Full range variable proportional fill flash system

• US 4,375,322 A
• Filed: 05/11/1981
• Issued: 03/01/1983
• Est. Priority Date: 05/11/1981
• Status: Expired due to Term

• Current Assignee: Polaroid Corporation (PLR IP Holdings LLC)
• Original Assignee: Polaroid Corporation (PLR IP Holdings LLC)
• Inventors: Rodriguez, Marie T., Coppa, Richard J.
• Primary Examiner(s): Adams, Russell E.
• Application Number:
  US06/262,501
• Time in Patent Office: 659 Days
• Field of Search: 354/23 D, 354/27, 354/29, 354/33, 354/34, 354/60 F, 354/195
• US Class Current: 396/105
• CPC Class Codes: G03B 7/16 in accordance with both the intensity of the flash source and the distance of the flash source from the object, e.g. in accordance with the "guide number" of the flash bulb and the focusing of the camera

Abstract

A photographic exposure control system of the type for controlling both the duration of a photographic exposure interval and the amount of artificial illumination provided during the exposure interval includes the capability of increasing the amount of artificial illumination in direct corresponding relation with increases in the camera-to-subject distance and the ambient scene light intensity in order to maintain the same proportional contribution to the film exposure from the ambient artificial light during a fill flash exposure.

Claims

1. In a photographic exposure control system of the type for controlling both the duration of a photographic exposure interval and the amount of artificial illumination provided during the exposure interval to provide a proportional fill flash exposure, the improvement comprising:

means for further controlling the amount of artificial illumination provided during the exposure interval in a manner whereby the amount of artificial illumination provided during the exposure interval is increased in direct corresponding relation with increases in the camera-to-subject distance and the ambient scene light intensity in order to maintain the same proportional contribution to the film exposure from the ambient and artificial light during a fill flash exposure.

2. The improvement of claim 1 wherein the exposure control system is of the type which includes means for determining the camera-to-subject distance prior to the exposure interval and for providing a timed signal corresponding to the determined camera-to-subject distance and means for detecting the ambient scene light intensity prior to the exposure interval and wherein said means for further controlling the amount of artificial illumination comprises means for counting the pulses for a first select frequency pulse train during a time interval corresponding to the timed signal provided by the camera-to-subject distance determining means prior to exposure, and for counting pulses from a second select frequency pulse train to offset against said pulses already counted from said first pulse train during a subsequent time interval corresponding to the time during which the pre-exposure ambient scene light is detected, said resultant pulse count thereafter being utilized during the exposure interval to time the duration of the artificial illumination during the fill flash exposure.

3. The improvement of claim 2 wherein the frequency of said first and second pulse trains are selected with respect to each other so as to assure that said resultant pulse count from said counting means is zero when the ambient scene light detected prior to the exposure interval is less than a select level thereby also assuring that said means for further controlling the amount of artificial illumination operates to control the amount of artificial illumination only under conditions where the ambient scene light intensity is above said select level.

4. The improvement of claim 3 wherein the exposure control system includes a shutter blade mechanism, means for mounting the shutter blade mechanism for displacement between at least one arrangement wherein it blocks scene light from reaching a focal plane and another arrangement wherein it defines a maximum size aperture so that the blade mechanism defines a range of progressively increasing sized apertures for admitting scene light to the focal plane as it moves from its scene light blocking arrangement to its maximum aperture size defining arrangement, means for detecting the scene light during the exposure interval in correspondence with the scene light admitted to the focal plane by the blade mechanism and for providing an assertive output signal upon the detection of a select amount of scene light corresponding to a select exposure value, selectively actuatable drive means for driving the shutter blade mechanism from its scene light blocking arrangement to its scene light unblocking arrangement and for thereafter returning the shutter blade mechanism to its scene light blocking arrangement in response to the assertive output signal from the scene light detecting means, and means for providing a signal to ignite the source of artificial illumination at the aperture defined by the blade mechanism when the aperture size corresponds to the camera-to-subject distance or, alternatively, at the aperture size defined by the blade mechanism upon receipt of the assertive output signal from the scene light detecting means when such aperture size is less than the aperture size corresponding to the camera-to-subject distance;

and wherein said means for further controlling the amount of artificial illumination includes gating means for disabling the artificial illumination control influence provided by said means for further controlling the amount of artificial illumination when the source of artificial illumination is ignited at the aperture size corresponding to the camera-to-subject distance.

5. The improvement of claim 2 wherein said counting means is signalled in correspondence with the ignition of the source of artificial illumination to start counting back to zero from said resultant pulse count and wherein the time required for said counting means to count back from said resultant pulse count to zero determines the duration at which the source of artificial illumination is ignited.

6. The improvement of claim 5 wherein the source of artificial illumination is an electronic flash of the quench type and wherein said means for further controlling the amount of artificial illumination includes gating means responsive to said counting means counting back from said resultant pulse count to zero to provide a signal effective to quench the electronic flash.

7. A system for controlling the amount of light provided by a source of artificial illumination during an exposure interval for use with a photographic camera apparatus of the type having a photographic exposure control system for controlling the admission of scene light to a focal plane to define an exposure interval wherein the exposure control system also includes means responsive to the determination of camera-to-subject distance for providing an output response corresponding to the determined camera-to-subject distance and means for detecting the ambient scene light intensity and for providing a response to the ambient scene light so detected, said control system comprising:

means for providing at least one pulse train output signal;

means for counting the individual pulses from said pulse train; and

gating means for gating said pulse train output signal to said counting means to enable said counting means to count the individual pulses therefrom during an interval corresponding to the determined camera-to-subject distance so as to input said counting means with a pulse count corresponding to the camera-to-subject distance, said gating means thereafter gating said pulse train output signal to said counting means to enable said counting means to offset the individual pulses counted therefrom against the previous pulse count during the interval in which the ambient scene light is detected prior to the exposure interval so as to input said counting means with a resultant pulse count corresponding to both the camera-to-subject distance and the ambient scene light intensity, said gating means thereafter responding to the ignition of the source of artificial illumination to gate said pulse train output signal to said counting means to enable said counting means to again offset the individual pulses counted therefrom against said previous resultant pulse count until reaching a zero count at which instant said gating means responds to provide a signal terminating the ignition of the source of artificial illumination.

8. The control system of claim 7 wherein the source of artificial illumination is an electronic flash of the quench type and wherein said terminating signal quenches the electronic flash.

9. A system for controlling the amount of light provided by a source of artificial illumination during an exposure interval for use with a photographic camera apparatus of the type having a photographic exposure control system for controlling the admission of scene light to a focal plane to define an exposure interval wherein the exposure control system also includes means responsive to the determination of camera-to-subject distance prior to the exposure interval for providing a timed signal corresponding to the determined camera-to-subject distance and means for detecting the ambient scene light intensity prior to the exposure interval, said control system comprising:

means for providing first and second pulse train output signals;

means for counting the individual pulses from said first and second pulse trains; and

gating means for gating said first pulse train to said counting means to enable said counting means to count the individual pulses therefrom during the interval of the timed signal thereby inputting said counting means with a pulse count corresponding to the camera-to-subject distance, said gating means thereafter gating said second pulse train to said counting means to enable said counting means to offset the individual pulses counted therefrom against the previous pulse count from said first pulse train during the interval in which the ambient scene light is detected prior to the exposure interval thereby inputting said counting means with a resultant pulse count corresponding to both the camera-to-subject distance and the ambient scene light intensity, said gating means thereafter responding to the ignition of the source of artificial illumination to gate said second pulse train to said counting means to enable said counting means to again offset the individual pulses counted therefrom against said previous resultant pulse count until reaching a zero count at which instant said gating means responds to provide a signal for terminating the ignition of the source of artificial illumination.

10. The system of claim 9 wherein the frequency of said first and second pulse trains are selected with respect to each other so as to assure that said resultant pulse count from said counting means is zero when the ambient scene light detected prior to the exposure interval is less than a select level thereby also assuring that said artificial illumination control system operates to control the amount of artificial illumination only under conditions where the ambient scene light intensity is above said select level.

11. The system of claim 9 wherein the camera photographic control system further includes a shutter blade mechanism, means for mounting the shutter blade mechanism for displacement between at least one arrangement wherein it blocks scene light from reaching a focal plane and another arrangement wherein it defines a maximum size aperture wherein the blade mechanism defines a range of progressively increasing sized apertures for admitting scene light to the focal plane as it moves from its scene light blocking arrangement to its maximum aperture size defining arrangement, means for detecting the scene light during the exposure interval in correspondence with the scene light admitted to the focal plane by the blade mechanism and for providing an assertive output signal upon the detection of a select amount of scene light corresponding to a select exposure value, selectively actuatable drive means for driving the shutter blade mechanism from its scene light blocking arrangement to its scene light unblocking arrangement and for thereafter returning the shutter blade mechanism to its scene blocking arrangement in response to the assertive output signal from the scene light detecting means, and means for providing a signal to ignite the source of artificial illumination at the aperture defined by the blade mechanism when the aperture size corresponds to the camera-to-subject distance or, alternatively, at the aperture size defined by the blade mechanism upon receipt of the assertive output signal from the scene light detecting means when such aperture size is less than the aperture size corresponding to the camera-to-subject distance;

and wherein said gating means responds to provide said ignition terminating signal only in response to the signal to ignite the source of artificial illumination being provided at the aperture size defined by the blade mechanism upon receipt of the assertive output signal from the scene light detecting means when such aperture size is less than the aperture size corresponding to the camera-to-subject distance.

12. The system of claim 11 wherein the source of artificial illumination is an electronic flash of the quench type and wherein said artificial illumination control system gating means responds to said counting means counting back from said resultant pulse count to zero to provide said ignition terminating signal to quench the electronic flash.

13. A photographic camera apparatus for use with a source of artificial illumination comprising:

means responsive to the determination of the camera-to-subject distance for providing an output response corresponding to the determined camera-to-subject distance;

a shutter blade mechanism;

means for mounting the shutter blade mechanism for displacement between at least one arrangement wherein it blocks scene light from reaching a focal plane and another arrangement wherein it defines a maximum size aperture, said blade mechanism defining a range of progressively increasing sized apertures for admitting scene light to the focal plane as it moves from its scene light blocking arrangement to its maximum aperture defining arrangement;

means for detecting the ambient scene light intensity prior to an exposure interval and for providing an output signal in response to the ambient scene light so detected, said detecting means also operating to detect scene light during an exposure interval in correspondence with the scene light admitted by said blade mechanism to provide an assertive output signal upon the detection of a select amount of scene light corresponding to a select exposure value;

selectively actuatable drive means for driving said shutter blade mechanism from its scene light blocking arrangement to its scene light unblocking arrangement and for thereafter returning said shutter blade mechanism to its scene light blocking arrangement to terminate the exposure interval in response to the assertive output signal from said scene light detecting means;

means for providing a signal for igniting the source of artificial illumination at the aperture defined by the blade mechanism when the aperture size corresponds to the camera-to-subject distance or, alternatively, at the aperture size defined by the blade mechanism upon receipt of said assertive output signal from said scene light detecting means when such aperture size is less than the aperture size corresponding to the camera-to-subject distance; and

artificial illumination control means for controlling the amount of artificial illumination as a function solely of said output signal from said ambient scene light detecting means prior to the exposure interval when the source of artificial illumination is ignited at the aperture size corresponding to the camera-to-subject distance or, alternatively, for controlling the amount of artificial illumination as a function of both said output response which corresponds to said determined camera-to-subject distance and said output signal from said ambient scene light detecting means prior to the exposure interval when the source of artificial illumination is ignited at the aperture size defined by said blade mechanism upon receipt of said assertive output signal from said scene light detecting means.

14. The camera of claim 13 wherein said artificial illumination control means operates to increase the amount of artificial illumination provided during the exposure interval in correspondence with decreasing ambient scene light intensity when the source of artificial illumination is ignited at the aperture size corresponding to the camera-to-subject distance and to increase the amount of artificial illumination provided during the exposure interval in correspondence with increasing ambient scene light intensity and increasing camera-to-subject distance when the source of artificial illumination is ignited at the aperture size defined by said blade mechanism upon receipt of said assertive output signal from said scene light detecting means.

15. The camera of claim 14 wherein said artificial illumination control means comprises:

means for providing at least one pulse train output signal;

means for counting the individual pulses from said pulse train; and

gating means for gating said pulse train output signal to said counting means to enable said counting means to count the individual pulses therefrom during an interval corresponding to the determined camera-to-subject distance so as to input said counting means with a pulse count corresponding to the camera-to-subject distance, said gating means thereafter gating said pulse train output signal to said counting means to enable said counting means to offset the individual pulses counted therefrom against the previous pulse count during the interval in which the ambient scene light is detected prior to the exposure interval so as to input said counting means with a resultant pulse count corresponding to both the camera-to-subject distance and the ambient scene light intensity, said gating means thereafter responding to the ignition of the source of artificial illumination to gate said pulse train output signal to said counting means to enable said counting means to again offset the individual pulses counted therefrom against said previous resultant pulse count until reaching a zero count at which instant said gating means responds to provide a signal terminating the ignition of the source of artificial illumination.

16. The camera of claim 15 wherein said resultant pulse count from said counting means is zero when the ambient scene light detected prior to the exposure interval is less than a select level thereby disabling said artificial illumination control system from increasing the amount of artificial illumination in correspondence with increasing camera-to-subject distance.

17. The camera of claim 16 wherein the source of artificial illumination is an electronic flash of the quench type and wherein said artificial illumination control system gating means responds to said counting means counting back from said resultant pulse count to zero to provide said ignition terminating signal to quench the electronic flash.

18. A photographic camera apparatus of the type having an exposure control system for controlling the admission of scene light to a focal plane to define an exposure interval and for use with a source of artificial illumination, said apparatus comprising:

means responsive to the determination of the camera-to-subject distance for providing an output response corresponding to the determined camera-to-subject distance;

means for detecting the ambient scene light intensity at least prior to an exposure interval and for providing an output signal in response to the ambient scene light so detected; and

artificial illumination control means for controlling the amount of artificial illumination as a function solely of said output signal from said ambient scene light detecting means prior to the exposure interval when the said output signal from said ambient scene light detecting means prior to the exposure interval is less than a select value or, alternatively, for controlling the amount of artificial illumination as a function of both said output response which corresponds to said determined camera-to-subject distance and said output signal from said ambient scene light detecting means prior to the exposure interval when said output signal from said ambient scene light detecting means prior to the exposure interval is greater than said select value.

19. The camera of claim 18 wherein said artificial illumination control means operates to increase the amount of artificial illumination provided during the exposure interval in correspondence with decreasing ambient scene light intensity when said ambient scene light intensity detected prior to exposure is less than said select value and to increase the amount of artificial illumination provided during the exposure interval in correspondence with increasing ambient scene light intensity and increasing camera-to-subject distance when said ambient scene light intensity detected prior to exposure is greater than said select value.

20. The camera of claim 19 wherein the source of artificial illumination is an electronic flash of the quench type and wherein said artificial illumination control means responds to provide a signal to quench the electronic flash.