Abstract: A novelty device comprising an energizing circuit, including an dielectric base material, having a circuit and a conductive member attached to a first surface of the dielectric base material. The novelty device further includes a transparent display, containing an inert gas, such as neon or argon, being illuminated when the transparent display is brought into sufficiently close proximity to the surface opposite the surface carrying the conductive member and the energizing circuit, when power is supplied to the circuit. The invention also relates to a method for illuminating the transparent display, containing an inert gas, such as neon or argon, by the use of the energizing circuit.

Abstract: The electrodeless low pressure discharge lamp has a lamp vessel (1) having a cavity (3) at an end portion (2) thereof. An electric coil (4) surrounding a plastic tube (5), wherein a liquid filled tubular container (7) surrounded by a soft-magnetic core (6) is present, is accommodated in the cavity (3). The tubular container (7) is at a portion outside the cavity (3) rigidly secured in a recess (82) present in a protrusion (81) present at a flange (8). A mounting member (9) bearing the plastic tube (5) and the lamp vessel (1) is securable to the flange (8).

Abstract: A high intensity discharge lamp device is formed from materials which form complex halides enclosed in an arc tube in addition to rare gas and metal halides, to realize the high reproducibility of luminous color called for in visual machines and devices and so on.

Abstract: This electrodeless high intensity discharge lamp including a light-transmissive arc tube having spaced wall portions of dielectric material and a first gaseous fill within the arc tube. An excitation coil about the arc tube is energizable with RF current effective to develop a toroidal arc discharge in the first gaseous fill upon a dielectric breakdown of the fill. A starting container is joined to the arc tube and has an end wall constituted by one of said arc-tube wall portions. A second gaseous fill within the starting container has a dielectric strength lower than that of the first gaseous fill. For initiating the rotoidal arc discharge, we provide an arrangement for producing a dielectric breakdown of the gaseous fill within the starting container that develops into an electric discharge that changes the potential at the end wall in such a manner as to cause a dielectric breakdown of the first gaseous fill.

Abstract: A circuit arrangement suitable for operating low-pressure mercury discharge lamp by means of a high-frequency current includes circuitry (I) for generating the high-frequency current from a supply voltage, and a modulator (II) for the substantially square-wave modulation of the amplitude of the high-frequency current at a modulation frequency f. The circuit arrangement is further provided with circuitry (V) for limiting the amplitude of the re-ignition voltage across the low-pressure mercury discharge lamp to a voltage Vi. As a result, interference with infrared systems caused by a discharge lamp operated by the circuit arrangement is substantially fully suppressed.

Abstract: A high frequency applicator for energizing electrodeless lamps is described. The applicators are end cups electrically attached to the ends of phased feed points of a planar transmission line, and facing each other so as to form a gap between the end cups. The end cups each have a concave surface facing the gap which forces an electric field concentration in the vicinity of the end cups and in the gap between the opposing end cups. Such a field configuration is useful for energizing a lamp capsule placed within the gaps formed by the end cups. The end cups can be made of metal or metallized ceramic.

Abstract: An electrodeless low-pressure mercury vapor discharge lamp whose discharge vessel is provided with a core of magnetic material and a coil surrounding the core which coil connected to a high-frequency supply unit. An interference-suppressing, light transmissive electrically conductive layer is present on the outside of the discharge vessel, which layer can be connected to the supply mains through an electric conductor. The electric conductor comprises one or several capacitors connected in series to keep the conducting layer safe to touch during operation.

Abstract: A microwave powered lamp wherein microwave energy is coupled to a cavity in which an electrodeless bulb is disposed, such that a rotating field of constant ellipticity is established in the cavity.

Abstract: A low-loss L-C circuit arrangement for an electrodeless high intensity discharge (HID) lamp includes an excitation coil having at least one coil turn which is disposed in surrounding relation to the arc tube portion of the HID lamp and is configured in a low profile manner so as to minimize light blockage caused thereby. The L-C circuit arrangement includes a capacitor member having first and second capacitor plates which are electrically and mechanically connected to the excitation coil. The connection between the excitation coil and the capacitor member is made by a pair of connection members integrally formed with the coil turn and capacitor plates from a stock sheet of electrically and thermally conductive material.

Abstract: This invention relates means for illumination of sealed bulbs containing an predetermined inner gaseous environment to be excited to a spontaineous emission predominately by frequency modulated photon pumped into sealed bulb through a fiber-optic waveguide by a laser, said waveguide being clad where is extends from laser and is coupled to sealed bulb and unclad where it extends through sealed bulb, and further has an intragally formed reflective end section for provisions of feedback of frequency modulated photons through the waveguide core at the output end, thereby producing counter-travelling photons within the waveguide causing said photons to collide at a variety of incident angles as to cause photons to be emitted from the unclad waveguide within sealed bulb therefore stimulating the inner gaseous environment to a spontaineous emission which in turn stimulates a frequency modulated fluorescent photon interaction coating source which creates visible light.

Abstract: An arrangement including an electrodeless discharge lamp having a sealed envelope enclosing an ionizable medium capable of emitting radiant energy when subjected to a radio frequency field and a circuit for operating the lamp. The circuit includes an oscillator for generating an output signal at a given radio frequency, an RF amplifier responsive to the oscillator output signal, and an output tank circuit including an induction coil and a capacitor connected in parallel. The RF amplifier includes a pair of semiconductor switches operating in a Class E mode. The induction coil is positioned in close physical proximity to the medium in the envelope for coupling to the medium an electric field having a magnitude sufficient to initiate ionization of the medium and a magnetic field for maintaining the ionization. In a preferred embodiment, the amount of EMI/RFI noise generated in the circuit is reduced by symmetrically driving the induction coil.

Abstract: The irradiation device for gaseous or liquid substances has at least one high-power radiator with a discharge chamber (4) filled with filling gas. The filling gas contained therein emits radiation under the influence of quiet electrical discharges. The discharge chamber (4) immediately adjoins a treatment chamber (6) whose walls consist throughout of non-metallic material. An electrode pair (2, 7) and an ac source (12) connected to the two electrodes serve to feed the discharge, the coupling of the discharge chamber (4) to the electrodes being performed essentially capacitively. It is even possible, in particular, to treat by means of an irradiation device of such a design corrosive media or media for which extreme degrees of purity are the aim.

Abstract: An electrodeless HID lamp of the type having an excitation coil disposed about an arc tube for exciting a plasma arc discharge therein includes a light-transmissive outer envelope disposed about the arc tube and a light-reflective coating on the upper portion of the arc tube. Thus, light emitted by the arc discharge radiates in a forward direction through the lower portion of the arc tube. An elongated support for the arc tube is situated within the outer envelope and extends in the forward direction through the corresponding lower end of the outer envelope. According to one embodiment, the arc tube support is tubular and contains therein a discharge starting aid. The lamp further preferably includes a getter disposed within the outer envelope for removing gaseous impurities therefrom. A getter support is attached to the upper end of the lamp envelope in order to optimize the position of the getter therein, while avoiding oxidation of the getter material during the lamp sealing process.

Abstract: A series resonant starting circuit for providing a starting voltage to a starting probe for initiating an arc discharge in an electrodeless HID lamp includes an electrically variable inductance. The HID lamp is of a type having an excitation coil situated around an arc tube containing an ionizable fill in which the arc discharge is ignited. The electrically variable inductance includes a magnetic core having a main winding wound thereon that is coupled in series with a resonant capacitance. A bias winding is also wound on the magnetic core. Either the bias winding is coupled in series with a bias inductor, or, alternatively, the main and bias windings are configured on the magnetic core as a cross-field inductor. A bias circuit supply provides dc or relatively low-frequency ac current to the bias winding in order to vary the permeability of the magnetic core, and hence the inductance of the main winding, thereby tuning the starting circuit.

Abstract: A gas probe starter for an electrodeless HID lamp includes a getter for removing gaseous impurities from the fill contained in the starting chamber of the gas probe starter. In a preferred embodiment, a metal foil having active getter material disposed on the surfaces thereof in the form of a sintered powder is inserted at an optimum location in the starting chamber which depends on the optimum operating temperature of the particular getter material.

Abstract: An electrodeless high intensity discharge (HID) lamp system includes a ballast housing constructed from a thermally conductive material for containing a ballast of a type having at least one RF power switching device. The RF switching device is thermally coupled to the ballast housing to provide heat sinking therefor. The excitation coil of the HID lamp is also thermally coupled to said ballast housing via thermally-conductive coil mounting studs, but is electrically insulated therefrom. An opening in the ballast housing enables the electrical connection of the coil to the output circuit of the ballast. The RF power switching device and the excitation coil are arranged so as to be spaced apart sufficiently in order to maintain the ballast housing temperature substantially uniform during operation of said lamp, thereby maximizing lamp efficiency and increasing the useful life of the lamp and ballast.

Abstract: The fill of a self-extinguishing gas probe starter for an electrodeless high intensity discharge lamp includes a starter fill component which has a relatively low vapor pressure and is substantially inert in the starter fill at ambient temperatures, but which component vaporizes and becomes electronegative as the temperature of the lamp increases, so that the starter fill component attaches electrons of the starting discharge in the gas probe starter and thereby extinguishes the starting discharge after initiation of the arc discharge in the arc tube. As a result, the flow of currents between the gas probe starter and the arc tube, which would otherwise have a detrimental effect on the arc tube wall, is avoided.

Abstract: An electrodeless high intensity discharge (HID) lamp having an arc tube, a starting aid, and an outer jacket all integrally formed of fused quartz, includes an excitation circuit for providing RF energy effective for initiating and maintaining a gas discharge within the arc tube. The arc tube is positioned within the outer jacket such that a minimum space exists between the outer jacket and the arc tube thereby allowing the efficient coupling of such RF energy to the arc tube by means of an excitation coil wound in close proximate location to the arc tube. The starting aid is of a substantially smaller dimension than the arc tube thereby allowing for a second spacing to occur above the arc tube. This second spacing is effective for optimum thermal management of heat generated within the outer jacket. The upper end of the outer jacket has an integrally formed annular groove for receiving an annular support member effective for securing the HID lamp to a lighting fixture.

Abstract: The electrodeless low-pressure discharge lamp comprises a tube which is closed at one end, which surrounds a body of soft magnetic material with clearance, and which is enclosed with clearance in the cavity in the outer bulb, which cavity enters the cavity in the discharge vessel. The tube provides a good insulation of the body from the heat of the discharge in the discharge vessel.

Abstract: The invention relates to a device for the generation of a plasma by means of circularly polarized high frequency waves. These high frequency waves are generated by means of voltages having a phase rotation of 90.degree..

Abstract: A method and apparatus which prevent mercury and fill gas loss in capacitively coupled electrodeless lamps operated at low frequencies (below 100 MHz). The lamp includes a lamp envelope with an inner coating of phosphor. Outer electrodes coupled to a radio frequency source are positioned around the outer surface of the lamp envelope. The lamp contains a fill gas (e.g. mercury and argon) which forms a plasma causing UV radiation which excites the phosphor. Mercury loss is prevented by providing a pair of inner conductors aligned with the outer conductors but electrically insulated therefrom. The inner conductors prevent the mercury and fill gas ions from embedding themselves in the lamp envelope.

Abstract: A microwave discharge light source device in which one side of a discharge space in which a plasma emission takes place is defined by a transparent dielectric member. A transparent microwave reflecting member is disposed in a position such as to face the discharge space through the dielectric member. A microwave having an electric field component in the direction of thickness of the dielectric member is introduced into the dielectric member through the coupling at an end surface of the dielectric member so that a microwave electric field is formed in the discharge space, and so that the plasma emission medium emits light by electric discharge. The light thus emitted is extracted through the transparent microwave reflecting member.

Abstract: The present invention describes an electrodeless HID lamp fixture which utilizes conventional microwave printed circuit material to provide both coupling and impedance matching functions. The fixture provides a steady state input impedance of a predetermined (e.g. 50 .OMEGA. or 75 .OMEGA.) value allowing direct connection to a RF power supply. Microwave power is applied at the input of the impedance matching network/balun which transforms the steady-state impedance of the lamp to the predetermined value. The network include a quarter wave transformer having a shunt capacitor coupled to balun-applicator which supplies microwave power to the lamp. In a preferred embodiment, the quarter wave transformer, shunt capacitor and balun are all manufactured on a microstrip.

Abstract: A circuit arrangement comprising a DC/AC converter for supplying power to a lamp upon receiving energy from a DC voltage source; the converter includes a branch A having at least one switching element and a control branch connected to the switching element; the control branch comprises a coil shunted by a capacitor; the circuit arrangement also includes a load branch with an inductor connected to a parallel arrangement of an inductance and capacitance.

Abstract: This electrodeless high intensity discharge lamp comprises a light-transmissive arc tube having spaced wall portions of dielectric material and a first gaseous fill within the arc tube. An excitation coil about the arc tube is energizable with RF current effective to develop a toroidal arc discharge in the first gaseous fill upon a dielectric breakdown of the fill. A starting container is joined to the arc tube and has an end wall constituted by one of arc-tube wall portions. A second gaseous fill within the starting container has a dielectric strength lower than that of the first gaseous fill. For initiating toroidal arc discharge, we provide an arrangement for producing a dielectric breakdown of the gaseous fill within the starting container that develops into an electric discharge that changes the potential at end wall in such a manner as to cause a dielectric breakdown of first gaseous fill.

Abstract: A silicon flake comprising silicon in a sufficient quantity is inserted into the arc tube of a high-intensity, metal halide discharge lamp in order to avoid a substantial buildup of free halogen, thereby extending the useful life of the lamp.

Abstract: The irradiation device for drying and/or curing paints, varnishes and similar coatings (13, 14) has at least one UV high-power radiator having a discharge space (3) filled with filling gas. The filling gas contained therein emits radiation under the effect of silent electrical discharges. The discharge space (3) is bounded by walls (1, 2), at least one wall consisting of dielectric material and being transmissive to the radiation generated in the discharge space (3). A pair of electrodes (4, 5), with an AC source (10) connected to the two electrodes, serves for feeding the discharge. The treatment space (6) is immediately adjacent to the dielectric (1, 2). The electrodes (4, 5) are positioned at a distance from the immediately neighboring dielectric. The coupling of the electrical energy from the electrodes into the discharge space takes place essentially capacitively.

Abstract: A feedback system for a high intensity discharge lamp detects arc instabilities and stabilizes the discharge, thereby increasing the useful life of the lamp. The feedback system includes a phase detector circuit for detecting relatively low fequency, recurrent variations in the characteristic of the arc discharge, indicating the onset of an arc instability. As a result, a signal is generated to decrease the power supplied to the lamp by an amount sufficient to stabilize the discharge without a significant decrease in visible light output.

Abstract: A high frequency applicator for energizing electrodeless lamps is described. The applicators are made of two loops of wire electrically attached to the ends of phased feed points of a planar transmission line. The loops are face each other and are positioned so as to form a gap in which a lamp capsule is placed. Each loop is made of three partial turns, the first and second turns being parallel to each other, each partial turn having a first and second end and the third partial turn is attached to the second end of each partial turn and positioned orthogonal the first and second turns. The plane formed by the third turn makes a dihedral angle between 9.degree. and 135.degree. with the planar transmission line.

Abstract: A passive starting circuit foran electrodeless HID lamp includes a series resonant LC circuit including an inductor of variable impedance coupled in series with the parasitic capacitance between a starting probe and the excitation coil of the lamp, and further including a coupling capacitance for directly coupling the starting circuit to the excitation coil. The coupling capacitance is connected between the high terminal of the excitation coil, or a point in the circuit at approximately the same potential thereof, and a conductive support for holding the lamp and starting probe in a lamp fixture. In this way, the starting voltage is maximized for more efficient and rapid starting. Preferably, the series resonant capacitance of the starting circuit is optimized so that the ballast requires little, if any, retuning after the lamp has started.

Abstract: A dual feedback control system for a Class-D power circuit maximizes efficiency by controlling the magnitude and phase angle of the resonant load circuit using two separate feedback loops. The first feedback loop changes the value of a first variable capacitor in response to difference in magnitude between the actual load impedance and the desired load impedance. The second feedback loop changes the value of a second variable capacitor in response to the phase difference between the actual phase angle and the desired phase angle. In this way, the real and imaginary components of the load impedance are controlled so that the Class-D circuit is in tune, and hence efficiency is maximized, over a wide range of load impedances. The dual feedback control of the present invention may be advantageously employed in the ballast of an electrodeless HID lamp system.

Abstract: Wireless Christmas tree lights (1) illuminated by means of Electro-Magnetic Energy eminating from a self contained antenna. Multiple wireless lamps may be placed anywhere on the tree without being constrained by wire length. The Electro-Magnetic Energy is produced from an RF power unit (5) decorated like a gift box that may be placed under the tree or in a remote location several feet away. The various illumination effects are selected via a magnetic wand (8) that activates switches and selector circuits, and a non-linear modulator internal to the RF generator.

Abstract: An electrodeless lamp may be formed with a capsule having a radiant energy transmissive material defining an approximately cylindrical enclosed volume having an external length less than 20.0 millimeters, and an outer diameter less than 8.0 millimeters. The enclosed volume is filled with a lamp fill excitable by a high frequency electromagnetic field to produce radiant energy. The small size capsule produces a particularly efficient, orientation tolerant arc discharge. The arc is then highly stable as to position, yielding a good optical source to design for. The temperature gradient is small, thereby yielding little thermal stress on the capsule. An electrodeless HID headlamp system may be formed with the efficient capsule from a radio frequency source operating from the power supply of a typical automobile. The headlamp system includes a high frequency power source, a transmission line, a coupler, an excitable lamp fill captured in a lamp capsule, a reflector and a lens.

Abstract: An electrodeless high pressure discharge lamp contains a halide or oxyhalide of W, Ta, Re, or rhenium oxide in such a quantity that a supersaturated metal vapor arises in the discharge, by which metal particles are formed. Owing to their high temperature these particles generate thermal emission. The lamp has a high color temperature and a high color rendering index.

Abstract: An electrodeless discharge tube containing an ionizable fill, the tube having a first portion for insertion in a launcher and a further portion separated from the first portion by a partition wall. Hence a discharge can be excited in the further portion because a surface wave can propagate through the wall separating the first and further portions.

Abstract: A passive, resonant starting circuit for an electrodeless HID lamp includes a starting coil that is shielded from stray capacitances that would otherwise result in detuning the resonant circuit and hence decreasing efficiency. The starting circuit further includes a capacitance coupled in series with the starting coil and another capacitance coupled in parallel with the coil. In a preferred embodiment, the starting coil is enclosed in a conductive cylindrical housing which functions as both a shield from external capacitances and the resonant capacitance in parallel with the starting coil. The housing has a lengthwise gap in order to prevent the housing from acting as a short circuit secondary with respect to the starting coil. A conductive disk is mounted to the ground end of the housing to increase shielding even further. The parallel resonant capacitance is determined by the length of the housing and the distance between the coil and the housing.

Abstract: A starting circuit for an electrodeless HID lamp, comprising a series resonant LC circuit of variable impedance, provides a starting voltage to a fixed or movable starting probe substantially simultaneously with the application of power to the excitation coil from the main power source. In a preferred embodiment, the starting circuit provides a starting signal to a gas probe starter of the type including a fixed starting electrode coupled to a starting chamber which contains a relatively low-pressure gas and is attached to the outer wall of the arc tube. Resonant operation of the starting circuit results in the application of a sufficiently high voltage to ignite a glow discharge in the low-pressure starting chamber. In turn, the starting voltage is capacitively coupled to the arc tube, ionizing the fill and initiating an arc discharge therein.

Abstract: A gas probe starter for an electrodeless high intensity discharge (HID) lamp includes a fixed starting electrode for coupling a starting voltage to a chamber which is attached to the outer wall of the arc tube and contains a gas. The gas in the starting chamber, which is preferably at a low pressure relative to that of the arc tube fill, is switched between conducting and nonconducting states corresponding to lamp-starting and normal running operation, respectively. To start the lamp, the starting voltage is applied to the starting electrode, causing a discharge current to flow in the gas chamber which, in turn, results in the capacitive coupling of a sufficiently high voltage to the arc tube in order to initiate an arc discharge therein. After the arc discharge is initiated, the starting voltage is substantially reduced so that the discharge current in the starting chamber is extinguished.

Abstract: An amusement device comprising a gas-filled plasma discharge tube; an electrode adjacent an end of the tube for coupling high-frequency, high-voltage energy into the gas in the plasma discharge tube; an ionization energy supply operably connectable to a source of electrcity for producing an adjustable high-frequency, high-voltage energy at an output thereof having an upper limit sufficient to ionize the gas in the plasma discharge tube without a ground return by utilizing the electrical capacity of the surroundings to provide a reactive impedance for plasma tube current to flow into, the electrode being operable connected to the output; and, a control circuit operably connected to the ionization energy supply for adjusting the level of the high-frequency, high-voltage energy at the output between levels causing ionization of the gas in the plasma discharge tube to occur in differing amounts as a function of a changing stimulus connected to an input thereof.

Abstract: An electrodeless discharge tube containing a fill which comprises a metal carbonyl complex. Such a complex will be sufficiently volatile to produce a vapor pressure in a discharge tube in which a discharge can be generated. The discharge so generated emits a mixture of visible and infra-red radiation.

Abstract: A starting aid for an electrodeless high intensity discharge (HID) lamp comprises at least one starting electrode which, at least during lamp starting, is situated adjacent to, and preferably in contact with, the portion of the arc tube nearest the arc discharge and oriented so as to provide a capacitive starting current that flows in substantially the same location as the arc discharge, thereby easing the transition from a relatively low current glow discharge to a relatively high current, high intensity discharge. The starting aid comprises one or more conductors that substantially conform to the shape of the arc tube at least during initiation of the arc discharge. After the lamp is started, the starting aid may be moved to a predetermined location away from the arc tube. Alternatively, the starting aid may comprise one or more fixed starting electrodes.

Abstract: A variable capacitor comprises two conductive plates with a liquid crystal material having an anisotropic dielectric constant disposed therebetween. The conductive plates are treated with a surfactant to align the liquid crystal molecules in a predetermined direction at the interfaces between the conductive plates and the liquid crystal material. A low-frequency control voltage above a threshold voltage is applied across the conductive plates to orient the molecules of the liquid crystal material so that the molecular axis with the highest dielectric constant aligns parallel to the applied voltage. Upon removal of the control voltage, the liquid crystal molecules resume their original orientation. In this way, the dielectric constant of the variable capacitor is varied between two predetermined values, thus varying the capacitance of the variable capacitor between two discrete values proportional thereto. An alternative control provides continuous control over a range of capacitance values.

Abstract: A variable capacitor includes a fixed conductive plate and a movable conductive plate with a dielectric disposed between them. A piezoelectric actuator is used to vary the distance between the conductive plates by moving the movable plate with respect to the fixed plate, with capacitance changing in inverse proportion to distance moved. In an electrodeless high intensity discharge lamp ballast, such a variable capacitor is situated in series with the excitation coil of the lamp. When a control voltage is applied to the piezoelectric actuator, the movable plate is moved from a starting position to a running position so as to maintain the ballast load in tune under both starting and running conditions, respectively, resulting in higher efficiency operation.

Abstract: A discharge tube arrangement comprises an excitation device and a discharge tube made of a light-transmissive dielectric material and containing a fill. The excitation device is suitable, when energized with radio frequency (r.f.) power, for exciting surface waves in the discharge tube. The excitation device includes a launcher and a plurality of electrical components associated with the supply of r.f. power to the launcher and constituting at least one of an impedance matching network and a part at least of means to generate r.f. power. This plurality of electrical components is positioned in the launcher between its inner and outer tubes.

Abstract: An electrodeless lamp may be formed with a capsule having a radiant energy transmissive material defining an approximately cylindrical enclosed volume having an external length less than 20.0 millimeters, and an outer diameter less than 8.0 millimeters. The enclosed volume is filled with a lamp fill excitable by a high frequency electromagnetic field to produce radiant energy. The small size capsule produces a particularly efficient, orientation tolerant arc discharge. The arc is then highly stable as to position, yielding a good optical source to design for. The temperature gradient is small, thereby yielding little thermal stress on the capsule. An electrodeless HID headlamp system may be formed with the efficient capsule from a radio frequency source operating from a the power supply of a typical automobile. The headlamp system includes a high frequency power source, a transmission line, a coupler, an excitable lamp fill captured in a lamp capsule, a reflector and a lens.

Abstract: A discharge tube arrangement includes a discharge tube containing a fill and means for generating a discharge in the fill from a source of radio frequency (r.f.) power. An electrically conductive structure surrounds the discharge tube. The electrically conductive structure is formed of a plurality of waveguides which extend outwardly from the discharge tube. One or more waveguides has a cross-sectional area that increases with separation from the discharge tube. Each waveguide is dimensioned to support the propagation of electromagnetic radiation above a cut-off frequency.

Abstract: A discharge tube arrangement for use as a light source includes a discharge tube made of a light-transmissive dielectric material and containing a fill. An excitation device for exciting surface waves in the discharge tube comprises an r.f. power generator and a launcher. The launcher is formed as an inner tube, an outer tube coaxial with the inner tube and first and second end walls, at least one of the first and second end walls having an aperture for receiving the discharge tube. A launcher gap extends axially from a first end of the inner tube and there is also a further gap. The outer tube and the first and second end walls form an unbroken electrically conductive path to provide an r.f. screening structure around the inner tube.

Abstract: A closed-loop control system for a Class-D power amplifier circuit, having a variable output resonant circuit impedance, maintains high-efficiency operation by using the phase angle between the resonant load voltage and current to control tuning of the resonant circuit. The resonant load circuit voltage and current are supplied to a phase detector for detecting the phase angle therebetween and for generating a voltage proportional thereto. The output voltage from the phase detector is compared to a reference voltage by an error amplifier. The resulting error voltage is employed as the input signal to control circuitry for tuning the output resonant circuit. Such a control system is suitable for maintaining high-efficiency operation of an electrodeless high intensity discharge lamp system.

Abstract: A starting circuit for an electrodeless high intensity discharge lamp comprises a high efficiency power supply for providing a radio frequency signal to a starting probe disposed proximate the arc tube of the lamp. The power supply may comprise either a Class-D or Class-E power amplifier having an output resonant circuit tuned to a substantially higher frequency than the operating frequency of the signal provided to the excitation coil by the lamp ballast to ensure minimal interaction between the starting circuit and the ballast. The output resonant circuit includes an inductance coupled in series with a capacitance that preferably comprises the capacitance between the excitation coil and the starting probe. After initiating the arc discharge, the starting circuit is deactivated.

Abstract: A protective coating of suitable composition and thickness is applied to the inner surface of the arc tube of a high-intensity, metal halide discharge lamp in order to avoid a substantial loss of the metallic component of the metal halide fill and hence a substantial buildup of free halogen, thereby extending the useful life of the lamp. A preferred lamp structure includes a fused silica arc tube with a silicon coating. The silicon coating is preferably applied to the arc tube using a chemical vapor deposition process.