Classifications

• • 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
  • G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
  • G10K11/175—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound
  • G10K11/178—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase
• • 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
  • G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
  • G10K2210/10—Applications
  • G10K2210/105—Appliances, e.g. washing machines or dishwashers
  • G10K2210/1053—Hi-fi, i.e. anything involving music, radios or loudspeakers
• • 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
  • G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
  • G10K2210/10—Applications
  • G10K2210/106—Boxes, i.e. active box covering a noise source; Enclosures
• • 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
  • G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
  • G10K2210/10—Applications
  • G10K2210/108—Communication systems, e.g. where useful sound is kept and noise is cancelled
• • 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
  • G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
  • G10K2210/10—Applications
  • G10K2210/12—Rooms, e.g. ANC inside a room, office, concert hall or automobile cabin
• • 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
  • G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
  • G10K2210/10—Applications
  • G10K2210/128—Vehicles
  • G10K2210/1282—Automobiles
• • 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
  • G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
  • G10K2210/30—Means
  • G10K2210/321—Physical
  • G10K2210/3217—Collocated sensor and cancelling actuator, e.g. "virtual earth" designs
• • 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
  • G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
  • G10K2210/30—Means
  • G10K2210/321—Physical
  • G10K2210/3223—Materials, e.g. special compositions or gases
• • 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
  • G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
  • G10K2210/30—Means
  • G10K2210/321—Physical
  • G10K2210/3229—Transducers
  • G10K2210/32291—Plates or thin films, e.g. PVDF
• • 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
  • G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
  • G10K2210/50—Miscellaneous
  • G10K2210/509—Hybrid, i.e. combining different technologies, e.g. passive and active
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS
  • H04R17/00—Piezoelectric transducers; Electrostrictive transducers
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS
  • H04R17/00—Piezoelectric transducers; Electrostrictive transducers
  • H04R17/04—Gramophone pick-ups using a stylus; Recorders using a stylus
  • H04R17/08—Gramophone pick-ups using a stylus; Recorders using a stylus signals being recorded or played back by vibration of a stylus in two orthogonal directions simultaneously

Definitions

• the present invention relates to the control of sound and vibration transmission through the use of active materials. More specifically, this invention relates to the use of a structure incorporating a transparent piezoelectric material and electrodes which may be used in windows to reduce the transmission of sound and vibrations.
• Background of the Invention It is desirable in many areas to control transmission of sound and vibrations. For instance, the maintenance of: a quiet environment while traveling (e.g. , in an automobile, train, etc.); an environment conducive to learning in schools; and, an environment suitable for relaxing in a home, hotel, or hospital all depend somewhat on the elimination or reduction of unwanted noise and vibration.
• Past techniques used to control vibrations and sound propagation include passive or active structural vibration damping.
• Passive vibration damping typically involves the use of a damping material such as a passive viscoelastic layer laminated to the vibrating or sound- radiating structure, typically a panel or laminated series of panels.
• a damping material such as a passive viscoelastic layer laminated to the vibrating or sound- radiating structure, typically a panel or laminated series of panels.
• the amount of damping such a panel will provide typically depends on the viscoelastic material chosen and the thickness and geometry of the panel and any ⁇ nstraiiiing layer.
• Active vibration damping typically employs actuators and sensors bonded to a structural panel, beam, or other elastic element(s), and interconnected through an analog and/or digital compensator and signal conditioning electronics to provide enhanced vibration damping or sound radiation control via active feedback or feedforward control.
• the actuators typically consist of piezoceramic chips, piezopolymer layers, magnetostrictive or electrostrictive layers, shape memory materials, and/or electromagnetically- driven actuators such as shakers or proof mass actuators.
• the sensors typically comprise microphones, accelerometers, piezoelectric chips or layers, and/or strain gages.
• An object of the present invention is to provide a structure which is transparent to visible light and capable of eliminating or reducing vibrations and sound propagation.
• a transparent vibration and sound control system for incorporation into a laminated glass or plastic structure which is transparent to visible light and is capable of eliminating or reducing vibrations and sound propagation.
• a transparent vibration and sound control system comprises at least one transparent active layer disposed between transparent patterned electrodes and at least one transparent passive layer affixed to the at least one active layer to create a laminate structure.
• the system also comprises a signal conditioning network electrically connected with the electrodes.
• the thickness and arrangement of the at least one passive layer is such that the mechanical neutral surface of the laminate structure is not coincident with the mid-plane of the at least one active layer.
• the active material is a transparent piezoelectric material.
• a window for controlling the propagation of vibrations and sounds comprises a laminated structure to be located within a window opening.
• the laminated structure comprises at least one layer of transparent active material, patterned electrodes disposed on opposite surfaces of each layer of transparent active material and at least one layer of transparent passive material.
• the active and passive layers and the patterned electrodes are bonded to each other forming the laminate structure.
• the window further comprises a signal conditioning network electrically connected to the patterned electrodes.
• the signal conditioning network may comprise a passive or active electrical network operative to dissipate a voltage differential across the electrodes.
• the signal conditioning network is operative to apply an electrical signal to the electrodes.
• the applied electrical signal is converted into a deformation of the active material thereby causing a sound to be radiated from the laminate structure.
• Figure lb schematically depicts a sound and vibration control system incorporating the laminate structure of Figure la.
• Figure 2a and 2b schematically depict exemplary electrode patterns according to one embodiment of the present invention.
• Figure 3 schematically depicts a sound and vibration control system according to another embodiment of the present invention.
• Figure 4 schematically depicts a sound and vibration control system according to another embodiment of the present invention.
• a vibration and sound control system comprising a laminate structure comprising layers of transparent active material, transparent patterned electrodes, and transparent passive material, and a signal conditioning network connected to the electrodes of the laminate structure.
• the system is operative to dissipate the energy present in an incident disturbance (e.g. , an incident sound wave or vibration) or to produce sound through application of a voltage to the patterned electrodes.
• incident disturbance in the following description denotes any force causing a deformation of the laminate structure such as a sound wave or vibration.
• the laminate structure of the system is transparent and is therefore suitable for incorporation into windows and the like, to create, for example, a "quiet window.” That is, a window which is controlled to actively damp sound waves and vibrations.
• Figure la shows a laminate structure 10 which includes a layer of active material 1 disposed between electrodes 2 and a passive layer 3.
• Active layer 1 is transparent to visible light and comprises a single sheet or multiple sheets of an active material.
• active material is any material which responds electrically (e.g. , produces a charge) to a mechanical stimulus (e.g. , a mechanical strain), or conversely which responds mechamcally (e.g. , produces a mechanical strain) to an electrical stimulus (e.g. voltage, current or electric field).
• Active materials are also referred to as induced strain actuators and may be, for example, a piezoelectric material, an electrostrictive material, a shape memory material or a magnetostrictive material.
• active layer 1 comprises a single sheet of the piezoelectric material polyvinylidene fluoride (PVDF).
• active layer 1 comprises a single sheet of the piezoelectric material zinc oxide (ZnO).
• Electrodes 2 are preferably patterned on to opposite surfaces of active layer 1 , and are operative to collect charge on the suiface of, or apply a voltage to, active layer 1. Electrodes 2 are composed of any suitable transparent conductive material. In one embodiment, electrodes 2 comprise Indium Tin Oxide (ITO). Suitable techniques for applying the patterned electrodes include inter alia adhering, sputtering and spraying. Although electrodes 2 are shown in Figure 1 as sheets for ease of drawing, they are preferably applied in specific patterns.
• ITO Indium Tin Oxide
• Passive layer 3 may comprise any transparent or translucent material such as glass, plastic, stained glass etc. Passive layer 3 helps enable the system to respond properly to an incident disturbance and provides protection to the underlying electrode structure. Passive layer 3 is configured so that the neutral surface C of the laminate structure (i.e. , the surface upon which the stress due to an incident disturbance will have zero magnitude), is offset from the mid ⁇ plane M of the active layer 1 (i.e. , the plane equidistant from opposite faces of the active layer). In this way laminate structure 10 of system 20 is given a nonzero moment arm between neutral surface C and mid-plane M of the active layer 1. Therefore an incident disturbance will give rise to a non-zero strain in active layer 1, thereby allowing active layer 1 to sense and respond to incident disturbances.
• the neutral surface C of the laminate structure i.e. , the surface upon which the stress due to an incident disturbance will have zero magnitude
• the mid ⁇ plane M of the active layer 1 i.e. , the plane equidistant from opposite faces of the active
• the layers 1-3 form laminate structure 10 in which the individual layers are bonded together so that the structural response of passive layer 3 is coupled to the structural response of active layer 1. That is, any disturbance incident upon passive layer 3 should be commumcated to active layer 1.
• the bonding is accomplished using any suitable method which will provide the proper coupling of the layers.
• cyanoacrylates or epoxies can be used to bond layers 1-3 together.
• Laminate structure 10 will generally be incorporated into a structure of a particular size and shape and having particular boundary conditions, for instance, a window or vehicle windshield. The size, shape and boundary conditions of a structure, among other variables, determine how the structure will respond to an incident disturbance.
• Mode shapes are the characteristic spatial deformations of a structure.
• the weighted collection of all mode shapes at which a particular structure will respond constitute the structure' s dynamic spatial response. Every structure (due to its size and boundary conditions) has certain mode shapes at which it is likely to respond to a disturbance. Further, certain of these mode shapes are better than others at producing or transmitting sound waves. For a structure of a known size and boundary conditions, it is possible to determine the mode shapes at which it is likely to respond and which of these mode shapes are likely to produce sound.
• electrodes are provided. According to one embodiment of the present invention.
• Electrodes 2 are patterned to couple active layer 1 to those portions of the dynamic response of laminate structure 10 which conduct sound. More specifically, electrodes 2 are patterned on active layer 1 in the areas in which the mode shapes of laminate structure 10 which are conducive to the production or transmission of sound, are likely to produce significant strain. Thus, if laminate structure 10 is subjected to an incident sound wave, laminate structure 10 will likely respond by deforming in one or more of its mode shapes likely to produce sound. This deformation causes a strain in active layer 1 thereby causing a charge distribution to accumulate on the faces of active layer 1.
• electrodes 2 have been patterned in the areas where the charge distribution is likely to be greatest (that is, areas corresponding to the mode curvatures of laminate structure 10) (the second derivative of a structure's mode shapes are its mode curvatures), active layer 1 is coupled into those modes most likely to contribute to noise transmission or radiation, and the accumulated charge distribution is efficiently converted to a voltage differential across the patterned electrodes.
• One method of designing the patterning of electrodes 2 is to first define a set of target modal coupling coefficients, and then choose an electrode distribution that best approximates those coefficients. In particular, one can define a positive semi-definite objective function of the form:
• C kj ⁇ g - are the target modal coupling coefficients
• c k are the computed modal coefficients for a particular electrode pattem with spatial parameters (e.g., locations) contained in the vector z.
• the electrode pattem that best approximates the target modal coupling coefficients minimizes J.
• a nonlinear, unconstrained optimization algorithm may be employed here, for example, the MATLAB ® function "ftnins" may be used to determine a distribution of electrodes resulting in c k which minimizes J.
• Other physically-motivated constraints may be imposed during the optimization process. For instance, the electrodes can not "spill over" the edges of the window, a rnini um spacing between segments may be imposed, and a minimum segment width may be defined.
• Figures 2a and 2b show exemplary pattems for electrode layers 2 designed using the above algorithm.
• Figure 2a shows an electrode pattem designed to control the (l-l)-(3-l) modes contributing to radiation and transmission of sound and vibrations in a rectangular plate with simply supported edges (an SSSS plate).
• Figure 2b shows an electrode pattem designed to control a broad contiguous range of modes contributing to radiation and transmission of sound and vibrations in an SSSS plate.
• Laminate structure 10 shown in Figure la may also be used to produce sound.
• One property of an active material is that it may act as an actuator as well as a sensor. Therefore, if a voltage is applied to patterned electrodes 2, that voltage will drive active layer 1 causing a deformation of the underlying structure.
• the laminate structure of Figure la is used to dissipate the energy out of an incident disturbance or to transmit or retransmit the incident disturbance by connecting the structure into a system such as is shown in Figure lb.
• Figure lb like elements have the same reference numerals as in Figure la.
• Figure lb shows laminate stmcture 10 of Figure la incorporated into a sound and vibration control system 20.
• System 20 includes laminate stmcture 10 and a signal conditioning network 5 electrically connected to electrodes 2.
• Signal conditioning network 5 is operative to dissipate a voltage appearing across electrodes 2 in response to an incident disturbance and can be any suitable network operative to do so.
• Signal conditioning network 5 can operate either passively or actively.
• network 5 is a passive network comprising standard electrical elements such as resistors, inductors, capacitors and operational amplifiers.
• Active layer 1 (which essentially acts as a capacitor, producing a charge) is electrically connected with network 5.
• the various circuit elements comprising network 5 convert the charge produced by active layer 1 into heat, thereby dissipating the energy out of an incident disturbance.
• network 5 is an active feedback network.
• Feedback network 5 operates to dissipate the energy in an incident disturbance by applying a second voltage across electrodes 2 in response to sensing a voltage caused by the incident disturbance.
• the second voltage is essentially superimposed with the first voltage thereby causing a new deformation in active layer 1 , which in rum gives rise to a third voltage across electrodes 2.
• the difference between the applied second voltage and the third voltage is then fed back through the network to arrive at a new voltage to apply to electrodes 2. This process is repeated until the response voltage is zero which indicates the applied voltage has caused a deformation of active layer 1 wliich cancels out the deformation due to the incident disturbance.
• network 5 is used to passively or actively detune laminate stmcture 10 so that it does not respond to incident disturbances and thus does not radiate or transmit sound.
• network 5 may be a passive network which sets up an impedance discontinuity in laminate stmcture 10 thus preventing the passage of energy through laminate stmcture 10.
• network 5 may be an active network which employs active feedback to detune laminate stmcture 10.
• network 5 is an active feedforward network.
• the feedforward network employs an extemal disturbance sensor to sense an incident disturbance. In response to an incident disturbance, the sensor generates a disturbance signal which is fed forward to signal conditioning network 5.
• Network 5 then produces a signal for application to electrodes 2 to cause a deformation of active layer 1 to cancel out the deformation caused by the incident disturbance.
• system 10 may include output device 6.
• Output device 6 is any device capable of further conveying the incident disturbance. In this embodiment, rather than dissipating the voltage across electrodes 2, the voltage is processed for output by signal conditioning network 5. The mode shapes causing the charge in active layer 1 , and thus the voltage across electrodes 2, are known because of the way electrodes 2 are patterned. Therefore, the network 5 can be tailored to enhance the disturbance signal (i.e., eliminate noise, boost signal, etc.). In this way, system 10 acts essentially as a microphone. Sounds are sensed by laminate stmcture 10 giving rise to a voltage across electrodes 2 and producing a disturbance signal. The resulting signal is processed by network 5 and output via output device 6. In one embodiment output device 6 is a speaker. In another embodiment, output device 6 is a txansmission circuit. In still another embodiment, output device 6 is a recording device.
• system 20 is used to produce sound.
• active layer 1 and the patterned electrodes can be used to produce sound.
• signal conditioning network 5 operates to apply an electrical signal (e.g. , voltage, current, etc.) to electrodes 2.
• the applied electrical signal will drive active layer 1 and cause it to deform in one of its mode shapes which produce sound.
• system 10 is essentially being used as a speaker.
• Figure 3 depicts another embodiment of vibration and sound control system 30.
• System 30 includes active layer 1 and electrodes 2 disposed between passive layers 3 and 4.
• layers 1-4 form a laminate stmcture 10 in which the individual layers are bonded together so that the stmctural response of passive layers 3 and 4 is coupled to the stmctural response of active layer 1. That is, any disturbance to passive layers 3 and 4 is communicated to active layer 1.
• FIG. 3 The configuration of the layers in Figure 3 provides proper response of laminate structure 10 to an incident vibration.
• Layers 1-4 are configured so that the neutral surface, C, of the laminate stmcture is offset from the mid-plane, M, of active layer 1. That is, one of layers 3 and 4 is thicker than the other.
• system 30 is given a nonzero moment arm between the neutral surface, C, and mid-plane, M, thereby allowing active layer 1 to be coupled into incident disturbances.
• Figure 4 shows an altemative embodiment of sound and vibration control system 40.
• like elements have the same reference numerals as in Figures 1 and 3.
• System 40 differs from systems 20 and 30 in that laminate stmcture 10 uses two active layers 1 which are separated from each other by passive layer 3. In this way neutral surface C lies within the center of passive layer 3 and thus provides the offset to create a nonzero moment arm for laminate stmcture 10.
• system 40 Operation of system 40 is analogous to that of systems 20 and 30 shown in Figures 1 and 3. However, in system 40, the operation of signal conditioning network 5 is slightly modified as compared to the operation with respect to systems 20 and 30 using a single active layer. For instance, if network 5 is operating passively to dissipate energy in an incident disturbance, active layers 1 are electrically connected to each other (in series or parallel), and the electrically connected active layers are connected to dissipative network 5. Network 5 then operates to dissipate the charge produced by the electrically connected active layers as explained with respect to network 5 in Figure lb.
• signal conditioning network 5 is operating as an active network to dissipate energy in an incident wave, then, typically, one of active layers 1 acts as a sensor for the incident disturbance and the other acts as an actuator.
• the sensing active layer feeds its signal to network 5.
• Network 5 receives the sensed signal and processes it to produce a cancelling signal.
• the cancelling signal is applied to the actuator active layer producing a deformation which will cancel the deformation caused by the incident disturbance.
• Modified system 40 may also be used in conjunction with an output device to retransmit the incident disturbance and as a sound source by modifying the network 5 as explained above.

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• Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Acoustics & Sound (AREA)
• Multimedia (AREA)
• Soundproofing, Sound Blocking, And Sound Damping (AREA)
• Piezo-Electric Transducers For Audible Bands (AREA)

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• 1996
  • 1996-10-30 EP EP96939549A patent/EP0858652A1/de not_active Withdrawn
  • 1996-10-30 AU AU76691/96A patent/AU7669196A/en not_active Abandoned
  • 1996-10-30 WO PCT/US1996/017727 patent/WO1997016817A1/en not_active Ceased

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