EP1070437A1 - Acoustic device - Google Patents
Acoustic deviceInfo
- Publication number
- EP1070437A1 EP1070437A1 EP99914672A EP99914672A EP1070437A1 EP 1070437 A1 EP1070437 A1 EP 1070437A1 EP 99914672 A EP99914672 A EP 99914672A EP 99914672 A EP99914672 A EP 99914672A EP 1070437 A1 EP1070437 A1 EP 1070437A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- panel
- cavity
- acoustic
- acoustic device
- enclosure
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 230000005855 radiation Effects 0.000 claims abstract description 30
- 238000005452 bending Methods 0.000 claims abstract description 9
- 238000000034 method Methods 0.000 claims abstract description 4
- 230000008878 coupling Effects 0.000 claims description 8
- 238000010168 coupling process Methods 0.000 claims description 8
- 238000005859 coupling reaction Methods 0.000 claims description 8
- 239000012530 fluid Substances 0.000 claims description 6
- 230000002093 peripheral effect Effects 0.000 claims 1
- 230000004044 response Effects 0.000 description 32
- 238000005259 measurement Methods 0.000 description 15
- 230000000694 effects Effects 0.000 description 14
- 230000006870 function Effects 0.000 description 11
- 230000008901 benefit Effects 0.000 description 7
- 238000001228 spectrum Methods 0.000 description 7
- 230000003993 interaction Effects 0.000 description 6
- 239000004417 polycarbonate Substances 0.000 description 6
- 239000000725 suspension Substances 0.000 description 6
- 238000012360 testing method Methods 0.000 description 6
- 238000006073 displacement reaction Methods 0.000 description 5
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 4
- 229910052799 carbon Inorganic materials 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 238000004088 simulation Methods 0.000 description 4
- 238000013016 damping Methods 0.000 description 3
- 229920001821 foam rubber Polymers 0.000 description 3
- 229920000515 polycarbonate Polymers 0.000 description 3
- 230000006835 compression Effects 0.000 description 2
- 238000007906 compression Methods 0.000 description 2
- 238000009795 derivation Methods 0.000 description 2
- 238000013461 design Methods 0.000 description 2
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- 230000006872 improvement Effects 0.000 description 2
- 230000007246 mechanism Effects 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 238000012546 transfer Methods 0.000 description 2
- 230000009466 transformation Effects 0.000 description 2
- 229920001875 Ebonite Polymers 0.000 description 1
- 229920005830 Polyurethane Foam Polymers 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 238000007792 addition Methods 0.000 description 1
- 230000004075 alteration Effects 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- 239000004411 aluminium Substances 0.000 description 1
- 230000003466 anti-cipated effect Effects 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 230000003416 augmentation Effects 0.000 description 1
- 230000003190 augmentative effect Effects 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 239000003990 capacitor Substances 0.000 description 1
- 238000005266 casting Methods 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 229920001971 elastomer Polymers 0.000 description 1
- 230000005520 electrodynamics Effects 0.000 description 1
- 230000005284 excitation Effects 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 239000003365 glass fiber Substances 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 230000002452 interceptive effect Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000013178 mathematical model Methods 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 238000003012 network analysis Methods 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 229920003023 plastic Polymers 0.000 description 1
- 239000011496 polyurethane foam Substances 0.000 description 1
- 230000002787 reinforcement Effects 0.000 description 1
- 239000012780 transparent material Substances 0.000 description 1
- 238000012795 verification Methods 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R7/00—Diaphragms for electromechanical transducers; Cones
- H04R7/02—Diaphragms for electromechanical transducers; Cones characterised by the construction
- H04R7/04—Plane diaphragms
- H04R7/045—Plane diaphragms using the distributed mode principle, i.e. whereby the acoustic radiation is emanated from uniformly distributed free bending wave vibration induced in a stiff panel and not from pistonic motion
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R1/00—Details of transducers, loudspeakers or microphones
- H04R1/20—Arrangements for obtaining desired frequency or directional characteristics
- H04R1/22—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired frequency characteristic only
- H04R1/24—Structural combinations of separate transducers or of two parts of the same transducer and responsive respectively to two or more frequency ranges
Definitions
- the invention relates to acoustic devices and more particularly, but not exclusively, to loudspeakers incorporating resonant multi-mode panel acoustic radiators, e.g. of the kind described in our International application O97/09842. Loudspeakers as described in O97/09842 have become known as distributed mode (DM) loudspeakers.
- DM distributed mode
- DML Distributed mode loudspeakers
- the product may with advantage be light, thin and unobtrusive.
- an acoustic device comprises a resonant multi-mode acoustic resonator or radiator panel having opposed faces, means defining a cavity enclosing at least a portion of one panel face and arranged to contain acoustic radiation from the said portion of the panel face, wherein the cavity is such as to modify the modal behaviour of the panel.
- the cavity may be sealed.
- a vibration exciter may be arranged to apply bending wave vibration to the resonant panel to produce an acoustic output, so that the device functions as a loudspeaker.
- the cavity size may be such as to modify the modal 3
- the cavity may be shallow.
- the cavity may be sufficiently shallow that the distance between the internal cavity face adjacent to the said one panel face and the one panel face is sufficiently small as to cause fluid coupling to the panel.
- the resonant modes in the cavity can comprise cross modes parallel to the panel, i.e. which modulate along the panel, and perpendicular modes at right angles to the panel.
- the cavity is sufficiently shallow that the cross modes (X,Y) are more significant in modifying the modal behaviour of the panel than the perpendicular modes (Z).
- the frequencies of the perpendicular modes can lie outside the frequency range of interest.
- the ratio of the cavity volume to panel area (ml: cm 2 ) may be less than 10:1, say in the range about 10:1 to 0.2:1.
- the panel may be terminated at its edges by a generally conventional resilient surround.
- the surround may resemble the roll surround of a conventional pistonic drive unit and may comprise one or more corrugations.
- the resilient surround may comprise foam rubber strips.
- edges of the panel may be clamped in the enclosure, e.g. as described in our co-pending PCT patent application PCT/GB99/00848 dated 30 March 1999.
- Such an enclosure may be considered as a shallow tray containing a fluid whose surface may be considered to have wave-like behaviour and whose specific properties depend on both the fluid (air) and the dimensional or volume box 4
- the panel is placed in coupled contact with this active wave surface and the surface wave excitation of the panel excites the fluid. Conversely the natural wave properties of the fluid interact with the panel, so modifying its behaviour. This is a complex coupled system with new acoustic properties in the field.
- Subtle variations in the modal behaviour of the panel may be achieved by providing baffling, e.g. a simple baffle, in the enclosure and/or by providing frequency selective absorption in the enclosure.
- baffling e.g. a simple baffle
- the invention is a method of modifying the modal behaviour of a resonant panel loudspeaker or resonator, comprising bringing the resonant panel into close proximity with a boundary surface to define a resonant cavity therebetween.
- Figure 1 is a cross section of a first embodiment of sealed box resonant panel loudspeaker
- Figure 2 is a cross-sectional detail, to an enlarges scale, of the embodiment of Figure 1;
- Figure 3 is a cross section of a second embodiment of sealed box resonant panel loudspeaker;
- Figure 4 shows the polar response of a DML free-radiating on both sides;
- Figure 5 shows a comparison between the sound pressure level in Free Space (solid line) and with the DML arranged 35mm from the wall (dotted line) ;
- Figure 6 shows a comparison between the acoustic power of a DML in free space (dotted line) and with a baffle around the panel between the front and rear;
- Figure 7 shows a loudspeaker according to the invention
- Figure 8 shows a DML panel system
- Figure 10 illustrates a single plate eigen-function
- Figure 11 shows the magnitudes of the frequency response of the first ten in-vacuum panel modes
- Figure 12 shows the magnitudes of the frequency response of the same modes in a loudspeaker according to the embodiment of the invention
- Figure 13 shows the effect of the enclosure on the panel velocity spectrum
- Figure 14 illustrates two mode shapes
- Figure 15 shows the frequency response of the reactance
- Figure 16 illustrates panel velocity measurement
- Figure 17 illustrates the microphone set up for the measurements
- Figure 18 shows the mechanical impedance for various panels
- Figure 19 shows the power response of various panels
- Figure 20 shows the polar response of various panels
- Figure 21 shows a microphone set up for measuring the internal pressure in the enclosure
- Figure 22 shows the internal pressure contour
- Figure 23 shows the internal pressure measured using the array of Figure 21
- Figure 24 shows the velocity and displacement of various panels
- Figure 25 shows the velocity spectrum of an A5 panel 6
- Figure 26 shows the velocity spectrum of another A5 panel in free space and enclosed
- Figure 27 shows the power response of an A2 panel in an enclosure of two depths
- Figure 28 illustrates equalisation using filters.
- a sealed box loudspeaker 1 comprises a box-like enclosure 2 closed at its front by a resonant panel-form acoustic radiator 5 of the kind described in
- the radiator 5 is energised by a vibration exciter 4 and is sealed to the enclosure round its periphery by a resilient suspension 6.
- the suspension 6 comprises opposed resilient strips 7, e.g. of foam rubber mounted in respective L-section frame members 9,10 which are held together by fasteners 11 to form a frame 8.
- the interior face 14 of the back wall 3 of the enclosure 2 is formed with stiffening ribs 12 to minimise vibration of the back wall.
- the enclosure may be a plastics moulding or a casting incorporating the stiffening ribs .
- the panel in this embodiment may be of A2 size and the depth of the cavity 13 may be 90mm.
- the loudspeaker embodiment of Figure 3 is generally similar to that of Figures 1 and 2, but here the radiator panel 5 is mounted on a single resilient strip suspension
- radiator panel size may be A5 and the cavity depth around 3 or 4 mm.
- Figures 1 to 3 relate to loudspeakers, it would equally be possible to produce an acoustic resonator for modifying the acoustic behaviour of a space, e.g. a meeting room or auditorium, using devices of the general kind of Figures 1 to 3, but which omit the vibration exciter 4.
- a panel in this form of deployment can provide a very useful bandwidth with quite a small enclosure volume with respect to the diaphragm size, as compared with piston speakers.
- the mechanisms responsible for the minimal interaction of this boundary with the distributed mode action are examined and it is further shown that in general a simple passive equalisation network may be all that is required to produce a flat power response. It is also demonstrated that in such a manifestation, a DML can produce a near-ideal hemispherical directivity pattern over its working frequency range into a 2Pi space.
- a closed form solution is presented which is the result of solving the bending wave equations for the coupled system of the panel and enclosure combination.
- the system acoustic impedance function is derived and is in turn used to calculate the effect of the coupled enclosure on the eigen-frequencies, and predicting the relevant shifts and additions to the plate modes.
- Figure 4 illustrates a typical polar response of a free DML. Note that the reduction of pressure in the plane of the panel is due to the cancellation effect of acoustic radiation at or near the edges.
- a free DML is brought near a boundary, in particular parallel with the boundary surface, acoustic interference starts to take place as the distance to the surface is reduced below about 15cm, for a panel of approximately 500 cm 2 surface area.
- the effect varies in its severity and nature with the distance to the boundary as well as the panel size.
- the result nonetheless is invariably a reduction of low frequency extension, peaking of response in the lower midrange region, and some aberration in the midrange and lower treble registers as shown in the example of Figure 5. Because of this, and despite the fact that the peak can easily be compensated for, application of a 'free' DML near a boundary becomes rather restrictive.
- FIG. 7 The system under analysis is shown schematically in Figure 7.
- the front side of the panel radiates into free space, whilst the other side is loaded with an enclosure.
- This coupled system may be treated as a network of velocities and pressures are shown in the block diagram of Figure 8.
- the components are, from left to right; the electromechanical driving section, the modal system of the panel, and the acoustical systems.
- the normal velocity of the bending-wave field across a vibrating panel is responsible for its acoustic radiation.
- This radiation leads to a reacting force which modifies the panel vibration.
- the radiation impedance which is the reacting element, is normally insignificant as compared with the mechanical impedance of the panel.
- the effect of acoustic impedance due to its rear radiation is no longer small, and in fact it will modify and add to the scale of the modality of the panel.
- This coupling is equivalent to a mechanoacoustical closed loop system in which the reacting sound pressure is due to the velocity of the panel itself.
- This pressure modifies the modal distribution of the bending wave field which in turn has an effect on the sound pressure response and directivity of the panel.
- L B is the bending rigidity differential operator of fourth order in x and y, v is the normal component of the bending wave velocity.
- ⁇ is the mass per unit area and ⁇ 12
- the panel is the driving frequency.
- the panel is disturbed by the mechanical driving pressure, p m , and the acoustic reacting sound pressure field, p a , Figure 7.
- Each term of the series in equation (1) is called a modal velocity, or, a "mode" in short.
- the model decomposition is a generalised Fourier transform whose eigen-functions ⁇ p ⁇ share the orthogonality property with the sine and cosine functions associated with Fourier transformation.
- the orthogonality property of ⁇ pi is a necessary condition to allow appropriate solutions to the differential equation (2) .
- the set of eigen-functions and their parameters are found from the homogenous version of equation (2) i.e. after switching off the driving forces. In this case the panel can only vibrate at its natural frequencies or the so-called eigen-frequencies, GJ. , in order to satisfy the boundary conditions.
- ⁇ P ⁇ ( X , y ) is the value of the i th plate eigen-function at the position where the velocity is observed.
- ⁇ p ⁇ ( XO ,yo) is the eigen-function at the position where the driving force F p ⁇ ⁇ J(a) is applied to the panel.
- the driving force includes the transfer functions of the electromechanical components associated with the driving actuator at (x 0 ,y 0 ), as for example exciters, suspensions, etc. Since the driving force depends on the panel velocity at the driving point, a similar feedback situation as with the mechanoacoustical coupling exists at the drive point (s), albeit the effect is quite small in practice. 13
- Figure 10 gives an example of the velocity magnitude distribution of a single eigen-function across a DML panel.
- the black lines are the nodal lines where the velocity is zero. With increasing mode index the velocity pattern becomes increasingly more complex. For a medium sized panel approximately 200 modes must be summed in order to cover the audio range.
- Y p ⁇ as described in equation (3), depends on the driving frequency, the plate eigen-value and, most important in the context of this paper, on the acoustic impedance of the enclosure together with the impedance due to the free field radiation.
- Figure 11 shows the magnitudes of the frequency response of the in-vacuum Ypi(j ⁇ ) for the first ten modes of a panel, when clamped at the edges. The panel eigen-frequencies coincide with the peaks of these curves. If the same panel is now mounted onto an enclosure, the modes will not only be shifted in frequency but also modified, as seen in Figure 12. This happens as a result of the interaction between the two modal systems of the panel and the enclosure, where the modal admittance of the total system is no longer a second order function as in the in-vacuum case. In fact, the denominator of equation (3) could be expanded in a polynomial of high order, which will reflect the resulting extended characteristic function.
- the frequency response graphs of Figure 13 shows the effect of the enclosure on the panel velocity spectrum.
- the two frequency response curves are calculated under identical drive condition, however, the left-hand graph displays the in-vacuum case, whilst the right hand graph shows the velocity when both sides of the panel are loaded with an enclosure.
- a double enclosure was used in this example in order to exclude the radiation impedance of air.
- the observation point is at the drive point of the exciter.
- the mechanical radiation impedance is the ratio of the reacting force, due to radiation, and the panel velocity.
- the radiation impedance can be regarded 10 as constant across the panel area and may be expressed in terms of the acoustical radiated power P a ⁇ of a single mode.
- the modal radiation impedance of the i th mode may be described by equation (5) .
- ⁇ v x > is the mean velocity across the panel associated with the i th mode. Since this value is squared and therefore always positive and real, the properties of the
- a positive reactance is caused by the presence of an 16
- acoustical mass This is typical, for example, of radiation into free space.
- a negative reactance of Z ma i is indicative of the presence of a sealed enclosure with its equivalent stiffness.
- a 'mass' type radiation impedance is caused by a movement of air without compression, whereas a 'spring' type impedance exists when air is compressed without shifting it.
- Figure 15 shows the frequency response of the imaginary part of the enclosure radiation impedance.
- the left-hand graph displays a 'spring-type' reactance, typically produced by a symmetrical panel-mode. Up to the first enclosure eigen-frequency the reactance is mostly negative. In-vacuum eigen-frequencies of the panel, which 17
- the right diagram displays a 'mass-type' reactance behaviour, typically produced by an asymmetrical panel mode. If the enclosure is sealed and has a rigid wall parallel to the panel surface, as in our case here, then the mechanical radiation impedance for the i th -plate mode is (5) :
- the indices, k and 1 are the enclosure cross-mode numbers in x and y direction, where Ldx and Ld y are enclosure dimensions in this plane.
- Ao is the area of the panel and
- Ad is cross-sectional area of the enclosure in the x and y plane . 18
- Equation (6) is a complicated function, which describes the interaction of the panel modes and the enclosure modes in detail.
- Equation (6) is a complicated function, which describes the interaction of the panel modes and the enclosure modes in detail.
- Equation (8) is the well known driving point impedance of a closed duct (6) . If the product k z . Ldz « 1 then a further simplification can be made as follows.
- the first set 'A' was selected as a small A5 size panel of 149mm x 210mm with three different bulk mechanical properties. These were A5-1, polycarbonate skin on polycarbonate honeycomb; A5-2 carbon fibre on Rohacell; and A5-3, Rohacell without skin. Set 'B' was chosen to be eight times larger, approximately to A2 size of 420mm x 592mm. A2-1 was constructed with glass fibre skin on polycarbonate honeycomb core, whilst A2-2 was carbon fibre skin on aluminium honeycomb. Table 1 lists the bulk properties of these objects. Actuation was achieved by a single electrodynamic moving coil exciter at the optimum position. Two exciter types were used, where they suited most the 20
- Panels were mounted onto a back enclosure with adjustable depth using a soft polyurethane foam for suspension and acoustic seal.
- the enclosure depth was made adjustable on 16,28,40 and 53mm for set 'A' and on 20,50,95 and 130mm for set 'B' panels.
- Various measurements were carried out at different enclosure depths for every test case and result documented.
- Panel velocity and displacement were measured using a Laser Vibrometer.
- the frequency range of interest was covered with a linear frequency scale of 1600 points.
- the set-up shown in Figure 16 was used to measure the panel mechanical impedance by calculating the ratio of the applied force to the panel velocity at the drive point.
- a special jig was made to allow the measurement of the internal pressure of the enclosure at nine predetermined points as shown in Figure 21.
- the microphone was inserted in the holes provided within the back-plate of an A5 enclosure jig at a predetermined depth, while the other eight position holes were tightly blocked with hard rubber grommets.
- the microphone was mechanically isolated from the enclosure by an appropriate rubber grommet during the measurement.
- Figure 25b shows the same panel as in Figure 25a but this time loaded with two identical enclosures, one on each side of the panel, with the same cross-section as the panel and a depth of 24mm.
- a double enclosure was designed and used in order to exclude the radiation impedance of free field on one side of the panel and make the experiment independent of the free field radiation impedance. It is important to note that this laboratory set-up was used for theory verification only.
- Power response measurements were found to be most useful when working with the enclosed DM system, in order to observe the excessive energy region that may need compensation. This is in line with other work done on DM loudspeakers, in which it has been found that the power response is the most representative acoustic measurement correlating well to the subjective performance of a DML. Using the power response, it was found that in practice a simple band-pass or a single pole high-pass filter is all that is needed to equalise the power response in this region.
Landscapes
- Engineering & Computer Science (AREA)
- Acoustics & Sound (AREA)
- Signal Processing (AREA)
- Physics & Mathematics (AREA)
- Multimedia (AREA)
- Otolaryngology (AREA)
- Health & Medical Sciences (AREA)
- Details Of Audible-Bandwidth Transducers (AREA)
- Obtaining Desirable Characteristics In Audible-Bandwidth Transducers (AREA)
- Diaphragms For Electromechanical Transducers (AREA)
- Measurement Of Mechanical Vibrations Or Ultrasonic Waves (AREA)
- Soundproofing, Sound Blocking, And Sound Damping (AREA)
- Fittings On The Vehicle Exterior For Carrying Loads, And Devices For Holding Or Mounting Articles (AREA)
- Piezo-Electric Transducers For Audible Bands (AREA)
Abstract
Description
Claims
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GBGB9807316.6A GB9807316D0 (en) | 1998-04-07 | 1998-04-07 | Loudspeaker |
GB9807316 | 1998-04-07 | ||
PCT/GB1999/001048 WO1999052322A1 (en) | 1998-04-07 | 1999-04-06 | Acoustic device |
Publications (2)
Publication Number | Publication Date |
---|---|
EP1070437A1 true EP1070437A1 (en) | 2001-01-24 |
EP1070437B1 EP1070437B1 (en) | 2006-07-26 |
Family
ID=10829902
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP99914672A Expired - Lifetime EP1070437B1 (en) | 1998-04-07 | 1999-04-06 | Acoustic device |
Country Status (25)
Country | Link |
---|---|
EP (1) | EP1070437B1 (en) |
JP (1) | JP2002511681A (en) |
KR (1) | KR20010042491A (en) |
CN (1) | CN100417304C (en) |
AR (1) | AR019019A1 (en) |
AT (1) | ATE334567T1 (en) |
AU (1) | AU3340099A (en) |
BG (1) | BG104811A (en) |
BR (1) | BR9909496A (en) |
CA (1) | CA2326193A1 (en) |
DE (1) | DE69932507T2 (en) |
EA (1) | EA200001038A1 (en) |
GB (1) | GB9807316D0 (en) |
HK (1) | HK1030327A1 (en) |
HU (1) | HUP0103916A3 (en) |
ID (1) | ID27518A (en) |
IL (1) | IL138310A0 (en) |
NO (1) | NO20005056L (en) |
NZ (1) | NZ506732A (en) |
PL (1) | PL343440A1 (en) |
SK (1) | SK14932000A3 (en) |
TR (1) | TR200002920T2 (en) |
TW (1) | TW462201B (en) |
WO (1) | WO1999052322A1 (en) |
ZA (1) | ZA200004675B (en) |
Families Citing this family (34)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB0114501D0 (en) * | 2001-06-14 | 2001-08-08 | New Transducers Ltd | Mobile telephone |
DE50115744D1 (en) * | 2001-07-13 | 2011-01-27 | Harman Becker Automotive Sys | PANEL SPEAKER |
US8284955B2 (en) | 2006-02-07 | 2012-10-09 | Bongiovi Acoustics Llc | System and method for digital signal processing |
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KR102663406B1 (en) | 2016-04-04 | 2024-05-14 | 엘지디스플레이 주식회사 | Sound generation actuator of panel vibration type and double faced display device with the same |
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KR101704517B1 (en) * | 2016-03-28 | 2017-02-09 | 엘지디스플레이 주식회사 | Display device for generating sound by panel vibration type |
US10412500B2 (en) | 2016-03-28 | 2019-09-10 | Lg Display Co., Ltd. | Actuator fixing device and panel vibration type sound-generating display device including the same |
US11211043B2 (en) | 2018-04-11 | 2021-12-28 | Bongiovi Acoustics Llc | Audio enhanced hearing protection system |
US10959035B2 (en) | 2018-08-02 | 2021-03-23 | Bongiovi Acoustics Llc | System, method, and apparatus for generating and digitally processing a head related audio transfer function |
US20200388265A1 (en) * | 2019-06-10 | 2020-12-10 | Toyota Motor Engineering & Manufacturing North America, Inc. | Sound isolation device |
KR102215716B1 (en) * | 2019-10-21 | 2021-02-18 | 삼원액트 주식회사 | Panel with sound reproduction |
AT525365B1 (en) | 2022-05-25 | 2023-03-15 | Cale3D Prime Gmbh | Electroacoustic Transducer |
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US4914750A (en) * | 1987-07-13 | 1990-04-03 | Avm Hess, Inc. | Sound transducer |
CN1164144C (en) * | 1995-09-02 | 2004-08-25 | 新型转换器有限公司 | Inertial vibrative transducer |
ATE179045T1 (en) * | 1995-09-02 | 1999-04-15 | New Transducers Ltd | INERTIAL VIBRATION TRANSDUCER |
UA51671C2 (en) * | 1995-09-02 | 2002-12-16 | Нью Транзд'Юсез Лімітед | Acoustic device |
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1998
- 1998-04-07 GB GBGB9807316.6A patent/GB9807316D0/en not_active Ceased
-
1999
- 1999-04-06 AT AT99914672T patent/ATE334567T1/en not_active IP Right Cessation
- 1999-04-06 NZ NZ506732A patent/NZ506732A/en unknown
- 1999-04-06 EP EP99914672A patent/EP1070437B1/en not_active Expired - Lifetime
- 1999-04-06 KR KR1020007011113A patent/KR20010042491A/en not_active Application Discontinuation
- 1999-04-06 HU HU0103916A patent/HUP0103916A3/en unknown
- 1999-04-06 AR ARP990101546A patent/AR019019A1/en unknown
- 1999-04-06 SK SK1493-2000A patent/SK14932000A3/en unknown
- 1999-04-06 ID IDW20001944A patent/ID27518A/en unknown
- 1999-04-06 WO PCT/GB1999/001048 patent/WO1999052322A1/en active IP Right Grant
- 1999-04-06 JP JP2000542951A patent/JP2002511681A/en not_active Abandoned
- 1999-04-06 BR BR9909496-7A patent/BR9909496A/en not_active Application Discontinuation
- 1999-04-06 CA CA002326193A patent/CA2326193A1/en not_active Abandoned
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- 1999-04-06 AU AU33400/99A patent/AU3340099A/en not_active Abandoned
- 1999-04-06 DE DE69932507T patent/DE69932507T2/en not_active Expired - Lifetime
- 1999-04-12 TW TW088105770A patent/TW462201B/en not_active IP Right Cessation
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2000
- 2000-09-06 ZA ZA200004675A patent/ZA200004675B/en unknown
- 2000-09-29 BG BG104811A patent/BG104811A/en unknown
- 2000-10-06 NO NO20005056A patent/NO20005056L/en not_active Application Discontinuation
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2001
- 2001-02-14 HK HK01101083A patent/HK1030327A1/en not_active IP Right Cessation
Non-Patent Citations (1)
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GB9807316D0 (en) | 1998-06-03 |
NZ506732A (en) | 2002-11-26 |
BR9909496A (en) | 2000-12-12 |
ID27518A (en) | 2001-04-12 |
CN100417304C (en) | 2008-09-03 |
NO20005056D0 (en) | 2000-10-06 |
TW462201B (en) | 2001-11-01 |
BG104811A (en) | 2001-07-31 |
HUP0103916A2 (en) | 2002-03-28 |
AR019019A1 (en) | 2001-12-26 |
HUP0103916A3 (en) | 2002-12-28 |
SK14932000A3 (en) | 2001-05-10 |
PL343440A1 (en) | 2001-08-13 |
CA2326193A1 (en) | 1999-10-14 |
CN1296719A (en) | 2001-05-23 |
AU3340099A (en) | 1999-10-25 |
EA200001038A1 (en) | 2001-04-23 |
ZA200004675B (en) | 2002-02-27 |
HK1030327A1 (en) | 2001-04-27 |
ATE334567T1 (en) | 2006-08-15 |
KR20010042491A (en) | 2001-05-25 |
NO20005056L (en) | 2000-12-06 |
IL138310A0 (en) | 2001-10-31 |
DE69932507T2 (en) | 2007-07-19 |
TR200002920T2 (en) | 2000-12-21 |
WO1999052322A1 (en) | 1999-10-14 |
JP2002511681A (en) | 2002-04-16 |
EP1070437B1 (en) | 2006-07-26 |
DE69932507D1 (en) | 2006-09-07 |
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