Circuit for preventing high-intensity false color caused by color separation filters

• US 4,974,066 A
• Filed: 02/27/1989
• Issued: 11/27/1990
• Est. Priority Date: 04/14/1988
• Status: Expired due to Term

• Current Assignee: Olympus Optical Corporation Limited (Olympus Corporation)
• Original Assignee: Olympus Optical Corporation Limited (Olympus Corporation)
• Inventors: Tusji, Kiyoshi
• Primary Examiner(s): Shepperd, John W.
• Application Number:
  US07/315,770
• Time in Patent Office: 638 Days
• Field of Search: 358/36, 358/43, 358/42, 358/44, 358/98, 358/47
• US Class Current: 348/242
• CPC Class Codes: H04N 23/555 for picking-up images in sites, inaccessible due to their dimensions or hazardous conditions, e.g. endoscopes or borescopes
• CPC Class Codes: H04N 23/84 for processing colour signals
• CPC Class Codes: H04N 25/136 using complementary colours

Abstract

A luminance signal and a color signal are separated from a color picture signal output from an imaging device with a plurality of color filters mounted thereon. The color filters are saturated at different intensity levels. This luminance signal is delayed to generate two delayed signals that respectively cover the front and rear edges of the color signal and a delayed signal that covers the interval between these edges. The color signal is suppressed by these delayed signals when the incident light has a high intensity, thereby preventing false color from occurring due to the incident light having a high intensity.

Claims

1. A false color preventing circuit for generating a standard color video signal from a color picture signal output from an imaging device with a plurality of color filters provided therein, said color filters being saturated at different intensities of light, said false color preventing circuit comprising:

signal generating means for generating, from said color picture signal, a luminance signal having a wide bandwidth and a color signal having a narrow bandwidth;

first and second delay means for generating first and second delayed signals that respectively cover front and rear edges of said color signal be delaying said luminance signal;

third delay means for generating at least a third delayed signal which has been delayed in time more than said first delayed signal generated by said first delay means and delayed less in time than said second delayed signal generated by said second delay means wherein said third delayed signal covers an interval between said first and second delayed signals;

suppressing signal generating means for generating a suppressing signal using said first, second and third delayed signals;

color signal suppressing means for suppressing said color signal by said suppressing signal; and

mixing means for generating said standard color video signal by mixing said color signal which has been suppressed by said color signal suppressing means with said luminance signal.

2. A false color preventing circuit according to claim 1, wherein said first, second and third delay means are formed by a delay line with a plurality of taps corresponding to the different delay times.

3. A false color preventing circuit according to either claims 1 or 2, wherein at least one delay time of said first, second and third delay means is made variable, said at least one delay time being varied by a switch-over means.

4. A false color preventing circuit according to either claims 1, or 2, wherein said mixing means generates a composite color video signal.

5. A false color preventing circuit comprising:

an imaging device with a plurality of color filters mounted on an imaging surface thereof for color separation, said color filters being saturated at different intensity levels, said imaging device being capable of photoelectric conversion;

a driving circuit for applying a driving signal to said imaging device;

signal generating means for generating a luminance signal and a color signal from a color picture signal output from said imaging device by application of said driving signal;

first and second delay means for generating first and second delayed signals that respectively cover front and rear edges of said color signal by delaying said luminance signal;

third delay means for generating at least a third delayed signal which has been delayed in time more than said first delayed signal generated by said first delay means and delayed less in time than said second delayed signal generated by said second delay means wherein said third delayed signal covers an interval between said first and second delayed signals;

suppressing signal generating means for generating a suppressing signal using said first, second and third delayed signals;

color signal suppressing means for suppressing said color signal by said suppressing signal; and

mixing means for generating a standard color video signal by mixing said color signal which has been suppressed by said color signal suppressing means with said luminance signal.

6. A false color preventing circuit according to claim 5, wherein said imaging device is accommodated in a TV camera.

7. A false color preventing circuit according to claim 5, wherein a TV camera can be mounted on an eyepiece portion of a fiberscope having an elongated inserted portion.

8. A false color preventing circuit according to claim 5, wherein said imaging device is disposed at a forward end of an elongated inserted portion of an electronic scope.