| 摘要 |
PROBLEM TO BE SOLVED: To detect an electron beam scanning position in real time even when a display screen size and a scanning frequency, etc., are changed by correcting a counted value from a counting part based on a correction value and obtaining the horizontal scanning position coordinate of an electron beam. SOLUTION: In a figure showing the specifications of the two points of a horizontal scanning direction coordinate and a vertical scanning direction coordinate set on a CRT screen, the screen 1 of a CRT display, a display area 2 where images and characters, etc., are displayed and sawtooth-shaped waves 3 for indicating a voltage waveform for which the absolute value of a deflection current made to flow through the horizontal direction deflection coil of a CRT is converted to a voltage are displayed. Then, a timing that the electron beam is passed through by horizontal scanning on the screen is detected, counting is performed by the signals of a fixed cycle with the prescribed time phase of the horizontal scanning of the electron beam as a trigger, the correction value is calculated by comparing the counted value counted at the detected timing with the coordinate value of a reference point and the horizontal scanning position coordinate of the electron beam is obtained by correcting the counted value based on the correction value. |
