U.S. Philips Corporation

North American Philips Corporation

Egbert Van Zanten

Hubertus M Chermin

Charles B Mattas

Stefan P Szuba

An ignitor circuit for a gas discharge lamp includes a transformer and means for generating pulsatory voltages across a primary winding of the transformer to generate ignition pulses by means of a secondary winding of the transformer. The ignitor circuit further includes first means for measuring an amplitude of the ignition pulses, and second means for changing the pulsatory voltage across the primary winding, and thus changing the amplitude of the ignition pulses, in dependence on the measured amplitude of the ignition pulses. The ignitor circuit is capable of generating a suitable ignition pulse over a wide range of connection cable lengths.

Discharge lamp ignitor which adjusts the amplitude of ignition pulses

A transformer (10) which forms part of a lamp ignition switching device has at least its primary winding (12) composed of a foil. Moreover, the transformer has an air core. In this way a satisfactory coupling, which is also maintained at high temperatures, is obtained between the primary (12) and the secondary (11) winding. This switching device is very suitable to be built in a lamp and to ignite the lamp at a high temperature.

Switching device and high-pressure discharge lamp

A circuit arrangement for igniting a high-pressure discharge lamp (6), in which ignition voltages are generated by means of discharges from two capacitors (10, 14) through a primary winding (12) of a transformer. During this, the lamp (6) is connected to a secondary winding (4) of this transformer. One capacitor (14) is charged to a higher voltage than the other capacitor (10), the two capacitors being discharged alternately through breakdown elements (11, 15) associated with the capacitors (10, 14, respectively). An ignition pulse with a low peak value for igniting the lamp (6) in the cold state is then followed by an ignition pulse with a high peak value for igniting the lamp (6) if it should be in the hot state.

Circuit arrangement suitable for igniting a high-pressure discharge lamp

Apparatus for starting and operating a high pressure discharge lamp includes a pair of input terms for connection to a high frequency inverter. A step-up transformer couples the input terminals to a pair of output terminals for connection of the discharge lamp. A switching arrangement including a voltage-multiplier circuit, is coupled to the primary winding of the transformer and includes a first branch comprising a first capacitor and a diode and a second branch comprising a diode. Between the first capacitor and the diode of the first branch is connected a third branch comprising a semiconductor switch such as a SIDAC. The first branch is connected through the transformer coil to a first supply source connection point. The second branch is connected to a tap point of the coil. The first and the second branch are connected via a common impedance including second capacitor and an inductor to a second supply source connection point. The third branch is connected directly to both the coil and the diode of the second branch. The SIDAC periodically switches over from a cut-off state to a conductive state in response to a voltage developed across one or more capacitors of the voltage-mulitplier circuit thereby to rapidly discharge the capacitor voltage across the winding of the step-up transformer. A high voltage ingnition pulse is generated in the secondary of the step-up transformer and is applied to the output terminals to ignite a connected discharge lamp.

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Eindhoven, Netherlands

Egbert Van Zanten