Technical field:

The present invention relates to a toothbrush that is structured uniquely and can be manufactured at low cost and yet provides good mechanical and ergonomic properties of standard quality toothbrushes.

Background and Prior art : Various types of toothbrushes have been designed to achieve quality oral care and major population of the world find it difficult to afford these. It has been an ongoing exercise to lower the cost of manufacturing toothbrushes and making them available at affordable prices. In the past the major direction for achieving this has been by reducing the toothbrush dimensions and thus saving on the material used for manufacturing.

The above mentioned approaches do not adequately take care of the mechanical strength provided and the ergonomic properties of the toothbrush. This approach leads toothbrushes which do not provide comfort while using the toothbrush and makes brushing inconvenient.

US5908038, discloses a unitarily molded toothbrush wherein the head, neck and handle are all formed of an identical plastic material having a Melt Index no lower than 6g/10 min. It also discloses that by providing a plurality of recesses with openings on undersurfaces will achieve minimizing the amount of plastic material required to manufacture the article. Still a further benefit of the

recesses is that the handle achieves greater flexibility thereby rendering the toothbrush more ergonomically functional. However, the presence of recesses requires other means for strengthening structural integrity of the toothbrush which has been done by providing a beam longitudinally traversing a length of the brush and additional cross members.

Further US5908038 discloses brushes that are unitarily molded thereby limiting the choice and longevity of the bristles .

It has now been possible to manufacture toothbrushes with reduced amount of plastic material and further reducing the material usage by eliminating the beam and cross members. Further it is possible by the present invention to make toothbrushes that are not unitarily molded and thus provide flexibility in the choice of bristle materials and configuration .

It is an object of the present invention to provide a relatively low cost toothbrush that is manufactured using reduced amount of plastic material .

It is another object of the present invention to provide a relatively low cost toothbrush formed without the use of means for strengthening structural integrity, thereby further economizing the use of material. It is another object of the present invention to provide a relatively low cost toothbrush that has the required

mechanical strength and ergonomic properties comparable to traditionally conventional toothbrushes.

It is yet another object of the present invention to provide a relatively low cost toothbrush that has the length, width of the head, neck and handle comparable to traditionally conventional toothbrushes.

Still another object of the present invention is to provide a relatively low cost toothbrush with a three angled neck to allow the bristle head to reach all faces of all the teeth.

Description of the Invention:

Thus according to the present invention there is provided a toothbrush having a head and a handle formed using a polymeric material whose tensile strength is in the range 20-80 MPa wherein the handle on at least one face is provided with a recess that is inside of the lateral edges of the handle wherein the volume of the recess is in the range of 20-50% of the volume of the equivalent portion of the handle if unrecessed.

It is particularly preferred that the tensile strength of the material used for forming the toothbrush is in the range 25-45 MPa and more preferably is 30-40 MPa.

Detailed description of the invention:

The details of the invention its objects and advantages are explained hereunder in greater detail in relation to non - limiting examples:

It has now been possible to manufacture toothbrushes with reduced amount of plastic material while maintaining the mechanical strength and ergonomic properties of the toothbrush without additional strengthening structural means like ribs and beams. This has been achieved by choosing a material which has a tensile strength in the range of 20-80 MPa and preferably in the range 25-45 MPa more preferably 30-40 MPa and providing a recess in the handle of the toothbrush which forms 20-50% of the volume of the equivalent portion of the handle if unrecessed.

The dimensions of the toothbrush according to the invention are maintained such that the toothbrush preferably has a length in the range 170-200 mm, the width of the handle is in the range 10-20 mm and the thickness is in the range 5-15 mm. Thus the surface area to the volume ratio which is a key parameter in determining the ergonomic properties of the toothbrush is maintained similar or superior to that of a standard quality toothbrush. The surface area to the volume ratio of the toothbrush according to the present invention is in the range 0.2-0.3 whereas the ratio for standard quality brushes known in the art is upto 0.2.

The plastic materials that are used to form the toothbrush is preferably selected from various grades of polypropylene, styrene acrylonitrile, polymethyl methylacrylate, acrylonitrile butadiene styrene, thermoplastic elastomers.

The most preferred materials are polypropylene and thermoplastic elastomers.

The recess in the handle is provided on the inside of the lateral edges of the handle wherein the volume of the recess is in the range of 20-50% and preferably 30-40% of the volume of the equivalent portion of the handle if unrecessed. The recess is provided on the non-brushing face of the toothbrush and extends from the distal end of the handle with respect to the head. The recess extends to 10%- 80% of the length of the toothbrush and preferably extends to 35-50% of the length of the toothbrush. It is so designed that maximum depth of the recess extends beyond the parting line to achieve maximum economy in the use of the plastic material .

The toothbrush comprises of a head and a handle and preferably neck portion between the head and the handle. The toothbrush is so designed that the width of the widest part of the handle is greater than the width of the head. The toothbrush according to the invention is provided with a neck portion which enables the bending of the bristle head relative to the handle thereby being ergonomically adjustable to a user's hand pressure and reach all the teeth to be cleaned. The neck provided is preferably three-angled to allow the bristle head to reach all faces of all the teeth and provide flexibility to the neck to allow bending of the bristle head relative to the handle.

The toothbrush according to the invention is manufactured by an injection molding process. The handle of the toothbrush can be formed using more than one plastic material or differently coloured same plastic material in which case the toothbrush is formed by two-stage injection molding process.

The mould is so designed that maximum depth of the recess extends beyond the parting line. Conventional molding and plastic injection equipment is utilized for manufacture of toothbrushes according to the present invention.

BRIEF DESCRIPTION OF THE DRAWING:

The above features, advantages and objectives of the present invention will more fully be appreciated through the following detailed description with reference to the drawings in which:

FIG. 1 is a front view of an embodiment according to the present invention;

FIG. 2 is a back view of the embodiment illustrated in FIG. 1;

Fig. 3 is a side view of the embodiment illustrated in FIG. 1

FIG. 1 illustrates a preferred embodiment of the present invention. The toothbrush includes a head (1) having bristles (2) , a neck (3) and handle (4) . The handle is made of two different plastic materials or of differently- coloured plastic material, although, this is a preferred feature to enhance the grip and aesthetic appeal of the toothbrush, these features need not be present for purposes of this invention. Grip is provided by portion (5) of the handle, which is made of the first material the rest of the handle is made of the second material .

Fig. 2 shows the back view of the toothbrush, which is provided with a recess (6) on the non-brushing face of the

toothbrush and extends from the distal end of the handle with respect to the head. The ridges (7 and 8) form the lateral edges of the toothbrush and provide the necessary mechanical strength and support to the toothbrush.

Fig 3 shows the side view of the toothbrush showing the three-angled neck (3) .

It is thus possible by way of present invention to provide a uniquely designed toothbrush that can be manufactured using reduced amount of plastic at significantly low cost and yet provide good mechanical and ergonomic properties of standard quality toothbrushes.