Exposure control device

Abstract

In the exposure control apparatus disclosed, a photo-electric element converts light to which it is exposed to an electrical quantity. A pulse entry circuit responds to the photo-electric element and enters a sequence of sets of pulses into a memory. Each set of pulses corresponds in number to the electric quantity and erases the previous set. A timing clock responds to a signal from a shutter opening member and keeps reading out the content of the memory until the memory is empty at which time the circuit, in conjunction with the memory, produces a shutter closing signal.

What is claimed is: 
     
       1. 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. 
     
     
       2. 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 include 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. 
     
     
       3. 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. .[.4. 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..]. 5. 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, pulses 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. 6. 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. 7. An apparatus as in claim 6, wherein said first and second pulse 
     
     
        producing circuits produce pulses of equal periods. 8. 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. .[.9. 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..]. .[.10. 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..]. .Iadd. 11. A photographic camera system, comprising; photo-electric means for converting a brightness of the object to be photographed into a first electrical signal having a value corresponding to the brightness;   (b) a pulse generator;   (c) memory means connected to said pulse generator, said memory means counting the pulses from the pulse generator and memorizing the pulses from the pulse generator;   (d) means for generating an electrical comparison signal;   (e) comparator means connected to said photo-electric means and said comparison signal generating means, said comparator means comparing the first electrical signal of said photo-electric means with the electrical comparison signal of said comparison signal generating means and producing a control signal when the difference between two signals reach a predetermined value;   (f) gate means coupling said pulse generator to said memory means and connected to said comparator means for preventing transmission of the pulses from said pulse generator to said memory means in response to a control signal from comparator, whereby the counted pulses are memorized in said memory means;   (g) an electrically controlled exposure defining device; and   (h) control means connected to said memory means for controlling an exposure on the basis of the number of the pulses memorized in said memory means. .Iaddend. .Iadd. 12. A photographic camera system according to claim 11, wherein said comparison signal generating means (5) produce a gradually changing voltage. .Iaddend..Iadd. 13. A photographic camera system according to claim 11, wherein said comparison signal generating means produce periodically a gradually changing voltage. .Iaddend..Iadd. 14. A photographic camera system having an electrically controlled exposure defining device, 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 number of pulses corresponding to the electric quantity, whereby the pulses are memorized in said memory means, and control means connected to said memory means for controlling the defining device on the basis of the number of the pulses memorized in said memory means. .Iaddend..Iadd. 15. A photographic camera system according to claim 14, said pulse entry means including;   (a) a pulse generating means producing a plurality of equally spaced pulses;   (b) means for generating an electrical comparison signal having a gradually changing level;   (c) comparison means connected to the photo-electric means and the comparison signal generating means, said comparison means comparing the electric quantity of said photo-electric means with the comparison signal of said comparison signal generating means and producing a control signal when the difference between the electric quantity of said photo-electric means and the comparison signal of said comparison signal generating means reaches a predetermined value; and   (d) means connected to said comparison means for preventing transmission of the pulses from said pulse generating means to said memory means in response to a control signal from comparison means, whereby the pulses are memorized in said memory means. .Iaddend..Iadd. 16. A photographic camera system having an electrically controlled exposure defining device, 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 number of equally spaced pulses corresponding to the electric quantity, whereby the pulses are memorized in said memory means, and control means connected to said memory means for controlling the defining device on the basis of the number of the pulses memorized in said memory means. .Iaddend. .Iadd. 17. A photographic camera system according to claim 16, wherein said pulse entry means enter into said memory means a sequence of sets of equally spaced pulses each set corresponding in number to the electric quantity. .Iaddend..Iadd. 18. A photographic camera system, comprising;   (a) photo-electric means for converting an amount of light to an electric quantity;   (b) pulse forming means connected to said photo-electric means for forming a number of pulses corresponding to the electric quantity;   (c) memory means connected to said pulse forming means for memorizing the pulses form said pulse forming means;   (d) reset signal forming means operatively connected to said memory means, said reset signal forming means resetting the content of said memory means periodically;   (e) an electrically controlled exposure defining device; and   (f) control means connected to said memory means for controlling the defining device on the basis of the latest value memorized in said memory means. .Iaddend..Iadd. 19. A photographic camera system having an electrically controlled exposure defining device, comprising photo-electric means for converting an amount of light to an electric quantity, an exposure information means for generating an electrical signal corresponding to exposure informations other than the exposure value to be determined, memory means, pulse entry means responsive to said photo-electric means for entering into said memory means a number of pulses corresponding to the electric quantity and the electric signal from the exposure information means, whereby the pulses are memorized in said memory means, and control means connected to said memory means for controlling the defining device on the basis of the number of the pulses memorized in said memory means. .Iaddend..Iadd. 20. A photographic camera system, comprising;   (a) photo-electric means for converting an amount of light to an electric quantity;   (b) pulse forming means connected to said photo-electric means for forming a number of pulses corresponding to the electric quantity;   (c) memory means connected to said pulse forming means for memorizing the pulses form said pulse forming means;   (d) an electrically controlled exposure defining device for defining an exposure factor;   (e) reference signal generating means for producing a reference signal; and   (f) circuit means connected to said reference signal generating means and said memory means for producing a control signal, whereby when the two signals have come into a predetermined relation, said circuit means is operatively connected to said exposure defining device and said circuit means adjusts said exposure defining device on the basis of said control signal. .Iaddend. .Iadd. 21. A photographic camera system, comprsing;   (a) photosensitive means for converting an amount of light to an electric quantity;   (b) pulse generating circuit for producing a number of pulses corresponding to the electric quantity;   (c) start pulse generator for producing a start signal;   (d) memory means responsive to the start signal from said start pulse generator for storing the number of the pulses from said pulse generating circuit;   (e) logic gate means (12) which controls transfer of the number of pulses from said pulse generating cicuit to said memory means in response to the start signal from said start pulse generator;   (f) an electrically controlled exposure defining device (16, S), responsive to the start signal from said start pulse generator; and   (g) control means connected between said memory means and said exposure defining device, for defining device on the base of the number of the pulses stored in said memory means in response to the start signal from said pulse generator. .Iaddend. .Iadd. 22. A photographic camera system having an electrically controlled exposure defining device, comprising;   (a) photosensitive means for converting an amount of light to an electric quantity;   (b) pulse forming means connected to said photo-electric means for forming a number of pulses corresponding to the electric quantity;   (c) memory means connected to said pulse forming means for memorizing the pulses form said pulse forming means;   (d) pulse generating means for supplying a plurality of equally spaced pulses; and   (e) control means connected to said memory means for controlling the defining device on the basis of the number of the pulses memorized in said memory means, said control means including pulse carrying means for carrying a plurality of equally spaced pulses, and pulse generating means supply pulses having a greater repetition rate to said pulse forming means than said pulse carrying means. .Iaddend..Iadd. 23. In a photographic camera system having an electrically controlled shutter means, an exposure control arrangement comprising;   (a) photo-electric means for converting an amount of light to an electric quantity;   (b) memory means;   (c) pulse entry means responsive to said photo-electric means for entering into said memory means a number of pulses corresponding to the electric quantity, whereby the pulses are memorized in said memory means; and   (d) control means for controlling the shutter speed in response to the number of the pulses memorized in said memory means. .Iaddend..Iadd. 24. A photographic camera system, comprising;   (a) photo-electric means for converting an amount of light to an electric quantity;   (b) memory means;   (c) pulse entry means responsive to said photo-electric means for entering into said memory means a number of pulses corresponding to the electric quantity, whereby the pulses are memorized in said memory means;   (d) an electrically controlled exposure defining device; and   (e) control means coupled to said memory means for reading out the value in said memory means and controlling the defining device on the basis of the number of the pulses memorized in said memory means. .Iaddend..Iadd. 25. A photographic camera system, comprising;   (a) photosensitive means for converting an amount of light to an electric quantity;   (b) memory means;   (c) pulse entry means responsive to said photosensitive means for entering into said memory means a number of pulses corresponding to the electric quantity, whereby the pulses are memorized in said memory means;   (d) an electrically controlled exposure defining device; and   (e) control means connected to said memory means for controlling the defining device for a time period dependent upon the content of said   
     
     
        memory means. .Iaddend..Iadd. 26.  A photographic camera system, comprising; (a) photosensitive means for converting an amount of light to an electric quantity;   (b) memory means;   (c) pulse entry means responsive to said photosensitive means for entering into said memory means a number of pulses corresponding to the electric quantity, whereby the pulses are memorized in said memory means;   (d) an electrically controlled exposure defining device; and   (e) control means responsive to a signal from said exposure defining device and coupled to said memory means for reading out the value in said memory means and the defining device on the basis of the number of the pulses memorized in said memory means, said control means forming clock pulses in response to said exposure defining device for reading out said memory means. .Iaddend..Iadd. 27. A photographic camera system, comprising;   (a) photo-electric means for converting an amount of light to an electric quantity;   (b) memory means;   (c) 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 the electric quantity, whereby the pulses are memorized in said memory means;   (d) an electrically controlled shutter means; and   (e) control means connected to said memory means for controlling the defining device on the basis of the number of the pulses memorized in said   
     
     
        memory means. .Iaddend..Iadd. 28.  A photographic camera system, comprising; (a) photo-electric means for converting an amount of light to an electric quantity;   (b) memory means;   (c) pulse entry means responsive to said photo-electric means for entering into said memory means a number of pulses corresponding to the electric quantity, whereby the pulses are memorized in said memory means;   (d) an electrically controlled shutter means; and   (e) control means connected to said memory means for reading out the value memorized in said memory means and controlling the shutter speed on the basis of the number of the pulses memorized in said memory means. .Iaddend. .Iadd. 29. A photographic camera system, comprising;   (a) photo-elecctric means for converting an amount of light to an electric quantity;   (b) memory means;   (c) pulse entry means responsive to said photo-electric means for entering into said memory means a number of pulses corresponding to the electric quantity, whereby the pulses are memorized in said memory means;   (d) an electrically controlled shutter means; and   (e) control means responsive to a signal from said shutter and connected to said memory means for controlling the shutter speed for a time period dependent upon the content of said memory means. .Iaddend..Iadd. 30. A photographic camera system, comprising;   (a) photo-electric means for converting an amount of light to an electric quantity;   (b) memory means;   (c) pulse entry means responsive to said photo-electric means for entering into said memory means a number of pulses corresponding to the electric quantity, whereby the pulses are memorized in said memory means;   (d) an electrically controlled shutter means; and   (e) control means connected to said memory means for reading out the value in said memory means and for controlling the shutter speed on the basis of the number of the pulses memorized in said memory means, said control means forming clock pulses in responsive to said shutter means for reading out said memory means. .Iaddend.