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Publication numberUS3721840 A
Publication typeGrant
Publication dateMar 20, 1973
Filing dateSep 14, 1971
Priority dateSep 14, 1971
Publication numberUS 3721840 A, US 3721840A, US-A-3721840, US3721840 A, US3721840A
InventorsYamada H
Original AssigneeNittan Co Ltd
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Sound generator
US 3721840 A
Abstract
A sound generator having a relatively thin diaphragm and a piezoelectric disc element with electrodes bonded to opposing sides thereof adhered to one side of said diaphragm and means supporting the edge of said diaphragm.
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Description  (OCR text may contain errors)

Yamada at; 3 "mile +0 imitet SOUND GENERATOR [75] Inventor: Hayao Yamada, Kita-ku, Tokyo,

Japan [73] Assignee: Nittan Company, Limited, Tokyo,

Japan [22] Filed: Sept. 14, 1971 [21] App1.No.: 180,397

[52] US. Cl ..310/9.1,179/110 A, 310/82 [51] int. Cl. ..H04r 17/00 [58] Field of Search ..3 10/8, 8.2, 8.3, 9.1-9.4,

[5 6] References Cited UNITED STATES PATENTS 9/1965 Shoot ..179/11OA 1/1969 Kompanek ]March 20, 1973 3,683,129 8/1972 Roos et a1 ..179/11OA 3,271,596 9/ 1 966 Brinkerhoff ..310/8.3 X 3,427,481 2/1969 Lenahan et a1... ..310/8.2 2,967,957 l/l96l Massa ..310/8.3 X 2,910,545 10/1959 Glenn ..179/1l0 A 3,222,462 12/1965 Karmann et a1. 179/1 10 R 3,439,128 4/1969 Sobeletal ..179/110A Primary Examiner-J. D. Miller Assistant ExaminerMark O. Budd Att0mey-Eugene E'. Geoffrey, Jr.

[ 5 7 ABSTRACT A sound generator having a relatively thin diaphragm and a piezoelectric disc element with electrodes bonded to opposing sides thereof adhered to one side of said diaphragm and means supporting the edge of said diaphragm.

1 Claim, 5 Drawing Figures 1 SOUND GENERATOR This invention relates to a sound generator and more particularly to an improved structure for supporting the vibrator of a sound generator including a piezoelectric vibrator.

Various structures have been proposed for supporting a piezoelectric vibrator of a sound generator, but most of them are so complicated in structure that the cost of manufacture is generally high and many problems have been encountered in design and manufacture. This is especially true in the case of the design of a waterproof sound generator.

Accordingly, one object of this invention resides in the provision of a sound generator having an improved vibrator supporting the structure which is simple, inexpensive, and waterproof.

According to this invention, a piezoelectric vibration element made of piezoelectric material such as barium titanate and having a pair of electrodes adhered on both faces thereof is adhered to the face of a thin plate made of synthetic resin, and the thin resin plate is fixed at its circumference to a supporting base member.

The invention will be more clearly described hereinunder with reference to the accompanying drawings.

FIG. 1 is a cross-sectional view representing one embodiment of a vibrator supporting structure according to the invention;

FIG. 2 is a cross-sectional view representing another embodiment of a vibrator supporting structure according to the invention;

FIG. 3 is a graph for use in explaining a feature of the structure of FIG. 2;

FIG. 4 is a cross-sectional view representing a further embodiment of a vibrator supporting structure according to the invention; and

FIG. 5 is a graph for use in explaining a feature of the structure of FIG. 4.

Throughout the drawings like reference numerals are used to denote corresponding structural elements.

'Referring to FIG. 1, the vibrator is composed of a piezoelectric element 1 in the form of a circular disc of piezoelectric material such as barium titanate and a pair of electrodes 2 and 3 adhered or deposited on both faces of said piezoelectric element 1. The vibrator is adhered to the face of a thin circular plate 4 made of synthetic resin. The thin plate 4 is supported at its circumference by a supporting member 5 which is generally a portion of a housing and fixedly secured by an overlying member 6 to the member 5. Though various kinds of synthetic resin can be used for the thin plate 4, it has been found that polyethylene terephthalate and cellulose triacetate are especially suitable. The thickness of the thin plate 4 should be selected so as to maximize the transducing efficiency, and may preferably be 0.l to 0.5 millimeters, for example. As readily found from the drawing, the thin plate 4 functions as the diaphragm of the sound generator and, at the same time, serves a function of a waterproof bulkhead for the internally contained elements (not shown).

The embodiment shown in FIG. 2 resembles the embodiment of FIG. 1 but the thin resin plate 4 of FIG. 2 has a central opening 7 and the vibrator (electrode 3) is adhered at its circumference to the resin plate 4 so as to cover the opening 7. The effect of the opening 7 as shown in FIG. 3 illustrates the relation of the load and sound volume to the diameter of the opening 7. In the figure the solid curve A shows the load in ohms and the dashed curve B shows the sound volume in decibels. As clearly evident from this figure, the load decreases and the sound volume increases with an increase in the diameter of the opening 7. However, the diameter of the opening 7 is limited by the size of the vibrator since the bonding strength of the vibrator and the thin plate 4 must not be lower than a specific value. It has been found that this allowable lowest bonding strength is reduced when the diameter of the piezoelectric element 1 is smaller than the diameter of the opening 7 to provide more efficient vibration.

The embodiment of FIG. 4 includes a vibratordiaphragm structure similar to that of FIG. I, but annular resilient materials 8 and 9 are disposed between the thin resin plate 4 and the supporting members 5 and 6. The resilient material may be foam rubber, polyurethane foam or the like. The acoustic efficiency is increased with decrease of the density of the resilient material as shown by the density-load curve of FIG. 5.

As described in the above, the vibrator supporting structure of this invention is simple in construction and inexpensive to manufacture and will provide a watertight structure for the sound generator.

I claim:

1. A sound generator comprising a piezoelectric disc having opposing faces, an electrode electrically connected to each face of said disc with one of said electrodes being in the form of a disc having a diameter greater than said piezoelectric disc, a thin circular synthetic resin plate having a central circular opening of a diameter greater than the diameter of said piezoelectric disc and smaller than said electrode disc, and means securing said electrode disc in overlying relationship to said opening with the piezoelectric disc disposed concentrically of said opening.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2910545 *Aug 30, 1954Oct 27, 1959Gen ElectricTransducer
US2967957 *Sep 17, 1957Jan 10, 1961Frank MassaElectroacoustic transducer
US3206558 *Sep 22, 1961Sep 14, 1965Erie Technological Prod IncMicrophone
US3222462 *Sep 26, 1962Dec 7, 1965Siemens AgElectroacoustic transducer
US3271596 *Nov 12, 1963Sep 6, 1966Boeing CoElectromechanical transducers
US3423543 *Jun 24, 1965Jan 21, 1969Kompanek Harry WLoudspeaker with piezoelectric wafer driving elements
US3427481 *Jun 14, 1965Feb 11, 1969Magnaflux CorpUltrasonic transducer with a fluorocarbon damper
US3439128 *May 16, 1966Apr 15, 1969Zenith Radio CorpMiniature ceramic microphone
US3683129 *Sep 25, 1969Aug 8, 1972Philips CorpElectroacoustic transducer having a diaphragm made of at least one layer of piezoelectric material
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US4190784 *Sep 15, 1978Feb 26, 1980The Stoneleigh Trust, Fred M. Dellorfano, Jr. & Donald P. Massa, TrusteesPiezoelectric electroacoustic transducers of the bi-laminar flexural vibrating type
US4328485 *Nov 28, 1980May 4, 1982Potter Bronson MBinary alarm
US4386241 *Aug 13, 1980May 31, 1983Seikosha Co., Ltd.Piezoelectric loudspeaker
US4471258 *Nov 9, 1981Sep 11, 1984Hitachi, Ltd.Piezoelectric ceramic transducer
US4700177 *Dec 17, 1984Oct 13, 1987Nippondenso Co., Ltd.Sound generating apparatus with sealed air chamber between two sounding plates
US5896000 *Feb 9, 1996Apr 20, 1999Vectron Laboratories, Inc.Mounting for reducing vibration-induced side bands
US7167570 *Aug 28, 2001Jan 23, 2007Fujihiko KobayashiPiezo-electric speaker
US8113689 *Mar 8, 2007Feb 14, 2012Nanohmics, Inc.Non-lethal projectile for disorienting adversaries
US8466604 *May 4, 2010Jun 18, 2013Samsung Electro-Mechanics Co., Ltd.Vibration actuator module having smaller elastic modulus than vibrated body
US8670578 *Mar 5, 2009Mar 11, 2014Nec CorporationPiezoelectric actuator and electronic device
US20110002485 *Mar 5, 2009Jan 6, 2011Nec CorporationPiezoelectric actuator and electronic device
US20110127884 *May 4, 2010Jun 2, 2011Samsung Electro-Mechanics Co., Ltd.Vibration actuator module
DE3620557A1 *Jun 19, 1986Dec 23, 1987Reinhardt FischerElectroacoustic transducer
WO1988003691A1 *Oct 1, 1987May 19, 1988Olten Ag Elektro ApparatebauAcoustic signal generator
Classifications
U.S. Classification310/334, 310/345, 310/324, 381/173
International ClassificationH04R17/00
Cooperative ClassificationH04R17/00
European ClassificationH04R17/00