A speaker system that obtains driving force from a ring magnet capable of magnetization in two directions.

Abstract

We provide speaker magnetic materials, magnetic circuits, and magnetized ring magnets that meet the essential requirements for wearable devices: small size and light weight; wide range of motion essential for ultra-low frequency reproduction; high linearity across the entire range of motion essential for sound field control; and low cost essential for consumer products. [Solution] In the speaker's magnetic circuit, the magnetic flux near the end face of the ring magnet is used, and ring magnets 201 and 202 that can only be magnetized in two directions are used. Depending on the application, one bidirectional magnetized ring magnet is used, or two types of bidirectional magnetized ring magnets are used as a pair on the outside and inside, or two or more bidirectional magnetized ring magnets of one type are used with spacers in between to form multiple layers, or two or more pairs of bidirectional magnetized ring magnets (one pair on the outside and one inside) are used with spacers in between to form multiple layers. A combination of bidirectional magnetized ring magnets that satisfies the required dimensions, mass, bass reproduction range, linearity, and cost is selected.

Description

Technical Field

[0001] Radial magnetization of ring magnet Small and lightweight, with a wide movable range necessary for excellent bass reproduction Ensuring high linearity throughout the entire movable range

Background Art

[0002] Verification and consideration in the development process of the present invention 1. Regarding cost reduction of the method using a ring magnet, When not using a yoke, the magnetic flux near the end face of the magnet significantly decreases, and the driving force of the voice coil significantly decreases. Therefore, when constructing a speaker without using a yoke due to the need to lighten the product, a magnet capable of omnidirectional magnetization is used to obtain at least a slightly high driving force. However, an omnidirectional magnetization ring magnet is costly. Although this is the market price and there is no universal basis, the cost increase factors are the cost increase in the sintering process of the material and the low demand. The price of a finished omnidirectional magnetization magnet is, as of April 2025, 5 to 8 times that of a normal two-directional magnetization. Since neodymium magnets are originally expensive, the cost of the magnet significantly affects the market price of consumer goods. Since the sintering process, which is an intermediate manufacturing process, is complex, the jigs required even in the prototype stage are expensive, and there are high barriers to remaking them many times. The present invention relates to a method of significantly reducing costs by using a two-directional magnetization ring magnet instead of omnidirectional magnetization.

Prior Art Documents

Patent Documents

[0003] Japanese Patent Application No. 2022-128811, relating to an earphone-type speaker using two ring magnets Japanese Patent Application No. 2023-4247: Earpiece speaker system that obtains driving force from a single ring magnet The text discusses the use of leakage flux in ring magnets, but there is no mention of cost reduction. [Overview of the project]

[0004] Terms defined in the claims shall also be used in the specification. [Problems that the invention aims to solve]

[0005] Task 1. The market demand for miniaturization, weight reduction, high performance, and cost reduction continues without end. [Means for solving the problem]

[0006] Method 1: Use a bidirectional magnetized ring magnet. Method 2 Depending on the application, Use a bidirectional magnetized ring magnet on either the outer or inner side, or both. Method 3 Depending on the application, Multiple bidirectional magnetized ring magnets for use on either the outer or inner side, or both. A composite structure with a spacer in between is used as a ring magnet. [Effects of the Invention]

[0007] Effect 1: Significant cost reduction

[0008] Effect 2: Due to its low cost, two-way magnetized ring magnets can be used to meet the required specifications. Multiple units can be used. As a result, diverse needs can be addressed at a low cost.

[0009] Effect 3: Due to its low cost, the range of motion of the voice coil necessary for ultra-low frequency reproduction and This allows for a wide range of design freedom within the high linearity range essential for sound field signal processing.

[0010] Effect 4: As a way to address a wide range of motion, The thickness of the ring magnet can be increased, and a voice coil with a narrow winding width can be selected. As a result, a highly efficient speaker can be realized despite having a wide movable range. Effect 5 Generally, rather than using an omnidirectional magnetized ring magnet that is high-performance but expensive, A speaker with significantly lower cost and equivalent or better performance can be realized.

Brief Explanation of Drawings

[0011] [Figure 1] Comparative explanatory drawing of magnetization states of the two-direction magnetized ring magnet and the omnidirectional magnetized ring magnet of the present invention [Figure 2] Explanatory drawing of how to use the two-direction magnetized ring magnet of the present invention [Figure 3] Explanatory drawing of magnetic flux distribution near the end face of the two-direction magnetized ring magnet of the present invention [Figure 4] Explanatory drawing of the relationship between the thickness of the spacer and the linearity of the magnetic flux density of the magnetic flux distribution near the end face of the two-direction magnetized ring magnet of the present invention

Best Mode for Carrying Out the Invention

[0012] An earphone-type, open-type subwoofer reproduction speaker system for wearable applications. In wearable applications, essential for cancellation of the closed loop including a microphone in the acoustic reproduction system A speaker system with a wide movable range and high linearity.

Industrial Applicability

[0013] Speakers for wearable applications in general.

Examples

[0014] Figure 1 is an explanatory drawing of the magnetization of the two-direction magnetized ring magnet of the present invention. It shows a comparison with an omnidirectional magnet.

[0015] Figure 1(a) shows a magnet made for bidirectional magnetization of a ring magnet being magnetized using an omnidirectional magnetizer. This diagram shows the magnetization process when magnetized. The ring represents the shape of the magnet, and the arrow indicates the strength of the magnetization in that direction. The arrow indicates the direction, and its length indicates the strength. The magnetization is strong in the direction in which magnetization is possible, but it weakens as the direction is misaligned. The driving force weakens because it is proportional to the total magnetic flux passing through the voice coil. Regardless of the variation in materials, The total magnetic flux of a bidirectionally magnetized ring magnet relative to an omnidirectionally magnetized ring magnet is: The calculation shows it to be approximately 61%, so the driving force is also 61%. Expressed in dB: The level is -4.2dB. However, the cost ratio, as of April 2025, is roughly 12% to 20%, meaning that even if the 39% driving force deficit is compensated for by increasing the thickness and number of magnets, the cost remains significantly lower. While the price varies depending on the conditions, when comparing devices with the same performance, Bidirectionally magnetized ring magnets are less expensive than omnidirectionally magnetized ring magnets. In speakers that require a wide range of motion, increasing the winding width of the voice coil is possible. The resistance and mass of the voice coil become large, and it cannot satisfy all the required performance, The number of magnets must be increased significantly. In other words, decisions must be made under trade-off conditions with respect to cost constraints. In the case of a bidirectional magnetized ring magnet, For products where the driving force is low but the voice coil's range of motion needs to be wide, Because the thickness and number of magnets can be adjusted, the winding width of the voice coil can be reduced, offering greater flexibility in meeting requirements, including cost.

[0016] Figure 1(b) shows the magnetization intensity of a real sample of a magnetized bidirectional magnetized magnet. The photograph shows a piece of paper placed on top of the magnet with iron powder sprinkled on top. The photograph shows that the iron powder is thicker in the vertical direction and thinner in the horizontal direction.

[0017] Figure 1(c) shows the magnetization of a magnet made for omnidirectional magnetization ring magnets when magnetized with an omnidirectional magnetizer. The ring represents the shape of the magnet, and the arrows indicate the magnetization strength in that direction. The arrows indicate direction, and their lengths indicate strength. Because magnetization is possible in all directions, the magnetization is uniformly strong regardless of the direction.

[0018] Figure 1(d) shows the magnetization intensity of a real sample of a magnetized omnidirectional magnetized magnet. The photograph shows a piece of paper placed on top of the magnet with iron powder sprinkled on top. The photograph shows that the iron powder is thick in all directions.

[0019] Figure 2 is an explanatory diagram of how to use the bidirectional magnetized ring magnet of this invention.

[0020] Figure 2(a) shows two types of ring magnets: large diameter and small diameter. 201 represents a large-diameter, and 202 represents a small-diameter, bidirectionally magnetized ring magnet.

[0021] Figure 2(b)203 shows a cross-section of a small-diameter bidirectional magnetized ring magnet.

[0022] Figure 2(c)204 shows a cross-section of a large-diameter bidirectional magnetized ring magnet.

[0023] Figure 2(d) shows cross-sections of the magnets when a pair of bidirectional magnetized ring magnets, one small and one large in diameter, are used. 207 is the gap between the two magnets. Figures 2(e)208 and 209 show cross-sections of the magnets when a set of small-diameter bidirectional magnetized ring magnets is used in two layers. 210 is a cross-section of the spacer between the two layers of magnets. Figures 2(f)211 and 212 show cross-sections of the magnets when two large-diameter bidirectional magnetized ring magnets are used in two layers. 214 is a cross-section of the spacer between the two layers of magnets. Figure 2(g) shows a cross-section of the magnets when two sets of bidirectional magnetized ring magnets (one large-diameter and one small-diameter) are used in a two-layer configuration. 213 and 214 are the large-diameter side, and 217 and 218 are the small-diameter side. This is a bidirectional magnetized ring magnet. 216 is between the two layers of large-diameter magnets, and 219 is between the two layers of small-diameter magnets. This is a cross-section of the spacer.

[0024] Figure 3 is an explanatory diagram of the magnetic flux density distribution near the end face of the bidirectional magnetized ring magnet of this invention. B is the axis of magnetic flux density intensity, indicating that the magnetic flux density increases to the right. The actual magnetic flux density distribution is complex, and explaining it accurately would only complicate the explanation of this proposal. The following explanation of the magnetic flux density distribution is a general trend. +D and -D indicate the distance from the center line of the magnet.

[0025] Figure 3(a) shows the magnetic flux density distribution near the end face of a bidirectionally magnetized ring magnet. 301 shows the cross-section of the magnet, 302 shows the line on which the voice coil is located, and 303 shows the magnetic flux density distribution along the line of the voice coil.

[0026] Figure 3(b) shows the case when using a large-diameter and a small-diameter bidirectional magnetized ring magnet. This shows the magnetic flux density distribution of the cap. 304 and 305 are cross-sections of the magnet, and 306 is the line where the voice coil is located. Figure 307 shows the magnetic flux density distribution along the voice coil.

[0027] Figure 3(c) shows the case where a pair of bidirectional magnetized ring magnets, one large and one small in diameter, are combined in two layers. This shows the magnetic flux density distribution of the cap. 308 and 309 are cross-sections of the magnets, and 310 is a cross-section of the spacer between the two magnets. 311 is the wire where the voice coil is located. 312 shows the magnetic flux density distribution along the voice coil line. The magnetic flux density weakens slightly at the spacer's position, The degree of this is determined by the relationship between the thickness of the magnet and the thickness of the spacer. How much can it be weakened? The relationship between the required range of motion and the allowable linearity is determined through design and actual measurements.

[0028] Figure 3(d) shows a set of two bidirectionally magnetized ring magnets, one on the outside and one on the inside. This shows the magnetic flux density distribution near the end face when using two sets with a spacer in between. 313 and 314 are cross-sections of the outer magnet. 315 is the cross-section of the spacer between the two magnets. 316 and 317 are cross-sections of the inner magnet. 318 is the cross-section of the spacer between the two magnets. 319 indicates the line on which the voice coil is located, and 320 indicates the magnetic flux density along the line of the voice coil. The magnetic flux density weakens slightly at the spacer's position, but the degree of this weakening is determined by the relationship between the magnet's thickness and the spacer's thickness. How much it can be weakened depends on the position of the spacer. The relationship between the required range of motion and the allowable linearity is determined through design and actual measurements.

[0029] Figure 4 shows the case where the bidirectional magnetized ring magnet of this invention has two layers. This diagram illustrates the difference in magnetic flux density distribution when the thickness of the spacer is changed. B is the axis of magnetic flux density intensity, indicating that the magnetic flux density increases to the right. +D and -D indicate the distance from the center line of the magnet.

[0030] Figure 4(a) shows an example where the spacer thickness is thin. This is applied when high linearity is required within the range of motion. 401 and 402 show the cross-section of the magnet, 403 shows the cross-section of the spacer, 404 shows the line on which the voice coil is located, and 405 shows the magnetic flux density distribution along the line of the voice coil.

[0031] Figure 4(b) shows an example where the spacer thickness is moderate. 405 and 406 show the cross-section of the magnet, 407 shows the cross-section of the spacer, 408 shows the line on which the voice coil is located, and 409 shows the magnetic flux density distribution along the line of the voice coil.

[0032] Figure 4(c) shows an example where the spacer thickness is greater. 410 and 411 show the cross-section of the magnet, 412 shows the cross-section of the spacer, 413 shows the line on which the voice coil is located, and 414 shows the magnetic flux density distribution along the line of the voice coil. Each spacer has a different thickness. You can select the magnets and spacers that have the lowest cost to obtain the required range of motion, linearity, and mass. The figure shows the trend of the magnetic flux density distribution qualitatively, rather than quantitatively.

[0033] Supplementary explanation of claim 1 The purpose of this proposal is to provide a wearable speaker system that meets the required performance at a low cost. By using low-cost magnets, This significantly expands the range of options available to meet the required specifications. The essence of this proposal is to make effective use of low-cost bidirectional magnetized ring magnets. When omnidirectional magnetization is applied to a bidirectionally magnetized ring magnet, the driving force is approximately 61% of that of an omnidirectionally magnetized magnet, under the same size and voice coil conditions. This is explained in Figure 1(a). Therefore, the thickness of the bidirectionally magnetized ring magnet should be approximately 61%. Increasing it will result in roughly the same driving force. In this case, the cost of ring magnets can be significantly reduced. If the voice coil has a range of motion of, for example, ±4mm, and high linearity is required, In omnidirectional magnetized ring magnets, increasing the winding width of the voice coil is chosen because the magnets themselves are expensive. In this case, as one design example, if the thickness of the ring magnet is 3 mm, The winding width of the voice coil is 11mm, including the movable range of ±4mm. The conversion efficiency is unconditionally reduced by 63% simply due to the copper loss equivalent to 8mm. Increasing the number of windings reduces the speaker's conversion efficiency. The increased mass of the voice coil lowers the conversion efficiency across the entire frequency range, and the increased mass particularly reduces the conversion efficiency at high frequencies. In other words, the options for achieving a large range of motion are extremely limited. In bidirectional magnetized ring magnets, because the magnets are inexpensive, it is possible to increase the thickness of the magnet rather than increasing the winding width of the voice coil. If the voice coil has a range of motion of ±4mm and high linearity is required, In one design example, if the voice coil winding width is 3mm, the simplest method is: The ring magnet will have a thickness of 11mm. The amount of magnets increases by approximately 3.7 times, but the cost is 20% to 12.5% ​​of 3.7 times, resulting in a cost reduction of 0.74 to 0.46 times. As explained in Figure 1(a), the driving force across the entire range of motion is 61%, The driving force is almost the same. Because the voice coil can be made lighter, it does not affect the ability to reproduce high frequencies. Overall, it appears that bidirectional magnetized ring magnets are advantageous for consumer products. When a wide range of motion is required, in practical designs, depending on the required degree of linearity, The methods shown in Figures 4(e), 4(f), and 4(g) can be selected, significantly reducing costs.

[0034] Supplementary explanation of claim 2 Claim 2 is a specific example of the application of Claim 1, in which there is one bidirectional magnetized ring magnet. The magnetic flux on the inside or near the outer surface of the ring magnet is used as the driving force. By using the magnetic flux near the outer surface of the ring magnet as the driving force for the entire frequency range, and the magnetic flux near the inner surface for ultra-high frequency reproduction, it can be used in a two-way speaker despite its simple structure.

[0035] Supplementary explanation of claim 3 Claim 3 is an example of an application of Claim 1, in which the bidirectional magnetized ring magnets are arranged in a set of two, one inner and one outer. The magnetic flux across the gap between a pair of ring magnets is used as the driving force. In addition, the magnetic flux near the outer surface of the outer ring magnet and the magnetic flux near the inner surface of the inner ring magnet can also be used as driving force. For example, the magnetic flux near the inner surface can be used for ultra-high frequency reproduction.

[0036] Supplementary explanation of claim 4 Claim 4 is an example of an application of Claim 1, wherein there is one type of bidirectional magnetized ring magnet, and a multilayer ring magnet is constructed using two or more of the same type of magnet. By balancing range of motion, linearity, and mass, it is possible to select the option that offers the best performance-to-cost ratio. The magnetic flux on the inside or near the outer surface of the ring magnet is used as the driving force. The magnetic flux near the outer surface of the ring magnet can be used as the driving force for the entire frequency range, while the magnetic flux near the inner surface can be used for ultra-high frequency reproduction.

[0037] Supplementary explanation of claim 5 Claim 5 is an example of an application of Claim 1, wherein there are two types of bidirectional magnetized ring magnets, and two or more sets of one set of the two types of magnets are used. It forms a multi-layered ring magnet. By balancing range of motion, linearity, and mass, it is possible to select the option that offers the best performance-to-cost ratio. The magnetic flux on the inside or near the outer surface of the ring magnet is used as the driving force. The magnetic flux near the surface of the inner ring magnet can be used for ultra-high frequency reproduction. [Explanation of symbols]

[0038] 201, 202 Large and small diameter, bidirectional magnetized ring magnets. 203 Cross-section of a small-diameter bidirectional magnetized ring magnet 204 Cross-section of a large-diameter bidirectional magnetized ring magnet 205, 206 Cross-sections of small and large diameter bidirectional magnetized ring magnets 207 The gap between the two magnets 208, 209 When using a set of small-diameter bidirectional magnetized ring magnets in two layers Cross-section of a magnet 210 Cross-section of the spacer between two layers of magnets 211, 212 When using a set of large-diameter bidirectional magnetized ring magnets in two layers Cross-section of a magnet 213 Cross-section of the spacer between two layers of magnets 214, 215 Cross-section of a large-diameter bidirectional magnetized ring magnet 216 Cross-section of the spacer between the two large-diameter magnets 217, 218 Cross-section of the bidirectional magnetized ring magnet on the smaller diameter side 219 Cross-section of the spacer between the two layers of small-diameter magnets

[0039] 301 Cross-section of a magnet 302 The wire where the voice coil is located 303 Magnetic flux density distribution along the line of a voice coil 304, 305 Cross-section of magnets 306 The wire where the voice coil is located 307 Magnetic flux density distribution along the voice coil line 308, 309 Cross-section of a magnet 310 Cross-section of the spacer between two magnets 311 The wire where the voice coil is located 312 Magnetic flux density distribution along the line of a voice coil 313, 314 Cross-section of the two outer layers of magnets 315 Cross-section of the spacer between two magnets 316, 317 Cross-section of the two inner layers of magnets 318 Cross-section of the spacer between two layers of magnets 319 The wire where the voice coil is located 320 Magnetic flux density distribution along the line of a voice coil

[0040] Cross-section of 401 and 402 two-layer magnets 403 Spacer 404 The wire where the voice coil is located 405 Magnetic flux density distribution along the voice coil line Cross-section of 405 and 406 two-layer magnets 407 Cross-section of the spacer 408 The wire where the voice coil is located 409 Magnetic flux density distribution along the voice coil line 410, 411 Cross-section of a two-layer magnet 412 Cross-section of the spacer 413 The wire where the voice coil is located 414 Magnetic flux density distribution along the voice coil line

Claims

1. Hereinafter, the terms used in the description of this invention are defined as follows: A ring magnet is a magnet with a square cross-section and a ring shape. In terms of magnetization properties, A ring magnet that can be magnetized in all radial directions is called an omnidirectional magnetized ring magnet. Even an omnidirectionally magnetized ring magnet that has already been magnetized in all directions will be considered an omnidirectionally magnetized ring magnet. A ring magnet that can magnetize in two directions on a plane, where magnetization is not possible in the entire radial direction. As a bidirectional magnetized ring magnet, A bidirectionally magnetized ring magnet, which is magnetized in all directions, is also referred to as a bidirectionally magnetized ring magnet. The above defines the terms used in the description of this proposal. The magnetic flux near one or both end faces of the inner and outer sides of a bidirectionally magnetized ring magnet Its first characteristic is that it is used to drive the voice coil. It is noteworthy that bidirectionally magnetized ring magnets have a significantly lower market price compared to omnidirectionally magnetized ring magnets. The first characteristic is a speaker having a magnetic circuit.

2. The terms shall be the same as those defined in Claim 1. One bidirectional magnetized ring magnet is placed, A second feature is that the magnetic flux near either the outer or inner end face, or both, of the bidirectional magnetized ring magnet is used as the driving force for the voice coil. A speaker having a magnetic circuit, which is an application of the first feature, and is a second feature.

3. The terms shall be the same as those defined in Claim 1. Two types of bidirectional magnetized ring magnets are arranged concentrically on the outer and inner sides. A third feature is that the magnetic flux in the magnetic gap between the outer and inner bidirectionally magnetized ring magnets is used as the driving force for the voice coil. A speaker having a magnetic circuit of the third feature, which is an application of the first feature.

4. The terms shall be the same as those defined in Claim 1. A single bidirectional magnetized ring magnet is arranged in two or more layers. The fourth feature is a structure in which two or more layers of bidirectional magnetized ring magnets are sandwiched with non-magnetic spacers that are thinner than the thickness of the magnets. A fifth feature is the use of the magnetic flux near the end faces of multiple layers of bidirectionally magnetized ring magnets in multiple sets as the driving force for the voice coil. A speaker having the magnetic circuits of the fourth and fifth features, which are an application of the first feature.

5. The terms shall be the same as those defined in Claim 1. Two types of bidirectional magnetized ring magnets are arranged concentrically on the outer and inner sides. The sixth feature is a structure in which two or more sets of bidirectional magnetized ring magnets are sandwiched between non-magnetic spacers thinner than the thickness of the magnets. Arranged in concentric circles in pairs of two types, A seventh feature is that the magnetic flux near the end faces of two sets of bidirectional magnetized ring magnets (two or more layers) is used as the driving force for the voice coil. A speaker having the magnetic circuits of the sixth and seventh features, which are an application of the first feature.

Images