Patent ID: 6097445
Filing Date: 2000-08-01
Classification: H04N

Abstract:
A color display with a white balance self-adjusting function, comprising:a DC-voltage-level and gain adjusting circuit for receiving adjustment digital data, and adjusting, on the basis of the received adjustment digital data, the DC voltage level and the gain of each signal passing through an input line for one of the group of R, G and B color signals, thereby outputting the adjusted signals;a CRT driving circuit for receiving the output signals of the DC-voltage-level and gain adjusting circuit, and outputting driving signals;a color CRT having cathode electrodes corresponding to the R, G and B color signals, the color CRT performing display when the driving signals of the CRT driving circuit are applied to the cathode electrodes;a cathode current detecting circuit connected to the cathode electrodes of the color CRT for detecting cathode currents corresponding to the R, G and B color signals; anda control circuit of a program control method connected to the cathode current detecting circuit and including non-volatile memories with pre-stored data,wherein the control circuit operates by following steps of:a first processing step of reading out the data pre-stored in the non-volatile memories for a predetermined period of time after turning on the display the pre-stored data read out in the first processing step being supplied to the DC-voltage-level and gain adjusting circuit, thereby setting the DC-voltage-level and the gain in the DC-voltage-level and gain adjusting circuit;a second processing step of detecting whether adjustment is requested;a third processing step of selecting black and white reference level voltages when the adjustment is requested;a fourth processing step of comparing detection values which are detected from the cathode current detecting circuit after the DC-voltage-level and the gain are set in the DC-voltage-level and gain adjusting circuit based on the data read out in the first processing step, with the black and white reference level voltages selected in the third processing step; anda fifth processing step of (i) updating the data stored in the non-volatile memories: or (ii) stopping updating of the data, on the basis of comparison results, the data updated in the fifth step being imparted to the DC-voltage-level and gain adjusting circuit, thereby re-setting the DC-voltage-level and the gain in the DC-voltage-level and gain adjusting circuit.