Camera exposure control system having digitally controlled timing circuitry including a decimal count storing memory
AssigneeAsahi Kogaku Kogyo Kabushiki Kaisha
InventorTsukumo Nobusawa
Life of this patent
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Abstract
This invention provides apparatus for producing a command signal used to control the closing of a camera shutter. Before the shutter opens, a photo-responsive portion of the apparatus generates a number of serially occurring data pulses. After the shutter opens, a timing pulse generator portion produces a number of serially occurring timing pulses. A memory portion, including a plurality of registers, accumulates a decimal count of the serially occurring data pulses with each register storing a respective one of unit and higher decimal place portions of the decimal count. The memory forms part of a comparison circuit arrangement which responds to the data pulses and the timing pulses to produce the command signal.
Claims1
Apparatus for automatically controlling a camera exposure operation, the apparatus comprising:
- means for generating data pulses by the number according to light intensity of an object to be photographed, preset diaphragm value and film sensitivity prior to opening of the camera shutter;
- digital memory means of decimal type adapted to be applied with and store the data pulses so as to accumulate a decimal count of the number of these data pulses, the digital memory means including a plurality of registers each for storing a respective one of unit and higher decimal place portions of the decimal count;
- discriminator means adapted to discriminate whether the decimal count stored in said decimal digital memory means is within a predetermined range or not after completion of the data pulse storage in said decimal digital memory means, being further adapted to output a shutter opening signal when said stored decimal count is within said predetermined range, and to output a diaphragm adjusting signal together with a reset signal for said digital memory means when said stored decimal count is out of said predetermined range;
- means adapted to be applied with the shutter opening signal from said discriminator means and thereby to open the shutter;
- timing-pulse generating means adapted to begin to apply timing pulses after opening of the shutter;
- shutter closing means adapted to be activated when the number of pulses generated by said timing-pulse generating means comes in a special relationship with the number of data pulses stored in said digital memory means;
- means adapted to adjust the diaphragm by a predetermined amount when applied with the diaphragm adjusting signal from said discriminator means, and wherein, when the diagphragm has been adjusted by said diaphragm adjusting means to a predetermined extent, said photo-responsive pulse generating means is activated again after the diaphragm has been stopped and thereby said storage and said discrimination are repeated.
Dependencies are inferred from the claim text.