WO2002062099A1 - Loudspeaker arrangement - Google Patents

Loudspeaker arrangement Download PDF

Info

Publication number
WO2002062099A1
WO2002062099A1 PCT/EP2002/000642 EP0200642W WO02062099A1 WO 2002062099 A1 WO2002062099 A1 WO 2002062099A1 EP 0200642 W EP0200642 W EP 0200642W WO 02062099 A1 WO02062099 A1 WO 02062099A1
Authority
WO
WIPO (PCT)
Prior art keywords
loudspeaker
membrane
porous material
basket
polymeric porous
Prior art date
Application number
PCT/EP2002/000642
Other languages
French (fr)
Other versions
WO2002062099A9 (en
Inventor
Sune Gustafsson
Original Assignee
Telefonaktiebolaget Lm Ericsson
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Telefonaktiebolaget Lm Ericsson filed Critical Telefonaktiebolaget Lm Ericsson
Publication of WO2002062099A1 publication Critical patent/WO2002062099A1/en
Publication of WO2002062099A9 publication Critical patent/WO2002062099A9/en

Links

Classifications

    • 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 
    • H04R1/28—Transducer mountings or enclosures modified by provision of mechanical or acoustic impedances, e.g. resonator, damping means
    • H04R1/2803—Transducer mountings or enclosures modified by provision of mechanical or acoustic impedances, e.g. resonator, damping means for loudspeaker transducers

Definitions

  • the present invention relates to a loudspeaker arrangement.
  • a loudspeaker generally comprises a membrane in connection with a magnet and a coil, which are mounted to a basket provided with outlet holes behind the membrane.
  • the loudspeaker is arranged in an enclosure with the membrane side facing outwards .
  • the motion of the membrane of the loudspeaker is affected by the compliance of the enclosed air.
  • the compliance varies with frequency and is dependent on resonances and standing waves in the enclosed air and vibrations in the enclosure itself.
  • a soft absorbing material such as mineral wool, plastic foams and felt.
  • US 4 278 852 A shows an earphone construction with a special loudspeaker that produce an impression that the acoustic event reaches the ear from the outside.
  • a sound absorbing cover is provided that reduces middle and high frequencies, mostly 1 kHz to 12 kHz. Sound of frequencies below, i.e. low frequency sound is hardly damped but pass through the porous material.
  • US 5 504 281 A shows perforated acoustical attenuators made of a porous material comprised of particles sintered and/or bonded together at their points of contact and having through holes provided therein. The material could be a polymeric material.
  • the perforated attenuator of the invention provides sufficient ventilation while still providing a high level of sound attenuation. Therefore, the attenuator is good as acoustical barrier in office equipment such as computers and photocopiers.
  • the air flow through the holes is important for the ventilation of the apparatuses in such attenuators . Because of the holes the sound absorbing of low frequncies are poor.
  • the problem is to provide a loudspeaker arrangement that is efficient in sound absorbation at low frequencies .
  • the separation of the air space at the back of the membrane from the ambient air with a sintered polymeric porous material an efficient damping of the low frequencies will be achieved and the damped sound pressure will be delayed in its progress to ambient air, since the porosity of the sintered polymeric porous material -allow the air to in a delayed way pass through the separating "wall", causing a damping of the sound.
  • the sintered polymeric porous material functions as an impedance for the air waves and provide longer ways for the air to pass until it reaches the ambient air.
  • echoes, standing waves and resonances in a loudspeaker enclosure, in its structures or in ambient air are in this way separated from the air behind the membrane and will thus be damped, too, so that the influence on the membrane is minimized.
  • An advantage of this invention is that the size of the loudspeaker arrangement can be minimized since such an efficient damping is performed directly behind the membrane, only leaving a small air space between absorbent and membrane.
  • Another advantage of this invention is that the demand for stiffness of loudspeaker boxes will be lower.
  • a further advantage of this invention is that the sound pressure in an enclosure of a loudspeaker will be lower and consequently cause less vibrations in the structur .
  • a still further advantage of this invention is that it will be easy to implement in production lines since a robot can be used for mounting the absorbent due to its stability. This is difficult with soft absorbent.
  • Fig. 1 illustrates a first embodiment of an acoustical absorbent of the present invention from behind and a typical loudspeaker.
  • Fig. 2 illustrates the front of the typical loudspeaker in fig. 1 showing the membrane.
  • Fig. 3 illustrates the first embodiment of the acoustical absorbent of the present invention showing the front of the typical loudspeaker without the membrane.
  • Fig. 4 illustrates the first embodiment of the acoustical absorbent assembled with the loudspeaker forming a loudspeaker arrangement.
  • Fig. 5 illustrates a second embodiment of an acoustical absorbent of the present invention from behind and a typical loudspeaker.
  • Fig. 6 illustrates the second embodiment of the acoustical absorbent assembled with the loudspeaker forming a loudspeaker arrangement.
  • Fig. 7 illustrates the front of a third embodiment of an acoustical absorbent of the present invention together with a loudspeaker forming a loudspeaker arrangement .
  • Fig. 8 illustrates the third embodiment of the acoustical absorbent assembled with the loudspeaker from behind.
  • an acoustical absorbent 1 according to the present invention is illustrated which is designed to fit into the back of a typical loudspeaker 2, see fig. 2.
  • the loudspeaker 2 comprises a magnet 3, a membrane 4 and a basket 5 in which the membrane 4 and the magnet 3 are provided.
  • the basket 5 is provided with holes 7 through which the moving air behind the membrane 4 pass.
  • the acoustical absorbent 1 have protrusions 6 that are designed to snuggly fit into the holes 7 to cover and fill the holes 7 up fully with the acoustical absorbent 1.
  • the acoustical absorbent 1 may be attached by an adhesive or by frictional forces to the loudspeaker basket 5, for example. It is important for the absorbing of low frequencies that no through holes or openings are present, through which sound, i.e. air waves, may freely pass. Instead the air waves should be delayed and attenuated through the sintered polymeric porous material .
  • a loudspeaker arrangement 8 is illustrated where the acoustical absorbent 1 is attached to the back of a loudspeaker basket 5.
  • a second embodiment of the acoustical absorbent 1 is illustrated.
  • the acoustical absorbent 1 is designed like a cup or cover 9 that is to be attached over the back of the loudspeaker 2 to cover the holes 7 in the basket 5 of the loudspeaker 2.
  • cup 9 may be attached by adhesive, staples or be clamped or screwed thereon.
  • a third embodiment of the acoustical absorbent 1 is illustrated.
  • the acoustical absorbent 1 also functions as a loudspeaker basket 5' .
  • the basket 5' does not have any holes 7. Due to the rigidity of the sintered polymeric porous material it is possible to provide the magnet 3 and the membrane 4 in such a basket 5' .
  • the basket 5' is provided with rigid inner and outer rings 10.
  • the sintered polymeric porous material could, for example, be a polyethylene, preferably a high density polyethylene.
  • the material may have an average pore size of 90-200 micrometer, preferably of 110-190 micrometer or most preferred, of 125-180 micrometer.
  • the thickness of the material could be about 6-10 mm, but this depends upon the dynamical characteristics of the loudspeaker.
  • the invention divides the air behind a loudspeaker into a small space of air situated directly behind the membrane and the ambient air by means of a "wall" of sintered polymeric porous material .
  • the "wall” could comprise the basket or replace the basket or cover the basket, for example in a cup-shaped style, closely to the basket.

Abstract

A loudspeaker arrangement comprising a loudspeaker provided with a membrane and an acoustical absorbent in which a sintered polymeric porous material is provided so that an air space in the back of said membrane is separated, by the sintered polymeric porous material, from ambient air. Method of damping low frequencies of sound characterised by the separation of an air space behind a membrane of a loudspeaker from ambient air by means of sintered polymeric porous material.

Description

LOUDSPEAKER ARRANGEMENT
TECHNICAL FIELD
The present invention relates to a loudspeaker arrangement.
BACKGROUND OF THE INVENTION AND PRIOR ART A loudspeaker generally comprises a membrane in connection with a magnet and a coil, which are mounted to a basket provided with outlet holes behind the membrane. Usually the loudspeaker is arranged in an enclosure with the membrane side facing outwards .
When mounting a loudspeaker in an enclosure the motion of the membrane of the loudspeaker is affected by the compliance of the enclosed air. The compliance varies with frequency and is dependent on resonances and standing waves in the enclosed air and vibrations in the enclosure itself.
Also when a loudspeaker is mounted openly, i.e. without any enclosure, the motion of the membrane is affected by surrounding air, sound waves and vibrations.
To increase the compliance and decrease the standing waves in a loudspeaker enclosure normally a soft absorbing material is used, such as mineral wool, plastic foams and felt.
The problem with such materials are that the efficiency of sound absorbing is not sufficient at lower frequencies, for example, less than 500 Hz.
US 4 278 852 A shows an earphone construction with a special loudspeaker that produce an impression that the acoustic event reaches the ear from the outside. In order to reduce the radiation of disturbing sound to the ambience a sound absorbing cover is provided that reduces middle and high frequencies, mostly 1 kHz to 12 kHz. Sound of frequencies below, i.e. low frequency sound is hardly damped but pass through the porous material. US 5 504 281 A shows perforated acoustical attenuators made of a porous material comprised of particles sintered and/or bonded together at their points of contact and having through holes provided therein. The material could be a polymeric material.
In the document it says that surprisingly the perforated attenuator of the invention provides sufficient ventilation while still providing a high level of sound attenuation. Therefore, the attenuator is good as acoustical barrier in office equipment such as computers and photocopiers. The air flow through the holes is important for the ventilation of the apparatuses in such attenuators . Because of the holes the sound absorbing of low frequncies are poor. These attenuators are all related to large appliances .
SUMMARY OF THE INVENTION
The problem is to provide a loudspeaker arrangement that is efficient in sound absorbation at low frequencies .
The solution according to the present invention is illustrated in the independent claims 1 and 7.
Thanks to the separation of the air space at the back of the membrane from the ambient air with a sintered polymeric porous material an efficient damping of the low frequencies will be achieved and the damped sound pressure will be delayed in its progress to ambient air, since the porosity of the sintered polymeric porous material -allow the air to in a delayed way pass through the separating "wall", causing a damping of the sound. The sintered polymeric porous material functions as an impedance for the air waves and provide longer ways for the air to pass until it reaches the ambient air.
Additionally, echoes, standing waves and resonances in a loudspeaker enclosure, in its structures or in ambient air are in this way separated from the air behind the membrane and will thus be damped, too, so that the influence on the membrane is minimized. An advantage of this invention is that the size of the loudspeaker arrangement can be minimized since such an efficient damping is performed directly behind the membrane, only leaving a small air space between absorbent and membrane. Another advantage of this invention is that the demand for stiffness of loudspeaker boxes will be lower.
A further advantage of this invention is that the sound pressure in an enclosure of a loudspeaker will be lower and consequently cause less vibrations in the structur .
A still further advantage of this invention is that it will be easy to implement in production lines since a robot can be used for mounting the absorbent due to its stability. This is difficult with soft absorbent.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 illustrates a first embodiment of an acoustical absorbent of the present invention from behind and a typical loudspeaker. Fig. 2 illustrates the front of the typical loudspeaker in fig. 1 showing the membrane.
Fig. 3 illustrates the first embodiment of the acoustical absorbent of the present invention showing the front of the typical loudspeaker without the membrane.
Fig. 4 illustrates the first embodiment of the acoustical absorbent assembled with the loudspeaker forming a loudspeaker arrangement.
Fig. 5 illustrates a second embodiment of an acoustical absorbent of the present invention from behind and a typical loudspeaker.
Fig. 6 illustrates the second embodiment of the acoustical absorbent assembled with the loudspeaker forming a loudspeaker arrangement. Fig. 7 illustrates the front of a third embodiment of an acoustical absorbent of the present invention together with a loudspeaker forming a loudspeaker arrangement . Fig. 8 illustrates the third embodiment of the acoustical absorbent assembled with the loudspeaker from behind. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
The invention will now be described in more detail . In fig. 1, 3 and 4 an acoustical absorbent 1 according to the present invention is illustrated which is designed to fit into the back of a typical loudspeaker 2, see fig. 2. The loudspeaker 2 comprises a magnet 3, a membrane 4 and a basket 5 in which the membrane 4 and the magnet 3 are provided. The basket 5 is provided with holes 7 through which the moving air behind the membrane 4 pass.
The acoustical absorbent 1 have protrusions 6 that are designed to snuggly fit into the holes 7 to cover and fill the holes 7 up fully with the acoustical absorbent 1. The acoustical absorbent 1 may be attached by an adhesive or by frictional forces to the loudspeaker basket 5, for example. It is important for the absorbing of low frequencies that no through holes or openings are present, through which sound, i.e. air waves, may freely pass. Instead the air waves should be delayed and attenuated through the sintered polymeric porous material .
In fig. 4 a loudspeaker arrangement 8 is illustrated where the acoustical absorbent 1 is attached to the back of a loudspeaker basket 5.
In fig. 5 and 6 a second embodiment of the acoustical absorbent 1 is illustrated. In this embodiment the acoustical absorbent 1 is designed like a cup or cover 9 that is to be attached over the back of the loudspeaker 2 to cover the holes 7 in the basket 5 of the loudspeaker 2.
For example the cup 9 may be attached by adhesive, staples or be clamped or screwed thereon.
In fig. 7 and 8 a third embodiment of the acoustical absorbent 1 is illustrated. In this embodiment the acoustical absorbent 1 also functions as a loudspeaker basket 5' . Of course the basket 5' does not have any holes 7. Due to the rigidity of the sintered polymeric porous material it is possible to provide the magnet 3 and the membrane 4 in such a basket 5' . Preferably the basket 5' is provided with rigid inner and outer rings 10. The sintered polymeric porous material could, for example, be a polyethylene, preferably a high density polyethylene.
The material may have an average pore size of 90-200 micrometer, preferably of 110-190 micrometer or most preferred, of 125-180 micrometer. The thickness of the material could be about 6-10 mm, but this depends upon the dynamical characteristics of the loudspeaker.
Of course, other sintered polymeric porous materials fulfilling the requirement, of damping of low frequencies is possible. The invention divides the air behind a loudspeaker into a small space of air situated directly behind the membrane and the ambient air by means of a "wall" of sintered polymeric porous material . The "wall" could comprise the basket or replace the basket or cover the basket, for example in a cup-shaped style, closely to the basket. One advantage is that it is possible to damp low frequencies very close to the back of the membrane and thus reduce the size of the loudspeaker arrangement .

Claims

1. A loudspeaker arrangement, comprising a loudspeaker provided with a membrane and an acoustical absorbent, characterised in..that said acoustical- absorbent-is a sintered polymeric porous material so arranged that an air space at the back of said membrane is separated, by the sintered polymeric porous material, from ambient air.
2. The loudspeaker arrangement according to claim 2, wherein the loudspeaker comprises a basket with holes, which holes are covered or filled with sintered polymeric porous material so that the air space at the back of the membrane is separated from ambient air.
3. The loudspeaker arrangement according to claim 2, wherein the loudspeaker comprises a basket with holes, which basket is covered by a cup of sintered polymeric porous material so that the air space at the back of the membrane is separated from ambient air.
4. The loudspeaker arrangement according to claim 2, wherein the loudspeaker comprises a basket without holes, which basket is made of sintered polymeric porous material so that the air space at the back of the membrane is separated from ambient air.
5. The loudspeaker arrangement according to anyone of the previous claims, wherein the material is a high density polyethylene.
6. The loudspeaker arrangement according to anyone of the previous claims, wherein the material has an average pore size of 90-200 micrometer, preferably of 110-190 micrometer or most preferred of 125-180 micrometer.
7. A method of damping low frequencies of sound in a loudspeaker, characterised by the separation of an air space behind a membrane of a loudspeaker from ambient air by means of sintered polymeric porous material.
PCT/EP2002/000642 2001-01-31 2002-01-23 Loudspeaker arrangement WO2002062099A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE0100285A SE522767C2 (en) 2001-01-31 2001-01-31 Speaker arrangement including an acoustic absorbent
SE0100285-6 2001-01-31

Publications (2)

Publication Number Publication Date
WO2002062099A1 true WO2002062099A1 (en) 2002-08-08
WO2002062099A9 WO2002062099A9 (en) 2002-10-31

Family

ID=20282789

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP2002/000642 WO2002062099A1 (en) 2001-01-31 2002-01-23 Loudspeaker arrangement

Country Status (2)

Country Link
SE (1) SE522767C2 (en)
WO (1) WO2002062099A1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2293592A1 (en) 2009-09-01 2011-03-09 Nxp B.V. Acoustic material for a small loudspeaker cabinet

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4127751A (en) * 1975-11-27 1978-11-28 Pioneer Electronic Corporation Loudspeaker with rigid foamed back-cavity
US4964482A (en) * 1989-02-23 1990-10-23 Meyer John E Loudspeaker enclosure
US5658656A (en) * 1992-01-10 1997-08-19 Minnesota Mining And Manufacturing Company Use of materials comprising microbubbles as acoustical barriers
EP0999723A2 (en) * 1998-11-05 2000-05-10 Matsushita Electric Industrial Co., Ltd. Piezoelectric speaker, method for producing the same, and speaker system including the same
US6266857B1 (en) * 1998-02-17 2001-07-31 Microsound Systems, Inc. Method of producing a backing structure for an ultrasound transceiver

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4127751A (en) * 1975-11-27 1978-11-28 Pioneer Electronic Corporation Loudspeaker with rigid foamed back-cavity
US4964482A (en) * 1989-02-23 1990-10-23 Meyer John E Loudspeaker enclosure
US5658656A (en) * 1992-01-10 1997-08-19 Minnesota Mining And Manufacturing Company Use of materials comprising microbubbles as acoustical barriers
US6266857B1 (en) * 1998-02-17 2001-07-31 Microsound Systems, Inc. Method of producing a backing structure for an ultrasound transceiver
EP0999723A2 (en) * 1998-11-05 2000-05-10 Matsushita Electric Industrial Co., Ltd. Piezoelectric speaker, method for producing the same, and speaker system including the same

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2293592A1 (en) 2009-09-01 2011-03-09 Nxp B.V. Acoustic material for a small loudspeaker cabinet

Also Published As

Publication number Publication date
WO2002062099A9 (en) 2002-10-31
SE0100285L (en) 2002-08-01
SE0100285D0 (en) 2001-01-31
SE522767C2 (en) 2004-03-02

Similar Documents

Publication Publication Date Title
US7206428B2 (en) Acoustic receiver having improved mechanical suspension
US10349166B2 (en) Passive acoustic radiator module
US5661271A (en) Acoustic speaker enclosure having a stacked construction
EA000860B1 (en) Packaging
KR101117078B1 (en) Recoilless speaker system
CN101444109B (en) Loudspeaker with reduced rocking tendency
US20020046901A1 (en) Noise cancellation using a mechanical oscillator
US20110158448A1 (en) Speakerbox
EP1949749A1 (en) Arrangement for optimizing the frequency response of an electro-acoustic transducer
US8085968B2 (en) Resonating cone transducer
WO2002062099A1 (en) Loudspeaker arrangement
EP1123633B1 (en) Method for sound reproduction and pillar loudspeaker
US4569414A (en) Augmented speaker enclosure
WO2013082594A1 (en) Planar speaker
JPS5868396A (en) Elastic support for electroacoustic converter
JP3973482B2 (en) Inner wall structure
JPH0359639B2 (en)
WO2023246613A1 (en) Acoustic apparatus
KR101915077B1 (en) A vibrator for body sense based on a acoustic sound
JP2023173333A (en) headphone unit
EP0078649A1 (en) Isolation pads
GB2509711A (en) Selective or frequency-dependent acoustic damping
CN117501712A (en) Noise canceling headphone device
EP0873039A2 (en) Speaker
ITRM940010A1 (en) ANTI-RESONANCE AND ANTI-REFLECTIONS DEVICE FOR SOUND TRANSDUCERS

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): AE AG AL AM AT AU AZ BA BB BG BR BY BZ CA CH CN CO CR CU CZ DE DK DM DZ EC EE ES FI GB GD GE GH GM HR HU ID IL IN IS JP KE KG KP KR KZ LC LK LR LS LT LU LV MA MD MG MK MN MW MX MZ NO NZ OM PH PL PT RO RU SD SE SG SI SK SL TJ TM TN TR TT TZ UA UG US UZ VN YU ZA ZM ZW

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): GH GM KE LS MW MZ SD SL SZ TZ UG ZM ZW AM AZ BY KG KZ MD RU TJ TM AT BE CH CY DE DK ES FI FR GB GR IE IT LU MC NL PT SE TR BF BJ CF CG CI CM GA GN GQ GW ML MR NE SN TD TG

121 Ep: the epo has been informed by wipo that ep was designated in this application
AK Designated states

Kind code of ref document: C2

Designated state(s): AE AG AL AM AT AU AZ BA BB BG BR BY BZ CA CH CN CO CR CU CZ DE DK DM DZ EC EE ES FI GB GD GE GH GM HR HU ID IL IN IS JP KE KG KP KR KZ LC LK LR LS LT LU LV MA MD MG MK MN MW MX MZ NO NZ OM PH PL PT RO RU SD SE SG SI SK SL TJ TM TN TR TT TZ UA UG US UZ VN YU ZA ZM ZW

AL Designated countries for regional patents

Kind code of ref document: C2

Designated state(s): GH GM KE LS MW MZ SD SL SZ TZ UG ZM ZW AM AZ BY KG KZ MD RU TJ TM AT BE CH CY DE DK ES FI FR GB GR IE IT LU MC NL PT SE TR BF BJ CF CG CI CM GA GN GQ GW ML MR NE SN TD TG

COP Corrected version of pamphlet

Free format text: PAGES 1/4-4/4, DRAWINGS, REPLACED BY NEW PAGES 1/4-4/4; DUE TO LATE TRANSMITTAL BY THE RECEIVING OFFICE

Free format text: PAGES 1/4-4/4, DRAWINGS, REPLACED BY NEW PAGES 1/4-4/4; DUE TO LATE TRANSMITTAL BY THE RECEIVING OFFICE

DFPE Request for preliminary examination filed prior to expiration of 19th month from priority date (pct application filed before 20040101)
REG Reference to national code

Ref country code: DE

Ref legal event code: 8642

122 Ep: pct application non-entry in european phase
NENP Non-entry into the national phase

Ref country code: JP

WWW Wipo information: withdrawn in national office

Country of ref document: JP