EARTH MAGNETIC FIELD COMPENSATION CIRCUIT AND METHOD

摘要

PURPOSE: A circuit for correcting a terrestrial magnetism and a method therefor are to minimize the effect of magnetism which is not fully demagnetized by a degaussing coil, thereby enhancing a color tone. CONSTITUTION: A pattern generation unit(102) generates a test pattern for correcting a terrestrial magnetism. A terrestrial magnetism correction unit(105) adjusts a direction and an amount of current flowing through a degaussing coil(104) in response to a current direction signal(DIR) and a current amount signal(PWM) and corrects a display position of the text pattern displayed on a CRT screen. In a terrestrial magnetism correction mode, a micro-computer(101) makes the pattern generation unit to generate the test pattern and determines the direction and the amount of the current to generate the current direction signal and the current amount signal to the terrestrial magnetism correction unit. The current direction and the current amount are determined by adjusting the test pattern to a virtual line crossing through the center of the screen in a right direction of upper and lower sides.