Exposure control system

An exposure control system for photographic apparatus, the apparatus having means for mounting photographic film material at a given focal plane, means for directing image-carrying light rays from a photographic scene to the focal plane, and selectively operable means for initiating an exposure cycle, said system comprising:

• means for selecting an exposure value;
• blade means;
• means for mounting said blade means for displacement between a position blocking the optical path and other positions unblocking the optical path, said blade means defining progressively increasing aperture values through which scene light is transmitted along he optical path as said blade means are displaced from said blocking position;
• drive means actuatable for displacing said blade means between said positions;
• and
• control means responsive to the cycle initiating means for initially actuating said drive means to displace said blade means from its said blocking position to initiate an exposure interval during which scene light is directed to the focal plane and for subsequently actuating said drive means to displace said blade means back to said blocking position to terminate said exposure interval, said control means including means for at least initially actuating said drive means to displace said blade means through a plurality of steps defining successively larger predetermined aperture values, each of said successive predetermined aperture values being achieved at progressively longer intervals of time following initiation of said exposure interval so as to define a minimum exposure initiation interval corresponding to each successive predetermined aperture value and means, responsive to said selected exposure value, for selecting the maximum predetermined aperture value achieved and for varying the exposure initiation interval between a time value ranging from less than to greater than the minimum exposure initiation interval corresponding to the next successive predetermined aperture value so as to provide optimum film exposure in accordance with said exposure value.

An exposure control system for photographic apparatus comprising:

• exposure mechanism means movable from one position to define a progressive variation of aperture values over an exposure opening and being operative to block said exposure opening to terminate the passage of light therethrough;
• drive means, pulse energizable to move said exposure mechanism means;
• light sensing means for deriving an exposure value inversely responsive to the brightness level of the scene to be photographed;
• converter means for deriving a digital representation of said exposure value;
• control means for actuating said drive means to displace said blade means from said one position to initiate an exposure interval and for subsequently actuating said drive means to displace said blade means to a position blocking the optical path so as to terminate said exposure interval, said control means including:
• first network means for counting at a given frequency while synchronously transmitting drive pulses at a submultiple of said one frequency to said drive means so as to displace said blade means from said one position;
• evaluating means for providing a given output signal responsive to equality between the count of said counting means and said digital representation;
• second network means including:
• means responsive to said given output signal for temporarily precluding further transmission of said drive pulses so as to halt said drive means in a predetermined step position;
• means for subsequently initiating further transmission of drive pulses to said drive means to displace said blade means to a blocking position to terminate said exposure interval;
• and
• means for varying the time interval between halting of said drive means and said subsequent transmission proportional to the number of count pulses following the last drive pulse before said equivalence.

An exposure control system for photographic apparatus comprising:

• exposure mechanism means movable from a first position to define a progressive variation of aperture values over an optical path and being operative to block said optical path to terminate an interval of exposure;
• exposure evaluating means having an output signal corresponding with an exposure evaluation of a scene;
• converter means responsive to said exposure evaluating means output and operative to derive a digital representation thereof;
• means for generating energizing pulses at a given frequency;
• first counter means for counting pulses transferred thereto at said given frequency to derive a time dependent output digital representation of the number transferred;
• first equality network means responsive both to said converter means and said counter means digital representations for generating a unique signal condition when the values of said representations coincide;
• drive means including a pulse energizable motor for moving said exposure mechanism means from said first position to initiate an exposure interval and subsequently operative to cause said exposure mechanism means to block said optical path;
• pulse transfer means for pulse energizing said motor at a submultiple of said given frequency simultaneously and in correspondence with said pulse counting and operative to block the transfer of pulses to said first counter means and said motor to halt said blade means in a given position in response to said first equality network means unique signal condition;
• and
• vernier control means for selectively delaying said optical path blockage for a time interval substantially equal to the number of pulses at said given frequency received at said first counter means following the receipt at said motor of that pulse energizing said motor to move said exposure mechanism means into said given position.

A photographic exposure control system for a camera, the camera having means for mounting photographic material at a given focal plane, means for directing imagecarrying rays from a scene along a given optical path to the camera focal plane, and selectively operable means for initiating an exposure cycle, said system comprising:

• means for selecting an exposure value, said exposure value selecting means including means for determining an exposure value inversely proportional to scene brightness;
• blade means;
• means for mounting said blade means for displacement between a position blocking the optical path and another position unblocking the optical path, said blade means providing changing aperture values through which scene light may pass to the focal plane as said blade means are displaced from said blocking position;
• drive means for displacing said blade means through a plurality of steps responsive to a train of step pulses;
• control means responsive to the exposure initiating means for counting at a first pulse rate and for applying step pulses to said drive means at a second pulse rate which is a submultiple of said first to initially displace said blade means from said blocking position to said other position to initiate an exposure interval during which scene light is directed to the focal plane and, in accordance with said exposure value, for subsequently displacing said blade means to again block the optical path thereby terminating the exposure interval, said control means including means responsive to said selected exposure value for halting said initial displacement of said blade means at a location defining a predetermined aperture value, for maintaining said blade means at said location for a time determined in accordance with said exposure value and said predetermined aperture and for subsequently displacing said blade means to block the optical path, said means for halting said initial displacement including means for comparing the count of said counting means with said exposure value and, responsive to equivalence therebetween, for precluding further application of said step pulses to said drive means to halt said displacement of said blade means, and said means for maintaining said blade means at said location including means for then actuating said drive means to displace said blade means back to its said blocking position following the occurrence after said equivalence of a number of pulses at said first pulse rate proportional to the number of pulses at said first rate following the last step pulse applied prior to said equivalence.

A photographic exposure control system for a camera, the camera having means for mounting photographic material at a given focal plane, means for directing image-carrying rays from a scene along a given optical path to the camera focal plane, and selectively operable means for initiating an exposure cycle, said system comprising:

• means for selecting an exposure value;
• blade means;
• means for mounting said blade means for displacement between blocking and unblocking relation to the optical path and for defining at least one of a plurality of incrementally different aperture values in operative relation to the optical path;
• control means responsive to the exposure initiating means for displacing said blade means from said blocking relation into said unblocking relation and for defining at least one aperture value in operative relation to the optical path so as to initiate an exposure interval during which scene light is transmitted along the optical path and for then displacing said blade means back into blocking relation to the optical path to terminate the exposure interval, said control means including;
• means for determining one exposure time programmed in accordance with a predetermined aperture value and, the selected exposure value;
• means for selecting from said plurality of aperture values a final aperture value not greater than said predetermined aperture value and for determining another exposure time programmed in accordance with the final aperture value;
• and
• means for maintaining said blade means at said final aperture value, following said one exposure time, for an additional time proportional to the difference in time between said one and said other exposure times.