EP1234478A2 - Bending wave loudspeakers - Google Patents
Bending wave loudspeakersInfo
- Publication number
- EP1234478A2 EP1234478A2 EP00985445A EP00985445A EP1234478A2 EP 1234478 A2 EP1234478 A2 EP 1234478A2 EP 00985445 A EP00985445 A EP 00985445A EP 00985445 A EP00985445 A EP 00985445A EP 1234478 A2 EP1234478 A2 EP 1234478A2
- Authority
- EP
- European Patent Office
- Prior art keywords
- panels
- cavity
- loudspeaker
- fluid
- pair
- 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.)
- Withdrawn
Links
- 238000005452 bending Methods 0.000 title claims abstract description 12
- 239000012530 fluid Substances 0.000 claims abstract description 15
- 230000008878 coupling Effects 0.000 claims abstract description 5
- 238000010168 coupling process Methods 0.000 claims abstract description 5
- 238000005859 coupling reaction Methods 0.000 claims abstract description 5
- 238000007789 sealing Methods 0.000 claims abstract description 5
- 230000005855 radiation Effects 0.000 claims abstract description 3
- 230000005520 electrodynamics Effects 0.000 claims description 3
- 238000010276 construction Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 230000005284 excitation Effects 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 125000006850 spacer group Chemical group 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
- H04R1/227—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired frequency characteristic only using transducers reproducing the same frequency band
Definitions
- the invention relates to loudspeakers and more particularly to bending wave panel -form loudspeakers, e.g. resonant bending wave panel speakers as exemplified by the disclosure in W097/09842 of New Transducers Limited. Loudspeakers as exemplified in WO97/09842 have become known as distributed mode loudspeakers.
- a loudspeaker comprising a spaced pair of vibrating diaphragms defining a cavity between them. It is also known from O98/16409 to provide a vehicle sun visor as a loudspeaker comprising a spaced pair of vibrating panels defining between them a cavity m which piezoelectric transducers for exciting the panels are located. Further more it is known from DE 298,11,727 Ul to provide a loudspeaker comprising a spaced pair of panels defining a cavity m which transducers for exciting the two panels are located.
- bending wave panel-form loudspeaker comprises a spaced pair of panels defining between them a shallow fluid cavity, a body member surrounding the pair of panels and suspending the panels by their edges, means sealing the cavity and vibration transducers m the fluid cavity and arranged to drive the respective panels, the electrical connections to the transducers being at least partially m antiphase such that the predominant motion of the panels is m phase to provide a degree of dipole radiation property for the loudspeaker, and the cavity being such that the gap between the panels is in the range 2 to 25 mm such that the shallow cavity provides conditions in which fluid coupling dynamics and behaviour is asserted between the pair of panels due to the fluid layer between them.
- the vibration transducers may be electrodynamic inertial devices.
- the body member which may be in the form of a frame or a shim between the panels, may clamp the panel edges.
- the body member may form the cavity sealing means. More than one vibration exciter may be fixed to the inside face of each panel .
- the panels may be resonant acoustic radiators, e.g. as disclosed in O97/09842
- the invention is an advertising display comprising a loudspeaker as described above.
- Figure 2 is a graph of the frequency response of a typical loudspeaker, formed as shown in Figure 1.
- a distributed mode loudspeaker (1) comprising two resonant bending wave panels (2) clamped by their edges (4) back to back into a frame (3) , and operating as a dipole sound radiator.
- the two panels and the frame define a sealed shallow cavity (5) .
- Each of the two (front and back) panels is driven by one or more electrodynamic inertial transducers exciters (6), mounted on the inwardly facing surfaces (7) of the panels so that the exciters (6) are mounted in the cavity (5), and generating distributed mode type bending waves in each of the panels, e.g. as described in WO97/09842.
- the exciters of the front and rear panel are connected to be electrically out of phase, in order to form a mechanical dipole system, meaning that the mechanical excursion of the front and rear panel is in phase.
- the two panels (12) are clamped to the frame (3) around their entire perimeters, to create a small sealed air volume that can be described as a fluid system for a stiff coupling between the front and the pack panel, preventing any unwanted front to back panel interaction caused by an otherwise possible resonance in the enclosure.
- the fluid coupling between the front and back panel also supports the mechanical dipole excursion due to its high mechanical spring stiffness.
- the cavity depth is 6 mm. It is envisaged that the loudspeakers of the present invention might find application in relation to inexpensive signboards and advertising displays, e.g.
- POP point of purchase
- the loudspeakers forming an advertising display board with the additional feature of an audio output to enhance the display appeal .
- display boards may be relatively large, e.g. around one metre square, and in such a case, the shallow cavity between the panels may be up to 25 mm in depth.
- Figure 2 shows the frequency response curve of a panel constructed according to Figure 1.
- Two identical panels (590 x 495 x 3 mm) are mounted on a rigid spacer frame of 6 mm thickness and form a completely sealed thin closed loudspeaker. Each panel is driven by two 13 mm exciters with a total nominal impedance of 2 ohms.
- the front and rear exciter configurations are in series connection and electrically out of phase, giving a total nominal impedance of the system of 4 ohm.
- the sound pressure level measurement shown in Figure 2 is on axis at 0.5 m with 2.83 Vrms input .
- the invention thus provides a useful alternative to known embedded bending wave panel -form loudspeakers.
- the benefit is an economical two sided bending wave speaker system of desirable thinness which is broadly equivalent to a standard single panel speaker but where the method of excitation is wholly concealed within the speaker assembly.
- signboards may have information on both sides of an assembly without obstruction.
- exciter means is wholly protected from damage, environmental and/or casual .
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Acoustics & Sound (AREA)
- Signal Processing (AREA)
- Multimedia (AREA)
- Health & Medical Sciences (AREA)
- Otolaryngology (AREA)
- Diaphragms For Electromechanical Transducers (AREA)
- Piezo-Electric Transducers For Audible Bands (AREA)
Abstract
Description
Claims
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB9928456 | 1999-12-02 | ||
GBGB9928456.4A GB9928456D0 (en) | 1999-12-02 | 1999-12-02 | Loudspeakers |
PCT/GB2000/004510 WO2001041498A2 (en) | 1999-12-02 | 2000-11-28 | Bending wave loudspeakers |
Publications (1)
Publication Number | Publication Date |
---|---|
EP1234478A2 true EP1234478A2 (en) | 2002-08-28 |
Family
ID=10865539
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP00985445A Withdrawn EP1234478A2 (en) | 1999-12-02 | 2000-11-28 | Bending wave loudspeakers |
Country Status (5)
Country | Link |
---|---|
EP (1) | EP1234478A2 (en) |
CN (1) | CN1390429A (en) |
AU (1) | AU2186401A (en) |
GB (1) | GB9928456D0 (en) |
WO (1) | WO2001041498A2 (en) |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB0221503D0 (en) * | 2002-09-17 | 2002-10-23 | 1 Ltd | Loudspeaker |
CN1823549A (en) * | 2003-07-16 | 2006-08-23 | 皇家飞利浦电子股份有限公司 | Panel-shaped acoustic wave generator |
KR102608137B1 (en) | 2018-09-20 | 2023-11-29 | 엘지디스플레이 주식회사 | Display apparatus |
Family Cites Families (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
UA51671C2 (en) * | 1995-09-02 | 2002-12-16 | Нью Транзд'Юсез Лімітед | Acoustic device |
GB9621523D0 (en) * | 1996-10-16 | 1996-12-04 | Noise Cancellation Tech | A flat panel loudspeaker arrangement and hands free telephone system using the same |
NZ330777A (en) * | 1998-06-22 | 1999-08-30 | Slab Technology Ltd | Loudspeaker with a planar diaphragm having a bending strength along one axis which is greater that along a second axis perpendicular to the first axis |
DE29923450U1 (en) * | 1998-06-22 | 2000-09-28 | Slab Technology Ltd Albany | speaker |
-
1999
- 1999-12-02 GB GBGB9928456.4A patent/GB9928456D0/en not_active Ceased
-
2000
- 2000-11-28 EP EP00985445A patent/EP1234478A2/en not_active Withdrawn
- 2000-11-28 CN CN 00815692 patent/CN1390429A/en active Pending
- 2000-11-28 AU AU21864/01A patent/AU2186401A/en not_active Abandoned
- 2000-11-28 WO PCT/GB2000/004510 patent/WO2001041498A2/en not_active Application Discontinuation
Non-Patent Citations (1)
Title |
---|
See references of WO0141498A3 * |
Also Published As
Publication number | Publication date |
---|---|
CN1390429A (en) | 2003-01-08 |
WO2001041498A3 (en) | 2002-05-10 |
GB9928456D0 (en) | 2000-01-26 |
WO2001041498A2 (en) | 2001-06-07 |
AU2186401A (en) | 2001-06-12 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
Free format text: ORIGINAL CODE: 0009012 |
|
17P | Request for examination filed |
Effective date: 20020620 |
|
AK | Designated contracting states |
Kind code of ref document: A2 Designated state(s): AT BE CH CY DE DK ES FI FR GB GR IE IT LI LU MC NL PT SE TR |
|
AX | Request for extension of the european patent |
Free format text: AL;LT;LV;MK;RO;SI |
|
GRAH | Despatch of communication of intention to grant a patent |
Free format text: ORIGINAL CODE: EPIDOS IGRA |
|
RTI1 | Title (correction) |
Free format text: BENDING WAVE LOUDSPEAKER |
|
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN |
|
18D | Application deemed to be withdrawn |
Effective date: 20030604 |