Claims
- 1. A sensor element for detecting a solid particle in a fluid, comprising:
- a substrate comprising (i) a main body having a closed-bottom recess formed in an upper surface thereof, and (ii) a thin-walled vibrating portion covering said recess so as to form a closed cavity; and
- a detecting unit formed on a surface of said thin-walled vibrating portion outside said closed cavity, said detecting unit comprising a piezoelectric film, a first electrode coated on at least a portion of the outer surface of said piezoelectric film, and a second electrode coated on at least a portion of the inner surface of said piezoelectric film;
- wherein said detecting unit and said thin-walled vibrating portion have sufficiently low mass such that solid particles in the fluid strike said detecting unit causing said detecting unit and said thin-walled vibrating portion to vibrate, and said piezoelectric film converts the vibration into an electric signal.
- 2. The sensor element of claim 1, wherein said substrate is a unitary ceramic substrate, and said main body and said thin-walled vibrating portion are integral parts thereof.
- 3. The sensor element of claim 1, wherein said piezoelectric film comprises at least one material selected from the group consisting of lead zirconate, lead magnesium niobate, lead nickel niobate, lead zinc niobate, lead manganese niobate, lead antimony stanate, lead titanate, and barium titanate.
- 4. The sensor element of claim 1, wherein the fluid is a lubricant.
- 5. The sensor element of claim 1, wherein said piezoelectric film has a thickness ranging from 1 to 100 micrometers, and said thin-walled vibrating portion has a thickness ranging from 1 to 100 micrometers.
- 6. The sensor element of claim 1, wherein said thin-walled vibrating portion comprises stabilized zirconium oxide.
- 7. The sensor element of claim 1, further comprising a protective cover for housing at least said detecting unit of the sensor element.
Parent Case Info
This application is a continuing application of U.S. Ser. No. 08/221,014, filed Apr. 1, 1994 now abandoned.
US Referenced Citations (21)
Foreign Referenced Citations (2)
Number |
Date |
Country |
0408306 |
Jan 1991 |
EPX |
0455342 |
Nov 1991 |
EPX |
Continuations (1)
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Number |
Date |
Country |
Parent |
221014 |
Apr 1994 |
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