Low cost transistorized inverter

Claim 2

A low cost circuit utilizing a two-transistor inverter with a feedback air-core transformer to provide high-frequency operation of a load comprising ballasted discharge lamps, said circuit comprising: a rectifier means having positive and negative output terminals, and input terminals adapted to be connected to an AC power source; b. first and second solid state switches connected in series directly between said positive and negative output terminals, said first solid state switch being connected to said positive output terminal of said rectifier means and said second solid state switch being connected to said negative output terminal of said rectifier means; c. a junction connected to the common connection between said first and second solid state switches, said junction and at least one of said positive and negative output terminals adapted to be connected to said load to transfer high-frequency power thereto; and d. feedback means comprising a resistor and an air-core transformer, said air-core transformer having a primary winding and a first secondary winding and a second secondary winding; i. said resistor and said primary winding being connected in series relationship, and said series-connected resistor and primary winding effectively connected in parallel with said load with a voltage shift at said junction producing a change in current in said primary winding; ii. said first secondary winding being connected to said first solid state switch, a change in current in said primary winding on a positive shift in voltage at said junction providing in said fisrt secondary winding an electrical signal which rapidly decays, said signal in first secondary first turning on said first solid state switch and then turning off said first solid state switch, and said turn-off of said first solid state switch producing a negative shift in voltage at said junction; and iii. said second secondary winding connected to said second solid state switch, a change in current in said primary winding on said negative shift in voltage at said junction providing in said second secondary winding an electric signal which rapidly decays, said signal in said second secondary first turning on said second solid state switch and then turning off said second solid state switch, and said turn-off of said second solid state switch producing a positive shift in voltage at said junction to continue the inverter action, and said rapid decays in electric signals in said secondary windings providing high-frequency operaton.

Claim 3

A circuit for improved operation of ballasted discharge lamps, said circuit comprising: a. a rectifier means having an electrically positive output terminal, an electrically negative output terminal, and input terminals adapted to be connected to an AC power source; b. inverter means comprising a first solid state switch having a collector, a base and an emitter; a second solid state switch having a collector, a base, and an emitter; and feedback means for switching said solid state switches; c. said first solid state switch and said second solid state switch connected in series relationship between said positive output terminal and said negative output terminal, with said first solid state switch connected to said positive output terminal of said rectifier means, and said second solid state switch connected to said negative output terminal of said rectifier means, and the junction connection of said first solid state switch and said second solid state switch providing an inverter output junction; d. at least one electric load comprising a series combination of at least one reactive electrical component and discharge lamp; e. an isolating means, said isolating means being connected in series with said load, said series combination of isolating means and load being connected between said inverter output junction and one of said output rectifiers terminals; f. said feedback means of said inverter comprising an air-core transformer having a primary winding and a first secondary winding and a seocnd secondary winding, and a resistor connected in series with said primary winding of said air-core transformer and said series-connected primary and resistor being connected effectively in parallel with said load, said first secondary winding connected between said base and said emitter of said first solid state switch, and said second secondary winding connected between said base and said emitter of said solid state switch, said first secondary winding and said second secondary winding polarized to control the inverter action of said circuit as follows; i. said first secondary being polarized to produce a turn-on current for said first solid state switch when the voltage at said inverter output junction has a positive shift in voltage; ii. after said first solid state switch is turned on, said current in said first secondary winding, thereafter rapidly decays to zero, the decay of current in said first secondary winding causing said first solid state switch to turn off, said turn-off of said first solid state switch then producing a negative shift in voltage at said inverter output junction; iii. said second secondary winding polarized to produce turn-on current for said second solid state switch when the voltage at the inverter output junction has said negative shift in voltage; iv. after said second solid state switch is turned on, said current in said second secondary winding rapidly decaying to zero, and the decay of current in said second secondary winding causing said second solid state switch to turn off, said turn-off of said second solid state switch then producing a positive shift in voltage at said inverter output junction and initiating turn-on of said first solid state switch, v. the frequency of the foregoing inverter action being predetermined by the design of said feedback means including the value of said resistor, winding ratios of said primary and said secondaries and the coupling therebetween.

Claim 4

A circuit for improved operation of ballasted discharge lamps, said circuit comprising: a. a rectifier means having an electrically positive output terminal, an electrically negative output terminal, and input terminals adapted to be connected to an AC power source; b. inverter means comprising a first solid state switch having a collector, a base and an emitter; a second solid state switch having a collector, a base, and an emitter; and feedback means for switching said solid state switches; c. said first solid state switch and said second solid state switch connected in series relationship between said positive output terminal and said negative output terminal, with said first solid state switch connected to said positive output terminal of said rectifier means, and said second solid state switch connected to said negative output terminal of said rectifier means, and the junction connection of said first solid state switch and said second solid state switch providing an inverter output junction; d. at least one electric load comprising a series combination of at least one reactive electrical component and discharge lamp; e. an isolating means, said isolating means being connected in series with said load, said series combination of isolating means and load being connected between said inverter output junction and one of said output rectifiers terminals; f. said feedback means of said inverter comprising an air-core transformer having a primary winding and a first secondary winding and a seocnd secondary winding, and a resistor connected in series with said primary winding of said air-core transformer and said series-connected primary and resistor being connected effectively in parallel with said load, said first secondary winding connected between said base and said emitter of said first solid state switch, and said second secondary winding connected between said base and said emitter of said solid state switch, said first secondary winding and said second secondary winding polarized to control the inverter action of said circuit as follows; i. said first secondary being polarized to produce a turn-on current for said first solid state switch when the voltage at said inverter output junction has a positive shift in voltage; ii. after said first solid state switch is turned on, said current in said first secondary winding, thereafter rapidly decays to zero, the decay of current in said first secondary winding causing said first solid state switch to turn off, said turn-off of said first solid state switch then producing a negative shift in voltage at said inverter output junction; iii. said second secondary winding polarized to produce turn-on current for said second solid state switch when the voltage at the inverter output junction has said negative shift in voltage; iv. after said second solid state switch is turned on, said current in said second secondary winding rapidly decaying to zero, and the decay of current in said second secondary winding causing said second solid state switch to turn off, said turn-off of said second solid state switch then producing a positive shift in voltage at said inverter output junction and initiating turn-on of said first solid state switch, v. the frequency of the foregoing inverter action being predetermined by the design of said feedback means including the value of said resistor, winding ratios of said primary and said secondaries and the coupling therebetween.

Claim 5

The circuit as specified in claim 2 wherein a starting means is connected between the base and the emitter of one of the solid state switches to initiate oscillations.

Claim 6

The circuit as specified in claim 3 wherein said load comprises a capacitor, an inductor, and a discharge lamp in series, the series resonance of said capacitor and said inductor being higher than the frequency at which said first and said second solid state switches oscillate, such that switching losses in said first and said second solid state switches are reduced.

Claim 7

The circuit as specified in claim 4 wherein said load comprises at least one portion, each load portion comprising a major reactive element in series with a parallel combination of at least two load segments, each load segment comprising a discharge lamp and a reactive component of a type opposite that of said major reactive component of that load portion.

Claim 8

The circuit as specified in claim 5 wherein said discharge lamps are fluorescent lamps having filaments, and said filaments are powered from secondaries of an air-core filament transformer, said air-core filament transformer having a primary connected effectively in parallel with said load.

Claim 9

The circuit as specified in claim 2 wherein said isolation means is a capacitor provided in series with said load, one terminal of said series combination of said capacitor and said load being connected to said inverter output junction, and the other terminal of said series combination of said capacitor and said load being connected to either said positive output terminal or said negative output terminal.

Claim 10

The circuit as specified in claim 2 wherein said isolation means comprises two capacitors, connected in series between said positive terminal and said negative terminal of said rectifier and one terminal of said load is connected to said inverter output junction and the other terminal of said load is connected to the common connection point of said two capcitors, such that the capacitors serve not only as isolation means, but also as filter capacitor for said rectifier means.

Claim 11

A circuit for improved operation of ballasted discharge lamps, said circuit comprising: a rectifier means having an electrically positive output terminal, an electrically negative output terminal, and input terminals adapted to be connected to an AC power source; b. inverter means comprising a first solid state switch having a collector, a base and an emitter; a second solid state switch having a collector, a base and an emitter; and feedback means for switching said solid state switches; c. said first solid state switch and said second solid state switch connected in series relationship with said fist solid state switch connected to said positive output terminal of said rectifier means, and said second solid state switch connected to said negative output terminal of said rectifier means, and the junction connection of said first solid state and said second solid state switches providing an inverter output junction; d. capacitor means connecting to a circuit output terminal, said capacitor means and output terminal connected as follows: said capacitor means connected between at least one of said rectifier output terminals and said circuit output terminal, and said ballasted lamps adapted to be connected between said circuit output terminal and said inverter output junction; and said capacitor means having predetermined large capacitance sufficient that, during operation of said circuit arrangement, the voltage or voltages across said capacitor means remain substantially constant at about one-half the peak-to-peak output voltage of said inverter mEans; e. said feedback means of said inverter comprising an air-core transformer having a primary winding and a first secondary winding and a second secondary winding, and a resistor connected in series with said primary winding, said series-connected resistor and said primary winding connected effectively across said termials adapted to be connected to said ballasted discharge lamps, said first secondary winding connected between said base and said emitter of said first solid state switch, and second secondary winding connected between said base and said emitter of said second solid state switch; said first secondary winding and said second secondary winding polarized as follows to control the inverter action of said circuit: i. said first secondary winding polarized to produce a current in said first secondary in the direction to turn on said first solid state switch when the voltage at said inverter output junction has a positive shift in voltage; ii. after said first solid state switch is turned on, said current in said first secondary winding thereafter rapidly decreases to zero, and the decay of current in said first secondary winding causing said first solid state switch to turn off, iii. said second secondary winding polarized to produce a current in said second secondary winding in the direction to turn on said second solid state switch when the voltage at said inverter output junction has a negative shift in voltage, the turn-off of said first solid state switch causing said negative shift in voltage at said inverter output junction and inducing turn-on of said second solid state switch; iv. after said second solid state switch is turned on, said current in said second secondary winding rapidly decaying to zero, and the decay of current in said second secondary winding causing said second solid state switch to turn off; and v. the frequency of the foregoing inverter action being predetermined by the design of said feedback means including the value of said resistor, winding ratios of said primary and said secondaries and the coupling therebetween.

Claim 12

A circuit for improved operation of ballasted discharge lamps, said circuit comprising: a rectifier means having an electrically positive output terminal, an electrically negative output terminal, and input terminals adapted to be connected to an AC power source; b. inverter means comprising a first solid state switch having a collector, a base and an emitter; a second solid state switch having a collector, a base and an emitter; and feedback means for switching said solid state switches; c. said first solid state switch and said second solid state switch connected in series relationship with said fist solid state switch connected to said positive output terminal of said rectifier means, and said second solid state switch connected to said negative output terminal of said rectifier means, and the junction connection of said first solid state and said second solid state switches providing an inverter output junction; d. capacitor means connecting to a circuit output terminal, said capacitor means and output terminal connected as follows: said capacitor means connected between at least one of said rectifier output terminals and said circuit output terminal, and said ballasted lamps adapted to be connected between said circuit output terminal and said inverter output junction; and said capacitor means having predetermined large capacitance sufficient that, during operation of said circuit arrangement, the voltage or voltages across said capacitor means remain substantially constant at about one-half the peak-to-peak output voltage of said inverter mEans; e. said feedback means of said inverter comprising an air-core transformer having a primary winding and a first secondary winding and a second secondary winding, and a resistor connected in series with said primary winding, said series-connected resistor and said primary winding connected effectively across said termials adapted to be connected to said ballasted discharge lamps, said first secondary winding connected between said base and said emitter of said first solid state switch, and second secondary winding connected between said base and said emitter of said second solid state switch; said first secondary winding and said second secondary winding polarized as follows to control the inverter action of said circuit: i. said first secondary winding polarized to produce a current in said first secondary in the direction to turn on said first solid state switch when the voltage at said inverter output junction has a positive shift in voltage; ii. after said first solid state switch is turned on, said current in said first secondary winding thereafter rapidly decreases to zero, and the decay of current in said first secondary winding causing said first solid state switch to turn off, iii. said second secondary winding polarized to produce a current in said second secondary winding in the direction to turn on said second solid state switch when the voltage at said inverter output junction has a negative shift in voltage, the turn-off of said first solid state switch causing said negative shift in voltage at said inverter output junction and inducing turn-on of said second solid state switch; iv. after said second solid state switch is turned on, said current in said second secondary winding rapidly decaying to zero, and the decay of current in said second secondary winding causing said second solid state switch to turn off; and v. the frequency of the foregoing inverter action being predetermined by the design of said feedback means including the value of said resistor, winding ratios of said primary and said secondaries and the coupling therebetween.