EP1060637B1 - Acoustic element - Google Patents

Acoustic element Download PDF

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Publication number
EP1060637B1
EP1060637B1 EP99919295A EP99919295A EP1060637B1 EP 1060637 B1 EP1060637 B1 EP 1060637B1 EP 99919295 A EP99919295 A EP 99919295A EP 99919295 A EP99919295 A EP 99919295A EP 1060637 B1 EP1060637 B1 EP 1060637B1
Authority
EP
European Patent Office
Prior art keywords
film
acoustic element
porous layer
support points
layers
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
Application number
EP99919295A
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German (de)
French (fr)
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EP1060637A1 (en
Inventor
Kari Kirjavainen
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Panphonics Oy
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Panphonics Oy
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Filing date
Publication date
Application filed by Panphonics Oy filed Critical Panphonics Oy
Publication of EP1060637A1 publication Critical patent/EP1060637A1/en
Application granted granted Critical
Publication of EP1060637B1 publication Critical patent/EP1060637B1/en
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Expired - Lifetime legal-status Critical Current

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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
    • H04R7/04—Plane diaphragms
    • H04R7/06—Plane diaphragms comprising a plurality of sections or layers
    • H04R7/10—Plane diaphragms comprising a plurality of sections or layers comprising superposed layers in contact
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R2201/00—Details of transducers, loudspeakers or microphones covered by H04R1/00 but not provided for in any of its subgroups
    • H04R2201/02—Details casings, cabinets or mounting therein for transducers covered by H04R1/02 but not provided for in any of its subgroups
    • H04R2201/021—Transducers or their casings adapted for mounting in or to a wall or ceiling

Definitions

  • the invention relates to an acoustic element which comprises an arbitrary number of layers, at least one layer comprising at least one porous layer which is either electrically conductive or coated at least on one of its surfaces to be electrically conductive, and at least one film, which is either charged or provided with at least one electrically conductive surface, at least one porous layer and film being arranged to come into contact with each other substantially only at support points, thereby providing an air gap between the porous layer and the film.
  • WO publication 97/31506 discloses a plate-like acoustic element comprising fixed stator plates, with a film secured between the plates at predetermined support points. Between the stator plate and the film are left small air gaps that allow the film 3 to move.
  • the stator plates and the film are provided with electrically conductive surfaces, so by applying electric signals to the surfaces, the film 3 can be made to move to produce sound.
  • the structure is simple and has a very even frequency response, but its field of application is somewhat limited and, to produce a sufficiently high air pressure by using a moving film, a fairly strong electric field is required.
  • AT-B-382 490 discloses an electrostatic loudspeaker comprising two electrodes and a film between the electrodes. There are elastic parts made of foam rubber between the film and an electrode.
  • US 4 885 783 discloses a transducer having opposed first and second conductive plates for application of an electrical potential difference therebetween. An elastomeric dielectric material such as neoprene rubber is disposed between the plates and in contact therewith.
  • An object of the present invention is to provide an acoustic element allowing the above shortcomings to be avoided.
  • the acoustic element of the invention is characterized in that the support points are arranged in such a way that the porous layer being moved by the film is able to move in such a way that the acoustic element can change its thickness substantially entirely.
  • the acoustic element comprises an arbitrary number of layers, at least one layer comprising a porous layer and a film arranged at a distance from the layer, the porous layer and the film coming into contact with each other substantially only at specific support points.
  • the porous layer is either electrically conductive or coated at least on one of its surfaces to be electrically conductive, and the film is charged or provided with at least one electrically conductive surface.
  • the support points at which the film and the porous layer come into contact with each other are arranged in such a way that the entire structure can change its thickness.
  • a preferred embodiment is based on the idea that the acoustic element is coated with an elastic surface material.
  • Another preferred embodiment is based on the idea that the acoustic element is hermetically sealed.
  • An advantage of the invention is that the structure of the acoustic element is very light, solid, inexpensive and easy to manufacture. Further, because the gap between the porous layer and the film is fairly small, a reasonably high pressure is obtained by applying a fairly low control voltage.
  • the porous material provides the element with a large air capacity, whereby the air displaced by the film is able to enter the porous layer, which reduces counter pressure and increases movement. The air entering the porous layer causes flow losses and therefore the structure does not resonate strongly. Further, due to the flow losses the material of the element also attenuates sound passively.
  • An element coated with an elastic surface material can be used for a number of different applications (e.g. floors). Hermetic sealing of the element allows it to be used also in fairly humid conditions.
  • FIG. 1 shows an acoustic element 1 comprising a plural number of porous layers 2.
  • a typical porous layer is, for example, 0.5 to 1 mm thick, about 70% of the layer being air.
  • the porous layer 2 can be made of cellulose, glass fibre, mineral fibre, metal fibre or by sintering plastic or metal powder.
  • the porous layer 2 is either electrically conductive or coated at least on one of its surfaces to be electrically conductive, for example, by sputtering the surface to provide a metallization 3 thereon.
  • the metallization 3 of the porous layer 2 is typically about 40 nanometers thick.
  • the metallization 3 on the porous layer 2 is also porous in order to allow air to pass through the porous layer 2 and the metallization 3.
  • the acoustic element 1 further comprises a film 4 arranged between the porous layers 2.
  • the porous layer 2 and the film 4 come into contact with each other only at support points 5, an air gap 6 being thus formed between the porous layer 2 and the film 4.
  • the thickness of the film 4 is typically about 5 micrometers and the width of the air gap 6, correspondingly about 10 micrometers.
  • Figure 1 shows an embodiment in which two films 4 are arranged one on the other, a metallization 7 typically about 40 nanometers thick being arranged between the films.
  • the films are charged and they can be made of polypropylene, polymethyl pentene or cyclic olefin copolymer, for example.
  • the films 4 can be further provided with a bubble structure comprising flat bubbles.
  • Porous layers 2 and films 4 are arranged one on the other to provide the acoustic element 1 with a layered structure as shown in Figure 1.
  • Control electrodes A are connected to the metallizations 7 between the films 4 and earth electrodes B. correspondingly, to the metallizations 3 of the porous layers 2.
  • the support points 5 are arranged in such a way that the film 4 is not supported to the porous layers 2 at exactly the same points on opposite sides of the film. Consequently, when a signal is supplied to the control electrode A, the film 4 changes is form. Since the film 4 is secured to the porous layer 2 at the support point 5, the porous layer 2 also moves and, since the support points 5 are at different places in the acoustic element, the acoustic element 1 can change its thickness substantially entirely.
  • the voltage U need not be very high to provide a fairly high pressure P.
  • Figure 2 shows an acoustic element with a plural number of different layers arranged one on the other.
  • one side of the film 4 is secured substantially entirely to a first porous layer 2.
  • the other side of the film 4 is secured to a second porous layer 2 substantially only at support points 5. between the second porous layer 2 and the film 4 being then the air gap 6.
  • the support points 5 of successive air gaps 6 are at different places, thereby allowing the entire acoustic element to change its thickness.
  • the support points 5 can be formed on the porous plates 2, for example, by pressing the plates at suitable places to form bulges.
  • the places of the support points 5 can vary symmetrically or randomly, but it is essential that the support points 5 of successive layers are arranged at substantially different places.
  • a strong electric field reduces the elastic constant of the structure, i.e. due to pressure the thickness of the structure changes essentially more than without the electric field, thereby substantially increasing the attenuating capability of the structure and lowering its resonance frequency.
  • the structure can function in an attenuating manner, control electronics being not needed then.
  • a static pre-voltage which allows the elastic constant of the structure to be controlled in a desired manner.
  • the films 4 can also be provided with a permanent electret charge, if desired.
  • the pre-voltage can be applied through a resistor having a high resistance, or the control electrode A, for example, can have a high resistance.
  • Figure 3 illustrates the acoustic element 1 coated with an elastic surface material 8.
  • the thickness of the surface material 8 can be from 0.1 to 10mm, for example.
  • the surface material 8 can be a rubber carpet, for example, the acoustic element 1 thus being applicable as a floor covering, for example.
  • the edges of the acoustic element can be provided with sealing portions 9 to make the element 1 hermetically sealed.
  • the control electronics 10 can be arranged inside the acoustic element.
  • the hermetically sealed element 1 can be used in very demanding humid conditions. Further, the acoustic element 1 can be made into a preformed structural board, thereby allowing it to be used as a construction element.
  • the surface material 8 can be substantially air impermeable because the entire acoustic element 1 can change its form and thereby produce sound, although it does not allow air to pass through.
  • the acoustic element in question can be used, for example, for sound attenuating purposes (as floor mats in cars, for example).
  • sound attenuating purposes as floor mats in cars, for example.
  • the acoustic element 1 may comprise an arbitrary number of layers. To produce sound, at least one porous layer 2 and at least one film 4 are needed. Instead of two charged films 4 and the metallization 7 between them shown in the embodiment of Figure 1, a film with polarized charging can be used (i.e. a film having a positive charging on one side and a negative charging on the other), the control voltage being then applied between the surfaces of the porous layers 2. The film 4 does not have to be charged if at least its surface is electrically conductive.
  • the acoustic element of the invention can be used in various applications relating to sound reproduction and active noise attenuation.
  • the acoustic element, or some of its layers can be used for example as sensors in acoustic systems while, at the same time, the other layers can be used as actuators.

Abstract

The invention relates to an acoustic element comprising and arbitrary number of layers. Each layer comprises at least one porous layer (2) and a film (4) arranged at a distance from the layer. The porous layer (2) can be electrically conductive or coated at least on one of its surfaces to be electrically conductive, and the film (4) can be charged or provided with at least one electrically conductive surface. The porous layer (2) and the film (4) come into contact with each other substantially only at support points (5). The support points (5) are arranged so as to allow the entire structure to change its thickness.

Description

  • The invention relates to an acoustic element which comprises an arbitrary number of layers, at least one layer comprising at least one porous layer which is either electrically conductive or coated at least on one of its surfaces to be electrically conductive, and at least one film, which is either charged or provided with at least one electrically conductive surface, at least one porous layer and film being arranged to come into contact with each other substantially only at support points, thereby providing an air gap between the porous layer and the film.
  • WO publication 97/31506 discloses a plate-like acoustic element comprising fixed stator plates, with a film secured between the plates at predetermined support points. Between the stator plate and the film are left small air gaps that allow the film 3 to move. The stator plates and the film are provided with electrically conductive surfaces, so by applying electric signals to the surfaces, the film 3 can be made to move to produce sound. The structure is simple and has a very even frequency response, but its field of application is somewhat limited and, to produce a sufficiently high air pressure by using a moving film, a fairly strong electric field is required.
  • AT-B-382 490 discloses an electrostatic loudspeaker comprising two electrodes and a film between the electrodes. There are elastic parts made of foam rubber between the film and an electrode. US 4 885 783 discloses a transducer having opposed first and second conductive plates for application of an electrical potential difference therebetween. An elastomeric dielectric material such as neoprene rubber is disposed between the plates and in contact therewith.
  • An object of the present invention is to provide an acoustic element allowing the above shortcomings to be avoided.
  • The acoustic element of the invention is characterized in that the support points are arranged in such a way that the porous layer being moved by the film is able to move in such a way that the acoustic element can change its thickness substantially entirely.
  • An essential idea of the invention is that the acoustic element comprises an arbitrary number of layers, at least one layer comprising a porous layer and a film arranged at a distance from the layer, the porous layer and the film coming into contact with each other substantially only at specific support points. The porous layer is either electrically conductive or coated at least on one of its surfaces to be electrically conductive, and the film is charged or provided with at least one electrically conductive surface. The support points at which the film and the porous layer come into contact with each other are arranged in such a way that the entire structure can change its thickness. A preferred embodiment is based on the idea that the acoustic element is coated with an elastic surface material. Another preferred embodiment is based on the idea that the acoustic element is hermetically sealed.
  • An advantage of the invention is that the structure of the acoustic element is very light, solid, inexpensive and easy to manufacture. Further, because the gap between the porous layer and the film is fairly small, a reasonably high pressure is obtained by applying a fairly low control voltage. The porous material provides the element with a large air capacity, whereby the air displaced by the film is able to enter the porous layer, which reduces counter pressure and increases movement. The air entering the porous layer causes flow losses and therefore the structure does not resonate strongly. Further, due to the flow losses the material of the element also attenuates sound passively. An element coated with an elastic surface material can be used for a number of different applications (e.g. floors). Hermetic sealing of the element allows it to be used also in fairly humid conditions.
  • The invention will be described in greater detail in the accompanying drawings, of which
  • Figure 1 is a schematic sectional side view of an acoustic element of the invention;
  • Figure 2 is a schematic sectional side view of another acoustic element of the invention: and
  • Figure 3 is a schematic view of a third embodiment of the invention.
  • Figure 1 shows an acoustic element 1 comprising a plural number of porous layers 2. A typical porous layer is, for example, 0.5 to 1 mm thick, about 70% of the layer being air. The porous layer 2 can be made of cellulose, glass fibre, mineral fibre, metal fibre or by sintering plastic or metal powder. The porous layer 2 is either electrically conductive or coated at least on one of its surfaces to be electrically conductive, for example, by sputtering the surface to provide a metallization 3 thereon. The metallization 3 of the porous layer 2 is typically about 40 nanometers thick. The metallization 3 on the porous layer 2 is also porous in order to allow air to pass through the porous layer 2 and the metallization 3.
  • The acoustic element 1 further comprises a film 4 arranged between the porous layers 2. The porous layer 2 and the film 4 come into contact with each other only at support points 5, an air gap 6 being thus formed between the porous layer 2 and the film 4. The thickness of the film 4 is typically about 5 micrometers and the width of the air gap 6, correspondingly about 10 micrometers.
  • Figure 1 shows an embodiment in which two films 4 are arranged one on the other, a metallization 7 typically about 40 nanometers thick being arranged between the films. The films are charged and they can be made of polypropylene, polymethyl pentene or cyclic olefin copolymer, for example. The films 4 can be further provided with a bubble structure comprising flat bubbles.
  • Porous layers 2 and films 4 are arranged one on the other to provide the acoustic element 1 with a layered structure as shown in Figure 1. Control electrodes A are connected to the metallizations 7 between the films 4 and earth electrodes B. correspondingly, to the metallizations 3 of the porous layers 2. The support points 5 are arranged in such a way that the film 4 is not supported to the porous layers 2 at exactly the same points on opposite sides of the film. Consequently, when a signal is supplied to the control electrode A, the film 4 changes is form. Since the film 4 is secured to the porous layer 2 at the support point 5, the porous layer 2 also moves and, since the support points 5 are at different places in the acoustic element, the acoustic element 1 can change its thickness substantially entirely.
  • Pressure P caused by the acoustic element 1 is obtained from the following formula P = ½ * ε * U2 s2 ,    where
       s is the width of the air gap 6,
       U is voltage acting over the air gap 6, and
       ε is a dielectricity constant of an intermediate medium.
  • Since the width s of the air gap 6 in the element concerned is very small, the voltage U need not be very high to provide a fairly high pressure P.
  • Figure 2 shows an acoustic element with a plural number of different layers arranged one on the other. In the embodiment shown in Figure 2 one side of the film 4 is secured substantially entirely to a first porous layer 2. The other side of the film 4 is secured to a second porous layer 2 substantially only at support points 5. between the second porous layer 2 and the film 4 being then the air gap 6. When the film 4 moves, it also makes the porous layer 2 move to which it is secured. The support points 5 of successive air gaps 6 are at different places, thereby allowing the entire acoustic element to change its thickness.
  • The support points 5 can be formed on the porous plates 2, for example, by pressing the plates at suitable places to form bulges. The places of the support points 5 can vary symmetrically or randomly, but it is essential that the support points 5 of successive layers are arranged at substantially different places.
  • A strong electric field reduces the elastic constant of the structure, i.e. due to pressure the thickness of the structure changes essentially more than without the electric field, thereby substantially increasing the attenuating capability of the structure and lowering its resonance frequency. When the control electrodes A and the earth electrodes B are connected with each other, the structure can function in an attenuating manner, control electronics being not needed then. Between the control electrodes A and earth electrodes B can also be applied a static pre-voltage which allows the elastic constant of the structure to be controlled in a desired manner. The films 4 can also be provided with a permanent electret charge, if desired. The pre-voltage can be applied through a resistor having a high resistance, or the control electrode A, for example, can have a high resistance.
  • Figure 3 illustrates the acoustic element 1 coated with an elastic surface material 8. The thickness of the surface material 8 can be from 0.1 to 10mm, for example. The surface material 8 can be a rubber carpet, for example, the acoustic element 1 thus being applicable as a floor covering, for example. The edges of the acoustic element can be provided with sealing portions 9 to make the element 1 hermetically sealed. Also the control electronics 10 can be arranged inside the acoustic element. The hermetically sealed element 1 can be used in very demanding humid conditions. Further, the acoustic element 1 can be made into a preformed structural board, thereby allowing it to be used as a construction element. The surface material 8 can be substantially air impermeable because the entire acoustic element 1 can change its form and thereby produce sound, although it does not allow air to pass through. The acoustic element in question can be used, for example, for sound attenuating purposes (as floor mats in cars, for example). By increasing the mass of the surface material 8. the attenuating capability of the acoustic element 1 can be enhanced and the resonance frequency further lowered.
  • The drawings and the related description are only meant to illustrate the inventive idea. The details of the invention may vary within the scope of the claims. The acoustic element 1 may comprise an arbitrary number of layers. To produce sound, at least one porous layer 2 and at least one film 4 are needed. Instead of two charged films 4 and the metallization 7 between them shown in the embodiment of Figure 1, a film with polarized charging can be used (i.e. a film having a positive charging on one side and a negative charging on the other), the control voltage being then applied between the surfaces of the porous layers 2. The film 4 does not have to be charged if at least its surface is electrically conductive. The acoustic element of the invention can be used in various applications relating to sound reproduction and active noise attenuation. The acoustic element, or some of its layers, can be used for example as sensors in acoustic systems while, at the same time, the other layers can be used as actuators.

Claims (6)

  1. An acoustic element which comprises an arbitrary number of layers, at least one layer comprising at least one porous layer (2) which is either electrically conductive or coated at least on one of its surfaces to be electrically conductive, and at least one film (4), which is either charged or provided with at least one electrically conductive surface, at least one porous layer (2) and film (4) being arranged to come into contact with each other substantially only at support points (5), thereby providing an air gap between the porous layer (2) and the film (4), characterized in that the support points (5) are arranged in such a way that the porous layer (2) being moved by the film (4) is able to move in such a way that the acoustic element (1) can change its thickness substantially entirely.
  2. An acoustic element according to claim 1, characterized in that the element (1) comprises at least two porous elements (2), at least one film (4) being arranged between the layers in such a way that on both sides of the film (4), an air gap (6) is formed, the support points (5) on opposite sides of the film (4) being arranged at substantially different places.
  3. An acoustic element according to claim 1, characterized in that the element (1) comprises at least two porous layers (2), at least one film (4) being arranged between the layers in such a way that the film (4) is secured to a second porous layer (2) and between the second porous layer (2) and the film (4) is an air gap (6).
  4. An acoustic element according to claim 3, characterized in that the acoustic element (1) is a layered structure comprising at least two air gaps (6) arranged one on the other, the support points (5) in successive air gaps (6) being substantially at different places.
  5. An acoustic element according to any one of preceding claims, characterized in that the acoustic element (1) is coated with an elastic surface material (8).
  6. An acoustic element according to claim 5, characterized in that the acoustic element (1) is hermetically sealed.
EP99919295A 1998-04-27 1999-04-26 Acoustic element Expired - Lifetime EP1060637B1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
FI980926A FI115598B (en) 1998-04-27 1998-04-27 Acoustic element
FI980926 1998-04-27
PCT/FI1999/000337 WO1999056498A1 (en) 1998-04-27 1999-04-26 Acoustic element

Publications (2)

Publication Number Publication Date
EP1060637A1 EP1060637A1 (en) 2000-12-20
EP1060637B1 true EP1060637B1 (en) 2005-08-03

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Application Number Title Priority Date Filing Date
EP99919295A Expired - Lifetime EP1060637B1 (en) 1998-04-27 1999-04-26 Acoustic element

Country Status (9)

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EP (1) EP1060637B1 (en)
JP (1) JP4527282B2 (en)
AT (1) ATE301382T1 (en)
AU (1) AU3712099A (en)
CA (1) CA2330377A1 (en)
DE (1) DE69926487T2 (en)
FI (1) FI115598B (en)
NO (1) NO20005393D0 (en)
WO (1) WO1999056498A1 (en)

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US6873863B2 (en) 2001-03-19 2005-03-29 Nokia Mobile Phones Ltd. Touch sensitive navigation surfaces for mobile telecommunication systems
FI20010766A0 (en) 2001-04-11 2001-04-11 Panphonics Oy Electromechanical converter and method of energy conversion
FI118622B (en) 2002-01-17 2008-01-15 Band Oy B Musical instrument converter and method of making it
FI20040093A (en) * 2004-01-22 2005-07-23 North Wave Ltd Oy Speaker
DE102004048990A1 (en) * 2004-10-04 2006-04-06 Volkswagen Ag Speaker arrangement in a motor vehicle
JP2006148612A (en) * 2004-11-22 2006-06-08 Yamaha Corp Acoustic device
DE102005058175A1 (en) * 2005-12-05 2007-06-06 Volkswagen Ag Speaker arrangement for sound in a motor vehicle
DE102006045385B4 (en) * 2006-03-01 2020-09-24 Volkswagen Ag Loudspeaker arrangement in a motor vehicle and a method for controlling the at least one loudspeaker
DE102006049543A1 (en) * 2006-06-13 2007-12-20 Volkswagen Ag Speaker arrangement for directional sonication of a motor vehicle seat
DE102007007957A1 (en) * 2007-02-17 2008-08-21 Lyttron Technology Gmbh Loudspeaker constructed of foils
FI20070155A0 (en) * 2007-02-23 2007-02-23 Panphonics Oy Elektreettilevyrakenne
DE102007063344A1 (en) 2007-12-28 2009-07-02 S1Nn Gmbh & Co. Kg Audio output stage for electrostatic flat surface loudspeaker in motor vehicle, has matching circuit including transformer and arranged between audio output stage for electrodynamic loudspeaker and electrostatic flat surface loudspeaker
DE102008047796A1 (en) 2008-09-17 2010-04-15 Siemens Aktiengesellschaft Device for generating broadband sound in the audible range of humans
JP6547272B2 (en) 2014-10-16 2019-07-24 ヤマハ株式会社 Electro-acoustic transducer
CN112584290B (en) * 2019-09-27 2022-07-26 华硕电脑股份有限公司 Actuator
TWI708473B (en) 2019-09-27 2020-10-21 華碩電腦股份有限公司 Actuator

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US3654403A (en) * 1969-05-01 1972-04-04 Chester C Pond Electrostatic speaker
US3787642A (en) * 1971-09-27 1974-01-22 Gte Automatic Electric Lab Inc Electrostatic transducer having resilient electrode
US3740496A (en) * 1971-11-08 1973-06-19 Industrial Research Prod Inc Diaphragm assembly for electret transducer
AT382490B (en) * 1984-12-03 1987-02-25 Akg Akustische Kino Geraete LARGE ELECTROSTATIC SPEAKER
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US4887248A (en) * 1988-07-07 1989-12-12 Cleveland Machine Controls, Inc. Electrostatic transducer and method of making and using same

Also Published As

Publication number Publication date
WO1999056498A1 (en) 1999-11-04
DE69926487D1 (en) 2005-09-08
FI115598B (en) 2005-05-31
CA2330377A1 (en) 1999-11-04
FI980926A (en) 1999-10-28
JP4527282B2 (en) 2010-08-18
DE69926487T2 (en) 2006-05-18
JP2002513263A (en) 2002-05-08
FI980926A0 (en) 1998-04-27
NO20005393L (en) 2000-10-26
EP1060637A1 (en) 2000-12-20
AU3712099A (en) 1999-11-16
NO20005393D0 (en) 2000-10-26
ATE301382T1 (en) 2005-08-15

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