Electric lamp and discharge devices: systems – Current and/or voltage regulation
Patent
1981-03-23
1983-04-05
LaRoche, Eugene R.
Electric lamp and discharge devices: systems
Current and/or voltage regulation
315199, 315307, 315DIG4, 323243, H05B 41392
Patent
active
043792545
ABSTRACT:
An intensity control for fluorescent lamps of the type wherein a triac in series with the lamp provides control of the lamp current. Triac gating is controlled by a novel phase-lock circuit. In the phase-lock circuit, voltage squaring means are provided for producing unipolar square waves having a pulse width equal to a corresponding half cycle of the a.c. input power. Ramp waves generated from the square waves are applied to the base of a PNP transistor. Current through the lamp is sampled and produces a proportional voltage signal which is superimposed on a parallel path of the square waves to create a phase reference signal. An intensity control potentiometer supplies a selectable d.c. intensity control signal of polarity opposite the phase reference signal, and the intensity control signal and phase reference signal are algebraically added together. The resultant signals apply to the inverting input of integrating amplifier which reverses the polarity and integrates the resultant signal. The integrated signal is also connected to the base of the PNP transistor. The PNP transistor conducts when the combined voltage of the ramp signals and integrated signals fall below zero potential. When the transistor conducts, a circuit is completed supplying a control signal to the gate of the triac.
REFERENCES:
patent: 3793557 (1974-02-01), Cramer
patent: 3863102 (1975-01-01), Herzog
patent: 3873910 (1975-03-01), Willis, Jr.
patent: 3875458 (1975-04-01), Kappenhagen
patent: 3890562 (1975-06-01), West
patent: 4037148 (1977-07-01), Owens et al.
patent: 4039897 (1977-08-01), Dragoset
patent: 4052648 (1977-10-01), Nola
D'Orio Andrew L.
LaRoche Eugene R.
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