Electric lamp and discharge devices: systems – Current and/or voltage regulation – Automatic regulation
Reexamination Certificate
1995-02-22
2001-01-30
Shingleton, Michael B (Department: 2817)
Electric lamp and discharge devices: systems
Current and/or voltage regulation
Automatic regulation
C315S224000, C315S291000, C315SDIG005, C315SDIG007
Reexamination Certificate
active
06181085
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electronic ballast for gas discharge lamps, particularly of a type wherein ballast power output is continuously controllable by way of an adjustment means on the light switch.
2. Description of Prior Art
Ballasts with controllable power output have been previously described, such as in U.S. Pat. No. 4,677,345 to Nilssen; wherein is described a means for controlling the power supplied to a fluorescent lamp by way of controlling the temperature of a pair of saturable current transformers used for determining the frequency in a self-oscillating half-bridge inverter loaded by way of a high-Q series-resonant LC circuit. The higher the temperature, the lower the resulting power output.
However, in an electronic ballast powered from regular electric utility AC power line voltage, prior art does not provide for a control arrangement wherein ballast output power can be controlled by way of applying a control voltage between a control input terminal and one of the power line conductors, where this control input terminal is galvanically connected with the electronic circuitry of the electronic ballast.
SUMMARY OF THE INVENTION
Objects of the Invention
A basic object of the present invention is that of providing for a cost-effective ballasting means for powering gas discharge lamps.
A more specific object is that of providing for control means in a series-resonance-loaded inverter ballast.
Another more specific object is that of providing an electronic ballast the power output from which may be step-wise or continuously controlled by way of a lighting switch having a manually adjustable control means.
These as well as other objects, features and advantages of the present invention will become apparent from the following description and claims.
Brief Description
An inverter-type fluorescent lamp ballast is, via a light switch (or, more accurately, a light control means) located at a convenient switch point, powered from the power line by way of two power conductors and one control conductor. From the light switch, which contains a power switch means as well as a continuous-range adjustment means, the control conductor is provided with a DC voltage of continuously (or, alternatively, step-wise) adjustable magnitude; which DC voltage is referenced to one of the power conductors.
At the ballast, the adjustable-magnitude DC voltage is introduced into the ballast circuitry via a diode, thereby to establish within the ballast circuitry a control voltage of magnitude substantially equal to the adjustable-magnitude DC voltage. This control voltage is used for controlling the magnitude of the ballast's 30 kHz output current, thereby providing for light output control.
The ballast itself is a self-oscillating half-bridge inverter loaded by way of a series-tuned high-Q LC circuit connected across its output. A pair of fluorescent lamps is series-connected across the tank-capacitor of the LC circuit.
The inverter has two bipolar transistors, each driven by an associated saturable current transformer that provides for a transistor ON-time dependent upon the magnitude of an associated bias voltage.
One of the transistors has a control arrangement connected in circuit with its associated saturable transformer; which control arrangement is operative to control the magnitude of this transistor's bias voltage. As the magnitude of this bias voltage is controlled, the magnitude of the lamp current is correspondingly controlled. The magnitude of the bias voltage is controlled as a function of the magnitude of the adjustable-magnitude DC voltage.
Otherwise, the magnitude of the bias voltage is automatically controlled such that: (a) with the lamps not-yet-ignited, the magnitude of the voltage across the tank-capacitor is maintained at a level about equal to or somewhat higher than the magnitude of the normal lamp operating voltage, except that for 10 milli-seconds once each second the magnitude is increased to a level high enough to cause lamp ignition; and (b) after the lamps have ignited, the magnitude of the lamp current is prevented from exceeding a pre-set maximum level.
REFERENCES:
patent: 4127798 (1978-11-01), Anderson
patent: 4277728 (1981-07-01), Stevens
patent: 4471269 (1984-09-01), Ganser et al.
LandOfFree
Electronic ballast with output control feature does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Electronic ballast with output control feature, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Electronic ballast with output control feature will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2527373