Method and apparatus for synchronizing two cameras

• US 5,307,168 A
• Filed: 11/10/1992
• Issued: 04/26/1994
• Est. Priority Date: 03/29/1991
• Status: Expired due to Term

• Current Assignee: Sony Electronics Inc. (Sony Group Corp.)
• Original Assignee: Sony Electronics Inc. (Sony Group Corp.)
• Inventors: Tashiro, Atsushi
• Primary Examiner(s): Mancuso, Joseph
• Assistant Examiner(s): Ho, Tuan V.
• Application Number:
  US07/974,385
• Time in Patent Office: 532 Days
• Field of Search: 358/209, 358/229, 358/225, 358/226, 358/88, 358/91, 358/97, 358/909, 354/76, 354/410, 354/412, 354/110
• US Class Current: 348/64
• CPC Class Codes: G03B 17/40 with delayed or timed action
• CPC Class Codes: H04N 23/00 Cameras or camera modules comprising electronic image sensors; Control thereof

Abstract

The imaging of a scene by two cameras is synchronized, wherein both cameras include releasable shutters exhibiting different shutter release delays. A controller responds to a release start signal to release the shutter of one of the cameras at a first time and to release the shutter of the other camera at a second, delayed time, the delay being substantially equal to the difference between the shutter release delays of the cameras. The release start signal may be manually produced when the user actuates a start switch; and this start signal is synchronized, or re-timed, when a predetermined one of the cameras is conditioned to image the scene. For example, if that camera includes a rotatable record disk to store electronic image signals, the shutter release operation is synchronized with the rotation of the disk to a reference position.

Claims

1. Apparatus for synchronizing the imaging of a scene by first and second cameras having respective shutters wherein said shutters may exhibit different shutter release delays τ

₁ and τ

₂, respectively, from the time that trigger signals are supplied to the respective cameras until the shutters arrive at their respective fully open positions, said apparatus comprising;

release means operable to initiate triggering of the shutters in said first and second cameras;

drive signal generating means for initiating a drive signal at a time t_a synchronized with the arrival of a storage medium of at least one of the cameras at a reference position for recording an image of the scene on said storage medium;

first and second trigger means synchronized in accordance with said drive signal for producing first and second trigger signals to release the shutters of said first and second cameras, respectively, such that the shutters arrive at their fully open positions at times t_x and t_y following said first and second trigger signals, respectively; and

delay means for delaying one of said trigger signals with respect to the other by a delay amount Δ

T substantially equal to the difference in the shutter release delays of said cameras Δ

T=τ

₁ -τ

₂ so that the shutters of said first and second cameras arrive at their fully open positions at substantially the same time t, where t=t_a +τ

₁ =t_a +Δ

T+τ

₂.

2. The apparatus of claim 1 wherein said storage medium of said one camera includes a rotary record disk to store electronic image signals.

3. The apparatus of claim 2, wherein said record disk has said reference position, and further comprising reference pulse means for providing a reference pulse when said disk rotates to said reference position and thereby is conditioned to store electronic image signals thereon.

4. The apparatus of claim 3 wherein said release means comprises switch means for generating a start signal.

5. The apparatus of claim 4 wherein said switch means is manually operable.

6. Apparatus for synchronizing the imaging of a scene by first and second cameras having respective shutters wherein said cameras may exhibit different shutter release delays when trigger signals are supplied thereto, and one camera includes a rotary record disk to store electronic image signals and said record disk has a reference position, said apparatus comprising:

reference pulse means for providing a reference pulse when said disk rotates to said reference position and thereby is conditioned to store electronic image signals thereon;

release switch means for generating a start signal operable to initiate triggering of the shutters in said first and second cameras;

drive signal generating means including retiming means for synchronizing said start signal generated by said switch means with said reference pulse provided by said reference pulse means to produce a drive signal;

first and second trigger means responsive to said drive signal for producing first and second trigger signals to release the shutters of said first and second cameras, respectively; and

delay means for delaying one of said trigger signals with respect to the other by a delay amount substantially equal to the difference in the shutter release delays of said cameras.

7. Apparatus for synchronizing the imaging of a scene by first and second cameras having respective shutters wherein said cameras may exhibit different shutter release delays when trigger signals are supplied thereto, said apparatus comprising:

release means operable to initiate triggering of the shutters in said first and second cameras;

drive signal generating means responsive to the operation of said release means for generating a drive signal synchronized to the conditioning of at least one of the cameras to record an image of the scene;

first and second trigger means responsive to said drive signal for producing first and second trigger signals to release the shutters of said first and second cameras, respectively; and

control means coupled to said drive signal generating means and including delay means for delaying one of said trigger signals with respect to the other by a delay amount substantially equal to the difference in the shutter release delays of said cameras, said control means responding to said drive signal for activating one of said trigger means directly to apply a trigger signal to one camera and for activating the other of said trigger means after a delay equal to said delay amount to apply a trigger signal to the other camera.

8. The apparatus of claim 7 wherein said control means includes learning means operable in a learning mode for determining the shutter release delay of said first camera and the shutter release delay of said second camera, and difference means for obtaining the difference between the respective shutter release delays to establish said delay amount.

9. The apparatus of claim 8 wherein each of said first and second cameras includes a PC output for producing a pulse when the shutter therein obtains a predetermined position;

and wherein said learning means includes first shutter release determining means for determining a first time delay between a first trigger signal that releases the shutter of said first camera and the pulse produced by the PC output of said first camera, and second shutter release determining means for determining a second time delay between a second trigger signal that releases the shutter of said second camera and the pulse produced by the PC output of said second camera.

10. The apparatus of claim 9 wherein said delay means includes first and second delay registers for selectively delaying the activation of said first or second trigger means, respectively, by said delay amount;

and wherein said control means includes means for loading said delay amount into said first delay register to delay said first trigger signal when the determined second time delay exceeds the determined first time delay and means for loading said delay amount into said second delay register to delay said second trigger signal when the determined first time delay exceeds the determined second time delay.

11. The apparatus of claim 7 wherein each of said cameras includes a PC output for producing a pulse when the shutter therein obtains a predetermined position;

and wherein said control means includes programmable means operable in a learning mode to activate said first and second trigger means concurrently, to determine a first shutter release delay substantially equal to a time delay between the activation of said first trigger means and the pulse produced by the PC output of said first camera, to determine a second shutter release delay substantially equal to a time delay between the activation of said second trigger means and the pulse produced by the PC output of said second camera, to determine said delay amount by obtaining a difference between said first and second shutter release delays, and to delay by said delay amount the trigger signal to be applied to the camera having the smaller shutter release delay.

12. The apparatus of claim 11 wherein said programmable means is operable in a shooting mode to respond to said drive signal to activate the one trigger means which applies a trigger signal to the camera having the larger shutter release delay, to activate the other trigger means after a delay equal to said delay amount, to determine a time difference in the times of occurrence of the pulses produced by the PC outputs of said first and second cameras, and to adjust said delay amount as a function of an average of a predetermined number of said time differences.

13. The apparatus of claim 12 wherein said programmable means is further operable in said shooting mode to sense if said time difference exceeds a preset amount and, if so, to produce an indication thereof.

14. Photo-proofing apparatus comprising:

a film camera having a releasable shutter for imaging a scene to be photographed onto a film medium and exhibiting a first shutter release delay from the time that the shutter therein is released until the time that said shutter is opened;

a still video camera having a releasable shutter for imaging said scene onto a record medium and exhibiting a second shutter release delay from the time that the shutter therein is released until the time that said shutter is opened, said record medium being movable past a reference position;

beam splitting means for projecting substantially identical images of said scene to be photographed to said film camera and to said video camera;

start means for generating a start signal; and

control means responsive to the start signal to release the shutter of one of said cameras at a first time and to release the shutter of the other camera at a second, delayed time, the delay being substantially equal to a difference between said first and second shutter release delays.

15. The apparatus of claim 14 wherein said start means includes trigger means for generating said start signal, and synchronizing means for synchronizing the start signal with the movement of said record medium to said reference position.

16. The apparatus of claim 15 wherein said video camera includes pulse generating means for generating a reference pulse each time said record medium moves to said reference position.

17. The apparatus of claim 16 wherein said synchronizing means comprises timing means for timing said start signal to occur when a reference pulse is generated, thereby producing a synchronized start signal delayed from the start signal generated by said trigger means.

18. The apparatus of claim 17 wherein said control means is operable to apply the synchronized start signal to said one camera as a shutter release signal to release the shutter therein.

19. The apparatus of claim 18 wherein said control means includes delay means responsive to said synchronized start signal to supply to said other camera a delayed shutter release signal to release the shutter therein.

20. The apparatus of claim 19 wherein each of said cameras includes a PC output for providing a respective shutter-open pulse when the shutter therein is opened;

and said control means includes delay adjust means for adjusting the delay of said delay means as a function of a time difference in the shutter-open pulses provided by the respective PC outputs.

21. The apparatus of claim 20 wherein the delay of said delayed shutter release signal applied to said other camera is reduced if the shutter-open pulse provided by the PC output of said other camera lags the shutter-open pulse provided by the PC output of said one camera, and the delay is increased if the shutter-open pulse provided by the PC output of said other camera leads the shutter-open pulse provided by the PC output of said one camera.

22. The apparatus of claim 20 wherein said control means further includes means for sensing said time difference in the shutter-open pulses provided by the respective outputs, and means for indicating if this time difference exceeds a threshold amount.

23. The apparatus of claim 14 wherein said control means includes learning means selectively operable in a learning mode to measure said first and second shutter release delays and to determine the difference therebetween.

24. The apparatus of claim 23 wherein each of said cameras includes a PC output for providing a respective shutter-open pulse when the shutter therein is opened;

and said learning means includes means for applying said start signal substantially concurrently to said film and video cameras as a shutter release signal;

means for detecting shutter-open pulses provided by the PC outputs of the respective cameras;

measuring means for measuring the delay between the start signal and the shutter-open pulse provided by the PC output of said film camera indicative of said first shutter release delay and for measuring the delay between the start signal and the shutter-open pulse provided by the PC output of said video camera indicative of said second shutter release delay; and

means for storing the difference between the measured delays.

25. The apparatus of claim 24 wherein said control means comprises a programmable processor.

26. The apparatus of claim 14 wherein said record medium comprises a rotatable magnetic disk.

27. A method for synchronizing the imaging of a scene by two cameras, both of which include releasable shutters and at least one of which includes a storage medium for storing electronic image signals, said cameras exhibiting different shutter release delays τ

₁ and τ

₂ from the time that the shutter therein is released until the time that said shutter arrives at its fully opened position, said method comprising the steps of initiating the release of both shutters;

timing both shutters to release at a time t_a in response to said initiation when the storage medium in said one camera is conditioned to store electronic image signals; and

delaying by an amount Δ

T the release of the shutter of one camera relative to the release of the shutter of the other as a function of the difference in the respective shutter release delays of said cameras (Δ

T=τ

₁ -τ

₂) so that the shutters of both cameras arrive at their fully opened positions at substantially the same time t, where t=t_a +τ

₁ =t_a +Δ

T+τ

₂.

28. The method of claim 27 wherein the step of timing both shutters to release when the storage medium in said one camera is conditioned to store electronic image signals comprises generating a synchronizing pulse when said storage medium is so conditioned, and generating a trigger signal in response to said synchronizing pulse if the release of both shutters has been initiated.

29. The method of claim 28 wherein the step of delaying the release of the shutter of one camera relative to the release of the shutter of the other comprises releasing the shutter of the camera having the larger shutter release delay substantially immediately when said trigger signal is generated;

and releasing the shutter of the other camera at a time delayed by said difference when said trigger signal is generated.

30. The method of claim 29 wherein said storage medium comprises a rotatable record disk and said synchronizing pulse is generated when said record disk rotates to a reference position.

31. The method of claim 29 further comprising the steps of detecting when each respective shutter is opened, and varying the delay with which the shutter of said other camera is released as a function of a difference in the time at which the respective shutters open.

32. A method for synchronizing the imaging of a scene by two cameras, both of which include releasable shutters and at least one of which includes a storage medium for storing electronic image signals, said cameras exhibiting different shutter release delays from the time that the shutter therein is released until the time that said shutter is opened, said method comprising the steps of initiating the release of both shutters;

generating a synchronizing pulse when the storage medium in said one camera is conditioned to store electronic image signals;

generating a trigger signal in response to said synchronizing pulse if the release of both shutters has been initiated;

releasing the shutter of the camera having the larger shutter release delay substantially immediately when said trigger signal is generated;

releasing the shutter of the other camera at a time delayed by the difference in the respective shutter release delays of the cameras when said trigger signal is generated;

detecting when each respective shutter is opened;

sensing a difference in the times at which both shutters open in response to the respective releases thereof, averaging the sensed differences over a predetermined number of releases, and selectively increasing or decreasing the delay with which the shutter of said other camera is released substantially by the average of the sensed differences.

33. A method for synchronizing the imaging of a scene by two cameras, both of which include releasable shutters and at least one of which includes a storage medium for storing electronic image signals, said cameras exhibiting different shutter release delays from the time that the shutter therein is released until the time that said shutter is opened, said method comprising the steps of initiating the release of both shutters;

generating a synchronizing pulse when the storage medium in said one camera is conditioned to store electronic image signals;

generating a trigger signal in response to said synchronizing pulse if the release of both shutters has been initiated;

releasing the shutter of the camera having the larger shutter release delay substantially immediately when said trigger signal is generated;

releasing the shutter of the other camera at a time delayed by the difference in the respective shutter release delays of the cameras when said trigger signal is generated;

detecting when each respective shutter is opened;

varying the delay with which the shutter of said other camera is released as a function of a difference in the time at which the respective shutters open;

sensing if the shutter of one camera opens at a time that differs from the opening of the shutter of the other camera by more than a threshold amount, and providing an indication thereof.

34. A method for synchronizing the imaging of a scene by two cameras, both of which include releasable shutters and at least one of which includes a storage medium for storing electronic image signals, said cameras exhibiting different shutter release delays from the time that the shutter therein is released until the time that said shutter is opened, said method comprising the steps of initiating the release of both shutters;

timing both shutters to release in response to said initiation when the storage medium in said one camera is conditioned to store electronic image signals;

determining the difference between the respective shutter release delays of said cameras; and

delaying the release of the shutter of one camera relative to the release of the shutter of the other as a function of said difference in the respective shutter release delays of said cameras.

35. The method of claim 34 wherein the step of determining the difference between the respective release delays of said cameras comprises measuring the respective shutter release delays of both cameras, obtaining a difference between the measured shutter release delays, identifying the camera exhibiting the smaller shutter release delay, and providing a delay substantially equal to said difference to the release of the shutter of the camera exhibiting the smaller shutter release delay.

36. The method of claim 35 wherein the step of measuring comprises releasing the shutters of both cameras concurrently when the release of both shutters has been initiated.