DEFLECTION YOKE PHASE CHARACTERISTIC EVALUATION METHOD

PURPOSE:To attain direct evaluation of phase characteristic by offsetting a timing of a horizontal synchronizing signal and a vertical synchronizing signal of a signal device controlling a signal on a screen by a prescribed quantity, receiving a picture again, obtaining a gravity center of longitudinal and lateral lines and evaluating the phase characteristic of a deflection yoke from a difference of the gravity center of the width of illuminated part. CONSTITUTION:When a signal is displayed on a CRT screen 1, a signal with a known phase, that is, delayed by a time is generated in advance, the signals are picked up in terms of closeup by an ITV camera 9 alternately, the resulting digital picture is subjected to picture processing, the gravity center of plural fluorescent dot line width resulting from a grid stripe signal is obtained respectively from longitudinal lines and lateral lines, and the phase characteristic is measured by the position of the picture. A CPU 47 commands a standard grit stripe signal to a signal device 12 through an output interface 50 mounted to a data bus 46 and a control line 40. The signal device 12 receives the signal and inputs a video signal to a drive circuit 36 driving the CRT 1 or the like. Thus, an optional grid strip signal 5 appears on the CRT 1 via deflection yoke connectors 2-1, 2-2 and a socket 3-1.