DC operated electronic ballast for fluorescent light
First Claim
1. A device for operating at least two gaseous discharge lamps, the device comprising:
- a) an input protection circuiti) having first and second input terminals across which an input voltage source is provided, andii) having a pair of output terminals which are protected from overvoltages and polarity reversals at the first and second input terminals;
b) a filter having a pair of inputs coupled with the pair of outputs of the input protection circuit and having a first output terminal and a second output terminal across which a filtered DC voltage is provided, wherein the first output terminal of the filter is at a higher potential than the second output terminal of the filter;
c) a DC to DC converter for performing a DC to DC conversion, the DC to DC converter having a first input coupled with the first output terminal of the filter, a second input for receiving a signal which controls the DC to DC conversion, a first output provided with a stepped-up DC voltage resulting from the DC to DC conversion, and a second output providing a feedback control signal;
d) a power output stage for providing a high frequency lamp drive output, the power output stage having a first input coupled with the first output of the DC to DC converter, a second input provided with a start control signal, a first output, a second output, and a third output, the third output of the power output stage providing a signal based on a voltage provided at the first output of the DC to DC converter;
e) a lamp connecting circuit for providing power to the at least two gaseous discharge lamps, the lamp connecting circuit having a first input coupled with the first output of the power output stage and a second input coupled with the second output of the power output stage; and
f) a control circuit, the control circuit includingi) a pulse width modulator having an output providing a fixed frequency pulse train and coupled with the second input of the DC to DC converter, and an input coupled with the second output of the DC to DC converter, wherein a duty cycle of the fixed frequency pulse train provided by the pulse width modulator is varied based on the feedback control signal provided from the second output of the DC to DC converter,ii) a multivibrator capacitively coupled with the second input of the DC to DC converter, andiii) a safety disconnect and starting device having an input coupled with the third output of the power output stage and an output coupled with the second input of the power output stage and providing a start control signal based on the input of the safety disconnect and starting device.
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Accused Products
Abstract
A device for operating lamps, such as fluorescent lamps includes an input protection circuit, a filter, a DC to DC converter, a power output stage, a lamp connecting circuit and a control circuit. The control circuit includes a pulse width modulator, a multivibrator and a start/stop controller. The pulse width modulator varies the duty cycle of a control signal supplied to the DC to DC converter based on a feedback signal from the DC to DC converter. The multivibrator assists in the control of the DC to DC converter. The start/stop controller initiates the operation of the power output stage when an output of the DC to DC converter reaches a predetermined level and halts the operation of the power output stage if a failure is detected.
151 Citations
22 Claims
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1. A device for operating at least two gaseous discharge lamps, the device comprising:
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a) an input protection circuit i) having first and second input terminals across which an input voltage source is provided, and ii) having a pair of output terminals which are protected from overvoltages and polarity reversals at the first and second input terminals; b) a filter having a pair of inputs coupled with the pair of outputs of the input protection circuit and having a first output terminal and a second output terminal across which a filtered DC voltage is provided, wherein the first output terminal of the filter is at a higher potential than the second output terminal of the filter; c) a DC to DC converter for performing a DC to DC conversion, the DC to DC converter having a first input coupled with the first output terminal of the filter, a second input for receiving a signal which controls the DC to DC conversion, a first output provided with a stepped-up DC voltage resulting from the DC to DC conversion, and a second output providing a feedback control signal; d) a power output stage for providing a high frequency lamp drive output, the power output stage having a first input coupled with the first output of the DC to DC converter, a second input provided with a start control signal, a first output, a second output, and a third output, the third output of the power output stage providing a signal based on a voltage provided at the first output of the DC to DC converter; e) a lamp connecting circuit for providing power to the at least two gaseous discharge lamps, the lamp connecting circuit having a first input coupled with the first output of the power output stage and a second input coupled with the second output of the power output stage; and f) a control circuit, the control circuit including i) a pulse width modulator having an output providing a fixed frequency pulse train and coupled with the second input of the DC to DC converter, and an input coupled with the second output of the DC to DC converter, wherein a duty cycle of the fixed frequency pulse train provided by the pulse width modulator is varied based on the feedback control signal provided from the second output of the DC to DC converter, ii) a multivibrator capacitively coupled with the second input of the DC to DC converter, and iii) a safety disconnect and starting device having an input coupled with the third output of the power output stage and an output coupled with the second input of the power output stage and providing a start control signal based on the input of the safety disconnect and starting device. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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22. A device for operating at least two gaseous discharge lamps from a supplied DC voltage, the device comprising:
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a) a DC to DC converter for performing a DC to DC conversion, the DC to DC converter having a first input coupled with the supplied DC voltage, a second input for receiving a signal which controls the DC to DC conversion, a first output provided with a stepped-up DC voltage resulting from the DC to DC conversion, and a second output providing a feedback control signal; b) a power output stage for providing a high frequency lamp drive output, the power output stage having a first input coupled with the first output of the DC to DC converter, a second input provided with a start control signal, a first output, a second output, and a third output, the third output of the power output stage providing a signal based on a voltage provided at the first output of the DC to DC converter; c) a lamp connecting circuit for providing power to the at least two gaseous discharge lamps, the lamp connecting circuit having a first input coupled with the first output of the power output stage and a second input coupled with the second output of the power output stage; and d) a control circuit, the control circuit including i) a pulse width modulator having an output providing a fixed frequency pulse train and coupled with the second input of the DC to DC converter, and an input coupled with the second output of the DC to DC converter, wherein a duty cycle of the fixed frequency pulse train provided by the pulse width modulator is varied based on the feedback control signal provided from the second output of the DC to DC converter, ii) a multivibrator capacitively coupled with the second input of the DC to DC converter, and iii) a safety disconnect and starting device having an input coupled with the third output of the power output stage and an output coupled with the second input of the power output stage and providing a start control signal based on the input of the safety disconnect and starting device.
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Specification