Porous piezoelectric ceramic sheet and piezoelectric transducer

• US 6,111,339 A
• Filed: 08/12/1999
• Issued: 08/29/2000
• Est. Priority Date: 08/12/1998
• Status: Expired due to Term

• Current Assignee: Ueda Japan Radio Co., Ltd. (Nisshinbo Holdings Incorporated)
• Original Assignee: Ueda Japan Radio Co., Ltd. (Nisshinbo Holdings Incorporated)
• Inventors: Ohya, Shigemasa, Nishio, Norihiro, Sekimori, Kenji
• Primary Examiner(s): BUDD, MARK OSBORNE
• Application Number:
  US09/373,332
• Time in Patent Office: 383 Days
• Field of Search: 310/358, 310/359, 310/311, 310/366, 252/62.9
• US Class Current: 310/358
• CPC Class Codes: H10N 30/853 Ceramic compositions

Abstract

A thin porous piezoelectric Pb(Zr,Ti)O₃ ceramic sheet having a thickness of 0.05 to 2 mm which is favorably employable for manufacturing a piezoelectric transducer has small pores essentially all of which have a size of less than 25 μm in which pores having a size of 5 to 25 μm have a mean pore size of 1/10 to 1/1,000 based on the thickness of the ceramic sheet, and which shows a ratio of apparent density to true density in the range of 5/10 to 9/10.

Claims

1. A porous piezoelectric ceramic sheet having a thickness in the range of 0.05 to 2 mm and comprising Pb(Zr,Ti)O₃, which has pores essentially all of which have a size of less than 25 μ

m in which pores having a size in the range of 5 to 25 μ

m have a mean pore size in the range of 1/10 to 1/1,000 based on the thickness of the ceramic sheet, and which shows a ratio of apparent density to true density in the range of 5/10 to 9/10.

2. The porous piezoelectric ceramic sheet of claim 1, wherein the thickness of the ceramic sheet is in the range of 0.1 to 2 mm.

3. The porous piezoelectric ceramic sheet of claim 1, wherein the pores having a size in the range of 5 to 25 μ

m have a mean pore size in the range of 1/10 to 1/100 based on the thickness of the ceramic sheet.

4. The porous piezoelectric ceramic sheet of claim 1, wherein essentially all of the pores have a size of less than 15 μ

m.

5. The porous piezoelectric ceramic sheet of claim 4, wherein pores having a size in the range of 5 to 15 μ

m have a mean pore size in the range of 1/10 to 1/50 based on the thickness of the ceramic sheet.

6. The porous piezoelectric ceramic sheet of claim 1, wherein the apparent density is in the range of 5.0 to 6.5 g/cm³.

7. A piezoelectric transducer which is manufactured by the steps of placing an electrode on each surface side of a porous piezoelectric ceramic sheet of claim 1, and applying a voltage between the electrodes to cause polarization in the ceramic sheet.

8. A piezoelectric transducer which is manufactured by the steps of placing an electric insulating coat on each surface side of a porous piezoelectric ceramic sheet of claim 1, placing an electrode on each electric insulating coat, and applying a voltage between the electrodes to cause polarization in the ceramic sheet.

9. An array of piezoelectric transducers comprising a plurality of piezoelectric transducers of claim 7 which are aligned adjacently to each other.

10. An array of piezoelectric transducers comprising a plurality of piezoelectric transducers of claim 8 which are aligned adjacently to each other.