| 摘要 |
<p>1381732 Converting MATSUSHITA ELECTRIC INDUSTRIAL CO Ltd 10 Dec 1971 [13 Dec 1970] 57382/71 Heading H2F Cathode-ray tube apparatus comprises means D1 . . . D4 for rectifying A.C. power and means, such as T1, T2, for regulating the resulting D.C. power for supply to the deflection circuits (not shown) of said CRT in accordance with a signal dependent on the beam current of the CRT. As shown in Fig. 6, the A.C. input is rectified by diodes D1 ... D4 and controlled by a series regulating transistor T1 in dependence on the difference between an adjustable voltage at the tapping of a potential divider R3 ... R5 across the D.C. output and a reference voltage across a Zener diode ZD. A connection is made at the junction of the video amplifier and cathode of the CRT so as to compensate for changes in CRT beam current. In Fig. 4 (not shown) the beam current compensating signal is obtained from a parallel RC circuit in series with the low potential end of the EHT secondary winding. The upper end of resistor R4 is connected to the collector of transistor T2 so that the D.C. output voltage is no longer monitored. Thyristor regulating circuits.-In Fig. 7, the output of rectifier 110 is chopped by thyristor 118 and filtered at 122 to provide the required D.C. output at 126. A sawtooth wave is generated at 130 and a pulse generated at 134 when the sawtooth wave crosses a reference voltage determined by the D.C. output and beam current, so that a trigger pulse is generated at 148 so as to provide the required conduction angle for thyristor 118. Figs. 8 and 9 (not shown) depict circuit diagrams of the system shown in Fig. 7.</p> |
