Thin layer composite unimorph ferroelectric driver and sensor

• US 5,632,841 A
• Filed: 04/04/1995
• Issued: 05/27/1997
• Est. Priority Date: 04/04/1995
• Status: Expired due to Term

• Current Assignee: Face International Corp.
• Original Assignee: United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration
• Inventors: Fox, Robert L., Bryant, Robert G., Hellbaum, Richard F.
• Primary Examiner(s): Ball, Michael W.
• Assistant Examiner(s): Lorin, Francis J.
• Application Number:
  US08/416,598
• Time in Patent Office: 784 Days
• Field of Search: 156/160, 156/163, 156/165, 156/245, 29/25.35, 310/330, 310/331, 310/332, 310/340, 310/345, 310/367, 310/369, 310/370, 310/371, 310/311, 264/229
• US Class Current: 156/245
• CPC Class Codes: B32B 37/144 using layers with different mechanical or chemical conditions or properties, e.g. layers with different thermal shrinkage, layers under tension during bonding constructional features for tensioning B32B38/1825
• CPC Class Codes: H10N 30/073 by fusion of metals or by adhesives
• CPC Class Codes: H10N 30/204 using bending displacement, e.g. unimorph, bimorph or multimorph cantilever or membrane benders
• CPC Class Codes: H10N 30/2048 having non-planar shape
• CPC Class Codes: Y10T 29/42 Piezoelectric device making

Abstract

A method for forming ferroelectric wafers is provided. A prestress layer is placed on the desired mold. A ferroelectric wafer is placed on top of the prestress layer. The layers are heated and then cooled, causing the ferroelectric wafer to become prestressed. The prestress layer may include reinforcing material and the ferroelectric wafer may include electrodes or electrode layers may be placed on either side of the ferroelectric layer. Wafers produced using this method have greatly improved output motion.

Claims

1. A method for producing ferroelectric devices, comprising:

selecting a mold for the device;

placing a prestress layer on the mold;

placing a ferroelectric layer on the prestress layer to create layer structure;

heating the prestress and ferroelectric layers; and

cooling the prestress and ferroelectric layers whereby the heating and cooling steps induce a prestress into the layered structure.

2. The method of claim 1 wherein the prestress layer includes reinforcing material.

3. The method of claim 1 wherein the ferroelectric layer includes surface electrodes.

4. The method of claim 1 further comprising:

placing a first electrode layer between the prestress layer and the ferroelectric layer; and

placing a second electrode layer on top of the ferroelectric layer.

5. The method of claim 1 wherein the prestress layer is an adhesive.

6. The method of claim 1 wherein the ferroelectric layer is a piezoelectric material.

7. The method of claim 1 wherein the ferroelectric layer is a piezostrictive material.

8. The method of claim 1 wherein the ferroelectric layer is formed from a composite.