WO2011042019A1 - Haut-parleur dipôle ayant une propagation diffuse vers l'arrière - Google Patents

Haut-parleur dipôle ayant une propagation diffuse vers l'arrière Download PDF

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Publication number
WO2011042019A1
WO2011042019A1 PCT/DK2010/000132 DK2010000132W WO2011042019A1 WO 2011042019 A1 WO2011042019 A1 WO 2011042019A1 DK 2010000132 W DK2010000132 W DK 2010000132W WO 2011042019 A1 WO2011042019 A1 WO 2011042019A1
Authority
WO
WIPO (PCT)
Prior art keywords
loudspeaker
acoustic reflector
dipole element
sound
loudspeaker system
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.)
Ceased
Application number
PCT/DK2010/000132
Other languages
English (en)
Inventor
Jes Mosgaard
Henrik Green Mortensen
Jan Abildgaard Pedersen
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.)
SL Audio AS
Original Assignee
SL Audio AS
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 SL Audio AS filed Critical SL Audio AS
Publication of WO2011042019A1 publication Critical patent/WO2011042019A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS
    • H04R1/00—Details of transducers, loudspeakers or microphones
    • H04R1/20—Arrangements for obtaining desired frequency or directional characteristics
    • H04R1/32—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired directional characteristic only
    • H04R1/34—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired directional characteristic only by using a single transducer with sound reflecting, diffracting, directing or guiding means
    • H04R1/345—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired directional characteristic only by using a single transducer with sound reflecting, diffracting, directing or guiding means for loudspeakers

Definitions

  • the invention relates to the field of audio equipment, especially loudspeakers for reproduction of audio signals. More specifically, the invention relates to the field of hi-fi loudspeakers for reproduction of stereo or multichannel signals.
  • the invention defines a dipole loudspeaker suitable for placement very close to or directly on a wall.
  • a loudspeaker drive unit is traditionally mounted in a closed box to prevent the rear side radiation to reach the listener because this radiation is 180 degrees out of phase compared to the front side radiation.
  • the closed box is of limited size, then the lower cut-off frequency becomes relatively high, which in turn prevents low frequency sound reproduction.
  • a closed box has resonances, which makes the sound from the loudspeaker driver be non- constant as a function of frequency, i.e. local peaks and dips in the response.
  • a dipole loudspeaker is known to solve these problems associated by closed box loudspeaker designs.
  • a dipole loudspeaker is open both to front radiation and rear radiation. That means that the lower cut-off frequency is as low as it can get with a given drive unit and no box resonances exists.
  • the drive unit is mounted in a baffle, which traditionally is a plane of a certain size.
  • the baffle should prevent rear radiation from canceling the front radiation by ensuring a longer distance for the rear radiation to travel to the listening position compared to the front radiation. This yields a delay and amplitude attenuation of the rear radiated sound.
  • the actual size of the baffle determines the effective lower cut-off frequency of the system, i.e. to which frequency the front and rear radiation starts to cancel.
  • dipole loudspeakers One problem with dipole loudspeakers is that they often need to be placed physically at a large distance to a wall behind the loudspeaker to avoid a strong reflection of the rear radiated sound off the wall. This is in conflict with a desire to mount small dipole loudspeakers very close to a wall or even directly on a wall.
  • An object of the present invention is to solve the above mentioned problems.
  • a way to avoid the strong reflection of the wall behind the loudspeaker is to place an acoustic reflector behind the loudspeaker driver to redirect the sound away from the wall.
  • the redirected sound should also be directed away from the listening position.
  • a direction approximately perpendicular to the wall behind the loudspeaker seems to be optimal. This can be achieved by using a triangular sound reflector as depicted on the accompanying drawings. Other shapes may be applied as well.
  • Redirecting the rear radiated sound from the dipole loudspeaker almost parallel with the wall will enhance the late reflected energy experienced at the listening position because the rear radiated sound will only arrive at the listening position after multiple reflections of side walls or other surfaces in the room. This will improve the perceived sound quality because late reflected sound energy tends to open the sound image and create a sensation of a very high ceiling, i.e. the sensation of being in a very large room.
  • this invention secures a null in the directivity characteristics towards the side walls. This follows from the basic principle of a dipole element, where a theoretical total cancelation exists in the baffle plane because the distance is equal to both front and rear of the loudspeaker drive unit, which is 180 degrees out of phase. Having a null in the directivity characteristics towards the side walls avoids or minimizes a strong reflection off the sidewalls, which is usually a problem with other systems for enhancing the energy of the late reflections.
  • fig. 1 Illustrates one embodiment of the invention in which a small loudspeaker is equipped with a dipole element for high frequency reproduction, fig.
  • FIG. 2 Illustrates how the rear radiated sound from the dipole element is directed toward left and right sides of the loudspeaker system by reflecting off the acoustic reflector.
  • fig. 3 illustrates the principle behind the present invention
  • fig. 4 illustrates alternative of the shaping of the acoustic rerflector.
  • Fig. 1 Illustrates one embodiment of the invention in which a small loudspeaker is equipped with a dipole element for high frequency reproduction (top driver). Behind this dipole element an acoustic reflector is placed such that the rear radiated sound is redirected towards the sides of the loudspeaker.
  • the shape of the shown acoustic reflector is two plane surfaces meeting in a straight line just behind the dipole element.
  • a top view of the loudspeaker which shows the acoustic reflector as a triangle pointing forward.
  • Fig. 2 (Sheet 2 of 2) Illustrates how the rear radiated sound from the dipole element is directed toward left and right sides of the loudspeaker system by reflecting off the acoustic reflector.
  • the drawing is a top view of the loudspeaker shown in Fig. 1.
  • the wall behind the loudspeaker On the top of the figure is the wall behind the loudspeaker, while the lower part of the figure is the plane baffle in which the dipole element is mounted.
  • the top view of the acoustic reflector which in this embodiment is a triangular shape.
  • Fig. 3 illustrated the principle behind the present invention, where a dipole element 301 is illustrated seen from above.
  • the arrows 303 and 305 illustrates that the acoustic reflector (not shown) should have a shape with a width increasing in the direction of the arrows relative to the dipole element and away from the dipole element. Thereby the acoustic reflector reflects at least a part of the rear radiated sound away in a direction towards the side of the speaker.
  • figure 3 could be an illustration of a dipole element seen from the side and the acoustic element has a shape with a width increasing in the direction of the arrows relative to the dipole element and away from the dipole element.
  • the acoustic reflector reflects at least a part of the rear radiated sound away in a direction towards the top and bottom.
  • the element is a combination of the above whereby the acoustic element has a shape having a width increasing in all direction whereby the reflector reflects at least a part of the rear radiated sound away in a direction towards the sides and the top and bottom.
  • the surface of the acoustic reflector could in one embodiment be smooth to ensure a precise control of the direction of the reflected sound and thereby a more precise sound. In an alternative embodiment the surface could be uneven and ruffled thereby not obtaining the same amount of control resulting in a more diffuse sound.
  • Fig. 4 illustrates two alternative of the shaping of the acoustic reflector, where the reflector is shaped as a circle or sphere in figure 4a and as a parabola or circular cone in figure 4b.
  • parallel surfaces inside the speaker in the area around the dipole element could be damped by adding a damping material to these surfaces, thereby higher order reflections between the parallel surfaces is reduced, damping any sound not being transmitting in a direction almost parallel to the wall behind the speaker.

Landscapes

  • Health & Medical Sciences (AREA)
  • Otolaryngology (AREA)
  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Obtaining Desirable Characteristics In Audible-Bandwidth Transducers (AREA)

Abstract

Cette invention permet d'éviter la réflexion importante qui se produit sur la paroi derrière le haut-parleur. Pour cela, un réflecteur acoustique est placé derrière le circuit d'attaque du haut-parleur afin de rediriger le son loin de la paroi. Toutefois, le son redirigé devrait également être dirigé loin de la position d'écoute. Une direction à peu près perpendiculaire à la paroi derrière le haut-parleur semble être optimale. Cela est par exemple possible grâce à un réflecteur acoustique triangulaire, tel que celui qui est représenté sur les dessins ci-joints. D'autres formes peuvent également être utilisées.
PCT/DK2010/000132 2009-10-07 2010-10-07 Haut-parleur dipôle ayant une propagation diffuse vers l'arrière Ceased WO2011042019A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DKPA200901098 2009-10-07
DKPA200901098 2009-10-07

Publications (1)

Publication Number Publication Date
WO2011042019A1 true WO2011042019A1 (fr) 2011-04-14

Family

ID=43067223

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/DK2010/000132 Ceased WO2011042019A1 (fr) 2009-10-07 2010-10-07 Haut-parleur dipôle ayant une propagation diffuse vers l'arrière

Country Status (1)

Country Link
WO (1) WO2011042019A1 (fr)

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB375166A (en) * 1930-10-17 1932-06-23 Vogt Hans Arrangement for bilateral reproducing sound apparatus, especially for electrostatic loudspeakers
US2483231A (en) * 1946-08-17 1949-09-27 Automatic Elect Lab Loud-speaking telephone set with low acoustic coupling
WO1991001074A1 (fr) * 1989-07-13 1991-01-24 Stark, Henric Enceinte acoustique
US5115882A (en) * 1989-03-29 1992-05-26 Woody D Grier Omnidirectional dispersion system for multiway loudspeakers
US20040065500A1 (en) * 2002-10-04 2004-04-08 Lacarrubba Emanuel Acoustic reproduction device with improved directional characteristics
DE102006015934A1 (de) * 2006-03-29 2007-10-04 Helmut Barth Richtlautsprecher

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB375166A (en) * 1930-10-17 1932-06-23 Vogt Hans Arrangement for bilateral reproducing sound apparatus, especially for electrostatic loudspeakers
US2483231A (en) * 1946-08-17 1949-09-27 Automatic Elect Lab Loud-speaking telephone set with low acoustic coupling
US5115882A (en) * 1989-03-29 1992-05-26 Woody D Grier Omnidirectional dispersion system for multiway loudspeakers
WO1991001074A1 (fr) * 1989-07-13 1991-01-24 Stark, Henric Enceinte acoustique
US20040065500A1 (en) * 2002-10-04 2004-04-08 Lacarrubba Emanuel Acoustic reproduction device with improved directional characteristics
DE102006015934A1 (de) * 2006-03-29 2007-10-04 Helmut Barth Richtlautsprecher

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