Shakeproof camera wherein shake correction parameters may be changed

• US 5,587,737 A
• Filed: 05/25/1995
• Issued: 12/24/1996
• Est. Priority Date: 01/23/1992
• Status: Expired due to Term

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Sekine, Masayoshi, Kondo, Toshiaki, Kino, Yoshiki
• Primary Examiner(s): Garber, Wendy
• Assistant Examiner(s): CHRISTENSEN, ANDREW BRUCE
• Application Number:
  US08/449,917
• Time in Patent Office: 579 Days
• Field of Search: 348/208, 348/221, 348/296, 348/207
• US Class Current: 348/208.8
• CPC Class Codes: G02B 27/646 compensating for small deviations, e.g. due to vibration or shake movement of one or more optical elements for control of motion blur in cameras, projectors or printers G03B2205/0007; image stabilisation in cameras peculiar to the presence or use of an electronic image sensor H04N23/68
• CPC Class Codes: H04N 23/68 for stable pick-up of the scene, e.g. compensating for camera body vibrations
• CPC Class Codes: H04N 23/6811 based on the image signal
• CPC Class Codes: H04N 23/686 with a variable apex prism
• CPC Class Codes: H04N 23/73 by influencing the exposure time

Abstract

A shakeproof camera includes an image pickup element whose exposure time and exposure period are set variable, a shake detection circuit for detecting a photographed image shake on the basis of an output from the image pickup element, a shake correction unit for correcting the image shake on the basis of an output from the shake detection circuit, and a control circuit for changing control parameters of the shake correction unit in accordance with the exposure time and the exposure period of the image pickup element.

Claims

1. A shakeproof camera comprising:

(A) image pickup means;

(B) shake detecting means for detecting an image shake from an image pickup signal output from said image pickup means;

(C) shake correcting means for correcting the image shake in accordance with an output from said shake detecting means;

(D) control structure for changing an accumulation time of said image pickup means; and

(E) control means for changing correction parameters of said shake correcting means in accordance with a variation of the accumulation time of said image pickup means controlled by said control structure.

2. A camera according to claim 1, wherein said shake detecting means calculates a movement vector of the image on the basis of a change of the image between a plurality of frames, and detects a shake amount and a shake direction.

3. A camera according to claim 1, wherein said shake correcting means includes a variable vertical angle prism.

4. A camera according to claim 1, wherein said shake correcting means comprises a shake correction feedback loop control system including said image pickup means, said shake detecting means, and said shake correcting means, and wherein said shake correction feedback loop control system comprises a discrete time control system having the accumulation time of the image pickup signal of said image pickup element as a sampling frequency.

5. A camera according to claim 4, wherein said shake detecting means starts a detection operation in synchronism with read access of said image pickup means and outputs a detection result during a vertical blanking period.

6. A camera according to claim 4, wherein the sampling frequency of said shake detecting means is substantially equal to the accumulation time of said image pickup means, and wherein said control means changes correction parameters of said feedback loop control system in accordance with the sampling frequency.

7. A camera according to claim 1, further comprising mode operating means for changing an accumulation time and/or an exposure period of said image pickup means in accordance with a photographic mode, and wherein said control means changes the correction parameters in accordance with a photographic mode set by said mode operating means.

15. A camera according to claim 1, wherein said shake detecting means calculates a movement vector of an image on the basis of a change between a plurality of frames obtained at different times and detects a shake amount and a shake direction.

16. A camera according to claim 15, wherein said shake correcting means includes a variable vertical angle prism and comprises, together with said image pickup means and said shake detecting means, a shake correction feedback loop control system for driving and controlling said variable vertical angle prism, and wherein said shake correction feedback loop control system comprises a discrete time control system having a read cycle of the image pickup signal of said image pickup means as a sampling frequency.

8. A shakeproof camera comprising:

(A) image pickup means;

(B) movement vector detecting means for detecting a movement vector of an image at a predetermined sampling period from an image pickup signal output from said image pickup means;

(C) control structure for controlling the sampling period so as to produce sampling periods which are equal to, greater than, and less than a standard image pickup period of the image sensor;

(D) correcting means for correcting a movement of the image in accordance with an output from said movement vector detecting means; and

(E) control means for changing correction parameters of said correcting means in accordance with a change in the sampling period controlled by said control structure.

9. A camera according to claim 8, wherein said correcting means includes a variable vertical angle prism.

10. A camera according to claim 8, wherein the sampling period of said movement vector detecting means is substantially equal to a read period of said image pickup means.

11. A camera according to claim 10, wherein said movement vector detecting means samples at the read period of said image pickup means and outputs detection information during a vertical blanking period.

12. A camera according to claim 11, wherein said correction means changes the control parameters to correct a delay of a feedback loop comprising by said image pickup means, said movement vector detecting means, and said correcting means.

13. A camera according to claim 12, wherein said control means varies a coefficient of a transfer function of said feedback loop variable.

14. A shakeproof camera comprising:

(A) image pickup means;

(B) exposure control means for changing an exposure time of said image pickup means;

(C) shake detecting means for detecting an image shake in accordance with a read period of said image pickup means from an image pickup signal output from said image pickup means;

(D) shake correcting means for correcting the image shake in accordance with an output from said shake detecting means; and

(E) control means for changing correction parameters of said shake correcting means in accordance with a variation of the exposure time of said image pickup means which is set by said exposure control means.

17. A camera according to claim 14, wherein said shake detecting means starts a detection operation in synchronism with read access of said image pickup means and outputs a detection result during a vertical blanking period.

18. A camera according to claim 14, wherein said exposure control means changes an accumulation time and/or the read period of said image pickup means in accordance with a photographic mode and changes correction parameters of said shake correcting means in accordance with a change in the accumulation time and/or the read period.

19. A shakeproof camera comprising:

(A) image pickup means;

(B) shake detecting means for detecting an image shake from an image pickup signal output from said image pickup means;

(C) shake correcting means for correcting the image shake in accordance with an output from said shake detecting means;

(D) storage means for storing correction characteristics of said shake correcting means in correspondence with a plurality of image pickup modes of said image pickup means, wherein the image pickup modes comprise a standard image pickup mode, a high-speed shutter image pickup mode, and a long exposure mode; and

(E) control means for, in response to a change of said image pickup mode, reading out correction characteristics corresponding to the image pickup mode of said image pickup means from said storage means and setting the readout correction characteristics in said shake correcting means.

20. A camera according to claim 19, further comprising mode selecting means for selecting the image pickup mode, and wherein said control means controls the correction characteristics in accordance with a state of said mode selecting means.

21. A camera according to claim 19, wherein said shake correcting means comprises a shake correction feedback control system including said image pickup means, said shake detecting means, and said shake correcting means, and wherein said shake correction feedback control system comprises a discrete time control system having a read cycle of the image pickup signal of said image pickup means as a sampling frequency.

22. A camera according to claim 21, further comprising read period control means for controlling a read period of said image pickup means, and wherein the sampling frequency of said shake detecting means is substantially equal to a read period of said image pickup means, and said control means changes the correction characteristics of said feedback loop control system in accordance with a change in the sampling frequency.