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Publication numberUS2691159 A
Publication typeGrant
Publication dateOct 5, 1954
Filing dateMar 13, 1952
Priority dateMar 13, 1952
Publication numberUS 2691159 A, US 2691159A, US-A-2691159, US2691159 A, US2691159A
InventorsHeibel Jerome D
Original AssigneeErie Resistor Corp
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Impact transducer
US 2691159 A
Abstract  available in
Images(1)
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Claims  available in
Description  (OCR text may contain errors)

Patented Oct. 5, 1954 UNITED STATES ATENT OFFICE IMPACT TRANSDUCER Pennsylvania Application March 13, 1952, Serial No. 276,307

1 Claim.

In piezo-electric devices responding to mechanical force, particularly impact, it is desirable that the effect of prior force or vibrations be eliminated, as otherwise the response would depend upon the past history rather than upon the impact. This invention is intended to provide such a device.

In the drawing, Fig. 1 is a top plan of a piezoelectric element; Fig. 2 is an edge view; and Fig. 3 is a circuit diagram.

The piezo-electric device comprises a barium titanate disk I having on opposite faces metalized electrodes 2 and 3 which terminate short of the periphery of the disk so as to provide an insulating band 4. The disk is activated or polarized by a voltage applied across electrodes by known techniques. See Patent No. 2,486,560, Gray.

When used under impact conditions, it is desirable that the ceramic disk be protected against fracture by metal covers 2m and 3a soldered to corresponding electrodes. The function of the covers is to prevent localized stress which might crush the ceramic. The shape of the covers 2a and 3a is not critical. The output of the piezoelectric device appears across the metal parts 2a and 3a which are connected across a neon lamp 5 through a switch 6. When the switch is closed, a blow striking the cover 2a, as indicated by the hammer I, will generate enough voltage in the piezo-electric device to light the lamp.

Because the piezo-electric device is also a capacitor, if the switch 6 is open, any charge appearing across the parts 2c, 8d will be stored and upon closure of the switch 6, the lamp 5 may be lighted, because of casual vibration or other forces exerted on the device sometime prior to the closure of the switch. This, in eifect, causes a false indication.

The false indication caused by casual vibratory or other forces exerted on the piezo-electric device, prior to the closure of the switch 6, is eliminated by a leakage resistance 8 in the form of a band 9 painted over the edge of the ceramic disk I and connecting the electrodes 2 and 3. Suitable paints for the band 9- are well known and may, for example, comprise a varnish loaded with carbon black. The painted resistance has the advantage that it is always present and does not in any way depend upon soldered connections.

No attempt has been made to illustrate the control for the switch 6, nor the actuating devices which may be substituted for the hammer 1, nor the utilization device which may be substituted for the lamp 5. The parts illustrated are sufficient to demonstrate the principle of operation.

What is claimed as new is:

In combination, a piezo-electric device having spaced electrodes across which a voltage appears when the device is subject to a mechanical force, metal caps on and electrically connected to said electrodes for protecting the piezo-electric device from fracture under impact, means supporting the device on one of said caps in position to receive an impact on the other of said caps, a resistance paint painted directly on the device beneath the caps in a path shunted across the electrodes providing a leak resistance, a voltage responsive device, a circuit connecting said device across said electrodes, a switch in said circuit closable whenever the device is to respond to a subsequently generated voltage, the leak resistance serving to discharge the voltage built up on the electrodes by casual impact or vibration prior to the closure of the switch whereby the voltage responsive device responds to voltage generated by impact subsequent to the closure of the switch rather than to voltage generated by prior casual impact or vibration.

References Cited in the file of this patent UNITED STATES PATENTS Australia Apr. 26, 1940

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2106143 *Apr 1, 1936Jan 18, 1938 Piezoelectric device and method of
US2289954 *Jan 8, 1942Jul 14, 1942Brush Dev CoLeakage reducing means
US2562917 *Jun 23, 1947Aug 7, 1951Hoyt William MMethod and apparatus for testing piezoelectric crystals
AU110462B * Title not available
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US2901644 *Dec 5, 1955Aug 25, 1959Tibbetts Lab IncElectromechanical device and method of making same
US2914686 *Oct 6, 1953Nov 24, 1959Texaco IncCrystal microphone
US2921252 *May 28, 1957Jan 12, 1960Edward L SchiavoneElectric generator
US2940035 *Feb 14, 1955Jun 7, 1960Gulton Ind IncElectrical component of ceramic combined with resistor applied to the surface thereof
US2944204 *Apr 26, 1957Jul 5, 1960Plessey Co LtdCharging device for electrometers
US3141330 *Dec 19, 1960Jul 21, 1964Thompson Ramo Wooldridge IncPrecipitation sensing system
US3167668 *Oct 2, 1961Jan 26, 1965Florence NeshPiezoelectric transducers
US3179823 *Jan 30, 1962Apr 20, 1965Florence NeshTransducer for dissipation and detection of high frequency vibratory energy
US3270283 *Oct 4, 1963Aug 30, 1966Kurt IkrathMechanically-actuated radio transmitter
US3363139 *May 28, 1964Jan 9, 1968Edward L. SchiavonePiezoelectric transformer
US3397329 *Oct 19, 1964Aug 13, 1968Endevco CorpMeasuring system
US3464503 *Jun 25, 1968Sep 2, 1969Black & Decker Mfg CoMeasuring device for impact tool
US3808418 *Apr 2, 1973Apr 30, 1974Conard ALight flashing apparatus
US3844174 *Oct 12, 1972Oct 29, 1974Commissariat Energie AtomiqueMethod and device for the rapid measurement of the mass and concentration of particles
US4368032 *Jul 1, 1980Jan 11, 1983Tokyo Shibaura Denki Kabushiki KaishaLiquid fuel combustion apparatus
US4470010 *Oct 15, 1981Sep 4, 1984Sears Lawrence MPiezoelectric apparatus for sensing movement of a moving element such as a dial arm of a utility meter
US4542315 *May 15, 1984Sep 17, 1985Murata Manufacturing Co., Ltd.Chip-shaped piezoelectric vibrator mount
US4658650 *Aug 22, 1985Apr 21, 1987Nippondenso Co., Ltd.Vibration and acoustic wave detecting device employing a piezoelectric element
US4662230 *Aug 19, 1985May 5, 1987AlsthomDevice for measuring the tangential force applied to a toothed rotor
US4723087 *Aug 27, 1986Feb 2, 1988Raychem Ltd.Piezoelectric impact sensor
US5578766 *Apr 3, 1995Nov 26, 1996Nec CorporationForce detector/indicator
US5680718 *Dec 20, 1994Oct 28, 1997First Choice Trading LimitedIlluminable hat
US6012822 *Nov 26, 1996Jan 11, 2000Robinson; William J.Motion activated apparel flasher
US20040130234 *Jan 3, 2003Jul 8, 2004Shah Reza H.Manual power generating device for handheld electronic unit
WO1989010166A1 *Apr 17, 1989Nov 2, 1989Impulse Sports Training SystemsSports impact measuring apparatus
Classifications
U.S. Classification310/319, 340/665, 73/11.1, 310/339, 340/691.1
International ClassificationG01H11/08, G01H11/00
Cooperative ClassificationG01H11/08
European ClassificationG01H11/08