Energy Savings, Inc.

Energy Savings, Inc., a Delaware Corporation

Randy G Russell

Kent E Crouse

Peter W Shackle

Ronald J Bezdon

An electronic ballast includes an inverter producing pulses having a DC component, an output circuit connecting the filaments of one or more lamps in series, and a control circuit for detecting direct current through the filaments. The control circuit includes a capacitor charged by the DC component. When the voltage on the capacitor reaches a predetermined value, the ballast applies a high voltage to the lamps. The predetermined value is not reached unless a direct current passes from the output of the inverter through all lamp filaments to the capacitor. If a lamp filament is not intact, the inverter will not apply high voltage to the lamp.

Electronic ballast that monitors direct current through lamp filaments

An electronic ballast includes a converter coupled to a variable frequency inverter and a series resonant, parallel loaded output coupled to the inverter. The frequency of the inverter increases when the supply voltage from the converter decreases. The converter includes a full wave rectifier producing a first voltage and an unregulated boost circuit producing a second voltage which is combined with the first voltage to produce the supply voltage. The amount of boost, and therefore the magnitude of the supply voltage, is varied to provide dimming. Dimming is controlled mechanically, via a potentiometer, or electrically, via a control input. Dimming also occurs in response to changes in the first voltage, i.e. from changes in the voltage on an AC power line or from changes in the voltage provided by a capacitive dimmer coupled between the ballast and an AC power line.

Externally dimmable electronic ballast

An electronic ballast has a high voltage portion and a low voltage portion. The high voltage portion includes a converter, having a variable frequency boost circuit, and a half-bridge, driven inverter having a series resonant, direct coupled output. The low voltage portion of the ballast includes a control circuit and fault detectors for shutting off the boost circuit and the inverter circuit. The fault detectors consume very little power when the ballast and lamp are functioning normally. Separate magnetics are used for boost, inverter, and output. Each magnetic is essentially cubic in shape and carries as little current as possible.

Low height ballast for fluorescent lamps

An electronic ballast includes a boost circuit, a low voltage control circuit, and a driven inverter in a half-bridge, push-pull, series resonant, parallel loaded configuration. The boost circuit includes a low voltage output for powering the control circuit. In the event of a fault, the control circuit shuts off the boost circuit and the inverter. A sense capacitor is in series with the lamps and the voltage across the capacitor prevents a timer in the control circuit from shutting off the ballast. The timer circuit waits a period longer than the time it takes for the lamps to start normally. The sense capacitor is either in series with the lamp across the resonant capacitor or is in series with the resonant capacitor.

Capacitive lamp out detector

A lamp protective, electronic ballast includes a lamp voltage detector having a capacitor and resistor series connected across a discharge lamp. The junction of the resistor and capacitor is coupled to a voltage sensitive switch for detecting DC offset on the lamp and excessive AC voltage on the lamp. The switch is more sensitive to DC offset than to excessive AC voltage and is disabled while the lamp is started.

Lamp protective, electronic ballast

An electronic ballast includes a triggered boost circuit, a driven inverter, and a low voltage signal generator in a a half-bridge, push-pull, series resonant, parallel loaded configuration. The boost circuit is triggered by a voltage from the inverter and the inverter is controlled by the low voltage signal generator. The boost circuit includes a low voltage output for powering the signal generator. In the event of a fault, the operation of the signal generator is interrupted, thereby shutting off the boost circuit and the inverter. A DC blocking capacitor is in series with the lamps and a resistor is connected in parallel with the DC blocking capacitor. The ballast is started by a pulse of displacement current through the lamp filaments to the boost circuit. Since the lamp filaments must be intact, the ballast does not begin a lamp starting sequence until lamps are connected to the ballast.

Booster driven inverter ballast employing the output from the inverter

Power factor is increased and harmonic distortion is decreased in a boost circuit by varying the current drawn in phase with the ripple voltage from a rectifying bridge. The boost circuit includes a series connected inductor and switching transistor and the control electrode of the switching transistor is connected to a second inductor. The second inductor is magnetically coupled to the first inductor and provides feedback for sustaining high frequency oscillations in the boost circuit. A third inductor is magnetically coupled to the first and second inductors and to the control electrode of the switching transistor. The voltage from the third inductor is rectified and filtered to remove the high frequency pulses but not the ripple and the voltage is coupled to the control electrode of the switching transistor for changing the power consumed by said boost circuit in phase with the ripple.

Electronic Ballast with low harmonic distortion

A self-dimming electronic ballast for a gas discharge lamp includes a converter having an unregulated boost circuit coupled to a variable frequency inverter having a series resonant, parallel loaded output. The inverter includes a variable frequency driver circuit having a timing circuit for determining the frequency of the driver. A transistor in the timing circuit operates as an inverting amplifer and is controlled by a signal proportional to the voltage of the AC line. The frequency of the inverter increases with decreasing voltage on the AC line. The ballast can be on the same circuit as incandescent lamps and powered by a triac or variac dimmer for dimming both the incandescent and gas discharge lamps.

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Glen Ellyn, IL, United States of America

Randy G Russell