Electromechanical converter

Abstract

To provide a large-sized electromechanical transducer, which is configured so that an armature is displaced properly.SOLUTION: An electromechanical transducer 100 is constituted of a structure part in which a pair of yokes 110, two pairs of magnets 120, a coil 130 and the like are integrally arranged, an armature 140 penetrating through an inner space of the structure and two pairs of springs 150 arranged between the structure part and the armature 140. Two arm parts of the armature 140 have through-holes, where bushes 142 are fixed to the through-holes respectively, from both upper and lower sides. In a state where shafts 144 are penetrated through center parts of the bushes and coil springs 150 are arranged respectively outside the bushes 142, both end parts of the shafts 144 are fixed to upper and lower pressing plates 160. When AC currents are supplied to the coil 130, the armature 140 is displaced in a vertical direction alternately and is vibrated. However, the arranged bush 142 can restrict the armature 140 from moving only in an axial direction of the shaft 144, which can prevent the armature from staggering in an unintended direction.SELECTED DRAWING: Figure 1

Description

Technical Field

[0005]

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

Background Art

[0002] Conventionally, in this type of electromechanical transducer, the restoring force of a leaf spring has been utilized. For example, an electromechanical transducer in which two pairs of leaf springs are arranged between a structural part in which a yoke, a magnet, and a coil are integrally arranged and an armature (see Patent Document 1), or an electromechanical transducer in which one pair of leaf springs is arranged (see Patent Document 2) is known.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] The above-described prior art structure is particularly effective when the electromechanical transducer is small. However, when the electromechanical transducer is enlarged and the displacement amount of the armature becomes larger than several millimeters, a spring design corresponding thereto is required. However, when using a leaf spring, it is not easy to design a spring that allows a large displacement. Further, in the case of the above-described structure, displacement of the armature in a direction other than the intended direction caused by slight asymmetry of components or assembly, or asymmetry of load, etc. cannot be ignored.

[0005] This invention has been made in view of these problems, and aims to provide a technology for appropriately displacing the armature in a large electromechanical transducer. [Means for solving the problem]

[0006] To solve the above problems, the present invention employs the following electromechanical converter. Note that the following statements in parentheses are merely examples, and the present invention is not limited thereto.

[0007] The electromechanical transducer of the present invention comprises at least a structural part in which a pair of magnets, a yoke that guides the magnetic flux from the pair of magnets, an air-core coil, and a plurality of shafts are integrally arranged; an armature having arms protruding from both ends in a predetermined direction and holes drilled in the arms, and arranged in the internal space of the structural part; and elastic members arranged on the outer periphery of a predetermined member, each of which is placed in a hole, and joined to the structural part and the arms.

[0008] According to this embodiment of the electromechanical transducer, a predetermined member is placed in a hole in the arm of the armature, and an elastic member (for example, a coil spring or a leaf spring) is placed on the outer circumference of the predetermined member and joined to the structural part and the arm. As a result, the armature, which is displaced by the attractive force from the magnet and the repulsive force from the elastic member, is displaced along the direction of the central axis of the predetermined member, preventing the armature from being displaced in an unintended direction, and thus vibrations with small deviations (fluctuations) in the direction of vibration can be obtained.

[0009] Preferably, in the electromechanical transducer described above, at least some of the multiple shafts penetrate the holes, and the elastic members are arranged on the outer circumference of some of the shafts.

[0010] In this embodiment of the electromechanical transducer, a portion of the shaft passes through a hole in the arm of the armature, and an elastic member is arranged on its outer circumference. This restricts the movement of the armature to only the axial direction of the shaft, thereby enabling vibrations with small fluctuations in the direction of vibration.

[0011] More preferably, the electromechanical transducer further comprises a bush fixed to the hole, wherein a portion of the shaft penetrates the center of the bush, and the elastic member is arranged on the outer circumference of the shaft that penetrates the center of the bush.

[0012] In this embodiment of the electromechanical transducer, a bushing is fixed to a hole in the arm of the armature, and a portion of the shaft passes through its center. This allows the movement of the armature to be reliably restricted only in the axial direction of the shaft, and also makes the movement of the armature smoother, resulting in vibrations with less vibrational deviation (variation).

[0013] More preferably, the electromechanical converter further comprises a columnar or cylindrical guide member fixed to the arm and / or the structural member, wherein the elastic member is arranged on the outer or inner circumference of the guide member.

[0014] In this embodiment of the electromechanical converter, the guide member is fixed to the structural part and / or to the arm of the armature, and the elastic member is arranged on the outer or inner circumference of such guide member. This prevents the elastic member from slipping and allows the repulsive force from the elastic member to act only in the intended direction. [Effects of the Invention]

[0015] As described above, according to the present invention, the armature can be appropriately displaced in a large electromechanical transducer. [Brief explanation of the drawing]

[0016] [Figure 1] This is a perspective view showing the electromechanical converter 100 of the first embodiment. [Figure 2] This is an exploded perspective view of the armature 140 and its surroundings. [Figure 3] This is an exploded perspective view of the electromechanical converter 100. [Figure 4] This is a perspective view showing the electromechanical converter 200 of the second embodiment. [Figure 5] It is an exploded perspective view of the armature 240 and its surroundings. [Figure 6] It is an exploded perspective view of the electromechanical transducer 200. [Figure 7] It is a perspective view showing the electromechanical transducer 300 of the third embodiment. [Figure 8] It is a perspective view showing the armature 340. [Figure 9] It is a perspective view showing the electromechanical transducer 400 of the fourth embodiment. [Figure 10] It is a view showing the electromechanical transducer 500 of the fifth embodiment. [Figure 11] It is a view showing the electromechanical transducer 600 of the sixth embodiment. [Figure 12] It is a view showing the electromechanical transducer 700 of the seventh embodiment. [Figure 13] It is a view showing the vibrator 800 using the electromechanical transducer 500. [Figure 14] It is a view showing the vibrator 900 using the electromechanical transducer 500. [Figure 15] It is a view showing the speaker unit 1000 using the electromechanical transducer 600.

Embodiments for Carrying Out the Invention

[0017] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that each of the following embodiments is a preferred example, and the present invention is not limited to this example. Also, for convenience of explanation, the directions related to the structure may be shown as up, down, left, and right along the directions on the paper surface of each drawing.

[0018] 〔First Embodiment〕 FIG. 1 is a perspective view showing the electromechanical transducer 100 of the first embodiment. The electromechanical transducer 100 has a substantially symmetrical structure vertically, with an armature 140 positioned within the internal space of a structural section in which two (one pair) yokes 110, four (two pairs) magnets 120, an air-core coil 130, etc., are integrally arranged. Furthermore, four (two pairs) springs 150 are positioned between the structural section and the armature 140. In the following description, the direction in which the armature 140 penetrates the internal space of the structural section will be referred to as the "X direction," the direction in which the two yokes 110 face each other will be referred to as the "Z direction," and the direction perpendicular to both the X and Z directions will be referred to as the "Y direction."

[0019] Figure 2 is an exploded perspective view of the armature 140 and its surroundings. The armature 140 has a flat plate shape with a middle section 140a and two arms 140b that extend outward from both ends, slightly narrower in width, and each arm 140b has a through hole 140c drilled in it. After the armature 140 is positioned through the air core of the coil 130, one bush 142 is positioned on each through hole 140c from both the top and bottom sides and fixed with adhesive or the like, and a shaft 144 is passed through the center of the two bushes 142. Then, a coil spring is placed on the outer circumference of each bush 142, and each arm 140b is joined to the coil spring 150 on both the top and bottom sides.

[0020] Figure 3 is an exploded perspective view of the electromechanical transducer 100. Note that in Figure 3, some parts of the lower section are not disassembled due to space constraints, but the assembly of these parts is the same as that of the upper section. Also, in Figure 3, the parts shown in Figure 2 are not disassembled, and the figure shows the armature 140 positioned through the air core of the coil 130, with bushings 142 fixed to both ends of the armature 140 and the shaft 144 passed through it.

[0021] Two magnets 120 are fixed to each yoke 110 with adhesive to the surface facing the armature 140, i.e., the inner surface of the completed electromechanical transducer 100 (hereinafter, the inner or outer surface in the completed state may be simply referred to as "inner" or "outer"). Each yoke 110 has two protruding portions at each end in the X direction, and fastening holes 110a are drilled at the tips of these portions. In addition, the retaining plate 160, which is positioned on the outside of each yoke 110, has three fastening holes at each end in the X direction. Two of these fastening holes 160a are drilled at positions corresponding to fastening holes 110a, and fastening hole 160b, located approximately in the center of the two fastening holes 160a, is drilled at a position corresponding to the screw hole of the shaft 144. The retaining plate 160 is placed on the outside of the yoke 110, and bolts 162 are passed through the four fastening holes 160a, 110a and fastened with nuts 164 to fix it to the yoke 110.

[0022] Furthermore, a coil 130 is fixed to each yoke 110 with adhesive in a position sandwiched between two magnets 120 fixed to the inner surface. Then, one coil spring 150 is placed on each of the upper and lower sides of the outer circumference of four bushings 142 fixed to the armature 140, which is positioned to penetrate the air core of the coil 130. In this state, the two retaining plates 160 to which the yoke 110 is fixed sandwich the two shafts 144 that pass through the center of the bushings 142 fixed to both ends of the armature 140 from the outside, and are fastened and fixed to the screw holes of the shafts 144 with bolts 162 that pass through each fastening hole 160b. Each coil spring 150 is compressed beyond its free length, with one end joined to the arm portion 140b of the armature and the other end joined to the retaining plate 160. In this embodiment, the components other than the armature 140, bush 142, and coil spring 150, namely the yoke 110, magnet 120, coil 130, shaft 144, retaining plate 160, bolt 162, and nut 164, are integrated to form the structural part.

[0023] With this structure, the distance between the pair of retaining plates 160, and consequently the distance between the pair of yokes 110, is determined by the length of the shaft 144, and the armature 140 is held in a position where the repulsive forces from the two coil springs 150 positioned above and below are balanced. In addition, the coil 130 has a gap that prevents it from coming into contact with the armature 140 even when the armature 140 is displaced vertically.

[0024] Assuming that the stiffness (spring constant) of the pair of coil springs 150 above and below the armature 140 is the same, approximately equal spacing gaps 170 are provided between the armature 140 and the two pairs of magnets 120 above and below it. The yoke 110, magnets 120, coils 130, armature 140, and gaps 170 constitute the magnetic circuit of the electromechanical transducer 100. Each retaining plate 160 deflects slightly when subjected to force from the two coil springs 150 on the left and right, but is designed to have sufficiently high rigidity so that this deflection is well smaller than the displacement of the coil springs 150.

[0025] The two pairs of magnets 120 (one pair on the left and one on the right) are magnetized in opposite directions, and the armature 140 is subjected to a repulsive force from the pair of coil springs 150 and an attractive force from the pair of magnets 120. When no current flows through the coil 130, the attractive forces acting on the armature 140 from the upper and lower magnets 120 are adjusted to balance each other, so the position of the armature 140 is approximately the same as the position where the forces from the coil springs 150 are balanced. Here, for example, if the pair of magnets 120 on the left are magnetized upward and the pair of magnets 120 on the right are magnetized downward, and if current is passed through the coil 130 (an electrical signal is input) and a magnetic flux is generated that moves the armature 140 from right to left, the armature 140 will be subjected to an upward force and displaced upward. In contrast, if the direction of the current is reversed, the armature 140 is subjected to a downward force and displaced downwards.

[0026] Two pairs of coil springs 150, positioned between the armature 140 and the structural part, repel relative displacement between the armature 140 and the structural part. When the armature 140 is displaced relative to the structural part, the repulsive force acts in the direction that returns the displacement to its original position. Staticly, the armature 140 is displaced relative to the structural part until the magnetic force acting between the armature 140 and the structural part due to electrical input balances out the repulsive force from the coil springs 150. If an alternating current is passed through the coil 130 (if an alternating signal is input), the armature 140 vibrates by alternately displacing relative to the structural part.

[0027] In this embodiment, since bushings 142 are provided on both the upper and lower sides of both ends (each arm portion 140b) of the armature 140, even when the displacement of the armature 140 is large, the movement of the armature 140 relative to the structural part is restricted to the axial direction of the shaft 144 only, allowing the armature 140 to be smoothly displaced only in the axial direction of the shaft 144, and preventing the armature 140 from wobbling in an unintended direction.

[0028] Furthermore, in this embodiment, the components excluding the armature 140, bush 142, and coil spring 150 are integrally formed to constitute the structural part. However, if the amount of displacement between the armature 140 and the structural part increases, the air gap between the coil 130, which is part of the structural part, and the armature 140 also increases. As a result, the resistance component of the coil 130 relative to the number of turns increases, which leads to a problem in that the driving efficiency of the electromechanical transducer 100 deteriorates. On the other hand, since it is desirable for the mass of the armature that displaces relative to the structural part to be lighter, the coil 130 is usually fixed to the yoke 110 as part of the structural part. However, if it is fixed to the armature 140, although the mass of the armature increases, the resistance component of the coil 130 relative to the number of turns can be reduced, thus solving the above-mentioned problem. Thus, there are advantages and disadvantages to fixing the coil 130 to either the structural part or the armature. Therefore, the coil 130 may be fixed to the structural part or to the armature.

[0029] Furthermore, according to the structure of this embodiment, it is possible to easily accommodate changes in the gap length between the armature 140 and the yoke 110, for purposes such as increasing the displacement of the armature 140. In the structures of the above-mentioned Patent Documents 1 and 2 (hereinafter referred to as "conventional structures"), the joints between the spring in the yoke and the joints between the upper and lower yokes were formed by press working or the like according to a predetermined gap length, so if the gap length was to be changed, the mold for the yoke had to be remanufactured. In contrast, in the structure of this embodiment, although it is necessary to change the dimensions of the components according to the change in gap length, if the gap length is only slightly changed, the yoke and armature can be used as is without being changed, and changes to other parts can also be accommodated relatively easily.

[0030] The yoke 110 and armature 140 form part of the magnetic circuit and are therefore made of a soft magnetic material such as electromagnetic pure iron or 3% silicon steel. For example, a neodymium magnet is used for the magnet 120, self-fusing copper wire for the coil 130, brass or stainless steel for the shaft 144, spring stainless steel (such as SUS301) for the spring 150, and stainless steel for the retaining plate 160. It is preferable to use non-magnetic materials for the shaft 144 and the retaining plate 160.

[0031] Next, various other embodiments of electromechanical transducers will be described. All of the other embodiments of electromechanical transducers have a substantially symmetrical structure vertically, and the armature is positioned through the internal space of a structural part in which a yoke, magnet, air-core coil, etc., are integrally arranged, and a spring is positioned between the structural part and the armature, and an air gap is provided between the coil and the armature so that the armature does not come into contact with the coil even when it is displaced vertically, which is common to the electromechanical transducer 100 of the first embodiment, but the types, number, and shapes of the components differ in various ways.

[0032] In the following description, explanations of points common to the first embodiment will be omitted as appropriate. Furthermore, for components of other embodiments that are equivalent to those of the first embodiment, the last two digits of their reference numerals will be the same as those of the first embodiment. For example, the yoke is represented by a reference numeral with the last two digits being "10", the armature by a reference numeral with the last two digits being "40", and each arm portion that the armature has at both ends in the X direction is represented by a reference numeral with the last two digits being "40b".

[0033] [Second Embodiment] Figure 4 is a perspective view showing the electromechanical converter 200 of the second embodiment. The electromechanical transducer 200 differs particularly from the electromechanical transducer 100 of the first embodiment (Figure 1) in the shape of the armature and the arrangement of eight (four pairs) coil springs between the structural part and the armature. In addition, other components also differ in shape and number in relation to these differences.

[0034] Figure 5 is an exploded perspective view of the armature 240 and its surroundings. The armature 240 has a flat plate shape with an intermediate section 240a, two first arms 240b protruding from both sides of the intermediate section 240a in the X direction, and second arms 240d connected to both sides of the intermediate section 240a in the Y direction by thin sections. Through holes 240c are drilled in each of the first arms 240b and each of the second arms 240d. After one coil 230 is placed on each side of the armature 240 in the X direction, a cylindrical shaft 244 is passed through each through hole 140c. Then, coil springs 250 are placed on the outer circumference of each shaft 244 that has passed through the armature 240 from both the upper and lower sides, and each of the first arms 240b and each of the second arms 240d are joined to the coil springs 250 on both the upper and lower sides. The armature 240 can be displaced smoothly and without play in the axial direction of the four shafts 244.

[0035] Figure 6 is an exploded perspective view of the electromechanical transducer 200. Note that in Figure 6, the parts shown in Figure 5 are not disassembled, and the diagram shows two coils arranged to surround the middle part of the armature 240, with the shaft 244 passing through the four arms of the armature 240.

[0036] Two magnets 220 are fixed to the inner surface of each yoke 210 with adhesive, and two coils 230 are fixed with adhesive in a position between these magnets 220. Then, four shafts 244 are passed through an armature 240 which is positioned through the air cores of the two coils 230, and coil springs 250 are positioned above and below each of these shafts 244.

[0037] Each retaining plate 260, positioned on the outside of each yoke 210, is substantially circular in shape and has four equally spaced fitting holes 260a on its outer edge, as well as eight upright portions 260d formed by bending a portion of the plate inward. Each yoke 210 is fitted and fixed inside the eight upright portions 260d, and the tip of each shaft 244 is fitted into the fitting holes 260a and fixed by laser welding or the like.

[0038] The two coils 230 are electrically connected in series or in parallel so as to generate magnetic flux in the same direction with respect to the electrical input. The position in which the armature 240 is held in the electromechanical transducer 200, and the principle by which the armature 240 is displaced vertically, are the same as those of the electromechanical transducer 100 in the first embodiment.

[0039] [Third Embodiment] Figure 7 is a perspective view showing the electromechanical converter 300 of the third embodiment. Figure 8 is a perspective view showing the armature 340, which is part of the electromechanical converter 300. The electromechanical transducer 300 is a modified version of the electromechanical transducer 200 of the second embodiment (Figure 4), and differs from the electromechanical transducer 200 in the shape of the armature, the shape and number of coils, and the number of coil springs.

[0040] Specifically, as shown in Figure 8, the armature 340 has an intermediate portion 340a and two arms 340b protruding from both sides in the X direction. Each arm 340b has a through hole 340c, but the intermediate portion 340a does not have an arm connected in the Y direction. Due to this shape, as shown in Figure 7, the armature 340 is joined to the coil spring 350 by its two arms 340b, so two pairs (four) of coil springs 350 are provided, corresponding to the two arms 340b. Furthermore, since the armature 340 does not have arms in the Y direction, there is no need to divide the coil into two to sandwich such arms, so the coil 330 has the same shape as the coil 130 of the first embodiment.

[0041] [Fourth Embodiment] Figure 9 is a perspective view showing the electromechanical converter 400 of the fourth embodiment. The electromechanical transducer 400 is a modified version of the electromechanical transducer 300 of the third embodiment (Figure 7), and differs from the electromechanical transducer 300 in the structure that restricts the movement of the armature (the component passed through the coil spring) and the number of shafts.

[0042] Specifically, two shafts 444 that do not pass through the coil spring 450 are fixed to the retaining plate 460. As a result, the distance between the pair of retaining plates 460, and consequently the distance between the pair of upper and lower magnets 420, is determined by the length of the shafts 444. In this embodiment, there are no shafts inside each coil spring 450, but two guides 446 are arranged, one fixed to the armature 440 and the other fixed to the retaining plate 460. A total of eight guides 446 (four pairs) are arranged, corresponding to the four coil springs. By providing the guides 446, displacement of the coil springs 450 can be prevented. The shape of the armature 440 is the same as that of the armature 340 (Figure 8), and the through holes are used for positioning the guides 446. The guides 446 are formed from materials such as metal or resin, and in the case of metal, they are fixed by laser welding, while in the case of resin, they are fixed with adhesive. The guide may also be placed on the outside of the coil spring 450.

[0043] [Fifth Embodiment] Figure 10 shows an electromechanical transducer 500 according to the fifth embodiment. Of these, (A) is a perspective view showing the electromechanical transducer 500, and (B) is a vertical cross-sectional view along line XX in (A). The electromechanical transducer 500 is a modified version of the electromechanical transducer 200 of the second embodiment (Figure 4), and differs from the electromechanical transducer 200 in its structure for restricting the movement of the armature and in its shaft fixing configuration.

[0044] Specifically, a linear bush 548 is fixed to a through-hole in the armature 540, and a shaft 544 passes through the center of the linear bush 548. This structure allows for smoother relative movement along the shaft 544 between the armature 540 and the structural part. Furthermore, the shaft 544 is more firmly fixed to the retaining plate 560 using bolts 562.

[0045] [Sixth Embodiment] Figure 11 shows an electromechanical transducer 600 according to the sixth embodiment. (A) is a perspective view of the electromechanical transducer 600, and (B) is a vertical cross-sectional view along the line XI-XI in (A). The electromechanical transducer 600 is a modified version of the electromechanical transducer 200 of the second embodiment (Figure 4), and differs from the electromechanical transducer 200 in its structure for restricting the movement of the armature.

[0046] Specifically, one bushing 642 and one guide 646 are placed inside each coil spring 650, and each shaft 644 passes through the centers of two bushings 642 placed inside two coil springs 650 that form an upper and lower pair. A total of eight bushings 642 are arranged and fixed to the armature 640. On the other hand, a total of eight guides 646 are arranged on the retaining plate 660 side and fixed to the retaining plate 660 or the shaft 644. This structure makes it possible to more reliably prevent displacement of the coil springs 650 and to smooth out any relative movement along the shaft 644 that may occur between the armature 640 and the structural part.

[0047] [Seventh Embodiment] Figure 12 shows the electromechanical converter 700 according to the seventh embodiment. The electromechanical transducer 700 is a modified version of the electromechanical transducer 200 of the second embodiment (Figure 4), and differs from the electromechanical transducer 200 in that a leaf spring is provided instead of a coil spring.

[0048] Specifically, two leaf springs 752, arranged in a pair, are positioned to sandwich the armature 740. The leaf springs 752 are roughly annular in shape, with portions bent in opposite directions alternately formed at approximately equal intervals. The first portion 752a, which is the bent end of one portion, is joined to the retaining plate 760, and the second portion 752b, which is the bent end of the other portion, is joined to the first arm portion 740b of the armature 740. This structure also allows for the generation of vibrations (driving force) of a desired magnitude while appropriately restricting the movement of the armature 740.

[0049] [Examples of applications for electromechanical converters] Next, we will describe an example of the application of the electromechanical converter of the embodiment described above. The electromechanical converter is applied as a drive unit for various devices, and the tips of each arm of the armature act as vibration transmission units.

[0050] Figure 13 shows a vibrator 800 using the electromechanical converter 500 (Figure 10) of the fifth embodiment as the drive unit. Of these, (A) is a perspective view of the vibrator 800, and (B) shows the inside of the housing 810 that forms the outer shell of the vibrator 800 with a part of it broken open.

[0051] Inside the housing 810 is the electromechanical transducer 500, with the four ends of the armature 540 (more precisely, the ends of the two first arms 540b and the two second arms 540d) sandwiched and fixed between the upper housing 810a and the lower housing 810b. The lead wires of the two coils 530 are soldered to the terminal board 532, and lead wires 534 are soldered to the two electrical input terminals and brought out of the housing 810.

[0052] When electricity is input through the lead wire 534, a driving force is generated between the armature 540 and housing 810 and the structural part. When an AC signal is input, relative vibration is generated between the armature 540 and housing 810 and the structural part, and if the housing 810 is in contact with or fixed to an object such as a diaphragm, that object can be made to vibrate.

[0053] Figure 14 shows a vibration exciter 900 using the electromechanical transducer 500 (Figure 10) of the fifth embodiment as the drive unit. Of these, (A) is a perspective view of the vibration exciter 900, and (B) shows the inside of the housing 910 that forms the outer shell of the vibration exciter 900 with a part of it broken open.

[0054] An electromechanical converter 500 is located inside the housing 910 and is fixed to the bottom of the housing 910. The four ends of the armature 540 (more precisely, the ends of the two first arms 540b and the two second arms 540d) are fixed to the connecting member 930. The housing 910 is also provided with a connector 920 for inputting electricity from the outside, which is connected to the terminal board 532.

[0055] When an AC signal is input through the connector 920, relative vibration occurs between the structural part and the armature 540, etc., and the vibration is transmitted to the tip 940 which is integrally provided with the connecting member 930. By fixing or contacting an object such as an acceleration pickup with the tip 940, vibration can be applied to that object.

[0056] In this application example, the lower retaining plate 560 is slightly modified from the one in the fifth embodiment and subjected to a drawing process, and its outer edge is fixed to the bottom of the housing 910 with bolts. By drawing the retaining plate, the rigidity of the retaining plate and its surrounding area can be further increased.

[0057] Figure 15 shows a speaker unit 1000 using the electromechanical transducer 600 (Figure 11) of the sixth embodiment as the drive unit. Of these, (A) is a perspective view of the speaker unit 1000 seen from the front, (B) is a perspective view of the speaker unit 1000 seen from the rear, and (C) shows the inside of the frame 1010 by enlarging only the peripheral part of the electromechanical transducer 600 shown in (B) and breaking off a part of the frame 1010.

[0058] In this application example, the upper retaining plate 660 is slightly modified from that of the sixth embodiment and subjected to drawing, and its outer surface 660f and the frame 1010 are fixed by laser welding or the like. The four ends of the armature 640 (more precisely, the ends of the two first arms 640b and the two second arms 640d) are fixed with adhesive to one end of a substantially cylindrical connecting part 1030, and the diaphragm 1020 is fixed with adhesive to the other end of the connecting part 1030.

[0059] When an AC signal is input to the coil through a terminal board (not shown), the armature 640 vibrates relative to the structural part fixed to the frame 1010, causing the diaphragm 1020 to vibrate through the connecting part 1030, thereby generating sound pressure.

[0060] As described above, each embodiment provides the following effects. (1) According to the electromechanical transducer 100 of the first embodiment, since bushings 142 are provided on both the upper and lower sides of each arm portion 140b of the armature, even when the displacement of the armature 140 is large, the movement of the armature 140 can be restricted to only the axial direction of the shaft 144.

[0061] (2) In the electromechanical transducer 200 of the second embodiment, the armature 240 has four arms (two first arms 240b and two second arms 240d), and four pairs of coil springs 250 are arranged for the four arms. Compared to the electromechanical transducer 100 of the first embodiment, where two pairs of coil springs are arranged for two arms, the repulsive force from the coil springs can be applied to more locations, and therefore the movement of the armature 240 along the axial direction of the shaft 244 can be made more stable.

[0062] (3) According to the electromechanical transducer 300 of the third embodiment, the armature 340 has two arms 340b, two of the four shafts 344 pass through the arms of the armature 340, and two pairs of coil springs 350 are arranged on the outer circumference of these. This allows the movement of the armature 340 to be restricted only in the axial direction of the shafts 344, while reducing the number of parts and thus reducing manufacturing costs.

[0063] (4) According to the electromechanical transducer 400 of the fourth embodiment, the distance between the upper and lower magnets, which form part of the structure, is determined by the lengths of the two shafts 444, and two guides 446 are arranged inside each coil spring 450, one of which is fixed to the armature 440 and the other is fixed to the retaining plate 460. This prevents displacement of the coil springs 450 and restricts the movement of the armature 440 in a direction along approximately the center of the guide 446 fixed to the retaining plate 460 (direction of the central axis).

[0064] (5) According to the electromechanical transducer 500 of the fifth embodiment, a linear bush 548 is fixed to the through hole of the armature 540, and a shaft 544 passes through its center, so that the friction generated when the armature 540 is displaced along the axial direction of the shaft 544 can be reduced and the movement can be made smoother.

[0065] (6) According to the electromechanical transducer 600 of the sixth embodiment, two bushings 642 and one guide 646 are arranged inside each coil spring 650, the bushings 642 are fixed to the armature 640 and the guide 646 is fixed to the retaining plate 660 or the shaft 644, so that the movement of the armature 440 is restricted only in the axial direction of the shaft 644, while more reliably preventing displacement of the coil springs 650.

[0066] (7) According to each embodiment, the movement of the armature can be restricted to the axial direction of the shaft only, so even in equipment that requires a large output or a large displacement, it is possible to generate high-quality vibrations with small deviations (fluctuations) in the direction of vibration.

[0067] (8) According to the electromechanical converters of each embodiment, the sound quality can be improved in devices such as audio speakers that require a large output compared to the conventional structure described above, and the desired sound quality can be ensured even with a balanced armature type.

[0068] The present invention can be implemented in various ways without being limited to the embodiments described above.

[0069] In the embodiments described above, the armature is formed of a soft magnetic material. However, since only a portion of the armature facing the magnet in the X direction constitutes part of the magnetic circuit, the other parts do not need to be made of a magnetic material. Alternatively, the armature may be constructed by assembling multiple parts, and these parts may work together as a single unit.

[0070] For example, a magnetic material may be used for the part of the armature that constitutes a portion of the magnetic circuit (the part corresponding to the intermediate section in each embodiment), while other materials may be used for the other parts (the parts corresponding to the arms in each embodiment). By using such a configuration, it becomes possible to assemble the armature after arranging the coil around the part corresponding to the intermediate section, thereby increasing the degree of design freedom regarding the plate thickness, shape, etc., of each component that makes up the armature.

[0071] In the first and sixth embodiments described above, a bush is provided on the outer circumference of the shaft. Depending on the size of the electromechanical transducer, a resin sliding bush (sliding bearing) or a ball-circulating linear bush (rolling bearing) may be used for the bush.

[0072] In the seventh embodiment described above, two leaf springs 752 arranged in a pair (one pair) on the upper and lower sides are used as elastic members that provide a repulsive force to the armature 740. However, as in the other embodiments, a bushing may be fixed to the armature and the leaf springs may be arranged on its outer circumference.

[0073] In each embodiment, a coil spring or a leaf spring is used to obtain a restoring force against the relative displacement between the armature and the structural part, but any member that can provide a restoring force is acceptable, and other types of springs or elastic members other than springs may be used.

[0074] The shafts and guides used in each embodiment may be in a substantially cylindrical shape or a substantially cylindrical shape.

[0075] Furthermore, the materials and numerical values ​​listed as examples for the components of the electromechanical transducers 100, 200, 300, 400, 500, 600, and 700 are merely illustrative examples, and it goes without saying that they can be modified as appropriate when implementing the present invention. [Explanation of symbols]

[0076] 100 Electromechanical Converters 110 York 120 magnets 130 coils 140 Armature 142 Bush 144 shaft 150 Coil Springs 160 Pressing plate

Claims

1. At a minimum, a structural part comprising a pair of magnets, a pair of yokes that guide the magnetic flux from the magnets, an air-core coil, and a plurality of shafts arranged integrally, An armature having arms protruding from both ends in a predetermined direction and holes drilled in the arms, and positioned in the internal space of the structural part, Elastic members that form a pair, each positioned on the outer circumference of a predetermined member placed in the hole, and joined to the structural part and the arm part. An electromechanical converter.

2. In the electromechanical converter according to claim 1, The aforementioned multiple shafts are At least a portion of the shaft passes through the hole, The elastic member is An electromechanical transducer characterized by being positioned on the outer circumference side of a portion of the shafts.

3. In the electromechanical converter according to claim 2, The bush is further fixed to the aforementioned hole, Some of the aforementioned shafts Penetrating the center of the bush, The elastic member is An electromechanical transducer characterized by being positioned on the outer circumference of the shaft that penetrates the center of the bush.

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