U.S. Philips Corporation

Herman Adrianus Smulders

Hubertus M Chermin

Cornelis A Jacobs

Meerten Luursema

Gijsbert H Kuus

Jaap Rozenboom

Robertus L De Vaan

The invention relates to an electric device provided with a switch which is constructed as a discharge tube which comprises at least two main electrodes and a reversible hydrogen getter. According to the invention the discharge tube contains a rare gas so that the current flow in the conducting state of the switch is mainly ensured by that rare gas. The non-conducting stage of the switch can be obtained by heating the getter. Namely, the hydrogen pressure in the discharge tube then becomes so high that the discharge in the tube is extinguished. Heating of the getter is preferably effected by the heat developed by the current between the main electrodes. This results in a self extinguishing breakdown element.

Electric device provided with a switch which is designed as a discharge

The invention relates to an arrangement for starting and supplying a discharge lamp provided with cold electrodes. The lamp is shunted by a starter circuit which consists of a series arrangement of at least a capacitor and a controlled semiconductor switching element having a bidirectional thyristor characteristic. According to the invention a resistor with a positive temperature coefficient is connected in series with the capacitor and the controlled semiconductor switching element. If the lamp fails to ignite the device produces substantially no radio interference owing to the high-ohmic value of the PTC resistor produced by an increase in its temperature. Furthermore, a controlled semiconductor switching element having a low blocking voltage can now be used. Normal starting of the lamp is hardly affected by the PTC resistor.

Arrangement for starting and operating a discharge lamp

A device for starting a discharge lamp by means of a transistor starter provided with an auxiliary transistor for stopping the starting procedure if the lamp fails to ignite. A zener diode is included in the control circuit of the auxiliary transistor, a capacitor is connected in parallel across the lamp, and a self-inductor is included in the connection from the lamp to the main transistor. The auxiliary transistor has a second function in that, by the action of the zener diode, the auxiliary transistor delays the conduction of the main transistor so that a large rise of the voltage between the lamp electrodes is produced, which provides a more reliable ignition of the lamp within a large temperature range.

Device for starting and feeding a discharge lamp

An improved method of and apparatus for operating an electric discharge lamp which includes a controlled semiconductor switch connected in shunt with the lamp. By means of the semiconductor switch, the discharge lamp receives, when in operation, a plurality of voltage peaks, during every second half cycle of the AC supply voltage.

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Eindhoven, Netherlands

Herman Adrianus Smulders