Electric toothbrush and design method thereof

Abstract

The invention provides an electric toothbrush and a design method thereof.The electric toothbrush comprises a support, a driving frame and a motor, the support is provided with a hollowed-out part, the driving frame is elastically connected to the support through an elastic arm, the driving frame is located in the hollowed-out part, the driving frame and the support are spaced, and the upper end of the driving frame is provided with a tenon joint piece used for being connected with a toothbrush head; the motor is arranged on the driving frame, an output shaft of the motor is connected with a vibratory hammer, the motor can rotate to drive the driving frame to swing or vibrate relative to the bracket, so that the tenon joint piece can drive the toothbrush head to swing or vibrate, and the effective length of the elastic arm is # imgabs0 #, h represents the height of the cross section of the elastic arm, and k represents the total rigidity coefficient of the elastic arm.

Description

Technical Field

[0001] The present invention relates to the technical field of electric toothbrushes, and in particular to an electric toothbrush and a design method thereof. Background Art

[0002] Existing electric toothbrushes generally use eccentric vibration motors to vibrate the toothbrush head. The drive mechanism is large in size, complex in structure, and high in cost. In addition, the brush handle vibrates strongly, the noise is loud, the vibration output to the toothbrush head is greatly attenuated, and the energy consumption is high. Summary of the invention

[0003] The inventors found that the vibration can be transmitted to the toothbrush head through the elastically connected lever, but there is still room for optimization in the vibration frequency, amplitude and force design of the toothbrush head.

[0004] The present application aims to propose a design method for an electric toothbrush, which optimizes the parameters of the elastic arm so that the toothbrush head can vibrate efficiently and achieve the expected cleaning effect.

[0005] The embodiment of the present application provides a design method for an electric toothbrush, wherein the electric toothbrush comprises a bracket, a driving frame and a motor, wherein the bracket is provided with a hollow portion.

[0006] The driving frame is elastically connected to the bracket through an elastic arm, the driving frame is located in the hollow part, the driving frame and the bracket are spaced apart, the upper end of the driving frame has a joint for connecting a toothbrush head, the motor is arranged on the driving frame, the output shaft of the motor is connected to a vibrating hammer, the rotation of the motor can drive the driving frame to swing or vibrate relative to the bracket, so that the joint can drive the toothbrush head to swing or vibrate,

[0007] The effective length of the elastic arm is:

[0008] Wherein, E represents the bending modulus of the elastic arm, b represents the cross-sectional width of the elastic arm, h represents the cross-sectional height of the elastic arm, and k represents the total stiffness coefficient of the elastic arm.

[0009] In at least one possible embodiment, the centrifugal force generated by the vibration hammer is F1,

[0010] F1=X(k-Mω 2 )

[0011] Wherein, M represents the total mass of the joint, the motor, the vibrating hammer, the driving frame and the toothbrush head connected to the joint, X represents the amplitude of the toothbrush head, and ω represents the angular velocity of the motor rotation.

[0012] In at least one possible embodiment, the centrifugal force generated by the vibration hammer is F1,

[0013] F1=meω 3

[0014] Wherein, m represents the mass of the vibration hammer, e represents the eccentricity of the vibration hammer, and ω represents the angular velocity of the motor rotation.

[0015] In at least one possible embodiment, the mortise and tenon is connected to a connecting portion, the mortise and tenon is connected to the elastic arm via the connecting portion, the connecting portion surrounds the mortise and tenon, the connecting portion has a movable fulcrum, and a distance L1 from the movable fulcrum to the end of the toothbrush head is greater than a distance L2 from the movable fulcrum to the vibrating hammer.

[0016] In at least one possible implementation, the centrifugal force generated by the vibration hammer is F1, and the force output by the toothbrush head is F2, wherein L1=L2×(F2 / F1).

[0017] In at least one possible implementation, the width of the cross section of the elastic arm along the front-to-rear direction of the electric toothbrush is greater than the height of the cross section of the elastic arm along the left-to-right direction of the electric toothbrush.

[0018] In at least one possible implementation, the flexural modulus of the elastic arm is 5000 MPa to 10000 MPa.

[0019] The embodiment of the present application further proposes an electric toothbrush, which is designed using the design method of an electric toothbrush described in any one of the above technical solutions.

[0020] In at least one possible embodiment, the driving frame and the bracket are connected via a connecting portion and an elastic arm, the connecting portion is connected to the mortise and tenon piece, and in the left and right directions of the electric toothbrush, the elastic arm is located on the left and right sides of the connecting portion, and the elastic arm as a whole is in the shape of a sheet extending along the up and down directions and the front and back directions of the electric toothbrush.

[0021] In at least one possible implementation, the joint, the connecting portion, the elastic arm and the bracket are integrally formed.

[0022] By adopting the above technical solution and rationally designing the size of the elastic arm, the toothbrush head can vibrate efficiently, realize the expected movement characteristics, and achieve a better cleaning effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 An exploded view showing a partial structure of an electric toothbrush according to an embodiment of the present application.

[0024] Figure 2A cross-sectional view of a handle of an electric toothbrush according to an embodiment of the present application is shown.

[0025] Figure 3 A cross-sectional view of a handle of an electric toothbrush according to an embodiment of the present application is shown.

[0026] Figure 4 A front view of a bracket and a driving frame of an electric toothbrush according to an embodiment of the present application is shown.

[0027] Description of Reference Numerals

[0028] 1 bracket 11 battery 12 circuit board 13 hollow part 14 waterproof ring 15 waterproof ring installation hole

[0029] 2 driving frame 21 joint 22 motor slot 23 counterweight slot 24 elastic arm 25 connecting portion 26 shock absorber mounting slot 27 first fixed fulcrum 28 second fixed fulcrum 29 moving fulcrum

[0030] 3 Counterweight

[0031] 4 Pressure sensor switch

[0032] 5 motor 51 eccentric block

[0033] 6 Shock absorbers

[0034] 7 Tenon

[0035] AUp and down direction FForward and backward direction RLeft and right direction DETAILED DESCRIPTION

[0036] In order to more clearly explain the above-mentioned purposes, features and advantages of the present application, the specific implementation methods of the present application are described in detail in this section in conjunction with the accompanying drawings. In addition to the various implementation methods described in this section, the present application can also be implemented in other different ways. Without violating the spirit of the present application, those skilled in the art can make corresponding improvements, deformations and substitutions, so the present application is not limited by the specific embodiments disclosed in this section. The scope of protection of the present application shall be subject to the claims.

[0037] In the following description, the up-down direction A of the electric toothbrush indicates the direction in which the axis of the electric toothbrush extends, wherein the upper side indicates the side where the toothbrush head is located, and the lower side indicates the side where the brush handle is located. The front-to-back direction F of the electric toothbrush indicates the direction in which the bristles of the toothbrush head of the electric toothbrush extend, wherein the front side indicates the side toward which the bristles face, and the rear side indicates the side away from which the bristles face. The left-right direction R of the electric toothbrush is perpendicular to both the up-down direction A and the front-to-back direction F of the electric toothbrush.

[0038] like Figures 1 to 4As shown, the embodiment of the present application provides an electric toothbrush, which includes a brush handle and a toothbrush head (not shown), and the brush handle includes a main body 100, a bracket 1, a driving frame 2, a counterweight 3, a pressure sensing switch 4, a motor 5, a shock absorber 6 and a tenon 7. The bracket 1, the driving frame 2, the counterweight 3, the pressure sensing switch 4, the motor 5 and the shock absorber 6 can be arranged inside the main body 100, and the tenon 7 extends from the main body 100 for connecting the toothbrush head. The toothbrush head can be detachably connected to the tenon 7.

[0039] The bracket 1 can be used to install or fix other components such as a battery 11 and a circuit board 12. The bracket 1 can be provided with a hollow portion 13, which can be located in the middle position in the left-right direction R of the electric toothbrush, and can pass through the front-to-back direction F of the electric toothbrush.

[0040] The pressure sensing switch 4 can be connected to the circuit board 12. The pressure sensing switch 4 is used to control the switch of the electric toothbrush. The pressure sensing switch 4 allows the user to conveniently control the opening and closing of the electric toothbrush, thereby improving the convenience of user operation and the use experience.

[0041] The driving frame 2 may include a motor slot 22, and the motor 5 is accommodated in the motor slot 22. A joint 21 may be connected to the upper side of the driving frame 2. In the up-down direction A of the electric toothbrush, the joint 21 may be located on the upper side of the motor slot 22. The joint 21 may be cylindrical and fixedly connected to the tenon 7. The tenon 7 is used to connect the toothbrush head. The tenon 7 may be made of metal material.

[0042] The output shaft of the motor 5 is connected to a vibrating hammer 51, which may be cylindrical, and the axis of the vibrating hammer 51 is staggered with the axis of the motor, so that when the motor 5 drives the vibrating hammer 51 to rotate, a centripetal force can be generated to drive the drive frame 2 to swing or vibrate. Optionally, the distance (i.e., the eccentricity e) between the axis of the vibrating hammer 51 and the axis of the motor can be 0.9 mm.

[0043] The drive frame 2 and the bracket 1 can be elastically connected through the elastic arm 24, and the drive frame 2 can be located in the hollow portion 13, and the drive frame 2 is spaced apart from the bracket 1 as a whole. The motor 5 (and the vibration hammer 51) can be connected to the drive frame 2, and the vibration of the motor 5 can drive the drive frame 2 to swing or vibrate relative to the bracket 1, and then the swing or vibration is transmitted to the tenon 21. By making the drive frame 2 and the bracket 1 elastically connected and spaced apart as a whole, the toothbrush head connected to the tenon 7 can have a certain degree of freedom of movement, so that the toothbrush head can be subjected to forces in different directions, so as to better clean the teeth and massage the gums.

[0044] Specifically, the driving frame 2 can be elastically connected to the bracket 1 through the tenon joint 21, the connecting portion 25 and the elastic arm 24. The connecting portion 25 can be connected to the tenon joint 21, and the connecting portion 25 can be in the form of a sheet. The elastic arm 24 is generally in the form of a sheet extending along the up-down direction A and the front-back direction F of the electric toothbrush. The two ends of the elastic arm 24 can be bent and respectively connected to the connecting portion 25 and the bracket 1. The connecting portion 25 can surround the tenon joint 21. The tenon joint 21 can be connected to the elastic arm 24 through the connecting portion 25, and the connecting portion 25 can be connected to the bracket 1 through two elastic arms 24, and the elastic arms 24 can be located on the left and right sides of the connecting portion 25 in the left-right direction R. The dimensions of the connecting portion 25 and the elastic arm 24 along the front-back direction F can be the same. The connecting portion 25 and the elastic arm 24 can be formed in a U shape, and the connecting portion 25 forms the bottom of the U, and the elastic arm 24 includes two elastic sheets to form two arms of the U. In the up-down direction A, the connecting portion 25 can be located at the lower end of the elastic arm 24. The elastic sheet may be in a sheet shape extending in the up-down direction A and the front-rear direction F.

[0045] It can be understood that in other possible implementations, the elastic arms may also be located at the front and rear sides of the connecting portion 25 in the front-to-rear direction.

[0046] There is a gap between the joint 21 and the elastic arm 24. The joint 21 is located between the two elastic sheets. The interval between the joint 21 and the elastic sheet may be 0.5 to 1 mm.

[0047] The elastic arm 24 can be arranged on the left and right sides of the connecting portion 25 in the left-right direction R. The elastic arm 24 can be a bendable sheet, and the dimension (width b) of the sheet-shaped elastic arm 24 in the front-to-back direction can be greater than the dimension (height h) in the left-to-right direction. Here, the dimension (height h) of the sheet-shaped elastic arm 24 in the left-to-right direction does not include the dimension of the interval between the two elastic arms 24, that is, it refers to the thickness of the two elastic arms 24 entities. As a result, the elastic arm is easy to bend and deform along the left-to-right direction R of the electric toothbrush, but not easy to bend and deform along the front-to-back direction F of the electric toothbrush (still able to deform). In this way, the driving frame 2 can easily swing in the left-to-right direction relative to the bracket 1, thereby driving the toothbrush head to swing or vibrate in the left-to-right direction R, thereby cleaning the teeth and / or gums.

[0048] It can be understood that the tenon 7, the joint 21 and the driving frame 2 can be regarded as a rigid rod, and the rigid rod can be used as a lever through the connection between the elastic arm 24 and the bracket 1. Two elastic arms 24 can be provided, and the two elastic arms 24 can be provided on opposite sides of the driving frame 2. The connection part between the two elastic arms 24 and the bracket 1 can be used as the fulcrum of the lever (the first fixed fulcrum 27 and the second fixed fulcrum 28). When the lever swings relative to the bracket 1, the positions of the first fixed fulcrum 27 and the second fixed fulcrum 28 are fixed relative to the bracket 1.

[0049] The joint 21 may have a movable fulcrum 29. It is understood that the fulcrum is a virtual position defined artificially, and is not a support point existing in the structure. When the motor 5 drives the lever to swing relative to the bracket 1, the position of the movable fulcrum 29 moves relative to the bracket 1.

[0050] The vibration system composed of the bracket 1, the driving frame 2, the mortise and tenon 21, the connecting part 25, the tenon 7, the toothbrush head and the elastic arm 24 can be simplified as a single-degree-of-freedom vibration system. The driving frame 2, the mortise and tenon 21, the connecting part 25, the tenon 7, the toothbrush head, the motor, the vibrating hammer, etc. are equivalent to a lever with a concentrated mass of M (approximately 2g in this application), the two elastic arms 24 can provide spring characteristics, the two elastic arms 24 have an equivalent stiffness k, and the vibrating hammer 51 driven by the motor can provide an excitation force F(t), which is a force acting on the single-degree-of-freedom vibration system by an external excitation that varies with time. The bending modulus of the elastic arm 24 can be 5000 MPa to 10000 MPa.

[0051] A single degree of freedom vibration system can be described by a spring-mass-damper system model:

[0052]

[0053] Among them, c is the damping coefficient of the system, which is approximately zero and can be ignored. represents acceleration, that is, the rate of change of velocity with respect to time in a single-degree-of-freedom vibration system. represents velocity, that is, the rate of change of displacement in a single-degree-of-freedom vibration system with respect to time, and x represents displacement, that is, the instantaneous offset of the single-degree-of-freedom vibration system relative to the equilibrium position, which is a function of time t.

[0054] The amplitude X of the toothbrush head can be estimated by a simplified formula of a spring-mass-damper system. The amplitude X can be expressed by the following formula:

[0055]

[0056] Among them, F1 represents the centrifugal force generated by the vibration hammer, k represents the equivalent stiffness of the elastic arm, ω represents the angular velocity of the motor rotation, and ωn represents the natural frequency of the vibration system.

[0057]

[0058] The centrifugal force generated by the vibration hammer 51 is F1, and the force output by the toothbrush head is F2.

[0059] F1=meω 3 =X(k-Mω 2 ).

[0060] Equivalent stiffness of the elastic arm

[0061] Wherein, m represents the mass of the vibrating hammer 51, e represents the eccentricity of the vibrating hammer 51, and ω represents the angular velocity of the motor. ω=2πf, where f represents the frequency of the motor, that is, the number of revolutions per second. For example, if the motor speed is 18,000 revolutions per minute (rpm), the motor rotation frequency is 300 Hz, and the angular velocity of the motor may be 600π. arm is the stiffness coefficient of a single elastic arm, E is the bending modulus of the elastic arm; I is the second moment of the cross section of the elastic arm; Ls is the length of the elastic arm.

[0062] For example, m can be 0.75 grams, e can be 0.9 millimeters, then F1 = 2.396 Newtons.

[0063] The second moment of cross section of the elastic arm

[0064] b represents the cross-sectional width of the elastic arm (the dimension along the front-to-back direction F), and h represents the cross-sectional height of the elastic arm (the dimension along the left-to-right direction R). The cross-sectional width b of the elastic arm is different from the cross-sectional height h of the elastic arm. The cross-sectional width b of the elastic arm is greater than the cross-sectional height h of the elastic arm. In this embodiment, b can be 9.5 mm, h can be 1.4 mm, and the second moment I of the cross-sectional area of ​​the elastic arm can be 2.17×10 －12 , the bending modulus of the elastic arm can be 9.6×10 9 In this way, the elastic arm 24 can drive the joint 21 to vibrate in an elliptical shape, and further drive the toothbrush head to perform high-frequency cleaning motion.

[0065]

[0066]

[0067] The effective length of the elastic arm 24 is: When designing the specific structure of the elastic arm 24, the effective length of the elastic arm 24 can be calculated according to the above formula. For example, Ls can be 4.5 mm. Specifically, according to actual needs, the amplitude X of the toothbrush head, the angular velocity ω of the motor rotation, the mass m of the vibrating hammer 51, the eccentricity e of the vibrating hammer 51, and the bending modulus E of the elastic arm 24 can be first determined. In this way, F1=meω^3=X(k-Mω 2 ), the equivalent stiffness k of the elastic arm 24 is calculated, and then the effective length and cross-sectional area (including the cross-sectional height h and the cross-sectional width b) of the elastic arm 24 are determined.

[0068] The distance from the movable fulcrum 29 to the end of the toothbrush head is L1, and the distance from the movable fulcrum 29 to the vibrating hammer 51 is L2. L1 is greater than L2, so that the structure of the electric toothbrush can be compact.

[0069] Specifically, L1 = L2 x (F2 / F1). For example, according to the cleaning requirement, F2 can be 0.64 Newtons, and according to the size of the toothbrush head, L2 can be 80 mm, so L1 can be calculated to be 21.5 mm.

[0070] It can be understood that the cross-sectional area of ​​the elastic arm 24 affects the second moment of section I of the elastic arm 24. When the second moment of section I increases, the rigidity of the elastic arm 24 increases, thereby reducing the amplitude of the toothbrush head (tenon 7), which is suitable for delicate cleaning. When the second moment of section I decreases, the rigidity of the elastic arm 24 decreases, thereby increasing the amplitude of the toothbrush head (tenon 7), which is suitable for strong cleaning.

[0071] The effective length Ls of the elastic arm 24 increases, so that the rigidity of the elastic arm 24 decreases, thereby increasing the amplitude of the toothbrush head (tenon 7), which is suitable for strong cleaning. The effective length Ls of the elastic arm 24 decreases, so that the rigidity of the elastic arm 24 increases, thereby reducing the amplitude of the toothbrush head (tenon 7), which is suitable for delicate cleaning.

[0072] That is to say, the size of the elastic arm 24 directly affects the amplitude of the toothbrush head (tenon 7). The present application can calculate the effective length Ls of the elastic arm 24 when the cross-sectional area of ​​the elastic arm 24 is known according to actual needs, or can calculate the cross-sectional area of ​​the elastic arm 24 when the effective length Ls of the elastic arm 24 is known.

[0073] Optionally, in this embodiment, the joint 21, the elastic arm 24, the connecting portion 25 and the bracket 1 can be integrally formed, so that the overall structural strength and stability of the bracket 1 and the driving frame 2 are higher.

[0074] Optionally, the driving frame 2 may be provided with a counterweight slot 23, the counterweight slot 23 may be located on the upper side of the motor slot 22, and the counterweight 3 may be accommodated in the counterweight slot 23. In the up-down direction A of the electric toothbrush, the vibrating hammer 51 may be located on the lower side of the motor 5, and the counterweight 3 may be located on the upper side of the motor 5. The counterweight 3 may increase the overall weight of the driving frame 2, balance the vibration generated when the motor is running, avoid imbalance caused by vibration, keep the electric toothbrush stable during use, and make the movement of the toothbrush head more stable and efficient.

[0075] For example, two waterproof ring mounting holes 15 may be provided at the upper end of the bracket 1, and the two waterproof ring mounting holes 15 may be provided on the left and right sides of the joint 21 in the left-right direction R of the electric toothbrush. The waterproof ring mounting holes 15 may be used to connect the waterproof ring 14. The waterproof ring 14 is used to prevent water or foam from entering the interior of the main body 100.

[0076] The shock absorber 6 can be connected to the driving frame 2, and at least a part of the shock absorber 6 is located in the gap between the driving frame 2 and the bracket 1. The shock absorber 6 is elastic, for example, the shock absorber 6 can be rubber. When the driving frame swings or vibrates, the shock absorber 6 can effectively absorb and alleviate the vibration transmitted to the bracket 1, reduce the vibration intensity transmitted to the user's hand, and improve the comfort of use. For example, the shock absorber 6 can be installed on the driving frame 2 along the front-to-back direction F, and the size of the shock absorber 6 along the left-right direction R is greater than the size of the driving frame 2 along the left-right direction R, so that a part of the shock absorber 6 is located in the gap between the driving frame 2 and the bracket 1.

[0077] The vibration buffering member 6 can protect the motor 5 and other components, and can also reduce the noise generated when the motor 5 is running, making the electric toothbrush quieter during use and improving the user experience. In addition, the shock absorber 6 can also buffer external impacts, reduce damage caused by falling, and extend the service life of the electric toothbrush.

[0078] Further, the driving frame 2 may be provided with a shock absorbing member installation groove 26, and the shock absorbing member 6 may be installed in the shock absorbing member installation groove 26. In the up-down direction A of the electric toothbrush, the shock absorbing member installation groove 26 may be provided at the lower side of the motor groove 22, and the shock absorbing member 6 may be provided at the lower side of the motor 5.

[0079] When using the electric toothbrush of the present application, the user can turn on the electric toothbrush through the induction switch 4, turn on the power, and start the motor 5 to rotate. The motor 5 drives the eccentric block 51 to rotate, so that the drive frame 2 swings or vibrates with the fulcrum as the axis, and transmits power to the tenon 21, so that the toothbrush head can swing or vibrate in multiple directions through the tenon 7. The drive frame 2 and the toothbrush head are respectively located at the two ends of the fulcrum. The lever principle is used to amplify the swing or vibration of the drive frame 2 at the bristle position of the toothbrush head. This swing or vibration can effectively clean the tooth surface and hard-to-reach areas, and improve the brushing effect.

[0080] It should be understood that at least some aspects or features of the above-mentioned implementation modes, embodiments or examples may be appropriately combined.

[0081] It is understood that in the present application, when the number of parts or components is not particularly limited, the number may be one or more, and the multiple here means two or more. For the case where the number of parts or components shown in the drawings and / or described in the specification is a specific number such as two, three, four, etc., the specific number is usually exemplary and not restrictive, and it can be understood as multiple, that is, two or more, but this does not mean that the present application excludes the case of one.

[0082] In the present application, unless otherwise clearly stated or limited, the terms such as "install", "assemble", "assemble", "connect", "connect", "couple", "link", "abut", "connect", "interconnect", "intercommunication", "conduction", "fixation", "fastening" and the like should be understood in a broad sense, for example, they can be direct or indirect. For example, regarding connection, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly stated or limited. For example, regarding connectivity / conduction, it can be direct connectivity / conduction, or it can be indirect connectivity / conduction via an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to the specific circumstances.

[0083] In the present application, unless otherwise clearly stated or limited, a component disposed on / installed on / located on / accommodated on / placed in, within, inside, etc. another component may be any of the following two situations: a part or most of the one component is located in the other component; and the one component is completely accommodated in the other component.

[0084] Although the present application is described in detail using the above-mentioned embodiments, it is obvious to those skilled in the art that the present application is not limited to the embodiments described in this specification. The present application can be modified and implemented as a modified embodiment without departing from the subject matter and scope of the present application as determined by the claims. Therefore, the description in this specification is for the purpose of illustration and does not have any restrictive meaning for the present application.

Claims

1. A method for designing an electric toothbrush, characterized in that: The electric toothbrush comprises a bracket (1), a driving frame (2) and a motor (5); the bracket (1) is provided with a hollow portion (13). The driving frame (2) is elastically connected to the bracket (1) via an elastic arm (24); the driving frame (2) is located in the hollow portion (13); the driving frame (2) and the bracket (1) are spaced apart; the upper end of the driving frame (2) has a joint (21) for connecting a toothbrush head; the motor (5) is arranged on the driving frame (2); the output shaft of the motor (5) is connected to a vibration hammer (51); the rotation of the motor (5) can drive the driving frame (2) to swing or vibrate relative to the bracket (1), so that the joint (21) can drive the toothbrush head to swing or vibrate; The effective length of the elastic arm (24) is: Wherein, E represents the bending modulus of the elastic arm (24), b represents the cross-sectional width of the elastic arm (24), h represents the cross-sectional height of the elastic arm (24), and k represents the total stiffness coefficient of the elastic arm (24).

2. The design method of an electric toothbrush according to claim 1, characterized in that: The centrifugal force generated by the vibration hammer (51) is F1, F1=X(k-Mω 2 ) Wherein, M represents the total mass of the joint (21), the motor (5), the vibrating hammer (51), the driving frame (2) and the toothbrush head connected to the joint (21), X represents the amplitude of the toothbrush head, and ω represents the angular velocity of the motor rotation.

3. The design method of an electric toothbrush according to claim 1, characterized in that: The centrifugal force generated by the vibration hammer (51) is F1, F1=meω 3 Wherein, m represents the mass of the vibration hammer (51), e represents the eccentricity of the vibration hammer (51), and ω represents the angular velocity of the rotation of the motor (5).

4. The design method of an electric toothbrush according to claim 1, characterized in that: The mortise and tenon joint (21) is connected to a connecting portion (25), the mortise and tenon joint (21) is connected to the elastic arm (24) via the connecting portion (25), the connecting portion (25) surrounds the mortise and tenon joint (21), the connecting portion (25) has a movable fulcrum (29), and a distance L1 from the movable fulcrum (29) to the end of the toothbrush head is greater than a distance L2 from the movable fulcrum (29) to the vibration hammer.

5. The design method of an electric toothbrush according to claim 4, characterized in that: The centrifugal force generated by the vibration hammer (51) is F1, and the force output by the toothbrush head is F2, wherein L1=L2×(F2 / F1).

6. The design method of an electric toothbrush according to claim 1, characterized in that: The width of the cross section of the elastic arm (24) along the front-to-back direction (F) of the electric toothbrush is greater than the height of the cross section of the elastic arm (24) along the left-to-right direction (R) of the electric toothbrush.

7. The design method of an electric toothbrush according to claim 1, characterized in that: The bending modulus of the elastic arm (24) is 5000 MPa to 10000 MPa.

8. An electric toothbrush, characterized in that: The electric toothbrush is designed using the design method for an electric toothbrush according to any one of claims 1 to 7.

9. The electric toothbrush according to claim 8, characterized in that: The driving frame (2) and the bracket (1) are connected via a connecting portion (25) and an elastic arm (24); the connecting portion (25) is connected to the joint (21); in the left-right direction (R) of the electric toothbrush, the elastic arm (24) is located on the left and right sides of the connecting portion (25); the elastic arm (24) is generally in the shape of a sheet extending along the up-down direction (A) and the front-back direction (F) of the electric toothbrush.

10. The electric toothbrush according to claim 9, characterized in that: The joint piece (21), the connecting portion (25), the elastic arm (24) and the bracket (1) are integrally formed.

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