US3436595A - Illuminating lamp power supply - Google Patents

Description

April 1, 1969 KNEISLEY ET AL 3,436,595

ILLUMINATING LAMP POWER SUPPLY Filed Oct. 23, 1965 3 PHASE AC POWER SUPPLY I I A 2 i C. mmg gag [4 /46%/6 P405 /4c5 Mk P/oc +20V.D.C.

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United States Patent 3,436,595 ILLUMINATING LAMP POWER SUPPLY Richard F. Kneisley, and Thomas R. Kneisley, Toledo, Ohio, assignors to The Kneisley Electric Company, Toledo, Ohio, a corporation of Ohio Filed Oct. 23, 1965, Ser. No. 503,929 Int. Cl. H05b 37/02, 39/09 U.S. Cl. 315165 4 Claims ABSTRACT OF THE DISCLOSURE A power supply for gas-filled lamps requiring an initial pulse of high voltage and a continuing low voltage DC supply. The supply circuit includes -a source of alternating current, and separate sources of high and low voltage current operably connected to a sparking device and a time delay relay such that initial energization of the device will apply a high voltage spark generated by the AC source across the lamps along with the high voltage direct current. The relay subsequently disconnects the AC source and the high voltage DC source and connects the low voltage DC supply to the lamp terminals.

This invention relates to a power supply for gas filled illuminating lamps which requires an initial high voltage pulse to break down the gap between the anode and cathode electrodes to start an arc, and a constant supply of relatively low voltage, direct current to maintain the electron stream between the anode and cathode electrodes once the gap has been bridged by the arc. More specifically, this invention relates to a power supply which is capable of supplying to gas filled illuminating lamps, such as xenon lamps, an initial high energy pulse in the order from to 50 kilovolts and at the same time a direct current voltage sufiicient to initiate an electron stream and finally a lower voltage direct current voltage to maintain the electron stream between the anode and cathode electrodes of the lighted lamps.

The power supply of this invention is particularly adapted for use with recently developed xenon arc lamps which are superior to conventional carbon are or incandescent lamps in many applications, such as motion picture projection, spot and flood lighting installations, etc. While the power supply of this invention may be used with other types of illuminating devices, it is described herein in relation to a xenon lamp which requires an initial high voltage, high energy pulse to bridge the gap between the anode and cathode electrodes in the xenon lamp and simultaneously requires a direct current voltage to initiate and maintain a stream of electrons across the gap until it is well established and may be efiiciently maintained by a lower voltage direct current supply.

Xenon lamps up to 8000 watts are commercially available, producing 38,000 foot-candles from an effective are area of only 16 sq. mm. The lamps are direct current operated devices, which consist generally of two tungsten electrodes enclosed in an envelope of fused quartz. In a typical 1600 watt xenon lamp, a high voltage pulse of from 20 to 50 kilovolts is required to ionize the gap between the tungsten electrode. Once this high voltage pulse has bridged the electrode gap, a direct current potential of approximately 80 volts is required to initiate and maintain the arc until an electron stream of sufficient density has been established, at which time a lower direct current voltage of approximately 20 volts is Sllfi'lClfiIlll to maintain the electron stream. It will be seen, therefore, that power supplies for such lamps necessarily must be capable of producing the 20 to 50 kilovolt pulse, along with the 80 volt DC potential, and preferably ice will automatically drop this DC potential to a value of about 20 volts, after the electron stream has been established.

Accordingly, it is an object of this invention to provide a power supply for gas filled illuminating lamps which is capable of supplying a high voltage pulse to the terminals of such gas filled lamp, along with a lower voltage direct current, and then will supply a lower direct current voltage to the lamp terminals.

It is another object of this invention to produce a power supply capable of maintaining a number of gasfilled illuminating lamps, such as the xenon lamps previously described, in operation in parallel circuits, which power supply is capable of producing an initial pulse of high voltage energy, a second supply of lower DC voltage and a third supply of yet lower DC voltage.

Other objects and advantages of the invention will be apparent from the following detailed description of a preferred embodiment thereof, reference being made to the accompanying drawings, in which:

The figure is a circuit diagram of the illuminating lamp power supply of this invention, showing a three phase, AC power supply with two separate rectifier stacks, and a means for supplying the initial high voltage pulse and lower voltage direct currents to a single gas filled illuminating lamp.

A three phase, AC power supply having three separate windings, A, B, and C is shown with each of these windings tapped at 10a, 10b, and and at the common terminal :11 to supply an AC voltage of for example volts in bus lines 12 and 13. Each of the windings A, B, and C is also tapped at 14a, 14b, and 140, which taps are operably connected to a first rectifier stack, generally designated by reference numeral 115, the output of which is connected to a positive busline 16 and a negative busline or common ground 17. The taps 14a, 14b, and are positioned on windings A, B, and C such that the rectitfied output of the rectifier stack 15 has a value of, for example, 80 volts DC.

Each of the windings A, B, and C is also tapped at points 18a, 18b, and .180, which points are connected to a second rectifier stack, generally designated by reference numeral 19. The positive output of the second rectifier stack 10 is connected to a busline 20' and the negative output thereof is connected to the common ground 17. The taps 18a, 18b and are positioned on the windings A, B, and C such that the DC output of the second rectifier stack 19 is of a value lower than the output of the rectifier stack 15, such as 20 volts positive for example.

It is to be understood that the components previously described comprise a common power supply which may be used to supply AC and DC voltages of appropriate value to any number of xenon lamps which may be operably connected in parallel to the buslines 12, 13, '16, 17 and 20, as will be described in detail. Each of the xenon lamps must be associated with its own individual ignition pulse producing mechanism and appropriate relays, as will be described, but may be powered from the common power source previously described.

A gas filled illuminating lamp, such as a xenon lamp L is connected between buslines 16 and 17 through a dropping resistor 21, a normally closed, solenoid operated switch 22, an adjustable resistor 23 and the winding 24 of a Tesla coil, the purpose of which will be subsequently explained. The lamp L is also connected across buslines 20 and 17, which supply 20 volts DC, through the adjustable resistor 23-, a line 25 and a normally open pole 26 of a double pole solenoid operated switch 27 and 27 is connected by a line 31 to one end of the primary winding of a voltage step-up transformer 32. The other end of this primary winding of the transformer 32 is connected to the other AC busline 13 by a line 33.

The operating windings 34 and 35 of the solenoid operated switches 22 and 27, respectively, have one end connected to the busline 16 by a common line 36. The other end of the solenoid 34 is connected to the xenon lamp L through the adjustable resistor 23 and line 25 at a junction 37 which also connects to the other terminal of the pole 26 of the double pole switch 27. The other end of the winding 35 of the double pole switch 27 is connected by a line 39 to the junction 37 and thus the xenon lamp L through one pole of a normally closed, manually operated double pole single throw switch 40. The other pole of this switch 40 connects the lines 30 and 31 so that when the switch 40 is manually moved to its open position, shown in dotted lines, all power to the primary of the transformer 32 and to the winding 35 of the switch 27 is shut oil.

The secondary of the transformer 32 is connected, by lines 41 and 42, to the primary of the Tesla coil winding 24 through a multiple condensor stack 43 which serves as an energy storing device. A pair of points 44 forming a spark gap is connected in parallel with the primary of the Tesla coil winding 24, in the manner well known to those skilled in the art. Finally, a time delay capacitor 45 is connected in parallel with the winding 34 of the solenoid operated switch 22 and a filter capacitor 46 is connected in parallel with the Tesla winding 24 and xenon lamp L, as shown.

The operation of the power supply circuit previously described is as follows. When an operator desires to light the xenon lamp L, the manually operated switch is closed. Closing the switch 40, simultaneously completes two circuits: (1) alternating current circuit from buslines 12 and 13 through the primary of the transformer 32 is completed through the normally closed pole 29 of the switch 26, the closed switch 40, line 31, the primary winding, and line 33, (2) 80 volt direct current circuit is completed from the busline 16, through the dropping resistor 21, the normally closed switch 22, the adjustable resistor 23, the xenon lamp L, and the winding of the Tesla coil 24 to the negative busline 17. In parallel with this circuit, an 80 volt direct current is applied across the windings 34 and 33 through the line 36 to the junction 37.

Within a few milliseconds, current through the windings 35 of the solenoid operated switch 27 pulls both poles 26 and 29 to the left, as shown in FIGURE 1, thus closing pole 26 and opening pole 29. When the pole 26 closes, a 20 volt DC circuit is completed to the xenon lamp L, through the line 28, the closed pole 26 of the switch 27, the lines 38 and 25, the adjustable resistor 23, the Xenon lamp L, and the winding of the Telsa coil 24 to the common ground busline 17. At the same time, the pole 29 is opened, thus breaking the AC circuit to the primary of the power transformer 32.

The slight delay of a few miliseconds necessary to saturate the winding 35 of the switch 27 to break the AC power circuit to the transformer 32 is sufiicient time for the transformer 32 and the Tesla coil to generate a high voltage spark across the electrodes of the Xenon lamp L in a manner well known to those skilled in the art. Very briefly, the alternating current in the primary of the power transformer 32 induces a very high voltage secondary current which charges the condenser stack 43 to an energy level sufficient to break down the gap between the points 44. This stored energy is discharged through the primary of the Tesla coil 24, thus inducing a very high voltage pulse in the secondary of the Tesla coil winding 24, which discharges across the electrodes in the xenon lamp L to ionize the gas across the gap. At the same time, the 80 volt direct current is applied across the lamp L to start the flow of electrons therein. This 80 volt potential is suflicient to initiate and maintain a stream of electrons which, once established, can be maintained by a lower direct current potential, such as 20 volts.

When the double pole switch 27 is moved to the left by the winding 35, the 80 volt and 20 volt DC buslines are connected in parallel simultaneously with the xenon lamp L until the normally closed switch 22 has been opened by its solenoid. This does not occur for a short time due to the time delay characteristics of the circuit including the capacitor connected in parallel with the winding 34. After a predetermined time which may be varied by selection of a capacitor 45 of an appropriate value, the winding 34 will open the switch 22, thus breaking the volt power supply to the xenon lamp L, whereby the 20 volt power supply alone will maintain the flowing stream of electrons, and ignition of the lamp L.

It will be seen that an important feature of this invention is the provision of three separate power supplies to the xenon lamp, (1) the high voltage pulse to ionize the xenon gas, (2) the 80 volt direct current supply to initiate the electron flow therein, and (3) the 20 volt direct current supply to maintain the lamp on. Another important feature of this invention is the time delay characteristic provided by the winding 34 and capacitor 45 which insures that the 80 volt direct current power supply is not turned off until the 20 volt supply has been connected across the xenon lamp L for a short time. Thus, no interruption of power to the xenon lamp is possible.

Another important feature of this invetnion is the provision of a single common power supply of AC and high and low DC voltages which can be used to power a large number of separate lamps connected in parallel, each lamp capable of independent operation and having its own ignition components. Thus a large cost savings in multiple lamp installations is effected through the use of a single power supply for a plurality of separate lamps, each lamp having its own igniter circuit.

It will be understood that various modifications to the described circuitry may be made, such as other energy storage sources for the high voltage pulse and various other means for providing the time delay characteristics of the normally closed switch 22. Various other modifications of the above-described preferred embodiment of this invention will be apparent to those skilled in the art and it is to be understood that such modifications can be made without departing from the scope of the invention, if within the spirit and tenor of the accompanying claims.

We claim:

1. An ignition and power supply apparatus for gasfilled lamps comprising, in combination, a power supply including a first source of direct current, a second source of direct current of a voltage lower than said first source and a third source of alternating current, at least one separate igniter device operably connected to said bus lines, said igniter device comprising a high voltage generator operably connected to said third source of alternating current, a pair of terminals for connection to an illuminating lamp, means including a normally closed first switch for connecting said pulse generator to said terminals, means including a normally closed second switch for connecting said terminals to said first source of direct current in parallel with said pulse generator, means including a normally open third switch for connecting said terminals with said second source of direct current in parallel with said first source and said pulse generator, means for simultaneously opening said first switch and closing said third switch, and means for subsequently opening said second switch after said first and third switches are simultaneously opened and closed respectively.

2. The power supply of claim 1 wherein said switches are solenoid operated and wherein said means for opening said second switch includes a time delay capacitor in parallel with the winding of the solenoid for said second switch.

3. The power supply of claim 1 wherein said pulse generator comprises an auto transformer having secondary taps operably connected to said lamp terminals and having primary taps operably connected to said alternating current source through a chraging capacitor, and means responsive to the level of energy stored in said capacitor for discharging said capacitor through said auto transformer primary when the level of energy stored in said capacitor exceeds a predetermined value.

4. The power supply of claim 3 wherein said pulse generator further includes a voltage step-up transformer having primary and secondary windings, said primary 6 said secondary winding operably connected to said charging capacitor whereby high voltage from said secondary winding will charge said capacitor.

References Cited UNITED STATES PATENTS 3,156,826 11/1964 Mutschler 250-199 3,323,012 5/1967 Seib 315174 3,334,270 8/1967 Nuckolls 315-171 10 JOHN W. HUCKERT, Primary Examiner.

SIMON BRODER, Assistaint Examiner.

US. Cl. X.R.

winding connected to said alternating current source and 15 315 163, 176

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