Exposure control device

Claim 2

An exposure control apparatus, comprising photo-electric means for converting an amount of light to an electric quantity, memory means, pulse entry means responsive to said photo-electric means for entering into said memory means a sequence of sets of equally spaced pulses each set corresponding in number to an electric quantity being connected, shutter control means for producing shutter operating signals, timing means responsive to a signal from said control means and coupled to said memory means for reading out the value in said memory means and controlling said control means for a time period dependent upon the content of said memory means, said timing means forming clock pulses in response to said control means for reading out said memory means.

Claim 3

An exposure control apparatus, comprising photo-electric means for converting amounts of light to electric quantities, memory means, pulse entry means responsive to said photo-electric means for entering into said memory means a sequence of sets of equally spaced pulses each set corresponding in number to sequential ones of the electric quantities, shutter control means for producing shutter operating signals, timing means responsive to a signal from said control means and coupled to said memory means for reading out the value in said memory means and controlling said control means for a time period dependent upon the content of said memory means, said memory means storing a count equal to the pulses entered, said timing means including pulse carrying means for carrying a plurality of equally spaced pulses, gate means for applying said pulses to said memory means in response to a shutter opening signal from said control means so that each pulse reads out one count in said memory means, and detecting means coupled to said memory means for producing a shutter closing signal when the pulses have read the full count in said memory means.

Claim 4

An exposure control apparatus, comprising photo-electric means for converting amounts of light to electric quantities, memory means, pulse entry means responsive to said photo-electric means for entering into said memory means a sequence of sets of equally spaced pulses each set corresponding in number to sequential ones of the electric quantities, shutter control means for producing shutter operating signals, timing means responsive to a signal from said control means and coupled to said memory means for reading out the value in said memory means and controlling said control means for a time period dependent upon the content of said memory means, said memory means storing a count equal to the pulses entered, said timing means including pulse carrying means for carrying a plurality of equally spaced pulses, gate means for applying said pulses to said memory means in response to a shutter opening signal from said control means so that each pulse reads out one count in said memory means, and detecting means coupled to said memory means for producing a shutter closing signal when the pulses have read the full count in said memory means.

Claim 5

An apparatus as in claim 2, wherein pulse generating means supply pulses of equal repetition rate to said pulse entering means and said pulse carrying means.

Claim 6

An apparatus as in claim 2, wherein pulse generating means supply pulses having a greater repetition rate to said pulse entering means than said pulse carrying means.

Claim 7

An exposure control device for a photographic shutter comprising, shutter control means for opening and closing a shutter to produce exposures of variable duration, the duration of said exposure caused by said shutter control means being controllable by digital pulses, pulse producing means for producing digital pulses, said pulse producing means having a photo-electric conversion element to convert a light brightness to an electrical quantity and a digital pulse generating circuit connected with the photo-electric conversion element and producing a number of pulses proportional to the electrical quantity from said element, memory means coupled to said pulse generating circuit for memorizing and retaining the digital pulses produced by said pulse producing means, and drive means connected to detect digital pulses in said memorizing means for driving said shutter control means for a period proportional to the pulses in said memory means, said drive means including clock pulse forming means responsive to said control means for forming clock pulses and reading out the pulses in said memory means in response to operation of said control means.

Claim 8

An exposure control device for a photographic shutter comprising, shutter control means for opening and closing a shutter to produce exposures of variable duration, the duration of said exposure caused by said shutter control means being controllable by digital pulses, pulse producing means for producing digital pulses, said pulse producing means having a photo-electric conversion element to convert a light brightness to an electrical quantity and a digital pulse generating circuit connected with the photo-electric conversion element and producing a number of pulses proportional to the electrical quantity from said element, memory means coupled to said pulse generating circuit for memorizing and retaining the digital pulses produced by said pulse producing means, and drive means connected to detect digital pulses in said memorizing means for driving said shutter control means for a period proportional to the pulses in said memory means, said drive means including clock pulse forming means responsive to said control means for forming clock pulses and reading out the pulses in said memory means in response to operation of said control means.

Claim 9

An exposure control device for a photographic shutter comprising, shutter control means for opening and closing a shutter to produce exposures of variable duration, the duration of said exposure caused by said shutter control means being controllable by digital pulses, pulse producing means for producing digital pulses, said pulse producing means having a photo-electric conversion element to convert a lIght brightness to an electrical quantity and a digital pulse generating circuit connected with the photo-electric conversion element and producing a number of pulses proportional to the electrical quantity from said element, memory means coupled to said pulse generating circuit for memorizing and retaining the digital pulses produced by said pulse producing means, drive means connected to detect digital pulses in said memorizing means for driving said shutter control means for a period proportional to the pulses in said memory means, said drive means including a second pulse generating circuit for producing pulses having a predetermined repetition rate which start in response to said shutter control means opening the shutter, and a comparing circuit connected to said memory means for comparing the number of pulses in the memory means with the number of pulses produced by said second pulse producing circuit, said comparing circuit being connected to drive said shutter control means when the number of pulse memorized in said memory means and produced by said second pulse producing means are equal.

Claim 10

An exposure control device for a photographic shutter comprising, shutter control means for opening and closing a shutter to produce exposures of variable duration, the duration of said exposure caused by said shutter control means being controllable by digital pulses, pulse producing means for producing digital pulses, said pulse producing means having a photo-electric conversion element to convert a lIght brightness to an electrical quantity and a digital pulse generating circuit connected with the photo-electric conversion element and producing a number of pulses proportional to the electrical quantity from said element, memory means coupled to said pulse generating circuit for memorizing and retaining the digital pulses produced by said pulse producing means, drive means connected to detect digital pulses in said memorizing means for driving said shutter control means for a period proportional to the pulses in said memory means, said drive means including a second pulse generating circuit for producing pulses having a predetermined repetition rate which start in response to said shutter control means opening the shutter, and a comparing circuit connected to said memory means for comparing the number of pulses in the memory means with the number of pulses produced by said second pulse producing circuit, said comparing circuit being connected to drive said shutter control means when the number of pulse memorized in said memory means and produced by said second pulse producing means are equal.

Claim 11

An apparatus as in claim 6, wherein said first and second pulse producing circuits produce pulses of equal periods.

Claim 12

An apparatus as in claim 6, wherein said first and second pulse producing circuits produce pulses of unequal periods, the repetition rate of said second pulse producing circuit being lower than that of the first pulse producing circuit.

Claim 13

An apparatus as in claim 2, wherein setting means set the pulse periods of said first and second pulse producing circuits on the basis of film sensitivity of the film being exposed.

Claim 14

An apparatus as in claim 9, wherein indicating means connected to said memory means calculate and indicate the content of said memory means as an indication of exposure time.