Toothbrush with resiliently flexible head

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

This application is a divisional application under Art 76 EPC from EP 92906956.5.

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 an individual's teeth and gums. Such toothbrushes are disclosed for example in EP-A-0336641, US 4520526, DE-OL-3640898, DE-OL-3612108, CH-0155730 and IT-485723. EP-A-613636 and EP-A-604425 disclose toothbrushes having their heads flexibly linked to their handles.

Various toothbrushes with their heads divided into flexibly linked segments are disclosed in FR-A-1525055, US-A-3188672, US-A-2,254,365 and US-A-2438268. In these disclosures the segments are longitudinally disposed and linked to each other longitudinally.

US-A-4691405, DE1233821 and US 2 266 195 disclose[s] a toothbrush having a head in the form of a frame surrounding two segments linked at longitudinal ends to the frame. Upon such known prion art is based the preamble of claim 1.

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

Accordingly the present invention provides a toothbrush as claimed in claim 1, preferred embodiments being as described in the dependent claims.

The toothbrush head of this invention, being flexible, can flex under the action of toothbrushing so as to accommodate itself to the differing profiles of individual users' teeth. In particular, teeth generally lie in a "C" shaped curve within the upper and lower jaw, the row of teeth consequently having a convex outer curve and a concave inner curve. The flexible head of the tooth-brush of the inventors can bend to accommodate itself to both the convex and concave curves of the teeth generally better than would be the case with a conventional rigid-headed toothbrush.

Within such a frame the one or more chains of bristle carriers may be integrally formed, or may be made as a separate part and fastened into the frame.

The linking of the one or more chains of bristle carriers to the frame may be by bridging portions of the material of the head or frame, and by varying the dimensions the degree of flexibility and/or resilience of the linking may be carried.

The frame may bear bristles, which may have the same or different distribution, length, orientation, colour or stiffness to those on the one or more chains of bristle carriers. Conveniently bristles when present on the frame may be shorter than those on the head.

The bristles may be uniformly distributed over the head, and the frame, if present, but preferably the bristles are distributed in discrete tufts. There may be one or more tufts per segment. Each bristle carrier may carry one or two tufts of bristles.

The space(s) within the frame and between the one or more chains of bristle carriers and the frame may be partly or wholly filled with a flexible and/or resilient material, which may be an elastomeric material and/or may be in the form of a thin diaphragm. By varying the degree of such filling and the material used the degree of flexibility and/or resilience of the head may be varied.

The toothbrush (i.e. the handle, head and bristles) 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'™ (marketed by BASF, Germany).

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-A-0 336 641, 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:

Fig 1 shows a toothbrush head in the form of a chain of linked bristle carriers within a frame extension of the handle.

Referring to Figs. 1A, 1B, 1C, 1D, 1E and 1F, a toothbrush head (41) is surrounded by a frame (42) extension of a handle (43), which are shown in an underside view in Fig. 1 A, in a top view in Figs 1B and 1F, in longitudinal section about line A-A in Figs. 1C and 1D and in an overall side view in Fig. 1E.

The head (41) is in the form of a series of bristle carriers (44) which are flexibly and resiliently linked by thin bridging portions (45) to each other and to the frame (42). The bristle carriers (44) carry one or two tufts (46) of bristles. More tufts (47) of bristles are mounted on the frame (42) in an outer ring of tufts (47) which are shorter than tufts (46).

Within frame (42) there is a space (48) around the chain of bristle carriers (44), which in Fig 4F is shown filled with an elastomeric material (49) which is of a different colour to that of the frame (42) and bristle carriers (44).

In Fig. 1D the head (41) is shown as flexing under the application of pressure at the point indicated by the arrow in Fig. 1D into a concave curve of tufts (46) accommodating itself to the outer side of the line of the teeth. The linking of individual tufts (46) in this way assists towards a very gentle tooth cleaning action.