Abstract: A discharge vessel for an electrodeless lamp having a pair of substantially parallel front and back walls. In one implementation, the front wall of the discharge vessel has a collimating structure, e.g a fresnel lens, for directing the light in a preferential direction such as in a flood light. In another implementation, the flat discharge vessel is quadrilateral and together with one or more quadrilateral excitation coils can be used as a backlight for a flat panel display. In yet another implementation, a cup-shaped discharge vessel with a collimating structure on the front wall is used in an electrodeless lamp for a task lighting such as a spot light.

Abstract: An electrodeless fluorescent lamp and fixture is disclosed which operates at radio frequencies and contains a bifilar coil to reduce RF voltage between the plasma and the coil and a metallic cylinder (10) to remove heat from a said bifilar coil. The bifilar coil consists of two windings. The primary (induction) winding (6) is used to generate RF electrical azimuthal field in the bulb volume needed to maintain the inductively-coupled RF plasma. The second (bifilar) winding (18) has essentially the same number of turns and is wound on the inductive winding (6), but in the direction opposite to that of the primary (inductive) winding. The RF current flowing in the inductive winding (6) induces an RF voltage of the opposite polarity in the bifilar winding (18), so two adjacent turns of both windings have equal (or nearly equal) but of opposite sign RF potentials with respect to the plasma.

Abstract: An electrodeless inductively-coupled fluorescent lamp which operates at ro frequency comprising a bulbous envelope (1) filled with rare gas and metal vapor. A reentrant cavity (4) and an induction coil (6) are disposed in the cavity (4). The inner walls of the envelope (1) and the cavity (4) have a protective coating (3) and a phosphor coating (2). A metal Faraday cylinder (12) welded to the lamp base (13) is disposed between the cavity (4) and the coil (6) to reduce capacitive RF voltage between the coil and the plasma to improve lamp maintenance and remove heat. A tubulation (16) is disposed on the lamp axis to evacuate the envelope (1). The proximal end of the tubulation (16) has an expansion (20) with the volume (23) where the initial capacitive discharge is ignited.

Abstract: An apparatus and method for operating an arc discharge lamp which can be hot restarted is described. The method involves providing low microwave power after the lamp ballast is disconnected from the lamp. The microwave power is modulated such that conductivity is maintained within the lamp as the lamp cools. Restarting the lamp is accomplished by reconnecting the ballast at any time. In one embodiment, the apparatus of the invention includes an arc discharge lamp and ballast coupled together with a switch to turn the lamp on and off. A microwave power supply is connected in parallel with the ballast and is coupled to the lamp when the ballast is shut off. The invention allows for hot restart of the arc lamp without requiring a high voltage pulse.

Abstract: An electrodeless, low pressure gas discharge lamp includes a vitreous envelope containing a discharge medium and being shaped with an external chamber for receiving an electrical excitation circuit. The excitation circuit is effective for exciting the discharge medium to emit light with electromagnetic fields that are generated by the excitation circuit. A circuit is included for supplying electrical power from power mains to the excitation circuit. A transparent, electrically conductive coating is provided atop the vitreous envelope and is electrically connected substantially directly to one of the power mains at any given time. A transparent, electrically insulative coating is disposed atop the electrically conductive coating, and comprises a contiguous, inorganic glass layer. The insulative coating preferably has a minimum coating thickness of at least about 3.1 microns.

Abstract: An electrodeless fluorescent lamp containing a fill of a rare gas and mercury and a flag (14) disposed therein at a predetermined location in the lamp for increasing the rate of luminous development in the lamp. The flag (14) includes a pair of spaced-apart metallic foil sections (31) and a metallic mesh substrate (30) disposed between the foil sections (31) whereby to be shielded from ion bombardment of the discharge. A coating (30a) of indium which is adapted to amalgamate with the mercury is disposed on the mesh (30). The sections are joined together by spot-welding (32) to enable migration of mercury into and out of the space between the sections thereby enable the atoms to form an amalgam with the indium and be rapidly released therefrom.

Abstract: Improved material and method for reflecting light in a photoinduction chamber is provided. The material comprises one or more layers of expanded polytetrafluoroethylene (ePTFE) membrane. Employing an ePTFE membrane as a reflective surfaces is demonstrated as providing excellent diffuse reflective properties, especially in the ultraviolet and visible ranges of light. Additionally, the material of the present invention has many other properties that make it particularly desirable for use in various photoinduction chamber applications, including inertness, flexibility, ease in shaping and installation, etc.

Abstract: An excimer lamp utilizing a high pressure fill. The fill includes a halogen at an operating pressure of greater than about 350 torr or the combination of a halogen and a rare gas at a total operating pressure of greater than about 2.5 atmospheres.

Abstract: Ignition of an electrodeless lamp, energized by microwave or radio frequency energy, is achieved by disposing an additive material in the lamp envelope along with the primary fill material. In a first embodiment, the additive is at least partially electrically conductive at room temperatures but non-conductive or a vapor at lamp operating temperatures. The preferred additives for this embodiment are mercury sulfide and mercury selenide. In a second embodiment, the additive is a material, such as piezoelectric crystals, that produces sparks in the envelope when the crystals collide with each other, or with other materials, in response to agitation of the envelope. The additive may alternatively build up electrostatic charge by rubbing along the interior surface of the lamp envelope when the envelope is agitated, the charge build up being sufficient to ignite the primary fill material.

Abstract: A lamp-to-light guide coupling arrangement includes an electrodeless high intensity discharge lamp comprising an arc tube with an ionizable fill, and an excitation circuit for electrically exciting the ionizable fill to induce therein a light-producing arc discharge. The coupling arrangement further includes a coupling device comprising a generally tubular, hollow body that has an inlet end for receiving light from the arc discharge and a larger, outlet end. The coupling device further comprises an interiorly directed reflector on a surface of the hollow body for reflecting visible light. Such coupling device is shaped so as to receive light at one solid angle over an area of the inlet end and to transmit light at a smaller solid angle but over a larger area of the outlet end. The coupling device is preferably formed from dielectric material. The reflector preferably comprises a refractory optical interference filter.

Abstract: Ignition of an electrodeless lamp, energized by microwave or radio energy, is achieved by disposing an additive material in the lamp envelope along with the primary fill material. In a first embodiment, the additive is at least partially electrically conductive at room temperatures but non-conductive or a vapor at lamp operating temperatures. The preferred additives for this embodiment are mercury sulfide and mercury selenide. In a second embodiment, the additive is a material, such as piezoelectric crystals, that produces sparks in the envelope when the crystals collide with each other, or with other materials, in response to agitation of the envelope. The additive may alternatively build up electrostatic charge by rubbing along the interior surface of the lamp envelope when the envelope is agitated, the charge build up being sufficient to ignite the primary fill material.

Abstract: An electrodeless neon discharge light source having a red color light output is provided for use in automotive applications. The light source has a lamp envelope containing a fill of neon gas which, when excited to a discharge state by introduction of an operating signal over a tuned circuit consisting of a resonant capacitor and a ferrite coil, produces a red color light output. A flash control input to a ballast circuit arrangement provides the ability to control the light output using bursts of high frequency sinusoidal energy. The use of the burst signal approach allows for providing varying levels of light intensity output thereby signifying the distinction between braking conditions and an on condition of the tail light. Furthermore, by controlling the rate of flashing of the light source, an indication of a hard braking or emergency condition, could be conveyed.

Abstract: An illumination unit according to the invention comprises an electrodeless low-pressure discharge lamp 10. The illumination unit is provided with a lamp vessel 20 which encloses a discharge space 21 which contains an ionizable filling. The illumination unit is in addition provided with a holder 60 for the lamp vessel 20, with a coil 30 for generating a high-frequency magnetic field so as to maintain an electric discharge in the discharge space 21, and with a high-frequency supply 50 for the coil. The illumination unit is further provided with ignition aids 40 for promoting the initiation of the discharge.

Abstract: An electrodeless high intensity discharge lamp has a light transmissive ceramic arc tube for containing a discharge sustaining medium and a hollow tube member. An excitation coil for causing an arc discharge is situated about the arc tube. The ceramic arc tube includes a first portion for developing the arc discharge therein and a second portion protruding outwardly from the first portion. The hollow tube member is so disposed in the second portion that a space is provided between the inner wall surface of the second portion and the outer wall surface of the hollow tube member. The space is in communication with the interior of the first portion for allowing the medium to be condensed and retained during the lamp operation.

Abstract: A lighting unit according to the invention comprises an electrodeless low-pressure discharge lamp 20 provided with a discharge vessel 20 enclosing a discharge space 20 with an ionizable filling in a gastight manner. The discharge vessel 20 has a recessed portion 23 and an enveloping portion 23 which transmits radiation generated in the discharge vessel. Means are present in the recessed portion for initiating and maintaining an electric discharge in the discharge space. The means comprise a member for generating an electric field in the discharge space. The recessed portion is provided with a luminescent layer, which is subdivided into mutually separated regions, at a surface facing the discharge space. The lighting unit further comprises a supply unit for supplying the means. The lamp of the lighting unit according to the invention has a comparatively low ignition voltage.

Abstract: An illumination unit comprises an electrodeless low-pressure discharge-lamp and a high-frequency power supply unit. The lamp has a gastight closed discharge vessel with an ionizable fill and a coil with turns of a primary and a secondary winding around a core of soft-magnetic material. The power supply unit has input terminals, a first output terminal, electrically neutral with respect to ground, that is connected to a first end of the primary winding, and a further output terminal that is connected to a second end of the primary winding. During nominal lamp operation the primary winding excites a high-frequency magnetic field that maintains an electrical discharge in the discharge vessel and that induces in the secondary winding a potential drop in the direction of a first, with respect to the electrically neutral end, to a second free end that varies in a sense opposite to the potential drop from the first to the second end in the first winding.

Abstract: An electrodeless fluorescent lamp and fixture is disclosed which operates radio frequencies and contains a metallic cylinder 9 to suppress capacitive coupling between an induction coil 7 and a plasma in the envelope 1 of the lamp and simultaneously substantially reduce heat in a reentrant cavity 5. The lamp includes a bulbous envelope 1 having a conventional phosphor layer 3 disposed therein. The bulbous envelope 1 contains a suitable ionizable gaseous fill. Upon ionization of the gaseous fill, the phosphor is stimulated to emit visible radiation upon absorption of ultraviolet radiation. The reentrant cavity 5 of the bulbous envelope 1 contains an inducation coil. The cylinder 9 transfers heat from the plasma to the fixture 11 through a base 13, 13a on the envelope 1.

Abstract: A luminaire includes a lamp connected at one electrode to an ordinary current loop and at the other electrode to the other current loop which is branched into more than two which are extending along two opposite sides of the lamp. Magnetic fields produced thus in the branched loops act to cancel each other, and any noise occurring due to generation of the magnetic field can be remarkably reduced.

Abstract: A lamp for providing visible light which utilizes a fill containing selenium and/or sulfur, or compounds of these substances. The lamp is excited such that the excited fill emits radiation from elemental selenium and/or elemental sulfur which is in a continuous band principally within the visible range.

Abstract: An electrically controllable variable capacitor includes the interelectrode capacitance of at least one power MOSFET, a capacitance connected in series with the MOSFET and having one terminal connected to the drain or source thereof (the series capacitance), and bias control circuitry for controlling the bias voltage applied to the MOSFET. The voltage rating of the MOSFET, the peak amplitude of the applied ac signal, and the value of the series capacitance determine the range of dc bias voltages over which the MOSFET can be operated, and hence the capacitance range of the variable capacitor. Such a variable capacitance is useful as a tuning capacitor in an electrodeless HID lamp ballast.

Abstract: An amalgam system for optimizing the mercury vapor pressure of an electrodeless discharge fluorescent lamp is disclosed. A coil network induces an electric discharge in a gas mixture contained in a sealed lamp vessel. An amalgam is supported in the discharge and thermally isolated from the lamp vessel by a thin glass strand. The discharge transfers power directly to the amalgam, thus quickly heating the amalgam. Rapid heating of the amalgam provides a rapid increase in mercury vapor pressure in the lamp so that the light output rises quickly when the lamp is energized. An impedance matching and filter network is constructed such that, in combination with the coil/plasma load, it provides a desired steady-state impedance and a desired start-up impedance.

Abstract: A fluorescent lamp for use in special applications includes an electrodeless envelope of glass or other light transmissive material carrying fluorescent material within the envelope. An RF energy source and coupler are embedded in epoxy as an integral power unit, thereby isolating the power unit from the hazardous environment. The power unit and the envelope are shaped in complementary form such that the coupler and envelope are in energy-transfer relation to excite the lamp, but the envelope may be removed from the power unit to re-lamp the fixture.

Abstract: Apparatus for efficiently exciting an electrodeless lamp to produce visible light. A source of microwave energy is coupled to a cylindrical cavity which encloses an electrodeless lamp. The cylindrical cavity includes a sidewall and end wall which is made from a metallic mesh which passes light produced from the electrodeless lamp. The electric field intensity within the cylindrical cavity is increased in the region above the lamp center. The increased electric field intensity produces a more uniform temperature across the bulb service, increasing the rate of plasma heating of gas molecules in the lamp.

Abstract: A fluorescent lamp (2) having at least two phosphor coatings (12) on the surface of the sealed lamp bulb, typically an inner surface. There is variable driving means which preferentially activates one phosphor and not the other phosphors, at one arrangement or setting or configuration of the driving means, while at another setting the driving means activates in addition a different or several different phosphors. Each phosphors may be a blend of phosphors and the phosphors and/or blends may be overcoated upon one another forming multiple layers or all mixed together and applied as a one layer coating on the lamp surface.

Abstract: Electrodeless arc tubes for high pressure sodium discharge lamps comprise a substantially tubular, translucent body formed from a material comprising sintered polycrystalline alumina. The body has an inside diameter and an outside diameter and a given length. A fill comprising sodium and xenon are loaded within the body. At least one end-seal is provided for the body, the end-seal comprising a first alumina disc sealed within the inside diameter by compression, the first disc being spaced inwardly from an end of the body and having a substantially centrally located aperture therein. A second alumina disc seals the aperture, the second disc being bonded to the first disc and to the inner wall of the body by a sealing frit.

Abstract: In some embodiments, a light bulb for an electrodeless discharge lamp has a protuberance such that the cold spot of the bulb is located in the protuberance. The protuberance is spaced from the induction coil of the lamp so as to be easily accessible. Hence the cold spot temperature is easy to measure and control. In some embodiments, heat sinks are provided to cool the light bulb. An active control element including a Peltier element is provided to control the cold spot temperature.

Abstract: An electrodeless low-pressure discharge lamp includes a translucent discharge-vessel of a glass that contains at least 5 weight % sodium, encloses a discharge-space and includes a mercury containing fill. The lamp further includes a device to maintain an electrical discharge in the discharge space and an auxiliary radiation source that emits at least 0.5 mW of visible radiation when activated, to provide a relatively short ignition time.

Abstract: An arrangement for adjusting the intensity of an electrodeless discharge lamp is described. In one embodiment the high-frequency signal delivered to the induction coil is interrupted during a predetermined portion of a full duty cycle. This function is provided by a dimmer control unit which may be in an analog or digital form and may respond to a control signal provided by a potentiometer, a three-way lighting fixture or an addressable, remote controlled interface with data transmitted over the power lines or over a radio or infrared communication channel. In another embodiment the dimmer control unit alters the amplitude of the high-frequency signal supplied to the lamp's induction coil.

Abstract: An electrodeless high intensity discharge lamp includes an electrodeless lamp capsule, first and second electric field applicators positioned so that the lamp capsule is between the electric field applicators, and a planar transmission line. The planar transmission line couples high frequency power from an input to the first and second electric field applicators and has a gap with in which the lamp capsule is positioned. A field symmetrizing conductor, preferably a thin wire, is located in an open side of the gap and is electrically connected to the ground plane of the planar transmission line. The field symmetrizing conductor is positioned such that the electric field in the lamp capsule is substantially symmetrical with respect to the lamp axis and is substantially colinear with the lamp axis.

Abstract: A hydrogen discharge lamp has a glass lamp enclosure formed with a radiation-emitting window and receiving a body of a zirconium-cobalt alloy forming in part a hydride which constitutes a reservoir for hydrogen or deuterium and enabling controlled liberation of the hydrogen or deuterium from the reservoir. The zirconium-cobalt alloy simultaneously forms a getter for elements interfering with spectral purity of a hydrogen discharge emission from the lamp. An electrical discharge is effected in the hydrogen or deuterium liberated in the enclosure to cause the emission of light through the window.

Abstract: An impedance matching and filter network is disclosed. The network performs two preselected impedance transformations and provides a filtering function to attenuate harmonics of an electrical signal delivered at an input of the network. The network may advantageously be structured in the form of balanced dual filters which are referenced to a virtual ground between them, the virtual ground being connected to a shield which surrounds the electric components. The network is particularly suitable for use with electrodeless discharge lamps to provide an impedance matching function for the induction coil and to limit RFI.

Abstract: A simple and effective technique for reducing an external magnet flux emitted from a driven inductor surrounded by an ionizable gaseous medium. This technique includes surrounding the inductor with at least one shielding conductive loop, terminating the shielding loop in a capacitive termination to resonate, and maintaining a resonant frequency of the capacitive termination in series with an inductance of the shielding loop below the predetermined driving frequency of the inductor.

Abstract: A material such as a gas at an initial pressure below atmospheric is treated with RF energy at a frequency greater than 1 MHz to transition to a glow discharge state and then at increased pressure to a new state at which the average internal temperature is at least an order of magnitude higher than in the glow discharge state but the rate or radiating heat is at least an order of magnitude lower than in the glow discharge state. The new state can be maintained for a period of the order of at least tens of seconds and energy can be extracted through contacting the gas in the new state with a heat conducting body. In variations, the gas pressure need not be below atmospheric, materials in liquid and solid phases can be used in place of the gas, and energizers other than RF energy can be used, such as high-voltage discharges and high-energy particle beams.

Abstract: A push-pull Class E amplifier is used to provide an efficient transfer of power to the induction coil in an electrodeless discharge lamp and to reduce the amount of radio frequency interference emitted by the lamp into the surrounding environment. A bifilar or other type of multifilar induction coil, preferably center-tapped, is used to further reduce the radio frequency interference problem.

Abstract: Apparatus for exciting electrodeless lamps. A magnetron for generating electromagnetic energy in the microwave region includes an extension for its antenna terminal. The extension extends the length of the antenna to control the phase of loading on the magnetron. A circular ground flange and perforated screen enclose the electrodeless lamp, permitting microwave energy to excite the gas within the lamp, while confining the energy to the space bounded by the perforated screen and cylindrical ground flange. The extension for the antenna has a length which maintains the reflection coefficient phase to a level which does not adversely disturb the magnetron operating frequency.

Abstract: An electrodeless discharge lamp includes a discharge gas sealed in a lamp tube. The discharge gas includes a halide of rare earth metal. An auxiliary electrode is disposed on or adjacent to an outer periphery wall of the lamp tube such that the auxiliary electrode is capacitively coupled to an interior space of the lamp tube. A main induction coil is wound around the lamp tube and receives power from a first high frequency power source. The auxiliary electrode receives power from a second high frequency power source. In operation, the electrodeless discharge lamp attains smooth lighting upon starting or restarting.

Abstract: The present invention provides a method for using electrodeless high-intensity discharge (HID) lamps for automotive headlamp and similar applications requiring high/low beam operation (first and second beam orientation) of signaling. The HID lamp is excited with a high-frequency radio frequency (rf) signal. Modulation of the radio frequency signal is used to cause the arc of the HID lamp to selectively operate at an acoustic resonance point. At such a point, the arc undergoes a perturbation and is physically displaced from its quiescent position. When the lamp is placed at a focal or light-gathering point of an optical system having forward gain, displacement of the arc away from the focal point causes discernible changes in the far-field output of the optical system.

Abstract: An excimer lamp utilizing a high pressure fill. The fill includes a halogen at an operating pressure of greater than about 350 torr or the combination of a halogen and a rare gas at a total operating pressure of greater than about 2.5 atmospheres.

Abstract: A glass rod extending through and sealed to the exhaust tube of an electrodeless SEF fluorescent discharge lamp has a metal support member at one end thereof for supporting an amalgam at or near the apex of the lamp envelope. The metal support member may comprise a spiral-shaped wire, a wire screen, or a wire basket. Preferably, the amalgam is maintained in contact with the apex of the lamp envelope. If desired, the metal support member may comprise a magnetic material to allow for magnetic transport of the amalgam assembly during lamp processing. The metal support member restricts spreading of the amalgam when in a liquid state; and the glass rod provides rigid support for the amalgam independent of lamp orientation.

Abstract: Electrodeless, low pressure, fluorescent discharge lamp of high aspect ratio, with a substantially flat spiral rf coil adjacent a back face (and insulated therefrom), that emits light through a front surface or selected portions under control of internal reflective and phosphor coatings placement to afford minimum resonance trapping, high efficiency and uniform illumination of high specific intensity over a selected area of the front wall.

Abstract: An electrodeless high intensity discharge lamp includes a lamp capsule containing a fill material for emitting radiation upon excitation by high frequency electromagnetic energy, a plurality of applicators spaced around a lamp capsule for nonresonant coupling of high frequency energy to the lamp capsule, a high frequency source for supplying high frequency power, and a power splitter and phase shifter for coupling high frequency power from the source to the applicators such that an electric field applied to the lamp capsule rotates at the frequency of the source. The applied high frequency energy is distributed over the lamp capsule so that the tendency for lamp envelope hot spots is reduced. Preferably, four helical couplers are spaced at 90.degree. intervals around the lamp capsule. The high frequency power applied to adjacent applicators is shifted in phase by 90.degree..

Abstract: An electrode-less high pressure discharge lamp has a lamp vessel which is surrounded by an electric coil having turns. End portions of the coil are electrically connected to current conductors. The turns of the coil are supported by aluminium nitride, which is in thermal contact with the current conductors. There is a good heat transfer from the coil to the conductors, keeping the coil relatively cool and efficient. The coil screens the lamp vessel to a small extent only, thereby improving the lamp efficacy.

Abstract: An electrodeless lamp which operates with a high efficiency and with a lower cooling requirement. The bulb is rotated at a high speed which results in a substantial increase in efficiency. Because more of the input energy is converted to light, and less to heat, the pressure of the cooling fluid source may be reduced, resulting in a less noisy system.

Abstract: An apparatus for providing excitation of a vapor discharge lamp includes a control circuit for controlling an oscillator circuit during an ignition mode of the vapor discharge lamp to establish and maintain a substantially constant DC voltage at an output of an oscillator transistor and to establish a current flow through the oscillator transistor at a first current level sufficient to ignite the vapor discharge lamp, and for controlling the oscillator after ignition of the vapor discharge lamp to maintain the substantially constant DC voltage at the output of the oscillator transistor while reducing the current flow through the oscillator transistor from the first current level to a second current level, and in preferred embodiments, includes circuitry to suppress unwanted blocking oscillations and optimize the dynamic range of the control circuitry.

Abstract: A simulated load circuit for measuring the impedance of the arc discharge of an electrodeless discharge lamp of the type having an arc tube and an excitation coil for exciting the arc discharge in an ionizable fill contained therein includes: a secondary coil spaced apart from the excitation coil by a distance which is varied in order to vary the coupling coefficient between the secondary coil and the excitation coil; a fixed load resistance coupled to the secondary coil; and a variable matching network coupled in series or parallel with the load resistance, the impedance of the matching network being varied in order to vary the ratio of reactance to resistance of the load circuit. The distance between the secondary coil and the excitation coil is varied, and the impedance of the matching network is varied, until the input impedance of the load circuit is substantially equivalent to the operating impedance of the lamp.

Abstract: An illumination unit of the invention comprises an electrodeless low-pressure discharge-lamp (10) and a high-frequency power supply (50). The lamp (10) is provided with a gastight closed discharge vessel (20) with an ionizable fill (21). The lamp (10) further is provided with a coil (30) with turns (31,32) of a primary and a secondary winding (33,34). The power supply unit 50 is provided with input terminals (51a,51b) and is further provided with a first output terminal (52a), electrically neutral with respect to mass, that is connected to a first end (36a) of the primary winding (33) and with a further output terminal (52b) that is connected to a second end (36b) of the primary winding (33).

Abstract: The resolution .DELTA.C of a binary capacitance ladder having a plurality of N branches is precisely determined by appropriately selecting the value of a fixed capacitor in each branch relative to the parasitic capacitance of a corresponding series-connected switch. The capacitance of each respective branch varies by 2.sup.n-1 .DELTA.C, where n is the number of the branch, adjacent branches being numbered sequentially. The total capacitance is variable between C.sub.Total and C.sub.Total -(2.sup.N -1).DELTA.C in steps of .DELTA.C, where C.sub.Total is the sum of the capacitances in the ladder with all switches closed, and C.sub.Total -(2.sup.N -1).DELTA.C is the capacitance of the ladder with all switches open. For any particular branch of the ladder, the switch capacitance may be further controlled by adding a fixed capacitance in parallel with the respective switch. Such a variable capacitance is useful as a tuning capacitor in an electrodeless HID lamp ballast.

Abstract: An electrodeless lamp (e.g., an electrodeless fluorescent lamp) includes a dielectric housing shaped to conform to a portion of a lamp envelope, which housed portion is opposite to a portion through which light is emitted. The dielectric housing includes a continuous conductor, i.e., a shorted turn, situated between the dielectric housing and the lamp envelope which conforms to at least a portion of the dielectric housing. The configuration of the shorted turn, in terms of the location and amount of surface area occupied thereby, is optimized to minimize interaction between the excitation coil and any metallic fixture and to avoid interfering with lamp starting and light output.

Abstract: This invention suppresses the occurrence of interference in a very short period to prevent device destruction. An inverter circuit of this invention includes a crystal oscillator, which oscillates at a fixed frequency, a load-status detector, which receives a voltage and current to be applied to a load including an inductive or capacitive component and detects the status of the load, a voltage-controlled oscillator, which oscillates at a frequency corresponding to the load status detected by the load-status detector, and a switch, which selects the output of the crystal oscillator or the output of the voltage-controlled oscillator and supplies the selected output to the load. An electrodeless discharge lamp lighting device according to this invention uses an inverter circuit having the above structure.

Abstract: Apparatus for coupling electromagnetic energy to electrodeless lamps. A waveguide having one end connected to a source of electromagnetic radiation was closed at the second opposite end. A coupling device at the second end couples microwave energy from the waveguide to an electrodeless lamp. The coupling device includes a coaxial transmission line having a center conductor extending through one of the walls of the waveguide adjacent the second end. An alcove partition within the waveguide contacts the extending conductor and forms an alcove in the waveguide. The alcove portion provides for an impedance matching structure between the transmission line and waveguide. The electrodeless lamp which is positioned above the free end of the coaxial transmission line is excited with the coupled microwave energy.