US4640382A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Acoustic frictional resistance construction and method of producing an acoustic frictional resistance using a laser
Assignee: AKG Acoustics GmbH
•
Filing: 1984-08-28
•
Granted: 1987-02-03
•
Expires: 2004-08-28
Abstract
Abstract Acoustic frictional resistance comprises a plate having at least one laser-formed hole therethrough. The plate is formed by positioning a plate preferably one having a thickness smaller than one and one-half milimeters alongside a laser and directing the laser beam so that it cuts a hole through the plate. During the process of producing the resistance, the value of the acoustic friction is measured as a pressure drop of a constant air stream or as an expenditure of electrical energy for an electrically excited electroacoustic transducer. This measurement is then used as a variable or as a standard for controlling the process. Advantageously, a coherent beam is emitted by the laser which is deflected by mirror from a horizontal to a vertical direction and focused by means of a lens to work in a contact-free manner on a workpiece supported on a support member such as a movable table. By moving the table in two coordinate directions, a plurality of bores are formed in a pattern in a workpiece. The workpiece may comprise a plate which may be rectangular, circular, annular, etc.
Inventors
- 👤 Hans Hartmann
- 👤 Ewald Kerschbaum
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 03:40
CPC Classifications
G; G10; G10K; G10K11/00; G10K11/02; H; H04; H04R; H04R31/00; H04R31/006
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
42 words
An acoustic frictional resistance member for producing a selected known frequency independent acoustical impedance comprising a plate having a thickness of from 0.1 to 1.5 mm and at least one laser formed hole therethrough having a diameter of 0.3 mm at most.
Claim 2
Dependent Claim
42 words
An acoustic frictional resistance member for producing a selected known frequency independent acoustical impedance comprising a plate having a thickness of from 0.1 to 1.5 mm and at least one laser formed hole therethrough having a diameter of 0.3 mm at most.
Claim 3
Independent Claim
56 words
A method of forming an acoustic frictional resistance member having a selected known frequency-independent acoustical impedance comprising providing a flat plate having a thickness of from 0.1 to 1.5 mm, and directing a laser beam at the plate to form a plurality of holes through the plate each having a diameter of 0.3 mm at most.
Claim 4
Independent Claim
56 words
A method of forming an acoustic frictional resistance member having a selected known frequency-independent acoustical impedance comprising providing a flat plate having a thickness of from 0.1 to 1.5 mm, and directing a laser beam at the plate to form a plurality of holes through the plate each having a diameter of 0.3 mm at most.
Claim 5
Dependent Claim
44 words
A method according to claim 2, wherein the laser beam is deflected before it is used to form a hole in the plate and wherein the plate is moved after the formation of each hole to position it in respect to the laser beam.
Claim 6
Dependent Claim
34 words
A method according to claim 3, wherein the plate is moved relative to the laser to form holes in the plate which is selected from a thin plate of rectangular, circular, or annular shape.
Claim 7
Dependent Claim
28 words
A method according to claim 2, wherein the flat plate comprises a transducer body and the plurality of holes are formed by the laser in said transducer body.
Claim 8
Dependent Claim
20 words
A method according to claim 5, wherein one or more concentric rows of holes are formed in said transducer body.
Claim 9
Dependent Claim
32 words
A method according to claim 2, including deflecting the laser beam by a different amount to move the laser beam to form each of the plurality of holes in the flat plate.
Claim 10
Independent Claim
131 words
A method of forming an acoustic frictional resistance member having a selected known acoustical impedance comprising providing a flat plate having a thickness of from 0.1 to 1.5 mm, directing a laser beam at the plate to form a plurality of holes through the plate each having a diameter of 0.3 mm at most, supplying a constant air stream to the plate during the formation of the holes in the plate, measuring a pressure drop of the constant air stream at the plate, the pressure drop having the value corresponding to an instantaneous frictional resistance of the plate, comparing the instantaneous frictional resistance of the plate to a desired final frictional resistance of the plate, and stopping the formation of holes when the instantaneous frictional resistance meets the desired frictional resistance.
Claim 11
Independent Claim
131 words
A method of forming an acoustic frictional resistance member having a selected known acoustical impedance comprising providing a flat plate having a thickness of from 0.1 to 1.5 mm, directing a laser beam at the plate to form a plurality of holes through the plate each having a diameter of 0.3 mm at most, supplying a constant air stream to the plate during the formation of the holes in the plate, measuring a pressure drop of the constant air stream at the plate, the pressure drop having the value corresponding to an instantaneous frictional resistance of the plate, comparing the instantaneous frictional resistance of the plate to a desired final frictional resistance of the plate, and stopping the formation of holes when the instantaneous frictional resistance meets the desired frictional resistance.
Claim 12
Dependent Claim
32 words
A method according to claim 8, including deflecting the laser beam by a different amount to move the laser beam to form each of the plurality of holes in the flat plate.
Claim 13
Dependent Claim
35 words
A method according to claim 9, including forming each hole to be cylindrical having a radius r, said flat plate having an acoustic frictional resistance with a transfer frequency fu which equals fu=(3μ/πρ)(1/r 2 )
References Cited (Backward Citations)
US2656004A
Cited
GB670868A
Cited
US2761912A
Cited
US3419321A
Cited
US3777079A
Cited
US3734234A
Cited
US3930560A
Cited
AT337793B
Cited
US4069401A
Cited
US4281670A
Cited
JPS54102691A
Cited
JPS564391A
Cited
US4391519A
Cited
US4447678A
Cited
US4458134A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-02-02 | 1990-08-04 | 1991-02-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-02-02 | 1994-08-04 | 1995-02-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-02-02 | 1998-08-04 | 1999-02-03 | $7700.00 | Window Closed / Lapsed |