Parallel plate structure provided with PZT thin-film bimorph and method of fabrication thereof

• US 6,262,516 B1
• Filed: 08/23/1999
• Issued: 07/17/2001
• Est. Priority Date: 07/04/1997
• Status: Expired due to Fees

• Current Assignee: Kabushiki Kaisha Tokai RIKA Denki Seisakusho
• Original Assignee: Kabushiki Kaisha Tokai RIKA Denki Seisakusho
• Inventors: Arai, Fumihito, Fukuda, Toshio, Iwata, Hitoshi, Itoigawa, Koichi
• Primary Examiner(s): Ramirez, Nestor
• Assistant Examiner(s): ADDISON, KAREN B
• Application Number:
  US09/380,014
• Time in Patent Office: 694 Days
• Field of Search: 310/328, 310/330, 310/331, 310/321
• US Class Current: 310/328
• CPC Class Codes: H10N 30/077 by liquid phase deposition
• CPC Class Codes: H10N 30/2043 connected at their free ends, e.g. parallelogram type

Abstract

A parallel plate structure (1) is provided with a pair of bimorph piezoelectric elements (2) and prismatic insulation spacers (3) inserted between the piezoelectric elements (2) at the upper and lower ends thereof for cementing the piezoelectric elements (2) together via the spacers (3). Each piezoelectric element (2) comprises a planar base material (4) of titanium, PZT thin films (5) formed on both sides of the base material (4) by the hydrothermal method, and electrode films (6) formed on the PZT thin films (5). The base material (4) is 20 μm thick and the PZT thin films (5) are several pm thick, while the aluminum electrode films (6) are several um thick.

Claims

1. A parallel plate structure including a pair of parallel bimorphs (2), and a spacer (3) for connecting the bimorphs (2), wherein each bimorph (2) has a titanium substrate (4), the titanium substrate (4) having a first surface and a second surface, which is located on the opposite side of the first surface, and a PZT thin-film (5) formed on each of the first and second surfaces, wherein the parallel plate structure is characterized by:

a plurality of spaced electrodes (6) formed on each PZT thin-film (5) and extending in the same direction.

2. The parallel plate structure according to claim 1 characterized in that the number of electrodes (6), which includes first and second electrodes (6), on each of the first and second surfaces is two.

3. The parallel plate structure according to claim 2 characterized in that the first electrode (6) extends from one end to a substantially middle portion of the associated PZT thin-film (5), and the second electrode (6) extends from the other end to the substantially middle portion of the associated PZT thin-film (5).

4. The parallel plate structure according to claim 1, characterized in that the PZT thin-film (5) is formed via a hydrothermal process.

5. The parallel plate structure according to claim 1, characterized in that the spacer (3) is arranged at one end of the bimorphs (2), and a further spacer (3) is arranged at the other end of the bimorphs (2), wherein both spacers (3) are insulating bodies.

6. A piezoelectric device, comprising:

a pair of parallel bimorphs, each bimorph including a substrate having a first surface and a second, opposing surface, and a PZT thin-film formed on each of the first and second surfaces;

a first spacer disposed between and connecting the bimorphs at a first end of the bimorphs; and

at least one electrode formed on each PZT thin-film.

7. The piezoelectric device of claim 6, wherein the substrate is made of titanium.

8. The piezoelectric device of claim 6, further comprising a second spacer disposed between and connecting the bimorphs at a second end, opposite the first end, of the bimorphs.

9. The piezoelectric device of claim 6, wherein the spacers are made from an insulating material.

10. The piezoelectric device of claim 6, wherein two electrodes are formed on each of the PZT thin-films.

11. The piezoelectric device of claim 10, wherein the two electrodes extend from opposing ends of the respective surface on which the thin-film is formed toward a center part of the surface.

12. The piezoelectric device of claim 11, wherein the electrodes are made of aluminum.