General Electric Company

Joseph C Borowiec

Sayed-Amr A El-Hamamsy

Victor D Roberts

John P Cocoma

Joseph Darryl Michael

George A Farrall

Otward M Mueller

Hsueh-Rong Chang

Robert James Thomas

Zoltan Toth

Sandor Lukacs

Andrew P Blau

Graham M Forsdyke

Steven John Everest

Martin Geoffrey Scott

William Wayne Akins

Kenneth J Downton

Robert S Scott

Erno Soos

Shaun Adrian Malin

Robert F Pashley

Robert A Senecal

A glass extension (,) with a cavity (,) for an amalgam (,) is added to an exhaust tube (,) or a flare (,) of a fluorescent lamp. The mouth (,) of the cavity (32) is provided with a bimetal valve having a cover portion (,) to close the cavity (,) when the lamp is cold and to open the cavity when the lamp is hot. The amalgam (,) is a metallic amalgam of, for example, mercury or other know suitable materials for establishing a metallic vapor equilibrium during operation of a discharge lamp. The amalgam holder helps to maintain optimum mercury vapor equilibrium at start-up, and to reduce the effects of mercury vapor starvation resulting from off-times.

Fluorescent lamp extension tube amalgam holder

A compact electrodeless fluorescent lamp has an A-line configuration including a globular upper portion which becomes narrower toward a lower portion, terminating in a narrow end. The narrow end of the A-line envelope is connected to a base. The alternating current energy source is electrically connected through the base, via a ballast, to the excitation coil. The ballast is integral with the lamp and is contained substantially within the re-entrant cavity.

Compact electrodeless fluorescent A-line lamp

An integrated starting and running amalgam assembly for an electrodeless SEF fluorescent lamp includes a wire mesh amalgam support constructed to jointly optimize positions of a starting amalgam and a running amalgam in the lamp, thereby optimizing mercury vapor pressure in the lamp during both starting and steady-state operation in order to rapidly achieve and maintain high light output. The wire mesh amalgam support is constructed to support the starting amalgam toward one end thereof and the running amalgam toward the other end thereof, and the wire mesh is rolled for friction-fitting within the exhaust tube of the lamp. The positions of the starting and running amalgams on the wire mesh are jointly optimized such that high light output is achieved quickly and maintained, while avoiding any significant reduction in light output between starting and running operation.

Integrated starting and running amalgam assembly for an electrodeless

At least one amalgam, which is disposed within the lamp envelope of an electrodeless fluorescent lamp to control mercury vapor pressure, is mechanically supported by an amalgam support arrangement in a manner non-invasive to the lamp envelope. The amalgam support arrangement supports one or more amalgams in a 'flag' configuration and includes a support member, one end of which is configured for friction-fitting within the exhaust tube opening. The flag may be configured as a wire mesh or spiral-shaped wire, for example. Exemplary configurations for this end of the support member include a U-shape, spiral, zig-zag, or tubular configuration.

Amalgam support arrangement for an electrodeless discharge lamp

An electrodeless fluorescent reflector lamp has a discharge vessel containing a fill, a solenoid in a reentrant and indium on the inner wall of the vessel acting as a primary amalgam. A secondary amalgam of indium may be provided on the reentrant. The primary amalgam is preferably under an insulative skirt. The vessel has a light reflective coating on the inner wall under the skirt. The exhaust tube is tipped off at the proximal end of the reentrant or is omitted, the vessel being tipped off at the distal end of the reentrant.

Amalgam Positioning in an electrodeless fluorescent lamp

For a given lamp size and lumen power, an electrodeless fluorescent lamp is configured with a split excitation coil and a baffle structure to provide multiple discharges, resulting in a higher light output and higher luminous efficacy.

Multiple-discharge electrodeless fluorescent lamp

An amalgam is accurately placed and retained in an optimized location in the exhaust tube of an electrodeless SEF lamp for operation at a mercury vapor pressure in the optimum range from approximately four to seven millitorr by forming a dimple in the exhaust tube and using a dose locating member to locate and retain the amalgam on the side of the dimple away from the core of the lamp after filling the lamp. As an alternative, two dimples may be situated on opposite sides of the exhaust tube for performing the same function as, but with less depth than, the single dimple. In another alternative embodiment, first and second dimple configurations are formed in the exhaust tube after tip-off thereof, each dimple configuration including either one or two dimples. The second dimple configuration is spaced apart from the first dimple configuration along the length of the exhaust tube. In this way, the amalgam may be initially positioned farther from the tip-off region, thereby avoiding problems during tipping off of the exhaust tube, such as loss of mercury from the lamp, or quenching of the tip which could cause stress cracks. After tip-off, the second dimple configuration allows for placement of the amalgam closer to, or preferably in contact with, the tip of the sealed exhaust tube, i.e., the coolest location in the exhaust tube.

Accurate placement and retention of an amalgam in a electrodeless

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.

Electronically controllable capacitors using power MOSFET's

An amalgam is accurately placed and retained in an optimal location near the cold spot of an electrodeless SEF lamp for operation at a mercury vapor pressure in the optimum range from approximately four to seven millitorr. The amalgam is positioned at the tip of an extended exhaust tube near the apex of the lamp envelope by forming an indentation in the exhaust tube and, in some embodiments, a dose locating member in combination therewith. An evacuation hole is formed below the indentation for evacuation of the lamp envelope, or bulb, during lamp fabrication. In an alternative embodiment, the extension of the exhaust tube is situated perpendicular to the main portion of the tube to allow for lateral adjustment of the position of the amalgam, thereby allowing for even further control of the amalgam operating temperature.

Electrodeless fluorescent lamp with optimized amalgam positioning

An electrodeless SEF fluorescent discharge lamp of the type having an envelope with a re-entrant cavity formed therein for containing an excitation coil includes an amalgam positioned for maintaining an optimum mercury vapor pressure during lamp operation. An exhaust tube extending through the re-entrant cavity has an extension into the envelope toward the apex of the lamp envelope. The exhaust tube extension has a rim portion for holding an amalgam support in position within the lamp envelope. The amalgam support preferably comprises a wire wrapped about and held in place by the rim portion. At the other end of the wire, an amalgam is wetted to a wire screen or helical wire structure at a predetermined optimal location within the lamp envelope. Alternatively, two amalgams are supported by the amalgam support at predetermined optimal locations for starting and steady-state operation of the lamp, respectively.

Amalgam support in an electrodeless fluorescent lamp

An excitation coil for an electrodeless fluorescent lamp of the type having a core of insulating material, is made of a metal having a low thermal expansion coefficient which is plated with a high-conductivity metal. An insulating coating is applied over the metal plating. An exemplary coil includes a molybdenum wire, plated with silver, and finally coated with alumina. The result is a thermally stable excitation coil that maintains its shape, even at high operating temperatures, and hence maintains its impedance characteristic over the operating range of the lamp.

Excitation coil for an electrodeless fluorescent lamp

A low-inductance package for multiple paralleled devices includes an electrically insulating substrate having three power terminals direct-bonded to the upper surface thereof and a conductive pad direct-bonded to the lower surface thereof for connection to a heat sink. Two groups of multiple parallel-coupled devices are each soldered to one of the three power terminals and are further connected in a half-bridge configuration such that one of the three power terminals is common to both groups of devices. The package further includes a pair of first Kelvin terminals, i.e., a first Kelvin control terminal and a first Kelvin source terminal, and a pair of second Kelvin terminals, i.e., a second Kelvin control terminal and a second Kelvin source terminal. The Kelvin terminals are soldered to the appropriate power terminals, depending upon the particular circuit configuration. The multiple parallel-coupled devices of each group are aligned such that the lengths of the wire bonds to the respective control and power terminals are substantially the same and furthermore are shortened. As a result, the stray inductance due to the wire bonds is the same for each group of devices and is minimized. Current sharing and simultaneous switching of devices within each group are thus ensured.

Low-inductance package for multiple paralleled devices operating at high

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.

Piezoelectrically actuated variable capacitor

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.

Feedback control system for a high-efficiency class-D power amplifier

A high-frequency capacitor includes first and second conductive members, each having a plurality of U-shaped metal plates disposed parallel to each other and a terminal plate coupled between the ends thereof. The metal plates of the first and second conductive members are interleaved, and a dielectric material is disposed between the adjacent metal plates. The result is a low-inductance capacitor suitable for use in a high-frequency electronic circuit, such as an electrodeless high intensity discharge (HID) lamp ballast. Furthermore, such acapacitor may be suitably integrated with a heat sink in an electrodeless HID lamp ballast.

Growing community of inventors

Schenectady, NY, United States of America

Joseph C Borowiec