Flash illumination system and method incorporating indirect reflecting surface detection

• US 5,136,312 A
• Filed: 08/26/1991
• Issued: 08/04/1992
• Est. Priority Date: 12/26/1989
• Status: Expired due to Fees

• Current Assignee: Eastman Kodak Company
• Original Assignee: Eastman Kodak Company
• Inventors: Wheeler, Richard B., Weaver, Thomas C.
• Primary Examiner(s): ADAMS JR, RUSSELL E
• Application Number:
  US07/754,242
• Time in Patent Office: 344 Days
• Field of Search: 354/132, 354/127.13, 354/145.1, 354/149.1
• US Class Current: 396/61
• CPC Class Codes: G03B 15/05 Combinations of cameras with electronic flash apparatus; Electronic flash units
• CPC Class Codes: G03B 2215/0528 movable reflector, e.g. change of illumination angle or illumination direction
• CPC Class Codes: G03B 2215/0553 with second integrated flash
• 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 flash system and method for providing artificial illumination for image capture wherein a source of flash illumination operates selectively in a first mode for projecting light in a first direction toward an indirect reflecting surface to illuminate a subject indirectly and in a second mode for projecting light in a second direction to illuminate the subject directly, electromagnetic radiation reflected directly from the indirect reflecting surface is sensed directly to provide a signal containing information about the indirect reflecting surface, and the information contained in the signal is utilized to control the selective projection of light in the first and second directions to control the quantities of indirect and direct light which illuminate the subject. In one aspect, electromagnetic radiation such as infrared radiation is transmitted to the indirect reflecting surface in a manner such that a portion of the radiation is reflected from the surface back to the flash system where it is detected to provide a signal containing information relating to the distance between the surface and a given location in the flash system. In another aspect, light reflected directly from the indirect reflecting surface during operation of the source in the first or indirect flash mode is received directly by a sensor in the system to provide a signal indicating the presence of the indirect reflecting surface.

Claims

1. A flash system for providing artificial illumination for image capture comprising:

a) a source of flash illumination which operates selectively in the first mode for projecting light in a first direction toward an indirect reflecting surface located in spaced relation to a subject to illuminate the subject indirectly and in a second mode for projecting light in a second direction to illuminate the subject directly;

b) sensing means utilizing electromagnetic radiation reflected from the indirect reflecting surface for providing a signal containing information about the indirect reflecting surface, said sensing means being positioned to receive electromagnetic radiation reflected from the indirect reflecting surface and not directly from the subject; and

c) control means operatively connected to said source of flash illumination and to said sensing means for controlling the selective operation of said source in said first and second modes as determined by the information in said signal from said sensing means.

2. A flash system according to claim 1, wherein said sensing means comprises means for transmitting electromagnetic radiation to the indirect reflecting surface in a manner such that a portion of the radiation is reflected from said surface and detecting means for receiving radiation reflected from the surface and providing a signal containing information relating to the distance between the surface and a given location and wherein said control means is operatively connected to said source of flash illumination and to said detecting means for causing operation of said source in both said first and second modes when the indirect reflecting surface is within a predetermined distance of said given location and for causing operation of said source only in said second mode when said surface is not within said predetermined distance.

3. A flash system according to claim 1, wherein said sensing means is located to receive light reflected from the indirect reflecting surface directly to said sensing means during operation of said source in said first mode for providing a signal indicating the presence of the indirect reflecting surface and wherein said control means is operatively connected to said source of flash illumination and to said sensing means for continuing operation of said source in said first mode when said signal is received within a predetermined time and then causing operation of said source in said second mode and for ceasing operation of said source from said first mode and operating said source in said second mode if said signal is not received within the predetermined time.

4. A flash system according to claim 1, wherein said source of flash illumination comprises separate indirect and direct flash light beam sources.

5. A flash system according to claim 1, wherein said source of flash illumination comprises a single flash light beam source and controlled means for separating the output of said single source into separate direct and indirect flash light beams.

6. A method of providing artificial illumination for image capture wherein light from a source of flash illumination is selectively projected in a first direction toward an indirect reflecting surface located in spaced relation to a subject to illuminate the subject indirectly and in a second direction to illuminate the subject directly, said method comprising the steps of:

a) sensing directly electromagnetic radiation reflected directly from the indirect reflecting surface and not directly from the subject to provide a signal containing information about the indirect reflecting surface; and

b) utilizing the information contained in said signal to control the selective projection of the light in said first and second directions to control the quantities of indirect and direct light which illuminate the subject.

7. A flash system for providing artificial illumination for image capture comprising:

a) a source of flash illumination which operates selectively in a first mode for projecting light in a first direction toward an indirect reflecting surface located in spaced relation to a subject to illuminate the subject indirectly and in a second mode for projecting light in a second direction to illuminate the subject directly;

b) means separate from said source for transmitting electromagnetic radiation in a third direction to the indirect reflecting surface in a manner such that a portion of the radiation is reflected from said surface;

c) detecting means for receiving said radiation reflected from the surface and providing a signal containing information relating to the distance between the surface and a given location; and

d) control means operatively connected to said source of flash illumination and to said detecting means for causing operation of said source in both said first and second modes when the indirect reflecting surface is within a predetermined distance of said given location and for causing operation of said source only in said second mode when said surface is not within said predetermined distance.

8. A flash system according to claim 7, wherein said transmitting means and said detecting means comprises an infrared emitter-detector combination and wherein said control means comprises distance finder means operatively connected to said combination for providing a signal indicative of the distance between said combination and the indirect reflecting surface.

9. A flash system according to claim 7 in combination with a camera, further including means for varying camera aperture selection as a function of the selective operation of said source of flash illumination in said first and second modes.

10. A flash system according to claim 7 in combination with a camera, wherein said camera includes auto-ranging and flashmatic exposure control systems and wherein said apparatus further includes:

a) means for selecting camera aperture based on a default flashmatic program utilizing subject distance information when said source of flash illumination is operated only in said second mode; and

b) means for causing the flashmatic programs to increase camera lens opening when said source of flash illumination is operated in both said first and second modes.

11. A flash system according to claim 7 in combination with a camera, wherein said camera includes auto-ranging and flashmatic exposure control systems and wherein said apparatus further includes:

a) means utilizing subject distance information to determine a direct flash f number when said information about said indirect reflecting surface indicates the absence of such surface; and

b) means utilizing subject distance information to determine an indirect flash f number when said information about said indirect reflecting surface indicates the presence of such surfaces.

12. A flash system according to claim 7 in combination with a camera, wherein said camera includes auto-ranging and flashmatic exposure control systems and wherein said apparatus further includes:

a) means utilizing subject distance information to determine the output of said source in said second mode when said information about said indirect reflecting surface indicates the absence of such surface; and

b) means utilizing subject distance information to determine the output of said source in said first and second modes when said information about said indirect reflecting surface indicates the presence of such surface.

13. A flash system according to claim 7 in combination with a camera, further including:

a) means for selecting a rapid recycle mode wherein said source of flash illumination operates only in said second mode; and

b) means operatively associated with said selecting means for utilizing subject distance information to determine a rapid recycle f number.

14. A method of providing artificial illumination for image capture wherein light from a source of flash illumination is selectively projected in a first direction toward an indirect reflecting surface located in spaced relation to a subject to illuminate the subject indirectly and in a second direction to illuminate the subject directly, said method comprising the steps of:

a) transmitting electromagnetic radiation in a third direction to the indirect reflecting surface in a manner such that a portion of the radiation is reflected from the surface;

b) detecting said radiation reflected from the indirect reflecting surface to provide a signal containing information relating to the distance between the surface and a given location; and

c) utilizing the information contained in said signal to cause projection of light in both said first and second directions when the indirect reflecting surface is within a predetermined distance of said given location and to cause projection of light only in said second direction when the indirect reflecting surface is not within said predetermined distance.

15. A flash system for providing artificial illumination for image capture comprising:

a) a source of flash illumination which operates selectively in a first mode for projecting light in a first direction toward an indirect reflecting surface located in spaced relation to a subject to illuminate the subject indirectly and in a second mode for projecting light in a second direction to illuminate the subject directly;

b) sensing means located to receive light reflected from the indirect reflecting surface directly to said sensing means during operation of said source in said first mode for providing a signal indicating the presence of the indirect reflecting surface, said sensing means comprising photodetector means disposed to receive light reflected from the indirect reflecting surface directly back to the photodetector means; and

c) control means operatively connected to said source of flash illumination and to said sensing means for continuing operation of said source in said first mode when said signal is received within a predetermined time then causing operation of said source in said second mode and for terminating operation of said source from said first mode and operating said source in said second mode if said signal is not received within the predetermined time, said control means comprising means for comparing the output of said photodetector means to a threshold value and circuit means for providing control signals indicative of whether or not the output of said photodetector means exceeds said threshold value within said predetermined time.

16. A flash system according to claim 15 in combination with a camera, further including means for varying camera aperture selection as a function of the selective operation of said source of flash illumination in said first and second modes.

17. A flash system according to claim 15 in combination with a camera, wherein said camera includes auto-ranging and flashmatic exposure control systems and wherein said apparatus further includes:

a) means for selecting camera aperture based on a default flashmatic program utilizing subject distance information when said source of flash illumination is operated only in said second mode; and

b) means for causing the flashmatic programs to increase camera lens opening when said source of flash illumination is operated in both said first and second modes.

18. A flash system according to claim 15 in combination with a camera, wherein said camera includes auto-ranging and flashmatic exposure control systems and wherein said apparatus further includes:

a) means utilizing subject distance information to determine a direct flash f number when said information about said indirect reflecting surface indicates the absence of such surface; and

b) means utilizing subject distance information to determine an indirect flash f number when said information about said indirect reflecting surface indicates the presence of such surface.

19. A flash system according to claim 15 in combination with a camera, wherein said camera includes auto-ranging and flashmatic exposure control systems and wherein said apparatus further includes:

a) means utilizing subject distance information to determine the output of said source in said second mode when said information about said indirect reflecting surface indicates the absence of such surface; and

b) means utilizing subject distance information to determine the output of said source in said first and second modes when said information about said indirect reflecting surface indicates the presence of such surface.

20. A flash system according to claim 15 in combination with a camera, further including:

a) means for selecting a rapid recycle mode wherein said source of flash illumination operates only in said second mode; and

b) means operatively associated with said selecting means for utilizing subject distance information to determine a rapid recycle f number.

21. A method of providing artificial illumination for image capture wherein light from a source of flash illumination is selectively projected in a first direction toward an indirect reflecting surface located in spaced relation to a subject to illuminate the subject indirectly and in a second direction to illuminate the subject directly, said method comprising the steps of:

a) receiving light reflected directly from the indirect reflecting surface and not directly from the subject during operation of the source in the first mode to provide a signal indicating the presence of the indirect reflecting surface;

b) continuing operation of the source in the first mode when the signal is received within a predetermined time then causing operation of the source in the second mode; and

c) terminating operation of the source from the first mode and operating said source in a second mode if the signal is not received within the predetermined time.

22. A flash system for providing artificial illumination in combination with a camera and comprising:

a) a source of flash illumination which operates selectively in a first mode for projecting light in a first direction toward an indirect reflecting surface located in spaced relation to a subject to illuminate the subject indirectly and in a second mode for projecting light in a second direction to illuminate the subject directly;

b) sensing means utilizing electromagnetic radiation reflected from the indirect reflecting surface for providing a signal containing information about the indirect reflecting surface, said sensing means being positioned to receive electromagnetic radiation reflected directly to said sensing means from the indirect reflecting surface, and not directly from the subject;

c) control means operatively connected to said source of flash illumination and to said sensing means for controlling the selective operation of said source in said first and second modes as determined by the information in said signal from said sensing means; and

d) means for varying camera aperture selection as a function of the selective operation of said source of flash illumination in said first and second modes.

23. A flash system for providing artificial illumination in combination with a camera including auto-ranging and flashmatic exposure control systems and comprising:

a) a source of flash illumination which operates selectively in a first mode for projecting light in a first direction toward an indirect reflecting surface located in spaced relation to a subject to illuminate the subject indirectly and in a second mode for projecting light in a second direction to illuminate the subject directly;

b) sensing means utilizing electromagnetic radiation reflected from the indirect reflecting surface for providing a signal containing information about the indirect reflecting surface, and said sensing means being positioned to receive electromagnetic radiation reflected directly to said sensing means from the indirect reflecting surface and not directly from the subject; and

c) control means operatively connected to said source of flash illumination and to said sensing means for controlling the selective operation of said source in said first and second modes as determined by the information in said signal from said sensing means.

24. Apparatus according to claim 23 further including:

a) means for selecting camera aperture based on a deflaut flashmatic program utilizing subject distance information when said source of flash illumination is operated only in said second mode; and

b) means for causing the flashmatic programs to increase camera lens opening when said source of flash illumination is operated in both said first and second modes.

25. Apparatus according to claim 23 further including:

a) means utilizing subject distance information to determine a direct flash f number when said information about said indirect reflecting surface indicates the absence of such surface; and

b) means utilizing subject distance information to determine an indirect flash f number when said information about said indirect reflecting surface indicates the presence of such surfaces.

26. Apparatus according to claim 23 further including:

a) means utilizing subject distance information to determine the output of said source in said second mode when said information about said indirect reflecting surface indicates the absence of such surface; and

b) means utilizing subject distance information to determine the output of said source in said first and second modes when said information about said indirect reflecting surface indicates the presence of such surface.

27. A flash system for providing artificial illumination in combination with a camera and comprising;

a) a source of flash illumination which operates selectively in a first direction toward an indirect reflecting surface located in spaced relation to a subject to illuminate the subject indirectly and in a second mode for projecting light in a second direction to illuminate the subject directly;

b) sensing means utilizing electromagnetic radiation reflected from the indirect reflecting surface for providing a signal containing information about the indirect reflecting surface, said sensing means being positioned to receive electromagnetic radiation reflected directly to said sensing means from the indirect reflecting surface and not directly from the subject;

c) control means operatively connected to said source of flash illumination and to said sensing means for controlling the selective operation of said source in said first and second modes as determined by the information in said signal from said sensing means;

d) means for selecting a rapid recycle mode wherein said source of flash illumination operates only in said second mode; and

e) means operatively associated with said selecting means for utilizing subject distance information to determine a rapid recycle f number.

28. A flash system for providing artificial illumination for image capture in combination with a camera, said flash system comprising:

a) a source of flash illumination which operates selectively in the first mode for projecting light in a first direction toward an indirect reflecting surface located in spaced relation to a subject to illuminate the subject indirectly and in a second mode for projecting light in a second direction to illuminate the subject directly;

b) sensing means utilizing electromagnetic radiation reflected from the indirect reflecting surface for providing a signal containing information about the indirect reflecting surface, said sensing means being positioned to receive electromagnetic radiation reflected directly from the indirect reflecting surface and not from the subject; and

c) control means operatively connected to said source of flash illumination and to said sensing means for controlling the selective operation of said source in said first and second modes as determined by the information in said signal from said sensing means.

29. A flash system for providing artificial illumination for image capture in combination with a camera, said flash system comprising:

a) a source of flash illumination which operates selectively in a first mode for projecting light in a first direction toward an indirect reflecting surface located in spaced relation to a subject to illuminate the subject indirectly and in a second mode for projecting light in a second direction to illuminate the subject directly;

b) means separate from said source for transmitting electromagnetic radiation in a third direction to the indirect reflecting surface in a manner such that a portion of the radiation is reflected from said surface;

c) detecting means for receiving said radiation reflected from the surface and providing a signal containing information relating to the distance between the surface and a given location; and

d) control means operatively connected to said source of flash illumination and to said detecting means for causing operation of said source in both said first and second modes when the indirect reflecting surface is within a predetermined distance of said given location and for causing operation of said source only in said second mode when said surface is not within said predetermined distance.

30. A flash system for providing artificial illumination for image capture in combination with a camera, said flash system comprising:

a) a source of flash illumination which operates selectively in a first mode for projecting light in a first direction toward an indirect reflecting surface located in spaced relation to a subject to illuminate the subject indirectly and in a second mode for projecting light in a second direction to illuminate the subject directly;

b) sensing means located to receive light reflected from the indirect reflecting surface directly to said sensing means during operation of said source in said first mode for providing a signal indicating the presence of the indirect reflecting surface, said sensing means comprising photodetector means disposed to receive light reflected from the indirect reflecting surface directly back to the photodetector means; and

c) control means operatively connected to said source of flash illumination and to said sensing means for continuing operation of said source in said first mode when said signal is received within a predetermined time then causing operation of said source in said second mode and for terminating operation of said source from said first mode and operating said source in said second mode if said signal is not received within the predetermined time, said control means comprising means for comparing the output of said photodetector means to a threshold value and circuit means for providing control signals indicative of whether or not the output of said photodetector means exceeds said threshold value within said predetermined time.