Arrangement for igniting and supplying a gas-and/or vapour discharge lamp

Claim 2

A supply circuit for an electric discharge lamp having at least two preheated electrodes comprisng, a pair of input terminals adapted for connection to a source of electric current, an inductor, means connecting said inductor in series with the lamp across said input terminals, a glow discharge starter, means connecting said glow discharge starter across the lamp electrodes, a photosensitive element having a negative coefficient of resistance and located to receive at least a part of the light emitted by the glow discharge starter, the illumination received by said photosensitive element from the glow discharge starter being greater than all of the illumination received from other light sources including said discharge lamp, and means connecting an auxiliary branch circuit including said photosensitive element in shunt with the glow discharge starter.

Claim 3

A supply circuit as claimed in claim 1 wherein said input terminals are adapted for connection to a source of AC current, said circuit further comprising a capacitor connected in series with the lamp and inductor across the input terminals and a rectifier element included in said auxiliary branch circuit.

Claim 4

A supply circuit as claimed in claim 2 wherein said rectifier element is connected in series with said photosensitive element across the glow discharge starter, said circuit further comprising, a resistor, means connecting said resistor between the junction of said rectifier element and one end of said photosensitive element and a second junction between the other end of the photosensitive element and the glow discharge starter.

Claim 5

A supply circuit as claimed in claim 3 further comprising a second resistor connected in series with the photosensitive element and between the two junctions.

Claim 6

A supply circuit as claimed in claim 1 wherein said inductor comprises a first winding of a transformer, said transformer including a second winding connected in series with the glow discharge starter across the lamp electrodes.

Claim 7

A supply circuit as claimed in claim 1 wherein the input terminals are adapted for connection to an AC source of approximately 220 volts and the lamp comprises a low-pressure mercury vapor discharge lamp having an operating voltage of approximately 180 volts, and wherein the ignition voltage of the glow discharge starter is at least 230 volts effective.

Claim 8

A supply circuit as claimed in claim 1 wherein said glow discharge starter and said photosensitive element are mounted within a common light-tight envelope.

Claim 9

A supply circuit as claimed in claim 7 further comprising a rectifier element connected in series with said photosensitive element across the glow discharge starter.

Claim 10

A supply circuit as claimed in claim 1 further comprising a rectifier element connected in series with said photosensitive element across the glow discharge starter.

Claim 11

A supply circuit for an electric discharge lamp having at least twO preheated electrodes comprising, a pair of input terminals adapted for connection to a source of electric current, an inductor, a glow discharge starter, means connecting said inductor, said two electrodes and said glow discharge starter in series circuit across said input terminals so that a heater current for the lamp electrodes flows through the glow discharge starter, a photosensitive element whose impedance varies with the light incident thereon and located to receive the light emitted by the glow discharge starter to vary its impedance therewith, and means connecting said photosensitive element in shunt with the glow discharge starter to provide a second path for the flow of heater current through the discharge lamp electrodes, said photosensitive element being arranged so that its impedance is substantially independent of the light emitted by the discharge lamp.

Claim 12

A supply circuit for an electric discharge lamp having at least twO preheated electrodes comprising, a pair of input terminals adapted for connection to a source of electric current, an inductor, a glow discharge starter, means connecting said inductor, said two electrodes and said glow discharge starter in series circuit across said input terminals so that a heater current for the lamp electrodes flows through the glow discharge starter, a photosensitive element whose impedance varies with the light incident thereon and located to receive the light emitted by the glow discharge starter to vary its impedance therewith, and means connecting said photosensitive element in shunt with the glow discharge starter to provide a second path for the flow of heater current through the discharge lamp electrodes, said photosensitive element being arranged so that its impedance is substantially independent of the light emitted by the discharge lamp.

Claim 13

A supply circuit as claimed in claim 10 wherein the input terminals are adapted for connection to a source of AC voltage and wherein the ignition voltage of the glow discharge starter is higher than the operating voltage of the discharge lamp.

Claim 14

A supply circuit as claimed in claim 10 further comprising a vapacitor connected in series with the inductor, the two lamp electrodes and the glow discharge starter across the input terminals, and a rectifier element connected in series with the photosensitive element across the glow discharge starter whereby the capacitor-rectifier combination cooperate to provide a voltage multiplier effect across the electrodes of the glow discharge starter.

Claim 15

A supply circuit as claimed in claim 12 further comprising an impedance element connected in shunt with the photosensitive element and in series with the rectifier element across the input terminals.