Loudspeaker and loudspeaker method

Abstract

The loudspeaker (1) comprises a fixed structure including a magnetic field generator (201), a mobile working unit including a radiator (301) movable along a longitudinal axis (L) and a movable magnetic element (302) connected to the radiator (301) and movable under the action of a magnetic field to form a transducer, and a guide device (10) configured to guide the reciprocating longitudinal movement of the mobile working unit. The guide device (10) includes an inner surface (202A) extending around a longitudinally oriented guide shaft (G), an outer surface (303B) extending around the guide shaft (G) and surrounding the inner surface (202A) to define a gap, and a spring (M) closing on itself to form a ring, the spring (M) being disposed in the gap in contact with the inner surface (202A) and the outer surface (303B) and rolling thereon while moving longitudinally in response to relative movement between the inner surface (202A) and the outer surface (303B), wherein the inner surface (202A) is connected to a fixed structure and the outer surface (303B) is connected to a mobile working unit, or the inner surface (202A) is connected to a mobile working unit and the outer surface (303B) is connected to a fixed structure.

Description

[Technical Field]

[0001] The present invention relates to a loudspeaker and a method for amplifying sound. [Background technology]

[0002] Generally speaking, a loudspeaker comprises an electromechanical conversion system that converts a variable electrical signal into a mechanical movement of a radiator to generate sound waves, such conversion system having a magnetic element integrated with the fixed part of the sound diffuser and a magnetic element connected to the radiator for moving it, in particular the movable magnetic element moving under the action of a magnetic field generated by the integrated magnetic element.

[0003] In this context, there are two types of electromechanical transduction systems. In the more common systems known as "moving coil" systems, the integrated magnetic element is a permanent magnet and the moving magnetic element is a coil. The coil is excited by the electrical signal to be transduced and moves in response to interaction with the magnetic field generated by the permanent magnet. An example of a moving coil system is described in patent document US 5,014,323 A. Alternatively, in systems known as "moving magnet", the integrated magnetic element is a fixed coil and the moving magnetic element is a magnet. The fixed coil is excited by an electrical signal and the moving magnet moves in response to the magnetic field generated by the coil. An example of a moving magnet system is described in patent document EP 2,550,724 in the name of the same applicant.

[0004] Loudspeakers may be equipped with a centering system between components that move relative to one another. The centering system must ensure that the relative movement between the components is as precise and frictionless as possible. This lack of friction is important to prevent unwanted noise and reduce wear on the components.

[0005] US Pat. No. 5,014,323 A describes a moving coil system with a centering system called a spider, but such centering systems tend to break down easily and require frequent repairs.

[0006] The moving magnet system described in EP2550724 discloses a centering system equipped with ball bearings. The ball bearings also function as sliding guides between the moving and fixed parts of the loudspeaker. However, this type of guide has the disadvantage of being very noisy due to the effects of inactive ball recirculation. Furthermore, such guides have high inertia and are prone to wear due to friction caused by frequent changes in direction and high acceleration. Patent documents US2022030351A1, US2021044902A1, and JPH04255197A describe various examples of loudspeakers, but none of them fully meet market needs. Summary of the Invention

[0007] SUMMARY OF THE INVENTION It is an object of the present invention to provide a loudspeaker and method for amplifying sound that overcomes the above-mentioned drawbacks of the prior art.

[0008] In particular, the present invention aims to provide a sound diffuser that allows accurate centering of parts moving relative to each other, ensuring that their relative movement is as quiet and reliable as possible.

[0009] These objects are fully achieved by the loudspeaker and loudspeaker method of the present disclosure, as characterized in the appended claims.

[0010] In particular, the loudspeaker comprises a fixed structure including a magnetic field generator, the loudspeaker comprises a mobile working unit including a radiator movable along a longitudinal axis and a mobile magnetic element connected to the radiator.

[0011] The movable magnetic element is movable under the action of a magnetic field to form a transducer. In particular, the assembly comprising the movable magnetic element, the magnetic field generator and the radiator constitutes an electromechanical transducer for a loudspeaker.

[0012] The loudspeaker includes a guide device configured to guide the longitudinal movement of the mobile working unit. Preferably, the longitudinal movement of the mobile working unit is a reciprocating movement.

[0013] The guide device comprises an inner surface extending around a guide shaft, the guide shaft preferably being longitudinally oriented.

[0014] The guide device has an outer surface extending around the guide shaft. The outer surface surrounds the inner surface to define the gap. It is also contemplated that a portion of the outer surface surrounds a portion of the inner surface, defining the gap between the outer surface and that portion. In other words, the outer surface faces (i.e., is oriented toward) the inner surface to define the gap.

[0015] The guide device includes a spring that closes on itself to form a ring (i.e., forms a closed line) and is positioned in the gap.

[0016] The term "spring" is used generally to refer to an elastic element. The elastic element may be (or preferably is) a helical element with multiple windings (e.g., made from a metallic material). Alternatively, the spring (i.e., elastic element) may be (or may include) a solid element made, for example, from a circular elastic material (e.g., preferably an elastomer with shape memory), or a circular tubular element (hollow inside), for example, made from a polymer material or rubber.

[0017] Preferably, the spring contacts the inner and outer surfaces and rolls thereon, moving longitudinally in response to relative movement between the inner and outer surfaces. The inner surface may be connected to a fixed structure and the outer surface may be connected to a mobile working unit, or vice versa, i.e., the inner surface may be connected to a mobile working unit and the outer surface may be connected to a fixed structure.

[0018] Thus, in response to longitudinal movement of the movable working unit, the inner and outer surfaces move relative to each other, and the spring rolls longitudinally within the gap interposed between the inner and outer surfaces.

[0019] In particular, the spring comprises a plurality of windings, each of which preferably contacts the inner surface to define a plurality of internal contact points and contacts the outer surface to define a plurality of external contact points, and the spring thus constitutes an (indirect) contact element between the inner and outer surfaces of the guide device.

[0020] A guide device according to the present disclosure can be used to guide relative motion between two elements moving relative to each other along a guide axis (e.g., it can be used in 3D printers, linear motors, vibration dampers, and other applications).

[0021] It should be noted that the movable magnetic element may be indirectly connected to the radiator, for example, via a constant speed inverter such that longitudinal movement of the movable magnetic element in a first direction corresponds to longitudinal movement of the radiator in a second direction opposite to the first direction.

[0022] In an exemplary embodiment, the guide device includes an additional spring that closes on itself to form a ring and is disposed in the gap in contact with the inner and outer surfaces, rolling thereon while moving longitudinally in response to relative movement between the inner and outer surfaces, the spring and the additional spring defining a pair of springs.

[0023] In particular, the additional spring also comprises a plurality of windings, each of the windings contacting the inner surface to define a plurality of internal contact points and contacting the outer surface to define a plurality of external contact points, and thus the additional spring constitutes an additional (indirect) contact element between the inner and outer surfaces of the guide device.

[0024] The presence of a pair of springs has the advantage of providing stability during relative movement between the inner and outer surfaces (i.e., between the mobile working unit and the fixed structure).

[0025] In one embodiment, the loudspeaker includes a positive terminal and a negative terminal. The positive and negative terminals can be connected to a current generator to receive a current. In particular, the movable magnetic element is a coil extending between a first end and a second end. Preferably, the pair of springs are electrically conductive, such that the inner surface defines an internal conductive path for carrying current from the positive terminal to the spring and from the negative terminal to the additional spring, and the outer surface defines an external conductive path for carrying current from the spring to the first end of the coil and from the additional spring to the second end of the coil. Thus, the first end of the coil is electrically connected to the positive terminal of the loudspeaker via the spring, and the second end of the coil is electrically connected to the negative terminal of the loudspeaker via the second spring to receive a current from the generator.

[0026] In particular, the loudspeaker may include a first electrical insulating element disposed on a first portion of the inner surface and interposed between the first portion of the inner surface and the positive terminal, and a second electrical insulating element disposed on a second portion of the inner surface and interposed between the second portion of the inner surface and the negative terminal.

[0027] It should be noted that the internal and external contact points of the windings may constitute mechanical and / or electrical contact points between the inner surface, the spring (and additional springs, if present) and the outer surface.

[0028] In one example, the guide device is preloaded radially toward or away from the guide axis. In other words, the guide device is compressed radially toward or away from the guide axis by a predetermined amount relative to a rest position. The preloading of the guide device is important to ensure there are no gaps between the components of the guide device and to ensure constant mechanical contact between the outer surface of the guide device, the spring (and additional springs, if present), and the inner surface.

[0029] Additionally, in exemplary embodiments where a guide device is provided, the preload of the guide device is important to ensure consistent and uniform contact between the components.

[0030] In one example, the spring and / or additional spring is disposed in the gap so as to be compressed a predetermined amount relative to a rest position along a radial direction. In particular, each of the plurality of windings may be interposed between the outer surface and the inner surface so as to be compressed (i.e., elliptical) relative to a rest position that is circular.

[0031] In particular, the spring (and / or the additional spring) comprises a plurality of windings. In other words, the spring extends along a deployment axis, with the plurality of windings wound around the deployment axis. In particular, when the spring closes on itself to form a ring, the deployment axis of the spring closes on itself. When the spring is at rest (i.e., when there is no force acting radially towards the deployment axis), the centers of the windings may be arranged consecutively with one another to form a circle. In one example, when the spring is at rest (i.e., when there is no force acting radially towards the deployment axis), the centers of the windings may be arranged consecutively with one another to form a spiral shape. In particular, when the spring is at rest, the pitch between one spiral and the next is greater than the pitch of the windings.

[0032] Under preload conditions, i.e., when there is a force acting radially towards the deployment axis, the helices of the spring (and / or additional springs) may be forced to align so that the centers of the helices are positioned consecutively to one another to form a circle.

[0033] In other words, the spring and / or additional spring are placed in the gap so that the centers of the spirals are arranged one after the other and form a circle, which allows the guide device to be preloaded in a particularly simple and reliable manner.

[0034] In one embodiment, the loudspeaker includes an inner body defining an interior surface, the inner body being capable of being radially deformed at least over a portion thereof that contacts the spring such that the inner body is radially compressed a predetermined amount relative to a rest position.

[0035] In one example, a loudspeaker includes an outer body defining an outer surface, the outer body being capable of being radially deformed at least over a portion thereof that contacts the spring such that the outer body is radially compressed a predetermined amount relative to a rest position.

[0036] To this end, the inner body and / or the outer body may be made from a resilient material.

[0037] In one example, the inner body and / or the outer body include a plurality of slots that may extend parallel to one another around the guide shaft or may extend in a spiral shape around the guide shaft, and the slots function to allow the inner body and / or the outer body to deform toward or away from the guide shaft.

[0038] Preferably, the spring is configured to roll between a maximum travel point and a minimum travel point, defining a total travel length E between the maximum travel point and the minimum travel point. In particular, the maximum travel point is located at a greater distance E / 2 from the rest point, and the minimum travel point is located at a lesser distance −E / 2 from the rest point.

[0039] In one example, the guide device is configured to attract the spring toward the rest point, i.e., to limit the rolling of the spring between the maximum travel point and the minimum travel point. For example, the outer surface of the guide device extends toward the guide axis between the maximum travel point and the rest point and extends away from the guide axis between the minimum travel point and the rest point. Thus, the outer surface defines a seat with a curved shape for the spring. Additionally or alternatively, the inner surface may extend away from the guide axis between the maximum travel point and the rest point and between the minimum travel point and the rest point. In this way, the inner surface defines a seat with a curved shape for the spring.

[0040] When both the outer and inner surfaces are so constructed, the outer and inner surfaces define an hourglass-shaped seat for the spring.

[0041] Similarly, the outer and / or inner surfaces may also define seats for additional springs, if present.

[0042] In one embodiment, the inner surface extends towards the guide axis between the point of maximum travel and the point of rest and between the point of minimum travel and the point of rest.

[0043] In one example, the loudspeaker includes a magnet located at a stationary point, and the spring (and / or additional spring) is made of a ferromagnetic material to interact with the magnet, such that the spring is attracted toward the stationary point by the magnet. The magnet may be inserted inside an inner body defining the inner surface of the guide device, or may be located outside an outer body defining the outer surface of the guide device.

[0044] In one example, the spring comprises a plurality of windings, each winding defining a layer, and preferably, in the absence of an external force acting on the guide device, the layers of the windings are oriented radially relative to the guide axis.

[0045] In response to an external force acting on the guide device, preferably an external force acting transversely to the guide axis, each of the plurality of windings may be configured to tilt its layers for a time interval at least equal to the duration of the external force.

[0046] Preferably, the longitudinal axis coincides with the guide axis, the outer surface is fixed to the mobile working unit, in particular to the radiator and the mobile magnetic element, and the outer surface is fixed to a fixed structure. Preferably, the mobile magnetic element is rigidly connected to the radiator.

[0047] In particular, the loudspeaker may comprise an inner body defining the inner surface of the guide system. The inner body may form part of the mobile working unit of the loudspeaker. The inner body may have a cylindrical cross section or a cross section of another shape. For example, the cross section may be rectangular with rounded corners to allow the spring to roll. Preferably, the loudspeaker comprises an outer body defining the outer surface of the guide system. The outer body may form part of the fixed structure of the loudspeaker. The outer body may have a circular or rectangular cross section with rounded corners to allow the spring to roll.

[0048] In particular, the inner body may be made of a ferromagnetic material so that the magnetic field generated by the magnetic field generator can pass through it. In one example, the inner body defines a seat for the outer body. The outer body is movably housed in the seat of the inner body. The outer body may have an outer wall, and the movable magnetic element may be integrated with the outer wall of the outer body. The outer body may be integrated with the radiator. In this way, the movable magnetic element transfers movement to the radiator.

[0049] The present disclosure also provides a method for sound reinforcement, the method comprising the steps of providing a stationary structure including a magnetic field generator and a movable working unit including a movable magnetic element connected to a radiator, generating a magnetic field via the magnetic field generator, and moving the movable magnetic element in response to the generated magnetic field to move the radiator along a longitudinal axis.

[0050] The method includes guiding longitudinal movement of a mobile working unit through a guide device. The guide device may be made according to one or more aspects of the present disclosure. Preferably, the guide device includes an inner surface extending around a longitudinally oriented guide shaft and an outer surface extending around the guide shaft and surrounding the inner surface to define a gap. The guide device includes a spring that closes on itself to form a ring, the spring being disposed in the gap in contact with the inner and outer surfaces.

[0051] In particular, the guiding step is performed by rolling a spring on the inner surface and the outer surface and moving it longitudinally in response to the relative movement between the inner surface and the outer surface, the inner surface being connected to the fixed structure and the outer surface being connected to the movable working unit, or the inner surface being connected to the movable working unit and the outer surface being connected to the fixed structure.

[0052] In one embodiment, the guiding device comprises an additional spring that closes on itself to form a ring, the additional spring being disposed in the gap in contact with the inner and outer surfaces. Preferably, the guiding step is performed by rolling the additional spring on the inner and outer surfaces and moving it longitudinally in response to relative movement between the inner and outer surfaces, the spring and the additional spring defining a pair of springs.

[0053] In one example, the pair of springs are electrically conductive and the movable magnetic element is a coil extending between a first end and a second end.

[0054] The method may include providing a positive terminal and a negative terminal, and generating a current via a current generator connected to the positive terminal and the negative terminal.

[0055] The method may include passing a current between the positive terminal and the spring and between the negative terminal and the additional spring along an internal conductive path defined by an inner surface, and passing a current between the spring and a first end of the coil and between the additional spring and a second end of the coil along an external conductive path defined by an outer surface.

[0056] In one example, the method includes preloading the guide system along a radial direction toward or away from the guide axis.

[0057] In one example, the spring is configured to roll between a maximum travel point and a minimum travel point, defining a total travel length E between the maximum travel point and the minimum travel point, the maximum travel point being located at a greater distance E / 2 from the rest point and the minimum travel point being located at a lesser distance −E / 2 from the rest point. The method may include applying an action (i.e., force) to the spring toward the rest point. [Brief explanation of the drawings]

[0058] This and other features will become more apparent from the following description of preferred embodiments, illustrated by way of non-limiting example in the accompanying drawings, in which: [Figures 1A-5A] 1 illustrates a cross section of a loudspeaker according to one or more embodiments of the present disclosure. [Figures 1B-5B] 1 illustrates a cross section of a loudspeaker according to one or more embodiments of the present disclosure. [Figures 6A-6B] 1 illustrates a guide device according to one or more aspects of the present disclosure. [Figure 7-15] 1 illustrates a guide device according to one or more aspects of the present disclosure. [Figures 16A-16B] 1 illustrates a guide device according to one or more aspects of the present disclosure. [Figure 17] 1 illustrates a guide device according to one or more aspects of the present disclosure. [Figures 18A-18C] 1 illustrates a spring according to one or more embodiments of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0059] The following description will refer primarily to moving coil type loudspeakers, but it will be understood that many of the aspects described, particularly with regard to the guide arrangement, are also applicable to moving magnet type loudspeakers.

[0060] The numeral 1 in the accompanying drawings indicates a loudspeaker.

[0061] The loudspeaker 1 comprises a stationary structure including a magnetic field generator 201. The magnetic field generator is a permanent magnet. The stationary structure comprises an inner body 202. The inner body 202 can be magnetized so as to transmit the magnetic field generated by the permanent magnet 201. In other words, the inner body 202 constitutes a magnetic core.

[0062] The diffuser 1 includes a movable working unit. The movable working unit includes a radiator 301 movable along a longitudinal axis L and a movable magnetic element 302. The movable magnetic element 302 is a coil. The movable magnetic element 302 is connected to the radiator 301 and is movable under the action of a magnetic field generated by a permanent magnet 201, and together with the permanent magnet 201, forms an electromechanical transducer for moving the radiator 301. The movable working unit includes an outer body 303. In some of the illustrated examples, the outer body 303 has a cylindrical shape extending around the longitudinal axis L. The outer body 303 defines an outer wall 303A, and the coil of the movable magnetic element 302 includes a plurality of windings wound around and integrally connected to the outer wall 303A of the outer body 303. Thus, the movable magnetic element 302 is connected to the radiator 301 by the outer body 303.

[0063] The inner body 202 defines a sheet T surrounding the longitudinal axis L and configured to accommodate the outer body 303 and the movable magnetic element 302. The sheet T also functions as an air gap. The sheet T comprises an abutment surface for the inner body 202. The outer body 303 is therefore mounted within the sheet T of the inner body 202 so as to be movable along the longitudinal direction. In practice, when an electric signal is applied to the coil 302, the coil 302 moves within the sheet T under the action of the magnetic field generated by the permanent magnet 201 along the longitudinal direction L, causing the inner body 202 and the radiator 301 to move.

[0064] The loudspeaker 1 comprises a guide device 10 for guiding the longitudinal reciprocating movement of the mobile working unit relative to the fixed structure. In particular, the guide device 10 comprises an inner surface 202A defined by an inner body 202 of the fixed structure. The inner surface 202A extends around a guide axis G, which coincides with the longitudinal axis L when the guide device 10 forms part of the loudspeaker 1.

[0065] The guide device 10 includes an outer surface 303B defined by the outer body 303 of the mobile working unit. The outer surface 303B extends around the guide axis G, i.e., around the longitudinal axis L. In particular, the outer surface 303B surrounds the inner surface 202A to define a gap.

[0066] The guide device 10 comprises a spring M that closes on itself to form a ring and is disposed in the gap in contact with the inner surface 202A and the outer surface 303B and rolls thereon around the longitudinal axis L.

[0067] The guide device 10 comprises an additional spring M' which closes on itself to form a ring and is arranged in the gap in contact with the inner surface 202A and the outer surface 303B and rolls over them around the longitudinal axis L.

[0068] In the following description, aspects described with respect to spring M are also applicable to additional spring M' unless otherwise specified.

[0069] The inner surface 202A is connected to a fixed structure and the outer surface 303B is connected to the mobile working unit, so that when the mobile working unit moves longitudinally, the spring M rolls between the inner surface 202A and the outer surface 303B.

[0070] Spring M is configured to roll between a maximum travel point and a minimum travel point, between which spring M defines a total travel length E. The maximum travel point is located a greater distance E / 2 from the rest point, and the minimum travel point is located a lesser distance −E / 2 from the rest point.

[0071] Preferably, the guide device 10 is preloaded along a radial direction toward or away from the guide axis G, the radial direction being perpendicular to the guide axis G. The guide device 10 may be configured to pull the spring M toward a rest point.

[0072] 15, the preload can be achieved by placing a spring M in the gap so that the windings are radially compressed by a predetermined amount relative to the rest position. The winding layers therefore have an elongated oval (or elliptical) shape along the guide direction given by the guide axis G relative to the radial direction of the guide axis G.

[0073] FIG. 18A shows a spring M that closes on itself to form a ring. As shown in FIG. 18A, the centers of the windings of spring M can be arranged back-to-back to form a circle. FIG. 18B shows an example of a spring M that does not close on itself, but rather has centers arranged back-to-back along a straight line. FIG. 18C shows another example of a spring M (that does not close on itself), in which the centers of the windings are arranged back-to-back to form a helix. When the spring is at rest, the pitch between one helix and the next is greater than the pitch of the windings. To create a preload (i.e., under a preload condition), the helices of spring M are forced to align on a single line.

[0074] 8-12 show, schematically and by way of example only, further examples of creating a radial preload. Figure 8 shows an example in which the outer surface 303B of the outer body 303 is radially deformable at least in a portion thereof that contacts the spring M. Thus, to create the preload, the outer body 303 is radially compressed away from the guide axis G by a predetermined amount relative to its rest position.

[0075] According to one aspect of the disclosure, there is also a centering system that centers the spring within its seat, exerting a suction force on the spring to bring it to a central rest position (and that will bring it to the central rest position when no external forces are acting on the inner and / or outer surfaces). This centering system can be embodied in various ways. For example, there may be a magnet at the rest position, and additionally or alternatively, slots on the inner and / or outer surfaces that allow these surfaces to elastically deform along the radial direction to a variable extent, with the extent being maximum at the rest position and minimum at a maximum or minimum travel position. Additionally or alternatively, the inner and / or outer surfaces may be curved to form a cradle-like shape, with the rest position being the spring's stable equilibrium (and only one) position.

[0076] 8 shows an example in which the spring M is attracted toward the rest point. In practice, the outer surface 303B of the outer body 303 extends between the maximum travel point and the rest point and between the minimum travel point and the rest point, away from the guide axis G, so that when the spring M is at the maximum travel point or the minimum travel point, it is attracted toward the rest point by the outer surface 303B.

[0077] 9 shows an example in which the inner surface 202A of the inner body 202 is radially deformable at least in a portion thereof that contacts the spring M. Thus, to create the preload, the inner body 202 is compressed radially toward the guide axis G by a predetermined amount relative to its rest position.

[0078] 9 also shows an example in which the spring M is attracted toward the rest point. In reality, the inner surface 202A extends toward the guide axis G between the maximum travel point and the rest point and between the minimum travel point and the rest point, so that when the spring M is at the maximum travel point or the minimum travel point, it is attracted toward the rest point by the inner surface 202A.

[0079] 10, 11, and 12 illustrate exemplary embodiments in which the inner body 202 or the outer body 303 includes a plurality of slots 101 extending around the guide axis G. The slots 101 allow the inner body 202 or the outer body 303 to be radially compressed toward or away from the guide axis G to create a radial preload. In FIG. 10, the inner body 202 includes a plurality of slots 101 extending parallel to the guide axis G, such that under a preload condition, the slots 101 compress the inner body 202 toward the guide axis G. In FIG. 11, the slots 101 extend along a helical configuration around the guide axis G. In FIG. 12, the outer body 303 includes a plurality of slots 101 extending parallel to the guide axis G, such that under a preload condition, the slots 101 compress the outer body 303 away from the guide axis G.

[0080] 10, 11 and 12 also show examples of how spring M can be attracted towards a rest point. In fact, when spring M is at a maximum or minimum travel position, slot 101 attracts spring M towards a rest point, allowing inner body 202 or outer body 303 to be compressed towards or away from guide axis G, respectively.

[0081] 13, in another example of how the spring M can be attracted toward the stationary point, the guide device 10 includes a magnet 102 installed at the stationary point, and the spring M is made of a ferromagnetic material to interact with the magnet 102. In the example shown, the magnet 102 is inserted inside the inner body 202, but it may also be installed outside the outer body 303, i.e., facing the inner surface 303A of the outer body 303. In particular, the magnet 102 attracts the spring M toward the stationary point.

[0082] In one example, the loudspeaker 1 includes a positive terminal 4A and a negative terminal 4B, both configured to receive current from a current generator, and the spring M and additional spring M' are electrically conductive. The coil 302 extends between a first end 302A and a second end 302B. The spring M is in electrical contact with the positive terminal 4A and the first end 302A of the coil 302. The additional spring M' is in electrical contact with the negative terminal 4B and the second end 302B of the coil 302. The loudspeaker includes a first electrical insulating element 5A and a second electrical insulating element 5B. The first electrical insulating element 5A is disposed on the inner surface 202A of the inner body 202 between the inner surface 202A and the spring M, which contacts the positive terminal 4A, to electrically insulate the inner body 202 from the spring M. A second electrical insulating element 5B is disposed on the inner surface 202A of the inner body 202 between the inner surface 202A and the additional spring M' in contact with the negative terminal 4B so as to electrically insulate the inner body 202 from the additional spring M'. Thus, when the positive terminal 4A and the terminal 4B receive a current from the generator, the spring M and the additional spring M' transmit the current to the coil 302.

[0083] FIG. 14 shows, by way of example only, a guide device 10 in which the inner body 202 and the outer body 303 extend around a guide axis G, the guide axis G having a curvature direction.

[0084] 16A and 16B show examples in which the inner body 202 and the outer body 303 have square cross sections with rounded corners to allow the spring M to roll.

[0085] The following paragraphs, listed alphabetically for reference, are non-limiting example modes describing the guide apparatus. A. A guide device 10, an inner surface 202A extending around the guide axis G; an outer surface 303B extending around the guide axis G and surrounding the inner surface 202A to define a gap; a spring M that closes on itself to form a ring, the spring M being arranged in the gap in contact with the inner surface 202A and the outer surface 303B and rolling thereon while moving along the guiding direction in response to the relative movement between the outer surface 303B and the inner surface 202A. A.1. The guide device 10 described in paragraph A, comprising an additional spring M' that closes on itself to form a ring and is positioned in the gap in contact with the inner surface 202A and the outer surface 303B, rolling thereon while moving along the guide direction in response to relative movement between the inner surface 202A and the outer surface 303B, wherein spring M and additional spring M' define a pair of springs. A.2. The guide device 10 of paragraph A or paragraph A.1, wherein the spring M is electrically conductive. A.3. The guide device 10 of any one of paragraphs A-A.2, wherein the guide device 10 is preloaded along a radial direction toward or away from the guide axis G. A.3.1. The guide device 10 described in paragraph A.3, wherein the spring M is positioned in the gap so that it is compressed a predetermined amount along the radial direction relative to a rest position. A.3.1.1. The guide device 10 described in paragraph A.3.1, wherein the spring M comprises a plurality of windings, the centers of the windings being arranged successively with respect to one another to form a helical shape, and wherein, in the rest position of the spring M, the pitch of the helix is ​​greater than the pitch of the windings. A.3.2. A guide device 10 as described in any one of paragraphs A.3 to A.3.1.1, comprising an inner body 202 defining an inner surface 202A, the inner body 202 being radially deformable at least in a portion thereof that contacts the spring M so as to be radially compressed by a predetermined amount relative to a rest position. A.3.3. A guide device 10 as described in any one of paragraphs A.3. to A.3.2, comprising an outer body 303 defining an outer surface 303B, the outer body 303 being radially deformable at least in a portion thereof that contacts the spring M so as to be compressed radially by a predetermined amount relative to a rest position. A.3.3.1. The guide device 10 of paragraph A.3.2 or A.3.3, wherein the inner body 202 or the outer body 303 comprises a plurality of slots 101. A.3.3.1.1. The guide device 10 described in paragraph A.3.3.1, wherein the slot 101 extends along a spiral shape around the guide axis G. A.4. A guide device 10 as described in any one of paragraphs A to A.3.3.1.1., wherein the spring M is configured to roll between a maximum travel point and a minimum travel point, defining a total travel length E between the maximum travel point and the minimum travel point, the maximum travel point being located at a greater distance E / 2 from the rest point, and the minimum travel point being located at a lesser distance -E / 2 from the rest point. A.4.1. The guide device 10 of paragraph A.4, wherein the guide device 10 is configured to attract the spring M toward a rest point. A.4.1.1. The guide device 10 described in paragraph A.4.1., wherein the inner surface 202A extends toward the guide axis G between the maximum travel point and the rest point, and between the minimum travel point and the rest point. A.4.1.2. The guide device 10 of paragraph A.4.1. or paragraph A.4.1.1, wherein the outer surface 303B extends away from the guide axis G between the maximum travel point and the rest point, and between the minimum travel point and the rest point. A.4.1.3. A guide device 10 as described in any one of paragraphs A.4.1. to A.4.1.2, comprising a magnet 102 arranged at a stationary point, the spring being made of a ferromagnetic material so as to interact with the magnet 102. B. A method of creating a guide, comprising: - providing an inner surface 202A extending around a guide axis G; - providing an outer surface 303B extending around the guide axis G and surrounding the inner surface 202A to define a gap; - providing a spring M located in the gap in contact with the inner surface 202A and the outer surface 303B, which closes on itself to form a ring; - moving the inner surface 202A and the outer surface 303B relative to each other; - rolling the spring on the inner surface 202A and the outer surface 303B along the guide direction in response to a relative movement between the inner surface 202A and the outer surface 303B. B.1. - providing an additional spring M' that is placed in the gap in contact with the inner surface 202A and the outer surface 303B and that closes on itself to form a ring; - rolling an additional spring M' on the inner surface 202A and on the outer surface 303B along the guide direction in response to the relative movement between the inner surface 202A and the outer surface 303B. B.2. The method of paragraph B or paragraph B.1, wherein spring M is electrically conductive and the method includes conducting electrical current through spring M from inner surface 202A to outer surface 303B. B.3. The method of any one of paragraphs B to B.2, including the step of preloading along a radial direction toward or away from the guide axis G. B.3.1. The method of paragraph B.3, including compressing spring M radially relative to a rest position by a predetermined amount. B.3.1.1. The method of paragraph B.3.1, wherein the spring M comprises a plurality of windings, the centers of the windings being positioned consecutively to one another to form a helical shape, and in the rest position of the spring M, the pitch of the helix is ​​greater than the pitch of the windings, and the compressing step includes aligning the helixes so that the centers of the helixes are positioned consecutively to one another to form a circle. B.3.2. providing an inner body 202 defining an inner surface 202A; The method according to any one of paragraphs B.3. to B.3.1.1, wherein the inner body 202 is radially deformed at least in a portion thereof that contacts the spring M so as to be radially compressed by a predetermined amount relative to a rest position. B.3.3. - providing an outer body 303 defining an outer surface 303B; The method according to any one of paragraphs B.3. to B.3.2, wherein the outer body 303 is radially deformed at least in a portion thereof that contacts the spring M so as to be radially compressed by a predetermined amount relative to a rest position. B.3.3.1. The method of paragraph B.3.2 or B.3.3, wherein inner body 202 or outer body 303 comprises a plurality of slots 101. B.3.3.1.1. The method according to paragraph B.3.3.1, wherein the slot 101 extends along a spiral shape around the guide axis G. B.4. The method of any one of paragraphs B to B.3.3.1.1, wherein the spring M rolls between a maximum travel point and a minimum travel point, defining a total travel length E between the maximum travel point and the minimum travel point, the maximum travel point being located at a greater distance E / 2 from the rest point, and the minimum travel point being located at a lesser distance -E / 2 from the rest point. B.4.1. The method of paragraph B.4, including the action of attracting spring M toward a rest point. B.4.1.1. The method of paragraph B.4.1., wherein inner surface 202A extends toward guide axis G between a maximum travel point and a rest point, and between a minimum travel point and a rest point. B.4.1.2. The method of paragraph B.4.1. or paragraph B.4.1.1, wherein outer surface 303B extends away from guide axis G between the maximum travel point and the rest point, and between the minimum travel point and the rest point. B.4.1.3. - providing a magnet 102 at a stationary point; - creating an interaction between the spring M and the magnet 102, wherein the spring M is made of a ferromagnetic material. [Prior art documents] [Patent documents]

[0086] [Patent Document 1] US5014323A [Patent Document 2] EP2550724

Patent Document 3

Patent document 4

Patent document 5

Claims

1. A loudspeaker (1), a stationary structure including a magnetic field generator (201); a mobile working unit comprising a radiator (301) movable along a longitudinal axis (L) and a mobile magnetic element (302) connected to said radiator (301) and movable under the action of a magnetic field to form a transducer; a guide device (10) configured to guide the longitudinal reciprocating movement of the mobile working unit, The guide device (10) an inner surface (202A) extending around a longitudinally oriented guide axis (G); an outer surface (303B) extending around said guide shaft (G) and surrounding said inner surface (202A) to define a gap; a spring (M) that closes on itself to form a ring, the spring (M) being arranged in the gap in contact with said inner surface (202A) and said outer surface (303B) and rolling thereon while moving longitudinally in response to the relative movement between said inner surface (202A) and said outer surface (303B); The inner surface (202A) is connected to the fixed structure and the outer surface (303B) is connected to the mobile working unit, or the inner surface (202A) is connected to the mobile working unit and the outer surface (303B) is connected to the fixed structure, a loudspeaker (1).

2. 2. The loudspeaker (1) of claim 1, wherein the guide device (10) comprises an additional spring (M') that closes on itself to form a ring, the additional spring (M') being positioned in the gap in contact with the inner surface (202A) and the outer surface (303B) and rolling thereon while moving longitudinally in response to relative movement between the inner surface (202A) and the outer surface (303B), the spring (M) and the additional spring (M') defining a pair of springs.

3. a positive terminal (4A) and a negative terminal (4B), both connectable to a current generator to receive current; - said mobile magnetic element (302) is a coil extending between a first end (302A) and a second end (302B); - the pair of springs are electrically conductive; 3. A loudspeaker (1) according to claim 2, wherein the inner surface (202A) defines an internal conductive path for carrying the current from the positive terminal (4A) to the spring (M) and from the negative terminal (4B) to the additional spring (M'), and the outer surface (303B) defines an external conductive path for carrying the current from the spring (M) to the first end (302A) of the coil (302) and from the additional spring (M') to the second end (302B) of the coil (302).

4. 4. The loudspeaker (1) according to any one of claims 1 to 3, wherein the guide device (10) is preloaded along a radial direction towards or away from the guide axis (G).

5. 5. The loudspeaker (1) according to claim 4, wherein the spring (M) is arranged in the gap so as to be compressed along the radial direction by a predetermined amount relative to a rest position.

6. 6. The loudspeaker (1) according to claim 5, wherein the spring (M) comprises a plurality of windings, the centers of which are arranged successively with one another to form a helical shape, and in the rest position of the spring (M), the pitch of the helix is ​​greater than the pitch of the windings.

7. At least one of the following conditions is true: i) the loudspeaker (1) comprises an inner body (202) defining the inner surface (202A), the inner body (202) being deformable along the radial direction at least in a portion thereof that contacts the spring (M) so as to be compressed by a predetermined amount relative to a rest position along the radial direction; ii) the loudspeaker (1) comprises an outer body (303) defining the outer surface (303B), the outer body (303) being deformable along the radial direction in at least a portion thereof that contacts the spring (M) so as to be compressed by a predetermined amount relative to a rest position along the radial direction;

8. 8. The loudspeaker (1) according to claim 7, wherein the inner body (202) or the outer body (303) comprises a plurality of slots (101) extending along a spiral shape around the guide axis (G).

9. - said spring (M) is configured to roll between a point of maximum and minimum travel, defining a total length of travel E between said point of maximum and minimum travel, said point of maximum travel being located at a greater distance E / 2 from a rest point and said point of minimum travel being located at a lesser distance -E / 2 from the rest point; - A loudspeaker (1) according to any one of claims 1 to 8, wherein the guide device (10) is configured to attract the spring (M) towards the rest point.

10. At least one of the following conditions is true: i) the inner surface (202A) extends towards the guide axis (G) between the maximum movement point and the rest point and between the minimum movement point and the rest point; ii) said outer surface (303B) extends away from said guide axis (G) between said maximum movement point and said rest point and between said minimum movement point and said rest point; iii) the loudspeaker (1) comprises a magnet (102) placed at the stationary point, and the spring (M) is made of a ferromagnetic material so as to interact with the magnet (102).

11. 11. A loudspeaker (1) according to any one of claims 1 to 10, wherein the longitudinal axis (L) coincides with the guide axis (G), the outer surface (303B) is fixed to the radiator (301) and the movable magnetic element (302), and the inner surface (202A) is fixed to the fixed structure.

12. 12. A loudspeaker (1) according to any one of claims 1 to 11, wherein the spring comprises an annular tubular element.

13. 13. The loudspeaker (1) according to claim 12, wherein the annular tubular element is made from a polymer material.

14. A sound reinforcement method, comprising: - providing a stationary structure comprising a magnetic field generator (201); - providing a mobile working unit comprising a radiator (301) and a mobile magnetic element (302) connected to said radiator (301); - generating a magnetic field via said magnetic field generator (201); - moving said mobile magnetic element (302) in response to said generated magnetic field, thereby moving said radiator (301) along its longitudinal axis (L); - guiding the longitudinal movement of said mobile working unit via a guide device (10), The guide device (10) comprises an inner surface (202A) extending around a longitudinally oriented guide shaft (G), an outer surface (303B) extending around the guide shaft (G) and surrounding the inner surface (202A) to define a gap, and a spring (M) closing on itself to form a ring, the spring (M) being disposed in the gap in contact with the inner surface (202A) and the outer surface (303B), and the guiding step is a spring (M) disposed between the inner surface (202A) and the outer surface (303B). the spring (M) rolling on the inner surface (202A) and the outer surface (303B) while moving longitudinally in response to relative movement between the inner surface (202A) and the outer surface (303B), wherein the inner surface (202A) is connected to the fixed structure and the outer surface (303B) is connected to the mobile working unit, or the inner surface (202A) is connected to the mobile working unit and the outer surface (303B) is connected to the fixed structure.

15. - the guiding device (10) comprises an additional spring (M') that closes on itself to form a ring, the additional spring (M') being arranged in the gap in contact with the inner surface (202A) and the outer surface (303B), the guiding step being achieved by rolling the additional spring (M') over the inner surface (202A) and the outer surface (303B) while moving longitudinally in response to the relative movement between the inner surface (202A) and the outer surface (303B), the spring (M) and the additional spring (M') defining a conductive spring pair; - said mobile magnetic element (302) is a coil extending between a first end (302A) and a second end (302B); The method comprises: - providing a positive terminal (4A) and a negative terminal (4B); - generating a current via a current generator connected to said positive terminal (4A) and said negative terminal (4B); - passing current between the positive terminal (4A) and the spring (M) and between the negative terminal (4B) and the additional spring (M') along an internal conductive path defined by the inner surface (202A), and passing current between the spring (M) and the first end (302A) of the coil (302) and between the additional spring (M') and the second end (302B) of the coil (302) along an external conductive path defined by the outer surface (303B).

16. 16. A method according to claim 14 or 15, comprising the step of preloading the guide device (10) along a radial direction towards or away from the guide axis (G).

17. 17. The method according to any one of claims 14 to 16, wherein the spring (M) rolls between a maximum travel point and a minimum travel point, defining a total length of travel E between the maximum travel point and the minimum travel point, the maximum travel point being located at a greater distance E / 2 from a rest point and the minimum travel point being located at a lesser distance -E / 2 from the rest point, the method comprising attracting the spring (M) towards the rest point.

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