Toothbrush having a flexibly linked zone between head and handle

This patent application is a divisional application from PCT/EP 92/00645 - 92906554.8.

The present invention relates to a novel article, being a toothbrush, and in particular to a toothbrush having a flexibly linked zone in its head.

When brushing one's teeth, particularly with a conventional toothbrush having a rigid head, it can be difficult to reach all parts of the teeth in order to brush the teeth satisfactorily. It is also difficult with such brushes to maintain an optimum angle between the teeth and the head of the toothbrush for effective brushing and cleaning, necessitating continual repositioning of the brush in the hand throughout the brushing process. Consequently, there is a tendency to apply excess brushing pressure to some teeth and insufficient pressure to other teeth. The resultant combination of excess brushing pressure and inadequate cleaning or bad cleaning technique can result in damage to both teeth and gums.

Although angled-head toothbrushes have been suggested as an attempt to overcome some of these difficulties, they do not satisfactorily meet all the requirements.

Proposals have also been made for toothbrushes having flexible handles or flexible zones in their handles to assist in accommodating the orientation of the bristle-bearing head of the brush to the profile of a user's teeth and gums. Such toothbrushes are disclosed for example in EP-A-0336641 which discloses a toothbrush having "S" folds in its handle, US 4520526, DE-OL-3640898 which discloses a toothbrush having a thinned resilient neck, DE-OL-3612108, CH-0155730 which discloses a toothbrush having cut-outs in its neck, and IT-485123. DE 3923495 (=US 5054154) discloses a toothbrush having a handle in which there are slots filled with an elastomeric material, these slots being in a part of the handle distant from the head. US 4488328 discloses a toothbrush having its head pivotally mounted between the arms of a yoke structure. US 4575894 discloses a toothbrush in which a rubber pad is included in the head. US 4520526 discloses a toothbrush in which the neck region is made more flexible by cut outs. US 759490 discloses a toothbrush with a flexible link between its head and handle.

In some circumstances it is desirable to further improve the flexibility of the head relative to the direction of the handle of the toothbrush.

According to the present invention a toothbrush is provided according to claim 1.

The toothbrush head of this invention can move, particularly in a rocking movement, relative to the handle and can thereby accommodate itself better to the shape of the teeth than might be the case with a completely rigid toothbrush. Moreover the ability of the head to "float" relative to the handle enables a much more gentle brushing action, reducing the likelihood of injury to the gums of the user.

The bristles on the head may be distributed over the head in a pattern which is conventional in toothbrush manufacture. The bristles may be distributed uniformly over the head but are preferably in discrete tufts each containing a number of bristles.

In embodiments of the toothbrush of the invention the flexible link may be achieved in a number of ways, as defined in the sub-claims.

The elastomeric material may be coloured differently to the head and/or the handle for aesthetic reasons or to emphasize the construction of the toothbrush.

The spine may extend in a direction generally in line with the longitudinal axis of the toothbrush between the handle and the head, and be thin, flexible and resilient.

The head may rock relative to the handle about a number of axes. Preferably the head is at least able to rock in the plane that contains the longitudinal axis of the handle.

The head and the spine may be made in the same moulding operation.

The handle, head and bristles of the toothbrush of the invention may be made of materials which are conventional in the manufacture of toothbrushes, especially plastics materials. Suitable plastics materials include, for example, polyamides and polypropylenes. An example of a suitable polyamide is the material 'Ultramid B3'(Trade mark, marketed by BASF, Federal Republic of Germany), having a modulus of elasticity (DIN 53452) of 3000. An example of a suitable polypropylene is the material 'Novolene 1100 HX' (Trade mark, marketed by BASF, Federal Republic of Germany), which is a homopolymer and has a modulus of elasticity (DIN 53457) of 1400. Such a polypropylene homopolymer may optionally be used in admixture with a polypropylene block co-polymer, such as the material 'Novolene 2500 HX' (Trade mark, marketed by BASF, Federal Republic of Germany), for example in an 80 : 20 mixture by weight (1100 HX : 2500 HX). Suitable elastomeric materials include natural or synthetic latex type elastomers, in particular polychloroprene, natural rubber and silicones.

The handle may be of a shape which is conventional in the manufacture of toothbrushes. It may however be advantageously made in the form described in EP 0336641 A, the contents of which are included by reference, more particularly as described in column 1 lines 36 - 49 thereof.

In use, the toothbrush of this invention may be used for cleaning the teeth by an entirely conventional toothbrushing hand action, preferably in a manner recommended by dental health authorities. The toothbrush of the invention may also be used in electrically driven toothbrushes.

The invention will now be described by way of example only, with reference to the accompanying drawings, in which: <ul id="ul0001" list-style="none" compact="compact"><li>Fig 1 shows a toothbrush of the invention.</li></ul>

Referring to Fig 1, the bristle-bearing portion of a toothbrush of the invention is shown in a top view in Fig 1A, in an underside view in Fig 1B, and in an overall side view in Fig 1C.

In the toothbrush of Fig 1, the handle (part shown 11), has an end which is integrally formed into an extended portion (12) in the shape of a thin flexible, resilient spine, The spine (12) extends into an aperture (13) in the head (14), and is integrally joined to the head (14) at the bottom of the aperture (13), thereby linking handle (11) and head (14). The spine (12) is thin enough to allow the head (14) to rock relative to the handle (11). The head (14) bears bristles (15) distributed in discrete tufts.

The space between the spine (12) and the head (14), i.e. including the aperture (13) is filled with an elastomeric material (16). The material (16) modifies the rocking characteristics of head (14) relative to handle (11), and is also of a different colour to the material of the handle (11) and head (14) for aesthetic reasons and to emphasise the construction of the toothbrush.