Method for use in producing a loudspeaker

Abstract

A method for use in producing an electromechanical transducer. The method includes: providing a precursor electromechanical transducer and a precursor damper. The precursor electromechanical transducer includes a static assembly and a movable assembly. The precursor damper includes: an outer portion which defines an outer periphery of the precursor damper, and which includes first and second outer portion segments; an inner portion which defines an inner periphery of the precursor damper, and which includes first and second inner portion segments; at least one first bridge portion which connects the first outer portion segment to the first inner portion segment; at least one second bridge portion which connects the second outer portion segment to the second inner portion segment. The first outer portion segment includes a first outer connection formation for forming an electrical connection between the first outer portion segment and an electrical signal source. The second outer portion segment includes a second outer connection formation for forming an electrical connection between the second outer portion segment and the electrical signal source. The first inner portion segment includes a first inner connection formation for forming an electrical connection between the first inner portion segment and the movable assembly. The second inner portion segment includes a second inner connection formation for forming an electrical connection between the second inner portion segment and the movable assembly. The first outer portion segment, first inner portion segment and first bridge portion provide a first part of the precursor damper. The second outer portion segment, second inner portion segment and second bridge portion provide a second part of the precursor damper. The first part and second part of the precursor damper are physically attached to each other by at least one severable feature. The method includes installing the precursor damper in the precursor electromechanical transducer so that the first outer portion segment is attached to the static assembly, the first inner portion segment is attached to the movable assembly, the second outer portion segment is attached to the static assembly, and the second inner portion segment is attached to the movable assembly; then forming a damper from the precursor damper by severing the at least one severable feature which physically attaches the first part and the second part of the precursor damper to each other so that the first part and the second part of the damper are physically separated from each other by air.

Description

[0001] 008857328

[0002] 1

[0003] METHOD FOR USE IN PRODUCING A LOUDSPEAKER

[0004] This application claims priority to CN202411545172.7 filed 31 October 2024.

[0005] Field of the Invention

[0006] The present invention relates to a method for use in producing a loudspeaker.

[0007] Background

[0008] A traditional loudspeaker includes a frame, a drive unit and a diaphragm, wherein the diaphragm is suspended from the frame by one or more suspensions, and wherein the drive unit is configured to move the diaphragm along a movement axis.

[0009] The diaphragm is typically dish shaped, and may e.g. be conically shaped, e.g. taking the form of a frustocone.

[0010] The drive unit is typically an electromagnetic drive unit that includes a magnet unit configured to produce a magnetic field in an air gap, and a voice coil attached to the diaphragm (typically via an intermediary coupling element, such as a voice coil former). The magnet unit may be attached to a frame. In use, the voice coil may be energized (have a current passed through it based on an electrical signal from an electrical signal source) to produce a magnetic field which interacts with the magnetic field produced by the magnet unit and which causes the voice coil (and therefore the diaphragm) to move relative to the magnet unit along the movement axis. The magnet unit may include a permanent magnet. The voice coil may be configured to sit in the air gap when the diaphragm is at rest.

[0011] A traditional loudspeaker, e.g. as described above, can be seen as including a static assembly and a moveable assembly. For example, the static assembly might include the frame and the magnet unit. The moveable assembly might include the diaphragm and voice coil. The / each suspension included in a traditional loudspeaker, e.g. as described above, may interconnect the static assembly and the moveable assembly.

[0012] The one or more suspensions included in a traditional loudspeaker, e.g. as described above, may include a roll suspension (also known as a “surround”), which is typically is attached to the static assembly (e.g. a frame of the loudspeaker) and is further attached to the moveable assembly at an outer periphery of the diaphragm. A roll suspension typically has a curved profile when viewed in cross-section in a plane containing the movement axis.

[0013] The one or more suspensions included in a traditional loudspeaker, e.g. as described above, may include a damper. A damper is typically attached to the static assembly (e.g. a frame of the loudspeaker) and is further attached to the moveable assembly at a location radially inwards of the outer periphery of the diaphragm. A damper typically serves to provide damping and centering for the voice coil while the voice coil is moving. For example, the damper may be attached to a voice coil of the moveable assembly (see e.g. Fig. 2B of WO2022 / 189546A1), or attached to the diaphragm itself (see e.g. WO2008 / 135857A1). A damper typically is typically disc-shaped, but it does not need to be flat, since it may e.g. include corrugations when viewed in cross-section (see e.g. Fig. 2B of WO2022 / 189546A1).

[0014] A traditional damper is typically made of a textile material, but it is also possible to have a damper made of metal, see e.g. WO2022268451 A1 or JP2010147839.

[0015] A traditional loudspeaker typically includes electrical tags, which are for connecting to an (external) electrical signal source, and flexible lead wires which each connect a respective one of the electrical tags to the voice coil, so that an electrical signal from the electrical signal source is able to energize the voice coil as described above.

[0016] Lead wires typically need to be shaped in order to give them the correct shape and position to prevent the lead wires from contacting the damper or the diaphragm when the loudspeaker is in use. The electrical tags are usually insert molded or pressed in the frame of the loudspeaker to fix the end of the lead wires.

[0017] In order to have soft connections between lead wires and the electrical tags, glue is often needed to fix the lead wires to the tags in addition to soldering the metal core of the lead wires to the electrical tags.

[0018] Typically, textile dampers are supplied to loudspeaker manufacturers by a separate supplier. Producing a textile damper is a complex process involving numerous manufacturing steps such as impregnating, cutting, hot pressing, adjust the shape, and cutting again. The supplier of the textile damper may also produce lead wires and solder the lead wires on a solder pad (e.g. of copper) on a voice coil former, with the voice coil former, voice coil and damper then being supplied to the loudspeaker manufacturer in assembled form.

[0019] Producing electrical tags and insert molding or pressing the electrical tags in the frame of the loudspeaker can similarly be complicated.

[0020] Despite the loudspeaker manufacture process as outlined above being quite mature and stable, the present inventors do not consider it to be particularly efficient, since many components are needed, the cost of materials can be high, and the need to shape the flexible lead wires can be difficult, particularly if space within the loudspeaker is limited.

[0021] Moreover, the presence of flexible lead wires may unbalance the one or more suspensions used to suspend the diaphragm from the frame, particularly if a lightweight diaphragm is used.

[0022] Various damper forms have been disclosed previously, some of which involve using the metal damper to provide an electrical connection to the voice coil, see for example:

[0023] • US1906379

[0024] • US1907687

[0025] • US5008945

[0026] US6853734B2

[0027] W02021089990A1 US1757386

[0028] • JPS53142030U

[0029] • JP2000232699

[0030] • JP2010147839

[0031] • US9635446B2

[0032] • CN218450523U

[0033] The present invention has been devised in light of the above considerations.

[0034] Summary of the Invention

[0035] In a first aspect, the present invention provides:

[0036] A method for use in producing an electromechanical transducer the method including: providing a precursor electromechanical transducer and a precursor damper; wherein the precursor electromechanical transducer includes a static assembly and a movable assembly; wherein the precursor damper includes: an outer portion which defines an outer periphery of the precursor damper, and which includes first and second outer portion segments; an inner portion which defines an inner periphery of the precursor damper, and which includes first and second inner portion segments; at least one first bridge portion which connects the first outer portion segment to the first inner portion segment; at least one second bridge portion which connects the second outer portion segment to the second inner portion segment; wherein the first outer portion segment includes a first outer connection formation for forming an electrical connection between the first outer portion segment and an electrical signal source; wherein the second outer portion segment includes a second outer connection formation for forming an electrical connection between the second outer portion segment and the electrical signal source; wherein the first inner portion segment includes a first inner connection formation for forming an electrical connection between the first inner portion segment and (e.g. a voice coil of) the movable assembly; wherein the second inner portion segment includes a second inner connection formation for forming an electrical connection between the second inner portion segment and (e.g. a voice coil of) the movable assembly; wherein the first outer portion segment, first inner portion segment and first bridge portion provide a first part of the precursor damper; wherein the second outer portion segment, second inner portion segment and second bridge portion provide a second part of the precursor damper; wherein the first part and second part of the precursor damper are physically attached to each other by at least one severable feature; installing the precursor damper in the precursor electromechanical transducer so that the first outer portion segment is attached to the static assembly, the first inner portion segment is attached to the movable assembly, the second outer portion segment is attached to the static assembly, and the second inner portion segment is attached to the movable assembly; then forming a damper from the precursor damper by severing the at least one severable feature which physically attaches the first part and the second part of the precursor damper to each other so that the first part and the second part of the damper are physically separated from each other by air.

[0037] Advantageously, after the at least one severable feature has been severed, the first and second parts of the damper are able to provide both the function of a damper, and provide two separate electrical connections (from the first and second outer connection formations) to (e.g. a voice coil of) the moveable assembly. Moreover, since the precursor damper is installed before the at least one severable feature is severed, the precursor damper can be installed as a single element, which simplifies its installation. Furthermore, if the first and second parts of the damper were produced as separate elements each part can deform more easily than if they are connected by severable features which are severed after installation.

[0038] The movable assembly may be configured to move relative to the static assembly along a movement axis, when the electromechanical transducer is produced from the precursor electromechanical transducer. Of course, a skilled reader would appreciate that the movable assembly may not be able to move relative to the static assembly prior to the electromechanical transducer being produced from the precursor electromechanical transducer (e.g. during one or more steps being performed in a method according to the first aspect of the invention), e.g. since, for example, some components of the precursor electromechanical transducer may be fixed in place by a manufacturing jig during one or more steps performed in a method according to the first aspect of the invention. Thus a skilled person would understand that the term “movable assembly” in the context of this disclosure refers to the movable assembly being able to move relative to the “static assembly” in an electromechanical transducer produced by a method according to the first aspect of the invention, rather than whilst a method according to the first aspect of the invention is being carried out.

[0039] Herein, the “first inner connection formation” may in some examples be referred to as the “first inner connection portion”, and the terms “first inner connection formation” and “first inner connection portion” may be used interchangeably.

[0040] Herein, the “second inner connection formation” may in some examples be referred to as the “second inner connection portion”, and the terms “second inner connection formation” and “second inner connection portion” may be used interchangeably. Herein, the “first outer connection formation” may in some examples be referred to as the “first outer connection portion”, and the terms “first outer connection formation” and “first outer connection portion may be used interchangeably.

[0041] Herein, the “second outer connection formation” may in some examples be referred to as the “second outer connection portion”, and the terms “second outer connection formation” and “second outer connection portion” may be used interchangeably.

[0042] Preferably, the at least one first bridge portion provides an electrical connection between the first outer connection formation (which may be referred to as the “first outer connection portion”) and the first inner connection formation (which may be referred to as the “first inner connection portion”), and the at least one second bridge portion provides an electrical connection between the second outer connection formation (which may be referred to as the “second outer connection portion”) and the second inner connection formation (which may be referred to as the “second inner connection portion”). This may be achieved, for example, by the precursor damper being formed of metal, but could also be achieved by forming conductive tracks on the precursor damper if the precursor damper is formed of another material (e.g. flexible PCB and / or plastic). By the bridge portions forming electrical connections in this way, the present invention can omit the need for lead wires. The omission of lead wires may help to improve the balance of the damper and can reduce the total height of an electromechanical transducer produced using the present method. Furthermore, the cost of lead wires is reduced. Additionally, the steps of shaping lead wires are omitted, reducing the cost and complexity of the manufacturing process.

[0043] In some examples, the electromechanical transducer may be a loudspeaker and the precursor electromechanical transducer is a precursor loudspeaker. Where the electromechanical transducer is a loudspeaker, the term “electromechanical transducer” may be replaced by “loudspeaker”, and the term “precursor electromechanical transducer” may be replaced with “precursor loudspeaker” herein.

[0044] In other examples, the electromechanical transducer may be a shaker. A shaker is typically very similar to a loudspeaker, but does not include a diaphragm. Although in all the examples shown in the drawings the electromechanical transducer is a loudspeaker, the same principles could be used to make a shaker (e.g. by omitting the inclusion of a diaphragm).

[0045] In some examples, the precursor damper is formed from metal. However, the precursor damper may be formed from other materials, e.g. flexible PCB and / or plastic.

[0046] In some examples, the precursor damper is integrally formed as a single piece of material.

[0047] Thus the / each severable feature may be integrally formed with the remainder of the precursor damper. This can help to simplify manufacture of the precursor damper, and ultimately, the electromechanical transducer.

[0048] Preferably, the precursor damper is integrally formed as a single piece of metal. This helps the at least one first bridge portion provide an electrical connection between the first outer connection formation (aka the “first outer connection portion”) and the first inner connection formation (aka the “first inner connection portion”), and helps the at least one second bridge portion provide an electrical connection between the second outer connection formation (aka the “second outer connection portion”) and the second inner connection formation (aka the “second inner connection portion”) as described previously.

[0049] In some examples, the / each severable feature includes a region of material that is thinner than the immediately adjacent portions of the first and second parts of the precursor damper to which the severable feature is physically attached.

[0050] The region of material (included in the / each severable feature) may be thinner (than the immediately adjacent portions of the first and second parts of the precursor damper to which the severable feature is physically attached) as measured in a plane perpendicular to the movement axis.

[0051] In some examples, the first and second parts of the damper have a thickness T as measured in a direction parallel to the movement axis, and the / each severable feature has a width as measured in a plane perpendicular to the movement axis that is between 0.5mm and 2*T.

[0052] In some examples, the / each severable feature includes a bent portion of material formed integrally with the first and second parts of the precursor electromechanical transducer.

[0053] For the / each severable feature, the / each severable feature may include a first arm, a second arm, and a base, wherein the first arm is joined to the first part of the precursor damper, the second arm is joined to the second part of the precursor damper, and the first arm and the second arm are joined together by the base. For example, the c severable feature may have a ‘U’ shape or a ‘V’ shape.

[0054] For the / each severable feature, the first and second arms of the severable feature may be thinner than the base of the severable feature, e.g. as measured in a plane perpendicular to the movement axis.

[0055] In some examples, the at least one severable feature includes: at least one outer severable feature (preferably at least two severable features) which physically attaches the first outer portion segment to the second outer portion segment; at least one inner severable feature (preferably at least two severable features) which physically attaches the first inner portion segment to the second inner portion segment.

[0056] In some examples (not shown), the at least one severable feature may include a severable feature which physically attaches the first bridge portion to the second bridge portion.

[0057] Having at least one inner severable portion (preferably two or more inner severable portions) helps to reduce relative movement of the first and second inner portion segments thereby improving the stability of the precursor damper. Similarly, having at least one outer severable portion (preferably two or more outer severable portions) helps to reduce relative movement of the first and second outer portion segments thereby improving the stability of the precursor damper.

[0058] It may in some examples be preferable to avoid having severable portions between the first and second bridge portions, since these may be carefully tuned to provide a desired frequency response for the electromechanical transducer (e.g. loudspeaker).

[0059] In some examples, severing the at least one severable feature includes cutting the at least one severable feature, e.g. by cutting the first and second arms of the severable feature. The static assembly of the precursor electromechanical transducer may include a frame, and optionally a magnet unit.

[0060] The movable assembly of precursor electromechanical transducer may include a voice coil, and optionally a voice coil former on which the voice coil is mounted.

[0061] The voice coil mounted on the voice coil former may include: a first solder pad configured to provide an electrical connection to the first inner connection formation; and a second solder pad configured to provide an electrical connection to the second inner connection formation.

[0062] For the purpose of this disclosure, the solder pads are treated as being part of the voice coil, even if they are physically separated from the coiled wire part of the voice coil (and, for example, connected to the coiled wire part of the voice coil by wire or tracks on the voice coil former).

[0063] The method may include: forming the electrical connection between the first inner portion segment and (e.g. the voice coil of) the movable assembly via the first inner connection formation (aka the “first inner connection portion”); and forming the electrical connection between the second inner portion segment and (e.g. the voice coil of) the movable assembly via the second inner connection formation (aka the “second inner connection portion”).

[0064] In some examples: forming the electrical connection between the first inner portion segment and the movable assembly via the first inner connection formation (aka the “first inner connection portion”) may include soldering the first inner connection formation to (e.g. the first solder pad of) the voice coil so as to provide a physical attachment between the first inner portion segment and the movable assembly; and forming the electrical connection between the second inner portion segment and the movable assembly via the second inner connection formation (aka the “second inner connection portion”) may include soldering the second inner connection formation to (e.g. the second solder pad of) the voice coil so as to provide a physical attachment between the second inner portion segment and the movable assembly

[0065] Thus, in some examples, the steps of forming the electrical connections between the inner portion segments and the movable assembly may form part of installing the precursor damper in the precursor electromechanical transducer (whereby the forming of these electrical connections also serve to provide an attachment between the inner portion segments and the movable assembly).

[0066] In other examples, the steps of forming the electrical connections between the inner portion segments and the movable assembly may be performed prior to installing the precursor damper in the precursor electromechanical transducer (in which case the first and second inner portion segments may be attached to the movable assembly before the precursor damper is installed in the precursor electromechanical transducer). The method may include: forming the electrical connection between the first outer portion segment and an electrical signal source; and forming the electrical connection between the second outer portion segment and the electrical signal source. However, typically these steps would be performed by a purchaser of an electromechanical transducer produced according to the present method, rather than as part of a method for use in producing the electromechanical transducer.

[0067] In some examples: the first inner connection formation (aka the “first inner connection portion”) includes a first rib which extends inwardly towards (e.g. a voice coil of) the movable assembly when the precursor damper is installed in the precursor electromechanical transducer; and the second inner connection formation (aka the “second inner connection portion”) includes a second rib which extends inwardly towards (e.g. a voice coil of) the movable assembly when the precursor damper is installed in the precursor electromechanical transducer.

[0068] In some examples: the first rib includes a first portion which extends inwardly towards (e.g. a voice coil of) the movable assembly when the precursor damper is installed in the precursor electromechanical transducer, and a second portion, distal from the first portion, which extends along the movement axis when the precursor damper is installed in the precursor electromechanical transducer; and the second rib includes a first portion which extends inwardly towards (e.g. a voice coil of) the movable assembly when the precursor damper is installed in the precursor electromechanical transducer, and a second portion, distal from the first portion, which extends along the movement axis when the precursor damper is installed in the precursor electromechanical transducer.

[0069] The distal second portion of each rib may help to provide a greater surface area in contact with the (e.g. voice coil and voice coil former of the) movable assembly when the precursor damper is installed in the precursor electromechanical transducer. This may help to provide stronger and more robust physical attachment between the precursor damper and the movable assembly, e.g. if the first and second ribs are soldered to the voice coil (optionally also the voice coil former).

[0070] In some examples: the first inner connection formation is shaped to form a respective gap between the first inner connection formation and (e.g. the voice coil former of) the movable assembly on each side of the first rib when the precursor damper is installed in the precursor electromechanical transducer; and the second inner connection formation is shaped to form a respective gap between the second inner connection formation and (e.g. the voice coil former of) the movable assembly on each side of the second rib when the precursor damper is installed in the precursor electromechanical transducer.

[0071] While electrically connecting the inner connections and the voice coil, these respective gaps may help to allow liquid solder to contact a greater area of the movable assembly (e.g. voice coil and / or voice coil former of the movable assembly), thereby providing stronger and more robust physical attachment between the damper and the movable assembly, e.g. if the first and second ribs are soldered to the voice coil (and optionally the voice coil former) of the movable assembly. In some examples: the first inner connection formation includes a respective hole on each side of the first rib; and the second inner connection formation includes a respective hole on each side of the second rib.

[0072] Such holes can be useful to inhibit heat diffusion into the first and second inner portion segments if the first and second ribs are soldered to the voice coil.

[0073] In some examples, installing the precursor damper in the precursor electromechanical transducer may include: attaching the first outer portion segment to the static assembly; attaching the first inner portion segment to the movable assembly; attaching the second outer portion segment to the static assembly; and attaching the second inner portion segment to the movable assembly.

[0074] In some examples, attaching the first and second outer portion segments to the static assembly may involve inset molding or pressing the first and second outer portion segments into a frame of the static assembly, for example.

[0075] In some examples, attaching the first and second outer portion segments to the static assembly may involve adhering (e.g. with glue) the first and second outer portion segments to a frame of the static assembly.

[0076] In some examples, attaching the first and second inner portion segments to the movable assembly may involve soldering the first inner connection formation to (e.g. the first solder pad of) the voice coil and soldering the second inner connection formation to (e.g. the second solder pad of) the voice coil as described previously, though other ways of attaching the first and second inner portion segments to the movable assembly (e.g. adhering, e.g. with glue) are possible.

[0077] In some examples, the first outer connection formation is a first electrical tag integrally formed with the first outer portion segment, and the second outer connection formation is a second electrical tag integrally formed with the second outer portion segment.

[0078] Advantageously, by providing an integral electrical tag, the present method omits the need for a separate method step to attach an electrical tag. Compared to a traditional damper, the present damper may help to provide a damper, tags and lead wires which can be a provided as a single physical element (precursor damper) when it is installed.

[0079] In some examples: the first electrical tag may extend outwardly away from the first outer portion segment; and the second electrical tag may extend outwardly away from the second outer portion segment.

[0080] In some examples: the first electrical tag may include a first portion which extends along the movement axis when the precursor damper is installed in the precursor electromechanical transducer, and a second portion, distal to the first portion, which extends outwardly away from the first outer portion segment the second electrical tag may include a first portion which extends along the movement axis when the precursor damper is installed in the precursor electromechanical transducer, and a second portion, distal to the first portion, which extends outwardly away from the second outer portion segment.

[0081] In some examples, the method may include: forming the electrical connection between the first outer portion segment and an electrical signal source (e.g. via the first outer connection formation); and forming the electrical connection between the second outer portion segment and the electrical signal source (e.g. via the second outer connection formation). However, normally the steps of forming the electrical connections with the electrical signal source are performed by an end user, i.e. after the electromechanical transducer has been produced.

[0082] In some examples, each bridge portion may include a (respective) torsion relief region, e.g. configured so as to relieve torsional stress on the bridge portion when the movable assembly moves relative to the static assembly along the movement axis.

[0083] The torsion relief region of each bridge portion may, as the bridge portion extends from an outer portion segment to an inner portion segment, trace a path which initially extends inwardly towards the movement axis, then outwardly away from the movement axis. For example, the torsion relief region may be ‘U’ shaped, when viewed in a plane perpendicular to the movement axis. The torsion relief region may be joined to the outer portion segment. The torsion relief region may further be joined to a circumferentially extending region of the bridge portion, wherein the circumferentially extending region of the bridge portion extends circumferentially with respect to the movement axis, is joined to the inner portion segment, and is located between the torsion relief region and the inner portion segment.

[0084] As discussed below in more detail (see discussion of Fig.13), a torsion relief region as described above may help to improve the longevity of the bridge portions (and thus the damper, once formed).

[0085] In some examples, the precursor damper may include third and fourth parts.

[0086] For example, the precursor damper may include third and fourth parts wherein: the third part of the precursor damper may include: a third outer portion segment of the outer portion of the precursor damper; a third inner portion segment of the inner portion of the precursor damper; at least one third bridge portion which connects the third outer portion segment to the third inner portion segment; wherein the third outer portion segment includes a third outer connection formation for forming an electrical connection between the third outer portion segment and an electrical signal source; wherein the third inner portion segment includes a third inner connection formation for forming an electrical connection between the third inner portion segment and (e.g. a voice coil of) the movable assembly; the fourth part of the precursor damper includes: a fourth outer portion segment of the outer portion of the precursor damper; a fourth inner portion segment of the inner portion of the precursor damper; at least one fourth bridge portion which connects the fourth outer portion segment to the fourth inner portion segment; wherein the fourth outer portion segment includes a fourth outer connection formation for forming an electrical connection between the fourth outer portion segment and an electrical signal source; wherein the fourth inner portion segment includes a fourth inner connection formation for forming an electrical connection between the fourth inner portion segment and (e.g. a voice coil of) the movable assembly; wherein the first part, second part, third part and fourth part of the precursor damper are physically attached to each other by a plurality of severable features; wherein the precursor damper is installed in the precursor electromechanical transducer so that the third outer portion segment is attached to the static assembly, the third inner portion segment is attached to the movable assembly, the fourth outer portion segment is attached to the static assembly, and the fourth inner portion segment is attached to the movable assembly; then wherein forming the damper from the precursor damper includes severing the plurality of severable features which physically attaches the first part, second part, third part and fourth part of the precursor damper to each other so that the first part, second part, third part and fourth part of the damper are physically separated from each other by air.

[0087] The various features already recited in connection with the first and second damper parts may be applied equally to the third and fourth damper parts.

[0088] In some examples, the precursor damper may include yet further parts, e.g. fifth and sixth parts.

[0089] In some examples, each bridge portion of the damper may extend circumferentially around the movement axis. This may help increase design freedom, by allowing the bridge portions to have greater length without increasing the diameter of the damper (and associated material costs) and / or by influencing the frequency response of the damper, when the electromechanical transducer (e.g. loudspeaker) is in use.

[0090] In some examples, each bridge portion may have a width (as measured in a plane perpendicular to the movement axis) which varies along its length.

[0091] In some examples, each bridge portion of the damper may include a w / t<=1 .5 region, where w is the width of the bridge portion as measured in a direction in a plane perpendicular to the movement axis and where t is the thickness of the bridge portion as measured in a direction parallel to the movement axis, wherein the w / t<=1 .5 bridge region has a length that is between 40% and 60% of the length of the bridge portion. In some examples, outside of the w / t<=1 .5 region, the bridge portion 636 might not have w / t <=1.5.

[0092] The present inventors have found that having such a w / t<=1 .5 region as described above can be helpful in achieving a desirable frequency response for the electromechanical transducer (e.g. loudspeaker), e.g. as described below in connection with the “first antiphase resonance frequency”.

[0093] In some examples, the damper has a Von Mises stress of less than 2000 MPa, preferably less than 1200 MPa. The inventors have found that designing a damper with a low Von Mises stress may improve the lifetime of the damper. The Von Mises stress may be evaluated based on the material tensile stress and yield stress.

[0094] Von Mises stress may be measured by simulation, as is known in the art.

[0095] In some examples, the first inner portion segment may be attached to the movable assembly and the second inner portion segment may be attached to the movable assembly prior to installing the precursor damper in the precursor electromechanical transducer.

[0096] In other examples, method steps of attaching the first inner portion segment to the movable assembly (e.g. by soldering the first inner portion segment to the voice coil - see above) and attaching the second inner portion segment to the movable assembly (e.g. by soldering the first inner portion segment to the voice coil - see above) may be performed as part of installing the precursor damper in the precursor electromechanical transducer.

[0097] The method may include producing the electromechanical transducer from the precursor electromechanical transducer, in which case the preamble of the method may be rewritten from “a method for use in producing an electromechanical transducer” to “a method of producing an electromechanical transducer”.

[0098] In some examples, producing the electromechanical transducer from the precursor electromechanical transducer may include, after the precursor damper has been installed in the precursor electromechanical transducer, and after forming the damper from the precursor damper, one or more subsequent method steps.

[0099] The one or more subsequent method steps may, for example, include adding one or more further components to the static assembly and / or movable assembly of the precursor electromechanical transducer.

[0100] For example, producing the electromechanical transducer from the precursor electromechanical transducer may include: installing a magnet unit in the precursor electromechanical transducer so that the magnet unit forms part of the static assembly (e.g. by attaching it to the frame).

[0101] For example, where the electromechanical transducer is a loudspeaker, producing the loudspeaker from the precursor loudspeaker may include: installing a diaphragm (optionally also a dustcap) in the precursor loudspeaker so that the diaphragm forms part of the movable assembly (e.g. by attaching it to the voice coil former of the movable assembly).

[0102] In the electromechanical transducer, the static assembly may include, for example, the frame and the magnet unit.

[0103] In the electromechanical transducer, the movable assembly may include, for example, the voice coil former and the voice coil. Where the electromechanical transducer is a loudspeaker, the movable assembly may further include a diaphragm (optionally also a dustcap). Where the electromechanical transducer is a shaker, the diaphragm (optionally also the dustcap) may be omitted. In the electromechanical transducer, the movable assembly may be suspended from the static assembly by one or more suspensions, wherein the one or more suspensions include: the damper, and optionally a roll suspension.

[0104] Where the electromechanical transducer is a loudspeaker, the damper (formed by severing the at least one severable feature which physically connects the first and second outer portion segments) may be configured so that the first antiphase resonant frequency of the first and second bridge portions is either: higher than 1 kHz, if the working frequency range of the loudspeaker extends above 1 kHz; at least 100 Hz above the working frequency range of the loudspeaker, if the working frequency range of the loudspeaker does not extend above 1 kHz.

[0105] In this context, the “first antiphase resonance frequency” may be measured by simulating the moving parts of the loudspeaker with the / each suspension having a fixed outer periphery, identifying the first (i.e. lowest) resonant frequency originating from out-of-phase movement of the damper (i.e. movement of the damper that does not move in phase with the diaphragm). Here we note that the loudspeaker would typically have a fundamental resonance frequency, originating from the pistonic (in-phase) movement of the diaphragm, that would typically be lower than the “first antiphase resonance frequency”, but this fundamental resonance frequency does not originate from out of phase movement of the damper (so should not be viewed as the “first antiphase resonance frequency”). Likewise, there may be other resonance frequencies associated with the loudspeaker that do not originate from out-of-phase movement of the damper, for example resonant frequencies associated with the tilt of the movable assembly. These other frequencies can be ignored while simulating the system, for example by simulating the system with certain parts of the loudspeaker being static as described above.

[0106] The inventors have found that configuring the damper so that the first antiphase resonant frequency falls in a range as defined above can help to mitigate noise produced by out-of-phase movement of the damper at low and / or medium frequencies..

[0107] We also note that the “first antiphase resonance frequency” may be identified by an eigenfrequency analysis to identify the first (i.e. lowest) resonant frequency originating from out-of-phase movement of the damper, or by some other form of analysis (e.g. applying a simulated force on the voice coil and looking at the frequency spectrum), as would be appreciated by the skilled person.

[0108] A skilled person would appreciate that the first antiphase resonant frequency of the first and second bridge portions may be influenced by various factors concerning the structure of the loudspeaker and damper, such as:

[0109] For example, a w / t<=1 .5 portion that is between 40% and 60% of the length of the bridge portion can help to achieve a first antiphase resonant frequency that falls in a range as defined above.

[0110] Other factors which can influence the help to achieve a first antiphase resonant frequency that falls in a range as defined above include: the material of the damper, the length of the bridge and the ratio w / t.

[0111] In a second aspect, the present invention may provide a precursor damper according to the first aspect of the invention. The precursor damper may thus include: an outer portion which defines an outer periphery of the precursor damper, and which includes first and second outer portion segments; an inner portion which defines an inner periphery of the precursor damper, and which includes first and second inner portion segments; at least one first bridge portion which connects the first outer portion segment to the first inner portion segment; at least one second bridge portion which connects the second outer portion segment to the second inner portion segment; wherein the first outer portion segment includes a first outer connection formation for forming an electrical connection between the first outer portion segment and an electrical signal source; wherein the second outer portion segment includes a second outer connection formation for forming an electrical connection between the second outer portion segment and the electrical signal source; wherein the first inner portion segment includes a first inner connection formation for forming an electrical connection between the first inner portion segment and (e.g. a voice coil of) the movable assembly; wherein the second inner portion segment includes a second inner connection formation for forming an electrical connection between the second inner portion segment and (e.g. a voice coil of) the movable assembly; wherein the first outer portion segment, first inner portion segment and first bridge portion provide a first part of the precursor damper; wherein the second outer portion segment, second inner portion segment and second bridge portion provide a second part of the precursor damper; wherein the first part and second part of the precursor damper are physically attached to each other by at least one severable feature.

[0112] Any feature described in connection with the precursor damper in relation to the first aspect of the invention may apply equally to the precursor damper of the second aspect of the invention.

[0113] Thus, for example, the precursor damper according to the first or second aspect of the invention may be formed from sheet metal.

[0114] In a third aspect, the present invention may provide an electromechanical transducer that includes: a static assembly and a movable assembly; a damper formed of metal, wherein the precursor damper includes: an outer portion which defines an outer periphery of the damper, and which includes first and second outer portion segments; an inner portion which defines an inner periphery of the damper, and which includes first and second inner portion segments; at least one first bridge portion which connects the first outer portion segment to the first inner portion segment; at least one second bridge portion which connects the second outer portion segment to the second inner portion segment; wherein the first outer portion segment includes a first outer connection formation for forming an electrical connection between the first outer portion segment and an electrical signal source; wherein the second outer portion segment includes a second outer connection formation for forming an electrical connection between the second outer portion segment and the electrical signal source; wherein the first inner portion segment includes a first inner connection formation for forming an electrical connection between the first inner portion segment and (e.g. a voice coil of) the movable assembly; wherein the second inner portion segment includes a second inner connection formation for forming an electrical connection between the second inner portion segment and (e.g. a voice coil of) the movable assembly; wherein the first outer portion segment, first inner portion segment and first bridge portion provide a first part of the damper; wherein the second outer portion segment, second inner portion segment and second bridge portion provide a second part of the damper; wherein the first outer portion segment is attached to the static assembly, the first inner portion segment is attached to the movable assembly, the second outer portion segment is attached to the static assembly, and the second inner portion segment is attached to the movable assembly; and wherein the first part and the second part of the damper are physically separated from each other by air.

[0115] The electromechanical transducer according to the third aspect of the invention may be produced according to the method of the first aspect of the invention, or may be produced by an alternative method (e.g. without using a precursor damper with one or more severable feature, and without severing any such features).

[0116] The electromechanical transducer according to the third aspect of the invention may have any feature as described in connection with any previous aspect of the invention, but without necessarily requiring the involvement of a precursor damper, any severable features or the severing of any such features.

[0117] For example, the electromechanical transducer may be a loudspeaker.

[0118] For example, where the electromechanical transducer is a loudspeaker, the damper of the loudspeaker may be configured so that the first antiphase resonant frequency of the first and second bridge portions is either: higher than 1 kHz, if the working frequency range of the loudspeaker extends above 1 kHz; at least 100 Hz above the working frequency range of the loudspeaker, if the working frequency range of the loudspeaker does not extend above 1 kHz For example, each bridge portion may include a (respective) torsion relief region, e.g. configured so as to relieve torsional stress on the bridge portion when the movable assembly moves relative to the static assembly along the movement axis.

[0119] Any feature described in connection with the electromechanical transducer (e.g. loudspeaker) in relation to the first aspect of the invention may apply equally to the electromechanical transducer (e.g. loudspeaker) of the third aspect of the invention.

[0120] The precursor damper according to the first or second aspect of the invention may be formed from sheet metal.

[0121] The invention includes the combination of the aspects and preferred features described except where such a combination is clearly impermissible or expressly avoided.

[0122] Summary of the Figures

[0123] Embodiments and experiments illustrating the principles of the invention will now be discussed with reference to the accompanying figures in which:

[0124] Figs. 1a-d show a loudspeaker produced according to a method as disclosed herein.

[0125] Figs. 2a-d show a precursor damper for use in a method as disclosed herein.

[0126] Fig. 3a shows the precursor damper of Figs. 2a-c.

[0127] Fig. 3b shows a damper formed from the precursor damper of Figs. 2a-c, for use in a method as disclosed herein.

[0128] Fig. 4 shows a method for use in producing a loudspeaker.

[0129] Fig. 5 shows a specific implementation of the method of Fig. 4, using the precursor damper of Figs. 2a-c.

[0130] Fig. 6 shows a first inner connection formation of the precursor damper of Figs. 2a-c.

[0131] Fig. 7 shows the forming a shaped piece of metal from a sheet of metal by progressive stamping.

[0132] Figs. 8a-8f are graphs comparing the performance of a damper made according to the present disclosure and a traditional damper.

[0133] Figs. 9a-b show various alternative bridge portions, which may be incorporated into a damper or precursor damper according to the present disclosure.

[0134] Fig. 10 shows an alternative example of a precursor damper.

[0135] Figs. 11a-b show an alternative example of a precursor damper and a damper formed therefrom.

[0136] Figs 12a-12b show an alternative example of a first inner connection formation.

[0137] Fig. 13a shows bending of a bridge portion vs bending plus twisting of the bridge portion.

[0138] Fig. 13b shows a bridge portion that includes a torsion relief region. Fig. 14 shows a simulation of a full range loudspeaker with out-of-phase movement of the damper.

[0139] Detailed Description of the Invention

[0140] Aspects and embodiments of the present invention will now be discussed with reference to the accompanying figures. Further aspects and embodiments will be apparent to those skilled in the art. All documents mentioned in this text are incorporated herein by reference.

[0141] Figs. 1a-d shows a loudspeaker 100 produced according to a method as disclosed herein, where Fig. 1a is a cross section along a movement axis 102, Fig. 1 b is an exploded view, Fig. 1 c is a profile view and Fig. 1d is a cut-away view.

[0142] The loudspeaker 100 includes a static assembly and a movable assembly. In this example, the static assembly includes a magnet unit 110 attached to a frame 120. In this example, the movable assembly includes a voice coil 170, a voice coil former 172 on which the voice coil 170 is mounted, a diaphragm 180 and a dust cap 190. In this example, the movable assembly is suspended from the static assembly by two suspensions: a roll suspension 182 and a damper 140. An outer periphery of the roll suspension 182 is attached to the frame 120 and an inner periphery of the roll suspension 182 is attached to an outer periphery of the diaphragm 180. In this example, an inner periphery of the diaphragm 180 is attached to the voice coil former 172 of the moveable assembly. In this example, an outer periphery of the damper 140 (provided by first and second outer portion segments, discussed later) is attached to the frame 120 and an inner periphery of the damper 140 (provided by first and second inner portion segments, discussed later) is attached to the voice coil 170 and / or voice coil former 172 of the movable assembly. Thus, the movable assembly is suspended from the static assembly by the damper 140 and the roll suspension 182.

[0143] In this example, the frame 120 does not form an acoustic enclosure due to large apertures in a sidewall of the frame. In other examples, the frame 120 may be more acoustically closed or be configured to function as a speaker enclosure.

[0144] In this example, the magnet unit 110 includes a yoke 112, a permanent magnet 114 and a washer 116. In this example, the yoke 112 is a T-yoke (in other examples, a U-yoke arrangement may be used). In this example, the annular permanent magnet 112 is shaped to fit over the yoke 112. The yoke 112, permanent magnet 114 and washer 116 are arranged to direct the magnetic field produced by permanent magnet 114 across a magnetic gap. In use, the voice coil 170 is positioned within the magnetic gap, so that when the voice coil 170 is energized, it produces a magnetic field which interacts with the magnetic field produced by the magnet unit 110 which causes the voice coil 170 (and therefore the diaphragm 180) to move relative to the magnet unit 110 along the movement axis 102. Here, the movement axis 102 is an axis passing through a centre of the magnet unit 110.

[0145] Note that the roll suspension 182 is depicted as being attached to the diaphragm 180 in Fig. 1 b, though these components may optionally be formed as separate components. The roll suspension 182 may have a curved profile when viewed in cross-section in a plane containing the movement axis 102. The dust cap 190 attached to the diaphragm 180 may help to prevent dust ingress into an air gap provided by the magnet unit 110 of the loudspeaker 100.

[0146] The voice coil 170 mounted on the voice coil former 172 may include: a first solder pad 174 configured to provide an electrical connection to a first inner connection formation 150a (discussed later); and a second solder pad 174 configured to provide an electrical connection to the second inner connection formation 150b (discussed later). In some examples the solder pads 174 are made of copper, but alternative materials could be used. In this example, the voice coil 170 includes wire wrapped around a cylindrical voice coil former 172 terminating in the solder pads 174, so that each solder pad can (respectively) be connected (through the damper 140) to a different polarity of an electrical source (as described below).

[0147] Fig. 2a-d shows a precursor damper 130 for use in a method as disclosed herein.

[0148] In this example, the precursor damper 130 is integrally formed as a single piece of metal and includes: an outer portion 139, and inner portion 137, one first bridge portion 136, two second bridge portions 136.

[0149] The outer portion 139 of the precursor damper 130 defines an outer periphery of the precursor damper 130 and includes a first outer portion segment 139a and a second outer portion segment 139b. The inner portion 137 of the precursor damper 130 defines an inner periphery of the precursor damper 130 and includes a first inner portion segment 137a and a second inner portion segment 137b. The first bridge portion 136a connects the first outer portion segment 139a to the first inner portion segment 137a. The second bridge portions 136b each connect the second outer portion segment 139b to the second inner portion segment 137b.

[0150] The first outer portion segment 139a includes a first electrical tag 132a, which serves as a first outer connection formation, for forming an electrical connection between the first outer portion segment 139a and an electrical signal source (not shown).

[0151] The second outer portion segment 139b includes a second electrical tag 132b, which serves as a second outer connection formation 132b, for forming an electrical connection between the second outer portion segment 139b and the electrical signal source (not shown).

[0152] In use, each electrical tag 132a-b may be connected to a different polarity of the electrical source. In examples described later (e.g. Fig. 11 a-b), more than two electrical tags 132a-b are present, in which case multiple electrical tags 132a-b may be connected to the same polarity of the electrical source. In an example, the first electrical tag 132a is connected to a first terminal (e.g. positive terminal) of the electrical source and the second electrical tag 132b is connected to a second terminal (e.g. negative terminal) of the electrical source.

[0153] The first inner portion segment includes a first rib 150a, which serves as a first inner connection formation, for forming an electrical connection between the first inner portion segment 137a and a voice coil 170 of the movable assembly. The second inner portion segment includes a second rib 150b, which serves as a second inner connection formation, for forming an electrical connection between the second inner portion segment 137b and a voice coil 170 of the movable assembly.

[0154] The first outer portion segment 139a, the first inner portion segment 137a and the first bridge portion 136a together provide a first part of the precursor damper 130.

[0155] The second outer portion segment 139b, the second inner portion segment 137b and second bridge portion 136b together provide a second part of the precursor damper 130.

[0156] In this example, the first part and second part of the precursor damper 130 are physically attached to each other by a plurality severable features 134a-b which include: two inner severable features 134a which physically attach the first inner portion segment 137a to the second inner portion segment 137b and two outer severable features 134b which physically attach the first outer portion segment 139a to the second outer portion segment 139b.

[0157] The first and second ribs 150a-b are discussed in more detail below, with reference to Fig. 6.

[0158] In this example, the first electrical tag 132a includes a first portion which extends along the movement axis 102 and a second portion, distal to the first portion, which extends outwardly away from the first outer portion segment 139a. In this example, the second electrical tag 132b includes a first portion which extends along the movement axis 102, and a second portion, distal to the first portion, which extends outwardly away from the second inner portion segment 139b. In some examples, the electrical tags 132a- b may be formed by bending parts of a shaped piece of metal which has been formed by stamping the shaped piece of metal out from a sheet of metal 30 (e.g. as discussed in Fig. 7, below). In this example, the first electrical tag 132a and the second electrical tag 132b each include an aperture suitable for accommodating a wire for forming an electrical connection with an electrical signal source (not shown). As can be seen in Figs. 1a-d, the first portion of each electrical tag 132a-b which extends along the movement axis 102 causes the second portions of the electrical tags 132a-b to sit in a plane perpendicular to the movement axis 102 which is different to a plane perpendicular to the movement axis 102 in which the inner and outer portion segments 137a-b, 139a-b of the damper sit. This may facilitate forming electrical connections with the electrical signal source. In this example, the first outer portion segment 139a and the second outer portion segment 139b are inset molded into the static assembly (not shown) which may be made from a resin or plastic, and the first and second electrical tags 132a-b respectively extends outwardly from the first and second outer portion segments 139a-b (best shown in Fig. 1d). Note, however, that the step of forming electrical connections with the electrical signal source (not shown) is usually performed by an end user, i.e. after the loudspeaker 100 has been produced. The electrical connection between the electrical signal source and electrical tags 132a-b may be formed for example using soldering, although other means of forming an electrical connection could be used.

[0159] In this example, the bridge portions 136a-b are flexible to permit relative movement between the static and moveable assemblies along the movement axis 102. The bridge portions 136 may take several different shapes according to the application requirements (discussed in greater detail later). In this example, the bridge portions 136a-b extend circumferentially (with respect to movement axis 102) between the outer and inner portions (e.g. in a spiral shape). Although formed of the same material as the rest of the damper 140, the bridge portions 136a-b may be flexible in part because of their shape (discussed in more detail later).

[0160] The number of inner portion segments 139a-b, outer portion segments 137a-b and bridge portions 136a-b may be chosen dependent on application requirements, although for the precursor damper 130 shown in Fig. 2 there is one first bridge 136a which connects a first inner portion segment 137a with a first outer portion segment 179a, and two second bridges portions 136b which connect the inner portion segment 137b and the outer portion segment 139b.

[0161] In general terms, connecting a rigid inner portion 137 and a rigid outer portion 139 by flexible bridge portions 136a-b is thought to be helpful from a design perspective, both from the perspective of achieving a desired frequency response and also because the bridge portions 136a-b are able to provide less resistance to airflow than a ‘solid’ damper (i.e. a damper without large apertures, or that is acoustically ‘closed’), meaning that less air is displaced as the damper 140 moves, which helps to reduce noise created by damper movement and total harmonic distortion (“THD”) when compared with a more traditional damper (see e.g. discussion of Figs. 8a-f, below). In this example, the inner portion 137 and the outer portion 139 are be considered rigid because they are thicker in a plane perpendicular to the movement axis 102 than the bridge portions 136a-b, and thus more rigid than the bridge portions 136a-b.

[0162] In this example, each bridge portion 136a-b of the damper 140 may include a portion 637, for which w / t<=1 .5 (best shown in Fig. 9b), where w is the width of the portion 637 as measured in a direction in a plane perpendicular to the movement axis 102 and where t is the thickness of the portion as measured in a direction parallel to the movement axis 102, wherein the portion 637 is between 40% and 60% of the length of the bridge portion 136a-b. In some examples the bridge portion 136a-b may bifurcate (See e.g. Fig. 9a), in which case a length of the bridge portion 136a-b can be considered to be the length of the bridge portion 136a-b along any path from the inner portion 137 to the outer portion 139. As such a bridge portion 136a-b may be considered to have more than one length.

[0163] Fig. 2b shows an inner severable feature 134a. In this example, the inner severable feature 134a includes a bent portion of metal formed integrally with the first and second parts of the precursor loudspeaker 104. In more detail, the inner severable feature 134a includes a first arm 162a, a second arm 162a’, and a basel 60a. The first arm 162a is joined to the first part of the precursor damper 130, the second arm 162a’ is joined to the second part of the precursor damper 130, and the first arm 162a and the second arm 162a’ are joined together by the base 160a. In this example, the inner severable feature 134a has a ‘U’ shape.

[0164] As shown in Fig. 2b, each arm 162a, 162a’ of the inner severable feature 134a includes a region of material that is thinner than the immediately adjacent portions of the first and second parts of the precursor damper 130 to which the inner severable feature 134a is physically attached as measured in a plane perpendicular to the movement axis 102. The thinner section of each arm 162a, 162a’ is therefore shaped to be severed (e.g. cut), according to a method described herein. As shown in Fig. 2b, a width 168a of each arm 162a, 162a’ as measured in a plane perpendicular to the movement axis is greater than 0.5mm but less than 2*T where T is a thickness of the damper as measured in a direction parallel to the movement axis. In this example, each arm 162a, 162a’ tapers from the base 160a towards the part of the damper 130 to which the arm 162a, 162a’ is joined. The width of the arms 162a, 162a’ preferably provides a balance between stability of the precursor damper 130 (which is improved with increasing width) and ease of severing the arms 162a, 162a’ (which is improved with decreasing width). In this example, the thickness of the damper T is 0.3mm but could for example be up to 1.2mm including 0.5mm, 0.8mm and 1.0mm.

[0165] The width 168a of each arm 162a, 162a’ is in this example 0.5mm. By having arms with a width less than 2*T it is made easier to cut the severable features with pliers, however other cutting techniques may be used (e.g. laser cutting) in which case the width of each arm could be thicker than 2*T without necessarily impeding the severing of the arms.

[0166] Fig. 2c shows an outer severable feature 134b. In this example, the outer severable feature 134b includes a bent portion of metal formed integrally with the first and second parts of the precursor loudspeaker 104. In more detail, the outer severable feature 134b includes a first arm 162b, a second arm 162b’, and a base 160b. The first arm 162b is joined to the first part of the precursor damper 130, the second arm 162b’ is joined to the second part of the precursor damper 130, and the first arm 162b and the second arm 162b’ are joined together by the base 160b. In this example, the outer severable feature 134b has a flattened ‘U’ shape.

[0167] As shown in Fig. 2c, each arm 162b, 162b’ of the outer severable feature 134b includes a region of material that is thinner than the immediately adjacent portions of the first and second parts of the precursor damper 130 to which the outer severable feature 134b is physically attached as measured in a plane perpendicular to the movement axis 102. This thinner section of each arm 162b, 162b’ is therefore shaped to be severed (e.g. cut) according to a method described herein.

[0168] As shown in Fig. 2c, a width 168b of each arm 162b. 162b’ as measured in a plane perpendicular to the movement axis is greater than 0.5mm but less than 2*T where T is a thickness of the damper as measured in a direction parallel to the movement axis. In this example, each arm 162b, 162b’ tapers from the base 160b towards the part of the damper 130 to which the arm 162b, 162b’ is joined. The width of the arms 162b, 162b’ preferably provides a balance between stability of the precursor damper 130 (which is improved with increasing width) and ease of severing the arms 162b, 162b’ (which is improved with decreasing width). In this example, the width 168a of each arm 162a, 162a’ is 0.5mm.

[0169] Preferably, the inner severable features 134a and outer severable features 134b are integrally formed with the remainder of the precursor damper 130, e.g. by stamping the precursor damper from a sheet of material having a uniform thickness (e.g. as described below with reference to Fig. 7).

[0170] The thickness T for the precursor damper shown in Fig. 2a is in this example 0.5mm, but could for example be between 0.3mm and 1 .2mm. Preferably, the thickness T is between 0.3 and 0.8mm. For both the inner and outer severable features 134a, 134b (although only illustrated for the first severable feature 134a of Fig. 2a), there is a gap 166 between the first and second arms that is greater than 2.5mm (as measured in a plane perpendicular to the movement axis). In some examples, when the damper 140 is formed by severing the severable features of precursor damper 130, both the first and second arms 152a-b of the severable features 134a-b are cut, leaving said gap between the first and second parts of the damper 140. This gap 166 (in this example a gap of greater than 2.5mm, should be adequately large to reduce the chance that the first and second parts of the damper 140 will come into contact, which may short-circuit an electrical signal source (not shown) rather than passing the electrical signal to / from the voice coil. The width of the gap 166 should be chosen based on the application requirements. In some examples, the gap 166 may be >=1.2*T.

[0171] Fig. 2d shows an inner severable portion 134a with first and second bridge portions 136a-b. In this example, the inner and outer severable features 134a, 134b are positioned at a distance 164 away from the bridge portions 136 of greater than 4.0mm.

[0172] Figs. 3a shows the precursor damper 130 of Figs. 2a-d.

[0173] Fig. 3b shows a damper 140 formed from the precursor damper 130 of Fig. 3a.

[0174] The damper 140 of Fig. 3b is formed by severing the severable features 134a-134b which physically attach the first part and the second part of the precursor damper 130 to each other so that the first part and the second part of the precursor damper 140 become physically separated from each other by air.

[0175] In this example, the first part of the damper 140 is depicted in white and the second part of the damper 140 is depicted in black for illustrative purposes only, to illustrate the separation of the first and second parts.

[0176] In this example, a small remnant of the severable features 134a-b is left behind on the first and second parts of the damper 140, such that the damper 140 can be identified as being produced from the precursor loudspeaker 130. However, it would also be possible to sever the severable features 134a-b without leaving such a remnant behind. Moreover, in some examples (not illustrated), it would also be possible to form the first and second parts of damper 140 as two separate parts (which are never attached to each other by severable features), thereby avoiding the need for a severing step to form the damper 140.

[0177] The precursor damper 130 may be designed based on requirements according to the system in which the precursor damper 130 is to be installed. This preliminary damper shape may then be adjusted based on simulated or measured vibration characteristics calculated based on this preliminary damper shape (once severed). Such simulations may be performed using software (e.g. Comsol) or mathematics (e.g. eigenfrequency analysis), as known to persons skilled in the art.

[0178] Fig. 4 shows a method for use in producing a loudspeaker 100 according to a first aspect of the present invention.

[0179] The method includes: providing a precursor loudspeaker 104 and a precursor damper 130 (S100); installing the precursor damper 130 in the precursor loudspeaker 104 (S108); then forming a damper 140 from the precursor damper 130 by severing at least one severable feature 134a-b of the precursor damper (S110); then optionally producing a loudspeaker 100 from the precursor loudspeaker 104 (S112).

[0180] The method of Fig. 4 may use the precursor damper 130 of Figs. 2a-c. The precursor loudspeaker 104 is described below in relation to Fig. 5. In this case, the step of installing the precursor damper 130 in the precursor loudspeaker 104 may include: installing the precursor damper 130 in the precursor loudspeaker 104 (S108) so that the first outer portion segment 139a is attached to the static assembly, the first inner portion segment 137a is attached to the movable assembly, the second outer portion segment 139b is attached to the static assembly, and the second inner portion segment 137b is attached to the movable assembly. Then the step of forming the damper 140 from the precursor damper 130 may include severing all of the severable features 134a-b so that the first part and the second part of the damper are physically separated from each other by air (S110).

[0181] In some examples, the method includes forming the electrical connection between the first outer portion segment 139a and an electrical signal source (not shown) via the first electrical tag 132a; and forming the electrical connection between the second outer portion segment 139b and the electrical signal source (not shown) via the second electrical tag 132b. This may be done by soldering or other means. In the example damper shown in Figs 2a-d, the first electrical tag 132a and second electrical tag 132b are provided with apertures through which wires may be passed. In some examples, forming the electrical connection between the first outer portion segment 139a and electrical signal source (not shown) involves passing wires through the apertures in the first electrical tag 132a, and optionally securing the wires by soldering. In some examples, forming the electrical connection between the second outer portion segment 139b and electrical signal source (not shown) involves passing wires through the apertures in the second electrical tag 132b, and optionally securing the wires of an electrical signal source (not shown) by soldering. Fig. 5 shows a specific implementation of the method of Fig. 4, using the precursor damper 130 of Figs. 2a-c.

[0182] Prior to step S202, a washer 116 and frame 120 are provided.

[0183] In step S202, the washer 116 is attached to the frame 120. In this example the washer is riveted to the frame using the nodules formed on a surface of the washer, though other methods of attachment are of course possible. For example, in other examples the washer could instead be attached to the frame by adhesive, a combination of adhesive and rivets.

[0184] In step S204, the magnet unit 110 is formed by attaching the permanent magnet 114 and the T yoke to the washer 116.

[0185] In step S206, the voice coil former 172 (to which the voice coil 170 is already mounted) is inserted into the magnet unit 110 so as to form a precursor loudspeaker 104 that includes the frame 120, magnet unit 110, voice coil former 172 and voice coil 170. Here, the frame 120 and magnet unit form 110 the static assembly of the precursor loudspeaker 104 and the voice coil former 172 and voice coil 170 form the movable assembly of the precursor loudspeaker 104.

[0186] At the point, a precursor damper 130 as described above (not shown until the subsequent step) is also provided, corresponding to step S100 in Fig. 4.

[0187] In step S208, corresponding to step S108 in Fig. 4, the precursor damper 130 is installed in the precursor loudspeaker 104. In this example, this installation step includes attaching the first outer segment portion 139a and second outer segment portion 139b of the precursor damper 130 to the frame, and soldering each of the first and second inner connection formations 150 to a respective solder pad 174 of the voice coil 172, thereby electrically connecting the first and second inner connection formations 150a-b to the voice coil 170 and physically attaching the first and second inner connection formations 150a-b to the voice coil 170 (and voice coil former 172). In step S210, corresponding to step S110 in Fig. 4, forming the damper 140 from the precursor damper 130 includes severing the severable features 134a-bof the precursor damper (S110). In this example, severing the severable features 134a-b includes cutting each first and second arm 152a-b to leave an air gap between the first and second parts of the damper 140.

[0188] In step S212, corresponding to step S112 in Fig. 4, the loudspeaker 100 is produced from the precursor loudspeaker 104 by installing the diaphragm 180, roll suspension 182 and dustcap 190 (which in this example are attached to each other prior to installation) in the precursor loudspeaker 104, by attaching an outer periphery of the roll suspension 182 to the frame 120, and attaching an inner periphery of the diaphragm 180 to the voice coil former 170.

[0189] Fig. 6 shows a first inner connection formation 150a used in a method of the present invention.

[0190] In this example, the first inner connection formation 150a includes a first rib 152 which extends inwardly towards the voice coil 170 of the movable assembly when the precursor damper 130 is installed in the precursor loudspeaker 104.

[0191] In this example, the first rib 152 includes a first portion which extends inwardly towards (e.g. a voice coil 170 of) the movable assembly when the precursor damper 130 is installed in the precursor loudspeaker 104, and a second portion, distal from the first portion, which extends along the movement axis 102 when the precursor damper 130 is installed in the precursor loudspeaker 104. The first rib 152 may be formed by bending part of a shaped piece of metal which has been formed by stamping the shaped piece of metal out from a sheet of metal 30 (e.g. as discussed in Fig. 7, below). In this example, the second portion of the first rib 152 is configured to form a connection with a first solder pad 174 of the voice coil 170 respectively, which may for example be formed from copper.

[0192] In this example, the first inner connection formation 150a is shaped to form a respective gap 156 between the first inner connection formation 156a and the voice coil 170 of the moveable assembly on each side of the first rib 152 when the precursor damper 130 is installed in the precursor loudspeaker 104. In this example the first inner connection formation 150a includes a respective hole 154 on each side of the first rib 152. In this example the respective holes 154 are proximal to the rib 152. In this example the remaining portions of the first connection formation 150a are shaped to abut the voice coil former 172. As shown in Fig. 5 where respective gaps 156 are also included in the first inner connection formation 150a, each of the respective holes 154 may be formed on the outside of the respective gaps 156. Forming the electrical connection between the first inner portion segment 137a and the movable assembly via the first inner connection formation 150a may include soldering the first rib 152 to the first solder pad 174 of the voice coil so as to provide a physical attachment between the first inner portion segment 137a and the movable assembly. The gaps 156 may help to allow liquid solder to contact a greater area of the solder pad 174 and / or voice coil former 172 of the movable assembly, thereby providing stronger and more robust physical attachment between the precursor damper 130 (and subsequently, the damper 140) and the movable assembly. The holes 154 can be useful to inhibit heat diffusion into the first inner portion segment 137a when the first rib 152 is soldered to the first solder pad 174 (which is defined herein as being part of the voice coil 170).The second inner connection formation 150b may be formed similarly to the first inner connection formation 150a, and attached to a second solder pad on the voice coil former 172, though this is not shown in Fig. 6.

[0193] Fig. 7 shows the forming a shaped piece of metal 30’ from a sheet of metal 30 by progressive stamping. The sheet of metal 30 may be one of, for example, stainless steel (e.g. SUS304 series, SUS301 series, SUS316 series, 17-7PH etc.), cobalt-based alloys (e.g. 3J21), nickel-based alloys (e.g. Elgiloy 3J22), copper alloys (e.g. Be-CU, Phosphorous Cu).

[0194] The progressive stamping illustrated by Fig. 7 may involve using the same tool to perform multiple stamping steps sequentially as the sheet of metal 30 is moved along an assembly line so that the different stamping steps are performed sequentially to different products at different times by the same tool, which helps improve efficiency. However, while progressive stamping is seen as an efficient and cost effective method of producing a precursor damper 130, other methods of producing the precursor damper 130 are envisioned (for example waterjet cutting, or casting the precursor damper 130).

[0195] The shaped piece of metal 30’ resulting from the progressive stamping process illustrated in Fig. 7 can subsequently be formed into the precursor damper 130 by suitable bending of certain parts of the shaped piece of metal 30’, e.g. so as to form electrical tags 132a-b and ribs 152 as described previously.

[0196] In other examples (not shown), the precursor damper 130 could, for example, be made from a flexible PCB (printed circuit board) or an electroplated plastic, whereby electrical connections between the first outer connection formation and the first inner connection formation, and between the second outer connection formation and the second inner connection formation are provided by electrical tracks formed on the precursor damper. The plastic may be, for example, a polyamide (“PA”, e.g. PA-GF10), polyether ether ketone (“PEEK”) or polypropylene (“PP”).

[0197] Figs. 8a - 8f are graphs comparing the performance of the damper 140 of Figs 1a-d and a traditional damper.

[0198] Several aspects of the design of the damper 140 can be changed, which themselves result in a different response from the damper 140 (and any loudspeaker 100 incorporating such a damper 140). As a skilled person would appreciate, the damper 140 of Figs 1a-d can deform, and therefore vibrate in use. When driven at certain frequencies, the moveable assembly of a loudspeaker 100 incorporating the damper 140 will vibrate out of phase with the damper 140, for example the bridge may deform into the shape of a since curve at these frequencies. At the first antiphase resonant frequency (e.g. as illustrated in Fig. 14) the loudspeaker 100 may produce sound at an abnormally low volume. This effect is particularly pronounced at medium and low frequencies, and therefore during the design of the damper 140 it is preferable to ensure that the first antiphase resonance frequency of the loudspeaker 100 is high (e.g. greater than 1000hz) or merely above the standard operating range of the loudspeaker 100. The inventors have found that improved frequency response is improved in loudspeakers 100 with a working rage below 200Hz (“Woofers”) the first antiphase resonance frequency should be greater than 400Hz. For loudspeakers 100 with a working range below 300 Hz the first anti-phase resonance frequency should be greater than 500Hz. For full, mid-range and high-frequency (“Tweeter”) loudspeakers the first anti-phase resonance frequency should be above 1000Hz. Typically, loudspeakers also have in-phase resonant frequencies resulting from pistonic (in-phase) movement of the damper 140 which can be low or within the working range of the loudspeaker 100.

[0199] In some cases, for example in low-frequency speakers, it may be difficult (and expensive) to modify a large damper 140 to increase the first anti-phase resonance of the loudspeaker 100 to be greater than 1000Hz. However, advantageously similar performance is achieved when the first anti-phase resonance frequency is sufficiently above the working range of the loudspeaker 100.

[0200] The first antiphase resonating frequency of the loudspeaker 100 may be determined by simulating the moving parts of the loudspeaker (e.g. using software such as “Comsol”). In the examples simulated in Fig. 9a the moving parts simulated are the diaphragm 180, roll suspension 182, damper 140 voice coil 170 and voice coil former 172 and dustcap 190. The portions of the roll suspension 182 and damper 140 attached to the static assembly are fixed in the simulation. Alternatively, or in addition to simulation, the first resonant frequency originating from out-of-phase movement of the damper 140 may be identified by eigenfrequency analysis or by an alternative analysis or mathematical method.

[0201] The mass and stiffness of the damper can be modified to affect the first anti-phase frequency of the damper. The maximum displacement of the damper 140 may also be modified to affect the first antiphase frequency.

[0202] In this example, while designing a damper the Von Mises stress of the damper has been kept less than 1200MPa to improve the lifetime of the damper.

[0203] Fig. 8a shows the sound pressure level (“SPL”) of the loudspeaker 100 of Figs 1a-d, which includes a damper 140 configured to have a first antiphase frequency (resulting from 1stantiphase resonance) that occurs above 1 kHz compared to the sound pressure level of a loudspeaker having a traditional damper.

[0204] Fig. 8b shows the SPL of the loudspeaker 100 of Figs 1a-d, which includes a damper 140 configured to have a first antiphase frequency (resulting from 1stantiphase resonance) that occurs below 1 kHz (~850Hz) compared to the sound pressure level of a loudspeaker having a traditional damper. Fig. 8c shows the THD of the loudspeaker 100 of Figs 1 a-d, which includes a damper 140 configured to have having a first antiphase frequency (resulting from 1stantiphase resonance) that occurs above 1 kHz compared to the sound pressure level of a loudspeaker having a traditional damper.

[0205] Fig. 8d shows the THD of the loudspeaker 100 of Figs 1 a-d, which includes a damper 140 configured to have a first antiphase frequency (resulting from 1stantiphase resonance) that occurs below 1 kHz (~850Hz) compared to the sound pressure level of a loudspeaker having a traditional damper.

[0206] As can be seen in the figures, significant attenuation in the SPL and THD occur between the damper 140 and a traditional damper when the first anti-phase resonance frequency of the damper 140 is low (i.e less than 1000Hz) but not when the first anti-phase resonance frequency of the damper 140 is high (i.e. greater than 1000Hz).

[0207] Fig. 8e shows the SPL of an 8-inch woofer using a damper 140 configured to have a first anti-phase resonance frequency of 780Hz (significantly above the working frequency of the woofer) compared to the SPL of an 8-inch woofer using a traditional damper. As can be seen, there is very little attenuation in SPL over the working frequencies of the woofer between the woofer using a damper 140 of the present invention compared to the distortion of the woofer using a traditional damper.

[0208] Fig. 8f shows the THD of an 8-inch woofer using a damper 140 configured to have a first anti-phase resonance frequency of 780Hz (significantly above the working frequency of the woofer) compared to the distortion of an 8-inch woofer using a traditional damper. In this example, the first anti-phase resonance frequency of the damper 140 is 780Hz (significantly above the working frequency of the woofer). As can be seen, there is very little increase in THD over the working frequencies of the woofer between the woofer using a damper 140 of the present invention compared to the distortion of the woofer using a traditional damper.

[0209] Figs. 9a-b show various alternative bridge portions 536a-c, which may be incorporated into a damper or precursor damper according to the present disclosure.

[0210] The bridge portions 136a-b previously discussed can have different shapes depending on the application requirements, and some alternative forms are shown in Figs. 9a-b.

[0211] In the first example shown in Fig. 9a, the bridge portion 536a follows a labyrinthine path and bifurcates to meet an inner portion segment 137a-b at two points, and an outer portion segment 139a-b at one point.

[0212] In the second example shown in Fig. 9a, the bridge portion 536b connects an inner portion segment 137a-b at a point, and an outer portion segment 139a-b at a point. The bridge portion 536b follows a corrugated path to add length to the bridge portion 536b.

[0213] In the third example shown in Fig. 9a, the bridge portion 536c bifurcates to meet at an outer portion segment 139a-b at two points, and the inner portion segment 137a-b at one point.

[0214] The various bridge portion shapes may be identified and refined by simulation as discussed previously.

[0215] Fig. 9b shows another bridge portion 636 whose width (as measured in a plane perpendicular to the movement axis) varies along its length. This bridge portion 636 also has a w / t<=1 .5 region, where w is the width of the bridge portion 636 as measured in a direction in a plane perpendicular to the movement axis 102 and where t is the thickness of the bridge portion as measured in a direction parallel to the movement axis, wherein the w / t<=1.5 region is between 40% and 60% of the length of the bridge portion. In this example, outside of the w / t<=1 .5 region, the bridge portion 636 does not have w / t <=1 .5. The present inventors have found that having the w / t<=1 .5 region can be helpful in achieving a desirable frequency response for the loudspeaker (associated with the “first antiphase resonance frequency” - see previous discussion).

[0216] Fig. 10 shows an alternative example of a precursor damper 230. In this example, there are three bridge portions 236a connecting the first inner portion segment 237a and the first outer portion segment 239b. In this example, there are two bridge portions 236b connecting the second inner portion segment 237b and the second outer portion segment 239b. Varying numbers of bridge portions 236a-b may be used provided there is at least one bridge portion 236a connecting the first inner portion segment 237a and the first outer portion segment 239a, and at least one bridge portion 236b connecting the second inner portion segment 237b and the second outer portion segment 239b.

[0217] Figs. 11 a-b show an alternative embodiment of a precursor damper 330 and a damper 340 formed therefrom.

[0218] In this example, the precursor damper 330 includes all of the features of damper 330 (with alike features given alike reference numerals) as well as third and fourth parts. The third part of the precursor damper 330 includes a third outer portion segment 339c of the outer portion 339 of the precursor damper 330, a third inner portion segment 337c of the inner portion 337 of the precursor damper 330 and at least one third bridge portion 336c which connects the third outer portion segment 339c to the third inner portion segment 337c. The third outer portion segment 339c includes a third electrical tag 332c for forming an electrical connection between the third outer portion segment 339c and an electrical signal source (not shown). The third inner portion segment 339a includes a third inner connection formation 350c for forming an electrical connection between the third inner portion segment 337c and (e.g. a voice coil 170 of) the movable assembly. The fourth part of the precursor damper 330 includes a fourth outer portion segment 339d of the outer portion 339 of the precursor damper 330, a fourth inner portion segment 337d of the inner portion 337 of the precursor damper 330, and at least one fourth bridge portion 336d which connects the fourth outer portion segment 339d to the fourth inner portion segment 337d. The fourth outer portion segment 339d includes a fourth electrical tag 332d for forming an electrical connection between the fourth outer portion segment 339d and the electrical signal source. The fourth inner portion segment 337d includes a fourth inner connection formation 350d for forming an electrical connection between the fourth inner portion segment 337d and (e.g. a voice coil 170 of) the movable assembly. The first part, second part, third part and fourth part of the precursor damper 330 are physically attached to each other by a plurality of severable features similar to those discussed previously (not labelled). In this example, the voice coil (not shown) may have first, second, third and fourth solder pads configured to provide an electrical connection to the first, second, third and fourth inner connection formations respectively. The electrical tags 332a-d are for attaching to different polarities of the electrical signal source. In this example, the first electrical tag 332a and the third electrical tag 332c are for connecting to a first terminal (e.g. positive terminal) of the electrical signal source and the second electrical tag 332b and the fourth electrical 332d tag are connected to a second terminal (e.g. negative terminal) of the electrical source.

[0219] Figs 12a-b show an alternative example of a first inner connection formation. In the example of Figs. 12a- b, the first inner connection formation 450a includes a rib 450awhich extends inwardly towards the voice coil former 472, but which unlike the examples discussed previously, does not have a portion which extends along the movement axis 102. In use, the rib 452 may be soldered (by solder 458) to a solder pad of the voice coil located on the voice coil former 472 so as to provide both an electrical connection to the voice coil and a physical attachment to the movable assembly. Fig. 13a shows (i) bending of a bridge portion vs (ii) bending plus twisting of the bridge portion.

[0220] The present inventors believe that, ideally, the bridge portions according to the present disclosure would bend as shown in Fig. 13a(i) rather than bend and twist as shown in Fig. 13a(ii), to maximise the longevity of the bridge portions. However, in practice, the present inventors have found that a damper 140 as shown in Figs. 1a-d does in practice twist, as well as bend as shown in Fig. 13a(ii) . This can cause the bridge portions to break more easily / quickly than is ideal.

[0221] Fig. 13b shows a bridge portion 736 that includes a torsion relief region 738.

[0222] The torsion accommodation region 738 of the bridge portion 736 may, as the bridge portion 736 extends from an outer portion segment 739 to an inner portion segment 737, trace a path which initially extends inwardly towards the movement axis 702, then outwardly away from the movement axis 702. In this example, the torsion relief region 738 is ‘U’ shaped, when viewed in a plane perpendicular to the movement axis 702. In this example, the torsion relief region 738 is joined to the outer portion segment 739, and joined to a circumferentially extending region 738’ of the bridge portion 736, wherein the torsion relief region 738 is located between the outer portion segment 739 and the circumferentially extending region 738’. In this example, the circumferentially extending region of the bridge portion extends circumferentially with respect to the movement axis 702, is joined to the inner portion segment 737, and is located between the torsion relief region 738 and the inner portion segment 737.

[0223] The torsion relief region 738 has been found to help to reduce twisting of / torsional stress on the bridge portion 736 when a damper incorporating the torsion relief region 738 is in use by deforming with the circumferentially extending region 738’, thereby reducing the internal stress of the circumferentially extending region 738’. This movement helps to reduce the internal stress of the extending region 738’, which helps to extend the longevity of the bridge portion 736, and therefore a damper (and loudspeaker) incorporating the bridge portion 736.

[0224] Fig. 14 shows a simulation of a full range loudspeaker with out-of-phase movement of the damper.

[0225] In this simulation, the antiphase movement of the bridge portions 836a, 836b of a damper 840 at the first antiphase resonance frequency, i.e. the lowest resonance originating from out-of-phase movement of the damper, is shown in exaggerated form. The features disclosed in the foregoing description, or in the following claims, or in the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for obtaining the disclosed results, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

[0226] While the invention has been described in conjunction with the exemplary embodiments described above, many equivalent modifications and variations will be apparent to those skilled in the art when given this disclosure. Accordingly, the exemplary embodiments of the invention set forth above are considered to be illustrative and not limiting. Various changes to the described embodiments may be made without departing from the spirit and scope of the invention.

[0227] For the avoidance of any doubt, any theoretical explanations provided herein are provided for the purposes of improving the understanding of a reader. The inventors do not wish to be bound by any of these theoretical explanations.

[0228] Any section headings used herein are for organizational purposes only and are not to be construed as limiting the subject matter described.

[0229] Throughout this specification, including the claims which follow, unless the context requires otherwise, the word “comprise” and “include”, and variations such as “comprises”, “comprising”, and “including” will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

[0230] It must be noted that, as used in the specification and the appended claims, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Ranges may be expressed herein as from “about” one particular value, and / or to “about” another particular value. When such a range is expressed, another embodiment includes from the one particular value and / or to the other particular value. Similarly, when values are expressed as approximations, by the use of the antecedent “about,” it will be understood that the particular value forms another embodiment. The term “about” in relation to a numerical value is optional and means for example + / - 10%.

[0231] References

[0232] A number of publications are cited above in order to more fully describe and disclose the invention and the state of the art to which the invention pertains. The entirety of each of these references is incorporated herein.

Claims

1. Claims:1 . A method for use in producing an electromechanical transducer, the method including: providing a precursor electromechanical transducer and a precursor damper; wherein the precursor electromechanical transducer includes a static assembly and a movable assembly; wherein the precursor damper includes: an outer portion which defines an outer periphery of the precursor damper, and which includes first and second outer portion segments; an inner portion which defines an inner periphery of the precursor damper, and which includes first and second inner portion segments; at least one first bridge portion which connects the first outer portion segment to the first inner portion segment; at least one second bridge portion which connects the second outer portion segment to the second inner portion segment; wherein the first outer portion segment includes a first outer connection formation for forming an electrical connection between the first outer portion segment and an electrical signal source; wherein the second outer portion segment includes a second outer connection formation for forming an electrical connection between the second outer portion segment and the electrical signal source; wherein the first inner portion segment includes a first inner connection formation for forming an electrical connection between the first inner portion segment and the movable assembly; wherein the second inner portion segment includes a second inner connection formation for forming an electrical connection between the second inner portion segment and the movable assembly; wherein the first outer portion segment, first inner portion segment and first bridge portion provide a first part of the precursor damper; wherein the second outer portion segment, second inner portion segment and second bridge portion provide a second part of the precursor damper; wherein the first part and second part of the precursor damper are physically attached to each other by at least one severable feature; installing the precursor damper in the precursor electromechanical transducer so that the first outer portion segment is attached to the static assembly, the first inner portion segment is attached to the movable assembly, the second outer portion segment is attached to the static assembly, and the second inner portion segment is attached to the movable assembly; then forming a damper from the precursor damper by severing the at least one severable feature which physically attaches the first part and the second part of the precursor damper to each other so that the first part and the second part of the damper are physically separated from each other by air.

2. The method of claim 1 , wherein the precursor damper is integrally formed as a single piece of metal.

3. The method of claim 1 or 2, wherein the / each severable feature includes a bent portion of material formed integrally with the first and second parts of the precursor electromechanical transducer.

4. The method of any previous claim, wherein the at least one severable feature includes: at least one outer severable feature which physically attaches the first outer portion segment to the second outer portion segment; at least one inner severable feature which physically attaches the first inner portion segment to the second inner portion segment5. The method of any previous claim, wherein severing the at least one severable feature includes cutting the at least one severable feature6. The method of any previous claim, wherein the / each severable feature includes a region of material that is thinner than the immediately adjacent portions of the first and second parts of the precursor damper to which the severable feature is physically attached.

7. The method of any previous claim, wherein the first and second parts of the damper have a thickness T as measured in a direction parallel to a movement axis, and the / each severable feature has a width as measured in a plane perpendicular to the movement axis that is between 0.5mm and 2*T8. The method of any previous claim, further including: forming the electrical connection between the first inner portion segment and the movable assembly via the first inner connection formation, wherein forming the electrical connection between the first inner portion segment and the movable assembly via the first inner connection formation optionally includes soldering the first inner connection formation to the voice coil so as to provide a physical attachment between the first inner portion segment and the movable assembly; and forming the electrical connection between the second inner portion segment and the movable assembly via the second inner connection formation, wherein forming the electrical connection between the second inner portion segment and the movable assembly via the second inner connection formation optionally includes soldering the second inner connection formation to the voice coil so as to provide a physical attachment between the second inner portion segment and the movable assembly9. The method of any previous claim, wherein the first inner connection formation includes a first rib which extends inwardly towards the movable assembly when the precursor damper is installed in the precursor electromechanical transducer; and the second inner connection formation includes a second rib which extends inwardly towards the movable assembly when the precursor damper is installed in the precursor electromechanical transducer.

10. The method of claim 9, wherein the first rib includes a first portion which extends inwardly towards the movable assembly when the precursor damper is installed in the precursor electromechanicaltransducer, and a second portion, distal from the first portion, which extends along a movement axis when the precursor damper is installed in the precursor electromechanical transducer; and the second rib includes a first portion which extends inwardly towards the movable assembly when the precursor damper is installed in the precursor electromechanical transducer, and a second portion, distal from the first portion, which extends along the movement axis when the precursor damper is installed in the precursor electromechanical transducer.

11. The method of claim 9 or 10, wherein the first inner connection formation is shaped to form a respective gap between the first inner connection formation and the movable assembly on each side of the first rib when the precursor damper is installed in the precursor electromechanical transducer; and the second inner connection formation is shaped to form a respective gap between the second inner connection formation and the movable assembly on each side of the second rib when the precursor damper is installed in the precursor electromechanical transducer.

12. The method of any of claims 9 to 11 , wherein: the first inner connection formation includes a respective hole on each side of the first rib; and the second inner connection formation includes a respective hole on each side of the second rib13. The method of any previous claim, wherein the first outer connection formation is a first electrical tag integrally formed with the first outer portion segment, and the second outer connection formation is a second electrical tag integrally formed with the second outer portion segment14. The method of any previous claim, wherein the electromechanical transducer is a loudspeaker.

15. The method of claim 14, wherein the damper is configured so that, after forming the damper from the precursor damper, the first antiphase resonant frequency of the first and second bridge portions is either: higher than 1 kHz, if the working frequency range of the loudspeaker extends above 1 kHz; at least 100 Hz above the working frequency range of the loudspeaker, if the working frequency range of the loudspeaker does not extend above 1 kHz.

16. The method of any previous claim, wherein each bridge portion of the damper includes a w / t<=1 .5 region, where w is the width of the bridge portion as measured in a direction in a plane perpendicular to the movement axis and where t is the thickness of the bridge portion as measured in a direction parallel to the movement axis, wherein the w / t<=1 .5 bridge region has a length that is between 40% and 60% of the length of the bridge portion. In some examples, outside of the w / t<=1 .5 region, the bridge portion 636 might not have w / t <=1 .5.

17. A precursor damper that includes: an outer portion which defines an outer periphery of the precursor damper, and which includes first and second outer portion segments; an inner portion which defines an inner periphery of the precursor damper, and which includes first and second inner portion segments; at least one first bridge portion which connects the first outer portion segment to the first inner portion segment; at least one second bridge portion which connects the second outer portion segment to the second inner portion segment; wherein the first outer portion segment includes a first outer connection formation for forming an electrical connection between the first outer portion segment and an electrical signal source; wherein the second outer portion segment includes a second outer connection formation for forming an electrical connection between the second outer portion segment and the electrical signal source; wherein the first inner portion segment includes a first inner connection formation for forming an electrical connection between the first inner portion segment and (e.g. a voice coil of) the movable assembly; wherein the second inner portion segment includes a second inner connection formation for forming an electrical connection between the second inner portion segment and (e.g. a voice coil of) the movable assembly; wherein the first outer portion segment, first inner portion segment and first bridge portion provide a first part of the precursor damper; wherein the second outer portion segment, second inner portion segment and second bridge portion provide a second part of the precursor damper; wherein the first part and second part of the precursor damper are physically attached to each other by at least one severable feature.

18. An electromechanical transducer that includes: a static assembly and a movable assembly; a damper formed of metal, wherein the precursor damper includes: an outer portion which defines an outer periphery of the damper, and which includes first and second outer portion segments; an inner portion which defines an inner periphery of the damper, and which includes first and second inner portion segments; at least one first bridge portion which connects the first outer portion segment to the first inner portion segment; at least one second bridge portion which connects the second outer portion segment to the second inner portion segment; wherein the first outer portion segment includes a first outer connection formation for forming an electrical connection between the first outer portion segment and an electrical signal source;wherein the second outer portion segment includes a second outer connection formation for forming an electrical connection between the second outer portion segment and the electrical signal source; wherein the first inner portion segment includes a first inner connection formation for forming an electrical connection between the first inner portion segment and (e.g. a voice coil of) the movable assembly; wherein the second inner portion segment includes a second inner connection formation for forming an electrical connection between the second inner portion segment and (e.g. a voice coil of) the movable assembly; wherein the first outer portion segment, first inner portion segment and first bridge portion provide a first part of the damper; wherein the second outer portion segment, second inner portion segment and second bridge portion provide a second part of the damper; wherein the first outer portion segment is attached to the static assembly, the first inner portion segment is attached to the movable assembly, the second outer portion segment is attached to the static assembly, and the second inner portion segment is attached to the movable assembly; and wherein the first part and the second part of the damper are physically separated from each other by air

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