Fluorescent lamp igniting circuit

Claim 2

A circuit for igniting a fluorescent lamp, the lamp having a first and a second electrically conductive filament and each filament having a first and a second terminal, which comprises: means for applying a first potential to the first terminal of the first filament and a second potential to the first terminal of the second filament; a first semiconductive device, connected between the second terminal of the first filament and the second terminal of the second filament, and responsive to the application of the first potential to become conductive to complete a path for a flow of current through the first and second filaments; means responsive to the application of the first and the second potentials to render the first semiconductive device nonconductive a predetermined time after the application of the potentials to interrupt the flow of current through the first and second filaments; and means responsive to the interruption of the current flow through the first and second filaments to ignite the fluorescent lamp.

Claim 3

A circuit for igniting a fluorescent lamp, the lamp having a first and a second electrically conductive filament and each filament having a first and a second terminal, which comprises: means for applying a first potential to the first terminal of the first filament and a second potential to the first terminal of the second filament; a first semiconductive device, connected between the second terminal of the first filament and the second terminal of the second filament, and responsive to the application of the first potential to become conductive to complete a path for a flow of current through the first and second filaments; means responsive to the application of the first and the second potentials to render the first semiconductive device nonconductive a predetermined time after the application of the potentials to interrupt the flow of current through the first and second filaments; and means responsive to the interruption of the current flow through the first and second filaments to ignite the fluorescent lamp.

Claim 4

A circuit for igniting a fluorescent lamp, the lamp having a first and a second electrically conductive filament and each filament having a first and a second terminal, which comprises: means for applying a first potential to the first terminal of the first filament and a second potential to the first terminal of the second filament; a first semiconductive device, connected between the second terminal of the first filament and the second terminal of the second filament, and responsive to the application of the first potential to become conductive to complete a path for a flow of current through the first and second filaments; means responsive to the application of the first and the second potentials to render the first semiconductive device nonconductive a predetermined time after the application of the potentials to interrupt the flow of current through the first and second filaments; and means responsive to the interruption of the current flow through the first and second filaments to ignite the fluorescent lamp.

Claim 5

A circuit for igniting a fluorescent lamp, the lamp having a first and second electrically conductive filament and each filament having a first and a second terminal, the second filament being characterized in that it exhibits a gradually increasing impedance as it is heated by I2R losses in response to the application of a potential thereacross, which comprises: means for applying a first potential to the first terminal of the first filament and a second potential to the first terminal of the second filament; a first semiconductive device, connected between the second terminal of the first filament and the second terminal of the second filament, and responsive to the application of the first potential to become conductive to apply a potential across the second filament to gradually increase the potential at the connection between the first semiconductive device and the second terminal of the second filament as a result of a voltage divider effect as the second filament exhibits the increasing impedance in response to the application of the potential thereacross; a second semiconductive device, connected to the connection between the first semiconductive device and the second terminal of the second filament, and responsive to a predetermined potential at the connection to render the first semiconductive device nonconductive; and means responsive to the first semiconductive device being rendered nonconductive to ignite the fluorescent lamp.

Claim 6

A circuit for igniting a fluorescent lamp, the lamp having a first and second electrically conductive filament and each filament having a first and a second terminal, the second filament being characterized in that it exhibits a gradually increasing impedance as it is heated by I2R losses in response to the application of a potential thereacross, which comprises: means for applying a first potential to the first terminal of the first filament and a second potential to the first terminal of the second filament; a first semiconductive device, connected between the second terminal of the first filament and the second terminal of the second filament, and responsive to the application of the first potential to become conductive to apply a potential across the second filament to gradually increase the potential at the connection between the first semiconductive device and the second terminal of the second filament as a result of a voltage divider effect as the second filament exhibits the increasing impedance in response to the application of the potential thereacross; a second semiconductive device, connected to the connection between the first semiconductive device and the second terminal of the second filament, and responsive to a predetermined potential at the connection to render the first semiconductive device nonconductive; and means responsive to the first semiconductive device being rendered nonconductive to ignite the fluorescent lamp.

Claim 7

A circuit as recited in claim 2, wherein: a silicon-controlled-rectifier is connected to the first semiconductive device to control the conduction thereof; and the second semiconductive device is also connected to the silicon-controlled-rectifier to control the conduction thereof, such that nonconduction of the silicon-controlled-rectifier allows the first semiconductive device to conduct and such that conduction of the silicon-controlled-rectifier prevents the first semi-conductive device from conducting.

Claim 8

A circuit as recited in claim 3, wherein: the first semiconductive device is a transistor switching device, the base of the transistor being connected to the silicon-controlled-rectifier; the Second semiconductive device is a Zener diode having a breakdown potential equal to the predetermined potential; and the means for igniting the lamp includes an induction coil connected in series with the first terminal of the first filament.

Claim 9

A circuit as recited in claim 3, further including: first and second series connected resistors connected between the first and the second potentials, the resistors being of such a value that the potential at the connection between them is equal to the predetermined potential; and wherein the first semiconductive device is a transistor switching device; the second semiconductive device is a transistor switching device, the emitter of the transistor being connected to the connection between the first transistor and the second terminal of the second filament and the base of the transistor being connected to the connection between the first and the second resistors, so that when the potential at the emitter reaches the predetermined potential the transistor is rendered conductive to render the silicon-controlled-rectifier conductive; and the means for igniting the lamp includes an induction coil connected in series with the portion of the circuit including the means for applying the first potential and the first terminal of the first filament, so that when the first transistor is rendered nonconductive an inductive voltage kick is provided to ignite the lamp.

Claim 10

A circuit for igniting a fluorescent lamp, the lamp having a first and a second electrically conductive filament and each filament having a first and a second terminal, which comprises: means for applying a first potential to the first terminal of the first filament and a second potential to the first terminal of the second filament; a first semiconductive device, connected between the second terminal of the first filament and the second terminal of the second filament, and responsive to the application of the first potential to become conductive; a resistor-capacitor network, connected in series between the means for applying the first potential and the means for applying the second potential; a second semiconductive device, connected to the connection between the resistor and the capacitor of the resistor-capacitor network for sensing the potential on the capacitor, and responsive to a predetermined potential on the capacitor to render the first semiconductive device nonconductive, the potential on the capacitor being below the predetermined potential when the first potential is initially applied and gradually rising to the predetermined potential in response to the application of the first and the second potentials; and means responsive to the first semiconductive device being rendered nonconductive to ignite the fluorescent lamp.

Claim 11

A circuit for igniting a fluorescent lamp, the lamp having a first and a second electrically conductive filament and each filament having a first and a second terminal, which comprises: means for applying a first potential to the first terminal of the first filament and a second potential to the first terminal of the second filament; a first semiconductive device, connected between the second terminal of the first filament and the second terminal of the second filament, and responsive to the application of the first potential to become conductive; a resistor-capacitor network, connected in series between the means for applying the first potential and the means for applying the second potential; a second semiconductive device, connected to the connection between the resistor and the capacitor of the resistor-capacitor network for sensing the potential on the capacitor, and responsive to a predetermined potential on the capacitor to render the first semiconductive device nonconductive, the potential on the capacitor being below the predetermined potential when the first potential is initially applied and gradually rising to the predetermined potential in response to the application of the first and the second potentials; and means responsive to the first semiconductive device being rendered nonconductive to ignite the fluorescent lamp.

Claim 12

A circuit as recited in claim 6 wherein: a silicon controlled rectifier is connected to the first semiconductive device to control the conduction thereof; and the second semiconductive device is connected to the silicon-controlled-rectifier to control the conduction thereof, such that nonconduction of the silicon-controlled-rectifier allows the first semiconductive device to conduct and such that conduction of the silicon-controlled rectifier prevents the first semiconductive device from conducting.

Claim 13

A circuit as recited in claim 7, wherein: the first semiconductive device is a transistor switching device, the base of the transistor being connected to the silicon-controlled-rectifier; the second semiconductive device is a Zener diode, the breakdown potential of the diode being equal to the predetermined potential; and the means for igniting the lamp includes an induction coil connected in series with the first terminal of the first filament.

Claim 14

In a fluorescent lamp igniting circuit, the lamp having at least one filament responsive to the application of a voltage to generate heat through I2R losses, the filament exhibiting a first impedance prIor to the application of the voltage and being characterized in that it exhibits a gradually increasing impedance as its temperature increases in response to the application of the voltage, the improvement which comprises: an impedance coupled in series with the filament to form a voltage divider; a transistor switching device connected in series with the impedance and the filament to control the conduction of current therethrough; a semiconductor device for sensing the potential between the impedance and the filament, and responsive to the potential reaching the predetermined potential as a result of the impedance of the filament reaching a predetermined impedance to render the transistor switching device nonconductive; and means, responsive to nonconduction of the transistor switching device, to ignite the lamp.

Claim 15

In a fluorescent lamp igniting circuit, the lamp having at least one filament responsive to the application of a voltage to generate heat through I2R losses, the filament exhibiting a first impedance prIor to the application of the voltage and being characterized in that it exhibits a gradually increasing impedance as its temperature increases in response to the application of the voltage, the improvement which comprises: an impedance coupled in series with the filament to form a voltage divider; a transistor switching device connected in series with the impedance and the filament to control the conduction of current therethrough; a semiconductor device for sensing the potential between the impedance and the filament, and responsive to the potential reaching the predetermined potential as a result of the impedance of the filament reaching a predetermined impedance to render the transistor switching device nonconductive; and means, responsive to nonconduction of the transistor switching device, to ignite the lamp.

Claim 16

A circuit as recited in claim 9, wherein: a silicon-controlled-rectifier is connected to the base of the transistor switching device to control the conduction thereof; and the semiconductor device is a Zener diode connected to the silicon-controlled-rectifier to control the conduction thereof.

Claim 17

A circuit as recited in claim 9, wherein: a silicon-controlled-rectifier is connected to the base of the transistor switching device to control the conduction thereof; and the semiconductor device is a transistor switching device connected to the silicon-controlled-rectifier to control the conduction thereof.

Claim 18

A circuit for igniting a fluorescent lamp, the fluorescent lamp having an input terminal and an output terminal, which comprises: a resistor-capacitor network; means for applying a voltage across the network to thereby increase the potential at the connection between the resistor and the capacitor; a transistor switching device, connected between the input and the output terminals, and responsive to the application of the voltage to become conductive to complete a path for a flow of current between the input and the output terminals; means, responsive to the potential between the resistor and capacitor reaching a predetermined potential, to render the transistor nonconductive to interrupt the flow of current between the input and the output terminals; and means, responsive to the interruption of the flow of current between the input and the output terminals, to ignite the lamp.

Claim 19

A circuit for igniting a fluorescent lamp, the fluorescent lamp having an input terminal and an output terminal, which comprises: a resistor-capacitor network; means for applying a voltage across the network to thereby increase the potential at the connection between the resistor and the capacitor; a transistor switching device, connected between the input and the output terminals, and responsive to the application of the voltage to become conductive to complete a path for a flow of current between the input and the output terminals; means, responsive to the potential between the resistor and capacitor reaching a predetermined potential, to render the transistor nonconductive to interrupt the flow of current between the input and the output terminals; and means, responsive to the interruption of the flow of current between the input and the output terminals, to ignite the lamp.

Claim 20

In a circuit for igniting a fluorescent tube having a pair of spaced filaments that exhibit an increased impedance upon application of current therethrough; a transistor having its collector connected to a first one of the filaments and its emitter connected to the second one of the filaments; means for applying operating current through the filaments and the base of the transistor to initiate conduction therethrough; a semiconductive device having three electrodes, one of which controls conduction between the other two electrodes, and then relinquishes control of conduction between the other two electrodes; means, responsive to a predetermined increase in impedance of the filaments, for applying a conduction potential to the control electrode to render conductive the semiconductive device; and means, responsive to the conduction of the semiconductive device, to interrupt conduction of the transistor and to generate and apply a pulse to ignite the fluorescent tube.

Claim 21

In a circuit for igniting a fluorescent tube having a pair of spaced filaments that exhibit an increased impedance upon application of current therethrough; a transistor having its collector connected to a first one of the filaments and its emitter connected to the second one of the filaments; means for applying operating current through the filaments and the base of the transistor to initiate conduction therethrough; a semiconductive device having three electrodes, one of which controls conduction between the other two electrodes, and then relinquishes control of conduction between the other two electrodes; means, responsive to a predetermined increase in impedance of the filaments, for applying a conduction potential to the control electrode to render conductive the semiconductive device; and means, responsive to the conduction of the semiconductive device, to interrupt conduction of the transistor and to generate and apply a pulse to ignite the fluorescent tube.