Electromechanical converter

Abstract

An electromechanical converter 100 comprises: a structure portion 120 integrally formed from a pair of magnets 124, a pair of yokes 122 that guide a magnetic flux caused by the magnets 124, and a coil 128 that is arranged in a space surrounded by the yokes 122 and side plates 126; an armature portion integrally formed from an armature 130 disposed inside the space of the structure portion 120 so as to pass through the coil 128, and housings 110, 112 that internally house the structure portion 120 and the armature 130 in a state of being mutually linked to the armature 130; and leaf springs 140 configured so as to be capable of imparting an elastic restoring force to both the housings 110, 112 and the structure portion 120 in a state of being disposed therebetween, thereby allowing relative vibration between the structure portion 120 and the armature portion.

Description

electromechanical transducer

[0001] The present invention relates to an electromechanical transducer that converts an electrical signal into a mechanical vibration.

[0002] A balanced armature type is known as a prior art electromechanical transducer. A balanced armature type electromechanical transducer has a structure formed by integrally arranging, for example, two pairs of magnets, a pair of yokes that guide the magnetic flux of the magnets, and an air-core coil to which an electric signal is supplied. An armature is disposed to pass through the internal space of the balanced armature, and the armature is supported displaceably by an elastic member disposed between the armature and the yoke (see, for example, Patent Documents 1 and 2).

[0003] Japanese Patent No. 5653543 Japanese Patent Application Laid-Open No. 2018-186378

[0004] The structures of both prior arts are useful in that the restoring force of the elastic member (leaf spring) is applied to the armature placed in the internal space of the structure in both directions of vibration, and the posture of the armature can be stably maintained within the space. Furthermore, in the prior art structures, when the electromechanical converter is used as a vibrator for other equipment (for example, audio equipment), the placement of the leaf spring for applying the restoring force to the armature is thought to restrict the miniaturization and high output of the entire vibrator.

[0005] For example, in the structure of the prior art (Patent Document 1), when the entire vibrator is viewed in a direction perpendicular to the vibration direction of the armature, the space for arranging the leaf springs occupies a fairly large portion. Therefore, the magnets and coils can only be arranged within the remaining, limited space in the entire vibrator. Furthermore, to ensure the arrangement space for these components and still satisfy the required specifications (output performance) of the vibrator, the entire vibrator must be made somewhat large. Conversely, if an attempt is made to fit the entire vibrator into a limited size, there are restrictions on the arrangement space for the magnets and coils in the direction perpendicular to the vibration direction, as described above. Therefore, it becomes difficult to obtain high output that meets the required specifications.

[0006] Therefore, the present invention provides a technique for improving the structural arrangement.

[0007] The present invention provides an electromechanical transducer. The electromechanical transducer comprises a structural part, an armature part, and an elastic member, which are solutions. The structural part and the armature part are integrally formed, and these two elements vibrate relative to each other via the elastic member. The electromechanical transducer of the present invention has a distinctive structure in which the elastic member is disposed between the housing and the structural part. This is a distinctive difference from the prior art structure in which the elastic member is disposed between the armature and the structural part.

[0008] In the structures of the prior art (Patent Documents 1 and 2), the structural part and the armature are housed in a housing, but in both cases the elastic member is disposed between the structural part and the armature, so that the space for disposing the elastic member takes up most of the space in the direction perpendicular to the vibration direction.

[0009] [Basic Structure] In contrast, in the basic structure provided by the present invention, the housing and armature are integrally configured to form an "armature portion," which is a single element that vibrates relative to the "structural portion." An elastic member is then disposed between the housing and the structural portion, allowing for elastic restoring force to be applied to both, thereby allowing for relative vibration between the "structural portion" and the "armature portion." As a result, there is no need to provide space for arranging the elastic member in a direction perpendicular to the vibration direction, making it possible to achieve overall miniaturization and high output according to required specifications. In the present invention, the housing may be configured to accommodate the structural portion therein, to surround the structural portion in a frame-like manner, or may have other configurations.

[0010] When an electromechanical transducer is used as a vibrator, vibration output can be extracted from the housing. However, if the housing is used as the output location (output point) of the vibrator, when an electrical signal is applied to the coil to drive the vibrator, the structural part vibrates relative to the armature part that is integral with the housing. As a result, the reaction force is transmitted to the housing, resulting in vibration output. This operating principle is also the same in the structures of prior art (Patent Documents 1 and 2), and in a typical electromechanical transducer, a gap of at least the maximum vibration displacement is required between the housing and the structural part in the vibration direction.

[0011] In the structure of the present invention, a space slightly larger than the maximum vibration displacement (maximum amplitude) is secured between the housing and the structural part to accommodate the elastic member disposed between the housing and the structural part. As a result, it is no longer necessary to secure the space required for the elastic member in the direction perpendicular to the vibration direction as in the prior art. This has the advantage that it is possible to meet the demands for miniaturization and high output of the entire vibrator, particularly in the direction perpendicular to the vibration direction, without being restricted by the space occupied by magnets and coils in the same direction.

[0012] The present invention further provides the following structures. [First Structure] The elastic member may be arranged in a space located in the relative vibration direction between the structural part and the housing (an integral component of the armature part; the same applies to the second structure). In this structure, it is clear that the elastic member is not arranged in a direction perpendicular to the vibration direction. By arranging the elastic member in the vibration direction, the space for arranging the elastic member does not expand in the direction perpendicular to the vibration direction. Therefore, the constraints imposed by the structures of the prior art are eliminated, making it possible to achieve overall miniaturization and high output according to required specifications.

[0013] [Second Structure] The elastic members may be arranged in the spaces located on both sides of the relative vibration direction between the structural part and the housing. Even in this structure, it is clear that the elastic members are not arranged in a direction perpendicular to the vibration direction. Furthermore, by arranging the elastic members on both sides of the vibration direction, the elastic members apply a restoring force to both sides via the housing. This allows the structural part and the armature part to return to a position where the forces in the vibration direction are balanced.

[0014] [Third Structure] The elastic member may be composed of a plurality of compression coil springs, whose axes are arranged along the direction of relative vibration between the structural portion and the armature portion. The structural portion may have a plurality of recesses capable of axially receiving one end of each of the plurality of compression coil springs. The plurality of compression coil springs may be arranged such that one end of each is received in a corresponding recess and the other end of each is in contact with the housing. This structure is applicable to the basic structure and the second structure.

[0015] [Fourth Structure] In the third structure, the structural part may include a side plate integrally connected to at least one pair of yokes. A recess may be formed in the side plate. This makes it clear which portion of the structural part the recess will be formed in. This fourth structure does not require the formation of recesses in drive components such as yokes, and does not prevent the realization of a structure that satisfies the required specifications regarding the arrangement of drive components.

[0016] As described above, the present invention can provide a technique with improved structural arrangement.

[0017] 1A . FIG. 1B is a perspective view showing an electromechanical transducer 100 of the first embodiment. FIG. 1C is a perspective view showing the electromechanical transducer 100 of the first embodiment. FIG. 1D is an exploded perspective view of the electromechanical transducer 100. FIG. 1E is a perspective view showing an assembled state of the structural unit 120. FIG. 1F is a perspective view showing the internal arrangement of the structural unit 120 and the leaf spring 140. FIG. 1G is a cross-sectional view taken along line IV-IV in FIG. 1A. FIG. 1H is a cross-sectional view taken along line V-V in FIG. 1A. FIG. 1G is a perspective view showing an electromechanical transducer 200 of the second embodiment. FIG. 1H is a perspective view showing the electromechanical transducer 200 of the second embodiment. FIG. 1I is an exploded perspective view of the electromechanical transducer 200. FIG. 1I is a perspective view showing a soldering state of the lead wire 228b to the coil 228. FIG. 1I is a perspective view showing the assembled state of the structural unit 220 and the internal arrangement of the compression coil spring 240. FIG. 1I is a cross-sectional view taken along line X-X in FIG. 6A. FIG. 1I is a cross-sectional view taken along line XI-XI in FIG. 6A. FIG. 1I is a perspective view showing an electromechanical transducer 300 of the third embodiment. FIG. 1I is a partial cross-sectional view including the internal structure of the electromechanical transducer 300. FIG. 1I is a view showing an application example. FIG. 1I is a view showing an application example.

[0018] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The electromechanical transducers shown in the following embodiments can be used not only for converting an electrical signal into mechanical vibration, but also for electroacoustic transducers such as speakers and earphones that convert an electrical signal into sound (acoustics) using the mechanical vibration. However, the present invention is not limited to these applications.

[0019] 1A and 1B are perspective views showing an electromechanical transducer 100 according to a first embodiment. FIG. 2 is an exploded perspective view of the electromechanical transducer 100. For convenience, in the following description, arrows representing three directions, X, Y, and Z, are shown in the figures. Of these, the X-axis direction is referred to as the left-right direction, the Y-axis direction as the front-rear direction, and the Z-axis direction as the up-down direction. In the following description, the up-down direction may also be referred to as the vertical direction, the left-right direction as the horizontal direction, the front as the front side, and the rear as the rear side. In this example, FIG. 1A is a front right-upper oblique view of the electromechanical transducer 100, and FIG. 1B is a rear left-upper oblique view. FIG. 2 is an exploded front right-upper oblique view of the electromechanical transducer 100. Note that the directions referred to here do not necessarily coincide with the directions in the actual use of the electromechanical transducer 100 (the same applies to other embodiments).

[0020] 1A and 1B, the electromechanical transducer 100 has two upper and lower housings 110 and 112 that occupy most of the external configuration. However, as shown in an exploded state in Fig. 2, many elemental parts are housed inside the housings 110 and 112. Note that even in the completed state, some elemental parts such as the electrical terminals 150 are exposed to the outside.

[0021] As shown in Fig. 2, the electromechanical transducer 100 is composed of a large number of element parts that are approximately symmetrical vertically and horizontally. Of these, a structural part 120 integrally formed from a plurality of element parts is defined as an element unit of the basic structure. Furthermore, an armature part (no reference number indicating the whole part) integrally formed from two upper and lower housings 110, 112 and an armature 130, and two upper and lower leaf springs 140 (elastic members) are also defined as element units of the basic structure. Although the armature 130 is shown within the range of the structural part 120 in Fig. 2 for convenience of illustration, the armature 130 is not included in the structural part 120.

[0022] The basic structure of such an electromechanical transducer 100 is such that an armature 130 disposed through the internal space of the structural part 120 is integrated with the housings 110, 112 to form an armature part. Leaf springs 140 are disposed and sandwiched between the upper and lower housings 110, 112 and the structural part 120, respectively, so that their elastic restoring force can be applied to both the housings 110, 112 and the structural part 120. This allows relative vibration (here, vertical vibration) between the structural part 120 and the armature part in the completed state. This will be explained in more detail below.

[0023] [Structural Unit] The structural unit 120 is primarily composed of two pairs of upper and lower magnets 124, a pair of upper and lower yokes 122, a pair of left and right side plates 126, and an air-core coil 128. Of these, the two pairs of upper and lower magnets 124 are rectangular flat plates facing each other from above and below. The pair of upper and lower yokes 122 are also rectangular flat plates, each with a through-hole 122a formed in the center in the thickness direction (here, the vertical direction). Furthermore, protrusions 122b that convex laterally are formed on both left and right side surfaces. The pair of left and right side plates 126 are groove-shaped members with a U-shaped vertical cross section extending in the front-to-rear direction, each with a through-hole 126a formed in the center in the thickness direction (here, the horizontal direction). Furthermore, upper and lower end faces that face each other in the horizontal direction each have a recess 126b that is concave inward. The coil 128 has terminals 128a bonded to both side surfaces, and the start and end of the coil winding are soldered to each terminal 128a, and lead wires (not shown) are also soldered to each of the terminals 128a.

[0024] The structural part 120 also includes a pair of upper and lower pivots 129, which are integrally formed of a cylindrical portion and a rectangular plate portion. When each pivot 129 is completed, the cylindrical portion fits into the through-hole 122a of the yoke 122. The pivots 129 may be formed by welding a spring and a yoke.

[0025] [Armature Section] The armature section is composed of a flat armature 130 and two upper and lower housings 110, 112. Protrusions 130a that are convex in the front-rear direction are formed on the front and rear end surfaces of the armature 130. The armature 130 is disposed so as to penetrate the inside of the coil 128 in the direction of the winding center (in this case, the front-rear direction).

[0026] The upper and lower housings 110, 112 are combined to form a single box shape. The structural unit 120 is housed inside this box shape. Each housing 110, 112 has two recessed notches 110a, 112a formed at the front and rear of the end faces where the housings join. When these housings are combined, the protrusion 130a of the armature 130 is sandwiched and fixed within the notches 110a, 112a. The leaf spring 140 is then positioned between the housings and the structural unit 120, pressing them down from above and below. The outer shape of the housings may be any shape suitable for the application and is not limited to a box shape.

[0027] [Elastic Member] Both the upper and lower leaf springs 140 are capable of exerting an elastic restoring force in the vertical direction. When pressed against the upper and lower housings 110 and 112, each leaf spring 140 contacts the inner surfaces (rear and bottom surfaces) of the housings 110 and 112 and the upper and lower surfaces of the structural unit 120 (yoke 122). Each leaf spring 140 has a rectangular base 140a at its center in the front-to-rear and left-to-right directions. Each leaf spring 140 has strip-shaped leaf portions 140c extending in all four directions from the four sides of the base 140a. Each leaf portion 140c is bent (curled) into a small-diameter cylindrical shape at its midpoint from the base 140a to its tip, forming a dogleg shape. When the four leaf portions 140c are extended, the leaf spring 140 has a cross shape when viewed from above. Furthermore, a square hole 140b is formed in the center of the base 140a, penetrating in the thickness direction, and in the completed state, the rectangular plate-shaped portion of the pivot 129 is fitted into the square hole 140b.

[0028] [Others] Additionally, the electromechanical transducer 100 has an electrical terminal 150. This electrical terminal 150 is attached to the front surface of the housings 110, 112 in the completed state. By soldering the lead wires (not shown) of the coil 128 to the electrical terminal 150, it is possible to input an electrical signal to the coil 128 from the outside. The lower housing 112 has U-shaped lead-out portions 112b formed on both sides of the cutout portion 112a. When the electrical terminal 150 is in the completed state, the lead wires (not shown) of the coil 128 are pulled out through these lead-out portions 112b and soldered to the electrical terminal 150.

[0029] 3A and 3B are perspective views showing the assembled state of the structural part 120 and the internal arrangement of the leaf spring 140. Of these, Fig. 3A shows the relationship between the assembled structural part 120 and the armature 130. Fig. 3B also shows the arrangement of the leaf spring 140 between the housings 110 and 112 and the structural part 120.

[0030] The structural unit 120 shown in FIG. 3A has two pairs of upper and lower magnets 124 glued and fixed to the inner surfaces of the upper and lower yokes 122, respectively, and a coil 128 positioned in the center in the front-to-rear direction. Furthermore, the upper and lower yokes 122 are sandwiched between a pair of left and right side plates 126, forming an integrated structure. The yokes 122 are made of a soft magnetic material such as 45% Ni permalloy. The magnets 124 are made of a relatively strong material such as a neodymium magnet or a samarium-cobalt magnet. Two magnets 124 are glued or fixed to the lower surface of the upper yoke 122 and the upper surface of the lower yoke 122 (both on the inner surfaces), spaced apart in the front-to-rear direction. This results in two magnets 124 arranged in pairs, one above the other, in the front-to-rear direction.

[0031] The coil 128 is fabricated by winding self-bonding copper wire, and the two lead wires (not shown) are flexible enough not to interfere with the vibration of the structural unit 120. Therefore, a twisted wire made of thin copper wire with an insulating coating is used. The coil 128 is disposed between the front and rear magnets 124 in the internal space surrounded by the upper and lower yokes 122 and the left and right side plates 126. The coil 128 is an air-core type without a core, and its winding center direction is aligned with the front-to-rear direction. The coil 128 is insulated and fixed to the inner surface of the yoke 122 by adhesive. The upper and lower pivots 129 are fixed by adhesive or the like with cylindrical portions fitted into the through holes 122a of the corresponding yokes 122. Rectangular portions protrude upward and downward from the yoke 122. The pivots 129 and side plates 126 are made of non-magnetic steel, such as SUS316L. As a result, the upper and lower yokes 122 including the pivot 129, the two pairs of upper and lower magnets 124, the left and right side plates 126, and the coil 128 are integrally formed as a single structure.

[0032] 3A and 3B is disposed relative to the structural unit 120 so as to penetrate its internal space in the front-to-rear direction and toward the winding core of the coil 128. The armature 130 is disposed so that both surfaces thereof face the upper and lower magnets 124, respectively, and is disposed so that the front and rear protrusions 130a protrude outward from the internal space.

[0033] In the completed state of the electromechanical transducer 100, the upper and lower leaf springs 140 are in a state in which the rectangular plate-shaped portions of the pivot 129 are fitted into the rectangular holes 140b as described above. At this time, the upper and lower leaf springs 140 are sandwiched between the upper and lower housings 110, 112 and the structural unit 120, i.e., between the upper and lower yokes 122, with a predetermined amount of displacement (deformation). As a result, the structural unit 120 is subjected to the elastic forces (restoring forces) of the upper and lower leaf springs 140 and is supported at a position where these forces are balanced. The structural unit 120 is disposed with an appropriate gap between the upper and lower housings 110, 112. Note that in the exploded state shown in FIGS. 2 and 3B, each leaf spring 140 is shown in an undeformed state. However, in the assembled state (see FIG. 4), each leaf spring 140 is deformed in the vertical direction and is assembled in a bent state. The leaf springs 140 are made of a plate material such as SUS301 for springs. Furthermore, by fitting the rectangular hole 140b of the leaf spring 140 into the rectangular plate-shaped portion of the pivot 129, rotational displacement around the vertical axis (Z-axis) within the housings 110 and 112 is suppressed.

[0034] The upper and lower housings 110, 112 then press and deform each leaf spring 140, and the front and rear protrusions 130a of the armature 130 are positioned within the front and rear notches 110a, 112a, respectively, sandwiching the armature from above and below. At this time, the protrusions 130a and the notches 110a, 112a, along with the joints between the upper and lower housings 110, 112, are fixed by laser welding or the like. As a result, the upper and lower housings 110, 112 and the armature 130 are integrally configured as an armature unit, which is a single structure. Here, "integral" means that the electromechanical transducer 100 behaves as a rigid body in its motion in the frequency range of interest. This also applies to the structural unit 120 described above.

[0035] When the structural portion 120 and the armature portion are integrally constructed as described above and the electrical terminals 150 including lead wires are attached, the electromechanical transducer 100 is in the completed state shown in FIGS. 1A and 1B.

[0036] [Internal Structure] Fig. 4 is a longitudinal cross-sectional view (IV-IV cross-sectional view in Fig. 1A) of the electromechanical transducer 100 in a completed state. Also, Fig. 5 is a longitudinal cross-sectional view (VV cross-sectional view in Fig. 1A) of the electromechanical transducer 100 in a completed state.

[0037] In the completed state of the electromechanical transducer 100, the same force acts on the upper and lower leaf springs 140 placed between the upper and lower housings 110, 112 and the structural part 120, and the two leaf springs 140 are made of the same elemental parts. As a result, the displacement amounts of the leaf springs 140 within the housings 110, 112 are also approximately equal. Therefore, when the elastic restoring forces applied to the structural part 120 from the upper and lower leaf springs 140 are balanced, the armature 130 is disposed in the center of the housings 110, 112 in the vertical direction, as shown in FIG. 4. As a result, the armature 130 is also positioned approximately in the center in the vertical direction with respect to the internal space of the structural part 120, and the upper and lower gaps 160, 162 between the armature 130 and the structural part 120 in the internal space are approximately equal. As shown in FIG. 4, a small gap is provided between the side plate 126 of the structural portion 120 and the housings 110 and 112 in the X-axis direction so as not to impede vibration.

[0038] [Operating Principle] The electromechanical transducer 100 is completed by magnetizing each magnet 124 and, if necessary, adjusting the magnetic forces acting on the armature 130 from the upper and lower magnets 124 to balance them. The electromechanical transducer 100 comprises four magnets 124, two upper and lower yokes 122, a coil 128, an armature 130, and four upper, lower, front, and rear air gaps 160, 162, forming a magnetic circuit. In this case, the magnetization directions of the magnets 124 are such that pairs of magnets in the vertical direction are magnetized in the same direction, while adjacent pairs in the front and rear direction are magnetized in opposite directions. For example, as shown by the white arrows in FIG. 5 , the pair of magnets 124 on the front side are both magnetized upward, and the pair of magnets 124 on the rear side are both magnetized downward. With the magnetization state of the magnets 124 as described above, it is assumed that when a current is passed through the coil 128 from the electrical terminal 150 in a predetermined direction, a magnetic flux is generated from the front to the rear of the armature 130. At this time, in the front, the magnetic flux between the lower magnet 124 increases, while the magnetic flux between the upper magnet 124 decreases. Similarly, in the rear, the magnetic flux between the lower magnet 124 increases, while the magnetic flux between the upper magnet 124 decreases. As a result, a magnetic force acts to displace the structural part 120 upward relative to the armature 130 and the housings 110, 112 integrated with it, and the displacement amount of the upper leaf spring 140 increases, while the displacement amount of the lower leaf spring 140 decreases.

[0039] At this time, the armature portion, which is an integrated structure including the armature 130 and the housings 110, 112, is considered as the reference point. A downward force equivalent to the difference between the elastic restoring forces generated by the upper and lower leaf springs 140 acts on the structural portion 120 from the leaf springs 140, and the structural portion 120 is displaced relatively within the housings 110, 112 to a position where this force balances with the upward magnetic force.

[0040] Then, by passing an alternating current through the coil 128 from the electrical terminal 150, the structural part 120 vibrates up and down within the housings 110, 112. This vibration generates a reaction force on the housings 110, 112, causing the housings 110, 112 to vibrate as well. In this case, the greater the acting force between the structural part 120 and the armature part, the more the electromechanical transducer 100 can function as a vibrator with a higher output.

[0041] Summary of the First Embodiment The electromechanical transducer 100 of the first embodiment described above provides the following advantages. (1) When the electromechanical transducer 100 functions as a vibrator, it is not necessary to secure space for disposing the leaf spring 140 in the horizontal direction perpendicular to the vibration direction (here, the front-rear direction or the left-right direction). Furthermore, by disposing the leaf spring 140 in the space required for vibration displacement in the vibration direction (the space between the housings 110, 112 and the structural part 120), a small additional space can be added to the minimum space required for displacement and used as the disposing space for the leaf spring 140. Therefore, it is only necessary to slightly increase the size in the vertical direction (here, the height and thickness directions) and significantly reduce the size in the front-rear direction, thereby enabling the electromechanical transducer 100 to be miniaturized as a whole.

[0042] (2) Even if the entire electromechanical transducer 100 is miniaturized, there is no restriction on the space required for arranging the magnet 124 and the coil 128, so it is possible to achieve a smaller size and higher output without reducing the vibration output.

[0043] Second Embodiment Next, a second embodiment of the electromechanical transducer will be described. The second embodiment is particularly suitable for use as a vibrator for vibrations in a frequency range of 100 Hz or less. It is also effective when adding mass in order to ensure a large vibration output (driving force) in the low frequency range. A specific description will be given below.

[0044] FIGS. 6A and 6B are perspective views showing an electromechanical transducer 200 according to the second embodiment. FIG. 7 is an exploded perspective view of the electromechanical transducer 200. In the second embodiment, elements equivalent to those in the first embodiment are designated by reference numerals in the 200s, with the last two digits of the reference numerals being the same, making it easier to understand the correspondence with the elements in the first embodiment. FIG. 8 is a perspective view showing how the lead wire 228b is soldered to the coil 228. FIG. 9 is a perspective view showing the assembled state of the structural unit 220 and the internal arrangement of the compression coil spring 240. The following description will focus on major differences from the first embodiment, and redundant descriptions of elements substantially common to the first embodiment, including the materials used, will be omitted.

[0045] [Basic Structure] The three element units of the basic structure of the electromechanical transducer 200 of the second embodiment are also the same. However, the second embodiment differs in the element components of the structural unit 220. Also, the second embodiment differs in that a compression coil spring 240 is used as the elastic member instead of the leaf spring 140.

[0046] The structural unit 220 is similar to that of the first embodiment in that it has two pairs of upper and lower magnets 224, a pair of upper and lower yokes 222, and a coil 228. However, it differs in that the element parts corresponding to the side plate 126 of the first embodiment are composed of a first side plate 226 and a second side plate 227.

[0047] The first side plate 226 is formed by pressing and bending a plate material, and has a rectangular opening 226a formed in the center. In addition, the first side plate 226 has multiple bent pieces (not referenced) formed at various locations around the periphery of the opening 226a and at the four corners. As shown in FIG. 8 , both left and right ends of the coil 228 are inserted into the opening 226a in the assembled state. Furthermore, lead wires 228b are soldered to terminals 228a on both sides of the opening 226a while the coil 228 is inserted therein.

[0048] The second side plate 227 has a rectangular outer diameter when viewed from the left-right direction, and has a rectangular opening 227a in the center, similar to the first side plate 226, so that the second side plate 227 has an overall rectangular ring shape. By providing a certain degree of thickness in the left-right direction, the second side plate 227 functions as a weight (mass) for the vibrator. Such a second side plate 227 can be made of a non-magnetic material such as brass.

[0049] The second side plates 227 are assembled to the first side plates 226 from both the left and right sides and are fixed together by adhesive bonding. Grooves 227c are formed on the inner surfaces of the left and right second side plates 227 that face each other. The grooves 227c extend in a stripe-like manner in the front-to-rear direction across the opening 226a. The lead wires 228b of the coil 228 soldered to the terminals 228a as described above are inserted into the grooves 227c, allowing the coil 228 to be guided forward.

[0050] Furthermore, four recesses 227b are formed at the front and rear end positions of the upper and lower end surfaces of the second side plate 227. Each of these recesses 227b is a circular hole with a bottom, and the inner diameter thereof is set slightly larger than the outer diameter of the compression coil spring 240. This allows each recess 227b to receive one end of the compression coil spring 240 therein. The manner in which the compression coil spring 240 is received in the recesses 227b will be described later with reference to another drawing.

[0051] [Armature Section] In the second embodiment, the armature section is formed by integrating the armature 230 and the upper and lower housings 210, 212, as in the first embodiment. However, in the second embodiment, no portion corresponding to the notch is formed in the upper housing 210. Therefore, the projection 230a of the armature 230 is received in the notch 212a of the lower housing 212, which is a difference. Note that the notch may also be formed in the upper housing 210 in the second embodiment. Furthermore, as shown in the figure, a through hole may be formed in the center of the armature 230 in the thickness direction (here, the vertical direction).

[0052] [Elastic Member] In the second embodiment, compression coil springs 240 are used as the elastic members. Four compression coil springs 240 are used on the top and bottom, for a total of eight. As described above, one end of each compression coil spring 240 is inserted into the recess 227b of the second side plate 227. The compression coil springs 240 can be made of a spring material such as SUS301.

[0053] 9 , the structural unit 220 of the second embodiment has second side plates 227 located on both the left and right sides. Compression coil springs 240 are inserted into the recesses 227b of the second side plates 227, and the compression coil springs 240 are then disposed between the structural unit 220 and the upper and lower housings 210, 212. The housings 210, 212 compress and deform each compression coil spring 240 in the vertical direction, and the protruding portion 230a of the armature 230 is positioned within the cutout portion 212a, sandwiching the armature 230 between the upper and lower housings 210, 212. The housings 210, 212 are fixed together by laser welding or the like.

[0054] [Internal Structure] Fig. 10 is a longitudinal cross-sectional view (X-X cross-sectional view in Fig. 6A) of the completed electromechanical transducer 200. Fig. 11 is a longitudinal cross-sectional view (XI-XI cross-sectional view in Fig. 6A) of the completed electromechanical transducer 200.

[0055] In the completed state of the electromechanical transducer 200, the same force acts on the four upper and four lower compression coil springs 240 disposed between the upper and lower housings 210, 212 and the structural unit 220. Furthermore, because the total of eight compression coil springs 240 are configured from the same components, the displacement amounts of the compression coil springs 240 within the housings 210, 212 are also approximately equal. Therefore, as shown in FIG. 10 , when the elastic restoring forces applied to the structural unit 220 from the four upper and four lower compression coil springs 240 are balanced, the armature 230 is positioned in the vertical center of the housings 210, 212. As a result, the armature 230 is also positioned approximately in the vertical center of the internal space of the structural unit 220, and the vertical gaps between the armature 230 and the structural unit 220 within the internal space are approximately equal. As shown in FIG. 10, a small gap is provided between the second side plate 227 of the structural portion 220 and the housings 210 and 212 so as not to impede vibration.

[0056] It can be seen that each recess 227b of the second side plate 227 is countersunk deeply from the vertical direction to a position nearly close to the center, allowing the compression coil spring 240 to be received deeply in the axial direction, thereby effectively preventing buckling deformation of the compression coil spring 240 in a compressed and displaced state.

[0057] [Operation Principle] As shown in FIG. 11, the operation principle by magnetizing the magnet 224 and applying a current is the same as in the first embodiment, and therefore a duplicated description will be omitted here.

[0058] Summary of the Second Embodiment The electromechanical transducer 200 of the second embodiment provides the following advantages. (1) By adding the second side plate 227 as a weight, it is possible to improve output in the low-frequency range, for example, at or below 100 Hz. (2) Furthermore, by forming a recess 227b in the second side plate 227, which functions as a weight, it is possible to accommodate the compression coil spring 240, which has a certain degree of free length, by sinking it into the recess 227b. This eliminates the need to ensure a displacement space for the compression coil spring 240 in the vertical direction above the structural unit 220, and allows the electromechanical transducer 200 to be configured compactly without increasing the overall thickness (height) in the vibration direction.

[0059] (3) In the second embodiment, there is no need to provide additional space for arranging an elastic member in the horizontal direction (here, the front-to-rear direction) perpendicular to the vibration direction. Furthermore, by storing most of the entire length of the compression coil spring 240 in the second side plate 227, only a portion of the spring protrudes vertically from the structural unit 220. This allows for a small additional space to be added to the minimum space required for displacement, and this space can also be used as the arrangement space for the compression coil spring 240. Therefore, only a slight increase in the vertical direction (here, the height and thickness directions) is required. Furthermore, since the size can be significantly reduced in the front-to-rear direction, the electromechanical transducer 200 as a whole can be made more compact.

[0060] (4) Even if the entire electromechanical transducer 200 is miniaturized, there are no restrictions on the space required to place the magnet 224 or the coil 228, so it is possible to achieve a smaller size and higher output without reducing the vibration output.

[0061] In the second embodiment, the first side plate 226 and the second side plate 227 may be formed as a single, integrated component, and a similar recess may be provided in this component to accommodate the compression coil spring 240.

[0062] In the first and second embodiments, the coils 128, 228 are formed integrally with the structural parts 120, 220, respectively. However, by reducing the dimensions of the hollow core parts of the coils 128, 228, the coils 128, 228 may be formed integrally with the armatures 130, 230 by adhesive or the like. In this case, a structure can be adopted in which an appropriate gap is secured between the coils 128, 228 and the structural parts 120, 220 so as not to interfere with vibration.

[0063] That is, if the overall mass of each electromechanical transducer 100, 200 (vibrator) is the same, it is often advantageous to set the mass of the armature 130, 230 side relatively small and the mass of the structural unit 120, 220 side relatively large, as this can increase the output of the vibrator. For this reason, in the first and second embodiments, the coils 128, 228 are configured integrally with the structural unit 120, 220 side. However, there are also cases where the coils 128, 228 are configured integrally with the armature 130, 230 side due to other requirements. Therefore, in this structure, it is also possible to have a configuration in which the structural unit does not include a coil, but the armature unit includes a coil and is configured integrally.

[0064] Third Embodiment Next, a third embodiment of the electromechanical transducer will be described. The third embodiment is suitable for use in converting an electrical signal into mechanical vibration, for example, to drive a diaphragm of a speaker or the like.

[0065] FIG. 12 is a perspective view showing an electromechanical transducer 300 according to the third embodiment. FIG. 13 is a partial cross-sectional view showing the internal structure of the electromechanical transducer 300. FIGS. 14A, 14B, and 14C are diagrams showing an application example. Similarly, in the third embodiment, elements equivalent to those in the first embodiment are assigned reference numerals in the 300 range, and the last two digits of the reference numerals are the same, making it easier to understand the correspondence with the elements in the first embodiment. The following description will focus on major differences from the first and second embodiments, and will omit redundant description of elements that are substantially the same as those in the first and second embodiments, including the materials used.

[0066] As shown in Figures 12 and 13, in the electromechanical transducer 300 of the third embodiment, the yoke 322, coil 328, magnet 324, side plate 326, electrical terminal 350, lead wires (not shown), etc. are assembled in the same structure as in the first embodiment.

[0067] In the third embodiment, the upper and lower housings 310, 312 are not structurally integrated, but a first elastic member 342 is disposed between them. Also, the upper yoke 322 and the upper housing 310 are fixed and integrated by laser welding or the like, and a second elastic member 344 is disposed between the lower yoke 322 and the lower housing 312.

[0068] In the third embodiment, the structural unit 320 (not shown in FIG. 13 ) is composed of the yoke 322, the coil 328, the magnet 324, the side plate 326, and the upper housing 310. Therefore, in the application example, the upper housing 310 is defined as a first structural member 530.

[0069] [Armature Section] The armature section is made up of an armature 330 and a lower housing 312. The lower housing 312 is connected to a lower yoke 322, which is one element of the structural section 320, via a second elastic member 344. Furthermore, the lower housing 312 is connected to an upper housing 310 (first structural member), which is also one element of the structural section 320, via a first elastic member 342.

[0070] [Operating Principle] The electromechanical transducer 300 of the third embodiment is characterized in that the lower housing 312 is fixed, and the upper housing 310, which is the first structural member 530, is directly vibrated. Alternatively, the upper housing 310, which is the first structural member 530, is fixed, and the lower housing 312 is directly vibrated.

[0071] Here, two elastic members, a first elastic member 342 and a second elastic member 344, are used. However, by selecting the appropriate material, it is possible to use only one of them. That is, since the first elastic member 342 and the second elastic member 344 are simultaneously compressed and stretched during operation, it is possible to use only one of them. In this case, the first and second elastic members 342, 344 must be able to apply a restoring force not only when compressed but also when stretched. Therefore, regardless of whether the first or second elastic member 342, 344 is used, it must be fixed to both the structural part 320 and the armature part.

[0072] [Application Examples] Application examples shown in Fig. 14A, Fig. 14B, and Fig. 14C will be described below. Fig. 14A shows an example in which the electromechanical transducer 300 of the third embodiment is applied to a speaker 500. The speaker 500 generally includes components such as a speaker housing 510, a damper 520, and a diaphragm 530. When driving such a speaker 500 using the electromechanical transducer 300 of the third embodiment, the following two modes (first mode and second mode) are possible.

[0073] 14B , the speaker housing 510 is a structure corresponding to the lower housing 312, and the damper 520 is a structure corresponding to the first elastic member 342. The diaphragm 530 is a structure corresponding to the upper housing 310 (first structural member), and the diaphragm 530 and the structural part 320 are fixed together. Therefore, the electromechanical transducer 300 as a vibrator can vibrate the diaphragm 530 (first structural member) by causing the structural part 320 to vibrate relative to the speaker housing 510 (lower housing 312).

[0074] At this time, the speaker housing 510 (lower housing 32) has a connecting portion 540, and is fixed to the armature 330 by laser welding or the like via the connecting portion 540, thereby forming an integrated structure. In addition, the structural portion 320 has a yoke 322 (not shown) connected to the speaker housing 510 (lower housing 312) via a second elastic member 344, such as a leaf spring.

[0075] As a result, the first aspect of the speaker 500 of the application example can be configured using the electromechanical transducer 300 of the third embodiment. Note that by appropriately designing the first elastic member 342 (damper 520), the second elastic member 344 can be omitted. Alternatively, by appropriately designing the second elastic member 344, the damper 520 does not have to function as the first elastic member 342.

[0076] 14C , the speaker housing 510 is a structure corresponding to the upper housing 310 (first structural member), and the damper 520 is a structure corresponding to the first elastic member 342. The diaphragm 530 is a structure corresponding to the lower housing 312, and the speaker housing 510 and the structural part 320 are fixed together. Therefore, the electromechanical transducer 300 as a vibrator can vibrate the diaphragm 530 (lower housing 312) by causing the structural part 320 to vibrate relative to the speaker housing 510 (first structural member).

[0077] Here, diaphragm 530 (lower housing 312) has connecting portion 540, and is fixed to armature 330 via connecting portion 540 with adhesive or the like, resulting in an integrated configuration. In this case, connecting portion 540 is desirably made of a relatively lightweight material, since it functions integrally with diaphragm 530. Furthermore, in structural portion 320, yoke 322 (not shown) is connected to diaphragm 530 (lower housing 312) via second elastic member 344, such as a leaf spring.

[0078] As a result, the second aspect of the speaker 500 of the application example can be configured using the electromechanical transducer 300 of the third embodiment. As in the first aspect, by appropriately designing the first elastic member 342 (damper 520), the second elastic member 344 can be omitted. Alternatively, by appropriately designing the second elastic member 344, the damper 520 does not have to function as the first elastic member 342.

[0079] The present invention is not limited to the above-described embodiments, and can be practiced in various modified forms.

[0080] In each embodiment, the outer shape formed by the upper and lower housings 110, 112, etc. is a cube or a rectangular parallelepiped. However, the outer shape may be cylindrical, egg-shaped, castanet-shaped, or any other shape. Furthermore, the housings 110, 112, etc. do not have to be box-shaped as described above. For example, the housings 110, 112, etc. may be formed integrally with the armature 130, etc. in a rectangular frame shape (a square-shaped frame), so that the structural unit 120 and the armature 130, etc. are disposed inside the housings 110, 112, etc.

[0081] Furthermore, although the electric terminals 150 and the like are arranged in each embodiment, a structure in which lead wires are drawn out to the outside without using the electric terminals 150 and the like may also be used.

[0082] The leaf spring 140 described in the first embodiment, the compression coil spring 240 described in the second embodiment, and the first elastic member 342 and the second elastic member 344 described in the third embodiment are merely examples. The form of the spring or the like may be any form as long as it can function as an elastic member having the desired properties, and elastic rubber, an air-filled bag, a bag filled with liquid, or the like may be substituted.

[0083] Furthermore, there are no limitations on the arrangement, specific shapes, dimensions, etc. of the various component parts, and various modifications can be applied.

[0084] 100, 200, 300 Electromechanical converter 110, 112 Housing 120 Structural part 122 Yoke 124 Magnet 126 Side plate 128 Coil 130 Armature 140 Leaf spring 240 Compression coil spring

Claims

1. An electromechanical transducer comprising: a structural part integrally formed of two pairs of magnets arranged opposite each other, a pair of yokes that guide the magnetic flux from the magnets, and an air-core coil arranged in the space surrounded by the yokes; an armature part integrally formed of an armature arranged in the space of the structural part passing through the air-core coil, and a housing interconnected with the armature; and an elastic member arranged between the housing and the structural part, which allows relative vibration between the structural part and the armature part by applying an elastic restoring force to both when placed between them.

2. An electromechanical transducer as claimed in claim 1, characterized in that the elastic member is disposed in a space positioned in the direction of relative vibration between the structural part and the housing.

3. An electromechanical transducer as claimed in claim 1, characterized in that the elastic members are arranged in each space located on both sides in the relative vibration direction between the structural part and the housing.

4. An electromechanical transducer as claimed in claim 1 or 3, characterized in that the elastic member is composed of a plurality of compression coil springs whose axes are arranged along the relative vibration direction between the structural part and the armature part, the structural part has a plurality of recesses capable of receiving one end of each of the plurality of compression coil springs in the axial direction, and the plurality of compression coil springs are arranged in a position where one end of each is received in an individual recess and the other end of each is in contact with the housing.

5. An electromechanical transducer according to claim 4, wherein the structural part includes side plates integrally connected to at least one pair of the yokes, and the recesses are formed in the side plates.

Images