Video camera apparatus having solid state imager

• US 5,283,655 A
• Filed: 09/15/1992
• Issued: 02/01/1994
• Est. Priority Date: 09/30/1991
• Status: Expired due to Term

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Usami, Makoto
• Primary Examiner(s): RAZAVI, MICHAEL
• Assistant Examiner(s): Colaianni, Joseph
• Application Number:
  US07/944,952
• Time in Patent Office: 504 Days
• Field of Search: 358/228, 358/213.16, 358/171, 358/213.13, 358/221
• US Class Current: 348/257
• CPC Class Codes: H04N 25/447 by preserving the colour pattern with or without loss of information
• CPC Class Codes: H04N 25/63 applied to dark current
• CPC Class Codes: H04N 25/683 by defect estimation performed on the scene signal, e.g. real time or on the fly detection
• CPC Class Codes: H04N 25/70 SSIS architectures; Circuits associated therewith
• CPC Class Codes: H04N 25/75 Circuitry for providing, modifying or processing image signals from the pixel array
• CPC Class Codes: H04N 5/165 to maintain the black level constant
• CPC Class Codes: H04N 9/73 Colour balance circuits, e.g. white balance circuits or colour temperature control camera processing pipelines for colour balance H04N23/88

Abstract

A video camera apparatus having a solid state imager for generating video signals and a black level balance adjusting circuit for automatically adjusting black levels of the video signals. The video camera apparatus comprises an incident light control device, an electronic shutter control circuit, a comparator and a processor. The incident light control device controls the amount of light incident to the solid state imager. The electronic shutter control circuit varies the mode of the solid state imager between at least a first mode and a second mode. The effective accumulating period of the solid state imager in the first mode is different from the corresponding period in the second mode. The comparator compares the voltage level of the video signal obtained in the first mode with that obtained in the second mode. The processor controls the electronic shutter control circuit and the comparator, and activates the black level balance adjusting circuit when the voltage levels of the video signals obtained in the first and the second modes are substantially the same.

Claims

1. A video camera apparatus comprising:

variable mode solid state imaging means for generating video signals and having an effective accumulating period, said video signals having voltage levels which are a function of the accumulating period,

black level balance adjusting means for automatically adjusting black levels of said video signals;

incident light control means for controlling the amount of light incident to said solid state imaging means;

electronic shutter control means for varying the mode of said solid state imaging means between at least a first mode and a second mode, the effective accumulating period of said solid state imaging means in said first mode being of different temporal duration than the effective accumulating period in said second mode;

comparator means for comparing the voltage level of the video signal obtained in said first mode with that obtained in said second mode; and

processing means for controlling said electronic shutter control means and said comparator means, and for activating said black level balance adjusting means when the voltage levels of said video signals obtained in said first and said second modes are substantially the same.

2. A video camera apparatus according to claim 1, wherein said incident light control means is a mechanical iris which can be operated automatically.

3. A video camera apparatus according to claim 1, wherein said processing means activates said black level balance adjusting means when the difference between the voltage levels of said video signals obtained in said first and said second modes is less than a predetermined voltage level.

4. A video camera apparatus according to claim 1, wherein said said electronic shutter control means repeats the varying of the mode of said solid state imaging means between said first mode and said second mode when the voltage levels of said video signals obtained in said first mode and those obtained in said second mode are not substantially the same.

5. A video camera apparatus according to claim 4, further including means for activating said processing means.

6. A video camera apparatus according to claim 5, wherein said processing means stops controlling said electronic shutter control means and said comparator means when a predetermined time has elapsed after activation of said processing means.

7. A video camera apparatus according to claim 6, further comprising means for indicating warning information when said predetermined time has elapsed after activation of said processing means.

8. An apparatus for detecting an absence of light incident on a solid state imaging means having an effective accumulating period and having different operating modes, said apparatus comprising:

electronic shutter control means for controlling the effective accumulating period of said solid state imaging means and for varying the mode of said solid state imaging means between at least a first mode and a second mode, the effective accumulating period of said solid state imaging means in said first mode being of different temporal duration than the corresponding period in said second mode such that said solid state imaging means produces video signals having voltage levels which are a function of the accumulating period;

a comparator means for comparing the voltage level of the video signal obtained in said first mode with that obtained in said second mode so as to produce a difference between the voltage levels of the video signals obtained in said first and second modes; and

means for detecting the absence of incident light when the difference between the voltage levels of said video signals is less than a predetermined voltage level.

9. A method for detecting an absence of light incident on a solid state imaging means having an effective accumulating period controlled by electronic shutter control means, said method comprising the steps of:

generating a voltage level of a video signal derived from said solid state imaging means in a first effective accumulating period;

generating a voltage level of a video signal derived from said solid state imaging means in a second effective accumulating period which is of different temporal duration than said first effective accumulating period;

producing a difference between voltage levels of the video signals obtained in said first and said second effective accumulating periods; and

detecting the absence of incident light when the difference between the voltage levels of said video signals is less than a predetermined voltage.