US3219880A - Automatic starter for the ignition of gas arc lamps - Google Patents

Description

Nov. 23, 1965 M. T. PETT 3,219,880

AUTOMATIC STARTER FOR THE IGNITION OF GAS ARC LAMPS Filed June 2'7, 1963 l I I5 l2. 3 0

LAM P LAM P SHORT-ARC POWER SUPPLY lGNlTER GAS LAMP FIG. 1

E l 2| 20 l I ZENERi I D K INVENTOR. MAFZTI N T. PETT ZZf M w A770 EY United States Patent Office 3,219,880 Patented Nov. 23, 1965 3,219,880 AUTOMATIC STARTER FOR THE IGNITION F GAS ARC LAMPS Martin T. Pett, Canoga Park, Calif, assignor to Spectrolab, a corporation of California Filed June 27, 1963, Ser. No. 291,040 1 Claim. (Cl. 31524il) This invention relates generally to igniter circuits for are lamps and more particularly, to an improved automatic starter for the ignition of Xenon or other high power short-arc gas lamps.

Conventional gas are lamps require a high voltage plus of electrical energy to initiate conduction. After ignition, the arc lamp will operate at a relatively low operating voltage. The usual method for igniting such are lamps is to supply power from an auxiliary source or power supply other than the normal power supply for the lamp. High voltage for the high voltage pulse is developed by two transformers in a spark gap or gas discharge regulator. This prior system thus necessitates additional wiring and control switches.

Further, conventional starting methods for gas are lamps require the use of a high voltage transformer incapable of carrying the current required for normal operation of the lamp once it has been started. As a consequence, the high voltage transform-er secondary has had to be shorted out by a set of relay contacts after the lamp has been ignited. Such added contacts often lead to faulty lamp operation and require periodic maintenance.

In addition to the foregoing, many conventional starting systems require timers or external controls in order to control the starting pulses and terminate the starting pulses after the lamp has been ignited. Such timers or external controls merely add to the expense and maintenance of such starting circuits.

With all the forgoing in mind, it is a primary object of this invention to provide a gas are lamp igniter in which the foregoing problems are avoided.

More particularly, it is an object to provide an igniter adapted to be connected between the lamp power supply and the gas arc lamp itself as a permanent installation so that no connections need be made and subsequently removed each time the gas arc lamp is to be ignited.

Another object is to provide a novel igniter for gas are lamps which is completely automatic in operation in that once the lamp is ignited, the provision of high voltage pulses of electrical energy is automatically terminated to the end that timers or external controls are wholly unnecessary.

Another important object is to provide a novel igniter for gas are lamps which requires no auxiliary power sources for generating high voltage pulses of electrical energy to start the lamp so that considerable economy in the manufacture and maintenance of the starter is realizable.

Still another object is to provide a novel gas lamp igniter which does not require any high current switching to take place but in which the igniter itself constitutes part of the circuit for providing supply voltage and operating current to the lamp after it has been ignited.

Another object is to provide a gas are lamp igniter which incorporates a unique, integral, transformer construction, so that the use of a coupling capacitor may be avoided thereby eliminating a separate coupling capacitor as has been required heretofore in the prior art.

Briefly, these and many other objects and advantages of this invention are attained by providing an igniting circuit adapted to be permanently connected between the lamp power supply and the terminals of the gas are lamp. The igniter circuit itself includes a voltage storage means connected to the storage means and is responsive to a ply. A voltage responsive switching means in turn is connected to the storage means and is responsive to a given voltage across the storage means. A transformer means is connected between the switching means and the output lines of the igniter passing to the gas arc lamp for generating a pulse of high voltage energy in response to discharging of the storage means through the switching means.

The switching means, as stated, is designed to close only when a predetermined given voltage greater than the operating voltage of the gas lamp is stored in the storage means and is designed to open upon completion of the discharging of the storage means so that a pulse of high voltage energy is automatically periodically applied to the arc lamp by the transformer means until the lamp is operating.

The transformer means includes a high voltage auto transformer in which the secondary is in series with one of the output leads and is formed from a relatively thick strip of copper foil sufficient to carry the operating current of the lamp so that the secondary Winding becomes a permanent part of the lamp circuit. Further, short strips of conducting foil are disposed between the turns of the high voltage transformer windings during the winding process to provide a coupling capacitor which constitutes an integral part of the transformer. The cost of this type of capacitor is very small in comparison to the separate coupling capacitor conventionally used in prior art igniters.

A better understanding of the invention will be had by now referring to a preferred embodiment thereof, as illustrated in the accompanying drawings, in which:

FIGURE 1 is a simple block diagram showing how the lamp igniter of this invention is connected with the lamp power supply and short-arc gas lamp; and,

FIGURE 2 is a schematic drawing of the circuit incorporated within the lamp igniter illustrated in FIGURE 1.

Referring first to FIGURE 1, there is shown a lamp igniter 10 connected between a lamp power supply 11 and a short-arc gas lamp 12. As shown, input lines 13 and 14 to the lamp igniter 10 connect directly to the output lines of the power supply 11, and output lines 15 and 16 from the lamp igniter 10 connect directly to the electrodes of the short-arc gas lamp 12.

Once the lamp igniter has been connected between the power supply and short-arc gas lamp, it may be retained in place permanently.

Referring now to FIGURE 2, the igniter circuit includes a voltage storage means connected across the input lines 13 and 14. This storage means includes a charging resistance R and storage condenser C connected in series as shown. Also included is a voltage responsive switching means including a zener diode D in series with a relay coil K to provide a series circuit connected across the condenser C. Switch contacts K for the relay coil K in turn are connected in series with the primary coil 17 of a first auto transformer TI. This series circuit defines a discharge path for the condenser C when the relay contacts K are closed, this discharge path passing through the primary coil 17 of the transformer T1.

The transformer T1 constitutes part of a transformer means arranged to provide a high voltage pulse of electrical energy in response to discharging of the condenser C through the discharge path defined by the relay contacts K. This high voltage pulse of electrical energy is generated in the secondary coil 18 of a second high voltage auto transformer T2 shown connected in series with the input and output lines 13 and 15. The primary coil 19 of the transformer T2 is connected to one end of the secondary coil 20 of the auto transformer T1, the other 3 end of this secondary coil 20 connecting to the output line 16.

The transformer circuit is completed by a modulating spark gap S connected between the primary coil 19 of the transformer T2 and the junction point 21 between the charging resistance R and storage condenser C.

Assume that the normal operating voltage for the short-arc gas lamp 12 is 30 volts and that the open circuit power supply voltage from the lamp power supply 11 is approximately 100 volts. Under these conditions, the relay coil K is designed to have a pull-in voltage of approximately 20 volts and the zener diode D is designed to conduct at approximately 82 volts. The operation of the circuit of FIGURE 2 is then as follows:

When the power supply 11 of FIGURE 1 is turned on, approximately 100 volts will be applied across the input lines 13 and 14. This same open circuit voltage will appear across the output lines 15 and 16 and be applied to the terminals of the short-arc gas lamp 12. Since the voltage required to ignite or start operation of the gas lamp is considerably higher than the operating voltage for the gas lamp and open circuit voltage of the power supply, the gas lamp 12 will remain inert. However, as soon as the supply voltage of approximately 100 volts is applied to the input lines 13 and 14, the condenser C will commence charging through the charging resistance R. When the condenser C is charged up to approximately the open circuit voltage of 100 volts, or to a value which exceeds the zener voltage of 82 volts by the amount of voltage necessary to operate the relay coil K, the relay coil will be energized when the zener diode D conducts to close the relay coil contacts K.

As soon as the contacts K are closed, the voltage across the condenser C will immediately discharge through the switch, contacts K and the primary 17 of the auto transformer T1. The secondary voltage induced in the secondary coil 20 of the auto transformer T1 will build up in the primary coil 19 of the high voltage transformer T2 and thence suddenly be modulated as a consequence of the provision of the spark gap S. This sudden change in the voltage in the primary 19 in turn induces an extremely high energy output voltage pulse in the secondary coils 18 of the high voltage transformer T2 which high voltage pulse is supplied by the output line 15 to the short-arc gas lamp 12 of FIGURE 1.

Once the condenser C has discharged as described, the relay coil contacts K will open since no energy is available to hold the relay coil K energized.

If the gas lamp 12 ignites in response to the provision of this high energy pulse, it will continue to conduct, the open circuit voltage from the power supply then being reduced to the operating voltage of the short-arc gas lamp. As stated, this operating voltage may be of the order of volts so that while the condenser C will charge to 30 volts, there will not be sufiicient voltage to operate the zener diode D and thus the relay coil K will remain unenergized and for all practical purposes the portion of the lamp igniter circuit between the input leads 13 and 14 may be considered as disconnected. In this respect, it should be noted that normal operating current for the gas lamp will pass through the secondary windings 18 of the auto transformer T2. These windings are formed, in the preferred embodiment, with a two inch wide and .016 inch thick strip of copper foil so that the winding can readily accommodate the operating current required by the short-arc lamp and thus can be retained as a permanent part of the lamp circuit.

If the initial high voltage pulse of energy supplied to the short-arc gas lamp 12 does not result in ignition of the gas lamp, the open circuit voltage applied to the lines 13 and 14 will remain at its value of approximately 100 volts and thus the condenser C will immediately commence charging again through the resistance R. When this normal open circuit voltage is attained across the condenser C, the zener D will again conduct to energize the coil K and again close the switch contacts K, thereby discharging the voltage across the condenser C through the primary 17 of the auto transformer T1. The cycle of events to initiate the generation of a high voltage pulse on the secondary 18 of the transformer T2 will then repeat, so that a second high voltage pulse of electrical energy will be aplied to the gas lamp.

This process will continue and a succession of high voltage pulses will be periodically passed to the gas lamp until ignition of the lamp takes place. The time interval between the pulses is determined approximately by the charging time of the condenser C which is controlled by its capacitance and the value of the charging resistance R. Representative values for these circuit components for the voltage conditions described above may be ohms for the resistance R and 800 microfarads for the storage condenser C.

As stated heretofore, the secondary winding of the transformer T2 is formed from a fixed strip of copper foil. By placing additional short strips of copper foil between the turns of the secondary of the anto transformer T2 during the winding process, a capacitor is created which is an integral part of this transformer. This capacitor foil is separated from the transformer secondary copper strip by appropriate layers of mylar to withstand the high voltages involved. The cost of this type of capacitor is very small by comparison to a separate coupling capacitor used conventionally.

From the foregoing description, it will thus he evident that the present invention has provided a greatly improved gas are lamp igniter circuit. The device is completely automatic in operation and simple in design. The starting pulses automatically cease upon lamp ignition, this action being a direct result of the use of the zener diode and relay combination. Thus, external timers and controls are wholly unnecessary.

Minor variations and substitutions of equivalent components for those shown and described will occur to those skilled in the art without departing from the scope and spirit of this invention. For example any equivalent voltage sensitive switch may be substituted for the zener diode. Also, the voltage and resistance values of the lamp described may be different for other short-arc lamp types. The gas lamp igniter is therefore not to be thought of as limited to the exact structural components and values given therefor merely for purposes of illustration.

What is claimed is:

A gas arc lamp igniter having input and output lines for connection, respectively, to the output lines of a power supply and the input terminals of a gas are lamp for igniting said are lamp and supplying operating voltage from said power supply to said lamp, said igniter comprising, in combination: a charging resistance and series connected condenser connected across said input lines; a zener diode and series connected relay coil connected as a series circuit across said condenser; a switch operable upon energization of said relay coil; a first auto transformer having a primary terminal, a secondary terminal and a center-tap terminal, said switch being connected in series with said center-tap terminal and the junction point of said charging resistance and condenser, and said primary terminal connecting to the other side of said condenser so that closing of said switch discharges current from said condenser through the primary of said auto transformer; a high voltage second auto transformer having a primary terminal, a secondary ter minal and a center-tap terminal, said primary terminal connecting to one of said input lines, said secondary terminal connecting to one of said output lines and said center-tap terminal connecting to the secondary terminal of said first auto transformer, the said other side of said condenser connecting to the other of said output lines; and a spark gap connected between said center-tap terminal of said second auto transformer and said junction point of said charging resistance and condenser, said switch closing only when a predetermined voltage greater than the operating voltage of said are lamp is stored in said condenser, is exceeded and opening upon discharging of said condenser whereby a pulse of high energy from said secondary terminal of said second auto transformer is automatically periodically applied to said are lamp until said lamp is operating.

References Cited by the Examiner UNITED STATES PATENTS 2,717,337 9/1955 Laird 315289 6 2,856,563 10/1958 Rively 3l5-24l X 2,887,592 5/1959 Stout et al 315-209 X 2,985,797 5/1961 Williams et a1. 3l5209 3,133,204 5/1964 Winchel 307-885 OTHER REFERENCES Silicon Zener Diode and Rectifier Handbook (2nd Edition) Copyright 1961, Motorola Inc., page 79 FIGURES 4-5.

10 DAVID J. GALVIN, Primary Examiner.

JAMES D. KALLAM, Examiner.

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