Lamp ballast

• US 4,001,637 A
• Filed: 06/12/1975
• Issued: 01/04/1977
• Est. Priority Date: 06/12/1975
• Status: Expired due to Term

• Current Assignee: Lutron Electronics Company Incorporated (Lutron Electronics)
• Original Assignee: Lutron Electronics Company Incorporated (Lutron Electronics)
• Inventors: Gray, George W.
• Primary Examiner(s): La Roche, Eugene
• Application Number:
  US05/586,251
• Time in Patent Office: 572 Days
• Field of Search: 315/171, 315/194, 315/199, 315/200 R, 315/205, 315/DIG. 4, 315/DIG. 7, 315/227 R, 315/247
• US Class Current: 315/205
• CPC Class Codes: H05B 41/392 using semiconductor devices, e.g. thyristor
• CPC Class Codes: Y10S 315/07 Starting and control circuits for gas discharge lamp using transistors

Abstract

A ballast circuit for coupling a lamp to an AC power source and having in series between the source and lamp a non-dissipative current limiting capacitor feeding a rectifier, the output of the rectifier being connected to a smoothing filter. The ballast lends itself particularly to use in connection with a dimmer control, and permits the use of a secondary path or bypass around the dimmer control through another capacitor feeding a rectifier formed as a diode bridge, thereby providing a minimum current level path to the lamp.

Claims

1. For use in a circuit for coupling an electrical vapor lamp to a cyclic electrical power source, a ballast comprising in series:

first substantially non-inductive, non-dissipative, capacitive, current limiting means having an input couplable to said source;

rectifying means connected to the output of said current limiting means; and

filter means having an input connected to the output of said rectifying means, and an output connectable to said lamp.

2. A circuit as defined in claim 1 wherein said rectifying means is a full-wave diode bridge.

3. A circuit as defined in claim 1 wherein said filter means is a low-pass filter.

4. A circuit as defined in claim 1 including an input low-pass filter for coupling said first current limiting means to said source.

5. A circuit as defined in claim 1 including dimming control means for controlling input current to said ballast.

6. A circuit as defined in claim 5 wherein said dimming control means is connected to the input of said first current limiting means.

7. A circuit as defined in claim 6 wherein said first current limiting means comprises a plurality of non-dissipative elements, and said dimming control means comprises means for selectively coupling various of said elements to said power source.

8. A circuit as defined in claim 6 wherein said dimming control means comprises bidirectional controllable current conductive means for regulating current flow between said power source and said ballast in a first path, and means for controlling conduction through said current conductive device.

9. A circuit as defined in claim 8 wherein said controllable current conductive means comprises a semiconductor device and said means for controlling comprises phase control means.

10. A circuit as defined in claim 9 wherein said semiconductor device is a triac.

11. A circuit as defined in claim 8 including a second current conductive path between said power source and said ballast and second current limiting means for limiting current flow in said second path.

12. A circuit as defined in claim 11 wherein said second current limiting means is non-dissipative.

13. A circuit as defined in claim 11 wherein said second current limiting means is a capacitor.

14. A circuit as defined in claim 11 wherein said rectifying means comprises a full-wave flow diode bridge, said first path being connected to said bridge through said first current limiting means, said second path being connected to said bridge through a pair of unidirectional current conductive elements connected across said bridge.