US4038629A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Propagation delay meter
Assignee: US Philips Corp
•
Filing: 1975-05-05
•
Granted: 1977-07-26
•
Expires: 1995-05-05
Abstract
Abstract For accurate measurements of the sound velocity in liquids, for example water, the propagation delay is measured between an ultrasonic wave which is emitted by a transducer and the wave which returns to the transducer upon reflection. By making the reflector spherical and disposing it at a distance from the transducer which is within 11/2 times the length of the Fresnel region of the emitted acoustic wave, a favorable ratio between the 1 τ and the 2 τ signal is obtained, which ratio can be further improved when the central portion of the reflector is slightly flattened.
Inventors
- 👤 Cornelis Martinus van der Burgt
- 👤 Gerardus Andreas Van Maanen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 21:22
CPC Classifications
G; G01; G01N; G01N29/00; G01N29/22; G01N29/24; G01N29/2437; G01N29/245; G01H; G01H5/00; G10; G10K; G10K11/00; G10K11/002
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
124 words
Apparatus for measuring the propagation delay of an acoustic wave in a fluid medium comprising, a transducer for launching an acoustic wave along a given path in the fluid medium, a reflector of acoustic energy positioned in the fluid medium in the path of said acoustic wave at a distance from the transducer which is less than 1/2 times the length of the Fresnel region of the acoustic wave launched by the transducer and greater than one half times said Fresnel region, said reflector having a convex surface facing the transducer for reflecting the launched acoustic wave back towards the transducer, and means coupled to the transducer and responsive to an acoustic wave reflected back from the reflector for deriving an electric control signal.
Claim 2
Dependent Claim
124 words
Apparatus for measuring the propagation delay of an acoustic wave in a fluid medium comprising, a transducer for launching an acoustic wave along a given path in the fluid medium, a reflector of acoustic energy positioned in the fluid medium in the path of said acoustic wave at a distance from the transducer which is less than 1/2 times the length of the Fresnel region of the acoustic wave launched by the transducer and greater than one half times said Fresnel region, said reflector having a convex surface facing the transducer for reflecting the launched acoustic wave back towards the transducer, and means coupled to the transducer and responsive to an acoustic wave reflected back from the reflector for deriving an electric control signal.
Claim 3
Dependent Claim
58 words
An apparatus as claimed in claim 1, characterized in that the reflector comprises a plastic material and the curved surface of the reflector has a radius of curvature between 6 and 12 times the diameter of the transducer and that said curved surface has a flattened central portion with a diameter between 1/8 and 1/4 the transducer diameter.
Claim 4
Dependent Claim
56 words
An apparatus as claimed in claim 1 wherein said control signal deriving means includes an electric pulse generator having a given threshhold value, and means connecting the transducer to the electrical pulse generator which, upon receipt of a reflected wave at the transducer which exceeds said threshold value, generates a new drive pulse for the transducer.
Claim 5
Dependent Claim
44 words
An apparatus as claimed in claim 1 further comprising a backing member made of the same material as the transducer and with a slightly greater diameter and a substantially greater thickness than that of the transducer, said transducer being mounted on the backing member.
Claim 6
Dependent Claim
47 words
An apparatus as claimed in claim 1 wherein the radius of curvature of the reflector curved surface is between three and six times the diameter of the transducer and said curved surface includes a flat central portion with a diameter between 1/8 and 1/4 the transducer diameter.
Claim 7
Dependent Claim
57 words
An apparatus as claimed in claim 1 wherein said control signal deriving means includes an electric pulse generator having a given voltage threshold level, and means connecting the transducer to the electric pulse generator which responds to a reflected wave received at the transducer and exceeding said threshold level to generate a drive pulse for the transducer.
Claim 8
Dependent Claim
37 words
An apparatus as claimed in claim 1 wherein the radius of curvature of the reflector curved surface is at least three times the diameter of the transducer and said curved surface includes a flat central reflecting area.
Claim 9
Dependent Claim
61 words
An apparatus as claimed in claim 7 wherein said transducer comprises a thin circular disc having a thickness dimension approximately half the wavelength of the acoustic wave, and further comprising a backing member supporting the disc and made of the same material as the disc, said backing member being thicker than the disc and of a greater diameter than said disc.
Claim 10
Dependent Claim
40 words
An apparatus as claimed in claim 8 further comprising an elongate housing in which the transducer and reflector are mounted at opposite ends thereof, said housing having openings in the longitudinally extending wall for the passage of the fluid medium.
Claim 11
Dependent Claim
67 words
An apparatus as claimed in claim 7 wherein said control signal deriving means includes an electric pulse generator having a given voltage threshold level and coupled to the transducer to generate a drive pulse for each reflected wave received at the transducer above the threshold level thereby producing a sequence of pulses whose repetition period is related to the propagation delay time between the transducer and reflector.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-07-25 | 1981-01-24 | 1981-07-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-07-25 | 1985-01-24 | 1985-07-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-07-25 | 1989-01-24 | 1989-07-26 | $7700.00 | Window Closed / Lapsed |