Control circuit for mercury arc lamps

Claim 2

In a starting and ballast circuit for mercury arc lamps, a source of a.c. power, an inductor, an arc lamp, a pair of capacitors, parallel circuit branches connecting said capacitors in parallel across said power source, rectifying means in each of saiD circuit branches in series relationship with said capacitors and arranged in opposite polarity, and circuit connections connecting said lamp and said inductor in series relationship between said parallel circuits and to points thereon between said capacitors and said rectifying means, whereby the sum of the charges on said capacitors is impressed across said lamp to start discharge therethrough and whereby said capacitors thereafter alternately discharge through said lamp and series inductor and limit the current flow through the lamp and whereby said inductor reduces current peaks and provides a more continuous current flow through said lamp.

Claim 3

A circuit as claimed in claim 1 which further includes voltage responsive switching means connected in series relationship with both of said parallel circuit branches and operative to delay charging of said capacitors each half cycle until the supply voltage has increased each half cycle to a predetermined value, thereby to increase the effective power supplied to the lamp and to reduce the required capacitance.

Claim 4

A circuit as claimed in claim 2 which further includes a second inductor connected in series relationship with said voltage responsive switching means and with both of said circuit branches across said power supply and operative to reduce peak capacitor charging currents and increase the total inductance.

Claim 5

A circuit as claimed in claim 2 in which said voltage responsive switching means comprises a controlled bi-directional, solid state switching device including a gating circuit therefor responsive to a predetermined supply voltage to effect conduction thereof.

Claim 6

In a starting and regulating circuit for vapor arc lamps, a source of a. c. power, an inductor, an arc lamp, a pair of capacitors, parallel circuit branches connecting said capacitors in parallel across said power source, rectifying means in each of said circuit branches in series relationship with said capacitors and arranged in opposed polarity, circuit connections connecting said lamp and said inductor in series relationship across said parallel circuit branches at points thereon between said capacitors and said rectifying means, whereby the sum of the charges on said capacitors is impressed across said lamp to start discharge therethrough and whereby said capacitors thereafter alternately discharge through said lamp and inductor and limit the current flow through the lamp, and switching means connected in series with both circuit branches controlling conduction therethrough, said switching means being responsive to variations in an operative condition of said lamp to variably delay the charging and discharging of said capacitors each half cycle of the power supply thereby to vary the inductive reactance of said inductor and consequently the effective power supplied to the lamp.

Claim 7

In a starting and regulating circuit for vapor arc lamps, a source of a. c. power, an inductor, an arc lamp, a pair of capacitors, parallel circuit branches connecting said capacitors in parallel across said power source, rectifying means in each of said circuit branches in series relationship with said capacitors and arranged in opposed polarity, circuit connections connecting said lamp and said inductor in series relationship across said parallel circuit branches at points thereon between said capacitors and said rectifying means, whereby the sum of the charges on said capacitors is impressed across said lamp to start discharge therethrough and whereby said capacitors thereafter alternately discharge through said lamp and inductor and limit the current flow through the lamp, and switching means connected in series with both circuit branches controlling conduction therethrough, said switching means being responsive to variations in an operative condition of said lamp to variably delay the charging and discharging of said capacitors each half cycle of the power supply thereby to vary the inductive reactance of said inductor and consequently the effective power supplied to the lamp.

Claim 8

A starting and regulating circuit as claimed in claim 5 in which said switching means is responsive to variations in the light intensity of said lamp to variably delay the charging and discharging of said capacitors each half cycle of the power supply.

Claim 9

A staring and regulating circuit as claimed in claim 5 in which said switching means is responsive to variations in the average current flow through said lamp to variably delay the charging and discharging of said capacitors each half cycle of the power supply.

Claim 10

In a starting and regulating circuit for the operation of vapor arc lamps, an a. c. power source, first and second inductors, an arc lamp, a pair of capacitors, parallel circuit branches connecting said capacitors in parallel across said power supply, a normally non-conductive, silicon controlled rectifier in each of said circuit branches, each connected in series with a capacitor and arranged in opposed polarity, circuit connections connecting said lamp and said first inductor in series between said circuit branches and to points thereon between said SCR''s and said capacitors, gating means operative to apply a firing signal to each of said SCR''s at a predetermined time during their conductive half cycle, whereby the sum of the charges on said capacitors is impressed across said lamp to start discharge therethrough and whereby said capacitors thereafter alternately discharge through said lamp and series inductor and limit current flow through the lamp, and circuit connections connecting said second inductor across said power source in series with both of said circuit branches.

Claim 11

In a starting and regulating circuit for the operation of vapor arc lamps, an a. c. power source, first and second inductors, an arc lamp, a pair of capacitors, parallel circuit branches connecting said capacitors in parallel across said power supply, a normally non-conductive, silicon controlled rectifier in each of said circuit branches, each connected in series with a capacitor and arranged in opposed polarity, circuit connections connecting said lamp and said first inductor in series between said circuit branches and to points thereon between said SCR''s and said capacitors, gating means operative to apply a firing signal to each of said SCR''s at a predetermined time during their conductive half cycle, whereby the sum of the charges on said capacitors is impressed across said lamp to start discharge therethrough and whereby said capacitors thereafter alternately discharge through said lamp and series inductor and limit current flow through the lamp, and circuit connections connecting said second inductor across said power source in series with both of said circuit branches.

Claim 12

A starting and control circuit as set forth in claim 8 in which said gating means comprises a resistor and a capacitor series connected across said power source, a transformer secondary winding connected between the control electrode of each of said SCR''s and the cathode side thereof, a transformer primary winding common to both of said secondary windings and a bi-directional, voltage breakdown, triggering switch, said primary winding and said triggering switch being series connected in parallel with said capacitor and in series with said resistor.

Claim 13

A starting and regulating circuit as claimed in claim 9 which further includes a photoconductive element series connected with said resistor and capacitor and being responsive to variations in the light intensity of said lamp to vary the firing time of said SCR''s.

Claim 14

A starting and regulating circuit as claimed in claim 10 which further includes a filament lamp connected in series relationship with said lamp across said circuit branches and adapted to be heated by current passing through said lamp, and in which said photoconductive element is responsive to variations in the radiant energy of said filament to vary the firing time of said SCR''s.

Claim 15

In a starting and regulating circuit for the operation of vapor arc lamps, an a. c. power source, first and second inductors, an arc lamp, a pair of capacitors, a pair of parallel circuit branches connecting said capacitors in parallel across said power source, a solid state diode in each of said branches, each in series relationship with a capacitor and said diodes being arranged in opposed polarity, circuit connections connecting said first inductor and said lamp in series relationship between said circuit branches and to points thereon between said capacitors and said diodes, a normally non-conductive, controlled, bi-directional, solid state switching device, circuit connections connecting said solid state switching device and said second inductor in series across said power source and in series relationship with both of said circuit branches, and gating means operative to apply firing signals to said bi-directional switching device during alternate half cycles of the power supply to effect conduction thereof at a predetermined time during each half cycle.

Claim 16

In a starting and regulating circuit for the operation of vapor arc lamps, an a. c. power source, first and second inductors, an arc lamp, a pair of capacitors, a pair of parallel circuit branches connecting said capacitors in parallel across said power source, a solid state diode in each of said branches, each in series relationship with a capacitor and said diodes being arranged in opposed polarity, circuit connections connecting said first inductor and said lamp in series relationship between said circuit branches and to points thereon between said capacitors and said diodes, a normally non-conductive, controlled, bi-directional, solid state switching device, circuit connections connecting said solid state switching device and said second inductor in series across said power source and in series relationship with both of said circuit branches, and gating means operative to apply firing signals to said bi-directional switching device during alternate half cycles of the power supply to effect conduction thereof at a predetermined time during each half cycle.

Claim 17

A starting and control circuit as set forth in claim 12 in which said bi-directional, solid state switching device is a Triac, and in which said gating means comprises a resistor and a capacitor series connected across said Triac, and a bi-directional, voltage responsive, triggering switch connected between the control electrode of said Triac and said R-C timing circuit at a point thereon between said resistor and said capacitor.