US3941932A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Loudspeaker having a voice coil and a piezoelectric feedback transducer
Assignee: US Philips Corp
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Filing: 1974-05-29
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Granted: 1976-03-02
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Expires: 1994-05-29
Abstract
Abstract Loudspeaker, in particular low-note loudspeaker, provided with a cone-shaped diaphragm having a coil form on which in addition to the voice coil is mounted a piezoelectric transducer in the form of a thin plate capable of pivotal movement. The output voltage of the transducer is degeneratively fed back to the input of an associated amplifier. The plate preferably is rectangular and suspended in rubber mounts along two opposed edges. The mounts form part of a mounting board provided with printed wiring on which an electronic transformation circuit is arranged. A shallow cup in which the mounting board is accommodated ensures that the piezoelectric plate is separated in an airtight manner from the coil form.
Inventors
- 👤 Guido Odilon Maurits D'Hoogh
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 17:44
CPC Classifications
H; H04; H04R; H04R3/00; H04R3/002
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
113 words
A loudspeaker comprising, a cone-shaped vibratory diaphragm having an inner portion secured to a coil form, a voice coil mounted on the coil form, means including the voice coil for vibrating the coil form and diaphragm, a piezoelectric transducer mounted on the coil form and comprising a thin plate of piezoelectric material having two opposed edges hingedly connected to the coil form and situated within the circumference of said voice coil and with its major surfaces lying in a plane substantially normal to the axis of the voice coil, and means for degeneratively coupling the output voltage of the piezoelectric transducer to an input of an amplifier adapted to drive the voice coil.
Claim 2
Dependent Claim
113 words
A loudspeaker comprising, a cone-shaped vibratory diaphragm having an inner portion secured to a coil form, a voice coil mounted on the coil form, means including the voice coil for vibrating the coil form and diaphragm, a piezoelectric transducer mounted on the coil form and comprising a thin plate of piezoelectric material having two opposed edges hingedly connected to the coil form and situated within the circumference of said voice coil and with its major surfaces lying in a plane substantially normal to the axis of the voice coil, and means for degeneratively coupling the output voltage of the piezoelectric transducer to an input of an amplifier adapted to drive the voice coil.
Claim 3
Dependent Claim
26 words
A loudspeaker as claimed in claim 1 wherein the piezoelectric plate is rectangular and is clamped in rubber mounts along two opposed edges of the plate.
Claim 4
Dependent Claim
33 words
A loudspeaker as claimed in claim 2, wherein the mounts are accommodated in a mounting board provided with printed wiring and on which electric components are inserted which together form an impedance transformer.
Claim 5
Dependent Claim
50 words
A Loudspeaker as claimed in claim 2, further comprising a mounting board on which the rubber mounts are supported and wherein the mounting board is accommodated in a shallow cup which is coupled to the coil form and separates the piezoelectric transducer from the coil form in an airtight manner.
Claim 6
Dependent Claim
53 words
A loudspeaker as claimed in claim 1 wherein the piezoelectric plate includes first and second electrodes and first and second electric connections connected to said first and second electrodes respectively, by means of solder drops of sufficient size to cause the natural frequency of the transducer and its suspension to exceed 3000 Hz.
Claim 7
Dependent Claim
118 words
A loudspeaker comprising, a cone-shaped vibratory diaphragm having an inner portion secured to a coil form and an outer portion attached to a support member, a voice coil attached to the coil form for vibrating the coil form and the attached diaphragm, a transducer comprising a plate of piezoelectric material, means for mounting said piezoelectric plate on the coil form in non-cantilevered fashion within the circumference of said voice coil and with its major surfaces lying in a plane substantially normal to the axis of the voice coil so as to allow pivotal movement of the plate, and means for coupling the output voltage of the transducer to an input of an amplifier adapted to drive said coil.
Claim 8
Dependent Claim
118 words
A loudspeaker comprising, a cone-shaped vibratory diaphragm having an inner portion secured to a coil form and an outer portion attached to a support member, a voice coil attached to the coil form for vibrating the coil form and the attached diaphragm, a transducer comprising a plate of piezoelectric material, means for mounting said piezoelectric plate on the coil form in non-cantilevered fashion within the circumference of said voice coil and with its major surfaces lying in a plane substantially normal to the axis of the voice coil so as to allow pivotal movement of the plate, and means for coupling the output voltage of the transducer to an input of an amplifier adapted to drive said coil.
Claim 9
Dependent Claim
47 words
A loudspeaker as claimed in claim 6 wherein the piezoelectric plate has a rectangular shape and said mounting means comprises, a mounting board mechanically coupled to the coil form and means for pivotally supporting the piezoelectric plate on the mounting board along opposed edges of the plate.
Claim 10
Dependent Claim
64 words
A loudspeaker as claimed in claim 7 wherein said mounting means further comprises a cup-shaped member supported by the coil form and in which the mounting board is supported so that the cup-shaped member separates the piezoelectric plate from the coil form in an airtight manner thereby to isolate said plate from the effects of air movements produced by movement of the coil form.
Claim 11
Dependent Claim
44 words
A loudspeaker as claimed in claim 7 wherein the mass of the transducer and the stiffness of the pivotal supporting means are chosen so that the resonant frequency of the transducer and its pivotal supporting means exceed the operating frequency range of the loudspeaker.
Claim 12
Dependent Claim
28 words
A loudspeaker as claimed in claim 6 wherein said coupling means is connected to feed back the transducer output voltage to provide a degenerative action in said amplifier.
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) | 1979-03-02 | 1979-09-01 | 1980-03-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-03-02 | 1983-09-01 | 1984-03-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-03-02 | 1987-09-01 | 1988-03-02 | $7700.00 | Window Closed / Lapsed |