| 摘要 |
1,175,252. Supply systems for discharge tubes. PHILIPS ELECTRONIC & ASSOCIATED INDUSTRIES Ltd. 9 Feb., 1967 [12 Feb., 1966], No. 6272/67. Heading H2H. A circuit for striking and supplying a discharge lamp includes a high-frequency generator which operates by discharging a capacitor through a switching element such as a thyristor. In the circuit shown in Fig. 1, a mains supply is connected to terminals 1, 2 so that the capacitor 5 is charged through a coupling impedance 3 and the primary winding 4 of a transformer whose secondary is connected across the lamp 8. Before the peak voltage of the supply is reached, the potential at the gate of the thyristor. 6 becomes sufficient to trigger it, and the capacitor now discharges through the thyristor, the effective frequency being determined by the magnitudes of the inductor 4 and capacitor 5. A number of such chargedischarge cycles will occur in each half-wave of the mains supply. In a modification, Fig. 2 (not shown), the mains is also connected to the discharge lamp and the circuit is arranged so that the high frequency generator serves only to ignite the lamp. In this arrangement also, the lamp is provided with preheater cathodes. |
