Starting and operating circuit for arc discharge lamp
First Claim
1. A starting and operating circuit for a discharge lamp comprising:
- a pair of AC input terminals adapted to receive an AC signal from an AC power supply;
DC power supply means coupled to said AC input terminals for generating a DC voltage;
oscillator means including a pair of semiconductor switches coupled to said DC power supply to receive said DC voltage;
oscillator starting means coupled to one of said semiconductor switches, said oscillator starting means having an input and including a series circuit comprising resistor means and capacitor means connected at a junction point and a threshold element means connected to said junction point, the input of said oscillator starting means being coupled to one of said AC input terminals so that said capacitor means is charged only on one half cycle of said AC signal; and
load means coupled to the output of said oscillator means and including said discharge lamp.
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Accused Products
Abstract
A circuit for starting and operating a discharge lamp, such as a compact fluorescent lamp, at high frequency from an 60 Hz AC supply. The circuit includes a power supply for generating a DC voltage coupled to a pair of AC input terminals. A DC/AC converter includes an oscillator having a pair of semiconductor switches coupled in parallel with the DC power supply. an oscillator starting circuit is coupled to one of the semiconductor switches and includes a series circuit comprising a resistor, capacitor and threshold element. The input of the oscillator starting circuit is coupled to one of the AC input terminals so as to prevent a momentary flicker in the lamp after the AC supply is removed and the lamp has extinguished. In accordance with another aspect of the invention, the oscillator includes fusible circuit elements which render the oscillator inoperable upon failure of the lamp due to depletion of emissive material on at least one of the lamp electrodes.
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Citations
10 Claims
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1. A starting and operating circuit for a discharge lamp comprising:
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a pair of AC input terminals adapted to receive an AC signal from an AC power supply; DC power supply means coupled to said AC input terminals for generating a DC voltage; oscillator means including a pair of semiconductor switches coupled to said DC power supply to receive said DC voltage; oscillator starting means coupled to one of said semiconductor switches, said oscillator starting means having an input and including a series circuit comprising resistor means and capacitor means connected at a junction point and a threshold element means connected to said junction point, the input of said oscillator starting means being coupled to one of said AC input terminals so that said capacitor means is charged only on one half cycle of said AC signal; and load means coupled to the output of said oscillator means and including said discharge lamp. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A starting and operating circuit for a discharge lamp having a pair of electrodes adapted to receive a quantity of emissive material, said circuit comprising:
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a pair of AC input terminals adapted to receive an AC signal from an AC power supply; DC power supply means coupled to said AC input terminals for generating a DC voltage; oscillator means coupled to said DC power supply and including a pair of semiconductor switches, each of said semiconductor switches having first resistor means connected in series with the output thereof and second resistor means connected to the input thereof, said first resistor means or said second resistor means of each of said semiconductor switches being a fusible type resistor operable to inhibit said oscillator means upon failure of said lamp due to depletion of emissive material on at least one of said lamp electrodes; oscillator staring means coupled to one of said semiconductor switches; and load means coupled to the output of said oscillator means and including said discharge lamp. - View Dependent Claims (9)
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10. An arrangement comprising:
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a pair of AC input terminals adapted to receive an AC signal from an AC power supply; DC power supply means coupled to said AC input terminals for generating a DC voltage; oscillator means coupled to said DC power supply and including a pair of semiconductor switches and fusible circuit means, oscillator starting means coupled to one of said semiconductor switches, said oscillator starting means having an input and including a series circuit comprising resistor means and capacitor means, said input of said oscillator starting means being coupled to one of said AC input terminals so that said capacitor means is charged only on one half cycle of said AC signal; load means coupled to the output of said oscillator means, said load means including a fluorescent lamp having a pair of electrodes adapted to receive a quantity of emissive material; said fusible circuit means being operable to inhibit said oscillator means upon failure of said lamp due to depletion of emissive material on at least one of said electrodes.
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Specification