# US 5,345,275 A · Color temperature selection circuitry having color matrix correction

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- Number: US 5,345,275 A
- Document ID: US5345275A
- Status: Granted
- Kind: A
- Application number: 08/015,241
- Filed: 1993-02-04
- Granted: 1994-09-06
- Earliest claimed: 1993-02-04
- Assignees: Thomson Consumer Electronics, Inc.
- Inventors: Jeffery B. Lendaro
- Web page: https://patentgrep.com/patent/US5345275A

## CPC

- H04N 9/73: Colour balance circuits, e.g. white balance circuits or colour temperature control (camera processing pipelines for colour balance H04N23/88)
- H04N 9/67: for matrixing (camera processing pipelines for matrixing of colour signals H04N23/85)
- H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION

## Abstract

In a television receiver including a feature allowing a user to select a color temperature at which whites will be produced on a display screen, circuitry is provided for altering the gain of the red and blue kine driver stages and simultaneously automatically altering the gain of the R-Y and B-Y color difference signal amplifier, to correct for errors which would otherwise be introduced by adversely altering the B-Y/R-Y ratio.

## Claims

### Claim 1

In a color television system, apparatus comprising:
means for altering the gain of one of a red color signal amplifier and a blue color signal amplifier to affect the temperature of a white area displayed on a display screen; and
means for controlling the gain of a respective one of an R-Y color difference amplifier and a B-Y color difference amplifier concurrently and in the opposite sense to the alternation of the gain of said one of said red color signal amplifier and said blue color signal amplifier.

### Claim 2 (depends on 1)

The system of claim 1, wherein:
said gain-altering means of said red color signal amplifier and said blue color signal amplifier comprises a switch for reducing the emitter resistance of one of said red color signal amplifier and said blue color signal amplifier.

### Claim 3 (depends on 2)

The system of claim 2, wherein:
said gain-altering means of said R-Y color difference amplifier and a B-Y color difference amplifier comprises a switch for reducing the emitter resistance of one of said R-Y color difference amplifier and a B-Y color difference amplifier.

### Claim 4 (depends on 3)

The system of claim 3, wherein:
said switch for reducing the emitter resistance of said B-Y color difference amplifier and said switch for reducing the emitter resistance of said blue color signal amplifier operate substantially simultaneously and inversely.