Asynchronous still timing for a video camera producing movie or still images

• US 4,714,963 A
• Filed: 07/03/1986
• Issued: 12/22/1987
• Est. Priority Date: 07/03/1986
• Status: Expired due to Term

• Current Assignee: Eastman Kodak Company
• Original Assignee: Eastman Kodak Company
• Inventors: Vogel, Richard M.
• Primary Examiner(s): Rubinson, Gene Z.
• Assistant Examiner(s): Brinich, Stephen
• Application Number:
  US06/882,121
• Time in Patent Office: 537 Days
• Field of Search: 358/909, 358/213.31, 358/213.26, 358/213.19, 358/335, 358/228
• US Class Current: 348/220.1
• CPC Class Codes: H04N 23/73 by influencing the exposure time
• CPC Class Codes: H04N 25/00 Circuitry of solid-state image sensors [SSIS]; Control thereof
• CPC Class Codes: H04N 5/77 between a recording apparatus and a television camera

Abstract

A still video camera produces a movie image for previewing in an electronic viewfinder according to a specific image repetition rate and a still image for recording on a magnetic disk. In the movie mode, video signals are clocked from a solid-state, interline transfer image sensor by application of driving signals from a movie timing generator. The still mode interrupts the movie timing with a special driving signal from a still timing generator. By initiating the still exposure in synchronism with the high frequency movie driving signals that operate the image sensor . . . and not with regard to the vertical drive interval determining the image repetition rate . . . a "pseudo"-asynchronous relationship can be obtained with the movie mode and the still exposure can begin without noticeable delay. After the still exposure is completed, control of the image sensor is returned to the movie timing generator in synchronism with the image repetition rate.

Claims

1. A still video camera of the type having an image sensor that generates a charge pattern in response to image light from an object and operates thereupon either as a signal source for a movie image, according to a specific image repetition rate, or as a signal source for a still image, the camera further including a release switch for initiating a still exposure period, said camera comprising:

means for generating a continuous stream of movie phasing signals for operating upon the charge in the image sensor at a rate that is substantially greater than the image repetition rate;

transfer means for applying said movie phasing signals to the image sensor when the image sensor operates as a signal source for a movie image;

means for generating a still phasing signal for operating the image sensor as a signal source for a still image; and

means responsive to actuation of the release switch for interrupting the application of said movie phasing signals to the image sensor and for substituting therefor said still phasing signal synchronously with respect to said movie phasing signals and asynchronously with respect to said image repetition rate.

2. The camera as claimed in claim 1 further including:

means for generating an end exposure signal at the end of the still exposure period; and

means responsive to said end exposure signal for directing said transfer means to resume application of said movie phasing signals to the image sensor.

3. The camera as claimed in claim 2 in which said movie phasing signals are resumed in synchronism with the image repetition rate.

4. The camera as claimed in claim 3 in which said image sensor is of the type that has one or more light-protected storage elements for temporarily storing the image-wise charge pattern until it can be removed from the sensor, said movie phasing signal generating means initiating the transfer of charge to the storage elements at an image repetition rate corresponding to field intervals, said still phasing signal generating means initiating the transfer of image charge to the storage elements after the end of the still exposure period, and said means responsive to said end exposure signal resuming application of said movie phasing signals at the beginning of a subsequent field interval.

5. A still video camera of the type that includes an electronic viewfinder for previewing a video image of an object and an image sensor that generates a charge pattern in response to image light from the object, said image sensor operating either as a signal source for the viewfinder according to a specific image repetition rate or as a signal source for a still image processed by the camera, the camera further including a diaphragm for regulating the aperture presented to the image light and a release switch for initiating a still exposure period, said camera comprising:

means for generating a continuous stream of movie phasing signals for operating the image sensor according to a specific frequency multiple of the image repetition rate;

means for generating at least one still phasing signal for operating the image sensor as a signal source for a still image;

transfer means for applying either said movie or said still phasing signals to the image sensor when the image sensor operates respectively as a signal source for either the viewfinder or for a still image;

means responsive to actuation of the release switch and initiated in synchronism with said movie phasing signals for setting the diaphragm to a predetermined still aperture;

means responsive to said still phasing signal and to the setting of said predetermined still aperture for initiating the still exposure period;

means for generating an end exposure signal at the end of the still exposure period; and

means responsive to said end exposure signal for triggering said transfer means to resume application of said movie phasing signals to the image sensor.

6. The camera as claimed in claim 5 in which said transfer means resumes application of said movie phasing signals to the image sensor in synchronism with the image repetition rate.

7. The camera as claimed in claim 6 in which said image repetition rate corresponds to a video field frequency and said transfer means resumes application of said movie phasing signals to the image sensor in synchronism with the beginning of a video field.

8. A still video camera of the type that includes an electronic viewfinder for previewing a video image of an object and a clocked image sensor having charge-generating photosites and at least one charge-coupled register for transferring image charge from the photosites, said image sensor operating upon the image charge either as a signal source for the viewfinder or as a signal source for a still image processed by the camera, the camera further including a diaphragm for regulating the aperture presented to image light and a release switch for initiating a still exposure period, said camera comprising:

means for generating a high frequency clock signal for operating upon the image charge in the sensor;

movie timing means responsive to said clock signal for generating a low frequency movie driving signal for moving image charge from the photosites of the image sensor to the register in correspondence with a specific image repetition frequency;

still timing means responsive to said clock signal for generating a still driving signal for operating the image sensor during the still exposure period;

control means for engaging either said movie timing means or said still timing means in the operation of the image sensor, said control means having a preview state in which said movie driving signal is passed to the image sensor and a still exposure state in which said still driving signal is passed to the image sensor;

means responsive to actuation of said release switch for engaging said control means in its still exposure state so that control of the image sensor in its still exposure state is initiated in time-dependent relation to the clock period of said clock signal and in substantial time-independent relation to the image repetition frequency;

means for generating an end exposure signal at the end of the still exposure period; and

means responsive to said end exposure signal for reengaging said control means in its preview state in time-dependent relation to the image repetition frequency, thereby returning control of the image sensor to said movie timing means.

9. A still video camera that includes an electronic viewfinder for previewing a video image of an object before a still image is processed by the camera, said still video camera comprising:

means for generating a high frequency clock signal;

movie timing means for generating a movie driving signal that is a frequency submultiple of said clock signal;

still timing means for generating a still driving signal that regulates the length of the still exposure;

an image sensor that receives image light from the object and generates a sensor signal therefrom, said image sensor being (a) under control of said movie timing means when operated as a signal source for the viewfinder, said movie driving signal initiating the removal of the sensor signal from said image sensor at set video intervals according to said movie driving signal, and (b) under control of said still timing means when operated as a signal source for the still image;

an exposure release switch for initiating a still exposure;

means responsive to initiation of a still exposure for transferring control of said image sensor from said movie timing means to said still timing means in time-related synchronism with respect to said clocking signal; and

means responsive to the end of the still exposure for transferring control of the image sensor back to the movie timing means in time-related synchronism with respect to said movie driving signal.

10. The camera as claimed in claim 9 further including:

a diaphragm for regulating the optical aperture of said image sensor to the image light and wherein said still timing means initially provides a diaphragm-adjusting signal to said diaphragm for setting a predetermined still aperture.

11. The camera as claimed in claim 10 further including:

means responsive to the termination of said diaphragm adjusting signal for beginning the still exposure of the image sensor.