CCD TELEVISION CAMERA

Abstract: A single-bit video output is obtained from the two analog outputs of a CCD sensor by digitizing each video output, multiplexing the resulting two digital outputs, and passing the result to a comparator; one such output passing through a digital filter.

Description: CCD TELEVISION CAMERA TECHNICAL FIELD This invention pertains to digital processing of video signals. BACKGROUND ART The video processor per se is a known device. U.S. patent No. 4,399,470, entitled "Optical Scanning System", to Earl R. Hibbard, discloses one type of this device. This processor, as usual, is applied to the video signal after it has been generated by an image sensor device. SUMMARY OF THE INVENTION A solid-state light sensor, such as the charge- coupled-device ("CCD") type, typically provides two electrical outputs, which outputs must be combined to obtain the desired output signal.. When, according to the prior art, these outputs are retained and processed in analog form, the combined output is not easily obtained. Also the many processing steps each introduce noise and signal degredation problems. However, • according to this invention, the two outputs are individually changed to digital form as soon* as available. This is so that circuit noise will be largely eliminated. t In addition, a dynamic thresholding technique is used to derive a variable reference signal, which describes the transition from "black." to "white" , and vice versa. This is implemented by means of a known digital filter. BRIEF DESCRIPTION OF DRAWINGS Fig. 1 is a block diagram of the circuit. BEST MODE FOR CARRYING OUT THE INVENTION Optically represented subject matter in Fig. 1 is imaged upon a line of CCD photosites of sensor 2 by lens 3. Typically, electrical scanning is accomplished along that line and successive lines of subject matter are presented by movement of the subject matter at right angle ' s' to the line of CCD photosites. An alternate embodiment of sensor 2 has a two- dimensional mosaic of photosites. Two dimensional television scanning is accomplished electrically. In Fig. 1, digital control circuits 8 supply a square-wave of, say, 16 megahertz frequency in the two phases X and T; these being at 90° to each other. Inventively, digitizer 4 is connected to the A output of CCD sensor 2, and digitizer 5 is separately connected to the B output of CCD sensor 2. There are 6 bit (for example) digital connections from each of these digitizers to multiplexer 10. An output therefrom becomes one input to comparator 7. The other input to comparator 7 is the output of multiplexer 10 passed through digital "FIR" non- recursive filter 12. The output from comparator 7 is a single-bit video output, suitable for video signal processing in the usual manner.

Claims: CLAIMS 1. The method of processing video signals from a CCD device that has one or more outputs, which includes the method steps of; (a) separately performing digitization on each of said outputs, and (b) subsequently digitally combining these outputs into one single-bit video signal for image processing. 2. The method of claim 1, in which the combining step includes the method steps of; (a) sampling the separate digital outputs at adjacent intervals of time, and (b) combining the sampled digital outputs in a single signal channel. 3. The method of calim 1, in which; (a) the plurality of outputs is two. 4. Apparatus for forming a single-bit video output from a CCD sensor (2) that has two digital control circuit inputs (jz.X and jz.T) and twp analog signal outputs (A & B) , said apparatus comprising; (a) a first digitizer (4) connected to a first said analog signal output (A) , (b) a second digitizer (5) connected to a second said analog signal output (B) , (c) a multiplexer (10) , having inputs connected by digital means to each of said first and second digitizers, and having a digital output, (d) a comparator (7) having a first input directly digitally connected to the digital output of said multiplexer (10) , and (e) a digital filter (12) , digitally connected to the output of said multiplexer and digitally connected to a second input of said comparator, to provide a single-bit video output from said comparator (7) .

Inventors: VAN DEN HEUVEL RAYMOND CHARLES, VAN DEN HEUVEL, RAYMOND, CHARLES
Applicants: TERMINAL DATA CORP, TERMINAL DATA CORPORATION
Application year: 1984
Main classification: H04N1
IPC codes: H04N1