional to the absolute temperature;
• a comparator circuit for comparing the output voltage of said differential amplifier with said third voltage;
• and
• means for effecting the operation for the shutter when the output of said differential amplifier and said third voltage have been equalized by said comparator circuit.