Ceramic metal halide lamp bi-modal power regulation control
First Claim
1. A method of controlling an oscillator of a high frequency ballast to drive a metal halide lamp at a constant power, said method comprising:
- monitoring a voltage of the oscillator, wherein the voltage is a direct current (DC) voltage provided to the oscillator by an alternating current (AC) to DC converter of the ballast;
monitoring a current of a power supply loop of the oscillator driving the lamp;
operating the oscillator at a first frequency during ignition of the lamp and operating at the first frequency or a second frequency following ignition, wherein the second frequency is different than the first frequency;
determining a duty cycle as a function of the monitored current and voltage, wherein the duty cycle indicates a percentage of a given time period during which the oscillator is to operate at the first frequency versus operating at the second frequency; and
switching the oscillator between the first frequency and the second frequency as a function of the determined duty cycle.
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Accused Products
Abstract
A high frequency ballast for a metal halide lamp comprises a controller, a switch, and an oscillator. The controller selectively enables and disables the oscillator via the switch to ignite the lamp. The switch selectively alters an inductance of the inductor to switch between a first frequency of the oscillator and a second frequency of the oscillator different than the first. The controller monitors a current of a power supply loop of the oscillator and a voltage of the oscillator and determines a duty cycle as a function of the monitored voltage and current. The duty cycle is indicative of the percentage of time that the oscillator is to operate at the first frequency versus the second frequency.
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Citations
21 Claims
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1. A method of controlling an oscillator of a high frequency ballast to drive a metal halide lamp at a constant power, said method comprising:
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monitoring a voltage of the oscillator, wherein the voltage is a direct current (DC) voltage provided to the oscillator by an alternating current (AC) to DC converter of the ballast; monitoring a current of a power supply loop of the oscillator driving the lamp; operating the oscillator at a first frequency during ignition of the lamp and operating at the first frequency or a second frequency following ignition, wherein the second frequency is different than the first frequency; determining a duty cycle as a function of the monitored current and voltage, wherein the duty cycle indicates a percentage of a given time period during which the oscillator is to operate at the first frequency versus operating at the second frequency; and switching the oscillator between the first frequency and the second frequency as a function of the determined duty cycle. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method of controlling an oscillator of a high frequency ballast to drive a metal halide lamp at a constant power, said method comprising:
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monitoring a voltage of the oscillator, wherein the voltage is a direct current (DC) voltage provided to the oscillator by an alternating current (AC) to DC converter of the ballast; monitoring a current of a power supply loop of the oscillator driving the lamp; determining a power consumption as a function of the monitored voltage and of the monitored current; operating the oscillator at a first frequency during ignition of the lamp and maintaining operation at the first frequency following ignition of the lamp; switching the oscillator to a second frequency when the power consumption is above a first threshold, said second frequency higher than the first frequency; and switching the oscillator to the first frequency when the power consumption is below a second threshold. - View Dependent Claims (10, 11, 12, 13, 14)
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15. A high frequency metal halide lamp ballast for providing power to a metal halide lamp from an alternating current (AC) power source, said ballast comprising:
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a direct current (DC) converter for receiving AC power from the AC power source and providing DC power; an oscillator for receiving the DC power from the DC converter and providing high frequency AC power to the lamp; a switch for switching the oscillator between a first frequency and a second frequency wherein the second frequency is higher than the first frequency; and a controller for controlling the switch to selectively switch the oscillator between the first and the second frequency, wherein the controller; monitors a voltage of the oscillator, wherein the voltage is a direct current (DC) voltage provided to the oscillator by an alternating current (AC) to DC converter of the ballast; monitors a current of a power supply loop of the oscillator driving the lamp; controls the switch to operate the oscillator at a first frequency during ignition of the lamp and to operate at the first frequency or a second frequency following ignition, wherein the second frequency is different than the first frequency; determines a duty cycle as a function of the monitored current and voltage, wherein the duty cycle indicates a percentage of a given time period during which the oscillator is to operate at the first frequency versus operating at the second frequency; and controls the switch to switch the oscillator between the first frequency and the second frequency as a function of the determined duty cycle. - View Dependent Claims (16, 17, 18, 19, 20, 21)
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Specification