EP2448726A1

EP2448726A1 - Bottom cutters for dry shavers

Info

Publication number: EP2448726A1
Application number: EP10750172A
Authority: EP
Inventors: Andreas Wurl; Andre Nauber; Andreas Moehring
Original assignee: Braun GmbH
Current assignee: Braun GmbH
Priority date: 2009-07-03
Filing date: 2010-07-01
Publication date: 2012-05-09
Anticipated expiration: 2030-07-01
Also published as: DE102009031628A1; WO2011001404A1; EP2448726B1

Abstract

The invention relates to a bottom cutter assembly for a dry shaver, a dry shaving apparatus and a shaving method, wherein the bottom cutter assembly (10) has a top cutter (12) with holes and a bottom cutter assembly that can be driven by a motor to oscillate to each other. The bottom cutter assembly (10) has at least one first bottom cutter (14) and a second bottom cutter (22; 32; 34; 36; 38; 40; 42) that precedes the first bottom cutter (14) in the direction of the oscillating movement, which second cutter is designed to exert a tensile force on a hair (18) extending into the hole (20) of the top cutter (12) in order to pinch the hair between the second bottom cutter (22; 32; 34; 36; 38; 40; 42) and the top cutter (12).

Description

BOTTOM CUTTERS FOR DRY SHAVERS

The present invention relates to a dry shaving apparatus and a related bottom cutter assembly as well as a method for shaving hair on human skin.

Electrical shaving apparatuses, in particular "dry shaving apparatuses" for cutting or shaving hair, are well known as such in the prior art. The plurality of known shaving devices are designed in such a way that they cut hair close to the surface of the skin and preferably below the surface without pinching or injuring the skin while doing so.

There are also systems that are designed to first grasp a hair sprouting from the skin and then to pull it out somewhat further from the skin and to draw it into the cutting system in order to then cut through the hair. Pulling on the hair draws the roots of the hair closer to the surface of the skin, as a result of which an overall longer section of the hair extends from the skin in comparison to when the hair is not pulled, which section of hair can then be cut off by the shearing or cutting system of the shaving apparatus.

After the cutting action is completed, the root of the hair returns to its initial position so that the shortened end of the hair lies completely under the surface of the skin. The result is a closer shave compared to conventional systems, which do not actively pull out the hair.

Different mechanisms and systems to pull human hair somewhat further out of the skin before cutting through it are known in the prior art.

One such system is described in US 7,065,877 B2, wherein a hair extending through a hole of the top cutter is pinched by means of two mounted bottom cutters that can slide against each other, wherein the interacting bottom cutters are designed to pull on the grasped hair before it is cut off. At the same time, the first and second bottom cutters provided for this purpose must work together so that their cutting blades move in succession to clamp onto or pinch hair.

At the same time, it in particular requires a first of two bottom cutters to be activated by a drive while the other bottom cutter, which trails behind the first, is coupled to the first bottom cutter by means of a spring element. Owing to a sideways movement of the first bottom cutter, adjacent cutting blades of the two bottom cutters move up against one another because the cutting blades of the bottom cutter trail behind the first bottom cutter as a result of their inertia and the elastic coupling provided. As a result of the back and forth movement of the first bottom cutter, each cutting blade of this bottom cutter alternately moves up against the adjacent right and left cutting blades of the bottom cutter trailing behind, according to the direction of the back and forth movement. At the same time, a tweezer action is employed on the hair threaded into the holes of the top cutter.

Because of the alternating action of the two bottom cutters in the direction of the oscillating movement, the coupling of two bottom cutters described in US 7,065,877 B2 is only suitable for bottom cutters that have so-called 90° cutting edges. More modern bottom cutter configurations that have acute-angled, sharp cutting edges with cutting-edge angles of significantly less than 90° cannot be coupled to one another in the known manner to bring about a pulling action on trapped hairs because an alternating action of adjacent bottom cutters would prematurely dull the sharpened cutting edges and wear out the blades early. In addition, with such a shearing system hair can be pinched between the two bottom cutters only within the range of the reversal points of the oscillating movement - i.e. only a fraction of the existing hair - so that the closeness of the shave cannot be improved very much and therefore different lengths of residual hair will remain after each shaving stroke. There is also the danger of pulling hair [completely] out of the skin.

The problem of the present invention is therefore to provide a bottom cutter assembly that facilitates both the pulling and the cutting through of hair sprouting from human skin and which guarantees a very gentle and at the same time a close shave. In particular, as a result of the pulling and cutting system according to the invention, the ends of the cut hair remain beneath the surface of the skin after shaving.

At the same time, the pulling and cutting concept according to the invention should also be applicable to bottom cutters that have a cutting angle of less than 90°, hence cutting edges sharpened at an acute angle.

The problem underlying the invention is solved by means of a bottom cutter assembly according to Claim 1 and a dry shaving apparatus according to Claim 13 as well as a shaving method according to Claim 14. Advantageous embodiments of the invention are indicated in the dependent claims.

The bottom cutter assembly according to the invention is provided for a dry shaving apparatus that has at least one top cutter provided with holes and a motor for activating the top cutter and bottom cutter assembly to oscillate against each other, preferably in translatory oscillation. The top cutter, which typically can be designed as a shearing foil or as a comb-like or shear bar-like shearing element, depending on the type of hair trimmer, and the bottom cutter or the bottom cutter assembly can move back and forth by means of the electromotive drive, wherein hair trapped in the holes of the top cutter are cut or sheared off as a result of a shearing or oscillating movement between the foil bars extending to the holes of the top cutter and cutting edges of the blades of the bottom cutter.

The bottom cutter assembly according to the invention has at least one first bottom cutter and a second bottom cutter that precedes the first bottom cutter in the direction of the oscillating movement and/or in the cutting or shearing direction. This second preceding bottom cutter is also designed to exert a tensile force on a hair protruding into the hole of the top cutter. This requires the hair to be pinched between the second bottom cutter and the top cutter and/or a tensile force or a synchronous movement be exerted on the hair trapped in the area between the second bottom cutter and the top cutter.

At the same time, this in particular requires the trapped hair to be pinched between the bottom side of the top cutter facing away from the skin and a side facing the skin of the second mounted bottom cutter that oscillates in a translatory fashion. Thus, a synchronous movement can be exercised on the pinched hair by means of the oscillating movement of the top cutter and the second bottom cutter relative to each other. Because of this tensile force or synchronous movement, the pinched hair and its root can be pulled out somewhat from the corresponding part of the skin before it can be completely cut through by the first bottom cutter trailing behind.

At the same time, this in particular requires that the hair extending essentially diagonally or perpendicularly to the cutting plane between the bottom cutter assembly and the top cutter is bent or buckled by means of the second bottom cutter so that, despite a relative movement between the top cutter and the bottom cutter assembly that oscillates essentially parallel to the surface of the skin, a tensile force can be applied to the hair, which force operates in a direction perpendicular to the surface of the skin.

A first advantageous embodiment of the invention provides that the first bottom cutter has a sharpened cutting edge for cutting through a hair. In this respect, two different types of cutters or blades are provided for the bottom cutter assembly, wherein the blades of the first bottom cutter are sharpened and designed to cut clean through the hair, while the blades of the second bottom cutter are designed as so-called scraping blades having a rather blunt edge or outer contour.

A tensile force that acts on the hair can be provided immediately after a hair caught in the shearing foil is grasped by means of the second bottom cutter. As soon as the trapped hair is pinched between a foil bar and the preceding second bottom cutter, the hair can be bent by an additional movement of the bottom cutters and pinched between the shearing foil and the second bottom cutter and/or its scraping blades. The additional movement of a scraping blade against the top cutter pulls the clasped and pinched hair further into the cutting system, wherein the sharp blade of the first bottom cutter that trails behind the scraping blade cuts through the hair.

The pulling action can be executed in two successive phases. In a first phase, the so-called "bending phase," the second bottom cutter grasps a hair caught by the top cutter and pushes it up to the hole of the foil bar bordering the top cutter and presses it against the foil bar. The forces exerted between the second bottom cutter and the foil bar as a consequence of the relative oscillating movement of the two components causes a gap to be formed between the top cutter and the second bottom cutter, so that the trapped hair can be bent in the direction of oscillation and then pinched between the second bottom cutter and the top cutter.

The gap required to pinch the hair can be created either by a local distortion of the top cutters or by moving the second bottom cutter further below the top cutter. At the same time, advantageous are those configurations in particular in which the second bottom cutter can be moved further below the top cutter so that the first bottom cutter that trails behind remains together with the edges of the foil bars in the required cutting plane.

In principle, two different mechanisms are possible for exerting a tensile force and for bending the hair. One can be that the second bottom cutter slides along the hair, bends it and, because of an inherent slide or static friction coefficient, a tensile force is exerted on the hair between the outer contour of the second bottom cutter facing the bent hair and a synchronous movement by the second bottom cutter is transmitted to the hair.

It is also possible to hook the second bottom cutter into the already bent or to be bent hair, binding it in a quasi form-fit manner. According to one especially advantageous embodiment of the invention, it is in particular required that the top cutter have a rounded edge contour contiguous to its holes, and/or that the second bottom cutter has a rounded outer contour facing the top cutter at its end section facing away from the first bottom cutter and preceding it in the direction of oscillating movement. Due to the fact that at least one edge moving up against a hair, either the edge of a foil bar extending to a hole of the top cutter and/or the subjacent preceding edge of the second bottom cutter in the cutting system, is rounded, the requisite effect according to the invention of bending instead of shearing or cutting off the hair can be achieved.

At the same time, it is also possible in particular that two edges of the top cutter and the second bottom cutter, both sides of which move up against the trapped hair on opposites sides, are rounded off. This effectively prevents the preceding second bottom cutter, preferably designed as a so-called scraper, from already exercising a cutting action on the hair. In addition, the rounded edges counteract cutting into the hair by means of the second bottom cutter, which is provided mainly for drawing the hair out.

According to another especially advantageous aspect of the invention, the first bottom cutter and the second bottom cutter are essentially fixed to each other and coupled in terms of the direction of the oscillating movement. Consequently, unlike what is typical in the prior art, a relative movement between the two bottom cutters in the direction of the oscillating movement that takes place in relation to the top cutter is not required.

This can effectively prevent, for example, the blunt second bottom cutter from moving up against the sharpened cutting edge of a first bottom cutter provided for cutting through the hair.

According to the invention, it is in particular required that a slight distance (viewed in the direction of oscillation) exist between the first bottom cutter and the second bottom cutter and/or between the individual blades attached to each bottom cutter. This distance between the first and second bottom cutter as well as the width of the second bottom cutter extending in the direction of oscillation defines the length a trapped hair can be pulled out from the skin by means of the previously described pinching action.

The gap to be formed between the first and the second bottom cutter can be, for example, 50 μm or more. The distance between the first and the second bottom cutter should be smaller than the anticipated hair diameter, so as to prevent hair from slipping through. The maximum length the hair is to be drawn out from the skin in order to achieve an optimal shaving result is between 200 and 400 μm; preferably it is

approximately 300 μm.

According to one development of the invention, the first bottom cutter and the second bottom cutter are mechanically decoupled from each other perpendicularly or diagonally to the direction of the oscillating movement.

At the same time, it is in particular contemplated that the first bottom cutter and the second bottom cutter be pre-stressed independently of each other in relation to the top cutter perpendicularly or diagonally to the direction of the oscillating movement. Such pre-stressing can be accomplished by means of spring elements that in each instance are specially provided for the first and for the second bottom cutters and which are specially designed for them. Mechanically decoupling the first and second bottom cutters at least in the direction of movement perpendicularly to the direction of oscillation contemplated for the shearing function allows the first and the second bottom cutters in each instance to be pressed against the underside of a top cutter facing away from an area of skin with different force and/or different pre-stressing.

Because the second bottom cutter is provided in particular to form a gap that pinches a hair between it and the top cutter, its spring element has to be designed so that the second bottom cutter can be lowered out of the cutting plane relatively easily. Such a lowering movement in order to pinch a hair has no effects on the other first bottom cutter provided for cutting through the hair. Its cutting edge remains in the cutting plane to continue to cut through the hair drawn into the cutting system by means of the second bottom cutter in the cutting plane.

Therefore, in each instance it is contemplated to pre-stress the first bottom cutter and the second bottom cutter against the top cutter by means of at least one spring element, wherein the pretensioning force exerted on the second bottom cutter in the direction of the top cutter is less than the force exerted on the first bottom cutter in the direction of the top cutter. At the same time, it is specifically contemplated to choose the elastic forces exerted on the two bottom cutters perpendicularly to the direction of their oscillating movements so that even under extreme stress, for example when there are several cuts to be completed simultaneously, a user's hair can still be cut through by the first bottom cutter without the latter leaving the cutting plane.

The pretensioning force to be provided for the second bottom cutter can be adjusted taking into account how far the second bottom cutter descends and the edge contour of the second bottom cutter that is achieved with a trapped hair in the engaged position and/or the edge design of the top cutter. For example, if in the case of a predetermined edge contour of the second bottom cutter, the pretensioning force is too low, the second bottom cutter will then be unable, under certain circumstances, to provide sufficient force to bend a trapped hair. In such a case, the second bottom cutter and/or its blade solely impacts a trapped hair and, as a result, descends far below the cutting plane.

A certain minimum pressure and/or a minimum pretensioning force for the second bottom cutter is therefore contemplated. This force should preferably be measured so that the oscillating movement between the top cutter and the bottom cutter assembly produces a synchronous movement on a hair pinched and bent between the second bottom cutter and the top cutter. If, for example, the pretensioning force exerted on the second bottom cutter is increased further, the second bottom cutter having a preceding edge at least partially beneath a break in the cuticle of a hair can hook into the bent or to be bent hair, respectively, and as a result of the oscillating movement can carry it along a certain distance. However, if the pretensioning force contemplated for the second bottom cutter reaches a [certain] value related to the sharpness of the second bottom cutter, the hair can also be cut through by the second bottom cutter.

Regardless of the pretensioning force exerted on the two bottom cutters in the direction of the top cutter, the second bottom cutter, and/or individual blades arranged on the second bottom cutter can have a surface quality that increases static or dynamic friction on an end section facing the top cutter. This action can advantageously increase a "carry along" effect and/or a pinching effect for the hair.

Increasing the friction between the second bottom cutter and the hair relative to the friction between the top cutter and the hair can increase the pulling ability of the bottom cutter assembly. Simple actions for this purpose include roughening a sliding surface of the second bottom cutter facing the top cutter and/or smoothing or polishing the surface of the top cutter facing the bottom cutter.

In addition, it can be contemplated that the second bottom cutter and/or individual blades arranged on the second bottom cutter have on at least one side facing the hair to be pinched or to be grasped a static or dynamic friction surface contour having at least one protrusion and/or one slanted and/or one gradually stepped surface contour. By means of a roughened surface contour or one provided with protrusions, the second bottom cutter, in particular, is suitable and designed to penetrate at least partially into a trapped hair and to cause a kind of "hooking in" effect so that after the second bottom cutter and trapped hair are "hooked in," a further movement of the bottom cutter relative to the top cutter can be transmitted on a nearly one-to-one basis to a pulling movement of the hair. So that an especially effective and easy "hooking in" of the bottom cutter into a trapped hair can take place, the protrusions or surface contours to be provided to the surface of the second bottom cutter are at least somewhat, but preferably significantly, smaller than the diameter of the hair so that any hair that has not yet been cut through by the second bottom cutter designed as a scraping blade can be completely cut through.

Another advantageous aspect of the invention provides that in each instance, at least one second bottom cutter or one blade of the second bottom cutter comes to lie and is arranged between blades of the first bottom cutter arranged next to one another in the direction of the oscillating movement.

At the same time, it can in particular be provided that all blades, both of the first and of the second bottom cutter, are in each instance interlaced on a common carrier. Various configurations of relative arrangements of blades of the two bottom cutters are conceivable for this. For configurations in which in each instance only one blade or one scraping element of the second bottom cutter is arranged between blades of the first bottom cutter arranged adjacent to one another in the direction of the oscillating movement, the scraping element can be arranged in the middle, between the adjacent blades of the first bottom cutter. However, depending on the design, this results in a relatively large gap or distance between the blades of the first bottom cutter and the blades of the second bottom cutter.

A better pulling result for hair to be trapped can be obtained if blades or scraping elements of the second bottom cutter are directly in front of the blades of the first bottom cutter, so that the gap between elements of the first and second bottom cutters is, for example, only some 10 μm.

It is also conceivable to arrange the individual blades of the first bottom cutter symmetrically in relation to the direction of the oscillating movement, and to assign each of the opposite cutting edges of a blade of the first bottom cutter in each instance to a pulling or blade element of the second bottom cutter. This arrangement can provide a sufficient and satisfactory pulling effect for trapped hair in each direction of movement of the bottom cutter assembly.

Another advantageous aspect provides that the second bottom cutter and/or components directly attached to the second bottom cutter audibly move up against a stop bar limiting the movement of the second bottom cutter or the underside of the top cutter after a hair is cut by the first bottom cutter by means of the elastic pretension provided. This can provide the user an acoustically detectable control that signals to the user in an intuitive way whether all the hair sprouting from a specific and just-shaved area of the skin has been sufficiently shortened.

For example, if on a well-shaven area of the skin there is hardly any hair left that could be caught by the second bottom cutter, the second bottom cutter, because of the lack of any available hair to be pinched, will not make any further movement down that would result in an acoustically detectable return stroke.

Thus as a result, moving a shaving apparatus along areas of the skin that have already been sufficiently shaved creates a relatively muted shaving sound, whereas when shaving areas of the skin with hair to be cut the shaving apparatus makes a clearly detectable sound.

According to another independent aspect, the invention relates to a dry shaving apparatus with a shaver head that has at least one top cutter and one bottom cutter assembly according to the present invention.

So that hair can always be cut to a length short enough so that the ends of the hair come to lie below the surface of the skin after shaving, the hair offered to the pulling and cutting system according to the invention must be of a sufficient length. Hairs that are too long hinder the system because they are generally harder to thread through the cutting system according to the invention and, in addition, they have to be precut by the cutting system before a cutting process can take place that provides hair cut under the skin. It therefore makes sense to shorten the hair before it is threaded into the pulling and cutting system according to the invention. That is why one embodiment of the invention provides that the shaver head comprises a precutting device. Especially advantageous precutting devices have exposed precutting edges and a comb-like top cutter that easily grasps hair, in particular long hair.

It is also conceivable to fuse the pulling and cutting system according to the invention with exposed precutting devices. For example, the top cutter of the pulling and cutting system could at the same time perform the function of the top cutter for the precutting device. The bottom cutter of the two precutting devices are then attached to the pulling and cutting system and can be moved in relation to it.

It is also conceivable to install bottom cutters with a pulling and cutting function or mechanism directly into the exposed precutting device. This can also increase the ability to thread hair into the pulling and cutting system.

The invention also comprises a shaving method for use in a dry shaving apparatus, wherein the dry shaving apparatus has a bottom cutter assembly having a first and a second bottom cutter. At the same time, the second bottom cutter is positioned in front of the first bottom cutter with regard to a relative oscillating movement between the top cutter and the bottom cutter assembly so that it moves sideways in front of the trailing first bottom cutter having trapped hairs in the engagement position.

The shaving method according to the invention provides that the top cutter and the bottom cutter assembly move relative to each other in an oscillating, preferably translatory oscillating fashion. This oscillating movement threads hairs through holes of a top cutter that is preferably configured as a perforated shearing foil. These hairs, which extend into the cutting system, are pinched by means of the second bottom cutter between the second bottom cutter and the top cutter and/or grasped by the second bottom cutter. Then, pinched or grasped hairs are bent and correspondingly pulled along the direction of movement and/or oscillation of the second bottom cutter so that the extended hair or the hair pulled out from the skin is cut through by the (preferably sharpened) bottom cutter that trails behind the second bottom cutter.

The exemplary embodiments described below use drawings to describe other objects, features and advantageous possibilities of application of the present invention. At the same time, all features depicted in images and described in words both individually and in reasonable combination with one another form the subject matter of the present invention, regardless of the claims or their references.

Fig. 1 shows a schematic sectional view of a threaded hair trapped between the top cutter and the second bottom cutter.

Fig. 2 shows a trapped hair immediately before it is grasped by the second

bottom cutter.

Fig. 3 shows a configuration of the cutting system as the trapped hair is bent sideways; and

Fig. 4 shows the hair being cut through by the first bottom cutter.

Fig. 5 shows another, enlarged view of the bottom cutter assembly, wherein the second bottom cutter hooks into the trapped hair.

Fig. 6 shows the embodiment according to Fig. 5 with a partially lowered

second bottom cutter. Fig. 7 shows the bottom cutter assembly with a completely lowered second bottom cutter; and

Fig. 8 shows a configuration immediately before the pinched hair is cut through by the sharpened first bottom cutter.

Fig. 9 shows an alternative configuration of the second bottom cutter having a beveled edge.

Fig. 10 shows another second bottom cutter having an outer contour consisting of a series of descending steps facing the hair.

Fig. 11 shows another configuration of a second bottom cutters having a

protrusion.

Fig. 12 shows a configuration of the second bottom cutters having two side

protrusions.

Fig. 13 shows a side-protruding protrusion on the second bottom cutter for

grasping and hooking into a hair.

Fig. 14 shows a further development of the second bottom cutter in combination with the first bottom cutter and the top cutter.

Fig. 15 shows several blades or scraping elements of the first and second bottom cutters, each of which is arranged on a carrier.

Fig. 16 shows the configuration according to Fig. 15 having an asymmetrically offset second bottom cutter. Fig. 17 shows scraping blades positioned in front of both sides of the sharpened blades of the first bottom cutter.

Fig. 18 shows a schematic drawing of a spring-loaded coupling of cutting and pulling components.

Fig. 19 shows an alternative configuration of a spring coupling having two-way stops between the blades of the first and the second bottom cutter.

Fig. 20 shows a bottom cutter assembly pre-stressed by various pressure springs.

Fig. 21 shows a bottom cutter assembly according to Fig. 20 having a stop that limits movement.

Fig. 22 shows a schematic drawing of individual, spring-loaded scraping blades suspended in relation to the cutting blades.

Fig. 23 shows another configuration according to Fig. 22 having end stops for the scraping blade components.

Fig. 24 shows a fully detailed configuration of a bottom cutter assembly pre- stressed by means of two spring elements.

Fig. 25 shows a perspective view, diagonal from the top, of the bottom cutter assembly according to Fig. 24.

Fig. 26 shows a combination of the pulling and cutting system according to the invention having a pre-cutting device. Fig. 27 shows a combination of the pulling and cutting system according to the invention having two pre-cutting devices; and

Fig. 28 shows another combination of the pulling and cutting system according to the invention having two pre-cutting devices.

Fig. 1 shows a schematic sectional view through a bottom cutter assembly 10 that has a first bottom cutter 14 and a second bottom cutter 22, both of which can move back and forth translatorially in a horizontal direction in relation to a top cutter designed as a kind of perforated shearing foil 12.

As is indicated in the sequence according to Figures 2 through 4, the second bottom cutter 22 is designed to work together with a trapped hair 18 and with the underside of a foil bar 12 in such a way that a hair extending through a hole 20 of the top cutter 12 is, as a consequence of the sideways movement of the two bottom cutters 14, 22, bent to the right in this same direction and pulled to a certain extent, as is clear from a comparison of the [different] positions of the hair in Figures 3 and 4.

The second bottom cutter 22, which is designed as a so-called "scraping cutter" or "scraping blade" is accordingly designed (if need be) to hook into the hair 18, not, however, to cut through it but only to exert a tensile force in a sideways direction on the bent hair, as is shown in Fig. 3. As Figures 5 through 10 show more clearly, because of the rounded outer contour 28 of the foil bar 12, a trapped hair 18 can be bent by the second bottom cutter 22 spring-mounted in a vertical direction and pulled by it to a certain extent in a horizontal direction. As Fig. 4 shows, before the hair 18 is cut through by the sharpened cutting edge 24 of the first bottom cutters 14, [it lies] completely on the level of the cutting plane 26.

At the same time, it is in particular contemplated that the blunt second bottom cutter 22 can, in relation to the cutting edge 24 of the first bottom cutter, drop down by at least a hair's width while increasing its distance from the top cutter 12; to that end it is spring-loaded so as to facilitate a pinching action to pinch the hair between the second bottom cutter 22 and the underside of a foil bar 12.

The outer contour and the geometry of the second bottom cutter 22 and the spring tension provided for the second bottom cutter 22 are matched to each other in such a way that the bottom cutter 22, as shown in Fig. 3, either slides along with its top side on the bent hair 18 (while obtaining a synchronous effect) or the second bottom cutter 22, as is shown sequentially in Figures 5 through 8, penetrates the hair 18 at least to a certain extent by means of a preceding edge while forming a notch 30, and at the same time "catches onto" it, as it were, so that the lateral movement of the bottom cutter 22 can ultimately be faithfully transmitted to a "pull-out" movement of the hair 18 from the skin.

Figures 9 through 14 show various geometric configurations of a second bottom cutter designed as a scraping cutter or scraping blade. For example, the scraping cutter 32 according to Fig. 9 has a slant 33 that makes it easier to bend the hair 18. Similarly, the scraping or bottom cutter element 34 shown in Fig. 10 has a step-like contour 35 by means of which the scraping cutter 34 can at least partially hook into the hair 18.

Fig. 11 shows a protrusion 37 arranged on the top side of a scraping cutter component or scraping blade 36 that provides a connected depression so that the scraping blade cannot be levered out from the bent hair. This depression compensates for the displacement effect created by the scraping edge penetrating the hair and the scraping blade remains hooked into the hair.

Fig. 12 also shows a scraping element 38 having two such protrusions 39 extending upward, between which there is also a depression that serves the same purpose as the one described above. The configuration of the scraping element 40 according to Fig. 13 shows a laterally arranged protrusion 41 that hooks into a hair 18 that comes to lie to the right of the scraping element 40, which precedes the other part of the scraping element 40. The hair can be pulled along by means of a pinching effect with the top cutter 12 that comes to lie on top of the scraping element 40.

Fig. 14 shows a preferred embodiment in which the scraping element 42 or the second bottom cutter 42 has a step-like or step-like descending outer contour 35 at least part of which faces the trapped hair 18. However, on the top side and on the upward- facing front surface of the scraping element 42 are two protrusions 39, whose free ends in the initial position shown in Figure 14 come to lie in an intersection line 26 formed between the first bottom cutter 14 and/or the bottom cutter assembly and the top cutter 12.

A depression is formed between the two protrusions 39, which depression is suitable for receiving a section of hair bent downward. The distance 44 between an edge in front of the direction of movement of the left protrusion 39 of the scraping element 42 and the cutting edge in front of the movement of direction of the first bottom cutter 14 determines the maximum distance the hair 18 can be drawn out from the skin before it is completely cut through by the sharpened cutting edge 24 of the first bottom cutter.

This distance 44 should preferably be in an order of magnitude of several 100 μm, [more] preferably between 200 and 400 μm, and most preferably around 300 μm. In addition, a gap 45 that is at least approximately 50 μm or more is formed between the first bottom cutter 14 and the second bottom cutter 42.

Figures 15 through 25 show various ways to arrange the two bottom cutters relative to each other and to their individual blades. For example, Fig. 15 shows a fixed coupling of all three scraping elements or scraping blades 22 of a bottom cutter that by means of a horizontal carrier 56 form the actual bottom cutter assembly 50 containing a plurality of individual blades 22. At the same time, the individual scraping blades 22 come to lie approximately midway between individual blades 14 of the first bottom cutter 52, wherein its blades 14 are rigidly connected to one another by means of another horizontal carrier 58. One such embodiment of the invention allows the hair trapped by the top cutter to be grasped first by the cutting blade 24 and not by the scraping blade 22. The hair is then cut immediately without having first been pulled, which is disadvantageous in terms of possible [shaving] thoroughness.

However, with an arrangement according to Fig. 16, in which the second bottom cutter 50 along with its individual blades 22 is arranged as close as possible to the first bottom cutter 52 that trails behind the blade 14 a better shaving result can be obtained by increasing the length a hair is drawn out before it is cut. In this configuration, the distance, or the extent, of the gap between adjacent blades 22, 14 is correspondingly small, so that a pinched or hooked-in hair can, if necessary, be cut through by scraping blade 22 while still under tensile stress from the sharpened bottom cutter 14 trailing behind; whereas in the configuration according to Fig. 15, because of the relatively great distance between scraping cutter components 22 and the cutting blade components 14, a temporary relaxation and retraction of the hair can, where possible, take place before it is grasped by the sharpened blade 14 trailing behind.

The configuration according to Fig. 16 may require that the second bottom cutter 50 not be coupled with the first bottom cutter 52 in a horizontal direction, i.e. in the direction of the oscillating movement, but rather that the scraping cutter 50 is pushed by the cutting blade 52 also in a lateral direction, which ensures that the cutting edges 24 of the individual cutting blades 14 do not make contact with the scraping blades 22 of the scraping cutter 50. By reversing the direction of the movement of the cutter, the scraping cutter 50 remains standing for a short time and is then pushed forward in the opposite direction by the cutting blade 52. This can significantly increase the likelihood of the hair 18 being grasped, because the distance between the bottom cutter components 14, 22 that precede and trail behind, respectively, can be advantageously reduced.

The configuration according to Fig. 17 requires in each instance arranging a scraping blade 22 of the second bottom cutter 50 in relation to the direction of oscillation on both sides of each cutting blade 14 of the first bottom cutters 52. Such a configuration can further increase the likelihood of grasping trapped hair compared to the configuration shown in Figure 16. This allows almost every hair to be grasped. However, in this case the structural complexity is comparatively high because twice as many scraping blades 22 as cutting blades 14 have to be provided.

Whereas in the drawings according to Figures 15 through 17 only the relative positioning of the individual blades or components of the two bottom cutters without their spring coupling is shown, the additional Figures 18 through 25 reflect different ways to spring load scraping and cutting blade components. In Figures 18 through 23, the top cutter and the foil bar 12 are not included for the sake of clarity; only the cutting plane 26 defined by the top and bottom cutters is shown.

At the same time, the relative positioning of scraping blades 22 and cutting blades 14 according to Figures 18 through 23 is based on the configuration according to Fig. 17. Nevertheless, the concepts for seating the springs as shown in Figures 18 through 23 can also apply equally to the configurations according to Figures 15 and 16.

In Fig. 18, two scraping blades 22 are in each instance assigned to each cutting blade 24. The scraping blades are only vertically displaceable vis-a-vis each cutting blade 14 by means of the guides 54 provided for that purpose. At the same time, each scraping blade 22 is mounted in a vertical direction by means of a separately provided spring element 60; i.e., perpendicular to the actual cutting movement of the first bottom cutter 52. At the same time, the entire first bottom cutter 52 is elastically supported by another spring element 62 [mounted] on a base 64; this base element 64 can be part of a supporting structure either of the shaving apparatus itself or of its shaver head.

By means of the pressure spring 63 using a defined pretensioning force, the first bottom cutter 52 that has the three blades 14 shown as examples in Fig. 18 for cutting hair 18 presses against the underside of the shearing foil 12 (not shown explicitly in Fig. 18). Typical configurations of such bottom cutters 52 provided with sharpened blades may have a total of 30 or more blades 14. At the same time, the bottom cutter 52 can itself be designed as a molded sheet-metal part with a U-shaped lateral cut running in the direction of oscillation.

As opposed to the configuration according to Fig. 18, the configuration according to Fig. 19 has alternating stops 66, 68 assigned to the individual cutter components 14, 22. For example, flange-like protrusions 66 are provided on the cutting blade 14 that act as movement-restricting end stops for the scraping components 22, which components are equipped with a corresponding counter-stop 68. This allows the scraping blades 22 to be only relatively lightly pre-stressed in relation to inner side of the shearing foil.

Thus, this can reduce the friction between the components of the second bottom cutter and the shearing foil otherwise generated by the individual scraping elements 22. By means of the coordinated stops 66, 68, a relatively non-linear force/displacement characteristic can be provided for the scraping blades 22. For example, the spring element 60 can be relatively strong in order to be able to provide a relatively high degree of contact or friction force between the front-side end section of the scraping blade 22 and a hair 18 to be pinched during a minor descent of a scraping blade 22.

In the configuration according to Fig. 20, although the individual scraping blades 22 of the second bottom cutter 50 are rigidly connected to one another by means of a carrier 56, 58 running crosswise (more or less like the blades 14 of the first bottom cutter 52), the spring-loaded suspension (completely independent of each other) of the first bottom cutter 52 and of the second bottom cutter 50 is accomplished by means of spring elements 72, 70 provided especially for this purpose [that are set] against a base 64 that is stationary in relation to the vertical [elements]. This base 64 takes part in the oscillating movement of the bottom cutter assembly. At the same time, the cutting blade 52 can be pre-stressed a relatively great amount against the shearing foil 12 so that it barely descends or does not descend at all, even under stress.

At the same time, the pre-stressing of the second bottom cutter 50 is preferably measured so that it can descend upon contact with hair 18 in the manner described above while pinching each hair 18. At the same time, the scraping blade 50 can move independent of the cutting blade 52, at least in the vertical direction. As a result of the application of the pre-stressing on the scraping blade 50 provided by the spring elements 70, a targeted minimum contact force between the scraping blade 22, the trapped hair 18 and the inner side of the shearing foil 12 can be set, which can prevent or reduce the [amount the] hair slips between scraping blade 22 and the shearing foil.

In particular, the configuration shown in Fig. 20 requires that the pressure springs 72 provided for the cutting blade 52 be significantly stronger than the pressure springs 70 provided for the scraping blade 50.

To that end and analogous to the path-limiting coupling shown in Fig. 19, Fig. 21 shows an alternative configuration in which the scraping blade 50 and the base part 64 are provided with alternating stops 74, 76 to limit any adjusting movement. As was already explained with regard to Fig. 19, this configuration can provide a non-linear

force/displacement characteristic for the scraping blade and its individual blades 22.

Figures 22 and 23 show two other exemplary embodiments in which the individual scraping blades 22 are not only decoupled from one another but in each instance are decoupled individually and, unlike the configuration according to Figures 18 and 19, are also decoupled from the cutting blade 52 in a vertical direction. In this configuration, the base part 86 is wider and has a plurality of individual pressure springs 78, each of which is dedicated to an individual scraping blade 22, while the cutting blades 14 are coupled over their common carrier 58 by means of the pressure springs 80 elsewhere to a wider, flange-like section of the base part 86.

The configuration according to Fig. 23 differs from that shown in Fig. 22 in that a sideways projecting stop 84 is configured on each scraping element 22, which stops work together with counter-stops 82 provided for each [element], which for their part are arranged on the base 86 to limit the movement of the individual scraping blades 22.

The advantage of the configuration according to Figures 22 and 23 is that the first bottom cutter 52, which has cutting blades like those provided by the individual scraping blades 22, is hardly impaired at all. Furthermore, the scraping blades are decoupled from one another and cannot disrupt one another, even when several "pulls" take place at the same time. The counter-stops 82 limit the pre-stress against the top cutter, which can keep the friction between the scraping blades and the top cutter to a minimum, regardless of the pre-stress between the top cutter and the cutting blades. As a result, a non-linear descent characteristic can be realized.

Although the fixed coupling among one another of individual scraping blades 22 over a common carrier 56 like the one shown in Figures 20 and 21 can be realized with relatively few parts to be assembled and with a reasonable amount of assembly work, such a configuration has the disadvantage (compared to the individual hanging of scraping blades 22 that is shown in Figures 18, 19, 22 and 23) that a descent of an individual scraping element 22 caused by pinching a hair 18 also causes other scraping blades 22 that are arranged at a distance to the side to be conveyed to a position lower than the cutting plane 26, which position is not very suitable for pinching additional hairs 18. Figures 24 and 25 show a perspective view of a fully detailed configuration of another bottom cutter assembly 100 for an exposed cutting system. In this configuration, the first bottom cutter 102 provided with individually sharpened cutting blades 114 is engaged with the scraping cutter 104 and the individual scraping blades 122 arranged on it, wherein the scraping blades 122 and/or the entire scraping cutter 104 are pre-stressed by means of two lateral spring elements 110 against a carrier 106, while the cutting blade 102 is pre-stressed by means of a separate spring element 108 against the carrier element 106.

Figures 26 through 28 depict extremely simplified and schematic combinations of a pulling and cutting system according to the invention having one or two pre-cutting devices.

According to Fig. 26, a bottom cutter 131 of a pulling and cutting system like the one corresponding, for example, to the one shown in Fig. 25 is assigned to a comb-shaped top cutter 130 against which it is propelled in a translatory oscillating movement by a [missing word] (not shown) transverse to the arrangement of the comb-like teeth 132 - i.e. perpendicular to the plane of the drawing. The tips 133 of the comb-like teeth 132, each of which is separated by thread ends lying between them that restrict them laterally, protrude above the bottom cutter 131 to a certain extent in a horizontal direction, which optimizes the supply of hair. On the underside of the comb-like teeth 132 facing the bottom cutter 131 are cutting edges 134 that work together with the bottom cutter 131. The arm 135 provided on the bottom cutter 131 helps both to guide and to couple a drive of the pulling and cutting system. The leg 136 helps to fix the top cutter 130 within the overall cutting system.

Fig. 27 shows a symmetrical arrangement of two systems according to Fig. 26, each of which consists of a bottom cutter 131 of a pulling and cutting system and a comb- shaped top cutter 130, wherein the tips 133 of the top cutter 130 point in opposite directions. Such a cutting system can then be used in both directions - forward and back - with equal effectiveness. Fig. 28 shows a complete pulling and cutting system 140 according to the invention whose top cutter 141 has additional, laterally arranged pre-cutting combs 142 that extend horizontally. They are part of an exposed pre-cutting system whose active elements are the oscillating (also comb-shaped) shearing elements 143. These shearing elements 143 form the bottom cutter of the pre-cutting system and can be run together with the bottom cutter arrangement of the pulling and cutting system 140 according to the invention (not shown).

Claims

CLAIMS What is claimed is:

1. Bottom cutter assembly for a dry shaver having a top cutter (12) provided with holes and a motor to drive the oscillation back and forth of the top cutter (12) and bottom cutter assembly, wherein the bottom cutter assembly has at least one bottom cutter (14) and a second bottom cutter (22; 32; 34; 36; 38; 40; 42) that precedes the first bottom cutter (14) in the direction of the oscillating movement, which bottom cutter is designed to exert a tensile force on a hair (18) extending into the hole (20) of the top cutter (12) to be pinched between the second bottom cutter (22; 32; 34; 36; 38; 40; 42) and the top cutter (12).

2. Bottom cutter assembly according to Claim 1, wherein the first bottom cutter (14) has a sharpened cutting edge (24) for cutting through a hair (18).

3. Bottom cutter assembly according to any of the preceding claims, wherein the top cutter (12) has a rounded-off edge contour contiguous to its holes (20) and/or the second bottom cutter (22; 32; 34; 36; 38; 40; 42) has a rounded-off outer contour facing the top cutter (12) on its end section that faces the first bottom cutter (14) and precedes it in the direction of the oscillating movement.

4. Bottom cutter assembly according to any of the preceding claims, wherein the first bottom cutter (14) and the second bottom cutter (22; 32; 34; 36; 38; 40; 42) rigidly coupled to each other in terms of the direction of the oscillating movement.

5. Bottom cutter assembly according to any of the preceding claims, wherein the first bottom cutter (14) and the second bottom cutter (22; 32; 34; 36; 38; 40; 42) are decoupled from each other perpendicular to the direction of the oscillating movement.

6. Bottom cutter assembly according to any of the preceding claims, wherein the first bottom cutter (14) and the second bottom cutter (22; 32; 34; 36; 38; 40; 42) are independently pre-stressed from each other against the top cutter (12)

perpendicular to the direction of the oscillating movement.

7. Bottom cutter assembly according to any of the preceding claims, wherein the first bottom cutter (14) and the second bottom cutter (22; 32; 34; 36; 38; 40; 42) are pre-stressed against the top cutter in each instance by means of at least one spring element, wherein the force exerted on the second bottom cutter (22; 32; 34; 36; 38; 40; 42) in the direction of the top cutter (12) is less than the force exerted on the first bottom cutter (14) in the direction of the top cutter (12).

8. Bottom cutter assembly according to any of the preceding claims, wherein the second bottom cutter (22; 32; 34; 36; 38; 40; 42) has a static or dynamic friction- increasing surface on an end section facing the top cutter (12).

9. Bottom cutter assembly according to any of the preceding claims, wherein the second bottom cutter (32; 34; 36; 38; 40; 42) has a static or dynamic friction- increasing surface contour having at least one protrusion (37; 39; 41) and/or a beveled and/or a gradually declining surface contour (35) on at least one side facing the hair (18) to be pinched or grasped.

10. Bottom cutter assembly according to Claim 9, wherein the length of the protrusion (37; 39; 41) is less than the average thickness of a hair (18).

11. Bottom cutter assembly according to any of the preceding claims, wherein in each instance a second bottom cutter (22; 32; 34; 36; 38; 40; 42) is arranged between blades (14) of the first bottom cutter (52) arranged next to one another in the direction of the oscillating movement.

12. Bottom cutter assembly according to any of the preceding claims, wherein the second bottom cutter (22; 32; 34; 36; 38; 40; 42) audibly moves up against a stop (12; 66; 76; 82) limiting the movement of the second bottom cutter (22; 32; 34; 36; 38; 40; 42) after a hair (18) is cut by the first bottom cutter by means of an elastic force.

13. Dry shaving apparatus having a shaver head that has at least one top cutter (12) and one bottom cutter assembly according to any of the preceding claims.

14. Dry shaving apparatus according to Claim 13, wherein the shaver head comprises a pre-cutting system (132, 131; 142,143).

15. Shaving method for use in a dry shaving apparatus having a bottom cutter

assembly (10) having a first (14) and a second bottom cutter (22; 32; 34; 36; 38; 40; 42), wherein the second bottom cutter (22; 32; 34; 36; 38; 40; 42) is positioned in front of the first bottom cutter (14) with regard to a relative oscillating movement between the top cutter (12) and the bottom cutter assembly (10), wherein the method comprises the following steps:

- the top cutter (12) and the bottom cutter assembly (10) oscillate relative to each other;

- at least one hair (18) is threaded into a hole (20) in the top cutter (12);

- the trapped hair (18) is pinched or grasped between the second bottom cutter (22; 32; 34; 36; 38; 40; 42) and the top cutter (12);

- the hair (18) is bent and/or pulled in the direction of the oscillating

movement;

- the hair (18) is cut through by the first bottom cutter (14) that trails behind.