Sensing unit and method of making same

• US 20080314146A1
• Filed: 06/20/2007
• Published: 12/25/2008
• Est. Priority Date: 06/20/2007
• Status: Active Grant

• Current Assignee: Headway Technologies Incorporated, SAE Magnetics Limited (TDK Corporation)
• Original Assignee: Headway Technologies Incorporated, SAE Magnetics Limited (TDK Corporation)
• Inventors: Ishizaki, Kazuo, Sasaki, Yoshitaka, Horinaka, Takehiro, Tanemura, Shigeki, Shimizu, Tatsushi
• Granted Patent: US 7,628,071 B2
• Time in Patent Office: Days
• US Class Current: 73/514.01
• CPC Class Codes: G01P 15/0802 Details
• CPC Class Codes: G01P 15/12 by alteration of electrical resistance G01P15/0897, G01P15/105 take precedence
• CPC Class Codes: G01P 15/123 by piezo-resistive elements, e.g. semiconductor strain gauges
• CPC Class Codes: Y10T 29/49002 Electrical device making

Abstract

In a sensing unit according to the present invention, a movable portion of a spring portion is supported floatably above a recessed portion formed in a substrate. Thus, the movable portion is capable of oscillating in any direction parallel to the substrate surface. Moreover, the movable portion is capable of oscillating in the thickness direction of the substrate such that the amplitude of a center side end portion thereof reaches a maximum. A sensor portion is provided on the movable portion. As a result, the sensing unit according to the present invention has a higher degree of freedom in terms of the measurement direction than a conventional sensing unit that oscillates in only one direction.

Claims

1. A sensing unit comprising:

a substrate formed with a recessed portion;

a spring portion having a support portion positioned on an edge portion of said recessed portion and a flat coil-shaped movable portion positioned above said recessed portion and supported floatably by said support portion; and

a sensor portion provided on said movable portion of said spring portion, for detecting displacement in said movable portion.

2. The sensing unit according to claim 1, wherein said spring portion is formed from a conductive material.

3. The sensing unit according to claim 1, wherein said spring portion is formed by plating.

4. The sensing unit according to claim 1, wherein said sensor portion is constituted by a GMR sensor.

5. The sensing unit according to claim 1, wherein a weighted portion is formed on a center side end portion of said movable portion of said spring portion.

6. The sensing unit according to claim 1, wherein said sensor portion is provided on said movable portion in a position near said support portion.

7. The sensing unit according to claim 1, wherein a plurality of said sensor portions are provided on said movable portion.

8. The sensing unit according to claim 1, wherein said substrate is held so as to extend in a vertical direction.

9. The sensing unit according to claim 1, wherein said substrate is held so as to extend in a horizontal direction.

10. A method of making a sensing unit having:

a substrate formed with a recessed portion;

a spring portion having a support portion positioned on an edge portion of said recessed portion and a flat coil-shaped movable portion positioned above said recessed portion and supported floatably by said support portion; and

a sensor portion provided on said movable portion of said spring portion, for detecting displacement in said movable portion,

said method comprising the steps of;

burying said recessed portion formed in said substrate with a resist layer to make said recessed portion flat;

forming a plating layer that is to become said spring portion such that a part that is to become said support portion is positioned on said edge portion of said recessed portion and a part that is to become said movable portion is positioned on said resist layer;

forming said sensor portion on said part of said plating layer that is to become said movable portion; and

removing said resist layer.