Koninklijke Philips Corporation N.V.

Johannes Theodorus Jacobus Van Haastrecht

Pieter C Ooms

Ronald Arjan Van Den Brakel

Willem Johannes Van Den Bogert

Wai Pang Chow

Peter Johannes Wilhelmus Vankan

Hindrik Hermannus Stel

Jeroen Jan Wits

Cornelis De Putter

A method for operating a fluorescent lamp () having a nominal power (WLa) and stabilized with an EM ballast (B) comprises the steps of during normal operation, short-circuiting the lamp during a closing time interval (CTI) during each current period in order to operate the lamp at a reduced power. The method comprises the step of detecting whether the lamp is stabilized by means of an inductive ballast or by means of a capacitive ballast. If it is found that the ballast is capacitive, the timing of the closing time interval (CTI) is set such that the closing time interval (CTI) has a first closing time segment (CTS) immediately before a zero-crossing of the current, having a first duration (&#x394;) higher than zero, and a second closing time segment (CTS) immediately after said zero-crossing of the current, having a second duration (&#x394;) higher than zero.

Method and device for driving a gas discharge lamp

A low-pressure mercury vapor discharge lamp is provided with a discharge vessel ( ). The discharge vessel comprises tubular end portions ( &prime;), which each have a longitudinal axis ( &prime;). The discharge vessel ( ) encloses a discharge space ( ) containing a filling of mercury and an inert gas in a gastight manner. Electrodes ( &prime;) are arranged in the discharge space ( ). An auxiliary amalgam is provided on a carrier ( &prime;) in the proximity of the electrodes ( &prime;). According to the invention, a part of the carrier ( &prime;) is arranged in a plane transverse to the longitudinal axis ( &prime;). Preferably, a stem ( &prime;) in the tubular end portion ( &prime;) carries, apart from the electrode ( &prime;), a support in the form of a wire ( &prime;) or an extended exhaust tube, which support carries the carrier ( &prime;). In an alternative embodiment, the carrier is clamped directly onto the stem. Preferably, the carrier ( &prime;) is electrically insulated with respect to the electrode. Preferably, a distance d between the carrier ( &prime;) and the electrode ( &prime;) lies in the range 1&lE;d&lE;3 mm. According to the invention, the discharge lamp has a relatively short run-up time.

Low-pressure mercury vapor discharge lamp with improved auxiliary amalgam

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Eindhoven, Netherlands

Johannes Theodorus Jacobus Van Haastrecht