Electric lamp and discharge devices: systems – Current and/or voltage regulation
Reexamination Certificate
1999-10-13
2001-03-13
Wong, Don (Department: 2821)
Electric lamp and discharge devices: systems
Current and/or voltage regulation
C315S307000, C315S309000, C315S297000
Reexamination Certificate
active
06201357
ABSTRACT:
BACKGROUND INFORMATION
In a conventional arrangement of this kind for adapting the power of a gas discharge lamp, as described in German Patent No. 44 39 812, a control device is provided for supplying power to the gas discharge lamp. The control device contains a DC/DC converter that converts a DC voltage into another DC voltage, as well as a bridge circuit, in particular an H bridge, in whose diagonal branch the gas discharge lamp is located. The gas discharge lamp is supplied with AC voltage or alternating current by way of the bridge circuit. Regulation of the power conveyed to the gas discharge lamp is performed. In the event of a reduction in the mean lamp power as compared to rated operation, provision is made for a lengthening of the period of the lamp AC voltage or the lamp alternating current. As a result, the low frequency at which the lamp is operated is decreased even further. This power decrease also serves, if applicable, to protect the control device from overtemperature in order to prevent it from being damaged.
In addition to this conventional lengthening of the period in order to improve the polarity reversal operation at reduced power, and to prevent damaging overtemperatures in the control device, it is also known to ascertain the temperature of a control device using a sensor, and then to limit the maximum output power.
SUMMARY
The arrangement according to the present invention has the advantage that without using a temperature sensor, damage to the control device due to overtemperature and/or excessive load can be easily and economically prevented.
According to the present invention, in an arrangement for protecting a the output value of the power controller (i.e. the control voltage of the DC/DC converter, to be considered the manipulated variable) and the input value of the power controller (to be considered the setpoint) are ascertained; the ratio of these two values (manipulated variable to setpoint) are determined; and the value determined for the above ratio to limit the output power of the control device is used.
According to an example embodiment of the arrangement according to the present invention, the DC/DC converter contains MOSFET transistors as the switching transistors.
In accordance with a an example embodiment of the present invention, the control device contains a microcontroller, and the power controller is provided as a program in the microcontroller and is implemented as software in order to limit the output power of the control device.
In an additional example embodiment of the arrangement according to the present invention, the power controller is used to reduce the power dissipation of the control device when the gas discharge lamp is in operation, in particular during steady operation at normal power, to prevent overtemperature at the control device.
According to an example application of the arrangement according to the present invention, the arrangement is used in motor vehicles for the operation of gas discharge lamps, in particular high-pressure gas discharge lamps, in headlights.
REFERENCES:
patent: 4355344 (1982-10-01), Maurizio et al.
patent: 5635799 (1997-06-01), Hesterman
patent: 5680015 (1997-10-01), Bernitz et al.
patent: 5784268 (1998-07-01), Steffek et al.
patent: 5925990 (1999-07-01), Crouse et al.
patent: 5942714 (1999-08-01), Oberlin et al.
patent: 6005302 (1999-12-01), Borho et al.
patent: 6051939 (2000-04-01), Eckert
patent: 44 06 533 (1994-12-01), None
patent: 44 39 812 (1996-05-01), None
patent: 96 22 007 (1996-07-01), None
Kern Robert
Seiler Hartmut
Kenyon & Kenyon
Robert & Bosch GmbH
Vo Tuyet T.
Wong Don
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