TW483008B - Magnet assembly - Google Patents

Abstract

A transducer comprises a magnet assembly comprising a magnet 1, magnetically permeable inner 3 and outer pole tips 5 and a voice coil 7 mounted in a gap between the pole tips. Either or both pole tips is electrically conductive in a plane substantially orthogonal to the axis of the voice coil in a region extending into the body of the pole tips from the edge of the pole tips adjoining the gap.

Description

Called 008 A7 B7 V. Description of the Invention (Printed by the Consumer Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs. This invention is about a magnet assembly, especially a magnet assembly for an actuator such as a speaker transducer. Access An axially symmetric permanent magnet assembly using a tubular coil that drives an actuator is required to generate a magnetic flux from a permanent magnet or an electromagnet focused in the coil area. This can produce a high magnetic flux density and has Helps improve overall efficiency. Following the existing design, focusing is usually done with steel magnetic pole tips, which can be increased to the effective magnetic permeability of the space seen by the wire coil, and therefore the effective inductance of the coil. When increasing the AC frequency The secondary effect occurs. This is the generation of eddy currents in the magnetic pole tips, which can be used to isolate the coils of the magnetic pole tips, thereby effectively reducing the magnetic permeability coefficient. T See the device shown in Figure 1 to illustrate this effect. This view A permanent magnet 3 is sandwiched between the first magnetic pole piece 5 and the second magnetic pole piece 7. The first magnetic pole 5 is a horse disc form having an outer periphery forming an inner magnetic pole tip 9. The second The pole β = horse form 'has an outer magnetic pole tip ". The inner and outer magnetic pole tips can be defined by ::-the coil 15 can be moved one space 13. The view shown is a broken one's positive magnet assembly system 'Circumferentially symmetrical about the axis 17. Therefore, the coil is a collar which can be provided in the ring-like shape interval 13. Figure 2 shows the magnetic field lines generated by the magnet. When the current passes through the coil, the line is on the axis The direction of movement. 丨-Force! The force used to make the coil from the magnetic flux density 3 and the current density. Extension, cloud, and more sound ya / gate can only provide ... degree J to the coil, and therefore the force, including High-line long film circle -------- ^ --------- ^ C Please read the precautions on the back before filling in this page) -4- x 297 public reply) 008

5. Description of the invention (2) The inductance decreases at high frequencies. If you want to know the magnetic flux associated with the dolphin flow flowing into the coil due to the increased coil inductance, if you = imitate and conceive this electric cutting field, then the magnetic field looks like the gas shown in Figure 3: Winding. Of vertical lines. The wild "" member is not correct about the% axis. The magnetic field lines are all hooked and no magnetic field lines are missing. The constrainable = receiving boundary is to terminate the mathematical model to ensure that—yes = when immersed in the magnet assembly, the magnetic flux distribution is shown in the figure. There are two effects of controlling the coil inductance. presence. The first effect when magnetic lines of force pass through the steel is to increase the magnetic flux measure because its magnetic permeability increases in air. When the frequency increases, the second effect caused by the mud can be completely controlled. According to this effect, a current can flow into the steel through the magnetic field lines of the steel because it is an electrical conductor (although not a very good conductor). However, when the frequency of the current passing through the coil is increased, the difficulty of increasing the A c magnetic flux to penetrate the steel is affected by the eddy current. The depth of penetration is called the skin depth. The skin depth (δ) of the conductor is expressed by the following formula: Pass through set of dense material -------- order -------- line »〈Read the precautions on the back before filling in this page ) Printed by the Consumer Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs 2 V μσω where μ is the relative magnetic permeability coefficient σ is the electrical conductivity coefficient angular frequency (2 π frequency) -5 This paper size applies the Chinese National Standard (CNS) A4 specification (21 〇X 297 mm) 483008 Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs A7 B7 V. Description of the invention (3) When the frequency is increased, the skin depth is reduced, and the magnetic flux can penetrate to a car. At high frequencies, such as 10,000 Hz, the penetration is quite small (about 0.6 mm at 10 kHz). For steel, Figure 6 shows the skin depth as a function of frequency. Existing techniques to reduce inductance are to use this skin depth by borrowing a copper foil over the pole pieces. This technique is only effective at frequencies when the skin depth of copper is approximately the thickness of copper foil. But increasing this foil can reduce the existing air gap, and the DC magnetic flux density will decrease. In this way, there is a major alternating use between reducing inductance and reducing magnetic flux density. Therefore, the copper foil shield is only partially successful. However, it can be understood that at 10 kHz (see Figure 7) the magnetic field lines do not penetrate deep into the steel. JP-32〇1797 illustrates an example of this technology. In the patent de19637847 describing the use of two copper rings on the outer magnetic pole piece, the configuration is similar to the moon. However, the reduction in inductance in this configuration is not entirely satisfactory. According to the present invention, a magnet assembly is provided. The inner and outer magnetic pole tips define a gap therebetween for a device, a voice coil in a predetermined axis direction, and the magnetic pole tips are magnetically permeable. At least one of the magnetic pole tips is substantially orthogonal. It is conductive in a plane in the predetermined axis direction, that is, extends from one side of the adjacent gap magnetic pole tip into the magnetic pole tip entity in a region. Preferably, the gap is ring-shaped. Inductance can constitute an important or even significant part of the impedance of a conventional speaker coil at a frequency of about 10 kHz or higher. Because this inductance can contribute to the --------------------- order --------- line (please read the precautions on the back before filling this page) -6-

Called 3008 A7 B7 Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs. 5. Description of the invention (4 to impedance, so that the impedance increases with frequency. When driven at a constant voltage, the current in the coil is therefore higher. It will decrease at frequency, and this current can also reduce the force on the coil. Therefore, the inductance will reduce the sound output at high frequencies. This effect is particularly serious for a large force to be generated. The large number of coil turns required can increase the inductance. The magnet assembly of the present invention can reduce the inductance at higher frequencies. The conductivity of the magnetic pole tip can protect the magnetic pole tip from being affected by a coil placed in the angular gap due to eddy current. Therefore, it can be reduced at this frequency. The coil inductance 'and the sound pressure intensity output of a speaker using such a magnet assembly will therefore be more consistent with the frequency. Preferably, the two magnetic pole tips can be conductive in this plane. The two magnetic pole tips can approach magnetic saturation. This also helps to slightly reduce the inductance of the coil, especially at low frequencies. Because of this, the magnetic pole tip has a magnetization of at least 75% of the saturation magnetization, preferably 9 0%. A pole tip can be formed by a slice stacked perpendicular to the plane. This slice is one of the magnet material and the south conductive material, and the mouth is steel and copper. This can be increased in The conductivity in this plane promotes eddy currents without unduly obstructing the flow of magnetic lines of force through the magnet assembly. Examples of replacements are made of steel with slots that extend from one edge of the adjoining angular gap into the magnetic pole tip. Iron is made into a copper shield and is added to the magnetic pole tip to fill the slot. It is understood that the eddy current caused by the magnetic field generated by a coil is essentially perpendicular to the coil axis in the coil plane. Although the high amount in the axial direction does not rule out this situation, it is more difficult to configure the amount of magnetic permeability coefficient --- r--I --------- I --- 丨 order ------- -Line C, please read the Zhuyin on the back? Matters before filling out this page)

Printed by the X Consumer Cooperative of the Intellectual Property Bureau of the Ministry of Economic Relief and the amount of configured conductivity is high in all directions. As an example, a molten mixture of steel and copper can form a magnetic pole tip. The magnet assembly of the present invention can increase the magnetic permeability visible to the coil. It is small and at the same time, the conductivity of the magnetic pole tip can be improved to promote eddy current. According to the normal training method, such as k-pressors and inductors, the purpose is to lighten the magnetic field lines into the core and reduce the effect of ’. This can prevent these magnetic field lines from penetrating into the core =. In this case, there is an inverse effect; coupling to the core does not require an increase in electricity. According to another aspect of the present invention, there is provided an electric power transmitter having one of the above-mentioned magnet assembly and a coil positioned in the gap. The coil may include a rectangular coil frame with a conductive wire wound around it. The present invention also provides a loudspeaker having the above-mentioned magnet assembly, a diaphragm and a voice coil fixedly fitted to the diaphragm and positioned in an angular gap in the magnet assembly. This speaker can be a distribution mode speaker as described in WO 97/09842.

A specific example of the present invention will now be described, and the drawings will be read by way of example, in which: Figure 1 shows a cross section through a conventional magnet assembly, Figure 2 shows the magnetic flux in the magnet assembly of Figure 1, and Figure 3 Shows the magnetic flux around a coil in the air. Figure 4 shows the magnetic flux around a coil in a conventional magnet assembly at 100 Hz. Figure 5 shows the magnetic flux around a coil in a conventional magnet assembly at 100 Hz. -8-This paper size is applicable to China National Standard (CNS) A4 (21〇X 297mm)

L. ------------------ ^. (Please read the notes on the back before filling out this page) 4. A7 A7 Copper printed by the Consumer Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs I. The magnetic field lines in the magnet assembly of the cover. V. Description of the invention (6) Figure 6 shows the frequency function twelve numbers & steel skin depth, Figure 7 shows the same degree of wood around the magnetic pole tip Figure 8 shows according to the present invention Japan H Shiming Ming Ai magnet assembly, Fig. 9 shows the magnetic field lines in a magnet assembly according to the present invention, and Fig. 10 shows the 乂 ^ and ^^ produced by the present invention at 100 Hz in the magnet assembly. The magnetic field lines of the coil I are shown in Figure 11. Figure 1 shows the magnetic field lines from the coil when H is large in the magnet assembly at 1000 edges according to the issue date. Figure 12 shows the magnetic field lines in the magnet assembly at 100 in accordance with the private day + 乂 ^ month. Magnetic lines of force from the coil at 0 Hz, FIG. 13 shows another example of the present invention, and FIG. 14 shows a further example of the present invention. As shown in FIG. 8, Yu Yuming ^ ^ y t λ months. Special Example I The magnet assembly includes two magnetic plates 5 1, a circular steel cup 7 and a steel disc 5 that surround one of the other magnetic pole pieces. One permanent magnet with 3 compartments and two pole pieces. It should be noted that everything shown in the figure is protruding from the center of the assembly, and the assembly is actually circular when viewed from above. The outer rim of the magnetic pole and the inner rim of the magnetic pole have an inner magnetic pole tip 9 and an outer magnetic pole tip 1 1. The female-magnetic pole tip is an overlapping layer of steel 19 and copper 21 to allow magnetic flux of 0 c to pass, from the outer magnetic pole piece 5 to the steel cup 7. A coil 15 is provided in an angular gap i 3 between the two magnetic pole pieces, and a metal wire 23 is wound on a bobbin 2 5. This coil is fixed to the membrane 27 of the speaker to drive the speaker. The magnet assembly is assembled by a resilient mount 2 $ -9 This paper size is applicable to China National Standard (CNS) A4 (210 X 297 mm) -I -------------- ------ Order --------- line (please read the precautions on the back before filling this page)

483008 V. Description of the invention (7) Placed on the film. This film may be a distribution pattern board, such as described in wo 98/09842. The magnetic circuit generated by the magnet assembly 3 is shown by the magnetic field lines in FIG. 9. By comparing this figure with Figure 2 showing the magnetic flux without superimposed magnetic pole tips, it can be understood that the superposition has only a minimal effect on the magnetic flux density generated by the permanent magnet 60. The thickness of the steel laminated sheet 21 is appropriately determined so that the laminated sheet operation approaches magnetic saturation 'and thus reduces its magnetic permeability while preventing eddy currents from circulating in the steel sheet. Because copper has a much higher electrical conductivity than steel (approximately more than 丨 0 times), the copper plate can be thinner (N10 == about 3 times thinner on the marking line) and is 2 times thinner according to this example. For added clarity, this thickness change is not shown in Fig. 8, although it can be shown in Figs. 10 '1 and 12. This ratio can be changed to accommodate the existing configuration 'and the reduction in required inductance. The close saturation of the steel pole tip 19 helps to slightly reduce the inductance of the coil 15 at low frequencies. Figure 10 shows the magnetic flux from the coil itself. The magnetic force and wire pass through the steel plate 1 9 ′ with a staggered copper plate having a very high conductivity to short-circuit the eddy current. This steel plate is thin enough to approximate skin depth at high frequencies, so that the frequency rise south 'eddy current cannot be formed and the staggering of copper can short-circuit it anyway. According to this example, the thickness of the steel plate is 0.2 mm, and the thickness of the copper plate is ο. Mm. Regarding the low inductance shown in Figure 12, even at 10 kHz, the magnetic flux field type can be lost in this way. To compare the possible improvements, the finite element (FE) model of the structure has been analyzed and Table 1 provides the results of the estimated inductance. -10- This paper size _ Chinese National Standard (CN ^^ grid (210 x 297)) --- Γ ------------------ Order ----- ---- Line (Please read the precautions on the back before filling out this page) Printed Invention Description (8)

The inside of the table is fine. The steel core of the standard assembly causes the large inductance at low frequencies to understand that the influence of a magnet assembly on the inductance. This effect _ the eddy current inside the steel will decrease when the frequency increases . In the case of the magnetic pole tip, a small reduction can be obtained at 100 Hz, the magnetic permeability of the magnetic pole tip can be reduced, and a significant improvement can be obtained at 10 kHz, and the inductance is actually less than that in the air coil. By selecting the thickness of the steel plate / copper plate < the correct ratio may reduce the inductance by 50% to 70%. Application superimposed on either magnetic pole and magnetic field or both. Figure 13 illustrates an alternative example in which the magnetic pole tips 9, 1 1 are not-laminated 'but a sintered mixture of steel and copper. + FIG. 14 illustrates a magnetic pole tip used in the alternative example. The magnetic pole tip system is formed with a slot 31 protruding in a direction perpendicular to the coil axis. The copper sheet 33 is then punched with a shaped iron on the opposite front side of the magnetic pole sheet to fill the slot. Although a specific example has been discussed, many alternative examples are possible. For example, without departing from the scope of the present invention, any suitable magnetic material can be used for the magnetic pole tip. The conductive sheet does not need to be copper, but other conductive materials, such as silver or Ming, can also be used. Any suitable shape of pole tip and pole piece can also be used. For example, a magnetic pole and steel example guideline -11 This paper size is applicable to the Zhongguanjia Standard (CNS) A4 specification ⑵0 x 297 public hair 483008 A7 B7_ V. Description of the invention (9) The piece can be a U-shaped piece with two terminals A magnetic pole tip on each end. An inner magnetic pole piece may be provided with a magnetic pole tip facing each magnetic pole tip of a U-shaped magnetic pole piece that spans two gaps; the two gaps are defined. The coil surrounds the inner pole piece and passes through two gaps. I -------------------- Order --------- line (Please read the notes on the back before filling this page) Intellectual Property Bureau of the Ministry of Economic Affairs Printed by Employee Consumer Cooperatives -12- This paper size applies to China National Standard (CNS) A4 (210 X 297 mm)

Claims (1)

483008 A8 B8 C8 D8 Scope of patent application Printed by the Consumer Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs 1. A magnet assembly, including: a magnet, and magnetically permeable inner and outer handsome pins, which are magnetic, defined between the inner and outer magnetic pole tips-gap ° and The magnet is connected to the voice coil, in which the door gap is used to be installed in a predetermined axis direction-at least-one magnetic pole tip is in a region that is substantially orthogonal to a pre-direction plane and is electrically conductive. Xiba @ A '，'-, ^, E domain protrudes from the side of the magnetic pole tip adjoining the gap into the entity of the magnetic pole tip. A little 2. As in the patent application Fan Yuan's magnet assembly, the gap is in the form of a circular path extending around the circumference of the inner magnetic pole tip. 3. If the scope of patent application is the first! Or item 2 of the magnet assembly, in which the two magnetic tips are conductive in this plane. 4. If the magnet assembly of the first or second item of the patent application scope, at least one of the magnetic pole tips includes a plurality of pieces of ferromagnetic material and high-conductivity material = pieces, and the pieces are substantially positioned in a direction orthogonal to the predetermined axis Within the flat. 5. For example, the magnet assembly of item 4 of the patent application, wherein the two magnetic pole tips contain a laminated piece of a ferromagnetic material and a high-conductivity material. 6. For the magnet assembly of item 1 or 2 of the scope of patent application, the magnetic pole tip is composed of a sintered mixture of steel and copper. 7. For example, the magnet assembly of item 1 or 2 of the patent application, wherein the magnetic pole tip is made of a magnetically permeable material, the material is formed with a slot, and the edge of the adjacent ring-like shape gap extends into the pole tip and A conductive shield is provided on the magnetic pole tip and fills the slot. -13- The size of this paper is applicable to Chinese National Standard (CNS) A4 (210 X 297 mm) extremely bread --------- fees --------- order ------- --Line i ^ w. (Please read the phonetic on the back? Matters before filling out this page) 483008 A8B8C8D8 Printing of clothing by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs. Or 2 pieces of the “combination”, wherein the magnetic pole tip 9. A transducer including a magnet: a magnetically permeable inner and outer magnetic pole tip, magnetically coupled to the magnet and defining a gap between the outer magnetic pole tip for pressing Installation in the predetermined axis direction—the vertical coil and the m-voice coil are installed in the gap according to the predetermined axis direction, in which at least one magnetic pole tip is in a region that is substantially orthogonal to the predetermined axis and is oriented in a plane. It can conduct electricity, and this area extends into the body of the magnetic pole tip by the magnetic side of Tian Bilian. 10. In the case of the transducer of item 9 of the patent application, the middle gap is in the form of a circular path extending around the pole tip. 11. The transducer of item 9 or 10 of the patent application park, in which the two magnetic poles can conduct electricity in the plane. 12. For the transducer of item 9 or 10 of the scope of patent application, at least one of the stones and the pole tip includes a stack of a ferromagnetic material and a high-conductivity material = the pieces are substantially orthogonal. In the plane of the predetermined axis direction, such as 13. The transducer of item 12 of the patent application range, wherein the two magnetic pole tips include a laminated sheet of a ferromagnetic material and a highly conductive material. 14. For a transducer in the scope of claims 9 or 10, the magnetic pole tip is composed of a sintered mixture of steel and copper. 15. If the transducer of the 9th or 10th scope of the patent application, the two magnetic pole tips are composed of a magnetically permeable material, the material is formed with a slot and is connected by an adjacent ring -14-This paper size applies to Chinese national standards (CNS) A4 specification (210 X 297 mm), -------- Order --------- line (Please read the note on the back? Matters before filling this page) 483008 A8 B8 C8 D8 6. The edge of one of the gaps in the scope of patent application extends into the magnetic pole tip and a conductive shield is provided on the magnetic pole tip and fills the slot. I6. The transducer of item 8 or 9 of the patent application, wherein the magnetic pole tip is substantially magnetically saturated. 17. If the coil of the patent application No. 9 in the energy conversion, the coil includes a ring-shaped frame with a conductive wire around it. 18. A speaker comprising a thin film and a transducer according to item 9 of the patent, wherein the voice coil is firmly attached to the thin film when an electrical signal is applied to the voice coil to excite the thin film. 19. The loudspeaker according to item 18 of the patent application, wherein the film is a flat plate capable of supporting many resonant bending wave modes in the plane of the sheet, and the transducer can excite the resonant bending wave to generate an acoustic output . (Please read the note on the back? Matters before filling out this page} --- I --- --Order --------- line. Printed by the Consumers ’Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs -15 paper size Applicable to China National Standard (CNS) A4 (210 X 297 mm)