Electric lamp and discharge devices: systems – With cathode or cathode heater supply circuit – Pulsating or a.c. supply to the cathode or heater circuit
Patent
1988-01-20
1990-06-19
LaRoche, Eugene R.
Electric lamp and discharge devices: systems
With cathode or cathode heater supply circuit
Pulsating or a.c. supply to the cathode or heater circuit
315205, 315209R, 315278, 315DIG5, 315DIG7, H05B 4129
Patent
active
049356690
ABSTRACT:
A self-oscillating inverter-type fluorescent lamp ballast has two modes of operation: (a) a first mode in which the inversion frequency is about 70 kHz and is resonant with a first tuned circuit by which power is supplied to the cathodes of the fluorescent lamp; and (b) a second mode in which the inversion frequency is about 30 kHz and is resonant with a second tuned circuit by which main lamp power is supplied. When the ballast is initially powered-up, it starts operation in its first mode, thereby providing cathode heating power without yet providing main lamp power. About one second later, after the cathodes have reached full incandescence, the inverter automatically changes into its second mode, thereby providing main lamp power while at the same time removing cathode heating power. If for some reason the lamp were not to ignite within about 10 milli-seconds, the inverter reverts back into its first mode; thereafter cycling between its two modes until the lamp does ignite.
REFERENCES:
patent: 4538093 (1985-08-01), Melai
patent: 4588924 (1986-05-01), Luursema
patent: 4719390 (1988-01-01), Sairanen
patent: 4746841 (1988-05-01), Ogawa
LaRoche Eugene R.
Shingleton Michael B.
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