Gte Laboratories Incorporated

Osram Sylvania Inc.

Yan M Li

A Bowman Budinger

Wojciech W Byszewski

Philip D Gregor

Brian Dale

William M Keeffe

Alan Lenef

Helmar Adler

Operation of an HID lamp may be improved by forming a glow generating recess on an exterior side the electrode. The lamp may be of standard construction with a light transmissive lamp envelope having a wall defining an enclosed volume. At least one electrode assembly is extended in a sealed fashion from the exterior of the lamp through the lamp envelope wall to be exposed at an inner end of the electrode assembly to the enclosed volume. A metal halide lamp fill is enclosed with an inert fill gas. The inner end of the electrode is formed with a recess having a least spanning dimension S and a recess depth of D where S is greater the electron ionization mean free path but less than twice the cathode fall plus negative glow distances, throughout the glow discharge phase of starting, for the chosen fill gas composition and pressure (cold).

Slotted electrode for high intensity discharge lamp

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.

Method of hot restarting a high intensity discharge lamp

In one aspect of the present invention a capacitor is placed in series with the ballast and the lamp. The capacitor lowers the impedance during lamp starting and is shorted out when final arc conditions of the lamp are reached. Method and device for improvement of lumen maintenance of high intensity discharge lamps through minimizing the wall blackening during lamp starting is disclosed. Reducing the electrode material sputtering during the thermionic arc phase of the lamp starting process was achieved by decreasing the cathode fall voltage. The cathode fall voltage in these lamps was decreased by increasing the current flowing through during the starting phase. The increase of starting current was achieved by increasing the open circuit voltage or by decreasing ballast impedance.

Method and circuit for improving HID lamp starting

Method and circuit for improved HID lamp maintenance

The present disclosure describes a method for determining the condensate location within an HID lamp. The method involves monitoring current and voltage waveforms during the glow phase of lamp starting. If the voltage drop during the glow phase is low with a corresponding high current, then the volatile component of the lamp fill has condensed on the electrodes during the previous cool down period. If the voltage drop is high and current is low then most of the condensate has localized on the arc tube wall. An automated detection apparatus is used to carry out the measurements to determine condensate location.

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Cambridge, MA, United States of America

Yan M Li