Lamp ballast with frequency modulated lamp frequency

Claim 2

An electronic power supply for a load, comprising: a high-frequency section providing alternating current to said load at said high-frequency, a power input section receiving input power at a low frequency, and having a pulsating DC output, and a circuit coupling between the high frequency section and the pulsating DC output for drawing current pulses from the power input section, characterized in that said power input section provides power only as a series of said current pulses at a repetition rate synchronized to said high frequency, arranged to minimize current distortion in the low frequency input power, and said power supply further comprises means for sensing a parameter which varies during each cycle of said low frequency to provide a sensed signal, and control means, responsive to said sensed signal, for frequency modulating said high frequency of the load current during each cycle of the low frequency power input to minimize low frequency modulation of the load current without significant increase in distortion of the current drawn by said power input section.

Claim 3

An electronic ballast for a discharge lamp, comprising: a high frequency section providing alternating lamp current to said lamp at said high frequency, a power input section receiving input power at a low frequency, and having a pulsating DC output, a circuit coupling between the high frequency section and the pulsating DC output for drawing current pulses from the power input section, characterized in that said power input section provides power only as a series of said current pulses at a repetition rate synchronized to said high frequency, arranged to minimize current distortion in the low frequency input power, and said ballast further comprises means for sensing a parameter which varies during each cycle of said low frequency to provide a sensed signal, and control means, responsive to said sensed signal, for frequency modulating said high frequency of the lamp current during each cycle of the low frequency power input to minimize low frequency modulation of the lamp current without significant increase in distortion of the current drawn by said power input section.

Claim 4

An electronic ballast for a discharge lamp, comprising: a high frequency section providing alternating lamp current to said lamp at said high frequency, a power input section receiving input power at a low frequency, and having a pulsating DC output, a circuit coupling between the high frequency section and the pulsating DC output for drawing current pulses from the power input section, characterized in that said power input section provides power only as a series of said current pulses at a repetition rate synchronized to said high frequency, arranged to minimize current distortion in the low frequency input power, and said ballast further comprises means for sensing a parameter which varies during each cycle of said low frequency to provide a sensed signal, and control means, responsive to said sensed signal, for frequency modulating said high frequency of the lamp current during each cycle of the low frequency power input to minimize low frequency modulation of the lamp current without significant increase in distortion of the current drawn by said power input section.

Claim 5

A ballast as claimed in claim 2, characterized in that said high frequency section includes an energy storage element; and current is drawn from said power input section, and current is delivered to said energy storage element, only at mutually different periods of time in each high frequency cycle.

Claim 6

A ballast as claimed in claim 3, wherein the high frequency section comprises a resonance circuit for coupling to the lamp, characterized in that said means for sensing senses a signal from said resonance circuit.

Claim 7

A ballast as claimed in claim 3, wherein the high frequency section comprises a resonance circuit for coupling to the lamp, characterized in that said means for sensing senses the lamp current.

Claim 8

A ballast as claimed in claim 5, characterized in that said high frequency has a maximum value approximately at the voltage crossover of said low frequency.

Claim 9

A ballast as claimed in claim 2, wherein the high frequency section comprises a resonance circuit for coupling to the lamp, characterized in that said means for sensing senses a signal from said resonance circuit.

Claim 10

A ballast as claimed in claim 2, wherein the high frequency section comprises a resonance circuit for coupling to the lamp, characterized in that said means for sensing senses the lamp current.

Claim 11

A ballast as claimed in claim 8, characterized in that said high frequency has a maximum value approximately at the voltage crossover of said low frequency.

Claim 12

An electronic lamp ballast, comprising input means for connecting to a source of low-frequency AC power, a full-wave rectifier circuit connected to said input means for providing a pulsating full-wave rectified supply voltage at a supply voltage output, an energy-storage capacitor connected to said supply voltage output through an isolating diode, an inverter circuit connected to said energy-storage capacitor for providing high-frequency power at an inverter frequency, a resonance circuit comprising at least one inductance and one capacitor, and means for connecting at least one electrical discharge lamp to said resonance circuit and to said inverter circuit to operate said lamp with alternating current at said inverter frequency, characterized in that said means for connecting comprises a component connected to said isolating diode for supplying current pulsations to said energy-storage capacitor only at a pulse repetition rate synchronized to said inverter frequency, and the ballast further comprises: means for sensing a parameter which varies during each half cycle of said low frequency to provide a sensed signal, and control means, responsive to said sensed signal, for frequency modulating the inverter frequency during each half cycle of the low frequency power input to minimize variation in the lamp current without significantly increasing distortion of the low frequency current drawn by said power input section.

Claim 13

An electronic lamp ballast, comprising input means for connecting to a source of low-frequency AC power, a full-wave rectifier circuit connected to said input means for providing a pulsating full-wave rectified supply voltage at a supply voltage output, an energy-storage capacitor connected to said supply voltage output through an isolating diode, an inverter circuit connected to said energy-storage capacitor for providing high-frequency power at an inverter frequency, a resonance circuit comprising at least one inductance and one capacitor, and means for connecting at least one electrical discharge lamp to said resonance circuit and to said inverter circuit to operate said lamp with alternating current at said inverter frequency, characterized in that said means for connecting comprises a component connected to said isolating diode for supplying current pulsations to said energy-storage capacitor only at a pulse repetition rate synchronized to said inverter frequency, and the ballast further comprises: means for sensing a parameter which varies during each half cycle of said low frequency to provide a sensed signal, and control means, responsive to said sensed signal, for frequency modulating the inverter frequency during each half cycle of the low frequency power input to minimize variation in the lamp current without significantly increasing distortion of the low frequency current drawn by said power input section.

Claim 14

A ballast as claimed in claim 10, characterized in that current is drawn from said supply voltage output, and current is delivered to said energy storage capacitor, only at mutually different periods of time in each high frequency cycle.

Claim 15

A ballast as claimed in claim 11, characterized in that said means for sensing senses a signal from said resonance circuit.

Claim 16

A ballast as claimed in claim 12, characterized in that said component is said capacitor in the resonance circuit.

Claim 17

A ballast as claimed in claim 11, characterized in that said means for sensing senses the lamp current.

Claim 18

A ballast as claimed in claim 14, characterized in that said high frequency is a maximum approximately at the voltage crossover of said low frequency AC power.

Claim 19

A ballast as claimed in claim 10, characterized in that said means for sensing senses a signal from said resonance circuit.

Claim 20

A ballast as claimed in claim 16, characterized in that said component is said capacitor in the resonance circuit.

Claim 21

A ballast as claimed in claim 10, characterized in that said means for sensing senses the lamp current.

Claim 22

A ballast as claimed in claim 18, characterized in that said high frequency is a maximum approximately at the voltage crossover of said low frequency AC power.

Claim 25

A method as claimed in claim 20, wherein said high frequency section includes a storage capacitor and a high frequency inverter whose input is connected across said storage capacitor, said high frequency inverter operating at said second frequency, and said storage capacitor having a capacitance sufficiently great that voltage across said capacitor does not change substantially during a half cycle of the first frequency alternating voltage, characterized by providing charging current to said storage capacitor as a second series of current pulses flowing only at times different from pulses of said first series, the voltage across said storage capacitor being greater than said output during each entire cycle of said first frequency alternating voltage.

Claim 26

A method as claimed in claim 21, characterized by: sensing a parameter which varies during each cycle of said first frequency, and frequency modulating said second frequency to minimize modulation of the load current at a frequency related to said first frequency without significant increase in distortion of the current drawn by said power input section.

Claim 27

A method as claimed in claim 22, characterized in that said sensing step includes sensing said load current to provide a current signal, and low-pass filtering said current signal.

Claim 28

A method as claimed in claim 23, wherein said load is a gas discharge lamp, characterized by connecting said lamp in effective series combination with an inductance and a capacitance to form said circuit.

Claim 29

A method as claimed in claim 20, characterized by: sensing a parameter which varies during each cycle of said first frequency, and frequency modulating said second frequency to minimize modulation of the load current at a frequency related to said first frequency without significant increase in distortion of the current drawn by said power input section.

Claim 30

A method as claimed in claim 25, characterized in that said sensing step includes sensing said load current to provide a current signal, and low-pass filtering said current signal.

Claim 31

A method as claimed in claim 26, wherein said load is a gas discharge lamp, characterized by connecting said lamp in effective series combination with an inductance and a capacitance to form said circuit.

Claim 32

A method as claimed in claim 25, wherein said load is a gas discharge lamp, characterized by connecting said lamp in effective series combination with an inductance and a capacitance to form said circuit.

Claim 33

A method as claimed in claim 20, wherein said load is a gas discharge lamp, characterized by connecting said lamp in effective series combination with an inductance and a capacitance to form said circuit.

Claim 34

An electronic power supply for a load, comprising: a power input section receiving input power at a low frequency, and having a pulsating DC output, a high frequency section providing alternating current to said load at said high frequency, said high frequency being substantially higher than said low frequency, and a circuit coupling between the high frequency section and the pulsating DC output for drawing current pulses from the power input section, characterized in that said power input section provides power only as a first series of said current pulses at a repetition rate synchronized to said high frequency, arranged to minimize current distortion in the low frequency input power, and said high frequency section comprises an energy storage element for storing energy over a period at least equal to one half cycle of said low frequency, and means for providing charging current to said storage element as a second series of second current pulses at a second repetition rate synchronized to said high frequency.

Claim 35

An electronic power supply for a load, comprising: a power input section receiving input power at a low frequency, and having a pulsating DC output, a high frequency section providing alternating current to said load at said high frequency, said high frequency being substantially higher than said low frequency, and a circuit coupling between the high frequency section and the pulsating DC output for drawing current pulses from the power input section, characterized in that said power input section provides power only as a first series of said current pulses at a repetition rate synchronized to said high frequency, arranged to minimize current distortion in the low frequency input power, and said high frequency section comprises an energy storage element for storing energy over a period at least equal to one half cycle of said low frequency, and means for providing charging current to said storage element as a second series of second current pulses at a second repetition rate synchronized to said high frequency.

Claim 36

A supply as claimed in claim 30, characterized in that said energy storage element is a capacitor which has a capacitance sufficiently great that voltage across said capacitor does not change substantially during said half cycle of said low frequency, and which is charged to a voltage greater than the peak value of said pulsating DC output, and said second current pulses flow only at times different from the pulses of said first series of said current pulses.

Claim 37

A supply as claimed in claim 31, characterized in that said high frequency section comprises an inverter for providing said alternating current to said load, and said inverter has power input connections connected across said capacitor.

Claim 38

A supply as claimed in claim 31, characterized in that said circuit coupling between the high frequency section and the pulsating DC output includes a further capacitor which is also part of the high frequency section, and said high frequency section comprises a diode having one terminal connected to said further capacitor and a second terminal connected to the energy storage capacitor.