Personal care device

Abstract

Provided in the present invention is a personal care device. A driving device comprises: a coil assembly, a main magnetic conductor, a coil and a coil holding portion for holding the coil, the coil holding portion being fixed relative to a housing; a magnet assembly, which has a permanent magnet and a magnet holding portion having a magnetic conductive portion, the magnet assembly being linearly and reciprocally movable relative to the coil assembly along the longitudinal axis of the driving device; and an elastic member, which acts between the coil assembly and the magnet assembly, the elastic member being configured to apply an elastic force in the longitudinal axis direction. The driving device comprises a transverse magnetic conductor arranged transverse to the longitudinal axis, at least part of the transverse magnetic conductor extending on the inner side of the magnet holding portion in the lateral space of the permanent magnet along one side or both sides parallel to the longitudinal axis direction. The permanent magnet faces the coil with a transverse gap formed therebetween, and most of magnetic force lines generated by the coil do not pass through the transverse gap. The personal care device of the present invention achieves stable operation, low noise and low vibration, and thus the device exhibits high comfort in use.

Description

Personal care devices Technical Field

[0001] This invention relates to the technical field of personal care devices, and more specifically, to a drive device in a personal care device for achieving linear reciprocating movement. Background Technology

[0002] Currently, there are various personal care devices on the market, such as electric toothbrushes and electric facial cleansers, which include drive devices for reciprocating motion. These drive devices are connected to external cleaning or operating components to achieve the corresponding actions.

[0003] In some personal care devices, the drive mechanism is configured to achieve linear reciprocating motion. However, existing drive mechanisms for achieving linear reciprocating motion have some shortcomings. For example, some drive mechanisms use a motor with gears and linkages to achieve linear reciprocating motion. However, these types of drive mechanisms have many mechanical parts, high requirements for the manufacturing tolerances of the parts, and are more complex to install. In addition, these drive mechanisms are also prone to generating noise.

[0004] Other personal care devices utilize a drive mechanism consisting of a permanent magnet and a coil, employing an alternating electromagnetic force generated by an alternating current in the coil as the driving force. The magnetic flux generated by the current-carrying coil passes through the air gap between the magnet and the coil, and within the permanent magnet. The magnetic field lines generated by the current-carrying coil are prone to distortion, as are the magnetic field lines generated by the permanent magnet. This magnetic distortion produces an electromagnetic force, which, according to physics, includes a force with a frequency of 2*f0. Since the coil is fixed, according to Newton's first law, the permanent magnet experiences a resultant force C from the Lorentz force and the electromagnetic force, where C = Asinωt + Bsin2ωt, A is the amplitude of the Lorentz force, and B is the amplitude of the electromagnetic force with a frequency of 2*f0. This resultant force C serves as the driving force for the permanent magnet. Since C cannot achieve simple harmonic resonance, the amplitude of the permanent magnet will vary periodically over time. This fluctuating amplitude of the permanent magnet is detrimental to the stable operation of the personal care device and generates additional high-order frequency noise and vibration.

[0005] Therefore, it is desirable to improve the drive mechanism of existing personal care devices to enable them to operate more smoothly. Summary of the Invention

[0006] To overcome the shortcomings of existing technologies, make the operation of personal care devices smoother, reduce noise and vibration, and improve user comfort, this invention provides a personal care device including a housing and a drive device disposed within the housing. The drive device includes: a coil assembly having a dominant magnet arranged along the longitudinal axis of the drive device, a coil, and a coil holding portion for holding the coil, the coil holding portion being fixed relative to the housing; a magnet assembly having a permanent magnet and a magnet holding portion for holding the permanent magnet, the magnet holding portion including a magnetically conductive portion, the magnet assembly being capable of linear reciprocating relative to the coil assembly along the longitudinal axis; and an elastic element acting between the coil assembly and the magnet assembly, the elastic element being arranged to apply an elastic force along the longitudinal axis direction, wherein the drive device includes a transverse magnetically conductive portion arranged transversely to the longitudinal axis, at least a portion of the transverse magnetically conductive portion extending inside the magnet holding portion in a lateral space on one or both sides of the permanent magnet along a direction parallel to the longitudinal axis direction, the permanent magnet being opposite to the coil and forming a transverse gap therebetween, and most of the magnetic lines of force generated by the coil not passing through the transverse gap.

[0007] According to one aspect of the invention, the transverse magnetic conductor includes side magnetic conductors respectively disposed on both sides of the coil. The side magnetic conductors extend from one of the magnetic conductor portion of the magnet holder and the dominant magnet of the coil assembly, and extend close to the other of the magnetic conductor portion of the magnet holder and the dominant magnet of the coil assembly. The end face of the transverse magnetic conductor forms a coil magnetic field air gap with the opposite magnetic conductor portion or dominant magnet face. In the transverse direction, the distance of the coil magnetic field air gap is not greater than the thickness of the permanent magnet.

[0008] According to another aspect of the invention, the permanent magnet includes a first permanent magnet and a second permanent magnet disposed along a longitudinal axis, with a longitudinal gap formed between the first permanent magnet and the second permanent magnet, each permanent magnet being opposite to a coil and forming a transverse gap therebetween, the transverse magnetic conductor further including an intermediate magnetic conductor, a portion of which is inserted into the longitudinal gap.

[0009] Preferably, the coil assembly includes a first coil and a second coil, with a first permanent magnet and a second permanent magnet respectively arranged opposite to the first coil and the second coil and separated by a transverse gap; the first coil and the second coil are wound around a central magnetic conductor at intervals around each other on a main magnet, with the central magnetic conductor located between the first coil and the second coil, and the free end of the central magnetic conductor inserted into the longitudinal gap. Alternatively, the coil assembly includes a first coil and a second coil, which are wound around a central magnetic conductor and arranged on both transverse sides of the main magnet, with the first permanent magnet and the second permanent magnet respectively facing partial end faces of the coils on both sides of the central magnetic conductor and separated by a transverse gap.

[0010] According to another aspect of the invention, the personal care device further includes a buffer disposed between a coil holding portion and a portion of the inner surface of the housing along a longitudinal axis, and also includes a drive shaft connected to the magnet holding portion of the magnet assembly. A stepped portion is formed inside the housing. The coil holding portion includes a coil support and a main support fixedly connected to the coil support. The buffer is disposed between the inner surface of the stepped portion near the drive shaft and the end face of the main support, and seals against the inner surface, the end face, and the drive shaft.

[0011] According to another aspect of the invention, the personal care device further includes a drive shaft and a support shaft, the drive shaft being fixedly connected to the support shaft and the support shaft being fixedly connected to the magnet assembly. The coil holding portion includes a coil support and a main support fixedly connected to the coil support. The support shaft is supported by the main support via a linear bearing or a bushing. Preferably, the support shaft includes a front support shaft and a rear support shaft, the drive shaft being fixedly connected to the front support shaft or the front support shaft and the drive shaft being integrally formed. The elastic element is a pair of helical springs, which are respectively sleeved on the front support shaft and the rear support shaft, and the two ends of the helical springs respectively abut against the main support and the magnet holding portion of the magnet assembly.

[0012] According to another aspect of the invention, the personal care device further includes a drive shaft and a support shaft, the drive shaft and the support shaft being fixedly connected to a magnet holding part, the coil holding part including a coil support and a main support fixedly connected to the coil support, the elastic element including a leaf spring, one end of the leaf spring being fixedly connected to the drive shaft or the support shaft, and the other end of the leaf spring being fixed to the main support.

[0013] According to another aspect of the invention, the magnet holding part further includes an outer frame, a magnetically conductive part is fixedly connected to the inner side of the outer frame, and a permanent magnet is fixedly connected to the inner side of the magnetically conductive part. The permanent magnets are arranged in pairs on both sides about the longitudinal axis, and the size of the transverse gap on both sides is substantially equal. The magnetic poles of the permanent magnets on both sides facing the coil are selected according to the direction of current flow in the coil portions on both sides. When the direction of current flow in the coil portions on both sides is the same, the magnetic poles of the permanent magnets on both sides facing the coil are opposite. When the direction of current flow in the coil portions on both sides is opposite, the magnetic poles of the permanent magnets on both sides facing the coil are the same.

[0014] According to another aspect of the invention, the length of the other of the magnetic conductor of the magnet assembly and the main magnet of the coil assembly along the longitudinal axis is greater than or equal to the distance between the outer surfaces of the two side magnetic conductors along the longitudinal axis plus twice the allowable amplitude of the elastic element.

[0015] According to another aspect of the invention, the surface of the permanent magnet forming the magnetic pole extends parallel to the longitudinal axis, and the portion of the magnetic conductor with the coil wound around it extends parallel to the longitudinal axis. The length of the permanent magnet along the longitudinal axis is greater than or equal to the sum of the length of the coil along the longitudinal axis and twice the amplitude of the elastic element. The permanent magnets are arranged in pairs on both sides about the longitudinal axis, and the transverse gaps are substantially equal along the longitudinal axis.

[0016] In the device according to the invention, the drive unit can easily achieve simple harmonic resonance similar to that of a spring oscillator, i.e., the drive unit, as a vibrating system, is subjected to a periodic external force with a frequency close to or equal to the system's natural frequency. Furthermore, the device reduces magnetic field distortion, enabling smoother operation of the electrical device and reducing noise and vibration during use. Attached Figure Description

[0017] For a more complete understanding of the invention, reference can be made to the following description of exemplary embodiments taken in conjunction with the accompanying drawings, in which:

[0018] Figure 1 shows a schematic diagram of the external shape of an electric toothbrush according to a preferred embodiment of the present invention.

[0019] Figure 2 shows a perspective view of the internal structure of an electric toothbrush according to a preferred embodiment of the present invention.

[0020] Figure 3 shows a perspective view of the drive device according to a first embodiment of the present invention, wherein a portion of the coil holding portion is removed.

[0021] Figure 4 shows another perspective view of the drive device according to a first embodiment of the present invention.

[0022] Figure 5 shows a perspective view of the coil and magnetic conductor assembly according to a first embodiment of the present invention.

[0023] Figure 6 shows a schematic diagram of the coil and permanent magnet assembly according to a first embodiment of the present invention.

[0024] Figure 7 shows a perspective view of the drive device according to a second embodiment of the present invention.

[0025] Figure 8 shows another perspective view of the drive device according to a second embodiment of the present invention.

[0026] Figure 9 shows a perspective view of a drive device according to a third embodiment of the present invention.

[0027] Figure 10 shows a perspective view of a drive device according to a third embodiment of the present invention.

[0028] Figure 11 shows a perspective view of a drive device according to a third embodiment of the present invention, wherein a portion of the coil holding portion is removed.

[0029] Figure 12 shows a perspective view of the magnet holding part according to a third embodiment of the present invention.

[0030] Figure 13 shows a partial perspective view of the leaf spring and drive shaft assembly according to a third embodiment of the present invention.

[0031] Figure 14 shows a perspective view of a drive device according to a fourth embodiment of the present invention, installed inside a housing.

[0032] Figure 15 shows a perspective view of a drive device according to a fourth embodiment of the present invention.

[0033] Figure 16 shows another perspective view of the drive device according to a fourth embodiment of the present invention, wherein a portion of the coil holding portion and the magnet holding portion are removed.

[0034] Figure 17 shows another perspective view of the drive device according to a fourth embodiment of the present invention, wherein a portion of the coil holding portion has been removed.

[0035] Figure 18 shows a perspective view of the coil assembly of the driving device according to a fourth embodiment of the present invention.

[0036] Figure 19 shows a perspective view of the main structure of the drive device according to a fifth embodiment of the present invention.

[0037] Figure 20 shows an exploded perspective view of the main structure of the drive device according to a fifth embodiment of the present invention.

[0038] Figure 21 shows a perspective view of the main structure of the drive device according to the sixth embodiment of the present invention.

[0039] Figure 22 shows a perspective view of the main structure of the drive device according to the seventh embodiment of the present invention.

[0040] List of reference numerals: 1. Electric toothbrush; 2. Handle; 21. Housing; 201. Stepped section; 202. Groove; 3. Drive unit; 13, 23, 33, 43, 53; 4. Coil assembly; 130, 230, 330, 430, 530; 530. Coil holding section; 131, 231, 331, 431, 531; 531. Coil bracket; 132, 232, 332, 432, 532; 532. Main bracket; 133, 233, 333, 433, 533, 633; ​​533. Coil; 133A, 233A, 3... 33A, 433A, 533A coil frames; 134, 234, 334, 534 magnetic conductors; 134A, 234A, 634A, 734A main magnets; 134B, 234B, 634B, 734B intermediate magnetic conductors; 134C, 234C, 434C, 534C side magnetic conductors; 134CD, 134BD, 634AD end faces; 14, 24, 34, 44, 54, 64 magnet assemblies; 140, 240, 340, 44. 0. Magnet holding part 141, 241, 341, 441. Permanent magnet outer frame 142, 242, 342, 442, 542, 642, 742. Magnetic guiding part 642C, 742C. Side magnetic guiding body 145, 245, 345, 445, 545, 645, 745. Permanent magnet 145A, 245A. First permanent magnet 145B, 245B. Second permanent magnet 15, 25, 45, 55. Helical spring 35. Leaf spring 351. Leaf spring bracket 352. Leaf spring connectors 16, 26, 36, 46, 56; transverse gaps 17, 27, 37; longitudinal spacing 17A, 17C, 27A, 67A; coil magnetic field air gaps 180, 280, 380, 480, 580; drive shafts 181, 281, 381, 481, 581; support shafts 182, 282, 382, ​​482, 582; buffer components 191, 192, 193, 194, 195; linear bearings 7; brush head L; longitudinal axis S; lateral space. Detailed Implementation

[0041] The present invention will be further described below with reference to specific embodiments and accompanying drawings. More details are set forth in the following description in order to provide a full understanding of the present invention. However, the present invention can obviously be implemented in many other ways different from those described herein. Those skilled in the art can make similar extensions and derivations based on actual application situations without departing from the spirit of the present invention. Therefore, the scope of protection of the present invention should not be limited by the content of this specific embodiment.

[0042] Figure 1 is a schematic diagram showing the shape of a personal care device according to the present invention. In this example, the personal care device is an electric toothbrush 1, but the present invention is not limited to this and may also be a personal care device such as an electric facial cleanser or an electric shower.

[0043] As shown in Figure 1, the electric toothbrush 1 includes a handle 2 and a brush head 7. A drive shaft extends from a hole at one end of the handle 2, and the brush head 7 is detachably connected to the drive shaft. The handle 2 of the electric toothbrush 1 has a long, hollow cylindrical shell. The central axis extending through the drive shaft is referred to below as the longitudinal axis L. In the following description, "proximal / proximal / proximal end" generally refers to a position close to or relatively close to the brush head 7, and "distal / distal / distal end" generally refers to a position far from or relatively far from the brush head 7.

[0044] Figure 2 shows the internal structure of the handle 2 of the electric toothbrush 1 according to the present invention. The internal structure of the electric toothbrush 1 is mainly divided into three parts: a control part, a power supply part, and a drive part. The control part mainly includes some control components for controlling the operation of the power supply part and the drive part, such as a PCB board and control switches and devices. The power supply part includes a built-in rechargeable battery for providing power to the drive part and the control part. The drive part mainly includes a drive device 3 and a drive shaft 180, which reciprocates linearly along the longitudinal axis L under the drive of the drive device 3. In addition, most of the structure of the power supply part and the drive part is installed inside the housing 21.

[0045] First Embodiment

[0046] Figures 3 to 6 illustrate a drive device 3 according to a first embodiment of the present invention. The drive device 3 mainly includes a coil assembly 13, a magnet assembly 14, and an elastic element located between the coil assembly 13 and the magnet assembly 14, the elastic element being a helical spring 15.

[0047] The coil assembly 13 mainly includes a coil 133 and a coil holding part 130. The coil 133 is held on the coil body part. The coil body part mainly includes a magnetic conductor 134 and a coil frame 133A. The coil 133 is wound around the main magnet 134 and constrained by the coil frame 133A. Preferably, the magnetic conductor 134 and the coil frame 133A are made into a single piece by injection molding, wherein the plastic part forms the coil frame 133A.

[0048] In the first embodiment, the coil assembly 13 includes two coils 133 along the left-right direction of FIG3: a first coil and a second coil. The two coils 133 are wound around a portion of the magnetic conductor 134 extending along the longitudinal axis L and are arranged separately in the longitudinal axis L direction. The coil holding portion 130 is configured to hold the coils 133 inside the housing 21, that is, the coil assembly 13 is fixed relative to the housing 21 so that the coil assembly 13 is in a stationary state.

[0049] The magnetic conductor 134 of the coil assembly 13 includes a main magnetic conductor 134A extending along the longitudinal axis L, an intermediate magnetic conductor 134B extending perpendicular to the longitudinal axis L, and a side magnetic conductor 134C. The main magnetic conductor 134A and the intermediate magnetic conductor 134B are two rods, arranged perpendicularly to each other in a "+" shape, and the side magnetic conductors 134C are arranged on both sides of the longitudinal axis of the coil 133. The two coils 133 are wound around the main magnetic conductor 134A on both sides of the intermediate magnetic conductor 134B at a distance from each other. Both the intermediate magnetic conductor 134B and the side magnetic conductors 134C are arranged transversely to the longitudinal axis L, that is, extending along the transverse direction of the drive device (the radial direction of the handle). Preferably, they are arranged perpendicular to the longitudinal axis L. The intermediate magnetic conductor 134B and the side magnetic conductor 134C are also collectively referred to as transverse magnetic conductors.

[0050] The magnet assembly 14 mainly includes a permanent magnet 145 and a magnet holding part 140 for holding the permanent magnet 145. The permanent magnet 145 includes a first permanent magnet 145A and a second permanent magnet 145B disposed along the longitudinal axis L, with a longitudinal gap 17 between them. In the transverse direction perpendicular to the longitudinal axis L, the two permanent magnets 145 are respectively disposed facing the two coils 133, and a transverse gap 16 is formed therebetween.

[0051] In the first embodiment, the first permanent magnet 145A and the second permanent magnet 145B are arranged in pairs, each pair being symmetrically arranged on both sides of the longitudinal axis L. In other words, there are two first permanent magnets 145A arranged at a 180-degree angle around the longitudinal axis L, and there are also two second permanent magnets 145B arranged at a 180-degree angle around the longitudinal axis L. The first and second permanent magnets on both sides of the longitudinal axis L form a lateral gap 16 relative to the coil 133. Preferably, the lateral gaps 16 at the two locations are substantially equal in size. The permanent magnets 145 are distributed in pairs on both sides of the longitudinal axis of the drive shaft 180, which can counteract the torque formed by the Lorentz force on the drive shaft 180, reduce the torque acting on the handle housing 21, and improve the feel.

[0052] As clearly shown in Figure 6, the intermediate magnetic conductor 134B is located between the two coils 133, essentially centered. The lateral extension length of the intermediate magnetic conductor 134B is greater than the lateral distance between the paired permanent magnets 145 located on both sides of the longitudinal axis L, so that the free end of the intermediate magnetic conductor 134B extends into the longitudinal gap 17 between the first and second permanent magnets. At the same time, the lateral extension length of the two lateral magnetic conductors 134C is the same as that of the intermediate magnetic conductor 134B. Thus, at least a portion of each of the intermediate magnetic conductor 134B and the lateral magnetic conductors 134C extends in the respective lateral spaces S of the permanent magnet 145 as shown in Figure 6. These lateral spaces S are located inside the magnet holding part (i.e., on the side closer to the longitudinal axis L) and along a direction parallel to the longitudinal axis L on both sides of the permanent magnet 145. In the first embodiment, in the lateral space S, a portion of the transverse magnetic conductor is aligned with the permanent magnet 145 along a direction parallel to the longitudinal axis. The lateral space S is the lateral space occupied by the permanent magnet 145 extending bidirectionally along the longitudinal axis L. Preferably, at least a portion of the transverse magnetic conductor extends into the lateral space S on opposite sides of each permanent magnet 145.

[0053] As shown in Figure 6, after the free end of the intermediate magnetic conductor 134B is inserted into the longitudinal gap 17, a sufficient gap is still maintained between the free end and the permanent magnets 145A and 145B on both sides. The size of this gap should be set such that the free end of the intermediate magnetic conductor 134B does not interfere with the linear reciprocating movement of the permanent magnet 145 along the longitudinal axis. In other words, the longitudinal distance between the free end of the magnetic conductor 134B and the permanent magnet 145 should be greater than the allowable displacement distance of the spring 15. Similarly, the spacer between the free end of the side magnetic conductor 134C and the permanent magnets 145A and 145B should be set so as not to interfere with the linear reciprocating movement of the permanent magnet 145 along the longitudinal axis.

[0054] In a first embodiment, the coil holding portion 130 includes two main supports 132 and two coil supports 131. The coil supports 131 are configured to hold both ends of the coil 133, the two main supports 132 are fixed by fasteners, and the main supports are fixed to the housing 21 of the handle 2. Preferably, the coil supports 131 can be integrally formed with the main supports 132. In other alternative embodiments, the coil supports can be separately formed from the main supports and then fixedly connected by fastening devices.

[0055] In a preferred embodiment, the coil support 131 is divided into two halves along a plane parallel to the longitudinal axis L. Figure 4 shows one of the halves. Each half of the coil support 131 includes a longitudinal support plate extending in a direction parallel to the longitudinal axis L and a locking member extending from the inner surface of the longitudinal support plate. The locking members of the two coil supports 131 are engaged with each other at the end of the coil 133, preferably engaged with the coil holder 133A, thereby holding the coil 133 and the magnetic conductor 134.

[0056] The magnet holding part 140 of the magnet assembly 14 includes a permanent magnet outer frame 141 and a magnetic guiding part 142. The magnetic guiding part 142 is fixedly connected to the inner side of the permanent magnet outer frame 141 and is exposed on the inner side, while the permanent magnet 145 is fixedly connected to the inner side of the magnetic guiding part 142. The magnetic guiding part 142 is made of magnetically conductive material, while the outer frame 141 is usually made of molding material. Thus, the magnetic guiding part 142 and the outer frame 141 can be made into a single piece by injection molding. The outer frame 141 is a rectangular frame, and the drive shaft 180 and support shaft 181 located on the front and rear sides of the rectangular frame are made into a single piece with the outer frame 141 by injection molding. A helical spring 15 is sleeved on the support shaft 181. As shown in FIG3, one end of the helical spring 15 abuts against the outer frame 141, and the other end abuts against the coil holding part 130, arranged to apply an elastic force along the longitudinal axis L. The helical spring 15 is prestressed after being installed therebetween, so as to provide elastic force for reciprocating movement between the coil holding part 130 and the magnet holding part 140.

[0057] Since the magnetic reluctance of the magnetic conductor is much smaller than that of air, and the internal magnetic reluctance of the permanent magnet is close to that of air, when the magnetic conductor and air coexist, most of the magnetic flux will pass through the magnetic conductor, while very little magnetic flux will pass through the air. Therefore, the magnetic flux generated by the permanent magnet 145 flows through the transverse gap 16 between the coil 133 and the permanent magnet 145, enters the main magnet 134A, then enters the intermediate magnetic conductor 134A, the side magnetic conductor 134C, passes through the air gaps 17A and 17C of the coil magnetic field, then enters the magnetic conductor 142, and then returns to the permanent magnet 145, thus forming the magnetic circuit of the permanent magnet 145.

[0058] As shown in Figure 6, after the drive device 3 is powered on, an alternating current with an alternating frequency of f0 flows through the coil 133, generating a current-carrying component. This alternating current generates an alternating magnetic field. Since a gap is formed between the two longitudinally adjacent permanent magnets 145 in the first embodiment, combined with the free end of the intermediate magnetic conductor 134B inserted into the longitudinal gap 17, and the side magnetic conductor 134C extending into the lateral space S outside the permanent magnet 145, most of the magnetic flux generated by the coil 133 enters the magnetically conductive part 142 through the magnetic conductors 134A, 134B, 134C and the air gaps 17A, 17C of the coil magnetic field (as shown by the dashed lines in Figure 6). Therefore, most of the magnetic flux generated by the coil 133 does not pass through the transverse gap 16. Thus, only the magnetic flux generated by the permanent magnet 145 exists in the transverse gap 16. In the transverse gap 16, the magnetic field generated by the coil 133 does not affect or interfere with the magnetic field of the permanent magnet, and correspondingly, it does not pass through the permanent magnet 145.

[0059] The magnetic field generated by the permanent magnet 145 produces a Lorentz force on the current-carrying conductor of the coil 133 at the transverse gap 16. The frequency of this Lorentz force is the same as the frequency of the current in the coil 133. This Lorentz force can drive the magnet assembly 14 to reciprocate linearly relative to the coil assembly 13 in the direction indicated by arrow M. Here, the coil magnetic field air gaps 17A and 17C formed between the end faces 134BD and 134CD of the free end of the transverse magnetic conductor and the magnetic conductor part 142 can also be considered as the movement gap between the coil assembly 13 and the magnet assembly 14. In the transverse direction perpendicular to the longitudinal axis, the distance between the coil magnetic field air gaps 17A and 17C is not greater than the thickness of the permanent magnet (the thickness of the cross section of the permanent magnet 145 perpendicular to the longitudinal axis L).

[0060] If the magnetic field of the permanent magnet and the magnetic field generated by the coil interfere with each other, causing magnetic field distortion, an electromagnetic force will also be generated between the coil and the permanent magnet. The frequency of the electromagnetic force is twice the frequency of the coil current. Due to the geometry and relative position of the coil and the permanent magnet, an even higher frequency electromagnetic force will be generated between them. This high-frequency harmonic electromagnetic force is more likely to cause high-frequency noise and vibration, which is detrimental to the smooth operation of the drive device. In the first embodiment, the magnetic field of the permanent magnet 145 and the magnetic field generated by the coil 133 do not interfere with each other, thereby avoiding the generation of high-frequency electromagnetic force. The drive device 3 is only subjected to the Lorentz force with the same frequency as the coil current. Since the coil current changes periodically with I*sin(ωt), the Lorentz force also changes with F*sin(ωt), while the elastic force Ft of the helical spring is linearly related to the compression. When the natural frequency of the spring oscillator, which is composed of the elastic element and the mass of the system driving the elastic element, is close to or equal to the frequency of the Lorentz force, the spring oscillator enters a resonant state. The aforementioned resonance or harmonic state is simply referred to as simple harmonic resonance. The velocity of the moving part changes according to a sine curve, meaning the velocity change is continuous and differentiable, and the acceleration is also continuous and differentiable, resulting in smooth and shock-free motion. Therefore, under the drive of the periodic Lorentz force, the drive device 3 can achieve simple harmonic resonance or harmonic resonance similar to that of a spring oscillator. Compared to harmonic vibration, this results in smoother operation and reduces noise and vibration during the use of the electric toothbrush 1.

[0061] Furthermore, in the air gap of the coil magnetic field formed between the transverse magnetic conductor and the magnetically conductive part of the magnet assembly or the main magnet of the coil assembly, the magnetic field generated by the coil may interfere with the magnetic field generated by the permanent magnet, causing magnetic field distortion. To avoid this situation leading to the generation of high-frequency electromagnetic forces, according to the present invention, the end face of the free end of the transverse magnetic conductor preferably faces the magnetically conductive part. As shown in Figure 6, the end face 134BD of the intermediate magnetic conductor 134B and the end face 134CD of the side magnetic conductor 134C face the magnetically conductive part 142. When the transverse magnetic conductor is located on the coil assembly, the length of the magnetically conductive part 142 in the longitudinal axis direction of the magnet assembly is greater than or equal to the sum of the distance between the outer surfaces of the two side magnetic conductors 134C along the longitudinal axis L and twice the allowable amplitude of the spring 15. In this way, it is ensured that during the movement of the magnet assembly, the end face of the free end of the side magnetic conductor 134C always faces the magnetically conductive part or the magnetic conductor. The above arrangement ensures that the moving magnetic conductor 142 is perpendicular to the magnetic poles represented by the two end faces of the longitudinal axis L, and perpendicular to the magnetic poles represented by the end face 134BD of the middle magnetic conductor 134B and the end face 134CD of the side magnetic conductor 134C, effectively avoiding distortion between magnetic fields and preventing the generation of high-frequency electromagnetic forces.

[0062] Second Embodiment

[0063] As shown in Figures 7 and 8, the driving device of the second embodiment includes a coil assembly 23, a magnet assembly 24, and a helical spring 25. The main difference between the driving device of the second embodiment and the first embodiment lies in the arrangement of the coil 233 in the coil assembly 23. As shown in Figure 8, the coil assembly 23 includes a magnetic conductor 234, a coil 233, and a coil holding part 230. The magnetic conductor 234 includes a main magnetic conductor 234A, an intermediate magnetic conductor 234B, and a side magnetic conductor 234C. The coil 233 includes a first coil and a second coil. Both the first coil and the second coil are wound along the intermediate magnetic conductor 234B, which is arranged perpendicular to the longitudinal axis L, and the two are separated by the main magnetic conductor 234A. The two free ends of the intermediate magnetic conductor 234B are respectively inserted between two permanent magnets 245 (the first permanent magnet 245A and the second permanent magnet 245B) on the corresponding sides, and a coil magnet air gap 27A is formed between the free ends and the magnetic conductor part 242. The lateral magnet 234C extends in the lateral space of the permanent magnet 245 and approaches the magnetically conductive part 242, and similarly forms a coil magnet air gap relative to the magnetically conductive part 242. Similar to the first embodiment, most of the magnetic lines of force generated by the coil 233 do not pass through the lateral gap 26, and correspondingly do not pass through the permanent magnet 245.

[0064] In the second embodiment, the structure of the coil holding part 230 of the coil assembly 23 (such as the coil support 231, the main support 232, and the coil frame 233A), the magnet holding part of the magnet assembly 24 (such as the magnet outer frame 241 and the magnetic guide part 242), the support shaft 281, and the linear bearing 192 are similar to those in the first embodiment, and will not be described again here.

[0065] Third Embodiment

[0066] As shown in Figures 9 to 13, the driving device of the third embodiment includes a coil assembly 33 and a magnet assembly 34. The structure of the coil assembly 33 and the magnet assembly 34 in the third embodiment is basically similar to that of the coil assembly 23 and the magnet assembly 34 in the second embodiment. Under the guidance of the magnetic conductor and the magnetic guide part, most of the magnetic lines of force generated by the coil 333 do not pass through the transverse gap 36, and correspondingly do not pass through the permanent magnet 345.

[0067] The difference is that the elastic element that acts as the elastic element between the two components 33 and 34 is set as a leaf spring 35, which is installed between the coil assembly 33 and the magnet assembly 34 through a leaf spring mounting assembly.

[0068] Figure 12 illustrates a leaf spring assembly according to a preferred embodiment. The leaf spring assembly includes a leaf spring bracket 351 and a leaf spring connector 352. One end of the leaf spring 35 is fixedly connected to the leaf spring bracket 351, while the other end is fixedly connected to the leaf spring connector 352. In a preferred embodiment, the leaf spring 35 includes a first leaf spring and a second leaf spring, which are symmetrically arranged about the longitudinal axis L. The leaf spring bracket 351 is preferably annular, with one end of the leaf spring 35 embedded in the inner circumferential surface of the annular bracket. The leaf spring connector 352 is fixedly connected to the magnet holding portion 340 of the magnet assembly 34, the drive shaft 380, and the support shaft 381.

[0069] Preferably, the leaf spring 35, leaf spring bracket 351, and leaf spring connector 352 can be integrally molded using an embedded molding process. In this embodiment, preferably, the leaf spring connector 352, leaf spring bracket 351, and support shaft 381 or drive shaft 380 are first integrally injection molded, and then the integral part is integrally formed with the magnet holding part 340 by an injection molding process. The support shaft 381 is then movably mounted into the main bracket 332 by means of a linear bearing 193. To facilitate the molding of the leaf spring connector 352 and the magnet holding part 340, a groove is formed at the end of the leaf spring connector 352, which will make the subsequent injection molding process more secure. On the other hand, the leaf spring bracket 351 is fixed to the main bracket 332 by fasteners.

[0070] In the third embodiment, the coil holding part 330 (such as coil support 331, main support 332, coil frame 333A), coil 333, magnetic conductor 334, magnet holding part 340 (such as permanent magnet outer frame 341, magnetic conductor 342), support shaft 381 or drive shaft 380, and linear bearing 193 of the coil assembly 33 are similar to those in the first embodiment. Here, the linear bearing 193 can also be replaced by a bushing. Further details are omitted here.

[0071] Fourth embodiment

[0072] As shown in Figures 14 to 18, the driving device of the fourth embodiment includes a coil assembly 43, a magnet assembly 44, and a helical spring 45 that provides a reciprocating elastic force between the coil assembly 43 and the magnet assembly 44.

[0073] In the fourth embodiment, as shown in FIG16, the coil assembly 43 includes a single coil 433 wound around a magnetic conductor extending around a longitudinal axis L. Correspondingly, the magnet assembly 44 includes a pair of permanent magnets 445 symmetrically distributed on both sides of the longitudinal axis L. The two permanent magnets 445 face the same coil 433 on both sides, and the magnetic poles of the permanent magnets 445 are separated from the coil 433 by a transverse gap 46. The magnet assembly 44 also includes two side magnetic conductors 434C extending from between opposing magnetic conductors 442. They are respectively arranged on the front and rear end sides of the coil 433, and at least a portion of the two side magnetic conductors 434 extends in the lateral space on the front and rear sides of the permanent magnets 445. In addition, in this embodiment, the length of the permanent magnets 445 in the longitudinal axis L direction is substantially equal to the length of the coil 433. In this way, most of the magnetic lines of force generated by the coil 433 are guided through the side magnetic conductors 434 on the front and rear sides, and do not pass through the transverse gap 46, and correspondingly, do not pass through the permanent magnets 445.

[0074] In the fourth embodiment, the coil holding part 430 of the coil assembly 43 (such as coil support 431, main support 432, coil frame 433A), the magnet holding part 440 of the magnet assembly 44 (such as permanent magnet outer frame 441, magnetic guide part 442), as well as the support shaft 481 and drive shaft 480 are similar to those in the first embodiment, and will not be described again here.

[0075] A square wave voltage with frequency f0 is applied to coil 433. Positive and negative currents flow through coil 433. Expanding according to Fourier series, a sinusoidal current with a large amplitude and frequency f0 flows through coil 433, while simultaneously, a harmonic current with a smaller amplitude flows. The fundamental frequency force keeps the simple harmonic oscillation system in a resonant state, while the harmonic force effectively suppresses the vibration amplitude of the simple harmonic oscillation system. This allows the personal care device to operate more smoothly, reducing noise and vibration during the use of the electric toothbrush 1.

[0076] Fifth Embodiment

[0077] As shown in Figures 19 and 20, the driving device of the fifth embodiment includes a coil assembly 53, a magnet assembly 54, and a helical spring 55 that provides a reciprocating elastic force between the coil assembly 53 and the magnet assembly 54.

[0078] The driving device of the fifth embodiment differs from that of the driving device of the first embodiment in that the intermediate magnetic conductor in the first embodiment is omitted. The coil assembly 53 of the fifth embodiment includes two coils 533: a first coil and a second coil. The magnetic conductor 534 of the coil assembly 53 includes a main magnetic conductor 534A and two side magnetic conductors 534C. The two side magnetic conductors 534C are respectively disposed on both sides of the two coils 533, and the free ends of the side magnetic conductors 534C extend into the lateral spaces on both sides of the permanent magnet 545. Both coils 533 are wrapped around the main magnetic conductor 534A, and the coils are longitudinally spaced apart.

[0079] Correspondingly, two pairs of permanent magnets 545 are provided in the magnet assembly 54, symmetrically distributed on both sides of the longitudinal axis L. The magnetic pole face of each pair of permanent magnets 545 is separated from a corresponding coil 533 by a transverse gap 56. The length of the permanent magnet 545 in the longitudinal axis L direction is basically equal to the length of the coil. In this way, most of the magnetic lines of force generated by the coil do not pass through the transverse gap 56, and correspondingly, do not pass through the permanent magnets 545.

[0080] Other structures in the fifth embodiment, such as the coil holding part of the coil assembly 53 and the magnet holding part (permanent magnet outer frame, magnetic conductive part 542) of the magnet assembly 54, are similar to those in the first embodiment and will not be described again here.

[0081] Sixth Embodiment

[0082] Figure 21 shows a perspective view of the main structure of the drive device according to a sixth embodiment of the present invention. The two pairs of permanent magnets 645 in the magnet assembly 64 and the coils 633 in the coil assembly of the drive device of the sixth embodiment are identical to those in the first embodiment. The difference is that the drive device of the sixth embodiment includes transverse magnetic guides extending from the magnetic guide portion 642 of the magnet assembly toward the dominant magnet 634A, namely two intermediate magnetic guides 634B and four side magnetic guides 642C. As can be seen from Figure 21, transverse magnetic guides are also present in the lateral spaces on both sides of the permanent magnets 645 to guide magnetic flux. The transverse magnetic guides extend substantially perpendicular to the longitudinal axis L. The side magnetic guides and intermediate magnetic guides have substantially the same transverse length. A coil magnetic field air gap 67A exists between the free end of the transverse magnetic guide and the dominant magnet, and the air gap 67A is smaller than the thickness of the permanent magnet 645.

[0083] When the transverse magnetic conductors are located on the magnet assembly, the length of the dominant magnet in the coil assembly along the longitudinal axis L is greater than or equal to the sum of the distance between the outer surfaces of the two side magnetic conductors along the longitudinal axis L and twice the allowable amplitude of the elastic element. The magnetic poles represented by the end faces of the linearly reciprocating transverse magnetic conductors 642C and 634B facing the dominant magnet 634A are perpendicular to the magnetic poles represented by the end face 634AD of the dominant magnet 634A perpendicular to the longitudinal axis L, effectively avoiding distortion between magnetic fields and preventing the generation of high-frequency electromagnetic forces.

[0084] Seventh Embodiment

[0085] Figure 22 shows a perspective view of the main structure of the drive device according to a seventh embodiment of the present invention. In this embodiment, lateral magnetic conductors, including side magnetic conductors 742C and intermediate magnetic conductors 734B, extend from the magnetic conductor portion 742 of the magnet assembly to move integrally with the magnet assembly. A portion of each of these lateral magnetic conductors extends in the lateral space on both sides of the permanent magnet 745. However, this portion of the lateral magnetic conductor is not aligned with the permanent magnet 145 along the direction parallel to the longitudinal axis, but is arranged in pairs. Specifically, at four positions at the front and rear ends of the paired magnetic conductor portions 742, a pair of spaced-apart side magnetic conductors 742C is provided at each position. Correspondingly, the main magnetic conductor 734A of the coil assembly has a flat magnetic surface of corresponding width, such that the free end of each side magnetic conductor 742 faces the magnetic surface of the main magnetic conductor 734A.

[0086] In the first to seventh embodiments, in order to keep the magnetic induction intensity from the permanent magnet in the transverse gap essentially constant, and to make the change in the magnitude of the Lorentz force follow only the change in the magnitude of the coil current, the length of the permanent magnet along the longitudinal axis is set to be greater than or equal to the sum of the length of the coil along the longitudinal axis L and twice the amplitude of the elastic element.

[0087] In the first to seventh embodiments, the electric toothbrush 1 may further include buffers 182, 282, 382, ​​482, and 582, as shown in FIG14. The buffers 182, 282, 382, ​​482, and 582 are disposed between the coil holding portion and a portion of the inner surface of the outer casing 21 along the longitudinal axis L. Specifically, a stepped portion is formed inside the outer casing of the handle 2, and the buffers are disposed between the inner surface of the stepped portion near the drive shaft and the end faces of the main supports 132, 232, 332, 432, and 532. The buffers 182, 282, 382, ​​482, and 582 absorb the impact of the reciprocating linear motion on the outer casing 21 of the handle 2, and also provide a seal between the outer casing 21 and the drive shaft.

[0088] Preferably, in an embodiment of the present invention, the brush head 7 is detachably attached to the outer handle 21 of the handle via a snap-fit ​​structure, and the transmission structure inside the brush head 7 cooperates with the drive shaft. Specifically, as shown in FIG14, the outer casing 21 has a groove 202 on the inner periphery of the end near the extension hole of the drive shaft, and the brush head 7 has a corresponding protrusion. Through the shape cooperation between the groove 202 and the protrusion, the brush head 7 is detachably connected to the outer casing 21.

[0089] On the other hand, in the first to seventh embodiments, on both sides of the longitudinal axis L, the magnetic pole faces of the paired permanent magnets are separated from the circumferential or end face of the coil by a transverse gap. The magnetic polarity of the magnetic pole faces of the paired permanent magnets facing the coil should be selected according to the direction of current flow in the coil portion they face. When the current flow directions of the coil portions on both sides are the same, the magnetic poles of the permanent magnets facing the coil on both sides are opposite; when the current flow directions of the coil portions on both sides are opposite, the magnetic poles of the permanent magnets facing the coil on both sides are the same. For example, for a coil wound around a magnetic conductor extending along the longitudinal axis L, the magnetic poles of the paired permanent magnets about the longitudinal axis L are the same, as in the first embodiment. In the second embodiment, for a coil wound around a magnetic conductor extending perpendicular to the longitudinal axis L, the magnetic pole polarities of the permanent magnets on the same side of the longitudinal axis L are opposite.

[0090] For the drive device according to the invention, the frequency of the coil drive current is close to (80%-120%) the natural frequency of the system composed of the elastic element and the magnet assembly, so that the Lorentz force generated by the current-carrying coil will drive the system to resonate.

[0091] In the first to sixth embodiments, the permanent magnet outer frame can also be removed, and the magnet holding part only includes the magnetically conductive parts 142, 242, 342, 442, 542, and 642. In other words, the magnet holding part is entirely formed of magnetically conductive material, and the magnetically conductive parts are then fixedly connected to the drive shafts 180, 280, 380, 480, and 580 and the support shafts 181, 281, 381, 481, and 581.

[0092] While the invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Any variations and modifications can be made by those skilled in the art without departing from the spirit and scope of the invention. Therefore, any modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the invention, without departing from the scope of the invention, fall within the protection scope defined by the claims of the invention.

Claims

1. A personal care device, comprising a housing and a drive mechanism disposed within the housing, the drive mechanism comprising: A coil assembly having a dominant magnet arranged along the longitudinal axis of a drive device, a coil, and a coil holding portion for holding the coil, the coil holding portion being fixed relative to the housing; A magnet assembly having a permanent magnet and a magnet holding portion for holding the permanent magnet, the magnet holding portion including a magnetically conductive portion, the magnet assembly being capable of linear reciprocating movement relative to the coil assembly along the longitudinal axis of the driving device. An elastic element acting between the coil assembly and the magnet assembly, the elastic element being arranged to apply an elastic force along the longitudinal axis direction. Its special feature is that, The driving device includes a transverse magnetic conductor arranged transversely to the longitudinal axis, at least a portion of which extends inside the magnet holding portion and in the lateral space of the permanent magnet on one or both sides along a direction parallel to the longitudinal axis. The permanent magnet is opposite to the coil and forms a transverse gap therebetween, and most of the magnetic lines of force generated by the coil do not pass through the transverse gap.

2. The personal care device of claim 1, wherein, The lateral magnetic conductor includes side magnetic conductors respectively disposed on both sides of the coil. The side magnetic conductors extend from one of the magnetic conductor portion of the magnet holding portion and the main magnet of the coil assembly, and extend close to the other of the magnetic conductor portion of the magnet holding portion and the main magnet of the coil assembly. The end face of the transverse magnetic conductor and the opposite magnetic conductor or the main magnetic conductor face form a coil magnetic field air gap, and the distance of the coil magnetic field air gap in the transverse direction is not greater than the thickness of the permanent magnet.

3. The personal care device of claim 1 or 2, wherein The permanent magnet includes a first permanent magnet and a second permanent magnet arranged along the longitudinal axis, with a longitudinal gap between the first and second permanent magnets. Each of the permanent magnets is opposite to the coil and forms a transverse gap therebetween. The transverse magnetic conductor also includes an intermediate magnetic conductor, a portion of which is inserted into the longitudinal gap.

4. The personal care device of claim 3, wherein the first and second electrodes are electrically connected to the controller. The coil assembly includes a first coil and a second coil, wherein the first permanent magnet and the second permanent magnet are respectively arranged opposite to the first coil and the second coil and are separated by a lateral gap; The first coil and the second coil are wound around the central magnetic conductor at a distance from each other on the main magnet. The central magnetic conductor is located between the first coil and the second coil, and the free end of the central magnetic conductor is inserted into the longitudinal gap.

5. The personal care device of claim 3, wherein the first and second electrodes are electrically connected to the controller. The coil assembly includes a first coil and a second coil, which are wound around the intermediate magnetic conductor and arranged on both sides of the dominant magnet. The first permanent magnet and the second permanent magnet are respectively opposite to the partial end faces of the coil on both sides of the intermediate magnetic conductor and separated by the transverse gap.

6. The personal care device of claim 1, wherein, The personal care device also includes a cushioning element disposed between the coil holder and a portion of the inner surface of the housing along the longitudinal axis. It also includes a drive shaft connected to the magnet holding portion of the magnet assembly, and a stepped portion is formed inside the housing. The coil holding part includes a coil bracket and a main bracket fixedly connected to the coil bracket. The buffer is disposed between the inner surface of the stepped part near the drive shaft and the end face of the main bracket, and seals the inner surface, the end face and the drive shaft.

7. The personal care device of claim 1, wherein the first and second electrodes are electrically coupled to the controller. The personal care device further includes a drive shaft and a support shaft, the drive shaft being fixedly connected to the support shaft, and the support shaft being fixedly connected to the magnet assembly. The coil holding part includes a coil support and a main support that is fixedly connected to the coil support. The support shaft is supported by the main bracket via a linear bearing or bushing.

8. The personal care device of claim 7, wherein the first and second electrodes are electrically connected to the controller. The support shaft includes a front support shaft and a rear support shaft, and the drive shaft is fixedly connected to the front support shaft, or the front support shaft and the drive shaft are integrally formed. The elastic element is a pair of helical springs, which are respectively sleeved on the front support shaft and the rear support shaft. Furthermore, the two ends of the helical spring respectively abut against the main support and the magnet holding part of the magnet assembly.

9. The personal care device of claim 1, wherein, The personal care device further includes a drive shaft and a support shaft, which are fixedly connected to the magnet holding part. The coil holding part includes a coil support and a main support that is fixedly connected to the coil support. The elastic element includes a leaf spring, one end of which is fixedly connected to the drive shaft or support shaft, and the other end of which is fixed to the main bracket.

10. The personal care device of claim 1, wherein, The magnet holding part further includes an outer frame, the magnetically conductive part is fixedly connected to the inner side of the outer frame, and the permanent magnet is fixedly connected to the inner side of the magnetically conductive part. The permanent magnets are arranged in pairs on both sides about the longitudinal axis, and the lateral gaps on both sides are substantially equal in size. The magnetic poles of the permanent magnets located on both sides of the longitudinal axis facing the coil are selected according to the direction of current flow in the coil portions on both sides. When the direction of current flow in the coil portions on both sides is the same, the magnetic poles of the permanent magnets facing the coil on both sides are opposite. When the direction of current flow in the coil portions on both sides is opposite, the magnetic poles of the permanent magnets facing the coil on both sides are the same.

11. The personal care device as claimed in claim 2, characterized in that, The length of the magnetic conductor of the magnet assembly and the other of the main magnets of the coil assembly along the longitudinal axis L is greater than or equal to the distance between the outer surfaces of the two side magnetic conductors along the longitudinal axis L plus twice the allowable amplitude of the elastic element.

12. The personal care device of claim 1, wherein, The permanent magnet forms a magnetic pole on a surface that extends parallel to the longitudinal axis, and the portion of the magnetic conductor with the coil wound around it also extends parallel to the longitudinal axis. The length of the permanent magnet along the longitudinal axis is greater than or equal to the sum of the length of the coil along the longitudinal axis and twice the amplitude of the elastic element. The permanent magnets are arranged in pairs on both sides of the longitudinal axis, and the transverse gap is substantially equal along the longitudinal axis.

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