Combination ballast for driving a fluorescent lamp or tube and ballast protection circuit
First Claim
1. An electronic ballast having an output terminal at which to provide output power for driving a fluorescent lamp or tube, said ballast comprising:
- power supply means;
oscillator means connected between said power supply means and the lamp or tube to provide a high frequency output signal to said lamp or tube; and
a protection circuit including a protection switch connected to said oscillator means to control the operation thereof and a flip-flop connected to said protection switch and responsive to the output power of said ballast, said flip-flop being triggered to operate said protection switch for terminating the operation of said oscillator means and disabling said ballast when the lamp or tube is defective or disconnected from said ballast and the output power of said ballast undergoes a corresponding change.
2 Assignments
0 Petitions
Accused Products
Abstract
A circuit is disclosed to implement an energy saving electronic ballast (1A) for driving a fluorescent lamp or tube (2). The circuit is characterized by a high power factor, low harmonic distortion and minimized radio frequency interference. The circuit includes a unique DC power supply (4) comprising a high pass filter (8), which receives an AC input signal, a diode bridge rectifier (6) and a high speed diode rectifier (D2) which cooperates with the bridge rectifier to provide the power supply with first and second rectification stages. A current regulating capacitor (C4) for driving the fluorescent lamp or tube is connected to the DC power supply between the first and second rectification stages. A trigger and high frequency oscillator are provided after the second rectification stage of the power supply to provide the DC current necessary to operate the ballast circuit. A protection circuit (30) is connected to the ballast and operable to disable the oscillator and thereby prevent damage to the ballast in the event that the tube or lamp is defective or disconnected from the ballast or subjected to abnormal operating conditions.
16 Citations
20 Claims
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1. An electronic ballast having an output terminal at which to provide output power for driving a fluorescent lamp or tube, said ballast comprising:
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power supply means; oscillator means connected between said power supply means and the lamp or tube to provide a high frequency output signal to said lamp or tube; and a protection circuit including a protection switch connected to said oscillator means to control the operation thereof and a flip-flop connected to said protection switch and responsive to the output power of said ballast, said flip-flop being triggered to operate said protection switch for terminating the operation of said oscillator means and disabling said ballast when the lamp or tube is defective or disconnected from said ballast and the output power of said ballast undergoes a corresponding change. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. An electronic ballast to provide output power for driving a fluorescent lamp or tube, said ballast comprising:
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power supply means; oscillator means connected between said power supply means and the lamp or tube to provide a high frequency output signal to said lamp or tube; and a protection circuit including a first ferrite choke coil that is responsive to the output power of said ballast and a flip-flop interconnected between said oscillator means and said first ferrite choke coil to receive from said choke coil a signal corresponding to the output power of said ballast, said flip-flop adapted to terminate the operation of said oscillator means and thereby disable said ballast when the lamp or tube is defective or disconnected from said ballast and the power to which said choke coil is responsive passes a threshold level. - View Dependent Claims (9, 10, 11, 12, 13)
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14. The combination of an electronic ballast to drive a fluorescent lamp or tube and a protection circuit to disable said ballast when the lamp or tube is defective or disconnected from said ballast, said ballast including a DC power supply to receive an AC input signal and provide an output signal to ignite the lamp or tube and oscillator means connected between said power supply and said lamp or tube to provide a high frequency output signal to said lamp or tube, the DC power supply of said ballast comprising:
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filter means to filter the AC input signal; first rectification means to rectify the filtered AC input signal; second rectification means connected to said first rectification means so that said input signal is rectified twice; and an output terminal connected to said second rectification means to provide a DC output current for operating said ballast, said ballast further including current regulating means regulating the filtered AC input signal rectified by said first rectification means and including a first capacitor connected between an electrode of the fluorescent lamp or tube and a point between the first and second rectification means of said DC power supply, such that a high frequency current flows from said lamp or tube to said second rectification means by way of said current regulating capacitor, and said protection circuit including switching means connected to said oscillator means and responsive to the output power of said ballast, said switching means being triggered when the output power of said ballast passes a threshold level to terminate the operation of said oscillator means and thereby disable said ballast. - View Dependent Claims (15, 16, 17, 18, 19, 20)
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Specification