TOOTHBRUSH

Abstract: The handle (2) and head (3) of a toothbrush (1) are interconnected by a neck (4) having a resiliently flexible portion (5) with a helical groove (6) which allows the neck (4) to flex in any transverse direction and also to twist relative to the handle (2).

Description: TOOTHBRUSH This invention relates to toothbrushes and is particularly concerned with a toothbrush having a flexible neck. Toothbrushes with flexible necks are already known, the flexible necks either being in the form of a resillently deformable region, as described in EP-A-0336641 and US-A-4520526, or including a snap-action mechanism, as described in EP-A-0281017, whereby the head of the toothbrush can be disposed angularly relative to the handle of the brush. The purpose of these brushes is to compensate for poor brushing techniques which have detrimental effects on oral hygiene as significant as negligence of oral hygiene. Flexible necks not only allow the user easily to reach awkward areas of the mouth without causing discomfort, but also help to maintain a steady, relatively uniform pressure on teeth by bending to take up any excess brushing pressure. A uniform brushing pressure is beneficial in that excess pressure can cause wear or loosening of the teeth and abrasion of the gums, causing them to bleed and leading to gingivitis, periodontal disease and ultimately to tooth loss. However, the known flexible-necked toothbrushes are flexible in one direction only, that is, backwards and forwards relative to the teeth being brushed, and this does not fully overcome the problems of reaching awkward areas of the mouth and of applying adequate pressure to the teeth, without causing discomfort to the user. One awkward area is the gum margin, particularly behind the front teeth, where a certain amount of lateral flexibility, and even twistability, of the neck of a brush would be advantageous in that it would minimise any peaks of pressure on the teeth and gums during brushing and would thus reduce abrasion of the teeth and gums. Thus, the object of the invention is to provide a toothbrush with a neck which is capable of flexing in any transverse direction relative to the handle, and possibly also of twisting, so as to achieve the maximum reduction of peaks in pressure exerted on the teeth by the user during brushing. Accordingly, the invention provides a toothbrush having a handle and a head interconnected by a neck with a resiliently flexible portion, in which at least the neck portion has a helical formation around a central core. The core is preferably substantially cylindrical or of substantially square cross-section. The presence of a helical formation, such as a groove, allows the head to move relative to the handle in any transverse direction as there is no immediate restraint in any one direction, and even allows the head of the brush to twist slightly with respect to the handle, thus enabling adequate contact between substantially all of the bristles and the teeth or gum margin areas with sufficient, uniform pressure. The central core confers a certain amount of rigidity to the helical portion of the neck and ensures that, in use, at least some of the pressure applied by the user is transmitted to the head of the brush and hence to the teeth. The resilience of the helical portion and its core is such that they can be bent to enable the head of the brush to reach awkward areas of the mouth and can yield to prevent tooth or gum damage when the user applies excess brushing pressure to the handle. The resilience of the helical portion also reduces the pressure transmitted to the bristles and hence prolongs the efficient life of the toothbrush. The helical portion also has the effect of distributing the flexing movement evenly throughout the length of the neck portion, rather than concentrating movement at one or more discrete locations as in certain known toothbrushes, which tends to create zones of weakness. The body of the toothbrush, that is, the handle, the neck with the helical portion and the head excluding the bristles, is preferably made in one piece from a plastics material which can be readily extruded or moulded in one piece with the helical portion. Alternatively, the helical portion may be formed later, for example, by machining. The helical portion is preferably confined to the neck portion of the toothbrush but may extend to the handle, thereby enhancing the flexibility of the handle and hence the comfort to the user. In such an instance, the handle and the neck may be effectively constituted by a continuous helically-formed portion of the toothbrush extending from the head to the distal part of the handle thereof. Preferred embodiments of the invention will now be described in detail, by way of example only, with reference to the appended drawings, in which: Figure 1 is a plan view of a toothbrush according to one embodiment of the invention; Figure 2 is a side view of the toothbrush of Figure 1; Figure 3 is a side view of a toothbrush according to a second embodiment of the invention; and Figure 4 is a side view of a toothbrush according to a third embodiment of the invention. With reference to the drawings, a toothbrush according to the invention is generally indicated 1. The toothbrush 1 has a handle 2 and a head 4 which are interconnected by a neck 3. The handle 2, the neck 3 and the head 4 of the toothbrush 1 are moulded in one piece from a plastics material, such as polyethylene or polypropylene. The bristles (not shown) are then bonded to the head 4 of the brush 1 in conventional manner. In accordance with the invention, the neck 3 includes a screw- or auger-like resiliently flexible portion 5 with a continuous, helical groove 6 around a central core 7. The core 7 is substantially cylindrical in the brushes 1 of Figures 1, 2 and 3 but is of substantially square cross-section (the square not necessarily being of constant orientation along the length of the portion 5) in the brush of Figure 4. The crests or ridges 8 between the turns of the helical groove 6 may be sharp as in Figures 1, 2 and 4 or rounded as in Figure 3. When a certain pressure is applied to the head 4 by the user, the helically grooved portion 5, 6 can flex to allow the head 4 of the brush to move in any transverse direction relative to the handle 2, for example in the directions indicated by the arrows A and B in Figures 1, 2 and 3, and/or can deform torsionally to allow the head 4 to twist relative to the handle 2, the portion 5 relaxing to return the head 4 to its normal position when the pressure is removed. The core 7 confers a certain amount of rigidity to the grooved portion 5, 6 so that it does not flex or deform too easily. The grooves 6 of the toothbrushes 1 of Figures 1, 2 and 3 are relatively deep and are defined by relatively tight helices, that is, helices of relatively fine pitch. In each case, the pitch of the helix is such that, when the head 4 of the brush 1 moves transversely relative to the handle 2 upon flexure of the grooved portions 5, 6, the crests or ridges 8 of the groove 6 facing in the direction of flexure and movement tend to move together slightly to limit the amount of flexure and hence of transverse movement, whereas the crests or ridges 8 facing in the opposite direction move apart correspondingly. The groove 6 of the toothbrush 1 of Figure 4, on the other hand, is relatively shallow and is defined by a relatively open helix, that is, a helix of relatively coarse pitch. In this case, the relative rigidity of the core 6 is more important than the moving together of the crests or ridges 8 of the groove 6 in limiting the transverse movement of the head 4 relative to the handle 2. In each embodiment, to accommodate the twisting of the head 4 relative to the handle 2 of the respective brush 1, the groove 6 closes up slightly, that is, the helix tends to contract axially, when the head 4 twists in one sense and the groove 6 opens up slightly, that is, the helix expands axially, when the head 4 twists in the opposite sense. Thus, when pressure is applied to the toothbrush 1 by the user, the head 4 can move in any transverse direction relative to the handle 2 and can twist relative thereto, the helically grooved portion 5 deforming both to allow this movement and to dissipate any excess brushing pressure, thereby maintaining a sufficient, uniform pressure on the teeth and gums. Preferably, the handle 2 of the brush 1 has grips 9 of rubber or a rubberised material on two opposite faces. These grips 9 may be incorporated in the handle 2 during extrusion or moulding or they may be applied to the handle as a coating. The neck 3 of the toothbrush 1 may be at an angle to the handle 2, as shown in Figure 2, or may be in line therewith, as shown in Figure 3. The head 4 of the brush 1 may be of a so-called compact size or of a standard size.

Claims: CLAIMS 1. A toothbrush (1) having a handle (2) and a head (4) interconnected by a neck (3) with a resiliently flexible portion (5), characterised in that at least the neck (3) has a helical formation (6) around a central core (7) . 2. A toothbrush according to Claim 1, characterised in that the helical formation comprises a groove (6) which is relatively deep and is defined by a helix of a sufficiently fine pitch that, when the resiliently flexible portion (5) flexes transversely of the handle, those crests (8) between the turns of the groove (6) which face in the direction of flexure tend to move together to limit the amount of flexure. 3. A toothbrush according to Claim 2, characterised in that the central core (7) is substantially cylindrical. 4. A toothbrush according to Claim 1, characterised in that the formation comprises a groove (6) which is relatively shallow and is defined by a helix of relatively coarse pitch. 5. A toothbrush according to Claim 4, characterised in that the central core (7) is substantially of square cross-section. 6. A toothbrush according to any of the preceding claims, characterised in that the handle (2) is provided with grips (9) on two opposite faces. 7. A toothbrush according to any of Claims 1 to 5, characterised in that the helical formation (6) is additionally formed in the handle (2) . AMENDED CLAIMS [received by the International Bureau on 18 March 1994 (18.03.94) original claim 1 replaced by amended claim 1 other claims unchanged (1 page)] 1. A toothbrush (1) having a handle (2) and a head (4) interconnected by a neck (3) with a resiliently flexible portion (5) , characterised in that at least the said portion (5) of the neck (3) has a helical formation (6) around a central core (7) . 2. A toothbrush according to Claim 1, characterised in that the helical formation comprises a groove (6) which is relatively deep and is defined by a helix of a sufficiently fine pitch that, when the resiliently flexible portion (5) flexes transversely of the handle, those crests (8) between the turns of the groove (6) which face in the direction of flexure tend to move together to limit the amount of flexure. 3. A toothbursh according to Claim 2, characterised in that the central core (7) is substantially cylindrical. 4. A toothbrush according to Claim 1, characterised in that the formation comprises a groove (6) which is relatively shallow and is defined by a helix of relatively coarse pitch. 5. A toothbrush according to Claim 4, characterised in that the central core (7) is substantially of square cross-section. 6. A toothbrush according to any of the preceding claims, characterised in that the handle (2) is provided with grips (9) on two opposite faces. 7. A toothbrush according to any of Claims 1 to 5, characterised in that the helical formation (6) is additionally formed in the handle (2) .

Inventors: SANDERSON JOHN WARD, SANDERSON LOUIS WILLIAM, SANDERSON, JOHN, WARD, SANDERSON, LOUIS, WILLIAM
Applicants: SANDERSON J & W LTD, SANDERSON JOHN WARD, SANDERSON LOUIS WILLIAM, J & W SANDERSON LIMITED, SANDERSON, JOHN, WARD, SANDERSON, LOUIS, WILLIAM
Application year: 1993
Main classification: A46B5
IPC codes: A46B5