Discharge lamp driver circuit

Details Discharge lamp driver circuit Discharge lamp driver circuit

2000-04-06

2001-12-11

Philogene, Haissa (Department: 2821)

Electric lamp and discharge devices: systems

Periodic switch in the supply circuit

Impedance or current regulator in the supply circuit

C315S291000, C315S282000, C315S20000A

Reexamination Certificate

active

06329762

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to a discharge lamp driver circuit.
High intensity discharge lamps (HID lamps) are arc lamps and do not have a physical filament as is the case with incandescent lamps. The HID lamp comprises a sealed envelope filled with xenon gas at a pressure above one atmosphere. The active volume of the lamp also includes within it mercury and other compounds (salts) which emit an intense light once an arc is established within the active volume of the lamp.
An HID lamp is approximately four time more efficient than alternative halogen lamps and produces a colour temperature similar to that of natural daylight. HID lamps are used for example in premium quality cars, floodlighting, architectural lighting and street lighting.
In order to light an HID lamp different conditions are required to initiate and then to maintain an arc. Firstly, a high voltage, typically up to 25000 volts, is required to establish the arc. Once the arc has been established, a power source must be connected to the lamp so as to maintain the arc. In conventional HID lamp driver circuits, the power source consists of two stages, that is a first stage to provide a high DC value and a second stage to convert this DC value into an AC voltage to maintain the arc. It is desirable to stabilise the power supply to the lamp by controlling the supplied voltage and/or current, and in order to achieve this conventional circuits require some form of computational capability so as to produce an output representing the product of the supplied voltage and current. As a result the conventional HID lamp driver circuits are relatively complex and expensive.
SUMMARY OF THE INVENTION
It is an object of the present invention to obviate or mitigate the problems outlined above.
According to the present invention, there is provided a driver circuit for a discharge lamp, comprising a constant current source for connection to the lamp, and a voltage source connected to the constant current source, the voltage source delivering a variable voltage to the constant current source, and means being provided to vary the delivered voltage to stabilise the supply of power to the lamp.
As a result of relying upon a constant current source, the power supply can be stabilised simply by appropriate control of the voltage delivered to the constant current source. The voltage applied to the lamp may be directly monitored and used to control the voltage source.
The constant current source may comprise a transformer an output winding of which is connected through a ballast capacitor to the lamp. A variety of different variable voltage sources may be used, for example a closed loop DC voltage supply circuit or an open loop DC voltage supply circuit.


REFERENCES:
patent: 3987339 (1976-10-01), Wroblewski
patent: 4009387 (1977-02-01), Nuver
patent: 4240009 (1980-12-01), Paul
patent: 4777409 (1988-10-01), Tracy et al.
patent: 4912374 (1990-03-01), Nagase et al.
patent: 5155415 (1992-10-01), Schmidt et al.
patent: 5225742 (1993-07-01), Beasley
patent: 5677602 (1997-10-01), Paul et al.
patent: 6075326 (2000-06-01), Nostwick

Affiliated with

Also associated with

Rating

Discharge lamp driver circuit does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Discharge lamp driver circuit, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Discharge lamp driver circuit will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2586937