Toothbrush and Method for Producing It

Abstract

A toothbrush comprises a grip part and a head part carrying a set of bristles. The grip part is connected to the head part via a joint which is associated with a spring element from an elastic plastic material. The spring element is configured froth an at least partial outer cover of the joint. In a preferred embodiment, the cover completely covers the joint and seals it off relative to the surroundings.

Description

The invention concerns a toothbrush with a grip part and a head part carrying a set of bristles, the grip part being connected to the head part via a joint that is associated with a spring element from an elastic plastic material. The invention also relates to a method for producing such a toothbrush.

It has been known for a long time that it is useful to structure the handle of a toothbrush so elastically that, when the toothbrush is used, the set of bristles can execute a movement relative to the grip section held by the user. In this way, the set of bristles can give way by elastic deformation of the toothbrush when excessive brushing forces are applied, so that the danger of injuring the oral mucosa and the gums is reduced. It is known that the elastic deformation of the toothbrush can be achieved in two different structural ways. The handle of the toothbrush can be a single component made of plastic, which has a lower elastic modulus in a transitional region between the rear grip section and the front head section due to special cross-sectional shaping and/or material combinations and therefore greater deformability. Alternatively, a rear grip part and a front head part of the toothbrush constitute separate components and can be connectable via a joint. The invention concerns a toothbrush of the latter type.

A toothbrush of this type is, for example, known from WO99/39610 Al. The toothbrush described therein comprises a grip part that has a J-shaped hook section on its front end nearest the set of bristles. A head part also has a J-shaped hook section on its rear end, nearest the grip part. The two hook sections hook one under the other, forming a gap, and the gap is filled with an elastic plastic material. In this way, the head part can swivel relative to the grip part when the toothbrush is used, deforming the elastic plastic material and generating the forces of reaction necessary to restore the head part.

In prior art, the deformation properties of the head part relative to the grip part depend largely on the thickness of the plastic material and therefore on the size of the gap between the head part and the grip part. Because the size of the gap is dependent on the design, it is only possible to achieve different deformation properties by using different elastic plastic materials. This is disadvantageous for production. Furthermore, it has been shown that the known toothbrush has undefined rigidity perpendicular to the desired direction of movement of the head part so that the toothbrush may bend away during use.

The object of the invention is to create a toothbrush of the this type with which defined deformation properties during use can be achieved. In addition, a method is to be created by which that toothbrush can be produced simply and at low cost.

With respect to the toothbrush, the object is inventively solved by the spring element being constituted by at least one outer cover of the joint, the cover preferably consisting of a thermoplastic elastomer.

The invention is based on the fundamental consideration that the elastic plastic material that constitutes the spring element, instead of being located inside the joint, could be located outside thereof in the form of an at least partial outer cover of the joint. This has the advantage of adapting the design of the joint and its possible movements optimally to the required deformation movements of the head part relative to the grip part.

In a preferred embodiment of the invention, the joint is a ball-and-socket joint or hinged joint. In the case of a ball-and-socket joint, a spherical joint body is fitted in a complementarily shaped joint receptacle with a tight fit, so that the head part can be swiveled 360° relative to the grip part in any direction. In the case of a hinged joint, by contrast, a cylindrical joint body is held in a complementary joint receptacle so that swiveling of the head part relative to the grip part is only possible in one direction or one plane. The joint can also have yet a different design, for example, as a saddle joint.

The outer cover can easily be applied to the joint and, in particular, be overmolded and determines the deformation properties of the head part relative to the grip part. The forces of reaction caused during deformation of the toothbrush in the elastic plastic material of the cover and therefore the spring constant of the spring element can be determined as desired by the design and/or the thickness of the cover and/or by the material properties and, in particular, by the Shore hardness of the plastic material.

If the joint permits movement of the head part relative to the grip part only in one defined plane, as is the case, for example, for a hinged joint, it is sufficient if the cover has at least two tendon parts that are fixed at one end to the grip part and at the other end to the head part. In particular, precisely two tendon parts should be provided that are located on opposite sides of the toothbrush in the direction in which the head part can deflect.

In an especially preferred embodiment of the invention, the cover encloses the joint completely and seals it off relative to the surroundings. This ensures sufficient resilience in all directions in a joint that permits movement of the head part relative to the grip part in multiple planes, for example, a ball-and-socket joint. It is also preferable to cover the joint completely for reasons of hygiene because this is a reliable way of preventing dirt and/or bacteria from entering the joint and accumulating there.

The inventive structure of a toothbrush enables the grip part and the head part to be produced as separate components or consecutively. The grip part and the head part may consist of the same material and, in particular, of the same plastic. However, in a further embodiment of the invention, the grip part and the head part consist of different materials. This may have cost advantages because only the head part is placed in the mouth of the user during use of the toothbrush and therefore has to satisfy more stringent hygienic requirements than the grip part. In a preferred embodiment of the invention, the head part is made of plastic and, in particular, of polypropylene. The grip part may also be made of plastic and, in particular, of polystyrene or ABS (acrylonitrile-butadiene-styrene copolymers).

The head part can consist of one component. However, in an alternative embodiment the head part may also be divided into a first head part section carrying the set of bristles and a second head part section connected to the grip part via the joint, the first head part section and the second head part section being interconnected via a further joint. The further joint may be structured as described above in connection with the first joint, to which reference is made here to avoid repetition. In particular, a further spring element in the form of a further, at least partial outer cover is assigned to the further joint, wherein the cover may be made of a thermoplastic elastomer as stated. The further cover can be structured as at least two tendon sections as stated, but preferably the further cover seals off the further joint completely relative to the surroundings.

The two head part sections can be made of the same material or also from different materials, although preferably the same plastic, in particular, polypropylene is used for both head part sections.

The further joint can be a ball-and-socket joint or a hinged joint.

As for the method, the above task can be solved in different ways. In a first embodiment of the inventive method, the grip part and the head part are produced as separate components and then interconnected to form the joint and, in particular, assembled. Thereupon, the joint is overmolded with an elastic plastic material to form the cover and, in particular, a thermoplastic elastomer. The grip part and the head part are preferably each formed by a plastic injection-molding and are put together and overmolded with the cover using an injection-molding machine.

The head part can be produced as a single component but it is also possible to produce the head part from two head part sections, wherein to form the head part, a first head part section and a second head part section are produced independently and then interconnected to form a further joint, whereupon the further joint to form a further cover is at least partially overmolded with an elastic and, in particular, elastomer plastic material.

In an alternative embodiment of the method, a first component in the form of the grip part or of the head part is initially produced. The other component is then molded onto this first component in an injection-molding machine, i.e. the head part or the grip part, to form the joint. The materials of the grip part and of the head part are, however, not materially bonded but only connected by positive action, i.e. the head part remains moveable relative to the grip part. The joint is then, at least partially and in particular completely, overmolded with an elastic plastic material and, in particular, a thermoplastic elastomer to form the cover.

In a preferred embodiment of this method, the grip part, the head part and the cover are produced in a three-stage injection-molding process in a common mold. After the grip part has been injection-molded in a first step, the head part is molded onto the grip part in a second step, retaining the relative flexibility. Alternatively, the head part can be molded in the first step and the grip part can then be molded on in the second step. The cover that constitutes the spring element is then overmolded in the third step.

In all embodiments of the method, the cover should completely surround the joint and therefore seal it off relative to the surroundings.

Further characteristics of the method, in particular, the materials used can be derived from the above description of the toothbrush.

Further details and characteristics of the invention can be seen from the following description of example embodiments with reference to the drawing. The illustrations show:

FIG. 1 side view of an inventive toothbrush

FIG. 2 a head part as a separate component,

FIG. 3 a grip part as a separate component,

FIG. 4 the head part and the grip part after joining together,

FIG. 5 a toothbrush according to an alternative embodiment and

FIG. 6 a further embodiment of the toothbrush according to FIG. 1.

FIG. 1 shows an inventive toothbrush 10, essentially comprising a rod-shaped grip part 13 and a rod-shaped head part 11, which are disposed one behind the other in the longitudinal direction and are connected to each other at the ends facing each other to form a joint 14, wherein the joint 14 is enclosed according to FIG. 1 by a cover 19 to form a spring element 17 and is thus completely sealed-off relative to the surroundings. A set of bristles 12 is provided in the conventional way on the end of the head part 11 furthest from the grip part 13.

FIG. 2 shows the head part 11 as a single component. Herein it can be seen that a spherical joint body 15 is fashioned at the lower end nearest the grip part 13.

FIG. 3 shows the grip part 13 as a single component, comprising a joint receptacle 16 on the upper end nearest the head part 11, into which the joint body 15 of the head part 11 can engage.

The head part 11 is preferably made of plastic and is provided with a set of bristles 12. Independently of this, the grip part 13 is also made of plastic. These two components are then assembled together by inserting the joint body 15 into the joint receptacle 16, where it is preferably prevented from falling out again by positive action, in particular, by latching forces. This condition is illustrated in FIG. 4. If the joint body 15 is a sphere, the head part 14 can be freely swiveled in all directions relative to the grip part 13.

The joint 14 of the pre-assembled toothbrush shown in FIG. 4 is then completely overmolded with the cover 19 made of thermoplastic elastomer in a mold for injection molding. The cover 19 constitutes the spring element 17 which, when the head part 11 is swiveled relative to the grip part 13 as the toothbrush is used, produces forces of reaction and restoring torques that return the head part 11 to its initial position relative to the grip part 13, as soon as the load ceases to be applied.

In the depicted variant of the method, the head part 11 and the grip part 13 were produced independently of each other, then assembled together and overmolded with the cover 19 in the region of the joint 14. Alternately, it is also possible to produce just the head part 11 in a first step and then to mold the grip part 13 in an injection-molding machine onto the head part 11 in such a way that the two parts connect by positive action, but can swivel relative to each other. Of course, it is also possible to produce the grip part 13 first and then to mold the head part 11 onto it.

In a third step, the cover 19 is molded on in the region of the joint 14. All three steps can be performed in the same injection-molding machine.

In the embodiment described above, the joint 14 is a ball-and-socket joint, so that the head part 11 can swivel relative to the grip part 13 in many different directions. Accordingly, the joint 14 is completely enclosed by the cover 19 so that the required forces of reaction are always produced in the cover 19, whatever the direction in which the head part 11 is swiveled. FIG. 5 depicts a modified embodiment in which the joint body 15 of the joint 14 is a cylindrical body that is located in a joint receptacle with a complementary shape. In this way, the head part 11 can only be swiveled relative to the grip part 13 in one predetermined plane about an axis of rotation A aligned in the longitudinal direction of the cylindrical joint body 15. In this embodiment, it is not necessary for the joint 14 to be completely enclosed by the cover 19, rather the cover 19 has two tendon parts 18a and 18b that are disposed on opposite sides of the toothbrush 10. Each tendon part 18a, 18b is attached at one end to the grip part 13 and at the other and to the head part 11. If the head part 11 is swiveled relative to the grip part 13 about the axis A, a tensile force is applied to one of the tendon parts 18a, 18b, while a compressive force is applied to the other tendon part. The tendon parts 18a and 18b produce the forces of reaction that determine the resilient deformation properties of the head part.

In the embodiment depicted so far, only one joint is provided but in a further embodiment of the invention it is also possible (see FIG. 6) to make the toothbrush (10) out of three parts, wherein the three parts are positioned one behind the other and are connected to a brush handle via two joints. The grip part 13 has the structure stated in conjunction with the previous embodiment. The head part 11 is divided into an upper first head part section 11a carrying the set of bristles 12 and a lower second head part section connected via the joint 14 to the grip part 13 in the way stated above. A further joint 20 is formed between the first head part section and the second head part section that has the structure described in conjunction with the joint 14 and is structured as a ball-and-socket joint in the embodiment shown that is enclosed by a further outer cover 22 made of an elastomer plastic and is completely sealed off relative to the surroundings. The further cover 22 constitutes a further spring element 21 that determines the degree of adjustment of the upper first head part section 11a compared to the lower second head part section 11b when the toothbrush is used.

Claims

1-24. (canceled)

25. A toothbrush, the toothbrush comprising:

a grip part;

a head part, said head part carrying a set of bristles;

a joint, said joint disposed between and connecting said head part and said grip part; and

a spring element made from an elastic plastic material, said spring element having a cover which at least partially surrounds said joint.

26. The toothbrush of claim 25, wherein said cover is made from a thermoplastic elastomer.

27. The toothbrush of claim 25, wherein said cover is formed by at least two tendon parts that are attached to said grip part and said head part.

28. The toothbrush of claim 27, wherein said two tendon parts are located on opposite sides of the toothbrush.

29. The toothbrush of claim 25, wherein said cover completely encloses said joint and seals it with respect to surroundings.

30. The toothbrush of claim 25, wherein said grip part and said head part consist of different materials.

31. The toothbrush of claim 25, wherein said head part consists of plastic or of polypropylene.

32. The toothbrush of claim 25, wherein said grip part consists of plastic, polystyrene, or ABS (acrylonitrile-butadiene-styrene copolymers).

33. The toothbrush of claim 25, wherein said joint is a ball-and-socket joint.

34. The toothbrush of claim 25, wherein said joint is a hinged joint.

35. The toothbrush of claim 25, wherein said head part is divided into a first head part section carrying said set of bristles and a second head part section connected to said grip part via said joint, wherein said first head part section and said second head part section are interconnected via a further joint, said further joint having a further spring element comprising a further, at least partial, outer cover.

36. The toothbrush of claim 35, wherein said further cover consists of a thermoplastic elastomer.

37. The toothbrush of claim 35, wherein said further cover completely encloses said further joint and seals it with respect to surroundings.

38. The toothbrush of claim 35, wherein said further joint is a ball-and-socket joint or a hinged joint.

39. A method for producing a toothbrush, the method comprising the steps of:

a) producing a grip part;

b) producing a head part;

c) interconnecting the head part and the grip part to form a joint; and

d) at least partially overmolding the joint with an elastic plastic material to form a cover.

40. The method of claim 39, wherein, in step b), a first head part section and a second head part section are initially produced independently and are interconnected to form a further joint, and that further joint is then at least partially overmolded with an elastic plastic material to form a further cover.

41. The method of claim 39, wherein one of the grip part and the head part is initially produced as a first component and an other one of said the head part and the grip part is then molded on the first component to form the joint, wherein only a positive-action connection is thereby provided by the joint.

42. The method of claim 39, wherein the grip part and the head part are each formed by plastic injection-molding.

43. The method of claim 41, wherein the grip part, the head part and the cover are produced in a three-stage injection-molding process in a common mold.

44. The method of claim 39, wherein the cover consists of a thermoplastic elastomer.

45. The method of claim 39, wherein the cover completely encloses the joint and seals it off relative to surroundings.

46. The method of claim 39, wherein the grip part and the head part consist of different materials.

47. The method of claim 39, wherein the head part consists of plastic and or of polypropylene.

48. The method of claim 39, wherein the grip part consists of plastic, polystyrene or ABS.