Ballast unit for gas discharge lamps such as fluorescent tubes or the like

• US 3,949,268 A
• Filed: 03/14/1974
• Issued: 04/06/1976
• Est. Priority Date: 02/11/1971
• Status: Expired due to Term

• Current Assignee: Burkhard Von Mangoldt
• Original Assignee: Burkhard Von Mangoldt
• Inventors: Von Mangoldt, Burkhard
• Primary Examiner(s): Demeo, Palmer C.
• Application Number:
  US05/451,162
• Time in Patent Office: 754 Days
• Field of Search: 315/257, 315/188, 315/126, 315/239, 315/94, 315/DIG. 5, 315/254
• US Class Current: 315/239
• CPC Class Codes: H01F 27/40 Structural association with built-in electric component, e.g. fuse
• CPC Class Codes: H01F 38/10 Ballasts, e.g. for discharge lamps
• CPC Class Codes: H05B 41/232 for low-pressure lamps
• CPC Class Codes: Y10S 315/05 Starting and operating circuit for fluorescent lamp

Abstract

The disclosure relates to a ballast unit for gas discharge lamps, particularly fluorescent lamps, by which a substantially constant burning current is supplied to the lamp. The ballast unit includes a transformer mounted on a core having a defined air gap. The transformer is provided with a leakage inductance having a value resulting in a voltage drop of between approximately 15 and 30 percent of an input voltage applied thereto. One or more capacitors are connected in series with the transformer output supply to the lamp. The one or more capacitors provide a capacitance in series with the lamp substantially equal to the ratio of the burning current to the angular frequency of the input voltage multiplied by the secondary no-load voltage supplied to the secondary circuit.

Claims

1. A ballast unit for supplying a burning voltage and a substantially constant burning current to a secondary circuit including a gas discharge lamp, said ballast unit comprising:

a core of magnetic material having a defined air gap therein;

transformer windings carried by said core, said transformer windings including a primary and secondary winding both surrounding said core, said windings and said core with said defined air gap together forming a transformer, the total value of leakage inductance of said transformer being such that with an input voltage applied to said primary winding, the voltage drop across the leakage inductance is between approximately 15 and 30 percent of said input voltage; and

,

at least one capacitor connected in series between said secondary winding and said gas discharge lamp, said at least one capacitor having a capacitance substantially equal to the ratio of the burning current of the gas discharge lamp to the product of the angular frequency of the input voltage multiplied by a secondary no-load voltage supplied to the secondary circuit, said transformer having said leakage inductance and said capacitor having said capacitance being cooperable to define means automatically operable to supply said burning current to said gas discharge lamp at a substantially constant value substantially independently of fluctuations in said burning voltage.

2. A ballast unit according to claim 1 wherein the air gap is disposed in the zone of the secondary winding.

3. A ballast unit according to claim 1 wherein the core is constructed in elongated, rectangular form and has a winding space intermediate two generally parallel legs thereof, the length of the winding space being at least 51/2 times its width.

4. A ballast unit according to claim 3, wherein the primary and secondary windings are disposed on the same leg of the core in serial disposition.

5. A ballast unit according to claim 1 wherein all components are combined into a unified block by enclosure through a casting resin jacket and the block is provided with one or more externally accessible recesses for accommodating connecting elements.

6. A ballast unit according to claim 1 wherein one side of each of at least two capacitors is connected to one end of said secondary winding with the free ends of said capacitors being adapted for connection into the secondary circuit, the free ends of said capacitors together with the free end of the secondary winding providing at least two constant-current circuits connected in parallel to each other.

7. A ballast unit according to claim 6, wherein the secondary winding is divided into separate sections in accordance with the number of capacitors and each of the secondary winding sections is connected to a different one of said capacitors.

8. A ballast unit according to claim 7 wherein the capacitance of the capacitors is variable.

9. A ballast unit according to claim 8 wherein said transformer is enclosed by a housing and wherein at least one recess for connecting and safety devices is formed in the housing of the ballast unit.

10. A ballast unit according to claim 9 wherein the recess is provided with a cover, the removal of which results in interruption of the primary circuit.

11. A ballast unit according to claim 10 in which all components are combined into a unified casting resin jacket which forms said housing, the housing being provided with mounting brackets at each end thereof.

12. A ballast unit for a gas discharge lamp comprising:

first and second input terminals for receiving an a.c. input voltage from an input voltage source;

first and second output terminals for connecting said ballast unit to said gas discharge lamp and for supplying an output voltage thereto; and

,

means connected between said input and output terminals for supplying a burning current of a substantially constant value to said gas discharge lamp connected to said output terminals in response to said input voltage, said burning current being automatically maintained at said substantially constant value substantially independently of fluctuations in the burning voltage across said gas discharge lamp, said means comprising;

a transformer including a core of magnetic material having a defined air gap therein and a primary and a secondary winding both surrounding said core, said primary winding being operatively connected to said input terminals to receive said input voltage and one side of said secondary winding being operatively connected to one of said output terminals, said transformer having a total value of leakage inductance such that between 15 and 30 percent of the input voltage applied to the ballast unit is dropped across said leakage inductance; and

,

at least one capacitor connected in series between the other side of said secondary winding and the other of said output terminals, said at least one capacitor having a capacitance substantially equal to said value of the burning current of the gas discharge lamp divided by the product of the angular frequency of said input voltage and said output voltage supplied at said output terminals with no-load connected to said output terminals.