Brush section for an electric toothbrush

[0002] This application is a continuation of co-pending International Application PCT/EP98/04750, having an international filing date of Jul. 30, 1998.

[0003] This invention relates to a brush section for an electric toothbrush, having a carrier tube to which is fitted a bristle carrier comprising a plurality of bristles, and being adapted to plug onto a mount of a hand piece of the electric toothbrush. Further, the present invention relates to an electric toothbrush with a hand piece and a brush section of the aforementioned type.

[0004] A brush section of this type and an electric toothbrush of this type are generally known and commercially available.

[0005] An electric motor and a storage battery are accommodated in the hand piece of the electric toothbrush. The bristle carrier held on the brush section is mounted on the carrier tube for rotary or pivotal motion. When the toothbrush is activated, a rotary motion produced by the electric motor is transmitted to the bristle carrier by way of suitable shafts and joints. Hence the bristles are made to perform a cleaning movement. The bristles can be placed by a user against the surface of his teeth and thus used for dental care.

[0006] In the course of time the bristles of the brush section become worn and have to be replaced. It is partly for this reason that the brush section is designed to be plugged on the hand piece because then it can be replaced. The carrier tube of the brush section and the mount of the hand piece are coordinated to be joinable together by positive engagement. In this manner the brush section is fixedly held on the hand piece in a positive-engagement relationship thereto.

[0007] Plugging on the brush section and, in particular, pulling it off the hand piece should not require too much force of the user. This is why, as previously mentioned, provision is only made for a positive-engagement relationship between the carrier tube and the mount. A press-fit connection or the like is not possible. Consequently, the carrier tube and the mount usually display a certain play.

[0008] When the electric toothbrush is activated this play results in a movement which is oriented particularly in a radial direction but also partly in a tangential direction. This movement creates undesirable noises and vibrations of the brush section relative to the hand piece. Furthermore, said movement makes it at least more difficult for optimum transmission of the cleaning movement to the surface of the teeth.

[0009] It is an object of the present invention to devise a brush section for an electric toothbrush such that it enables a zeroplay connection with the hand piece yet does not require greater force of the user when plugging on or pulling off the brush section.

[0010] This object is accomplished with a brush section of the type initially referred to by providing spring elements arranged between the carrier tube and the mount.

[0011] The spring elements ensure that the carrier tube and hence the brush section adopts a zero-play position on the mount and hence on the hand piece. Undesirable movements of the brush section in the activated state are thus reliably prevented, as are the noises and vibrations resulting therefrom. At the same time the spring elements require no special force of the user when plugging the brush section on the hand piece. On account of the resilient characteristics of the spring elements the user has to overcome only a small resistance in order to urge back the spring elements and plug the carrier tube on the mount. Overcoming this resistance signifies no great effort and hence no reduction of comfort for the user but is taken rather as a sign that the brush section is now plugged correctly on the hand piece. Thanks to the spring elements the brush section is fixedly held on the mount of the hand piece in such a way that no relative movements arise between the profiled sleeve and the mount when the brush head is pressed (or better placed) against the surface of the teeth and when only small contact forces are applied. It is thereby ensured that even smallest movements of the mount are invariably transmitted to the mouthpiece.

[0012] In an advantageous further aspect of the present invention the spring elements are either fitted to the brush section or are fitted to the hand piece and/or the mount and/or are adapted to plug onto the mount. The spring elements can thus be assigned to the component best suited for design reasons for implementation of the same. This may be not only the brush section but also the hand piece and particularly its mount. Similarly, it is possible to design the spring elements as a separate component to be plugged on the hand piece and/or the mount.

[0013] If the spring elements are assigned to the brush section, provision is made in a first advantageous embodiment of the invention for a sleeve equipped with the spring elements and adapted to plug into the carrier tube. Hence with a view to the material selection, for example, the spring elements can be manufactured independently of the other components of the brush section. Similarly, the spring elements can be constructed with an optimum design for their intended function, without having to make allowance for any particular fringe conditions of the brush section's other components.

[0014] If the spring elements are assigned to the brush section, provision is made in a second advantageous embodiment of the invention for the carrier tube to be equipped with the spring elements. No separate component is needed, therefore, to implement the spring elements. Instead the spring elements are integrated in the carrier tube. This represents a particularly simple and convenient way to accommodate the spring elements, particularly with a view to the material outlay and production effort required.

[0015] In an advantageous further aspect of the present invention, the sleeve or the carrier tube includes as spring elements at least one shoulder having a bend that curves in the direction of the mount. The spring elements are thus implemented by means of one or several curved shoulders. This shoulder ultimately forms a type of bending bar whose curvature results in the desired resilient characteristics. Starting from the sleeve plugged onto the carrier tube or from the carrier tube the curve is oriented in the direction of the hand piece mount. When the mount is inserted in the carrier tube, the curve is oriented inwards. A certain resistance develops on the curve of the shoulder which the user is in a position to overcome using a slight pressing motion. The resilient characteristics of the shoulder then act on the brush section in such a way that it is held in the mount without play.

[0016] Particularly conveniently, the sleeve or the carrier tube is made of a plastics material. The shoulder is thus also made of plastic so that the plastic's capability of being bent has an advantageous effect on the resilient properties of the shoulder.

[0017] Further features, application possibilities and advantages of the present invention will become apparent from the subsequent description of embodiments of the invention illustrated in the Figures of the accompanying drawing. It will be understood that any single feature and any combination of single features described or represented by illustration form the subject-matter of the present invention, irrespective of their summary in the patent claims or their back reference, as well as irrespective of their wording and representation in the description and the drawing, respectively.

[0018] FIG. 1 is a schematic longitudinal sectional view of a brush section for an electric toothbrush illustrating an embodiment of the present invention; and

[0019] FIGS. 2ato 2crepresent schematically a longitudinal sectional view, a top plan view and a cross-sectional view, respectively, of a sleeve of the brush section of FIG. 1.

[0020] FIG. 1 shows an electric toothbrush 1 having a brush section 2 and a hand piece 3. The brush section 2 is plugged on the hand piece 3 but can be pulled off the hand piece 3 in order, for example, to be replaced by a different brush section 2.

[0021] The brush section 2 has an elongate carrier tube 4 with a bristle carrier 5 projecting at approximately right angles from the tube end remote from the hand piece 3. The bristle carrier 5 is equipped with a plurality of bristles 6. At its end close to the brush section 2 the hand piece 3 has a mount 7 on which the brush section 2 is plugged.

[0022] Further accommodated in the hand piece 3 are an electric motor and a storage battery. With the electric toothbrush 1 activated, a rotary or pivotal motion produced by the electric motor is transmitted by means of shafts, couplings, gears and the like to the bristle carrier 5 which thus performs a rotary or pivotal motion about an axis approximately parallel to the bristles 6.

[0023] With the electric toothbrush 1 actuated, a user can place the bristles 6 against the surfaces of his teeth and use the rotary or pivotal motion of the bristle carrier 5 to clean and care for his teeth.

[0024] A sleeve 8 is provided in the end of the brush section 2 close to the hand piece 3. In this area of the brush section 2 the carrier tube 4 is of an approximately cylindrical configuration and the sleeve 8 is plugged in the carrier tube 4. The sleeve 8 is secured against rotary movement in the carrier tube 4 as by ridges or the like engaging in grooves. Furthermore, the sleeve 8 is secured against being pulled out of the carrier tube 4 by detent elements or the like.

[0025] FIGS. 2ato 2cshow the sleeve 8 of the brush section 2 on an enlarged scale.

[0026] The sleeve 8 is of a cylindrical construction and has an essentially circular cross section. On its outside wall 9 the sleeve 8 has two circumferential annular ridges 10, 11, at least one of which can act as detent element.

[0027] In the longitudinal direction the sleeve 8 has two slots 12, 13, with a shoulder 14 constructed in between. As can be seen in FIG. 2ain particular, the shoulder 14 is equipped with a curve or bend. The latter is oriented inwards, meaning toward the smaller diameters, and hence in the direction of the mount 7 of the hand piece 3.

[0028] At least the shoulder 14 is made of a flexible or elastic material. The entire sleeve 8 in particular is made of a plastics material. The shoulder 14 thus forms a bending bar with resilient properties. Hence the shoulder 14 performs the function of spring elements.

[0029] The inside wall 15 of the sleeve 8 has a cross-sectional shape and a diameter conforming to the outside wall 16 of the mount 7 so that the mount 7 can be plugged in the sleeve 4 by positive engagement therewith. Where applicable, the sleeve 8 and the mount 7 have cross sectional shapes designed to permit the sleeve 8 and hence the brush section 2 to be plugged on the mount 7 and hence on the hand piece 3 only when turned to a certain position.

[0030] To plug the brush section 2 on the hand piece 3, the mount 7 of the hand piece 3 has to be inserted in the sleeve 8 of the brush section 2. As this occurs, the sleeve 8 is itself plugged in the carrier tube 4 of the brush section 2. When the mount 7 reaches the inward projecting bend of the shoulder 14, a certain resistance results. This resistance is overcome by pressing back the bend of the shoulder 14. The mount 6 can then be inserted fully in the sleeve 8. The brush section 2 is thus plugged fully on the hand piece 3.

[0031] In a configuration differing from the sleeve 8 as described, there can be either two or more shoulders 14. The shoulder or shoulders 14 do not have to be fastened at both ends; it is also possible for the shoulder or shoulders 14 to be fixed at one end only. The slots 12, 13 defining the shoulder or shoulders 14 may also be implemented by reductions in wall thickness to the sleeve 8 so that the sleeve is completely closed around its circumference. It is also possible for the spring elements to be incorporated generally in the sleeve 8 as elastic components in the broadest sense.

[0032] It is likewise possible for the spring elements to be arranged directly on the carrier tube 4, thereby eliminating the need for the sleeve 8. This can be accomplished, for example, by providing the shoulder or shoulders 14 directly on the carrier tube 4. At least the shoulder or shoulders 14, or the complete carrier tube 4 as well, are then made particularly of a plastics material, thus producing the desired resilient characteristics.

[0033] Another possibility is for the spring elements to be assigned to the hand piece 3 and not to the brush section 2. In this arrangement the spring elements can be provided directly on the hand piece 3 or on the mount 7. Similarly it is possible for the spring elements, for example, in the form of a sleeve or the like, to be plugged on the mount 7.

[0034] Further, the spring elements can be constructed so that they produce not only a force outwards in a radial direction but also a force in a tangential direction. This enables tangential movements of the brush section in the activated state to be prevented and vibrations and noises to be further reduced.