Electric lamp and discharge devices: systems – Periodic switch in the supply circuit – Periodic switch in the primary circuit of the supply...
Patent
1989-10-27
1991-09-24
Pascal, Robert J.
Electric lamp and discharge devices: systems
Periodic switch in the supply circuit
Periodic switch in the primary circuit of the supply...
315DIG7, H05B 3700
Patent
active
050516604
DESCRIPTION:
BRIEF SUMMARY
PRIOR ART
The invention is based on a circuit arrangement, for operating a gas discharge lamp on a direct-current source, as is known e.g. from DE-OS 31 39 340. This publication shows a circuit arrangement for feeding an X-ray tube which is connected with a known resonant circuit inverter via a LC series resonant circuit. In this known arrangement, the series resonant circuit is located in the primary circuit of the transformer, wherein the inductance is, formed by means of the leakage inductance of the high-voltage transformer and the lead inductance.
A wiring example for the current supply of a fluorescent lamp from a direct-current source is described in a text published by Siemens AG under stock number B1-B3192. The lamp current is not stabilized in the described preswitching device. The circuit is started by means of a special starting generator, the alternating voltage for operating the fluorescent lamp is generated by means of two SIPMOS transistors which alternately connect a primary winding of the transformer with an input direct-voltage. A RC network is connected in series with the fluorescent lamp in the secondary circuit of the transformer and provides an ignition voltage of approximately 1000 volts to the lamp by means of resonance step-up. After the firing of the lamp, the voltage at the resonant circuit capacitor breaks down to the maintaining voltage of 55 volts. The lamp current is limited by the resonant circuit choke.
ADVANTAGES OF THE INVENTION
In contrast, the circuit arrangement, according to the invention, has the advantage that, in continuous operation, a supply of the lamp is always effected with approximately constant power output. This is also true particularly with fluctuating input direct-voltage as is available e.g. in motor vehicles. The circuit arrangement, according to the invention, supplies an alternating voltage of suitable level and frequency for feeding the gas-discharge lamp with an energy which is always constant and accordingly ensures a constant brightness of the lamp. Moreover, the circuit arrangement, according to the invention, supplies the ignition voltage between 1 and 10 kV which differs depending on the lamp temperature.
Advantageous developments and improvements of the circuit arrangement provide the production of an increased heating up current after the lamp is switched on, so as to enable a quicker brightening. The maximum value of the lamp current is limited to a value which is not harmful for the electrodes of the gas-discharge lamp.
It has proven particularly advantageous that the inverter of the circuit arrangement be constructed as a push-pull inverter with transistors, whose inputs for regulating the angle of flow of opposite primary currents of the transformer are supplied with output-proportional signals corresponding to the actual values derived from the lamp current and lamp voltage. In contrast to the known circuit arrangements, it is accordingly possible to operate the lamp at constant power output and, constant brightness in a particularly simple and advantageous manner, and further also to provide the ignition voltage necessary for the hot reignition. The latter is required because there is no electrode heating, which reduces the work function of the charge carrier.
DRAWING
An embodiment example of the invention is shown in the drawing and explained in more detail in the following description.
FIG. 1 shows the principle of the circuit arrangement according to the invention;
FIG. 2 shows the output regulator of the inverter;
FIG. 3 shows the configuration of the voltage at the power output of the inverter; and
FIG. 4 shows the construction of the transformer.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The overall construction of the DC/AC inverter is designated by 10 in FIG. 1. This inverter substantially contains a power output regulator 11 and two power transistors 12 and 13. The chief components of the power output regulator 11 are a switching device 14 for the alternating pulse-interval modulated control of the transistors 12 and
REFERENCES:
patent: 4414493 (1983-11-01), Henrich
patent: 4477748 (1984-10-01), Grubbs
Siemens, Schaltbeispiel: Batteriebetriebenes 100 kHz Lampen-Vorschaltgerat mit Sipmos-Transistoren fur Eine 18W Leuchtstofflampe.
Domann Helmut
Rupp Hartmann
Pascal Robert J.
Robert & Bosch GmbH
Striker Michael J.
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