Tuned oscillator ballast circuit
AssigneeGTE Sylvania Incorporated
InventorIra Jay Pitel
Life of this patent
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Abstract
A fluorescent lamp ballast circuit includes a tuned oscillator coupled to a pulsed DC potential source and to a transformer having a first winding directly connected to the oscillator and in series connection with a capacitor to form a series resonant circuit. A second winding of the transformer inductively couples the first winding of the transformer to the oscillator, a third winding inductively couples a load across the capacitor of the series resonant circuit, and a fourth winding is inductively coupled to the first winding of the transformer and clamps the DC potential source to a given potential level. Also, protection for open circuits, short circuits, and temperature change due to changed ambient conditions or increased current flow is provided.
Claims13
A tuned oscillator ballast circuit comprising:
- a pulsed DC potential source;
- oscillator means coupled to said pulsed DC potential source;
- first inductive means including a first winding directly coupled to said oscillator means and in series connection with a charge storage means to form a series resonant circuit shunting said oscillator means;
- second inductive means including a second winding directly connected to said oscillator means to provide drive signals therefor;
- third inductive means including a third winding in shunt connection across said charge storage means of said series resonant circuit and coupled to lamp circuitry to form a load circuit;
- fourth inductive means including a fourth winding inductively coupled to said first inductive means and directly connected by a pair of diodes to said pulsed DC potential source to effect clamping thereof at a given potential level whereby said given potential level is maintained despite open circuiting of said load circuit and increased current flow through said charge storage means;
- and
- power factor correcting circuit means in the form of a capacitor shunting and an inductor coupling said pulsed DC potential source to an AC potential source.
A tuned oscillator ballast circuit comprising:
- an AC potential source;
- a bi-metal switch connected to said AC potential source;
- a DC rectifier means coupled to said AC potential source and to said bi-metal switch;
- oscillator means including first and second series connected transistors shunting said DC rectifier means;
- and
- transformer means coupled to said oscillator means, said transformer means including;
- a. a first inductive winding and a capacitor forming a series resonant circuit shunting said oscillator means;
- b. a second inductive winding inductively loosely coupled to said first inductive winding and directly coupled to said oscillator means;
- c. a third inductive winding shunt connected across said capacitor of said series resonant circuit, said winding coupled to a load circuit;
- and
- d. a fourth inductive winding inductively coupled to said first inductive winding, said fourth inductive winding having a center tap coupled to said oscillator circuit with opposing ends of said winding each coupled to a diode connected to said DC rectifier means to effect clamping of said output of said DC rectifier at a given potential level.
Dependencies are inferred from the claim text.