Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
  • G01H11/00—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by detecting changes in electric or magnetic properties
  • G01H11/06—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by detecting changes in electric or magnetic properties by electric means
  • G01H11/08—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by detecting changes in electric or magnetic properties by electric means using piezoelectric devices
• • G—PHYSICS
  • G10—MUSICAL INSTRUMENTS; ACOUSTICS
  • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
  • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
  • G10K11/004—Mounting transducers, e.g. provided with mechanical moving or orienting device
• • G—PHYSICS
  • G10—MUSICAL INSTRUMENTS; ACOUSTICS
  • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
  • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
  • G10K11/18—Methods or devices for transmitting, conducting or directing sound
  • G10K11/24—Methods or devices for transmitting, conducting or directing sound for conducting sound through solid bodies, e.g. wires

Definitions

• the present invention relates to sensing of force or vibration, delivering electrical signals representative of the sensed force or a parameter of a vibration state. More particularly, the invention relates to a mechano-electrical sensor for sensing force or vibration and delivering at least one electrical signal that is a function of the sensed force or vibration.
• Force sensors, acceleration sensors and vibration sensors have many uses, and exist in many embodiments.
• two or three separate sensors are utilized e.g. to sense acceleration in three orthogonal directions, by allowing massive bodies, suspended in spring systems, to move relative to respective reference frames.
• Rotation is usually sensed with a gyroscope device.
• the present invention aims at providing a sensor that, better than previously known solutions, is able to operate with a directional effect and provide good mea- surements regarding translation as well as rotation, by means of one movable body only.
• Fig. 1 shows a two-dimensional embodiment of the sensor in accordance with the invention
• Fig. 2 shows the same embodiment as Fig. 1 , however suspended in an outer frame
• Fig. 3 shows another two-dimensional embodiment of the sensor in accordance with the invention.
• Fig. 4 shows the same embodiment as Fig. 3, however suspended in an outer frame
• Fig. 5 shows a three-dimensional embodiment of the sensor in accordance with the invention, with foil-shaped support structures, in a partially cut-away view; and Fig. 6 shows another three-dimensional embodiment with filament-shaped support structures, this drawing also in a partially cut-away view.
• Fig. 1 appears a relatively simple, two-dimensional embodiment of the sensor of the invention.
• An inner body 1 is supported by means of piezoelectric
• foils 3 in a framework 2 are able to deliver electrical signals generated when the foils are subject to deformation due to shift of the inner body 1 relative to a relaxed centre position.
• the figure shows three foils tautened in a hexagonal opening, however one single foil may be used, or a larger number of foils.
• the choice of lo inner body will depend on the use field of the sensor.
• the inner body may, in uses including recording from soft surfaces, consist of e.g. plastic or silicone rubber with various shore values. In other applications, for example industrial diamond material may be used. Combinations of material and geometrical shape of the inner body is important.
• the inner body may also exhibit openings to provide a possibi- i5 lity for air passage therethrough, for example in microphone applications.
• the foils may possibly be attached between two metallic frame parts that are insulated from each other and possibly from other frame parts along the periphery, so that signals can be collected from the metallic frame parts.
• the stretch directions of the foils may be e.g. along the longitu-
• framework 2 crucial, as long as the frame is rigid and suitable for attaching the piezoelectric foils.
• Such a two-dimensional sensor will clearly be most sensitive with regard to force or vibratory influence in a direction perpendicular to the plane spanned by
• Fig. 2 appears the same embodiment as in Fig. 1 , however the whole basic sensor is suspended in an outside framework 5.
• the suspension is by means of elastic elements 4, e.g. rubber elements, and such an embodiment of the invention will be particularly favourable e.g. when using the sensor as a sensor element in a microphone.
• the main purpose of the outside framework 5 is noise attenuation, i.e. attenuation of noise in the form of vibrations that may bring the piezo elements of the sensor into oscillation.
• the framework 2 or the inner body 1 that is supposed to oscillate in relation to the surroundings.
• the suspension of the sensor frame will normally provide "good” acoustic coupling between the surroundings and the sensor elements, and normally this is not desirable.
• the mass of the inner body will influence the characteristic (the frequency response) most strongly, but design and material choice will also be of importance regarding the coupling between the "sensed medium” and the sensor. Due to the coupled oscillatory systems, the characteristic must be optimized as a function of mass ratios, stiffnesses etc.
• Fig. 3 appears an alternative embodiment of the sensor in accordance with the invention, still in a two-dimensional version.
• an inner body 1 suspended in a number of sector-shaped piezoelectric foils 3, and preferably the stretch direction for every foil sector is arranged in the same manner in relation to the radius in the respective position, e.g. pointing substantially in a radial direction.
• connection of signal leads is made in a similar manner as mentioned regarding Fig. 1 , and it appears that it may be possible to achieve high sum voltages with appropriate coupling of signal leads from each respective foil sector, if this is desirable. Alternatively, of course separate signals can be collected from each respective sector.
• Fig. 4 shows suspension in an outer frame 5 in the same manner as in Fig. 2, however in this case the suspension structures are elastic, sector-shaped diaphragms made of e.g. rubber.
• Fig. 5 appears an embodiment of a three-dimensional type.
• the inner body 1 is held suspended at the centre of a spherical frame 2, by means of piezoelectric foil pieces 3 arranged in such a manner that a relative shifting of the inner body 1 , or a rotation for that matter, will be detectable by means of voltages cre- ated in the foils 3, and that can be collected by means of (not shown) signal wires connected to the two sides of the foil pieces projecting out through the frame.
• framework 2 does not have to be spherical, nor does it need to be closed, but it is important that it is rigid, in order to constitute a reference for the position of the inner body.
• the piezoelectric foils have been replaced by filaments, and the filaments are either of a piezoelectric type with corresponding function as the foil pieces in Fig. 5, or the filaments are taut and substantially inelastic, but attached to piezoelectric areas (not shown) of the framework, so that these areas generate voltages depending on the translation or rotation of the inner body relative to framework 2.
• Such a three-dimensional force/vibration sensor as shown in Fig. 5 and Fig. 6, is based upon a rigid coupling between the framework and the body for which force or possibly acceleration shall be measured, and thereby the inertia of the inner body will create the measurable voltages in the suspension structures 3 or in their attachment areas.
• an acceleration/vibration sensor may constitute a main element in e.g. an inertia navigation system.
• the three-dimensional embodiments shown in Figs. 5 and 6 can be suspended in an outer framework via an elastic material in two or three dimensions.
• the foil pieces shown in the embodiment of Fig. 5 may come in other sha- pes, for example more sector-like or possibly as approximations to full circle areas, and the planes to be spanned, do not necessarily have to be orthogonal like in the figure.
• foil materials or filament materials are not the only possible materials in this application, the suspension structures between inner body and frame- work may possibly be piezoelectric bimorph elements or similar elements.
• the invention is also intended to accommodate the variant that has already been mentioned, namely the variant with suspension structures that are not piezoelectric, but attached to piezoelectric areas of the framework.

Landscapes

• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Acoustics & Sound (AREA)
• Multimedia (AREA)
• Measurement Of Mechanical Vibrations Or Ultrasonic Waves (AREA)
• Force Measurement Appropriate To Specific Purposes (AREA)
• Piezo-Electric Transducers For Audible Bands (AREA)

Applications Claiming Priority (3)

Publications (1)

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• 2000
  • 2000-06-23 NO NO20003311A patent/NO312792B1/no not_active IP Right Cessation
• 2001
  • 2001-06-15 JP JP2002506054A patent/JP2004502158A/ja active Pending
  • 2001-06-15 CN CNB01811623XA patent/CN1302267C/zh not_active Expired - Fee Related
  • 2001-06-15 AU AU2001274687A patent/AU2001274687A1/en not_active Abandoned
  • 2001-06-15 PL PL36048301A patent/PL360483A1/xx unknown
  • 2001-06-15 EP EP01941327A patent/EP1311811A1/en not_active Withdrawn
  • 2001-06-15 CA CA002413447A patent/CA2413447A1/en not_active Abandoned
  • 2001-06-15 EA EA200300054A patent/EA200300054A1/ru unknown
  • 2001-06-15 KR KR1020027017589A patent/KR20030071618A/ko not_active Application Discontinuation
  • 2001-06-15 WO PCT/NO2001/000252 patent/WO2002001167A1/en active Application Filing
  • 2001-06-15 BR BR0112277-0A patent/BR0112277A/pt not_active Application Discontinuation

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