Image sensing device having a photometric element for setting an exposure condition for the image sensing device

• US 4,956,715 A
• Filed: 09/19/1989
• Issued: 09/11/1990
• Est. Priority Date: 04/24/1984
• Status: Expired due to Term

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Date, Nobuaki, Okino, Tadashi, Saito, Syuichiro, Tezuka, Nobuo
• Primary Examiner(s): BRINICH, STEPHEN M
• Application Number:
  US07/409,283
• Time in Patent Office: 357 Days
• Field of Search: 358/909, 358/228, 358/213.13, 354/431, 354/432, 354/402
• US Class Current: 348/230.1
• CPC Class Codes: H04N 23/71 Circuitry for evaluating the brightness variation
• CPC Class Codes: H04N 23/72 Combination of two or more compensation controls
• CPC Class Codes: H04N 23/73 by influencing the exposure time
• CPC Class Codes: H04N 25/53 Control of the integration time

Abstract

An image sensing device includes an image sensor; a photometric element which is arranged separate from the image sensor to measure light with a diaphragm aperture fully opened; a storing time control circuit arranged to variably control the storing time of the image sensor; a circuit arranged to form exposure control information from the output of the image sensor on the basis of the output of the photometric element at least under a condition in which the storing time is controlled by the storing time control circuit; and an exposure control circuit arranged to control the exposed condition of the image sensor on the basis of the exposure control information.

Claims

1. An image sensing device comprising:

(a) image sensing means;

(b) a photometric element;

(c) accumulating time control means for variably controlling the storing time of said image sensing means;

(d) exposure information forming means for forming first exposure control information based on an output of said photometric element, and for forming second exposure control information based on an output of said image sensing means, under a condition in which the accumulating time is controlled by said accumulating time control means; and

(e) exposure control means for correcting the exposure condition of said image sensing means on the basis of said second exposure control information, said exposure control means having a lower responsiveness than said accumulating time control means.

2. A device according to claim 1, wherein said accumulating time control means is provided to control the accumulating time by clearing an image sensing signal in said image sensing means at a predetermined timing.

3. A device according to claim 1, said exposure control means comprising stop means for controlling the quantity of light incident upon said image sensing means.

4. A device according to claim 3, wherein said photometric element is disposed behind said stop means.

5. A device according to claim 1, said exposure control means comprising shutter means for variably controlling the incident time of light incident on said image sensing means.

6. A device according to claim 5, wherein said light incident time controlled by said shutter means nearly corresponds to said accumulating time.

7. An image sensing device according to claim 1, and further comprising recording means for recording an output of said image sensing means which is formed under a condition in which said exposure control means corrects the exposure condition of said image sensing means.

8. An exposure controlling method for a still video camera comprising:

(a) a first step of forming first exposure control information for an object to be photographed, said information being formed based on light measuring means which is provided in addition to image sensing means;

(b) a second step of controlling an aperture value of an iris based on said first exposure control information, under a condition in which the accumulating time of said image sensing means is also controlled based on said first exposure control information;

(c) a third step of forming second exposure control information for correcting said first exposure information based on an image sensing signal formed by said image sensing means at said second step; and

(d) a fourth step of controlling the level of subsequent image sensing signals formed by said image sensing means based on the second exposure control information formed at the second step.

9. A method according to claim 8, wherein, at said fourth step, the quantity of light incident upon said image sensing means is controlled on the basis of said corrected first exposure control information.

10. A method according to claim 8, wherein, at said fourth step, at least the incident time of the light incident upon said image sensing means is controlled based on said corrected first exposure control information.

11. An exposure controlling method according to claim 8, and further comprising a step of recording and image sensing signal formed by said image sensing means during said fourth step.

12. An image sensing device for a still video camera comprising:

(a) stop means for controlling the quantity of light incident;

(b) image sensing means for forming an image sensing signal from light incident through said stop means;

(c) light measuring means other than said image sensing means for detecting the luminance of an object to be photographed;

(d) accumulating time control means for controlling the accumulating time of said image sensing means;

(e) control means for controlling said stop means;

(f) exposure control information forming means for forming light metering information based on said image sensing signal, under a condition in which the accumulating time is controlled by said accumulating time control means, and in which said stop means is controlled by said control means according to an output of said light measuring means; and

(g) level control means for controlling the level of subsequent image sensing signal formed in said image means according to said light metering information.

13. An image sensing device according to claim 12, said exposure control means comprising correcting means for correcting said stop means on the basis of said light metering information.

14. An image sensing device according to claim 12, and further comprising recording means for recording an image sensing signal which is level controlled by said level control means.

15. An image sensing device for a still video camera, comprising:

(a) image sensing means for generating an image signal; and

(b) exposure control means for controlling light incident to said image sensing means, comprising;

(1) a shutter member located in front of said image sensing means;

(2) presetting means for presetting an exposure time of said shutter member; and

(3) control means for accumulating the image signal in the image sensing means for a period of time corresponding to the exposure time preset by said presetting means, and for correcting said preset exposure time based on said image signal, and for controlling said shutter member so as to subsequently expose said image sensing means for said corrected preset exposure time.

16. A device according to claim 15, wherein said shutter member includes a shutter blade.

17. A device according to claim 15, wherein said presetting means includes manual setting means.

18. A device according to claim 15, wherein said presetting means further includes light metering means, and controls said exposure time by using a light metering information of said light metering means.

19. A device according to claim 15, wherein said exposure control means further includes a diaphragm.

20. A device according to claim 19, which further comprises recording means for recording the image signal whose exposure time is controlled by the control means.

21. An image sensing and recording device for a still video camera, comprising:

(a) image sensing means for generating an image signal and having variable accumulating time;

(b) a trigger member;

(c) a diaphragm for adjusting an amount of light incident on said image sensing means;

(d) a shutter located in front of said image sensing means which controls a time of incidence of light on said image sensing means;

(e) indication means for indicating a time value for the light incidence by said shutter and an aperture value for said diaphragm;

(f) control means for setting said diaphragm to the aperture value corresponding to the indication of said indication means by an operation of said trigger member, and for driving said image sensing means instead of said shutter to store the image signal for the time indication by said indication means to obtain a first image signal;

(g) shutter driving means for causing the light incidence, in accordance to the first image signal, to form a second image signal for said image sensing means for a predetermined shutter time; and

(h) recording means for recording the second image signal as a still image.

22. A device according to claim 21, wherein said setting means includes manual setting means.

23. A device according to claim 21, wherein said presetting means further includes light metering means, and controls said predetermined time value based on a light metering information of said light metering means.

24. An image sensing device for a still video camera, comprising:

(a) image sensing means for generating an image signal, said image sensing means variably controlling the accumulating time;

(b) a trigger member;

(c) a diaphragm for adjusting an amount of light incident on said image sensing means;

(d) a shutter located in front of said image sensing means which controls a time of incidence of light on said image sensing means;

(e) control means for forming a first image signal in response to said triggering means to drive said diaphragm and said image sensing means to obtain a predetermined aperture value and a predetermined accumulating time, respectively, then correcting said predetermined accumulating time based on said first image signal and successively forming a second image signal by driving said shutter in accordance with the first image signal to effect incidence of light on said image sensing means for a predetermined time; and

(f) recording means for recording the second image signal.

25. A device according to claim 24, wherein the diaphragm maintains a full-open state until said trigger member operates.