DE9418843U1 - toothbrush - Google Patents

Description

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ng. HEINER LICHTI

DIPL.-PHYS. DR. RER. NAT. JOST LEMPERT D-76207 KARLSRUHE (DURLACH)

PO BOX 410760

DIPL.-ING. HARTMUT LASCH PHONE: (O72D94328I5 FAX: (0721)9432840

CORONET-Werke GmbH
69483 Wald-Michelbach

12800.7

22 November 1994

toothbrush

The invention relates to a toothbrush made of plastic, in which the essentially rigid brush head is connected to the essentially rigid handle in a tapered transition region via a spring part and the spring part is embedded in the plastic.

The toothbrush has been the standard care device in oral hygiene for more than 100 years. It is not only used to clean the teeth and interdental spaces, but is also often intended to have a massage effect on the gingiva or its edge areas. It is precisely this additional effect that has led to the development of special design measures. This includes in particular the formation of a springy connection between the brush head and handle, which in turn are made of a relatively rigid plastic, usually by injection molding, for reasons of stability.

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Various designs are known for achieving a resilient connection between the brush head and handle. Only a few representative designs are mentioned here. According to FR 1 247 433, the head is "split" lengthwise up to the handle area and the resulting strip-shaped parts, each of which is separately covered with bristles, are covered by a clamping ring, by means of which the free length of the strips and thus the flexibility of this area, which is more elastic than the handle, can be adjusted. This design is complex in terms of construction and use. It is also questionable from a hygienic point of view due to the existing gap. The same applies to another design (US 4 520 526), in which the toothbrush is weakened in the transition area between the head and handle by recesses in the plastic in order to give this area greater resilience. Dirt, dental care product residues, bacteria, etc. can also accumulate here.

0. The same applies to designs where strong profiling is provided in the transition area (EP 0 281 017).

From a hygienic point of view, preference should therefore be given to those designs in which the transition between the brush head and handle is essentially smooth-walled, but a spring effect is implemented in this area. It is known (DE 93 10 112 Ul, DE 3 8 4 0 13 6) to insert a leaf spring in the transition area between the handle and brush head and to embed this completely in the plastic. The leaf spring ensures that the toothbrush does not retreat if too much pressure is applied, but that sufficient pressure is always applied when the toothbrush is guided correctly.

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Even if the versions with leaf springs made of metal are largely satisfactory in terms of use, they do have other disadvantages. Firstly, there is the problem in terms of production technology that the leaf spring has to be injected into the plastic, which requires corresponding structural precautions on the injection mold. Secondly, leaf springs are difficult to handle in the production process, both manually and with manipulators, due to their extremely thin walls, and are difficult to position in the injection molding machine. Finally, the large-surface and thin-walled leaf spring leads to uncontrolled shrinkage processes in the plastic surrounding it when the mold is sprayed, which reduces the quality, especially considering the fact that the plastic mass in this narrow transition area is very small anyway. In terms of use, there is the disadvantage that the brush head only springs in the direction perpendicular to the working plane of the bristles, but is extremely rigid in all directions deviating from this.

The invention is based on the object of proposing a toothbrush which is simple to manufacture and cost-effective as well as inexpensive to use.

This object is achieved according to the invention in that 0 the spring part has a substantially circular cross-section.

The invention firstly offers the advantage that the toothbrush in the transition area between the brush head

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and handle can be made very slim, since the circular cross-section of the spring part - in contrast to a leaf spring - has the same extension in all axes. The slim design made possible by this has the advantage in terms of use that the cleaning movements can be carried out with the mouth closed.

The round spring provided according to the invention also has the advantage that the brush head can move not only perpendicular to the working plane of the bristles, but also in all other directions, depending on the direction in which the user applies the greatest pressure. Round springs are also easier to handle when inserting into the injection mold and are also easier to position in the mold. Finally, round springs have the advantage that they exhibit the same thermal behavior in all cross-sectional axes, so that the plastic around the round spring is subjected to uniform shrinkage forces. This ensures that the round spring is optimally embedded on the one hand, and on the other hand there are no distortions on the plastic surface.

In a preferred embodiment, the plastic covering the spring part in the transition area has a cross-section whose moment of inertia in the axis running perpendicular to the working plane of the bristles is greater than in relation to any other axis. This ensures that the springing is only or primarily possible in the direction of the axis with the smaller moment of inertia. This axis is essentially parallel to the bristles. By designing the cross-sectional shape accordingly, a less pronounced spring capacity can also be achieved outside the axis with

the smallest moment of inertia, so that torsional movements between the handle and the brush head are possible or can be absorbed by springs.

Preferably, the spring part consists of a metal round wire, e.g. spring steel. Instead, the spring part can also consist of a fiber bundle, a plastic with spring properties or a fiber-reinforced plastic, whereby glass fibers are preferably used. This spring part can be injection molded separately and then inserted into the injection mold of the toothbrush or injection molded integrated.

The spring part can have a flat or oval cross-section in order to influence the type of rebound of the brush head. This rebound can be provided not only against the pressure on the tooth surface, but also, to at least a limited extent, transversely or in any direction. 20

In a further preferred embodiment, the spring part has projections extending transversely to its extent. These projections can initially serve as a simple aid for positioning in the injection mold and for holding the position during injection molding. Furthermore, the spring part is "centered" in the plastic mass surrounding it and anchored with its ends in the larger cross section of the bristle handle and brush head.

0 The projections can be easily obtained by compressing, bending, folding or embossing.

The invention is described below with reference to an embodiment shown in the drawing. In

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the drawing shows:

Figure 1 is a partially sectioned longitudinal view

a toothbrush;
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Figure 2 is a plan view of the representation according to

Figure 1;

Figure 3 shows an enlarged section III-III according to Figure 2 and

Figure 4 is an enlarged section in the area "X" of Figure 1.

The toothbrush according to Figure 1 consists of a brush head 1 with bristles and an elongated handle 2, which are both connected to each other via a slim transition area 3.

0 In the transition area 3 from the brush head 1 to the handle 2 a spring part 4 is embedded. For example, the entire toothbrush is manufactured by injection molding and the spring part 4 is molded around. The spring part 4 is therefore surrounded by plastic on all sides, so that the toothbrush has a uniform appearance.

The spring part 4 has a circular cross-section and consists, for example, of a round wire. This allows the transition area 3 to be given a particularly slim shape. A uniform spring capacity on all sides is achieved when the cross-section of the plastic surrounding the spring part is also circular. In order to enable an oriented springing of the brush head 1, the cross-section in the embodiment shown is

The plastic covering the spring part is not rotationally symmetrical in the transition area 3, but rather has two axes 5, 6 of different lengths, of which axis 5 is shorter, so that the smaller moment of inertia is present in this axis, and therefore the rebound occurs in this axis. Adjacent to this axis, the spring capacity decreases in the other directions. By using a different cross-sectional shape, e.g. an oval or elliptical shape, the spring capacity can be continuously varied across the entire cross-section.

The spring part 4 has projections 7 and 8 in the area of its end that run transversely to its extension. These projections can be used for positioning within the injection mold. They are preferably located outside the transition area 3 in the area of the brush head 1 and handle 3. The projections 7, 8 of the spring part 4 can be embossings of the round wire.

Claims (10)

DiPLiNG. HEINER LICHTI DlPL-PHYS. dr. RER. NAT. JOST LEMPERT D-76207 KARLSRUHE (DURLACH) PO BOX 410760 DIPL.-ING. HARTMUT LASCH TELEPHONE: (0721) 9432815 FAX: (0721) 9432840 CORONET-Werke GmbH
69483 Wald-Michelbach 12800.7 22 November 1994 Protection claims 1. Toothbrush made of plastic, in which the essentially rigid brush head is connected to the essentially rigid handle in a tapered transition region via a spring part and the spring part is embedded in the plastic, characterized in that the spring part (4) has an essentially circular cross-section. 2. Toothbrush according to claim 1, characterized in that the plastic enveloping the spring part (4) in the transition region (3) has a cross-section whose moment of inertia in the axis (6) running perpendicular to the working plane is greater than in relation to any other axis (5). 3. Toothbrush according to claim 1 or 2, characterized in that the spring part (4) consists of a metallic see round wire. 4. Toothbrush according to one of claims 1-3, characterized in that the spring part (4) consists of spring steel. 5. Toothbrush according to claim 1 or 2, characterized in that the spring part (4) consists of a fiber bundle or a fiber-reinforced plastic. 6. Toothbrush according to claim 5, characterized in that the spring part (4) consists of a glass fiber reinforced plastic. 7. Toothbrush according to claim 1 or 2, characterized in that the spring part (4) consists of a plastic with spring properties. 8. Toothbrush according to one of claims 1 to 7, characterized 0 characterized in that the spring part (4) has projections (7, 8) transverse to its extension. 9. Toothbrush according to claim 8, characterized in that the projections (7, 8) are provided at the ends of the spring part (4) embedded in the brush head (1) or in the handle (2). 10. Toothbrush according to claim 7 or 9, characterized in that the projections (7, 8) are obtained by compressing, bending, folding or embossing the round wire.