| 摘要 |
PURPOSE: To automatically adjust picture height in different screen formats and to enable centering by modulating a deflection signal and keeping the relation of a deflection voltage with a reference voltage to a desired value after the deflection voltages in the start and the last of a valid picture time are respectively compared with first and second reference voltages and the part of a luster picture is controlled. CONSTITUTION: Signal pulses (Vs1, Vs2) indicating the start and the last of the valid picture time are generated and the deflection voltage (Vtm) is stored in the start of the valid picture time. Then, the stored deflection voltage (Vtm) is compared with the reference voltage (Vtmref) and, then, the deflection voltage after fly-back is controlled so as to deep the relation of the two voltages to the desired value. The deflection voltage (Vbm) is stored in the last of a valid voltage time, the stored deflection voltage (Vbm) is compared with another reference voltage and, after that, a deflection voltage signal is modulated so as to keep the relation of the two voltages to the desired value. Therefore, even in the case of the different screen format, the display of the vertical mergin of the picture is made to be fixed. Thus, automatic picture height adjustment and centering are executed. |
