High-efficiency incandescent lamp power controller
OwnerGuido Lemkeinventor
Life of this patent
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Abstract
A high-efficiency low-cost electronic controller circuit for powering incandescent lamps which provides constant RMS voltage output from a battery or other varying output DC supply. The controller prolongs lamp life by limiting the cold filament in-rush power thereby reducing filament thermal shock deterioration. The controller further prolongs lamp life by supplying rectified AC power which reduces lamp filament embrittlement. A supply voltage monitor indicates a low-battery condition by flashing the lamp. A battery tester enables determination of the battery voltage which is indicated by pulse-coded modulation of the incandescent lamp brightness. A transistor contained in the controller eliminates the usual high-current mechanical power switch.
Claims29
A circuit for maintaining constant RMS voltage across an incandescent lamp when powered from a varying voltage supply with the circuit comprising:
- an incandescent lamp with a nominal voltage rating which is approximately equal to the lowest voltage output of the varying voltage supply;
- a primary high current series circuit comprised of the incandescent lamp, the varying voltage supply, and a switch adapted for switching the current flow from the varying voltage supply to the incandescent lamp;
- a means of sensing the voltage applied to the incandescent lamp adapted to produce a feedback signal of the voltage waveform applied to the incandescent lamp;
- a low pass filter with the feedback signal applied to the low pass filter input and the low pass filter output producing a voltage level proportional to the average of the voltage waveform applied to the incandescent lamp;
- a reference network which produces a scalable output voltage command signal having the characteristic that the scalable output voltage command signal approximates a hyperbolic voltage function of the varying voltage supply;
- a comparison means having two inputs for comparing the voltage output of the low pass filter with the output voltage command signal and the comparison means having an output which controls the switching action of the switch;
- wherein the switch is turned-on when the output command signal exceeds the output of the low pass filter and is turned-off when the output command signal does not exceed the output of the low pass filter thereby maintaining constant RMS voltage application to the incandescent lamp.
A circuit for maintaining constant RMS voltage across an incandescent lamp when powered from a varying voltage supply with the circuit comprising:
- an incandescent lamp with a nominal voltage rating which is approximately equal to the lowest voltage output of the varying voltage supply;
- a primary high current series circuit comprised of the incandescent lamp, the varying voltage supply, and a switch adapted for switching the current flow from the varying voltage supply to the incandescent lamp;
- a means of sensing the voltage applied to the incandescent lamp adapted to produce a feedback signal of the voltage waveform applied to the incandescent lamp;
- a means for squaring the voltage of the feedback signal waveform applied to the incandescent lamp;
- a low pass filter with the squared feedback signal applied to the low pass filter input and the low pass filter output producing a voltage level proportional to the average of the square of the voltage waveform applied to the incandescent lamp;
- a scalable source of reference potential adapted to be coupled to the varying supply voltage providing substantially constant output voltage command signal potential when energized;
- a comparison means having two inputs for comparing the voltage output of the low pass filter with the output voltage command signal and the comparison means having an output which controls the switching action of the switch;
- wherein the switch is turned-on when the output command signal exceeds the output of the low pass filter and is turned-off when the output command signal does not exceed the output of the low pass filter thereby maintaining constant RMS voltage application to the incandescent lamp.
Dependencies are inferred from the claim text.