WO2006004316A1

WO2006004316A1 - Brushhead for an electric toothbrush

Info

Publication number: WO2006004316A1
Application number: PCT/KR2005/001278
Authority: WO
Inventors: Dae-Sung Wang; Ki-Seob Kim; Heon-Young Park; Sung-Jin Kim; Sang-Tae Eun
Original assignee: Lg Household & Health Care Ltd.
Priority date: 2004-07-06
Filing date: 2005-05-03
Publication date: 2006-01-12
Also published as: KR100591396B1; KR20060003497A

Abstract

The present invention provides a brushhead for an electric toothbrush which includes a toothbrush head housing (1) having both a bristle holder mounting part (101) and a hollow neck part (102), a bristle holder (2) which is mounted to the bristle holder mounting part (101), and a rotating drive shaft (3) which is inserted into the hollow neck part (102), with an eccentric shaft (301) provided on an end of the rotating drive shaft (3). The bristle holder (2) has an arm rotating shaft (203) which protrudes from each of opposite sides of an arm support (201), and an arm (202) which is coupled to the arm rotating shafts (203), with an eccentric shaft coupling hole (204) provided in the arm (202). An end of the eccentric shaft (301) is jointed to the eccentric shaft coupling hole (204), so that the drive force is transmitted to the bristle holder (2) by revolution of the eccentric shaft (301). In the present invention, a bristle holder for an electric toothbrush rotationally vibrates at high torque, thus enhancing cleaning ability. Furthermore, bristles of the bristle holder can vibrates at high frequency due to forward and backward vibration of an eccentric shaft and vibration amplifying action of a coil spring, thus efficiently removing plague from teeth. In addition, even when the motion of the bristle holder is stopped, both a rotating drive shaft and an output shaft of a drive motor, which is coupled to the rotating drive shaft, rotate smoothly. Accordingly, current consumption due to overload of the drive motor is prevented, so that the present invention makes it possible to use the electric toothbrush for a long time.

Description

BRUSHHEAD FOR AN ELECTRIC TOOTHBRUSH Technical Field

[1] The present invention relates, in general, to brushheads for electric toothbrushes and, more particularly, to a brushhead for an electric toothbrush which has a link structure capable of reducing loss of power transmitted from a drive motor to a bristle holder, so that a high torque is transmitted to the bristle holder despite a relatively low number of revolutions per minute (torque) of the drive motor, thus enhancing cleaning ability, and in which one or more coil springs are fitted over a rotating drive shaft, thus amplifying vibration of the brushhead while brushing teeth, thus enhancing cleaning ability. Background Art

[2] Cleaning ability of an electric toothbrush depends on both the frequency of vibrations and the torque of a bristle holder, which rotationally vibrates. In other words, if the frequency of rotational vibrations and the torque are high, the electric toothbrush has superior cleaning ability. However, an electric toothbrush having an ex¬ cessively high frequency of rotational vibrations may injure the user's gums.

[3] Generally, an electric toothbrush has a direct current (D.C.) motor serving as a drive force generating means. In the case of a direct current motor, to increase the torque transmitted to the bristle holder of a brushhead of an electric toothbrush, the direct current motor must have a high number of revolutions per minute (rpm). As such, the high rpm increases the frequency of rotational vibrations. As a result, while brushing teeth, the teeth may be damaged. To prevent this, an electric toothbrush, which uses a reduction gear to increase the torque and reduce the frequency of rotational vibrations of a bristle holder, was proposed and has been used.

[4] FIG. 12 shows a power transmission structure of a conventional electric toothbrush which reduces a rotational frequency and increases torque using a reduction gear 404. As shown in the drawing, the conventional power transmission structure reduces the rpm of a drive motor 405 using reduction gears 404 while increasing the torque. The increased torque is transmitted to a bristle holder 402 having a movement guide hole 407 through an eccentric shaft 408 mounted to the end of a rotating drive shaft 403. Thus, the bristle holder 402 rotationally vibrates around a rotating shaft 406. Disclosure of Invention Technical Problem

[5] However, in this conventional structure, to prevent the bristle holder 402 from being stopped by outside pressure (pressure which is applied from the bristle holder to tooth surfaces), that is, to rotationally vibrate the bristle holder 402 at high torque and to increase the number of vibrations, the drive motor 405 must have high revolutions per minute. Furthermore, the use of the reduction gear 404 complicates the structure and increases the manufacturing costs of the electric toothbrush. Moreover, due to damage to the reduction gear 404, mechanical trouble may frequently occur to electric toothbrushes. As well, the reduction gear makes it difficult to miniaturize the electric toothbrush. In addition, noise occurs due to the high rpm of the drive motor and the gear mechanism. Technical Solution

[6] Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a brushhead for an electric toothbrush which has an efficient power transmission structure, so that a bristle holder of the brushhead rotationally vibrates at high torque despite a relatively low number of revolutions per minute (torque) of a drive motor.

[7] Another object of the present invention is to provide a brushhead for an electric toothbrush which has a structure capable of amplifying vibration of the drive motor, a central shaft and the brushhead such that bristles of the bristle holder can vibrate at high frequency, thus efficiently removing plagues from teeth.

[8] In an aspect, the present invention provides a brushhead for an electric toothbrush, including: a bristle holder 2 rotationally vibrating within a predetermined angular range due to the revolution of an eccentric shaft 301 coupled to an end of a rotating drive shaft 3, with bristles set in the bristle holder. The eccentric shaft 301 is jointed to an arm 202 which is spaced apart from a rotating shaft 205 of the bristle holder 2 by a predetermined distance and is shafted to the bristle holder 2 in a direction per¬ pendicular to the rotating shaft 205.

[9] The eccentric shaft 301 may have a spherical shape at an end thereof, and the arm

202 may include an eccentric shaft coupling hole 204 provided in an end of the arm 202, so that the end of the eccentric shaft 301 is inserted into the eccentric shaft coupling hole 204, and forms a pivot joint structure.

[10] The eccentric shaft 301 may have a spherical shape at an end thereof, and the arm

202 may include a spherical eccentric shaft coupling hole 204 provided in an end of the arm 202, so that the end of the eccentric shaft 301 is inserted into the eccentric shaft coupling hole 204, and forms a ball-socket joint structure.

[11] The rotating drive shaft 3 may be elastically supported in a hollow neck part 102 of a toothbrush head housing 1 such that the eccentric shaft 301 pushes the arm 202.

[12] The rotating drive shaft 3 may include: a spring support 306 fitted over the rotating drive shaft 3 and fastened to the hollow neck part 102; and a coil spring 303, 305 fitted over the rotating drive shaft 3, so that a repulsive power of the coil spring 303, 305 is transmitted to the arm 202 through the eccentric shaft 301 provided on an eccentric shaft support 302.

[13] In another aspect, the present invention provides a brushhead for an electric toothbrush, including: a toothbrush head housing 1 integrally having both a bristle holder mounting part 101 and a hollow neck part 102; a bristle holder 2 mounted to the bristle holder mounting part 101 and rotationally vibrating around a rotating shaft 205 thereof, with bristles set in the bristle holder 2; and a rotating drive shaft 3 inserted into the hollow neck part 102 of the toothbrush head housing 1, with an eccentric shaft 301 provided on an end of the rotating drive shaft 3, so that the rotating drive shaft 3 revolves the eccentric shaft 301 using a rotational drive force transmitted from a drive motor. The bristle holder 2 includes: an arm rotating shaft 203 protruding from each of opposite sides of an arm support 201, which extends downwards, in a radial direction with respect to the rotating shaft 205; and an arm 202 having a U- shape and coupled to the arm rotating shafts 203, with an eccentric shaft coupling hole 204 provided at a predetermined position in the arm 202 toward the eccentric shaft 301. An end of the eccentric shaft 301 is jointed to the eccentric shaft coupling hole 204, so that a drive force is transmitted to the bristle holder 2 by revolution of the eccentric shaft 301.

[14] The eccentric shaft 301 may have a spherical shape at an end thereof, and the arm

[15] The eccentric shaft 301 may have a spherical shape at an end thereof, and the arm

[16] The rotating drive shaft 3 may be elastically supported by a coil spring 303, 305 which is provided between a spring support 306, fitted over the rotating drive shaft 3 and fastened in the hollow neck part 102 of the toothbrush head housing 1, and an eccentric shaft support 302 which is provided on the end of the rotating drive shaft 3 and on which the eccentric shaft 301 is provided.

[17] The coil spring may comprise two coil springs 303 and 305 which are provided between the eccentric shaft support 302 and the spring support 306 and are spaced apart from each other by a spring spacing unit 304 fitted over the rotating drive shaft 3.

[18] The arm support 201 of the bristle holder 2 may be provided with an arc- shaped groove 208 at a predetermined position opposite to the eccentric shaft 301, and a pin 104 is fitted into the bristle holder mounting part 101 and reaches the groove 208, so that the bristle holder 2 is prevented from being removed. [19] The arm support 201 of the bristle holder 2 may be provided with a spring seat 207 which has a cylindrical shape, with a support spring 206 seated in the spring seat 207, so that the bristle holder 2 is elastically supported against the bristle holder mounting part 101. Advantageous Effects

[20] In the present invention, a bristle holder for an electric toothbrush rotationally vibrates at high torque, thus enhancing cleaning ability. Furthermore, bristles of the bristle holder can vibrates at high frequency due to forward and backward vibration of an eccentric shaft and vibration amplifying action of a coil spring, thus efficiently removing plague from teeth.

[21] In addition, even when the motion of the bristle holder is stopped, both a rotating drive shaft and an output shaft of a drive motor, which is coupled to the rotating drive shaft, rotate smoothly. Accordingly, current consumption due to overload of the drive motor is prevented, so that the present invention makes it possible to use the electric toothbrush for a long time.

Brief Description of the Drawings

[22] The above and other objects, features and advantages of the present invention will become apparent from the following description of preferred embodiments given in conjunction with the accompanying drawings, in which: [23] FIG. 1 is an exploded perspective view of a brushhead for an electric toothbrush, according to an embodiment of the present invention; [24] FIG. 2 is a sectional view showing the coupling of the brushhead to a handle of the electric toothbrush, according to the embodiment of the present invention; [25] FIGS. 3 and 4 are sectional views showing the operation of a bristle holder coupled to an eccentric shaft of the electric toothbrush, according to the embodiment of the present invention; [26] FIGS. 5 and 6 are side sectional views showing the operation of the bristle holder coupled to the eccentric shaft of the electric toothbrush, according to the embodiment of the present invention; [27] FIGS. 7 through 10 are views showing the operation of an arm and the bristle holder in relation to the phase of a rotating drive shaft of the electric toothbrush, according to the embodiment of the present invention; [28] FIG. 11 is a sectional view showing a coupling of an arm of a brushhead to an eccentric shaft of the electric toothbrush, according to another embodiment of the present invention; and [29] FIG. 12 is a view showing the power transmission structure of a conventional electric toothbrush which increases torque using a reduction gear. Best Mode for Carrying Out the Invention

[30] Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings. Some specific details including the following de¬ scription and the accompanying drawings will be provided for general comprehension of the present invention, but, such specific details are merely examples for description of the present invention but do not mean that the present invention is limited to them. Furthermore, detailed explanations of well-known functions and constructions which may make the point of the present invention unclear will be omitted.

[31] FIG. 1 is an exploded perspective view of a brushhead for an electric toothbrush, according to an embodiment of the present invention. FIG. 2 is a sectional view showing the coupling of the brushhead to a handle of the electric toothbrush, according to the embodiment of the present invention. As shown in the drawings, the brushhead for the electric toothbrush according to the embodiment of the present invention includes a toothbrush head housing 1, and a bristle holder 2 which is rotatably mounted to a bristle holder mounting part 101 of the toothbrush head housing 1, with bristles set in an upper surface of the bristle holder 2. The brushhead further includes a rotating drive shaft 3 which is inserted into a hollow neck part 102 of the toothbrush head housing 1.

[32] The toothbrush head housing 1 has the bristle holder mounting part 101 which has a round shape and to which the bristle holder 2 is mounted. The toothbrush head housing 1 further has the hollow neck part 102 in which the rotating drive shaft 3 is installed and which has a handle coupling part 103 that is provided at an end opposite to the bristle holder mounting part 101 and coupled to the handle H, such that a rotational drive force is transmitted from a drive motor to the rotating drive shaft 3.

[33] The bristle holder 2 has a holder rotating shaft 205 which is a metal pin fastened to the center of the bristle holder 2. The holder rotating shaft 205 is coupled to the bristle holder mounting part 101 and makes it possible for the bristle holder 2 to rotate around the holder rotating shaft 205. The bristle holder 2 further has an arm support 201 which extends downwards, an arm rotating shaft 203 which protrudes from each of opposite sides of the arm support 201 in a direction perpendicular to the holder rotating shaft 205, and a U-shaped arm 202 which is mounted to the arm rotating shafts 203 and is rotatable upwards and downwards.

[34] The U-shaped arm 202 has at each of opposite ends thereof a hole which is fitted over each arm rotating shaft 203. An eccentric shaft coupling hole 204 is formed toward the outside in a convex part of an intermediate portion of the U-shaped arm 202. A cylindrical spring seat 207 is formed around the holder rotating shaft 205 in a central portion of the arm support 201. Furthermore, a support spring 206 is seated in the cylindrical spring seat 207, so that the bristle holder 2 is elastically supported against the bristle holder mounting part 101. The arm support 201 is provided with an arc-shaped groove 208 at a predetermined position opposite to the eccentric shaft coupling hole 204. A pin 104 is fitted into the bristle holder mounting part 101 and is loosely inserted into the groove 208, thus preventing the bristle holder 2 from being undesirably removed, and allowing the bristle holder 2 to rotationally vibrate.

[35] The rotating drive shaft 3 is installed in the hollow neck part 102 of the toothbrush head housing 1. The rotating drive shaft 3 has a motor shaft coupling part 308 at a flat end thereof, thus being coupled to an output shaft of the drive motor. An eccentric shaft support 302, to which the eccentric shaft 301 is integrally mounted, is provided on an opposite end of the rotating drive shaft 3. Next to the eccentric shaft support 302, a coil spring 303, a cylindrical spring spacing unit 304, a coil spring 305 and a cylindrical spring support 306 are sequentially fitted over the rotating drive shaft 3. An annular protrusion 307 is provided around the outer surface of the spring support 306 and engages with an annular groove 105 which is provided on an inner surface of the hollow neck part 102, thus preventing the coil springs 303 and 305 and the spring spacing unit 304 from being removed, and allowing the elasticity of the coil springs 303 and 305 to be transmitted to the eccentric shaft coupling hole 204.

[36] The power transmission path and element mounting structure of the present invention will be described herein below in detail with reference to FIG. 2. The bristle holder 2 is rotatably mounted to the bristle holder mounting part 101 without being un¬ desirably removed from the bristle holder mounting part 101. This is achieved by the insertion of the pin 104 into the arc-shaped groove 208 formed on a sidewall of the arm support 201. Of course, only the holder rotating shaft 205 is used as a means for preventing the bristle holder 2 from being removed, in the same manner as con¬ ventional electric toothbrushes. However, in the case of this structure, because the holder rotating shaft 205, which is a metal pin, is fastened to the toothbrush head housing 1 made of plastic, as the usage time increases, the possibility of a safety hazard occurring becomes high, for example, the bristle holder 2 undesirably changes in the mouth of a user while brushing teeth. Therefore, in the present invention, the holder rotating shaft 205 serves only as a rotating shaft, and an additional pin 104 serves to prevent the bristle holder 2 from being undesirably removed.

[37] The opposite ends of the U-shaped arm 202 are coupled to the arm rotating shafts

203 which are integrally provided at opposite sides on the arm support 201 of the bristle holder 2. An end of the eccentric shaft 301 having a spherical shape is inserted and coupled to the eccentric shaft coupling hole 204 formed in an intermediate portion of the U-shaped arm 202. The eccentric shaft coupling hole 204 may be manufactured into a spherical socket type, as shown in FIG. 11. [38] The eccentric shaft 301 has a pushing force toward the bristle holder 2 due to two coil springs 303 and 305, which are supported by the spring support 306 fastened in the hollow neck part 102 of the toothbrush head housing 1. This is possible because the annular protrusion 307, provided around the outer surface of the spring support 306, engages with the annular groove 105 formed in the inner surface of the hollow neck part 102. Therefore, in the state in which the spherical end of the eccentric shaft 301 is always coupled to the eccentric shaft coupling hole 204, the bristle holder 2 ro- tationally vibrates and the eccentric shaft 301 vibrates forwards and backwards.

[39] Because the spring spacing unit 304 is placed between the coil springs 303 and 305, forward and backward vibration of each coil spring 303, 305 can be amplified. Furthermore, the motor shaft coupling part 308, which is the motor-side end of the rotating drive shaft, maintains the coupling of the rotating drive shaft to the output shaft of the drive motor during forward and backward movement of the eccentric shaft 301 coupled to the end opposite to the motor shaft coupling part 308. Thus, the drive force of the drive motor can always be transmitted to the bristle holder 2 through the rotating drive shaft 3.

[40] FIGS. 3 and 4 are sectional views showing the operation of the bristle holder coupled to the eccentric shaft of the electric toothbrush, according to the embodiment of the present invention. FIGS. 5 and 6 are side sectional views showing the operation of the bristle holder coupled to the eccentric shaft of the electric toothbrush, according to the embodiment of the present invention. With reference to these drawings, the operation of the brushhead for the electric toothbrush according to the embodiment of the present invention will be explained herein below.

[41] As shown in FIG. 3, to operate the brushhead in a normal state, a clockwise drive force is transmitted from the drive motor to the arm 202 through the eccentric shaft 301. Then, as shown in FIG. 4, the bristle holder 2 coupled to the arm 202 half turns counterclockwise, and, simultaneously, the eccentric shaft 301 vibrates forwards and backwards.

[42] As shown in FIGS. 5 and 6, when the eccentric shaft 301 moves towards the top of the drawing according to the rotation of the rotating drive shaft 3, the arm 202 also moves upwards along with the eccentric shaft 301. Simultaneously, the eccentric shaft 301 vibrates forwards and backwards. Here, even though the position of the eccentric shaft 301 is changed, a gap between the end of the eccentric shaft 301 and the eccentric shaft coupling hole 204 of the arm 202 does not occur. This is because the eccentric shaft support 302, to which the eccentric shaft 301 is mounted, is biased toward the bristle holder 2 by the coil springs 303 and 305 which are supported by the spring support 306. Furthermore, due to this, the rotational drive force can be smoothly transmitted from the eccentric shaft 301 to the arm 202. Therefore, the present invention minimizes the loss of drive force transmitted to the arm 202.

[43] FIGS. 7 through 10 are views showing the consecutive operation of the arm 202 and the bristle holder 2 related to the phase of the rotating drive shaft 3 of the electric toothbrush, according to the embodiment of the present invention. As shown in the drawings, when the rotating drive shaft 3 rotates one turn, the eccentric shaft 301 revolves one turn around the rotating drive shaft 3. As a result, both the bristle holder 2 and the arm 202 rotationally vibrate clockwise and counterclockwise one time.

[44] In FIG. 7, the eccentric shaft 301 is placed at the lowest position, and the bristle holder 2 is not biased to either side. In this state, when the rotating drive shaft 3 rotates 90 degrees clockwise, the eccentric shaft 301 is placed at a middle position and the bristle holder 2 rotates at a predetermined angle clockwise, as shown in FIG. 8. When the rotating drive shaft 3 further rotates 90 degrees clockwise, the eccentric shaft 301 is placed at the highest position and the bristle holder 2 rotates counterclockwise and is in a state not biased to one side, as shown in FIG. 9. Continuously, when the rotating drive shaft 3 rotates a further 90 degrees clockwise, the eccentric shaft 301 is placed at the right middle position and the bristle holder 2 rotates at a predetermined angle coun¬ terclockwise, as shown in FIG. 10. In the above state, when the rotating drive shaft 3 rotates a further 90 degrees clockwise, the bristle holder 2 rotates at the predetermined angle clockwise and, thus, it is returned to the state of FIG. 7.

[45] This movement is repeated so that the brushhead rotationally vibrates.

[46] Furthermore, in the brushhead of the electric toothbrush according to the embodiment of the present invention, even if the operation of the bristle holder 2 is stopped by an outside force, the rotating drive shaft 3 can continuously rotate. The reason is that the arm 202, which is not a rigid body but is made of elastic material such as flexible engineering plastic, can be elastically bent and the rotating drive shaft 3 can also be elastically bent when the operation of the bristle holder 2 is forcibly stopped. Furthermore, this causes vibration in a manner similar to how vibration occurs when an eccentric cam rotates (vibration of a pager or cellular phone).

Claims

[1] A brushhead for an electric toothbrush, comprising: a bristle holder (2) ro- tationally vibrating within a predetermined angular range due to the revolution of an eccentric shaft (301) coupled to an end of a rotating drive shaft (3), with bristles set in the bristle holder, wherein the eccentric shaft (301) is jointed to an arm (202) which is spaced apart from a rotating shaft (205) of the bristle holder (2) by a predetermined distance and is shafted to the bristle holder (2) in a direction perpendicular to the rotating shaft

(205).

[2] The brushhead for the electric toothbrush according to claim 1, wherein the eccentric shaft (301) has a spherical shape at an end thereof, and the arm (202) comprises an eccentric shaft coupling hole (204) provided in an end of the arm (202), so that the end of the eccentric shaft (301) is inserted into the eccentric shaft coupling hole (204), and forms a pivot joint structure.

[3] The brushhead for the electric toothbrush according to claim 1, wherein the eccentric shaft (301) has a spherical shape at an end thereof, and the arm (202) comprises a spherical eccentric shaft coupling hole (204) provided in an end of the arm (202), so that the end of the eccentric shaft (301) is inserted into the eccentric shaft coupling hole (204), and forms a ball-socket joint structure.

[4] The brushhead for the electric toothbrush according to any one of claims 1 through 3, wherein the rotating drive shaft (3) is elastically supported in a hollow neck part (102) of a toothbrush head housing (1) such that the eccentric shaft (301) pushes the arm (202).

[5] The brushhead for the electric toothbrush according to claim 4, wherein the rotating drive shaft (3) comprises: a spring support (306) fitted over the rotating drive shaft (3) and fastened to the hollow neck part (102); and a coil spring (303), (305) fitted over the rotating drive shaft (3), so that a repulsive power of the coil spring (303), (305) is transmitted to the arm (202) through the eccentric shaft (301) provided on an eccentric shaft support (302).

[6] A brushhead for an electric toothbrush, comprising: a toothbrush head housing

(1) integrally having both a bristle holder mounting part (101) and a hollow neck part (102); a bristle holder (2) mounted to the bristle holder mounting part (101) and rotationally vibrating around a rotating shaft (205) thereof, with bristles set in the bristle holder (2); and a rotating drive shaft (3) inserted into the hollow neck part (102) of the toothbrush head housing (1), with an eccentric shaft (301) provided on an end of the rotating drive shaft (3), so that the rotating drive shaft (3) revolves the eccentric shaft (301) using a rotational drive force transmitted from a drive motor, wherein the bristle holder (2) comprises: an arm rotating shaft (203) protruding from each of opposite sides of an arm support (201), which extends downwards, in a radial direction with respect to the rotating shaft (205); and an arm (202) having a U- shape and coupled to the arm rotating shafts (203), with an eccentric shaft coupling hole (204) provided at a predetermined position in the arm (202) toward the eccentric shaft (301), wherein an end of the eccentric shaft (301) is jointed to the eccentric shaft coupling hole (204), so that a drive force is transmitted to the bristle holder (2) by revolution of the eccentric shaft (301).

[7] The brushhead for the electric toothbrush according to claim 6, wherein the eccentric shaft (301) has a spherical shape at an end thereof, and the arm (202) comprises an eccentric shaft coupling hole (204) provided in an end of the arm (202), so that the end of the eccentric shaft (301) is inserted into the eccentric shaft coupling hole (204), and forms a pivot joint structure.

[8] The brushhead for the electric toothbrush according to claim 6, wherein the eccentric shaft (301) has a spherical shape at an end thereof, and the arm (202) comprises a spherical eccentric shaft coupling hole (204) provided in an end of the arm (202), so that the end of the eccentric shaft (301) is inserted into the eccentric shaft coupling hole (204), and forms a ball-socket joint structure.

[9] The brushhead for the electric toothbrush according to any one of claims 6 through 8, wherein the rotating drive shaft (3) is elastically supported by a coil spring (303), (305) which is provided between a spring support (306), fitted over the rotating drive shaft (3) and fastened in the hollow neck part (102) of the toothbrush head housing (1), and an eccentric shaft support (302) which is provided on the end of the rotating drive shaft (3) and on which the eccentric shaft (301) is provided.

[10] The brushhead for the electric toothbrush according to claim 9, wherein the coil spring comprises two coil springs (303) and (305) which are provided between the eccentric shaft support (302) and the spring support (306) and are spaced apart from each other by a spring spacing unit (304) fitted over the rotating drive shaft (3).

[11] The brushhead for the electric toothbrush according to any one of claims 6 through 8, wherein the arm support (201) of the bristle holder (2) is provided with an arc-shaped groove (208) at a predetermined position opposite to the eccentric shaft (301), and a pin (104) is fitted into the bristle holder mounting part (101) and reaches the groove (208), so that the bristle holder (2) is prevented from being removed.

[12] The brushhead for the electric toothbrush according to any one of claims 6 through 8, wherein the arm support (201) of the bristle holder (2) is provided with a spring seat (207) which has a cylindrical shape, with a support spring (206) seated in the spring seat (207), so that the bristle holder (2) is elastically supported against the bristle holder mounting part (101).