METHOD AND APPARATUS FOR SINGLE-ENDED CONVERSION OF DC TO AC POWER FOR DRIVING DISCHARGE LAMPS
First Claim
1. An apparatus for converting a direct current (DC) signal into an alternating current (AC) signal, comprising:
- a network of at least one switch for generating an AC signal from a DC signal, the AC signal being generated by a first portion of the network periodically opening and closing;
filtering means being coupled between said network of at least one switch and a load, said filtering means filtering the AC signal delivered to said load, wherein said filtering means includes a transformer having at least one primary winding that receives the AC signal from said network of at least one switch and having a secondary winding that is coupled to said load;
a diode being connected to at least one primary winding of said transformer;
at least one capacitor being coupled to said transformer secondary winding to form a resonant circuit for generating a substantially sinusoidal waveform to drive said load;
and impedance means being coupled between said at least one transformer primary winding and said network of at least one switch.
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Accused Products
Abstract
The present disclosure introduces a simple method and apparatus for converting DC power to AC power, and, specifically, to single-ended inverter circuits for driving discharge lamps such as a Cold Cathode Fluorescent Lamp (CCFL) or an External Electrode Fluorescent Lamp (EEFL). Among other advantages, these circuits offer nearly symmetrical voltage waveform to drive discharge lamps when the duty cycle is close to 50%. They also eliminate the high current and high voltage resonant capacitor on the primary side, and reduce the voltage rating of a primary switch to twice the input voltage without the need for snubber circuits. The recommended inverters can be used to efficiently drive discharge lamps at low cost, particularly for applications with a narrow input voltage range. The lamp current can be regulated through the duty cycle modulation of the main switch.
36 Citations
31 Claims
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1. An apparatus for converting a direct current (DC) signal into an alternating current (AC) signal, comprising:
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a network of at least one switch for generating an AC signal from a DC signal, the AC signal being generated by a first portion of the network periodically opening and closing;
filtering means being coupled between said network of at least one switch and a load, said filtering means filtering the AC signal delivered to said load, wherein said filtering means includes a transformer having at least one primary winding that receives the AC signal from said network of at least one switch and having a secondary winding that is coupled to said load;
a diode being connected to at least one primary winding of said transformer;
at least one capacitor being coupled to said transformer secondary winding to form a resonant circuit for generating a substantially sinusoidal waveform to drive said load;
and impedance means being coupled between said at least one transformer primary winding and said network of at least one switch. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 13)
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12. The apparatus of claim 12, wherein said two primary windings are coupled by a capacitor.
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14. An apparatus for converting a direct current (DC) signal into an alternating current (AC) signal for operating at least one electrical discharge lamp, comprising:
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a single-ended network of at least one semiconductor device for generating an AC signal from a DC input signal, said AC signal being generated by a first portion of the network periodically opening and closing;
filtering means being coupled between said network of at least one switch and a load, said filtering means filtering said AC signal delivered to said load, wherein said filtering means includes a transformer having two primary windings;
at least one capacitor being coupled to said transformer'"'"'s secondary winding to form a resonant circuit for generating a substantially sinusoidal waveform to drive said load;
and another capacitor being coupled between one of said two primary windings and said network of at least one semiconductor device. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. A method of converting a direct converting a direct current (DC) signal into an alternating current (AC) signal for operating at least one electrical discharge lamp, comprising:
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receiving a DC signal;
opening and closing a switching device;
chopping said DC input signal by the opening and closing of said switching device;
generating an alternating signal in primary windings of a transformer by chopping the DC signal, wherein a capacitor is coupled to at least one primary winding of the transformer;
stepping up said alternating signal of the transformer'"'"'s primary winding into its secondary winding and deriving a stepped-up alternating signal;
filtering said stepped-up alternating signal and deriving a filtered signal through a filter; and
supplying said filtered signal to said electrical discharge lamp. - View Dependent Claims (25, 26, 27, 28, 29, 30, 31)
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Specification