Loudspeaker, an armature and a method

Abstract

A loudspeaker having a first magnet configured to output a first magnetic field in a first magnet gap, an elongate armature extending through the first magnet gap, a first coil configured to generate a magnetic flux in the armature, a first diaphragm, a first element configured to transfer force and/or movement from the armature to the first diaphragm, a base and a first and a second support element, the first support element connecting the armature to the base at a first longitudinal position at a first side of a predetermined portion along the length of the armature, and the second support element connecting the armature to the base at a second longitudinal position at a second, opposite side of the predetermined portion. The base may flex between a U-shape and an inverted U-shape and may thus provide force to move the diaphragm.

Claims

1. A loudspeaker comprising: a first magnet configured to output a first magnetic field in a first magnet gap, an elongate armature extending through the first magnet gap, a first coil configured to generate a magnetic flux in the armature, a first diaphragm, a first element configured to transfer force and/or movement from the armature to the first diaphragm, a base and a first and a second support elements, the first support element connecting the armature to the base at a first longitudinal position at a first side of a predetermined portion along the length of the armature, and the second support element connecting the armature to the base at a second longitudinal position at a second, opposite side of the predetermined portion the magnetic flux bending the armature at the predetermined portion, wherein force and/or movement is transferred, via the first element, from the armature to the first diaphragm.

2. The loudspeaker according to claim 1, wherein at least one of the first and second support elements are configured to rotatingly fix the armature to the base at the first and second longitudinal positions.

3. The loudspeaker according to claim 1, wherein the predetermined portion is configured to be moved in a direction toward or away from the base.

4. The loudspeaker according to claim 1, wherein the armature is configured to be movable in a direction toward or away from the base within the first magnet gap.

5. The loudspeaker according to claim 1, wherein the armature extends within the first coil and is configured to be movable in a direction toward or away from the base within the first coil.

6. The loudspeaker according to claim 1, wherein the armature extends within the first coil and is fixed to the first coil.

7. The loudspeaker according to claim 1, the loudspeaker comprising an additional element configured to transfer force and/or movement from the armature to the first diaphragm, the first and additional elements both being positioned either between the first and second support elements or outside the first and second support elements.

8. The loudspeaker according to claim 1, the loudspeaker further comprising a second magnet configured to output a second magnetic field in a second magnet gap, the armature extending through the second magnet gap.

9. The loudspeaker according to claim 1, the loudspeaker comprising an additional diaphragm and a second element configured to transfer force and/or movement from the armature to the second diaphragm.

10. The loudspeaker according to claim 1, wherein the armature has two extreme end portions and wherein a mass of a part of the armature between the first and second positions is no more than 10% higher or lower than a mass of parts of the armature between the end portions and the first and second positions, respectively.

11. The loudspeaker comprising a housing comprising a chamber, a sound output, a diaphragm forming part of an inner surface of the chamber and a motor assembly comprising an armature, a coil, and a magnet as well as at least a first and a second transfer element configured to transfer movement or force from the armature to the diaphragm, where the first transfer element is positioned closer to the output than the second transfer element, the motor assembly being configured to exert a larger displacement/force/torque on the diaphragm via the second transfer element than the first transfer element.

12. The loudspeaker according to claim 1, the loudspeaker comprising an additional element, the first and additional elements being positioned either between the first and second support elements or outside the first and second support elements and wherein the transfer step comprises also the additional element transferring force and/or movement from the armature to the first diaphragm.

13. The loudspeaker according to claim 1, the loudspeaker comprising an additional diaphragm and a second element, and wherein the transfer step comprises the second element transferring force and/or movement from the armature to the second diaphragm.

14. The loudspeaker according to claim 1, wherein the armature is configured to be movable in opposite directions on opposite sides of the first and second longitudinal positions.

15. A loudspeaker comprising: a first magnet configured to output a first magnetic field in a first magnet gap, an elongate armature extending through the first magnet gap, a first coil configured to generate a magnetic flux in the armature, a first diaphragm, a first element configured to transfer force and/or movement from the armature to the first diaphragm, a base, and a first and a second support elements, the first support element connecting the armature to the base at a first longitudinal position at a first side of a predetermined portion along the length of the armature, and the second support element connecting the armature to the base at a second longitudinal position at a second, opposite side of the predetermined portion, wherein the armature has two extreme end portions and wherein a mass of a part of the armature between the first and second positions is no more than 10% higher or lower than a mass of parts of the armature between the end portions and the first and second positions, respectively.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the following, preferred embodiments will be described with reference to the drawings, wherein:

(2) FIG. 1 illustrates main components of a first embodiment of the invention seen from the side,

(3) FIG. 2 illustrates a cross section of the embodiment of FIG. 1,

(4) FIG. 3 illustrates a second embodiment,

(5) FIG. 4 illustrates a third embodiment,

(6) FIG. 5 illustrates a dual diaphragm embodiment,

(7) FIG. 6 illustrates an armature suitable for use in the apparatus of the invention,

(8) FIG. 7 illustrates another armature suitable for use in the apparatus of the invention,

(9) FIG. 8 illustrates a further armature suitable for use in the apparatus of the invention,

(10) FIG. 9 illustrates a fourth embodiment,

(11) FIG. 10 illustrates a fifth embodiment,

(12) FIG. 11 illustrates flux return paths in a sixth embodiment,

(13) FIG. 12 illustrates a seventh embodiment,

(14) FIG. 13 illustrates an eighth embodiment,

(15) FIG. 14 illustrates a preferred supporting element for use in the loudspeaker of the invention,

(16) FIG. 15 illustrates a loudspeaker comprising a housing,

(17) FIGS. 16 and 17 illustrate embodiments with hinged, dual diaphragms,

(18) FIG. 18 illustrates an embodiment with a hinged, single diaphragm,

(19) FIG. 19 illustrates an embodiment with a hinged diaphragm divided along the direction of the armature, and

(20) FIG. 20 illustrates a diaphragm for use in the embodiment of FIG. 19.

DETAILED DESCRIPTION OF THE DRAWINGS

(21) In FIGS. 1 and 2, a first embodiment 10 is seen. Alike elements are denoted by the same numerals.

(22) The loudspeaker of the first embodiment 10 has a housing 20, a diaphragm 22, an armature 24, a base 26, a first magnet 30, a second magnet 32, a coil 40, a first support element or rod 50, a second support rod 52, and first and second elements 60, 62, respectively, for transferring movement/force from the armature 24 to the diaphragm 22.

(23) The magnets 30/32 and the coil 40 are fixed to the base 26 which is fixed to the housing 20. Alternatively, the magnets 30/32 and coil 40 may be fixed directly to the housing 20 which then acts as the base 26.

(24) The support rods 50/52 may be fixed to the base or the housing or other elements, such as the magnets, fixed to the base and/or housing.

(25) The housing 20 may have a further part (not illustrated) positioned above the diaphragm 22 so as to provide a front chamber as is well known within loudspeaker technology.

(26) Preferably, the chamber 21 defined by the housing 20 and diaphragm 22 may be completely sealed by the diaphragm 22 or an element (not illustrated) provided between the diaphragm 22 and housing 20, so as to ensure that sound arriving at the upper side of the diaphragm 22 is not allowed to travel into the chamber 21 between the housing 20 and the diaphragm 22.

(27) The armature is fixed to or controlled by the first and second elements 50/52 in relation to the base 26 but all other parts are allowed to move upwardly/downwardly in relation to the base 26. Thus, the ends 24′ and 24″ as well as the centre portion 24c of the armature positioned to the left of the first element 60, to the right of element 62 and between the elements 60/62, respectively, are not fixed in relation to the base 26.

(28) The operation of the loudspeaker of FIGS. 1 and 2 is as follows: when an electrical current is fed into coil 40, a magnetic flux is generated in the armature extending through the coil. A part of this flux will travel along a path defined by the armature 24, the base 26 and the magnets 30/32 and thus into the magnets 30/32, whereby the parts of the armature extending through the magnets will be brought to move up/down, depending on the magnetization direction of the magnets and the direction of the flux.

(29) Preferably, the magnetization directions of the magnets is selected so that both ends 24′ and 24″ will move up or down at the same time, so that the diaphragm is moved upwardly or downwardly—whereby sound is produced. This provides a piston-like movement of the diaphragm, which is a highly sought-for movement providing a more efficient sound production. In this situation, the fixing of the diaphragm to the housing should be sufficiently resilient all around the diaphragm to allow this piston-like movement.

(30) Naturally, the first and second elements 60/62 may be replaced by a single element, as will be described below. The use of multiple elements provides multiple points of driving of the diaphragm 22 and thus usually a better sound generation due to the more piston-like movement.

(31) In reaction to the upward/downward movement of the ends 24′ and 24″, the centre portion 24c will move in the opposite direction. Thus, the portion 24c will move upwardly/downwardly within the coil 40. Also, this will cause a bending of the armature in the centre portion 24c. As will be described further below, a hinge portion may be provided in the centre portion 24c so as to have a well defined position of this bending.

(32) A wide variety of set-ups utilizing this overall structure may be contemplated.

(33) In FIG. 3, two coils 40 and 42 are provided, compared to FIGS. 1 and 2. In addition, the support elements 50 and 52 have been moved closer to keep the overall dimensions of the loudspeaker small. Then, it is clear that the bending of the armature 24, between the support elements 50/52, may be quite large, whereby it may be desired to provide, between the support elements 50/52, a hinge portion 24n which may be a narrowing portion, a resilient portion or the like, which facilitates the bending without permanent damage to the armature.

(34) In FIG. 4, the relative positions of the magnets 30/32 and the support elements 50/52 have been altered. The same overall effect, however, is seen.

(35) In FIG. 12, another embodiment is seen wherein a single magnet 30 is provided along with two coils 40/42. A single coil 40 would suffice, as is seen in FIG. 13.

(36) In these embodiments, two return path elements 34 and 36 have been provided in order to provide a high permeability flux path from the coil, through the magnet and back. One return path element, i.e. the return path element 36, suffices, as it is positioned so as to return flux flowing in the armature and through the magnet 30 to the coil 40.

(37) The flux return path elements 34/36 may be elements of a high permeability positioned so as to guide flux from the armature to the base or any other element taking part in the flux path. The flux return path elements 34/36 preferably allow the armature to move towards/away from the base without contacting the flux return path elements 34/36 while preferably maintaining as small a distance to the armature in order to guide as much flux as possible.

(38) If the return path elements 34/36 are left out, the support elements 50/52 may aid in the flux return path, or constitute the return path

(39) In FIG. 5, a dual diaphragm set-up is seen wherein, in addition to the diaphragm 22, an additional diaphragm 22′ has been provided being driven by a third element 64 now provided at the centre portion 24c of the armature. It is seen that when the lower diaphragm 22 is moved downwardly, the upper diaphragm 22′ is moved upwardly.

(40) In FIG. 6, an armature type is seen which is oblong and at its ends has parts 25/25′ to which the first and second elements 60/62 may be fixed, such as by welding, gluing, soldering or the like.

(41) In FIG. 7, an alternative armature design is illustrated which again has the outer parts 25/25′ but now also has wings 25w, to which one or two centrally positioned third elements 64 (see FIG. 5) may be fastened. In addition, it is seen that the armature in FIG. 7 has an indentation at the central portion 24c. This indentation may act as a hinge portion if desired.

(42) In FIG. 8, yet another alternative of an armature may be seen which also has a central portion configured to act as a hinge portion.

(43) The armature of FIG. 8 is a stack construction which makes the parts 24/24″ stiffer. The stacked elements of the armature may be combined by gluing, welding, soldering or the like.

(44) FIG. 9 illustrates yet another embodiment of the most relevant parts of a loudspeaker. In this embodiment, the magnetic circuit has been altered in that the base 26 now extends through the coil 40, whereby the armature 24 only extends through the magnets 30/32.

(45) The armature 24 has been bent so as to make space for the coil 40, so that the overall height of the assembly is reduced.

(46) The magnetic circuit again comprises the armature, the base and the magnets and again, the electro-magnetic field is generated by the coil.

(47) Naturally, the base, in FIG. 9, could be replaced by another element configured to guide the electro-magnetic field from the coil to the magnets.

(48) In FIG. 10, the armature of FIG. 9 is illustrated in a permanently bent shape, which is suitable for positioning in e.g. the BTE part of a hearing aid.

(49) Naturally, the first and second elements 60/62 may be provided at the extreme ends of the armature 24, but it may be found easier to provide a single, third, element at the centre (top portion) of the armature 24.

(50) In general, it is noted that when the armature is bending, the interface between the armature and the support elements 50/52 may be stressed. This interface may be a fixed interface, where the armature is welded/soldered/glued to the support elements 50/52.

(51) It is noted that the support elements 50/52 may themselves be bendable, so that they (in FIG. 1) bend slightly outwardly, when the armature ends are forced downwardly as in configuration of FIG. 10.

(52) In addition, the armature preferably, a least the outer parts 24′/24″ thereof as well as the parts at the support elements 50/52, is stiff, so that the force exerted to the outer parts 24′/24″ is transferred also to the central part 24c in order to obtain the below advantage in a lower vibration of the loudspeaker.

(53) Then, the central part 24c may be made more bendable than other parts of the armature. A well-defined hinge portion or bending portion may be defined, such as by providing a part which is softer, more bendable, more resilient or the like. A simple manner of providing a hinge portion is to provide a portion with a thinner cross section, at least perpendicular to the direction of force exerting (in the plane of the figure). In other embodiments, the armature material may be altered, adapted, replaced, softened or the like in order to be more resilient at the desired position.

(54) In addition or alternatively, the interface between the support elements 50/52 and the armature may be resilient, such as by using a glue type which when after curing still has a resiliency.

(55) In the above embodiments, it has been sought that the magnets and coil(s) is/are symmetrically positioned around a centre portion of the armature. The same is the situation for the position of the support elements 50/52 and the first/second/third elements 60/62/64, as this makes the design easier.

(56) Naturally, such symmetry is not a requirement. The skilled person will know that displacing the first element 60 toward the centre of the armature 24 will make the overall movement (at a certain bending of the armature) lower but will increase the force/torque applied. Also, the positions of the magnets and the coil(s) will determine the electromagnetic field at the magnets and, together with the direction of magnetization and the strength of the magnets and, thus, the force exerted on to the armature. Then, the positions of the support elements 50/52 and the stiffness of the armature will determine the overall bending of the armature, where also the mass, resiliency etc. of the diaphragm could be taken into account. Thus, finally, the displacement of the diaphragm and thus the sound pressure provided may be determined.

(57) Thus, the skilled person will be able to derive also non-symmetric set-ups and determine (if tests are not sufficient) the output obtained.

(58) In addition to the above determination of the functioning of non-symmetric set-ups, the dynamics determined may also be used for calculating the vibration of loudspeakers of this type. When, in FIG. 1, the magnets pull the ends of the armature downwardly, the diaphragm, the first/second elements 60/62 and the ends 24′/24″ are moved downwardly, while the part 24c is moved upwardly. The resulting vibration may be determined, and it is seen that this depends on e.g. the armature thickness etc. but also on the positions of the support elements 50/52.

(59) In this respect, it may be desired to provide a heavier central portion 24c of the armature, such as by making it longer, thicker or the like, to counter the weight of the outer ends 24′/24″ and the diaphragm moving in the other direction. In a first approximation, it may be desired to ensure that the outer parts 24′ and 24″ weigh the same as the central part 24c, as they move in opposite directions. It may also be desired to add to the weight of the parts 24/24″ the weight of the diaphragm 22, as it moves with the parts 24/24″.

(60) In that respect, it may be desired to fasten the coil 40 to the central portion 24c and thus have the coil movable in relation to the base 26. This will increase the mass of the central portion, which may be desired, if the portion 24c is quite short.

(61) Naturally, the other set-ups may require that the diaphragm mass is added to the mass of the part 24c, if the diaphragm is driven by that part.

(62) In relation to FIG. 13, the use of flux return paths 34/36 may be utilized also, if the flux return paths 34/36 are fixed to the armature to again add mass to predetermined parts of the armature.

(63) In FIG. 11, the magnetic circuit is illustrated in another embodiment of a loudspeaker according to the invention. In this embodiment, a third magnet 31 is positioned at the central portion 24c of the armature, and where two coils 40/42 are used.

(64) It is seen that the coils 40/42 are driven in opposite directions so that the electromagnetic fields generated in the armature are directed oppositely to each other. The direction of magnetization of the magnets is the same.

(65) In this respect, it is seen that two magnetic circuits are formed: one magnetic circuit is fed by the coil 40 and comprises magnet 30 and the left parts of armature, base and magnet 31. The other magnetic circuit comprises the coil 42, magnet 32 and the right parts of armature, base and magnet 31. No large part of any magnetic field is transported between the left and right sides of the armature.

(66) This embodiment has a number of advantages. One advantage is that, as mentioned, no or very little magnetic flux is guided across the centre 24c of the armature 24, whereby the magnetic properties and the mechanical properties of this part of the armature may be de-coupled. There, thus, is no problem in using a reduced cross section to provide a well-defined bending or flexing position.

(67) Another advantage is that all magnets 30/31/32 are magnetized in the same direction, which benefits production of the loudspeaker.

(68) FIG. 14 illustrates a particularly preferred type of supporting element 25 which is made of a layer of a material, such as a metal, having a part 25b attachable to the housing 20. Alternatively, the element 25 may be fixed to a magnet if desired.

(69) The element 25, which may be made by blank cutting, stamping/punching, laser cutting or the like, has a central portion 25c having an opening 25a for the armature and connected to the remainder of the element 25 by two narrow parts 25n defining an axis 25x around which the central portion 25c may rotate while the remainder of the element 25 is fixed to the housing.

(70) FIG. 15 illustrates an embodiment wherein a motor assembly as that illustrated in e.g. FIGS. 1-13 is used having a diaphragm 22, an armature 24, drive pins or elements 60/62. The coil(s), magnet(s) and the base have been left out in order to not complicate the drawing.

(71) It is seen that the diaphragm 22 divides the interior of a housing 21 into two chambers 21′ and 21″ and that a sound opening or output 21A is provided from the chamber 21′.

(72) When the armature 24 forces the elements 60/62 and thus the diaphragm 22 upwardly, the air pressure in the chamber 21′ increases, and air is forced out of the output 21A. During this process, the air pressure in the chamber 21′ will be higher in the area B away from the output 21A than in the area A at the output 21A. Thus, a larger force or torque is required in the area B in order to move the diaphragm 22 the same distance, in order to obtain a high sound pressure output.

(73) Thus, the force or torque exerted by the armature 24 to the element 60 is higher than that exerted to the element 62. This may be obtained as described above by providing a stronger magnet, a larger flux in the armature from the coil and/or by positioning the element 60, on the armature, at a position where a smaller deflection takes place.

(74) An alternative, of course, is to provide two different motor assemblies or elements, one for driving each element 60 and 62, where the motor assemblies may be of any desired type, such as moving armature, moving coil or the like, where the assembly driving the element 60 may be stronger than the other one (stronger magnet, different coil or the like) and/or may be fed a higher current in order to provide the larger force/torque.

(75) In FIG. 16, an embodiment largely as that of FIG. 1 is seen. Some of the reference numerals have been left out for the sake of clarity, and the largest differences are the positions of the first and second elements 60/62 and the fact that the diaphragm is divided into two diaphragms 22 and 22′ separated by two hinge portions H, providing bending hinges along axes perpendicular to the plane of the drawing. Naturally, a single hinge H may be used, but the advantage of providing two hinges is that the portion of the diaphragm between the hinges H may be stationary, such as fixed to a portion of the housing.

(76) It is seen that the first and second elements 60/62 have different displacements or drive ratios and thus will drive the diaphragms 22/22′ differently.

(77) Clearly, different positions of the hinge portion(s) H and the first/second elements 60/62 in relation to the armature 24 will drive the diaphragms 22′/22″ differently, where the difference may be both the amplitude of the vibration/displacement and the torque or force with this driving is performed. Thus, different amounts of air may be displaced with the same overall frequency contents, as these are defined by the movement or vibration of the armature 24.

(78) The upper side (in the drawing) of the diaphragms 22′/22″ may define or take part in the defining of the same chamber of the loudspeaker, or two different chambers may be defined where the diaphragm 22′ takes part in the delimitation of only one chamber and the diaphragm 22″ in the part of only the other chamber. The chambers may be separated by a separating wall engaging the diaphragm portion between the hinges H.

(79) In FIG. 17, a corresponding set-up is illustrated where the first element 60 has been shifted into a position similar to that (mirrored) of the second element 62, but as the hinge portions H are not positioned directly around the centre of the set-up, the two diaphragms 22′/22″ are still driven differently.

(80) In FIG. 18, a single diaphragm 22 is illustrated driven by a first element 60 but again having a hinge portion H. Again, it is seen that the position of the hinge portion H and the first element 60 may define the amplitude and force/torque applied to the diaphragm 22.

(81) In FIG. 19, an embodiment is seen with, again, a first and a second element 60/62 and a diaphragm 22 with a hinge element H. The diaphragm 22 is illustrated in FIG. 20 and has been divided up along the longitudinal direction of the armature 24. The hinge portion H is provided, as in the embodiments of FIGS. 16-18, perpendicular thereto. Thus, the two resulting diaphragms 22′ and 22″ may be moved independently out of the plane of FIG. 20 and up/down in FIG. 19.

(82) Between the diaphragms 22′/22″, a resilient sealing material may be provided so as to prevent air or at least sound from moving from the lower side (in FIG. 19) of the diaphragms to the upper side thereof.

(83) It is seen that the positions of the hinge portion H and the first/second elements 60/62 again may provide different movements/vibrations of the two diaphragms 22′/22″. Also, as is described in relation to FIG. 16, the two diaphragms 22′/22″ may (above them in FIG. 19) delimit the same chamber or they may take part in the delimiting of different chambers, if a sound barrier is provided between the diaphragms 22′/22″ so as to divide the inner portion of a housing, in which the drive mechanism of FIG. 19 is positioned, into at least three chambers: one chamber above the diaphragm 22′, one chamber above the diaphragm 22″, and one or more chambers below the diaphragms 22′/22″.

(84) Clearly, the above embodiments are only examples of the inventions claimed. As mentioned, the symmetry desired is by no means a requirement.

(85) Also, more than two support elements may be used. Any number of support elements may be used, as the main operation is that when the armature on one side of the support element moves toward the diaphragm, it will move away therefrom on the other side. Providing three supporting elements, for example, this pattern will simply be repeated. Thus, the armature will move toward the diaphragm at more positions and more parts of the armature will move away from the diaphragm. Then, more positions are available for positioning magnets and coils, if this is desired. In this example, it may be preferred that the support elements engage the armature at equidistant positions. Alternatively, the bending properties of the armature may be varied in order to support a deformation with constant or invariate movement at the positions of the support elements.