Vibration-type linear actuator and electric toothbrush

Abstract

The present disclosure provides a vibration-type linear actuator and an electric toothbrush capable of reciprocating a first movable body and a second movable body with a more complex movement. This vibration-type linear actuator (40) is provided with an electromagnetic block (50) having an electromagnet (52) and a magnetic block (60) having a permanent magnet (63). In addition, the magnetic block (60) is provided with a first movable body (61) and a second movable body (62), and a thrust force acting on the first movable body (61) is different from a thrust force acting on the second movable body (62). Furthermore, the vibration-type linear actuator (40) is configured such that, when a voltage having a waveform obtained by superimposing two different waveforms is applied to the electromagnet (52), the first movable body (61) and the second movable body (62) reciprocate at a frequency at which the amplitude increases in opposite phases, and reciprocate at a frequency at which the amplitude increases in the same phase.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a vibration type linear actuator and an electric toothbrush. BACKGROUND

[0002] In the past, as a vibration type linear actuator, there has been known a vibration type linear actuator provided with an electromagnetic block and a magnetic block, and causing the magnetic block to relatively reciprocate with respect to the electromagnetic block by causing an electromagnetic force to act between the electromagnetic block and the magnetic block, as shown in Patent Literature 1 below, in which the electromagnetic block has an electromagnet, and the magnetic block has a permanent magnet configured to face the electromagnet across a gap.

[0003] In Patent Literature 1, the magnetic block has a first movable body having a permanent magnet configured to face the electromagnet across a gap, and a second movable body having a permanent magnet configured to face the electromagnet across a gap. Further, the first movable body and the second movable body are caused to reciprocate in opposite phases to each other by generating a periodically varying magnetic field between the electromagnetic block and the first movable body and between the electromagnetic block and the second movable body.

[0004] PRIOR ART DOCUMENTS

[0005] PATENT LITERATURE

[0006] Patent Literature 1: Japanese Patent Application Publication No. 2014-128187 SUMMARY

[0007] PROBLEMS TO BE SOLVED BY THE INVENTION

[0008] In such a vibration type linear actuator, it is preferable that the first movable body and the second movable body be able to reciprocate in more complex motions.

[0009] Therefore, an object of the present disclosure is to obtain a vibration type linear actuator and an electric toothbrush capable of causing the first movable body and the second movable body to reciprocate in more complex motions.

[0010] SOLUTION TO PROBLEM

[0011] A vibration type linear actuator according to an embodiment of the present disclosure includes an electromagnetic block having an electromagnet, and a magnetic block having a permanent magnet configured to face the electromagnet across a gap, the magnetic block relatively reciprocating in a first direction with respect to the electromagnetic block by a periodically varying magnetic field, wherein the magnetic block includes a first movable body coupled to the electromagnetic block via a first spring, and a second movable body coupled to the first movable body via a second spring, the vibration type linear actuator configured to cause the first movable body and the second movable body to reciprocate at a frequency at which amplitudes increase in opposite phases and at a frequency at which amplitudes increase in the same phase when a voltage of a waveform obtained by superimposing two different waveforms is applied to the electromagnet in a state where a thrust acting on the first movable body and a thrust acting on the second movable body are different.

[0012] An electric toothbrush according to an embodiment of the present disclosure includes the above-described vibration type linear actuator, and a handle having a brush portion, the handle being connected to the first movable body or the second movable body.

[0013] Effects of Invention

[0014] According to the present disclosure, a vibration type linear actuator and an electric toothbrush capable of causing a first movable body and a second movable body to reciprocate in more complex motion can be obtained. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 FIG. 1 is a side view showing an example of an electric toothbrush according to an embodiment of the present disclosure.

[0016] Figure 2 FIG. 2 is a perspective view showing an example of a vibration type linear actuator structure according to an embodiment of the present disclosure.

[0017] Figure 3 FIG. 3 is a perspective view showing an example of a vibration type linear actuator according to an embodiment of the present disclosure.

[0018] Figure 4 FIG. 4 is a plan view showing an example of a vibration type linear actuator according to an embodiment of the present disclosure.

[0019] Figure 5 FIG. 5 is a side view showing an example of a vibration type linear actuator according to an embodiment of the present disclosure.

[0020] Figure 6 FIG. 6 is a back view showing an example of a vibration type linear actuator according to an embodiment of the present disclosure.

[0021] Figure 7 FIG. 7 is a front view showing an example of a vibration type linear actuator according to an embodiment of the present disclosure.

[0022] Figure 8 FIG. 1 is a rear view showing an example of a vibration-type linear actuator to which the embodiment is applied.

[0023] Figure 9 FIG. 2 is a diagram schematically showing a vibration model of an example of a vibration-type linear actuator to which the embodiment is applied.

[0024] Figure 10 FIG. 3 is a diagram showing frequency characteristics of a first movable body and a second movable body to which the embodiment is applied.

[0025] Figure 11 FIG. 4 is a diagram showing a waveform of a voltage applied to an electromagnet to which the embodiment is applied.

[0026] Figure 12 FIG. 5 is a diagram schematically showing a vibration model of an example of a vibration-type linear actuator structure to which the embodiment is applied.

[0027] Figure 13 FIG. 6 is a diagram showing an output waveform of a first movable block to which the embodiment is applied.

[0028] Figure 14 FIG. 7 is a plan view showing an example of a vibration-type linear actuator to which a modification is applied.

[0029] Figure 15 FIG. 8 is a diagram schematically showing a vibration model of an example of a vibration-type linear actuator to which the modification is applied. DETAILED DESCRIPTION

[0030] Hereinafter, the embodiment will be described in detail with reference to the drawings. However, unnecessary detailed description will be omitted at times. For example, detailed description of matters which are already well known and repeated description of substantially identical structures will be omitted at times.

[0031] Further, the drawings and the following description are provided to enable those skilled in the art to fully understand the present disclosure and are not intended to limit the subject matter recited in the claims.

[0032] In addition, in the following embodiment, a vibration-type linear actuator for an electric toothbrush, that is, an example of an oral hygiene device, as a personal care product is exemplified.

[0033] In addition, in the following embodiment, the direction in which the first movable body and the second movable body are reciprocated is set as the X direction, the direction in which the electromagnet and the permanent magnet face each other is set as the Z direction, and the direction which intersects (for example, is orthogonal to) the X direction and the Z direction is set as the Y direction. The X direction is also referred to as a front-rear direction, a first direction, or an axial direction of an output shaft. The Y direction is also referred to as a width direction or a third direction. The Z direction is also referred to as an up-down direction or a second direction.

[0034] Furthermore, the vertical direction of the vibration type linear actuator will be defined and described in a state where the electromagnet is located at the bottom and the permanent magnet is located at the top.

[0035] In the following embodiments, for convenience, the side from which the output shaft protrudes is defined as the front side of the vibration-type linear actuator (ie, the front in the X direction).

[0036] (Implementation Method)

[0037] Figure 1 1 is a side view showing an example of an electric toothbrush 10 according to the embodiment. Figure 1 As shown, the electric toothbrush 10 involved in this embodiment (i.e., an example of an oral hygiene device) includes a main body 20 and a handle 30 (i.e., an example of a driven body) that is detachably mounted on the front end of the main body 20. In this embodiment, the main body 20 is elongated in the X direction (i.e., the front-to-back direction, the first direction, or the axial direction of the output shaft). Moreover, the main body 20 includes a main body shell 21 that forms the outer profile of the main body 20, and a gripping portion 211 (i.e., an example of a gripping portion) that can be held by hand is formed on the main body shell 21. For example, such a main body shell 21 can be formed by connecting a plurality of split bodies together using materials such as synthetic resin. In addition, for example, a plurality of split bodies can be connected together by using screws or by fitting the split bodies into each other. In addition, the operating switch 24 is mounted on the main body shell 21 in a state exposed to the outside and in a manner that can be pressed inward.

[0038] Furthermore, in the present embodiment, a cavity is formed inside the main body housing 21 formed by connecting a plurality of divided bodies, and various electrical components such as the vibration-type linear actuator 40 are housed in the cavity.

[0039] In this embodiment, a cavity formed within the main body housing 21 houses the portion of the vibration-type linear actuator 40 excluding the tip portion (more specifically, the front end portion) of the output shaft 616; a battery 23 for driving the vibration-type linear actuator 40; and a circuit board 22 for controlling the power supply to the vibration-type linear actuator 40 in response to pressing an externally exposed operating switch 24. Examples of the battery 23 housed within the cavity formed within the main body housing 21 include dry cell batteries and rechargeable batteries that are shaped similarly to and interchangeable with dry cell batteries (e.g., rechargeable batteries in the shape of dry cells). Furthermore, a control unit 221 for controlling the voltage applied to the electromagnet 52 of the vibration-type linear actuator 40, described later, is formed on the circuit board 22.

[0040] On the other hand, the handle 30 (i.e., an example of a driven body) is provided with a handle main body 31 elongated in the X direction (i.e., the front-rear direction, the first direction, or the axial direction of the output shaft) and a brush portion 32 provided continuously with the front end of the handle main body 31. In the present embodiment, the vibration-type linear actuator 40 is housed in the main body housing 21 in a state in which the connected portion 6161 formed on the output shaft 616 is exposed to the outside of the main body housing 21. Also, by connecting the connected portion 311 formed on the rear end portion of the handle main body 31 to the connected portion 6161 exposed to the outside of the main body housing 21 in a releasable manner, the handle main body 31 is detachably linked with the output shaft 616.

[0041] In addition, the plurality of bristles 321 (i.e., a brush bundle) are provided in the upper surface of the brush portion 32 in a manner such that the plurality of bristles 321 (i.e., a brush bundle) protrude upward, and the brush portion 32 in which the plurality of bristles 321 (i.e., a brush bundle) are provided in the bore can be put into the oral cavity of the user or the like.

[0042] In addition, in the present embodiment, when the vibration-type linear actuator 40 is driven, the output shaft 616 reciprocates in the X direction (i.e., the front-rear direction, the first direction, or the axial direction of the output shaft). Therefore, when the vibration-type linear actuator 40 is driven in a state in which the handle 30 (i.e., an example of a driven body) is linked with the output shaft 616, the handle 30 (i.e., an example of a driven body) also reciprocates in the X direction (i.e., the front-rear direction, the first direction, or the axial direction of the output shaft) in conjunction with the reciprocation of the output shaft 616. That is, the bristles 321 (i.e., a brush bundle) provided in the bore of the brush portion 32 reciprocate (i.e., an example of vibration) in the X direction (i.e., the front-rear direction, the first direction, or the axial direction of the output shaft).

[0043] Also, in a state in which the bristles 321 (i.e., a brush bundle) vibrate in the X direction (i.e., the front-rear direction, the first direction, or the axial direction of the output shaft), the user holds the holding portion 211 (i.e., an example of a holding portion) by hand and puts the bristles 321 (i.e., a brush bundle) into the oral cavity to perform tooth brushing, and food residue, dental plaque, or the like can be removed.

[0044] As such, the electric toothbrush 10 (i.e., an example of an oral hygiene device) according to the present embodiment is a device for performing cleaning or the like of the oral cavity (e.g., teeth, gums, or the like) of the user or the like by the bristles 321 (i.e., a brush bundle) that vibrate in the X direction (i.e., the front-rear direction, the first direction, or the axial direction of the output shaft).

[0045] Further, the handle 30 (i.e., an example of the driven body) is configured to relatively reciprocate in the X direction (i.e., the front-rear direction, the first direction, or the axial direction of the output shaft) with respect to the main body 20. Thus, the electric toothbrush 10 (i.e., an example of the oral hygiene device) according to the present embodiment is housed in the main body 20 in a state in which the vibration-type linear actuator structure 100 is formed by linking the vibration-type linear actuator 40 to the handle 30 (i.e., an example of the driven body) so that the handle 30 (i.e., an example of the driven body) can relatively reciprocate in the X direction (i.e., the front-rear direction, the first direction, or the axial direction of the output shaft) with respect to the main body 20. Figure 2 is a perspective view illustrating an example of the vibration-type linear actuator structure 100 according to the present embodiment. The electric toothbrush 10 (i.e., an example of the oral hygiene device) according to the present embodiment is provided with the vibration-type linear actuator structure 100 as illustrated in Figure 2 .

[0046] Next, the specific structure of the vibration-type linear actuator 40 that constitutes a part of the vibration-type linear actuator structure 100 will be described.

[0047] Figure 3 is a perspective view illustrating an example of the vibration-type linear actuator 40 according to the present embodiment. Figure 4 is a plan view illustrating an example of the vibration-type linear actuator 40 according to the present embodiment. Figure 5 is a side view illustrating an example of the vibration-type linear actuator 40 according to the present embodiment. Figure 6 is a back view illustrating an example of the vibration-type linear actuator 40 according to the present embodiment. Figure 7 is a front view illustrating an example of the vibration-type linear actuator 40 according to the present embodiment. Figure 8 is a rear view illustrating an example of the vibration-type linear actuator 40 according to the present embodiment. As illustrated in Figures 3 to 8 , the vibration-type linear actuator 40 is provided with an electromagnetic block 50 having an electromagnet 52. In addition, the vibration-type linear actuator 40 is provided with a magnetic block 60 having a permanent magnet 63 that is disposed so as to face the electromagnet 52 across a gap, and the magnetic block 60 is capable of relatively reciprocating in the X direction (i.e., the front-rear direction, the first direction, or the axial direction of the output shaft) with respect to the electromagnetic block 50 by a periodically varying magnetic field.

[0048] As illustrated in Figure 3 and Figure 5 , the electromagnetic block 50 is provided with the electromagnet 52 that is capable of generating a periodically varying magnetic field, and a fixed portion 51 that is capable of fixing the vibration-type linear actuator 40 to the main body housing 21 in a state in which the electromagnet 52 is held so as to allow reciprocation of the output shaft 616.

[0049] In the present embodiment, the fixing portion 51 includes a first fixing plate 511 for fixing and holding the electromagnet 52, and a second fixing plate 512 to which the first fixing plate 511 is fixed. Further, the vibration-type linear actuator 40 is fixed to the main body case 21 in a state of allowing the reciprocating movement of the output shaft 616 by fixing the second fixing plate 512 to a fixing portion (not shown) formed on the inside of the main body case 21. In addition, in the present embodiment, the first fixing plate 511 and the second fixing plate 512 are fixed by a fastening member 531 such as a rivet.

[0050] Further, in the present embodiment, the fixing portion 51 includes a pair of link plates 513 fixed to both end portions in the X direction (i.e., the front-rear direction, the first direction, or the axial direction of the output shaft) of the second fixing plate 512. Further, the link spring 80 for linking the magnetic block 60 is linked to each of the pair of link plates 513 in a state of being able to be elastically deformed (i.e., an example of elastic deformation) in the X direction (i.e., the front-rear direction, the first direction, or the axial direction of the output shaft).

[0051] Specifically, the pair of link plates 513 includes a lower fixing portion 5131 fixed to the second fixing plate 512, an upper fixing portion 5132 to which the upper end of the link spring 80 (more specifically, the first spring 81 and the third spring 83 described later) is fixed, and a linking portion 5133 for linking the lower fixing portion 5131 and the upper fixing portion 5132.

[0052] Further, in the present embodiment, the upper spring fixing portion 71 is fixed to the upper fixing portion 5132 by a fastening member 533 such as a rivet. Further, the upper end of the first spring 81 and the third spring 83 is fixed to the upper spring fixing portion 71 by a fastening member 751 such as a rivet.

[0053] As such, in the present embodiment, one end (more specifically, the upper end) of the first spring 81 and the third spring 83 is fixed to the link plate 513 via the upper spring fixing portion 71, and the other end (more specifically, the lower end) is fixed to the magnetic block 60. By so doing, the magnetic block 60 is fixed to the link plate 513 via the first spring 81 and the third spring 83 (i.e., elements of the link spring 80), and the magnetic block 60 is relatively reciprocated in the X direction (i.e., the front-rear direction, the first direction, or the axial direction of the output shaft) with respect to the electromagnet block 50. In addition, in the present embodiment, the second fixing plate 512 and the link plate 513 are fixed by a fastening member 532 such as a rivet.

[0054] On the other hand, the electromagnet 52 includes a core 521 that forms a main magnetic path of magnetic flux generated when the electromagnet 52 is driven, a bobbin 522 held to the core 521, and a coil 523 wound around the bobbin 522.

[0055] For example, the core 521 can be formed of a soft magnetic material (i.e., soft magnet) that has a small coercive force and a high permeability. In the present embodiment, the core 521 is formed of an electromagnetic steel sheet that allows many magnetic lines of force to pass therethrough.

[0056] For example, the bobbin 522 can be formed of a material having electrical insulation, such as synthetic resin. The coil 523 formed of an electrically conductive material is wound around the outer surface of the bobbin 522. Moreover, when an alternating current is supplied to the coil 523 in a state in which the coil 523 is wound around the outer surface of the bobbin 522, magnetic flux (i.e., magnetic path) that passes through the core 521 is generated, and a magnetic pole surface in which N poles and S poles are periodically alternated is formed on the upper end surface of the core 521.

[0057] As shown in FIG. 6, the magnetic block 60 includes a first movable body 61 and a second movable body 62 that are fixed to the link plate 513 via a link spring 80. Figures 3 to 5

[0058] Specifically, the link spring 80 includes a first spring 81, a second spring 82, and a third spring 83. The first movable body 61 is fixed to the link plate 513 via the first spring 81. In addition, the second movable body 62 is fixed to the link plate 513 via the third spring 83. In the present embodiment, the first movable body 61 and the second movable body 62 are linked by the second spring 82.

[0059] As described above, in the present embodiment, the magnetic block 60 includes the first movable body 61 that is linked to the electromagnet block 50 via the first spring 81, and the second movable body 62 that is linked to the first movable body 61 via the second spring 82 and is linked to the electromagnet block 50 via the third spring 83.

[0060] ​In this embodiment, the first movable body 61 is substantially rectangular plate-shaped and elongated in the X direction (i.e., the front-rear direction, the first direction, or the axial direction of the output shaft), and includes: an opposing wall 611 disposed above the electromagnet 52 so as to face the electromagnet 52 with a gap therebetween; and a pair of fixed walls 612 continuously provided from both sides of the opposing wall 611 in the X direction (i.e., the front-rear direction, the first direction, or the axial direction of the output shaft) so as to extend downward and away from the electromagnet 52. Further, a permanent magnet 614 is fixed to the lower surface of the opposing wall 611 with a back yoke 615 interposed therebetween. In this embodiment, the back yoke 615 and the permanent magnet 614 are fixed to the lower surface of the opposing wall 611 by a fastening member 617 such as a rivet. Alternatively, the back yoke 615 and the permanent magnet 614 can be adhered to the lower surface of the opposing wall 611. In this way, the permanent magnet 614 of the permanent magnet 63 of the magnetic block 60 faces the electromagnet 52 in the up-down direction with a gap therebetween. In addition, the lower ends of the first springs 81 are respectively connected to the lower ends of the pair of fixed walls 612.

[0061] Further, in this embodiment, the first movable body 61 includes an extension wall 613 continuously provided from the front end of the opposing wall 611 so as to protrude further forward than the front-side connecting plate 513. The extension wall 613 is curved so that the front end portion thereof faces downward, and an output shaft fixing portion 6131 is formed at the portion of the extension wall 613 that is curved downward so as to protrude forward. Further, an output shaft 616 is fixed to the output shaft fixing portion 6131.

[0062] On the other hand, the second movable body 62 includes: a one-side weight 621 disposed on one side in the Y direction (i.e., the width direction or the third direction) of the first movable body 61; another-side weight 622 disposed on the other side in the Y direction (i.e., the width direction or the third direction) of the first movable body 61; and a connecting wall 623 connecting the one-side weight 621 and the another-side weight 622.

[0063] Further, the one-side weight 621 includes an opposing wall 6211 that is substantially rectangular plate-shaped and elongated in the X direction (i.e., the front-rear direction, the first direction, or the axial direction of the output shaft), and is disposed above the electromagnet 52 so as to face the electromagnet 52 with a gap therebetween and so as to face the opposing wall 611 with a gap therebetween in the Y direction (i.e., the width direction or the third direction). In addition, the one-side weight 621 includes a pair of fixed walls 6212 continuously provided from both sides of the opposing wall 6211 in the X direction (i.e., the front-rear direction, the first direction, or the axial direction of the output shaft) so as to extend downward and away from the electromagnet 52.

[0064] Similarly, the other-side weight 622 has a facing wall 6221 that is a substantially rectangular plate shape elongated in the X direction (i.e., the front-rear direction, the first direction, or the axial direction of the output shaft), and that is arranged above the electromagnet 52 so as to face the electromagnet 52 with a gap therebetween and so as to face the facing wall 611 with a gap therebetween in the Y direction (i.e., the width direction or the third direction). In addition, the other-side weight 622 has a pair of fixed walls 6222 that are continuously provided from both sides of the facing wall 6221 in the X direction (i.e., the front-rear direction, the first direction, or the axial direction of the output shaft) so as to extend downward and away from the electromagnet 52.

[0065] Furthermore, the fixed wall 6212 on the front side of the one-side weight 621 and the fixed wall 6222 on the front side of the other-side weight 622 are joined by the joining wall 623. In addition, the fixed wall 6212 on the rear side of the one-side weight 621 and the fixed wall 6222 on the rear side of the other-side weight 622 are joined by the joining wall 623.

[0066] Furthermore, the lower ends of the third springs 83 are joined to the lower ends of the fixed walls 6212, respectively, and the lower ends of the third springs 83 are joined to the lower ends of the fixed walls 6222, respectively. In addition, the fixed wall 612 on the front side of the first movable body 61 and the fixed wall 6212 on the front side of the one-side weight 621 are fixed by the second springs 82, and the fixed wall 612 on the rear side of the first movable body 61 and the fixed wall 6212 on the rear side of the other-side weight 622 are fixed by the second springs 82.

[0067] In the present embodiment, the lower end of the first spring 81 and one end of the second spring 82 are fixed to the lower end of the fixed wall 612 by the first lower-side spring fixing portion 72 using a rivet or the like fastening member 752, whereby the lower end of the first spring 81 and one end of the second spring 82 are fixed to the lower end of the fixed wall 612.

[0068] In addition, the lower end of the third spring 83 on one side in the Y direction (i.e., the width direction or the third direction) is fixed to the lower end of the fixed wall 6212 of the one-side weight 621 by the second lower-side spring fixing portion 73 using a rivet or the like fastening member 753, whereby the lower end of the third spring 83 is fixed to the lower end of the fixed wall 6212. At this time, the other end of the second spring 82 is fixed to the lower end of the fixed wall 6212 on the front side of the one-side weight 621 together with the lower end of the third spring 83.

[0069] Further, the lower end of the third spring 83 on the other side in the Y direction (i.e., the width direction or the third direction) is fixed to the lower end of the fixed wall 6222 of the other-side weight block 622 by the rivet or the like fastening member 754 using the third lower-side spring fixing portion 74, thereby fixing the lower end of the third spring 83 to the lower end of the fixed wall 6222. At this time, the other end of the second spring 82 is fixed to the lower end of the fixed wall 6222 on the rear side of the other-side weight block 622 together with the lower end of the third spring 83.

[0070] Further, in the present embodiment, as the first spring 81 and the third spring 83, a leaf spring configured to have a surface substantially coincident with the YZ plane is used. In addition, as the second spring 82, a spring in which a plurality of spring pieces having a torsion portion are stacked in the X direction (i.e., the front-rear direction, the first direction, or the axial direction of the output shaft) is used.

[0071] As such, in the present embodiment, the electromagnetic block 50 has only one electromagnet 52. In addition, the magnetic block 60 has two movable bodies (i.e., the first movable body 61 and the second movable body 62) that are capable of reciprocating independently of each other in the X direction (i.e., the front-rear direction, the first direction, or the axial direction of the output shaft).

[0072] Further, by driving one electromagnet 52, the two movable bodies (i.e., the first movable body 61 and the second movable body 62) are capable of reciprocating in the X direction (i.e., the front-rear direction, the first direction, or the axial direction of the output shaft) at phases opposite to each other. As such, by using one electromagnet 52 to reciprocate the first movable body 61 and the second movable body 62, miniaturization of the vibration-type linear actuator 40 capable of reciprocating the first movable body 61 and the second movable body 62 can be achieved.

[0073] In addition, in the present embodiment, the output shaft 616 for mounting the handle 30 (i.e., an example of a driven body) is formed in only one of the two movable bodies (i.e., the first movable body 61). Further, the first movable body 61 in which the output shaft 616 is formed is located at the center in the Y direction (i.e., the width direction or the third direction).

[0074] By doing so, it is possible to suppress the vibration generated when the two movable bodies (i.e., the first movable body 61 and the second movable body 62) reciprocate in the X direction (i.e., the front-rear direction, the first direction, or the axial direction of the output shaft).

[0075] The vibration-type linear actuator 40 having such a structure is particularly suitable for use in a device in which one driven body (e.g., the handle 30) reciprocates in the axial direction, such as the electric toothbrush 10 (i.e., an example of an oral hygiene device).

[0076] Moreover, by the periodically varying magnetic field generated when the electromagnet 52 is driven, the first movable body 61 in which the handle 30 (i.e., an example of a driven body) is installed and the second movable body 62 linked to the first movable body 61 via the second spring 82 are caused to reciprocate in the X direction (i.e., the front-rear direction, the first direction, or the axial direction of the output shaft) at phases opposite to each other.

[0077] That is, the first movable block 110 composed of a member in which the handle 30 (i.e., an example of a driven body) having the output shaft 616 installed in the first movable body 61 and reciprocating together with the first movable body 61, and the second movable block 120 composed of a member reciprocating together with the second movable body 62 are caused to reciprocate in the X direction (i.e., the front-rear direction, the first direction, or the axial direction of the output shaft) at phases opposite to each other.

[0078] At this time, it is preferable that the two movable bodies (i.e., the first movable body 61 and the second movable body 62) not only reciprocate at phases opposite to each other but also reciprocate at more complex motions.

[0079] Therefore, in the present embodiment, the first movable body 61 and the second movable body 62 not only reciprocate at phases opposite to each other but also reciprocate at the same phase.

[0080] Specifically, the permanent magnet 63 is provided to at least either one of the first movable body 61 and the second movable body 62 so that the magnetic force of the first movable body 61 is different from the magnetic force of the second movable body 62. The magnetic force of each movable body can be obtained, for example, by measuring the magnetic flux density of the permanent magnet 63 using a gauss meter or the like.

[0081] By so doing, the thrust acting on the first movable body 61 and the thrust acting on the second movable body 62 are different when the vibration-type linear actuator 40 is driven.

[0082] Furthermore, the thrust acting on the first movable body 61 and the thrust acting on the second movable body 62 can be made different by the method shown below.

[0083] For example, the thrust acting on the first movable body 61 and the thrust acting on the second movable body 62 can be made different by providing the same permanent magnet 63 to the first movable body 61 and the second movable body 62, and making the shape of the portion of the stator (e.g., the fixed portion 51 of the electromagnet block 50) facing the first movable body 61 and the shape of the portion facing the second movable body 62 different.

[0084] Further, it is also possible to make the thrust acting on the first movable body 61 different from the thrust acting on the second movable body 62 by providing the same permanent magnet 63 to the first movable body 61 and the second movable body 62, and making the shape of the portion of the stator (for example, the fixed portion 51 of the electromagnetic block 50) facing the first movable body 61 and the shape of the portion of the stator (for example, the fixed portion 51 of the electromagnetic block 50) facing the second movable body 62 the same, on the basis of which the gap length between the first movable body 61 and the stator (for example, the fixed portion 51 of the electromagnetic block 50) and the gap length between the second movable body 62 and the stator (for example, the fixed portion 51 of the electromagnetic block 50) are made different.

[0085] Further, it is also possible to make the thrust acting on the first movable body 61 different from the thrust acting on the second movable body 62 by making the permanent magnet 63 provided to one of the first movable body 61 and the second movable body 62 protrude from the stator (for example, the fixed portion 51 of the electromagnetic block 50).

[0086] Further, it is also possible to make the thrust acting on the first movable body 61 different from the thrust acting on the second movable body 62 by disposing a conductor between one of the first movable body 61 and the second movable body 62 and the stator (for example, the fixed portion 51 of the electromagnetic block 50), or on the side surface of the one movable body, and making the thrust acting on the first movable body 61 different from the thrust acting on the second movable body 62 by utilizing the braking by eddy current.

[0087] For example, it is possible to obtain the thrust acting on each movable body by measuring the thrust when the current flows through the coil 523 using a load sensor or the like.

[0088] Here, in the present embodiment, the permanent magnet 614 as the permanent magnet 63 is provided only to the first movable body 61 among the first movable body 61 and the second movable body 62, and the permanent magnet 63 is not provided to the second movable body 62. By so doing, the magnetic force of the first movable body 61 is made different from the magnetic force of the second movable body 62. As such, in the present embodiment, the magnetic force of the second movable body 62, which is the smaller magnetic force among the magnetic force of the first movable body 61 and the magnetic force of the second movable body 62, is made zero (more specifically, 50% or less of the magnetic force of the first movable body 61, which is the larger magnetic force).

[0089] Thus, the vibration-type linear actuator 40 according to the present embodiment has the first movable body 61 and the second movable body 62 approximated by the vibration model shown in FIG. 6. Figure 9 The first movable body 61 and the second movable body 62 are approximated by the vibration model shown in FIG. 6.

[0090] That is, the vibration-type linear actuator 40 according to the present embodiment has a structure in which the first movable body 61 having the permanent magnet 63 is fixed to the stator (for example, the fixed portion 51 of the electromagnet block 50) by the first spring 81, and the second movable body 62 not having the permanent magnet 63 is fixed to the stator (for example, the fixed portion 51 of the electromagnet block 50) by the second spring 82.

[0091] Figure 9 is a diagram schematically showing a vibration model of an example of the vibration-type linear actuator 40 according to the present embodiment. The driving electromagnet 52 is driven to vibrate the first movable body 61 and the second movable body 62 shown in the vibration model Figure 9 .

[0092] Figure 10 is a diagram showing frequency characteristics of the first movable body 61 and the second movable body 62 according to the present embodiment. In addition, when the magnetic force of the first movable body 61 and the magnetic force of the second movable body 62 are made different as in the vibration model Figure 9 shown, it is known that the two movable bodies (that is, the first movable body 61 and the second movable body 62) have the frequency characteristics shown in Figure 10 . That is, it is known that there are a frequency at which the amplitude becomes large in the same phase (that is, resonance in the same phase) and a frequency at which the amplitude becomes large in the opposite phase (that is, resonance in the opposite phase). Furthermore, when the difference between the magnetic force of the first movable body 61 and the magnetic force of the second movable body 62 becomes large, the amplitude at the frequency at which the amplitude becomes large in the same phase also becomes large.

[0093] Therefore, in the present embodiment, the first movable body 61 and the second movable body 62 are vibrated using two resonance frequencies (that is, a frequency at which the amplitude becomes large in the same phase and a frequency at which the amplitude becomes large in the opposite phase).

[0094] Specifically, a voltage V that becomes a waveform obtained by superimposing two different waveforms is applied to the electromagnet 52 at the time of driving the electromagnet 52. Figure 11 is a diagram showing a waveform of the voltage applied to the electromagnet 52 according to the present embodiment. In the present embodiment, a voltage V that becomes the waveform shown in Figure 11 is applied to the electromagnet 52.

[0095] Furthermore, the voltage V shown in Figure 11 is V = sin(ω1t) + sin(ω2t). Thus, in the present embodiment, at the time of driving the electromagnet 52, a voltage V of a resultant wave (that is, a wave obtained by synthesizing two sine waves having different frequencies) obtained by synthesizing waveforms of two different frequencies is applied to the electromagnet 52. Here, ω1 is a frequency at which the amplitude becomes large in the same phase, and it is preferable that ω1 be based on the frequency of the first movable body 61 and the frequency of the second movable body 62. Furthermore, ω2 is a frequency at which the amplitude becomes large in the opposite phase, and it is preferable that ω2 be based on the frequency of the first movable body 61 and the frequency of the second movable body 62.Figure 10 The ω1 is set in the range of 20 Hz to 60 Hz based on the frequency characteristics shown in FIG. 7. In this case, the amplitude in the same phase can be set to 1.0 mm or more. At this time, if the ω1 is set to 48 Hz, the amplitude in the same phase can be the maximum amplitude. In addition, the ω2 is a frequency at which the amplitude in the opposite phase becomes large, and is preferably set in the range of 250 Hz to 280 Hz based on the frequency characteristics shown in FIG. 7. In this case, the amplitude in the opposite phase can be set to 0.2 mm or more. At this time, if the ω2 is set to 270 Hz, the amplitude in the opposite phase can be the maximum amplitude. Figure 10 The ω1 is set in the range of 20 Hz to 60 Hz based on the frequency characteristics shown in FIG. 7. In this case, the amplitude in the same phase can be set to 1.0 mm or more. At this time, if the ω1 is set to 48 Hz, the amplitude in the same phase can be the maximum amplitude. In addition, the ω2 is a frequency at which the amplitude in the opposite phase becomes large, and is preferably set in the range of 250 Hz to 280 Hz based on the frequency characteristics shown in FIG. 7. In this case, the amplitude in the opposite phase can be set to 0.2 mm or more. At this time, if the ω2 is set to 270 Hz, the amplitude in the opposite phase can be the maximum amplitude.

[0096] As described above, the first movable body 61 and the second movable body 62 are vibrated by the electromagnetic body 52 to which the voltage V shown in FIG. 7 is applied, and thus the first movable body 61 and the second movable body 62 reciprocate at a frequency at which the amplitude in the opposite phase becomes large and at a frequency at which the amplitude in the same phase becomes large. Figure 11 The first movable body 61 and the second movable body 62 that approximate the vibration model shown in FIG. 7 are vibrated, and thus the first movable body 61 and the second movable body 62 reciprocate at a frequency at which the amplitude in the opposite phase becomes large and at a frequency at which the amplitude in the same phase becomes large. Figure 9 The first movable body 61 and the second movable body 62 that approximate the vibration model shown in FIG. 7 are vibrated, and thus the first movable body 61 and the second movable body 62 reciprocate at a frequency at which the amplitude in the opposite phase becomes large and at a frequency at which the amplitude in the same phase becomes large.

[0097] Specifically, the first movable body 61 and the second movable body 62 reciprocate while performing a short-period fine reciprocation in opposite phases to each other and while performing a relatively large reciprocation having a longer period than the fine reciprocation in the same phase to each other. That is, the first movable body 61 and the second movable body 62 not only reciprocate while performing a single vibration in opposite phases to each other but also reciprocate while performing a single vibration in the same phase to each other and having a longer period than the single vibration in opposite phases to each other, and thus reciprocate while performing a more complex motion.

[0098] In the present embodiment, the weight of the first movable body 61 and the second movable body 62 is set so that the weight ml of the first movable block 110 that has the first movable body 61 and the handle portion 30 connected to the first movable body 61 (i.e., an example of a driven body) and that reciprocates with the first movable body 61 and the weight m2 of the second movable block 120 that reciprocates with the second movable body 62 are substantially the same. Here, the first movable block 110 refers to a single member that reciprocates with the first movable body 61, and in the present embodiment, at least includes the first movable body 61 and the handle portion 30 connected to the first movable body (i.e., an example of a driven body). In addition, the second movable block 120 refers to a single member that reciprocates with the second movable body 62, and at least includes the second movable body 62.

[0099] As such, in the present embodiment, the weights of the first movable body 61 and the second movable body 62 are set so that the weight ml of the first movable block 110, which includes at least the first movable body 61 and the handle 30 (i.e., an example of a driven body) and which reciprocates together with the first movable body 61, and the weight m2 of the second movable block 120, which includes at least the second movable body 62 and which reciprocates together with the second movable body 62, are substantially the same. That is, in the case where the electric toothbrush 10 (i.e., an example of an oral hygiene device) is provided, the weight of the single member that reciprocates together with the first movable body 61 is made the same as the weight of the single member that reciprocates together with the second movable body 62. Thus, in the present embodiment, the weight of the first movable body 61 is lighter than the weight of the second movable body 62.

[0100] As such, as a method of making the weight of the first movable body 61 lighter than the weight of the second movable body 62, for example, there is a method of forming at least a portion of the second movable body 62 using brass having a larger specific gravity and forming at least a portion of the first movable body 61 using resin having a smaller specific gravity.

[0101] Further, by making the weight ml of the first movable block 110 and the weight m2 of the second movable block 120 substantially the same, it is possible to more reliably suppress the vibration generated when the handle 30 (i.e., an example of a driven body) is driven (e.g., caused to reciprocate).

[0102] Further, regarding the operation of the first movable block 110 and the second movable block 120 in the case where the vibration-type linear actuator structure 100 related to the present embodiment is used and the above-described voltage V is applied to the electromagnet 52, it is possible to approximate by a forced vibration model in which an external force F exists in the mass-spring-damper system shown in FIG. 8. Figure 12

[0103] Figure 12 is a diagram schematically showing a vibration model of an example of the vibration-type linear actuator structure 100 related to the present embodiment. In the diagram, the vibration-type linear actuator structure 100 is shown as a mass-spring-damper system. Figure 12 ​In the vibration model of the mass-spring-damper system shown, the following structure is achieved: a first movable mass 110, which is fixed to a stator (e.g., the fixed portion 51 of the electromagnetic block 50) via a first spring 81 with a spring constant k1 and a first damper 91 with a damping coefficient c1, is connected to a second movable mass 120, which is fixed to a stator (e.g., the fixed portion 51 of the electromagnetic block 50) via a third spring 83 with a spring constant k3 and a third damper 93 with a damping coefficient c3, via a second spring 82 with a spring constant k2 and a second damper 92 with a damping coefficient c2. With this structure, an external force F is applied to the first movable mass 110 to vibrate it, thereby vibrating both the first movable mass 110 and the second movable mass 120. The external force F applied to the first movable mass 110 is a constant multiplied by sin(ω1t)+sin(ω2t).

[0104] Furthermore, when the vibration type linear actuator structure 100 according to this embodiment is used and the voltage V is applied to the electromagnet 52, the first movable block 110 and the second movable block 120 behave as follows. Figure 12 In the forced vibration model in which an external force F exists in the mass-spring-damper system, the first movable mass 110 and the second movable mass 120 behave in substantially the same manner. Figure 13 1 is a diagram showing the output waveform of the first movable block 110 according to the embodiment. In addition, the output waveform of the second movable block 120 is also shown. Figure 13 About the same.

[0105] Specifically, the first movable block 110 is as follows Figure 13 The second movable block 120 moves as shown in the waveform. Figure 13 Among the waveforms shown, the first movable block 110 and the second movable block 120 operate in a waveform whose phase is opposite to the phase of the waveform of the first movable block. That is, in the short-period, fine waveform, the first movable block 110 and the second movable block 120 reciprocate at a frequency with a larger amplitude at opposite phases, and in the long-period, relatively large waveform, the first movable block 110 and the second movable block 120 reciprocate at a frequency with a larger amplitude at the same phase. In other words, the first movable block 110 and the second movable block 120 perform a short-period, fine reciprocating motion in opposite phases while performing a relatively large reciprocating motion with a period longer than the period of the fine reciprocating motion in the same phase.

[0106] Thus, when the electric toothbrush 10 (i.e., an example of an oral hygiene device) using the vibration-type linear actuator 40 according to the present embodiment is set, the shank 30 (i.e., an example of a driven body), i.e., the brush portion 32 in which the bore is provided with a plurality of bristles 321 (i.e., a bundle of bristles) performs a small reciprocating motion of a short period while performing a large reciprocating motion of a period longer than that of the small reciprocating motion. Further, in the present embodiment, the amplitude of the small reciprocating motion of the short period, i.e., the reciprocating motion of opposite phases to each other is set to 0.2 mm to 1.5 mm, and the amplitude of the large reciprocating motion of the long period, i.e., the reciprocating motion of the same phase to each other is set to 1.0 mm to 2.0 mm. That is, the brush portion 32 in which the bore is provided with a plurality of bristles 321 (i.e., a bundle of bristles) as a whole performs a reciprocating motion with an amplitude of 1.2 mm to 3.5 mm.

[0107] Further, if the brush portion 32 performing a reciprocating motion in such a complex motion is put into the oral cavity to perform tooth brushing, it is possible to reduce the stimulation of the oral cavity by the vibration of the brush portion 32 and more efficiently remove food residue, dental plaque, and the like.

[0108] Further, the vibration-type linear actuator 40 can also be configured as Figure 14 shown in the drawing.

[0109] Figure 14 is a plan view showing an example of the vibration-type linear actuator 40 according to the modification. Figure 15 is a diagram schematically showing a vibration model of an example of the vibration-type linear actuator 40 according to the modification. In the vibration-type linear actuator 40 shown in Figure 14 In the vibration-type linear actuator 40 shown in

[0110] In the vibration-type linear actuator 40 shown in Figure 14 In the vibration-type linear actuator 40 shown in

[0111] In the vibration-type linear actuator 40 shown in Figure 14 The permanent magnet 6213 is fixed to the lower surface of the facing wall 6211 of the one side weight block 621 with the back yoke 6214 interposed therebetween. In addition, the permanent magnet 6223 is fixed to the lower surface of the facing wall 6221 of the other side weight block 622 with the back yoke 6224 interposed therebetween.

[0112] Further, the magnetic force of the first movable body 61 is made different from the magnetic force of the second movable body 62. In the vibration-type linear actuator 40 shown in Figure 14In the embodiment, the magnetic force of the second movable body 62, which is the smaller of the magnetic forces of the first movable body 61 and the second movable body 62, is 50% or less of the magnetic force of the first movable body 61, which is the larger of the magnetic forces.

[0113] Thus, Figure 14 The vibration-type linear actuator 40 shown in the drawing has a first movable body 61 having a large magnetic force and a second movable body 62 having a small magnetic force connected by a second spring 82. Figure 15 The first movable body 61 and the second movable body 62 shown in the drawing are approximated by a vibration model.

[0114] That is, Figure 14 The vibration-type linear actuator 40 shown in the drawing has a structure in which a first movable body 61 having a large magnetic force permanent magnet 63 and fixed to a stator (for example, a fixed portion 51 of an electromagnetic block 50) by a first spring 81 and a second movable body 62 having a small magnetic force permanent magnet 63 and fixed to a stator (for example, a fixed portion 51 of an electromagnetic block 50) by a third spring 83 are connected by a second spring 82.

[0115] Even if configured in such a structure, the same effects as those of the vibration-type linear actuator 40 shown in the above-described embodiment can be obtained.

[0116] (Postscript)

[0117] According to the above-described embodiment, the following technology is disclosed.

[0118] (Technology 1) A vibration-type linear actuator including: an electromagnetic block having an electromagnet; and a magnetic block having a permanent magnet configured to face the electromagnet across a gap, the magnetic block relatively reciprocating in a first direction with respect to the electromagnetic block by a periodically varying magnetic field, wherein the magnetic block includes: a first movable body connected to the electromagnetic block via a first spring; and a second movable body connected to the first movable body via a second spring, the vibration-type linear actuator configured such that, when a voltage that is a waveform obtained by superimposing two different waveforms is applied to the electromagnet in a state where a thrust acting on the first movable body and a thrust acting on the second movable body are different, the first movable body and the second movable body reciprocate at a frequency at which the amplitude becomes larger in opposite phases, and reciprocate at a frequency at which the amplitude becomes larger in the same phase.

[0119] As such, the vibration-type linear actuator of Technology 1 is a device that relatively reciprocates the first movable body and the second movable body in the first direction with respect to the electromagnetic block by generating a periodically varying magnetic field.

[0120] Moreover, in a state where the thrust acting on the first movable body and the thrust acting on the second movable body are different, a voltage of a waveform obtained by superimposing two different waveforms is applied to the electromagnet. By so doing, the first movable body and the second movable body perform reciprocating motion with motion at a frequency at which the amplitude becomes large in opposite phases and motion at a frequency at which the amplitude becomes large in the same phase being synthesized. In this case, it is possible to make the first movable body and the second movable body perform fine reciprocating motion of a short period in opposite phases and relatively large reciprocating motion of a period longer than that of the fine reciprocating motion in the same phase. That is, it is possible to make the first movable body and the second movable body not only perform single vibration in opposite phases but also perform single vibration of a period longer than that of the single vibration in opposite phases in the same phase.

[0121] If the vibration-type linear actuator of Technology 1 is configured as such, it is possible to make the first movable body and the second movable body perform reciprocating motion with more complex motion.

[0122] (Technology 2) The vibration-type linear actuator according to Technology 1, wherein the movable body of at least either one of the first movable body and the second movable body is provided with the permanent magnet, and the thrust acting on the first movable body and the thrust acting on the second movable body are made different by making the magnetic force of the first movable body and the magnetic force of the second movable body different.

[0123] In this case, it is possible to configure the shapes of the first movable body and the second movable body to be simple structures, and make the thrust acting on the first movable body and the thrust acting on the second movable body different.

[0124] (Technology 3) The vibration-type linear actuator according to Technology 2, wherein the movable body of only one of the first movable body and the second movable body is provided with the permanent magnet.

[0125] In this case, it is possible to more easily and reliably make the smaller one of the magnetic force of the first movable body and the magnetic force of the second movable body zero.

[0126] (Technology 4) The vibration-type linear actuator according to any one of Technologies 1 to 3, wherein the weight of the first movable body and the weight of the second movable body are different.

[0127] In this case, it is possible to make the weight on the first movable body side and the weight on the second movable body side when the driven body is connected to the first movable body or the second movable body approximately the same weight. If the weight on the first movable body side and the weight on the second movable body side when the driven body is connected are made approximately the same weight as such, it is possible to more reliably suppress vibration generated when the driven body is driven (for example, made to perform reciprocating motion).

[0128] (Technology 5) The vibration-type linear actuator according to any one of Technologies 1 to 4, wherein the electromagnetic block has only one of the electromagnets.

[0129] In this case, one electromagnet is used to reciprocate the first movable body and the second movable body, and thus the vibration-type linear actuator that can reciprocate the first movable body and the second movable body with more complex motion can be made compact.

[0130] (Technology 6) The vibration-type linear actuator according to any one of Technologies 1 to 5, wherein the second movable body is linked to the electromagnetic block via a third spring.

[0131] In this case, the first movable body and the second movable body can be more stably held to the electromagnetic block, and thus the first movable body and the second movable body can be more reliably suppressed from shaking in a direction intersecting the first direction when reciprocating the first movable body and the second movable body in the first direction.

[0132] (Technology 7) An electric toothbrush including: the vibration-type linear actuator according to any one of Technologies 1 to 6; and a handle having a brush portion, the handle being connected to the first movable body or the second movable body.

[0133] In this case, an electric toothbrush that can reciprocate the brush portion of the handle with more complex motion can be obtained. Furthermore, if such an electric toothbrush is used, the vibration of the brush portion against the oral cavity can be reduced, and food residue, dental plaque, and the like can be more efficiently removed.

[0134] (Technology 8) The electric toothbrush according to Technology 7, wherein, in a case where the handle is connected to the first movable body, the weights of the first movable body and the second movable body are set so that a weight of a first movable block including at least the first movable body and reciprocating together with the first movable body is substantially the same as a weight of a second movable block including at least the second movable body and reciprocating together with the second movable body, and, in a case where the handle is connected to the second movable body, the weights of the first movable body and the second movable body are set so that the weight of the first movable block including at least the first movable body and reciprocating together with the first movable body is substantially the same as the weight of the second movable block including at least the second movable body and the handle and reciprocating together with the second movable body.

[0135] In this case, the vibration generated when driving (e.g., reciprocating) the handle of the electric toothbrush formed using the vibration-type linear actuator can be more reliably suppressed.

[0136] [Others]

[0137] The above describes the contents of the vibration-type linear actuator and the electric toothbrush according to the present disclosure, but is not limited to these descriptions, and various modifications and improvements can be made, as will be apparent to those skilled in the art.

[0138] For example, in the above-described embodiments and modifications thereof, the vibration-type linear actuator for the electric toothbrush (i.e., an example of an oral hygiene device) as a personal care appliance is exemplified, but the vibration-type linear actuator can also be used for products other than the electric toothbrush (i.e., an example of an oral hygiene device). For example, it can be used for a shaver (i.e., an electric shaver), a hair clipper (i.e., an example of a hair cutting device), and other personal care appliances.

[0139] In addition, the present disclosure can be applied to embodiments obtained by changing, replacing, adding, omitting, and the like, of the structures shown in the above-described embodiments and modifications thereof. In addition, the respective constituent elements described in the above-described embodiments and modifications thereof can also be combined to form new embodiments.

[0140] In addition, in the above-described embodiments and modifications thereof, the case where the weight m1 of the first movable block 110 and the weight m2 of the second movable block 120 are substantially the same is exemplified, but the weight m1 of the first movable block 110 and the weight m2 of the second movable block 120 can also be made different.

[0141] In addition, the weight of the first movable body 61 and the weight of the second movable body 62 can also be made substantially the same.

[0142] In addition, in the above-described embodiments and modifications thereof, the vibration-type linear actuator 40 provided with the third spring 83 is exemplified, but the vibration-type linear actuator 40 can also be provided without the third spring 83. For example, it can also be provided as a structure in which the second movable body 62 is connected to the first movable body 61 via the second spring 82, but is not connected to the electromagnetic block 50, i.e., a structure in which it is connected only to the electromagnetic block 50 and the first movable body 61 among the first movable body 61.

[0143] In addition, the vibration-type linear actuator 40 in which the handle 30 (i.e., an example of a driven body) is connected to the first movable body 61 is exemplified, but the vibration-type linear actuator in which the handle 30 (i.e., an example of a driven body) is connected to the second movable body 62 can also be provided. In this case, it is preferable that the weights of the first movable body 61 and the second movable body 62 are set so that the weight of the first movable block 110 including at least the first movable body 61 and reciprocating together with the first movable body 61 is substantially the same as the weight of the second movable block 120 including at least the second movable body 62 and the handle 30 (i.e., an example of a driven body) and reciprocating together with the second movable body 62.

[0144] In addition, in the above-described embodiment and modifications thereof, a case where the electromagnet 52 is applied with a voltage V of a resultant wave obtained by synthesizing two different frequency waves (i.e., a wave obtained by synthesizing two sine waves having different frequencies) is exemplified, but as long as the waveform of the voltage V applied to the electromagnet 52 is a waveform obtained by superimposing two different waveforms, various waveforms can be provided. For example, the electromagnet 52 can be applied with a voltage V of a waveform obtained by superimposing different two waveforms among a sine wave, a rectangular wave, a triangular wave, a sawtooth wave, a trapezoidal wave, and the like.

[0145] Further, in the present disclosure, waves that are different in at least any one of frequency, amplitude, and phase although the shapes are the same are defined as mutually different waves. Therefore, in the above-described embodiment and modifications thereof, the two waves shown as waves to be synthesized are both sine waves but different in frequency, and thus are mutually different waves in the above-described embodiment and modifications thereof.

[0146] In addition, other specifications of details such as the electromagnet block, the magnetic block, and the like (e.g., shape, size, layout, and the like) can be appropriately changed.

[0147] Industrial Applicability

[0148] As described above, the vibration-type linear actuator and the electric toothbrush according to the present disclosure can cause the first movable body and the second movable body to reciprocate with more complex motions, and thus can be used as a part of a personal care appliance such as an electric toothbrush.

[0149] Explanation of Reference Signs

[0150] 10: electric toothbrush; 20: main body portion; 21: main body housing; 211: grip portion; 22: circuit board; 221: control portion; 23: battery; 24: operation switch; 30: handle portion; 31: handle portion main body; 311: connecting portion; 32: brush portion; 40: vibration type linear actuator; 50: electromagnetic block; 51: fixed portion; 511: first fixed plate; 512: second fixed plate; 513: connecting plate; 5131: lower side fixed portion; 5132: upper side fixed portion; 5133: connecting portion; 52: electromagnet; 521: core; 522: bobbin; 523: coil; 531: fastening member; 532: fastening member; 533: fastening member; 60: magnetic block; 61: first movable body; 611: facing wall; 612: fixed wall; 613: extension wall; 614: permanent magnet; 615: back yoke; 616: output shaft; 617: fastening member; 6161: connected portion; 62: second movable body; 621: one side weight; 6211: facing wall; 6212: fixed wall; 622: other side weight; 6221: facing wall; 6222: fixed wall; 623: connecting wall; 63: permanent magnet; 71: upper side spring fixed portion; 72: first lower side spring fixed portion; 73: second lower side spring fixed portion; 74: third lower side spring fixed portion; 751: fastening member; 752: fastening member; 753: fastening member; 754: fastening member; 80: connecting spring; 81: first spring; 82: second spring; 83: third spring; 100: vibration type linear actuator structure; 110: first movable block; 120: second movable block; F: external force; V: voltage.

Claims

1. A vibration type linear actuator comprising: an electromagnetic block having an electromagnet; and a magnetic block having a permanent magnet configured to face the electromagnet across a gap, the magnetic block relatively reciprocating in a first direction with respect to the electromagnetic block by a periodically varying magnetic field, the magnetic block comprising: a first movable body linked to the electromagnetic block via a first spring; and a second movable body linked to the first movable body via a second spring, the vibration type linear actuator configured such that, when a voltage of a waveform obtained by superimposing two different waveforms is applied to the electromagnet in a state where a thrust acting on the first movable body and a thrust acting on the second movable body are different, the first movable body and the second movable body reciprocate at a frequency at which the amplitude is larger in opposite phases and reciprocate at a frequency at which the amplitude is larger in the same phase.

2. The vibration type linear actuator according to claim 1, wherein the movable body of at least either one of the first movable body and the second movable body is provided with the permanent magnet, the thrust acting on the first movable body and the thrust acting on the second movable body are made different by making the magnetic force of the first movable body and the magnetic force of the second movable body different.

3. The vibration type linear actuator according to claim 2, wherein the movable body of only one of the first movable body and the second movable body is provided with the permanent magnet. wherein 4. The vibration type linear actuator according to any one of claims 1 to 3, wherein the weight of the first movable body and the weight of the second movable body are different.

5. The vibration type linear actuator according to any one of claims 1 to 3, wherein the electromagnetic block has only one electromagnet.

6. The vibration type linear actuator according to any one of claims 1 to 3, wherein the second movable body is linked to the electromagnetic block via a third spring.

7. An electric toothbrush comprising: the vibration type linear actuator according to any one of claims 1 to 3; and a handle portion having a brush portion, the handle portion being connected to the first movable body or the second movable body.

8. The electric toothbrush according to claim 7, wherein in a case where the handle portion is connected to the first movable body, the weights of the first movable body and the second movable body are set such that the weight of a first movable block including at least the first movable body and reciprocating together with the first movable body and the weight of a second movable block including at least the second movable body and reciprocating together with the second movable body are substantially the same, in a case where the handle portion is connected to the second movable body, the weights of the first movable body and the second movable body are set such that the weight of a first movable block including at least the first movable body and reciprocating together with the first movable body and the weight of a second movable block including at least the second movable body and the handle portion and reciprocating together with the second movable body are substantially the same. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

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