DESCRIPTION OF DRAWINGS
FIG. 1 shows a perspective view of an electric toothbrush according to a preferred embodiment of the invention, which has a brush head with a rotary drivable bristle field.
FIG. 2 shows a schematic representation of a bristle cluster including filaments bent in a U-shape, which is accommodated in a cluster-receiving recess and is fastened with an anchor lying over the bend in the filaments.
FIG. 3 shows a schematic, perspective representation of a tooth cleaning bristle of the toothbrush from FIG. 1 according to a first preferred embodiment.
FIG. 4 shows a cross section through the tooth cleaning bristle from FIG. 3.
FIG. 5 shows a cross section through a tooth cleaning bristle according to an alternative embodiment of the invention.
Like reference symbols in the various drawings indicate like elements.
DETAILED DESCRIPTION
The toothbrush 13 shown in FIG. 1 comprises a handle 14 and a toothbrush head 2 which is seated on a brush tube 25 forming a front end of, connected to, or removably coupled to the handle 14. The handle 14 is formed by a toothbrush housing 26, in which a battery compartment and a drive motor 27 are disposed axially one behind the other. The drive motor 27 can be switched on and off by means of a switch 18. Via a drive train (not shown), comprising a gear mechanism and a transducer extending through the brush tube 25, the disk-shaped bristle holder 3 of the toothbrush head 2 can be driven in a rotationally oscillating manner. In the illustrated embodiment, a bristle field 19 is seated on the bristle holder 3. The bristle field has a substantially circular cylindrical configuration and can include a multiplicity of bristle clusters 4, as shown by FIG. 2.
The bristle cluster 4 shown in FIG. 2 is advantageously fastened to the bristle holder 3 by so-called anchor-plugging methods. The bristle holder 3 has for this purpose a substantially cylindrical, blind hole-shaped cluster-receiving recess 12, in which the bristle cluster 4 is held. The bristle cluster 4 here comprises a multiplicity of tooth cleaning bristles 1 bent in a U-shape, which essentially have double the length of the bristle cluster 4, so that each tooth cleaning bristle 1 sits in the shape of a loop in the receiving recess 12 and forms with its two side pieces in fact two bristles in the bristle cluster 4. As shown by FIG. 2, over the bend of tooth cleaning bristle 1 there is placed an anchor 11, with the aid of which the bristle cluster 4 is anchored in the cluster-receiving recess 12. The anchor 11 here extends transversely over the receiving recess 12 and can be driven in the wall thereof.
According to a first advantageous embodiment of the invention, the tooth cleaning bristles 1 advantageously have the contour shown in FIG. 3. Each tooth cleaning bristle 1 is here configured as a monofilament and is produced from a polymer material, in particular polyamide, PBT (polybutylene terephthalate) or a thermoplastic elastomer, other materials, too, in principle being usable. By virtue of the monofil configuration, the tooth cleaning bristle 1 has a substantially homogeneous material cross section.
As shown by FIG. 3, the tooth cleaning bristle 1 advantageously has an altogether cylindrical shape, in the illustrated embodiment a cross section being provided which is constant over the length of the tooth cleaning bristle 1. On the outer surface 5 of the tooth cleaning bristle 1 there is provided a contour 6, which in the illustrated embodiment has a course running axially parallel to the longitudinal axis of the tooth cleaning bristle 1.
As jointly shown by FIGS. 3 and 4, the contour 6 of the outer surface 5 substantially corresponds to a splined shaft contour, which in the illustrated embodiment has an eight-grooved configuration. In the peripheral direction, dentate or crenelated projections 7 alternate with depressions 8 of U-shaped cross section, the depressions 8 forming all in all axially parallel grooves in the outer surface 5 and the projections 7 forming axially parallel ribs.
As shown by FIG. 4, the projections 7 have in the peripheral direction a somewhat greater width than the depressions 8. The crenelated projections 7 are laterally delimited by straight side walls 13, while the raised top side of the projections 7, which forms a connecting portion 14 between the side walls 13 of the respective projection 7, has a slightly convex configuration. Said top sides of the projections 7 here respectively have the shape of a circular cylindrical segment and lie on a joint outer envelope circle 10 or an outer envelope cylinder, the diameter of which is labeled in FIG. 4 with the reference symbol D. The depressions 8 provided between the projections 7 form axially parallel grooves of U-shaped cross section, having a planar or, alternatively, slightly convex bottom 15, the bottoms 15 of all the depressions 8 lying together on an inner envelope circle 9 or an inner envelope cylinder, the diameter of which is labeled in FIG. 4 with the reference symbol d.
As shown by FIG. 4, the depressions 8 widen slightly radially outwards. The side walls 13 of the projections 7, which laterally delimit the depressions 8, are slightly inclined one to the other at an acute angle, preferably at an angle 16a of about 10° to 30°, preferably about 15°. While the angle 16a describes the “apex angle” directly between the inner points of intersection of the side wall 13 and the surface line of the depression, the greater angle 16b (about 20°) indicates the apex angle between the outer points of intersection of the side wall and the surface line of the projections.
The angle α (16a) in FIG. 4, which describes the angular range of the depressions in terms of their angular extent, is in any event less than the angle β, which describes the angular range of the angular extent of the projections. Preferably, a ratio of α to β is about 1 to 2.
In the illustrated embodiment, the depth of the depressions 8 is chosen such that the ratio of the aforesaid diameter D of the outer envelope circle 10 to the diameter d of the inner envelope circle 9 in the illustrated embodiment is about 1.15.
In the illustrated embodiment, eight depressions 8 and eight projections 7 are provided, with the depressions 8 and the projections 7 being evenly distributed over the periphery of the outer surface 5 respectively at a dividing angle of 45°.
In concrete terms, the diameter D of the outer envelope curve 10 in the illustrated embodiment is about 6.25 mil, equivalent to about 0.1587 mm, while the diameter d of the inner envelope curve 9 is about 5.5 mil, equivalent to about 0.1397 mm.
For the illustrated embodiment, this produces a circumference of about 0.60 mm to about 0.65 mm and a cross-sectional area of about 0.015 mm2 to about 0.20 mm2, so that the ratio of the circumference to the cross-sectional area is about 34 mm−1 to about 35 mm−1.
Alternatively to the cross-sectional area shown in FIG. 4, the tooth cleaning bristle can also have an approximately flower-shaped cross section or a cross section which approximately corresponds to the contour of a multi-lobed clover leaf, as shown by FIG. 5. The axially parallel projections 7 have in cross section a circular-arc-shaped outer contour, which is dimensioned and arranged such that respectively semicircular arc segments are placed adjacent to each other around the periphery. In this embodiment, the depressions 8 are formed by the pointedly converging side walls 13, so that the depressions 8 have an approximately V-shaped contour, while the walls have a curvature. In the illustrated embodiment, the side walls 13 of two adjacent projections 7 meet at an angle of about 45°.
As shown by FIG. 5, six such projections 7 of circular-segment-shaped cross section are evenly distributed over the periphery at a dividing angle of 60°, the projections 7 being evenly arranged also in the radial direction, so that with their respectively maximum radial extent they define an outer envelope circle 10, the diameter of which, in FIG. 5, is once again labeled with the reference symbol D. The depressions 8 define the inner envelope circle 9, the diameter of which is labeled in FIG. 5 with the reference symbol d.
The outer contour of the projections 7, which is rounded in cross section in the shape of a circular arc, is rounded with a radius of curvature of about 0.02 mm to about 0.03 mm, in the illustrated embodiment a rounding radius 16 of about 0.026 mm being provided. Together with the even distribution of the six projections 7, this produces a diameter D of the outer envelope circle 10 of about 6.58 mil, equivalent to about 0.167 mm. The diameter d of the inner envelope circle 9, which is defined by the depressions 8, amounts in the illustrated embodiment to about 4.34 mil, equivalent to about 0.11 mm. The minimum outer diameter 17, which is obtained by a measurement in the manner shown in FIG. 5, is about 5.5 mil to about 6.5 mil, in particular about 6 mil, equivalent to about 0.152±0.013 mm.
The diameter ratio of the outer envelope circle 10 to the inner envelope circle 9 in the illustrated embodiment is about 1.5.
By virtue of the arc-shaped projections 7 of the contour 6, the circumference is significantly enlarged relative to a circular cross section with the same cross-sectional area. For a flower-shaped cross-sectional contour of this kind, the circumference is advantageously about 0.575 mm to about 0.675 mm, combined with a cross-sectional area of about 0.013 mm2 to about 0.023 mm2. In concrete terms, in the illustrated embodiment, a circumference of about 0.625 mm is obtained with a cross-sectional area of about 0.018 mm2. Thus, the ratio of the circumference to the cross-sectional area is in a range of about 34 mm−1 to about 35 mm−1.
The tooth cleaning bristle can be used in manual toothbrushes and electric toothbrushes with sonic drive, oscillation drive or with eccentric balance drive.
A number of embodiments of the invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. Accordingly, other embodiments are within the scope of the following claims.
Patent Application
20070289078
