Bias circuit to prevent distortion of color in a cathode ray tube

An apparatus to prevent color distortion in a cathode ray tube by stabilizing a color ratio of at least two color component bias voltages of a video signal, the apparatus comprising:

• a bias voltage amplifying stage to receive the at least two color component bias voltages of a video signal, to separately amplify the at least two color component bias voltages, and to output the at least two color component bias voltages;
• an addition amplifying stage to receive the amplified at least two color component bias voltages from the bias voltage amplifying stage, to separately add each of the at least two color component bias voltages to a brightness control voltage, and to separately amplify the added color component bias voltages;
• and
• an inverting amplifying stage to receive the amplified at least two color component bias voltages, to restore the amplified at least two color component bias voltages to have the color ratio, and to output the amplified at least two color component bias voltages to a cathode in the cathode ray tube.

An apparatus to prevent color distortion in a cathode ray tube by maintaining the same color ratio between color bias voltages before and after brightness of a display is changed, the apparatus comprising:

• a first amplifying means to amplify at least first and second color bias voltages having a color ratio;
• a second amplifying means to receive the first and second color bias voltages from the first amplifying means, to add a brightness control voltage to the first and second color bias voltages, and to amplify the added first and second color bias voltages;
• and
• a third amplifying means to receive the amplified first and second color bias voltages from the second amplifying means, to restore the color ratio between the amplified first and second color bias voltages, and to output the amplified first and second bias color voltages.

A video display apparatus, comprising:

• a bias circuit to prevent color distortion in a cathode ray tube when changing brightness in a display screen by equalizing a color ratio of at least a first color bias voltage and a second color bias voltage of a video signal, the bias circuit including:
• a bias voltage amplifier to separately amplify at least the first color bias voltage and the second color bias voltage,
• an addition amplifier to receive at least the first color bias voltage and the second color bias voltage from the bias voltage amplifier, to receive a brightness control voltage that determines an amplification rate of at least the first color bias voltage and the second color bias voltage, to separately add the brightness control voltage to at least the first color bias voltage and the second color bias voltage, and to amplify at least the first color bias voltage and the second color bias voltage, respectively, and
• an inverting amplifier to receive the amplified at least the first color bias voltage and the second color bias voltage and to compensate for distortion by restoring the color ratio between the amplified at least the first color bias voltage and the amplified second color bias voltage and to output at least the amplified first color bias voltage and the amplified second color bias voltage.

A method of preventing color distortion in a cathode ray tube while changing brightness in a display screen, the method comprising:

• receiving a change in a brightness control voltage and receiving at least two color bias voltages having a color ratio from a video signal;
• performing a first amplifying operation on the at least two color bias voltages;
• separately adding the brightness control voltage to the at least two color bias voltages and performing a second amplifying operation on the at least two color bias voltages;
• and
• performing a third amplifying operation on the at least two color bias voltages and restoring the color ratio to the at least two color voltages.