Power supply apparatus, an electronic ballast using the power supply, and a self-ballasted fluorescent lamp

• US 20020017878A1
• Filed: 01/29/2001
• Published: 02/14/2002
• Est. Priority Date: 01/27/2000
• Status: Active Grant

• Current Assignee: Toshiba Lighting & Technology Corporation (Toshiba Corporation)
• Original Assignee: Toshiba Lighting & Technology Corporation (Toshiba Corporation)
• Inventors: Hakuta, Shinya, Osaki, Hajime
• Granted Patent: US 6,437,516 B2
• Time in Patent Office: Days
• US Class Current: 315/291
• CPC Class Codes: H05B 41/2827 using specially adapted components in the load circuit, e.g. feed-back transformers, piezoelectric transformers; using specially adapted load circuit configurations
• CPC Class Codes: Y02B 20/00 Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps

Abstract

A power supply apparatus includes a direct current power supply having a pair of terminals. First and second switching elements are connected in series between the pair of terminals of the direct current power. A load circuit, which includes a resonance inductance and a resonance capacitance, receives a high-frequency alternating current generated by a switching of the first and second switching elements. An unsaturated transformer has a first winding connected to the load circuit, and a second winding generating an induced voltage in proportion to a current flowing in the load circuit. A drive resonance circuit includes a capacitance, and an inductance of the second winding. The drive resonance circuit produces a resonance output to cause the first and second switching elements to alternately conduct. The power supply may be used in a ballast for a discharge lamp.

Claims

1. A power supply apparatus comprising:

a direct current power supply having a pair of terminals;

first and second switching elements connected in series between said pair of terminals of said direct current power;

a load circuit, which includes a resonance inductance and a resonance capacitance, receiving a high-frequency alternating current generated by the switching of said first and second switching elements;

an unsaturated transformer having a first winding connected to said load circuit, and a second winding generating an induced voltage in proportion to a current flowing in said load circuit; and

a drive resonance circuit including a capacitance, and an inductance of said second winding, and producing a resonance output which is applied to said first and second switching elements to cause said first and second switching elements to alternately conduct.

2. A power supply apparatus according to claim 1, wherein an inductance of said first winding of said unsaturated transformer is less than that of said resonance inductance of said load circuit.

3. A power supply apparatus according to claim 2, wherein a ratio Ln2/Ln1 of said unsaturated transformer is 100 or more, wherein said Ln2 is an inductance of said second winding of said unsaturated transformer, and said Ln1 is an inductance of said first winding.

4. A power supply apparatus according to claim 2 or 3, wherein a ratio Ln2δ

/Ln2[UNIT?] of said unsaturated transformer is 0.5 or more, and said Ln2δ

is an equivalent inductance existing in said second winding equivalently, when said first winding is shorted.

5. A power supply apparatus as in claim 1, 2 or 3, in which said first and second switching elements are complementary MOSFET switching elements.

6. A power supply apparatus as in claim 1, 2 or 3, in which said capacitance of said drive resonance circuit comprises a gate-to-source capacitance.

7. A power supply apparatus as in claim 1, 2 or 3, in which said switching elements are field effect transistors and a capacitance of said drive resonance circuit comprises a gate-to-source capacitance of said switching elements.

8. An electronic ballast using a power supply comprising:

a power supply apparatus comprising;

a direct current power supply having a pair of terminals,

first and second switching elements connected in series between said pair of terminals of said direct current power,

a load circuit, which includes a resonance inductance and a resonance capacitance, receiving a high-frequency alternating current generated by a switching of said first and second switching elements,

an unsaturated transformer having a first winding connected to said load circuit, and a second winding generating an induced voltage in proportion to a current flowing in said load circuit, and

a drive resonance circuit including a capacitance, and an inductance of said second winding, and producing a resonance output which is applied to said first and second switching elements to cause said first and second switching elements to alternately conduct; and

a discharge lamp connected to said load circuit.

9. A self-ballasted discharge lamp comprising:

an electronic ballast using a power supply comprising;

a power supply apparatus comprising;

a direct current power supply having a pair of terminals,

first and second switching elements connected in series between said pair of terminals of said direct current power,

a load circuit, which includes a resonance inductance and a resonance capacitance, receiving a high-frequency alternating current generated by a switching of said first and second switching elements,

an unsaturated transformer having a first winding connected to said load circuit, and a second winding generating an induced voltage in proportion to a current flowing in said load circuit, and

a drive resonance circuit including a capacitance, and an inductance of said second winding, and producing a resonance output which is applied to said first and second switching elements to cause said first and second switching elements to alternately conduct;

a discharge lamp connected to said load circuit; and

an enclosure accommodating said discharge lamp and said electronic ballast.