WO2003101147A1 - Haut-parleurs ameliores - Google Patents

Haut-parleurs ameliores Download PDF

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Publication number
WO2003101147A1
WO2003101147A1 PCT/GB2003/002243 GB0302243W WO03101147A1 WO 2003101147 A1 WO2003101147 A1 WO 2003101147A1 GB 0302243 W GB0302243 W GB 0302243W WO 03101147 A1 WO03101147 A1 WO 03101147A1
Authority
WO
WIPO (PCT)
Prior art keywords
carbon dioxide
loudspeaker
cabinet
interior space
gas
Prior art date
Application number
PCT/GB2003/002243
Other languages
English (en)
Inventor
Mark Alexander Dodd
Original Assignee
Kh Technology Corporation
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 Kh Technology Corporation filed Critical Kh Technology Corporation
Priority to GB0423588A priority Critical patent/GB2403093B/en
Priority to AU2003234023A priority patent/AU2003234023A1/en
Publication of WO2003101147A1 publication Critical patent/WO2003101147A1/fr

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
    • H04R1/2869—Reduction of undesired resonances, i.e. standing waves within enclosure, or of undesired vibrations, i.e. of the enclosure itself
    • H04R1/2876—Reduction of undesired resonances, i.e. standing waves within enclosure, or of undesired vibrations, i.e. of the enclosure itself by means of damping material, e.g. as cladding
    • H04R1/288—Reduction of undesired resonances, i.e. standing waves within enclosure, or of undesired vibrations, i.e. of the enclosure itself by means of damping material, e.g. as cladding for loudspeaker transducers

Definitions

  • This invention relates to loudspeakers, and in particular to the achievement of improved bass performance from a minimum size of loudspeaker cabinet.
  • WO-A-84/03600 (Ward) there is described a technique for reducing pressure variations in an essentially closed volume, such as the interior of a loudspeaker cabinet.
  • the essentially closed volume of the cabinet is effectively reduced in volume when the loudspeaker cones make excursions into the interior of the cabinet. Such excursions tend to increase the pressure in the cabinet and these pressure variations are reduced by locating a mass of material within the cabinet, the material being adsorbent to the gas or vapour in the cabinet.
  • the adsorbing material can be a mass of activated charcoal or carbon in granular form.
  • the granules are described as being held in place by a mesh-like support structure which can be a moulding of plastics material or formed from expanded metal sheet. This can be lined with a porous fabric such as filter paper to prevent small granules from passing through the support structure.
  • adsorbing material and/or the containment means for it which is at least partially hydrophobic, i.e. water- repellent.
  • the loudspeaker cabinet can be made to seem acoustically bigger without any physical change to the cabinet.
  • the same acoustic output can be obtained with a cabinet of smaller size.
  • the aforesaid WO-A-03/013183 describes a loudspeaker comprising a cabinet within which there is provided an adsorbent material which is or which has been treated to make it at least partially hydrophobic.
  • the adsorbent material is preferably activated carbon, suitably treated to provide it with hydrophobic properties.
  • US-B-6381337 (Greenberg) describes a loudspeaker or microphone which comprises a flexible enclosure and a transducer.
  • the enclosure can be stressed by internal pressure which can be supplied by an inflating gas which can be carbon dioxide.
  • the carbon dioxide is therefore used to provide the enclosure with a degree of rigidity.
  • US-A-4308431 (Hanbicki) describes a loudspeaker which comprises an air-tight chamber having one major surface formed from a thin gauge plastics sheet and an array of conductive pins extending away from a conductive plate forming the opposite major surface. An electrical signal is applied to the plate and to a conductive coating on the plastics sheet. This creates an electric field within the chamber which the plastics sheet to vibrate in accordance with the electrical signal.
  • the interior of the chamber preferably contains a polar gas which may be carbon dioxide. The carbon dioxide is therefore used as part of the transducer for its polar properties.
  • US-A-4101736 (Czerwinski) describes a loudspeaker enclosure which contains a bag formed from a soft, pliable membrane and which contains a gas, which may be carbon dioxide, or a combination of a gas and a liquid.
  • the bag is surrounded and separated from the loudspeaker drive unit by an acoustically transparent and porous cocoon which is itself surrounded by acoustical padding.
  • US-A-2797766 (Sullivan) describes loudspeaker horns and enclosures which contain a relatively heavy gas such as sulphurhexafluoride . It is also mentioned that carbon dioxide has been found to have the effect of increasing or extending the low frequency response of the loudspeaker.
  • the present invention is concerned with an alternative approach to the solving of the problems associated with the low frequency performance of small loudspeaker systems.
  • the present invention is based upon the realisation that by providing carbon dioxide within the loudspeaker cabinet in association with an adsorbent material one can achieve up to double the acoustic compliance enhancement of the adsorbent material alone. Moreover, it has been found that the use of carbon dioxide alone leads to only a very small enhancement in the acoustic compliance, typically no more than 10%. The improvement in acoustic compliance achieved with the invention can lead to a lower fundamental resonance frequency and hence improved frequency response. Thus, the combination of activated carbon and carbon dioxide can provide improved bass performance. There may also be a significant reduction in distortion, particularly second harmonic distortion.
  • the adsorbent material is preferably activated carbon which advantageously has been treated to render it at least partially hydrophobic.
  • the carbon dioxide within the loudspeaker cabinet should be in inherently dry form, i.e. with a low moisture content.
  • the present invention also provides a loudspeaker assembly comprising wall means defining a substantially airtight rigid enclosure defining a substantially closed interior space, and one or more drive units mounted in respective apertures in the wall means, the interior space containing a gas which has an enhanced proportion of carbon dioxide relative to that of air and a material which is adsorbent to the gas contained in the interior space.
  • the or at least one drive unit comprises a moving sound-generating diaphragm which has an outer surface exposed to the ambient atmosphere and an inner surface exposed to the gas contained in the interior space.
  • the assembly also includes a source of gaseous carbon dioxide, means for supplying the interior space with carbon dioxide from the source, sensing means for sensing the gas contained in the interior space and means for controlling the supply means in response to the sensing means to maintain a predetermined content of carbon dioxide in the interior space.
  • Figure 1 is a schematic diagram showing a cross- sectional view through a loudspeaker assembly in accordance with the present invention.
  • Figure 2 is a graph showing various characteristics of a speaker in accordance with the invention and a speaker not in accordance with the invention.
  • a loudspeaker cabinet 10 having a rear wall 12, a bottom 14, a top 16 and a front wall 18.
  • the rear wall 12, bottom 14, top 16, front wall 18 and side walls form a substantially rigid enclosure of cuboidal shape.
  • the front wall 18 has in it a smaller circular aperture 18a and a larger circular aperture 18b, behind which are mounted respectively a high frequency drive unit 20 a low frequency drive unit 22.
  • the drive units consist in conventional manner of conical diaphragms 20a, 22a and drive units 20b, 22b, shown schematically in the figure.
  • the drive units 20, 22 are sealed around their peripheries to the surfaces of the front wall 18 forming the apertures 18a, 18b respectively.
  • the interior of the cabinet 10 is therefore substantially sealed from the ambient atmosphere, front surfaces of the diaphragms 20a, 22a being exposed to the ambient atmosphere whilst their rear surfaces are exposed to the atmosphere within the cabinet 10.
  • a third drive unit could be provided mounted in a further aperture in the front wall 18 and sealed around is periphery as described above.
  • the third unit could be a further low frequency unit or a unit responsive to some other frequency range.
  • the cabinet may also contain electrical or electronic devices, for example amplifiers and cross-over devices.
  • a mass of adsorbent material 24, for example activated carbon, is located within a plurality of tubes 26 which are suspended within the cabinet from a support arm 28.
  • the tubes 26 can be suspended individually or can be linked together to form curtains extending across the interior of the box.
  • horizontally extending tubes holding adsorbent material can be provided.
  • the tubes 26 are preferably in the form of tubular bags of material, for example of a multi-filament textile material.
  • the aim is to achieve maximum exposure of the adsorbent material to the surrounding gas in the cabinet 10.
  • the volume of activated carbon relative to the internal volume of the cabinet is shown only schematically in figure 1: in practice up to about two-thirds of the internal volume might be occupied by the activated carbon.
  • a shelf 30 Positioned above the support arm 28 is a shelf 30 on which is positioned a container 32 for carbon dioxide in gaseous or solid form.
  • a pressure regulator 34 Connected to the output of the carbon dioxide supply 32 is a pressure regulator 34.
  • the output of the pressure regulator 34 is connected to a control valve 36 which is a slow release valve.
  • the flow through the control valve 36 is controlled by a sensor or sensors 38 connected to the control valve and arranged to sense the carbon dioxide level in the enclosure, either directly or indirectly. Instead of sensing the percentage concentration of carbon dioxide it may be easier to sense the percentage of oxygen in the cabinet enclosure. Assuming a constant ratio of oxygen to nitrogen, this will give a measure, of the volume of air that has leaked into the cabinet and, thus, the volume of carbon dioxide needed to replace it. The aim is always to maintain a constant high percentage of carbon dioxide in the cabinet enclosure. A typical level is about 70% carbon dioxide by volume with the balance air.
  • a carbon dioxide level of at least 50% by volume is preferred according to the invention, with minimum levels of 80% or 90% by volume being desirable. Any air entering the cabinet from the ambient atmosphere will be expelled by the carbon dioxide released from the container 32.
  • the drive unit and cabinet enclosure must be airtight apart from a small leakage path, as represented by a vent tube 40 positioned at the bottom of the cabinet enclosure.
  • the vent tube 40 can include a moisture trap to prevent moisture entering the cabinet from the ambient atmosphere.
  • valve 36 and sensor 38 it may be possible to arrange simply for carbon dioxide to be released at a constant low rate from the container 32, in order to compensate for leakage from the cabinet 10 taking place at a substantially similar rate.
  • Carbon dioxide may be able to flow through some of the materials which constitute the loudspeaker. It is therefore desirable to use materials which will help prevent this or reduce the flow to a minimum.
  • the loudspeaker cone for example might be metallised.
  • the output of carbon dioxide through the control valve 36 will be dependent upon the particular characteristics of any given loudspeaker. A few cubic centimeters per hour is envisaged as being appropriate for many loudspeakers.
  • the rear wall 12 of the loudspeaker cabinet can be provided with an access door in order to be able to remove and replace the carbon dioxide container 32.
  • the adsorbent material 24 within the container bags 26 is chosen to provide the maximum acoustic benefit from its combination with the carbon dioxide. It may be activated charcoal or carbon in granular form. Alternatively, it may be a material such as described in WO-A-03/013183 which is an absorbent material which is or which has been treated to make it at least partially hydrophobic.
  • the key feature of the invention is that the provision of carbon dioxide within the same enclosure as the adsorbent carbon material gives a significant reduction in distortion and improved bass response.
  • the positions of the materials within the cabinet enclosure, the proportion of carbon dioxide in the gas within the enclosure, and the particular adsorbent material used are all matters of choice, selected for the best response for any given loudspeaker.
  • Figure 2 shows in its upper part the frequency response curves for a loudspeaker according to the invention (curve A) and the same loudspeaker with its cabinet containing air (curve B) .
  • the y-axis shows sound pressure level ("SPL") in units of decibels. It will be noted that curve A shows a significantly higher SPL over the frequency range from 20Hz to about 50Hz and a significant reduction in the resonant hump at around 100Hz, compared with curve B.
  • SPL sound pressure level
  • FIG. 2 shows the electrical impedance measured in ohms of the loudspeaker of the invention (curve C) compared with that of the same speaker having a cabinet containing air (curve D) .
  • curve C shows an impedance peak at a significantly lower frequency (about 55Hz) than curve D (about 80Hz) , indicating an increase in acoustic compliance and an improved bass response .

Landscapes

  • Health & Medical Sciences (AREA)
  • Otolaryngology (AREA)
  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Separation Of Gases By Adsorption (AREA)
  • Details Of Audible-Bandwidth Transducers (AREA)

Abstract

L'invention concerne une enceinte acoustique (10) dotée d'excitateurs (20, 22) présentant un volume interne rempli par une grande proportion de dioxyde de carbone à la place de l'air. Ladite enceinte (10) contient également du carbone activé (24) traité pour le rendre hydrophobe, dans des tubes (26). Le taux de dioxyde de carbone est maintenu par la libération de gaz provenant d'une source (32) au moyen d'un régulateur (34), d'une vanne (36) et d'un capteur (38) qui peut détecter une perte en dioxyde de carbone en surveillant le taux d'oxygène, ce dernier augmentant lorsque l'air fuit dans l'enceinte. La combinaison du dioxyde de carbone et d'un carbone activé par un absorbant peut mener à une amélioration de d'ordre 3 à 6 dans l'élasticité acoustique du haut-parleur.
PCT/GB2003/002243 2002-05-24 2003-05-23 Haut-parleurs ameliores WO2003101147A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
GB0423588A GB2403093B (en) 2002-05-24 2003-05-23 Improvements in loudspeakers
AU2003234023A AU2003234023A1 (en) 2002-05-24 2003-05-23 Improvements in loudspeakers

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB0211977.4 2002-05-24
GB0211977A GB0211977D0 (en) 2002-05-24 2002-05-24 Improvements in loudspeakers

Publications (1)

Publication Number Publication Date
WO2003101147A1 true WO2003101147A1 (fr) 2003-12-04

Family

ID=9937345

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB2003/002243 WO2003101147A1 (fr) 2002-05-24 2003-05-23 Haut-parleurs ameliores

Country Status (3)

Country Link
AU (1) AU2003234023A1 (fr)
GB (2) GB0211977D0 (fr)
WO (1) WO2003101147A1 (fr)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1868409A1 (fr) * 2005-03-17 2007-12-19 Matsushita Electric Industrial Co., Ltd. Systeme de haut-parleur
WO2009014015A1 (fr) 2007-07-20 2009-01-29 Kuraray Chemical Co., Ltd. Matériau pour dispositif haut-parleur et dispositif haut-parleur l'utilisant
WO2011151675A1 (fr) * 2010-06-01 2011-12-08 Nokia Corporation Appareil radioélectrique comprenant une agglomération d'éléments adsorbants acoustiques
US8292023B2 (en) 2009-02-13 2012-10-23 Nokia Corporation Enclosing adsorbent material
US8630435B2 (en) 2008-08-08 2014-01-14 Nokia Corporation Apparatus incorporating an adsorbent material, and methods of making same
CN101548553B (zh) * 2007-07-20 2015-04-22 可乐丽化学株式会社 扬声器装置用材料及使用其的扬声器装置
CN104581499A (zh) * 2013-10-23 2015-04-29 宏碁股份有限公司 音箱结构

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8687836B2 (en) 2012-08-31 2014-04-01 Bose Corporation Loudspeaker system
US8794373B1 (en) 2013-03-15 2014-08-05 Bose Corporation Three-dimensional air-adsorbing structure

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2797766A (en) * 1953-10-20 1957-07-02 David Bogen & Company Inc Louid speaker
US3302748A (en) * 1963-04-11 1967-02-07 Prentiss B Reed Loudspeaker system
WO1984003600A1 (fr) * 1983-03-02 1984-09-13 Brian Douglas Ward Dispositif a pression constante
US5853690A (en) * 1996-02-28 1998-12-29 Toyota Jidosha Kabushiki Kaisha Method for decomposing water using an activated carbon catalyst

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2797766A (en) * 1953-10-20 1957-07-02 David Bogen & Company Inc Louid speaker
US3302748A (en) * 1963-04-11 1967-02-07 Prentiss B Reed Loudspeaker system
WO1984003600A1 (fr) * 1983-03-02 1984-09-13 Brian Douglas Ward Dispositif a pression constante
US5853690A (en) * 1996-02-28 1998-12-29 Toyota Jidosha Kabushiki Kaisha Method for decomposing water using an activated carbon catalyst

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1868409A1 (fr) * 2005-03-17 2007-12-19 Matsushita Electric Industrial Co., Ltd. Systeme de haut-parleur
EP1868409A4 (fr) * 2005-03-17 2009-04-29 Panasonic Corp Systeme de haut-parleur
US7743877B2 (en) 2005-03-17 2010-06-29 Panasonic Corporation Speaker system
WO2009014015A1 (fr) 2007-07-20 2009-01-29 Kuraray Chemical Co., Ltd. Matériau pour dispositif haut-parleur et dispositif haut-parleur l'utilisant
US8265330B2 (en) 2007-07-20 2012-09-11 Kuraray Chemical Co., Ltd. Material for speaker device and speaker device using it
CN101548553B (zh) * 2007-07-20 2015-04-22 可乐丽化学株式会社 扬声器装置用材料及使用其的扬声器装置
US8630435B2 (en) 2008-08-08 2014-01-14 Nokia Corporation Apparatus incorporating an adsorbent material, and methods of making same
US8292023B2 (en) 2009-02-13 2012-10-23 Nokia Corporation Enclosing adsorbent material
WO2011151675A1 (fr) * 2010-06-01 2011-12-08 Nokia Corporation Appareil radioélectrique comprenant une agglomération d'éléments adsorbants acoustiques
US9430998B2 (en) 2010-06-01 2016-08-30 Nokia Technologies Oy Radio apparatus comprising an agglomeration of acoustically adsorbing members
CN104581499A (zh) * 2013-10-23 2015-04-29 宏碁股份有限公司 音箱结构

Also Published As

Publication number Publication date
AU2003234023A1 (en) 2003-12-12
GB0211977D0 (en) 2002-07-03
GB2403093A (en) 2004-12-22
GB2403093B (en) 2005-06-15
GB0423588D0 (en) 2004-11-24

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