Electromechanical Converter

Abstract

To provide a technique of downsizing an electromechanical converter while reducing the difficulty of manufacturing components.SOLUTION: A driving unit 1 includes: an integrated structure part to which, in the inside of a pair of yokes 10, a coil 22 and two pairs of magnets 20 are fixed; an armature 25 penetrating the inner space of the structure part; and two pairs of springs 28 arranged therebetween. The yokes 10 are formed by integrating the outside yoke 11 and the inside yoke 12 with each other, and finally the end part of each bending part 11b is fixed. The outside yoke 11 is set to be thick enough to secure a desired strength for a spring engagement unit 11c, on which the repulsive force of the springs 28 acts. The inside yoke 12 is set to be thick enough to compensate for shortages of thickness required to secure a predetermined cross section which does not saturate magnetic fluxes passing through the yokes 10. This makes it easier to manufacture yoke components, and manufacturing the yokes 10 with a reduced protruding size without saturating magnetic fluxes leads to downsizing of the driving unit and the electromechanical converter.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an electromechanical transducer that converts an electrical signal into mechanical vibration, and in particular to an electromechanical transducer having a structure that utilizes the restoring force of a spring engaged with an armature, among so-called balanced armature structures. [Background technology]

[0002] In this type of electromechanical converter, a spring is disposed between a structural part in which a yoke, magnet, and coil are integrally disposed, and an armature penetrating the internal space of the structural part to form a drive part, and when a current flows through 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, and the drive part generates relative vibration between the armature and the structural part. For example, an electromechanical converter in which two pairs of springs are disposed between the structural part and the armature (see Patent Document 1) and an electromechanical converter in which one pair of springs is disposed (see Patent Document 2) are known. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2015-139041 A [Patent Document 2] JP 2018-186378 A Summary of the Invention [Problem to be solved by the invention]

[0004] The yoke, which is part of the structure, is made of a soft magnetic material and serves to guide the magnetic flux generated by the magnet. The soft magnetic material has a set saturation magnetic flux density as a characteristic, and if the saturation magnetic flux density is exceeded, the magnetic flux becomes saturated and reaches a plateau, and the yoke no longer functions as a yoke. Therefore, the cross-sectional area of ​​the yoke needs to be designed to be within a range that does not saturate the magnetic flux.

[0005] All of the above-mentioned prior arts have a structure in which an armature is sandwiched between two yokes via springs, and then the yokes are joined and fixed in place. In other words, the role of the yoke in these prior arts is to guide the magnetic flux (role during use), as well as to position the armature via the springs and to fix the two yokes together to complete the drive unit (role during manufacture).

[0006] Usually, when manufacturing parts by processing a plate material, the minimum width of punching or bending naturally becomes larger as the thickness of the plate material increases. In consideration of the role of the yoke during use, the yoke in the above-mentioned prior art needs to be thick enough to ensure a desired cross-sectional area of ​​the part through which the magnetic flux passes. However, when designing a plate material of this thickness to be bent so that it can fulfill its role during manufacturing, problems arise such as manufacturing being difficult depending on the shape of the part, or the dimensions of the part to be bent become larger than necessary, resulting in a large overall dimension of the electromechanical transducer.

[0007] The present invention has been made in view of the above problems, and an object of the present invention is to provide a technique for miniaturizing an electromechanical transducer while mitigating the difficulties involved in manufacturing components of the electromechanical transducer. [Means for solving the problem]

[0008] In order to solve the above problems, the present invention employs the following electromechanical transducer. Note that the following words in parentheses are merely examples, and the present invention is not limited thereto.

[0009] The electromechanical converter of the present invention comprises a pair of magnets, a pair of yokes, each of which is formed by overlapping a number of yoke parts at flat portions thereof, for guiding magnetic flux from the magnets, an air-core coil to which an electric signal is supplied, an armature disposed inside the pair of yokes and penetrating the internal space of a structural part in which the magnet and coil are integrally disposed, and a pair of elastic members, each of which engages with the structural part and the armature.

[0010] In the electromechanical transducer of this aspect, each yoke is formed by stacking a plurality of yoke parts each having a flat portion, and the sum of the thicknesses of the plurality of flat portions ensures a predetermined cross-sectional area that does not saturate the magnetic flux passing through the yoke. Since each of these yoke parts is made of a plate material thinner than the thickness of the yoke, when bending to form other portions, the manufacturing is easier than when bending a plate material of the same thickness as the yoke, and the protruding dimension due to the bending is suppressed to a small size. Therefore, according to the electromechanical transducer of this aspect, it is possible to manufacture a smaller yoke that does not saturate the magnetic flux while mitigating the difficulty in manufacturing, which contributes to the miniaturization of the electromechanical transducer.

[0011] Preferably, in the above-mentioned electromechanical converter, the yoke has a bent portion in any one of the yoke components that protrudes from symmetrical positions on both side surfaces in a predetermined second direction perpendicular to the first direction in which the yoke components are stacked, bent in the first direction, and extends a predetermined length, and the pair of yokes are fixed to each other at the end faces of the bent portion.

[0012] In the electromechanical transducer of this aspect, one of the yoke components has a bent portion. The bent portion is formed by bending the plate material that constitutes the yoke component, but since this plate material is thinner than the thickness of the yoke, it is easier to bend it compared to a plate material having the same thickness as the yoke, and the protruding dimension is suppressed to a small value by bending it. Therefore, with the electromechanical transducer of this aspect, it is possible to reduce the size of the electromechanical transducer while easing the difficulty in manufacturing the components.

[0013] More preferably, in the above electromechanical converter, each yoke has an engagement portion protruding from a predetermined position on both side surfaces in any direction perpendicular to the first direction of the yoke part arranged on the outside of the structural portion, and the elastic member engages with the engagement portion.

[0014] According to the electromechanical converter of this embodiment, a portion where the elastic member engages is provided on the yoke part that is arranged on the outside when the yoke is integrated as part of the structural part. Therefore, the length of the elastic member can be made longer than if such a portion were provided on the yoke part that is arranged on the inside of the structural part, and a predetermined displacement amount that allows the elastic member to be displaced in the first direction can be secured. Effect of the Invention

[0015] As described above, according to the present invention, it is possible to reduce the size of the electromechanical transducer while mitigating the difficulties involved in manufacturing the components of the electromechanical transducer. [Brief description of the drawings]

[0016] [Figure 1] FIG. 2 is a perspective view showing a drive unit in the electromechanical transducer of the first embodiment. [Diagram 2] FIG. 2 is a perspective view showing a yoke in the electromechanical transducer of the first embodiment. [Diagram 3] FIG. 2 is an exploded perspective view showing a drive unit in the electromechanical transducer of the first embodiment. [Figure 4] FIG. 2 is a diagram for explaining the first embodiment in comparison with a comparative example. [Diagram 5] FIG. 11 is a perspective view showing a drive unit in an electromechanical transducer according to a second embodiment. [Figure 6] FIG. 11 is a perspective view showing a yoke in an electromechanical transducer according to a second embodiment. [Figure 7] FIG. 11 is an exploded perspective view showing a drive unit in an electromechanical transducer according to a second embodiment. [Figure 8] FIG. 11 is a diagram for explaining the second embodiment in comparison with a comparative example. [Figure 9] FIG. 11 is a perspective view showing a drive unit in an electromechanical transducer according to a third embodiment. [Figure 10] FIG. 11 is a perspective view showing a side plate in an electromechanical transducer according to a third embodiment. [Figure 11] FIG. 11 is an exploded perspective view showing a drive unit in an electromechanical transducer according to a third embodiment. [Figure 12] FIG. 13 is a perspective view showing a drive unit in an electromechanical transducer according to a fourth embodiment. [Figure 13] FIG. 11 is a perspective view showing a side plate in an electromechanical transducer according to a fourth embodiment. [Figure 14] FIG. 13 is an exploded perspective view of a drive unit in an electromechanical transducer according to a fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the following embodiments are preferred examples, and the present invention is not limited to these examples. For convenience of explanation, the directions of the configuration may be indicated as up, down, left, and right along the directions on the paper surface of each drawing.

[0018] [First embodiment] 1 is a perspective view showing a driving section (driving section 1) in an electromechanical transducer according to a first embodiment. The driving section 1 is composed of one pair (two) of yokes 10, two pairs (four) of magnets 20, a coil 22, an armature 25, and two pairs (four) of springs 28.

[0019] 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 one above the other with the outer yoke 11 facing outwards. The coil 22 is fixed to the inside and left-right center of the pair of yokes 10 (more precisely, the inner yokes 12) arranged one above the other. The magnets 20 are paired one above the other, and two pairs of magnets 20 are fixed to the inside and both left and right ends of the pair of yokes 10 (more precisely, the inner yokes 12). The yokes 10, magnets 20, and coils 22 arranged integrally in this manner constitute a structural part.

[0020] The armature 25 is disposed so as to penetrate the internal space of the structural part. The springs 28 are paired vertically, and the two pairs of springs 28 are disposed at both left and right ends between the structural part (more precisely, the outer yoke 11) and the armature 25 penetrating the internal space thereof. Then, the ends of the pair of yokes 10 (more precisely, the outer yoke 11) are fixed to each other, and the armature 25 and the springs 28 are added to the structural part to constitute the drive part 1.

[0021] The two pairs of magnets 20 are magnetized in mutually opposite directions. 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 a current flows through the coil 22 (an electric signal is supplied), magnetic fluxes in mutually opposite directions are generated in the regions on both sides of the left and right direction of the armature 25, and these magnetic fluxes are guided in a closed circuit by a pair of yokes, and the structural part (yoke 10, magnet 20, coil 22) and the armature 25 form a magnetic circuit. Then, when the magnetic force of the magnet 20 acts to displace the armature 25, the restoring force of the spring 28 corresponding to this displacement acts on the armature 25, and a relative vibration occurs between the structural part and the armature.

[0022] The configuration of the yoke 10 and the connections between the components of the drive unit 1 will be described in detail later with reference to other drawings. In the following description, the direction in which the two pairs of magnets 20 sandwich the coil 22 is referred to as the "X direction", the direction in which the pair of springs 28 sandwich the armature 25 is referred to as the "Z direction", and the direction perpendicular to both the X direction and the Z direction is referred to as the "Y direction".

[0023] 2 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 pressure-welded and fixed by laser welding or the like. The outer yoke 11 and the inner yoke 12 are formed of a soft magnetic material, for example, 45% Ni permalloy.

[0024] The outer yoke 11 has a magnetic flux passing portion 11a through which magnetic flux passes, a bent portion 11b having an end surface for fixing the 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, and is provided at two locations on both sides of the magnetic flux passing portion 11a in the Y direction, protruding from both sides of the magnetic flux passing portion 11a in the Y direction and bending in the Z direction to extend out by the same length. The spring engaging portion 11c is provided at one location on both sides of the magnetic flux passing portion 11a in the X direction, and the surface that engages with the spring 28 is formed in a shape that can suppress the torque of the force acting on the spring 28 to a small value.

[0025] The inner yoke 12 is a flat rectangular part whose shape in the XY plane is substantially the same as that of the magnetic flux passing part 11a of the outer yoke, and is superimposed on the magnetic flux passing part 11a and integrated therewith, so that the magnetic flux passes through it. Since the magnetic flux guided from the magnet 20 to the yoke 10 passes in the X direction, the cross-sectional areas of the magnetic flux passing part 11a and the inner yoke 12 in the YZ plane are designed to be a predetermined size that does not saturate the magnetic flux. Here, since the dimension in the Y direction is restricted according to the design of the driving part 1 (electromechanical converter) as a whole, in order to set the cross-sectional area to a predetermined size, the dimension in the Z direction, that is, the thickness of the magnetic flux passing part 11a and the inner yoke 12 must be adjusted to ensure a predetermined thickness for the yoke 10 as a whole. On the other hand, the repulsive force of the spring 28 acts on the spring engagement part 11c from start to finish, and as a result, the repulsive force of the spring 28 is also transmitted to the end of the bent part 11b fixed by laser welding or the like from start to finish, so that the desired strength must be ensured for each of these parts.

[0026] Therefore, in this embodiment, the thickness of magnetic flux passing portion 11a is made thin within a range that allows spring engagement portion 11c to have the desired strength, and any thickness that is short of the predetermined thickness is made up for by the thickness of inner yoke 12. This ensures a predetermined thickness for yoke 10 as a whole, and ensures sufficient strength for each of spring engagement portion 11c and bent portion 11b, while minimizing the protruding dimension of yoke 10 in the Y direction that is generated by forming bent portion 11b by bending.

[0027] Fig. 3 is an exploded perspective view showing the drive unit 1. In Fig. 3, in order to improve the visibility of the drawing and facilitate understanding of the invention, dashed dotted lines indicating the connection between the magnetic flux passing portion 11a of the outer yoke and the inner yoke 12, and the connection between the bent portions 11b of the outer yokes arranged at both ends in the Z direction are omitted.

[0028] The magnetic flux passing portion 11a of the outer yoke 11 and the inner yoke 12 are pressure-welded and fixed by laser welding or the like. A magnet 20 is adhesively fixed to each of both ends in the X direction of the inner yoke 12, and an air-core coil 22 is adhesively fixed to the center of the inner yoke 12 in the X direction. Coil terminals 23 are adhesively fixed to both ends in the Y direction of the coil 22, and the start and end of the coil winding are soldered to the coil terminals 23, respectively.

[0029] Then, the armature 25 is arranged so as to penetrate a hole penetrating in the X direction formed in the coil 22 forming a part of the structural part. The armature 25 is formed, for example, using a soft magnetic material such as 45% Ni permalloy, which is the same as the outer yoke 11 and the inner yoke 12, and a spring engagement portion 25a that is notched in a concave shape is formed at both ends in the Y direction slightly inside the ends in the X direction. The springs 28 are formed, for example, by bending a plate-shaped member using a stainless steel material such as SUS301 material for springs. Of the two pairs of springs 28 that form a pair in the Z direction, one pair is arranged between the outer yoke 11 and the armature 25 at one end in the X direction (for example, the right side) and engages with the spring engagement portions 11c, 25a of both, and the other pair is arranged between the outer yoke 11 and the armature 25 at the other end in the X direction (for example, the left side) and engages with the spring engagement portions 11c, 25a of both. Finally, the four bent portions 11b provided on the outer yokes 11 arranged at both ends in the Z direction are pressed against each other and fixed by laser welding or the like, and the drive unit 1 is completed.

[0030] In the drive unit 1, the two pairs of springs 28 are sandwiched between the outer yoke 11 and the armature 25 with a predetermined amount of displacement in the Z direction. The armature 25 receives repulsive forces from the pair of springs 28 in the Z direction, and is held at a position where these repulsive forces are balanced with an appropriate gap between the armature and the structural part. The spring engaging portion 11c is provided on the outer yoke 11, which allows the length of the plate-like member required for the spring 28 to be longer than if the spring engaging portion were provided on the inner yoke, and ensures a predetermined amount of displacement that allows the spring 28 to be displaced in the Z direction.

[0031] The driving unit 1 is accommodated in a housing (not shown). Then, when both ends of the armature 25 are fixed to the housing and the wiring (not shown) extending from the coil terminal 23 is connected to an electric terminal provided on the housing, the electromechanical converter is completed. Such an electromechanical converter is used as a vibrator. For example, if it is applied to a cartilage conduction hearing aid worn in the user's concha, it is possible to transmit vibrations generated by the electromechanical converter to the ear cartilage through the housing. This configuration is merely one example of an electromechanical converter equipped with the driving unit 1, and depending on the application of the electromechanical converter, the driving unit 1 may be accommodated in a housing together with further components. Alternatively, it may be used without being accommodated in a housing.

[0032] Fig. 4 is a diagram for explaining the first embodiment in comparison with a comparative example, in which (A) in Fig. 4 is a perspective view showing a yoke 10' in an electromechanical transducer as a comparative example, and (B) in Fig. 4 is a side view showing the yoke 10' next to the yoke 10 of the first embodiment.

[0033] The yoke 10' of the comparative example is intended to ensure, with one component, the thickness of the magnetic flux passing portion ensured by the combined thickness of the two yoke components (outer yoke 11 and inner yoke 12) in the yoke 10 of the embodiment. For this reason, the yoke 10' is formed by processing a single plate material having a predetermined thickness T', and has two bent portions 10b' on each side of the magnetic flux passing portion 10a' in the Y direction, and one spring engagement portion 10c' on each side in the X direction.

[0034] Since the bent portion 10b' is formed by bending a plate material with a thickness T', the dimension in the Y direction at the tip thereof is equal to the thickness T'. Therefore, a large strength is ensured for the bent portion 10b', but such strength is not required. Further, the height H' of the portion protruding above the magnetic flux passing portion 10a' of the bent portion 10b' 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 of the yoke 10' is the size obtained by adding the dimension required for bending the thickness T' to the dimension W1' in the Y direction of the magnetic flux passing portion 10a'.

[0035] On the other hand, in the yoke 10 of the first embodiment, the inner yoke 12 formed of a plate material with a thickness T1 that can give the spring engaging portion 11c a desired strength is fixed to the magnetic flux passing portion 11a of the outer yoke, and the shortage of the thickness is compensated by the thickness of the inner yoke 12. According to such a yoke 10, the cross-sectional area (the shaded portion in the figure) of the portion through which the magnetic flux passes is ensured to be the same size as that of the yoke 10' of the comparative example (W1×T = W1'×T'), and while ensuring sufficient strength for each of the spring engaging portion 11c and the bent portion 11b, the protruding dimension W2 in the Y direction can be suppressed to be smaller by the amount by which the thickness T1 of the plate material to be bent is made thinner (W2 < W2'). Further, it becomes easier to design the height H of the portion protruding above 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, it is possible to reduce the difficulty in manufacturing parts and thus miniaturize the drive unit and ultimately the electromechanical converter as a whole.

[0036] In order to facilitate understanding of the invention, the description has been given under the assumption that the width and thickness of the cross section of the magnetic flux passage portion are the same in the embodiment and the comparative example (W1=W1' and T=T'). However, taking into consideration the design of the driving unit 1 (electromechanical transducer) as a whole, it is possible to ensure the same cross-sectional area while making the width and height in the embodiment different from those in the comparative example (for example, making the thickness slightly larger than T and accordingly making the width slightly smaller than W1). In addition, the yoke 10 in the first embodiment is composed of two yoke parts (the outer yoke 11 and the inner yoke 12), but the number of yoke parts constituting the yoke is not limited to this. For example, the inner yoke without a bent portion may be composed of two or more yoke parts formed using a soft magnetic material, and the yoke may be composed of a total of three or more yoke parts.

[0037] Second Embodiment 5 is a perspective view showing a driving section (driving section 2) in an electromechanical transducer of the second embodiment. The driving section 2 is composed of one pair (two) of yokes 30, two pairs (four) of magnets 40, a coil 42, an armature 45, and one pair (two) of springs 48. That is, the second embodiment is significantly different from the above-mentioned first embodiment in that the driving section is made up of one pair of springs, and therefore the shapes and sizes of the other components (yoke, armature, etc.) are also different from those in the first embodiment.

[0038] In this embodiment, the materials used for the yoke, armature, and spring are the same as those in the first embodiment, and a description of the points common to the first embodiment will be omitted as appropriate.

[0039] 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 in the Z direction with the outer yoke 31 facing outward. The coil 42 is fixed inside the pair of yokes 30 (more precisely, the inner yoke 32) and at the center in the X direction. The two pairs of magnets 40 are fixed inside the pair of yokes 30 (more precisely, the inner yoke 32) and at both ends in the X direction. The armature 45 is arranged so as to penetrate the internal space of the structural part in which the yoke 30, the magnet 40, and the coil 42 are integrally arranged. The two pairs of springs 48 are arranged between the structural part (more precisely, the outer yoke 31) and the armature 45. Then, the ends of the pair of yokes 30 (more precisely, the inner yoke 32) are fixed to each other to constitute the driving part 2.

[0040] In the second embodiment, the springs 48 constituting the drive unit are a pair, so that assembly of the components is easier than in the first embodiment, and therefore the second embodiment is suitable for a smaller electromechanical transducer. The configuration of the yoke 30 and the connection between the components constituting the drive unit 2 will be described in detail later with reference to other drawings.

[0041] 6 is a perspective view showing the yoke 30. As described above, the yoke 30 is made up of the outer yoke 31 and the inner yoke 32, which are pressure-welded and fixed together by laser welding or the like.

[0042] The outer yoke 31 is composed of a magnetic flux passing portion 31a through which magnetic flux passes, and a spring engagement portion 31b that engages the spring 48. The magnetic flux passing portion 31a is a generally flat rectangular portion. The spring engagement portions 31b are provided at two locations on both sides of the magnetic flux passing portion 31a in the Y direction, and the surfaces that engage with the spring 48 are formed in a shape that can reduce the torque of the force acting on the spring 48.

[0043] 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 is overlapped with the magnetic flux passing portion 31a of the outer yoke 31. The bent portions 32b are portions formed by bending the plate material constituting the magnetic flux passing portion 32a, and are provided in 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 to extend by the same length.

[0044] In this embodiment, the magnetic flux passing parts 31a and 32a are integrated, and the cross-sectional area in the YZ plane is designed to be a predetermined size that does not saturate the magnetic flux. The thickness of the magnetic flux passing part 31a is made thin within a range that allows the spring engagement part 31b to have a desired strength, and the thickness of the magnetic flux passing part 32a of the inner yoke 32 makes up for the thickness that is insufficient to the above-mentioned predetermined thickness. This ensures a predetermined thickness for the yoke 30 as a whole, and ensures sufficient strength for each of the spring engagement part 31b and the bent part 32b, while minimizing the protruding dimension of the yoke 30 in the Y direction that is generated by forming the bent part 32b by bending.

[0045] Fig. 7 is an exploded perspective view showing the drive unit 2. In Fig. 7, in order to improve the visibility of the drawing and facilitate understanding of the invention, dashed dotted lines indicating 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 connection between the bent portions 32b of the inner yoke arranged at both ends in the Z direction, are omitted.

[0046] The magnetic flux passing portion 31a of the outer yoke and the magnetic flux passing portion 31a of the inner yoke are pressure-welded and fixed by laser welding or the like. A magnet 40 is adhesively fixed to each of both ends in the X direction of the magnetic flux passing portion 32a, and an air-core coil 42 is adhesively fixed to the center of the magnetic flux passing portion 32a in the X direction. Coil terminals 43 are adhesively fixed to both ends in the Y direction of the coil 42, and the start and end of the coil winding are soldered to the coil terminals 43, respectively.

[0047] Then, the armature 45 is disposed so as to pass through a hole penetrating in the X direction formed in the coil 42 forming a part of the structural part. A spring engagement portion 45a is formed in a concave shape at both ends in the Y direction of the armature 45 slightly inside the ends in the X direction. A pair of springs 48 is disposed between the outer yoke 31 and the armature 25, and engages with the spring engagement portion 45a of the armature at both ends in the X direction and engages with the spring engagement portion 31b of the outer yoke at both ends in the Y direction. Finally, the four bent portions 32b provided on the inner yokes 32 disposed at both ends in the Z direction are pressed against each other and fixed by laser welding or the like, whereby the drive unit 2 is completed.

[0048] In the drive unit 2, the pair of springs 48 are sandwiched between the outer yoke 31 and the armature 45 with a predetermined amount of displacement in the Z direction. The armature 45 receives repulsive forces from the pair of springs 48 in the Z direction, and is held at a position where these repulsive forces are balanced with an appropriate gap between it and the structural part.

[0049] Fig. 8 is a diagram for explaining the second embodiment in comparison with a comparative example. Fig. 8(A) is a perspective view showing a yoke 30' in an electromechanical transducer as a comparative example, and Fig. 8(B) is a side view showing the yoke 30' next to the yoke 30 of the second embodiment. Note that the symbols (W1, W2, H, T, T1, T2, etc.) indicating the dimensions of each part shown in Fig. 8 are not related to the symbols shown in Fig. 4.

[0050] The yoke 30' of the comparative example is intended to ensure, with one component, the thickness of the magnetic flux passing portion ensured by the combined thickness of the two yoke components (outer yoke 31 and inner yoke 32) in the yoke 30 of the embodiment. For this reason, the yoke 30' of the comparative example is formed by processing a single plate material having a predetermined thickness T', and has two bent portions 30b' on each side of the magnetic flux passing portion 30a' in the Y direction, and a spring engagement portion 30c' at each intermediate position between the two bent portions 30b'.

[0051] Since the bent portion 30b' is formed by bending a plate material with a thickness T', the dimension in the Y direction at the tip thereof is equal to the thickness T'. Therefore, a large strength is ensured for the bent portion 30b', but such strength is not required. Further, the height H' of the portion protruding above the magnetic flux passing portion 30a' of the bent portion 30b' 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 where the bent portion 30b' of the yoke 30' is provided is the size obtained by adding the dimension required for bending the thickness T' to the dimension W1' in the Y direction at the magnetic flux passing portion 30a'.

[0052] On the other hand, in the yoke 30 of the second embodiment, the magnetic flux passing portion 31a of the outer yoke formed of a plate material with a thickness T1 that can give the spring engaging portion 31b a desired strength and the magnetic flux passing portion 32a of the inner yoke formed of a plate material with a thickness T2 are fixed, and the shortage in thickness is compensated by the thickness of the magnetic flux passing portion 32a of the inner yoke. The thickness T2 of the inner yoke 32 is thinner than the thickness T1 of the outer yoke 31, but even with the thickness T2, the strength required for the bent portion 32b can be sufficiently ensured. According to such a yoke 30, the cross-sectional area (the shaded portion 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'), and while sufficient strength is ensured for each of the spring engaging portion 31b and the bent portion 32b, the protruding dimension W2 in the Y direction at the position where the bent portion 32b is provided can be suppressed to be smaller by the amount by which the thickness T2 of the plate material to be bent is reduced (W2 < W2'). Further, it becomes easier to design the height H of the portion protruding above the magnetic flux passing portion 32a of the bent portion 32b to be larger 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, it is possible to reduce the difficulty in manufacturing parts and, as a result, miniaturize the drive unit and thus the electromechanical converter as a whole.

[0053] 〔Third Embodiment〕 Fig. 9 is a perspective view showing a driving section (driving section 3) in an electromechanical transducer of a third embodiment. The driving section 3 is composed of one pair (two pieces) of yokes 50, two pairs (four pieces) of magnets 60 (some of the magnets 60 are not shown in Fig. 9 because they cannot be seen due to the angle), a coil 62, an armature 65, two pairs (four pieces) of springs 68, and one pair (two pieces) of side plates 70. Each yoke 50 is formed from a single plate material.

[0054] That is, the third embodiment is common to the first embodiment described above in that the drive unit is made up of two pairs of springs, but is significantly different from the first embodiment in that each yoke 50 is made of a single plate material and that a pair of side plates 70 is provided, and therefore the shapes and sizes of other components are also different from those in the first embodiment. Below, a description of the points in common with the first embodiment will be omitted as appropriate.

[0055] A pair of yokes 50 are disposed at both ends in the Z direction. A coil 62 is fixed inside the pair of yokes 50 and at the center in the X direction. Two pairs of magnets 60 are fixed inside the pair of yokes 50 and at both ends in the X direction. A pair of side plates 70, which will be described later, are added to the yokes 50, magnets 60, and coils 62 thus disposed integrally to form a structural part.

[0056] The armature 65 is disposed so as to penetrate the internal space of the structural part. Two pairs of springs 68 are disposed 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 a role of positioning and fixing the pair of yokes 50, and is disposed at both ends in the Y direction with the coil terminals 63 exposed from the openings thereof, and is fixed to the side surfaces in the Y direction of each yoke 50 after determining the positions and intervals of the pair of yokes 50. In this manner, the drive part 3 is constituted by the armature 65 and the springs 68 added to the structural part.

[0057] In the third embodiment, the yoke 50 is formed from a single plate material without bending, so that the manufacture of the yoke is easier than that in the first embodiment. The configuration of the side plate 70 and the connection relationship between the components constituting the drive unit 3 will be described in detail later with reference to other drawings.

[0058] FIG. 10 is a perspective view showing the side plate 70. As shown in FIG.

[0059] The side plate 70 has an opening 70a at the center thereof for exposing the coil terminal, a fixed portion 70b which is formed to surround the opening 70a and is fixed to a pair of yokes 50, bending portions 70c which are provided at symmetrical positions on both sides of the fixed portion 70b in the X direction and which protrude from parts of both side surfaces of the fixed portion 70b in the X direction and are bent in the Y direction, and a spacer portion 70d which is provided at the Y direction end of the bending portion 70c and has a predetermined length L1 in the Z direction and which determines the spacing and position of the pair of yokes 50 to ensure a space between them.

[0060] Each of these portions of the side plate 70 is formed by performing various processes on a single plate material. The thickness of the side plate 70 is set to be significantly thinner than the thickness of the yoke 50. The material of the side plate 70 is, for example, a stainless steel material such as SUS301 material.

[0061] Fig. 11 is an exploded perspective view showing the driving unit 3. Note that in Fig. 11, the dashed dotted line showing the connection between the side plate 70 and the yoke 50 is omitted.

[0062] The yoke 50 is formed from a single plate material and has a magnetic flux passing portion 50a having a substantially flat rectangular shape through which magnetic flux passes, and a spring engagement portion 50b formed at each of the central portions of both ends in the X direction of the magnetic flux passing portion 50a for engaging a spring 68. A magnet 60 is adhesively fixed to each of both ends in the X direction of the magnetic flux passing portion 50a, and an air-core coil 62 is adhesively fixed to the central portion in the X direction of the magnetic flux passing portion 50a. Coil terminals 63 are adhesively fixed to both ends in the Y direction of the coil 62, and the start and end of the coil winding are soldered to the coil terminals 63, respectively.

[0063] On top of that, an armature 65 is disposed so as to pass through a hole penetrating in the X direction formed in a coil 62 forming a part of the structural section. A spring engagement portion 65a that is notched in a concave shape is formed at both ends in the Y direction slightly inside the ends in the X direction of the armature 65. Two pairs of springs 68 are disposed between the yoke 50 and the armature 65 at both ends in the X direction and engage with the spring engagement portions 50b, 65a of both.

[0064] In addition, side plates 70 are arranged on both sides in the Y direction of the integrally arranged yoke 50, magnet 60, and coil 62. The side plates 70 are first arranged so that the coil terminals 63 are exposed from the openings 70a, and the spacer portions 70d are inserted between the pair of yokes 50 and aligned with a predetermined position of the magnetic flux passing portion 50a. This maintains a predetermined gap between the two yokes 50. The fixing portions 70b are then fixed to the side surfaces of the magnetic flux passing portions 50a by laser welding or the like, and the drive portion 3 is completed.

[0065] [Fourth embodiment] Fig. 12 is a perspective view showing a driving section (driving section 4) in an electromechanical transducer of the fourth embodiment. The driving section 4 is composed of a pair (two) of yokes 80, two pairs (four) of magnets 90 (some of the magnets 90 are not shown in Fig. 12 because they cannot be seen due to the angle), a coil 92, an armature 95, a pair (two) of springs 98, and a pair (two) of side plates 100. Each yoke 80 is formed from a single plate material.

[0066] That is, the fourth embodiment is common to the second embodiment described above in that the springs constituting the drive unit are a pair, but is significantly different from the second embodiment in that each yoke is formed from a single plate material and that a pair of side plates is provided, and therefore the shapes and sizes of other components are also different from those in the second embodiment. Also, the fourth embodiment is common to the third embodiment described above in that each yoke is formed from a single plate material and that a pair of side plates is provided, but is significantly different from the third embodiment in that the springs constituting the drive unit are a pair. Below, explanations of the points in common with the second and third embodiments will be omitted as appropriate.

[0067] A pair of yokes 80 are disposed at both ends in the Z direction. A coil 92 is fixed inside the pair of yokes 80 and at the center in the X direction. Two pairs of magnets 90 are fixed inside the pair of yokes 80 and at both ends in the X direction. A pair of side plates 100 (described later) are added to the yokes 80, magnets 90, and coils 92 thus disposed integrally to form a structural part.

[0068] The armature 95 is disposed so as to penetrate the internal space of the structural part. The pair of springs 98 are disposed between the structural part (more precisely, the yoke 80) and the armature 95. The pair of side plates 100 play a role in positioning and fixing the pair of yokes 80, and are disposed at both ends in the Y direction with the coil terminals 93 exposed from their openings, and are fixed to the Y-direction side surfaces of each yoke 80 after determining the positions and intervals of the pair of yokes 80. In this manner, the drive part 4 is constituted by the armature 95 and the springs 98 added to the structural part.

[0069] In the fourth embodiment, the yoke 80 is formed from a single plate material without bending, so that the yoke can be manufactured more easily than in the second embodiment. Also, since the springs 98 constituting the driving unit are provided as a pair, the assembly of the structure is easier than in the third embodiment, so that the fourth embodiment is suitable for a smaller electromechanical converter. The configuration of the side plate 100 and the connection between the components constituting the driving unit 4 will be described in detail later with reference to other drawings.

[0070] FIG. 13 is a perspective view showing the side plate 100. As shown in FIG.

[0071] The side plate 100 has an opening 100a that exposes the coil terminals at its center, a fixed portion 100b that surrounds the opening 100a and is formed by cutting out one central portion on each side in the Z direction to be concave, a bent portion 100c that is provided at one symmetrical position on each side of the fixed portion 100b in the X direction, protrudes from a part of each side surface of the fixed portion 100b in the X direction and bends in the Y direction, and a spacer portion 100d that is provided at the end of the bent portion 100c in the Y direction and has a predetermined length L2 in the Z direction, and determines the interval and position of the pair of yokes 80 to ensure a space between them. The notch formed in the fixed portion 100b is for receiving a spring engagement portion that protrudes from the yoke 80 in the Y direction.

[0072] Each of these portions of the side plate 100 is formed by performing various processes on a single plate material. Moreover, the thickness of the side plate 100 is set to be considerably thinner than the thickness of the yoke 80.

[0073] Fig. 14 is an exploded perspective view showing the driving unit 4. Note that in Fig. 14, the dashed dotted line showing the connection between the side plate 100 and the yoke 80 is omitted.

[0074] The yoke 80 is formed from a single plate material and has a magnetic flux passing portion 80a having a substantially flat rectangular shape through which magnetic flux passes, and a spring engagement portion 80b formed at each of the central portions of both ends in the Y direction of the magnetic flux passing portion 80a for engaging a spring 98. A magnet 90 is adhesively fixed to each of both ends in the X direction of the magnetic flux passing portion 80a, and an air-core coil 92 is adhesively fixed to the central portion in the X direction of the magnetic flux passing portion 80a. Coil terminals 93 are adhesively fixed to both ends in the Y direction of the coil 92, and the start and end of the coil winding are soldered to the coil terminals 93, respectively.

[0075] Then, side plates 100 are arranged on both sides in the Y direction of the integrally arranged yoke 80, magnet 90, and coil 92. The side plates 100 are first arranged so that the spring engagement portions 80b of the yokes are received in their concave cutouts while the coil terminals 93 are exposed from the openings 100a, and the spacer portions 80d are inserted between the pair of yokes 80 and aligned with a predetermined position of the magnetic flux passing portions 80a. This maintains a predetermined gap between the two yokes 80.

[0076] The armature 95 is disposed so as to pass through a hole penetrating in the X direction formed in the coil 92 forming a part of the structural part. A spring engagement portion 95a is formed in a concave shape at each end in the Y direction of the armature 95 slightly inside the ends in the X direction. A pair of springs 98 is disposed between the yoke 80 and the armature 95, and engages with the spring engagement portion 95a of the armature at both ends in the X direction and engages with the spring engagement portion 80b of the yoke at both ends in the Y direction. Then, when the fixing portion 100b of the side plate is fixed to the side surface of the magnetic flux passing portion 80a by laser welding or the like, the driving portion 4 is completed.

[0077] [Advantages of the embodiment] In the first and third embodiments, the springs constituting the drive unit correspond to two pairs of electromechanical converters, and in the second and fourth embodiments, the springs constituting the drive unit correspond to one pair of electromechanical converters. Among these, in the first and second embodiments, the yoke is formed of two plates (constituted of two yoke parts), and bending is performed on only one plate (a plate thinner than the thickness of the yoke) to form bent parts, which are fixed to each other, thereby facilitating the manufacture of the components and suppressing the size of the drive unit as a whole. In contrast, in the third and fourth embodiments, the yoke is formed of one plate without bending, and the pair of yokes are fixed to a pair of side plates that are bent from a plate thinner than the yoke, which facilitates the manufacture of the components and suppresses the size of the drive unit as a whole. Thus, the four embodiments can be roughly classified into two types, but all the embodiments have in common that the pair of yokes are fixed to a part formed from a plate thinner than the thickness of the yoke having the bent parts.

[0078] As described above, according to each embodiment, the following effects can be obtained. (1) According to each of the four embodiments, a pair of yokes are fixed at a portion formed from a plate material having a thickness thinner than that of the yokes, so that a component having such a portion can be easily manufactured compared to a case where the portion is formed from a plate material having the same thickness as the yokes. Also, when forming a portion by bending a portion of such a component, the protruding dimension of the component at the portion protruding due to bending is suppressed to be small compared to a case where a plate material having the same thickness as the yokes is bent, so that the driving unit and therefore the electromechanical converter can be made smaller.

[0079] (2) According to the first and second embodiments, each pair of yokes is formed by integrating two yoke parts (an outer yoke and an inner yoke), one of the yoke parts is set to a thickness that can provide a desired strength to the spring engagement part where the repulsive force of the spring acts all the time, and the other yoke part is set to a thickness that compensates for the thickness deficiency in securing a predetermined cross-sectional area that does not saturate the magnetic flux passing through the yoke, so that the yoke as a whole can have a predetermined thickness. This also makes it possible to easily manufacture the yoke parts, and to suppress the protruding dimension of the yoke at the protruding part by bending. As a result, the driving part and therefore the electromechanical converter can be made smaller.

[0080] (3) According to the third and fourth embodiments, the yoke is formed from a single plate material without bending, so that the yoke can be easily manufactured. In addition, the pair of side plates for positioning and fixing the yoke are formed from plate material thinner than the thickness of the yoke by performing various processes, so that the side plates can be easily manufactured with the minimum necessary size. As a result, the drive unit and therefore the electromechanical converter can be miniaturized.

[0081] The present invention is not limited to the above-described embodiments, and can be practiced in various modified forms.

[0082] In the second embodiment described above, the spring engagement portion 31b is provided on the outer yoke 31 and the bent portion 32b is provided on the inner yoke 32, but the spring engagement portion and the bent portion may be provided on the same yoke part. For example, the spring engagement portion and the bent portion may be provided on the outer yoke. In such a configuration, the inner yoke is formed in approximately the same shape as the shape of the magnetic flux passing portion of the outer yoke.

[0083] The springs 28, 48, 68, 98 in each of the above-described embodiments may be made of elastic members other than leaf springs, so long as they can provide a restoring force corresponding to the displacement of the armature caused by the action of the magnetic force of the magnet.

[0084] The driving units 1, 2, 3, and 4 in the above-described embodiments may be used for purposes other than electromechanical transducers. For example, they may be used as part of an electroacoustic transducer that converts electrical vibrations into sound and outputs the sound to the outside.

[0085] Furthermore, the materials and numerical values ​​given as examples of the components of the drive units 1, 2, 3, and 4 are merely examples, and it goes without saying that suitable modifications can be made when implementing the present invention. [Explanation of symbols]

[0086] 1, 2, 3, 4 Drive unit 10,30,50,80 York 11,31 Outer yoke 12,32 Inner Yoke 20,40,60,90 Magnet 22,42,62,92 coil 23,43,63,93 Coil terminal 25,45,65,95 Armature 28,48,68,98 Spring 70,100 Side plate

Claims

1. A pair of magnets, a pair of yokes, each of which is formed by stacking a plurality of yoke parts on each other at flat plate-shaped portions, for guiding magnetic flux from the magnet; an air-core coil to which an electrical signal is supplied; an armature disposed inside the pair of yokes and penetrating an internal space of a structural part in which the magnet and the coil are integrally disposed; a pair of elastic members each of which engages with the structure and the armature; Equipped with Each of the yokes is An electromechanical transducer characterized in that by overlapping the multiple yoke components, an area that does not cause magnetic flux saturation is ensured in a cross section perpendicular to the direction of magnetic flux passage at a portion through which magnetic flux passes.

2. 2. The electromechanical transducer of claim 1, Each of the yokes is any one of the yoke components has a bent portion protruding from a symmetrical position on both side surfaces in a predetermined second direction perpendicular to a first direction which is a superposition direction of the yoke components, and bent in the first direction to extend a predetermined length; The pair of yokes are An electromechanical transducer, characterized in that the end faces of the bent portions are fixed to each other.

3. 3. The electromechanical transducer of claim 2, Each of the yokes is the yoke component is disposed on an outer side of the structural portion, and the engaging portion protrudes from a predetermined position on each of both side surfaces in the second direction of the yoke component; The elastic member is An electromechanical transducer that engages with the engagement portion.

Images