Toothbrush

Abstract

The invention relates to a toothbrush comprising a brush head, at least one folded bristle bundle, and at least one anchor plate made of plastic, wherein the brush head has a hole with a longitudinal axis for the at least one bristle bundle, an anchor plate is fixed in the hole in order to anchor the bristle bundle in question, the anchor plate is retained in two grooves which run parallel to the longitudinal axis and which are formed in the hole by injection molding, and the grooves have a centering portion which has, viewed in a direction perpendicular to the longitudinal axis, a depth that gradually decreases with increasing distance from an entrance of the hole.

Description

[0001] TITLE:

[0002] toothbrush

[0003] DESCRIPTION

[0004] Technical area

[0005] The invention relates to a toothbrush with a brush head made of plastic with at least one folded bundle of bristles and at least one anchor plate made of plastic.

[0006] State of the art

[0007] Conventionally, during toothbrush manufacturing, the bristle bundles are secured to the brush body with metal anchor plates. These anchor plates are, for example, 3 / 10 mm wider than the hole diameter. The anchor plates are stuffed into the bristle bundle holes along with folded bristle bundles, digging their opposing outer edges into the brush body material and thus being held in place.

[0008] Furthermore, it has already been proposed that, in a metal brush head, the bristle bundles be secured by metal anchors. Holes for the bristle bundles are drilled in the brush head, and at each of these holes, small holes are drilled diametrically opposite each other for inserting the metal anchors (JP 2009 125084 A, KAO CORP).

[0009] The known anchoring techniques are complex in production and have insufficient reliability in fixing the bristle bundles.

[0010] Description of the invention

[0011] The object of the invention is to create a toothbrush belonging to the aforementioned technical field that is easier to manufacture and ensures more reliable anchoring of the bristles. The solution to this problem is defined by the features of claim 1.

[0012] The toothbrush according to the invention has a brush head made of plastic, at least one folded bundle of bristles, and at least one anchor plate made of plastic. The brush head has a hole for the at least one bundle of bristles, said hole having a longitudinal axis and a hole cross-section with a basic shape for receiving the folded bundle of bristles. To anchor the respective bundle of bristles in the free hole cross-section, an anchor plate is fixed in the hole. In one wall of the hole, two grooves running parallel to the longitudinal axis of the hole are held, which (viewed perpendicular to the longitudinal axis) extend beyond the basic shape of the hole cross-section and which are formed by injection molding. The grooves form a U-shaped profile. The anchor plate is fixed in the two grooves in the U-shaped profile by welding.The grooves have, adjacent to an entrance of the hole, a combination section with a centering and tapering section, which, viewed in a direction perpendicular to the longitudinal axis, has a depth and a width that decrease successively with increasing distance from an entrance of the hole.

[0013] The invention is based on the realization that without the combination section according to the invention it is not possible to anchor the plastic anchors sufficiently firmly (i.e. with sufficiently high pull-out force) and sufficiently reliably (i.e. with sufficient consistency with each weld). Tests have shown that if the feeding is insufficiently symmetrical (e.g. due to a slight production-related offset between the grooves and the anchor plate), the anchor plates are either deformed when inserted into the holes and are therefore only partially welded, or that the welding only occurs in individual places because the contact between the edge of the anchor plate and three wall sides of the U-profile is insufficient in other places. In this context, it has also been shown that significantly higher pull-out forces are achieved for the bristle nuts when anchor plates are welded to all three sides of a U-shaped groove.

[0014] The tests also showed that it is important that the U-shaped grooves are embedded in the volume material of the brush head. If the wall surrounding the groove is too slack, the softened plastic material can yield, significantly reducing stability. Plastic anchor plates have the advantage over steel ones in that they allow for easy, environmentally friendly disposal of the toothbrush, because material separation (metal / plastic) is not necessary.

[0015] Preferably, the longitudinal axis of the hole is perpendicular to a surface of the brush head. Several parallel rows of holes can be provided in the brush head at close intervals.

[0016] According to a special design, the hole (viewed transversely to its longitudinal axis) has a geometrically simple basic shape such as a circle, a rectangle or an ellipse.

[0017] The grooves are recessed into the wall of the hole, meaning they extend beyond the basic shape of the hole's cross-section and into the bulk material of the brush head. The grooves are already present in the hole when the bristles and anchor plates are inserted. They are applied by injection molding, i.e., during the injection molding of the brush head.

[0018] The wall is therefore preferably essentially the inner surface of a hollow cylinder or a rectangular or elliptical hollow profile defined by the hole. The wall is therefore essentially parallel to the longitudinal axis of the hole.

[0019] According to the invention, the grooves have a U-shaped cross-section (viewed perpendicular to the longitudinal axis of the hole). Because the grooves are recessed into the wall and not, for example, mounted on a rib that protrudes into the (free) hole cross-section, the three wall sides of the U-profile are surrounded by the volume material of the brush head. The heating and softening of the material that inevitably occurs during welding in the U-profile cannot therefore lead to the plastic material slipping. The anchor plate is thus reliably fixed both to the front side (base of the U-profile) and to the edge sides of the U-profile.

[0020] In order not to weaken the wall between closely spaced holes in a row and to ensure sufficient spacing between the grooves of adjacent holes, in a special embodiment the basic shape of the holes is circular or elliptical and the alignment defined by the opposing grooves of a hole is offset by an angle greater than zero, in particular by 30°-45°, from the direction of the row of holes (hole row direction of immediately adjacent holes). Because the basic shape is simple (circular, elliptical, rectangular or the like), i.e. convex (i.e. has no indentations, such as ribs or inward projections) and the grooves are recessed into the wall, the hole cross-section can be optimally adapted to the tuft of bristles to be inserted.

[0021] At the entrance to the hole and thus at the entrance to the grooves, the combination section forms, on the one hand, a centering section of the U-shaped profile. This tapers radially relative to the longitudinal axis of the hole, forming the insertion area or insertion path for the anchor plate. On the one hand, this centers the anchor plate (e.g., relative to the longitudinal axis of the hole), and on the other hand, as it is inserted, the anchor plate is gradually guided to the area (referred to below as the "constant section") where the anchor plate is finally fixed. There, the anchor plate is essentially welded over its entire surface to the plastic section of the U-profile of the grooves.

[0022] According to the invention, the grooves in the combination section also each have a tapered section, which, viewed in the direction perpendicular to the longitudinal axis, has a width that gradually decreases with increasing distance from the hole entrance. This ensures that the anchor plate is fed symmetrically to the two side walls of the U-profile in the constant section.

[0023] Adjacent to the combination section, the grooves each have a constant section, which, viewed in the direction perpendicular to the longitudinal axis, has a width and depth that are constant along the longitudinal axis. The width and depth of the U-profile in the constant section are adapted to the width and thickness of the anchor plate. Before the anchor plate is secured by friction welding, the U-profile in the hole is slightly less wide than the edge of the anchor plate, and the distance between the two base surfaces of the opposing grooves is slightly less than the width of the anchor plate.

[0024] According to the invention, the combination section is designed as both a centering section and a tapered section. This has the advantage that the centering and alignment of the anchor plate takes place over the shortest possible distance.

[0025] According to the invention, the combination section is followed by the constant section.

[0026] In some embodiments, the depth decreases in two or more stages. For this purpose, the centering section can have two or more linear or curved subsections whose angle with the longitudinal axis decreases successively with increasing distance from the hole entrance.

[0027] In some embodiments, the width decreases in two or more stages. For this purpose, the tapered section can have two or more linear or curved subsections whose angle with the longitudinal axis decreases successively with increasing distance from the hole entrance.

[0028] In some embodiments, the width of the grooves at the entrance to the combination area can be greater than the thickness of the anchor plate, specifically by at least 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 the constant section. The anchor plate is preferably rectangular. In particular, it can be advantageous if it has no chamfers on the narrow sides.

[0029] The invention also relates to a method for producing a toothbrush with a brush head made of plastic and with at least one bundle of bristles anchored in the brush head, comprising the steps of: a) providing a brush head with a hole for fixing the at least one bundle of bristles, a hole with a longitudinal axis and a hole cross-section with a basic shape for receiving the folded bundle of bristles, wherein two grooves running parallel to the longitudinal axis and extending beyond the basic shape of the hole cross-section are injection-molded in a wall of the hole, wherein the grooves have, adjacent to an inlet of the hole, a combination section with a centering and tapering section, which, viewed in a direction perpendicular to the longitudinal axis, has a depth (T) and a width (B) which successively decrease with increasing distance from an inlet of the hole.b) providing a plastic anchor plate for anchoring the respective folded bristle bundle in the hole; c) inserting the anchor plate with the folded bristle bundle into the hole, wherein the anchor plate is inserted into the combination section of the grooves and fixed in the U-profile using a friction welding process. Preferably, the grooves each have a constant section that, viewed in a direction perpendicular to the longitudinal axis, has a width and depth that are constant along the longitudinal axis.

[0030] Further advantageous embodiments and combinations of features of the invention emerge from the following detailed description and the entirety of the patent claims.

[0031] Short description of the drawings

[0032] To explain examples of implementation, see:

[0033] Figure 1 is a perspective view of several rows of holes in a brush head;

[0034] Figure 2 is a perspective view of several rows of holes with an inserted anchor plate;

[0035] Figure 3 is a schematic sectional view of a hole with anchor plates capable of introducing a bundle of bristles into the hole, and a centering section and a constant section of the grooves;

[0036] Figure 4 is a schematic plan view of the hole shown in Figure 3;

[0037] Figure 5 is a schematic sectional view of the hole from Figures 3 and 4 with

[0038] Anchor plate that folded the bundle of bristles and inserted them into the hole;

[0039] Figure 6 is a schematic plan view of the hole shown in Figure 5;

[0040] Figure 7 is a schematic sectional view of a hole with grooves having a tapered section, a centering section and a constant section; and

[0041] Figure 8 is a schematic plan view of the hole shown in Figure 7. Ways of implementing the invention

[0042] Figure 1 shows a transparent brush head 1 of an embodiment of the toothbrush according to the invention. This embodiment has a plurality of circular-cylindrical holes 5 in several rows. The basic shape of the hole in longitudinal cross-section is thus a circle. Folded bundles of bristles (not shown) and a corresponding plurality of plastic anchor plates 3 are inserted into the holes. The holes are preferably formed as blind holes in the one-piece brush head.

[0043] The brush head 1 also has a hole 5 with a longitudinal axis L1 for each bristle bundle. In the present example, all holes 5 are aligned equally with their longitudinal axes, namely perpendicular to the upper main surface of the brush head. The anchor plate 3 serves to anchor the respective bristle bundle and is fixed in the hole 5. The longitudinal axis L1 is exactly perpendicular to a surface 4 of the brush head.

[0044] According to an advantageous embodiment, the hole 5 as such does not taper or widen, i.e., a 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.

[0045] Each hole now has two grooves 7 and 8, injection-molded into the wall 6 of the hole 5, opposite each other and aligned parallel to the longitudinal axis L1, which are designed to receive the anchor plate 3. The grooves extend from the entrance of the hole 5 or from the surface 4 of the brush head to a depth in the lower half of the hole 5.

[0046] In the present embodiment, the alignment of the groove pair of a hole is not parallel to the row of holes, but is inclined at an angle of approximately 45° to the direction of the row of holes. This has the advantage that the grooves of adjacent holes are relatively far apart.

[0047] Figure 2 shows the view from Figure 1, with the exemplary anchor plate 3 fixed here. The anchor plate is essentially rectangular. Preferably, it has no bevels on the sides. This allows the anchor plate to be welded over a large area in the constant section of the slots. When pushed in, the anchor plate 3 is clamped between the slots 7 and 8 in that the corresponding dimension of the anchor plate 3 is a certain amount higher than the distance between the bottoms of the slots 7 and 8, at least in the end position of the anchor plate shown here. The anchor plate 3 is welded to the U-profiles of the slots 7 and 8, e.g. by friction welding or by ultrasonic excitation of at least one of the components involved.

[0048] 3 and 4, the two grooves 9 and 10 run continuously down to the hole base 11. Figure 4 is a plan view of the hole 12 and Figure 3 is a section through the hole 12 in the plane S1. In the upper area the groove has a centering section Z1, in which the groove base runs obliquely to the longitudinal axis L2. Adjacent to this the groove has a constant section l<1, in which the groove base runs parallel to the longitudinal axis L2. In this case the fact that a depth T of the grooves 9 and 10, viewed along the longitudinal axis L2 and starting from the surface 13 or the entrance of the hole 12 into the brush head 14, decreases and that when the anchor plate 15 is pushed in the anchor plate is fed symmetrically into the.In particular, the value of the depth T extends from the maximum T2 at the entrance of the hole to the minimum T1 at the end of the centering section Z1. In other words, the depth T of the groove is a distance value in a first plane S1 / S2, which runs through the longitudinal axis L2 and perpendicularly through the two grooves. Accordingly, the width B1 is a distance value in a second plane, which runs perpendicular to the first plane.

[0049] Figures 3 to 6 illustrate how the bristle bundle 2 is anchored in the hole 12 by the anchor plate 15. By inserting the anchor plate 15 into the grooves 9 and 10, the bristle bundle 2 is folded so that, after anchoring, the bristles protrude upwards out of the hole 12 (see Figures 5 and 6). Figure 5 is a view of section S2 marked in Figure 6. It also shows how the anchor plate 15 has become jammed in the groove.

[0050] Both parts, bristle head 14 and anchor plate 15, are made of plastic, in particular of the same material, and both parts can be welded.

[0051] In this embodiment of Figures 3 to 6, a further optional aspect can also be seen, which can be used independently of other optional aspects in various embodiments: The width B 1 in the combination section of the grooves is wider at the hole edge, in particular by at least 5% (e.g., a maximum of 10%), than the thickness D of the anchor plate 15. Where the combination section meets the constant section, the width of the combination section is the same as the constant section.

[0052] If an even more precise and stable assembly is desired, the grooves can be modified according to the embodiment shown in Figures 7 and 8 by also providing a tapered section V. Figure 7 is a view of the section S3 marked in Figure 8. This embodiment shown here is based on the embodiment shown in Figures 1 and 2. Viewed in the direction S3, the depth decreases successively. The width B of the grooves 16 and 17 also decreases successively with increasing distance from the entrance of the hole 20 on the surface 18 of the brush head 19. This additional taper has the effect that the anchor plate (not shown here) is biaxially centered and symmetrically loaded when pushed into the grooves during friction welding into the constant section.

[0053] 7 and 8, a further optional aspect is also shown, which can also be used independently of other optional aspects in various embodiments: the centering section Z2 and the tapering section V (only one of the two tapers would also be possible) are both designed in two stages, i.e. a first stage from the brush head surface 18 downwards tapers the groove at a first angle and a second stage following the first stage tapers the groove again, but at a second angle which is smaller than the first angle. A third phase (constant section l<2) up to the offset of the grooves 16 and 17 is then parallel to the longitudinal axis L3 as shown, but could also be designed at an angle. In the embodiment according to Figures 3 to 6, the taper of the depth of the groove could also be designed in two or more stages.

[0054] While the invention has been described in terms of its preferred embodiment(s), many other changes and variations may be made without departing from the scope of the present invention. Therefore, it is intended that the appended claims cover such changes and variations as fall within the true scope of the invention.

Claims

Patent claims 1. Toothbrush with a brush head (1, 14, 19) made of plastic, at least one folded bristle bundle (2) and at least one anchor plate (3, 15) made of plastic, wherein the brush head (1, 14, 19) has a hole (5, 12, 20) for the at least one bristle bundle (2) with a longitudinal axis (L1, L2, L3) and a hole cross-section with a basic shape for receiving the folded bristle bundle (2), wherein an anchor plate (3, 15) is fixed in the hole (5, 12, 20) for anchoring the respective bristle bundle (2), wherein two grooves (7, 8, 9, 10, 16, 17) extending parallel to the longitudinal axis (L1, L2, L3) and extending beyond the basic shape of the hole cross-section are injection molded into a wall of the hole (5, 12, 20). characterized in that the anchor plate (3, 15) is fixed in the two grooves (7, 8, 9, 10, 16, 17) in the u-shaped profile by a weld the grooves (7, 8, 9, 10, 16,17) following an entrance of the hole, have a combination section with a centering and tapering section (Z1, Z2) which, viewed in a direction (S1, S2, S3) perpendicular to the longitudinal axis (L1, L2, L3), has a depth (T) and a width (B) that decrease successively with increasing distance from an entrance of the hole (5, 12, 20).

2. Toothbrush according to claim 1, wherein the grooves (7, 8, 9, 10, 16, 17) each have a constant section (l<2) which, viewed in the direction (S 1 ,S 2,S3) perpendicular to the longitudinal axis (L1,L2,L3), has a width (B 1) and a depth (T 1) which are constant along the longitudinal axis (L1,L2,L3).

3. Toothbrush according to one of the preceding claims, wherein the depth (T) decreases in two stages. A toothbrush according to any of the preceding claims, wherein the width (B) decreases in two stages. A toothbrush according to any of the preceding claims, wherein the width (B1) is greater than a thickness (D) of the anchor plate (3, 15), in particular by at least 5% and in particular by a maximum of 100%. A toothbrush according to any of the preceding claims, wherein an anchor direction formed by the opposing grooves is at an angle greater than zero to a hole row direction of immediately adjacent holes. Method for manufacturing a toothbrush with a brush head (1, 14, 19) made of plastic and with at least one bristle bundle anchored in the brush head, comprising the steps of: a) providing a brush head (1, 14, 19) with a hole for fixing the at least one bristle bundle (2), the brush head having a hole (5, 12, 20) with a longitudinal axis (L1, L2, L3) and a hole cross-section with a basic shape for receiving the folded bristle bundle (2), wherein a wall of the hole (5, 12,20) Two grooves (7, 8, 9, 10, 16, 17) extending parallel to the longitudinal axis (L1, L2, L3) and extending beyond the basic shape of the hole cross-section are formed by injection molding, wherein the grooves (7, 8, 9, 10, 16, 17) have a combination section with a centering and tapering section (Z1, Z2) following an entrance of the hole, which, viewed in a direction (S1, S2, S3) perpendicular to the longitudinal axis (L1, L2, L3), has a depth (T) and a width (B) that decrease successively with increasing distance from an entrance of the hole (5, 12, 20). b) providing a plastic anchor plate for anchoring the respective folded bristle bundle (2) in the hole (5, 12, 20), c) inserting the anchor plate with the folded bristle bundle into the hole, wherein the anchor plate is inserted into the combination section of the grooves and fixed in the u-profile by a friction welding process. Method according to claim 7, wherein the grooves (7, 8, 9, 10, 16,17) each have a constant section (l<2) that is perpendicular to the longitudinal axis in the direction (S 1 , S 2, S 3), (L1,L2,L3) considers a width (B 1) and a depth (T 1) that are constant along the longitudinal axis (L1 ,L2,L3).

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