US5802195A
Expired / Lapsed
US
⏱️ 0.0 years remaining
High displacement solid state ferroelectric loudspeaker
Assignee: National Aeronautics and Space Administration
•
Filing: 1997-01-13
•
Granted: 1998-09-01
•
Expires: 2017-01-13
Abstract
Abstract A piezoelectric loudspeaker suitable for midrange frequencies uses a dome shaped piezoelectric actuator to drive a speaker membrane directly. The dome shaped actuator is made from a reduced and internally biased oxygen wafer, and generates excursion of the apex of the dome in the order of 0.02-0.05 inches when a rated drive voltage of 350 V rms is applied between the convex and the concave surfaces of the dome shaped actuator. The load capacity exceeds 10 lbs. The edge of the rim of the dome shaped actuator must be free to rock when the dome height varies to ensure low distortion in the loudspeaker. This is achieved by mounting the rim of the dome shaped actuator on a support surface by prestress only. An exceptionally simple design uses a planar speaker membrane with the center part of one side pressed against the rim of a dome shaped actuator by prestress from a stretched latex surround member.
Inventors
- 👤 Curtis R. Regan
- 👤 Antony Jalink, Jr.
- 👤 Richard F. Hellbaum
- 👤 Wayne W. Rohrbach
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 16:00
CPC Classifications
H; H04; H04R; H04R17/00
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
157 words
A loudspeaker, comprising: (a) a speaker membrane; (b) a speaker frame; (c) a solid state integral monomorph dome shaped internally prestressed ferroelectric actuator having a spherical curvature, said solid state integral monomorph dome shaped actuator having a rim and an apex, and a dome height measured from a plane through said rim to said apex that varies with an electric voltage applied between an inside and an outside surface of said dome shaped actuator; and (d) means for mounting said actuator between said speaker frame and said speaker membrane so that said dome height determines an axial distance between said speaker frame and said speaker membrane, wherein said actuator is sandwiched between said speaker membrane and said speaker frame and a predetermined prestress force is applied between said speaker membrane and said speaker frame for mechanically biasing said actuator and said speaker membrane so that the responsiveness of the loudspeaker to lower levels of voltage is increased.
Claim 2
Dependent Claim
157 words
A loudspeaker, comprising: (a) a speaker membrane; (b) a speaker frame; (c) a solid state integral monomorph dome shaped internally prestressed ferroelectric actuator having a spherical curvature, said solid state integral monomorph dome shaped actuator having a rim and an apex, and a dome height measured from a plane through said rim to said apex that varies with an electric voltage applied between an inside and an outside surface of said dome shaped actuator; and (d) means for mounting said actuator between said speaker frame and said speaker membrane so that said dome height determines an axial distance between said speaker frame and said speaker membrane, wherein said actuator is sandwiched between said speaker membrane and said speaker frame and a predetermined prestress force is applied between said speaker membrane and said speaker frame for mechanically biasing said actuator and said speaker membrane so that the responsiveness of the loudspeaker to lower levels of voltage is increased.
Claim 3
Dependent Claim
43 words
A loudspeaker according to claim 1, wherein said means for mounting said actuator permits the edge of said rim pivot freely when said dome height varies so that the spherical curvature of the dome shape is maintained, thereby permitting maximum dome height excursions.
Claim 4
Dependent Claim
27 words
A loudspeaker according to claim 2, wherein said mounting means comprises prestress which permits the edge of the rim to pivot freely when said dome height varies.
Claim 5
Dependent Claim
31 words
A loudspeaker according to claim 2, wherein said speaker membrane is a planar membrane and said actuator is arranged with its rim in contact with one side of said planar membrane.
Claim 6
Dependent Claim
164 words
A midrange driver for a loudspeaker system, comprising: (a) a speaker membrane; (b) a speaker frame; (c) a solid state integral monomorph dome shaped internally prestressed ferroelectric actuator having a spherical curvature for driving the speaker membrane, said actuator having a rim and an apex and an apex height that varies with an electric voltage applied between an inside and an outside surface of said dome shaped actuator; (d) means for mounting said actuator between said speaker frame and said speaker membrane so that said apex height determines an axial distance between said speaker frame and said speaker membrane, wherein said actuator is sandwiched between said speaker membrane and said speaker frame and a predetermined prestress force is applied between said speaker membrane and said speaker frame for mechanically biasing said actuator and said speaker membrane so that the responsiveness of the loudspeaker to lower levels of voltage is increased and the spherical curvature of the actuator is maintained as the apex height varies.
Claim 7
Dependent Claim
164 words
A midrange driver for a loudspeaker system, comprising: (a) a speaker membrane; (b) a speaker frame; (c) a solid state integral monomorph dome shaped internally prestressed ferroelectric actuator having a spherical curvature for driving the speaker membrane, said actuator having a rim and an apex and an apex height that varies with an electric voltage applied between an inside and an outside surface of said dome shaped actuator; (d) means for mounting said actuator between said speaker frame and said speaker membrane so that said apex height determines an axial distance between said speaker frame and said speaker membrane, wherein said actuator is sandwiched between said speaker membrane and said speaker frame and a predetermined prestress force is applied between said speaker membrane and said speaker frame for mechanically biasing said actuator and said speaker membrane so that the responsiveness of the loudspeaker to lower levels of voltage is increased and the spherical curvature of the actuator is maintained as the apex height varies.
Claim 8
Dependent Claim
45 words
A midrange driver for a loudspeaker system according to claim 5, wherein said speaker membrane is a planar disc of light weight material and said rim of said dome shaped actuator is pressed against the center of said planar disc by said predetermined prestress force.
Claim 9
Dependent Claim
19 words
A midrange driver according to claim 5, wherein said actuator has a lower cutoff frequency response below 1,000 Hz.
Claim 10
Dependent Claim
22 words
A device according to claim 1, wherein said actuator is made from a reduced and internally biased oxide wafer of piezoelectric material.
Claim 11
Dependent Claim
22 words
A device according to claim 5, wherein said actuator is made from a reduced and internally biased oxide wafer of piezoelectric material.
Claim 12
Dependent Claim
21 words
A device according to claim 1, wherein said actuator is made from a thin layer composite unimorph ferroelectric driver and sensor.
Claim 13
Dependent Claim
21 words
A device according to claim 5, wherein said actuator is made from a thin layer composite unimorph ferroelectric driver and sensor.
Claim 14
Dependent Claim
157 words
A loudspeaker, comprising: (a) a speaker membrane; (b) a speaker frame; (c) a solid state integral monomorph dome shaped internally prestressed ferroelectric actuator having a spherical curvature, said solid state integral monomorph dome shaped actuator having a rim and an apex, and a dome height measured from a plane through said rim to said apex that varies with an electric voltage applied between an inside and an outside surface of said dome shaped actuator; and (d) means for mounting said actuator between said speaker frame and said speaker membrane so that said dome height determines an axial distance between said speaker frame and said speaker membrane, wherein said actuator is sandwiched between said speaker membrane and said speaker frame and a predetermined prestress force is applied between said speaker membrane and said speaker frame for mechanically biasing said actuator and said speaker membrane so that the responsiveness of the loudspeaker to all levels of voltage is increased.
Claim 15
Dependent Claim
157 words
A loudspeaker, comprising: (a) a speaker membrane; (b) a speaker frame; (c) a solid state integral monomorph dome shaped internally prestressed ferroelectric actuator having a spherical curvature, said solid state integral monomorph dome shaped actuator having a rim and an apex, and a dome height measured from a plane through said rim to said apex that varies with an electric voltage applied between an inside and an outside surface of said dome shaped actuator; and (d) means for mounting said actuator between said speaker frame and said speaker membrane so that said dome height determines an axial distance between said speaker frame and said speaker membrane, wherein said actuator is sandwiched between said speaker membrane and said speaker frame and a predetermined prestress force is applied between said speaker membrane and said speaker frame for mechanically biasing said actuator and said speaker membrane so that the responsiveness of the loudspeaker to all levels of voltage is increased.
Claim 16
Dependent Claim
164 words
A midrange driver for a loudspeaker system, comprising: (a) a speaker membrane; (b) a speaker frame; (c) a solid state integral monomorph dome shaped internally prestressed ferroelectric actuator having a spherical curvature for driving the speaker membrane, said actuator having a rim and an apex and an apex height that varies with an electric voltage applied between an inside and an outside surface of said dome shaped actuator; (d) means for mounting said actuator between said speaker frame and said speaker membrane so that said apex height determines an axial distance between said speaker frame and said speaker membrane, wherein said actuator is sandwiched between said speaker membrane and said speaker frame and a predetermined prestress force is applied between said speaker membrane and said speaker frame for mechanically biasing said actuator and said speaker membrane so that the responsiveness of the loudspeaker to all levels of voltage is increased and the spherical curvature of the actuator is maintained as the apex height varies.
Claim 17
Dependent Claim
164 words
A midrange driver for a loudspeaker system, comprising: (a) a speaker membrane; (b) a speaker frame; (c) a solid state integral monomorph dome shaped internally prestressed ferroelectric actuator having a spherical curvature for driving the speaker membrane, said actuator having a rim and an apex and an apex height that varies with an electric voltage applied between an inside and an outside surface of said dome shaped actuator; (d) means for mounting said actuator between said speaker frame and said speaker membrane so that said apex height determines an axial distance between said speaker frame and said speaker membrane, wherein said actuator is sandwiched between said speaker membrane and said speaker frame and a predetermined prestress force is applied between said speaker membrane and said speaker frame for mechanically biasing said actuator and said speaker membrane so that the responsiveness of the loudspeaker to all levels of voltage is increased and the spherical curvature of the actuator is maintained as the apex height varies.
References Cited (Backward Citations)
US3496617A
Cited
US3676722A
Cited
US3816774A
Cited
US3900748A
Cited
US3891871A
Cited
US4373119A
Cited
US4430529A
Cited
US4488010A
Cited
US5042492A
Cited
US4845776A
Cited
US4868445A
Cited
US5309519A
Cited
US5115472A
Cited
US5185549A
Cited
US4979219A
Cited
US4996713A
Cited
US5149197A
Cited
US5291460A
Cited
US5276657A
Cited
US5589725A
Cited
US5632841A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2001-08-31 | 2002-03-02 | 2002-09-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2005-08-31 | 2006-03-02 | 2006-09-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2009-08-31 | 2010-03-02 | 2010-09-01 | $7700.00 | Window Closed / Lapsed |