Apparatus for detecting gas discharge lamp faults

DETAILED DESCRIPTION I claim: 1.
A fault detection circuit for use with series connected gas discharge lamps powered from a source of alternating voltage, comprising: A) a capacitor coupled in series with the series connected gas discharge lamps; B) a direct current voltage detector having at least one resistor coupled in parallel with the capacitor.
2.
The fault detection circuit of claim 1, wherein the resistor comprises a high impedance resistor to significantly minimize direct current flow through the series connected gas discharge lamps to prevent polarization of gases within the gas discharge lamps.
3.
The fault detection circuit of claim 2, wherein the direct current voltage detector further includes a transistor that is coupled to the resistor.
4.
The fault detection circuit of claim 3, wherein the transistor has a base, and the base couples to the resistor.
5.
A circuit for powering series connected gas discharge lamps comprising: a source of alternating voltage; a resonant circuit coupled to the source, the resonant circuit having an inductor and a first capacitor; a second capacitor coupled in series with the gas discharge lamps; the second capacitor and the gas discharge lamps coupled in parallel with the first capacitor; and a direct current voltage detector coupled in parallel with the second capacitor for detecting a fault condition.
6.
The circuit of claim 5, wherein the direct current voltage detector includes a resistor that is coupled to the capacitor.
7.
The circuit of claim 6, wherein the resistor comprises a high impedance resistor to significantly minimize direct current flow through the series connected gas discharge lamps to prevent polarization of gases within the gas discharge lamps.
8.
The circuit of claim 7, wherein the direct current voltage detector further includes a transistor that is coupled to the resistor.
9.
The circuit of claim 8, wherein the transistor has a base, and the base couples to the resistor.




Description:
The technical field of this invention relates generally to gas discharge lamps and control circuits therefor