| 摘要 |
PURPOSE:To degauss securely a shadow mask by connecting a serial circuit consisting of a degaussing coil and a triode AC switch between both ends of a charging capacitor and controlling this triode AC switch. CONSTITUTION:A horizontal output pulse is rectified by a diode D1, smoothened by a capacitor C, and pressure-divided by resistances R1 and R2, while a capacitor C2 is charged with the aid of time constants of the capacitor C2 and a resistance R3. When the capacitor C2 is charged to >=90%, a Zener diode D2 is conducted and a transistor (TR) Q1 is turned on, which causes a TRQ2 to be turned on. A base potential of a TRQ3 is linearly rised by a resistance R11. The rise of a base voltage of the TRQ3 renders an emitter-collector current of a TRQ4 to be turned on abruptly and a gate current of a triode AC switch T to be larger instantaneously, and finally causes the triode AC switch T to be turned on. Thus a charge charged by the capacitor C2 flows in a degaussing coil L, and the degaussing is executed with the aid of a current, which flows in the degaussing coil L and a resonance circuit of an LC2 and decreases slowly. |
