(19)
(11)EP 3 515 092 B1

(12)EUROPEAN PATENT SPECIFICATION

(45)Mention of the grant of the patent:
29.07.2020 Bulletin 2020/31

(21)Application number: 19162462.6

(22)Date of filing:  01.04.2015
(51)International Patent Classification (IPC): 
H04R 7/20(2006.01)

(54)

LOUDSPEAKER

LAUTSPRECHER

HAUT-PARLEUR


(84)Designated Contracting States:
AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

(30)Priority: 24.04.2014 GB 201407263

(43)Date of publication of application:
24.07.2019 Bulletin 2019/30

(62)Application number of the earlier application in accordance with Art. 76 EPC:
15162134.9 / 2938099

(73)Proprietor: Funktion One Research
Surrey RH5 4 PS (GB)

(72)Inventors:
  • ANDREWS, Anthony John
    Dorking, Surrey RH5 4PS (GB)
  • NEWSHAM, John
    Dorking, Surrey RH5 4PS (GB)

(74)Representative: Blake, Stephen James 
Marks & Clerk LLP Alpha Tower Suffolk Street Queensway
Birmingham B1 1TT
Birmingham B1 1TT (GB)


(56)References cited: : 
GB-A- 937 838
US-A- 4 319 098
US-A- 2 856 467
US-A1- 2011 044 490
  
      
    Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention).


    Description

    Technical Field



    [0001] The invention relates to loudspeakers. More specifically, the invention relates to damping of vibrations in a diaphragm of a loudspeaker.

    Background



    [0002] Loudspeakers typically comprise an electro-magnetic motor and a diaphragm or cone. The audio driver comprises a voice coil and former that are configured to move in response to electrical signals received at the audio driver. The cone is attached to the voice coil and vibrates with movement of the voice coil to cause a pressure wave, which is heard as sound by a listener.

    [0003] In order to reproduce sound accurately based on the received electrical signals, a cone should ideally have pure pistonic motion. Pistonic motion may be characterised by linear motion of the cone away from and towards a plane of the electro-magnet motor with zero or minimal deformation of the cone, either due to mechanical break up or standing wave patterns.

    [0004] In addition, the cone should be permitted to move freely in response to movement of the voice coil and former. Damping compound may be added to the cone but this increases the mass of the cone, which restricts the free movement of the cone and therefore distorts and/or degrades the sound produced by the loudspeaker.

    [0005] GB937838 discloses a diaphragm coated with an adhesive such that flock, or similarly fibrous material, can be deposited onto the diaphragm.

    [0006] US4319098 discloses a layer of acoustic damping-adhesive material which covers a portion of the diaphragm surface to form an acoustic termination structure.

    [0007] US2011/044490 discloses a diaphragm including a concave part comprising a recess. The recess is filled with an expandable material to supress resonance.

    [0008] US 2856467 discloses to a compound diffraction horn loudspeaker.

    Summary



    [0009] According to an aspect of the invention there is provided a loudspeaker according to claim 1, the loudspeaker comprising: an electro-magnetic motor configured to receive electrical signals and, based on the received electrical signals to induce vibrations in a diaphragm for generating a pressure wave; a surround connected to the diaphragm for suspending the diaphragm from a driver chassis; and a damper in contact with the surround for damping the vibrations in the surround and the diaphragm.

    [0010] Optionally, the diaphragm is a cone.

    [0011] Optionally, the cone comprises a cone input opening connected to the electro-magnetic motor and a cone output opening connected to the surround.

    [0012] Optionally, a surface of the surround is one of corrugated, a half roll or a double half roll.

    [0013] According to the invention, the driver chassis further comprises a lip extending radially inwards and at least partially covering the surround to define a gap therebetween.

    [0014] According to the invention, the damper is positioned in the gap defined between the lip and the surround.

    [0015] According to the invention, the thickness of the damper is greater than the maximum width of the gap between the lip and the surround.

    [0016] Optionally, the damper comprises an annular element configured to at least partially cover the surround.

    [0017] Optionally, the damper comprises one or more of foam and rubber.

    [0018] Optionally, the diaphragm comprises a material comprising one or more of paper, paper composites, paper laminates, aluminium, titanium, beryllium, glass, para-aramid, carbon composites and plastics materials.

    [0019] Optionally, the surround comprises material comprising one or more of paper, cloth, rubber, foam and plastics materials.

    Brief description of drawings



    [0020] Exemplary embodiments of the invention are described herein with reference to the accompanying drawings, in which:

    Figure 1 is a partial section through a loudspeaker;

    Figure 2 is an image of a cone and surround and a waveguide; and

    Figure 3 is an image of a waveguide with a damper attached thereto.


    Description



    [0021] Generally, disclosed herein are loudspeakers in which vibration of the diaphragm has been damped by a damper element. The damper is in contact with a surround or suspension, which is directly connected to an outer edge of the cone.

    [0022] Figure 1 shows a section through a loudspeaker 100. The loudspeaker 100 comprises at least one magnet 102 and a pole piece 104, which are positioned on a back plate 106. The magnet 102 is positioned between the back plate 106 and a top plate 108. The magnet 102 and top plate are annular and surround the pole piece 104. The loudspeaker 100 further comprises a former 110 and voice coil 112. Together, the magnet 102, pole piece 104, back plate 106, top plate 108, former 110 and voice coil 112 form an electro-magnetic motor 114. The electro-magnetic motor 114 is configured to receive electrical signals and induce movement in the voice coil 112 and former 110 based on the received electrical signals.

    [0023] The loudspeaker 100 further comprises a diaphragm, which in the exemplary loudspeaker 100 is a cone 116 and a surround 118. The cone 116 is substantially frustum shaped and has a cone input opening at a smaller diameter end and a cone output opening at a larger diameter end. The cone 116 (and any other type of diaphragm used in other exemplary loudspeakers) may be manufactured from paper, paper composites, paper laminates, aluminium, titanium, beryllium, glass, para-aramid, carbon composites or plastics materials. The cone input opening is attached to the former 110 of the electro-magnetic motor 114.

    [0024] The surround 118 is substantially annular having an inner edge and an outer edge. The inner edge is attached to the cone 116 at the cone output opening. Typically, this attachment is provided by adhesive or bonding agent. The surround 118 is attached at the outer edge to a driver chassis 120 connected to the electro-magnetic motor 114 and configured to support various elements of the loudspeaker 100. Specifically, the driver chassis 120 is substantially frustum shaped and is connected at a smaller diameter end to the top plate 108 and at a larger diameter end to the surround 118.

    [0025] The surround 118 may be manufactured from paper, cloth, rubber, foam or plastics materials. A surface of the surround 118 may be corrugated to allow freedom of movement in the vertical plane and to provide stiffness in a horizontal direction and going through the page with respect to the image in Figure 1, that is, in a direction parallel to the plane of the electro-magnetic motor 114 and circumferential with respect to the surround 118.

    [0026] Relative terms such as upper, lower, vertical, horizontal etc. are used herein to aid description and need not limit the scope of the invention.

    [0027] A dust dome 122 is attached to an internal surface of the cone 116 and covers the centre of the electro-magnetic motor 114, specifically the pole piece 104 the former 110 and the voice coil 112 to prevent dust ingress to the electro-magnetic motor 114. In addition, a suspension 124 (spider) is connected to the driver chassis 120 and to the cone opening end of the cone 116 to support the cone 116 at the point where it is attached to the former 110.

    [0028] A damper 126 is in contact with the surround 118 and is configured to damp the vibrations of the surround 118 and the cone 116. As the surround 118 is attached to the cone 116, the damper 126 therefore damps the vibration of the cone 116 and the surround 118. This results in damped oscillations of the cone 116 during operation of the loudspeaker 100. As such, the deformation of the cone 116, either due to mechanical break up or standing wave patterns is reduced.

    [0029] The damper 126 may be configured to critically damp the oscillations of the cone 116. In exemplary loudspeakers, the damper 126 may comprise foam. In exemplary loudspeakers, the damper 126 may comprise rubber.

    [0030] Exemplary loudspeakers 100, which are useful for understanding the invention further comprise a waveguide 128 having a waveguide input opening and a waveguide output opening. The waveguide input opening is configured to cooperate with the cone output opening to guide the audio waves emitted from the cone 116. The waveguide input opening is substantially circular and may have a diameter substantially equal to the cone output opening, which is the opening of the cone that has the largest diameter or "body diameter". The waveguide 128 comprises a flange 130 at the waveguide input opening. The flange 130 extends radially outwards. The flange 130 is configured for attachment to the driver chassis 120 such that the flange 130 extends at least partially over the surround 118.

    [0031] The damper 126 may be positioned, at least partially, between the flange 130 and the surround 118. The damper 126 may have a thickness greater than the maximum gap between the flange 130 and the surround 118 such that the damper 126 is under compression. The damper may be annular and may cover a portion of the surround around its entire circumference. This allows the surround to vibrate but mitigates or removes any non-uniform vibration of the surround.

    [0032] A sealing gasket 131 may also be adhered to the surround 118 and the driver chassis 120 in a gap between the driver chassis 120 and the flange 130.

    [0033] In exemplary loudspeakers, when the waveguide 128 is fixed to the driver chassis 120, the flange 130 may not be parallel with a centre line running through the corrugations of the surround 118. This is not shown in Figure 1 but may be the case in exemplary loudspeakers. Specifically, the flange 130 and the surround 118 may converge as they extend radially outwards such that a gap between the surround 118 and the flange 130 is greater at the waveguide input opening than at the point where the surround 118 is attached to the driver chassis 120.

    [0034] In loudspeakers according to the invention, the driver chassis 120 has a lip that extends radially inwardly towards the centre of the loudspeaker 100 and defines a cavity within which the surround 118 is attached to the driver chassis 120. Therefore, the lip extends at least partially over the surround 118. The sealing gasket and/or the damper are positioned in the cavity formed by the lip. Such loudspeakers have no waveguide connected to the driver chassis 120.

    [0035] Figure 1 shows an exemplary loudspeaker 100 useful for understanding the invention. However, it will be understood that the principles of the invention may be applied to any design of loudspeaker having a cone and a surround to which damping may be applied.

    [0036] Figure 2 shows an exemplary loudspeaker useful for understanding the invention and comprising a waveguide 128 and a corresponding cone 116, surround 118 and driver chassis 120. The corrugations in the surround 118 can be seen in Figure 2. The flange 130 of the waveguide 128 may be placed over the driver chassis 120 and surround 118 and secured by bolts through holes 132a and 132b.

    [0037] Figure 3 shows an exemplary loudspeaker useful for understanding the invention and comprising a damper 126 secured to the flange 130 of the waveguide 128. To construct the loudspeaker 100, the damper 126 may be attached to the flange 130 and the flange 130 may then be bolted to the driver chassis 120 compressing the damper in between the flange and the surround.

    [0038] The invention may also be applied to other types of loudspeaker such as a compression driver, in which the diaphragm may be dome shaped and may have a single annular suspension or surround.


    Claims

    1. A loudspeaker (100) comprising:

    a driver chassis (120);

    an electro-magnetic motor (114) configured to receive electrical signals and, based on the received electrical signals to induce vibrations in a diaphragm for generating a pressure wave;

    a surround (118) connected to the diaphragm for suspending the diaphragm from the driver chassis (120); and

    a damper (126) in contact with the surround (118) for damping the vibrations in the surround (118) and the diaphragm, characterised by

    the driver chassis (120) comprising a lip extending radially inwards and at least partially covering the surround (118) to define a gap therebetween; and

    wherein the damper (126) is positioned in the gap defined between the lip and the surround (118) and the thickness of the damper (126) is greater than the maximum width of the gap between the lip and the surround (118).


     
    2. A loudspeaker (100) according to claim 1, wherein the diaphragm is a cone (116).
     
    3. A loudspeaker (100) according to claim 2, wherein the cone (116) comprises a cone input opening connected to the electro-magnetic motor (114) and a cone output opening connected to the surround (118).
     
    4. A loudspeaker (100) according to claim 1 or 2, wherein a surface of the surround (118) is one of corrugated, a half roll or a double half roll.
     
    5. A loudspeaker (100) according to any preceding claim, wherein the damper (126) comprises an annular element configured to at least partially cover the surround (118).
     
    6. A loudspeaker (100) according to any preceding claim, wherein the damper (126) comprises one or more of foam and rubber.
     
    7. A loudspeaker (100) according to any preceding claim, wherein the diaphragm comprises a material comprising one or more of paper, paper composites, paper laminates, aluminium, titanium, beryllium, glass, para-aramid, carbon composites and plastics materials.
     
    8. A loudspeaker (100) according to any preceding claim, wherein the surround (118) comprises material comprising one or more of paper, cloth, rubber, foam and plastics materials.
     


    Ansprüche

    1. Lautsprecher (100), umfassend:

    ein Treiberchassis (120);

    einen elektromagnetischen Motor (114), welcher konfiguriert ist, um elektrische Signale zu empfangen und, basierend auf den empfangenen elektrischen Signalen, Schwingungen in einer Membran zur Erzeugung einer Druckwelle zu induzieren;

    eine Einfassung (118), welche mit der Membran zum Suspendieren der Membran vom Treiberchassis (120) verbunden ist; und

    einen Dämpfer (126), welcher mit der Einfassung (118) zum Dämpfen der Schwingungen in der Einfassung (118) und in der Membran in Kontakt steht; dadurch gekennzeichnet,

    dass der Treiberchassis (120) einen Rand umfasst, der sich radial nach innen erstreckt und die Einfassung (118) mindestens teilweise abdeckt, um einen Spalt dazwischen zu definieren; und

    wobei der Dämpfer (126) in dem zwischen dem Rand und der Einfassung (118) definierten Spalt positioniert ist, und die Dicke des Dämpfers (126) größer als die maximale Dicke des Spalts zwischen dem Rand und der Einfassung (118) ist.


     
    2. Lautsprecher (100) nach Anspruch 1, wobei die Membran aus einem Kegel (116) besteht.
     
    3. Lautsprecher (100) nach Anspruch 2, wobei der Kegel (116) eine Kegeleingangsöffnung, welche mit dem elektromagnetischen Motor (114) verbunden ist, und eine Kegelausgangsöffnung umfasst, welche mit der Einfassung (118) verbunden ist.
     
    4. Lautsprecher (100) nach Anspruch 1 oder 2, wobei eine Oberfläche der Einfassung (118) wellenförmig, halbrollenförmig oder doppelhalbrollenförmig ist.
     
    5. Lautsprecher (100) nach einem der vorhergehenden Ansprüche, wobei der Dämpfer (126) ein Ringelement umfasst, welches konfiguriert ist, um die Einfassung (118) mindestens teilweise abzudecken.
     
    6. Lautsprecher (100) nach einem der vorhergehenden Ansprüche, wobei der Dämpfer (126) eines oder beide von Schaumstoff und Gummi umfasst.
     
    7. Lautsprecher (100) nach einem der vorhergehenden Ansprüche, wobei die Membran ein Material umfasst, welches eines oder mehrere von Papier, Papierverbundstoffen, Papierlaminaten, Aluminium, Titan, Beryllium, Glas, Para-Aramid, Kohlenstoffverbundstoffen und Kunststoffmaterialien umfasst.
     
    8. Lautsprecher (100) nach einem der vorhergehenden Ansprüche, wobei die Einfassung (118) ein Material umfasst, welches eines oder mehrere von Papier, Gewebe, Gummi, Schaumstoff und Kunststoffmaterialien umfasst.
     


    Revendications

    1. Haut-parleur (100) comprenant:

    un chassis de commande (120) ;

    un moteur électromagnétique (114) conçu pour recevoir des signaux électriques et, en fonction des signaux électriques reçus, pour induire des vibrations dans un diaphragme afin de produire une onde de pression ;

    une bordure (118) reliée au diaphragme pour effectuer la suspension du diaphragme à partir du chassis de commande (120) ; et

    un amortisseur (126) en contact avec la bordure (118) afin d'amortir les vibrations dans la bordure (118) et le diaphragme, caractérisé par

    le chassis de commande (120) comprenant une lèvre s'étendant radialement vers l'intérieur et couvrant au moins partiellement la bordure (118) pour définir un espace entre eux; et

    dans lequel l'amortisseur (126) est positionné dans l'espace défini entre la lèvre et la bordure (118), et l'épaisseur de l'amortisseur (126) est supérieure à la largeur maximale de l'espace entre la lèvre et la bordure (118).


     
    2. Haut-parleur (100) selon la revendication 1, dans lequel le diaphragme est un cône (116).
     
    3. Haut-parleur (100) selon la revendication 2, dans lequel le cône (116) comprend une ouverture d'entrée de cône reliée au moteur électromagnétique (114) et une ouverture de sortie de cône reliée à la bordure (118).
     
    4. Haut-parleur (100) selon la revendication 1 ou 2, dans lequel une surface de la bordure (118) est soit ondulée, en demi-rouleau soit en double demi-rouleau.
     
    5. Haut-parleur (100) selon l'une quelconque des revendications précédentes, dans lequel l'amortisseur (126) comprend un élément annulaire conçu pour couvrir au moins partiellement la bordure (118).
     
    6. Haut-parleur (100) selon l'une quelconque des revendications précédentes, dans lequel l'amortisseur (126) comprend un ou plusieurs parmi de la mousse et du caoutchouc.
     
    7. Haut-parleur (100) selon l'une quelconque des revendications précédentes, dans lequel le diaphragme comprend un matériau comprenant un ou plusieurs parmi le papier, les composites à base de papier, les stratifiés à base de papier, l'aluminium, le titane, le béryllium, le verre, le para-aramide, les composites à base de carbone et les matières plastiques.
     
    8. Haut-parleur (100) selon l'une quelconque des revendications précédentes, dans lequel la bordure (118) comprend un matériau comprenant un ou plusieurs parmi le papier, le tissu, le caoutchouc, la mousse et les matières plastiques.
     




    Drawing











    Cited references

    REFERENCES CITED IN THE DESCRIPTION



    This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.

    Patent documents cited in the description