US3611433A - Plasma power supply for arc discharge device - Google Patents

Plasma power supply for arc discharge device Download PDF

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Publication number
US3611433A
US3611433A US823802A US3611433DA US3611433A US 3611433 A US3611433 A US 3611433A US 823802 A US823802 A US 823802A US 3611433D A US3611433D A US 3611433DA US 3611433 A US3611433 A US 3611433A
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voltage
current
supply circuits
winding
circuit
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US823802A
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English (en)
Inventor
Stephen J Erst
Ralph H Beardsley
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TDK Micronas GmbH
ITT Inc
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Deutsche ITT Industries GmbH
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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B41/00—Circuit arrangements or apparatus for igniting or operating discharge lamps
    • H05B41/02—Details
    • H05B41/04—Starting switches
    • H05B41/042—Starting switches using semiconductor devices

Definitions

  • a plasma power supply for use in a starting and operating system for a high-intensity, high-pressure arc discharge lamp, such as a xenon lamp.
  • a high-voltage, alternating current source is serially coupled in the lamp circuit for starting the lamp, and a low-voltage, direct current source is coupled across the lamp circuit by a current-limiting ballast resistor and isolating diode.
  • the plasma power supply comprises a plurality of plasma voltage supply circuits respectively having one side coupled to progressively higher voltage points on a transformer secondary winding by diodes, the other sides being common and coupled to a common point on the transformer winding.
  • Each of the supply circuits has a currentlimiting resistor therein, the common side of the supply circuits being connected to one side of the low-voltage source and the other sides being connected together and to the lamp circuit.
  • the supply circuit resistors are proportioned to backbias the diodes so as sequentially to apply progressively lower voltages to the lamp circuit in response to increase in the current flow in the lamp following starting, this proportioning being such that the voltage/current characteristic of the applied voltages generally approximates the voltage/current characteristic of the lamp.
  • High-pressure, high-intensity arc lamps such as xenon, mercury, or mercury-xenon arc lamps, require a very high voltage in the general range from to 60 kv. for initial ionization of the gas, i.e. to start" the lamp.
  • interclectrode, wirelike discharges appear causing local hotspot heating of the cathode which thus becomes an emitter of electrons with the potential drop across the electrodes becoming lower.
  • a much lower voltage in the general range from 65 to 140 volts will sustain and support buildup of the plasma" arc.
  • the arc current has built 'up to its operating value, a still lower voltage in the general range from 20 to 35 volts will sustain the are at its operating current level.
  • the starting and operating system for such lamps must supply three distinct requirements: the high starting voltage; the much lower plasma supply voltage; and the still lower operating voltage. While the starting voltage for such lamps may be an alternating current voltage, the plasma and operating voltages must be direct current since the arc cannot be sustained from an alternating current source.
  • Such lamps in common with all are discharge devices, have a negative voltage/current exponential characteristic, i.e. the interelectrode resistance decreases exponentially as the arc current increases, and thus it is necessary to provide a currentlimiting impedance or ballast in the lamp circuit in order to provide the desired operating current and to prevent ultimate destruction of the lamp.
  • Prior starting and operating systems for such lamps known to the present applicants have employed a plasma power supply providing a single direct current voltage in the general range from I20 to 140 volts. We have observed that there is a tendency for the plasma arc to blow out of the direct path between the lamp electrodes thereby reducing the probability of completing the ignition.
  • the ballast impedance is generally a series resistor which provides a linear voltage/current characteristic, a high-reactance transformer, or some combination thereof. None of these conventional ballasting techniques provides a voltage/current characteristic corresponding to that of the lamp and thus, excessive energy is consumed in the ballast in order to provide the requisite limitation of lamp current.
  • a plasma power supply having a plurality of output circuits respectively providing progressively higher direct current voltages. These supply circuits are sequentially coupled to the lamp so as to apply progressively lower voltages thereto in response to increase in the plasma current flow. Further, a ballast resistor is provided in each of the plasma voltage supply circuits, these resistors being proportioned so that the composite voltage/current characteristic generally approximates that of the lamp.
  • FIG. 1 is aschematic block diagram showing a starting and operating system for an arc discharge device incorporating the plasma power supply of the invention
  • FIGS. 2A, B and C show the voltage/current characteristics provided by conventional ballasting techniques
  • FIG. 3 shows the voltage/current characteristic of a typical high-pressure, high-intensity arc discharge lamp
  • FIG. 4 is a schematic diagram showing one embodiment of the plasma power supply of the invention.
  • FIG. 5 shows the voltage/current characteristic provided by the plasma power supply of FIG. 4 and
  • FIG. 6 is a schematic diagram showing a modification of the system of FIG. 4.
  • FIG. 1 there is shown a starting and operating system 10 having its output terminals 11 and 12 connected across the anode l3 and cathode 14 of a high-pressure, high-intensity arc discharge lamp 15, such as a xenon lamp.
  • a high-voltage ignition circuit 16 is coupled in series with anode l3 and is energized from a source 17 of alternating current.
  • a source 18 of direct current operating voltage and a ballasting resistor 19 and isolating diode 20 are serially connected with igniter circuit 16 across output terminals 1 I, 12.
  • the plasma power source 22 is coupled across the serially connected ballasting resistor 19 and insulating diode 20.
  • a series-ballasting resistor provides a linear voltage/current characteristic as shown in FIG. 2A.
  • a high-reactance transformer employed for ballasting provides a nonlinear, exponential voltage/current characteristic as shown in FIG. 25.
  • Employment of a series-ballasting resistor in conjunction with a high-reactance transformer provides a more linear, but still exponential voltage/current characteristic as shown in FIG. 2C.
  • the negative, exponential, voltage/current characteristic of a typical arc discharge device is shown in FIG. 3, and it will be seen that the voltage/current characteristics of the resistive and high-reactance devices, as shown in FIGS. 2A, B and C, do not at all correspond to the lamp characteristic, and it will be observed that each of these ballasting techniques involves excessive energy loss.
  • a transformer 23 having its primary winding 24 energized, preferably at 400 cycles, by inverter 25 coupled across low voltage direct current power source 18, which may be a 28 volt source.
  • Secondary winding 26 of transformer 23 has a center tap 27, and a plurality of progressively higher voltage taps 28, 29 and 30 respectively on opposite sides thereof. In the illustrated embodiment, three progressively higher alternating current voltages are provided by taps 28, 29 and 30. Center tap 27 is coupled to the positive terminal 32 of direct current source I8 by lead 33.
  • Plasma voltage supply circuits 34, 35 and 36 are provided respectively having series ballast resistors 37, 38 and 39 therein.
  • Plasma voltage supply circuits 34, 35 and 36 are respectively connected to taps 28, 29 and 30 of secondary winding 26 by diodes 40, 42 and 43 which thus provide fullwave rectification of the three progressively higher alternating current voltages respectively applied to the plasma voltage Section 53 of secondary winding 26 has its side 54 coupled to lead 44 by momentary start switch 55 and its other side 56 coupled thereto by capacitor 57.
  • Spark gap 58 couples side 56 to tap 59 on ignition transformer winding 45.
  • a relay 60 is provided having a voltage-responsive operating coil 62 coupled across ballast resistor 19 and having normally closed contacts 63 coupled in series with primary winding 24 of transformer 23.
  • operating coil 62 will actuate contacts 63 to open the energizing circuit of primary winding 24.
  • switch 55 is momentarily closed thereby coupling capacitor 57, section 64 of ignition transformer winding 45, and spark gap 58 across transformer secondary winding section 53, the capacitor 57 and spark gap 58 thereby in known fashion generating a high-voltage pulse in section 64 of transformer winding 45 to apply the requisite high-voltage starting pulse across the electrodes of lamp 15. While a manually actuated starting switch 55 is shown it will be understood that a conventional automatic starting switch may be employed.
  • ballast resistors 37, 38 and 39 are proportioned respectively to provide voltage/current characteristics 65, 66 and 67 as shown in FIG. 5, the resultant composite, stepped characteristic generally approximating the lamp characteristic, as shown in FIG. 3.
  • ballast resistor 38 has been eliminated from the plasma voltage supply circuit 35, and replaced by ballast resistor 68 serially connected in the common lead 33.
  • ballast resistor 68 and 39 again the initial plasma current flow through ballast resistors 68 and 39 is insufficient to reduce the potential lead 44 sufficiently to remove the back-bias on diode 42.
  • the increased current flow flowing through both resistors results in unloading the highest voltage supply circuit 36 and removing the back-bias on diode 42.
  • a starting and operating system for an arc discharge device comprising an output circuit connected to said device, first means coupled to said output circuit for supplying a relatively high voltage for starting said device, second means coupled to said output circuit for supplying a first relatively low direct currentvoltage for operating said device and including first means for limiting the operating current flow in said device; and a direct current plasma power supply coupled to said output circuit and including a plurality of plasma voltage supply circuits for supplying a corresponding plurality of direct current voltages respectively progressively higher than said first voltage, each of said supply circuits including bias means for limiting the current flow therein said bias means being coupled to said output circuit and sequentially applying progressively lower ones of said plurality of voltages thereto in response to increasing current flow in said device following starting thereof.
  • each said bias means includes a current-limiting resistor and diode respectively coupled in series with each supply circuit.
  • bias means and supply circuits comprise an OR circuit.
  • said plasma power supply includes means for providing a corresponding plurality of progressively higher alternating current voltages and having said supply circuits coupled thereto, said diode in each of said supply circuits providing a rectified alternating current voltage.
  • said alternating current voltages providing means comprises a transformer secondary winding having a common point, each of said supply circuits having one side connected to different voltage points on said winding with respect to said common point, the other sides of said supply circuits being connected together and to said common point, each supply circuit including said diode and resistor serially connected in said one side, said common sides of said supply circuits being connected to one side of said output circuit and the one side of each of said supply circuits being connected through said winding to the other side of said output circuit, said resistors being proportioned so that only the diode connected in the highest voltage supply circuit is initially conductive upon starting of said device with the remaining diodes being initially back-biased out of conduction and being sequentially biased into conduction in response to the increase in current flow through said device.
  • said low-voltage supplying means includes a source of direct current voltage having one side connected to said common side of said supply circuits and the other side thereof connected to said one side of said output circuit, said first current-limiting means comprising a resistor series-connected with an isolating diode between said one side of said source and said other side of said output circuit.
  • said first supplying means includes a second transformer secondary winding connected in series with said output circuit, and further comprising means coupling a pan of said first-named transformer winding to said second transformer winding for inducing said starting voltage therein.
  • said alternating current voltages providing means comprises a transformer secondary winding, each of said supply circuits having first and second sides, the second sides being connected in common and to a midpoint on said winding, each said supply circuit including a pair of diodes respectively connecting the first sides of said supply circuits to corresponding points on said winding on opposite sides of said midpoint to provide full-wave rectification of the alternating current voltages respectively supplied to said supply circuits, each of said bias means comprising a current-limiting resistor connected in series with each said pair of diodes in one side of a respective supply circuit, said common sides of said supply circuits being connected to one side of said output circuit and the first sides of said supply circuits being connected through said winding to the other side of said output circuit, said resistors being proportioned so that only the pair of diodes connected to the highest voltage points on said winding are initially conductive upon starting of said device with the remaining pairs of diodes being initially back-biased out of conduction and being sequentially biased into conduction in response to
  • the system of claim 12 further comprising a filter circuit coupled across said supply circuits.
  • said low-voltage supplying means includes a source of direct current voltage having one side connected to said common side of said supply circuits and the other side thereof connected to said one side of said output circuit, said first current-limiting means comprising a resistor and isolating diode connected in series between said one side of said source and said other side of said device, said first supplying means including a second transformer secondary winding connected in series with said output circuit and further comprising means coupling a part of said first-named transformer winding to said second transformer winding for inducing said starting voltatge therein, and means responsive to a predetermined current ow in said last-named resistor for disabling said plasma power supply.

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US823802A 1969-05-12 1969-05-12 Plasma power supply for arc discharge device Expired - Lifetime US3611433A (en)

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US82380269A 1969-05-12 1969-05-12

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DE (1) DE2020786A1 (de)
GB (1) GB1265944A (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5077770A (en) * 1990-07-05 1991-12-31 Picker International, Inc. High voltage capacitance discharge system for x-ray tube control circuits
US20090160417A1 (en) * 2007-12-24 2009-06-25 Huettinger Electronic Sp. Z.O.O. (Tple) Current limiting device for plasma power supply

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AT369609B (de) * 1980-09-11 1983-01-25 Elger Elektro Neon Schaltungsanordnung fuer den betrieb von gasentladungslampen
HU208778B (en) * 1983-07-28 1993-12-28 Tungsram Reszvenytarsasag Operating circuit for a high-pressure sodium or metal-halogen lamp

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5077770A (en) * 1990-07-05 1991-12-31 Picker International, Inc. High voltage capacitance discharge system for x-ray tube control circuits
US20090160417A1 (en) * 2007-12-24 2009-06-25 Huettinger Electronic Sp. Z.O.O. (Tple) Current limiting device for plasma power supply
US8981664B2 (en) * 2007-12-24 2015-03-17 TRUMPF Huettinger Sp. zo. o. Current limiting device for plasma power supply

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DE2020786A1 (de) 1970-11-19
GB1265944A (de) 1972-03-08

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Owner name: ITT CORPORATION

Free format text: CHANGE OF NAME;ASSIGNOR:INTERNATIONAL TELEPHONE AND TELEGRAPH CORPORATION;REEL/FRAME:004389/0606

Effective date: 19831122