Electric lamp and discharge devices: systems – Periodic switch in the supply circuit – Silicon controlled rectifier ignition
Patent
1997-10-07
2000-08-01
Vu, David
Electric lamp and discharge devices: systems
Periodic switch in the supply circuit
Silicon controlled rectifier ignition
315224, 315276, 315291, 315DIG5, H05B 3702
Patent
active
060971606
DESCRIPTION:
BRIEF SUMMARY
STATE OF THE TECHNOLOGY
The invention is based on an apparatus and a method for operating a gas discharge lamp of the type having a resonant circuit that contains the gas discharge lamp. DE-A 37 15 162.2 discloses a circuit arrangement for operating a gas discharge lamp that provides an AC voltage of suitable amplitude and frequency for operating the gas discharge lamp. The gas discharge lamp is contained in a resonant circuit that is excited with the resonant frequency for igniting the gas discharge lamp. After lamp ignition, the known circuit arrangement reduces the frequency of the AC voltage, with respect to the resonant frequency, to lower values for operating the gas discharge lamp in continuous operation.
It is the object of the invention to provide a circuit and a method for operating a gas discharge lamp which, using simple means, permit reliable ignition and operation of the gas discharge lamp in continuous operation.
SUMMARY AND ADVANTAGES OF THE INVENTION
The above object generally is achieved according to the present invention by an apparatus for operating a gas discharge lamp, having a resonant circuit that contains the gas discharge lamp, a series circuit connected to a voltage source and including a first semiconductor switch, an inductive element and a second semiconductor switch, and wherein the resonant circuit is connected at a connecting point between the inductive element and the second semiconductor switch.
The circuit arrangement of the invention has the advantage of providing a sufficiently-high ignition voltage for igniting a gas discharge lamp, particularly a high-pressure gas discharge lamp, and a highly-effective operating voltage in the subsequent operation of the gas discharge lamp.
In accordance with the invention, it is provided that the gas discharge lamp is contained in a resonant circuit. Moreover, a series connection is provided that includes a first semiconductor switch, a first inductive element and a second semiconductor switch, with the resonant circuit being connected at the connection of the first inductive element to the second semiconductor switch.
The method of the invention, which is preferably used with the described structure, provides that the first semiconductor switch is continuously switched on prior to lamp ignition, and the second semiconductor switch is at least approximately switched with the resonant frequency of the resonant circuit that contains the gas discharge lamp in order to excite the resonant circuit. Depending on the operating frequency, only the first inductive element of the resonant circuit remains significant following ignition of the gas discharge lamp, and the two semiconductor switches are alternatingly switched with an operating frequency for operating the gas discharge lamp in continuous operation.
Advantageous modifications and embodiments of the apparatus and method of the invention are disclosed.
An advantageous embodiment involves the configuration of the resonant circuit as a series connection of a second inductive element having a capacitor that is connected in parallel to the gas discharge lamp. The configuration as a resonant circuit according to the invention has the advantage that the capacitor connected in parallel to the gas discharge lamp is ineffective following ignition of the gas discharge lamp.
An advantageous modification of the resonant circuit provides that the resonant circuit is connected to a circuit ground, for example, by a further capacitor. The further capacitor leads to a partition of DC-voltage components at the gas discharge lamp. With this measure, the circuit arrangement of the invention can be supplied with energy by a voltage source that only provides an output voltage.
An advantageous modification provides the use of an ignition detector that detects the ignition of the gas discharge lamp and triggers switching processes in an actuation circuit of the semiconductor switches. The use of the ignition detector, which preferably evaluates the voltage occurring at the gas discharge lamp, permits a
REFERENCES:
patent: 5008597 (1991-04-01), Zuchtriegel
Encyclopedia of Electronics edited by Stan Gibilisco, TAB Professional and Reference Books, 3 pages, 1985.
Kunitz Norman
Lee Wilson
Robert & Bosch GmbH
Spencer George
Vu David
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