Motion converter and drive unit comprising motion converter

Abstract

The invention relates to a motion converter (5A, 5B, 5C, 5D, 8C) which is designed to convert a rotational motion provided by a motor shaft (31A, 31B, 31, 3) into a linear reciprocating motion of a drive shaft (70A, 70B, 70D). The motion converter (5A, 5B, 5C, 5D, 8C) has: a deformable unit (50A, 50B, 50C, 50D, 8C); a mounting unit (60A, 60B, 60D), which is connected to the deformable unit (50A, 50B, 50C, 50D, 8C); a coupling unit (59A, 59B, 59C, 59D, 8A) connected to the deformable unit (50A, 50B, 50C, 50D, 8C), the coupling unit (59A, 59B, 59C, 59D, 8A) being configured to receive the drive shaft (70A, 70B, 70D) or the coupling unit (59A, 59B, 59C, 59D, 8A) comprising the drive shaft (70A, 70B, 70D); a connector unit (8A, 8B, 8C, 8D) connected to the deformable unit (50A, 50B, 50C, 50D, 8C), the connector unit (8A, 8B, 8C, 8D) comprising at least a first substantially U-shaped receptacle (90E) configured for receiving a first eccentric shaft element (41A, 41B, 41D) of the motor shaft (31 A, 31B, 31, 3) and having a U-shaped base and two U-shaped legs, and a first support element (903E) configured for supporting the first eccentric shaft element (41A, 41B, 41D) of the motor shaft (31 A, 31B, 31, 3); the U-shaped base and the two U-shaped legs together define a first elongated aperture (804B, 805B, 814B, 902E) having a length (1), a width and a height, the first support element connecting the two U-shaped legs on free ends of the two U-shaped legs of the first substantially U-shaped receiving portion (90E) such that access to the first elongated aperture (804B, 805B, 814B, 902E) across the width and the height of the first elongated aperture (804B, 805B, 814B, 902E) is provided, preferably wherein the first support element (903E) is strip-shaped or U-shaped or O-shaped, and wherein the length (1) is measured from an inner surface of the U-shaped base to the free end of the U-shaped leg.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a motion converter and to a drive unit comprising a motion converter. The motion converter is intended for receiving a rotational motion of a motor shaft and for providing a linear, reciprocating motion at a drive shaft, and the drive unit comprising a motor and a drive shaft can be arranged in a handle section of a personal care device and can be used for driving a head of the personal care device. BACKGROUND

[0002] It is generally known that a rotational motion, which can be provided by a shaft of a DC motor, is converted into an oscillating motion by a suitable gear mechanism, for example by a four-bar linkage as described in DE 39 37 854 A1. DE 34 30 562 C1 describes a device for converting a rotational motion of an eccentric, which is driven by a motor shaft, into a reciprocating motion of a working tool of an electrically driven small electric appliance. The described conversion mechanism comprises a connecting rod, which is connected with the eccentric and with a first lever arm of a double-arm rocker. The connecting rod comprises a film hinge, the central axis of which intersects the longitudinal axis of the first lever arm. The first lever arm is designed to be elastically torsionable about its longitudinal axis. The double-arm rocker is pivotably mounted at a housing of the electric appliance and further comprises a shaft pin, which is coupled with the working tool. In operation, the shaft pin is moved in an oscillating wiping motion relative to the pivotable mounting of the double-arm rocker.

[0003] A drive unit for converting a rotational motion of a motor shaft into a reciprocating linear motion of a drive shaft of the drive unit can comprise a motion converter. Drive units with motion converters are described in the co-pending applications EP 21158962.7 and EP 22156286.1.

[0004] It is an object of the present disclosure to provide a motion converter and a drive unit with a motion converter, in particular an injection-molded motion converter, wherein the motion converter has a structure which allows for a simple manufacture. It is a further object of the present disclosure to provide a method for manufacturing a motion converter for a drive unit by injection molding. SUMMARY

[0005] According to at least one aspect, there is provided a motion converter configured for converting rotational motion provided by a motor shaft into linear reciprocating motion of a drive shaft, the motion converter comprising a variable profile unit; a mounting unit connected with the variable profile unit; a coupling unit connected with the variable profile unit, the coupling unit being configured to receive the drive shaft or the coupling unit comprising the drive shaft; a connector unit connected with the variable profile unit, the connector unit comprising at least a first substantially U-shaped receiving portion configured for receiving a first eccentric shaft element of the motor shaft and having a U-shaped base and two U-shaped legs together defining a first elongated hole having a length, a width and a height, and a first support element connecting the two U-shaped legs on free ends of the two U-shaped legs of the first substantially U-shaped receiving portion such that a passage into the first elongated hole is provided across the width and the height of the first elongated hole, preferably wherein the first support element is bar-shaped or U-shaped or O-shaped, and wherein the length is measured from an inner surface of the U-shaped base to the free ends of the U-shaped legs.

[0006] According to at least one aspect, there is provided a drive unit comprising the proposed motion converter, the drive unit comprising: a drive shaft connected with the coupling unit for providing linear reciprocating motion in operation; a motor having a motor shaft providing rotational motion about a longitudinal center axis of the motor shaft in operation; a motor shaft extension coupled to or connected with the motor shaft, the motor shaft extension comprising at least a first eccentric shaft element arranged eccentrically with respect to the longitudinal center axis such that the first eccentric shaft element moves in a circular path about the longitudinal center axis in operation, wherein the first eccentric shaft element extends through the first elongated hole in the height direction of the first elongated hole, the first eccentric shaft element having a diameter that fits tightly into the first elongated hole in the width direction of the first elongated hole, and the first eccentric shaft element is freely movable in the first elongated hole in the length direction of the first elongated hole in operation.

[0007] According to at least one aspect, there is provided a personal care device comprising a drive unit as proposed, the drive unit comprising a head section coupled with a drive shaft such that the head section or a driven element of the head section is in operation driven in a back-and-forth motion, such as an oscillating motion or a reciprocating motion, optionally wherein the mounting unit of the motion translator is firmly mounted relative to the motor, and further optionally wherein in operation the circular motion of at least the first eccentric shaft element causes at least the first substantially U-shaped receiver to transfer a periodic force onto the variable form unit such that the variable form unit is periodically deformed, preferably wherein the periodic deformation refers to a periodic deformation in the z-direction and a 180-degree phase-shift periodic deformation in the y-direction perpendicular to the z-direction. BRIEF DESCRIPTION OF DRAWINGS

[0008] The present disclosure will be further clarified by a detailed description of example implementations, with reference to the accompanying drawings. In the drawings, Figure 1 is a depiction of a personal care device implemented as an electric toothbrush comprising a handle section and a head section, and the head section comprises a driven element implemented as a personal care head; Figure 2 is a depiction of a cut-away top portion of a handle section of a personal care device comprising an example drive unit according to the present disclosure; Figure 3 is a depiction of an example drive unit according to the present disclosure, wherein the variable form unit can at least partially be made of a bent sheet metal; Figure 4A is a perspective view of an example motion translator implemented according to the present proposal; Figure 4B is Figure 4A a side view of the motion translator shown; Figure 5 is Figure 4A and Figure 4B is a close-up of a central portion of the motion translator of Figure 6A is a side view of an example drive unit according to the present disclosure, the drive unit comprising the proposed motion translator; Figure 6B is Figure 6A a cross-sectional depiction of the drive unit shown; Figure 6C is Figure 6B a close-up of portion A of the cross-sectional view of Figure 7 is a detailed depiction of an example receiver of a connecting unit according to the present disclosure. DETAILED DESCRIPTION

[0009] In the context of this specification, “personal care” means the maintenance (or care) of the skin and its appendages (i.e., hair and fingernails / toenails) and the teeth and mouth (including the tongue, gums, etc.), the purpose of which is, on the one hand, to prevent disease and maintain and enhance health, and on the other hand, to provide cosmetic care and improve the appearance of the skin and its appendages. It should include maintaining and enhancing well-being. This includes skin care, hair care, oral care, and nail care. It also includes grooming activities such as beard care, shaving, and hair removal. Therefore, “personal care device” means any device used to perform such nutritional or grooming activities, such as (cosmetic) skin treatment devices such as skin massagers or skin brushes; wet razors; electric razors or trimmers; electric epilators; and oral care devices such as manual or electric toothbrushes, (electric) dental floss, (electric) rinsing devices, (electric) tongue cleaners, or (electric) gum massagers. Terms in parentheses imply that these are optional features. This should not preclude the proposed personal care device from having a more significant beneficial effect in one or more of these nutritional or device areas than in one or more other areas. In this instruction manual, the electric toothbrush is chosen to represent personal care devices. While these details are not specific to electric toothbrushes, the proposed technologies and concepts can be used in any other personal care device.

[0010] This disclosure relates to motion converters, drive units having such motion converters, and personal care devices including such drive units.

[0011] The motion transducer is configured to convert rotational motion provided by a motor shaft of a drive or motor (such as a DC motor) into linear reciprocating motion, preferably wherein the direction of said linear reciprocating motion coincides with or is parallel to the longitudinal central axis of the motor shaft. The motion transducer is configured to receive a first eccentric shaft element of a motor shaft extension connected to at least the motor shaft and to receive a drive shaft. The motor shaft extension may be a separate component detachably attached to the motor shaft, or the motor shaft extension may be integral with the motor shaft. The motion transducer has a mounting unit for securely mounting the motion transducer at or relative to the motor in a personal care device, a coupling unit for receiving the drive shaft, a connector unit configured to receive at least the first eccentric shaft element, and a deformable unit connected to the connector unit, mounting unit, and coupling unit. The connector unit includes a first substantially U-shaped receiving portion having a U-shaped base and two U-shaped legs, the U-shaped base and the two U-shaped legs together defining a first elongated aperture open at one end (the end opposite the U-shaped base). The first elongated hole has a length measured from the inner surface of the U-shaped base toward the free end of the U-shaped leg, a width between the U-shaped legs, and a height, wherein the height may be non-constant over the length of the elongated hole – see further below regarding Figure 7The width should be constant at least along the length of the first elongated U-shaped aperture, in which the eccentric shaft element moves during operation. A first support element is provided, connecting the free end of the U-shaped leg, allowing access to the first elongated aperture across its entire width and height in the longitudinal direction. The first support element can be substantially strip-shaped, U-shaped, or O-shaped, but other shapes are also possible, as is its function—connecting the free end of the U-shaped leg of the receiving portion while allowing full access to the elongated aperture in the longitudinal direction. The width of the first elongated aperture can be set such that the aforementioned first eccentric shaft element fits tightly into the first elongated aperture in the width direction. The first eccentric shaft element can extend through the first elongated aperture in the height direction and can have a cylindrical shape having a diameter substantially coinciding with the width of the first elongated aperture. The connector unit may include a second substantially U-shaped receiving portion, and potentially a third substantially U-shaped receiving portion for receiving the second and third eccentric shaft elements, respectively. The previous discussion of the first receiving portion, the first elongated aperture, the first support element, and the first eccentric shaft element also applies to all such elements with different designations (such as second or third). Two, three, or more receiving portions may have a rest position in which the corresponding elongated apertures are aligned with each other at least in the width direction. The length directions of the elongated apertures are parallel to each other. Each receiving portion may be connected to an arm element; for example, a first arm element may be connected to a first substantially U-shaped receiving portion, which is then connected to a deformable unit, such that motion transmitted from the eccentric shaft element to the receiving portion is transmitted by the arm element to the deformable unit. In some examples, the arm elements of two or more aligned receiving portions may engage to transmit motion of the two or more aligned receiving portions to the deformable unit via a single engaging arm element. The structure of the two engaging arm elements may be substantially similar to a tuning fork.

[0012] The deformable unit can be configured to deform in such a way that, when the drive shaft is connected to the coupling unit, the periodic force provided to the deformable unit by the arm element causes a linear reciprocating motion of the coupling unit, and thus a linear reciprocating motion of the drive shaft. To achieve this, the deformable unit can have a generally convex quadrilateral type structure, such as a rhombus structure with four sides and four vertices, wherein the mounting unit and the coupling unit can be positioned at two opposite vertices of the convex quadrilateral type structure. The coupling unit can be connected to at least one of the two other vertices via one or more of the arm elements mentioned, preferably to two of the two other substantially opposite vertices.

[0013] The aforementioned U-shaped receiving portion and preferably complete motion converter can be manufactured by injection molding, wherein it is sufficient to provide two half-molds that move together in the longitudinal direction of the receiving portion, because due to the position of the support element, no additional core is required to define the U-shaped elongated hole of the receiving portion.

[0014] The term "U-shape" should be understood as referring to the internal shape of the receiving portion that defines the elongated orifice. The receiving portion may have an external shape other than a U-shape.

[0015] The receiving portion can also be described with reference to a Cartesian coordinate system having x, y, and z axes, wherein the length direction is parallel to the x-axis, the width direction is parallel to the y-axis, and the height direction is parallel to the z-axis. The terms axis and direction are used synonymously in this disclosure. The support element can then extend in a plane parallel to the yz plane, although it should not be excluded that the support element may be curved, particularly having curvature in the length direction. Regarding the direction defined by such a Cartesian coordinate system, the first eccentric shaft element and / or the other eccentric shaft element rotate about the longitudinal central axis of the motor shaft, i.e., along a circular path about the longitudinal central axis parallel to the z-axis. This means that the movement of the first eccentric shaft element and the other eccentric shaft element, i.e., circular movement, essentially occurs in the xy plane. The elongated aperture of the receiving portion is constructed as described above, and thus the receiving portion moves by the movement of the corresponding eccentric shaft element in the x-direction, while movement in the y-direction occurs freely within the elongated aperture and does not cause movement of the receiving portion. The arm element of the receiving part typically extends in the y-direction. Those skilled in the art will understand that each element described herein has a natural 3D shape and will extend in all directions; however, the relevant direction of extension here refers to the direction along which the arm element extends to connect the receiving part to the deformable unit. The periodic movement of the arm element in the y-direction causes deflection of the deformable unit in the y-direction. Due to the structure of the deformable unit, the periodic movement of the arm element also causes periodic deformation in the z-direction, which results in periodic movement of the connecting unit in the z-direction, i.e., linear reciprocating motion of the connecting unit in the z-direction.

[0016] The drive unit disclosed herein can utilize a standard motor such as a DC motor, which is available as an off-the-shelf component and therefore has a typical low-cost configuration. To achieve the described conversion, the motor shaft includes a motor shaft extension comprising at least a first eccentric shaft element arranged eccentrically relative to the longitudinal central axis of the motor shaft, such that in operation, the first eccentric shaft element moves along a circular path about the longitudinal central axis of the motor shaft, the circle extending in a plane perpendicular to the longitudinal central axis. The motor shaft extension may be integral with the motor shaft or may be a separate component detachably or non-detachably connected to the motor shaft. The motor shaft extension may include two, three, or more eccentric shaft elements arranged front-to-back relative to each other with respect to a direction defined by the longitudinal central axis, i.e., front-to-back in the z-direction. When the first eccentric shaft element is intended to extend through a first elongated hole in a first substantially U-shaped receiving portion, a second eccentric shaft element is intended to extend through a second elongated hole in a second substantially U-shaped receiving portion, and so on. In the drive unit, a first eccentric shaft element extends through a first elongated hole in a height direction (i.e., in the z-direction) that coincides with the direction defined by the longitudinal central axis, and optionally a second eccentric shaft element extends through a second elongated hole in the same manner, and further optionally a third eccentric shaft element extends through a third elongated hole.

[0017] The first and second eccentric shaft elements can be configured such that they rotate about the longitudinal central axis at a 180-degree angle offset during operation. The third eccentric shaft element can then be arranged to be kinetically aligned with the first eccentric shaft element. The first arm connecting the first substantially U-shaped receiving portion to the deformable unit and the third arm connecting the third substantially U-shaped receiving portion to the deformable unit can be engaged before the point where the engaging arm is connected to the deformable unit.

[0018] This disclosure also relates to a personal care device including a drive unit as previously discussed. The personal care device may include a head section coupled to a drive shaft such that the head section or a driven element of the head section is driven in operation to reciprocate, such as oscillating or reciprocating motion. Optionally, the mounting unit of the motion converter is securely mounted relative to the motor, and further optionally, in operation, at least the circular motion of the first eccentric shaft element causes at least the first substantially U-shaped receiving portion to transmit periodic forces to the deformable unit, causing the deformable unit to deform periodically. Preferably, the periodic deformation refers to periodic deformation in the z-direction and a 180-degree phase-shifted periodic deformation in the y-direction perpendicular to the z-direction. This means that, where deformation in the z-direction causes the deformable unit to extend in the z-direction, deformation of the deformable unit causes contraction of the deformable unit in the y-direction.

[0019] Figure 1 This is a description of an example personal care device 1 implemented as an electric toothbrush. The personal care device 1 includes a head section 10 and a handle section 20. The head section 10 may include a driven element 11 (implemented herein as a brush head), or alternatively, the head section may implement a driven element such that the entire head section is then driven to move, not just the driven element of the head section. When the head section 10 includes the driven element 11, the head section 10 may include a connector element to releasably attach the head section 10 to the handle section 20, such that at least a mounting section of the head section 10 is secured relative to the handle section 20. The head section 10 may be repeatedly detached from the handle section 20 and reattached to the handle section to allow for cleaning of the head section 10 or replacement of a worn head section with a new head section or exchange of a first type of head section with a different type of head section. The handle section 20 may include a drive unit for driving the movement of the driven element 11 as discussed herein.

[0020] Figure 2 This is a depiction of the cut-away top portion of the handle section 20A of a personal care device, wherein the handle section 20A can be used for, for example Figure 1 The personal care device 1 is depicted with a handle section. The lower bottom of the handle section 20A is not shown. The handle section 20A includes a handle housing 21A in which a motor carrier 22A is mounted, and an attachment shaft 23A for detachably attaching the head section, as shown. Figure 1 The general outline is shown. The handle section 20A also includes a drive unit 25A, which is described below. The drive unit 25A includes a motor 30A having a motor shaft 31A and a motor shaft extension 40A, a drive shaft 70A, and a motion converter 5A. The motion converter 5A includes a deformable unit 50A, a mounting unit 60A, a coupling unit 59A, and a connector unit 8A. The motion converter 5A can be, for example, a single integral element manufactured by injection molding, or the motion converter 5A can include several elements fixed to each other, such as those relating to… Figure 3 The discussion is as follows. It should be understood, as will be clear to those skilled in the art, that according to this disclosure, Figure 2 Some of the features shown are optional and not required. For example, the motor carrier 22A is optional, and the drive unit 25A can be directly mounted on the handle housing 21A.

[0021] Motor 30A is fixed to motor carrier 22A. Motor 30A includes motor shaft 31A for providing rotational motion R about a central longitudinal axis A of motor shaft 31A. Motor shaft 31A extends via motor shaft extension 40A, which in the illustrated embodiment includes a first eccentric shaft element 41A, a second eccentric shaft element 42A, and a third eccentric shaft element 43A. Since all three eccentric shaft elements 41A, 42A, and 43A are shown in their central positions, their relative positions with respect to the longitudinal central axis A and with respect to each other are... Figure 2 It is not clearly visible in the middle, and the perspective view is shown in the reference. Figure 3 The motor shaft extension 40A may be integral with the motor shaft 31A, or it may be an additional element removably or non-removably attached to the motor shaft 31A. The first eccentric shaft element 41A and the third eccentric shaft element 43A have the same circumferential position about the longitudinal central axis A, and the second eccentric shaft element 42A has a circumferential position offset by 180 degrees relative to the first eccentric shaft element 41A and the third eccentric shaft element 43A. In operation, the three eccentric shaft elements 41A, 42A, and 43A move in a circle about the longitudinal central axis A, which extends in a plane perpendicular to the longitudinal central axis A. The first eccentric shaft element 41A and the third eccentric shaft element 43A are connected to a first crossbeam 80A, which includes a first arm element and a third arm element that engage with each other. The eccentric shaft elements 41A, 42A, and 43A are each connected to their respective arm element through an elongated hole, this relationship being determined from... Figure 3 and with Figure 3 The relevant description makes this clearer. The first arm element is connected to the first eccentric shaft element 41A, and the third arm element is connected to the third eccentric shaft element 43A. Therefore, the first eccentric shaft element 41A and the third eccentric shaft element 43A cooperate as a single eccentric shaft element in the illustrated embodiment to cause the first crossbeam 80A to perform a periodic linear reciprocating motion along a first crossbeam direction perpendicular to the longitudinal central axis A. The second eccentric shaft element 42A is similarly connected to the second crossbeam or the second arm element 81A, and when the second eccentric shaft element 42A rotates about the longitudinal central axis A, it causes the second crossbeam or the second arm element 81A to perform a periodic linear reciprocating motion along a second crossbeam axis that coincides with or is at least parallel to the axis of the first crossbeam. The periodic circular movements of the first axis element 41A, the third axis element 43A, and the second axis element 42A are offset by 180 degrees, that is, when the first crossbeam 80A moves to the right, the second crossbeam 81A moves to the left, and vice versa (where left and right are defined here relative to the plane of the paper). The arms and crossbeams, together with the aforementioned elongated holes, form a connecting unit 8A that is connected to the deformable unit 50A.

[0022] The first crossbeam 80A and the second crossbeam 81A, i.e., the first arm, the second arm, and the third arm, are each connected to the deformable unit 50A. The deformable unit 50A is implemented here as a rhombus structure with four sides and four vertices, but this should not be considered limiting. The rhombus structure is a special case of a more general category of convex quadrilateral structures, representing one possible implementation of the deformable unit. The four sides of the rhombus structure are here implemented by four arm segments 51A, 52A, 53A, and 54A. The first arm segment 51A has a first end fixed to a mounting structure 60A, which is here securely mounted to or relative to the motor 30A. Opposite to the first arm segment 51A in the rhombus structure is the third arm segment 53A, which also has a first end fixed to the mounting structure 60A, such that the first ends of the first arm segment 51A and the first ends of the third arm segment 53A form the first vertex 55A of the rhombus structure of the deformable unit 50A. The second end of the first arm segment 51A is connected to the first end of the second arm segment 52A at a generally obtuse angle, and the connection point is considered as the second vertex 56A of the rhomboid structure formed by the deformable unit 50A (or a "knee segment" resulting from the obtuse angle at which the first and second arm segments meet). The second end of the second arm segment 52A is connected to the connecting unit 59A. The first end of the fourth arm segment 54A, opposite the second arm segment 52A, is connected to the second end of the third arm segment 53A at an obtuse angle, thereby forming a third vertex 57A (or another "knee segment"). The second ends of the second arm segment 52A and the second ends of the fourth arm segment 54A are fixed to each other at the connecting element 59A, thereby forming a fourth vertex 58A.

[0023] The first crossbeam 80A (i.e., the first and third arms joined together) is connected to the second vertex 56A, and the second crossbeam 81A or the second arm is firmly connected to the third vertex 57A, which is the vertex opposite to the second vertex 56A. Once both the first and second crossbeams move outward or both move inward, the deformable unit 50A deforms and the connecting unit 59A is set to perform a linear reciprocating motion along axis A1. When the two crossbeams 80A and 81A move outward, the connecting unit 59A is pulled downward toward the motor 30A, and when the two crossbeams 80A and 81A move inward, the connecting unit 59A moves upward away from the motor 30A, generating a periodic linear reciprocating motion M as indicated by the double arrows, which occurs along axis A1, which is parallel to the central longitudinal axis A, along which the motor shaft 31A rotates, as indicated by arrow R.

[0024] The four vertices 55A, 56A, 57A, and 58A can each be implemented as essentially rigid structures without hinge functionality. Then, the arm segments 51A, 52A, 53A, and 54A each need to be able to extend substantially linearly from their respective ends (e.g., ...). Figure 2 As shown, (representing their natural or resting states) are deformed into deformed states, for example, arm segments 51A, 52, 53A, and 54A may each bulge inward or outward, or may extend along an S-shaped curve between their respective connecting vertices. Arm segments 51A, 52A, 53A, and 54A may be made substantially of a spring-loaded material such as spring steel or spring-loaded plastic, such that the energy required to deform arm segments 51A, 52A, 53A, and 54A is stored in the spring-loaded material and released again when arm segments 51A, 52A, 53A, and 54A return to their natural state.

[0025] The motor 30A, together with the motor shaft extension 40A, the drive shaft 70A and the motion converter 5A, forms the drive unit 25A according to the present disclosure.

[0026] Figure 3 This is a depiction of another exemplary drive unit 25B, which is related to... Figure 2 Shown and referenced Figure 2The drive unit 25A discussed has various structural similarities. Drive unit 25B includes a motion converter 5B having a deformable unit 50B, a mounting unit 60B connected to the deformable unit, a coupling unit 59B connected to the deformable unit 50B, and a connector unit 8B connected to the deformable unit 50B. Drive unit 25B also includes a motor 30B (shown only partially) having a motor shaft 31B, a shaft extension 40B attached to the motor shaft 31B, and a drive shaft 70B connected to the coupling unit 59B. The mounting unit 60B is here securely fixed to the motor 30B; however, in other embodiments, the motor 30B and the mounting unit 60B may be mounted on the same base structure (e.g., the handle of a personal care device) such that they are securely fixed relative to each other. Generally, the shaft extension 40B may be integral with the motor shaft 31B, or it may be a separate element securely fixed to the motor shaft 31B. In the latter case, the shaft extension 40B can snap-fit ​​onto the motor shaft 31B, and can be friction-locked, welded, glued, or securely attached in any other manner known to those skilled in the art. The drive unit 25B includes a drive shaft 70B connected to the coupling unit 59B, which can be coupled to a driven element. When the motor shaft 31B provides rotational movement about its longitudinal central axis, this movement is converted by the motion converter 5B of the drive unit 25B, and the drive shaft 70B will instead provide periodic linear reciprocating motion along an axis that coincides with or is parallel to the longitudinal central axis of the motor shaft 31B (see [reference needed] for indication of the corresponding longitudinal central axis A). Figure 2 The shaft extension 40B here again includes a first eccentric shaft element 41B, a second eccentric shaft element 42B, and a third eccentric shaft element 43B. The eccentric shaft elements 41B, 42B, and 43B are each offset relative to the longitudinal central axis, and therefore rotate about the longitudinal central axis along a circular path in operation, as also for... Figure 2 As described. Similarly, as for... Figure 2 As described, the first eccentric shaft element 41B and the third eccentric shaft element 43B have the same circumferential position and thus move in a positional and angular alignment manner, while the second eccentric shaft element 42B is circumferentially positioned with a 180-degree offset.

[0027] The first eccentric shaft element 41B and the third eccentric shaft element 43B are connected to the deformable unit 50B via connector unit 8B. Connector unit 8B includes a first crossbeam 80B, which is again forked and formed by first arms 801B and third arms 802B engaging with each other. The first arms 801B and third arms 802B are parallel to each other in the free end region, but this should not be construed as limiting, and any other configuration may be chosen. The second eccentric shaft element 42B is connected to the deformable unit 50B via the second crossbeam or second arm 81B of connector unit 8B. The first crossbeam 80B and the second crossbeam 81B extend, in a manner parallel to each other. The first crossbeam 80B is arranged to move along a first crossbeam direction perpendicular to the longitudinal central axis of the motor shaft 31B, and the second crossbeam 81B is arranged to move along a second crossbeam direction parallel to the axis of the first crossbeam, which is also, of course, perpendicular to the longitudinal central axis of the motor shaft 31B.

[0028] The deformable unit 50B is designed as a generally rhomboid structure with four sides and four vertices. The first side is formed by the first arm segment 51B, the second by the second arm segment 52B, the third by the third arm segment 53B, and the fourth by the fourth arm segment 54B. The first arm segments 51B and 53B are each mounted at their first ends on a mounting structure 60B, which is securely connected to the motor 30B. The mounting points together form the first vertex 55B of the rhomboid structure, which is a so-called "extended vertex" because there is a distance between the mounting sides of the first ends of the first arm segments 51B and 53B. The first arm segments 51B and 53B are oriented outwards relative to the central axis of the rhomboid structure. The first arm segment 51B has a second end connected to the first end of the second arm segment 52B to form the second vertex 56B of the rhomboid structure. Figure 3 As seen, the first arm segment 51B and the second arm segment 52B meet at an obtuse angle. This should not be considered limiting depending on the design of the deformable unit, and in cases including arm segments designed essentially as discussed in this context, these arm segments may meet at obtuse or acute angles, or the angle between two arm segments may be approximately 180 degrees in the resting state of the deformable unit. Furthermore, the second end of the third arm segment 52B connects to the first end of the fourth arm segment 54B to form a third vertex 57B. The second end of the second arm segment 52B and the second end of the fourth arm segment 54B connect to form a fourth vertex 58B, wherein a connecting element 59B is also integrated into this slightly extended fourth vertex 58B. The drive shaft 70B is connected here to the connecting unit 59B.

[0029] If available Figure 3As seen in the perspective view shown, arm segments 51B, 52B, 53B, and 54B are implemented as "double-arm segments," meaning each arm segment includes two parallel arm elements arranged at a certain distance. This makes the deformable unit 50B relatively lightweight overall, while still providing stable resistance to torsional deformation. In the illustrated design, the first arm segment 51B includes two parallel arm elements 511B and 512B, the second arm segment 52B includes two parallel arm elements 521B and 522B, the third arm segment 53B includes two parallel arm elements 531B and 532B, and the fourth arm segment 54B includes two parallel arm elements 541B and 542B. At the second, third, and fourth vertices, the parallel arm elements are connected by vertical strip elements. The second vertex 56B and the third vertex 57B each include mounting elements 561B and 571B, which provide fixing points for the first crossbeam 80B and the second crossbeam 81B of the connector unit 8B.

[0030] The first crossbeam 80B includes a first crossbeam arm 801B and a second crossbeam arm 802B, which are parallel to each other over a certain extension length to avoid interfering with the second crossbeam 81B, which moves between the two crossbeam arms 801B and 802B. The first crossbeam arm 801B is connected to a first eccentric shaft element 41B through an elongated hole 804B provided in the first crossbeam arm 801B, and the second crossbeam arm 802B is connected to a third eccentric shaft element 43B through an elongated hole 805B provided in the second crossbeam arm 802B. The elongated holes 804B and 805B are perpendicular to the longitudinal central axis of the motor shaft 31B and oriented perpendicular to the axis of the first crossbeam. The first eccentric shaft element 41B extends through the elongated hole 804B, and the third eccentric shaft element 43B extends through the elongated hole 805B. The first crossbeam 80B includes a connecting portion 803B, at which the first crossbeam arm 801B and the second crossbeam arm 802B engage with each other, and the connecting portion 803B is securely connected to the mounting element 561B of the second apex 56B of the deformable unit 50B. The first crossbeam 80B and the mounting element 561B can be connected by overmolding, filling, threading, gluing, welding, or any other connection means known to those skilled in the art. The elongated holes 804B and 805B are sized such that the first eccentric shaft element 41B and the third eccentric shaft element 43B respectively substantially fit tightly through the elongated holes 804B and 805B relative to the direction defined by the axis of the first crossbeam, and the first eccentric shaft element and the third eccentric shaft element are free to move longitudinally in the elongated holes 804B and 805B when the motor shaft 31B rotates the shaft extension 40B. Due to this design, the elongated holes 804B and 805B transmit movement of the first eccentric shaft element 41B and the third eccentric shaft element 43B only in the direction of the first crossbeam axis to the second vertex 56B. Again, note that the first eccentric shaft element 41B and the second eccentric shaft element 41C move in alignment. Similarly, the second crossbeam 81B includes a connecting portion 813B that is securely connected to the mounting element 571B of the third vertex 57B. The size of the elongated hole 814B is set such that the second eccentric shaft element 42B fits substantially tightly through the elongated hole 814B relative to the direction defined by the second crossbeam axis, and that the second eccentric shaft element is able to move freely in the longitudinal direction of the elongated hole 814B when the motor shaft 31B rotates the shaft extension 40B. Due to this design, the elongated hole 814B transmits movement of the second eccentric shaft element 42B only in the direction of the second crossbeam axis to the third vertex 57B.When the second eccentric shaft element 42B is circumferentially offset by 180 degrees relative to the first eccentric shaft element 41B and the third eccentric shaft element 43B, the first crossbeam 80B and the second crossbeam 81B move in an oscillating manner in opposite directions. That is, when the first crossbeam moves to the right (relative to the "right" defined by the paper plane), the second crossbeam moves to the left, and vice versa. This means that the directions of motion of the two crossbeams periodically reverse at the same moment. Due to this design, when the first crossbeam 80B moves to the right and the second crossbeam 81B moves to the left, the deformable unit 50B is first "widened," which causes the connecting element 59B to be pulled toward the motor 30B. And when the first crossbeam 80B moves to the left and the second crossbeam 81B moves to the right, the deformable unit 50B is then "pressed together," which causes the connecting element 59B to move upward and beyond its rest position to reach the maximum deflection away from the motor 30B. This linear reciprocating motion of the connecting element 59B occurs periodically and in a direction that coincides with or is parallel to the longitudinal central axis of the motor shaft 31B. It should be noted here that, generally, i.e., for all embodiments, the eccentric shaft element must have a height extension along the longitudinal axis that accommodates the deformation of the deformable unit, allowing the connecting unit to move up and down according to the deformation.

[0031] exist Figure 2 and Figure 3 In the example shown, the first crossbeam has a forked structure and cooperates with two axially displaced eccentric shaft elements, which allows the connecting portion of the first crossbeam to have the same axial position as the connecting portion of the second crossbeam. This allows the first and third arm elements, as well as the second and fourth arm elements, to be designed to have the same length.

[0032] The co-pending applications EP21158962.7 and EP22156286.1 also describe the provisions based on... Figure 2 and Figure 3 The contents of these applications are incorporated herein by reference in the following description of drive units with hinge elements.

[0033] The focus of this application is relative to Figure 2 and Figure 3 The discussion focuses on modified designs for connector units 8A and 8B, specifically specifying modifications to the receiving portions of elongated holes 804B, 805B, and 814B. For example... Figure 3 As can be seen, the elongated holes 804B, 805B, and 814B are defined by elements having substantially O-shaped or diamond-shaped cuts, wherein the cuts define the elongated holes. (See reference...) Figure 4A , Figure 4B and Figure 5 The O-cavities discussed here require long cores in the injection molding tool, for example, cores that define all three cuts. Based on the discussions in this paper... Figure 2 andFigure 3 In this design change, the O-shaped receiver is replaced by a U-shaped receiver, which includes a support element positioned such that the internal cutout of the elongated hole defined by the U-shaped receiver can be accessed from the side, i.e., by introducing a shape-forming element on the mold tool side extending along the length of the elongated hole. Therefore, the proposed design allows for the elimination of the long core required for manufacturing motion converters 8A or 8B. The support element mentioned can be strip-shaped, U-shaped, or O-shaped. The support elements discussed below are all O-shaped because such support elements provide stability to the free ends of the U-shaped legs of the U-shaped receiver and provide geometric symmetry, making the stability similar in all directions. Without such a stabilizing support element, the width of the elongated hole defined by the U-shaped receiver would become ambiguous during operation because the eccentric shaft element would bend open the U-shaped legs, resulting in noise and vibration. Therefore, the proposed design modifications to the motion converter discussed in the previously cited application are intended to provide a motion converter that is easily manufactured in an injection molding process while still possessing good stability of a receiving portion designed to mate with an eccentric shaft element, thereby causing periodic deformation of the deformable unit and thus converting the rotational motion of a motor shaft, such as an off-the-shelf DC motor, into linear reciprocating motion of a drive shaft. It should be understood that the ease of manufacture is not altered even if the motion converter is not entirely manufactured using an injection molding process but rather incorporates inserts, such as metal sheets, for some part of the motion converter.

[0034] Figure 4A It is a perspective depiction of the example motion converter 5C, and Figure 4B yes Figure 4A The side view of the motion converter shown. Figure 5 yes Figure 4A and Figure 4B Enlarged detail of connector unit 8C of motion converter 5C shown.

[0035] Figure 4A and Figure 4B The motion converter 5C shown is essentially a single, integral part manufactured by injection molding, wherein a metal drive shaft 70C is connected to a coupling section 59C of the motion converter 5C, wherein during the injection molding process, the metal drive shaft 70C is configured as an insert into a corresponding cavity of the molding tool. The motion converter 5C includes a deformable unit 8C connected to a mounting unit 60Cm, a coupling unit 59C, and a connector unit 8C, which... Figure 4A The perspective view is partially hidden by the deformable unit 8C and can be seen in Figure 4B This can be seen better in the front view. The basic structure of connector unit 8C is similar to that of... Figure 2 and Figure 3Connector units 8A and 8B are discussed. Therefore, reference is made to... Figure 2 and Figure 3 Related discussion. The deformable unit 50C is again designed as a generally rhomboid structure with four sides and four vertices, wherein the deformable unit 50C can be described as being formed by two relatively positioned H-shaped arm structures, wherein each H-shaped arm structure bends outward at the level of the vertical bar of the H. The two relatively arranged H-shaped arm elements realize a first arm segment 51C with two generally parallel arm elements 511C and 512C, a second arm segment 52C with two generally parallel arm elements 521C and 522C, a third arm segment 53C with two generally parallel arm elements 531C and 532C, and a fourth arm segment 54C with two generally parallel arm elements 541C and 542C. As in Figure 4B As can be best seen from the image, connector unit 8C includes a first receiving portion 90C, a second receiving portion 91C, and a third receiving portion 91C, which are again designed to receive the eccentric shaft portion, such as from... Figure 6A to Figure 6C It can be seen in the image.

[0036] Figure 5 yes Figure 4A This is an enlarged view of the cross-sectional detail of the motion converter 8C. In this depiction, the motion converter 8C includes three receiving portions 90C, 91C, and 92C. The first receiving portion 90C has a generally U-shaped receiving body 901C, an elongated receiving hole 902C, and an O-shaped support element 903C. The second receiving portion 91C has a generally U-shaped receiving body 911C, an elongated receiving hole 912C, and an O-shaped support element 913C. The third receiving portion 92C has a generally U-shaped receiving body 921C, an elongated receiving hole 922C, and an O-shaped support element 923C. When support elements 903C and 923C face one direction, the second support element 913C faces the opposite direction; this design is chosen for manufacturing reasons. Figure 6C A more extensive discussion of the structure of the receiving section and the corresponding eccentric shaft extension element is provided, and references are made to... Figure 7 A more general discussion of the structure of the receiving section is given.

[0037] Figure 6A This is a side view of the drive unit 25D including the motion converter 5D shown, which can be connected with... Figure 4A , Figure 4B and Figure 5 The motion converter shown is the same. Figure 6B Is it through Figure 6A The cross-section of the drive unit 25C is shown, wherein the drive unit is rotated 90 degrees about its longitudinal axis. Figure 6C Is it like this? Figure 6BEnlarged view of details of connector unit 8D and motor shaft extension 40D shown.

[0038] Figure 6A The drive unit 25D shown includes a driver 30D, which can be implemented as a ready-made DC motor, a motion converter 5D, and a drive shaft 70D. The motion converter 5D includes a deformable unit 50D, a mounting unit 60D, a connector unit 8D, and a coupling unit 59D. The driver or motor 30D includes a motor shaft 31D and a motor shaft extension 40D. These components and their functions and structures have been described in the preceding paragraphs and do not need to be repeated. Figure 6B The cross section shown is specifically taken in a plane extending through the motor shaft 31D, the motor shaft extension 40D, and the three eccentric shaft elements 41D, 42D, and 43D. Figure 6B The text indicates part A, which is in... Figure 6C It is shown in a magnified manner. Figure 6C As can be seen, the first eccentric shaft element 41D extends through a U-shaped cutout 902D in the form of a U-shaped elongated hole in the first receiving portion 90D. The second eccentric shaft element 42D extends through a U-shaped cutout 912D in the form of a U-shaped elongated hole in the second receiving portion 91D. The third eccentric shaft element 43D extends through a U-shaped cutout 922D in the form of a U-shaped elongated hole in the third receiving portion 92D. (As already shown relative to...) Figure 5 The motion converter 5C shown in the middle section discusses receiving portions 90D, 91D, and 92D, each of which includes corresponding O-shaped support elements 903D, 913D, and 923D. These O-shaped support elements provide stability to the open ends of the U-shaped elongated holes 902D, 912D, and 922D to prevent bending and opening. It can also be seen that receiving portions 90D, 91D, and 92D, and therefore the corresponding elongated holes 902D, 912D, and 922D, each taper towards the closed end of the respective receiving portion. This allows for better deformation of the mold protrusion defining the elongated hole.

[0039] Figure 7 This is a schematic diagram of the receiving portion 90E of the connector unit, which is part of a motion converter for a transmission system as proposed herein. The eccentric shaft element 41E is shown in dashed lines, as are the arms 801E of the connector unit. Figure 7 The focus is on the structure of the receiving part 90E and its interaction, as well as the motion generated by the movement of the eccentric shaft element 41E.

[0040] The receiving portion 90E has a generally U-shaped cutout in the form of an elongated aperture 902E and a generally U-shaped body 901E. The U-shaped body 901E has a U-shaped base 9011E and two U-shaped legs 9012E and 9013E, which together define the elongated aperture 902E. The U-shaped legs 9012E and 9013E have free leg ends 9014E and 9015E, respectively, which are fixed relative to each other by a support element 903E, which is strip-shaped in the illustrated embodiment. Figure 7 The diagram illustrates a coordinate system defining the x, y, and z directions. A rod-shaped support element 903E extends in the y direction. While support element 903E is clearly a three-dimensional object extending in all three spatial directions, it should be understood that "direction of extension" as used herein generally refers to the primary direction of extension. An elongated U-shaped aperture 902E has a length l extending in the x direction, a width w extending in the y direction, and a height h extending in the z direction relative to the indicated coordinate system. Support element 903E is constructed and positioned such that a passageway is provided through the entire width w and the entire height h via the x direction into the elongated aperture 902E. This allows the receiving portion 90E to be defined by two half-molds, which close by moving together in the x direction. This would not be possible if the elongated aperture were an O-shaped cutout, i.e., due to the fact that an O-shaped aperture is closed along its circumference while a U-shaped aperture has an opening, the elongated aperture would then only be defined by the additional core extending in the z direction, as already mentioned above. In the operation of the transmission system as discussed in this disclosure, the eccentric shaft element 41E extends through the elongated bore 902E in the z-direction. The eccentric shaft element 41E has a cylindrical shape and a diameter d that substantially coincides with the width w of the elongated bore, and has a central axis A extending in the z-direction. E The cylindrical eccentric shaft element 41E also has a height, extending above and below the receiving portion 90E, such that upward or downward movement of the receiving portion 90E due to deformation of the deformable unit is supported by the cylindrical portion. Assume the motor shaft (not shown) is about the longitudinal central axis A. M Rotate and connect with the eccentric shaft extension 41E, such that the eccentric shaft extension 41E moves along a circle C having a diameter D, as... Figure 7 As shown, when the eccentric shaft extension 41E moves along circle C, movement in the x-direction occurs freely in the elongated hole 902E, and movement in the y-direction is transmitted to the receiving part 90E, causing the receiving part to move periodically in the y-direction along the double arrow P, where the peak-to-peak amplitude coincides with the diameter D of circle C. The arm 801E then transmits this movement to the deformable unit of the motion converter, causing the deformable unit to deform periodically, as discussed in the previous paragraphs. At least the outer surface region of the eccentric shaft extension 41E that contacts the elongated hole 902E and / or at least the inner surface of the elongated hole 902E can be coated to reduce friction between the two parts.

[0041] The dimensions and values ​​disclosed herein should not be construed as strictly limited to the precise numerical values ​​cited. Rather, unless otherwise specified, each such dimension is intended to represent the stated value and the range surrounding its functional equivalent. For example, a dimension disclosed as “40 mm” is intended to represent “approximately 40 mm”.

Claims

1. A motion converter configured to convert rotational motion provided by a motor shaft into linear reciprocating motion of a drive shaft, the motion converter comprising: Deformable element; The mounting unit is connected to the deformable unit; A coupling unit, which is connected to the deformable unit, is configured to receive the drive shaft or the coupling unit includes the drive shaft; A connector unit, connected to the deformable unit, includes at least a first substantially U-shaped receiving portion and a first support element. The first substantially U-shaped receiving portion is configured to receive a first eccentric shaft element of the motor shaft and has a U-shaped base and two U-shaped legs. The U-shaped base and the two U-shaped legs together define a first elongated aperture having a length, width, and height. The first support element is connected to the two U-shaped legs of the first substantially U-shaped receiving portion at their free ends, such that a passage is provided across the width and height of the first elongated aperture. Preferably, the first support element is strip-shaped, U-shaped, or O-shaped, and the length is measured from the inner surface of the U-shaped base to the free end of the U-shaped leg.

2. The motion converter according to claim 1, wherein the motion converter is an integral component, preferably an injection-molded component.

3. The motion converter according to claim 1 or claim 2, wherein the connector unit includes at least a first arm element that connects the first substantially U-shaped receiving portion to the deformable unit.

4. The motion converter according to any one of claims 1 to 3, wherein the deformable unit is configured to deform periodically along the z-direction to provide the linear reciprocating motion along the z-direction, and to deform periodically along the y-direction, the z-direction and the y-direction spanning a plane, and wherein the first elongated aperture extends longitudinally along the x-direction, the x-direction being perpendicular to the plane spanned by the z-direction and the y-direction.

5. The motion converter of claim 4, wherein the first strip-shaped, U-shaped, or O-shaped support element of the two U-shaped legs connected to the first substantially U-shaped receiving portion at its free end extends in a plane parallel to the plane spanned by the z-direction and the y-direction.

6. The motion converter according to any one of claims 1 to 5, wherein the connector unit includes a second generally U-shaped receiving portion and a strip-shaped, U-shaped, or O-shaped support element, the second generally U-shaped receiving portion being configured to receive a second eccentric shaft element and having a U-shaped base and two U-shaped legs, the U-shaped base and the two U-shaped legs together defining a second elongated aperture having a length, width, and height, the second strip-shaped, U-shaped, or O-shaped support element connecting the two U-shaped legs at the free ends of the two U-shaped legs of the second generally U-shaped receiving portion such that a passage is provided across the width and height of the second elongated aperture into the second elongated aperture.

7. The motion converter of claim 6, wherein the connector unit includes at least a second arm element that connects the second substantially U-shaped receiving portion to the deformable unit.

8. The motion converter according to any one of claims 6 or 7, wherein the connector unit comprises a third substantially U-shaped receiving portion and a third strip-shaped, U-shaped, or O-shaped support element, the third substantially U-shaped receiving portion being configured to receive a third eccentric shaft element and having a U-shaped base and two U-shaped legs, the U-shaped base and the two U-shaped legs together defining a third elongated aperture having a length, width, and height, the third strip-shaped, U-shaped, or O-shaped support element connecting the two U-shaped legs at their free ends such that a passage is provided across the width and height of the elongated aperture into the third elongated aperture.

9. The motion converter of claim 8, wherein the connector unit includes at least a third arm element that connects the third substantially U-shaped receiving portion to the deformable unit, preferably wherein the second arm and the third arm engage with each other.

10. The motion converter according to any one of claims 1 to 9, wherein the deformable unit has a generally convex quadrilateral type structure, preferably a rhomboid structure, the generally convex quadrilateral type structure having four sides and four vertices, wherein the mounting unit and the connecting unit are disposed at two substantially opposite vertices of the convex quadrilateral type structure, and the connector unit is connected to at least one of the two other vertices, preferably to both of the two other substantially opposite vertices.

11. The motion converter according to any one of claims 10 and 6 to 9, wherein the first arm is connected to one of the vertices, and the second arm is connected to the corresponding opposite vertex.

12. A drive unit comprising a motion converter according to any one of claims 1 to 11, the drive unit further comprising: A drive shaft, connected to the coupling unit, is used to provide the linear reciprocating motion during operation; A motor having a motor shaft that provides rotational motion about a longitudinal central axis during operation; A motor shaft extension, which is coupled to or connected to the motor shaft, includes at least a first eccentric shaft element arranged eccentrically relative to the longitudinal central axis, such that the first eccentric shaft element moves in operation along a circular path around the longitudinal central axis. The first eccentric shaft element extends through the first elongated hole along the height direction of the first elongated hole, the first eccentric shaft element has a diameter that fits tightly into the first elongated hole in the width direction of the first elongated hole, and the first eccentric shaft element is able to move freely in the first elongated hole in the length direction of the first elongated hole during operation.

13. The drive unit according to claim 12, wherein the motor shaft extension has a second eccentric shaft element arranged eccentrically relative to the longitudinal central axis, wherein the second eccentric shaft element extends through the second elongated hole in the height direction, the second eccentric shaft element has a diameter that fits tightly into the second elongated hole in the width direction, and the second eccentric shaft element is operable to move freely in the second elongated hole in the length direction.

14. The drive unit of claim 13, wherein the first eccentric shaft element and the second eccentric shaft element are disposed opposite to each other relative to the longitudinal central axis, such that in operation the first eccentric shaft element and the second eccentric shaft element rotate about the longitudinal central axis at an angular distance of 180 degrees.

15. A personal care device comprising a drive unit according to any one of claims 12 to 14, the personal care device comprising a head section coupled to the drive shaft such that the head section or a driven element of the head section is driven in operation to reciprocate, such as an oscillating motion or a reciprocating motion, optionally wherein the mounting unit of the motion converter is securely mounted relative to the motor, and further optionally wherein in operation, at least the circular motion of the first eccentric shaft element causes at least the first substantially U-shaped receiving portion to transmit a periodic force to the deformable unit, causing the deformable unit to deform periodically, preferably wherein the periodic deformation refers to periodic deformation in the z-direction and a 180-degree phase-shifted periodic deformation in the y-direction perpendicular to the z-direction.

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