Loudspeaker and method for propagating sound

Abstract

A loudspeaker (1) comprising: an active radiator (30) movable along a longitudinal axis (X); and a ferromagnetic circuit comprising: a central core (21) extending along a longitudinal axis (X) from a first end (21B) close to the active radiator (30) to a second end (21B); an outer core (22) located outside the central core (21) and separated from a first end (21A) of the central core (21) so as to define a gap (T) in which a coil (40) connected to the radiator (30) is longitudinally movable; a main magnet (23) having a ring shape and inserted into the outer core (22) in a longitudinally oriented polarization to generate a main magnetic flux circulating in a ferromagnetic loop to pass through the gap (T) in a pass-through direction; a secondary magnet (50) oriented longitudinally and located at the first end (21A) of the central core (21) to generate a secondary magnetic flux that passes through the gap (T) in the direction (V) of passage and is closed on itself outside the ferromagnetic circuit.

Description

Technical Field

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

[0002] Generally, a loudspeaker includes a ferromagnetic circuit in which a magnetic field generated by a permanent magnet or a coil through which an electric current flows. The loudspeaker also includes a coil or magnet that can move within gaps in the ferromagnetic circuit under the influence of the magnetic field, and this coil or magnet directly or indirectly drives a (active) radiator, the movement of which produces sound. Therefore, the ferromagnetic circuit is subdivided by gaps into a central core (inside the gap) and an outer core (outside the gap).

[0003] In this context, the prior art teaches that the magnetic flux circulating in a ferromagnetic circuit can be generated by a magnet placed in the outer core; this type of scheme is known, for example, from patent documents US2015 / 0030199A and US8135162B2.

[0004] Document US2015 / 0030199A proposes to generate a magnetic field shielding effect by placing an additional magnet (marked as 105 in the figure) below the ferromagnetic circuit and extending below both the central core and the outer core.

[0005] The loudspeaker US8135162B2 proposes to increase the magnetic flux circulating in the ferromagnetic circuit by using an additional magnet aligned with the main magnet (in the attached diagram, the two magnets are labeled 104 and 108).

[0006] Patent documents US5461677A, US7068807B2, JPH10112896A, and US2016 / 227325A1 describe other examples of loudspeakers equipped with additional magnets. In US2016 / 227325A1, the additional magnet located at the end of the central core near the radiator is a magnet called a bucking magnet, i.e., a magnet used to reduce magnetic flux loss; for this purpose, the additional magnet has a polarity opposite to that of the magnet located in the outer core. US7068807B2 also shows an additional magnet with a polarity opposite to that of the magnet in the outer core. JPH10112896A describes an additional magnet placed at the end of the central core near the radiator, located within a recess formed in the central core. A disadvantage of this configuration is that it increases the magnetic flux in the central poles, causing saturation of the central poles, particularly in the portions near the gap and near the additional magnet.

[0007] Document US5461677A relates to a loudspeaker comprising a ferrofluid material for cooling the loudspeaker; in this case, an additional magnet is used to contain the ferrofluid material in which a coil is immersed. To ensure heat exchange between the coil and the ferrofluid material, the movement of the coil within the gap must be restricted and must not pass through the additional magnet. However, restricting the movement of the coil negatively impacts the loudspeaker's SPL parameter (i.e., the amount of sound produced). This problem can be avoided by using a larger additional magnet, which disadvantageously means increasing the size and cost of the loudspeaker.

[0008] Therefore, the industry needs speakers that are particularly compact (i.e., small in size) but at the same time offer particularly high performance. Summary of the Invention

[0009] One object of this disclosure is to provide a loudspeaker and a method for transmitting sound that overcomes the aforementioned disadvantages of the prior art.

[0010] In particular, the purpose of this disclosure is to provide a compact loudspeaker characterized by high performance.

[0011] Another objective is to provide a loudspeaker characterized by a particularly wide and linear frequency response.

[0012] These objectives are fully achieved by the loudspeaker and the method for propagating sound as characterized in the appended claims of this disclosure.

[0013] Specifically, the loudspeaker includes an active radiator that can move along the longitudinal axis to generate sound waves.

[0014] The loudspeaker includes a ferromagnetic circuit. The ferromagnetic circuit includes a central core extending along a longitudinal axis. The central core extends from a first end to a second end. The first end is close to the active radiator, while the second end is away from the active radiator.

[0015] The ferromagnetic circuit includes an outer core located outside a central core. The outer core surrounds a longitudinal axis. The outer core (preferably at least a portion thereof) is separated from the central core. For example, the outer core is separated from a first end of the central core to define a longitudinally extending gap. In other words, the outer core is longitudinally separated from the central core to define a gap at a first end of the central core.

[0016] The loudspeaker includes a magnetic field generator. The magnetic field generator can be inserted into the outer core, or it can be inserted into the inner core. The magnetic field generator is configured to generate a main magnetic flux that circulates in a ferromagnetic loop, particularly through the gap in the passing direction.

[0017] The field generator can be, for example, a coil coaxial with the longitudinal axis (that is, wound around the longitudinal axis) or a permanent magnet. Preferably, the loudspeaker includes a permanent magnet, i.e., a main magnet.

[0018] The main magnet is toroidal. It is inserted into the outer core. The main magnet is configured to generate a main magnetic flux. This main magnetic flux circulates in a ferromagnetic loop to pass through the gap in the through-path direction. Preferably, the main magnet forms an interruption in the outer core. The main magnet has a longitudinally oriented polarization. The main magnetic flux passes through the central core along the through-path orientation.

[0019] The loudspeaker includes a movable element configured to move along a movement orientation parallel to the longitudinal axis to move an active radiator. The movable element can be a coil or a magnet. The movable element is located within a gap and is preferably coaxial with the longitudinal axis.

[0020] Preferably, the loudspeaker includes a coil that is movable along a movement orientation parallel to the longitudinal axis to move the active radiator within the gap, and the coil is coaxial with the longitudinal axis.

[0021] The loudspeaker includes a secondary magnet. The secondary magnet is aligned with the longitudinal axis. The secondary magnet is located at a first end of the central core to generate a secondary magnetic flux. The secondary magnetic flux passes through a gap in the passing direction and closes itself outside the ferromagnetic loop. Preferably, the secondary magnet has a longitudinally oriented polarization. The secondary magnetic flux passes through the central core along a passing orientation inconsistent with that of the primary magnetic flux. This reduces the magnetic flux density in the central core.

[0022] Preferably, the main magnet and the auxiliary magnet are not aligned longitudinally.

[0023] Therefore, the presence of the secondary magnet has the effect of reducing the magnetic flux density in the central core and increasing the magnetic flux density through the gap. Under the same conditions of magnetic flux through the gap, this allows for the use of a smaller, and therefore cheaper, main magnet, and allows for a lower saturation level in the central core. This means that the central core can be made of less expensive materials, thus making it more economical and allowing for a smaller size.

[0024] In practice, other methods are possible to prevent core saturation, including increasing the core size or using expensive materials characterized by high saturation. However, such solutions make loudspeakers bulky and expensive. Using this invention, the total flux in the core is much lower under the same flux to the gap, thus allowing for limitations on loudspeaker size without the use of expensive materials.

[0025] Another function of the auxiliary magnet is to reduce magnetic flux loss (to the gap), resulting in a more uniform distribution within the gap; therefore, the force generated to move the coil located in the gap is also more symmetrical. Note that using an auxiliary magnet increases losses outside the speaker. Therefore, an additional auxiliary magnet configured according to the reaction magnet can be used.

[0026] In one example, the secondary magnet is placed flush with the central core. In other words, the secondary magnet is circular in shape and its radius relative to the longitudinal axis is (essentially) equal to the radius of the central core measured at the second end of the central core. It is also conceivable to use a secondary magnet with a radius greater than or less than that of the central core.

[0027] In one example, the auxiliary magnet has a lower surface that contacts (directly or indirectly) a first end of the central core, and a top surface opposite the lower surface. The top and lower surfaces extend in corresponding planes perpendicular to the longitudinal axis. The auxiliary magnet has an outer surface extending around (i.e., around) the longitudinal axis. Specifically, the outer surface faces away from the longitudinal axis. The peripheral edge included between the top and outer surfaces may have a chamfer (to define a chamfered edge); in other words, the auxiliary magnet may have a trapezoidal cross-section, considering that the auxiliary magnet extends through its cross-section along a plane including the longitudinal axis. The chamfered edge facilitates the passage of power cables.

[0028] Preferably, the first end of the central core extends (only) in an extending plane perpendicular to the longitudinal axis. Therefore, the lower surface of the sub-magnet contacts (directly or indirectly) the first end of the central core to define a contact surface located in the extending plane of the central core. The fact that the contact surface is located in the extending plane of the central core (and therefore the sub-magnet is not located in the recess of the central core) reduces the risk of saturation of the portions of the central core near the sub-magnet and near the gap.

[0029] In one example, the secondary magnet has an inner surface opposite the outer surface, which extends around and faces the longitudinal axis. Therefore, the secondary magnet can be ring-shaped, i.e., annular.

[0030] Specifically, the outer core may include an upper part and a lower part. The upper and lower parts may be longitudinally aligned with each other. The main magnet may be located between the upper and lower parts of the outer core along an orientation parallel to the longitudinal axis. The gap is defined by a portion of the outer surface of the central core, a portion of the upper surface of that portion facing the outer surface of the central core, and a portion of the surface of the main magnet.

[0031] Regarding the cross-section in a half-plane with the longitudinal axis as its origin, the radial extent of the outer core can be greater than that of the central core. In other words, the extent to which the outer core extends along the radial orientation can be greater than that of the central core along the radial orientation, wherein the radial orientation is defined perpendicular to the longitudinal axis.

[0032] The upper part is annular. The upper part of the outer core has an inner surface that extends around the longitudinal axis and faces the longitudinal axis (in other words, it is close to the longitudinal axis). The upper part has an outer surface that is opposite to the inner surface and extends around the longitudinal axis.

[0033] In one example, the area S of the inner surface of the upper part of the outer core tp The area S of the radially extending surface of the central core pp The ratio between (measured with respect to cross sections in a half-plane with the longitudinal axis as its origin) is less than or equal to 1.3, especially 1.6, and even more especially 2.

[0034] Ratio S tp / S pp This represents the relationship between the upper surface of the outer core through which a given magnetic flux passes and the cross-section of the central core through which the same magnetic flux passes. For an outer core of the same size, the presence of a secondary magnet allows for a reduction in the cross-section of the central core (and thus a reduction in the size of the central core) in order to achieve high performance with limited size and inertia.

[0035] The coil is configured to move along a movement orientation preferably parallel to the longitudinal axis. The coil moves along this movement orientation between a first end and a second end opposite the first end. The coil moves along this movement orientation such that the first end (or the second end) moves between a maximum point and a minimum point. At the maximum point, the radiator moves away from the central core; at the minimum point, the radiator moves towards the central core. Specifically, at the maximum point, the coil (completely or partially) leaves the gap (specifically, at least one of the two ends of the coil leaves the gap, more specifically, the first end of the coil leaves the gap). Specifically, at the maximum point, the first end may move longitudinally past the auxiliary magnet. During the movement between the maximum and minimum points, the first end (or the second end) of the coil passes through a balance point, which is preferably equidistant from the maximum and minimum points.

[0036] Preferably, the coil moves in the air space.

[0037] In one example, the height H of the upper inner surface of the outer core pp The distance X between the first end of the coil and the balance point and the maximum limit point max The ratio between them is less than or equal to 2, especially 1.6, and even more especially 1.4 (particularly, the height of the outer surface measured parallel to the longitudinal axis, as well as the distance between the balance point and the maximum point). This ratio indicates the relationship between the coil travel and the height of the upper part of the outer core; the greater the coil travel, the wider the frequency response of the speaker.

[0038] In one example, the height H of the upper inner surface of the outer core, measured parallel to the longitudinal axis. pp With the height H of the coil vcThe ratio between them is greater than or less than 1 (that is, different from 1). Preferably, the ratio is less than or equal to 1.5, especially less than 1.8, and even more particularly less than 2. In fact, for good speaker response linearity, it is useful that the height of the coil is significantly less than (or greater than but hardly equal to) the height of the upper part of the outer core.

[0039] In one example, the height H of the upper inner surface of the outer core, measured parallel to the longitudinal axis. pp Height H of the main magnet m The ratio between them is less than or equal to 1.55, specifically less than or equal to 1.7, and even more specifically, less than or equal to 2. In fact, in order to achieve high performance while maintaining a reduced size, it is useful to limit the height of the main magnet compared to the height of the upper part.

[0040] In one example, the diameter D of the suspension... d With respect to the diameter D of the main magnet m The ratio between them is less than or equal to 1.3, especially less than or equal to 1.13, and even more especially 1.1. In fact, the larger the size of the main magnet relative to the speaker piston, the higher the speaker power.

[0041] Preferably, with respect to the cross-section of a half-plane with the longitudinal axis as its origin, the radial extent of the secondary magnet is equal to the radial extent of the central core. In other words, the secondary magnet has no portion located at the outer core; that is, with respect to the cross-section of a half-plane with the longitudinal axis as its origin, the secondary magnet does not extend radially at the outer core, i.e., it does not extend radially through the central core.

[0042] In one example, the secondary magnet is in direct contact with the first end of the central core, or in contact with the first end of the central core through a region with high permeability.

[0043] Preferably, the loudspeaker includes a basket. The basket surrounds the ferromagnetic circuit and the coil. The basket has a circular aperture. The radiator is fixed to the basket (via the suspension) at the circular aperture.

[0044] In one example, the gap defines an air space. The loudspeaker includes a center position adjustment element surrounding a longitudinal axis. The center position adjustment element is located between the radiator and the upper part of the outer core. The center position adjustment element and the top surface of the upper part of the core define an air space. The air space defined by the gap and the air space defined by the center position adjustment element and the top surface of the upper part are in air communication.

[0045] In one embodiment, the outer core is also separated from the second end of the central core to define a longitudinally extending additional gap. Preferably, the additional gap is aligned with the aforementioned gap. In this case, the main magnetic flux passes through the additional gap in the additional passing direction. Preferably, the additional passing direction is opposite to the first passing direction.

[0046] The loudspeaker may include an additional sub-magnet aligned with the longitudinal axis and located at a second end of the central core. The additional sub-magnet generates an additional sub-magnetic flux that passes through an additional gap in an additional passing direction and closes itself outside the ferromagnetic loop. Preferably, the additional sub-magnet has longitudinally oriented polarization. The additional sub-magnet and the sub-magnet may be longitudinally aligned with each other. The main magnet may be misaligned with the additional sub-magnet and the sub-magnet. The additional sub-magnetic flux is configured to pass through the central core in a direction opposite to that of the main magnetic flux.

[0047] The auxiliary magnet can be made to have the same properties as those described for the auxiliary magnet.

[0048] The loudspeaker may include an additional coil located in an additional gap. The additional coil is coaxial with the longitudinal axis and movable along an additional movement orientation parallel to the longitudinal axis. Preferably, the additional movement orientation of the additional coil is aligned with the movement orientation of the coil; that is, the coil and the additional coil are aligned along the same orientation parallel to the longitudinal axis. The coil and the additional coil may be configured to move along the movement orientation and the additional movement orientation, respectively, in the same or opposite directions.

[0049] In particular, the additional gap may be defined by a portion of the outer surface of the central core, a portion of the lower surface of that portion facing the outer surface of the central core, and a portion of the surface of the main magnet.

[0050] The loudspeaker may include a cylindrical support surrounding a central core and located within a gap, and a coil may be wound around the cylindrical support, meaning it may be integral with the cylindrical support to move together with it. The cylindrical support is connected to a radiator to move the radiator in response to movement of the coil along a movement orientation.

[0051] In one embodiment, the cylindrical support is located within the additional gap, or it is located within both the gap and the additional gap, and the additional coil can be wound around the cylindrical support, that is, it can be integral with the cylindrical support to move together with the cylindrical support. In this case, the coil and the additional coil move in the same direction along the same movement orientation.

[0052] In another embodiment, the loudspeaker includes an additional active radiator movable along a longitudinal axis to generate sound waves and opposite to the active radiator; the loudspeaker may include an additional cylindrical support surrounding a central core in an additional gap, and an additional coil may be wound around the cylindrical support, i.e., it may be integral with the additional cylindrical support for movement together with the additional cylindrical support. In this case, the coil and the additional coil move in the same and / or opposite directions along the same movement orientation.

[0053] In one example, the central core includes a cylindrical bore. The cylindrical bore may extend between a first end and a second end of the central core. Specifically, the cylindrical bore may extend along a longitudinal axis between an inlet and an outlet located at the second end and the first end of the central core, respectively. The central core may have cylindrical symmetry about the longitudinal axis.

[0054] In one example, the loudspeaker includes a power cable for connecting a power supply unit (i.e., an amplifier acting as a power supply unit) to a coil. Specifically, a cylindrical aperture may define a channel for guiding the power cable from the inlet to the outlet of the cylindrical aperture.

[0055] In one example, the loudspeaker may include a light diffuser, i.e., a dome configured to diffuse light. Preferably, the diffuser is located at the exit of the cylindrical aperture. The light diffuser may protrude toward the active radiator, that is, it may be configured to diffuse light toward the active radiator.

[0056] The loudspeaker may include a dustproof dome. In one embodiment, the light diffuser may be a dustproof dome, that is, the dustproof dome is configured to diffuse light. In another embodiment, the light diffuser may be configured to diffuse light toward the dustproof dome, wherein the dustproof dome is at least partially permeable to light. Thus, the light diffuser and the dustproof dome may be one or the same, or the light diffuser and the dustproof dome may be different parts of the loudspeaker. The active radiator may be at least partially permeable to light.

[0057] The loudspeaker may include a light source configured to emit (i.e., generate) light, preferably located at the entrance of a cylindrical aperture. The loudspeaker may also include a light guide configured to connect the light source to a light diffuser. Thus, the light generated by the light source is diffused toward an active radiator. The light source, light diffuser, and light guide can constitute an illumination system.

[0058] The speaker may include an electronic card, which preferably includes a control unit for driving the speaker (i.e., the coil). A light source may be connected to the electronic card. The control unit can be programmed to drive the light source.

[0059] Therefore, the holes are filled with power cables and light guides.

[0060] Note that the lighting system just described can be applied to any type of speaker, including those with cylindrical holes.

[0061] Therefore, this disclosure also provides a loudspeaker comprising: an active radiator movable along a longitudinal axis to generate sound waves; and a ferromagnetic circuit comprising a central core and an outer core, the central core extending along the longitudinal axis from a first end near the active radiator to a second end away from the active radiator, the outer core being located outside the central core, surrounding the longitudinal axis, and separated from the first end of the central core to define a longitudinally extending gap. The loudspeaker (i.e., the ferromagnetic circuit) includes a magnetic field generator, such as a main coil or a main magnet, configured to generate a main magnetic flux that circulates in the ferromagnetic circuit to pass through the gap in a passing direction. The field generator may be located in the central core or the outer core. The loudspeaker includes a movable element (e.g., a movable magnet or coil) located in the gap, the movable element being coaxial with the longitudinal axis and movable along a movement orientation parallel to the longitudinal axis to (directly or indirectly) move the active radiator. In this configuration, the central core includes a cylindrical aperture extending along a longitudinal axis between an inlet and an outlet located at a second end and a first end of the central core, respectively. The central core may have cylindrical symmetry about the longitudinal axis. The loudspeaker includes an illumination system. The illumination system may include a diffuser configured to diffuse light. The diffuser may have a dome shape. Preferably, the diffuser is located at the outlet of the cylindrical aperture. The diffuser may protrude toward the active radiator, that is, it may be configured to diffuse light toward the active radiator.

[0062] The loudspeaker may include a dustproof dome (configured to keep dust inside the loudspeaker and outside). A light diffuser may protrude toward the dustproof dome to diffuse light toward the dome. In particular, the dustproof dome is at least partially permeable to light.

[0063] The loudspeaker (i.e., the lighting system) may include a light source (e.g., one or more LEDs) configured to emit light (i.e., generate light). Preferably, the light source is located at the entrance of a cylindrical aperture. The loudspeaker (i.e., the lighting system) may include a light guide configured to connect the light source to a light diffuser. In this way, the light generated by the light source is diffused toward an active radiator.

[0064] The speaker may include an electronic card, which preferably includes a control unit for driving the speaker (i.e., the coil). A light source may be connected to or mounted on the electronic card. The control unit can be programmed to drive (i.e., control) the light source.

[0065] The control unit can control the light source in response to the operating conditions of the speaker; for example, the control unit can drive the light source to turn it on and / or off in response to a speaker malfunction. Therefore, the lighting system can function as a diagnostic indicator regarding the operation of the speaker. For example, the control unit can be programmed to drive the light source in response to an electrical signal used to power the coil; that is, it can be programmed to drive the light source based on the sound produced by the speaker.

[0066] In one example, the loudspeaker is part of a lighting system; for instance, the lighting system can be used to provide visual evidence indicating which of the multiple loudspeakers is emitting sound.

[0067] Preferably, the polarization of the primary magnet and the secondary magnet are aligned with respect to the longitudinal direction. When an additional secondary magnet is present, its polarization is also aligned with the polarization of the primary magnet (and therefore also with the polarization of the secondary magnet) along the longitudinal orientation. In other words, the primary magnet and the secondary magnet (and the additional secondary magnet, when present) each have a north pole and a south pole aligned longitudinally in the same direction.

[0068] Preferably, the longitudinal range of the coil is smaller than the longitudinal range of the gap, meaning the coil is completely located within the gap. In other words, the ratio between the longitudinal range of the gap and the longitudinal range of the coil is greater than 1, i.e., the gap and coil constitute a suspension configuration system. In this configuration, the greater the ratio between the ranges is than 1, the more pronounced the advantages derived from the present invention become.

[0069] When present, the longitudinal range of the additional coil can be smaller than the longitudinal range of the additional gap, that is, the additional coil can be completely located within the additional gap.

[0070] This disclosure also provides a method for transmitting sound.

[0071] The method includes the step of providing an active radiator that can move along a longitudinal axis to generate sound waves.

[0072] The method includes the step of providing a ferromagnetic circuit. The ferromagnetic circuit can be manufactured according to one or more features described herein. Preferably, the ferromagnetic circuit includes a central core extending along a longitudinal axis from a first end near the active radiator to a second end away from the active radiator. Preferably, the ferromagnetic circuit includes an outer core located outside the central core, surrounding the longitudinal axis and separated from the first end of the central core to define a longitudinally extending gap. Preferably, the ferromagnetic circuit includes a ring-shaped main magnet inserted into the outer core.

[0073] Preferably, the main magnet forms an interruption in the outer core. The main magnet has longitudinally oriented polarization.

[0074] As a substitute for the main magnet, a coil can exist.

[0075] The method includes the step of providing a movable element located within the gap and coaxial with the longitudinal axis. The movable element may be a magnet, or more preferably a coil.

[0076] The method includes the step of generating a main magnetic flux via a main magnet, which circulates in a ferromagnetic loop to pass through the gap in the passing direction.

[0077] The method includes the step of moving a coil (or magnet) along a movement orientation parallel to the longitudinal axis in response to the generated magnetic flux to move the active radiator.

[0078] The method includes the step of generating a secondary magnetic flux that passes through a gap in the passing direction and closes itself outside the ferromagnetic loop, such that the density of the total flux passing through the gap is greater than the density of the primary magnetic flux.

[0079] Specifically, the secondary magnetic flux is self-closed outside the ferromagnetic loop and passes through the central core in the opposite direction to the primary magnetic flux, resulting in a total flux density through the gap that is greater than the density of the primary magnetic flux. Simultaneously, the flux density through the central core is less than the density of the primary magnetic flux.

[0080] The secondary magnetic flux can be generated by a secondary magnet aligned with the longitudinal axis and located at a first end of the central core. In other words, the method may include the step of providing a secondary magnet aligned with the longitudinal axis and located at a first end of the central core. Preferably, the secondary magnet has longitudinally oriented polarization.

[0081] Preferably, the main magnet and the auxiliary magnet are not aligned longitudinally.

[0082] The secondary magnet can contact the first end of the central core directly or through a region with high magnetic permeability.

[0083] The method may include the step of simultaneously magnetizing a main magnet inserted into the outer core and a secondary magnet located at the first end of the central core.

[0084] In one example, the outer core is separated from the central core to define an additional gap that extends longitudinally and is aligned with the gap, and the main magnetic flux passes through the additional gap in the additional passing direction.

[0085] The method may include the step of providing an additional coil located in an additional gap and coaxial with the longitudinal axis. The method may include the step of moving the additional coil along a movement orientation parallel to the longitudinal axis in response to the generated magnetic flux. The method may include the step of generating an additional secondary magnetic flux that passes through the additional gap in an additional passing direction and is self-closing outside the ferromagnetic loop, such that the density of the total flux passing through the additional gap is greater than the density of the primary magnetic flux. Specifically, the additional secondary magnetic flux is self-closing outside the ferromagnetic loop and passes through the central core in a direction opposite to the direction of the primary magnetic flux, such that the density of the total flux passing through the additional gap is greater than the density of the primary magnetic flux. The density of the flux passing through the central core is less than the density of the primary magnetic flux.

[0086] For example, the method may include the step of providing an additional sub-magnet aligned with the longitudinal axis and located at a second end of the central core. In other words, the additional sub-magnetic flux is generated by the additional sub-magnet. Preferably, the additional sub-magnet has longitudinally oriented polarization. The additional sub-magnet and the sub-magnet may be longitudinally aligned. The main magnet may be longitudinally misaligned with the additional sub-magnet and the sub-magnet.

[0087] In one example of this method, the longitudinal range of the coil is smaller than the longitudinal range of the gap. Attached Figure Description

[0088] This feature and other features will become more apparent from the following description of a preferred embodiment shown by way of non-limiting example in the accompanying drawings, wherein:

[0089] - Figure 1A and Figure 2A A cross-section of a loudspeaker 1 according to one or more aspects of this disclosure is shown;

[0090] - Figure 1B and Figure 2B A cross-section of a loudspeaker 1 according to the prior art is shown;

[0091] - Figure 3 A loudspeaker 1 is shown according to one or more aspects of this disclosure;

[0092] - Figure 4 An exploded view of a loudspeaker 1 according to one or more aspects of this disclosure is shown;

[0093] - Figure 5A and Figure 5B A loudspeaker 1 is schematically shown according to one or more aspects of this disclosure;

[0094] - Figure 6A and Figure 6B A cross-section of a loudspeaker 1 according to one or more aspects of the present disclosure is shown, the loudspeaker 1 including a lighting system;

[0095] - Figures 6C to 6E A cross-section of a loudspeaker 1 according to one or more aspects of the present disclosure is shown, wherein the radiators are in different positions relative to the longitudinal axis;

[0096] - Figure 7A A simulation of the magnetic flux circulating in a loudspeaker 1 according to one or more aspects of this disclosure is shown. Figure 7B A simulation of the magnetic flux circulating in a prior art loudspeaker is shown;

[0097] - Figure 8A and Figure 8B The schematic diagram illustrates the direction of magnetic flux in a loudspeaker 1 according to one or more aspects of this disclosure;

[0098] - Figure 9 A cross-section of a loudspeaker 1 according to one or more aspects of this disclosure is shown. Detailed Implementation

[0099] The number 1 in the attached diagram represents a speaker.

[0100] The loudspeaker 1 includes an active radiator 30 that can move along the longitudinal axis X to generate sound waves.

[0101] The loudspeaker 1 includes a ferromagnetic circuit. The ferromagnetic circuit includes a central core 21 that extends along a longitudinal axis X from a first end 21A near the active radiator 30 to a second end 21B away from the active radiator 30. For example, the central core 21 may be made of iron.

[0102] The ferromagnetic circuit includes an outer core 22 located outside the central core 21 and surrounding the longitudinal axis X. For example, the outer core 22 may be made of iron. The outer core 22 includes an upper portion 22A and a lower portion 22B that are longitudinally aligned with each other. The upper portion 22A is separated from a first end of the central core 21 to define a longitudinally extending gap T.

[0103] The ferromagnetic circuit includes a ring-shaped main magnet 23 that is longitudinally inserted into the outer core 22 between the upper part 22A and the lower part 22B.

[0104] In one embodiment, the lower portion 22B is in direct contact with the central core 21 at the second end portion 21B; for example, the lower portion 22B may be defined by a lower portion extending away from the longitudinal axis X of the second end portion 21B. In this case, the gap T is longitudinally defined by the surface of the upper portion 22A of the outer core 22 facing each other and a portion of the inner surface of the central core 21.

[0105] The main magnet 23 also separates from the central core 21.

[0106] The main magnet 23 generates a main magnetic flux that circulates in the ferromagnetic loop and passes through the gap T in the passing direction V. The main magnet 23 includes a north pole N and a south pole S oriented longitudinally relative to each other. The north pole N can contact the upper part 22A of the outer core 22, and the south pole S can contact the lower part 22B of the outer core 22, or vice versa. That is, the north pole N can contact the lower part 22B of the outer core 22, and the south pole S can contact the upper part 22A of the outer core 22.

[0107] The loudspeaker 1 includes a coil 40 located in the gap T, coaxial with the longitudinal axis X, and movable along a movement orientation M parallel to the longitudinal axis X.

[0108] Preferably, the longitudinal extent of the coil 40 is smaller than the longitudinal extent of the gap T, meaning that the coil 40 is completely located within the gap T. In particular, the longitudinal extent of the coil 40 is smaller than the longitudinal extent of the upper portion 22A of the outer core 22.

[0109] The loudspeaker 1 includes a cylindrical support 60 surrounding a central core 21 and located within a gap T. A coil 40 is wound around the cylindrical support 60, and the cylindrical support 60 moves together with the coil 40 along a movement orientation M. The cylindrical support 60 is connected to an active radiator 30 so that the radiator 30 moves in response to movement of the coil 40.

[0110] The loudspeaker 1 includes a frame 70, and the radiator 30 is fixed to the frame 70 via a suspension edge 31. The loudspeaker 1 includes a dustproof dome 32 fixed to the radiator 30.

[0111] The speaker 1 includes a guiding system. In the example shown, the guiding system is a center position adjustment element 33, which is connected to the cylindrical support 60 and configured to keep the cylindrical support 60 (and thus the coil 40) centered in the gap T during movement.

[0112] The center position adjustment element 33 can be connected to the fixed structure via the support ring 24.

[0113] In examples not shown, the guidance system may be manufactured based on the content disclosed in the applicant’s patent document 102022000026061, which is incorporated herein by reference.

[0114] The loudspeaker 1 includes a secondary magnet 50 located at the first end 21A of the central core 21 and aligned with the longitudinal axis X. The secondary magnet 50 is in direct contact with the first end 21A of the central core 21.

[0115] The secondary magnet 50 is configured to generate a secondary magnetic flux that passes through the gap T in the through direction V and closes itself outside the ferromagnetic loop.

[0116] The polarization of the main magnet 23 and the polarization of the auxiliary magnet 50 are consistent with the longitudinal orientation. That is, both the main magnet 23 and the auxiliary magnet 50 have a north pole (N) and a south pole (S) with longitudinal orientation in the same direction.

[0117] The main magnet 23, the auxiliary magnet 50, the center core 21 and the outer core 22 define the fixed structure of the loudspeaker 1, while the coil 40, the cylindrical support 60 and the radiator 30 define the movable working unit.

[0118] In one embodiment, the lower portion 22B is separated from the second end portion 21B of the central core 21 to define a longitudinally extending additional gap T'. In this case, the additional gap T' is longitudinally defined by the surfaces of the lower portion 22B of the outer core 22 facing each other and a portion of the inner surface of the central core 21.

[0119] Therefore, the magnetic flux generated by the main magnet 23 also passes through the additional gap in the additional passing direction. The loudspeaker 1 may include an additional coil 40' located within the additional gap T', coaxial with the longitudinal axis X, and movable along an additional movement orientation M' parallel to the longitudinal axis X and preferably coinciding with the movement orientation M of the coil 40. The longitudinal extent of the additional coil 40' may be smaller than the longitudinal extent of the additional gap T', meaning that the additional coil 40' is entirely located within the additional gap T'. In particular, the longitudinal extent of the additional coil 40' may be smaller than the longitudinal extent of the lower portion 22B of the outer core 22.

[0120] exist Figure 5A In the embodiment shown only as an example, the cylindrical support 60 extends longitudinally to the additional gap T', and the additional coil 40' is wound around the cylindrical support 60 to move integrally with the cylindrical support and the coil 40; therefore, in this case, the orientation and direction of movement are consistent.

[0121] exist Figure 5BIn another embodiment, illustrated only by way of example, the loudspeaker 1 includes an additional cylindrical support 60', which positions the core 21 and is located within an additional gap T'. An additional coil 40' is wound around the additional cylindrical support 60', so that the additional cylindrical support 60' and the additional coil 40' move as an integral part along an additional movement orientation M'; in this case, the additional cylindrical support 60' can be connected to an additional active radiator so that the additional active radiator moves in response to the movement of the additional coil 40'. In this case, preferably, the movement orientation M of the coil 40 and the movement orientation M' of the additional coil 40' are aligned, but the directions of movement can be the same or opposite. The additional radiator can be secured to the frame 70 by an additional overhang, and the loudspeaker 1 can include an additional dustproof dome secured to the additional radiator. The loudspeaker 1 can then include an additional center position adjustment element connected to the additional cylindrical support 60' and configured to keep the additional cylindrical support 60' (and thus the additional coil 40') centered in the additional gap T' during movement. The loudspeaker 1 may include an auxiliary magnet 50' located at the second end 21B of the central core 21 and aligned with the longitudinal axis X. The auxiliary magnet 50' is in direct contact with the second end 21B of the central core 21.

[0122] The auxiliary magnet 50' is configured to generate an auxiliary magnetic flux that passes through the auxiliary gap T' in the auxiliary passing direction V and closes itself outside the ferromagnetic loop.

[0123] The polarization of the main magnet 23, the polarization of the secondary magnet 50, and the polarization of the auxiliary magnet 50' are consistent with the longitudinal orientation. That is, the main magnet 23, the secondary magnet 50, and the auxiliary magnet 50' all have a north pole (N) and a south pole (S) with the same longitudinal orientation.

[0124] The central core 21 may include a cylindrical aperture F. The cylindrical aperture extends along the longitudinal axis X between an inlet and an outlet located at a second end 21B and a first end 21A of the central core 21, respectively. The cylindrical aperture F may define a channel that guides the power cable 80 of the coil 40 (and any additional coil 40', if present) from the inlet to the outlet of the cylindrical aperture F.

[0125] exist Figure 6A and Figure 6BThe image illustrates, by way of example, a speaker 1 including a lighting system. The lighting system includes a light diffuser 81 having a dome shape and located at the exit of a cylindrical aperture F to diffuse light toward a dustproof dome 32, wherein the dustproof dome is partially permeable to light. The lighting system includes a light source 82 that generates light. The speaker 1 may include an electronic card 83 including a control unit programmed to drive the speaker 1. The light source 82 may be located on the electronic card 83 and controlled by the control unit. The light source 82 is located at the entrance of the cylindrical aperture F. The lighting system includes a light guide 84 configured to connect the light source 82 to the light diffuser 81.

[0126] The electronic card 83 may include a memory, preferably accessible to a control unit of the electronic card 83. A control unit external to the speaker 1 may also access the memory. The memory may contain information representing the speaker 1. This information may be contained in encrypted form. This information may include a serial number (identifying the speaker 1) and / or a batch number (identifying multiple speakers including the speaker 1) and / or the production facility that manufactured the speaker 1 and / or other information. This information may include multiple electromechanical parameters associated with the speaker 1. For example, the electromechanical parameters may describe typical characteristics or specifications of the speaker 1 (in numerical, tabular, or matrix form). For instance, the information may include movable mass values, and / or resonant frequency values, and / or variations in the force factor as a function of coil position, and / or inductance as a function of frequency and coil position, and / or other characteristics.

[0127] The information contained in the memory can be accessed by an external control unit, for example, to control the function of speaker 1.

[0128] In one example, the electronic card 83 includes multiple conductive tracks 85. The conductive tracks 85 can be configured to transmit electrical signals (i.e., signals to be converted into audio signals) and / or power supplies. The conductive tracks 85 can be configured to deliver power supplies to, for example, a light source and / or a memory.

[0129] The electronic card 83 includes a connector 86 for receiving power from a power supply unit, which is an amplifier that acts as a power supply unit.

[0130] Figure 6C , Figure 6D and Figure 6E The operating sequence of the speaker 1 is shown. As the coil 40 moves along the movement orientation (i.e., along the longitudinal axis X), the radiator 30, which is (indirectly) connected to the coil 40, also moves along the longitudinal axis X.

[0131] Figure 7A and Figure 7BPatterns of magnetic flux in a loudspeaker 1 according to the present invention and a loudspeaker 1 according to the prior art are shown respectively.

Claims

1. A loudspeaker (1), comprising: - An active radiator (30) that can move along the longitudinal axis (X) to generate sound waves; - A ferromagnetic circuit, which includes: A central core (21) extends along the longitudinal axis (X) from a first end (21A) near the active radiator (30) to a second end (21B) away from the active radiator (30); An outer core (22), located outside the central core (21), surrounds the longitudinal axis (X) and is separated from the first end (21A) of the central core (21) to define a longitudinally extending gap (T). A main magnet (23), having a ring shape and being inserted into the outer core (22) with longitudinally oriented polarization, generates a main magnetic flux that circulates in the ferromagnetic loop to pass through the gap (T) in the passing direction (V). - A coil (40), located in the gap (T), coaxial with the longitudinal axis (X) and movable along a movement orientation (M) parallel to the longitudinal axis (X) to move the active radiator (30). The speaker is characterized in that it includes a secondary magnet (50) aligned with the longitudinal axis (X) and located at the first end (21A) of the central core (21) to generate a secondary magnetic flux, which passes through the gap (T) in the passing direction (V) and closes itself outside the ferromagnetic circuit.

2. The loudspeaker (1) according to claim 1, wherein the secondary magnet (50) is in direct contact with the first end (21A) of the central core (21) or through a region having high permeability.

3. The loudspeaker (1) according to claim 1 or 2, wherein the outer core (22) is further separated from the second end (21B) of the central core (21) to define an additional gap (T') extending longitudinally and aligned with the gap (T), the main magnetic flux passing through the additional gap (T') in the additional passing direction, the loudspeaker (1) comprising: An additional secondary magnet (50'), aligned with the longitudinal axis (X) and located at the second end (21B) of the central core (21), generates an additional secondary magnetic flux that passes through the additional gap (T') in the additional through direction and closes itself outside the ferromagnetic loop. - An additional coil (40') is located in the additional gap (T'), coaxial with the longitudinal axis (X) and movable along an additional movement orientation (M') parallel to the longitudinal axis (X).

4. The loudspeaker (1) according to any one of the preceding claims, wherein the central core (21) includes a cylindrical hole (F) extending along the longitudinal axis (X) between an inlet and an outlet located at the second end (21B) and the first end (21A) of the central core (21), respectively, and the central core (21) is cylindrically symmetrical about the longitudinal axis (X).

5. The loudspeaker (1) according to claim 4, comprising a power cable (80) configured to connect an amplifier to the coil (40), wherein the cylindrical aperture (F) defines a passage for the power cable (80) from the inlet of the cylindrical aperture (F) to the outlet.

6. The loudspeaker (1) according to claim 4 or 5, comprising: A light diffuser (81) is located at the outlet of the cylindrical aperture (F) and protrudes toward the active radiator (30); A light source (82) is located at the entrance of the cylindrical aperture (F) and is configured to produce light; A light guide (84) is configured to connect the light source (82) to the light diffuser (81) so as to diffuse the light generated by the light source (82) toward the active radiator (30).

7. The loudspeaker (1) according to any one of the preceding claims, wherein the polarization of the main magnet (23) and the polarization of the secondary magnet (50) are consistent with the longitudinal orientation.

8. The loudspeaker (1) according to any one of the preceding claims, wherein the longitudinal extent of the coil (40) is smaller than the longitudinal extent of the gap (T).

9. The loudspeaker (1) according to any one of the preceding claims, wherein the outer core (22) comprises an upper portion (22A) and a lower portion (22B) longitudinally aligned with each other, the main magnet (23) being located between the upper portion (22A) and the lower portion (22B) along an orientation parallel to the longitudinal axis (X), the upper portion (22A) being annular and having an inner surface extending around the longitudinal axis (X) and facing the longitudinal axis (X).

10. The loudspeaker (1) according to claim 9, wherein the area S of the inner surface of the upper portion (22A) of the outer core (22) is... tp The area S of the radially extending surface of the central core (21) pp The ratio between them is less than or equal to 1.

6.

11. The loudspeaker (1) according to claim 9 or 10, wherein the height H of the inner surface of the upper portion (22A) of the outer core (22), measured longitudinally, is... pp The height H of the main magnet (23) m The ratio between them is less than or equal to 1.

7.

12. The loudspeaker (1) according to any one of claims 9 to 11, wherein the height H of the inner surface of the upper portion (22A) of the outer core (22), measured longitudinally, is... pp The height H of the coil (40) vc The ratio between them is different from 1.

13. The loudspeaker (1) according to any one of claims 9 to 12, wherein: - The coil (40) extends longitudinally between a first end near the radiator (30) and a second end opposite the first end. The coil (40) is configured to move within the gap (T) such that the first end moves between a maximum point of movement of the radiator (30) away from the central core (21) and a minimum point of movement of the radiator (30) toward the central core (21), and wherein, during movement between the maximum point and the minimum point, the first end (or the second end) of the coil (40) passes through a balance point. - The height H of the inner surface of the upper part (22A) of the outer core (22) pp The distance X between the equilibrium point and the maximum point max The ratio between them is less than or equal to 1.

6.

14. The loudspeaker (1) according to any one of the preceding claims, comprising a frame (70) and a sill (31), wherein the radiator (30) is fixed to the frame (70) via the sill (31), wherein the diameter D of the sill (31) is... d The diameter D of the main magnet (23) m The ratio between them is less than or equal to 1.

13.

15. A method for transmitting sound, comprising the following steps: - Provide an active radiator (30) that can move along the longitudinal axis (X) to generate sound waves; - Provides a ferromagnetic circuit, which includes: A central core (21) extends along the longitudinal axis (X) from a first end (21A) near the active radiator (30) to a second end (21B) away from the active radiator (30); An outer core (22), located outside the central core (21), surrounds the longitudinal axis (X) and is separated from the first end (21A) of the central core (21) to define a longitudinally extending gap (T). The main magnet (23), which has a ring shape and is inserted into the outer core (22) with longitudinally oriented polarization; - Provide a coil (40) located in the gap (T) and coaxial with the longitudinal axis (X); - A main magnetic flux is generated via the main magnet (23), which circulates in the ferromagnetic circuit to pass through the gap (T) in the passing direction (V); - In response to the generated magnetic flux, the coil (40) is moved along a movement orientation (M) parallel to the longitudinal axis (X) to move the active radiator (30). The method is characterized by the step of generating a secondary magnetic flux, which passes through the gap (T) in the passing direction (V) and closes itself outside the ferromagnetic loop, such that the density of the total flux passing through the gap (T) is greater than the density of the primary magnetic flux.

16. The method of claim 15, further comprising the step of providing a secondary magnet (50) aligned with the longitudinal axis (X) and located at the first end (21A) of the central core (21).

17. The method according to claim 16, wherein the secondary magnet (50) contacts the first end (21A) of the central core (21) directly or through a region having high permeability.

18. The method according to claim 16 or 17, comprising the step of simultaneously magnetizing the main magnet (23) inserted in the outer core (22) and the auxiliary magnet (50) located at the first end (21A) of the central core (21).

19. The method according to any one of claims 15 to 18, wherein the outer core (22) is separated from the central core (21) to define an additional gap (T') extending longitudinally and aligned with the gap (T), and the main magnetic flux passes through the additional gap (T') in the additional passing direction, the method comprising the steps of: - Provide an additional coil (40') located in the additional gap (T') and coaxial with the longitudinal axis (X); - In response to the generated magnetic flux, the additional coil (40') is moved along an additional movement orientation (M') parallel to the longitudinal axis (X). - An additional secondary magnetic flux is generated, which passes through the additional gap (T') in the additional passing direction and closes itself outside the ferromagnetic loop, such that the density of the total flux passing through the additional gap (T') is greater than the density of the primary magnetic flux.

20. The method of claim 19, further comprising the step of providing an additional sub-magnet (50') aligned with the longitudinal axis (X) and located at the second end (21B) of the central core (21).

21. The method according to any one of claims 15 to 20, wherein the longitudinal extent of the coil (40) is smaller than the longitudinal extent of the gap (T).

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