Back to results
US 5,179,326 AGranted
Electronic ballast with separate inverter for cathode heating
OwnerOle K. Nilsseninventor
Life of this patent
Estimating the term…
Abstract
A high-frequency electronic ballast for fluorescent lamps has a first inverter for controllably providing heating power to the lamp cathodes and a second inverter for controllably providing main lamp operating power. The two inverters are separately and independently controllable, thereby: i) to permit adjustment of lamp current so as to provide full or reduced light output in accordance with requirements, ii) to permit cathode heating power to be removed under conditions of providing full light output, thereby to maximize efficiency, and iii) to permit cathode heating power to be restored under conditions of reduced light output, thereby to prevent premature lamp failure.
Claims20
An arrangement comprising:
- rectifier means operative to connect with an ordinary electric utility power line and, when so connected, to provide a DC voltage at a set of DC terminals;
- first inverter means connected with the DC terminals and operative in response to the DC voltage to provide an arc current from a first set of output terminals;
- second inverter means connected with the DC terminals and operative in response to the DC voltage to provide cathode heating power from a second set of output terminals, the second inverter means having control means operable in response to the magnitude of the arc current to control the magnitude of the cathode heating power;
- and
- fluorescent lamp means having arc terminals and cathode terminals, the arc terminals being operative to connect with and to receive the arc current from the first set of output terminals, the cathode terminals being operative to connect with and to receive the cathode heating power from the second set of output terminals;
- whereby the fluorescent lamp means is:
- i) provided with arc current from the first inverter means, and ii) controllably provided with cathode heating power from the second inverter means.
4 more elements
An arrangement comprising:
- rectifier means operative to connect with the power line voltage of an ordinary electric utility power line and, when indeed so connected, to provide a DC voltage at a set of DC terminals;
- first source means connected with the DC terminals and operative to provide a substantially continuous sinusoidal arc current from a first set of output terminals;
- the fundamental frequency of the arc current being higher than about 10 kHz;
- the first source means being characterized by including an L-C circuit resonant at or near the fundamental frequency of the arc current;
- second source means connected with the DC terminals and operative provide cathode heating power from a second set of output terminals;
- the second source means having control means operable to permit control of the magnitude of the cathode heating power;
- the control action being derived from the arc current and being a function of the magnitude thereof;
- and
- gas discharge lamp means having arc terminals and cathode terminals;
- the arc terminals being operative to connect with and to receive the arc current from the first set of output terminals;
- the cathode terminals being operative to connect with and to receive the cathode heating power from the second set of output terminals;
- whereby the fluorescent lamp means is:
- (a) provided with arc current from the first source means;
- and (b) provided with cathode heating power from the second source means in such manner that the magnitude of the cathode heating power will:
- (i) exceed a predetermined level whenever the magnitude of the arc current fails to exceed a certain level, and (ii) be substantially lower than said predetermined level whenever the magnitude of the arc current does exceed said certain level.
12 more elements
An arrangement comprising:
- a source providing a DC voltage at a pair of DC terminals;
- converter means connected with the DC terminals and operative to provide:
- (i) a continuous substantially sinusoidal high-frequency arc current from a first set of output terminals, and (ii) cathode heating power from a second set of output terminals;
- the converter means having adjustment means operative to permit, in response to an electric control action, adjustment of the magnitude of the arc current;
- and
- gas discharge lamp means having arc terminals and cathode terminals;
- the arc terminals being connected with the first set of output terminals and being operative to receive the arc current therefrom;
- the cathode terminals being connected with the second set of output terminals and being operative to receive the cathode heating power therefrom;
- whereby the gas discharge lamp means is:
- (a) provided from the first set of output terminals with a continuous flow of arc current of adjustable magnitude;
- and (b) provided from the second set of output terminals with cathode heating power in such manner that the magnitude of the cathode heating power will:
- (i) be higher than a predetermined level whenever the magnitude of the arc current is adjusted below a certain level, and (ii) be substantially lower than said predetermined level whenever the magnitude of the arc current is adjusted above said certain level.
9 more elements
An arrangement comprising:
- a gas discharge lamp having a pair of arc terminals and a pair of cathode terminal connected with a thermionic cathode;
- the cathode terminals being characterized by having therebetween a cathode load impedance;
- the cathode load impedance being defined as the impedance represented by the thermionic cathode as observed from the cathode terminals;
- a source having a first and second pair of output terminals;
- the first pair of output terminals being connected with the arc terminals;
- the second pair of output terminals:
- (i) being characterized by having a cathode source impedance, the cathode source impedance being defined as the internal impedance exhibited by the second pair of output terminals, and (ii) being connected with the cathode terminals;
- the source being operable to provide a non-interrupted substantially sinusoidal arc current of adjustable magnitude to the arc terminals and a cathode heating voltage of adjustable magnitude to the cathode terminals;
- the arc current having a frequency of at least 10 kHz;
- and
- control means connected in circuit with the source and operable to control the magnitude of the cathode heating voltage such that:
- (i) it is higher than a certain level whenever the magnitude of the arc current is adjusted to be lower than predetermined level;
- and (ii) it is substantially lower than said certain level whenever the magnitude of the arc current is adjusted to be higher than said predetermined level.
10 more elements
An arrangement comprising:
- a source providing a DC voltage at a pair of DC terminals;
- converter means connected with the DC terminals and operative to provide:
- (i) a substantially continuous flow of high-frequency arc current form a first pair of terminals, and (ii) cathode heating power from a second set of terminals;
- the converter means having adjustment means operative to effect adjustment of the magnitude of the arc current in response to an electric control action;
- and
- gas discharge lamp means having arc terminals and cathode terminals;
- the arc terminals being connected with the first set of output terminals and being operative to receive the arc current therefrom;
- the cathode terminals being connected with the second set of output terminals and being operative to receive the cathode heating power therefrom;
- the arrangement being operative to causes the cathode heating power to be:
- (i) higher than a predetermined level whenever the magnitude of the arc current is adjusted below a certain level, and (ii) substantially lower than said predetermined level whenever the magnitude of the arc current is adjusted above said certain level.
7 more elements
Dependencies are inferred from the claim text.