High-power electronic ballast for fluorescent lamp

• US 6,600,273 B2
• Filed: 08/06/2001
• Issued: 07/29/2003
• Est. Priority Date: 12/23/2000
• Status: Expired due to Fees

• Current Assignee: Samsung Electro-Mechanics Co., Ltd. (Samsung Group)
• Original Assignee: Samsung Electro-Mechanics Co., Ltd. (Samsung Group)
• Inventors: Jung, Jong-Man, Yoo, Choong-Sik, Kim, Jong-Sun
• Primary Examiner(s): VU, DAVID HUNG
• Application Number:
  US09/921,600
• Publication Number:
  US 20020140375A1
• Time in Patent Office: 722 Days
• Field of Search: 315/224, 315/209.PZ, 315/247, 310/316.01
• US Class Current: 315/247
• 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

Abstract

Disclosed is a high-power ballast inexpensively applicable to a fluorescent lamp of the 28-Watt class without any increase in the number of constituent elements used or any complexity in the manufacturing process. The high-power ballast includes a rectifier circuit for rectifying a low-frequency AC voltage to convert it into a direct current DC voltage, a power factor compensation circuit for compensating a power factor for the voltage outputted from the rectifier circuit, thereby boosting the level of the output voltage, the power factor compensation circuit including an active type power factor driver, and an inverter circuit for converting the DC voltage, outputted from the power factor compensation circuit, into a desired high-frequency AC voltage. The inverter circuit includes an inverter, a resonator circuit connected to the inverter, and a high-power piezoelectric transformer having an input terminal connected to the resonator circuit and an output terminal connected to the fluorescent lamp. The high-power piezoelectric transformer is made of a composition expressed by the following chemical formula: ${\mathrm{Pb}}_{1-a}{\mathrm{Sr}}_a\left[{\left({\mathrm{Ni}}_{\frac{1}{2}}W_{\frac{1}{2}}\right)}_b{\left({\mathrm{Mn}}_{\frac{1}{3}}{\mathrm{Nb}}_{\frac{2}{3}}\right)}_c{\left({\mathrm{Zr}}_{1-x}{\mathrm{Ti}}_x\right)}_{1-b-c}\right]O_3+\mathrm{kPbO}.$

The high-power piezoelectric transformer serves to apply, as a drive voltage, the high-frequency AC voltage to the fluorescent lamp and includes a substantially rhombic input electrode centrally formed on each of upper and lower surfaces of a piezoelectric body block and adapted as the input terminal.

Claims

1. A high-power ballast for a high-power fluorescent lamp adapted to supply a drive voltage to the fluorescent lamp said ballast, comprising:

a rectifier circuit for rectifying a low-frequency AC voltage to convert the AC voltage into a direct current (DC) voltage;

a power factor compensation circuit for compensating a power factor for the voltage outputted from the rectifier circuit, thereby boosting the level of the output voltage, the power factor compensation circuit including an active type power factor driver; and

an inverter circuit for converting the DC voltage, outputted from the power factor compensation circuit, into a desired high-frequency AC voltage, the inverter circuit including an inverter, a resonator circuit connected to the inverter, and a high-power piezoelectric transformer having an input terminal connected to the resonator circuit and an output terminal connected to the fluorescent lamp, the high-power piezoelectric transformer serving to apply, as the drive voltage, the high-frequency AC voltage to the fluorescent lamp, said piezoelectric transformer including

a substantially hexahedral piezoelectric body block,

a substantially rhombic input electrode centrally formed on each of upper and lower surfaces of the piezoelectric body block, the input electrode serving as the input terminal, and

an output electrode formed on each of the upper and lower surfaces of the piezoelectric body block so as to surround the input electrode while being spaced apart from the input electrode by a desired distance, the output electrode serving as the output terminal.

2. The ballast set forth in claim 1, wherein the high-power piezoelectric transformer is made of a composition expressed by the following chemical formula:

${\mathrm{Pb}}_{1-a}<br><br>{\mathrm{Sr}}_a<br><br>\left[{\left({\mathrm{Ni}}_{\frac{1}{2}}<br><br>W_{\frac{1}{2}}\right)}_b<br><br>{\left({\mathrm{Mn}}_{\frac{1}{3}}<br><br>{\mathrm{Nb}}_{\frac{2}{3}}\right)}_c<br><br>{\left({\mathrm{Zr}}_{1-x}<br><br>{\mathrm{Ti}}_x\right)}_{1-b-c}\right]<br><br>O_3+\mathrm{kPbO}.$

3. The ballast set forth in claim 2, wherein, in the chemical formula, a is in a range of 0˜

0.06 mol, b is in a range of 0.01˜

0.05 mol, c is in a range of 0.01˜

0.09 mol, x is in a range of 0.47˜

0.53 mol, and k is in a range of 0.1˜

0.7 wt %.

4. The ballast as set forth in claim 1, wherein the high-power piezoelectric transformer is operated at 66 KHz.

5. A high-power ballast adapted to supply a drive voltage to a high-power fluorescent lamp, said ballast comprising:

a rectifier circuit for rectifying a low-frequency AC voltage to convert the low-frequency AC voltage into a direct current (DC) voltage;

a power factor compensation circuit coupled to said rectifier circuit for maintaining the DC voltage outputted from said rectifier at a constant level, the power factor compensation circuit including an active type power factor driver; and

an inverter circuit coupled to said power factor compensation circuit for performing a switching operation to convert a power factor-compensated DC voltage received from said power factor compensation circuit into a high-frequency AC voltage;

wherein the inverter circuit includes an inverter, a resonator circuit connected to the inverter, and a high-power piezoelectric transformer having an input terminal connected to the resonator circuit and an output terminal adapted to be connected to the fluorescent lamp for supplying the fluorescent lamp with the high-frequency AC voltage as the drive voltage; and

wherein said high-power piezoelectric transformer is made of a composition expressed by the following chemical formula;

${\mathrm{Pb}}_{1-a}<br><br>{\mathrm{Sr}}_a<br><br>\left[{\left({\mathrm{Ni}}_{\frac{1}{2}}<br><br>W_{\frac{1}{2}}\right)}_b<br><br>{\left({\mathrm{Mn}}_{\frac{1}{3}}<br><br>{\mathrm{Nb}}_{\frac{2}{3}}\right)}_c<br><br>{\left({\mathrm{Zr}}_{1-x}<br><br>{\mathrm{Ti}}_x\right)}_{1-b-c}\right]<br><br>O_3+\mathrm{kPbO}.$

6. The ballast of claim 5, wherein, in the chemical formula, a is in a range of 0˜

0.06 mol, b is in a range of 0.01˜

0.05 mol, c is in a range of 0.0˜

0.09 mol, x is in a range of 0.47˜

0.53 mol, and k is in a range of 0.1˜

0.7 wt %.

7. The ballast of claim 5, wherein said piezoelectric transformer includes

a substantially hexahedral piezoelectric body block;

a substantially rhombic input electrode centrally formed on each of upper and lower surfaces of the piezoelectric body block, the input electrode serving as the input terminal, and

an output electrode formed on each of the upper and lower surfaces of the piezoelectric body block so as to surround the input electrode while being spaced apart from the input electrode by a predetermined distance, the output electrode serving as the output terminal.

8. The ballast of claim 7, wherein each of the output electrodes of said piezoelectric transformer completely encircles the respective input electrode.

9. The ballast of claim 8, wherein the input electrodes of said piezoelectric transformer are coupled to output terminals of said resonance circuit for applying said high-frequency AC voltage to said piezoelectric body, and the output electrodes of said piezoelectric transformer are adapted to be coupled to the lamp.

10. The ballast of claim 5, wherein said piezoelectric transformer includes

a piezoelectric body having opposite first and second faces;

at least a first input electrode formed on said first face of said piezoelectric body; and

at least a first output electrode formed on said first face of said piezoelectric body, said first output electrode surrounding, while being spaced from, the first input electrode.

11. The ballast of claim 10, wherein said piezoelectric body is a piezoelectric block;

said first input electrode is disposed closer to a central region of each side of said first face than to a corner region on said first face, the input electrode serving as the input terminal; and

said first output electrode is separated from the first input electrode by a constant distance at a peripheral region on said first face so that a size of said first output electrode at the central region of each side of said first face is smaller than at the corner region of said first face, the first output electrode serving as the output terminal.

12. The ballast of claim 11, wherein said piezoelectric transformer further includes

a second input electrode formed on said second face of said piezoelectric body;

and

a second output electrode formed on said second face of said piezoelectric body, said second output electrode surrounding, while being spaced from, the second input electrode;

wherein the second input electrode is disposed closer to a central region of each side of said second face than to a corner region on said second face; and

the second output electrode is separated from the second input electrode by a constant distance at a peripheral region on said second face so that a size of said second output electrode at the central region of each side of said second face is smaller than at the corner region of said second face.

13. The ballast of claim 5, wherein said high-power piezoelectric transformer operates at 66 KHz.