Electromechanical transducers

Abstract

The electromechanical transducer comprises: a pair of magnets; a pair of yokes, each yoke being formed by overlapping a plurality of yoke parts at a flat plate-shaped portion to guide the magnetic flux generated by the magnets; an air-core coil to which an electrical signal is supplied; an armature configured to penetrate an internal space of a structural portion in which the magnets and the coils are integrally arranged on the inner side of the pair of yokes; and a pair of elastic members, each elastic member being engaged with the structural portion and the armature.

Description

Technical Field

[0001] The present invention relates to an electromechanical transducer that converts an electrical signal into mechanical vibration, and more particularly to an electromechanical transducer having a structure utilizing the restoring force of a spring engaged with an armature in a so-called balanced armature type structure. Background Art

[0002] In this type of electromechanical transducer, a spring is arranged between a structure having a yoke, a magnet, and a coil integrally arranged therein and an armature penetrating its internal space to form a driving part. When current flows in the coil, the armature is displaced within a certain range due to the balance between the magnetic force of the magnet acting on the armature and the restoring force of the spring, thereby causing the driving part to generate relative vibration between the armature and the structure. For example, an electromechanical transducer having two pairs of springs arranged between the structure and the armature (see Patent Document 1) and an electromechanical transducer having a pair of springs arranged between the structure and the armature (see Patent Document 2) are known.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2015-139041

[0006] Patent Document 2: Japanese Patent Application Publication No. 2018-186378 Summary of the invention

[0007] Problems to be solved by the invention

[0008] Furthermore, the yoke forming part of the structure is formed of a soft magnetic material and has the function of guiding the magnetic flux generated by the magnet. As for the soft magnetic material, as its characteristic, the saturation magnetic flux density is determined. When the saturation magnetic flux density is exceeded, the magnetic flux is saturated and becomes a peak state, and no longer plays the role of a yoke. Therefore, the cross-sectional area of ​​the yoke needs to be designed to be within the range that does not cause the magnetic flux to saturate.

[0009] The above-mentioned prior arts all have a structure in which the armature is clamped from both sides by two yokes via springs and then the yokes are joined to fix them. That is, in addition to guiding the magnetic flux (a function during use), the yokes in these prior arts also play a role in positioning the armature via springs and fixing the two yokes to complete the drive unit (a function during manufacturing).

[0010] Generally, when processing a plate to make a component, if the thickness of the plate becomes thicker, the minimum width of the punching and bending process will naturally become larger. Based on the effect during use, the yoke in the above-mentioned prior art needs to be made to a thickness that can ensure that the cross-sectional area of ​​the part through which the magnetic flux passes is of the desired size. However, for a plate of this thickness, if a design that implements bending processing is adopted in order to further play the role during manufacturing, the following problems will arise: depending on the shape of the part, the manufacturing will become difficult, or the size of the part to be bent will increase beyond the necessary size, resulting in an increase in the overall size of the electromechanical transducer.

[0011] Solutions for solving problems

[0012] The present invention has been made in view of the above problems, and an object of the present invention is to provide a technology for alleviating the difficulty in manufacturing components of an electromechanical transducer and miniaturizing the electromechanical transducer.

[0013] In order to solve the above problems, the present invention adopts the following electromechanical transducer. It should be noted that the words in the following brackets are just examples, explanations, specific expressions, etc., and the present invention is not limited thereto.

[0014] The electromechanical transducer of the present invention comprises: a pair of magnets; a pair of yokes for guiding the magnetic flux of the magnets, each yoke being formed by overlapping a plurality of yoke components at a flat plate-shaped portion; an air-core coil to which an electrical signal is supplied; an armature configured to penetrate the internal space of a structural portion formed by integrally configuring the magnets and the coils on the inner side of the pair of yokes; and a pair of elastic members, each elastic member being engaged with the structural portion and the armature.

[0015] In the electromechanical transducer of this scheme, each yoke is formed by overlapping a plurality of yoke parts having a flat plate-like portion, and the specified cross-sectional area that does not saturate the magnetic flux passing through the yoke is ensured by the sum of the thicknesses of the plurality of flat plate-like portions. Since such yoke parts are respectively formed of plates thinner than the yoke, when bending is performed to form other portions, it is easier to manufacture compared to the case where bending is performed on a plate of the same thickness as the yoke, and in addition, the protruding size due to the bending is suppressed to be small. Therefore, the electromechanical transducer according to this scheme can alleviate the difficulties in manufacturing and make the yoke that does not saturate the magnetic flux smaller, which can contribute to the miniaturization of the electromechanical transducer.

[0016] Preferably, in the above-mentioned electromechanical transducer, the yoke has a bent portion on any one of the yoke components, and the bent portion protrudes from both side surfaces of the yoke in a second direction orthogonal to a first direction as an overlapping direction of the yoke components, and from positions of symmetrical side surfaces, respectively, and bends in the first direction to extend out by a predetermined length. Furthermore, the paired yokes are fixed to each other at the end surfaces of the bent portions.

[0017] In the electromechanical transducer of this scheme, any one of the yoke components has a bent portion. The bent portion is formed by bending the plate forming the yoke component, but the plate is thinner than the yoke, so it is easier to bend it than a plate of the same thickness as the yoke, and the protruding size due to the bending is suppressed to be small. Therefore, according to the electromechanical transducer of this scheme, the difficulties in component manufacturing can be alleviated and the electromechanical transducer can be miniaturized.

[0018] More preferably, in the electromechanical transducer, each yoke has an engaging portion protruding from predetermined positions on both side surfaces of a yoke member arranged outside the structure in an arbitrary direction orthogonal to the first direction, and the elastic member engages with the engaging portion.

[0019] According to the electromechanical transducer of this solution, when the yoke is integrated as a part of the structural part, a portion for the elastic member to engage is provided on the yoke part arranged on the outside. Therefore, compared with the case where the portion is provided on the yoke part arranged on the inside of the structural part, the length of the elastic member can be made longer, and the predetermined displacement amount of the elastic member in the first direction can be ensured.

[0020] Effects of the Invention

[0021] As described above, according to the present invention, it is possible to alleviate the difficulty in manufacturing components of an electromechanical transducer and to miniaturize the electromechanical transducer. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a perspective view showing a driving unit of the electromechanical transducer according to the first embodiment.

[0023] Figure 2 It is a perspective view showing a yoke of the electromechanical transducer according to the first embodiment.

[0024] Figure 3 It is an exploded perspective view showing the driving unit of the electromechanical transducer according to the first embodiment.

[0025] Figure 4A It is a figure which demonstrates by comparing the 1st embodiment and a comparative example.

[0026] Figure 4B It is a figure which demonstrates by comparing the 1st embodiment and a comparative example.

[0027] Figure 5 It is a perspective view showing a driving unit of an electromechanical transducer according to a second embodiment.

[0028] Figure 6 It is a perspective view showing a yoke of an electromechanical transducer according to a second embodiment.

[0029] Figure 7 It is an exploded perspective view showing a driving unit of an electromechanical transducer according to a second embodiment.

[0030] Fig. 8A It is a figure which demonstrates the 2nd Embodiment by comparison with a comparative example.

[0031] Figure 8B It is a figure which demonstrates the 2nd Embodiment by comparison with a comparative example.

[0032] Fig. 9 It is a perspective view showing a driving unit of an electromechanical transducer according to a third embodiment.

[0033] Fig.10 It is a perspective view showing a side plate of an electromechanical transducer according to a third embodiment.

[0034] Fig.11 It is an exploded perspective view showing a driving unit of an electromechanical transducer according to a third embodiment.

[0035] Fig.12 It is a perspective view showing a driving unit of an electromechanical transducer according to a fourth embodiment.

[0036] Fig.13 It is a perspective view showing a side plate of an electromechanical transducer according to a fourth embodiment.

[0037] Fig.14 It is an exploded perspective view showing a driving unit of an electromechanical transducer according to a fourth embodiment. DETAILED DESCRIPTION

[0038] Hereinafter, the embodiments of the present invention will be described with reference to the accompanying drawings. It should be noted that the following embodiments are preferred examples, and the present invention is not limited to these examples. In addition, for the convenience of description, directions related to the configuration are sometimes represented as up, down, left, and right along the directions on the paper of each accompanying drawing.

[0039] [First embodiment]

[0040] Figure 1 1 is a perspective view showing a driving unit (driving unit 1 ) of the electromechanical transducer according to the first embodiment. The driving unit 1 is composed of a pair (two) of yokes 10 , two pairs (four) of magnets 20 , a coil 22 , an armature 25 , and two pairs (four) of springs 28 .

[0041] Each yoke 10 is composed of an outer yoke 11 forming an outer portion and an inner yoke 12 forming an inner portion, and is arranged up and down with the outer yoke 11 as the outer side. The coil 22 is fixed to the inner side and the center of the left and right directions of a pair of yokes 10 (more accurately, the inner yoke 12) arranged up and down. The magnets 20 are paired up and down, and two pairs of magnets 20 are fixed to the inner side and the left and right ends of a pair of yokes 10 (more accurately, the inner yoke 12). The yoke 10, magnet 20, and coil 22 arranged in this way constitute a structural part.

[0042] The armature 25 is arranged to penetrate the internal space of the structure. The springs 28 are arranged in pairs up and down, and the two pairs of springs 28 are arranged at the left and right ends between the structure (more precisely, the outer yoke 11) and the armature 25 that penetrates the internal space. On this basis, the ends of a pair of yokes 10 (more precisely, the outer yoke 11) are fixed to each other, and the armature 25 and the spring 28 are added to the structure to form the drive unit 1.

[0043] The two pairs of magnets 20 are magnetized in opposite directions to each other. For example, the pair of magnets 20 arranged on the right side is magnetized downward, and the pair of magnets 20 arranged on the left side is magnetized upward. Therefore, when current flows in the coil 22 (an electrical signal is supplied), magnetic fluxes in opposite directions are generated in the areas on both sides of the armature 25 in the left-right direction. These magnetic fluxes are guided into a closed loop by a pair of yokes, and the structural part (yoke 10, magnet 20, coil 22) and the armature 25 constitute a magnetic circuit. In addition, when the magnetic force of the magnet 20 acts and the armature 25 is displaced, the restoring force of the spring 28 corresponding to the displacement acts on the armature 25, generating relative vibration between the structural part and the armature.

[0044] It should be noted that the structure of the yoke 10 and the connection relationship between the components forming the drive unit 1 will be described in detail later using other drawings. In addition, in the following description, the direction in which the two pairs of magnets 20 sandwich the coil 22 is represented as the "X direction", the direction in which the paired springs 28 sandwich the armature 25 is represented as the "Z direction", and the direction orthogonal to both the X direction and the Z direction is represented as the "Y direction".

[0045] Figure 2 1 is a perspective view showing the yoke 10. As described above, the yoke 10 is composed of the outer yoke 11 and the inner yoke 12, which are pressed and fixed by laser welding etc. The outer yoke 11 and the inner yoke 12 are formed of a soft magnetic material such as 45% Ni permalloy.

[0046] The outer yoke 11 has: a magnetic flux passing portion 11a for passing magnetic flux; a bent portion 11b having an end surface for fixing a pair of yokes 10; and a spring engaging portion 11c for engaging the spring 28. The magnetic flux passing portion 11a is a flat rectangular portion. The bent portion 11b is a portion formed by bending the plate material forming the magnetic flux passing portion 11a. Two portions are provided on both sides of the magnetic flux passing portion 11a in the Y direction. They protrude from both side surfaces of the magnetic flux passing portion 11a in the Y direction and bend in the Z direction, all extending to the same length. The spring engaging portion 11c is provided on both sides of the magnetic flux passing portion 11a in the X direction. The surface engaging with the spring 28 is formed in a shape that can suppress the torque of the force acting on the spring 28 to be small.

[0047] The inner yoke 12 is a flat rectangular portion having a shape in the XY plane that is substantially the same as the magnetic flux passing portion 11a of the outer yoke, and overlaps with the magnetic flux passing portion 11a, and is integrated with it for magnetic flux to pass through. The magnetic flux guided from the magnet 20 by the yoke 10 passes along the X direction, so the cross-sectional area of ​​the magnetic flux passing portion 11a and the inner yoke 12 in the YZ plane is designed to be a specified size that will not saturate the magnetic flux. Among them, as far as the size in the Y direction is concerned, there will be constraints corresponding to the overall design of the drive unit 1 (electromechanical transducer), so in order to make the cross-sectional area into a specified size, the size in the Z direction, that is, the thickness of the magnetic flux passing portion 11a and the inner yoke 12, must be adjusted to ensure the specified thickness of the yoke 10 as a whole. On the other hand, the rebound force of the spring 28 always acts on the spring engaging portion 11c, and thus the rebound force of the spring 28 is also always transmitted to the end of the curved portion 11b fixed by laser welding, etc., so the desired strength must be ensured at these locations respectively.

[0048] Therefore, in this embodiment, the thickness of the magnetic flux passing portion 11a is reduced within a range that allows the spring engaging portion 11c to have a desired strength, and the amount that does not reach the specified thickness is supplemented by the thickness of the inner yoke 12. In this way, the specified thickness of the yoke 10 as a whole is ensured, sufficient strength is ensured for each of the spring engaging portion 11c and the bent portion 11b, and the protruding dimension of the yoke 10 in the Y direction caused by forming the bent portion 11b by bending can be suppressed to be small.

[0049] Figure 3 FIG. 1 is an exploded perspective view showing the driving unit 1. Figure 3 In order to improve the visual recognizability of the drawings and promote understanding of the invention, the single-dot chain line illustration showing the connection between the magnetic flux passing portion 11a of the outer yoke and the inner yoke 12 and the single-dot chain line illustration showing the connection between the bent portions 11b of the outer yoke arranged at both ends in the Z direction are omitted.

[0050] The magnetic flux passing portion 11a of the outer yoke 11 is crimped and fixed to the inner yoke 12 by laser welding or the like. In addition, a magnet 20 is bonded and fixed to each of the two ends in the X direction of the inner yoke 12, and an air-core coil 22 is bonded and fixed to the center of the inner yoke 12 in the X direction. Furthermore, coil terminals 23 are bonded and fixed to the two ends in the Y direction of the coil 22, and the winding start end and winding end end of the coil winding are welded to the coil terminals 23, respectively.

[0051] On this basis, the armature 25 is arranged to penetrate the hole formed in the coil 22 forming a part of the structure part and extending in the X direction. The armature 25 is formed of a soft magnetic material such as 45% Ni permalloy as the outer yoke 11 and the inner yoke 12, and a spring engaging portion 25a cut into a concave shape is formed at both ends of the armature 25 in the Y direction slightly inside the two ends of the armature 25 in the X direction. The spring 28 is formed by bending a plate-like member made of a stainless steel material such as a spring SUS301 material, and one end of the pair of springs 28 in the Z direction (for example, the right side) is arranged between the outer yoke 11 and the armature 25 and engages with the spring engaging portions 11c and 25a of the two pairs, and the other end of the pair in the X direction (for example, the left side) is arranged between the outer yoke 11 and the armature 25 and engages with the spring engaging portions 11c and 25a of the two pairs. Finally, when the four bent portions 11 b provided on the outer yokes 11 disposed at both ends in the Z direction are pressed against each other and fixed by laser welding or the like, the driving unit 1 is completed.

[0052] In the driving unit 1, two pairs of springs 28 are sandwiched between the outer yoke 11 and the armature 25 in a manner that has a predetermined displacement amount in the Z direction. In addition, the armature 25 is subjected to the rebound force from the springs 28 that form a pair in the Z direction, and is held at a position where these rebound forces are balanced with an appropriate gap between the structural part. The spring engaging portion 11c is provided on the outer yoke 11, but as a result, the length of the plate-like member required for the spring 28 can be made longer than in the case where the spring engaging portion is provided on the inner yoke, and the predetermined displacement amount that the spring 28 can displace in the Z direction can be ensured.

[0053] It should be noted that the drive unit 1 is housed in a housing (not shown). And when the two ends of the armature 25 are fixed to the housing and the wiring (not shown) extending from the coil terminal 23 is connected to the electrical terminal provided in the housing, the electromechanical transducer is completed. Such an electromechanical transducer is used as a vibrator. For example, if it is applied to a cartilage conduction hearing aid worn in the user's concha cavity, the vibration generated by the electromechanical transducer can be transmitted to the ear cartilage via the housing. This structure is only an example of an electromechanical transducer having a drive unit 1, and depending on the purpose of the electromechanical transducer, the drive unit 1 is sometimes housed in the housing together with other components. Or, it is sometimes used without being housed in a housing.

[0054] Figure 4A and Figure 4B It is a figure which demonstrates by comparing the 1st embodiment and a comparative example. Figure 4A is a perspective view showing a yoke 10 ′ of an electromechanical transducer as a comparative example, Figure 4B It is a side view which shows the yoke 10' in parallel with the yoke 10 of the first embodiment.

[0055] In the comparative example yoke 10', the thickness of the magnetic flux passing portion ensured by summing the thickness of the two yoke components (outer yoke 11 and inner yoke 12) in the yoke 10 of the embodiment is ensured by one component. Therefore, the yoke 10' is formed by processing a plate having a predetermined thickness T', and two bent portions 10b' are provided on both sides of the magnetic flux passing portion 10a' in the Y direction, and one spring engaging portion 10c' is provided on both sides in the X direction.

[0056] The bent portion 10b′ is formed by bending a plate having a thickness of T′, so the dimension of the top portion in the Y direction is equal to the thickness T′. Therefore, a greater strength is ensured in the bent portion 10b′, but such a large strength is not required. In addition, the height H′ of the portion of the bent portion 10b′ that protrudes upward from the magnetic flux passing portion 10a′ is designed to be smaller than the thickness T′, but it is very difficult to form such a shape. The protruding dimension W2′ of the yoke 10′ in the Y direction is the size obtained by adding the dimension W1′ of the magnetic flux passing portion 10a′ in the Y direction to the dimension required based on the bending process of the thickness T′.

[0057] In contrast, in the yoke 10 of the first embodiment, the inner yoke 12 formed to have a thickness of T2 is fixed to the magnetic flux passing portion 11a of the outer yoke formed of a plate material of thickness T1, wherein the thickness T1 is a thickness that enables the spring engaging portion 11c to have a desired strength, and the insufficient thickness is supplemented by the thickness of the inner yoke 12. According to such a yoke 10, the cross-sectional area of ​​the portion through which the magnetic flux passes (the shaded portion in the figure) is ensured to be the same size as the yoke 10' of the comparative example (W1×T=W1′×T′), sufficient strength is ensured for each of the spring engaging portion 11c and the bent portion 11b, and the protruding dimension W2 in the Y direction can be reduced by an amount corresponding to the thinning of the thickness T1 of the plate material to be bent (W2<W2′). In addition, it is easy to design the height H of the portion protruding upward from the magnetic flux passing portion 11a of the bent portion 11b to be larger than the thickness T1 of the plate material to be bent, and the formation of the bent portion 11b becomes easy. Therefore, according to the first embodiment, the difficulty in manufacturing components can be alleviated, and the driving unit can be miniaturized, and the entire electromechanical transducer can be miniaturized.

[0058] It should be noted that, in order to facilitate the understanding of the invention, in the embodiments and comparative examples, the description is made under the assumption that the width and thickness of the cross section forming the magnetic flux passing portion are the same (W1=W1′ and T=T′), but based on the overall design of the drive unit 1 (electromechanical transducer), even if the width and height in the embodiments are set to be different from those in the comparative example (for example, the thickness is slightly larger than T, and the width is slightly smaller than W1 according to the thickness, etc.), the same cross-sectional area can be ensured. In addition, the yoke 10 of the first embodiment is composed of two yoke parts (an outer yoke 11 and an inner yoke 12), but the number of yoke parts constituting the yoke is not limited thereto. For example, the inner yoke without a curved portion may be composed of two or more yoke parts formed using a soft magnetic material, and the yoke may be composed of a plurality of yoke parts totaling more than three.

[0059] [Second embodiment]

[0060] Figure 5 1 is a perspective view showing a driving unit (driving unit 2) of an electromechanical transducer according to a second embodiment. The driving unit 2 is composed of a pair (two) of yokes 30, two pairs (four) of magnets 40, a coil 42, an armature 45, and a pair (two) of springs 48. That is, the second embodiment is greatly different from the first embodiment described above in that the springs constituting the driving unit are a pair, and accordingly, the shapes and sizes of other components (yokes, armatures, etc.) are also different from those of the first embodiment.

[0061] It should be noted that in this embodiment, the materials used for the yoke, the armature, and the spring are the same as those in the first embodiment. The description of the points common to the first embodiment will be appropriately omitted.

[0062] Each yoke 30 is composed of an outer yoke 31 forming an outer portion and an inner yoke 32 forming an inner portion, and is arranged at both ends of the Z direction with the outer yoke 31 as the outer side. The coil 42 is fixed to the inner side of a pair of yokes 30 (more accurately, the inner yoke 32) and the central part in the X direction. Two pairs of magnets 40 are fixed to the inner side of a pair of yokes 30 (more accurately, the inner yoke 32) and the two ends in the X direction. The armature 45 is configured to penetrate the internal space of the structural part formed by the integral configuration of the yoke 30, the magnet 40, and the coil 42. A pair of springs 48 are arranged between the structural part (more accurately, the outer yoke 31) and the armature 45. On this basis, the ends of a pair of yokes 30 (more accurately, the inner yoke 32) are fixed to each other to form a drive unit 2.

[0063] In the second embodiment, since the spring 48 constituting the driving portion is provided as a pair, the assembly of the components is easier than in the first embodiment, and therefore, it is suitable for a smaller electromechanical transducer. It should be noted that the structure of the yoke 30 and the connection relationship between the components forming the driving portion 2 will be described in detail later using other drawings.

[0064] Figure 6 2 is a perspective view showing the yoke 30. As described above, the yoke 30 is composed of the outer yoke 31 and the inner yoke 32, which are pressed together and fixed by laser welding or the like.

[0065] The outer yoke 31 is composed of a magnetic flux passing portion 31a through which magnetic flux passes and a spring engaging portion 31b for engaging the spring 48. The magnetic flux passing portion 31a is a substantially flat rectangular portion. The spring engaging portion 31b is provided at each of the two sides of the magnetic flux passing portion 31a in the Y direction, and the surface engaging with the spring 48 is formed in a shape that can suppress the torque of the force acting on the spring 48 to be small.

[0066] The inner yoke 32 is composed of a magnetic flux passing portion 32a through which magnetic flux passes and a bent portion 32b having an end surface for fixing the pair of yokes 30. The magnetic flux passing portion 32a is a substantially flat rectangular portion, and overlaps with the magnetic flux passing portion 31a of the outer yoke 31. The bent portion 32b is a portion formed by bending the plate material forming the magnetic flux passing portion 32a, and is provided at two locations on both sides of the magnetic flux passing portion 32a in the Y direction, protruding from both side surfaces of the magnetic flux passing portion 32a in the Y direction and bending in the Z direction, extending out to the same length.

[0067] In this embodiment, the magnetic flux passing parts 31a and 32a are integrated, and the cross-sectional area of ​​the YZ plane is designed to be a predetermined size that does not cause magnetic flux saturation. In addition, the thickness of the magnetic flux passing part 31a is reduced within a range that allows the spring engaging part 31b to have a desired strength, and the thickness of the magnetic flux passing part 32a of the inner yoke 32 is used to make up for the amount of thickness that does not reach the above-mentioned predetermined thickness. In this way, the predetermined thickness of the yoke 30 as a whole is ensured, and sufficient strength is ensured for each of the spring engaging part 31b and the bent part 32b, while the protruding size of the yoke 30 in the Y direction caused by forming the bent part 32b by bending can be suppressed to be small.

[0068] Figure 7 FIG. 2 is an exploded perspective view showing the driving unit 2. Figure 7 In order to improve the visual recognizability of the drawings and promote the understanding of the invention, the single-dash line illustration representing the connection between the magnetic flux passing portion 31a of the outer yoke and the magnetic flux passing portion 32a of the inner yoke and the single-dotted line illustration representing the connection between the respective bent portions 32b of the inner yoke arranged at the two end portions in the Z direction are omitted.

[0069] The magnetic flux passing portion 31a of the outer yoke is crimped to the magnetic flux passing portion 32a of the inner yoke and fixed by laser welding or the like. In addition, a magnet 40 is bonded and fixed to each of the two ends of the magnetic flux passing portion 32a in the X direction, and an air-core coil 42 is bonded and fixed to the center of the magnetic flux passing portion 32a in the X direction. Furthermore, coil terminals 43 are bonded and fixed to the two ends of the coil 42 in the Y direction, and the winding start end and winding end end of the coil winding are welded to the coil terminals 43, respectively.

[0070] On this basis, the armature 45 is configured to penetrate a hole formed in the X direction on the coil 42 that forms a part of the structural part. At the two ends in the Y direction that are slightly inner than the two ends in the X direction of the armature 45, spring engaging portions 45a cut into concave shapes are respectively formed. A pair of springs 48 are arranged between the outer yoke 31 and the armature 45, engaging with the spring engaging portions 45a of the armature at the two ends in the X direction, and engaging with the spring engaging portions 31b of the outer yoke at the two ends in the Y direction. Finally, when the four bends 32b provided on each inner yoke 32 arranged at the two ends in the Z direction are pressed against each other and fixed by laser welding or the like, the drive unit 2 is completed.

[0071] In the drive unit 2, a pair of springs 48 are sandwiched between the outer yoke 31 and the armature 45 so as to have a predetermined displacement in the Z direction. In addition, the armature 45 receives a rebound force from the pair of springs 48 in the Z direction and is held at a position where these rebound forces are balanced with an appropriate gap between the structure.

[0072] Fig. 8A and Figure 8B It is a figure which demonstrates the 2nd Embodiment by comparison with a comparative example. Fig. 8A is a perspective view showing a yoke 30 ′ of an electromechanical transducer as a comparative example, Figure 8B 30' is a side view showing the yoke 30 of the second embodiment in parallel. Fig. 8A and Figure 8B The reference numerals (W1, W2, H, T, T1, T2, etc.) of the dimensions of the various parts shown are the same as Figure 4A and Figure 8B The reference numerals shown are completely unrelated.

[0073] In the comparative example yoke 30', the thickness of the magnetic flux passing portion ensured by summing the thickness of the two yoke components (outer yoke 31 and inner yoke 32) in the yoke 30 of the embodiment is ensured by one component. Therefore, the comparative example yoke 30' is formed by processing a plate having a predetermined thickness T', two bent portions 30b' are provided on both sides of the magnetic flux passing portion 30a' in the Y direction, and a spring engaging portion 30c' is provided at each intermediate position of the two bent portions 30b'.

[0074] The curved portion 30b′ is formed by bending a plate having a thickness of T′, so the dimension of the top portion in the Y direction is equal to the thickness T′. Therefore, a greater strength is ensured in the curved portion 30b′, but such a large strength is not required. In addition, the height H′ of the portion of the curved portion 30b′ that protrudes upward from the magnetic flux passing portion 30a′ is designed to be smaller than the thickness T′, but it is very difficult to form such a shape. The protruding dimension W2′ in the Y direction at the position of the curved portion 30b′ where the yoke 30′ is provided is the size obtained by adding the dimension W1′ in the Y direction of the magnetic flux passing portion 30a′ to the dimension required based on the bending process of the thickness T′.

[0075] In contrast, in the yoke 30 of the second embodiment, the magnetic flux passing portion 31a of the outer yoke formed of a plate material of thickness T1 that enables the spring engaging portion 31b to have a desired strength and the magnetic flux passing portion 32a of the inner yoke formed of a plate material of thickness T2 are fixed, and the insufficient thickness is supplemented by the thickness of the magnetic flux passing portion 32a of the inner yoke. Although the thickness T2 of the inner yoke 32 is thinner than the thickness T1 of the outer yoke 31, the strength required for the bent portion 32b can be sufficiently ensured even with the thickness T2. According to such a yoke 30, the cross-sectional area (shaded area in the figure) of the portion through which the magnetic flux passes is ensured to be the same size as that of the yoke 30' of the comparative example (W1×T=W1′×T′), sufficient strength is ensured for each of the spring engaging portion 31b and the bent portion 32b, and at the same time, the protruding dimension W2 in the Y direction at the position where the bent portion 32b is provided can be reduced by an amount corresponding to the thinning of the thickness T2 of the plate material subjected to the bending process (W2<W2′). In addition, it is easy to design the height H of the portion protruding upward from the magnetic flux passing portion 32a of the bent portion 32b to be greater than the thickness T2 of the plate material to be bent, and the formation of the bent portion 32b becomes easy. Therefore, according to the second embodiment, the difficulty in component manufacturing can be alleviated, and the driving portion can be miniaturized, thereby miniaturizing the entire electromechanical transducer.

[0076] [Third embodiment]

[0077] Fig. 9 3 is a perspective view showing a driving unit (driving unit 3) of an electromechanical transducer according to the third embodiment. The driving unit 3 comprises a pair (two) of yokes 50, two pairs (four) of magnets 60 (in Fig. 9 In the figure, a portion of the magnet 60 that cannot be visually recognized due to the angle is not shown), a coil 62, an armature 65, two pairs (four) of springs 68, and a pair (two) of side plates 70. In addition, each yoke 50 is formed of a single plate.

[0078] That is, the third embodiment is common to the first embodiment in that the springs constituting the driving portion are two pairs, but is greatly different from the first embodiment in that each yoke 50 is formed of a sheet material and a pair of side plates 70 are provided, and the shapes and sizes of other components are also different from those of the first embodiment. Hereinafter, the description of the points common to the first embodiment will be appropriately omitted.

[0079] A pair of yokes 50 are arranged at both ends in the Z direction. The coil 62 is fixed to the inner side of the pair of yokes 50 and the center in the X direction. Two pairs of magnets 60 are fixed to the inner side of the pair of yokes 50 and the two ends in the X direction. In this way, the integrally arranged yoke 50, magnet 60, coil 62 and a pair of side plates 70 described later constitute a structural part.

[0080] The armature 65 is configured to penetrate the internal space of the structural part. Two pairs of springs 68 are configured between the structural part (more precisely, the yoke 50) and the armature 65 at both ends in the X direction. A pair of side plates 70 has the function of positioning and fixing the pair of yokes 50. The coil terminals 63 are configured at both ends in the Y direction in a state where they are exposed from the openings of the pair of side plates 70. After the positions and intervals of the pair of yokes 50 are determined, the side surfaces of the yokes 50 in the Y direction are fixed. In this way, the structural part, the armature 65, and the springs 68 are added to form the drive unit 3.

[0081] In the third embodiment, since the yoke 50 is formed by a sheet without bending, the yoke is easier to manufacture than in the first embodiment. It should be noted that the structure of the side plate 70 and the connection relationship between the components forming the drive unit 3 will be described in detail later using other drawings.

[0082] Fig.10 It is a perspective view showing the side plate 70 .

[0083] The side plate 70 includes: an opening portion 70a, which is opened in the central portion of the side plate 70 to expose the coil terminal; a fixing portion 70b, which is formed to surround the opening portion 70a and is fixed to a pair of yokes 50; a bent portion 70c, which is provided at symmetrical positions on both sides of the fixing portion 70b in the X direction, protruding from a part of the two side surfaces of the fixing portion 70b in the X direction and bending in the Y direction; and a spacer 70d, which is provided at the end of the bent portion 70c in the Y direction, has a predetermined length L1 in the Z direction, determines the spacing and position of the pair of yokes 50 and ensures the space between the two.

[0084] The various parts of the side plate 70 are formed by performing various processes on a single plate. The thickness of the side plate 70 is set to be considerably thinner than the thickness of the yoke 50. As the material of the side plate 70, for example, a stainless steel material such as SUS301 material is used.

[0085] Fig.11 FIG. 2 is an exploded perspective view showing the driving unit 3. Fig.11 In order to improve the visual recognition of the drawings and facilitate the understanding of the invention, the single-dot chain line indicating the connection between the side plate 70 and the yoke 50 is omitted. In addition, for reference numerals not shown in the drawings to improve visual recognition, appropriate reference can be made to Fig. 9 , Fig.10 .

[0086] The yoke 50 is formed of a sheet material, and has: a substantially flat rectangular magnetic flux passing portion 50a for magnetic flux to pass through; and a spring engaging portion 50b, formed at each of the central portions at both ends of the magnetic flux passing portion 50a in the X direction to engage the spring 68. A magnet 60 is bonded and fixed to each of the two ends of the magnetic flux passing portion 50a in the X direction, and an air-core coil 62 is bonded and fixed to the central portion of the magnetic flux passing portion 50a in the X direction. In addition, coil terminals 63 are bonded and fixed to both ends of the coil 62 in the Y direction, and the winding start end and winding end end of the coil winding are welded to the coil terminals 63, respectively.

[0087] On this basis, the armature 65 is configured to penetrate the hole formed in the coil 62 forming a part of the structure and extending in the X direction. Spring engaging portions 65a cut into concave shapes are respectively formed at both ends in the Y direction slightly inside the two ends in the X direction of the armature 65. Two pairs of springs 68 are arranged between the yoke 50 and the armature 65 at both ends in the X direction and engage with the spring engaging portions 50b and 65a of both.

[0088] In addition, side plates 70 are arranged from both sides of the Y direction of the integrally arranged yoke 50, magnet 60, and coil 62. First, the side plates 70 are arranged so that the coil terminal 63 is exposed from the opening 70a, and the spacer 70d is inserted between the pair of yokes 50 and aligned with the prescribed position of the magnetic flux passing portion 50a. Thus, a prescribed size of interval is maintained between the two yokes 50. On this basis, when the fixing portion 70b is fixed to the side of the magnetic flux passing portion 50a by laser welding or the like, the drive unit 3 is completed.

[0089] [Fourth embodiment]

[0090] Fig.12 1 is a perspective view showing a driving unit (driving unit 4) of an electromechanical transducer according to a fourth embodiment. The driving unit 4 comprises a pair (two) of yokes 80, two pairs (four) of magnets 90 (in Fig.12 In the figure, a portion of the magnet 90 that cannot be visually recognized due to the angle is not shown), a coil 92, an armature 95, a pair (two) of springs 98, and a pair (two) of side plates 100. In addition, each yoke 80 is formed of a single plate.

[0091] That is, the fourth embodiment is common to the second embodiment in that the springs constituting the driving portion are a pair, but is greatly different from the second embodiment in that each yoke is formed by a sheet and a pair of side plates are provided, and the shapes and sizes of other components are also different from the second embodiment. In addition, the fourth embodiment is common to the third embodiment in that each yoke is formed by a sheet and a pair of side plates are provided, but is greatly different from the third embodiment in that the springs constituting the driving portion are a pair. Hereinafter, the description of the points common to the second and third embodiments will be appropriately omitted.

[0092] A pair of yokes 80 are arranged at both ends in the Z direction. A coil 92 is fixed to the inner side of the pair of yokes 80 and the center portion in the X direction. Two pairs of magnets 90 are fixed to the inner side of the pair of yokes 80 and the two ends in the X direction. In this way, the integrally arranged yoke 80, magnet 90, coil 92 and a pair of side plates 100 described later constitute a structural part.

[0093] The armature 95 is configured to penetrate the internal space of the structural part. A pair of springs 98 are configured between the structural part (more precisely, the yoke 80) and the armature 95. The pair of side plates 100 has the function of positioning and fixing the pair of yokes 80. The coil terminals 93 are arranged at both ends of the Y direction in a state where they are exposed from the openings of the pair of side plates 100. After the positions and intervals of the pair of yokes 80 are determined, the side surfaces of the yokes 80 in the Y direction are fixed. In this way, the structural part, the armature 95, and the springs 98 are added to form the drive unit 4.

[0094] In the fourth embodiment, since the yoke 80 is formed by a sheet without bending, the yoke is easier to manufacture than in the second embodiment. In addition, since the springs 98 constituting the drive unit are provided as a pair, the assembly of the structural part is easier than in the third embodiment, and thus it is suitable for a smaller electromechanical transducer. It should be noted that the structure of the side plate 100 and the connection relationship between the components forming the drive unit 4 will be described in detail later using other drawings.

[0095] Fig.13 It is a perspective view showing the side plate 100 .

[0096] The side plate 100 has: an opening portion 100a, which is opened in the center of the side plate 100 to expose the coil terminal; a fixing portion 100b, which is used to fix with a pair of yokes 80, and is formed by surrounding the opening portion 100a and cutting out a concave shape at the center of both sides of the side plate 100 in the Z direction; a bending portion 100c, which is provided at a symmetrical position on both sides of the fixing portion 100b in the X direction, protruding from a part of both side surfaces of the fixing portion 100b in the X direction and bending in the Y direction; and a spacing portion 100d, which has a predetermined length L2 in the Z direction and is provided at the end of the bending portion 100c in the Y direction, determines the spacing and position of the pair of yokes 80 and ensures a space between the two. The notch formed in the fixing portion 100b is used to accommodate the spring engaging portion protruding from the yoke 80 in the Y direction.

[0097] These parts of the side plate 100 are formed by performing various processes on a single plate material. In addition, the thickness of the side plate 100 is set to be considerably thinner than the thickness of the yoke 80 .

[0098] Fig.14 FIG. 4 is an exploded perspective view showing the driving unit 4. Fig.14 In order to improve the visual recognition of the drawings and facilitate the understanding of the invention, the single-dot chain line diagram representing the connection between the side plate 100 and the yoke 80 is omitted. In addition, for reference numerals that are not shown in the drawings to improve visual recognition, appropriate references can be made to Fig.12 , Fig.13 .

[0099] The yoke 80 is formed of a sheet material, and has: a substantially flat rectangular magnetic flux passing portion 80a for magnetic flux to pass through; and a spring engaging portion 80b, formed at each of the central portions at both ends of the magnetic flux passing portion 80a in the Y direction to engage the spring 98. A magnet 90 is bonded and fixed to each of the two ends of the magnetic flux passing portion 80a in the X direction, and an air-core coil 92 is bonded and fixed to the central portion of the magnetic flux passing portion 80a in the X direction. In addition, coil terminals 93 are bonded and fixed to both ends of the coil 92 in the Y direction, and the winding start end and winding end end of the coil winding are welded to the coil terminals 93, respectively.

[0100] Furthermore, the side plates 100 are arranged from both sides of the yoke 80, the magnet 90, and the coil 92 arranged integrally in the Y direction. First, the side plates 100 are arranged so that the spring engaging portion 80b of the yoke is accommodated in the concave notch and the coil terminal 93 is exposed from the opening 100a, and the spacer 100d is inserted between the pair of yokes 80 and aligned with the predetermined position of the magnetic flux passing portion 80a. Thus, a predetermined size of space is maintained between the two yokes 80.

[0101] The armature 95 is configured to penetrate a hole formed in the X direction on the coil 92 forming a part of the structural part. At the two ends in the Y direction slightly inward than the two ends in the X direction of the armature 95, spring engaging portions 95a cut into concave shapes are respectively formed. A pair of springs 98 are arranged between the yoke 80 and the armature 95, engaging with the spring engaging portions 95a of the armature at the two ends in the X direction, and engaging with the spring engaging portions 80b of the yoke at the two ends in the Y direction. On this basis, when the fixing portion 100b of the side plate is fixed to the side of the magnetic flux passing portion 80a by laser welding or the like, the drive unit 4 is completed.

[0102] [Advantages of the implementation method]

[0103] In the first and third embodiments, the springs constituting the driving part correspond to two pairs of electromechanical transducers, and in the second and fourth embodiments, the springs constituting the driving part correspond to a pair of electromechanical transducers. In the first and second embodiments, the yoke is formed by two sheets (composed of two yoke parts), and the bent parts formed by bending only one sheet (sheet thinner than the yoke) are fixed to each other, so that the components are easily manufactured and the overall size of the driving part is suppressed. In contrast, in the third and fourth embodiments, the yoke is formed by a sheet without bending, and a pair of yokes are fixed by a pair of side plates formed by bending a sheet thinner than the yoke, so that the components are easily manufactured and the overall size of the driving part is suppressed. In this way, the four embodiments have different structures, but all the embodiments are common in that a pair of yokes are fixed by a member formed by a sheet thinner than the yoke and having a bent portion.

[0104] As described above, according to each embodiment, the following effects can be obtained.

[0105] (1) According to each of the four embodiments, a pair of yokes is fixed by a portion formed by a plate having a thickness thinner than that of the yokes, so that a component having the portion can be easily manufactured compared to a case where the portion is formed by a plate having the same thickness as that of the yokes. In addition, when a portion of the component is formed by bending, the protruding size of the component at the portion protruding due to the bending is suppressed to be small compared to a case where a plate having the same thickness as that of the yokes is bent, so that the drive unit can be miniaturized, and the electromechanical transducer can be miniaturized.

[0106] (2) According to the first embodiment and the second embodiment, a pair of yokes is formed by integrating two yoke parts (an outer yoke and an inner yoke), respectively. The yoke part on one side is set to have a thickness of a desired strength so that the spring engaging portion, on which the spring's rebound force always acts, can have a thickness. The yoke part on the other side is set to have a thickness that makes up for the shortfall in thickness on the basis of ensuring that the magnetic flux passing through the yoke is not saturated with a specified cross-sectional area. Therefore, the specified thickness of the yoke as a whole can be ensured. In addition, thereby, the yoke parts can be easily manufactured, and the protruding size of the yoke at the portion that protrudes due to the bending process can be suppressed to be small. As a result, the drive unit can be miniaturized, and the electromechanical transducer can be miniaturized.

[0107] (3) According to the third and fourth embodiments, since the yoke is formed by a sheet without being bent, the yoke can be easily manufactured. In addition, since the pair of side plates for positioning and fixing the yoke are formed by various processes on a sheet thinner than the yoke, the side plates can be easily manufactured with the minimum required size. As a result, the drive unit can be miniaturized, and the electromechanical transducer can be miniaturized.

[0108] The present invention is not limited to the above-described embodiments, and can be implemented in various modified forms.

[0109] In the second embodiment, the spring engaging portion 31b is provided on the outer yoke 31, and the bent portion 32b is provided on the inner yoke 32, but the spring engaging portion and the bent portion may be provided on the same yoke component. For example, the spring engaging portion and the bent portion may be provided on the outer yoke. In such a configuration, the inner yoke is formed into a shape substantially the same as the shape of the magnetic flux passing portion of the outer yoke.

[0110] The springs 28 , 48 , 68 , and 98 in the above-described embodiments may be any spring as long as they can impart a restoring force corresponding to the displacement to the armature that is displaced by the magnetic force of the magnet, and elastic members other than leaf springs may be used.

[0111] The driving units 1, 2, 3, and 4 of the above-described embodiments may be applied to purposes other than electromechanical transducers, for example, as a part of an electroacoustic transducer that converts electrical vibration into sound and outputs it to the outside.

[0112] It is needless to say that the materials, numerical values, etc. given as examples of the components of the drive units 1 , 2 , 3 , and 4 are merely examples and can be appropriately modified when implementing the present invention.

[0113] This application is based on Japanese Patent Application No. 2020-152715 filed on September 11, 2020, the contents of which are incorporated herein by reference.

[0114] Description of reference numerals:

[0115] 1, 2, 3, 4: driving part;

[0116] 10, 30, 50, 80: yoke iron;

[0117] 11, 31: outer yoke;

[0118] 12, 32: inner yoke;

[0119] 20, 40, 60, 90: magnet;

[0120] 22, 42, 62, 92: coils;

[0121] 23, 43, 63, 93: coil terminals;

[0122] 25, 45, 65, 95: armature;

[0123] 28, 48, 68, 98: spring;

[0124] 70, 100: Side panels.

Claims

1. An electromechanical transducer, comprising: Pairs of magnets; A pair of yokes, each yoke being formed by overlapping a plurality of yoke parts at a flat plate-like portion, for guiding the magnetic flux generated by the magnet; The air-core coil is supplied with an electrical signal; An armature is configured to penetrate an internal space of a structure in which the magnet and the coil are integrally arranged inside the paired yokes; as well as A pair of elastic members, each elastic member is engaged with the structural part and the armature, The plurality of yoke components include a first yoke component and a second yoke component, Each of the yokes has a bent portion on the first yoke component, the bent portion protruding from two side surfaces in a predetermined second direction orthogonal to a first direction as an overlapping direction of the yoke components, and bent toward the first direction to extend by a predetermined length, The thickness of the second yoke member is configured such that a cross-sectional area of ​​a plane perpendicular to a direction in which magnetic flux passes where the second yoke member overlaps the first yoke member is designed to be a predetermined size that does not saturate the magnetic flux.

2. The electromechanical transducer according to claim 1, characterized in that: Each of the yokes has an engaging portion protruding from a predetermined position on both side surfaces of a yoke member arranged on the outside of the structural portion in any direction perpendicular to the first direction. The elastic member is engaged with the engaging portion.

Images