Linear motor magnet assembly and loudspeaker unit

Abstract

To provide a linear motor magnet assembly that can improve a performance of a linear motor actuator system, and is used in a loudspeaker unit.SOLUTION: A linear motor magnet assembly 2 used in a loudspeaker unit 1, includes: a fixing base part actuator construction element 4; a film operation element 5 that has a linear motion shaft line A; a first assistance magnet element 7; and a second assistance magnet element 8. The first assistance magnet element 7 provides a first assistance space magnet field having a main shaft line arrayed with the linear motion shaft line A. The second assistance magnet element 8 is fixedly connected to the film operation element 5 of the linear motor magnet assembly 2, and has a second assistance space magnet field. The second assistance space magnet field is overlapped with the first assistance space magnet field, and is distributed substantially similarly the first assistance space magnet field over a first predetermined movement range of the linear motor magnet assembly 2.SELECTED DRAWING: Figure 2A

Description

[Technical Field]

[0001] The present invention relates to a linear motor magnet assembly for use in a loudspeaker unit, the linear motor magnet assembly comprising a fixed base actuator component and a membrane actuating element, the membrane actuating element having a linear axis of motion. [Background technology]

[0002] Such a linear motor magnet assembly is known, for example, from WO 2018 / 056814, which discloses a loudspeaker unit having a membrane and a number of drive units for driving the membrane. Summary of the Invention

[0003] The present invention seeks to provide a linear motor magnet assembly for use in a loudspeaker unit that can improve the performance of the linear motor actuator system.

[0004] According to the present invention, there is provided a linear motor magnet assembly as defined above, having a fixed base actuator component and a membrane actuation element, the membrane actuation element having a linear motion axis, a first auxiliary magnetic element and a second auxiliary magnetic element, the first auxiliary magnetic element providing a first auxiliary spatial magnetic field having a main axis aligned with the linear motion axis of the linear motor magnet assembly, and a second auxiliary magnetic element fixedly connected to the membrane actuation element of the linear motor magnet assembly and having a second auxiliary spatial magnetic field that overlaps with the first auxiliary spatial magnetic field and is oriented substantially similarly to the first auxiliary spatial magnetic field over a first predetermined range of motion of the linear motor magnet assembly.

[0005] The first auxiliary magnetic element and the second auxiliary magnetic element are arranged such that as the linear motor magnet assembly moves, a resultant force generated by the first auxiliary magnetic element and the second auxiliary magnetic element amplifies the movement of the motor. Thus, the present invention provides an improved, energy-efficient linear motion system by reducing the stiffness of the linear motor over its range of motion. This improvement effectively reduces the power required by the linear motor system to perform a complete motion. Further embodiments are described by the dependent claims and with reference to exemplary embodiments shown in the drawings.

[0006] The invention will be explained in more detail below with reference to the accompanying drawings. [Brief explanation of the drawings]

[0007] [Figure 1A] 3A to 3C are diagrams showing an example of a permanent magnet auxiliary structure in two operating situations according to the linear motor magnet assembly of the first embodiment of the present invention; [Figure 1B] 3A to 3C are diagrams showing an example of a permanent magnet auxiliary structure in two operating situations according to the linear motor magnet assembly of the first embodiment of the present invention; [Figure 2A] 10 is a cross-sectional view of a loudspeaker unit having two opposing membranes each driven by two linear motor magnet assemblies according to a further embodiment. [Figure 2B] 10 is a perspective view of a loudspeaker unit having two opposing membranes each driven by two linear motor magnet assemblies according to a further embodiment; FIG. [Figure 3] FIG. 10 is a cross-sectional view of a linear motor magnet assembly according to a further embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0008] The present invention relates to a linear motor magnet assembly (also referred to herein as actuator amplifier or permanent magnet assist device) comprising a combination of permanent magnets that use their magnetic fields to assist and amplify the motion generated by a linear motor actuator, and the application of this feature to counter non-linearities in the stiffness of the overall loudspeaker device by using a combination of a linear motor and a permanent magnet assist device.

[0009] It is noted that the present invention may be applied to various types of loudspeaker units 1, such as the examples described and disclosed in WO 2018 / 056814 and unpublished applications from the same applicant, PCT / NL2018 / 050263, PCT / EP2018 / 079509, PCT / EP2019 / 055831, and EP19162460.0. The linear motor magnet assembly 2 may be implemented according to any of the exemplary embodiments described herein.

[0010] Electrodynamic transducers generally include a linear motor, a membrane, and a support for the linear motor. Transducers for mid- and low-frequency response are typically mounted in an enclosure. Mounting the transducer in an enclosure (which may be, for example, sealed or bass-reflex) increases the total stiffness of the support that must be overcome by the linear motor. Electrodynamic transducer systems capable of providing low-frequency response (10 Hz to 200 Hz) in a sealed or bass-reflex enclosure typically have stiffness resulting from the support of the transducer itself as well as from the air compression within the enclosure. When the membrane needs to compress the air, the air-compression-induced stiffness increases; the higher the required compression, the higher the stiffness. As the air-induced stiffness increases, the support stiffness of the transducer itself must also increase to prevent undesired deformation of the support caused by the air-induced stiffness. As a result, linear motor actuators require increased power input to produce the desired air compression. Ideally, to create an electrodynamic transducer that experiences the least distortion caused by stiffness nonlinearities when placed in a sealed or bass-reflex enclosure, one seeks to achieve the lowest possible stiffness increase caused or required by enclosure effects. The transducer ideally behaves as if it were in free air.

[0011] The present invention, in various embodiments, provides an apparatus that uses a combination of at least two permanent magnets to improve the performance of a linear motor actuator system by reducing the stiffness over the full range of motion of the linear motor, effectively reducing the power required by the linear motor system to move over its range of motion.

[0012] 1A and 1B show an example of a portion of a linear motor magnet assembly 2 or permanent magnet auxiliary structure in two operating situations. This exemplary embodiment comprises axially magnetized magnets, with the second auxiliary magnetic element 8 being a ring-shaped magnet that moves around the first auxiliary magnetic element 7, which is a cylindrical magnet.

[0013] The present invention provides an improved linear motor magnet assembly for use in a loudspeaker unit that requires less power from the linear motor system to effect linear motor motion. The present invention therefore provides a cost-effective and power-efficient system that requires less structural modification to the system.

[0014] FIG. 2A shows a cross-sectional view and FIG. 2B shows a perspective view of an exemplary embodiment of a loudspeaker unit 1 of the present invention having two opposing membranes 3, each driven by two linear motor magnet assemblies 2, in which an embodiment of the present invention is implemented.

[0015] The linear motor magnet assembly 2 is adapted for use in, for example, a loudspeaker unit 1. The linear motor magnet assembly 2 comprises a fixed base actuator component 4 and a membrane actuated element 5. The fixed base actuator component 4 is connected to two axially aligned magnetic elements 7 and 7 which are part of the linear motor magnet assembly 2. * The material of the fixed base actuator component 4 is a non-magnetic material and includes two axially aligned magnetic elements 7, 7 * The membrane actuation element 5 is movable and has a linear motion axis A, i.e., the direction in which the membrane 3 moves up and down. Upon actuation, the membrane actuation element 5 moves the linear motor magnet assembly 2 connected to the membrane 3. Thus, the membrane 3 moves up and down depending on the actuation direction. The two opposing membranes 3 are separated by a predetermined distance. The linear motor magnet assembly 2 is connected to the first auxiliary magnetic element 7 (two axially aligned magnetic elements 7, 7 *The linear motor magnet assembly 2 further comprises a first auxiliary magnetic element 7 (one of the first auxiliary magnetic element 7 and the second auxiliary magnetic element 8). The first auxiliary magnetic element 7 provides a first auxiliary spatial magnetic field having a main axis aligned with the linear motion axis A of the linear motor magnet assembly 2. The second auxiliary magnetic element 8 is fixedly connected to the membrane actuating element 5 of the linear motor magnet assembly 2 and has a second auxiliary spatial magnetic field. The second auxiliary magnetic field overlaps with the first auxiliary spatial magnetic field and is oriented substantially similarly to the first auxiliary spatial magnetic field over a first predetermined range of motion E1 of the linear motor magnet assembly 2.

[0016] The inventive embodiment of the loudspeaker unit 1 has two opposing membranes 3 disposed on the upper and lower surfaces of the loudspeaker unit 1. While the loudspeaker unit 1 is shown in FIGS. 2A and 2B as a rectangular unit, it is not limited to this geometry. The base element of each of the membranes 3 is structurally connected to two linear motor magnet assemblies 2 at two diagonal ends of the membrane 3. As shown in FIG. 2B, the base element of the lower membrane 3 is structurally connected by two different linear motor magnet assemblies 2 disposed at both of the membrane's lower diagonal ends. Similarly, the base element of the upper membrane 3 is structurally connected by two different linear motor magnet assemblies 2 disposed at both of the membrane's upper diagonal ends. The effect of this combination of features is an increase in magnetic force (or a decrease in stiffness) in the direction of motion in a first predetermined range of motion; i.e., the first auxiliary magnetic element and the second auxiliary magnetic element help overcome support and air compression forces in the loudspeaker unit 1. It should be noted that the second auxiliary magnetic element 8 is attached to the membrane actuation element 5 using, for example, a holder body as shown in the cross-sectional view of Figure 2A. Note that a fixed connection does not necessarily imply a direct physical attachment of these two elements to each other.

[0017] In a further embodiment, the second auxiliary magnetic element 8 is positioned a first distance along the linear motion axis A from the membrane actuating element 5. Figure 1A shows an operating situation in which the second auxiliary magnetic element 8 is positioned at the center of the first auxiliary magnetic element 7 along the linear motion axis A. Furthermore, Figure 1B shows an operating situation in which the second auxiliary magnetic element 8 is positioned away from the center of the first auxiliary magnetic element 7 along the linear motion axis A.

[0018] A further embodiment of the present invention relates to a linear motor magnet assembly 2 in which the second auxiliary spatial magnetic field and the first auxiliary spatial magnetic field only partially overlap over a second predetermined range of motion E2 of the linear motor magnet assembly 2. This feature reduces the force in the direction of motion in the second predetermined range of motion E2. In the exemplary embodiment of Figures 1A and 1B, the first auxiliary magnetic element 7 has a finite dimension along the axis A, and the second predetermined range of motion E2 extends beyond the first predetermined range of motion E1.

[0019] According to yet another further embodiment of the present invention, a linear motor magnet assembly 2 is provided, wherein a first auxiliary magnetic element 7 is fixedly connected to a fixed base actuator component 4 of the linear motor magnet assembly 2. The fixed connection does not necessarily imply a direct attachment or structural connection of these two elements to each other. This may be, for example, a simple magnetic connection or a magnetic connection by levitation.

[0020] Yet another further embodiment of the present invention relates to a linear motor magnet assembly 2 comprising a membrane actuating element 5 and a support assembly 6 connected to a fixed base actuator component 4, the support assembly 6 being arranged to enable relative movement between the membrane actuating element 5 and the fixed base actuator component 4 along a linear motion axis A and to define a rest position of the membrane actuating element 5 (and a second auxiliary magnetic element 8 fixedly connected to the membrane actuating element 5) along the linear motion axis A.

[0021] The present invention, in various embodiments, further seeks to provide a linear motor magnet assembly for use in a loudspeaker unit, the purpose of which is to improve the performance of a linear motor actuator system by using a combination of at least two permanent magnets to reduce stiffness over the complete range of motion of the linear motor, effectively reducing the power required by the linear motor system to achieve the complete range of motion. Embodiments of the present invention also relate to a linear motor actuator amplifier (or permanent magnet assist device) comprising a combination of permanent magnets that use their magnetic fields to assist and amplify the motion generated by the linear motor actuator, and the application of this feature to counteract non-linearities in the stiffness of the complete system by using a combination of a linear motor and a permanent magnet assist device.

[0022] According to one embodiment, the present invention relates to a linear motor magnet assembly 2 in which the second auxiliary magnetic element 8 comprises a permanent magnetic material. Another embodiment of the present invention relates to a linear motor magnet assembly 2 in which the second auxiliary magnetic element 8 comprises an electromagnet. In such a system, the second auxiliary magnetic element 8 is electrically magnetized, for example, for a specific period of time. Similarly, a further embodiment of the present invention relates to a linear motor magnet assembly 2 in which the first auxiliary magnetic element 7 comprises a permanent magnetic material. Yet another further embodiment of the present invention relates to a linear motor magnet assembly 2 in which the first auxiliary magnetic element 7 comprises an electromagnet.

[0023] According to a further exemplary embodiment of the present invention, a linear motor magnet assembly 2 or motor assist unit is provided, the assist unit comprising at least two permanent magnets 7, 8. One magnet is attached to the moving part of a linear motor actuator system. The other of the at least two magnets 7, 8 is attached to the static part of the same aforementioned linear motor actuator system. The magnets 7, 8 are arranged such that as the linear motor actuator moves, the force generated by the auxiliary magnetic fields of the combined moving and stationary magnets 7, 8 amplifies the motor's movement. The structure of the permanent magnet assist unit determines the variation in resultant and reaction forces over the range of motion of the permanent magnet system, which counteracts the stiffness of the linear motor system. The structure and mutual element orientation of the present invention make it possible to provide a more energy-efficient linear motion system.

[0024] An exemplary embodiment relates to a permanent magnet structure that can be used in combination with a linear motor actuator system, the permanent magnet structure comprising at least two permanent magnets, one of the at least two permanent magnets attached to a moving portion of the linear motor actuator system and at least one permanent magnet attached to a stationary portion of the linear motor actuator system, the permanent magnets being arranged such that a combined magnetic field of the permanent magnets of the permanent magnet system counteracts increasing stiffness over a range of motion of the linear motor actuator system.

[0025] In a further embodiment, the permanent magnet structure and linear motor actuator system are provided in combination with a support that returns the moving part of the linear motor actuator to a static rest position, the support being caused by mechanical stiffness of the support device or by stiffness caused by air or fluid pressure.

[0026] The present invention also relates to a permanent magnet structure and linear motor actuator system applied to a loudspeaker unit, where the permanent magnet is on the membrane of the loudspeaker unit and stationary magnets are arranged above and below the membrane.

[0027] A further embodiment of the present invention relates to a linear motor magnet assembly 2 in which the first auxiliary magnetic element 7 is integrally formed with the fixed base actuator component 4. This configuration has the advantage that the linear motor magnet assembly has one less structural element (shared component), resulting in lower cost and easier manufacture. The first auxiliary magnetic element 7 comprises either a permanent magnetic material or an electromagnet material.

[0028] An exemplary embodiment of the present invention relates to a linear motor magnet assembly 2 in which the first auxiliary magnetic element 7 is a cylindrical (or rod) shaped, axially magnetized permanent magnet (with opposing poles 7a, 7b at its outer ends, as shown in the exemplary embodiment shown in FIGS. 1A and 1B). A further embodiment of the present invention relates to a linear motor magnet assembly 2 in which the second auxiliary magnetic element 8 is ring-shaped with axially aligned poles 8a, 8b, having a central opening larger than the maximum cross-sectional diameter of the first auxiliary magnetic element 7. This geometry allows the first auxiliary magnetic element 7 to be positioned at different operating positions within the second auxiliary magnetic element 8.

[0029] A further embodiment of the present invention relates to a linear motor magnet assembly 2 in which the first auxiliary magnetic element 7 has a predetermined shape and provides a predetermined first auxiliary spatial magnetic field profile over the range of motion of the linear motor magnet assembly 2. Yet another further embodiment of the present invention relates to a linear motor magnet assembly 2 in which the predetermined shape is a double (e.g., truncated) conical shape with a maximum diameter at the middle of the first auxiliary magnetic element 7. This shape can be implemented by having one of the magnets as a conical magnet, which shape generates a magnetic field of varying strength over the motion. Such a magnetic field allows for more efficient control of the relative movement of the second auxiliary magnetic element 8 with respect to the first auxiliary magnetic element 7, taking into account changes in magnetic field strength.

[0030] 3 shows a cross-sectional view of a linear motor magnet assembly according to a further embodiment of the present invention, comprising two magnetic bodies 7' facing each other to form a first auxiliary magnetic element, with a magnetic body 8' disposed therebetween to form a second auxiliary magnetic element. The two magnetic bodies may have the same type of magnetization, for example, both may be permanent magnets or both may be electromagnets. Alternatively, the two magnetic bodies 7' may be magnetized in different ways, for example, one of them may be a permanent magnet and the other an electromagnet.

[0031] The first auxiliary magnetic element and the second auxiliary magnetic element may have different sizes and shapes. For example, the first auxiliary magnetic element may be flat or disk-shaped. The second auxiliary magnetic element may be disk- or ring-shaped. Furthermore, the size of the first auxiliary magnetic element may be different from the size of the second auxiliary magnetic element. As mentioned above, a further embodiment of the present invention relates to a linear motor magnet assembly 2, in which the first auxiliary magnetic element 7 comprises two (e.g., permanent) (e.g., flat or disk-shaped) magnetic bodies 7 at a predetermined distance from each other along the linear motion axis A, and the second auxiliary magnetic element 8 comprises an axially magnetized (e.g., disk- or ring-shaped) magnetic body 8' disposed between the two magnetic bodies 7'. Due to the presence of the two magnetic bodies 7', the second auxiliary spatial magnetic field and the first auxiliary spatial magnetic field partially overlap over a second predetermined range of motion E2 of the linear motor magnet assembly 2 in a symmetrical direction. This feature will further reduce the force in the direction of movement in the second predetermined range of movement E2.

[0032] A further embodiment of the present invention is a linear motor magnet assembly 2 having two axially aligned magnetic elements 7, 7 with a main spatial magnetic field having a main axis aligned with the linear motion axis A of the linear motor magnet assembly 2. *For the linear motor magnet assembly 2 further comprising: the membrane actuation element 5 comprises a voice coil configured to generate a coil magnetic field that interacts with the main space magnetic field to move the voice coil along the linear motion axis A (i.e., to drive the membrane 3).

[0033] Another embodiment of the invention relates to a loudspeaker unit 1 comprising a membrane 3 and a linear motor magnet assembly 2, wherein a membrane actuating element 5 and a second auxiliary magnetic element 8 are fixedly connected to the membrane 3.

[0034] The present invention has been described with reference to some exemplary embodiments shown in the drawings. Modifications and alternative implementations of some parts or elements are possible and fall within the scope of protection defined in the appended claims.

Claims

1. A loudspeaker unit comprising: a membrane coupled to the sealed enclosure; and a linear motor assembly for driving a membrane along an axis of motion relative to said enclosure; The linear motor assembly includes: membrane actuation element, a first auxiliary stationary magnetic element and a second auxiliary stationary magnetic element disposed along the axis of motion, wherein the membrane actuating element is movably disposed between the first auxiliary stationary magnetic element and the second auxiliary stationary magnetic element; and a third auxiliary movable magnetic element coupled to the membrane actuation element; Including, the linear motor assembly is configured to apply a magnetic force to move the membrane along an axis of motion, resulting in a reduction in stiffness of the loudspeaker unit. Loudspeaker unit.

2. 10. A loudspeaker unit in accordance with claim 1, wherein the membrane-actuated element comprises a voice coil.

3. 3. A loudspeaker unit according to claim 1, wherein the first auxiliary magnetic element is cylindrical.

4. 4. The loudspeaker unit according to claim 1, wherein the movable third auxiliary magnetic element is ring-shaped.

5. 5. A loudspeaker unit according to claim 1, wherein the first auxiliary magnetic element is a permanent magnet.

6. 5. A loudspeaker unit according to claim 1, wherein the first auxiliary magnetic element is an electromagnet.

7. 7. A loudspeaker unit according to claim 1, wherein the second auxiliary magnetic element is a permanent magnet.

8. 8. A loudspeaker unit as claimed in any preceding claim, further comprising a second membrane coupled to the closed enclosure, the first and second membranes being located on opposite sides of the enclosure.

9. 9. A loudspeaker unit in accordance with claim 8, wherein said linear motor assembly is configured to cause said first membrane and said second membrane to move simultaneously inwardly and outwardly along an axis of motion relative to an enclosure.

10. A loudspeaker unit comprising: a membrane bonded to a sealed enclosure; a membrane actuation element that drives the membrane along the axis of motion; and A loudspeaker unit having a magnet assembly, The magnet assembly includes: a stationary first magnet; a second stationary magnet spaced apart from the first stationary magnet and positioned along the axis of motion, wherein the membrane actuation element is movably disposed between the first stationary magnet and the second stationary magnet; and a movable third magnet coupled to the membrane and the membrane actuation element; Including, the magnet assembly is configured to apply a magnetic force to move the membrane along an axis of motion, resulting in a reduction in stiffness of the loudspeaker unit. Loudspeaker unit.

11. 11. A loudspeaker unit in accordance with claim 10, wherein the membrane-actuated element comprises a voice coil.

12. A loudspeaker unit according to any one of claims 10 to 11, wherein the stationary first magnet is cylindrical.

13. 13. The loudspeaker unit according to claim 10, wherein the movable third magnet is ring-shaped.

14. A loudspeaker unit according to any one of claims 10 to 13, wherein the stationary first magnet is a permanent magnet.

15. A loudspeaker unit according to any one of claims 10 to 13, wherein the stationary first magnet is an electromagnet.

16. A loudspeaker unit according to any one of claims 10 to 15, wherein the second movable magnet is a permanent magnet.

17. 17. A loudspeaker unit as claimed in any one of claims 10 to 16, further comprising a second membrane coupled to the closed enclosure, the first membrane and second membrane being located on opposite sides of the enclosure.

18. 18. A loudspeaker unit in accordance with claim 17, wherein the loudspeaker unit is configured such that the first membrane and the second membrane are simultaneously moved inwardly and outwardly along an axis of motion relative to an enclosure.

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