Method and apparatus for energizing a gaseous discharge lamp using switched energy storage capacitors

Apparatus for flashing a gaseous discharge lamp having a gas interior, anode and cathode terminals, a minimum anode voltage and a minimum holding voltage, comprising:

• a. trigger means coupled to said lamp for generating a trigger voltage pulse to provide first stage ionization of the gas in said lamp;
• b. power supply means coupled to a boost storage capacitor and to an energy storage capacitor for charging said boost storage capacitor to a first voltage and for charging said energy storage capacitor to a second voltage, wherein the sum of the first and second voltages exceeds the minimum anode voltage of said lamp and the second voltage exceeds the minimum holding voltage of said lamp;
• and
• c. voltage controlled capacitor switching means having input terminals coupled across said boost storage capacitor and across said energy storage capacitor and further including output terminals coupled to the anode and cathode terminals of said lamp for operating in a first state to couple said boost storage capacitor in series with said energy storage capacitor and to apply the sum of the first and second voltages to the anode and cathode terminals of said lamp to allow energy to flow from said boost storage capacitor and said energy storage capacitor into said lamp after the first stage ionization of the gas in said lamp has been achieved by said trigger means to initiate second stage ionization of the gas in said lamp and for operating in a second state to couple said energy storage capacitor to the anode and cathode terminals of said lamp before the sum of the first and second voltages falls below the minimum holding of said lamp to enable said energy storage capacitor to continue discharging energy into said lamp.

A method for flashing a gas discharge lamp having a gas interior, anode and cathode terminals, a trigger electrode, a minimum anode voltage and a minimum holding voltage, comprising:

• a. providing a trigger voltage source coupled to said trigger electrode to accomplish first stage ionization of the gas in said lamp;
• b. providing a boost storage capacitor and an electrolytic energy storage capacitor, wherein the capacitance rating of said energy storage capacitor is substantially greater than the capacitance rating of said boost storage capacitor;
• c. charging said boost storage capacitor to a first voltage;
• d. charging said energy storage capacitor to a second voltage having a magnitude greater than the minimum holding voltage but less than minimum anode voltage, wherein the sum of the first and second voltages exceeds the minimum anode voltage of said lamp;
• e. operating said trigger voltage source to initiate first stage ionization of the gas in said lamp;
• f. configuring said boost storage capacitor and said energy storage capacitor into a series-connected first state to apply a boost voltage having a magnitude greater than the minimum anode voltage across the anode and cathode terminals of said lamp to allow energy to flow into said lamp after initiation of first stage ionization of the gas in said lamp to initiate second stage ionization of said lamp;
• and
• g. configuring said boost storage capacitor and said energy storage capacitor into a second state after the boost voltage falls below the minimum anode voltage but before the boost voltage falls below the minimum holding voltage to couple said energy storage capacitor across the anode and cathode terminals of said lamp to enable said energy storage capacitor to discharge additional energy into said lamp.

Apparatus for flashing a gaseous discharge lamp having a gas interior, anode and cathode terminals, a trigger electrode, a minimum anode voltage and a minimum holding voltage, comprising:

• a. trigger means coupled to the trigger electrode of said lamp for generating a series of trigger pulses separated by defined time intervals to initiate first stage ionization of the gas in said lamp;
• b. a two element power supply including
• i. a boost power supply continuously coupled to a boost storage capacitor for applying a first voltage to said boost storage capacitor and for directing a charging current into said boost storage capacitor whenever the first voltage exceeds the voltage on said boost storage capacitor;
• ii. an energy storage power supply continuously coupled to an electrolytic energy storage capacitor for applying a second voltage having a level above the minimum holding voltage but below the minimum anode voltage to said energy storage capacitor, for directing a charging current to said energy storage capacitor whenever the second voltage exceeds the voltage on said energy storage capacitor, and for causing said energy storage capacitor to store a defined quantum of energy, said energy storage capacitor having an equivalent series resistance substantially lower than the equivalent series resistance of a high voltage electrolytic capacitor rated to operate at a voltage above the minimum anode voltage and capable of storing the defined quantum of energy at an operating voltage above the minimum anode voltage, the capacitance rating of said energy storage capacitor substantially exceeding the capacitance rating of said high voltage capacitor, wherein the sum of the first and second voltages exceeds the minimum anode voltage, wherein the capacitance rating of said energy storage capacitor is substantially greater than the capacitance rating of the boost storage capacitor and wherein said boost storage capacitor and said energy storage capacitor are recharged simultaneously during a part of each time interval between sequential trigger voltage pulses;
• and
• c. voltage controlled capacitor switching means having input terminals coupled across said boost storage capacitor and across said energy storage capacitor and output terminals coupled to the anode and cathode terminals of said lamp for operating in a first state to apply a boost voltage exceeding the minimum anode voltage across the anode an cathode terminals of said lamp to allow energy to flow from said boost storage capacitor into said lamp after first stage ionization of the gas in said lamp has been achieved by said trigger means to initiate second stage ionization of the gas in said lamp and for switching into a second state after the boost voltage falls below the minimum anode voltage but before the boost voltage falls below the minimum holding voltage to couple said energy storage capacitor across the anode and cathode terminals of said lamp to enable said energy storage capacitor to discharge energy into said lamp as the voltage on said energy storage capacitor decreases from the second voltage to the minimum holding voltage of said lamp;
• whereby said energy storage capacitor dissipates substantially less heat in its equivalent series resistance and operates at a lower temperature than the high voltage, higher equivalent series resistance electrolytic capacitor.

Apparatus for flashing a gaseous discharge lamp having gas interior, anode and cathode terminals, a minimum anode voltage and a minimum holding voltage, comprising:

• a. trigger means coupled to said lamp for generating spaced apart groups of trigger pulses, wherein each trigger pulse initiates first stage ionization of the gas in said lamp, wherein each group of pulses includes a primary trigger pulse and a secondary trigger pulse, wherein the primary and secondary trigger pulses are separated by a first time interval and each group of trigger pulses is separated by a second time interval, and wherein the duration of the first time interval is substantially shorter than the duration of the second time interval;
• b. capacitor means including a boost storage capacitor and an energy storage capacitor;
• c. power supply means coupled to said capacitor means for charging said boost storage capacitor to a first voltage having a magnitude less than the trigger voltage pulse magnitude and for charging said energy storage capacitor to a second voltage having a magnitude greater than the minimum holding voltage but less than the minimum anode voltage, wherein the sum of the first and second voltages exceeds the minimum anode voltage;
• d. voltage controlled capacitor switching means having input terminals coupled across said boost storage capacitor and across said energy storage capacitor and output terminals coupled to the anode and cathode terminals of said lamp for operating in a first state to apply a boost voltage exceeding the minimum anode voltage to the anode and cathode terminals of said lamp to allow energy to flow into said lamp after first stage ionization of the gas in said lamp to initiate second stage ionization of the gas in said lamp and for switching into a second state after the boost voltage falls below the minimum anode voltage but before the boost voltage falls below the minimum holding voltage to couple said energy storage capacitor across the anode and cathode terminals of said lamp to enable said energy storage capacitor to discharge additional energy into said lamp;
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• e. the capacitance rating of said boost storage capacitor being set at an adequately low value and the duration of the first time interval between the primary and secondary trigger pulses being set at an adequately high value such that said boost storage capacitor is charged to a voltage substantially equal to the first voltage during the first time interval and the capacitance rating of said energy storage capacitor being set at an adequately high value and the duration of the first time interval being set at an adequately low value such that said energy storage capacitor is charged to a voltage above the minimum holding voltage but below the second voltage during the first time interval and the second time interval between groups of trigger pulses being set at an adequately high value such that said energy storage capacitor is fully charged to the first voltage during the second time interval;
• whereby each primary trigger pulse initiates a full power flash from said lamp and each secondary trigger pulse initiates a reduced power flash from said lamp closely spaced in time relative to the full power flash.