Method and apparatus for saving energy
AssigneeLear Siegler, Inc.
InventorsGene B. Potter, Martin H. Jurick
Life of this patent
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Abstract
A method and apparatus for regulating the output flux generated by a lamp with the degeneration of the voltage from a power source such as a battery. The regulating circuit maintains a constant luminous flux output from a lamp over a substantial range of voltages by switching the voltage to the lamp on and off at a preselected and controlled duty cycle. The power pulses applied to the lamp have heights that vary directly as the voltage variations of the power source and widths that vary as the inverse square of the voltage from the power source for maintaining a constant RMS voltage on the lamp and thereby constant light output flux.
Claims12
Apparatus for maintaining a substantially constant RMS voltage across a load device powered from a power source having a decreasing output voltage with time comprising
- means adapted to be coupled to said power source in parallel circuit relationship for providing a reference output voltage signal that has an inverse relationship to the voltages of the power source and with a substantially constant slope,
- a serial resistor-capacitor network having a junction between the resistor and capacitor and adapted to be coupled to said power source in parallel circuit relationship therewith to permit the capacitor to be exponentially charged from said source through the resistor,
- first switching circuit means adapted to be coupled to said power source through said serial resistor and including a parallel circuit path connected to opposite sides of the capacitor and being normally arranged in a nonconductive condition and to be automatically rendered conductive at preselected time intervals for discharging the capacitor by means of the parallel circuit path during the conductive time intervals of the parallel circuit path, the time intervals the parallel circuit path is conductive is short relative to the nonconductive time intervals, pulse generating means adapted to be coupled to said power source for generating pulses of a preselected repetition rate and a preselected short pulse width and being coupled to said first switching circuit means for rendering said conductive in response thereto,
- comparison circuit means coupled to be responsive to said reference output signal and to the signals at the junction between the resistor and the capacitor for periodically providing output pulses having pulse widths that vary as the inverse square of the output voltages from said source only when the signals at said junction are less than the amplitude of the reference output signals, and
- second switching circuit means coupled to be responsive to the output pulses from said comparison circuit means to be rendered conductive thereby for the time duration of said output pulses, and a load device adapted to be coupled to said power source to be powered therefrom through the second switching circuit means during the time intervals the second switching means is rendered conductive in response to said output pulses.
Apparatus for maintaining a substantially constant RMS voltage across a load device powered from a power source having a decreasing output voltage with time comprising
- means adapted to be coupled to said power source for generating pulses having a preselected repetition rate and pulse width,
- means adapted to be coupled to said power source for providing a reference voltage having an inverse relationship to the voltages of said source with a substantially constant slope,
- a resistance-capacitance network adapted to be coupled across the power source for exponentially charging the capacitor therefrom;
- switching means coupled to be responsive to the pulse generating means to be rendered conductive in response to a pulse coupled thereto, said switching means being coupled in parallel circuit relationship with the capacitor to provide a circuit path for discharging the capacitor during the conductive intervals of the switching means and thereby permitting the capacitor to be charged during the nonconducting intervals of the switching means, the charging and discharging of the capacitor providing an oscillating signal having amplitudes that vary with the decreasing output voltages of the power source and exhibiting reversals in direction regularly and continuously and with the amplitudes varying about the voltage level of the reference voltages,
- comparison circuit means coupled to be responsive to the output signals derived from the capacitor and from the reference voltage generator for providing output pulses having pulse widths that vary as the inverse square of the output voltages,
- switching means coupled to be conductively responsive to said output pulses for the time duration of the pulses for applying pulses to a load to be energized therefrom, and
- a load device adapted to be coupled to the power source to be powered therefrom and in series circuit relationship with said last mentioned means to be energized from the power source during the conductive time intervals of said switching means.
Apparatus for maintaining a substantially constant RMS voltage across a lamp powered from a power source having a decreasing output voltage with time, comprising
- voltage reference generating means comprising a current mirror device adapted to be coupled to said power source for providing an output signal having an inverse voltage relationship with the voltages from said power source,
- energy storage means adapted to be coupled to said source to be charged therefrom,
- a lamp adapted to be coupled to the source to be energized therefrom,
- switching circuit means coupled to said energy storage means for periodically discharging said energy storage means at a preselected fixed switching rate to thereby provide an oscillating signal from said storage means,
- means for sensing the relative amplitudes of the output signal from said voltage reference means and said oscillating signal from said storage means for switchably coupling the power source to the lamp for regulating the luminous flux output of the lamp to maintain the flux output substantially constant over a range of voltages capable of sustaining the constant flux by switching the power source to the lamp on and off at a preselected rate, the pulses being proportioned in height and width for maintaining a substantially constant RMS voltage value on the lamp.
Apparatus for maintaining a substantially constant RMS voltage across a lamp as defined in claim 18 wherein the power source is substantially coupled to the lamp at a rate so that the period between pulses is short relative to the thermal lag of the lamp filament for avoiding filament temperature and resistance variations.
Dependencies are inferred from the claim text.