Toothbrush

Abstract: The invention relates to a toothbrush (20) with a brush head which can be secured on a brush handle (24) by means of a bayonet catch (26). The bayonet catch comprises a locking pin (28) which is mounted in the front end of the brush handle (24) in such a way that it can be displaced axially to a limited extent but is non-rotatable and which is subject to the action of a prestressing device (50). The brush head (22) is provided with a recess (102) which has a locking groove by means of which the brush head (22) is mounted on the locking pin (28) by engagement of a bayonet stud (32) in the locking groove (106), the locking pin (28) being pulled out of the brush handle (24) counter to the prestressing device (50) until the bayonet stud (32) locks into a lock-in portion (114) of the locking groove. Since the locking groove is arranged in the bristle bed (100) of the brush head (22), a minimum use of material for the brush head, which is disposable after wearing out, is guaranteed and the brush head is reliably secured on the brush handle.

Description: The invention relates to a toothbrush, the brush head of which is connected releasably to the brush handle by a plug-in and lock-in connection. In each of EP-0 326 363 A1 and DE 31 04 383 A1 is disclosed a toothbrush which corresponds to the above-mentioned known type of a toothbrush. The first mentioned document is based on the objective to provide an oral hygienic system consisting of a disposable brush head, an aseptic container for the brush head and a grip for introducing into said container and to mount said brush head. The brush head has in its neck an axial conical recess being provided with an annular groove. The aseptic container encloses the brush head. A conical tip of a front end of said grip portion has an annular projecting ring portion which engages the annular groove within the conical recess of the tip of the front end of the grip portion if the brush head is inserted into the grip portion. The annular groove can be replaced by means of knob-shaped projections being positioned in angular and axial distances around the circumference of the conical front end of the grip portion, corresponding to openings in the conical recess within the end of the brush head. The above-mentioned second document is related to an electrical toothbrush having a driving portion and a brush being fitted on it. A shaft having projecting rods on both sides is mounted at the end of the driving portion, wherein the projecting portions engage an axial recess at the end of the brush grip. The wall of the recess of the brush shaft is provided with an aperture being completely closed within which is provided a pair of spring arms. The spring arms surround the projecting portion of the shaft and axially fix it. From DE-A-496 164 is known a releasing device having an actuating means which is slidably mounted within the brush grip. Toothbrushes of the above-mentioned known type have the advantage that, if the brush head is worn-out, it is not necessary to dispose the whole toothbrush, but only to replace the used brush head by a new brush head. The savings achieved hereby result in lesser costs for the user. But toothbrushes having such replaceable brush heads can be a danger for children, if the brush head can be already replaced by children or already released by more or less powerful handling of the brush grip during the cleansing of the teeth. The present invention intends to solve this problem by means of a toothbrush having a replaceable brush head in such a manner that there will be provided a child-proof toothbrush having a secure reliable connection between brush head and brush grip, wherein, in spite of it, the brush head can be relatively easily released from the brush grip and, if this is the case, can be replaced by a new brush head. Along with this aim, the need of material for the disposable brush head should be minimal. The invention solves this object by the features disclosed in the characterizing portion of claim 1. Hereby, there is achieved, in a way, a twofold security of the brush head against an unintended or enforced release of the brush head from the brush grip. These security means consist of one part of a locking means comprising a locking groove and a locking pin, wherein the locking pin is movable to and fro only in a limited manner, but is non-rotatably positioned and elastically biased in a direction being opposite to said brush head. A further security means of the brush head comprises a bayonet nose for engaging the locking groove of the brush head. Consequently, the locking pin must be forced out by means of the actuating means provided at the rear end towards the brush head by overcoming the biasing force of the helical pressure spring to release the brush head from the brush grip and to remove it subsequently by a rotation relative to the locking pin and to replace it by a new brush head. The manipulation as described cannot be done by small children so that a child can use toothbrushes of the present invention without any danger. Subclaims 2 to 7 disclose further convenient embodiments of the invention. The invention is explained in greater detail in the drawing by means of the schematic drawing of illustrative embodiments of the toothbrush according to the invention. In the drawing: Fig. 1 shows a vertical section through the longitudinal centre line of a toothbrush with mounted brush head, Fig. 2 shows the toothbrush in a view similar to that in Fig. 1 but with the brush head in the unlocked position, Fig. 3 shows a partially sectioned plan view of the rear side of the brush, the said rear side facing away from the bristles, Fig. 4 shows a view in accordance with IV-IV in Fig. 1 of the front end of the handle neck, the said end facing the brush handle, Fig. 5 shows a view in accordance with V-V in Fig. 1, Fig. 6 shows a curve development of the locking groove of the bayonet catch, Figs. 7, 8 and 9 show the rear end of a brush head, the side view of a locking pin and an end view of the locking pin in Fig. 8, Fig. 10 shows another embodiment of an unlocking device in a vertical section along the longitudinal centre line, Fig. 11 shows a plan view relating to Fig. 10, and Fig. 12 shows a section along the line XII-XII in Fig. 10. Figs. 1 to 3 show a toothbrush 20, the brush head 22 of which is locked to a brush handle 24 by a bayonet catch 26. The bayonet catch comprises a locking pin 28 which is mounted in a sliding bearing 30 in the forward handle neck 46 of the brush handle 24 in such a way that it is displaceable axially to a limited extent but is non-rotatable and which protrudes with its front end out of the front end of the handle neck, the said end facing the brush head 22. The free outer end of the locking pin 28 is provided with a radially projecting bayonet stud 32. The locking pin 28 is provided approximately halfway along its length with one or more longitudinal ribs 34, which engage in longitudinal grooves 36 in the sliding-bearing wall of the handle neck. The longitudinal grooves 36 are longer than the longitudinal ribs 34 of the locking pin 28 by the stroke length of the locking pin 28 and in this way ensure the limited axial displaceability of the locking pin 28. The front end 38 and the rear end 40 of the locking pin serve as cylindrical guide shanks which are guided in corresponding coaxial bores 42 and 44, respectively, of the sliding bearing in the handle neck 46. The rear shank end 40 of the locking pin 28, the said end protruding into a cavity 48 of the brush handle 24, carries a prestressing device 50 which, in the illustrative embodiment under consideration, is designed as a helical compression spring 52. The ends of the helical compression spring are supported, on the one hand, on a transverse wall 54 in the brush handle 24, the said transverse wall containing the bore 44, and on a supporting disc 56 which is secured on the inner end of the threaded pin 28. Figs. 1 to 3 furthermore show an unlocking device 60 comprising a pressure plate 62 which is mounted in longitudinally displaceable fashion in the rear end 64 of the brush handle 24. In plan view, the pressure plate is of H-shaped configuration, as Fig. 3 shows, a central web 66 of the pressure plate being mounted in an axial slot 68 in the brush handle 24 in such a way that it can be displaced backwards and forwards to a limited extent. In this arrangement, the inner plate part 70 of the pressure plate 62 normally rests against stop faces 72 in the brush handle 24. This position is secured by a wire 74 being fixed or loosely inserted in the plate part 70 at 76 and extending with longitudinal mobility through transverse walls at 78, 80, 82, 84, 86 in Fig. 2 and engaging with its end facing away from the pressure plate in a spherical cup 92 in the rear end of the locking pin 28 and resting against the latter. Since the wire is of sufficiently rigid design, the pressure plate 62 is at all times held in the position shown in Fig. 3 by the locking pin 28 subject to the action of the prestressing device 50. If the pressure plate 62 is pressed into the brush handle 24, the locking pin 28 can be moved axially out of the handle neck 46, counter to the action of the prestressing device 50, by a stroke length which permits unlocking, this stroke length being determined by the length of the longitudinal grooves 36 in the handle neck 46 for the longitudinal ribs 34 on the locking pin 28. The brush head 22 has a bristle bed 100 which, as shown in particular by Figs. 1 and 5, is distinguished in the region of an axial recess 102 by a central, longitudinally extending bulge. In this way, the parting plane between the abutting end faces of the brush head 22 and the handle neck 46 is brought extremely close to the bristles 104 of the brush element, a considerable saving in material thereby being achieved for the brush head 22, which can be discarded after a certain time in use and replaced by a new brush head. Arranged in the cylindrical wall of the recess 102 in the brush head 22 is at least one locking groove 106, the development of which can be seen from Fig. 6. According to this figure, the locking groove consists of an axial portion 108, adjoining which is a helically curved portion 110, which merges into a portion 112 extending transversely to the axial direction of the recess 102 and merging at the outer end into a lock-in portion 114 which is angled by 90° relative to portion 112 towards the rear end facing the brush handle 24 and accommodates the bayonet stud 32 in the lock-in position. 116 denotes the lock-in path which the bayonet stud with the locking pin 28 must travel into the interior of the brush handle 24, under the action of the prestressing device 50, in order to be able to reach the lock-in position or be moved back out of the lock-in position into the locking groove when the brush head 22 is to be removed from the brush handle 24. The locking groove is produced from injection-moulded plastic as an integral component of the bristle bed, as can be seen from the view in Fig. 4. 118 denotes annular sealing ribs in Fig. 4, the said ribs guaranteeing reliable sealing of the parting plane between the brush head 22 and the brush handle 24. As Fig. 5 shows, the closing angle or angle of rotation of the brush head from the mounting position to the closing position of the bayonet catch is 135°, the closing direction being indicated by the arrow X. Two diametrically opposite locking grooves 106, 106a can be seen in the brush element 22 in Fig. 7. In this case, the closing angle is only 90°. Fig. 8 shows corresponding bayonet studs 32 and 32a, these being shown in an end view in Fig. 9. Another embodiment of an unlocking device 120 is depicted in Figs. 10 to 12. This unlocking device 120 comprises an unlocking button 121, which is guided by means of a connecting pin 124 in an elongated slot 122 on the rear side of the handle neck 46, the said pin being secured on the underside of the unlocking button 121 and being firmly connected to the locking pin 28 by means of a locking peg 126. Although, in this embodiment, the locking pin 28 can likewise be provided with the longitudinal ribs 34 which engage in the longitudinal grooves 36 of the brush neck 46 in accordance with Figs. 1 and 2, the unlocking button 121 with its locking pin 124, 126 may be quite sufficient as a stop for the limitation of the axial backwards and forwards mobility of the locking pin 28, as Fig. 10 shows by means of the brush head 22, depicted in essentially broken-away form. Appropriate selection of the characteristic of the helical compression spring 52 allows the bayonet catch for the illustrative embodiments in Figs. 1, 2 and 10 to be configured in such a way that it can be used as a child-proof catch. It is self-evident that it is also possible, instead of the helical compression spring, to use tension springs, one end of which is anchored on the rear end of the locking pin and the other end of which is anchored in the brush handle 24. The springs used can, if required, like the locking pin and the unlocking devices in Figs. 1, 2 and 10, be composed completely of plastic since, if required, the wire 90 in Fig. 1 can also be composed of a relatively flexurally stiff plastics material. List of reference numerals 20 Toothbrush 22 Brush head 24 Brush handle 26 Bayonet catch 28 Locking pin 30 Sliding bearing 32 Bayonet stud 32a Bayonet stud 34 Longitudinal ribs 36 Longitudinal grooves 38 Front end 40 Rear end 42 Bore 44 Bore 46 Handle neck 48 Cavity 50 Prestressing device 52 Helical compression spring 54 Transverse wall 56 Supporting disc 60 Unlocking device 62 Pressure plate 64 Rear end 66 Central web 68 Slot 70 Plate part 72 Stop face 74 Wire 78 Transverse wall 80 Transverse wall 82 Transverse wall 84 Transverse wall 86 Transverse wall 90 Wire 92 Spherical cup 100 Bristle bed 102 Recess 106 Locking groove 106a Locking groove 104 Bristles 108 Portion 110 Portion 112 Portion 114 Portion 116 Lock-in path 118 Sealing ribs 120 Unlocking device 121 Unlocking button 122 Elongated slot 124 Connecting pin 126 Locking peg

Claims: Toothbrush, the brush head of which is connected releasably to the brush handle by a plug-in and lock-in connection, characterized in that the releasable connection between brush head (22) and brush handle (24) is designed as a bayonet catch (26), said bayonet catch (26) comprises at least one locking groove (106) in an axial recess (102) in a rear end of the brush head (22), the said end facing the brush handle (24), and a locking pin (28) in an axial sliding bearing (30) of the front end of the brush handle (24), the said end facing the brush head (22), the locking pin (28) being mounted in the sliding bearing (30) in such a way that it is movable backwards and forwards to a limited extent but is non-rotatable and being resiliently prestressed in the direction away from the brush head (22), and, at its end (38) protruding freely out of the brush handle (24), has at least one bayonet stud (32) directed radially to the locking pin (28) and intended for engagement in the locking groove of the brush head. Toothbrush according to claim 1, characterized in that at least one radial projection (34; 120, 124, 126) of the locking pin (28) engages in exclusively longitudinally displaceable fashion in at least one longitudinal guide (36; 122) with closed ends in the wall of the sliding bearing (30) in the brush handle (24). Toothbrush according to claim 1, characterized in that said sliding bearing (30) and the locking groove (106) are each an integral component of the brush handle (24) and of the brush head (22), respectively. Toothbrush according to claim 1, characterized in that, at its inner end facing away from the brush head (22), the sliding bearing (30) for the locking pin (28) is bounded by a stop of the longitudinal guide (36; 122), against which stop the inner end of the radial projection (34; 120, 124, 126), of which there is at least one, rests, the shank (40) of the locking pin (28), which shank extends out of the inner end of the sliding bearing (30) into the interior of the brush handle (24), being connected to a part of a prestressing device (50), the other part of which is arranged on the brush handle. Toothbrush according to claim 1, characterized in that the locking groove (106) in the brush head (22) consists of a curve portion (108) parallel to the axis, a curve portion (110) extending in the axial direction and over a circumferential angle of the recess (102), a portion (112) at right angles to the longitudinal axis of the recess (102) and a locking portion (114) for the bayonet stud (32) of the locking pin (28), the said portion being angled towards the rear end of the brush head. Toothbrush according to claim 1, characterized in that an unlocking device (60; 120) is assigned to the bayonet catch (26). Toothbrush according to claim 6, characterized in that the unlocking device (60, 120) has an actuating member (62; 121) which is mounted displaceably in the brush handle (24) and is connected to the locking pin (28), allowing the locking pin (28) to be moved out of the locking portion (114) of the locking groove (106) in the brush head (22) counter to the action of the prestressing device (50).

Inventors: JEANNET ROLAND, LEUTWYLER ROBERT, LEUTWYLER WERNER, JEANNET, ROLAND, LEUTWYLER, ROBERT, LEUTWYLER, WERNER
Applicants: JOHNSON & JOHNSON CONSUMER, JOHNSON & JOHNSON CONSUMER PRODUCTS, INC.
Application year: 1992
Main classification: A46B5
IPC codes: A46B5, B25G3