Patent US5146435A successfully refreshed from Google Patents.
US5146435A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Acoustic transducer
Assignee: Charles Stark Draper Laboratory Inc
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Filing: 1989-12-04
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Granted: 1992-09-08
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Expires: 2009-12-04
Abstract
Abstract An acoustic transducer includes a perforated capacitor plate; a movable capacitor plate spaced from the perforated plate; springs for movably supporting the movable capacitor plate relative to the perforated plate; and a support structure for supporting the perforated and movable plates, where the movable plate is interconnected to the support structure by the springs and where the plates, springs and support structure form a unified, monolithic structure. The movable plate, springs and support structure are made from a silicon wafer. The transducer also includes a dielectric fluid in the space between the plates; and equipment for applying an electric field across the plates for producing an output signal representative of the variation in capacitance induced by the variation in space between the plates in response to an acoustic signal.
Inventors
- 👤 Jonathan J. Bernstein
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 11:10
CPC Classifications
G; G01; G01H; G01H11/00; G01H11/06; H; H04; H04R; H04R19/00; H04R19/005; H04R1/00; H04R1/44; H04R19/04; Y; Y10; Y10T; Y10T29/00; Y10T29/43; Y10T29/435
Claims Analysis
Total Claims: 31
Claim 1
Independent Claim
124 words
An acoustic transducer comprising: perforated plate means; movable capacitor plate spaced from said perforated plate means; spring means interconnecting said movable plate means and said perforated plate means for movably supporting said movable capacitor plate means relative to said perforated plate means; said perforated plate, movable plate and spring means made from a silicon wafer, and said perforated plate, movable plate, and spring means forming a unified monolithic structure; a dielectric fluid in the space between said movable and perforated plate means; and means for applying an electric field across said movable and perforated plate means for producing an output signal representative of the variation in capacitance induced by the variation of the space between the plates in response to an incident acoustic signal.
Claim 2
Dependent Claim
124 words
An acoustic transducer comprising: perforated plate means; movable capacitor plate spaced from said perforated plate means; spring means interconnecting said movable plate means and said perforated plate means for movably supporting said movable capacitor plate means relative to said perforated plate means; said perforated plate, movable plate and spring means made from a silicon wafer, and said perforated plate, movable plate, and spring means forming a unified monolithic structure; a dielectric fluid in the space between said movable and perforated plate means; and means for applying an electric field across said movable and perforated plate means for producing an output signal representative of the variation in capacitance induced by the variation of the space between the plates in response to an incident acoustic signal.
Claim 3
Dependent Claim
23 words
The acoustic transducer of claim 1, wherein said movable plate and spring means are made from a silicon wafer using micromachining photolithographic process.
Claim 4
Dependent Claim
23 words
The acoustic transducer of claim 1, wherein said movable plate and spring means are made from a silicon wafer using micromachining photolithographic techniques.
Claim 5
Dependent Claim
21 words
The acoustic transducer of claim 1 in which said perforations constitute approximately thirty percent or more of said perforated plate means.
Claim 6
Dependent Claim
12 words
The acoustic transducer of claim 1 in which said perforations are holes.
Claim 7
Dependent Claim
12 words
The acoustic transducer of claim 1 in which said perforations are slots.
Claim 8
Dependent Claim
15 words
The acoustic transducer of claim 1 in which said dielectric fluid is a gaseous medium.
Claim 9
Dependent Claim
13 words
The acoustic transducer of claim 7 in which said gaseous medium is air.
Claim 10
Dependent Claim
14 words
The acoustic transducer of claim 1 in which said dielectric fluid is a liquid.
Claim 11
Dependent Claim
37 words
The acoustic transducer of claim 1 in which said dielectric fluid has a specific gravity matched to that of said movable plate means to minimize errors due to motion of the plate in response to acceleration forces.
Claim 12
Dependent Claim
48 words
The acoustic transducer of claim 1 in which said monolithic structure includes a chamber, said chamber has an opening, said movable and perforated plate means are disposed across said opening with one of said movable and perforated plate means facing into said chamber and the other facing out.
Claim 13
Dependent Claim
27 words
The acoustic transducer of claim 11 in which said chamber is filled with the same dielectric fluid as is present in the space between said plate means.
Claim 14
Dependent Claim
20 words
The acoustic transducer of claim 1 in which said movable plate means moves translationally relative to said perforated plate means.
Claim 15
Dependent Claim
20 words
The acoustic transducer of claim 11 in which said movable plate means moves rotationally relative to said perforated plate means.
Claim 16
Dependent Claim
60 words
The acoustic transducer of claim 1 further including a second perforated plate means on the opposite side of said movable plate means from the first said perforated plate means and spaced from said movable plate means with dielectric fluid between them, said movable plate means, spring means and both first and second perforated plate means forming a unified, monolithic structure.
Claim 17
Dependent Claim
30 words
The acoustic transducer of claim 15 in which said means for applying an electric field applies an electric field across said second perforated plate means and said movable plate means.
Claim 18
Dependent Claim
41 words
The acoustic transducer of claim 16 in which said means for applying an electric field applies an electric field of one polarity to the first said perforated plate means and of the opposite polarity to the second said perforated plate means.
Claim 19
Dependent Claim
18 words
The acoustic transducer of claim 1 in which said movable plate means is held at a virtual ground.
Claim 20
Dependent Claim
18 words
The acoustic transducer of claim 17 in which said movable plate means is held at a virtual ground.
Claim 21
Dependent Claim
20 words
The acoustic transducer of claim 11 further including a flexible membrane covering the plate means facing out of said chamber.
Claim 22
Dependent Claim
24 words
The acoustic transducer of claim 1 in which said movable plate means includes a pressure equalization path through the plate interconnecting its opposite faces.
Claim 23
Dependent Claim
14 words
The acoustic transducer of claim 21 in which said path includes a perimetrical slot.
Claim 24
Dependent Claim
16 words
The acoustic transducer of claim 21 in which said perforated plate means includes strain relief means.
Claim 25
Dependent Claim
14 words
The acoustic transducer of claim 23 in which said strain relief means are slots.
Claim 26
Dependent Claim
78 words
The acoustic transducer of claim 1 in which said means for applying an electric field includes a local oscillator circuit for providing a carrier wave across said plate means, means for ampllifying said carrier wave modulated by the variations introduced by variations in the space between said plate means, means for demodulating said carrier wave to obtain the modulating variations in spacing of said plate means representative of the change in capacitance effected by incident acoustic wave energy.
Claim 27
Dependent Claim
22 words
The acoustic transducer of claim 1, in which said movable plate, spring and perforated plate means are made from a silicon wafer.
Claim 28
Dependent Claim
28 words
The acoustic transducer of claim 15, in which said movable plate means, spring means and said first and second perforated plate means are made from a silicon wafer.
Claim 29
Dependent Claim
29 words
The acoustic transducer of claim 1, in which said means for applying an electric field across said movable and perforated plate means includes circuitry integrated into said silicon wafer.
Claim 30
Dependent Claim
25 words
The acoustic transducer of claim 26, wherein said movable plate, spring and perforated plate means are made from a silicon wafer using micromachining photolithographic process.
Claim 31
Dependent Claim
30 words
The acoustic transducer of claim 27, wherein said movable plate means, spring means and first and second perforated plate means are made from a silicon wafer using micromachining photolithographic process.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1995-09-08 | 1996-03-09 | 1996-09-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-09-08 | 2000-03-09 | 2000-09-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-09-08 | 2004-03-09 | 2004-09-08 | $7700.00 | Window Closed / Lapsed |