Solid-state color TV camera image size control

• US 4,521,804 A
• Filed: 02/25/1983
• Issued: 06/04/1985
• Est. Priority Date: 02/25/1983
• Status: Expired due to Term

• Current Assignee: RCA Corporation
• Original Assignee: RCA Corporation
• Inventors: Bendell, Sidney L.
• Primary Examiner(s): Masinick, Michael A.
• Application Number:
  US06/469,773
• Time in Patent Office: 830 Days
• Field of Search: 358/50, 358/51, 358/213, 357/24, 357/30, 357/31
• US Class Current: 348/263
• CPC Class Codes: H04N 23/15 Image signal generation with circuitry for avoiding or correcting image misregistration
• CPC Class Codes: H04N 23/16 Optical arrangements associated therewith, e.g. for beam-splitting or for colour correction

Abstract

The apparent size of the image produced by a clocked solid-state television imager is controlled by the read clock rate. In a camera using such an imager the clock rate is adjusted to provide an effect similar to zoom. Where a plurality of imagers are used in a color camera, differential control of the clock rate as between the imagers allows compensation for lens chromatic aberration thereby providing for correction of misregistration. In the case where the optical system includes a variable focal length such as a zoom lens, the zoom control is coupled to the size clock control for compensating for the differences in optical power for different colors. The size adjustment may result in a second-order centering error. The centering error is reduced by a scheme for changing the time at which the read clock is gated to the imager in dependence upon the clock rate.

Claims

1. An image size control arrangement for a color television camera, comprising:

first and second solid-state imagers, each including an array of discrete light-responsive regions and a buffer register;

optical means optically coupling a first color component of a scene to be imaged to said first imager and a second color component of said scene to be imaged to a second imager, said first and second color components being imaged to different sizes thereby causing color misregistration;

pull-down clock generating means coupled to said solid-state imagers for establishing the recurrent light integrating intervals of said arrays and for transferring signals representative of said scene from each of said arrays to its corresponding buffer register;

controllable clock signal generating means coupled to said buffer registers for applying respective clock signals to said respective buffer registers for controlling the rates of transfer of signals from said buffer registers, and further including rate control terminal means;

registration control means coupled to said rate control terminal means for controlling the rate of said respective clock signals, thereby controlling said rates of transfer of signals from said buffer register relative to each other so as to apparently change the size of said imaged color components whereby said misregistration is reduced; and

controllable application means coupled to said controllable clock signal generating means and responsive to a change in relative rates of said respective clock signals for controlling the relative times of application of said respective clock signals to said respective buffer registers in a manner so as to prevent movement of the apparent center of said imaged color components when their apparent size is changed.

3. An arrangement according to claim 1 wherein said controllable optical means comprises a zoom lens.

4. An arrangement according to claim 1 wherein said first and second imagers comprise a line array of light-responsive regions.

2. A color misregistration correction arrangement for a television camera comprising:

controllable optical means for forming images of a scene;

a first solid state imager coupled to said controllable optical means and responsive to a first spectral light distribution of at least one of said images, said first imager including a first array of individual light-responsive regions each of which produces an electrical signal representative of the amount of light falling thereon;

a second solid-state imager coupled to said controllable optical means and responsive to a second spectral light distribution different from said first spectral light distribution, said second imager including a second array of individual light responsive regions corresponding with said first array;

clock signal generating means for generating clock signals which are coupled to said first and second imagers for sequentially reading each of said electrical signals at a rate such that said first array is read within a reference time interval and said second array is read within a second time interval related to said reference time interval, whereby if said reference and said second time intervals remain constant color misregistration results when said controllable optical means is controlled, as a result of differing responses of said controllable optical means to said first and second spectral distributions, which causes variation in the sizes of the images to which said first and second imagers respond as said controllable optical means is controlled; and

clock control signal generating means coupled to be responsive to control of said controllable optical means and to said clock signal generating means for controlling said clock signals for controlling said second time interval relative to said reference time interval for compensating for said variations in the sizes of the images to which said first and second imagers respond for reducing said color misregistration when said controllable optical means is controlled.

5. An arrangement according to claim 2 wherein said first and second imagers each comprise a plurality of line arrays of light-responsive regions.

6. An array according to claim 2 wherein each of said first and second imagers comprises a line array of light-responsive regions and a parallel-to-serial buffer array to which said clock signal generating means is coupled.

7. An arrangement according to claim 2 further comprising:

application control means coupled to said clock signal generating means for controlling the relative starting times of said reference time interval and of said second time interval for controlling the apparent centering.

8. An arrangement according to claim 7 further comprising centering control means coupled to said application control means and to said controllable optical means for controlling said relative starting times as said controllable optical means is controlled.

9. An arrangement according to claim 2 further including controllable coupling means coupled to receive said clock signals and responsive to control of said optical means for delaying or advancing the relative timing of the clock signals coupled to said first and second imagers, respectively, so as to prevent change of the apparent center of said images to which said imagers respond when said time intervals are controlled.

10. A television image centering control arrangement comprising:

a solid-state imager including an array of discrete light-responsive regions and a buffer register;

optical means for optically coupling a scene to said imager for illuminating said array,

means for transferring signals representative of said scene from said array to said buffer register;

clock signal generating means for generating clock signals for controlling the rate of transfer of signals from said buffer register; and

controllable gating means coupled to said clock signal generating means and to said imager for relatively advancing or retarding the time of gating of said clock signals to said imager controlling the apparent center of said imager.

11. An arrangement according to claim 10 further including:

rate control means coupled to said clock signal generating means for controlling the rate of said clock signals, said controllable gating means being responsive to control of the rate of said clock signals for advancing or retarding the time of gating said clock signals in a manner which prevents change of the apparent center of said optically coupled scene.

12. An image control arrangement for a television camera comprising:

a first solid state imager including an array of discrete light-sensitive regions onto which in use incident light from a scene is optically imaged and from which signals representative of said scene are read out under the control of clock signals;

a controllable clock signal source coupled to said first imager;

a second solid state imager also responsive to said scene which is optically imaged thereon but subject to misregistration with respect to the scene optically imaged on said first imager and from which signals representative of said scene are read out under the control of clock signals from a further clock signal source;

a changeable optical system for providing first and second images of said scene to said first and second imagers, respectively, the size and/or effective position of said images tending to change as said optical system is changed resulting in said misregistration; and

a clock signal controller coupled to said controllable clock signal source and said changeable optical system and responsive to control signals indicative of change of said optical system so as to vary the timing of said clock signals coupled to said first imager in a manner influencing the size and/or effective position of the image represented by the signals read out from said first imager so as to compensate said changes in image size and/or position and reduce said misregistration.

13. An arrangement according to claim 12 wherein said control signals are indicative of a power change of said optical system.

14. An arrangement according to claim 12, further including controllable coupling means coupled to said clock signal controller and responsive to variation of said timing of said clock signals which changes the size of the image representeed by the signals read out from said first imager, for advancing or retarding the time of coupling said clock signals to said first imager relative to said second imager by an amount which prevents movement of the apparent center of said image representative signals read out from said first image.