Brush head for electric toothbrush

Abstract

The object of the invention is a brush head for an electric toothbrush, the brush head comprising a hollow body part (1), a back and forth rotating shaft (3) inside the body part (1), and a rotating bristle carrier (7) rotated back and forth by the shaft (3) at the first end of the body part (1), and where the second end of the shaft (3) comprises a protrusion (3a) that is in an inclined angle (A) in relation to the rotation axis of the shaft (3). The inclination angle (A) is substantially between 20-70 degrees, and the inclination of the protrusion (3a) is directed towards the rotation axis of the shaft (3).

Claims

1. A brush head for an electric toothbrush, the brush head comprising: a hollow body part having a first end and a second end; a back and forth rotating actuating shaft inside the body part; a cylindrical pin proximate an end of the actuating shaft, the cylindrical pin is coaxial in relation to the longitudinal rotation axis of the actuating shaft; a hole near the second end of the body part, wherein the pin is received in the hole; and the body part having a rotating bristle carrier rotated back and forth by the actuating shaft at the second end of the body part, wherein the end of the actuating shaft comprises a protrusion that is in an inclined angle (A) in relation to the rotation axis of the actuating shaft, wherein the bristle carrier comprises a groove that is substantially straight and parallel to the rotation axis of the bristle carrier, and when the bristle carrier is in its middle position, the groove is open substantially towards the end of the actuating shaft, and the protrusion is inside the groove so that when the actuating shaft is making its back and forth rotation motion around its rotation axis, the protrusion in the groove turns and rotates simultaneously the bristle carrier back and forth, wherein the inclination angle (A) of the protrusion is between 20-70 degrees, and the protrusion is directed to extend towards the rotation axis of the actuating shaft, and that the pin and the inclined protrusion form a combination where the protrusion is extending towards the rotation axis of the actuating shaft and towards the pin.

2. The brush head for an electric toothbrush according to claim 1, wherein the groove has two side walls which are substantially planar, and a mutual distance of the side walls is bigger than the width of the protrusion.

3. The brush head for an electric toothbrush according to claim 2, wherein a contact between the groove and the protrusion is a changing line contact between at least one planar side wall of the groove and an envelope surface of the protrusion.

4. The brush head for an electric toothbrush according to claim 1, wherein the protrusion is circular or elliptic in its cross-section and substantially uniform in its cross-section from its root end to its top end.

5. The brush head for an electric toothbrush according to claim 1, wherein in a middle position of the rotation motion of the actuating shaft, the protrusion is inclined in the angle (A) in a direction towards a back end of the bristle carrier.

6. The brush head for an electric toothbrush according to claim 1, wherein in a middle position of the rotation motion of the actuating shaft, the protrusion has been inclined in the angle (A) in a direction that is parallel to a longitudinal direction of the groove.

7. The brush head for an electric toothbrush according to claim 1, wherein a structure of the brush head and its components have been dimensioned and arranged so that when the actuating shaft rotates 90 degrees back and forth from its middle position, the bristle carrier rotates back and forth from its own middle position an angle that is substantially equal to the inclination angle (A) of the protrusion.

8. The brush head for an electric toothbrush according to claim 1, wherein the inclination angle (A) is between 30 degrees and 40 degrees.

9. The brush head for an electric toothbrush according to claim 1, wherein the protrusion is a fixed and integrated part of the actuating shaft and is made of a same material as the actuating shaft.

10. The brush head for an electric toothbrush according to claim 1, wherein an assembly hole is on an opposite side of the body part compared to the bristle carrier.

Description

(1) In the following, the invention will be described in more detail by the aid of one preferred embodiment with reference to the attached drawings, wherein

(2) FIG. 1 presents in a side view an actuating shaft according to the invention to be installed inside a body part of the brush head for an electric toothbrush,

(3) FIG. 2 presents in an oblique side view and partially cross-sectioned a brush head according to the invention, inside which the actuating shaft according to FIG. 1 is installed in its place but where the locking plug is still partially loose,

(4) FIG. 2a presents an inner space of the body part of the brush head according to the invention seen from the first end of the body part,

(5) FIG. 3 presents in a side view and partially cross-sectioned an upper end of the brush head according to the invention, inside which the actuating shaft according to FIG. 1 is installed in its place,

(6) FIG. 4 presents in a front view a brush head according to the invention without a bristle carrier,

(7) FIG. 5 presents schematically and in a simplified way a bristle carrier according to the invention in its middle position seen from behind,

(8) FIG. 6 presents schematically and in a simplified way a bristle carrier according to the invention in its rotated position seen from behind,

(9) FIG. 7 presents a bristle carrier according to the invention seen from below and behind,

(10) FIG. 8 presents a bristle carrier according to the invention partially cross-sectioned seen from side and behind,

(11) FIG. 9 presents a bristle carrier according to the invention seen from the top and behind,

(12) FIG. 10 presents a bristle carrier according to one embodiment of the invention seen from below,

(13) FIG. 11 presents a bristle carrier according to another embodiment of the invention seen from below,

(14) FIG. 12 presents a bristle carrier according to a third embodiment of the invention seen from below,

(15) FIG. 13 presents a bristle carrier according to yet another embodiment of the invention seen from below,

(16) FIG. 14 presents a bristle carrier according to the invention partially cross-sectioned seen from side, and

(17) FIG. 15 presents a bristle carrier according to yet another embodiment of the invention seen from side.

(18) The replaceable brush head for an electric toothbrush according to the invention comprises at least a hollow body part 1 of the brush head, a back and forth rotating actuating shaft 3 inside the body part 1, and a back and forth rotating bristle carrier 7 at the second end of the body part 1. Advantageously, the body part 1, actuating shaft 3 and bristle carrier 7 are made of plastic but as well they can be made also of other suitable materials and their combinations.

(19) FIG. 1 presents in a side view the actuating shaft 3 according to the invention to be installed inside a body part 1 of the brush head. At its second end or the upper end the actuating shaft 3 has a cylindrical pin 4 that is coaxial in relation to the longitudinal rotation axis of the actuating shaft 3. Preferably the pin 4 is made of metal and it acts as an axle pin for the rotation axis of the actuating shaft 3 when the electric motor of the electric toothbrush rotates the actuating shaft 3 back and forth at its first end or lower end. At the side of the pin 4 and the rotation axis of the actuating shaft 3 the second end part of the actuating shaft 3 passes the pin 4 and extends towards the tip of the second end of the actuating shaft 3.

(20) At the tip of the second end of the actuating shaft 3 there is a protrusion 3a acting as a crank member. The protrusion 3a has been inclined with its center axis in an angle A in relation to the rotation axis of the actuating shaft 3. The protrusion 3a is substantially dowel like or cylindrical and is preferably circular in its cross-section but it can also be elliptic in its cross-section, and the protrusion 3a extends in the angle A towards the rotation axis of the actuating shaft 3. Thus the distal end of the protrusion 3a is directed in angle A towards the rotation axis of the actuating shaft 3. Substantially the whole length of the protrusion 3a is of the uniform cross-section. In addition the protrusion 3a is a fixed and integrated part of the actuating shaft 3 and is made of the same material as the actuating shaft 3. Preferably the protrusion 3a has been cast of the same material and at the same time in the same mould as the rest of the actuating shaft 3.

(21) FIGS. 2-4 present the brush head according to the invention. The actuating shaft 3 has been installed in its place inside the body part 1 of the brush head, and the bristle carrier 7 has been installed in its place at the second end of the body part 1. The pin 4 is in its place in a hole 5 that is situated near the second end of the body part 1. The pin 4 in the hole 5 keeps the second end of the actuating shaft 3 in its place and allows the actuating shaft 3 rotate back and forth around its rotation axis that is coaxial with the pin 4 and the hole 5. The installation is not yet complete in FIG. 2 because the locking plug 6 aimed to lock the actuating shaft 3 in its place is not yet in its final place inside the first end of the body part 1. The locking plug 6 is also an adapter to connect the brush head model-specifically to the main body of the electric toothbrush, whose primary shaft connects at the same time to the actuating shaft 3 inside the body part 1 of the brush head.

(22) On the backside, i.e. on the opposite side of the body part 1 as the bristle carrier 7 there is an assembly hole 1a in the body part 1 in order to make the assembly of the actuating shaft 3 easier. The assembly hole 1a on the backside of the body part 1 makes it possible that toothpaste does not penetrate inside the body part 1 as easily as in case where the assembly hole would be on the same side of the body part 1 as the bristle carrier 7, or even on both the sides the body part 1.

(23) At the second end of the body part 1 there is a shaft pin 2 that extends from the back wall of the body part 1 towards the bristle carrier 7 and acts as a rotation shaft of the bristle carrier 7. The shaft pin 2 that is preferably made of metal is substantially perpendicular to the rotation axis of the actuating shaft 3 but it can also be in another angle. In addition the bristle carrier 7 has been locked to the second end of the body part 1 with the help of a locking pin 9 that is placed through a locking hole 9a at the second end of the body part 1 to a transversal groove in the body of the bristle carrier 7. The locking pin 9 locks the bristle carrier 7 in its place so that the bristle carrier 7 can rotate back and forth around the shaft pin 2 but the bristle carrier 7 cannot move horizontally along the shaft pin 2 and therefore the bristle carrier 7 cannot disengage from its place.

(24) The back part of the bristle carrier 7 contains a substantially straight groove 8 that is parallel to the rotation axis of the bristle carrier 7. When the bristle carrier 7 is in its place the groove 8 is open substantially towards the second end of the actuating shaft 3 and the protrusion 3a is installed in the groove 8 so that when the actuating shaft 3 is making its back and forth rotation motion around its rotation axis, the protrusion 3a in the groove 8 rotates simultaneously the bristle carrier 7 back and forth. The width of the groove 8 is substantially the same as the width or diameter of the protrusion 3a, or suitably somewhat broader so that the protrusion 3a can be fitted into the groove 8 and can be turned in the groove 8.

(25) FIG. 2a presents an inner space of the body part 1 of the brush head according to the invention seen from the first end of the body part 1. In FIG. 2a the body part 1 is shown its backside downwards and without the actuating shaft 3 and bristle carrier 7.

(26) FIGS. 5 and 6 present schematically and in a simplified way the bristle carrier 7 according to the invention seen from behind. In FIG. 5 the bristle carrier 7 is in its middle position, and in FIG. 6 the bristle carrier 7 is in its rotated position. Also a part of the second end of the actuating shaft 3 is shown in FIGS. 5 and 6.

(27) The protrusion 3a at the second end of the actuating shaft 3 is arranged into an angle A that is for example 30 degrees in relation to the rotation axis of the actuating shaft 3, and the inclination of the protrusion 3a is directed towards the rotation axis of the actuating shaft 3 so that when the bristle carrier 7 is in the middle position of its rotation area the protrusion 3a is directed obliquely away from the bristle carrier 7 towards the rotation axis of the actuating shaft 3. As mentioned earlier, the rotation axis of the actuating shaft 3 is coaxial with the pin 4. This way the distance of the point of contact between the protrusion 3a and the groove 8 from the rotation axis of the actuating shaft 3 is as short as possible, which improves the durability of the structure and makes at the same time the desired rotation motion possible. The point of contact between the protrusion 3a and the groove 8 is substantially a changing line contact between the sides 8a of the groove 8 and the cylindrical or elliptical envelope surface 3b of the protrusion 3a.

(28) FIGS. 5 and 6 show clearly how the bristle carrier 7 rotates when the actuating shaft 3 rotates around its rotation axis. The bristle carrier 7 has been locked in its place by the shaft pin 2 and the locking pin 9, thus it can only rotate back and forth around the shaft pin 2 that is inserted in the hole 7a. In FIG. 5 the actuating shaft 3 and the bristle carrier 7 are in their middle position. In FIG. 6 the actuating shaft 3 has rotated 90 degrees clockwise from its middle position. When the inclination angle A of the protrusion 3a is for example 30 degrees the protrusion 3a is inclined towards the rotation axis of the actuating shaft 3 and towards the pin 4 the same 30 degrees as is seen in FIG. 6 straight from the side of the actuating shaft 3. The protrusion 3a is in the groove 8 of the bristle carrier 7 and the contact between the envelope surface 3b of the protrusion 3a and the substantially planar sidewalls 8a of the groove 8 is a line contact that has turned the bristle carrier 7 around its rotation axis the same 30 degrees. When the actuating shaft 3 rotates from its middle position counterclockwise the bristle carrier 7 rotates correspondingly to another direction.

(29) In general, it can be noted that the structure of the brush head according to the invention and its components have been dimensioned and arranged so that when the actuating shaft 3 rotates 90 degrees back and forth from its middle position the bristle carrier 7 rotates back and forth from its own middle position an angle that is substantially equal to the inclination angle A of the protrusion 3a.

(30) The actuating shaft 3 can be arranged to rotate back and forth around its rotation axis substantially as many degrees as the primary shaft of the main body of the electric toothbrush rotates back and forth, and in the same phase. Thus, for example, when the primary shaft rotates 30 degrees clockwise the actuating shaft 3 rotates simultaneously the same 30 degrees clockwise, and when the primary shaft rotates degrees counterclockwise the actuating shaft 3 rotates simultaneously the same 30 degrees counterclockwise. In that case the total rotation angle of the actuating shaft 3 is 60 degrees. However, a different transmission ratio can be used to rotate the actuating shaft 3 more or less than the primary shaft rotates.

(31) Also the inclination angle A of the protrusion 3a can be changed. In that case inclination angle A of the protrusion 3a is adjustable and also the rotation angle of the bristle carrier 7 is therefore adjustable. Thus the adjustment of the rotation angle of the bristle carrier 7 has been carried out with the inclination angle A of the protrusion 3a. In that case the inclination angle A of the protrusion 3a can be also smaller or bigger than 30 degrees. It can be for instance between 10-80 degrees, suitably substantially between 20-70 degrees and advantageously between 30-40 degrees, preferably about 30 degrees.

(32) FIGS. 7-9 present the bristle carrier 7 according to the invention in different positions. FIG. 7 presents the bristle carrier 7 seen from below or from the direction of the handle, and behind whereas FIG. 8 presents the bristle carrier 7 partially cross-sectioned seen from side and behind, and FIG. 9 presents the bristle carrier 7 seen from the top and behind. In its front part the bristle carrier 7 has a group of bristles and in its back part the bristle carrier 7 has a body that comprises the groove 8, the shaft hole 7a and the groove 7b that is transversal in relation to the shaft hole 7a, and is arranged to allow the rotational motion of the bristle carrier 7 when the locking pin 9 is in the groove 7b to prevent the bristle carrier 7 disengaging from the shaft pin 2.

(33) Above the bristle carrier 7 with the symmetrical groove 8 having flat and straight sidewalls 8a has been described. That kind of a bristle carrier 7 is described also in FIGS. 7 and 10. The protrusion 3a moves smoothly in the even groove 8 and at the same time rotates the bristle carrier 7 smoothly. In order to make it possible to achieve a rotating and simultaneously vibrating bristle carrier 7 that cleans teeth in a more effective way, another embodiments of the invention are presented in FIGS. 11-15. Instead of being smooth or flat and straight the sidewalls 8a can be uneven having regular or irregular bulges and hollows, which act as guiding means causing the bristle carrier 7 to vibrate during its rotation motion. In that case when seeing the groove 8 perpendicularly towards the rotation axis of the bristle carrier 7 the sidewalls 8a can be, for example, undulated or serrated. FIGS. 11 and 12 show a bristle carrier 7 where the sidewalls 8a of the groove 8 are undulated. Whereas FIGS. 13-15 show a bristle carrier 7 where the sidewalls 8a of the groove 8 are serrated.

(34) The form, direction and size of the undulation and/or serration can vary. In that case the wavelength of the undulation and/or serration can be shorter or longer and the peak-to-peak amplitude of the undulation and/or serration can be smaller or bigger. Also the form of the undulation and/or serration can be symmetrical or asymmetrical. In embodiments shown in FIGS. 11 and 12 the peak-to-peak amplitude of the undulation is essentially the same but the wavelength in FIG. 11 is bigger than in FIG. 12.

(35) In the embodiments shown in FIGS. 11-14 the undulation and serration are straight and the bulges and hollows, for example, wave crests 8b are substantially perpendicular to the bottom of the groove 8. Whereas FIG. 15 presents a structure where the serration is in an inclined position or in an acute angle in relation the bottom of the groove 8. Also the undulation of the sidewalls 8a of the groove 8 can be in an inclined position or in an acute angle in relation the bottom of the groove 8. The wave crest 8b presented in FIGS. 14 and 15 is straight in its entire length but it can also be curvilinear both in undulated sidewalls and serrated sidewalls. The form of the entire wave or serration is similar to the form of its crest.

(36) According to the invention the brush head, more precisely the bristle carrier 7 comprises a guiding means to cause the bristle carrier 7 to vibrate. The intensity or volume of the vibration of bristle carrier 7 is arranged to be adjustable with the help of the form, direction and/or the size of the guiding means comprising the groove 8, its sidewalls 8a and possible undulation or serration on the sidewalls 8a. When the sidewalls 8a are flat and straight the value of the volume of vibration of bristle carrier 7 is zero and vibration does not exist. When the sidewalls 8a are undulated and/or serrated the undulation and/or serration causes vibration to the bristle carrier 7 when the bristle carrier 7 rotates back and forth around its rotation axis.

(37) The adjustment of the vibration of the bristle carrier 7 has been arranged so that the bigger is the amplitude of the undulation or serration the stronger is the volume of the vibration, and the smaller is the wavelength of the undulation or serration the greater is the frequency of the vibration. Thus the intensity or volume of the vibration of the bristle carrier 7 is arranged to vary between the values 0 and N where 0 means no vibration and N means an amount of vibration, which is a maximum given value, which can be safely used without a danger to cause any harm to the user or to the structure of the toothbrush.

(38) It is obvious to the person skilled in the art that the invention is not limited to the embodiment example presented above, but that it may vary within the scope of the claims to be presented below.