EP1174001B1 - Bending- wave panel loudspeakers - Google Patents
Bending- wave panel loudspeakers Download PDFInfo
- Publication number
- EP1174001B1 EP1174001B1 EP00927409A EP00927409A EP1174001B1 EP 1174001 B1 EP1174001 B1 EP 1174001B1 EP 00927409 A EP00927409 A EP 00927409A EP 00927409 A EP00927409 A EP 00927409A EP 1174001 B1 EP1174001 B1 EP 1174001B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- panel
- dish
- loudspeaker according
- voice coil
- loudspeaker
- 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.)
- Expired - Lifetime
Links
Images
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R9/00—Transducers of moving-coil, moving-strip, or moving-wire type
- H04R9/06—Loudspeakers
- H04R9/066—Loudspeakers using the principle of inertia
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- 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
- H04R7/12—Non-planar diaphragms or cones
- H04R7/127—Non-planar diaphragms or cones dome-shaped
-
- 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
- H04R7/00—Diaphragms for electromechanical transducers; Cones
- H04R7/02—Diaphragms for electromechanical transducers; Cones characterised by the construction
- H04R7/04—Plane diaphragms
- H04R7/06—Plane diaphragms comprising a plurality of sections or layers
-
- 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
- H04R7/12—Non-planar diaphragms or cones
- H04R7/122—Non-planar diaphragms or cones comprising a plurality of sections or layers
Definitions
- the invention relates to loudspeakers and more particularly to bending-wave panel loudspeakers, e.g. resonant panel speakers of the kind described in International patent application WO97/09842.
- an electrodynamic vibration exciter having a tubular voice coil fixed as a continuous or discontinuous ring contact to a bending-wave or resonant panel to excite the panel can cause the disc of panel material directly underneath and enclosed by the ring contact of the voice coil to vibrate in the manner of a drum, and the frequency at which this localised resonance, occurs depends upon the exciter voice coil diameter and the panel material properties. For some panels, there may be little or no modal panel behaviour above this resonant frequency and therefore this resonant frequency may form the effective upper frequency limit of the panel. For thin panels used with 25mm diameter exciters this can be a particular problem.
- the panel material underneath or within the ring contact of the voice coil of an electrodynamic exciter is dished, e.g. formed or deformed to extend out of the plane of the panel, e.g. is formed into a raised or depressed concave or convex structure e.g. a dome or pyramidal shape. Since such a depressed or raised shape, whether curved or faceted, forms an inherently stiffer structure than the flat panel material, and this causes the local resonant frequency to be shifted to a higher frequency. The degree of frequency shift is dependent upon the radius or height, and diameter of the raised or depressed structure.
- the simplest form is a spherical contour which may be raised as in a dome or concave, the latter partially dependant on the depth available to the moving part of the exciter.
- the height of the raised element may be altered to suit, and its shaped may be based on other curves e.g. hyperbolic, or parabolic, or combinations of straight and curved sections.
- a simple cone shape may also be effective.
- the 'dome' element may be formed integrally with the panel, or be additional to the panel, where it may reinforce or replace the original disc section.
- a section of the core may be processed for increased thickness in the region of the exciter, or the panel may be moulded to conform to the desired local contour.
- the 'dome' feature may be part of the overall moulding profile.
- controlling feature may have more complex profiles such as a series or an array of smaller 'domes' proportioned so as to give finer control of the resultant acoustic output.
- the invention is also applicable to the conventional paper/felted speaker diaphragm technology where the bonded felted matrix is formed as a bending wave panel with the dome section for the exciter made integrally by design of the profile of the former.
- the internal diameter of the dome or other raised or depressed structure may match the internal diameter of a foot or mounting ring by which the exciter voice coil is mounted on the panel, or that of the voice coil itself if directly mounted on the panel, to enhance the improvement in frequency bandwidth.
- a 22mm diameter dome may be suitable for use with 25mm diameter exciters whilst for 19mm exciters, a 16mm diameter dome may be more suitable.
- a bending wave loudspeaker 1 generally of the kind described in WO 97/09842, comprises a thin stiff lightweight panel 2 excited by an electrodynamic vibration exciter 3, of the kind comprising an inertial magnet assembly comprising a magnet 8 and a pair of pole pieces 6, and a voice coil assembly comprising a coil 10 wound on a former 4 having an annular mounting foot 7 to produce an acoustic output, the exciter 3 being fixed to the panel 2 by the mounting foot 7 of the voice coil assembly to form a contact ring therewith.
- the ring may be discontinuous or continuous as desired.
- the area of the panel inside the contact ring is bulged away from the exciter to form a domed, part spherical dish 5.
- the magnet assembly 6,8 of the exciter 3 is resiliently suspended on the panel 2 by a compliant suspension 9, e.g. of foam rubber.
- Figures 2a to 2f show alternative shapes of the dish 5 in the panel 2.
- the dish is conical
- the dish is a part-sphere
- the part spherical dish of Figure 2b is inverted.
- the dish is pyramidal
- the dish is a combined cone and dome shape
- the dish is of hyperbolic shape.
- Figure 3 shows the improvement in frequency bandwidth of the loudspeaker by using the dome feature or shape compared to a conventional flat panel.
- the flat panel frequency response shows a panel "local or cap” resonance at approximately 6 kHz and a subsequent isolated harmonic of this resonance at approximately 18kHz.
- the 'dish' feature panel shows an extended high frequency range with a minor resonance at approximately 16 kHz.
- the height of the dome or dish may be changed to improve the frequency bandwidth.
- Figure 4 shows the effect of using different dome height (radius) on a different type of felt paper panel, in this case a Black SIG grade of paper with a lacquer treatment.
- Figure 4 clearly shows that the 5mm dome height (thick line) increases the useful bandwidth by approximately 2 kHz.
- the aperture resonance frequency for the 5mm height dome is approximately 2 kHz greater than that of the 3mm height dome (thin line).
- the useful range of heights for the dome feature may vary from about 1 to 7mm. Above 7mm or below 1mm, there is likely to be only a very slight increase in the aperture effect resonance frequency.
- the total thickness of the panel may be of critical importance in some applications which will prohibit the use of very high domes i.e. >7mm.
- the dome feature is most suited to thinner resonant panels because the "cap or local" resonance frequency is more of a problem on thin materials.
- a typical panel thickness range for the present invention would be approximately 0.2-4mm.
- This conventional pistonic cone speaker material i.e. felted paper
- injection-moulded thermoplastics such as nylon, ABS (acrylo butadiene styrene) or polypropylene.
- the invention thus provides a simple way of increasing the frequency bandwidth of a bending-wave panel loudspeaker.
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Acoustics & Sound (AREA)
- Signal Processing (AREA)
- Multimedia (AREA)
- Diaphragms For Electromechanical Transducers (AREA)
- Audible-Bandwidth Dynamoelectric Transducers Other Than Pickups (AREA)
Description
Claims (10)
- A bending-wave panel loudspeaker comprising a bending-wave panel and an electrodynamic exciter attached to the panel to vibrate the panel, the exciter comprising a magnet assembly and a voice coil assembly having a tubular voice coil fixed as a continuous or discontinuous ring contact to the panel, characterised in that the panel within the ring contact of the voice coil is formed to extend out of the plane of the panel to form a dish whereby a local resonant frequency is shifted to a higher frequency to increase frequency bandwidth of the loudspeaker.
- A loudspeaker according to claim 1, wherein the height of the dish is changed to improve the frequency bandwidth.
- A loudspeaker according to claim 1, wherein the height varies from about 1 to 7mm.
- A loudspeaker according to any one of claims 1 to 3, wherein the dish is a part-spherical curve.
- A loudspeaker according to any one of claims 1 to 3, wherein the shape of the dish is selected from conical, pyramidal, a combined core and dome shape and a hyperbolic shape
- A loudspeaker according to any one of claims 1 to 3, wherein the dish has an array of smaller domes proportioned so as to give finer control of the resultant acoustic output.
- A loudspeaker according to any preceding claim, wherein the dish is formed integrally with the panel.
- A loudspeaker according to any preceding claim, wherein the voice coil is mounted on the panel by a mounting ring and the diameter of the dish matches the internal diameter of the mounting ring.
- A loudspeaker according to any one of claims 1 to 7, wherein the voice coil is directly mounted on the panel and the diameter of the dish matches the internal diameter of the voice coil.
- A loudspeaker according to any preceding claim, wherein the panel material is selected from felted paper or foam materials such as polystyrene, polyurethane and polymethylacrylimide, or injection-moulded thermoplastics such as nylon, acrylo butadiene styrene or polypropylene.
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GBGB9909535.8A GB9909535D0 (en) | 1999-04-27 | 1999-04-27 | Loudspeakers |
GB9909535 | 1999-04-27 | ||
PCT/GB2000/001459 WO2000065869A2 (en) | 1999-04-27 | 2000-04-27 | Bending-wave panel loudspeakers |
Publications (2)
Publication Number | Publication Date |
---|---|
EP1174001A2 EP1174001A2 (en) | 2002-01-23 |
EP1174001B1 true EP1174001B1 (en) | 2003-08-27 |
Family
ID=10852249
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP00927409A Expired - Lifetime EP1174001B1 (en) | 1999-04-27 | 2000-04-27 | Bending- wave panel loudspeakers |
Country Status (8)
Country | Link |
---|---|
EP (1) | EP1174001B1 (en) |
JP (1) | JP2002543702A (en) |
CN (1) | CN1343437A (en) |
AU (1) | AU4581500A (en) |
DE (1) | DE60004813T2 (en) |
GB (1) | GB9909535D0 (en) |
TW (1) | TW484337B (en) |
WO (1) | WO2000065869A2 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP3101911B1 (en) * | 2015-06-04 | 2023-06-21 | Amina Technologies Limited | Distributed mode loudspeaker damping oscillations within exciter feet |
Families Citing this family (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6839444B2 (en) | 2000-11-30 | 2005-01-04 | New Transducers Limited | Loudspeakers |
GB0029098D0 (en) * | 2000-11-30 | 2001-01-10 | New Transducers Ltd | Vibration transducer |
US7120263B2 (en) | 2001-03-23 | 2006-10-10 | New Transducers Limited | Bending wave acoustic radiator |
WO2009028121A1 (en) * | 2007-08-29 | 2009-03-05 | Toa Corporation | Vibration plate and speaker |
Family Cites Families (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE3521845A1 (en) * | 1985-06-19 | 1987-01-02 | Martin Stute | Electrodynamic loudspeaker |
JPH03145900A (en) * | 1989-11-01 | 1991-06-21 | Yamaha Corp | Diaphragm for speaker |
US5259036A (en) * | 1991-07-22 | 1993-11-02 | Shure Brothers, Inc. | Diaphragm for dynamic microphones and methods of manufacturing the same |
GB9714050D0 (en) * | 1997-07-03 | 1997-09-10 | New Transducers Ltd | Panel-form loudspeakers |
GB9718878D0 (en) * | 1997-09-06 | 1997-11-12 | New Transducers Ltd | Vibration Transducer |
-
1999
- 1999-04-27 GB GBGB9909535.8A patent/GB9909535D0/en not_active Ceased
-
2000
- 2000-04-27 JP JP2000614692A patent/JP2002543702A/en active Pending
- 2000-04-27 AU AU45815/00A patent/AU4581500A/en not_active Abandoned
- 2000-04-27 EP EP00927409A patent/EP1174001B1/en not_active Expired - Lifetime
- 2000-04-27 CN CN 00804906 patent/CN1343437A/en active Pending
- 2000-04-27 WO PCT/GB2000/001459 patent/WO2000065869A2/en active IP Right Grant
- 2000-04-27 DE DE60004813T patent/DE60004813T2/en not_active Expired - Fee Related
- 2000-04-28 TW TW89108148A patent/TW484337B/en not_active IP Right Cessation
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP3101911B1 (en) * | 2015-06-04 | 2023-06-21 | Amina Technologies Limited | Distributed mode loudspeaker damping oscillations within exciter feet |
Also Published As
Publication number | Publication date |
---|---|
GB9909535D0 (en) | 1999-06-23 |
DE60004813T2 (en) | 2004-07-08 |
TW484337B (en) | 2002-04-21 |
JP2002543702A (en) | 2002-12-17 |
AU4581500A (en) | 2000-11-10 |
EP1174001A2 (en) | 2002-01-23 |
DE60004813D1 (en) | 2003-10-02 |
CN1343437A (en) | 2002-04-03 |
WO2000065869A2 (en) | 2000-11-02 |
WO2000065869A3 (en) | 2001-02-01 |
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