Vibration type linear actuator, and electric toothbrush

Abstract

To obtain a vibration type linear actuator capable of reciprocating a first movable body and a second movable body in a more complicated movement, and an electric toothbrush.SOLUTION: A vibration type linear actuator 40 comprises: an electromagnetic block 50 having an electromagnet 52; and a magnetic block 60 having a permanent magnet 63. The magnetic block 60 comprises a first movable body 61 and a second movable body 62, and a thrust force acting on the first movable body 61 and a thrust force acting on the second movable body 62 are different. Then, the vibration type linear actuator 40 is configured such that, when a voltage having a waveform created by two different waveforms being superimposed, is applied to the electromagnet 52, the first movable body 61 and the second movable body 62 reciprocate at a frequency that increases an amplitude in the same phases while reciprocating at a frequency that increases the amplitude in opposite phases.SELECTED DRAWING: Figure 9

Description

[Technical Field]

[0001] The present disclosure relates to an oscillatory linear actuator and an electric toothbrush. [Background technology]

[0002] Conventionally, as shown in Patent Document 1 below, a vibration type linear actuator has been known that includes an electromagnetic block having an electromagnet and a magnetic block having a permanent magnet arranged to face the electromagnet across a gap, and that causes the magnetic block to reciprocate relative to the electromagnetic block by applying electromagnetic force between the electromagnetic block and the magnetic block.

[0003] In Patent Document 1, the magnetic block includes a first movable body having a permanent magnet arranged to face the electromagnet across a gap, and a second movable body having a permanent magnet arranged to face the electromagnet across a gap. By generating periodically varying magnetic fields between the electromagnetic block and the first movable body and between the electromagnetic block and the second movable body, the first movable body and the second movable body are caused to reciprocate in opposite phases. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-128187 Summary of the Invention [Problem to be solved by the invention]

[0005] In such a vibration type linear actuator, it is preferable to make it possible to reciprocate the first movable body and the second movable body with more complex movements.

[0006] Therefore, an object of the present disclosure is to provide a vibration-type linear actuator and an electric toothbrush that are capable of reciprocating a first movable body and a second movable body with more complex movements. [Means for solving the problem]

[0007] A vibratory linear actuator according to one embodiment of the present disclosure comprises an electromagnetic block having an electromagnet, and a magnetic block having a permanent magnet arranged opposite the electromagnet across a gap, which reciprocates relative to the electromagnetic block in a first direction due to a periodically changing magnetic field, the magnetic block comprising 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, and is configured such that when a voltage having a waveform in which two different waveforms are superimposed is applied to the electromagnet, with the thrust acting on the first movable body and the thrust acting on the second movable body being different, the first movable body and the second movable body reciprocate at a frequency in which the amplitude increases in opposite phase, and at the same time reciprocate at a frequency in which the amplitude increases in the same phase.

[0008] An electric toothbrush according to one aspect of the present disclosure includes the above-described vibration type linear actuator and a handle portion having a brush portion and connected to the first movable body or the second movable body. [Effects of the Invention]

[0009] According to the present disclosure, it is possible to obtain a vibration type linear actuator and an electric toothbrush that are capable of reciprocating the first movable body and the second movable body with more complex movements. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a side view showing an example of an electric toothbrush according to an embodiment. [Figure 2] 1 is a perspective view showing an example of a vibration type linear actuator structure according to an embodiment; [Figure 3]1 is a perspective view showing an example of a vibration type linear actuator according to an embodiment; [Figure 4] 1 is a plan view showing an example of a vibration type linear actuator according to an embodiment; [Figure 5] 1 is a side view showing an example of a vibration type linear actuator according to an embodiment. [Figure 6] FIG. 2 is a rear view showing an example of a vibration type linear actuator according to an embodiment. [Figure 7] 1 is a front view showing an example of a vibration type linear actuator according to an embodiment. [Figure 8] FIG. 2 is a rear view showing an example of a vibration type linear actuator according to an embodiment. [Figure 9] FIG. 2 is a diagram schematically illustrating a vibration model of an example of a vibration type linear actuator according to an embodiment. [Figure 10] FIG. 4 is a diagram showing frequency characteristics of a first movable body and a second movable body according to the embodiment. [Figure 11] 5 is a diagram showing a waveform of a voltage applied to an electromagnet according to the embodiment; FIG. [Figure 12] 1 is a diagram schematically illustrating a vibration model of an example of a vibration type linear actuator structure according to an embodiment. FIG. [Figure 13] FIG. 4 is a diagram showing an output waveform of a first movable body according to the embodiment. [Figure 14] FIG. 10 is a plan view showing an example of a vibration type linear actuator according to a modified example. [Figure 15] FIG. 10 is a diagram schematically illustrating a vibration model of an example of a vibration type linear actuator according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments will be described in detail with reference to the drawings. However, unnecessary detailed description may be omitted. For example, detailed description of well-known matters or redundant description of substantially the same configuration may be omitted.

[0012] The accompanying 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 described in the claims.

[0013] In the following embodiments, a vibration type linear actuator used in an electric toothbrush (oral hygiene device) as a personal care product will be exemplified.

[0014] In the following embodiments, the direction in which the first movable body and the second movable body reciprocate will be described as the X direction (front-to-back direction: first direction: axial direction of the output shaft), the direction in which the electromagnet and the permanent magnet face each other will be described as the Z direction (up-down direction: second direction), and the direction intersecting (orthogonal to) the X direction and the Z direction will be described as the Y direction (width direction: third direction).

[0015] The explanation will be given by defining the up and down direction of the vibration type linear actuator in a state where the electromagnet is positioned on the lower side and the permanent magnet is positioned on the upper side.

[0016] In the following embodiments, the side from which the output shaft protrudes will be defined as the front side (front in the X direction) of the vibration type linear actuator for the sake of convenience.

[0017] (Embodiment) As shown in FIG. 1 , an electric toothbrush (oral hygiene device) 10 according to this embodiment includes a main body 20 and a handle (driven body) 30 detachably attached to the front end of the main body 20. In this embodiment, the main body 20 has an elongated shape in the X direction (front-rear direction: first direction: axial direction of the output shaft). The main body 20 includes a main body housing 21 that forms the outer shell of the main body 20. The main body housing 21 is formed with a grip portion (handhold portion) 211 that can be held by hand. The main body housing 21 can be formed by joining multiple segments using a material such as synthetic resin. The multiple segments can be joined together, for example, by using screws or by fitting the segments together. An operation switch 24 is attached to the main body housing 21 so that it can be pushed inward while being exposed to the outside.

[0018] Furthermore, in this embodiment, a cavity is formed inside the main housing 21, which is formed by joining multiple divided bodies, and various electrical components such as the vibration type linear actuator 40 are housed in this cavity.

[0019] In this embodiment, the cavity formed inside the main body housing 21 accommodates the vibration type linear actuator 40 excluding the tip (front end) of the output shaft 616, a battery 23 that drives the vibration type linear actuator 40, a circuit board 22 that controls the power supply to the vibration type linear actuator 40 in response to the depression of an operation switch 24 exposed to the outside, etc. The battery 23 accommodated in the cavity formed inside the main body housing 21 may be, for example, a dry battery or a rechargeable battery (dry battery-shaped rechargeable battery) that has the same shape as a dry battery and is compatible with dry batteries. In addition, the circuit board 22 is formed with a control unit 221 that controls the voltage applied to an electromagnet 52 (described later) of the vibration type linear actuator 40.

[0020] On the other hand, the handle (driven body) 30 includes a handle body 31 that is elongated in the X direction (front-rear direction: first direction: axial direction of the output shaft) and a brush part 32 that is connected to the front end of the handle body 31. In this embodiment, the vibration type linear actuator 40 is housed in the main body housing 21 with a connected part 6161 formed on the output shaft 616 exposed to the outside of the main body housing 21. The connecting part 311 formed on the rear end of the handle body 31 is releasably connected to the connected part 6161 exposed to the outside of the main body housing 21, so that the handle body 31 is detachably coupled to the output shaft 616.

[0021] In addition, multiple bristles (brush bundles) 321 are drilled into the upper surface of the brush part 32 so that they protrude upward, allowing the brush part 32 with multiple bristles (brush bundles) 321 drilled therein to be introduced into the oral cavity of a user, etc.

[0022] Furthermore, in this embodiment, when the vibration linear actuator 40 is driven, the output shaft 616 reciprocates in the X direction (front-rear direction: first direction: axial direction of the output shaft). Therefore, when the vibration linear actuator 40 is driven with the handle portion (driven body) 30 connected to the output shaft 616, the handle portion (driven body) 30 also reciprocates in the X direction (front-rear direction: first direction: axial direction of the output shaft) in conjunction with the reciprocating movement of the output shaft 616. In other words, the bristles (brush bundles) 321 provided in the brush portion 32 reciprocate (vibrate) in the X direction (front-rear direction: first direction: axial direction of the output shaft).

[0023] Then, with the bristles (brush bundle) 321 vibrating in the X direction (front-back direction: first direction: axial direction of the output shaft), the user can hold the grip portion (holding portion) 211 with their hand, insert the bristles (brush bundle) 321 into their mouth, and brush their teeth to remove food debris, plaque, etc.

[0024] As described above, the electric toothbrush (oral hygiene device) 10 according to this embodiment is a device for cleaning the inside of the oral cavity (teeth, gums, etc.) of a user or the like by vibrating bristles (brush bundles) 321 in the X direction (front-back direction: first direction: axial direction of the output shaft).

[0025] The handle portion (driven body) 30 is configured to reciprocate relatively to the main body portion 20 in the X direction (front-rear direction: first direction: axial direction of the output shaft). Therefore, the electric toothbrush (oral hygiene device) 10 according to this embodiment is formed by accommodating a part of a vibratory linear actuator structure 100 formed by connecting the handle portion (driven body) 30 to the vibratory linear actuator 40 within the main body portion 20 in a state in which the handle portion (driven body) 30 can reciprocate relatively to the main body portion 20 in the X direction (front-rear direction: first direction: axial direction of the output shaft). That is, the electric toothbrush (oral hygiene device) 10 according to this embodiment includes a vibratory linear actuator structure 100 as shown in FIG. 2.

[0026] Next, a specific configuration of the vibration type linear actuator 40 that constitutes a part of the vibration type linear actuator structure 100 will be described.

[0027] 3 to 8, the vibration type linear actuator 40 includes an electromagnetic block 50 having an electromagnet 52. The vibration type linear actuator 40 also includes a magnetic block 60 having a permanent magnet 63 arranged to face the electromagnet 52 across a gap, and capable of reciprocating relative to the electromagnetic block 50 in the X direction (front-back direction: first direction: axial direction of the output shaft) due to a periodically varying magnetic field.

[0028] As shown in Figures 3 and 5, the electromagnetic block 50 includes an electromagnet 52 capable of generating a periodically varying magnetic field, and a fixing portion 51 capable of fixing the vibration type linear actuator 40 to the main body housing 21 while holding the electromagnet 52, in a state in which the reciprocating motion of the output shaft 616 is permitted.

[0029] In this embodiment, the fixing portion 51 includes a first fixing plate 511 that fixes and holds the electromagnet 52, and a second fixing plate 512 to which the first fixing plate 511 is fixed. The second fixing plate 512 is fixed to a fixed portion (not shown) formed inside the main body housing 21, so that the vibration type linear actuator 40 is fixed to the main body housing 21 in a state in which the output shaft 616 is allowed to reciprocate. In this embodiment, the first fixing plate 511 and the second fixing plate 512 are fixed by fastening parts 531 such as rivets.

[0030] Furthermore, in this embodiment, the fixed portion 51 includes a pair of connecting plates 513 fixed to both ends of the second fixed plate 512 in the X direction (front-rear direction: first direction: axial direction of the output shaft). Each of the pair of connecting plates 513 is connected to a connecting spring 80 for connecting the magnetic block 60 in a state in which it can be flexibly deformed (elastically deformed) in the X direction (front-rear direction: first direction: axial direction of the output shaft).

[0031] Specifically, the pair of connecting plates 513 include a lower fixing portion 5131 fixed to the second fixing plate 512, an upper fixing portion 5132 to which the upper ends of the connecting springs 80 (first spring 81 and third spring 83 described later) are fixed, and a connecting portion 5133 that connects the lower fixing portion 5131 and the upper fixing portion 5132.

[0032] Furthermore, in this embodiment, upper spring fixing portion 71 is fixed to upper fixing portion 5132 with fastening parts 533 such as rivets. The upper ends of first spring 81 and third spring 83 are fixed to upper spring fixing portion 71 with fastening parts 751 such as rivets.

[0033] As described above, in the present embodiment, first spring 81 and third spring 83 have one end (upper end) fixed to connecting plate 513 via upper spring fixing portion 71, and the other end (lower end) fixed to magnetic block 60. In this manner, magnetic block 60 is fixed to connecting plate 513 via first spring 81 and third spring 83 (connecting spring 80), and magnetic block 60 can be reciprocated relative to electromagnetic block 50 in the X direction (front-rear direction: first direction: axial direction of the output shaft). Note that in the present embodiment, second fixing plate 512 and connecting plate 513 are fixed by fastening parts 532 such as rivets.

[0034] On the other hand, the electromagnet 52 includes a core 521 in which the main magnetic path of the magnetic flux generated when the electromagnet 52 is driven is formed, a coil bobbin 522 held by the core 521, and a coil 523 wound around the coil bobbin 522.

[0035] Core 521 can be formed using, for example, a soft magnetic material (soft magnetic body) that has a small magnetic force retention force and a large magnetic permeability. In this embodiment, core 521 is formed from an electromagnetic steel plate that allows many magnetic lines of force to pass through.

[0036] Coil bobbin 522 can be made of an electrically insulating material such as synthetic resin, and has coil 523 made of a conductive material wound around its outer surface. When coil 523 is wound around the outer surface of coil bobbin 522 and an AC current is supplied to coil 523, a magnetic flux (magnetic circuit) passing through core 521 is generated, and a magnetic pole surface in which the N pole and S pole alternate periodically is formed on the upper end surface of core 521.

[0037] As shown in Figures 3 to 5, the magnetic block 60 has a first movable body 61 and a second movable body 62, and each of the first movable body 61 and the second movable body 62 is fixed to a connecting plate 513 via a connecting spring 80.

[0038] Specifically, the connecting spring 80 includes a first spring 81, a second spring 82, and a third spring 83, and the first movable body 61 is fixed to the connecting plate 513 via the first spring 81. The second movable body 62 is fixed to the connecting plate 513 via the third spring 83. Furthermore, in this embodiment, the first movable body 61 and the second movable body 62 are connected by the second spring 82.

[0039] Thus, in this embodiment, the magnetic block 60 comprises a first movable body 61 connected to the electromagnetic block 50 via a first spring 81, and a second movable body 62 connected to the first movable body 61 via a second spring 82 and connected to the electromagnetic block 50 via a third spring 83.

[0040] Here, in this embodiment, the first movable body 61 has a generally rectangular plate shape elongated in the X direction (front-rear direction: first direction: axial direction of the output shaft), and includes an opposing wall 611 arranged above the electromagnet 52 so as to face the electromagnet 52 with a gap therebetween, and a pair of fixed walls 612 continuously provided so as to extend downward from both sides of the opposing wall 611 in the X direction (front-rear direction: first direction: axial direction of the output shaft) in a direction away from the electromagnet 52. A permanent magnet 614 is fixed to the lower surface of the opposing wall 611 via a back yoke 615. In this embodiment, the back yoke 615 and the permanent magnet 614 are fixed to the lower surface of the opposing wall 611 with fastening parts 617 such as rivets. The back yoke 615 and the permanent magnet 614 may also be bonded to the lower surface of the opposing wall 611. In this manner, the permanent magnet 614 as the permanent magnet 63 of the magnetic block 60 and the electromagnet 52 face each other vertically with a gap therebetween. The lower ends of the pair of fixed walls 612 are connected to the lower ends of the first springs 81, respectively.

[0041] Furthermore, in this embodiment, the first movable body 61 includes an extended wall 613 that is connected to the front end of the opposing wall 611 and protrudes further forward than the front connecting plate 513. The extended wall 613 has a shape in which the front end portion is bent downward, and an output shaft fixing portion 6131 is formed at the downwardly bent portion of the front end portion of the extended wall 613 so as to protrude forward. The output shaft 616 is fixed to the output shaft fixing portion 6131.

[0042] On the other hand, the second movable body 62 is provided with a one-side weight 621 arranged on one side of the first movable body 61 in the Y direction (width direction: third direction), an other-side weight 622 arranged on the other side of the first movable body 61 in the Y direction (width direction: third direction), and a connecting wall 623 connecting the one-side weight 621 and the other-side weight 622.

[0043] One-side weight 621 has a generally rectangular plate shape that is elongated in the X direction (front-rear direction: first direction: axial direction of the output shaft), and includes opposing wall 6211 that is disposed above electromagnet 52 so as to face electromagnet 52 with a gap therebetween and to face opposing wall 611 in the Y direction (width direction: third direction) with a gap therebetween. One-side weight 621 also includes a pair of fixed walls 6212 that are continuously provided from both sides of opposing wall 6211 in the X direction (front-rear direction: first direction: axial direction of the output shaft) so as to extend downward and in a direction away from electromagnet 52.

[0044] Similarly, the other-side weight 622 has a generally rectangular plate shape that is elongated in the X direction (front-rear direction: first direction: axial direction of the output shaft), and includes an opposing wall 6221 that is disposed above the electromagnet 52 and faces the electromagnet 52 with a gap therebetween, and that faces the opposing wall 611 in the Y direction (width direction: third direction) with a gap therebetween. Also, the other-side weight 622 includes a pair of fixed walls 6222 that are continuously provided from both sides of the opposing wall 6221 in the X direction (front-rear direction: first direction: axial direction of the output shaft) so as to extend downward and in a direction away from the electromagnet 52.

[0045] Fixed wall 6212 located on the front side of one side weight 621 and fixed wall 6222 located on the front side of the other side weight 622 are connected by connecting wall 623. Also, fixed wall 6212 located on the rear side of one side weight 621 and fixed wall 6222 located on the rear side of the other side weight 622 are connected by connecting wall 623.

[0046] Furthermore, the lower ends of the third springs 83 are respectively connected to the lower ends of the fixed walls 6212, and the lower ends of the third springs 83 are respectively connected to the lower ends of the fixed walls 6222. Also, the fixed wall 612 located on the front side of the first movable body 61 and the fixed wall 6212 located on the front side of the one-side weight 621 are fixed by the second springs 82, and the fixed wall 612 located on the rear side of the first movable body 61 and the fixed wall 6212 located on the rear side of the other-side weight 622 are fixed by the second springs 82.

[0047] In this 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 using the first lower spring fixing portion 72 with fastening parts 752 such as rivets.

[0048] Furthermore, by using the second lower spring fixing portion 73 to fix the lower end of the third spring 83 located on one side in the Y direction (width direction: third direction) to the lower end of the fixed wall 6212 of the one-side weight 621 with a fastening part 753 such as a rivet, 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 together with the lower end of the third spring 83 to the lower end of the fixed wall 6212 located in front of the one-side weight 621.

[0049] Then, using the third lower spring fixing portion 74, the lower end of the third spring 83 located on the other side in the Y direction (width direction: third direction) is fixed to the lower end of the fixed wall 6222 of the other-side weight 622 with a fastening part 754 such as a rivet, 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 together with the lower end of the third spring 83 to the lower end of the fixed wall 6222 located on the rear side of the other-side weight 622.

[0050] In this embodiment, leaf springs arranged so that their surfaces substantially coincide with the YZ plane are used as the first spring 81 and the third spring 83. Also, the second spring 82 is made by stacking multiple spring pieces having torsion portions in the X direction (front-rear direction: first direction: axial direction of the output shaft).

[0051] As described above, in this embodiment, the electromagnetic block 50 includes only one electromagnet 52. Furthermore, the magnetic block 60 includes two movable bodies (first movable body 61 and second movable body 62) that can reciprocate independently in the X direction (front-rear direction: first direction: axial direction of the output shaft).

[0052] By driving one electromagnet 52, the two movable bodies (first movable body 61 and second movable body 62) can be reciprocated in the X direction (front-back direction: first direction: axial direction of the output shaft) in opposite phases to each other. In this way, by using one electromagnet 52 to reciprocate the first movable body 61 and the second movable body 62, it is possible to reduce the size of the vibration type linear actuator 40 that can reciprocate the first movable body 61 and the second movable body 62.

[0053] In this embodiment, only one of the two movable bodies (first movable body 61 and second movable body 62) (first movable body 61) is formed with an output shaft 616 to which a handle portion (driven body) 30 is attached. The first movable body 61 on which the output shaft 616 is formed is positioned at the center in the Y direction (width direction: third direction).

[0054] This suppresses vibrations that occur when the two movable bodies (first movable body 61 and second movable body 62) reciprocate in the X direction (front-back direction: first direction: axial direction of the output shaft).

[0055] The vibrating linear actuator 40 configured in this manner is particularly suitable for use in a device that moves a single driven body (handle portion 30) back and forth in the axial direction, such as an electric toothbrush (oral hygiene device) 10.

[0056] When the electromagnet 52 is driven, a periodically fluctuating magnetic field is generated, which allows the first movable body 61, to which the handle portion (driven body) 30 is attached, and the second movable body 62, which is connected to the first movable body via the second spring 82, to move back and forth in the X direction (front-back direction: first direction: axial direction of the output shaft) in opposite phases to each other.

[0057] That is, a first movable block 110 having a handle portion (driven body) 30 attached to the output shaft 616 of the first movable body 61 and consisting of a member that reciprocates together with the first movable body 61, and a second movable block 120 consisting of a member that reciprocates together with the second movable body 62 are able to reciprocate in the X direction (front-to-back direction: first direction: axial direction of the output shaft) in opposite phases to each other.

[0058] At this time, it is preferable that the two movable bodies (first movable body 61 and second movable body 62) not only move harmonically in opposite phases to each other, but also move back and forth with more complex movements.

[0059] Therefore, in this embodiment, the first movable body 61 and the second movable body 62 are not only able to rotate harmonically in opposite phases to each other, but are also able to rotate harmonically in the same phase to each other.

[0060] Specifically, a permanent magnet 63 is provided on at least 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 by measuring the magnetic flux density of the permanent magnet 63 using, for example, a gaussmeter or the like.

[0061] By doing so, when the vibration type linear actuator 40 is driven, the thrust acting on the first movable body 61 and the thrust acting on the second movable body 62 are made different.

[0062] It is also possible to make the thrust acting on the first movable body 61 and the thrust acting on the second movable body 62 different from each other by the method described below.

[0063] For example, by providing the same permanent magnet 63 on the first movable body 61 and the second movable body 62, and making the shape of the stator (fixed part 51 of the electromagnetic block 50) different on the side facing the first movable body 61 and the side facing the second movable body 62, it is possible to make the thrust acting on the first movable body 61 and the thrust acting on the second movable body 62 different.

[0064] In addition, it is also possible to provide the same permanent magnet 63 on the first movable body 61 and the second movable body 62, while making the shape of the side of the stator (fixed part 51 of the electromagnetic block 50) facing the first movable body 61 the same as the shape of the side facing the second movable body 62, and then making the gap length between the first movable body 61 and the stator (fixed part 51 of the electromagnetic block 50) different from the gap length between the second movable body 62 and the stator (fixed part 51 of the electromagnetic block 50), thereby making the thrust acting on the first movable body 61 and the thrust acting on the second movable body 62 different.

[0065] In addition, by making the permanent magnet 63 provided on one of the first movable body 61 and the second movable body 62 protrude from the stator (fixed portion 51 of the electromagnetic block 50), it is possible to make the thrust acting on the first movable body 61 different from the thrust acting on the second movable body 62.

[0066] It is also possible to arrange a conductor between one of the first movable body 61 and the second movable body 62 and the stator (fixed part 51 of the electromagnetic block 50), or on the side of one of the movable bodies, and to make the thrust acting on the first movable body 61 and the thrust acting on the second movable body 62 different by braking due to eddy currents.

[0067] The thrust acting on each movable body can be obtained by measuring the thrust when a current is passed through the coil 523 using, for example, a load cell.

[0068] Here, in this embodiment, of the first movable body 61 and the second movable body 62, only the first movable body 61 is provided with a permanent magnet 614 as a permanent magnet 63, and the second movable body 62 is not provided with a permanent magnet 63. In this way, the magnetic force of the first movable body 61 and the magnetic force of the second movable body 62 are made different. In this way, in this 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 made zero (50% or less of the magnetic force of the first movable body 61, which is the larger magnetic force).

[0069] Therefore, the vibration type linear actuator 40 according to this embodiment has a first movable body 61 and a second movable body 62 that are approximated by the vibration model shown in FIG.

[0070] That is, the vibration type linear actuator 40 of this embodiment has a structure in which a first movable body 61 has a permanent magnet 63 and is fixed to the stator (fixed part 51 of the electromagnetic block 50) by a first spring 81, and a second movable body 62 does not have a permanent magnet 63 and is fixed to the stator (fixed part 51 of the electromagnetic block 50) by a third spring 83, and these are connected by a second spring 82.

[0071] Then, the first movable body 61 and the second movable body 62 approximated by the vibration model shown in FIG. 9 are The electromagnet 52 is driven to vibrate.

[0072] Incidentally, it is known that 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 shown in Fig. 9, the two movable bodies (first movable body 61 and second movable body 62) have the frequency characteristics shown in Fig. 10. That is, it is known that there are frequencies where the amplitude increases in the same phase (resonates in the same phase) and frequencies where the amplitude increases in the opposite phase (resonates in the opposite phase). Note that as the difference between the magnetic force of the first movable body 61 and the magnetic force of the second movable body 62 increases, the amplitude at the frequency where the amplitude increases in the same phase also increases.

[0073] Therefore, in this embodiment, the first movable body 61 and the second movable body 62 are vibrated using two resonant frequencies (a frequency at which the amplitude increases in the same phase and a frequency at which the amplitude increases in the opposite phase).

[0074] Specifically, when driving the electromagnet 52, a voltage V having a waveform in which two different waveforms are superimposed is applied to the electromagnet 52. In this embodiment, a voltage V having a waveform as shown in FIG. 11 is applied to the electromagnet 52.

[0075] The voltage V shown in FIG. 11 is V=sin(ω1t)+sin(ω2t). Therefore, in this embodiment, when driving the electromagnet 52, a voltage V of a composite wave (a wave obtained by combining two sine waves with different frequencies) is applied to the electromagnet 52. Here, ω1 is a frequency at which the amplitude increases in the same phase. Based on the frequency characteristics shown in FIG. 10, this ω1 is preferably set in the range of 20 Hz to 60 Hz. This allows the amplitude in the same phase to be 1.0 mm or more. Setting ω1 to 48 Hz allows the amplitude in the same phase to be the maximum. Furthermore, ω2 is a frequency at which the amplitude increases in the opposite phase. Based on the frequency characteristics shown in FIG. 10, this ω2 is preferably set in the range of 250 Hz to 280 Hz. This allows the amplitude in the opposite phase to be 0.2 mm or more. Setting ω2 to 270 Hz allows the amplitude in the opposite phase to be the maximum.

[0076] In this way, by vibrating the first movable body 61 and the second movable body 62, which are approximated by the vibration model shown in Figure 9, using the electromagnet 52 to which the voltage V shown in Figure 11 is applied, the first movable body 61 and the second movable body 62 reciprocate at a frequency that increases the amplitude in opposite phase, and at a frequency that increases the amplitude in the same phase.

[0077] Specifically, the first movable body 61 and the second movable body 62 perform short-wavelength fine reciprocating motions in opposite phases, while performing in-phase reciprocating motions with a relatively large wavelength longer than the fine reciprocating motions. That is, the first movable body 61 and the second movable body 62 not only perform simple harmonic motions in opposite phases, but also perform simple harmonic motions in the same phase with a wavelength longer than the simple harmonic motion in the opposite phase, resulting in more complex reciprocating motions.

[0078] Furthermore, in this embodiment, the weights of the first movable body 61 and the second movable body 62 are set so that the weight m1 of the first movable block 110, which has the first movable body 61 and the handle portion (driven body) 30 connected to the first movable body 61 and reciprocates together with the first movable body 61, is approximately the same as the weight m2 of the second movable block 120, which reciprocates together with the second movable body 62. Here, the first movable block 110 means a single member that reciprocates together with the first movable body 61, and in this embodiment, at least the first movable body 61 and the handle portion (driven body) 30 connected to the first movable body are included in this first movable block 110. Furthermore, the second movable block 120 means a single member that reciprocates together with the second movable body 62, and at least the second movable body 62 is included in this second movable block 120.

[0079] As described above, in this embodiment, the weights of the first movable body 61 and the second movable body 62 are set so that the weight m1 of the first movable block 110, which includes at least the first movable body 61 and the handle portion (driven body) 30 and reciprocates together with the first movable body 61, is approximately the same as the weight m2 of the second movable block 120, which includes at least the second movable body 62 and reciprocates together with the second movable body 62. In other words, when made into an electric toothbrush (oral hygiene device) 10, the single member that reciprocates together with the first movable body 61 and the single member that reciprocates together with the second movable body 62 are set to have the same weight. Therefore, in this embodiment, the weight of the first movable body 61 is lighter than the weight of the second movable body 62.

[0080] In this way, one method of making the weight of the first movable body 61 lighter than the weight of the second movable body 62 is to form at least a portion of the second movable body 62 using brass, which has a relatively high specific gravity, while forming at least a portion of the first movable body 61 using resin, which has a relatively low specific gravity.

[0081] Furthermore, by making the weight m1 of the first movable block 110 and the weight m2 of the second movable block 120 approximately the same, it is possible to more reliably suppress vibrations that occur when the handle portion (driven body) 30 is driven (reciprocated).

[0082] When the vibration type linear actuator structure 100 according to this embodiment is used and the above-mentioned voltage V is applied to the electromagnet 52, the operation of the first movable block 110 and the second movable block 120 can be approximated by a forced vibration model in which an external force F is present in a mass-spring-damper system as shown in FIG. 12.

[0083] 12, the vibration model of the mass-spring-damper system has a structure in which a first movable block 110 is fixed to the stator (fixed portion 51 of the electromagnetic block 50) by a first spring 81 with a spring constant k1 and a first damper 91 with a damping coefficient c1, and a second movable block 120 is fixed to the stator (fixed portion 51 of the electromagnetic block 50) by a third spring 83 with a spring constant k3 and a third damper 93 with a damping coefficient c3, and these are connected by 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 block 110 to vibrate it, thereby vibrating the first movable block 110 and the second movable block 120. The external force F applied to the first movable block 110 is a force that is a constant multiple of sin(ω1t) + sin(ω2t).

[0084] When the vibration type linear actuator structure 100 according to this embodiment is used and the above-mentioned voltage V is applied to the electromagnet 52, the operation of the first movable block 110 and the second movable block 120 is substantially the same as the operation of the first movable block 110 and the second movable block 120 in the forced vibration model in which an external force F is present in the mass-spring-damper system shown in FIG. 12.

[0085] Specifically, the first movable block 110 and the second movable block 120 operate as shown in the waveform of Fig. 13. That is, they reciprocate at a frequency that increases amplitude in opposite phase, while also reciprocating at a frequency that increases amplitude in the same phase. In other words, the first movable block 110 and the second movable block 120 perform short-wavelength fine reciprocating movements in opposite phase, while also performing relatively large reciprocating movements in the same phase with a longer wavelength than the fine reciprocating movements.

[0086] Therefore, in an electric toothbrush (oral hygiene device) 10 using the vibration linear actuator 40 according to this embodiment, the handle portion (driven body) 30, i.e., the brush portion 32 having multiple bristles (brush bundles) 321 formed therein, performs short-wavelength fine reciprocating motions while also performing relatively large reciprocating motions with longer wavelengths than the fine reciprocating motions. In this embodiment, the amplitudes of the short-wavelength fine reciprocating motions, which are opposite in phase to each other, are set to 0.2 mm to 1.5 mm, while the amplitudes of the long-wavelength relatively large reciprocating motions, which are in phase to each other, are set to 1.0 mm to 2.0 mm. In other words, the brush portion 32 having multiple bristles (brush bundles) 321 formed therein, reciprocates with an overall amplitude of 1.2 mm to 3.5 mm.

[0087] If the brush part 32, which reciprocates in such a complex motion, is placed in the oral cavity and used to brush teeth, food debris, plaque, etc. can be removed more efficiently while reducing irritation to the oral cavity caused by the vibration of the brush part 32.

[0088] The vibration type linear actuator 40 can also be configured as shown in FIG.

[0089] In the vibration type linear actuator 40 shown in Figure 14, a permanent magnet 63 is provided in at least one of the first movable body 61 and the second movable body 62 so that the magnetic force of the first movable body 61 and the magnetic force of the second movable body 62 are different.

[0090] In the vibration type linear actuator 40 shown in Figure 14, permanent magnets 63 are provided on both the first movable body 61 and the second movable body 62, while the magnetic force of the first movable body 61 and the magnetic force of the second movable body 62 are made different.

[0091] 14, a permanent magnet 6213 is fixed to the lower surface of an opposing wall 6211 of one-side weight 621 via a back yoke 6214. Also, a permanent magnet 6223 is fixed to the lower surface of an opposing wall 6221 of the other-side weight 622 via a back yoke 6224.

[0092] The magnetic force of the first movable body 61 is different from the magnetic force of the second movable body 62. In Fig. 14, 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 set to 50% or less of the magnetic force of the first movable body 61, which is the larger magnetic force.

[0093] Therefore, the vibration type linear actuator 40 shown in FIG. 14 has a first movable body 61 and a second movable body 62 that are approximated by the vibration model shown in FIG.

[0094] That is, the vibration type linear actuator 40 shown in Figure 14 has a structure in which a first movable body 61 has a permanent magnet 63 with a large magnetic force and is fixed to the stator (fixed part 51 of the electromagnetic block 50) by a first spring 81, and a second movable body 62 has a permanent magnet 63 with a small magnetic force and is fixed to the stator (fixed part 51 of the electromagnetic block 50) by a third spring 83, and these are connected by a second spring 82.

[0095] Even with this configuration, it is possible to achieve substantially the same functions and effects as the vibration type linear actuator 40 shown in the above embodiment.

[0096] (Addendum) The above description of the embodiments discloses the following techniques.

[0097] (Technology 1) A vibration-type linear actuator comprising: an electromagnetic block having an electromagnet; and a magnetic block having a permanent magnet arranged to face the electromagnet across a gap, the magnetic block reciprocating in a first direction relative to the electromagnetic block by a periodically varying magnetic field; the magnetic block comprising 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; and configured such that when a voltage having a waveform in which two different waveforms are superimposed is applied to the electromagnet, with the thrust acting on the first movable body and the thrust acting on the second movable body being different, the first movable body and the second movable body reciprocate at a frequency in which the amplitude increases in opposite phase, and at the same time reciprocate at a frequency in which the amplitude increases in the same phase.

[0098] In this way, the vibration type linear actuator of Technology 1 is a device that generates a periodically varying magnetic field to reciprocate the first movable body and the second movable body relative to the electromagnetic block in the first direction.

[0099] Then, a voltage having a waveform in which two different waveforms are superimposed is applied to the electromagnet while the thrust acting on the first movable body and the thrust acting on the second movable body are made different. This allows the first movable body and the second movable body to reciprocate with a combined motion that combines motion at a frequency in which the amplitude increases in the opposite phase with motion at a frequency in which the amplitude increases in the same phase. This allows the first movable body and the second movable body to perform fine reciprocating motions with short wavelengths in the opposite phase, while also performing relatively large reciprocating motions in the same phase with wavelengths longer than the fine reciprocating motions. In other words, not only can the first movable body and the second movable body be made to perform simple harmonic motion in the opposite phase, but they can also be made to perform simple harmonic motion in the same phase with a wavelength longer than the simple harmonic motion in the opposite phase.

[0100] In this way, the vibration type linear actuator of Technique 1 can reciprocate the first movable body and the second movable body with more complex movements.

[0101] (Technology 2) A vibration type linear actuator according to Technology 1, in which the permanent magnet is provided in at least one of the first movable body and the second movable body, and the magnetic force of the first movable body is made different from the magnetic force of the second movable body, so that the thrust acting on the first movable body and the thrust acting on the second movable body are made different.

[0102] This makes it possible to make the thrust acting on the first movable body and the thrust acting on the second movable body different while keeping the shapes of the first movable body and the second movable body simple in configuration.

[0103] (Technology 3) The vibration type linear actuator according to Technology 2, wherein the permanent magnet is provided on only one of the first movable body and the second movable body.

[0104] This makes it possible to more easily and reliably set the smaller of the magnetic forces of the first and second movable bodies to zero.

[0105] (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.

[0106] This allows the weight of the first movable body side and the weight of the second movable body side to be approximately the same when the driven body is connected to the first movable body or the second movable body. By making the weight of the first movable body side and the weight of the second movable body side to be approximately the same when the driven body is connected in this way, it becomes possible to more reliably suppress vibrations that occur when the driven body is driven (reciprocated).

[0107] (Technology 5) The vibration type linear actuator according to any one of Technologies 1 to 4, wherein the electromagnetic block has only one electromagnet.

[0108] In this way, the first movable body and the second movable body are moved back and forth using a single electromagnet, which makes it possible to miniaturize the vibration-type linear actuator, which can move the first movable body and the second movable body back and forth with more complex movements.

[0109] (Technology 6) The vibration type linear actuator according to any one of Technologies 1 to 5, wherein the second movable body is connected to the electromagnetic block via a third spring.

[0110] This makes it possible to more stably hold the first movable body and the second movable body in the electromagnetic block, thereby more reliably preventing the first movable body and the second movable body from shaking in a direction intersecting the first direction when the first movable body and the second movable body are moved back and forth in the first direction.

[0111] (Technology 7) An electric toothbrush comprising: a vibration type linear actuator according to any one of technologies 1 to 6; and a handle portion having a brush portion and connected to the first movable body or the second movable body.

[0112] This allows for an electric toothbrush that can move the brush part of the handle back and forth in a more complex motion, and by using such an electric toothbrush, it is possible to more efficiently remove food debris, plaque, etc. while reducing irritation to the oral cavity caused by the vibration of the brush part.

[0113] (Technology 8) An electric toothbrush described in Technology 7, wherein, when the handle portion is connected to the first movable body, the weights of the first movable body and the second movable body are set so that the weight of a first movable block that includes at least the first movable body and the handle portion and reciprocates together with the first movable body is approximately the same as the weight of a second movable block that includes at least the second movable body and reciprocates together with the second movable body, and when the handle portion 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 that includes at least the first movable body and reciprocates together with the first movable body is approximately the same as the weight of the second movable block that includes at least the second movable body and the handle portion and reciprocates together with the second movable body.

[0114] This makes it possible to more reliably suppress vibrations that occur when the handle of an electric toothbrush formed using a vibration-type linear actuator is driven (reciprocated).

[0115] [others] The details of the vibratory linear actuator and electric toothbrush according to the present disclosure have been described above, but it will be obvious to those skilled in the art that they are not limited to these descriptions and that various modifications and improvements are possible.

[0116] For example, in the above embodiment and its modified examples, a vibrating linear actuator used in an electric toothbrush (oral hygiene device) as a personal care product has been exemplified, but the vibrating linear actuator can also be used in products other than an electric toothbrush (oral hygiene device), such as a shaver (electric razor), clippers (hair cutting devices), and other personal care products.

[0117] The present disclosure can also be applied to embodiments in which the configurations shown in the above-described embodiments and their modifications have been changed, replaced, added, omitted, etc. Furthermore, it is also possible to combine the components described in the above-described embodiments and their modifications to create new embodiments.

[0118] Furthermore, in the above embodiment and its modified examples, the weight m1 of the first movable block 110 and the weight m2 of the second movable block 120 are illustrated as being approximately the same, but it is also possible to make the weight m1 of the first movable block 110 and the weight m2 of the second movable block 120 different.

[0119] It is also possible to make the weight of the first movable body 61 and the weight of the second movable body 62 approximately the same.

[0120] Furthermore, in the above embodiment and its modified examples, the vibration type linear actuator 40 is exemplified as being equipped with the third spring 83, but it is also possible to configure the vibration type linear actuator 40 as not being equipped with the third spring 83. For example, it is also possible to configure the second movable body 62 as being connected to the first movable body 61 via the second spring 82 but not connected to the electromagnetic block 50, i.e., as being connected only to the first movable body 61 out of the electromagnetic block 50 and the first movable body 61.

[0121] Furthermore, although the vibration type linear actuator 40 in which the handle portion (driven body) 30 is connected to the first movable body 61 has been exemplified, it is also possible to use a vibration type linear actuator in which the handle portion (driven body) 30 is connected to the second movable body 62. In this case, it is preferable to set the weights of the first movable body 61 and the second movable body 62 so that the weight of the first movable block 110, which includes at least the first movable body 61 and reciprocates together with the first movable body 61, is approximately the same as the weight of the second movable block 120, which includes at least the second movable body 62 and the handle portion (driven body) 30 and reciprocates together with the second movable body 62.

[0122] Furthermore, in the above embodiment and its modified examples, a voltage V of a composite wave obtained by combining waveforms of two different frequencies (a wave obtained by combining two sine waves with different frequencies) is applied to the electromagnet 52, but the waveform of the voltage V applied to the electromagnet 52 may be any of various waveforms as long as it is a waveform obtained by superimposing two different waveforms. For example, it is possible to apply to the electromagnet 52 a voltage V having a waveform obtained by superimposing two different waveforms selected from sine waves, rectangular waves, triangular waves, sawtooth waves, trapezoidal waves, etc.

[0123] In this disclosure, even if two waves have the same shape, if at least one of the frequencies, amplitudes, and phases is different, they are defined as different waves. Therefore, in the above embodiment and its modified examples, the two waves shown as waves to be synthesized are both sine waves but have different frequencies, and therefore are different waves in the above embodiment and its modified examples.

[0124] In addition, the specifications of the electromagnetic block, magnetic block, and other details (shape, size, layout, etc.) can also be changed as appropriate. [Industrial Applicability]

[0125] As described above, the vibratory linear actuator and electric toothbrush according to the present disclosure are capable of reciprocating the first movable body and the second movable body with more complex movements, and can therefore be used as part of personal care products such as electric toothbrushes. [Explanation of symbols]

[0126] 10. Electric toothbrush 30 Handle (driven body) 32 Brush section 40 Vibration type linear actuator 50 Electromagnetic Block 52 Electromagnet 60 Magnetic Blocks 61 1st movable body 62 Second movable body 63 Permanent Magnets 81 First Spring 82 Second spring 83 Third Spring 110 First Movable Block 120 Second Movable Block

Claims

1. an electromagnetic block having an electromagnet; a magnetic block having a permanent magnet arranged to face the electromagnet across a gap, the magnetic block reciprocating in a first direction relative to the electromagnetic block by a periodically varying magnetic field; Equipped with The magnetic block is a first movable body connected to the electromagnetic block via a first spring; a second movable body connected to the first movable body via a second spring; Equipped with When a voltage having a waveform in which two different waveforms are superimposed is applied to the electromagnet in a state in which a thrust acting on the first movable body and a thrust acting on the second movable body are different from each other, the first movable body and the second movable body are configured to reciprocate at a frequency in which the amplitude increases in opposite phases, and at the same time, to reciprocate at a frequency in which the amplitude increases in the same phase. Vibration type linear actuator.

2. the permanent magnet is provided on at least one of the first movable body and the second movable body, The magnetic force of the first movable body and the magnetic force of the second movable body are made different from each other, so that the thrust acting on the first movable body and the thrust acting on the second movable body are made different from each other.

2. The vibratory linear actuator according to claim 1.

3. the permanent magnet is provided on only one of the first movable body and the second movable body; 3. The vibratory linear actuator according to claim 2.

4. The weight of the first movable body is different from the weight of the second movable body. The vibration type linear actuator according to any one of claims 1 to 3.

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

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

7. A vibration type linear actuator according to any one of claims 1 to 3; a handle portion having a brush portion and connected to the first movable body or the second movable body; Equipped with Electric toothbrush.

8. when the handle portion is connected to the first movable body, 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 the handle portion 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; When the handle portion 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 a first movable block that includes at least the first movable body and reciprocates together with the first movable body is substantially the same as the weight of a second movable block that includes at least the second movable body and the handle portion and reciprocates together with the second movable body. The electric toothbrush according to claim 7.

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