Electrical toothbrush

TECHNICAL FIELD

This invention relates to an electric toothbrush with a grip section, a brush head which is mounted for movement relative to the grip section, and a drive mechanism for driving the brush head in an oscillatory and/or orbital motion.

BACKGROUND

In order to accelerate the dental cleaning process and to make it more thorough, it has already been proposed to form the toothbrush head in a manner which enables a plurality of tooth surfaces to be worked on simultaneously. For example, it has thus been proposed to arrange three bristle sets at an angle of approximately 45° to each other on the brush head, and to place them in gripper-like fashion on the tooth to be cleaned, so that the tooth can be cleaned simultaneously from three sides. Cleaning three surfaces simultaneously shortens the time required for cleaning, and additionally offers the advantage that individual tooth surfaces are less easy to forget during cleaning.

However, the arrangement of a plurality of bristle sets for the purpose of cleaning a plurality of tooth surfaces makes the brush head disproportionately large. In order to give the bristles a certain softness, they must have a corresponding length when using the currently typical filaments. As a result, the cleaning head becomes very large. The size of such brush heads is perceived to be uncomfortable in the mouth, resulting in the brush often not being pushed all the way to the rearmost molars. Furthermore, the teeth are hugged only to a limited extent. As a result, particularly the round canine teeth areas and the incisors, which have varying occlusal and coronal thicknesses, are not cleaned optimally.

German patent DE 693 24 373 T2 discloses a toothbrush, in which the brush head has a part that is shaped to conform to the contour of a molar, and which has on its U-shaped inside surface with a set of bristles, which work on the molar from three sides. However, this shaped part which forms the brush head is very bulky and suffers from the disadvantages outlined above.

SUMMARY

One aspect of the present invention features an electric toothbrush with a grip, a brush head which is mounted for movement relative to the grip section and a drive mechanism for driving the brush head in an oscillatory and/or orbital motion. The brush head has a cleaning element, for example a cleaning fork, the legs of which have a piece of plush or velvet on their insides. No array of bristle sets on a plurality of sides is provided. Instead, a cleaning element is provided which is lined with a thin, non bulky piece of plush or velvet, allowing the toothbrush head to have a compact design despite hugging the respective tooth on a plurality of sides. In conjunction with the plush or velvet lining, the oscillatory and/or orbital driving motion of the brush head results in excellent interproximal cleaning. An individual tooth can be cleaned simultaneously from all three sides, i.e., from the buccal, lingual, and occlusal sides, resulting in a more thorough and faster cleaning. By using the piece of plush or velvet instead of bristle sets, a compact brush head, which is perceived as being comfortable in the mouth during usage, can be achieved.

The piece of plush or velvet can be a piece of fabric with a pile, for example, and both the piece of fabric and the pile can be made of polyamide.

Although a variety of velvet or plush pieces can be used, in an effective example the pile has a depth of approximately 2-8 mm, preferably approximately 3-6 mm.

In this arrangement, the depth of the pile may vary across the cleaning element. The pile of the piece of plush or velvet may have a greater depth at the free end of the legs of the cleaning fork, than at a root or foot section of the legs.

The pieces of plush or velvet have pile yarn, which has a thickness ranging from 0.05-0.2 mm, for example about 0.1 mm. The thickness of the pile yarn may also vary across the cleaning element. For example, in some embodiments, the pile yarn at the free ends of the legs is thinner than in the root or foot sections of the legs.

In some embodiments, only the legs of the cleaning fork are equipped with one piece of plush or velvet each. In some other embodiments, a cross bar which connects the legs of the cleaning fork may also be provided with a piece of plush or velvet on the inside, resulting in a U-shaped plush or velvet lining on the inside contour of the cleaning fork.

In order to be able to adapt the cleaning fork to a variety of tooth contours, and to clean teeth of varied widths with uniform efficiency, in some embodiments the cleaning fork is formed in such a way that the legs are capable of springing relative to each other. The legs of the cleaning fork may be sprung themselves. Alternatively, they may be formed in a manner of a joint in their foot or root area and be acted upon by a spring which biases the legs towards each other. The legs can be designed to be sprung in their entirety, as a result of which better adaptation to the tooth contour is achieved. The distance between the legs can be chosen so that the cleaning fork expands slightly when placed on a tooth, resulting in the legs being spring-biased against the flanks of the teeth.

The legs of the cleaning fork may enclose an angle of 15° to 45° between each other. The free ends of the legs may be expanded in a bell-shaped configuration.

In some embodiments, the cleaning fork has two legs, i.e., it may be formed as a simple, U-shaped fork. In another embodiment, the cleaning fork has four legs which extend in pairs on opposite sides. With the aid of such a double fork, both the mandibular teeth and the maxillary teeth can be cleaned simultaneously. If appropriate, the legs on the one side may be at a smaller relative distance than the legs on the other side, as a result of which the different widths of fork can be used for different tooth areas.

In some embodiments in order to be able to place the brush head on a row of teeth without corresponding accurate alignment of the grip section of the toothbrush, in a further development of the invention the brush head is mounted on a brush head carrier for rotation about a transverse axis which extends substantially perpendicular to the longitudinal axis of the toothbrush, such that the brush head is not driven in relation to this transverse axis. At the toothbrush end facing away from the grip section, the transverse axis extends parallel to the direction in which the cleaning fork is placed on the teeth. It can extend through the plane of symmetry of the cleaning fork. Preferably, the possible angle of rotation is sufficiently large to allow the cleaning fork which has been placed on the teeth to be moved from the left-hand side of the jaw to the right-hand side of the jaw without lifting the cleaning fork from the teeth.

The rotary mounting of the brush head about the non-driven transverse axis is preferably of the retarding type so that, although the brush head can be rotated arbitrarily, it comes to a standstill in the respective position in the absence of the action of forces.

The drive mechanism may be constructed differently in terms of the generated drive motions of the brush head. According to another aspect of the invention, the drive mechanism has a drive axis which is parallel to the longitudinal axis of the toothbrush, and about which the brush head is adapted to be driven in a preferably conically orbital motion. Particularly good cleaning results can be achieved with the plush or velvet lined cleaning element by providing for a nutating drive motion of the brush head about the longitudinal axis of the toothbrush. A cleaning motion in three directions is accomplished with the aid of a suitable nutating drive, namely along the tooth height, across the width of the tooth, and perpendicular to the primary tooth surface, or in any desired combination of these directions, and as a result dirt can be removed thoroughly.

In order to drive the brush head conically in an orbital path about the longitudinal axis of the toothbrush, the brush head may be seated upon a brush head carrier, which is constructed as a driving rocker. The brush head carrier can be mounted in the fashion of a ball-and-socket joint, at a pivot point between the brush head and a motor arranged in the grip section, and having a drive coupling element at its end remote from the brush head. The design of the brush head carrier as a spatial rocker which is driven in a double-conical orbital motion achieves a multi-axis cleaning motion using a simple construction. The brush head carrier can be mounted non-rotatably about its longitudinal axis, and as a result it does not rotate about itself during the nutating motion about the longitudinal axis of the toothbrush. The brush head carrier may be fastened at the pivot point to an elastic bearing element, which allows an at least limited motion of the brush head carrier in the manner of a ball-and-socket joint.

Preferably, the drive coupling element of the brush head carrier is of the releasable type, in which the brush head carrier is releasably secured to a brush shank, which connects the brush head to the grip section, so that the brush head carrier is exchangeable, i.e., it is detachable from the remainder of the toothbrush and replaceable in the manner of a refill.

A releasable connection can also be provided between the brush head and the brush head carrier, allowing the brush head to be exchanged, i.e., to be detached from the brush head carrier and replaced with a refill.

A driving rocker can be provided in order to drive the brush head carrier. The driving rocker is mounted in the manner of a ball-and-socket joint at a pivot point on the grip section and is driven in a spatially orbital motion by the motor which is arranged in the grip section. For this purpose, an eccentric member may be seated on the motor shaft. The eccentric member is in engagement with the motor-side end of the driving rocker. The brush head-side end of the driving rocker is engageable with the brush head carrier, which is also formed as a driving rocker, so that the conically orbital motion of the driving rocker is translated into a corresponding motion of the brush head carrier. The driving rocker has a releasable connection member for releasable connection to the brush head carrier.

In some embodiments, the driving rocker is non-rotationally mounted about its longitudinal axis, being fastened to an elastic bearing element at the pivot point on the grip section side. In this way, the grip section can be hermetically sealed in a simple manner, as there is no relative movement between the bearing element and the driving rocker.

As an alternative to the driving rocker on the grip section side, a drive shaft, which projects from the grip section and has a drive member which rotates eccentrically, can be provided for driving the brush head carrier. The drive member is engageable with the end of the brush head carrier, which is on the grip section side. In this case, a radial shaft seal is provided at the point at which the drive shaft passes through the forward end of the grip section.

The connection between the drive member on the grip section side, i.e., the driving rocker or the rotary drive shaft with eccentric member, and the brush head carrier may be designed to substantially have zero play. As a consequence, the drive motion of the drive member on the grip section side is translated into a corresponding orbital drive motion of the brush head carrier, which is formed as a rocker.

It may however also be desirable to translate only part of the drive motion of the drive member on the grip section side into a corresponding drive motion of the brush head carrier. To do this, the connection between the driving rocker on the grip section side, or the rotating eccentric member on the grip section side and the brush head carrier may display at least limited play in at least one direction transverse to the longitudinal direction of the toothbrush. For example, the driving rocker on the grip section side may sit in an elliptic or oval sleeve which is secured to the brush head carrier. The brush head carrier may also have a slotted recess at its end close to the grip section. The driving rocker of the grip section is seated in the slotted recess. As a consequence of this arrangement, the amplitude of the drive motion of the drive member on the grip section side is transmitted in full in one direction, but in the direction perpendicular thereto, it is transmitted only in part, or not at all.

In some cases, the drive mechanism includes an adjusting device for adjustment of the stroke of the brush head motion. The adjusting device allows adjustment of the lever ratios of the driving rocker on the grip section side and/or the brush head carrier which is also constructed as a driving rocker. For example, the pivot point, at which the brush head carrier is mounted in the manner of a ball-and-socket joint, may be displaced in the longitudinal direction of the toothbrush. It is equally conceivable to displace the corresponding pivot point of the driving rocker on the grip section side. As an alternative or as an addition, the point of application of the eccentric member seated on the motor shaft may be changed at the driving rocker on the grip section side. The adjustable stroke of the nutating motion of the brush head enables the motion of the brush head to be adjusted from gentle, i.e., short motions, to strong, i.e., large motions, according to the preferences of the user.

The brush head carrier does not necessarily have to be driven in a conically orbital motion about the longitudinal axis of the toothbrush. In some embodiments, the drive mechanism can have a drive axis which is parallel to the longitudinal axis of the toothbrush and about which the brush head is driven in an oscillatory rotational motion. As an alternative or as an addition, the drive mechanism may have a drive axis which is parallel to the longitudinal axis of the toothbrush, and along which the brush head is adapted to be driven in a translatory oscillating motion, i.e., the brush head is moved back and forth. As an alternative or as an addition, the drive mechanism may also have a further drive axis which extends in a direction transverse to the longitudinal axis of the toothbrush and about which the brush head is driven in an oscillatory rotational motion. This transverse axis may extend parallel to a plane of symmetry of the cleaning element, and may preferably be arranged substantially at the end of the grip section on the brush head side. Accordingly, the brush head with the plush or velvet lined cleaning element is swiveled to and fro to the right and to the left in an oscillating motion. As an alternative or as an addition, a drive axis may also be provided which extends perpendicular to the plane of symmetry of the cleaning element, which is also preferably arranged at the end of the grip section on the brush head side. Accordingly, the brush head is rocked up and down at the tooth flanks, as a result of which any dirt which is located in the interproximal spaces can be removed.

The piece of velvet or plush may be fastened to the cleaning element in a variety of ways. The piece of velvet or plush may be secured to the cleaning element by forming a firm bond between the materials involved. In particular, the respective piece of velvet or plush may be adhesively bonded to the inside of the cleaning fork, for example, by means of a silicone adhesive, or it may be secured by hot-sealing.

As an alternative or as an addition, the piece of velvet or plush may be fastened by positive engagement, for example, the respective piece of velvet or plush may be clamped by its edges under a clamping bar of the cleaning element, or of a plush supporting structure attached to it.

If appropriate, the piece of velvet or plush may be secured by just its edges to the free ends of the legs of the cleaning fork. Additionally, the piece of velvet or plush can be secured to the bottom of the cross bar connecting the legs, so that the piece of velvet or plush is only tensioned in a V-shaped configuration, such that it does not make full surface contact with the inside contour of the legs of the cleaning fork. Only when the cleaning fork is pushed onto the tooth being cleaned does the velvet or plush strip make full surface contact with the inside contour of the legs and/or the outside contour of the tooth.

Further objects, advantages, features, and application possibilities are set out in the subsequent description of preferred embodiments with reference to the accompanying drawing.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic, perspective view of an electric toothbrush having a velvet- or plush-lined cleaning fork capable of being driven by a nutating drive;

FIG. 2 is a schematic, perspective view of an alternative, U-shaped cleaning fork and of a tooth onto which the cleaning fork can be placed, the cleaning fork being designed for the toothbrush of FIG. 1;

FIGS. 3A-3C are schematic views of a variety of embodiments of an eccentric member which is seated on the motor shaft for the nutating drive of the toothbrush of FIG. 1;

FIG. 4 is a schematic, perspective view of an electric toothbrush similar to FIG. 1, wherein the nutating drive has a drive shaft with an eccentric member instead of a driving rocker which rotates spatially;

FIG. 5 is a schematic, perspective view of an embodiment of the electric toothbrush, wherein a bell-shaped cleaning fork is mounted on a brush head carrier for rotation about a transverse axis, the brush head carrier being capable of being driven in nutating fashion;

FIG. 6 is a longitudinal section of a schematic partial view of another embodiment of the electric toothbrush;

FIG. 7 is a longitudinal sectional view of the electric toothbrush of FIG. 6 taken along the line A-A of FIG. 6;

FIG. 8 is a cross-section through the brush shank of the toothbrush of FIG. 6 taken along the line B-B of FIG. 6;

FIG. 9 is a cross-section through the brush head of the toothbrush of FIG. 6 taken along the line C-C of FIG. 6;

FIG. 10 is a schematic representation of the cleaning fork of the toothbrush of the preceding FIGS. 6 to 9 when it is placed on an incisor;

FIG. 11 is a schematic representation of the cleaning fork of the toothbrush of the preceding FIGS. 6 to 9 when it is placed on a molar;

FIG. 12 is a partial schematic plan view of a brush head for a toothbrush according to FIG. 6 which carries an additional lateral weight;

FIG. 13 is a representation showing the function of the toothbrush of the preceding FIGS. 6 to 9 placed on a row of teeth, which highlights the capability of the cleaning fork to rotate about a transverse axis;

FIG. 14 is a longitudinal section of a schematic partial view of an electric toothbrush according to another embodiment, wherein the toothbrush has a double fork with legs pointing upward and downward;

FIG. 15 is a longitudinal sectional view of the toothbrush of FIG. 14 taken along the line E-E of FIG. 14;

FIG. 16 is a cross-section through the brush shank of the toothbrush of FIG. 14 taken along the line F-F of FIG. 14;

FIG. 17 is a cross-section through the brush shank of the toothbrush of FIG. 14 taken along the line G-G of FIG. 14;

FIG. 18 is a cross-section through the brush head of the toothbrush of FIGS. 14 and 15 taken along the line H-H of FIG. 14;

FIG. 19 is a longitudinal section of a schematic partial view of an electric toothbrush according to another embodiment;

FIG. 20 is a longitudinal section of a schematic partial view of an electric toothbrush according to another embodiment;

FIGS. 21A and 21B illustrate a schematic representation of a cleaning fork having a piece of plush fastened to the free ends of the legs and to the base of the cleaning fork, wherein FIG. 21A shows the cleaning fork prior to being placed on a tooth for cleaning and FIG. 21B shows the cleaning fork following its placement on the tooth;

FIGS. 22A and 22B illustrate a die for forming a piece of plush or velvet for a cleaning fork of a toothbrush from the preceding Figures, wherein FIG. 22A shows the piece of plush or velvet prior to forming and FIG. 22B shows the piece of plush or velvet subsequent to its forming in the die; and

FIG. 23 is a schematic representation of a piece of plush or velvet which is secured to the legs of a cleaning fork by making positive engagement therewith.

DETAILED DESCRIPTION

The toothbrush shown in FIG. 1 has a grip section 1 and a brush head 2, which is connected to the grip section 1 by means of a brush tube 3. The brush head 2 is mounted for movement relative to the brush tube 3 and is adapted to be driven by a drive mechanism 5 in a manner which will be described in more detail below.

A housing 4 of the grip section 1 accommodates a motor 6, which in the shown embodiment is supplied with energy from batteries 7. The batteries 7 are arranged in the grip section 1 behind the motor 6 and may be in the form of primary or secondary batteries. If secondary batteries are used they can be charged inductively or via contacts by means of a charging device not illustrated here in greater detail.

The motor 6 comprises a motor shaft 9 which extends substantially parallel to the longitudinal axis 8 of the toothbrush and has a disc-shaped eccentric member 10 seated thereon. The eccentric member 10 is pivotally connected to a driving rocker 11 in order to drive it in a conically orbital motion. The driving rocker 11 penetrates through the forward end of the housing of the grip section 1, so that it extends from within the grip section 1 through the forward end and into the brush tube 3. It is mounted in the fashion of a ball-and-socket joint on the forward end wall 12 of the grip section housing 4. In this arrangement, the ball-and-socket-joint-like pivot point 13 is formed by means of a rubber-like, plug-type sealing element 14, in which the driving rocker 11 is inserted. The sealing element 14 sits in the passage opening 15 in the forward end wall 12 of the grip section housing 4, in order to seal the point at which the driving rocker 11 passes through the grip section housing 4.

The driving rocker 11 sits in a non-rotating relationship in the sealing element 14 so that it does not rotate about itself when it is driven by the eccentric member 10 in a conically orbital motion about the longitudinal axis of the toothbrush. This significantly facilitates sealing.

With its end remote from the motor 6, the driving rocker 11 is pivotally connected via a coupling element 16 to a brush head carrier 17, as a result of which the drive motion of the driving rocker 11 is transferred onto the brush head carrier 17. In the embodiment shown in the drawing, the coupling element 16 is a coupling sleeve receiving the forward end of the driving rocker 11, the coupling sleeve being rigidly fastened to the end of the brush head carrier 17.

The brush head carrier 17 is mounted via a ball-and-socket joint 18 on a sliding member 19 which is slidably mounted in longitudinal direction of the toothbrush on the brush tube 3 and is adapted to be locked in a desired position by means of notches 20, for example. As shown in FIG. 1, the sliding member 19 and the brush head carrier 17 are arranged in the interior of the hollow brush tube 3. Via an inserted profile ring 21, the brush tube 3 is releasably secured to a brush tube mounting 22 on the forward end wall 12 of the grip section 1.

The brush head carrier 17 emerges at the forward end of the brush tube 3 on the side remote from the grip section 1 and carries the brush head 2 at its forward end. In the embodiment shown in the drawing, the brush head 2 comprises a cleaning fork 23 which is secured by means of a releasable connection 24 to the brush head carrier 17. In the embodiment shown, the cleaning fork 23 is constructed as a simple U-shaped fork having two legs 25 which are preferably sprung in a manner which allows them to spring in a direction away from each other. In the embodiment shown, the two legs 25 are biased against each other by means of a pressure spring 26. Where applicable, the legs 25 may have a joint in their connecting area. In some embodiments, they are injection molded from plastic, so that the legs 25 possess sufficient elasticity to allow them to spring to an open and a closed position. The biasing of the legs 25 causes the legs 25 to engage the outer sides of a tooth in the desired fashion.

As shown in FIG. 1, contoured cleaning element holders 27 are attached to the free ends of the legs 24 on the insides thereof. The cleaning element holders are provided with one cleaning element 28 each on the inside, in the form of a piece of plush or velvet 29. The cleaning element holders 27 are releasably secured by means of releasable connecting elements 30, for example locking clips, to the legs 25 of the cleaning fork 23. As shown in FIG. 1, the cleaning element holders 27 and the cleaning elements 28 attached to them extend in a direction substantially transverse to the longitudinal direction of the brush head carrier 17. They widen in a bell-shaped configuration towards one end, and as a result they can be pushed on to the tooth with greater ease. In some embodiments, the cleaning elements 28 are rotatable relative to the brush head carrier 17 about a transverse axis which extends parallel to the plane of symmetry of the cleaning fork 23, so that the cleaning fork 23 can slide from the left-hand side of the jaw to the right-hand side of the jaw while sitting on the teeth, and without it being necessary to turn over the grip section. The cleaning fork 23 is therefore capable of rotating about the Z-axis shown in FIG. 2 which is perpendicular to the primary surface of the tooth. The rotatability is preferably of the decelerated or retarding type so that the brush head comes to a standstill in the respective position in the absence of any forces acting on it.

Due to the rotation of the motor shaft 9, the eccentric member 10 rotates, causing the pivot point 31 of the driving rocker 11 at the eccentric member 10 to describe a circular path, and the driving rocker 11 to describe a conical or double-conical orbital path. As the driving rocker 11 performs no rotation about its own axis, it is possible to hermetically seal the grip section in a simple manner through the bearing and sealing element 14.

The opposite end of the driving rocker 11, which is engaged with the coupling element 16, performs a corresponding motion along a circular path, with the diameters of the circular paths being proportional to the lever lengths l¹and l₂(see FIG. 1). The opening angle of the two resulting cones of the orbital motion is α₁in each case (see FIG. 1).

Because the driving rocker 11 is received within the coupling element 16, the motion of the driving rocker 11 is transferred onto the brush head carrier 17, with the brush head carrier 17 advantageously not rotating about itself either, so that a rubber elastic bearing element can be used here as well for the ball-and-socket joint 18. Depending on the geometric conditions, particularly on the distance l₃between the joint 18 and the point of engagement of the coupling element 16 and the driving rocker 11, a cone angle α₂(see FIG. 1) results for the likewise double-conical orbital motion of the brush head carrier 17. By means of an offset of the point of attachment of the respective cleaning element holder 27 on the leg 25 by the angle β (see FIG. 1) relative to the centerline or longitudinal axis of the brush head carrier 17, the cleaning element 28, which is arranged perpendicular to the brush head carrier axis, performs a three-dimensional motion relative to a standing tooth in height direction z, in length direction x and in width direction y, as can be seen more clearly from FIG. 2.

Through displacement of the sliding member 19 within the brush tube 3, the position of the point of engagement 32 of the driving rocker 11 and the brush head carrier 17 changes within the coupling element 16, and with it the amplitude of the transferred motion. Through displacement of the sliding member 19, the cone angle α₂of the orbital motion of the brush head carrier 17, and therefore the amplitude of the motion of the cleaning fork 23, can be adjusted. The adjusting device formed by virtue of the displaceability of the sliding member 19 allows the cleaning motion to be adjusted to the preferences of the user.

The amplitude of the cleaning motion may also be adjusted via the eccentricity e of the eccentric member 10. FIG. 3 shows various possible embodiments of the eccentric member 10, which may be replaceably secured to the motor shaft 9. Eccentric members 10 may also find application where an infinitely variable adjustment of the pivot point 31 of the driving rocker 11 is possible.

Furthermore, an adjustment of the amplitude of the cleaning motion may also be achieved by means of an adjustment of the length l₄, i.e., the distance between the cleaning fork 23 and the pivot point 18 of the brush head carrier 17. For example, the brush head carrier 17 can be pulled out and extended, or the cleaning fork 23 can be fastened in a manner which allows it to be displaced in the longitudinal direction of the brush head carrier 17 relative to the latter.

The amplitude of the cleaning motion is defined by the eccentricity e (see FIG. 3) of the eccentric member 10, the lever lengths l₁to l₄and the angle β. Through adjustment of the eccentricity, the lever lengths l₁to l₄and the angle β it is possible to adjust the variables δ_x, δ_yand δ_zin relation to the motion axes shown in FIG. 2, e.g., from 0 mm-10 mm, with an infinitely variable adjustment.

Due to the tension of the legs 25 of the cleaning fork 23 in the direction of the tooth width y (see FIG. 2), i.e., the resilient bias of the legs 25 towards each other, and due to a flexible mounting of the cleaning elements 28 or the cleaning element holders 27 on the legs 25, the cleaning elements 28 can always make full surface contact, on both sides, with both wide molars and narrow incisors.

FIGS. 2 and 5 show another embodiment of the cleaning fork 23. In comparison to the embodiment shown in FIG. 1, the cleaning fork is arranged rotated through 90°, so that the entire insides of the legs 25 can be directly lined with a piece of plush or velvet 29. The cleaning fork 23 is formed U-shaped in cross-section, with the free ends of the legs 25 expanding outwardly in a bell-shaped configuration. The cleaning fork 23 is mounted on the brush head carrier 17 in a manner which permits rotation about an axis of rotation 33 which is arranged perpendicular to the longitudinal axis of the brush head carrier 17. The corresponding swivel joint 34 is preferably of the retarding type causing deceleration of the rotary motion of the cleaning fork 23 about the axis of rotation 33. Due to the arrangement of the cleaning fork 23 shown in FIG. 5, it can slide from the left-hand side of the jaw to the right-hand side of the jaw while sitting on the teeth, and while the cleaning fork rotates relative to the brush head carrier 17. As shown in FIG. 2, the cleaning fork is lined with plush or velvet also on the bottom of the “U” shape, i.e., also on the cross bar connecting the two legs 25. As a result, it is possible to achieve efficient, tooth-hugging cleaning, during which the upper sides of the teeth are also cleaned at the same time.

FIG. 4 shows an embodiment which is slightly modified in comparison to FIG. 1 and differs in terms of the driving rocker 11. Instead of a driving rocker 11, a drive shaft which rotates with an eccentric member is provided. The motor shaft 9 protrudes from the forward end of the grip section 1 and extends into the brush tube 3. At its end close to the brush head carrier 17, the motor shaft 9 includes an eccentric member 10 which is formed as an elbowed hook, in the embodiment shown. The eccentric member 10 engages in the coupling element 16 provided on the brush head carrier 17, and drives the brush head carrier 17 again in a double-conical orbital motion via the coupling element 16. In order to provide a seal between the motor shaft 9 and the grip section housing 4, a radial shaft seal 35 is provided which sits in the corresponding recess in the forward end wall 12, through which the motor shaft 9 extends. In all other aspects, the embodiment of FIG. 4 corresponds to the embodiment of FIG. 1, as a result of which like reference numerals are used for like parts and reference is made to the preceding description.

In the embodiment of FIGS. 6 to 9, the brush head 2 is not driven by a brush head carrier moving in an orbital path on a double cone, but it is instead driven in an oscillatory motion. A drive shaft 9 projects from the forward end of the grip section 1 of the electric toothbrush. The drive shaft 9 performs at least one of the following motions: an oscillatory rotational motion 36 about the longitudinal axis 8 of the toothbrush or the drive shaft axis which coincides with this; an oscillatory rotational motion 37 about a swivel axis 38 (see FIG. 6), which extends transversely to the longitudinal axis of the toothbrush, and, advantageously, extends in the forward end portion of the grip section 1, and substantially perpendicular to the plane of symmetry 39 of the cleaning fork 23 (see FIG. 9); an oscillatory rotational motion 40 about a swivel axis 41, which extends transversely to the longitudinal axis 8 of the toothbrush and substantially parallel to the plane of symmetry 39 of the cleaning fork 23 (see FIG. 7); and a translatory oscillation 42 in a direction parallel to the longitudinal axis 8 of the toothbrush.

The drive shaft 9 seats the brush tube 3, which is secured by means of catches, not shown, in a detachable manner.

The front part of the brush tube 3 on the side close to the brush head 2 includes a rectangular channel 43 into which two arms 44, which are integrally molded onto a bearing element 45, are inserted. Each arm 44 carries a lug 46, each of which engage in a respective aperture or cutout 47 of the brush tube 3. This enables the bearing element 45 to be inserted from the forward end into the brush tube 3 for attachment thereto. In the interior of the brush tube 3 are four grooves 48, by virtue of which in conjunction with the two cutouts 47 two spring arms 49 result. The free end of the spring arms 49 rests on a free end 50 of the arms 44. When the user exerts pressure on the spring arms 49 in the area of rounded protuberances 51 (see FIG. 8), the lugs 46 are disengaged. This enables the bearing element 45 to be pulled out from the brush tube 3.

The cleaning fork 23 is rotatably mounted in a bore 52 of the bearing element 45, and has a bearing journal 53 with an axis 54, two legs 25 and a cross bar 55 connecting the two legs 25. The bearing journal 53 has two lugs 56 and a slot 57 at its free end, through which the lugs 56 are capable of springing back inwardly. For assembly the bearing journal 53 is pressed into the bore 52 of the bearing element 45, such that the lugs 56 are pressed together against the spring action. After passing through the bore 52, the lugs 56 expand again due to the spring action, so that the bearing journal 53 is rotatable, but sits axially fixed in the bearing element 45.

The cleaning fork 23 can be infinitely rotatable relative to the bearing element 45. However, in the embodiment shown, the rotatability of cleaning fork 23 is limited by a rotation stop 58 (see FIG. 6).

As shown in FIG. 9, the legs 25 enclose an angle γ which is preferably between 15° and 45°. At their free end they have a bell-shaped curved portion 59 which is bent outwardly.

The inside of the legs 25 and the cross bar 55 connecting the legs 25 carries a piece of velvet or plush 29, which may be secured by means of adhesive bonding, hot-sealing or by other methods.

Preferably the piece of velvet or plush 29 comprises a piece of fabric 60 and a pile 61, which may both be made of polyamide. In the region of the cross bar 55 and the adjoining legs 25 the threads of the pile 61 may preferably have a thickness of 3/1000 to 5/1000 of an inch, and at the bell-shaped curved portion 59 of the legs 25 they preferably have a thickness of 2/1000 to 4/1000 of an inch. The thickness of the threads of the pile 61 may vary within a region.

The depth of the pile 61 may vary. Advantageously, the depth H₁of the pile 61 in the region of the cross bar 55 is approximately 2 mm to 6 mm, while the depth H₂of the pile 61 at the legs 25 and their bell-shaped curved portions 59 may amount to approximately 4 mm to 8 mm. The depths H₁and H₂may also vary within their regions.

In the embodiment shown, the distance 62 between the longitudinal axis of the brush tube 3 and a free area of the pile 61 is preferably approximately −6 mm to +6 mm.

FIGS. 10 to 13 clarify the way in which the toothbrush works. The cleaning fork 23 can be placed with the cleaning elements 28 made of plush or velvet on a tooth 63 or 64. The elasticity of the legs 25 of the cleaning fork 23 and of the pile 61 of the piece of plush or velvet 29 compensates for the varying thicknesses of incisors 63, shown in FIG. 10, and molars 64, shown in FIG. 11. When the drive shaft 9 performs the oscillatory rotational motion 36 about the longitudinal axis 8, the vestibular, occlusal and lingual dental surfaces are cleaned simultaneously.

As becomes apparent from FIG. 13, the axis of rotation 33, about which the cleaning fork 23 can be rotated relative to the bearing element 45 of the brush head carrier 17, enables the toothbrush to be drawn from the left-hand side of the jaw 65 to the right-hand side, while the cleaning fork is placed on the teeth. To clean the entire jaw 65, the user holds the grip section 1 and draws the cleaning fork 23 together with the piece of velvet or plush 29 under continuous oscillatory drive motion of the brush head slowly across all of the teeth in the jaw 65. By virtue of the rotatability of the cleaning fork 23 about the axis of rotation 33 all teeth are evenly cleaned.

As shown in FIG. 12, the cleaning fork 23 may be equipped with an additional weight 66 positioned at a distance from the axis of rotation 33, which causes an imbalance of the cleaning fork 23. This enables the cleaning fork 23 to perform an oscillatory rotational motion 67 about the axis of rotation 33 when the oscillatory rotational motion 36 acts about the longitudinal axis 8 of the toothbrush.

FIGS. 14 to 18 show a variant of the toothbrush from the preceding Figures. The end portion of the brush tube 3 on the side close to the brush head 2 contains an oval channel 43 with two slots 68, into which two arms 44, which are integrally molded onto the bearing element 45 of the brush head carrier 17, are inserted. A free end 50 of the arms 44 lies in the interior of the channel 43, each arm 44 carrying a lug 46, each of which engage within a respective aperture or cutout 47 of the brush tube 3. This arrangement secures the bearing element 45 in the brush tube 3. When the user exerts pressure on the arms 44 in the area of rounded protuberances 51 then the lugs 46 are disengaged, enabling the bearing element 45 of the brush head carrier 17 to be pulled out from the brush tube 3.

A cleaning fork 23 constructed as a double fork is mounted in a bore 52 of the bearing element 45. The cleaning fork 23 has a bearing journal 53 with an axis 54, four legs 25 which stand in pairs facing in opposing directions and a respective cross bar 55 which connects each of the pairs of legs 25. The assembly with the bearing element 45 and the cleaning fork 23 may be manufactured using the two-component injection molding method in which first the bearing element 45 is injection molded from plastic and then the cleaning fork 23, which is formed as a double fork and is made of plastic, is injection molded onto the bearing element 45. In the process, the bearing journal 53 of the cleaning fork 23 shrinks to an extent producing a radial clearance sufficient to provide rotatability of the cleaning fork 23 about the axis of rotation 33. In order to produce the axial clearance the injection mold may have a tongue in a gap 69 between the bearing element 45 and one of the cross bars 55.

It will be understood that it would also be possible to manufacture the cleaning fork 23 which is formed as a double fork and the bearing element 45 by other means. For example, the bearing element 45 and/or the cleaning fork 23 may be formed as a two-part structure.

The insides of the forks formed by the legs 25 and the cross bars 55 are each fitted with a piece of velvet or plush 29 in the manner described in the foregoing.

The embodiment of FIGS. 14 to 16 allows the teeth on the upper jaw and lower jaw to be cleaned simultaneously.

In the embodiment of FIG. 19, a latch 70 having a collar 71 is mounted in the channel 43 of the brush tube 3 for displacement parallel to the longitudinal axis 8 of the toothbrush. The latch 70 is urged by a spring 72 against the end of the drive shaft 9. With the brush tube 3 seated on the drive shaft 9, the forward end of the latch 70 lies between the free ends 50 of the arms 44, as a result of which the bearing element 45 cannot be separated from the brush tube 3. In this way, accidental release of the bearing element 45 by the user is prevented. If the brush tube 3 is taken off the drive shaft 9, then the spring 72 slides the latch 70 rearward, as a result of which the free ends 50 of the arms 44 are released. Now the bearing element 45 can be pulled off from the brush tube 3 by virtue of the user exerting pressure on the rounded protuberances 51.

In the embodiment of FIG. 20 the arms 44 of the bearing element 45 are so long that their free ends 50 lie to both sides of the forward end of the drive shaft 9 when the brush tube 3 is pushed onto the drive shaft 9. In this state the bearing element 45 cannot be separated from the brush tube 3, similarly to the embodiment of FIG. 14. When, by contrast, the brush tube 3 is taken off from the drive shaft 9, then the free ends 50 of the arms 44 are released, as a result of which the bearing element 45 can be pulled off from the brush tube 3 by virtue of the user exerting pressure on the rounded protuberances 51.

Advantageously, by suitably dimensioning the cleaning fork 23, in particular its legs 25 and cross bar 55, a natural bending frequency of the legs 25 that is identical to the frequency of the oscillatory rotational motion 36 about the longitudinal axis 8 of the toothbrush can be achieved. As a result, the legs 25 perform a bending oscillation 73 (see FIGS. 9 and 18), which enhances the cleaning action.

It will be appreciated that the cross-section of the channel 43 at the forward end of the brush tube 3 does not necessarily have to be rectangular or oval; other cross-sectional shapes are also possible.

In some embodiments, the piece of plush or velvet 29 may provide a depot for chemical and/or biological agents. The active agents may be enclosed in micro-capsules which break open on use. The threads of the piece of fabric 60 and/or the pile 61 may be made of synthetic material which is doped with silver, or a small proportion of the synthetic material can be made of silver in order to achieve an antibacterial effect.

The pieces of plush or velvet 29 may be secured in different ways and means to the cleaning fork 23. According to one embodiment, the respective piece of plush or velvet 29 may be severed from a length of plush or velvet material by means of a hot stamp or a laser beam. In both methods the heat fuses the cut threads together, which prevents fraying. The fabric of the velvet or plush may also be impregnated with a suitable medium, and then cold-stamped or cut out, e.g., with the aid of a water jet. Here, the impregnating prevents fraying.

The respective piece of velvet or plush 29 may be adhesively bonded or welded onto the inside of the legs 25 of the cleaning fork 23. By providing contact across the entire surface it is ensured that the respective piece of velvet or plush 29 exactly corresponds to the predetermined contour of the leg 25 of the cleaning fork 23.

FIG. 21 shows by contrast an embodiment in which the piece of velvet or plush 29 is only affixed in points or lines to the insides of the cleaning fork 23 or its legs 25. As is shown in particular in FIG. 21A, a piece of velvet or plush may be secured on the one hand to the free ends of the legs 25 and on the other hand to the base of the cross bar 55 connecting the legs 25. When the cleaning fork 23 is positioned on a tooth for cleaning, then the piece of velvet or plush 29 rests elastically against the contour of the tooth, as shown in FIG. 21B.

FIGS. 22 A-B shows a method suitable for manufacturing a cleaning fork 23. To start with, a piece of velvet or plush 29 is connected to a cleaning fork blank, which is still planar, for example by means of adhesive bonding or welding. The cleaning fork blank, which is still planar and has the piece of velvet or plush attached to it, is then placed on a die 74 having a cavity 75 which corresponds to the desired contour of the cleaning fork and into which the cleaning fork blank is then drawn by vacuum application through a vacuum duct 76. For this purpose the cleaning fork blank may be suitably heated as required.

FIG. 23 A-B shows an alternative way of securing the piece of velvet or plush 29 to the respective leg 25 of the cleaning fork 23 or the still unformed blank therefor. Positive engagement is achieved by sliding the piece of velvet or plush 29 onto a mandrel 77, so that the mandrel penetrates through the material of the piece of plush or velvet. By means of a tappet 78 the mandrel 77 is then shaped to form a mushroom- or rivet-like head which holds the piece of plush or velvet 29 in place on the mandrel and preferably clamps it securely.

Electrical toothbrush

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