Omni-directional ultrasonic transducer apparatus having controlled frequency response
DCFirst Claim
1. A transducer apparatus comprising:
- a spool member having a body portion and first and second elevated regions formed on the body portion;
a piezoelectric film surrounding said spool member and unsecured thereto, said piezoelectric film spaced apart from the body portion of said spool member by an elevation of the elevated regions, thereby forming a predetermined gap between said piezoelectric film and the body portion of said spool member, wherein the predetermined gap is sufficiently sized for enabling a predetermined resonance frequency in said piezoelectric film to control the resonance frequency of the transducer.
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Abstract
A transducer apparatus is disclosed including a spool member having a body portion and first and second elevated regions formed on the body portion. A piezoelectric film such as a PVDF film surrounds the spool member and is spaced apart from the body portion of the spool member by an elevation of the elevated region, thereby forming a predetermined gap between the piezoelectric film and the body portion of the spool member. The predetermined gap is at least 0.1 mm and enables a predetermined resonance frequency in the piezoelectric film to control the resonance frequency of the transducer. Opposite lateral ends of the piezoelectric film are secured together such that secured ends of the piezoelectric film have substantially the same resonance frequency as a remainder of the piezoelectric film.
29 Citations
28 Claims
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1. A transducer apparatus comprising:
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a spool member having a body portion and first and second elevated regions formed on the body portion;
a piezoelectric film surrounding said spool member and unsecured thereto, said piezoelectric film spaced apart from the body portion of said spool member by an elevation of the elevated regions, thereby forming a predetermined gap between said piezoelectric film and the body portion of said spool member, wherein the predetermined gap is sufficiently sized for enabling a predetermined resonance frequency in said piezoelectric film to control the resonance frequency of the transducer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. An omni-directional ultrasonic transducer for use with an external device, the improvement to the ultrasonic transducer comprising:
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a spool member having a body portion and first and second elevated regions formed on the body portion;
a piezoelectric film surrounding said spool member and unsecured thereto, said piezoelectric film spaced apart from the body portion of said spool member by an elevation of the elevated region, thereby forming a substantially uniform predetermined gap between said piezoelectric film and the body portion of said spool member, the predetermined gap sufficiently sized so as to mitigate perturbations to a predetermined resonance frequency in said piezoelectric film. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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23. A transducer apparatus comprising:
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a spool member having a body portion and first and second elevated regions formed on said body portion;
a piezoelectric film surrounding said spool member and unsecured thereto, said piezoelectric film spaced apart from said body portion via said first and second elevated regions to form a gap between said piezoelectric film and the body portion of said spool member, said gap having a thickness selected so as to not influence the resonance frequency of the piezoelectric film. - View Dependent Claims (24, 25, 26)
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27. A transducer apparatus comprising:
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a cylindrical member having a body portion;
a piezoelectric film surrounding said cylindrical member and unsecured thereto, said piezoelectric film spaced apart from said body portion of said cylindrical member to form a gap between said piezoelectric film and said body portion, said gap having a thickness selected so as to not influence the resonance frequency of the piezoelectric film.
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28. A transducer apparatus comprising:
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a cylindrical member having a body portion;
a piezoelectric film surrounding said cylindrical member and unsecured thereto, said piezoelectric film spaced apart from the body portion of said cylindrical member to form a predetermined air gap between said piezoelectric film and said body portion, wherein said air gap is sized so as to have an effective spring constant Ka of about one fifth of the effective spring constant Kb of said film.
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Specification