Vibration actuator and electric device

Abstract

This vibration actuator comprises: a fixed part that has a thickness in the up-down direction, is fixed to a base, and includes a magnet; and a movable part that is disposed around the fixed part, is supported by a spring so as to be capable of vibrating in the up-down direction, includes a coil, and vibrates in the up-down direction by means of a driving force generated by an interaction that occurs between the magnet and the energized coil. The spring has a frustum shape. An outside portion of the spring is connected to the outer peripheral portion of the movable part. An inside portion of the spring is connected to the base. The inside portion has an opening into which an end portion of the fixed part in the up-down direction is inserted.

Description

Vibration actuator and electrical device

[0001] The present invention relates to a vibration actuator and an electrical device equipped with the same.

[0002] Portable or wearable electrical devices with a vibration function generally incorporate an actuator (vibration actuator) as a vibration generating source. The electrical device can notify the user of an incoming call or provide a stimulus by driving the vibration actuator to transmit vibrations that the user can experience. Portable or wearable electrical devices include mobile terminals such as mobile phones, smartphones, and smartwatches, as well as various healthcare and beauty devices that provide massages and other services to users.

[0003] One example of a conventional vibration actuator is a linear resonant actuator (LRA) described in Patent Document 1. The linear resonant actuator described in Patent Document 1 includes a cylindrical case with a bottom and a lid, which includes a cylindrical fixed part extending in the vertical direction, a circular movable part arranged around a permanent magnet, an elastic member, and a flexible printed circuit (FPC). The fixed part includes a magnet (permanent magnet), and the movable part includes a coil, a weight, and a yoke. The case includes a disk-shaped base that forms the bottom of the case, and a cylindrical cover with a lid that covers the top of the base. A circular protrusion is provided in the center of the base, and the lower end of the cylindrical fixed part is inserted into the inside of this protrusion to be fixed. The upper end of the fixed part is adhered to the top of the case.

[0004] The cylindrical case has spaces above and below the movable part to define the movable part's range of motion, with an elastic member disposed in the upper space and a flexible printed circuit board disposed in the lower space. The flexible printed circuit board is connected to the coil from below the movable part to supply power to the coil. The elastic member is a truncated cone-shaped spring, with its outer periphery fixed to the outer periphery of the upper part of the case and its inner periphery, which protrudes downward from the outer periphery of the spring, connected to the inner periphery of the upper part of the movable part, supporting the movable part so that it can vibrate up and down.

[0005] When the coil receives power, the magnetic field generated in the coil interacts with the magnetic field of the permanent magnet, generating a magnetic driving force that causes the movable part to vibrate up and down. The movable part vibrates up and down due to the generated magnetic driving force and the reaction force of the spring.

[0006] JP 2016-152734 A

[0007] However, in the above-mentioned conventional vibration actuator, a protrusion for fixing the fixing part is provided in the center of the bottom of the case, so the base serving as the bottom of the case needs to be processed. Meanwhile, due to space limitations for installing vibration actuators in portable or wearable electrical devices, further miniaturization of vibration actuators is desired. When miniaturization of vibration actuators is desired, for example, in the above-mentioned conventional vibration actuator, fine processing is required for the base, for example. In other words, the above-mentioned conventional vibration actuators have issues with ease of manufacture. Furthermore, when vibration actuators are applied to portable or wearable electrical devices, the risk of being subjected to a drop impact increases, making it important to ensure reliability against drop impacts.

[0008] An object of the present invention is to provide a vibration actuator that can be made compact yet is easy to manufacture and reliable against drop impacts, and an electrical device equipped with such a vibration actuator.

[0009] One aspect of the vibration actuator according to the present invention comprises: a fixed part having a thickness in the vertical direction, fixed to a base, and including a magnet; and a movable part arranged around the fixed part, supported by a spring so as to be able to vibrate in the vertical direction, including a coil, and vibrating in the vertical direction by a driving force generated by the interaction between the coil and the magnet when current is applied, wherein the spring has a frustum shape, an outer part of the spring is connected to the outer periphery of the movable part, and an inner part of the spring is connected to the base, and the inner part has an opening into which an end of the fixed part in the vertical direction is inserted.

[0010] One aspect of the electrical device according to the present invention is a portable or wearable electrical device incorporating the above vibration actuator.

[0011] According to the present invention, even if the vibration actuator is miniaturized, it is possible to achieve both ease of manufacturing and reliability against drop impact.

[0012] FIG. 1A is a perspective view showing the appearance of a vibration actuator according to an embodiment. FIG. 1B is a perspective view showing the vibration actuator according to an embodiment excluding the outer casing. FIG. 2 is an exploded view showing the vibration actuator according to an embodiment. FIG. 3 is a schematic view showing the cross-sectional configuration of the vibration actuator according to an embodiment. FIG. 4 is an enlarged view showing the connection portion between the base, fixed portion, and spring in the vibration actuator according to an embodiment, in order to explain the connection portion. FIG. 5 is a view showing the connection portion from below in order to explain the connection portion between the base, fixed portion, and spring in the vibration actuator according to an embodiment. FIG. 6 is a view showing a mobile terminal in which a vibration actuator according to an embodiment is implemented. FIG. 7 is a view showing a wearable terminal in which a vibration actuator according to an embodiment is implemented.

[0013] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0014] Fig. 1A is a perspective view showing the appearance of a vibration actuator according to this embodiment, and Fig. 1B is a perspective view showing the vibration actuator according to this embodiment excluding the outer casing. Fig. 3 is a diagram showing a schematic cross-sectional configuration of a vibration actuator according to an embodiment. Fig. 4 is an enlarged view of a connection portion between a base, a fixed portion, and a spring in a vibration actuator according to an embodiment, for explaining the connection portion. Fig. 5 is a diagram showing the connection portion between a base, a fixed portion, and a spring in a vibration actuator according to an embodiment, as viewed from below, for explaining the connection portion.

[0015] In the following description, the terms "upper" and "lower" in terms such as "upper side" and "lower side" are used for convenience to make it easier to understand the configuration and behavior of the vibration actuator 1 according to this embodiment. When the vibration actuator 1 is mounted on an electrical device (see FIGS. 6 and 7), the "upper" and "lower" described here may be reversed, or may be rotated left and right, or may be at an angle. Incidentally, in this embodiment, the up and down direction refers to the vibration direction of the movable body in the vibration actuator 1, with the "upward direction" being one of the vibration directions and the "downward direction" being the other of the vibration directions. In other words, the vibration actuator 1 is a linear actuator that vibrates the movable part 13 linearly in the up and down direction.

[0016] In the following description, when the vibration actuator 1 is viewed from above and below, the direction extending radially or centrifugal from the center of the vibration actuator 1 is referred to as the "radial direction." Furthermore, the "inside" in "inner" and the like refers to a position in the radial direction closer to the center of the vibration actuator 1 when viewed from above, and the "outside" in "outer" and the like refers to a position in the radial direction farther from the center of the vibration actuator 1 when viewed from above. Furthermore, unless otherwise specified, the "circumferential direction" refers to a direction extending around the center of the vibration actuator 1 when viewed from above.

[0017] Furthermore, it goes without saying that the expressions relating to shapes used in the following description are expedient expressions for the purpose of explaining simple outlines, and do not necessarily apply to geometrically accurate definitions of figures. The shapes of the entire device or each component described herein are examples, and the present invention is not limited to the shapes exemplified in this embodiment.

[0018] The vibration actuator 1 is mounted as a vibration generating source in a portable or wearable electrical device, realizing the vibration function of the electrical device. Examples of electrical devices include mobile terminals such as smartphones (e.g., the mobile terminal M shown in FIG. 6 ) and wearable smart devices such as ring-type or wristwatch-type devices (e.g., the wearable terminal W shown in FIG. 7 ). Electrical devices that can mount the vibration actuator 1 also include healthcare devices and beauty devices that provide massages and the like to the user. The vibration actuator 1 is mounted in various electrical devices, and the vibration actuator 1 itself vibrates due to the vibration of the internal movable part 13, thereby notifying the user of an incoming call or providing a physical stimulus.

[0019] The vibration actuator 1 has a cylindrical case 10 , a base 11 , a fixed part 12 , a movable part 13 , a flexible substrate 14 , and a spring 15 .

[0020] The cylindrical case 10 has a hollow portion that is rectangular in plan view and penetrates in the vertical direction. In other words, the cylindrical case 10 is a square-shaped cylinder. The cylindrical case 10 is made of a non-magnetized magnetic material and functions as an outer yoke (fixed yoke) in the vibration actuator 1. Examples of magnetic materials include permalloy.

[0021] In this embodiment, the "rectangular shape in plan view" typically refers to a square shape in plan view, and this also applies to the following description.

[0022] The base 11 includes a first base 11-1 and a second base 11-2. Both the first base 11-1 and the second base 11-2 are flat plates that are rectangular in plan view. The first base 11-1 functions as a lid (which may also be referred to as a top surface) that closes the opening at the upper end of the cylindrical case 10, and the second base 11-2 functions as a lid (which may also be referred to as a bottom surface) that closes the opening at the lower end of the cylindrical case 10. Furthermore, both the first base 11-1 and the second base 11-2 are made of unmagnetized magnetic material, and function as an actor yoke (fixed yoke) together with the cylindrical case 10 in the vibration actuator 1. Examples of magnetic materials include permalloy.

[0023] The box formed by combining the cylindrical case 10 and the base 11 is the outer housing of the vibration actuator 1. The cylindrical case 10 and the base 11 are fixed to each other by welding, but the fixing method may also be bonding with an adhesive or fastening with fastening members (e.g., screws). The outer housing is attached to an external device (portable or wearable electrical equipment) by a desired fixing method such as bonding or fastening.

[0024] Since the first base 11-1 and the second base 11-2 have the same shape, they function as a lid (which may also be called a top surface) that closes the opening at the upper end of the cylindrical case 10, and the second base 11-2 can use a common part as a lid that closes each of the lower end and the opening at the lower end of the cylindrical case 10.

[0025] In this embodiment, the term "same shape" does not include "similar" meaning that the shapes are the same but the sizes (dimensions) are different, but includes "congruent" meaning that the shapes are not only the same but also the sizes (dimensions). This point also applies to the following explanation.

[0026] The fixed portion 12 includes a first fixed portion 12-1 and a second fixed portion 12-2. The first fixed portion 12-1 has a first magnet 12-1a, and the second fixed portion 12-2 has a second magnet 12-2a. Although the fixed portion 12 may be a single component, in this embodiment, from the viewpoint of ease of manufacture, the fixed portion 12 includes a pair of components (the first fixed portion 12-1 and the second fixed portion 12-2) having the same shape. This point will be described later.

[0027] The fixed portion 12 constitutes the fixed body of the vibration actuator 1 together with the cylindrical case 10 and the base 11 that constitute the outer casing.

[0028] The first magnet 12-1a and the second magnet 12-2a are each a prismatic body (a rectangular parallelepiped or a cube) that is rectangular in plan view (more specifically, square in plan view) and has a thickness (which may also be referred to as height) in the vertical direction. The first magnet 12-1a and the second magnet 12-2a have the same shape. The magnetization direction of the first magnet 12-1a and the second magnet 12-2a is the vertical direction (which may also be referred to as the thickness direction or height direction). In this embodiment, the upper end 12-1c side of the first magnet 12-1a is magnetized to the south pole, and the lower end side is magnetized to the north pole. Furthermore, the lower end 12-2c of the second magnet 12-2a is magnetized to the south pole, and the upper end side is magnetized to the north pole.

[0029] The first magnet 12-1a and the second magnet 12-2a are fixed to the first base 11-1 and the second base 11-2, respectively, by adhesive bonding.

[0030] The first base 11-1 and the second base 11-2 close the cylindrical case 10 from above and below, with the first magnet 12-1a and the second magnet 12-2a facing each other (more specifically, with the same poles facing each other). An adhesive is applied to the gap between the opposing portions of the first magnet 12-1a and the second magnet 12-2a. This strengthens the fixing strength between the upper and lower halves of the vibration actuator 1.

[0031] The movable part 13 is an annular body disposed around the fixed part 12. The movable part 13 includes an air core coil 13-1 and a weight 13-2. Both the air core coil 13-1 and the weight 13-2 are annular bodies having a rectangular shape in a planar view (more specifically, a square shape in a planar view). The air core coil 13-1 is disposed relatively radially inward, and the weight 13-2 is disposed relatively radially outward. The inner peripheral surface of the air core coil 13-1 has a rectangular shape in a planar view that corresponds to the rectangular shapes in a planar view of the magnet outer peripheral portions 12-1b and 12-2b of the first magnet 12-1a and the second magnet 12-2a, but its radial size is slightly larger than that of the magnet outer peripheral portions 12-1b and 12-2b. Therefore, the air core coil 13-1 faces the magnet outer peripheral portions 12-1b and 12-2b with a small gap therebetween. The outer circumferential surface of the air-core coil 13-1 is fixed to the outer circumferential surface of the weight 13-2 by adhesive.

[0032] The air core coil 13-1 can be replaced with, for example, a winding coil wound around a bobbin, but from the perspective of minimizing the number of parts and the size of the device, it is preferable to use an air core coil 13-1 that does not require a holding member such as a bobbin.

[0033] The weight 13-2 is made of a material with a high specific gravity and functions as a weight that provides the desired mass to the movable part 13. The material with a high specific gravity may be a magnetic material. Examples of such materials include tungsten. When the weight 13-2 is an unmagnetized magnetic body, the weight 13-2 can function as an inner yoke (movable yoke). The outer peripheral surface of the weight 13-2 has a rectangular shape in a plan view that corresponds to the rectangular shape of the hollow part of the cylindrical case 10 in a plan view, but its radial size is slightly smaller than that of the hollow part of the cylindrical case 10. Therefore, the weight 13-2 faces the cylindrical case 10 with a small gap therebetween.

[0034] The flexible substrate 14 is a circuit board for supplying electricity (supplying a drive signal) to the air core coil 13-1. Since this circuit board is required to be flexible in order to be connected to the air core coil 13-1 that constitutes the movable part 13, a flexible substrate 14 is used.

[0035] In this embodiment, the flexible substrate 14 has a ring-shaped connection portion 14a at its tip and a strip-shaped extension portion 14b extending from the connection portion 14a to its rear end. The connection portion 14a surrounds the outer periphery of the fixed portion 12 and is fixed to the upper outer periphery 13-2a of the weight 13-2. The connection portion 14a has a terminal that connects to the air-core coil 13-1. The extension portion 14b has wiring for electrically connecting the terminal provided on the connection portion 14a to an external device. The extension portion 14b extends to the outside of the vibration actuator 1 through a side opening 10a provided in the cylindrical case 10.

[0036] The spring 15 includes a first spring 15-1 and a second spring 15-2. The first spring 15-1 and the second spring 15-2 have the same shape. The first spring 15-1 has two first flexible portions 15-1c, each of which has a spiral shape extending from the first inner portion 15-1a to the first outer portion 15-1b. The second spring 15-2 has two second flexible portions 15-2c, each of which has a spiral shape extending from the second inner portion 15-2a to the second outer portion 15-2b.

[0037] In this embodiment, the first spring 15-1 and the second spring 15-2 are flat springs before assembly, i.e., leaf springs. Because the first spring 15-1 and the second spring 15-2 are manufactured as leaf springs, they can be easily manufactured by punching a spiral shape from a flat metal plate, such as a stainless steel plate.

[0038] However, in this embodiment, the first spring 15-1 and the second spring 15-2 have a frustum shape after assembly, as shown in Figures 1B and 3. The frustum shape of the first spring 15-1 is such that the first inner portion 15-1a protrudes upward relative to the first outer portion 15-1b. The frustum shape of the second spring 15-2 is such that the second inner portion 15-2a protrudes downward relative to the second outer portion 15-2b.

[0039] The thickness of the first spring 15-1 is sufficiently thin compared to the space secured as a movable range above the movable part 13 in the cylindrical case 10. Therefore, when the first inner part 15-1a and the first outer part 15-1b are connected to the radial center part of the first base 11-1 and the upper outer peripheral part 13-2a of the movable part 13, respectively, the first spring 15-1 naturally takes on a frustum shape.

[0040] The thickness of the second spring 15-2 is sufficiently thin compared to the space secured as a movable range below the movable part 13 in the cylindrical case 10. Therefore, when the second inner part 15-2a and the second outer part 15-2b are connected to the radial center part of the second base 11-2 and the lower outer peripheral part 13-2b of the movable part 13, respectively, the second spring 15-2 naturally takes on a frustum shape.

[0041] The first inner portion 15-1a of the first spring 15-1 is connected to the first base 11-1. The second inner portion 15-2a of the second spring 15-2 is connected to the second base 11-2. In this embodiment, the first inner portion 15-1a and the second inner portion 15-2a are fixed to the first base 11-1 and the second base 11-2, respectively, by welding. That is, the first inner portion 15-1a of the first spring 15-1 is the fixed end of the first spring 15-1, and the second inner portion 15-2a of the second spring 15-2 is the fixed end of the second spring 15-2.

[0042] A first outer portion 15-1b of the first spring 15-1 is connected to an upper outer peripheral portion 13-2a of the movable portion 13. A second outer portion 15-2b of the second spring 15-2 is connected to a lower outer peripheral portion 13-2b of the movable portion 13.

[0043] More specifically, in the first spring 15-1, the first outer end portions 15-1e of the two first flexible portions 15-1c are connected to two diagonally opposite corners of the upper outer peripheral portion 13-2a. In this way, the first outer end portions 15-1e of the two first flexible portions 15-1c can support the rectangular movable portion 13 at positions furthest outward from the radial center, thereby stably maintaining the horizontal posture of the rectangular movable portion 13.

[0044] In the second spring 15-2, the second outer end portions 15-2e of the two second flexible portions 15-2c are connected to two diagonal corners of the lower outer peripheral portion 13-2b. In this way, the second outer end portions 15-2e of the two second flexible portions 15-2c can support the rectangular movable portion 13 at positions furthest outward from the radial center, thereby stably maintaining the horizontal posture of the rectangular movable portion 13.

[0045] Here, the weight 13-2 has protrusions 13-2c that protrude upward and downward from the four corners of the upper outer peripheral portion 13-2a and the lower outer peripheral portion 13-2b, respectively. The first outer end 15-1e of the first spring 15-1 and the second outer end 15-2e of the second spring 15-2 are fixed by welding to the protrusions 13-2c at the corresponding positions. In this way, the fixed portions of the first outer end 15-1e and the second outer end 15-2e of the movable part 13 protrude, making it easy to fix the first outer end 15-1e and the second outer end 15-2e to the movable part 13. Furthermore, because the protrusions 13-2c are provided at all corners, the protrusions 13-2c can be positioned at positions corresponding to the two second outer end portions 15-1e and the two second outer end portions 15-2e, regardless of the orientation of the movable part 13 within the cylindrical case 10. Furthermore, the location of the weight 13-2 where the spring 15 is connected and the location of the flexible substrate 14 can be distinguished by the unevenness.

[0046] The diagonal line on which the two corners of the upper outer peripheral portion 13-2a, to which the two first outer ends 15-1e are connected, intersects with the diagonal line on which the two corners of the lower outer peripheral portion 13-2b, to which the two second outer ends 15-2e are connected. This allows the springs 15, consisting of the upper first spring 15-1 and the lower second spring 15-2, to support the rectangular movable portion 13 in both diagonal directions. This further stabilizes the horizontal position of the movable portion 13.

[0047] The first inner portion 15-1a has a first opening 15-1d. The first opening 15-1d has a rectangular shape in plan view that corresponds to the rectangular shape of the magnet outer periphery 12-1b of the first fixed portion 12-1 (first magnet 12-1a) in plan view. The upper end 12-1c of the first magnet 12-1a is inserted into the first opening 15-1d. Therefore, the first spring 15-1 can function as a positioning member that determines the fixed position of the first magnet 12-1a. This eliminates the need for fine processing to fix the first fixed portion 12-1 to the first base 11-1, making manufacturing easier. As a result, the dimensional stability of the vibration actuator 1 can be improved, thereby stabilizing and improving vibration characteristics.

[0048] Furthermore, with the first opening 15-1d surrounding the magnet outer periphery 12-1b, the first inner portion 15-1a is connected to the first base 11-1 included in the fixed body. Therefore, the first spring 15-1 can also function as a support member for supporting the first fixed portion 12-1 (first magnet 12-1a). This allows the first fixed portion 12-1 to be fixed not only by the first base 11-1 but also by the first spring 15-1, thereby strengthening the fixing strength of the first fixed portion 12-1. This improves the reliability of the vibration actuator 1 against drop impacts and the like.

[0049] The second inner portion 15-2a has a second opening 15-2d. The second opening 15-2d has a rectangular shape in plan view that corresponds to the rectangular shape of the magnet outer periphery 12-2b of the second fixed portion 12-2 (second magnet 12-2a) in plan view. The lower end 12-2c of the second magnet 12-2a is inserted into the second opening 15-2d. Therefore, the second spring 15-2 can function as a positioning member that determines the fixed position of the second magnet 12-2a. This eliminates the need for fine processing to fix the second fixed portion 12-2 to the second base 11-2, making manufacturing easier. As a result, the dimensional stability of the vibration actuator 1 can be improved, thereby stabilizing and improving vibration characteristics.

[0050] Furthermore, with the second opening 15-2d surrounding the magnet outer periphery 12-2b, the second inner portion 15-2a is connected to the second base 11-2 included in the fixed body. Therefore, the second spring 15-2 can also function as a support member for supporting the second fixed portion 12-2 (second magnet 12-2a). This allows the second fixed portion 12-2 to be fixed not only by the second base 11-2 but also by the second spring 15-2, thereby strengthening the fixing strength of the second fixed portion 12-2. This improves the reliability of the vibration actuator 1 against drop impacts and the like.

[0051] In the vibration actuator 1 having the above configuration, when an AC driving current is input as a driving signal to the air core coil 13-1, a driving force for upward movement and a driving force for downward movement are repeatedly generated in the movable part 13 in accordance with the frequency (driving frequency) of the driving current. This causes the movable part 13 to vibrate. In this embodiment, the thrust acts in the vertical direction, so the movable part 13 vibrates linearly in the vertical direction. The driving force described above is a thrust that follows Fleming's left-hand rule and is generated by the interaction between the energized air core coil 13-1 and the first magnet 12-1a and second magnet 12-2a.

[0052] In this embodiment, the movable part 13 is elastically supported by the first spring 15-1 and the second spring 15-2 so as to be able to vibrate in the vertical direction. Therefore, when the movable part 13 moves upward or downward from the center position of the vibration, the deformed first flexible part 15-1c of the first spring 15-1 and the second spring 15-2 generate a restoring force that attempts to return them to their original shapes, and transmits this force to the movable part 13. This force urges the movable part 13 in the opposite direction. In other words, the movable part 13 moves downward if it has moved upward, or moves upward if it has moved downward, so as to return to the center position of the vibration.

[0053] When an AC wave having a frequency equal to the resonant frequency of the movable part 13 is input to the air core coil 13-1, the movable part 13 enters a resonant state. In other words, by inputting an AC wave having a frequency equal to the resonant frequency of the movable part 130 to the air core coil 13-1, the movable part 13 can be vibrated efficiently.

[0054] As described above, according to this embodiment, the vibration actuator 1 has a fixed portion 12 and a movable portion 13. The fixed portion 12 has a thickness in the vertical direction and includes a magnet (at least one of a first magnet 12-1a and a second magnet 12-2a) fixed to the base 11. The movable portion 13 is disposed around the fixed portion 12, is supported by springs 15 so as to be able to vibrate in the vertical direction, includes a coil (an air-core coil 13-1), and vibrates in the vertical direction due to a driving force generated by the interaction between the energized coil and the magnet. The spring 15 has a frustum shape. An outer portion of the spring 15 (at least one of a first outer portion 15-1b and a second outer portion 15-2b) is connected to an outer periphery of the movable portion 13 (at least one of an upper outer periphery 13-2a and a lower outer periphery 13-2b). An inner portion of the spring 15 (at least one of a first inner portion 15-1a and a second inner portion 15-2a) is connected to the base 11. The inner portion of the spring 15 (at least one of the first inner portion 15-1a and the second inner portion 15-2a) has an opening (at least one of the first opening 15-1d and the second opening 15-2d) into which the end portion (upper end portion 12-1c or lower end portion 12-2c) of the fixed portion 12 in the vertical direction is inserted.

[0055] According to the above configuration, the inner portion of the spring 15 corresponding to the radial center portion where the fixed portion 12 is located is fixed to the base 11. This allows the spring 15 to support the vertical ends of the fixed portion 12. Specifically, as described above, an opening is provided in the inner portion of the spring 15, and the vertical ends of the fixed portion 12 are inserted into this opening. The vertical ends of the fixed portion 12 are fixed to the base 11 with the opening in the inner portion of the spring 15 surrounding the outer periphery of the fixed portion 12. This allows the fixed portion 12 to be fixed not only by the base 11 but also by the spring 15, thereby increasing the fixing strength of the fixed portion 12. This therefore improves the reliability of the vibration actuator 1 against drop impacts, etc.

[0056] Furthermore, since the spring 15 can be used to position the fixed portion 12, there is no need to perform fine processing on the base 11 in order to position the fixed portion 12. This makes it easier to manufacture the base 11, and therefore the vibration actuator 1.

[0057] Therefore, according to this embodiment, even if the vibration actuator 1 is made smaller, the ease of manufacturing the vibration actuator 1 can be ensured, and the reliability of the vibration actuator 1 against shocks caused by dropping and the like can be improved.

[0058] Furthermore, according to this embodiment, the vibration actuator 1 further includes a cylindrical case 10 having a hollow portion that is rectangular in plan view and penetrates in the vertical direction. The fixed portion 12 includes a first fixed portion 12-1 and a second fixed portion 12-2 that have identically shaped first magnets 12-1a and second magnets 12-2a. The base 11 includes an identically shaped first base 11-1 and a second base 11-2 to which the first fixed portion 12-1 and the second fixed portion 12-2 are fixed, respectively. The spring 15 includes an identically shaped first spring 15-1 and a second spring 15-2. In the first spring 15, a first inner portion 15-1a connected to the first base 11-1 has a first opening 15-1d into which the upper end portion 12-1c of the first fixed portion 12-1 is inserted. In the second spring 15-2, a second inner portion 15-2a connected to the second base 11-2 has a second opening 15-2d into which the lower end portion 12-2c of the second fixed portion 12-2 is inserted. The first base 11-1 and the second base 11-2 close the cylindrical case 10 from above and below with the first magnet 12-1a and the second magnet 12-2a facing each other, respectively.

[0059] According to the above configuration, the upper half including the first base 11-1, the first fixed portion 12-1, and the first spring 15-1 and the lower half including the second base 11-2, the second fixed portion 12-2, and the second spring 15-2 have the same shape. The upper and lower halves, which have the same shape, are assembled facing each other. Therefore, the components of the upper and lower halves can be standardized, which effectively reduces the number of components in the vibration actuator 1.

[0060] An example of the implementation of the vibration actuator 1 will be described below.

[0061] 6 shows an example of an electrical device that incorporates a vibration actuator equivalent to the vibration actuator 1. FIG. 6 shows an example in which the vibration actuator 1 is incorporated into a mobile terminal M.

[0062] The mobile terminal M is, for example, a mobile communication terminal such as a mobile phone, a smartphone, etc. The mobile terminal M can notify the user of an incoming call from, for example, an external communication device by vibrating.

[0063] The mobile terminal M has a communication unit 101, a processing unit 102, a drive control unit 103, and a vibration actuator 104 which is the vibration actuator 1 as a drive unit. Note that a plurality of vibration actuators 104 may be implemented.

[0064] In the mobile terminal M, the vibration actuator 104 is preferably mounted so that, for example, the main surface (e.g., the operation surface) of the mobile terminal M and a surface perpendicular to the vibration direction of the vibration actuator 104, in this case the first base 11-1 and the second base 11-2, are parallel.

[0065] The communication unit 101 is connected to an external communication device via wireless communication, receives signals from the communication device, and outputs the signals to the processing unit 102. In the case of the mobile terminal M, the external communication device is, for example, a base station, and communication is performed in accordance with a mobile communication standard.

[0066] The processing unit 102 converts the input signal into a drive signal for driving the vibration actuator 104 using a conversion circuit unit (not shown) and outputs the drive signal to the drive control unit 103. In the mobile terminal M, the processing unit 102 generates the drive signal based on signals input from the communication unit 101 as well as signals input from various functional units (not shown, for example, an operation unit such as a touch panel).

[0067] The drive control unit 103 is connected to the vibration actuator 104, and is equipped with a circuit for driving the vibration actuator 104. The drive control unit 103 supplies a drive signal to the vibration actuator 104.

[0068] The vibration actuator 104 is driven in accordance with a drive signal from the drive control unit 103. Specifically, in the vibration actuator 104, the movable part 13 vibrates in a direction perpendicular to the main surface of the mobile terminal M.

[0069] Since vibrations are transmitted in a direction perpendicular to the body surface to the surface of the user's body that is in contact with the mobile terminal M, the user can be given a sufficient bodily sensation of vibrations.

[0070] 7 shows another example of an electrical device that incorporates a vibration actuator equivalent to the vibration actuator 1. FIG. 7 shows an example in which the vibration actuator 1 is incorporated into a wearable terminal W.

[0071] Similar to the above-described mobile terminal M, the wearable terminal W has a communication unit 101, a processing unit 102, a drive control unit 103, and a vibration actuator 104 that is the vibration actuator 1 serving as a drive unit. Note that a plurality of vibration actuators 104 may be implemented.

[0072] In the wearable terminal W, the vibration actuator 104 is also preferably mounted so that the main surface of the wearable terminal W and the surface perpendicular to the vibration direction of the vibration actuator 104, in this case the first base 11-1 and the second base 11-2, are parallel to each other. If the wearable terminal W has a ring shape as shown in Fig. 7, for example, the surfaces of the first base 11-1 and the second base 11-2 should be arranged toward the center of the ring shape.

[0073] Vibrations perpendicular to the body surface are transmitted to the body surface of the user that is in contact with the wearable terminal W, so that the user can feel the vibrations sufficiently.

[0074] In this way, the vibration actuator 1 (vibration actuator 104) is effective when mounted on a portion of portable or wearable electrical equipment that comes into contact with the user.

[0075] Although the embodiments of the present invention have been specifically described above, the present invention is not limited to the above-described specific embodiments. Various modifications and changes to the specific examples described in the above embodiments are possible within the scope of the gist of the present invention as defined in the claims.

[0076] The disclosures of the specification, drawings and abstract contained in Japanese Patent Application No. 2023-141715, filed on August 31, 2023, are incorporated herein by reference in their entirety.

[0077] The vibration actuator according to the present invention is useful as a vibration generating source for, for example, notifying incoming calls in portable or wearable electrical devices such as mobile terminals.

[0078] 1 vibration actuator 10 cylindrical case 10a side opening 11 base 11-1 first base 11-2 second base 12 fixed portion 12-1 first fixed portion 12-1a first magnet 12-1b magnet outer periphery 12-1c upper end portion 12-2 second fixed portion 12-2a second magnet 12-2b magnet outer periphery 12-2c lower end portion 13 movable portion 13-1 air core coil 13-2 weight 13-2a upper outer periphery 13-2b lower outer periphery 13-2c protrusion 14 flexible substrate 14a connection portion 14b extension portion 15 spring 15-1 first spring 15-1a first inner portion 15-1b first outer portion 15-1c first flexible portion 15-1d First opening 15-1e First outer end 15-2 Second spring 15-2a Second inner part 15-2b Second outer part 15-2c Second flexible part 15-2d Second opening 15-2e Second outer end 5201 Communication unit 5202 Processing unit 5203 Drive control unit M Portable terminal W Wearable terminal

Claims

1. A vibration actuator comprising: a fixed part including a magnet, having a thickness in the vertical direction, and fixed to a base; and a movable part arranged around the fixed part, supported by a spring so as to be able to vibrate in the vertical direction, including a coil, the movable part vibrating in the vertical direction by a driving force generated by the interaction between the coil when electrified and the magnet, the spring having a frustum shape, an outer part of the spring connected to the outer periphery of the movable part, an inner part of the spring connected to the base, and the inner part having an opening into which an end of the fixed part in the vertical direction is inserted.

2. The vibration actuator according to claim 1, wherein the fixed portion has a rectangular shape in a plan view, and the opening portion has a rectangular shape in a plan view that corresponds to the rectangular shape of the fixed portion in a plan view.

3. A vibration actuator as described in claim 2, wherein the movable part has a rectangular shape in a planar view corresponding to the rectangular shape of the fixed part in a planar view, the spring has two flexible parts each having a spiral shape extending in a spiral manner from the inner part to the outer part, and the outer ends of each of the two flexible parts are connected to two diagonally opposite corners of the outer periphery of the movable part.

4. A vibration actuator as described in claim 3, wherein the springs include a first spring and a second spring of the same shape, the outer ends of the two flexible portions of the first spring are connected to two diagonal corners of an upper outer periphery of the movable part, and the outer ends of the two flexible portions of the second spring are connected to two diagonal corners of a lower outer periphery that are positioned so as to intersect with the diagonal of the upper outer periphery of the movable part.

5. The vibration actuator as described in claim 1, further comprising a cylindrical case having a hollow portion of a rectangular shape in a plan view that penetrates in the vertical direction, wherein the fixed portion includes a first fixed portion and a second fixed portion each having a first magnet and a second magnet of the same shape, the base includes a first base and a second base of the same shape to which the first fixed portion and the second fixed portion are respectively fixed, the spring includes a first spring and a second spring of the same shape, wherein in the first spring, a first inner portion connected to the first base has an opening into which an upper end of the first fixed portion is inserted, and in the second spring, a second inner portion connected to the second base has an opening into which a lower end of the second fixed portion is inserted, and the first base and the second base respectively close the cylindrical case from above and below with the first magnet and the second magnet facing each other.

6. A vibration actuator as described in claim 4, further comprising a cylindrical case having a hollow portion of a rectangular shape in a plan view that penetrates in the vertical direction, wherein the fixed portion includes a first fixed portion and a second fixed portion each having a first magnet and a second magnet of the same shape, wherein the base includes a first base and a second base of the same shape to which the first fixed portion and the second fixed portion are respectively fixed, wherein in the first spring, a first inner portion connected to the first base has an opening into which an upper end portion of the first fixed portion is inserted, wherein in the second spring, a second inner portion connected to the second base has an opening into which a lower end portion of the second fixed portion is inserted, and wherein the first base and the second base respectively close the cylindrical case from above and below with the first magnet and the second magnet facing each other.

7. A portable or wearable electrical device incorporating the vibration actuator according to claim 1.

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