GB2050156A

GB2050156A - Toothbrush

Info

Publication number: GB2050156A
Application number: GB8013955A
Authority: GB
Original assignee: PAKARNSEREE S
Current assignee: PAKARNSEREE S
Priority date: 1979-04-27
Filing date: 1980-04-28
Publication date: 1981-01-07
Also published as: GB2050156B

Abstract

The handle has a rigid core composed of metal strip 21 and hard plastic 22. Tufts 24 are inserted in holes in the head of the strip 21 and secured by pegs 25 embedded in the hard plastic 22. A layer 26 of elastomer provides a comfortable and secure grip and prevents damage to teeth and gums. The bristles preferably have a bundle of nylon filaments as a core with another nylon filament wound round in a coil to form a soft outer sheath which is bonded to and stiffens the core. <IMAGE>

Description

SPECIFICATION Toothbrush The present invention relates to a toothbrush.

The invention is concerned particularly with the structure of the handle of a toothbrush and the mounting of bristles in the handle.

The bristles are preferably composed of synthetic plastics material and may comprise an inner core and an outer sheath.

In accordance with the present invention there is provided a toothbrush having a handle comprising a core consisting of a metal strip covered with a hard plastics material and bristles mounted in the core near one end to form the head of the brush, the core being covered with an elastomer at least in the region of the head.

The bristles are preferably in tufts which are located in holes in the metal strip and secured by pegs which pass through the tufts and are embedded in the hard plastics material. A preferred form of bristle has an inner core composed of a bundle of filaments and an outer sheath composed of a filament wound around the core.

The invention will be described in more detail with the aid of an example illustrated in the accompanying drawings, which in Figs. 1 to 7 show the construction of a toothbrush in accordance with the invention somewhat schematically and in Figs. 8 to 11 show details of the structure of one embodiment of the invention.

In the drawings: Figure 1 is a longitudinal section through a toothbrush according to the invention; Figure 2 is a transverse section through the toothbrush shown in Fig. 1; Figure 3 is a cross-section through a bristle of the toothbrush shown in Fig. 1; Figure 4 is a longitudinal section through part of a filament of material from which bristles for a brush according to the invention can be made; Figure 5 is a longitudinal section through part of an alternative filament of material from which bristles can be made; Figure 6 is a partial longitudinal section through a bristle made from the filament shown in Fig. 4; Figure 7 is a partial longitudinal section through a bristle made from the filament shown in Fig. 5; Figure 8 is a longitudinal section of the preferred embodiment in a plane containing the bristles, Figure 9 is a longitudinal section in an orthogonal plane;; Figure 10 is a transverse section of the head of the brush, and Figure 11 is a perspective view, much enlarged, of a single bristle.

Figs. 1 and 2 show a toothbrush constructed according to the invention. The toothbrush has bristles 11 mounted in a rigid handle 1 2. The handle 1 2 comprises a core 1 3 of a rigid material and a covering 1 4 of an elastomer. The covering 14 can be of soft thermoplastic material, such as ethylene vinyl acetate co-copolymers, polyethylene or polyvinyl chloride, or of natural or synthetic rubber. The handle 1 2 has a head portion 15, in which the bristles 11 are mounted, a body portion 21 intended to be gripped when the brush is being used, and a neck portion 1 6 connecting the head portion 1 5 to the body portion 21.The covering of elastomer 14 is thinner on the neck portion 1 6 than in the head portion 1 5 or the body portion 21.

Securing the bristles in the handle can be achieved by forming holes in the rigid core 1 3 of the handle into which tufts of bristles fit tightly.

Referring to Fig. 3 a bristle 11 for a toothbrush according to the invention has a stiff core 1 7 made of a hard thermoplastic such as Nylon 6 or high-density polyethylene. The stiff core 1 7 is surrounded by a sheath 1 8 of a softer material. The sheath 1 8 can be made of a soft thermoplastic material, such as ethylene vinyl acetate co-polymer, polyethylene or polyvinyl chloride, or of natural or synthetic rubber.If the diameter of the core 1 7 is d and the outer diameter of the sheath 1 8 is D then the ratio d D can be in the range 1 1 to 1.01 2.5 Fig. 4 shows a part of a filament of material 1 9 produced by continuous extrusion moulding of a substance suitable for the core 1 7 and a substance suitable for the sheath 1 8 of the bristle shown in Fig. 3. The filament 1 9 may be divided into bristles, at the ends of which the stiff core 1 7 is exposed. Fig. 6 shows an end of a bristle 11 made from the filament 1 9.

Fig. 5 shows part of a similar filament 20.

During the production of the filament 20 the extrusion of the substance of the core was regularly interrupted. The filament 20 can be divided into bristles by severing the substance of the sheath in the gaps between the portions of the core substance. In this way bristles are produced at the ends of which stiff core 1 7 is covered by the sheath 18, as shown in Fig 7.

Referring now to Figs. 8 to 10 it will be seen that the rigid core of the handle of the toothbrush is composed of a metal strip 21 covered with a layer 22 of a hard synthetic plastics material. The strip 21 has holes 23 in the head region and tufts 24 of bristles are located in the holes 23. Each tuft 24 is formed of a bundle of bristles folded in haif. A peg 25 is passed between the two halves of the folded bundle and is embedded in the hard plastics layer 22, thereby securing the bristles in the handle. Substantially the whole of the handle, and especially the head portion, is enclosed in a covering 26 of elastomer, corresponding to the covering 14 of Figs. 1 and 2.

The preferred material for the bristles, which may of course be used in other toothbrushes, is shown in Fig. 11 and comprises a bundle of filaments 27 forming an inner core and a filament 28 wound around the core to form an outer sheath. The core may be made of stiffer material and the sheath of softer material but preferably both are composed of nylon filaments, of which that forming the sheath may be of smaller diameter. Nylon filaments, because of the long molecular chain of the material, bend easily and easily lose their spring. Winding a coil of soft filament around the core overcomes these problems.

The sheath is preferably joined to the core by heat or by chemical treatment. The ratio of the diameter of the core to the outer diameter of the sheath can again be between 1:1.01 and 1:2.5.

When using the toothbrush described, there is less chance of damage to the gums, fillings in the teeth and soft tissues in the mouth.

This is particularly important for children and for people with oral diseases. The bristles are resilient yet their outer surfaces are soft.

When in contact with the gum the sheath 1 8 of a bristle 11 will deform to give a large area of contact between the bristles and the gum.

This feature is advantageous for massage of the gum to improve blood circulation. In addition, the large area of contact developed between the sheath 1 8 and the tooth surface facilitates the removal of plaque because each bristle cleans a large area for each stroke of the brush. The soft sheath 1 8 develops more friction with the teeth and this also assists in cleaning. The handle, in particuiar the head and the neck are made thin by using a thin strip of metal as the rigid core, and this is preferable for easy use. In addition, the soft covering on the handle makes it easier to grip.

For cleaning the teeth and removing plaque the type of bristle having the stiff core exposed at the end is used, and the bristle having the core covered at the end is preferable for gum massage.

It will be appreciated that although only one tooth brush has been described the invention is not confined to this embodiment. The covering of elastomer on the handle can be incomplete. The head of the handle can be inclined to the remainder of the handle, the relative dimensions of the head, neck and remainder of the handle can be changed. The number of tufts of bristles can vary, for example between 1 and 56.

Claims

1. A toothbrush having a handle comprising a core consisting of a metal strip covered with a hard plastics material and bristles mounted in the core near one end to form the head of the brush, the core being covered with an elastomer at least in the region of the head.

2. A toothbrush as claimed in claim 1 wherein the covering of elastomer extends over substantially the whole of the core.

3. A toothbrush as claimed in claim 1 or 2 in which the bristles are located in holes in the metal strip and embedded at their roots in the hard plastics material.

4. A toothbrush as claimed in claim 3 in which tufts of bristles are located in the holes in the metal strip and each tuft is secured by a peg which is embedded in the hard plastics material.

5. A toothbrush as claimed in any of the preceding claims in which the bristles have an inner core and an outer sheath.

6. A toothbrush as claimed in claim 5 in which the outer sheath is of a softer material.

7. A toothbrush as claimed in claim 6 in which the end of the inner core is exposed.

8. A toothbrush as claimed in claim 5 in which the outer sheath is composed of a filament wound around the inner core.

9. A toothbrush as claimed in claim 8 in which the core is a bundle of filaments.