WO2000048428A2 - Exciter for imparting bending wave energy to a panel - Google Patents
Exciter for imparting bending wave energy to a panel Download PDFInfo
- Publication number
- WO2000048428A2 WO2000048428A2 PCT/GB2000/000389 GB0000389W WO0048428A2 WO 2000048428 A2 WO2000048428 A2 WO 2000048428A2 GB 0000389 W GB0000389 W GB 0000389W WO 0048428 A2 WO0048428 A2 WO 0048428A2
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- exciter
- coil
- plinth
- panel
- assembly
- Prior art date
Links
- 238000005452 bending Methods 0.000 title claims abstract description 10
- 230000008878 coupling Effects 0.000 claims abstract 2
- 238000010168 coupling process Methods 0.000 claims abstract 2
- 238000005859 coupling reaction Methods 0.000 claims abstract 2
- 238000013461 design Methods 0.000 description 8
- 238000010276 construction Methods 0.000 description 6
- 238000005259 measurement Methods 0.000 description 5
- 239000011162 core material Substances 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 230000005520 electrodynamics Effects 0.000 description 3
- 239000006260 foam Substances 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 229920001169 thermoplastic Polymers 0.000 description 3
- 239000004416 thermosoftening plastic Substances 0.000 description 3
- 230000000694 effects Effects 0.000 description 2
- 238000012935 Averaging Methods 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 239000003822 epoxy resin Substances 0.000 description 1
- 239000003292 glue Substances 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- 238000010030 laminating Methods 0.000 description 1
- 238000003475 lamination Methods 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 229920003023 plastic Polymers 0.000 description 1
- 229920000647 polyepoxide Polymers 0.000 description 1
- 239000004814 polyurethane Substances 0.000 description 1
- 229920002635 polyurethane Polymers 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
- H04R9/00—Transducers of moving-coil, moving-strip, or moving-wire type
- H04R9/06—Loudspeakers
-
- 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
-
- 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
Definitions
- the invention relates to loudspeakers and more particularly to resonant panel -form loudspeakers e.g. of the general kind described in International patent application WO97/09842, and to vibration exciters for such resonant panel -form loudspeakers.
- the present invention is particularly concerned with resonant panel-form loudspeakers of the kind in which one or more vibration exciters are embedded within the panel structure.
- the invention is an exciter for imparting bending wave energy to a resonant panel, comprising a coil assembly having a coil for engaging a first plinth, a magnet assembly having a magnet, an inner pole piece inside the coil, and an outer pole piece outside the coil, the assembly defining apertures therein, a strut member for engaging a second plinth at the opposite end of the coil to the first plinth having projections extending through the apertures m the magnet assembly.
- the invention is a loudspeaker comprising a resonant panel -form member and an exciter as described above embedded therein to cause the panel to resonate to produce an acoustic output.
- the exciter design may be such that the coil of the exciter is bonded directly to a disc-like plinth below the coil and also to an identical plinth positioned directly above the coil via axial projections m the form of a set of ribs.
- the coil movement is transmitted to the lower plinth and upper plinth simultaneously and both plinths move in the same direction.
- the two plinths may be adhesively bonded to the panel core material at the top and bottom surfaces of the panel .
- Figure 1 is an exploded view of an embodiment of embedded inertial electrodynamic vibration exciter
- Figure 2 is a view of the exciter of Figure 1 when assembled
- Figure 3 is a cross section through the exciter embedded in a panel ;
- Figure 4 shows a cross section through a second embodiment of the exciter embedded in a panel
- Figure 5 illustrates the assembly of exciters into a panel
- Figure 6 illustrates the orientation of exciters in a panel
- Figure 7 is a graph of the frequency response of another embodiment of an embedded inertial electrodynamic vibration exciter
- Figure 8 is a graph of the frequency response of an exciter of the kind shown in Figures 1 and 2 ;
- Figure 9 illustrates the power response using a pair of exciters;
- FIG 10 shows the structure of the plinths in an embodiment .
- an electrodynamic exciter is shown.
- a top plinth (1) and a bottom plinth (3) form the top and bottom faces of the exciter.
- a coil assembly including a coil (5) mounted on a coil former (7) is mounted on the bottom plinth (3) .
- a magnet assembly having a magnet cup (11) having a base (13) and sides (15) sits over the voice coil (5) . Inside the magnet cup sit a magnet (17) and an inner pole piece (19) in the form of a disc. Apertures (21) in the base and sides of the cup are provided.
- a strut member (23) has a ring (25) extending circumferentially around the base of the cup and ribs (27) extending through the apertures (21) .
- Foam supports (29) for bonding to the core material of the panel (or to separate supports) maintain the magnet cup position relative to the coil while still allowing movement of the magnet cup .
- the three equi-spaced axial ribs (27) are bonded to both disc-like plinths and to the sides of the coil support. As shown the vertical ribs appear to cross the magnet cup. This is achieved by using a cut-away magnet cup as shown in Figure 2 which allows the ribs to connect to the coil assembly at three positions.
- Figure 3 shows a cross section of the exciter (4) embedded in a panel (31) .
- the foam supports (29) hold the magnet cup (11) .
- the panel comprises skins (33) around a core (35) ; the exciter is flush with the faces (34) of the panel .
- An alternative embodiment is shown in Figure 4.
- the strut member (23) may be integrally formed with the coil assembly (5) . Indeed, a single plastics moulding (39) may include the coil former (7) and ribs (27) . In this case the ring may be omitted; it may be possible to glue the ribs to the top plinth or slots (37) may be provided in the top plinth to accept the ribs.
- two holes (41) are machined in the panel of a size corresponding to the outer diameter of the plinths (1,3).
- a slit (43) is cut m the panel and holes are machined prior to laminating the panel.
- a length of copper track is cut m the panel and holes are machined prior to laminating the panel.
- Figure 6 illustrates how the second exciter (49) is reversed with respect to the first (47) to produce a more symmetrical structure and hence frequency response.
- the exciter is such that the area around the exciter will have comparable bending stiffness to that of the panel.
- the plinths connected by the axial ribs act as a form of sandwich structure which will have a comparable impedance to the rest of the panel.
- the plinths are thin, aperture effects related to the diameter, density and stiffness of the plinths may occur.
- a small diameter, stiff, low density plinth construction is preferable. The construction of the plinth must also allow the effective transmission of bending waves to the panel .
- the thickness restrictions mean that the plinth thickness is limited to approximately 2mm for a total panel thickness of 12mm.
- the preferred exciter size is based on the required loudness of the panel i.e. smaller diameter exciters may not put enough force into the panel .
- This restriction dictates that the minimum plinth diameter is fixed at approximately 40mm.
- the plinth options can then be evaluated.
- Table 1 Plinth Constructions and Upper Frequency Limits Table 1 shows that increasing the plinth thickness improves the high frequency performance of the panel up to the maximum possible thickness of 2mm. Using a thicker panel or decreasing the exciter thickness to allow higher plinth thickness could increase the high frequency limit further .
- a plinth (1,3) may have a sandwich structure of skins (51) sandwiching a core (53) ( Figure 10) .
- the sandwich structure plinths appear to have improved high frequency performance compared to the monolithic structures. This is probably due to the higher stiffness to weight ratio of these sandwich structures .
- the frequency of the coil side of the panel differs from that of the magnet side of the panel and therefore both sides of the panel need to be measured and compared.
- the frequency response needs to be identical; see the results presented later.
- Figure 7 shows the frequency response for an embedded panel with a single exciter.
- the high frequency performance can be seen to be uneven, with the magnet side of the panel having a 'suck-out' at approximately 7-8 kHz.
- the high frequency limit of this material is approximately 10 kHz.
- the higher frequency performance appears to be due to the nature of the plinths.
- the sandwich structure plinths have improved higher frequency performance .
- the plinth, vertical ribs and foam supports may be injection moulded to form a single part.
- thermoplastic plinth design may be more suitable for low cost panels where high frequency performance is not required.
- a sandwich construction plinth has superior high frequency performance and is more suited where broad bandwidth is essential.
- Thicker, sandwich structure plinths would improve the high frequency performance of the panel .
- Thinner exciters or thicker panels may be used.
- Back to back exciters embedded in a panel may be expected to have more similar frequency responses at the respective panel surfaces than using a single double plinth exciter. This turns out to be the case.
- Figure 8 shows the frequency response on each side of a panel with two exciters, which may be compared with the like graph of Figure 7 for a panel with one exciter.
- Figure 8 shows an improved match; for example, on the gross asymmetry at 7 - 8 kHz is smoothed.
- the invention is not limited to the above described embodiment.
- the properties of the exciter are substantially improved by having the strut member located close to the voice coil, which requires the strut member to pass through the magnet assembly and hence for the magnet assembly to have apertures, it may be possible in a less preferred embodiment for the or each exciter to have the strut member located outside the magnet assembly.
- the strut member may span the gap between first and second plinths and be fixed to each plinth, for example using adhesive, so that it couples the first and second plinths.
Abstract
Description
Claims
Priority Applications (5)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AU25563/00A AU2556300A (en) | 1999-02-11 | 2000-02-09 | Loudspeakers |
EA200100883A EA200100883A1 (en) | 1999-02-11 | 2000-02-09 | SPEAKERS |
JP2000599239A JP2002537705A (en) | 1999-02-11 | 2000-02-09 | Loudspeaker |
EP00903798A EP1151631A2 (en) | 1999-02-11 | 2000-02-09 | Exciter for imparting bending wave energy to a panel |
CA002361295A CA2361295A1 (en) | 1999-02-11 | 2000-02-09 | Loudspeakers |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GBGB9903044.7A GB9903044D0 (en) | 1999-02-11 | 1999-02-11 | Loudspeakers |
GB9903044.7 | 1999-02-11 |
Publications (2)
Publication Number | Publication Date |
---|---|
WO2000048428A2 true WO2000048428A2 (en) | 2000-08-17 |
WO2000048428A3 WO2000048428A3 (en) | 2001-01-25 |
Family
ID=10847510
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/GB2000/000389 WO2000048428A2 (en) | 1999-02-11 | 2000-02-09 | Exciter for imparting bending wave energy to a panel |
Country Status (9)
Country | Link |
---|---|
EP (1) | EP1151631A2 (en) |
JP (1) | JP2002537705A (en) |
CN (1) | CN1339236A (en) |
AU (1) | AU2556300A (en) |
CA (1) | CA2361295A1 (en) |
EA (1) | EA200100883A1 (en) |
GB (1) | GB9903044D0 (en) |
TW (1) | TW469747B (en) |
WO (1) | WO2000048428A2 (en) |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2002025992A2 (en) * | 2000-09-21 | 2002-03-28 | New Transducers Limited | Loudspeaker driver |
US6751329B2 (en) | 2000-09-21 | 2004-06-15 | New Transducers Limited | Loudspeaker driver |
WO2008043260A1 (en) | 2006-09-27 | 2008-04-17 | Bailiang Zhang | Vibrating system of panel form electrodynamic loudspeaker |
US7447322B2 (en) | 2004-01-13 | 2008-11-04 | Brookstone Purchasing, Inc. | Speaker having a transparent panel |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO1997009842A2 (en) * | 1995-09-02 | 1997-03-13 | New Transducers Limited | Acoustic device |
WO1998034320A2 (en) * | 1997-01-31 | 1998-08-06 | New Transducers Limited | Electro-dynamic inertial vibration exciter |
WO1998039947A1 (en) * | 1997-03-04 | 1998-09-11 | New Transducers Limited | Acoustic device |
-
1999
- 1999-02-11 GB GBGB9903044.7A patent/GB9903044D0/en not_active Ceased
-
2000
- 2000-02-09 WO PCT/GB2000/000389 patent/WO2000048428A2/en not_active Application Discontinuation
- 2000-02-09 EP EP00903798A patent/EP1151631A2/en not_active Withdrawn
- 2000-02-09 CN CN 00803532 patent/CN1339236A/en active Pending
- 2000-02-09 CA CA002361295A patent/CA2361295A1/en not_active Abandoned
- 2000-02-09 EA EA200100883A patent/EA200100883A1/en unknown
- 2000-02-09 JP JP2000599239A patent/JP2002537705A/en active Pending
- 2000-02-09 AU AU25563/00A patent/AU2556300A/en not_active Abandoned
- 2000-02-11 TW TW89102289A patent/TW469747B/en not_active IP Right Cessation
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO1997009842A2 (en) * | 1995-09-02 | 1997-03-13 | New Transducers Limited | Acoustic device |
WO1998034320A2 (en) * | 1997-01-31 | 1998-08-06 | New Transducers Limited | Electro-dynamic inertial vibration exciter |
WO1998039947A1 (en) * | 1997-03-04 | 1998-09-11 | New Transducers Limited | Acoustic device |
Cited By (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2002025992A2 (en) * | 2000-09-21 | 2002-03-28 | New Transducers Limited | Loudspeaker driver |
WO2002025992A3 (en) * | 2000-09-21 | 2003-01-03 | New Transducers Ltd | Loudspeaker driver |
US6751329B2 (en) | 2000-09-21 | 2004-06-15 | New Transducers Limited | Loudspeaker driver |
US7447322B2 (en) | 2004-01-13 | 2008-11-04 | Brookstone Purchasing, Inc. | Speaker having a transparent panel |
WO2008043260A1 (en) | 2006-09-27 | 2008-04-17 | Bailiang Zhang | Vibrating system of panel form electrodynamic loudspeaker |
EP2071868A1 (en) * | 2006-09-27 | 2009-06-17 | ZHANG, Bailiang | Vibrating system of panel form electrodynamic loudspeaker |
EP2071868A4 (en) * | 2006-09-27 | 2011-04-20 | Bailiang Zhang | Vibrating system of panel form electrodynamic loudspeaker |
Also Published As
Publication number | Publication date |
---|---|
CN1339236A (en) | 2002-03-06 |
TW469747B (en) | 2001-12-21 |
GB9903044D0 (en) | 1999-03-31 |
JP2002537705A (en) | 2002-11-05 |
EP1151631A2 (en) | 2001-11-07 |
AU2556300A (en) | 2000-08-29 |
WO2000048428A3 (en) | 2001-01-25 |
CA2361295A1 (en) | 2000-08-17 |
EA200100883A1 (en) | 2002-02-28 |
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