Head suspension and piezoelectric actuator

• US 20090086379A1
• Filed: 09/24/2008
• Published: 04/02/2009
• Est. Priority Date: 09/27/2007
• Status: Active Grant

• Current Assignee: NHK Spring Company Limited
• Original Assignee: NHK Spring Company Limited
• Inventors: Ando, Toshiki, Hanya, Masao
• Granted Patent: US 8,094,416 B2
• Time in Patent Office: Days
• US Class Current: 360/294.400
• CPC Class Codes: G11B 5/4833 Structure of the arm assembly, e.g. load beams, flexures, parts of the arm adapted for controlling vertical force on the head G11B5/484 takes precedence
• CPC Class Codes: G11B 5/4873 the arm comprising piezoelectric or other actuators for adjustment of the arm
• CPC Class Codes: G11B 5/5552 using fine positioning means for track acquisition separate from the coarse (e.g. track changing) positioning means
• CPC Class Codes: G11B 5/596 for track following on disks G11B5/5526, G11B5/5552, G11B5/5565, G11B5/5582 take precedence
• CPC Class Codes: H10N 30/206 using only longitudinal or thickness displacement, e.g. d33 or d31 type devices

Abstract

A head suspension with a piezoelectric element involves simple wiring and realizes high reliability, the head suspension has a base plate, a load beam connected to the base plate, a flexure attached to the load beam, and a piezoelectric actuator having a piezoelectric element arranged between the base plate and the load beam, the piezoelectric element is configured to deform according to a state of applied voltage and move a front end of the load beam in a sway direction according to the deformation, and the piezoelectric element has first and second piezoelectric parts that are oppositely polarized and deform according to a state of applied voltage, a common electrode formed over first surfaces of the first and second piezoelectric parts, a first electrode formed on a second surface of the first piezoelectric part, and a second electrode formed on a second surface of the second piezoelectric part.

Claims

1. A head suspension having a base plate, a load beam connected to the base plate, and a flexure attached to the load beam, the head suspension comprising:

a piezoelectric actuator arranged between the base plate and the load beam, the piezoelectric actuator having a piezoelectric element configured to deform according to a state of applied voltage and move a front end of the load beam in a sway direction according to the deformation of the piezoelectric, the piezoelectric actuator including;

first and second piezoelectric parts that are oppositely polarized and deform according to a state of applied voltage;

a common electrode formed over first surfaces of the first and second piezoelectric parts;

a first electrode formed on a second surface of the first piezoelectric part; and

a second electrode formed on a second surface of the second piezoelectric part.

2. The head suspension of claim 1, wherein:

the piezoelectric element substantially has a rectangular shape;

the first and second electrodes substantially have the same shape and size and are arranged side by side with a gap interposed between them;

the shape and size of the common electrode are substantially equal to the collective shape and size of the first and second electrodes and gap; and

the first and second piezoelectric parts are polarized so that their polarities are different from each other by 180 degrees.

3. The head suspension of claim 1, further comprising:

an actuator plate arranged between the base plate and the load beam;

an opening formed through the actuator plate; and

the piezoelectric element being arranged in the opening and attached to the actuator plate.

4. The head suspension of claim 3, wherein:

the common electrode of the piezoelectric element formed on the first surfaces of the first and second piezoelectric parts is in the vicinity of the flexure and the first and second electrodes formed on the second surfaces of the first and second piezoelectric parts are on the far side of the flexure; and

the piezoelectric element and the opening of the actuator plate are electrically isolated from each other with a nonconductive material interposed between them, the common electrode is electrically connected to wiring of the flexure, and the first and second electrodes are electrically connected to the actuator plate.

5. The head suspension of claim 1, further comprising:

an actuator plate arranged between the base plate and the load beam;

an opening formed through the actuator plate; and

the piezoelectric actuator bridged between edges of the opening.

6. The head suspension of claim 5, wherein:

the first and second electrodes formed on the second surfaces of the first and second piezoelectric parts are in the vicinity of the flexure and the common electrode of the piezoelectric element formed on the first surfaces of the first and second piezoelectric parts is on the far side of the flexure;

the first and second electrodes are attached to and electrically connected to the actuator plate; and

the common electrode is electrically connected to wiring of the flexure.

7. The head suspension of claim 1, further comprising:

a resilient connection plate configured to connect the load beam to the base plate; and

a hinge provided for the connection plate, the hinge being configured to bend in thickness directions of the base plate and load beam.

8. The head suspension of claim 1, further comprising:

a flexible part formed on each longitudinal side of the piezoelectric element between the base plate and the load beam, the flexible part outwardly protruding from the longitudinal side.

9. The head suspension of claim 1, wherein:

the common electrode entirely covers the first surfaces of the first and second piezoelectric parts.

10. A piezoelectric actuator for driving an object, comprising:

a piezoelectric element configured to deform according to a state of applied voltage and drive the object according to the deformation, the piezoelectric element including;

first and second piezoelectric parts that are oppositely polarized and deform according to a state of applied voltage;

a common electrode formed over first surfaces of the first and second piezoelectric parts;

a first electrode formed on a second surface of the first piezoelectric part; and

a second electrode formed on a second surface of the second piezoelectric part.

11. The piezoelectric actuator of claim 10, wherein:

the piezoelectric element substantially has a rectangular shape;

the first and second electrodes substantially have the same shape and size and are arranged side by side with a gap interposed between them;

the shape and size of the common electrode are substantially equal to the collective shape and size of the first and second electrodes and gap; and

the first and second piezoelectric parts are polarized so that their polarities are different from each other by 180 degrees.

12. The piezoelectric actuator of claim 10, wherein:

the common electrode entirely covers the first surfaces of the first and second piezoelectric parts.