U.S. Philips Corporation

Pieter Postma

Henk Houkes

Andreas C Van Veghel

Hans G Ganser

Dieter Leers

Klaus B Lohn

Martin Ossmann

Johannes A Van Vliet

Patricius W Lepelaars

Jan W Denneman

Andreas G Van Veghel

A circuit for operating a discharge lamp having circut input terminals for connection to a supply voltage source and an inverter coupled to the circuit input terminals for generating an AC voltage at a frequency f from a supply voltage supplied by the supply voltage source. A piezotransformer has transformer input terminals coupled to the inverter output terminals. Terminals for lamp connection are coupled to the inverter output terminals and is provided for detecting whether the lamp has ignited. A protective device is coupled between the output terminals of the inverter and the transformer output terminals so that the inverter is effectively protected against damage due to ignition pulses generated by the piezotransformer.

Discharge lamp operating circuit using piezoelectric transformer and

A circuit arrangement for operating a lamp has circuit input terminals for connection to a supply voltage source. An inverter is coupled to the circuit input terminals for generating an AC voltage with a frequency f from a supply voltage supplied by the supply voltage source and includes inverter output terminals. A piezotransformer has input terminals coupled to the inverter output terminals. Terminals for lamp connection are coupled to the inverter output terminals. A detector detects whether the lamp has ignited. The transformer input terminals are connected to the inverter output terminals only by means of passive components and the inverter comprises means coupled to the detector for changing the frequency f in response to the ignition of the lamp. The circuit arrangement is simple and inexpensive and need not provide a device for switching the piezotransformer out of the circuit after ignition of the lamp.

Inventer-ballast using a piezoelectric transformer

An electrodeless low-pressure discharge lamp comprising a glass lamp vessel (1) which is sealed in a gas-tight manner and is filled with a metal vapor and a rare gas, this lamp vessel being provided with a tubular protuberance (2) which accommodates a rod-shaped core (3) of magnetic material surrounded by a wire winding (4) connected to a high-frequency supply unit, by means of which during operation of the lamp an electrical discharge is maintained in the lamp vessel, the inner side of the lamp vessel being provided with a transparent conductive layer (10), which is electrically connected by means of a lead-through member (12) to a conductor, such as a metal rod (11) provided in the core (3), located outside the lamp vessel, this lead-through member (12) being located at the end of the tubular protuberance, and being electrically connected to the internal conductive layer, for example by means of a wire spring (15).

Electrodeless low-pressure discharge lamp

An electrodeless low-pressure discharge lamp comprising a lamp vessel (1) which is sealed in a vacuum-tight manner and is filled with a metal vapor (for example mercury) and a rare gas, this lamp being provided with a core (4) of magnetic material (for example ferrite), while during operation of the lamp, and electric field is produced in the lamp vessel by means of a winding arranged to surround this core and a high-frequency supply unit connected thereto, the lamp vessel further being provided with an internal transparent conductive layer (11) and an external conductive layer (12), which during operation of the lamp is connected to one of the mains conductors and which together with the internal conductive layer (11) forms a capacitor.

An electrodeless low-pressure discharge lamp comprising a glass lamp vessel sealed in a gas-tight manner and filled with a metal vapor and a rare gas, and a winding on a ferrite core. During lamp operation an electrical discharge is maintained in the lamp vessel by the winding connected to a high-frequency supply. The winding is surrounded by a thin-walled cylindrical metal body or layer which is electrically insulated from the winding, is interrupted at at least one area and is connected during operation of the lamp to one of the power mains conductors.

An electrodeless low-pressure discharge lamp having a lamp vessel (1), a core (3) of magnetic material, a first winding (7) arranged to surround the core and connected to a high-frequency supply unit (4), one of the lead-in wires of this winding being electrically connected to a lead-in wire of a second winding (11) with a free end (12), while during operation of the lamp the potential drop between the ends of the second winding is substantially equal to the potential drop between the ends of the first winding and the potential drops in the two windings vary in opposite senses. Interference currents at the supply mains to which the lamp is connected are then strongly suppressed.

An electrodeless metal vapor discharge lamp comprising a lamp vessel (1) which is sealed in a vacuum-tight manner and is further filled with a rare gas, which lamp is provided with a core (4) of magnetic material, in which a high-frequency magnetic field can be induced by means of an electric supply unit (7) and a winding (5) arranged to surround the core, an electric field being produced in the lamp vessel (1), the surface area of a cross-section orthogonal to the axis of the winding lying between 20 mm.sup.2 and 60 mm.sup.2, the lamp vessel (1) containing as rare gas krypton and/or argon at a pressure of at most 100 Pa, and the axial length of the winding lying between 8 and 15 mm.

Electrodeless metal vapor discharge lamp with minimized electrical

An electrodeless low-pressure discharge lamp comprising a lamp vessel (1) sealed in a vacuum-tight manner and filled at least with a metal vapor and a rare gas, the lamp being provided also with a cylindrical core (2) of magnetic material, such as ferrite, a winding (4) arranged to surround the core (2) and an electrical supply unit connected thereto for producing during operation of the lamp an electrical field in the lamp vessel (1). The supply unit is located in a thin-walled metal housing (8) provided in a wall portion (9) of synthetic material, which is partly of conical shape and is provided at its end with an Edison lamp cap (10), and the core (2) accommodates a rod-shaped or tubular body (11) of thermally conducting material connected to the housing (8). In order to improve the ignition properties of the lamp, an electrical insulator (12) is provided between the end of the body (11) and the wall of the housing (8).

A discharge lamp having a sealed glass vessel filled with gas and a metal vapor, operated with a supply at a frequency of at least 20 kHz. An interference-suppressing conductive layer is arranged on a wall surface surrounding the discharge, and connected to an electric supply lead-in wire. Preferably, a plurality of insulated metal rings, on the outside of the wall, also surround the discharge.

Discharge lamp with interference shielding

Electrodeless gas discharge lamp having a lamp vessel which is closed in a vacuum-tight manner, the lamp comprising a rod-shaped core of a magnetic material, a member of a heat-conducting material (for example copper) extending at or near the axis of the core, heat generated in the core during operation of the lamp being discharged to the environment of the lamp by the member.

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Eindhoven, Netherlands

Pieter Postma