toothbrush

Abstract

The present invention relates to a toothbrush comprising a brush head, at least one folded bristle bundle and at least one plastic anchor plate piece, the brush head having a hole with a longitudinal axis for at least one bristle bundle, an anchor plate piece being fixed in the hole for fixing each bristle bundle, the anchor plate piece being held in two grooves extending parallel to the longitudinal axis, the grooves being formed in the hole on the basis of injection molding technology, the groove having a centering portion, the centering portion having a depth, viewed in a direction perpendicular to the longitudinal axis, which gradually decreases as the distance from the entrance of the hole increases.

Description

[Technical field]

[0001] The present invention relates to a toothbrush comprising a plastic brush head, at least one folded bristle tuft, and at least one anchor plate piece made of plastic. [Background technology]

[0002] In conventional toothbrush manufacturing, the bristle bundles are attached to the brush head by metal anchor plate pieces, which are, for example, 3 / 10 mm wider than the hole diameter. The anchor plate pieces together with the folded bristle bundles are pressed into the bristle bundle holes, with the anchor plate pieces being embedded with their opposing outer edges in the brush body material and thus held therein.

[0003] Moreover, it has already been proposed that in metallic brush heads the bristle bundles are fixed by metal anchors: the brush head is drilled with holes for the bristle bundles, and in each hole small holes are formed, located diametrically opposite each other, for introducing the metal anchors (JP 2009-125084 A, Kao Corporation).

[0004] Known fastening techniques are laborious to produce and provide low reliability in fastening the hair bundles. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2009-125084 A Summary of the Invention [Problem to be solved by the invention]

[0006] The object of the invention is to provide a toothbrush belonging to the technical field mentioned at the outset which is easy to manufacture and ensures a secure fixation of the bristles. [Means for solving the problem]

[0007] The solution to the problem is defined by the features of claim 1.

[0008] The toothbrush according to the invention comprises a plastic brush head, at least one folded bristle bundle and at least one plastic anchor plate piece. The brush head has a hole for at least one bristle bundle with a longitudinal axis and a hole cross section with a basic shape for receiving the folded bristle bundle. An anchor plate piece is fixed in the hole for fixing each bristle bundle in its free cross section. The wall of the hole holds two grooves extending parallel to the longitudinal axis of the hole, which grooves extend beyond the basic shape of the hole cross section (seen perpendicular to the longitudinal axis) and are formed on the basis of injection molding technology. The grooves form a U-shaped profile. The anchor plate piece is fixed by welding to both grooves of the U-shaped profile. The groove has a combination part with a centering and a tapered part next to the entrance of the hole, which combination part has a depth and a width, seen perpendicular to the longitudinal axis, that gradually decrease with increasing distance from the entrance of the hole.

[0009] The invention is based on the recognition that without the combination according to the invention, it is not possible to achieve a sufficiently firm (i.e. with a sufficiently high pull-out force) and sufficiently reliable (i.e. with sufficient consistency during the respective welding) fixing of the plastic anchor. It has been found by experiment that if the anchor plate pieces are not fed sufficiently symmetrically when introduced into the bore, they are deformed (e.g. due to slight manufacturing offsets between the groove and the anchor plate) and are therefore only partially welded, or the contact between the edge of the anchor plate pieces and the three wall sides of the U-shaped profile is insufficient in other places, so that welding only takes place at individual points. In this connection, it has also been found that a significant increase in the pull-out force for the hair bundle is achieved if the anchor plate pieces are welded to all three sides of the U-shaped groove.

[0010] Experiments have also shown that it is important that the U-shaped grooves are machined into the voluminous material of the brush head: if the wall volume around the groove is too small, the softened plastic material can escape, which significantly reduces stability.

[0011] The plastic anchor plate pieces have the advantage over steel anchor plate pieces in that no separate materials (metal / plastic) are required, allowing for easy and environmentally friendly disposal of the toothbrush.

[0012] Preferably, the longitudinal axis of the holes is perpendicular to the surface of the brush head.The brush head may be provided with several rows of parallel holes spaced a small distance apart.

[0013] According to one particular embodiment, the holes have a geometrically simple basic shape, such as a circle, a rectangle or an oval (seen transversely to their longitudinal axis).

[0014] The grooves are machined into the walls of the holes, i.e. the holes extend beyond the basic shape of the cross section of the holes into the material volume of the brush head. The grooves are already provided in the holes when the bristles and the anchor plate pieces are inserted. The grooves are formed on the basis of injection molding technology, i.e. during the manufacture of the brush head on the basis of injection molding technology.

[0015] Thus, preferably, the wall is substantially the inner surface of a hollow cylinder or a rectangular or elliptical hollow moulding defined by the hole, and thus the wall is generally parallel to the longitudinal axis of the hole.

[0016] According to the invention, the groove has a cross section (seen perpendicularly to the longitudinal axis of the hole) that is U-shaped. Since the groove is recessed into the wall and is not, for example, fitted over a rib protruding into the (free) cross section of the hole, the three wall sides of the U-shaped profile are surrounded by the voluminous material of the brush head. Therefore, the inevitable heating and softening of the material that occurs in the U-shaped profile during welding does not allow the plastic material to escape. The anchor plate pieces are therefore reliably fixed both to the end faces (bottom of the U-shaped profile) and to the edge faces of the U-shaped profile.

[0017] In order not to weaken the walls between closely adjacent holes in a row or to have a sufficient distance between the grooves of adjacent holes, in a particular embodiment the basic shape of the holes is configured as a circle or an oval, and the direction defined by the mutually opposing grooves of the holes is offset by an angle greater than 0°, in particular an angle of 30° to 40°, relative to the direction of the row of holes.

[0018] By having a simple basic shape (circular, oval, rectangular, etc.), i.e. convex (i.e. having no recesses such as ribs or inward protrusions), and by having the groove recessed into the wall, the cross-section of the hole can optionally be adapted to the tuft of hair to be inserted.

[0019] At the entrance of the hole and thus of the groove, on the one hand, the combination part forms a centering part of the U-shaped profile, which, viewed in the radial direction with respect to the longitudinal axis of the hole, tapers the insertion area or insertion path of the anchor plate piece. On the one hand, the anchor plate piece is thus centered (e.g. with respect to the longitudinal axis of the hole), and on the other hand, the anchor plate piece is gradually fed during insertion into the area (referred to further below as "constant part") in which it is finally fixed, where it is welded almost entirely to the constant part of the U-shaped profile of the groove.

[0020] According to the invention, in the combination part, the grooves also each have a tapered portion, which, viewed perpendicular to the longitudinal axis, has a width that gradually decreases with increasing distance from the entrance of the hole, thus achieving that the anchor plate pieces are fed symmetrically to the two side walls of the U-shaped portion of the certain part.

[0021] The grooves each have a constant portion following the mating portion, the constant portion having a width and a depth that are constant along the longitudinal axis when viewed perpendicularly to the longitudinal axis. The width and depth of the U-shaped portions in the constant portions are adapted to the width and thickness of the anchor plate pieces. Before the anchor plate pieces are fixed by friction welding, the U-shaped portions in the holes are slightly narrower than the edges of the anchor plate pieces, and the distance between the two bottom surfaces of the grooves facing each other is slightly smaller than the width of the anchor plate pieces.

[0022] According to the invention, the combination section is configured as both a centering section and a tapered section at the same time, with the advantage that centering and alignment of the anchor plate pieces takes place over as short a distance as possible.

[0023] According to the invention, the combination portion is followed by a fixed portion.

[0024] In many embodiments, the depth decreases in two or more steps, i.e., the centering portion may have two or more straight or curved sub-portions, the angle of the sub-portions with the longitudinal axis decreasing progressively with increasing distance from the entrance of the hole.

[0025] In many embodiments, the width decreases in two or more steps, so that the tapered section may have two or more straight or curved subsections, the angle of the subsection relative to the longitudinal axis decreasing in a progressive manner with increasing distance from the bore entrance.

[0026] In many embodiments, the width of the groove at the entrance to the mating area may be greater than the thickness of the anchor plate piece, in particular by a minimum of 5% and a maximum of 100%. Such a widening of the groove facilitates insertion and improves the symmetry of the load during friction welding in certain parts. The anchor plate piece is preferably rectangular. In particular, it may be advantageous to have no chamfers on the short sides.

[0027] The present invention also relates to a method of manufacturing a toothbrush comprising a plastic brush head and at least one bristle tuft secured within the brush head, comprising the steps of: a) providing a brush head having a hole for fixing at least one bristle bundle, the brush head having a hole with a longitudinal axis and a hole cross-section having a basic shape for accommodating a folded bristle bundle, in which two grooves extending parallel to the longitudinal axis and beyond the basic shape of the hole cross-section are formed in the wall of the hole based on an injection molding technique, the grooves having a combination portion with a centering and tapering portion following the entrance of the hole, the combination portion having a depth and a width, viewed in a direction perpendicular to the longitudinal axis, that gradually decrease with increasing distance from the entrance of the hole, b) providing a plastic anchor plate piece for fixing each folded hair bundle in the hole; c) inserting the anchor plate piece with the folded tufts into the hole, inserting the anchor plate piece into the mating portion of the groove and securing it to the U-shaped formation using a friction welding process.

[0028] Preferably, the grooves each have a constant portion following the mating portion, the constant portions each having a width and depth that are constant along the longitudinal axis when viewed in a direction perpendicular to the longitudinal axis.

[0029] Further advantageous embodiments and feature combinations of the invention are apparent from the detailed description that follows and from the claims as a whole. [Brief description of the drawings]

[0030] To illustrate the example: [Figure 1] FIG. 2 shows a perspective view of multiple rows of holes in a brush head. [Diagram 2] FIG. 2 shows a perspective view of rows of holes with anchor plate pieces inserted therein. [Diagram 3] 1 shows a schematic cross-sectional view of a hole with a centering portion and a constant portion of the groove, along with an anchor plate piece with a hair bundle introduced into the hole. [Figure 4] 4 shows a schematic plan view of the hole shown in FIG. 3. [Diagram 5] 5 shows a schematic cross-sectional view of the hole shown in FIG. 3 and FIG. 4 together with an anchor plate with a hair bundle folded and introduced into the hole. [Figure 6] 6 shows a schematic plan view of the hole shown in FIG. 5. [Figure 7] 1 shows a schematic cross-sectional view of a hole having a groove with a tapered portion, a centering portion, and a constant portion. [Figure 8] 8 shows a schematic plan view of the hole shown in FIG. 7. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] 1 shows a brush head 1 of an embodiment of a toothbrush according to the invention in a perspective view. In this embodiment, multiple rows of cylindrical holes 5 are provided. The basic shape of the holes is therefore circular in cross section. The holes are fitted with folded bristle tufts (not shown) and a corresponding number of plastic anchor plate pieces 3. The holes are preferably formed as blind holes in a one-piece brush head.

[0032] The brush head 1 further comprises a hole 5 with a longitudinal axis L1 for each bristle tuft. In this example, all holes 5 are aligned with their longitudinal axes in the same direction, i.e. perpendicular to the upper main surface of the brush head. Anchoring plate pieces 3 are used to secure each bristle tuft and are fixed in the holes 5. The longitudinal axis L1 is here exactly perpendicular to the surface 4 of the brush head.

[0033] According to an advantageous embodiment, the hole 5 itself is not tapered or flared, i.e. the cross section of the wall 6 is constant along the longitudinal axis L1 of the hole 5. In other words, the wall is substantially parallel to the longitudinal axis L1.

[0034] Each hole has two oppositely aligned grooves 7, 8, here recessed by injection molding techniques into the wall 6 of the hole 5, arranged to receive the anchor plate pieces 3. The grooves extend from the entrance of the hole 5 or the surface 4 of the brush head to a depth of half the bottom of the hole 5.

[0035] In this embodiment, the alignment direction of the hole groove pairs does not run parallel to the row of holes, but is set obliquely at an angle of about 45° to the direction of the row of holes, with the advantage that adjacent hole grooves have a relatively large distance from each other.

[0036] Figure 2 is a view based on Figure 1, where an exemplary anchor plate piece 3 is fixed. The anchor plate piece is approximately rectangular. It is preferably not chamfered on the sides, so that the anchor plate piece can be welded over a large area in a certain part of the groove.

[0037] When inserted, the anchor plate piece 3 is clamped between the grooves 7 and 8 due to the appropriate size of the anchor plate piece 3 being somewhat larger than the distance between the bottom of the grooves 7 and 8, at least in the end position of the anchor plate piece shown here. The anchor plate piece 3 is welded to the U-shaped profiles of the grooves 7 and 8, for example by friction welding or ultrasonic excitation of at least one component contained therein.

[0038] In an embodiment shown in Figures 3 and 4, the two grooves 9, 10 extend continuously to the hole bottom 11. Figure 4 shows the hole 12 in a top view, and Figure 3 shows a cross-section of the hole 12 in the plane S1. In the upper region, the groove has a centering portion Z1, where the groove bottom extends obliquely to the longitudinal axis L2. Following this, the groove has a constant portion K1, where the groove bottom extends parallel to the longitudinal axis L2. Thus, in this case, for clamping and / or welding, the situation can be exploited that the depth T of the grooves 9, 10 decreases starting from the surface 13 or the inlet of the hole 12 along the longitudinal axis L2 into the brush head 14, so that when inserting the anchor plate pieces 15, the anchor plate pieces are fed symmetrically into the grooves. In this case, in particular, the value of the depth T transitions from a maximum value T2 at the entrance of the hole to a minimum value T1 at the end of the centering portion Z1. In other words, the depth T of the groove is a distance value in a first plane S1 / S2 passing through the two grooves perpendicularly to the longitudinal axis L2. Correspondingly, the width B1 is a distance value in a second plane extending perpendicularly to the first plane.

[0039] Based on Figures 3 to 6, we will now explain in detail how the bristle bundle 2 is fixed in the hole 12 by the anchor plate piece 15. By introducing the anchor plate piece 15 into the grooves 9, 10, the bristle bundle 2 is folded, so that when fixing is completed, the bristle bundle protrudes upwards from the hole 12 (see Figures 5 and 6). Here, Figure 5 is a view of the cross section S2 marked in Figure 6. It can be seen how the anchor plate piece 15 is clamped in the groove.

[0040] The two parts, namely the brush head 14 and the anchor plate piece 15, are made of plastic, in particular of the same material, and both parts can be welded together.

[0041] In this embodiment of figures 3 to 6, apart from other optional aspects, yet another optional feature that can be used in various embodiments is observed: the width B1 of the mating part of the groove is in particular at least 5% (for example up to 10%) wider at the hole edge than the thickness D of the anchor plate piece 15. At the point where the mating part abuts the constant part, the width of the mating part has the same width as the constant part.

[0042] If an even more precise and more stable assembly is desired, the grooves can be modified by also being provided with a tapered section V according to the embodiment shown in figures 7 and 8. Figure 7 shows a view of the section S3 marked in figure 8. This embodiment shown there is based on the embodiment shown in figures 1 and 2. Looking in the direction S3, the depth decreases progressively. In this case, the width B of the grooves 16, 17 likewise decreases progressively with increasing distance from the inlet of the hole 20 in the surface 18 of the brush head 19, respectively. This additional taper serves to ensure that when inserting the anchor plate pieces (not shown here) into the grooves, they are centered and loaded symmetrically in two axes when introduced into the fixed part based on the friction welding technique.

[0043] Moreover, in the embodiment according to figures 7 and 8, yet another optional feature is shown, which can be applied to various embodiments, apart from the other optional features. The centering portion Z2 and the tapered portion V (only one of the two tapered portions is also possible) are here both configured in two stages, i.e. in a first stage, the groove tapers from the brush head surface 18 downwards at a first angle, and in a second stage following the first stage, the groove tapers again, but at a second angle smaller than the first angle. In this case, the third stage (constant portion K2) up to the step of the groove 16, 17 is parallel to the longitudinal axis L3 as shown, but can of course also be configured obliquely. In the embodiment according to figures 3 to 6, the taper of the depth of the groove can be configured in more than two stages.

[0044] Although the present invention has been described based on its preferred embodiments, many further variations and modifications may be made without departing from the scope of the present invention. It is therefore contemplated that the appended claims will cover such variations and modifications as fall within the scope of the actual invention.

Claims

1. A toothbrush, comprising: a plastic brush head (1, 4, 19), at least one folded tuft (2), and at least one plastic anchor plate piece (3, 15), the brush head (1, 14, 19) has holes (5, 12, 20) having a longitudinal axis (L1, L2, L3) and a hole cross-section with a basic shape for accommodating the folded tuft (2), and the anchor plate pieces (3, 15) are fixed within the holes (5, 12, 20) to fix the respective tufts (2), in the toothbrush, two grooves (7, 8, 9, 10, 16, 17) are formed on the walls of the holes (5, 12, 20) based on injection molding technology, extending parallel to the longitudinal axis (L1, L2, L3) and beyond the basic shape of the hole cross-section, the anchor plate pieces (3, 15) are fixed to the two grooves (7, 8, 9, 10, 16, 17) as U-shaped formed parts by welding, the grooves (7, 8, 9, 10, 16, 17) have a combination part having a centering and taper part (Z1, Z2) following the entrance of the hole, and the combination part has a depth (T) and a width (B) that gradually decrease as the distance from the entrance of the holes (5, 12, 20) increases when viewed in a direction (S1, S2, S3) perpendicular to the longitudinal axis (L1, L2, L3), characterized in that it is a toothbrush.

2. the grooves (7, 8, 9, 10, 16, 17) each have a constant part (K2), and the constant part (K2) has a width (B1) and a depth (T1) that are constant along the longitudinal axis (L1, L2, L3) when viewed in a direction (S1, S2, S3) perpendicular to the longitudinal axis (L1, L2, L3), the toothbrush according to claim 1.

3. the depth (T) decreases in two steps, the toothbrush according to claim 1 or 2.

4. the width (B) decreases in two steps, the toothbrush according to claim 1 or 2.

5. the width (B1) is larger than the thickness (D) of the anchor plate pieces (3, 15), particularly at least 5% and particularly at most 100% larger, the toothbrush according to claim 2.

6. the fixing direction formed by the grooves facing each other is at an angle greater than 0° with respect to the hole row direction of directly adjacent holes, the toothbrush according to claim 1 or 2.

7. In a method of manufacturing a toothbrush having a plastic brush head (1, 14, 19) and at least one tuft of bristles fixed to the brush head, a) preparing a brush head (1, 14, 19) having holes for fixing at least one tuft of bristles (2), wherein the brush head (1, 14, 19) has holes (5, 12, 20) having a longitudinal axis (L1, L2, L3) and a hole cross-section having a basic shape for accommodating the folded tuft of bristles (2), and on the walls of the holes (5, 12, 20), two grooves (7, 8, 9, 10, 16, 17) are formed based on injection molding technology, which extend parallel to the longitudinal axis (L1, L2, L3) and extend beyond the basic shape of the hole cross-section, and the grooves (7, 8, 9, 10, 16, 17) have a combined portion having a centering and tapered portion (Z1, Z2) following the entrance of the hole, and the combined portion has a depth (T) and a width (B) that gradually decrease as the distance from the entrance of the hole (5, 12, 20) increases when viewed in a direction (S1, S2, S3) perpendicular to the longitudinal axis (L1, L2, L3), step, b) preparing plastic anchor plate pieces for fixing the folded tufts of bristles (2) in the holes (5, 12, 20), respectively, step, c) inserting the anchor plate piece having the folded tuft of bristles into the hole, introducing the anchor plate piece into the combined portion of the groove, and fixing it to the U-shaped forming portion by a friction welding process, a method having the step.

8. The groove (7, 8, 9, 10, 16, 17) has a constant portion (K2), and the constant portion (K2) has a width (B1) and a depth (T1) that are constant along the longitudinal axis (L1, L2, L3) when viewed in a direction (S1, S2, S3) perpendicular to the longitudinal axis (L1, L2, L3), respectively. The method according to claim 7.

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