| 摘要 |
<p>A CRT display unit comprises a line mode detecting circuit (17) for determining a standard mode or a high-resolution mode dependent on the output of a counter (179) counting a horizontal synchronizing signal. When the high-resolution mode is determined, a switching circuit (18) enables a horizontal oscillator (13) and a horizontal deflecting circuit (14) to operate corresponding to the high-resolution mode. In other words, the switching circuit (18) selects time constants (R2 and C 1) so as to increase a horizontal oscillating frequency of the horizontal oscillator (13). To a collector of a horizontal deflecting transistor (Q3), two capacitors (C3 and C4) are connected so that a horizontal flyback period may be shortened. An end of a horizontal deflecting coil (28) is connected to a step-down transformer (27) so as to increase a horizontal amplitude. Thus, the horizontal oscillating frequency, the horizontal amplitude and the horizontal flyback period can be automatically set according to each mode.</p> |
