Title of Invention

AN ELECTRIC TOOTHBRUSH

Abstract

The invention relates to an electric toothbrush with a toothbrush shaft (4) rotating inside a brush casing (1) and a bristle carrier disc (10) which are connected to each other by a gear converting the rotary motion of the toothbrush shaft (4) into a reciprocating rotary motion of the bristle carrier disc (10), the toothbrush shaft (4) having at its end turned towards the rotatably mounted bristle carrier disc (10) an eccentric engaging in a gap bounded by two bearing faces on the bristle carrier disc (10), characterised in that the eccentric is formed by an eccentric disc (5) arranged on the toothbrush shaft (4) and spanning the gap (24) in any angular position.

Full Text

The invention relates to an electric toothbrush with a toothbrush shaft rotating inside a brush casing and a bristle carrier disc which are connected to each other by a gear converting the rotary motion of the toothbrush shaft into a reciprocating rotary motion of the bristle carrier disc, the toothbrush shaft having at its end turned towards the rotatably mounted bristle carrier disc an eccentric engaging in a gap bounded by two bearing faces on the bristle carrier disc. Such a toothbrush is known from WO 96137164. The gap is formed by a slot in the bristle carrier disc; and the eccentric, by a double crank at the end of the toothbrush shaft. The free end of the crank must be aligned with the centre of the bristle carrier disc in order that the eccentric works in the groove without play in all angular positions. To obtain adequate wear resistance and the desired absence of play, and at the same time low friction, in the known toothbrush, the toothbrush shaft has to be made as a metal part, which significantly increases the production cost of the electric toothbrush. The fundamental problem of the invention is to design an electric toothbrush of the kind stated at the outset so that so far as possible all its parts can be cheaply produced as injection-moulded parts. According to the invention this problem is solved by forming the eccentric from an eccentric disc arranged on the toothbrush shaft and spanning the gap in any angular position. This configuration enables the toothbrush shaft with the eccentric disc can be made as simple injection mouldings, or can even be made in one piece as a single injection moulding. Adequate freedom from play can be achieved with normal production accuracies, because the eccentric disc (disregarding its necessary eccentricity) does not need to be aligned with the centre of the bristle carrier disc. Furthermore, if the 2 toothbrush shaft and the eccentric disc are made as two parts, different sweep angles of the bristle carrier disc can be obtained by using different eccentric discs. One particularly simple embodiment consists in arranging the two bearing faces parallel with each other so that they bear against the eccentric and in configuring the eccentric as a non-circular, approximately elliptical, eccentric disc. By means of this arrangement, the changing gap (in projection) between the two bearing faces during the reciprocating rotary motion is compensated. Particularly low-play, low-friction working of the toothbrush is obtained by shaping the bearing faces with a convex curvature towards the circumferential surface of the eccentric disc. This has the effect of keeping the bearing face tangential to the circumferential surface of the eccentric disc at all times. Further configurations of the inventive idea follow from the subordinate claims. But it is exceptionally advantageous if the eccentric disc has a rotating helical groove which is obliquely angled with respect to the eccentric disc and the root of which forms the eccentric spanning the gap between the two drive pins. The effect of this configuration is that linear contact rather than point contact is made between the drive pins and the eccentric disc, with a considerable reduction in wear. With the embodiments described above, an eccentric disc acts on one side of the rotational axis of the bristle carrier disc, in a slot in the said bristle carrier disc. According to a development of the invention, a symmetrical and therefore inertially neutral application offeree can be realised by providing the bristle carrier disc with gaps on either side, disposed symmetrically and diametrically opposite about its rotational axis, and by providing the toothbrush shafl with two eccentric discs orientated in opposite directions and each engaging in one of the gaps. This results in a smoother oscillating motion of the bristle carrier disc. Forces acting in the axial direction on the toothbrush shafl are moreover avoided. The electric toothbrush can be given a particularly simple construction if the bristle carrier disc is rotatably mounted by its circumferential face inside the cylinder and the toothbrush shaft passes underneath the bristle carrier disc to a bearing in the brush head on the same side as the free end of the brush casing. Such an embodiment can be produced particularly cheaply in comparison with the embodiments described above. By virtue of the invention, it also becomes possible to subject Sets of bristles of the brush part to different motions by rotatably mounting concentrically inside the bristle carrier disc another bristle carrier disc that likewise has a projection with opposing gaps into each of which an eccentric disc on the toothbrush shaft engages in a similar fashion to the eccentric discs for the outer bristle carrier disc, so that the toothbrush shaft has altogether four eccentric discs. The invention admits of various embodiments. A number of these are shown in the drawing, and will now be described. In the accompanying drawings: Fig, 1 shows a brush casing and brush head of a toothbrush in an exploded view. Fig. 2 shows the components of Fig. 1 in a sectional view, Fig. 3 is a perspective view of the gear between the toothbrush shaft and the brush head. Fig. 4 is a section through the gear with the brush head located in the central position of the swept path. Fig. 5 is a section through the gear with the brush head turned away from the central position, Fig. 6 is a perspective view of a second embodiment of the toothbrush, in the region of its toothbrush shaft. Fig. 7 is a perspective view of the brush casing with components mounted therein in accordance with the second embodiment of the invention. Fig, 8 is a longitudinal section through the brush head region of another embodiment of the invention. Fig. 9 shows the arrangement of Figure 8 in an exploded perspective view. Fig, 10 is a perspective view of the bristle carrier disc according to Figures 8 and 9, Fig. 11 is a longitudinal section through the brush head region of yet another embodiment of the invention. Fig. 12 shows the arrangement of Figure 11 in an exploded perspective view. Figure 1 shows a brush casing 1 for a clip-on brush of an electric toothbrush. The brush casing 1 is configured as an elongated hollow cylinder whose one end is connectable to a handle (not shown) of the electric toothbrush and whose other end merges into a bowl-shaped brush head 2 for a brush part 3. A toothbrush shaft 4 mounted inside the brush casing 1 can be coupled at one end to a motor inside the handle of the toothbrush, and carries at its other end an eccentric disc 5 whose precise shape will be described in detail presently. On the toothbrush shaft 4 behind the eccentric disc 5 there is a collar 6 which is held in a bearing shell 7 of the brush casing 1. The brush head 2 has a cylinder 8 which is open upwards and is partially closed downwards by a bottom 9. The brush part 3 has bristles 25 anchored in a bristle carrier 5 disc 10. In the assembled condition, the bristle carrier disc 10 is held rotatably in the cylinder 8. A pivot pin 11 passes through the bottom 9 and is fixed externally by a circlip 12. Two drive pins 13, 14 project downwards from the bristle carrier disc 10, They are parallel with, but at a distance from, the pivot pin II. An angular zone is left clear in the bottom 9, corresponding to the sweep angle of the bristle carrier disc 10. Part of the cylinder 8 and brush casing 1 is cut away. This cutaway is completely covered by a cover 15 whose importance will become clear from the following description of Figure 2. Fig. 2 shows a forward region of the assembled clip-on brush in longitudinal section. The toothbrush shaft 4 is inserted into the brush casing 1 from the clip-on end. As the cover 15 has not yet been put on, the collar 6 can be placed in the bearing shell 7 immediately behind the eccentric disc 5, The cover 15 has a shoulder 22 which straddles the toothbrush shaft 4 above the bearing shell 7, thereby trapping it in the position shown. Further away from the brush head 2, the toothbrush shaft 4 has a collar 16 straddled by a slot 23 in the cover 15, thereby additionally trapping the toothbrush shaft 4 in the axial direction. The actual eccentric disc 5 is located inside the brush head 2 for the brush part 3. After assembly of the bristle carrier disc 10, the drive pins 13, 14, of which only the drive pin 13 can be seen in Figure 2, straddle the eccentric disc 5 on either side. The pivot pin 11 passes through a bearing sleeve 17 inserted in the bottom 9, and is held by a circlip 12 which lies in a recess on the outside of the bottom 9, which is covered by a cap 18. The assembly is sealed off by closing the brush casing 1 by means of the cover 15, Fig. 3 shows in particular the gear formed from the eccentric disc 5 at the end of the toothbrush shaft 4 and the two drive pins 13,14 on the bristle carrier disc 10. It can be seen that the eccentric disc 5 is attached to the toothbrush shaft 4 with extreme eccentricity; the eccentricity defines the angle swept by the bristle carrier disc 10 as it pivots to and fro. The crucial point is that the eccentric disc 5 at all times spans a gap 24 between the drive pins 13, 14 with little or no play, so that the transition from one direction of motion to the other occurs smoothly and without play. Since the drive pins 13, 14 move on circular paths about the pivot pin U, some peculiar features have to be taken into account: First, the orientation of the drive pins 13,14 with respect to the circumferential face 20 of the eccentric disc 5 changes, as is evident from comparison of Figures 4 and 5. The further away the drive pins 13, 14 are from the toothbrush shaft 4, the more obliquely they are angled with respect to the circumferential face 20, The sides of the drive pins 13, 14 forming the bearing faces are therefore curved so that the circumferential face 20 is always tangential to each bearing face. Next, they move forward and back with respect to the eccentric disc 5. For this reason the eccentric disc 5 has a certain thickness and its circumferential face 20 has a certain longitudinal extent. Lastly, it should be observed that the gap between the drive pins 13, 14 viewed parallel with the toothbrush shaft 4 changes with the angular position of the bristle carrier disc 10. This has implications for the outer contour of the eccentric disc: Fig. 4 shows a section through the theoretically circular eccentric disc 5 when its principal axis 21 is parallel with the drive pins 13, 14 (this axis is drawn in Figure 3; it is the line between the centre of the eccentric disc and the rotational axis defined by the toothbrush shaft 4). The eccentric disc 5 extends equally on either side of the principal axis 21. Hence the bristle carrier disc 10 is located in its central position. The diameter of the eccentric disc 5 perpendicular to the principal axis 21 will be designated the principal circle diameter. After a rotation through 90°, the principal axis 21 is perpendicular to the drive pins 13 and 14 and the bristle carrier disc 10 has undergone maximum rotation from the central position. This situation is shown in Figures 3 and 5. The distance between the 7 drive pins 13, 14 in the plane of projection formed by the eccentric disc 5 has decreased. TTie diameter of the eccentric disc 5 must decrease accordingly in this direction- Hence this diameter is smaller in the principal axis than the principal circle diameter defined above The transition irom one diameter to the other is continuous, so that the eccentric disc 5 is given an approximately elliptical outer contour. In the case of the embodiment shown in Figures 6 and 7, an angled all-round helical groove 19 is provided in the circumferential face of the eccentric disc 5. The root of this helical groove 19 forms the eccentric of the eccentric disc 5 in this embodiment. As Figure 7 shows, the two drive pins 13, 14 of the bristle carrier disc 10 engage in this helical groove 19. Therefore the rotary motion of the toothbrush shaft 4 again produces a reciprocating motion of the bristle carrier disc 10, In the embodiment shown in Figure 8, the bristle carrier disc 10 is rotatably mounted by its circumferential face 26 in the cylinder 8 of the brush head 2. The toothbrush shaft 4 passes underneath the bristle carrier disc 10 to a bearing 27 on the outer side of the brush head 2. On the side towards the toothbrush shaft 4, the bristle carrier disc 10 has a ring-shaped projection 28 in which a gap 29 on the opposite side is provided in addition to the gap 24. In exactly the same way as in the previously described embodiments, the toothbrush shaft engages by an eccentric disc 5 in the gap 24, But this toothbrush shaft 4 has a second eccentric disc 30, close to the bearing 27, which is orientated the opposite way to the eccentric disc 5 and engages in the second gap 29. The exploded perspective view in Figure 9 will serve to reveal more clearly the design of the embodiment shown in Figure 8, The toothbrush shaft 4 with its two eccentric discs 30 and 5 can be seen. Also visible in Figure 9 is the bristle carrier disc 10 with its projection 28 and gap 24 in which the eccentric disc 5 engages. The brush head 2 consists oftwo shells 2aj 2b. Two rings 31, 32, which define the axial position of the 8 bristle carrier disc !0 in the cylinder 8 of the brush head 2, ^e inserted in the upper shell 2a. The view in Figure 10 of the individual component consisting of the bristle carrier disc 10 reveals the two opposing gaps 29, 24 in the projection 28 of the bristle carrier disc 10 in which the eccentric discs 30, 5 respectively engage. In the embodiment of Figure 11, another bristle carrier disc 33 is rotatably inserted concentrically inside the bristle CEurier disc 10, The outer bristle carrier disc 10 is therefore ring-shaped. Just like the outer bristle carrier disc 10, the inner bristle carrier disc 33 has a projection 34 with two gaps 35,36 in which eccentric discs 37,38 on the toothbrush shaft 4 respectively engage to produce the reciprocating motion. The toothbrush shaft 4 therefore has altogether four eccentric discs 5, 37, 38, 30 in this embodiment. The exploded perspective view in Figure 12 shows the ring-shaped bristle carrier disc 10 with its projection 28 and a gap 24. The bristle carrier disc 33 with its projection 34 and a gap 35 can also be seen. As in Figure 9, the toothbrush shaft 4 is again seen in Figure 12, but here it has four eccentric discs 5,27,38,30. Also visible in Figure 12 is one half of the bearing 27 in which the free end of the toothbrush shaft 4 is mounted in the brush head 2. List of reference numbers 1 brush casing 2 brush head 3 brush part 4 toothbrush shaft 5 eccentric disc 6 collar 7 bearing shell 8 cylinder 9 bottom 10 bristle canier disc 11 pivot pin IZcirclip 13 drive pin 14 drive pin 15 Cover 16 collar 17 bearing sleeve 18 cap 19 helical groove 20 circumferential face 21 principal axis 22 shoulder 23 slot 24 gap 25 bristles 16 circumferential face 27 bearing 28 projection 29 gap 30 eccentric disc 31 ring 32 ring 33 bristle carrier disc 34 projection 35 gap 36 gap 37 eccentric disc 38 eccentric disc WE CLAIM : 1, An electric toothbrush with a toothbrush shaft (4) rotating inside a brush casing (1) and a bristle carrier disc (10) which are connected to each other by a gear converting the rotary motion of the toothbrush shaft (4) into a reciprocating rotary motion of the bristle carrier disc (10), the toothbrush shaft (4) having at its end turned towards the rotatably mounted bristle carrier disc (10) an eccentric engaging in a gap bounded by two bearing faces on the bristle carrier disc (10), characterised in that the eccentric is formed by an eccentric disc (5) arranged on the toothbrush shaft (4) and spanning the gap (24) in any angular position. 2, The electric toothbrush as claimed in claim 1, wherein the two bearing faces are parallel with each other and bear against the eccentric and in that the eccentric is configured as a non-circular, elliptical, eccentric disc (5). 3, The electric toothbrush as claimed in claim 1 or 2, wherein the bearing faces have a convex curvature towards the circumferential surface (20) of the eccentric disc (5). 4. The electric toothbrush as claimed in any one of the preceding claims, wherein the gap (24) is formed between two drive pins (13, 14) projecting from a bottom end face of the bristle carrier disc (10), and the bearing faces are provided on these drive pins (13,14), 5. The electric toothbrush as claimed in any one of the preceding claims, wherein the toothbrush shaft (4) has, near to its eccentric disc, a rotating collar (6) which engages into a bearing shell (7) of the brush casing (1), 6. The electric toothbrush as claimed in claim 5, wherein a portion of the brush casing (1) is formed by a cover (15) removably inserted into a recess in the brush casing (1) and forming part of the bearing shell (7). 7. The electric toothbrush as claimed in claim 6, wherein the cover (15) also forms part of a seat (2) for the bristle carrier disc (10). 8. The electric toothbrush as claimed in any one of the preceding claims, wherein the eccentric disc (5) has a rotating helical groove (19) which is obliquely angled with respect to the eccentric disc (5) and the root of which forms the eccentric spanning the gap (24) between the two drive pins (13, 14). 9. The electric toothbrush as claimed in any one of the preceding claims, wherein tiie bristle carrier disc (10) has gaps (24, 29) on either side, arranged symmetrically and diametrically opposite about its rotational axis, and the toothbrush shaft (14) correspondingly has two eccentric discs (5,30) orientated in opposite directions, each engaging in one of the gaps (24, 29), 10. The electnc toothbrush as claimed in claim 9, wherein the bristle carrier disc (10) is rotatably mounted by its circumferential face (26) in the cylinder (8), and the toothbrush shaft (4) passes underneath the bristle canier disc (10) to a bearing (27) in the brush head (2) on the same side as the free end of the brush casing (1). 11. The electric toothbrush as claimed in claim 9 or 10, wherein a bristle carrier disc (33) is rotatably mounted concentrically inside the bristle carrier disc (10), and likewise has a projection (34) with opposing gaps (35, 36) into each of which an eccentric disc (37, 38) on the toothbrush shaft (4) engages, in similar fashion to the eccentric discs (5, 30) for the outer bristle carrier disc (10), so that the toothbrush shaft (4) has altogether four eccentric discs (5, 30; 37, 38).

Documents:

0722-chenp-2003 abstract-duplicate.pdf

0722-chenp-2003 abstract.pdf

0722-chenp-2003 claims-duplicate.pdf

0722-chenp-2003 claims.pdf

0722-chenp-2003 correspondences others.pdf

0722-chenp-2003 correspondences po.pdf

0722-chenp-2003 description (complete)-duplicate.pdf

0722-chenp-2003 description (complete).pdf

0722-chenp-2003 drawings-duplicate.pdf

0722-chenp-2003 drawings.pdf

0722-chenp-2003 form-1.pdf

0722-chenp-2003 form-13.pdf

0722-chenp-2003 form-26.pdf

0722-chenp-2003 form-3.pdf

0722-chenp-2003 form-5.pdf

0722-chenp-2003 pct.pdf

0722-chenp-2003 petition.pdf