Circuit for powering fluorescent lamps

• US 4,008,414 A
• Filed: 07/28/1975
• Issued: 02/15/1977
• Est. Priority Date: 07/28/1975
• Status: Expired due to Term

• Current Assignee: Power Saver Corporation
• Original Assignee: Power Saver Corporation
• Inventors: Agnew, Donald L.
• Primary Examiner(s): LaRoche, Eugene R.
• Application Number:
  US05/599,378
• Time in Patent Office: 568 Days
• Field of Search: 315/94, 315/95, 315/97, 315/100, 315/101, 315/105, 315/119, 315/121, 315/122, 315/125, 315/189, 315/210, 315/312, 315/324, 315/DIG. 5, 315/DIG. 7, 339/57, 240/51.11 R
• US Class Current: 315/97
• CPC Class Codes: H05B 41/2855 against abnormal lamp operating conditions
• CPC Class Codes: H05B 41/2988 for protecting the lamp against abnormal operating conditions
• CPC Class Codes: Y10S 315/07 Starting and control circuits for gas discharge lamp using transistors

Abstract

A circuit employing an oscillator having a feedback loop for supplying operating current at a frequency in the range 20-25 kilohertz to a pair of fluorescent lamps connected in series. The heater filament of the first lamp is made a series element in the feedback loop of the oscillator, so that removal of that lamp disables the oscillator. Switching means is provided to bypass the open socket terminals of the second lamp when it is removed from its sockets, permitting power to continue to be supplied to the first lamp.

Claims

1. Apparatus for powering first and second fluorescent lamps connected in series, said lamps each having a starter heater filament, comprising:

a. a pair of sockets associated with each lamp, each socket having a terminal for making electrical connection to a lamp, with one of the terminals associated with each lamp connected in common;

b. an oscillator including two output terminals each of which is connected to the terminal of a socket associated with a different lamp but not to the terminals connected in common, and further including a feedback circuit including means for connecting a starter heater filament of the first lamp in series within the feedback circuit, whereby removal of the first lamp from its sockets disables said oscillator; and

c. switching means for establishing a short circuit between the socket terminals of the second lamp when the lamp is removed from its sockets, whereby the socket terminals of the socket lamp are bypassed permitting power to continue to be applied to the socket terminals of the first lamp after the second lamp has been removed from its sockets.

2. The apparatus of claim 1 wherein said oscillator has an operating frequency in the range 20-25 kilohertz.

3. The apparatus of claim 1 wherein said oscillator is connected to a distribution system for supplying power to the fluorescent lamps at a distance, whereby lower voltage wiring may be used in the distribution system at a savings in cost.

4. The apparatus of claim 1 wherein said switching means is located in one of said lamp sockets.

5. The apparatus of claim 1 wherein said switching means comprises a contact yieldingly urged closed by resilient force when not normally held apart by a portion of a fluorescent lamp when the lamp is mounted in its sockets, whereby removal of the lamp from its sockets causes the contacts to close.

6. The apparatus of claim 1 wherein said oscillator is powered by a direct current power source.

7. The apparatus of claim 1 wherein said oscillator is a relaxation oscillator.

8. The apparatus of claim 7 wherein said relaxation oscillator is a blocking oscillator.

9. The apparatus of claim 1 in which said oscillator further includes converter means adapting said oscillator to be powered by a primary power source.

10. The apparatus of claim 9 wherein said converter means includes a rectifier circuit for providing direct current power to said oscillator from an alternating primary power source.

11. The apparatus of claim 9 wherein said converter means further include dimmer means for controlling the amount of power supplied to the fluorescent lamps whereby the fluorescent lamps may be operated at a reduced power level.

12. The apparatus of claim 9 wherein said oscillator and said converter means occupy the space normally used for a ballast element in a conventional fluorescent lamp fixture.

13. The apparatus of claim 9 wherein said converter means and said oscillator are included within a common enclosure.

14. In a circuit employing an oscillator circuit having a feedback loop for supplying operating current at a frequency in the range 20 to 25 kilohertz to a pair of fluorescent lamps connected in series, normally mounted in sockets, and having starter heater filaments, the improvement comprising:

a. means for connecting a starter heater filament of a first lamp in series within the feedback loop of the oscillator circuit, whereby removal of the first lamp from its sockets disables the oscillator circuit; and

b. switching means for establishing a short circuit between the socket terminals of the second lamp when that lamp is removed from its sockets, whereby the socket terminals of the second lamp are bypassed permitting power to continue to be applied to the socket terminals of the first lamp after the second lamp has been removed from its sockets.