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US 6,211,619 B1Granted
Electronic ballast cathode heating circuit
OwnerOle K. Nilsseninventor
Life of this patent
Estimating the term…
Abstract
In a high-frequency electronic ballast, a screw-in fluorescent lamp is connected with and powered by way of a series-resonant LC circuit. A resistive load is connected with the LC circuit, thereby to constitute a load therefor before ignition of the fluorescent lamp or in case the fluorescent lamp were to fail to ignite.
Claims8
An arrangement comprising:
- a source providing an alternating voltage across a pair of source terminals;
- the alternating voltage having a fundamental frequency distinctly higher than that of the AC voltage on an ordinary electric utility power line;
- a series-combination of an inductor and a capacitor;
- the series-combination being:
- (i) naturally resonant at a frequency lower than said fundamental frequency, (ii) effectively connected across the source terminals, thereby to draw a source current from the source terminals, and (iii) connected in circuit with a pair of output terminals across which is provided an approximately sinusoidal output voltage;
- the inductor being coupled with an auxiliary winding, thereby to cause an auxiliary voltage to be provided from this auxiliary winding;
- the coupling between the inductor and the auxiliary winding being sufficiently loose so that, in case an electrical short circuit were to be placed across the auxiliary winding, the magnitude of the source current would be prevented from increasing to a detrimentally high level;
- and
- a gas discharge lamp means having a first thermionic cathode with a pair of cathode terminals connected with the auxiliary winding by way of a connect means;
- the lamp means also having a second thermionic cathode;
- the approximately sinusoidal output voltage being applied between the first and the second thermionic cathodes.
8 more elements
An arrangement comprising:
- a source providing an alternating voltage across a pair of source terminals;
- the alternating voltage having a fundamental frequency distinctly higher than that of the AC voltage on an ordinary electric utility power line;
- a series-combination of an inductor and a capacitor;
- the series-combination being:
- (i) naturally resonant at a frequency lower than said fundamental frequency, (ii) effectively connected across the source terminals, thereby to draw a source current from the source terminals, and (iii) connected in circuit with a pair of output terminals across which is provided an approximately sinusoidal output voltage;
- the inductor means being coupled with an auxiliary winding, thereby to cause an auxiliary voltage to be provided from this auxiliary winding;
- the coupling between the inductor and the auxiliary winding being sufficiently loose so that, in case an electrical short circuit were to be placed across the auxiliary winding, the magnitude of the source current would be prevented from increasing to a detrimentally high level;
- and
- a gas discharge lamp having a first thermionic cathode with a pair of cathode terminals connected with the auxiliary winding by way of a connect means;
- the lamp also having a second thermionic cathode;
- the substantially sinusoidal output voltage being applied between the first and the second thermionic cathodes.
8 more elements
An arrangement comprising:
- a source providing an alternating voltage across a pair of source terminals;
- the alternating voltage having a fundamental frequency distinctly higher than that of the AC voltage on an ordinary electric utility power line;
- a series-combination of an inductor and a capacitor;
- the series-combination being:
- (i) naturally resonant at a frequency lower than said fundamental frequency, (ii) effectively connected across the source terminals, thereby to draw a source current from the source terminals, and (iii) connected in circuit with a pair of output terminals across which is provided an approximately sinusoidal output voltage;
- the inductor means being coupled with an auxiliary winding, thereby to cause an auxiliary voltage to be provided from this auxiliary winding;
- and
- a gas discharge lamp means having a first thermionic cathode with a pair of cathode terminals connected with the auxiliary winding by way of a connect means;
- the lamp means also having a second thermionic cathode;
- the substantially sinusoidal output voltage being applied between the first and the second thermionic cathodes;
- the connect means being characterized by including a resistor means.
8 more elements
An arrangement comprising:
- a source providing an alternating voltage across a pair of source terminals;
- the alternating voltage having a fundamental frequency distinctly higher than that of the AC voltage on an ordinary electric utility power line;
- a series-combination of an inductor and a capacitor;
- the series-combination being:
- (i) naturally resonant at a frequency lower than said fundamental frequency, (ii) effectively connected across the source terminals, thereby to draw a source current from the source terminals, and (iii) connected in circuit with a pair of output terminals across which is provided an approximately sinusoidal output voltage;
- the inductor means being coupled with an auxiliary winding, thereby to cause an auxiliary voltage to be provided from this auxiliary winding;
- and
- a gas discharge lamp means having a first thermionic cathode with a pair of cathode terminals connected with the auxiliary winding by way of a connect means;
- the lamp means also having a second thermionic cathode;
- the substantially sinusoidal output voltage being applied between the first and the second thermionic cathodes;
- the connect means including limiting means operative to manifestly limit to a pre-established level the magnitude of any current drawn from the auxiliary winding.
8 more elements
An arrangement comprising:
- a source providing an alternating voltage across a pair of source terminals;
- the alternating voltage having a fundamental frequency distinctly higher than that of the AC voltage on an ordinary electric utility power line;
- an inductive reactance combined with a capacitive reactance;
- the combination being:
- (i) naturally resonant at a frequency at or near said fundamental frequency, (ii) effectively connected across the source terminals, thereby to draw a source current from the source terminals, and (iii) connected in circuit with a pair of output terminals across which is provided an approximately sinusoidal output voltage;
- the inductive reactance being coupled with an auxiliary winding, thereby to cause an auxiliary voltage to be provided from this auxiliary winding;
- the auxiliary winding exhibiting a current-limiting feature by which, in case an electrical short circuit were to be placed across the auxiliary winding, the magnitude of any current thereby drawn therefrom would be manifestly limited to a level sufficiently low not to give rise to a damaging effect;
- and
- a gas discharge lamp having a first thermionic cathode with a pair of cathode terminals connected with the auxiliary winding;
- the lamp means also having a second thermionic cathode;
- the approximately sinusoidal output voltage being applied between the first and the second thermionic cathodes.
8 more elements
An arrangement comprising:
- a source providing an alternating voltage across a pair of source terminals;
- the alternating voltage having a fundamental frequency distinctly higher than that of the AC voltage on an ordinary electric utility power line;
- an inductive reactance combined with a capacitive reactance;
- the combination being:
- (i) naturally resonant at a frequency at or near said fundamental frequency, (ii) effectively connected across the source terminals, thereby to draw a source current from the source terminals, and (iii) connected in circuit with a pair of output terminals across which is provided a high-frequency output voltage;
- the inductive reactance being coupled with an auxiliary winding, thereby to cause an auxiliary voltage to be provided from this auxiliary winding;
- the auxiliary winding exhibiting a current-limiting feature by which, in case an electrical short circuit were to be placed across the auxiliary winding, the magnitude of any current drawn therefrom would be prevented from increasing to a detrimentally high level;
- and
- a gas discharge lamp having a first thermionic cathode with a pair of cathode terminals connected with the auxiliary winding;
- the lamp means also having a second thermionic cathode;
- the high-frequency output voltage being applied between the first and the second thermionic cathodes.
8 more elements
Dependencies are inferred from the claim text.