CN1126485C - toothbrush - Google Patents

Abstract

A toothbrush having a handle and, attached at one end thereof, a head (1), the head (1) having a handle end (4), a free end (2), and a bristle-bearing face (7) with a plurality of tufts (6) extending therefrom, the tufts (6) each having a base and a free end and comprising one or more bristles, wherein the tufts (6) are arranged in groups which are separated from each other by a transverse gap (8), the distance between the bases of the tufts (6) within a group being less than 1.3 mm, the distance between the bases of the tufts (6) between groups being in the range from 1.3 mm to 5 mm and wherein the distance between the free ends of the tufts between groups is preferably at least 0.5 mm. Preferably, each group is in the form of a crescent shaped array and tufts (6) are generally perpendicular to the toothbrush head (1). The arrangement allows for independent movement of bristle tufts (6), particularly whilst using the Bass or Rolling techniques for toothbrushing, yet maintains a high density of tufts (6) on the toothbrush head (1).

Description

toothbrush

technical field

This invention relates to the arrangement of bristles on a toothbrush, and more particularly to a toothbrush head having tufts of bristles arranged in several different groups extending from one side of the head to the other. separated by the gaps. The positioning and orientation of the tufts of bristles is such that certain tufts of bristles operate substantially without interference from adjacent tufts of bristles, while still maintaining a high overall tuft density on the toothbrush head.

Background technique

Effective brushing requires a high degree of bristle contact with all tooth surfaces and penetration of the bristles into interdental spaces and other crevices. A conventional toothbrush with several tufts of bristles evenly spaced on the head achieves a high degree of bristle contact, but due to interference from adjacent tufts, i.e., the full set of bristles will appear as a solid body arranged in one piece. Penetration of the bristles into the interdental spaces is restricted.

Various bristle arrangements on toothbrush heads have been described which are intended to improve toothbrushing.

For example, International Patent Publication No. WO 91/19437 describes a toothbrush with three-dimensional bristle distribution to improve brushing between adjacent teeth. In two European patents, EP-A-449,653 and EP-A-449,655, respectively, toothbrushes are disclosed in which tufts of bristles are arranged at an angle relative to the toothbrush head and to each other to scrub the gingival area and adjacent teeth. between gaps. It is also mentioned that all the tufts do not structurally support each other, allowing a single tuft of bristles to penetrate into small holes and interdental spaces without being obstructed by surrounding tufts. International Patent Publication No. WO 96/01578 cites a multi-level tuft of bristles that stimulate the gums and give the mouth a unique sensation to remind the teeth that brushing has been effectively accomplished. Publication No. WO 96/15696 International Patent refers to such a toothbrush with many flexible strips of elastic material protruding from the toothbrush head to enhance its teeth cleaning effect.

Other approaches to improving toothbrushing performance include the shape or performance of the toothbrush head. For example, International Patent Publication No. WO 91/19438 discloses a toothbrush with some weaker parts on the head that allow it to be deformed to fit the specific size and shape of the arch of the user's teeth. In these weaker parts there are several rows of maneless. WO 96/02165 and some other documents mentioned here describe toothbrushes with flexible toothbrush heads which can adapt or be adapted to the user's teeth while brushing.

WO 94/09677 also describes another variant in which roughly two-oriented rectangular bristles are used on the same toothbrush head for improved scrubbing performance. The above references review earlier techniques describing the use of rectangular bristles to achieve different brushing characteristics with different motions of the toothbrush.

In addition to the above, the way of using a toothbrush has received more attention from dental professionals over the years. The best methods of brushing are described in the book "Primary Preventive Dentistry" by N.O. Harrison and A.G. Christen, 4th edition, Applenton & Lange, as the Bass and Rolling technique.

Despite all of the foregoing and much else in the literature concerning toothbrushes, there remains a need for improved toothbrush design.

Contents of the invention

It is an object of the present invention to provide a toothbrush which allows independent movement of tufts of bristles while maintaining a high overall tuft density.

Another object of the present invention is to provide a toothbrush which allows independent movement of the tufts of bristles and achieves optimum positioning of the bristles to the tooth surface during brushing.

It is a further object of the present invention to provide a toothbrush with a head that is comfortable to place in the mouth and has a bristle arrangement that contributes to improved cleaning.

According to the present invention, there is provided a toothbrush having a handle and a head connected to the handle. The head has a handle end, a free end and a bristle support surface extending therefrom a plurality of tufts, each tuft having a base and a free end and comprising one or more bristles, wherein the Tufts arranged in groups, the groups being separated from each other by a transverse interval, the distance between the bases of the tufts within a group is less than 1.3 mm, and the bases of the tufts between the groups The distance between them is 1.3mm-5mm; moreover, the distance between the free ends of the tufts between the groups is at least 0.5mm.

According to a second aspect of the present invention there is provided a toothbrush having a handle and a resiliently bendable head connected to the handle. The head has a handle end, a free end and a bristle support surface extending therefrom a plurality of tufts, each tuft having a base and a free end and comprising one or more bristles, wherein the Tufts arranged in groups, the groups being separated from each other by a transverse interval, the distance between the bases of the tufts within a group is less than 1.3 mm, and the bases of the tufts between the groups The distance between them is 1.3mm-5mm.

The tufts are arranged so that they move independently and maintain a high tuft density on the toothbrush head.

The toothbrush of the present invention may be a one-piece toothbrush of conventional manual design, or it may have a replaceable head as in an electric toothbrush, or the head may be fixed but have replaceable bristles Hair support insert. The toothbrush has a handle and a head connected to one end of the handle. The design of the handle is not critical to the invention, generally it is of a conventional elongated shape. Preferably it is ergonomically designed, constructed with features such as elastic inserts to improve the user's grip, thumb and forefinger placement for improved grip. In a preferred embodiment, the handle has a neck which is sufficiently arched so that the free working ends of the bristles lie in substantially the same plane as the handle (to be described hereinafter).

The toothbrush has a bristle support surface from which a plurality of tufts of bristles protrude, a free end with a pointed portion, and a handle end. The head also has opposite sides extending from its free end to the handle end. The handle end can be attached continuously to a long handle as in a one-piece toothbrush, or it can be attached to a separate handle. In any case, the long axis of the handle defines the longitudinal axis of the head, the free end and the handle end being at opposite ends of the longitudinal axis. The head also has a transverse axis which is orthogonal to the longitudinal axis and generally parallel to the bristle support surface. Unless otherwise noted, the transverse or longitudinal directions herein refer to directions parallel to the transverse axis and the longitudinal axis, respectively. Preferably, the head itself is also elongated, and its long axis is a longitudinal axis. The toothbrush head also includes a replaceable insert secured to a support frame as described in European Patent EP-A-704,179. In the latter case, "head" denotes the combination of the support frame and the insert for assembly for toothbrushing.

As used herein, "tuft" means a group of one or more bristles fastened at the same point on the toothbrush. The bristles used here can be made of any material known in the art. Suitable materials here include polyesters and nylons such as DuPont Tynex ^R 612 and Stylon ^R 612 available from STP Corporation. The cross-section of the bristles is preferably circular, but other cross-sectional shapes are possible including, but not limited to, rectangular, hexagonal, and three-chambered cross-sections. Additionally, the diameter and length of the bristles can vary within the usual size ranges known to those of ordinary skill in the art. In all preferred embodiments, the cross section of mane is circular, and diameter is 0.1 millimeter-0.25 millimeter, and length is 7-15 millimeter, is preferably 9-12 millimeter, and each group of mane comprises about 10- 50 bristles. In these embodiments, each tuft generally assumes a cylindrical shape with a diameter of about 1-2 mm. The cutting of the bristles and the rounding of the hair ends can be accomplished using any conventional method in the prior art. As used herein, the term "bristle" also includes other flexible strips of scrubbing material, such as those described in the above-mentioned WO 96/15696. In such a case, a tuft accordingly comprises only one bristle. The bristle tufts can be secured to the toothbrush using any of the methods known in the art, such as fusion, staples and injection molding. The best methods here are stapled and fused. Each tuft has a base and a free end, the free ends of the tufts forming the working surface for cleaning the teeth. As used herein, the "base" of the tufts is the portion of the tufts that abuts the face of the toothbrush head. It will be appreciated that a portion of the tufts extends under the base into the toothbrush head so as to secure the tufts within the toothbrush head. It is preferred for the toothbrush head to include pre-molded tuft holes so as to accommodate that portion of the tufts. The cross sections of the tuft holes can be of any shape, including square and rectangular, but are preferably circular. Their depth and diameter can be selected by those of ordinary skill in the art prior to making the tufts suitable for insertion into these holes. The bristles inserted into the same tuft hole should be fastened at the same point and be part of the same tuft.

The length L of the toothbrush heads is the length measured between the end of the free end and a line drawn perpendicular to the long axis of the head at their base closest to the handle The points of the handle just touch the tuft or row of tufts closest to the handle. Typically, L will be in the range of about 15 mm to 35 mm, preferably in the range of about 20 mm to 30 mm.

The tufts are arranged in multiple groups N, and there is a transverse interval between each group and the adjacent group or groups; there are N-1 intervals. N is at least 2, preferably 3-5, preferably 4. Each group includes one or more tufts, preferably about 5-20 tufts, most preferably about 7-12 tufts. The total number of tufts is suitably about 25-50 tufts, preferably about 30-40 tufts, most preferably about 35 tufts. "Lateral space" means an area on the bristle-supporting surface that is free of tufts and extends from one side of the toothbrush head to the other, such that each space has two ends, one at each end of the head. side. The transverse spacing may be linear or non-linear, depending on the arrangement of the tufts on the bristle support surface. A line drawn between the two ends of a space is preferably parallel to the transverse axis of the head, but can also be inclined relative to this transverse axis.

Within each group of tufts, the distance between the bases of adjacent tufts is less than 1.3 mm, preferably 0.6-1.2 mm, most preferably 0.8-1.1 mm. The distance between the bases of the tufts, here refers to the distance along the bristle support surface, measured from the edge of one tuft to the edge of the other along a straight line drawn between the centers of the tufts . The distance between the free ends of the tufts here refers to the distance parallel to the supporting surface of the bristles, from the free ends of the shorter tufts, along a straight line drawn between the centers of the tufts, from a Measured from edge of tuft to edge of another tuft. Unless specifically defined otherwise, the distance between tufts refers to the distance between adjacent tufts. "Adjacent tufts" means the closest tufts.

The distance between the bases of adjacent tufts in adjacent groups, that is, the distance measured across the spacing between groups, is from about 1.3 mm to about 5 mm, preferably from about 1.5 to 3.5 mm. mm, preferably about 1.7-3 mm. This distance varies somewhat between individual pairs of tufts, but not all pairs, with the tufts of each pair in different groups separated by at least 1.3 mm at their bases.

When the distance between the tufts in adjacent groups is large, the tufts of these groups can work independently of each other. That is, the tufts from one set do not substantially interfere with the tufts from the other set. This allows better penetration of the tufts in the groups, especially the edges, into interdental spaces and other crevices. However, the smaller distance between tufts within groups maintains a higher overall tuft density on the toothbrush head. In particular, this provides better bristle coverage on each tooth surface.

In order for the present invention to take full advantage of its strengths, it is necessary not only for the tufts spaced apart on the substrate, but also for their free ends to not interfere with each other affecting their individual movements when the toothbrush is in use. For a conventional rigid toothbrush head, the distance between the free ends of the tufts between groups is at least 0.5 mm, preferably at least 1 mm, most preferably at least 1.7 mm. This condition is automatically satisfied when the tufts are parallel to each other and the bristles in a tuft do not diverge towards their free ends.

The tufts can be generally perpendicular to the bristle-supporting surface of the toothbrush head, or can be inclined at a more pronounced angle. "Substantially perpendicular" means that the central axis of the tufts is oriented at an angle of no more than 10° to a perpendicular from the center of the bristle support surface. Preferably, at least 70%, more preferably at least 80%, of the tufts are substantially perpendicular to the bristle supporting surface of the toothbrush head. In particularly preferred embodiments, all of the tufts are substantially perpendicular to the bristle-supporting surface of the toothbrush head such that they are substantially parallel to each other. The tufts that are generally perpendicular to the bristle-supporting surface of the toothbrush head perform better because they are more or less perpendicular to the tooth surface when they are generally pressed against the tooth surface. They are also less prone to "tipping", ie, the tendency of the bristle tufts to flatten after repeated use. Slanted tufts have an unsightly appearance and impair toothbrushing. However, some tufts have an inclination angle greater than 10° to the bristle support surface. As an example, it may be desirable for some of the tufts in the outer longitudinal rows to be angled relative to the sides of the toothbrush head to provide gentler scrubbing of the gingival margins. Preferably, the tufts are not inclined relative to each other, especially on both sides of the spaces between the groups, as this would detract from the benefits of the invention.

As described hereinafter, on an elastically flexible toothbrush head, the requirement that the distance between the free ends of the tufts between the groups be at least 0.5 mm can be relaxed. This is because, during use, when pressure is applied to the toothbrush, the toothbrush adopts a more convex profile, with the free ends of the tufts separating from each other. However, it is preferred that the free ends of the tufts be at least 0.5 mm apart, more preferably at least 1 mm apart, most preferably at least 1.5 mm apart.

The overall density of tufts on the toothbrush head is a function of the size of the toothbrush head and the number of tuft groups and the size of the spacing between groups. In preferred embodiments, the average spacing (G) between adjacent tufts in adjacent groups is from about 0.15×L/(N-1) to about 0.3×L/(N-1) . That is, although they do not provide any appreciable improvement to the individual movements of groups of tufts when the spacing exceeds about 5 mm, they are wasteful of these spaces, and when the number of groups of tufts is small, the spacing between groups When also less, all intervals can be larger. The average spacing between adjacent tufts in adjacent groups is determined by taking the average of the spacing between all pairs of adjacent tufts, wherein each side of each pair is located at the spacing between groups each side of the

The overall mane tuft density and the degree of freedom with which the individual tufts operate independently of each other can be affected by the shape of the tuft groups and the arrangement of the tufts within the groups. Although rectangular bristle groups can be used, and the bristle tufts are arranged in conventional in-line arrangements, better results can be achieved if at least part of the tufts within a group are offset from each other along the transverse axis. "At least partially offset" means that, for any particular tuft, at least 50% of the width of the tuft, measured along the longitudinal axis, has a length, measured along a line parallel to the transverse axis, of No other tufts within a distance of 1.3 mm, preferably 1.5 mm. In particular, for at least 70%, preferably 100%, of the width of the tuft, the distance to an adjacent tuft is greater than 1.3 mm, preferably greater than 1.5 mm. In several preferred embodiments, at least 50%, preferably 70%, of the total number of tufts are at least partially offset in two directions along the transverse axis. Like this, when using Bass technology to brush teeth, toothbrush is placed along tooth and moves up and down, and all tufts can move past each other more easily, make the resistance that moves up and down compared with toothbrush longitudinally. One way to practice such an offset arrangement is to arrange the groups of tufts in a parallelogram, wherein the spaces between the groups are generally straight, but inclined relative to the long and transverse axes of the toothbrush head. A desirable solution is to arrange one or more groups of tufts in a crescent or herringbone pattern. "Crescent" and "herringbone" mean a row that is symmetrical about the major axis, but at least two longitudinal rows of tufts are within the row, the rows being set at distances from their adjacent tufts. Clusters are such a distance of at least 20% of the average width that the general appearance of the entire group is that of an arc or a "V" with the apex at or near the central longitudinal axis. The overall tuft density is also maintained when the groups in which the spaces are substantially parallel to each other form a set of interconnected shapes. In a preferred embodiment, this is achieved by arranging at least N-1 groups of tufts in a crescent arrangement. The end set, preferably the set closest to the end of the handle need not be so shaped. For example, it may be oval, diamond-shaped or round. A further advantage of crescent-shaped or herringbone-shaped groups of tufts is that they use space more efficiently on toothbrushes with a pointed or rounded free end. For this reason, it is especially advisable to have the apex of the crescent or herringbone point towards the free end of the toothbrush head.

The working surface formed by the free ends of the tufts may be of any suitable shape, such as flat, concave or corrugated. Preferably it is cut to a wave profile (as described in WO 91/19437). Preferably, some of the outer rows of tufts will have a raised profile (as described in WO 96/07343).

As described in WO 96/02165, the toothbrush head of the present invention is preferably elastically bendable. Here, "elastically bendable" means that when a force of 3 Newtons is applied to the free end of the head, the handle end is immediately fixed and held behind the last course of bristles, and the free end will deviate from an angle (deflection angle ), the angle is at least 2°, preferably at least 5°, preferably at least 10°; in addition, when the 3 Newton force is removed, the free end of the head returns to its original position without external force applied. The deflection angle is less than 40°, preferably less than 30°, most preferably less than 20°. This has been found to give the user an acceptable degree of flex without exposing the hinge parts and elastomeric segment bond to undue stress. It is also desirable that the toothbrush head has a concave bristle support surface in its unstressed state. A resiliently bendable toothbrush head better conforms to teeth of different contours and facilitates penetration of individual tufts into interdental spaces and other crevices. It is also preferred that the bristle-supporting surface of the toothbrush head is concave along the longitudinal axis in its unstressed state, the radius of curvature being variable along the length of the head. The bending radius is preferably 10-500 mm, more preferably 15-250 mm, especially 25-150 mm.

A further advantage of having larger intervals between groups is that these intervals can be accommodated in transverse grooves on the bristle support surface to allow bending of the head, as described in WO 96/02165.

In preferred embodiments herein, the toothbrush head includes a transverse slot in each space between groups of tufts to allow the head to bend along the long axis. This allows the toothbrush head to flex so that it acquires a concave profile along the long axis when pressed against the teeth. This is particularly suitable for brushing the tongue or inner surfaces of the teeth. Preferably there are matching grooves on the reverse side of the toothbrush, which grooves are preferably filled with an elastomer as described in WO96/02165. A kind of desirable way of constructing a flexible toothbrush head is determined according to our co-pending patent application GB 9601013, will briefly explain below, so that better describe according to the best practice of a toothbrush of the present invention Way.

The toothbrush has a pair of opposing surfaces, one of which is a bristle support surface from which bristles are attached and extend. The toothbrush head comprises two or more flexibly connected segments with slots between adjacent segments to allow the head to bend under the action of the toothbrush and eg adapt itself to the different contours of each user's teeth. The head also includes elastomer contained within the groove on at least one surface. The elastic body can improve the elasticity of the head by acting like a spring, so that when a force applied to the head and causing the head to bend is removed, the head returns to its original position within a short period of time. shape. The grooves define hinges between the segments. The hinges are preferably located between the surfaces, preferably at a distance from each surface of at least about 10% of the depth of the head, rather than being coextensive with either surface. Elastomers can also be used to limit the degree of bending, so that when a large force is applied, the deflection of the head is limited, greatly reducing the occurrence of excessive strain on the hinges, and thus improving the durability of the product sex.

Toothbrush heads and handles are generally made of a relatively incompressible material, preferably with a modulus of elasticity of at least about 500 MPa, more preferably at least about 1,000 MPa, which is conventional in the manufacture of toothbrushes, especially plastic toothbrushes. practice. Suitable plastics include, for example, amides and polypropylene. Preferably polypropylene. Suitable polypropylenes include the material "Polypropylene PM 1600" (brand name Shell) from Elf Atochem, which has a modulus of elasticity (ISO 178) of 1,500 MPa and Apryl 3400 MA1. Preferably, a foaming additive is mixed in the polypropylene, such as Hydrocerol HP20DP of Boehringer-Mannheim, in a proportion of about 1% to 3% by weight of the polypropylene, preferably about 1.5% to about 2.5% by weight Compare. This foaming additive aids in the flow of the polypropylene during the molding process and, in particular, helps to ensure uniform formation of hinge parts. The handle itself is generally rigid and of a shape as is usual in toothbrush manufacture. Optionally: the handle may include a neck, which, as is known from the prior art, is more flexible than the rest of the handle, provided that it is stiff enough in use that when applied to the head, Especially when brushing the teeth, the head is bent to the extent described below.

The toothbrush head includes grooves on the bristle-supporting surface and the opposite face, which grooves are the spaces between the segments. These grooves allow the toothbrush head to flex or bend. The orientation of these slots may be perpendicular or parallel to the longitudinal axis of the handle, and may be rectilinear or non-rectilinear, such as curved or herringbone. The non-linear grooves help to counteract the compressive stresses in the resilient material containing the grooves when the toothbrush head is bent. "Transverse grooves" can also include grooves whose main axis is defined by a straight line connecting the start and end points of the grooves and which deviates by an oblique angle of up to 45° with respect to the transverse axis of the toothbrush head. Similarly, "longitudinal grooves" can also include grooves whose main axis is offset by an angle of up to 45° with respect to the longitudinal axis of the toothbrush head.

In preferred embodiments, the toothbrush head includes one or more transverse grooves on each opposing face to allow bending of the toothbrush head along the longitudinal axis. This allows the head to bend so that it acquires a convex profile along the longitudinal axis when it is pressed against the teeth. This is particularly suitable for brushing the or inner surfaces of the teeth towards the tongue.

The toothbrush head can also include one or more longitudinal grooves. The longitudinal grooves allow eg the outer longitudinal rows of bristles to bend away from the inner row.

In particularly preferred embodiments, the head of the toothbrush includes transverse grooves on each opposite face which allow the head to bend along the longitudinal axis, and at least one longitudinal groove which cooperates with the longitudinal grooves. The transverse slots are connected to allow the elastomer to flow from one slot to the other during molding of the handle. In a one-piece toothbrush with a co-molded handle, this longitudinal slot can extend along the handle so that the same elastomer injection point in the mold normally used to deliver the elastomer to form the grip of the handle can be used. to inject elastomer into the grooves of the head. The longitudinal groove preferably extends along the back of the head, that is to say on the opposite side to the bristle-supporting surface, so that it does not interfere with the tufting.

The grooves on one of the two opposing faces can be directly opposite the grooves on the other face, or partially or totally offset.

The slots separating the segments of the head also define hinges which are thinned regions of the head at the base of the slots.

The width and depth of the grooves are variable, as can the distance between the grooves. In this way, the curvature of the head can be varied along its length and/or across its width. Preferably only the transverse grooves are changed as such. Variations in the groove depth control the position and thickness of the hinges connecting the segments. For a toothbrush head having a thickness of about 4-6 mm, typically about 5 mm, suitable groove depths are about 1.4 mm-3 mm, preferably about 1.5-2.8 mm. A suitable hinge has a thickness of about 0.4-2.0 mm, preferably about 0.5-1.5 mm. When transverse slots are used, then, as desired, those hinges which are or will be closer to the handle are less flexible than those which are or will be farther from the handle. In this way, a more uniform curvature of the head can be achieved. The deflection can be changed by changing the thickness of the hinge. In a preferred embodiment, the hinge member closest to the handle is about 3 times, preferably about 2 times thicker than the hinge member furthest from the handle. A typical set of toothbrushes having three transverse grooves has a hinge thickness of about 1.1 mm, 0.6 mm and 0.6 mm, respectively, measured from the end of the handle. If the same hinges are used along the toothbrush head, the tendency of the head to bend occurs primarily at the hinge close to the handle. The grooves on the bristle-supporting surface have a different depth than the grooves on the opposite face. Preferably, the depth of the grooves on the bristle-supporting surface is less than the depth of the grooves on the opposite face. In some embodiments there is elastomer in grooves on both surfaces so that more of the elastomer is in compression rather than tension. The elastomer used to connect the segments is more clearly in compression than tension.

Increasing the width of the slots increases the spacing between the segments and therefore increases the length of the hinges, thus increasing their deflection. However, it is preferable to insert the bristles into the segments rather than into the elastomer, since the increased slot length reduces the space available for bristles within a given head size. Suitable slot widths are from about 0.3 mm to 3.0 mm, preferably from about 1.2 mm to 2.0 mm. The grooves preferably taper slightly inward toward the bottom of the groove and converge at an included angle of from about 3° to about 10° for ease of molding. As the toothbrush is flexed, the slot width changes more rapidly at the top of the slot than at the bottom of the slot, and this relative change is a function of slot width and slot depth. Since this variation in slot width results in compression or stretching of the elastomer contained within the slot, it can be seen that, for a given elastomer, the slot geometry can be used to control the deflection of the head.

The hinges can be the full length of the slots or, preferably, there are one or more spaced sides of the hinges, the slots in these areas being the full length of the head. This has the advantage of allowing a single injection point for the elastomer when molding the toothbrush head. This spacing allows the elastomer to flow from one side to the other during the molding process. In a preferred embodiment, the hinges are discontinuous and two or more hinges, preferably two hinges connect each segment to its adjacent segment or handle. In this embodiment, there are spaces between the hinges to each side. Hinge width is usually not critical in linear slots, but wide hinges will bend if used in a non-linear slot if space is still present. Suitable hinge widths are from about 0.5 mm to about 4.0 mm, preferably from about 1.0 mm to about 3.0 mm.

Preferably, each hinge is located between the two faces at a distance of at least about 10%, preferably at least about 20%, and more preferably about 30% of the depth of the toothbrush head from each face. The distance of the hinge from a face is measured along the perpendicular line from the top of the face to the nearest interface to the center of the hinge. Locating the hinges away from the faces of the toothbrush means that the toothbrush heads are less stretched or compressed when they are bent, thus improving their useful life. In a particularly preferred embodiment, the toothbrush head has transverse grooves arranged in pairs such that any groove in the pair of grooves is located on a side and opposite to another groove in the pair of grooves, and the gap between them is One or more hinges connect the segments such that each hinge is located between the two faces and is at least about 10% of the depth of the toothbrush head's distance from each face, preferably at least about 20%, more preferably is about 30%.

The grooves on at least one face of the toothbrush contain elastomer. To achieve this, it is only necessary to carry out a separate injection molding process after the molding of the segments is completed. Preferably, all elastomers are injected from a single injection point. However, there are several other elastomer injection points on the mold to provide the elastomer required for the discrete elastomer units in the head, for example, one injection point is used to supply the bristle support surface Elastomer, another injection point is used to feed the elastomer on the opposite face. When the head is bent along a direction perpendicular to the two opposite surfaces, the elastic body is stretched or compressed. The elastomer has the effect of limiting the deflection of the head thereby reducing the tension or compression of the hinges and limiting the stress at the junction between the elastomer and the segments of the head. Preferably, the grooves on the face opposite the bristle support surface contain elastomer which allows the elastomer to be compressed in either direction. The elastomer on the opposite face is of course stretched, but the tensile stress of the elastomer to the junction of the segments is limited and shared with the hinge material.

Preferably, all the grooves are filled with elastomer in a separate molding process after the molding of the head section is completed. The advantage of filling all slots is that, for example, contamination of the slots with toothpaste deposits is avoided. However, the slots may be partially filled provided that sufficient elastomer is used to effectively moderate the deflection of the head.

Suitable elastomers include thermoplastic elastomers having a Shore hardness of 30-80 and a modulus of elasticity of less than about 500 MPa, preferably less than about 300 MPa, such as Santoprene and Thermoflex. A typical elastomer is 'PTS Thermoflex 75' (sold by Plastic Technologie Service, Germany), which has a modulus of elasticity (ISO 178) of 100 MPa and a hardness (ISO 868) of 80 Shore A. Also suitable for use herein are the elastomers PL12291, PL12292 and PL12293 (sold by Multibase, Saint Laurent Du Pont, France). In general, the elastomer is selected so that its material is of the same polymer chemical class as the head segment, which promotes bonding between the elastomer and the head segments. For example, when the head segments are made of polypropylene, the elastomer is preferably also made of polypropylene. The elastomers are optionally mixed with a suitable plasticizer or blowing agent to render them readily compressible. The elastomeric material can be the same color as the head segments, or a different color to achieve a different sheet or otherwise patterned appearance.

Description of drawings

The present invention will be illustrated below with reference to the accompanying drawings, in which:

Fig. 1 is the top view of the first embodiment of the present invention, has represented the distribution profile of all hair tufts on the toothbrush head;

Fig. 2A is a top view of another embodiment, wherein there are bars filled with elastomeric transverse grooves located in the spaces between groups of tufts;

Figure 2B is a side view of the embodiment shown in Figure 2A, in order to reveal the hinges, the elastic body in the groove closest to the handle is not shown among the figures;

Figure 3 is a perspective view of a toothbrush head according to the present invention; and

Figure 4 is a diagram showing the offset sizes of the tufts along the transverse axis.

Detailed ways

Referring now to Figure 1, a toothbrush head 1 has a rounded free end 2 with a top end 3, a handle end 4 and side surfaces 5 extending from the free end to the handle end. A plurality of tufts 6 extend from the bristle support surface. The tufts are arranged in four groups separated by intervals 8 from each other. The three groups closest to the free end present a crescent-shaped arrangement. The set closest to the handle is roughly oval or diamond-shaped. The tufts are more closely spaced within each group, the distance T between the bases of adjacent tufts varying from 0.6 mm to 1 mm. Adjacent tufts in adjacent columns are offset from each other along the transverse axis so that their free ends can pass each other more easily when brushing with the Bass technique. The distance G between the bases of adjacent tufts in adjacent rows varies from 1.9 mm to 3 mm. The length L of the toothbrush head is 29.6 mm.

Referring to Figures 2A and 2B again, the toothbrush head 1 has grooves 9 filled with elastomer so that the head can be elastically bent. When a force of 3 Newtons is applied to the top of the head and the handle is fixed at its position immediately behind the bristles of the last row, the free end deviates from an angle of 15°; when the 3 Newtons After the force is removed, the free end of the head returns to its original position when no external force was applied. In the unstressed state the bristle-supporting surface of the head is concave along the longitudinal axis with a radius of curvature of 75 mm. Grooves 9 divide the toothbrush head into segments 10 . The segments are connected by only a few pairs of thin hinges 11 . For the sake of clarity, only the hinges in the groove closest to the handle are shown, others are hidden by the elastic body. The tufts are separated from each other by spaces 8 into four groups. Each of the three groups closest to the free end are arranged in a crescent shape. The set closest to the handle is roughly oval or diamond-shaped. All tufts are substantially perpendicular to the bristle support surface, that is to say, the direction of the central axis of each tuft as shown in the "Z-Z" line in Fig. 2B and a vertical line from the center of the bristle support surface There is an included angle not greater than 10° between them. The result is that the distance (F) between the free ends of the tufts is substantially equal to the distance between the bases. Because the bristle-supporting surface of the head is concave in the unstressed state, the tufts at each end of the head are not perpendicular although the tufts are parallel to each other and to the central axis (Z-Z). on the supporting surface of the bristles at their point of attachment. According to a further aspect of the invention, it is preferred to mold a curved toothbrush head with holes all axially parallel to the axis Z-Z. Its overall advantage is that during the molding process, the pins used to form the holes are easier to remove from the molded toothbrush body without deforming the tuft holes.

Figure 3 shows an embodiment of a toothbrush head having a transverse axis (X-X) and a longitudinal axis (Y-Y) in which thirty-five tufts 6 are arranged in four groups with transverse intervals between these groups 8. Each group appears as a crescent. The tufts are all perpendicular to the bristle-supporting surface of the head and are of substantially equal length so that their free ends 12 form a flat working surface. Within each group, the tufts are spaced closer together, the distance between the bases 13 of adjacent tufts varying from 0.7 mm to 1 mm. The tufts are distributed symmetrically with respect to the long Y-Y axis of the head. Regardless of which direction is chosen along the transverse axis, for thirty tufts, at least 60% of the width of each tuft is free of tufts within 10 mm measured parallel to the transverse axis. For reasons of symmetry, the central two of the columns contain four tufts and lie on the same transverse axis. The tufts in the row closest to the free end 2 of the head are slightly offset from each other. The head comprises elastomeric bodies filling the transverse grooves 9 located in the spaces between the groups.

Figure 4 shows a portion of a top view of a head, only three tufts 14, 15 and 16 being shown for clarity. The transverse axis is perpendicular to the longitudinal axis (Y-Y). The tufts 14 have a width "W", measured along the longitudinal axis. At 70% of this width W, the tufts 16 adjacent to the tufts 14 are at least 2 mm apart in the full width W when viewed in the X direction and along the transverse axis. However, for 30% of the width, the lateral extension of the tufts 14 overlaps the tufts 15 which are less than 1.3 mm apart in the X direction. The analysis of tufts 15 can also be used for the analysis of tufts 16 . As for tufts 16, since it is located in an outer row, no tufts exist in the X direction.

Claims (7)

1. A toothbrush having a handle and a head connected to the handle, the head has a handle end, a free end and a bristle support surface extending from it with multiple tufts, a long The axis extends from the free end to the handle end, and each tuft has a base and a free end and includes one or more bristles, wherein the tufts are arranged in N groups, and the N groups of tufts are separated by a transverse interval. Spaced apart, the distance between the bases of tufts within a group is less than 1.3 mm, and the distance between the bases of tufts between groups is 1.3 mm to 5 mm; in addition, between groups The distance between the free ends of the tufts is at least 0.5 mm, wherein N is 2-5, and the average distance between the tufts in adjacent groups is from about 0.15×L/(N-1) to a range of about 0.3 x L/(N-1), L being the length measured between the top of the free end of the head and a line perpendicular to the long axis of the head at the point nearest the handle The location on the base of the tuft or row of tufts closest to the handle is just in contact with the tuft or row of tufts. 2. A toothbrush having a handle and a resiliently bendable head connected to the handle, the head having a handle end, a free end and a bristle support extending from it with a plurality of tufts surface, a longitudinal axis extending from the free end to the handle end, each tuft having a base and a free end and comprising one or more bristles, wherein the tufts are arranged in N groups, and the groups are separated from each other by a transverse Spaced apart, the distance between the bases of the tufts within each group is less than 1.3 mm, and the distance between the bases of the tufts between groups is 1.3 mm to 5 mm, where N is 2-5, the average distance between tufts in adjacent groups is in the range from about 0.15×L/(N-1) to about 0.3×L/(N-1), L being in the head The length measured between the top of the free end and a line perpendicular to the long axis of the head which just touches the handle at the point closest to the handle on the base of the tuft or row of tufts closest to the handle The tuft or row of tufts. 3. A toothbrush according to claim 1 or 2, wherein one or more groups of tufts are arranged in a crescent-shaped array. 4. The toothbrush according to claim 3, wherein at least N-1 groups of tufts are arranged in a crescent or herringbone array. 5. The toothbrush according to claim 4, wherein the apex of the crescent or chevron is directed towards the free end of the toothbrush head. 6. The toothbrush of claims 1 or 2, further comprising one or more transverse grooves located in the spaces between adjacent groups. 7. The toothbrush of claim 1 or 2, wherein more than 80% of the tufts are oriented substantially perpendicular to the bristle support surface.

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