Toothbrush with flexibly linked zone between the head and a surrounding frame

Abstract: A toothbrush having a handle and a bristle bearing head made of a plastics material, the head being flexibly and resiliently linked to a frame which wholly or partly surrounds the head, the relative dimensions of the head and the frame being such as to leave a gap between the head and the frame such that the head and frame are capable of relative rocking motion about the gap, the gap being wholly closed with a flexible and resilient elastomeric material.

Description: 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, US-A-4520526, DE-OL-3640898, DE-OL-3612108, CH-0155730 and IT-485723. In some circumstances it is desirable to further improve the flexibility of the head relative to the direction of the handle of the toothbrush. Toothbrushes which have flexible features in their head are disclosed in US-A-2266195, US-A-4488328, US-A-4691405 and DE-1233821-A. In particular US-A-4488328 (upon which the preamble of claim 1 is based) discloses a toothbrush whereby the head is partly surrounded by a frame and is moveably linked thereto by connecting arms. Accordingly the present invention provides a toothbrush as claimed in claim 1 below. The toothbrush head of this invention can move 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 frame preferably completely surrounds the head and is preferably integral with the handle. The head is preferably in the form of an undivided elongate rectangular or lozenge-shaped portion within the frame. 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. The frame may also be bristle-bearing. Bristles on the frame are also preferably distributed in discrete tufts, and may have the same or different colour, distribution, length, orientation or stiffness to those on the head. Conveniently bristles on the frame are shorter than those on the head so that the bristles on the frame do not interfere with the movement of the head. The head and extended portion of the handle, i.e. the frame, may have different colours for aesthetic appeal or to emphasise the construction of the toothbrush. The gap between the head and the frame is wholly or partially closed with a flexible and resilient elastomeric material, suitably in the form of a thin diaphragm. The flexibility and resilience of such a diaphragm will depend upon the materials of which it is made, its thickness and the extent to which it closes the gap between the head and the extended portion. Suitably the elastomeric material may be coloured differently to the head and/or extended portion and/or the handle for aesthetic reasons or to emphasize the construction of the toothbrush. The elastomeric material may be coloured differently to the head and/or extended portion and/or the handle for aesthetic reasons or to emphasise the construction of the toothbrush. The linking of the head to the extended portion in the above-described ways allows rocking of the head 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 diaphragm may be made as a separate part to a plastics material head and frame. For example the diaphragm made of an elastomeric material may need to be made and fitted separately. 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: Fig 1 shows a toothbrush of the invention having an extended portion in the form of a frame in which the linking of the head and frame is by a diaphragm. Fig 2 shows a toothbrush of the invention having an extended portion in the form of a bristle-bearing frame. 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, in an overall side view in Fig 1C, in long section and long section view about the line A-A in Figs 1D and 1F respectively, and in a cross sectional view about the line B-B in Fig 1E. In the toothbrush of Fig 1, the handle (part shown (11)) of a toothbrush is extended to form an integral frame (12) which surrounds a rigid head (13). The upper surface of the head (13) bears bristles (14) distributed in a number of discrete tufts. The relative sizes of the frame (12) and head (13) are such that a narrow gap (15) lies between them. The gap (15) is open on its lower side, but its upper side is closed with a thin diaphragm (16) of an elastomeric material. The thickness of the diaphragm (16) is such that it is flexible and resilient. In Figs 1E and 1F the rocking movement of the head (13) relative to the frame (12) is shown, as pressure is applied to the bristles (14) at the points indicated by the arrow, the diaphragm (16) being thin enough and the gap (15) being of dimensions such as to allow this movement. Referring to Fig 2, the bristle-bearing portion of a toothbrush of the invention is shown in a top view in Fig 2A, in an underside view in Fig 2B, in an overall side view in Fig 2C, in long section and long sectional view about the line A-A in Figs 2D and 2F respectively, and in cross sectional view about the line B-B in Fig 2E. In the toothbrush of Fig 2, the handle (part shown (21)) is extended into an integral frame (22) surrounding a rigid head (23) which bears bristles (24), there being a narrow gap (25) between frame (22) and head (23). The lower side of the space (25) is open, and the upper side is closed with a diaphragm of an elastomeric material (26), thin enough to be flexible and resilient. The construction, disposition and rocking movement under applied pressure of these features of the toothbrush of Fig 2 are identical to the corresponding features of Fig 1. In the upper surface of the frame (22) are mounted bristles (27), distributed in discrete tufts around the frame (22). These bristles (27) are shorter than the bristles (24) on the head (23).

Claims: A toothbrush having a handle (11, 21) and at one end thereof a bristle-bearing portion which comprises a bristle bearing head (13, 23), the head (13, 23) and the handle (11, 21) being disposed along a longitudinal axis direction and having a width direction perpendicular to the longitudinal direction and to the direction in which the bristles extend, the handle (11, 21) and bristle bearing portion (13, 23) being made of a plastics material, the head being wholly or partly surrounded by a frame (12, 22) which is an extended portion of the handle (11, 21), the head being flexibly and resiliently linked to the frame (12, 22), the head being capable of rocking motion relative to the handle (11, 21), the relative dimensions of the head (13, 23) and the frame (12, 22) being such as to leave a gap (16, 25) between the head (13, 23) and the frame (12, 22) such that the head (13, 23) and frame (12, 22) are capable of relative rocking motion about the gap (16, 25), characterised by the gap (16, 25) being wholly or partly closed with a flexible and resilient elastomeric material and by the head being able to rock within the frame about a number of axes, including axes aligned both in the width direction and the longitudinal direction. A toothbrush according to claim 1 characterised in that the frame (12, 22) completely surrounds the head (13, 23) and is integral with the handle (11, 21). A toothbrush according to claim 1 or 2 characterised in that the head (13, 23) is in the form of an undivided elongate rectangular or lozenge shaped portion within the frame (12, 22). A toothbrush according to any one of the preceding claims characterised in that the frame (12, 22) is bristle bearing. A toothbrush according to claim 4 characterised in that the bristles on the frame (12, 22) are shorter than the bristles on the head (13, 23). A toothbrush according to any one of claims 1 to 5 characterised in that the space between the head (13, 23) and the frame (12, 22) is wholly closed with the flexible and resilient elastomeric material.

Inventors: HALM HANS, HALM, HANS
Applicants: SMITHKLINE BEECHAM CONSUMER, SMITHKLINE BEECHAM CONSUMER HEALTHCARE GMBH
Application year: 1992
Main classification: A46B7
IPC codes: A46B5, A46B7