Abstract The electronic shutter device of this invention has a circuit for generating a voltage whose value is proportional to a logarithm of a magnitude of the current generated by a photosensitive element for sensing the intensity of the light from an object. It is so designed that said voltage generating circuit is used also for a circuit for controlling a shutter speed by the antilogarithmic transformation. Thus the variation in temperature and aging chracteristics, which are inherent if the separate circuits were provided, of a logarithmic transformation component can be corrected automatically. Further, an element adopted to store therein the intensity of light from the object is placed in the logarithmic transformation circuit.
An electronic shutter device of the type comprising a circuit for performing a logarithmic transformation of the output variation of a photoelectric effect element which senses light from an object to be photographed, a memory means for storing the output from said logarithmic transformation circuit, a circuit for performing the antilogarithmic transformation of the output from said memory means, a control circuit for controlling an exposure time in response to the output of said antilogarithmic transformation circuit and a switching means adapted to selectively switch said logarithmic transformation circuit so as to be used as said antilogarithmic transformation circuit.
Claim 2
Dependent Claim
99 words
An electronic shutter device of the type comprising a circuit for performing a logarithmic transformation of the output variation of a photoelectric effect element which senses light from an object to be photographed, a memory means for storing the output from said logarithmic transformation circuit, a circuit for performing the antilogarithmic transformation of the output from said memory means, a control circuit for controlling an exposure time in response to the output of said antilogarithmic transformation circuit and a switching means adapted to selectively switch said logarithmic transformation circuit so as to be used as said antilogarithmic transformation circuit.