Electric beard trimmer

Abstract

The present invention relates to a cutting device system 3 for an electric shaver and / or trimmer 1, the cutting device system 3 comprising a pair of cooperating cutting blades 4, 5 each having at least one row of comb-like cutting teeth 6, 7, one of the cutting blades being a fixed cutting blade and the other being movable relative to the fixed cutting blade along a cutting plane 8 defined between the cooperating cutting blades, the cutting teeth each having a pair of transverse cutting edges 9 tapering towards a tooth tip 11, at least one tooth tip of the cooperating cutting blade having a flat chamfered leading surface 12, The skin contact surface 14 of the device system guides the cutting blade in the region of the tooth tip on the user's skin and has an inclined front end portion 14f defining an acute angle φ with respect to the cutting plane, and the flat chamfered tip surface is inclined at an acute angle ε with respect to an imaginary plane 27 which extends parallel to the cutting direction 25 and is perpendicular to the skin contact surface and / or the tangent plane 33 tangential to it, such that the tooth tip contacts the imaginary plane only at the cutting surface having a substantially wedge-shaped gap 29 between the flat chamfered tip surface and the imaginary plane.

Description

[Technical field]

[0001] The present invention relates to cutting body hair such as multi-day beard stubble. More particularly, the present invention relates to a cutting device system for an electric razor and / or trimmer, comprising a pair of cooperating cutting blades each having at least one row of comb-like cutting teeth, one of the cutting blades being a fixed cutting blade and the other being movable relative to the fixed cutting blade in a cutting direction along a cutting plane defined between the cooperating cutting blades, the cutting teeth each having a pair of transverse cutting edges tapering towards the tooth tips, and the skin contact surface of the cutting device system defined by the surface of the fixed cutting blade facing away from the movable cutting blade or a distance comb attached to the fixed cutting blade has an inclined front end portion in the region of the tooth tips for guiding the cutting blade along the skin of a user and defining an acute angle with respect to the cutting plane. Furthermore, the present invention also relates to an electric razor and / or trimmer including such a cutting device system. [Background technology]

[0002] Electric razors and trimmers utilize a variety of mechanisms to provide hair cutting functionality. Some electric razors include a perforated shear foil that cooperates with a lower cutting device movable relative to the shear foil to cut hair that falls into the perforations in the shear foil. Such shear foil type razors are often used on a daily basis to provide a clean shave where short beard stubble is cut just above the skin surface.

[0003] On the other hand, other cutting device systems including a pair of cooperating comb-like cutting elements with multiple comb-like or rake-like cutting teeth reciprocating or rotating relative to each other are often used to cut long beard stubble or problem hairs that are difficult to cut, for example because they grow at a very small angle to the skin or from very elastic skin. The teeth of such comb-like or rake-like cutting elements usually project substantially parallel to each other or substantially radially, depending on the type of drive movement, and are able to cut hairs that enter the gaps between the cutting teeth, the cutting or shearing being achieved in a scissor-like manner when the cutting teeth of the cooperating elements close the gaps between the finger-like cutting teeth and pass each other.

[0004] Such a cutting device system for longer hair may be integrated into an electric razor or trimmer and may at the same time comprise the above-mentioned shear foil cutting device. For example, the comb cutting element may be disposed between a pair of shear foil cutting devices or may be disposed in a separate extendable long hair cutting device. On the other hand, there are also electric razors or trimmers or styling devices that are provided with only such a comb cutting element.

[0005] For example, EP 2425938(B1) shows a razor having a pair of long hair trimmers integrated between shear foil cutting devices. Furthermore, CN 206287174(U) discloses a beard trimmer having a pair of cooperating comb-like cutting elements, each of which is provided with two rows of protruding cutting teeth.

[0006] Furthermore, EP 3003654(B1) discloses a hair clamping device having a pair of cooperating cutting blades with comb-like cutting teeth, wherein the fixed cutting blade forming the skin contact surface of the cutting device system should have transverse cutting edges with a wedge-shaped cross-section defining a wedge angle of less than 55°, and the finger-like cutting teeth should taper towards the tooth tips with an opening or scissor angle in the range of 5° to 25°.

[0007] US Patent Application Publication No. 20160229070 discloses a hair trimmer movable blade having a flat chamfered portion close to the tooth tip at a tooth height level away from the cutting surface, the tooth tip is not chamfered but includes a vertical region extending perpendicular to the cutting surface of the movable blade.

[0008] WO 2018109093(A1) discloses a movable blade of a hair trimmer having flat chamfered teeth.

[0009] Such beard stubble trimmers must address very different and diverse functional requirements and performance issues, such as close contact, thoroughness, good visibility of the cutting location, efficiency, and pleasant feel, good ergonomics and handling. Close contact means short or very short remaining stubble, whereas thoroughness means fewer missed hairs, especially in problem areas such as the neck. Efficiency means fewer and faster strokes, sufficient to achieve the desired trimming result. Pleasant feel depends on the individual user, but often includes better glide over the skin with less irritation in the form of cuts or abrasions.

[0010] To achieve a smooth and efficient cut, the hair should be cut on first contact with the cutting blades as it enters the gap between the finger-like teeth. However, such a first contact cut is difficult to achieve due to the scissor-like, shear-type cutting action of the comb-like cutting blades, since the hair is not cut by contacting only the cutting edge of one cutting blade, but by being caught between the cutting edges of the cooperating cutting teeth, i.e., at the shear or contact point where the cutting edge of one cutting blade slides over the cutting edge of the other cutting blade.

[0011] Conventional cutting device systems tend to deflect and reject hairs several times before actually cutting them. The teeth of the moving cutting blade impact the hairs and kick them out before they are caught between the transverse cutting edges that slide over each other. Due to this impact action of the cutting teeth, the hairs kind of "dance" in that they resiliently swing and deflect like a snake before being cut.

[0012] Such hair dancing is especially seen at the entrance of the gap between the interdigital cutting teeth. Usually, depending on the user's preference for manually moving the trimmer along the skin, the moving speed of the cutting device system along the skin surface is usually low compared to the cutting speed of the cutting blade transverse to the moving direction, and therefore most of the cutting action occurs at the front end part of the cutting tooth close to its tip. Since the moving speed is low compared to the cutting speed, the cutting teeth of the driven cutting blade mainly strike the hair entering the gap between the interdigital cutting teeth laterally, i.e. with a major moving component of the cutting direction transverse to the moving direction of the cutting device system. Thus, when viewing the cutting scene in the moving direction of the cutting device system, the hair dances from left to right before being cut. Such dancing causes the hair to contact the moving teeth of the driven cutting blade multiple times before actually reaching the shearing point where adjacent cutting edges pass each other to cut the hair.

[0013] One issue that makes first contact cutting difficult is the hair growth direction, which is usually not perpendicular to the skin surface, but hairs tend to grow out of the skin at an acute angle and therefore collide with the protruding cutting teeth before reaching the shear point where the cooperating teeth pass each other. More specifically, slanted or oblique hairs can be pushed aside by the top contour of the cutting teeth that is spaced away from the cutting surface, and therefore do not directly and smoothly reach the shear point where the cutting edges of the two cooperating teeth begin to overlap each other and cut the hair with a scissor-like shearing action.

[0014] Trimmers operate on the principle of scissor cutting, where two relatively blunt blades, such as a fixed blade and a movable blade, act against each other to shear the hair between them. Relatively blunt means that one blade alone is not sharp enough to cut the hair. The cutting, or more precisely the shearing, occurs because the blades move against each other and act as a counterblade. The cutting occurs in the cutting or shearing zone, where the surfaces of the two blades come into contact and move towards each other, so that only the cutting edge directly at the cutting surface can make the cut, while the more raised part of the cutting tooth, in that it is away from the cutting surface, rejects the hair rather than cutting it. Typically, the movable blade may be driven by a motor into a lateral / transverse oscillating motion, and the speed of the movable blade is typically high compared to the manual movement of the trimmer across the skin.

[0015] Both the fixed and movable blades have a number of teeth on their front faces, the sides of which are formed as cutting edges, and the movable blade is typically set back from the fixed blade to avoid skin damage.

[0016] As the trimmer moves over the skin, the hair is first threaded between the teeth of the fixed blade. The cutting edge of the fixed blade is relatively blunt so it does not cut the hair by itself. Rather, the hair is guided towards the movable blade. As the hair enters the area of ​​the movable blade, it may first be contacted by the tip of the movable blade. The tip of the movable blade also has a material thickness above the cutting area so that the hairs may be pushed aside without immediately cutting them. The thickness of material at the tips of the teeth above the cutting surface does not contribute to cutting, but reduces efficiency by pushing the hair aside.

[0017] This occurs especially when the hair is inclined towards the movable blade. This is very common and there are two reasons. First, most hairs grow out of the skin at an acute angle significantly different from 90°. Second, for good efficiency, the trimmer is usually held at an angle to the skin so that the tip of the fixed blade goes under the inclined hair, lifts it up, and then feeds the hair into the cutting system. Such an inclined positioning of the cutting device system with the teeth inclined downwards to the skin is facilitated and guided to some extent by an inclined leading end portion of the skin contact surface at the bottom of the cutting device system, which may be inclined at an acute angle to the cutting plane defined between the cutting blades. Thus, certain parts of the hair are inclined towards the movable blade and therefore can be more easily kicked out by the movable blade.

[0018] It is very difficult to simultaneously meet the various performance problems mentioned above. For example, EP 3003654(B1) aims at an efficient cutting action with a fairly low contact pressure between the cutting blades, but it tends to leave uneven cut lengths and produce plucking and picking due to the hair being pushed aside when the cutting device system is moved along the skin surface. The cutting efficiency is adversely affected by the aforementioned problem of the moving cutting blade colliding with the hair and kicking it out, which cannot be avoided by the specific structure of the fixed blade proposed by this document. As a result, first contact cutting cannot be achieved. [Prior art documents] [Patent documents]

[0019] [Patent Document 1] European Patent No. 2425938(B1) [Patent Document 2] Chinese Patent No. 206287174(U) [Patent Document 3] European Patent No. 3003654(B1) [Patent Document 4] U.S. Patent Application Publication No. 20160229070 [Patent Document 5] International Publication No. 2018109093(A1) Summary of the Invention [Means for solving the problem]

[0020] The object underlying the present invention is to provide an improved cutting device system which avoids at least one of the drawbacks of the prior art and / or further develops existing solutions. A more specific object underlying the present invention is to provide a highly efficient and at the same time reliable and clean cutting action of the cooperating cutting teeth, even when moving the cutting device system with fast strokes along the skin contour, without sacrificing a smooth and comfortable cutting action.

[0021] A further object underlying the present invention is to achieve a first contact cut without hair dancing at the entrance to the gap between adjacent cutting teeth.

[0022] At least one of these objects is achieved by the features of claims 1, 17 and 18.

[0023] Further advantageous features are set forth in the dependent claims.

[0024] In order to achieve at least one of the above-mentioned objects, it is proposed to provide the tips of the cutting teeth with a configuration that does not push or displace hairs that enter the gaps between the comb teeth to a small extent, and allows the hair to quickly find a cutting position between the cooperating cutting edges. More specifically, the chamfered tip surface of at least the tip of the movable cutting blade is inclined at an acute angle to an imaginary plane extending parallel to the cutting direction and perpendicular to the front end part of the skin contact surface of the cutter system and / or a tangent plane tangent thereto, so that the tooth tip contacts the imaginary plane only at the cutting surface with a substantially wedge-shaped gap between the flat chamfered tip surface and the imaginary plane. The chamfer at the tip of the tooth removes sufficient material at the tip portion that may cause the hair to be pushed out, so that in particular hairs that grow out of the skin at an acute angle and therefore are inclined towards the cutter system are less likely to be contacted and pushed out by the tooth tip. Considering the high transverse cutting speed, it is somewhat surprising at first glance that the kicking out and dancing of hairs can be reduced by giving the tooth tips a certain configuration relative to the skin contact surface of the cutter system, as it is assumed that it is the tooth sides that are responsible for kicking out the hairs. However, tilting the tooth tips backwards reduces the height of the teeth at their forward end, making the transverse cutting edges kind of sharp at their forward-most parts, so that the hair, even when growing obliquely, has a reduced tendency to contact the raised parts of the teeth before directly contacting the cutting edges at the cutting surface. Since the cutting speed is rather high compared to the forward movement of the cutter system, the most forward or outermost parts of the transverse cutting edges become more effective, and the first contact cut there is likely to be very helpful in reducing the dancing of hairs. The above tooth tip design means that the forward most tip of the cutting tooth of the movable cutting blade has substantially no vertical planar area perpendicular to the cutting surface (plane), or such vertical extent at the forward most tip is less than the diameter of a hair (0.1 mm), so that both the tooth tip and the above wedge shaped gap are sharp and extend to the cutting surface. In other words, a flat chamfered leading surface extends to the cutting surface of the cutting tooth.

[0025] More specifically, the tooth tip surfaces are angled away from the hair in front of the cutting blade, i.e., the tooth tip surfaces are angled backwards towards the base of the teeth, so that hair that enters the comb-like teeth, even if it grows diagonally or is inclined away from the skin, is less likely to be kicked away by the tip of the cutting teeth and is more likely to be cut on initial contact with the cutting teeth.

[0026] More specifically, because at least the cutting teeth of the movable blade are provided with such flat beveled tooth tip surfaces, hair dance can be significantly reduced since the hair is primarily dislodged by the reciprocating motion of the movable cutting blade or the moving cutting blade moving in and out of the gaps between the teeth of the fixed cutting blade. Because the leading edge surface is angled backwards, the hair is less likely to strike the leading edge surface before it is sheared between the cutting edges of the cooperating blades.

[0027] In order to achieve first contact cutting without causing hair to dance and at the same time have sufficient structural stability of the teeth, the inclination angle of the acute angle of the flat chamfered tip surface relative to the aforementioned imaginary plane may be in the range of 10° to 40° or 10° to 20°.

[0028] A flat chamfered tooth tip may have a substantially planar tip surface, in which case the gap between the tooth tip and the aforementioned imaginary plane may actually be wedge-shaped. However, a tip surface that still has a planar configuration may not be exactly planar, but may include some curvature, such as a slightly convex or concave portion, or some rounding or non-planar portion, and thus a substantially wedge-shaped gap may be considered to be defined between an imaginary plane and a tangent plane that is tangent to the tip surface. In other words, the wedge that defines the gap does not have to have two flat sides. More specifically, a wedge-shaped gap may have a wedge surface that is not exactly planar on the side facing the tooth tip.

[0029] More specifically, the tooth tip of the movable cutting blade can define a linear profile parallel to the cutting direction in a cross-sectional plane parallel to the cutting surface, so that the hair contacting the tip surface can slide smoothly along the tooth tip surface without experiencing a collision force due to the lateral cutting motion. Because the tooth tip surface lacks a convex or concave profile when viewed in a cross-sectional plane parallel to the cutting surface, it does not provide a wedge-shaped rejection force to the hair even when it reciprocates at high speed in the cutting direction, but the tooth tip surface of the moving cutting tooth can slide smoothly along the hair contacting the tip surface.

[0030] More specifically, the cutting tooth may define a pyramidal profile at the tooth tip having three inclined flat surfaces that join one another, one of the inclined flat surfaces being formed by a flat chamfered tip surface and the other two inclined flat surfaces being formed by the transverse cutting edges of the cutting tooth. Such a pyramidal profile may be a kind of partial pyramid, having only three flat inclined surfaces and not a complete pyramid since it lacks a fourth side of the pyramid, and furthermore does not have a rectangular base as a regular pyramid does, but is nevertheless similar to a portion of a pyramid having three flat sides that are inclined relative to each other and inclined relative to the base.

[0031] To further aid in cutting the hair on initial contact with the teeth, the flat beveled tip surface may be substantially planar with an angular transition to the lateral cutting edge of the cutting tooth, the angular transition having a radius of curvature of less than 50 μm, or less than 25 μm, or less than 10 μm. Such a steep transition from the tip surface to the lateral cutting edge grabs the hair that passes the tooth tip more or less immediately above the lateral cutting edge and avoids pushing the hair away, as would be the case with a rounded transition with a significantly larger radius of curvature from the lateral cutting edge to the tip portion.

[0032] A hair that has passed the tooth tips and entered the gap between a pair of adjacent cutting teeth is essentially ready to be cut or sheared by the transverse cutting edges of the pair of cooperating cutting teeth. Although the hair has passed the first hurdle, so to speak, with respect to the tooth tips, it may still be rejected or pushed out of the gap again when it contacts the transverse cutting edges. Usually, the transverse cutting edges do not extend exactly perpendicular to the direction of tooth movement, but are inclined relative to it, and usually the teeth are tapered towards the tooth tips to avoid cutting all hairs between a pair of cooperating teeth exactly at the same time. Due to the tapered configuration of the teeth, the overlap of the transverse cutting edges starts at the inner end or root portion of the teeth and, due to such tapered configuration, moves continuously outward towards the tooth tips when the cooperating teeth are driven laterally relative to each other. Thus, due to such tapered configuration, a smooth cutting action can be achieved. On the other hand, however, due to such a tapered configuration, the force applied to the hair by the contacting lateral cutting edges includes a component directed outward, i.e. from the bottom of the gap between the cooperating teeth towards the open end of the gap, thereby creating a tendency to deflect the hair outwardly and / or to push the hair towards the tooth tips. The greater the taper, the stronger the tendency to push the hair outwardly.

[0033] To address such issues, the opening angle between adjacent teeth and / or the tooth taper may be kept small or set to zero, but this would create high cutting forces that could block the system or lift the blade.

[0034] To allow some tapering and opening angle of the teeth large enough to keep the cutting forces small, but nevertheless avoid the aforementioned problem of pushing the hair back outwards towards the tooth tips, according to another aspect it is proposed to make the lateral cutting edges rather sharp to reduce the tendency to deflect the hair towards the tooth tips. More specifically, the lateral cutting edges of the cutting teeth may have a wedge-like configuration with a wedge angle of less than 60° or less than 50°, or in the range of 35°-60° or 45°-50°, when viewed in a cross section taken perpendicular to the longitudinal axis of the respective tooth.

[0035] In order to avoid pushing back hair at the tooth tips and lateral cutting edges, the sum of the aforementioned tip angle (between the chamfered tip surface and the cutting surface between the cutting blades) and the wedge angle of the lateral cutting edges may be less than 110°, or may be in the range of 60° to 110° or 90° to 110°.

[0036] The opening angle of the gap between two adjacent teeth, as defined by the lateral cutting edges of the adjacent teeth facing each other, may range from 10° to 30°, combining a smooth cut with retention of the hair within the gap. More specifically, the opening angle may range from 15° to 25°.

[0037] The opening angle may be selected differently for different wedge angles. For example, the larger the opening angle, the smaller the wedge angle. More specifically, the sum of the wedge angle and the opening angle may be less than 80°, or less than 75°, or less than 70°.

[0038] The above object is also achieved by providing a cutting tool for a cutting machine comprising a pair of cooperating cutting blades each having at least one row of comb-like cutting teeth, one of the cutting blades being a fixed cutting blade and the other of the cutting blades being a movable cutting blade movable relative to the fixed cutting blade in a cutting direction along a cutting surface defined between the cooperating cutting blades, the cutting teeth each having a pair of transverse cutting edges tapering towards their tips, at least the tips of the movable cutting blade being provided with flat chamfered leading surfaces which extend to the cutting surfaces of the cutting teeth and between the flat chamfered leading surfaces and the cutting surfaces. This is achieved by a cutting device system for electric shavers and / or trimmers, in which the transverse cutting edges, considering a cross section transverse to the longitudinal tooth axis of the respective cutting tooth, have a wedge-shaped configuration with a wedge angle (γ) in the range of 35°-60°, 40°-55°, or 45°-50°, the sum of the tip angle (β) and the wedge angle (γ) being less than 120° or less than 110° and / or in the range of 90°-120° or 100°-110°. This cutting device system may be combined with any of the features of the dependent claims.

[0039] These and other advantages will become apparent from the following description which refers to drawings and possible examples. [Brief description of the drawings]

[0040] [Figure 1] 1 is a perspective view of an electric beard trimmer including a cutting device system having a pair of cooperating comb-like cutting blades that reciprocate relative to one another; FIG. [Diagram 2] 2 is a side view of the beard trimmer of FIG. 1 showing the angled skin-contacting surface at the front end portion of the cutting blade. [Diagram 3] FIG. 3 is a cross-sectional view of the beard trimmer of FIGS. 1 and 2, showing the drive mechanism of the cutting device system; [Figure 4] FIG. 2 is a perspective view of the cutting device system of the trimmer of the previous figure, showing a movable support structure for movably supporting the movable cutting blade relative to the fixed cutting blade, and a spring mechanism for biasing the movable cutting blade against the fixed cutting blade; [Diagram 5]5 is a longitudinal cross-sectional view of the cutting device system of FIG. 4 showing a movable cutting blade and a fixed cutting blade arranged on top of each other. [Figure 6] FIG. 6 is a side cross-sectional view of a cutter system similar to FIG. 5 , shown in an inclined position with the skin contacting surface of the fixed cutting blade contacting the skin and the hair growing away from the skin at an acute angle, and the hair not contacting the tip of the movable cutting blade due to the beveled tip of the movable cutting blade. [Figure 7] FIG. 7 is a side cross-sectional view of a cutter system similar to FIG. 6, in which the teeth of the movable cutting blade lack a leading edge chamfer and therefore push aside hairs that grow at an angle. [Figure 8] FIG. 8 is a side cross-sectional view of the cutter system of FIG. 7, illustrating that tilted hairs are displaced even when the cutter system is not tilted too steeply. [Figure 9(a)] 1 is a diagram of a movable cutting blade, where partial view a is a perspective view of the entire movable cutting blade having a row of comb-like teeth, partial view b is a partial plan view of a pair of cutting teeth showing the opening angle defined between a pair of adjacent teeth, and partial view c is a bottom view of the cutting teeth showing the non-rounded transition from the lateral cutting edge to the tip. [Figure 9(b)] 1 is a diagram of a movable cutting blade, where partial view a is a perspective view of the entire movable cutting blade having a row of comb-like teeth, partial view b is a partial plan view of a pair of cutting teeth showing the opening angle defined between a pair of adjacent teeth, and partial view c is a bottom view of the cutting teeth showing the non-rounded transition from the lateral cutting edge to the tip. [Figure 9(c)] 1 is a diagram of a movable cutting blade, where partial view a is a perspective view of the entire movable cutting blade having a row of comb-like teeth, partial view b is a partial plan view of a pair of cutting teeth showing the opening angle defined between a pair of adjacent teeth, and partial view c is a bottom view of the cutting teeth showing the non-rounded transition from the lateral cutting edge to the tip. [Figure 10] FIG. 2 is a partial plan view of three teeth of a movable cutting blade, showing the flat beveled leading surfaces and wedge-shaped transverse cutting edges of the teeth. [Figure 11]FIG. 11 is a longitudinal cross-sectional view of the tooth taken along line AA in FIG. 10 to show the tip angle between the tooth tip and the cutting surface. [Figure 12] 11 is a cross-sectional view taken along line BB of FIG. 10, illustrating the wedge-shaped configuration of the transverse cutting edge and its wedge angle. [Figure 13] FIG. 11 is a cross-sectional view of a possible tooth tip configuration showing the tip angle. [Figure 14] FIG. 13 is a cross-sectional view of a cutting tooth illustrating the wedge configuration of the transverse cutting edges. [Figure 15] FIG. 2 is a side cross-sectional view of the cutting device system with an attached distance comb, showing the cutting device system contacting the skin surface and defining a tip angle relative to the skin contact surface by the distance comb. [Figure 16] FIG. 16 is a side cross-sectional view of the cutting device system similar to FIG. 15 but without a view of the distance comb. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0041] In order to smoothly introduce the hair into the cutting zone, it is proposed to give the tips of the cutting teeth a configuration which does not push or pushes away to a lesser extent hairs which enter the gaps between the comb teeth, enabling the hair to quickly find the cutting position between the cooperating cutting edges.

[0042] More specifically, the beveled tip surface of the tooth of the movable cutting blade is inclined at an acute angle to an imaginary plane extending parallel to the cutting or reciprocating direction of the movable cutting blade and perpendicular to the front end portion of the skin contact surface of the cutter system and / or the tangent plane tangent thereto, so that the tooth tip contacts the imaginary plane only at the cutting surface with a substantially wedge-shaped gap between the flat beveled tip surface and the imaginary plane. The bevel at the tooth tip removes sufficient material at the tip portion that can cause hair to be pushed out, so that hairs, especially those that grow out of the skin at an acute angle and therefore inclined towards the cutter system, are less likely to be contacted and pushed out by the tooth tip. It is somewhat surprising at first glance that hair kicking and hair dancing can be reduced by giving the tooth tip a specific configuration with respect to the skin contact surface of the cutter system, as it is assumed that it is the tooth flank that is responsible for kicking out the hair, taking into account the high transverse cutting speeds. However, tilting the tooth tips backwards reduces the height of the teeth at their forward end and makes the transverse cutting edges kind of sharp at their forwardmost parts, so that the hair, even when it grows at an angle, reduces the tendency to contact the raised part of the teeth before directly contacting the cutting edge at the cutting surface. Since the cutting speed is quite fast compared to the forward movement of the cutting device system, most of the cutting action occurs at the entrance of the gap between adjacent teeth, so the forwardmost or outermost part of the transverse cutting edge becomes more effective, and the first contact cut there is likely to be very helpful in reducing the dance of the hair. This means that the forwardmost tooth tips of the cutting teeth of the movable cutting blade have substantially no vertical planar area perpendicular to the cutting surface (plane), or such vertical extent is less than the diameter of a hair, so that both the tooth tips and the aforementioned wedge-shaped gap are sharp and extend to the cutting surface. In other words, the flat chamfered tip surface extends to the cutting surface of the cutting teeth.

[0043] More specifically, the tooth tip surfaces are inclined away from the hair in front of the cutting blades, i.e. the tooth tip surfaces are inclined backwards towards the roots of the teeth and / or backwards when taking into account the forward direction of the cutting device system, so that hairs entering the comb-like teeth row, even if they are growing at an angle or are angled away from the skin, are less likely to be kicked out by the tips of the cutting teeth and more likely to be cut on initial contact with the cutting teeth.

[0044] In order to achieve first contact cutting without causing hair to dance and at the same time have sufficient structural stability of the teeth, the inclination angle of the acute angle of the flat chamfered tip surface relative to the aforementioned imaginary plane may be in the range of 10° to 40° or 10° to 20°.

[0045] The tooth tips may define, in a cross-sectional plane parallel to the cutting surface, a linear profile parallel to the cutting direction, such that a hair contacting the tip surface may slide smoothly along the tooth tip surface without experiencing impact forces due to the lateral cutting motion. Because the tooth tip surface lacks a convex or concave profile when viewed in a cross-sectional plane parallel to the cutting surface, it does not provide a wedge-shaped rejection force to the hair even when it reciprocates at high speed in the cutting direction, but the tip surface of the moving cutting tooth may slide smoothly along a hair contacting the tip surface.

[0046] More specifically, the cutting tooth may define a pyramidal profile at the tip having three inclined flat surfaces that join one another, one of the inclined flat surfaces being formed by a flat chamfered tip surface and the other two inclined flat surfaces being formed by lateral cutting edges of the cutting tooth.

[0047] More specifically, the tooth tip of at least one of the cooperating cutting blades may have a flat chamfered leading surface, and a leading angle between the flat chamfered leading surface and the cutting surface defined between the cooperating cutting blades is in the range of 30° to 70° or 55° to 65°.

[0048] Such chamfering of the tooth tips helps reduce the displacement or deflection of hairs that attempt to enter the gap between adjacent cutting teeth. The chamfering of the tooth tips removes leading material that can cause hairs to be displaced, so that hairs, especially those that grow out of the skin at an acute angle and angled towards the cutter system moving forward along the skin contour, are less likely to be contacted and displaced.

[0049] More specifically, the cutting teeth of the movable cutting blade are provided with such flat chamfered tooth tips to avoid hair being dislodged by the reciprocating or moving cutting teeth moving in and out of the gaps between the teeth of the fixed cutting blade.

[0050] To further aid in shearing the hair upon initial contact with the cutting teeth, the flat beveled tip surface may be substantially planar with an angular transition to the lateral cutting edge of the cutting tooth, the angular transition having a radius of curvature of less than 50 μm, or less than 35 μm, or less than 25 μm, or even less. Such a steep transition from the tip surface to the lateral cutting edge grabs the hair that passes the tooth tip more or less immediately above the lateral cutting edge and avoids pushing the hair away, as would be the case with a rounded transition from the lateral cutting edge to the tip portion with a significantly larger radius of curvature.

[0051] A hair that has passed the tooth tips and entered the gap between a pair of adjacent cutting teeth is essentially ready to be cut or sheared by the transverse cutting edges of the pair of cooperating cutting teeth. Although having passed the tooth tips, the hair may still be rejected or pushed out of the gap again when it contacts the transverse cutting edges. Usually, the transverse cutting edges do not extend exactly perpendicular to the direction of tooth movement, but are inclined relative thereto, and usually the teeth are tapered towards the tooth tips to avoid cutting all hairs between a pair of cooperating teeth exactly at the same time. Due to the tapered configuration of the teeth, when the cooperating teeth are driven laterally relative to each other, the overlap of the transverse cutting edges starts at the inner end or root portions of the teeth and due to such tapered configuration, moves continuously outward towards the tooth tips. Thus, a smooth cutting action can be achieved by such tapered configuration. On the other hand, however, due to such a tapered configuration, the force applied to the hair by the contacting lateral cutting edges includes a component directed outward, i.e. from the bottom of the gap between the cooperating teeth towards the open end of the gap, thereby creating a tendency to deflect the hair outwardly and / or to push the hair towards the tooth tips. The greater the taper, the stronger the tendency to push the hair outwardly.

[0052] To address such issues, the open angle between adjacent teeth and / or the tooth taper can be kept small, but this creates high cutting forces that can block the system or lift the blade.

[0053] To allow some tapering and opening angle of the teeth large enough to keep the cutting forces small, but nevertheless avoid the aforementioned problem of pushing the hair back outwards towards the tooth tips, according to another aspect it is proposed to make the lateral cutting edges rather sharp to reduce the tendency to deflect the hair towards the tooth tips. More specifically, the lateral cutting edges of the cutting teeth may have a wedge-like configuration with a wedge angle of less than 60° or less than 50°, or in the range of 35°-60° or 45°-50°, when viewed in a cross section taken perpendicular to the longitudinal axis of the respective tooth.

[0054] In order to avoid pushing back hair at the tooth tips and lateral cutting edges, the sum of the aforementioned tip angle (between the chamfered tip surface and the cutting surface between the cutting blades) and the wedge angle of the lateral cutting edges may be less than 110°, or may be in the range of 60° to 110° or 90° to 110°.

[0055] The opening angle of the gap between two adjacent teeth, as defined by the lateral cutting edges of the adjacent teeth facing each other, may range from 10° to 30°, combining a smooth cut with retention of the hair within the gap. More specifically, the opening angle may range from 15° to 25°.

[0056] The opening angle may be selected differently for different wedge angles. For example, the larger the opening angle, the smaller the wedge angle. More specifically, the sum of the wedge angle and the opening angle may be less than 80°, or less than 75°, or less than 70°. Such a wedge angle configuration may be provided for the fixed blade and / or the movable blade, and is particularly advantageous for the movable blade to avoid the problem of kicking hair, which is mainly caused by the movable blade.

[0057] To further aid the cutting blade in initial contact and cutting the hair, the cutting teeth may have a tooth width that is significantly smaller at their tip portions. More specifically, the cutting teeth may have a tip width in the range of 1 / 6 to 2 / 3 or 1 / 6 to 1 / 3 of the rear width of the cutting teeth at the rear end of the transverse cutting edge, which may extend from the rear end to the tooth tip along a straight line. The tip width may be measured at the forward end of the tooth in the cutting plane defined between the fixed blade and the movable blade and along which the movable blade reciprocates relative to the fixed blade.

[0058] Basically, the tip width of the cutting teeth can be adjusted to the pitch of the comb tooth arrangement. More specifically, the tip width can be in the range of about 1 / 9 to 1 / 3 of the tooth pitch, i.e., the distance from tooth to tooth, more specifically, the distance from the center of a tooth to the center of the next tooth. For example, the cutting teeth can have a tip width in the range of 1 / 6 to 1 / 4 of the pitch.

[0059] As can be seen from Figures 1-3, the cutting device system 3 may be part of a cutting device head 2 which may be attached to a handle 10 of a razor and / or trimmer 1. More specifically, the razor and / or trimmer 1 may include an elongated handle 10 housing electronic and / or electrical components such as a control unit, an electric or magnetic drive motor 18, and a drive train 19 for transmitting drive motion of the motor 18 to the cutting device system 3 of the cutting device head 2; with reference to Figure 1, the cutting device head 2 may be located at one end of the elongated handle 10 (see Figures 1, 2 and 3).

[0060] The cutter system 3 including a pair of cooperating cutting blades 4 and 5 may be the only cutter system of the cutter head 2, as in the embodiment shown in Figure 1. Alternatively, the cutter system 3 may be incorporated into a razor head 2 having other cutter systems, such as shear foil cutters, as shown in Figure 12, e.g., the cutter system 3 having at least one row of cooperating cutting teeth 6, 7 may be disposed between a pair of shear foil cutters.

[0061] As shown in Figures 1 and 4, the cutting device system 3 may include elongated rows of cutting teeth 6 and 7 that can reciprocate relative to each other along a linear path to close the gaps between the teeth 6 and 7 and provide a cutting action by passing over each other. On the other hand, the cutting device system 3 may also include cutting teeth aligned along a circle and / or arranged radially. Such rotating cutting elements may have cutting teeth that project substantially radially, and the cutting elements may be driven to rotate relative to each other and / or to rotationally oscillate relative to each other. The cutting action is essentially similar to the reciprocating cutting elements as radially extending teeth, which when rotating and / or rotationally oscillating, periodically close and reopen the gaps between adjacent teeth and pass over each other like scissors.

[0062] As shown in Figures 3 and 4, the drive system may include a motor 18, the shaft of which can rotate an eccentric drive pin 28 received between a channel-like profile 21 of a drive 20, the eccentric drive pin being connected to one of the cutting blades 4 and providing a reciprocating motion due to engagement of the rotating eccentric drive pin with the profile of the drive (see Figure 4).

[0063] As shown in Figures 4-6, the cooperating cutting blades 4 and 5 can have an essentially at least approximately plate-like configuration, with each cutting blade 4 and 5 including at least one row of cutting teeth 6 and 7 (see Figure 4). The cutting blades 4 and 5 are supported and positioned such that the flat sides of the cutting blades lie on top of each other. More specifically, the cutting teeth 6 and 7 of the cutting blades 4 and 5 contact each other back to back, like the blades of a pair of scissors.

[0064] To support the cutting blades 4 and 5 in position relative to each other but still allow the teeth 6, 7 to move reciprocally relative to each other, the cutting blade 4 may be sandwiched between the other cutting blade 5 and a support structure which may include a frame-like or plate-like support.

[0065] More specifically, as can be seen from Figures 4 and 5, the cutting blades 4, 5 of the cutting device system 3 may each have a substantially plate-like configuration and / or may be arranged on top of each other such that the rows of cutting teeth 6, 7 are aligned with each other.

[0066] The cutting blade 5 may be a fixed cutting blade, but may still be supported on the handle 10 in a sort of self-adjusting manner to allow for adaptation to skin contours. For example, the fixed cutting blade 5 (and the movable cutting blade 4) may pivot and / or tilt relative to the handle 10. However, in the alternative, the fixed cutting blade 5 may be fixedly attached to the handle 10.

[0067] The movable cutting blade 4 is driven by a motor 18 via a drive train 19 (see FIG. 3) to reciprocate relative to the fixed cutting blade 5, thereby defining a cutting direction 25. For example, the movable cutting blade 4 may be connected to a transmitter 20, and a reciprocating or rotating drive pin may be received within a slotted receiver 21 (see FIG. 4).

[0068] The movable cutting blade 4 may be movably supported by a support structure 22 for movement relative to the fixed cutting blade 5 such that the teeth 6 of the movable cutting blade 4 reciprocate relative to the cutting teeth 7 of the fixed cutting blade 5, causing the cutting teeth 7 to repeatedly engage and disengage with one another. A spring mechanism 23 may bias the fixed cutting blade 4 onto the fixed cutting blade 5 to bias the cutting blades 4, 5 against one another, particularly in the region of the rows of cooperating cutting teeth 6, 7 (see Figures 4 and 5).

[0069] The fixed cutting blade 5 may define a skin contact surface 14 at the front end portion of the cutting device system 3, taking into account the forward direction 30 of the cutting device system 3. The contact surface 14 may be defined below and / or at the row of cutting teeth 6, 7, and the bottom of the cutting blade 5 facing away from the other cutting blade 4 may define the skin contact surface 14 (see FIG. 16). On the other hand, if a distance comb 15 is attached to the bottom of the fixed cutting blade 5, it is not the fixed cutting blade 5 itself but such distance comb 15 that defines the skin contact surface 14 of the cutting device system (see FIG. 15). More specifically, the surface of the distance comb 15 facing away from the cutting blades 4, 5 may define the skin contact surface 14 (see FIG. 15).

[0070] As can be seen from Figures 5, 6, 15 and 16, the front end portion 14f of the skin contact surface 14 at the front end portion of the cutting blade 5 may be inclined at an acute angle φ of, for example, 5°-10° with respect to the cutting surface 8 between the cutting blades 4, 5 and / or the bottom portion arranged further back, so that the skin contact surface 14 at the front end portion of the cutting device system 3 is in stable contact with the skin surface 24 when the cutting device system 3 is inclined forward with respect to the skin surface 24 such that the front end portion of the cutting device system 3 is inclined downwards towards the skin surface 24 (see Figure 6). Such an inclined position of the trimmer 1 (see Figures 6 and 7) is a natural use of the trimmer 1 by a user maneuvering the trimmer 1 in a forward direction 30 (see Figure 4) along the skin surface 24 to bring the comb-like cutting teeth 6, 7 close to the skin surface 24 and / or into the hair to be cut to achieve a close cut.

[0071] 5-8 and 16 show that the skin contact surface 14 may be formed by the bottom of the fixed cutting blade 5 itself. However, as mentioned above, the skin contact surface 14 may also be formed by the bottom of a distancing comb 15 which may be attached to the bottom of the fixed blade 5 (see FIG. 15). Also, such a skin contact surface 14 formed by such a distancing comb 15 may have a front end portion 14f inclined at an acute angle φ with respect to the cutting plane 8.

[0072] As can be seen from Fig. 15, the inclined front end portion 14f of the skin contact surface 14 does not have to be exactly flat, but may still be exactly flat, but may have a more or less slightly curved profile, such as a convex shape, e.g. a slight barrel or approximately cylindrical rounding towards the front end, to help the cutting device system slide smoothly along the skin. If the inclined front end portion of the skin contact surface 14 has a curved configuration, its tangent plane 33 (see Fig. 15) may be taken into account for the definition of the imaginary plane 27, as described below.

[0073] As can be seen from Figures 9-12, the cutting teeth 6, 7 of the movable cutting blade 4 each include a pair of transverse cutting edges 9 tapering towards the tooth tips 11, and the cutting teeth 6 may have a longitudinal tooth axis 17 extending substantially perpendicular to the reciprocating driving movement of the cutting blades 4, 5 relative to one another, as indicated by the double arrow 25 (see Figure 9a).

[0074] The transverse cutting edges 9 of the cutting teeth 6 may extend substantially parallel to a cutting plane 8 defined between the cutting blades 4, 5. Such cutting plane 8 may be a cutting surface, in which case the transverse cutting edges 9 may have a straight configuration. However, the cutting surface 8 may also have a non-planar, e.g., shovel-shaped configuration, in which case the transverse cutting edges have a curved configuration. The non-planar shovel-shaped configuration may have a curvature in a plane perpendicular to the reciprocating drive motion, and may have a linear or straight configuration in a direction parallel to the reciprocating motion or cutting direction 25.

[0075] As can be seen from Fig. 9b, the lateral cutting edges 9 of adjacent cutting teeth 6 facing each other can define an opening angle α, which indicates a kind of V-shaped configuration of the gap between adjacent cutting teeth 6. The width of such a gap between adjacent teeth 6 essentially increases from the bottom or root portion of the tooth 6 towards the tooth tip 11. In other words, the gap gets smaller the deeper you go into the gap (see Fig. 9b).

[0076] The opening angle α (see FIG. 9b) may be in the range of 10° to 30° or 20° to 25°. For example, an opening angle of 22° may be advantageous in that it achieves a smooth cut with a relatively small cutting force on the hand and avoids pushing the hair outwards, as explained above.

[0077] As can be seen from Fig. 12, the transverse cutting edges 9 may have a wedge-shaped configuration with a wedge angle γ when considering a cross-sectional view of the cutting teeth 6 in a plane perpendicular to the longitudinal tooth axis 17, as shown by line BB in Fig. 10 and Fig. 12. The wedge angle γ may be in the range of 35°-60°, or 40°-55°, or 45°-50°, for example a wedge angle of 48° may provide an advantageous cutting action.

[0078] Basically, the smaller the wedge angle γ, the easier it is for the cutting blade to penetrate the hair, and the chances that the hair will be cut immediately instead of being pushed out are significantly increased. A small wedge angle γ of the transverse cutting edge 9 also has the advantage of reducing the cutting forces, with respect to reducing the forces acting on the teeth during cutting. The thus reduced cutting forces allow the tooth tips 11 to be made smaller without sacrificing the necessary stability. In other words, the tooth tips can be made thinner, preventing the hair from being pushed out by the tooth tips.

[0079] As can be seen from Figures 9b and 11, the tooth tips 11 of the cutting teeth 6 of the movable cutting blade 4 can be provided with an essentially flat chamfered tip surface 12, the chamfered tip surface 12 having a tip angle β defined between the flat chamfered tip surface 12 and the cutting surface 8 and / or between the tip surface 12 and the longitudinal tooth axis 17 (see Figure 11), the tip angle β being in the range of 40°-80° or 40°-70° or 50°-70° or 45°-65°. For example, the tip angle β may be around 60° to avoid hairs being pushed back, but still provide the necessary stability.

[0080] More specifically, the chamfered flat tip surface 12 of the movable blade 4 may extend parallel to the cutting direction 25 of the movable cutting blade 4 and may be inclined with respect to the aforementioned imaginary plane 27 perpendicular to the inclined front end portion 14f of the skin contacting surface 14 at the bottom of the cutting device system (see Figs. 15 and 16). As previously mentioned, the inclined front end portion 14f of the skin contacting surface 14 may have a slightly convex or other curved surface configuration, i.e., a non-planar configuration. In such a non-planar case, a tangent plane 33 tangent to the inclined front end portion of the skin contacting surface 14 may be considered (see Fig. 15), and the imaginary plane 27 may extend perpendicular to such tangent plane. More generally, the inclined front end portion 14f of the skin contacting surface 14 is essentially the portion of the skin contacting surface 14 extending below and / or in the area of ​​the tooth tips 11 so as to contact the skin when the cutting device system is placed on the skin in a forwardly inclined orientation, as shown, for example, in Figs. 6 and 7.

[0081] Relative to the imaginary plane 27, the tip face 12 is inclined rearwardly at an acute angle ε toward the rear portion of the cutting tooth such that the tooth tip 11 contacts the imaginary plane 27 only at the cutting surface 8, while the more raised portion of the tip face 12 is inclined away from the imaginary plane 27 to form a substantially wedge-shaped gap 29 between the imaginary plane 27 and the tip face 12 (see Figures 15 and 16).

[0082] The acute angle ε of the inclination of the flat chamfered tip surface 12 with respect to the imaginary plane 27 may be in the range of 10° to 30° or 10° to 20° (see FIGS. 15 and 16). The angle ε may be less than 10°, for example, 3° or more, or 5° or more.

[0083] Such a range of acute angles ε may be particularly advantageous when the inclination angle φ of the inclined front end portion 14f of the skin contact surface 14 relative to the cutting surface 8 is in the range of 5°-25° or 10°-20°, but may also be provided for other ranges of inclination angles φ. The inclination angle φ allows for a reduction in the thickness of the teeth towards the tooth tip, which allows for a closer cutting action.

[0084] As can be seen from Fig. 6, the hair 26 may grow from the skin at an acute angle and therefore may not contact the reciprocating tooth tip 11 even when it is inclined towards the cutting device system 3. Typically, an oblique hair may grow from the skin at an acute angle of, for example, about 40°, so that when the cutting device system 3 is advanced against the inclined hair 26 as shown by Fig. 6, the hair 26 may collide with the tooth tip 11 as shown by Figs. 7 and 8, which show cutting device systems having cutting teeth with non-chamfered tooth tips. Such collision with non-chamfered tooth tips is likely to occur not only when the cutting device system 3 is inclined forward as shown by Fig. 7 in order to place the skin contact surface 14 completely on the skin surface, but also when the cutting device system 3 is used in a less steep position as shown by Fig. 8.

[0085] As a result, when the tooth tips 11 are provided with the flat, chamfered tip surfaces 12 described above, as shown in FIG. 6, the likelihood of hairs being pushed out of the engagement zone of the transverse cutting edges 9 is significantly reduced.

[0086] As shown in Fig. 15, the chamfered flat tip surface 12 helps to avoid pushing away hairs not only when the cutting device system 3 with the fixed cutting blade 5 is placed directly on the skin surface 24, but also when a so-called distance comb 15 is used. Such distance combs 15 are known per se and are used to adjust the cut length of the hairs. More specifically, if a beard of a certain or increased length is desired, the distance comb 15 may be attached to the bottom of the cutting device system 3 in such a way that the cooperating cutting teeth 6, 7 are held a certain distance away from the skin surface (see Fig. 15).

[0087] The distance comb 15 may also define a skin contact surface 14 of the cutting device system 3 having a front end portion 14f arranged at the front end portion of the cutting device system 3 and / or essentially in the row of cooperating cutting teeth 6, 7 when taking into account the forward movement direction 30 of the cutting device system 3, and the skin contact surface 14 defined by the distance comb 15 and / or its front end portion 14f may essentially have an orientation and / or inclination parallel to the skin contact surface 14 defined by the bottom of the fixed cutting blade 5 and its front end portion 14f.

[0088] Taking into account the skin contact surface 14 defined by the bottom of the fixed cutting blade 5 or defined by the distance comb 15, the tip surfaces 12 of the cutting teeth 6 of the movable cutting blade 4 may be inclined at an angle δ relative to the front end portions 14f of the skin contact surface 14 (see FIG. 15 ), and the angle δ may be in the range of 60° to 85° or 75° to 85° to ensure avoidance of dislodging hairs that get into the gaps between adjacent teeth 6.

[0089] As can be seen from FIG. 13, if the tip surface 12 is not exactly flat but is uneven in relief, the tip angle β and, correspondingly, the aforementioned angle δ relative to the skin contact surface 14 may be selected to be within the aforementioned ranges.

[0090] Such a non-uniform relief-like shape of the tip surface 12 may result from the manufacturing process and / or may be purposefully selected. For example, the tip surface 12 has a concave configuration (see right side of FIG. 13). More generally, the asperities may be geometrically regular or may have an irregular cloud-like configuration (see left side of FIG. 13).

[0091] If the distal end surface 12 exhibits some irregularity, the aforementioned angle of inclination ε of the distal end surface 12 relative to an imaginary plane 27 may be defined between the imaginary plane 27 and a plane 32 tangent to the distal end surface 12 (see FIG. 13). The same tangent plane 32 may also be used to define the aforementioned angle β when the distal end surface 12 is not planar.

[0092] With regard to the aforementioned wedge angle γ of the transverse cutting edge 9 (see FIG. 12), it should also be noted that only a part of the entire flank or side surface of the cutting tooth 6 may be adapted to the wedge angle γ. More specifically, only the edge portion forming the cutting edge 9 facing the cooperating tooth of the cooperating cutting blade 5 and / or the outermost edge portion directly adjacent to the cutting surface 8 may define the aforementioned wedge angle γ, while the flank portion of the tooth 6 further away from the cutting surface 8 and / or further away from the cutting edge 9 may have a steeper configuration (see FIG. 14). To achieve a sharp cutting edge and a smooth cutting action with low cutting forces, it is sufficient if the outermost edge portion of the transverse cutting edge 9 is configured to have the aforementioned wedge angle γ.

[0093] As can be seen in Figures 9b, 9c and 10, the flat chamfered tip surface 12 may be substantially planar with an angular, raised transition 13 to each of the transverse cutting edges 9, the angular transition 13 may have a radius of curvature of less than 50 µm, or less than 25 µm, or less than 10 µm.

[0094] As can be seen from figure 10, the tooth tip 11 defines a pyramidal profile with three inclined flat surfaces joining one another, one of which is formed by a flat chamfered tip surface 12, and the other two inclined flat surfaces are formed by the lateral cutting edges 9 of the cutting tooth joining the tip surface 12. The tooth tip profile is of course not a true complete pyramid, since it only has three flat inclined surfaces and lacks a fourth side of the pyramid, and furthermore does not have a rectangular base, but it nevertheless resembles a portion of a pyramid with three flat sides inclined relative to each other and inclined relative to the base.

[0095] The flat beveled tip surface 12 may define a tip width tw in the range of 150 μm to 400 μm or 200 μm to 300 μm (see FIG. 10).

[0096] Considering the rear end 9r of the cutting edge 9, the cutting edge 9 may have a substantially linear straight shape tapering towards the tooth tip. The width tw of the tooth 6 at the tooth tip 11 may be in the range of 1 / 6 to 2 / 3 or 1 / 6 to 1 / 3 of the rear width tr of the cutting tooth 6 at the rear end 9r of the transverse cutting edge 9 (see FIG. 10).

[0097] The tip width tw may be adjusted to the pitch 31 of the blade teeth, where such pitch 31 is the distance from the center of a tooth to the center of an adjacent tooth (see FIG. 10). Considering such pitch 31, the tip width tw may be in the range of 1 / 9 to 1 / 3 or 1 / 6 to 1 / 4 of the pitch 31.

[0098] Dimensions and values ​​disclosed herein should not be understood as being strictly limited to the exact numerical values ​​recited. Instead, unless otherwise indicated, each such dimension is intended to mean both the recited value and a functionally equivalent range surrounding that value. For example, a dimension disclosed as "40 mm" is intended to mean "about 40 mm."

Claims

1. A cutting device system for an electric shaver and / or trimmer (1), comprising a pair of cooperating cutting blades (4, 5) each having at least one row of comb-like cutting teeth (6, 7), one of said cutting blades (5) being a fixed cutting blade (5) and the other of said cutting blades (4) being a movable cutting blade (4) movable relative to said fixed cutting blade in a cutting direction (25) along a cutting surface (8) defined between said cooperating cutting blades (4, 5), each of said cutting teeth (6, 7) having a pair of transverse cutting edges (9) tapering towards a tooth tip (11), said tooth tip (11) of at least said movable cutting blade (4) comprising a flat chamfered leading surface (12), a skin contact surface (14) of said cutting device system guiding said cutting blades (4, 5) on a user's skin in the area of ​​said tooth tips (11) and said cutting surface (12) being movable relative to said fixed cutting blade in a cutting direction (25) along a cutting surface (8) defined between said cooperating cutting blades (4, 5), 8), said skin contact surface (14) is defined by a surface of said fixed cutting blade (5) facing away from said movable cutting blade (4) or by a distance comb (15) attached to said fixed cutting blade (5), said flat chamfered tip surface (12) is inclined at an acute angle (ε) to an imaginary plane (27), said imaginary plane (27) extending parallel to said cutting direction (25) and perpendicular to said skin contact surface (14) and / or a tangent plane (33) tangent thereto, such that teeth tips (11) contact said imaginary plane (27) only at a cutting surface (8) having a substantially wedge-shaped gap (29) between said flat chamfered tip surface (12) and said imaginary plane (27).

2. 2. The cutting device system of claim 1, wherein the acute angle (ε) of inclination of the flat chamfered tip surface (12) relative to the imaginary plane (27) is in the range of 10° to 40° or 10° to 20°.

3. 3. The cutting device system according to claim 1 or 2, wherein the teeth (11) of the moving cutting blade (4) define, in a cross-sectional plane parallel to the cutting surface (8), a linear contour parallel to the cutting direction (25).

4. 4. The cutting device system according to claim 1, wherein the cutting teeth (6, 7) of the movable cutting blade (4) define at the tip (11) a pyramidal profile having three mutually joining inclined flat surfaces, one of which is formed by the flat chamfered tip surface (12) and the other two inclined flat surfaces are formed by the transverse cutting edges (9) of the cutting teeth (6, 7).

5. 5. The cutting device system of claim 1, wherein the flat chamfered tip surface (12) is substantially planar with an angular transition (13) to each of the transverse cutting edges (9), the angular transition (13) having a radius of curvature of less than 50 μm, less than 25 μm, or less than 10 μm.

6. 6. A cutting device system according to any one of claims 1 to 5, wherein the cutting teeth (6, 7) have a tip width (tw) at the rear end of the transverse cutting edge (9) in the range of 1 / 6 to 2 / 3 or 1 / 6 to 1 / 3 of the rear width (tr) of the cutting tooth (6, 7), the transverse cutting edge (9) extending along a straight line from the rear end to the tooth tip.

7. 7. The cutting device system according to claim 1, wherein the cutting teeth (6, 7) have a tip width (tw) in the range of 1 / 9 to 1 / 3 or 1 / 6 to 1 / 4 of a tooth pitch (31), which is the distance from the center of a tooth to the center of the next tooth.

8. 8. A cutting device system according to any one of claims 1 to 7, wherein the acute angle (φ) of the inclined front end portion of the skin contact surface (14) relative to the cutting surface (8) is in the range of 5° to 25° or 10° to 20°, and the acute angle (ε) of the flat chamfered tip surface (12) relative to the imaginary plane (27) is in the range of 10° to 30° or 10° to 20°.

9. 9. The cutting device system according to any one of claims 1 to 8, wherein an included angle (β) between the flat chamfered leading surface (12) and the cutting surface (8) is in the range of 30° to 70° or 50° to 65°.

10. 10. The cutting device system according to any one of claims 1 to 9, wherein the flat chamfered tip surface (12) of the cutting tooth (6) of the movable cutting blade (4) is inclined relative to the front end portion (14f) of the skin contact surface (14) at an angle (δ) in the range of 50° to 85°, or 65° to 85°, or 75° to 85°.

11. A cutting device system according to any one of claims 1 to 10, wherein the flat bevelled tip surface (12) defines a maximum tip width (16) in the range of 150 μm to 400 μm or 200 μm to 300 μm.

12. 12. The cutting device system according to any one of claims 1 to 11, wherein the transverse cutting edges (9), when considered in a cross section transverse to the longitudinal tooth axis (17) of the respective cutting tooth (6), have a wedge-shaped configuration with a wedge angle (γ) in the range of 35° to 60°, or 40° to 55°, or 45° to 50°.

13. 13. The cutting device system according to any one of claims 1 to 12, wherein the sum of the tip angle (β) and the wedge angle (γ) is less than 120° or less than 110° and / or is in the range of 90° to 120° or 100° to 110°.

14. 14. The cutting device system according to any one of claims 1 to 13, wherein an opening angle (α) defined by a pair of cutting edges (9) of adjacent cutting teeth (6) facing each other is in the range of 10° to 30°, or 15° to 25°, or 20° to 25°.

15. 15. The cutting device system according to any one of claims 1 to 14, wherein the sum of the wedge angle (γ) and the opening angle (α) is less than 80° or less than 75° and / or is in the range of 60° to 80° or 65° to 75°.

16. 16. The cutting device system according to any one of claims 1 to 15, wherein the sum of the tip angle (β), the wedge angle (γ) and the opening angle (α) is less than 150° or less than 140°, and / or is in the range of 110° to 150° or 120° to 140°.

17. An electric shaver and / or trimmer comprising a cutting device system (3) constructed according to any one of claims 1 to 16.

18. A cutting device system for an electric shaver and / or trimmer (1), comprising a pair of cooperating cutting blades (4, 5) each having at least one row of comb-like cutting teeth (6, 7), one of said cutting blades (5) being a fixed cutting blade (5) and the other of said cutting blades (4) being a movable cutting blade (4) movable relative to said fixed cutting blade in a cutting direction (25) along a cutting plane (8) defined between said cooperating cutting blades (4, 5), each of said cutting teeth (6, 7) having a pair of transverse cutting edges (9) tapering towards a tooth tip (11), said tooth tip (11) of at least said movable cutting blade (4) having a flat chamfered leading surface (12). wherein the flat chamfered tip surface extends to the cutting surface of the cutting tooth with a tip angle (β) in the range of 30° to 70° or 50° to 65° between the flat chamfered tip surface (12) and the cutting surface (8), and when considering a cross-section transverse to the longitudinal tooth axis (17) of each cutting tooth (6), the transverse cutting edges (9) have a wedge-shaped configuration with a wedge angle (γ) in the range of 35° to 60°, or 40° to 55°, or 45° to 50°, and the sum of the tip angle (β) and the wedge angle (γ) is less than 120° or less than 110° and / or in the range of 90° to 120° or 100° to 110°.

19. a) the tips (11) of the movable cutting edge (4) define, in a cross-sectional plane parallel to the cutting surface (8), a linear contour parallel to the cutting direction (25); and / or b) the cutting teeth (6, 7) of the moving cutting blade (4) define at the tip (11) a pyramidal profile having three mutually joining inclined flat surfaces, one of which is formed by the flat chamfered tip surface (12) and the other two inclined flat surfaces are formed by the transverse cutting edges (9) of the cutting teeth (6, 7); and / or c) said flat chamfered tip surface (12) is substantially planar with an angular transition (13) to each of said transverse cutting edges (9), said angular transition (13) having a radius of curvature of less than 50 μm, less than 25 μm, or less than 10 μm; and / or d) the cutting tooth (6, 7) has a tip width (tw) at the rear end of the transverse cutting edge (9) in the range of 1 / 6 to 2 / 3 or 1 / 6 to 1 / 3 of the rear width (tr) of the cutting tooth (6, 7), the transverse cutting edge (9) extending along a straight line from the rear end to the tooth tip; and / or e) a cutting device system according to any one of claims 1 to 18, in which the cutting teeth (6, 7) have a tip width (tw) in the range of 1 / 9 to 1 / 3 or 1 / 6 to 1 / 4 of the tooth pitch (31), which is the distance from the centre of a tooth to the centre of the next tooth; and / or f) the flat bevelled tip surface (12) of the cutting tooth (6) of the movable cutting blade (4) is inclined with respect to the front end portion (14f) of the skin contact surface (14) at an angle (δ) in the range of 50° to 85°, or 65° to 85°, or 75° to 85°; and / or g) said flat bevelled tip surface (12) defines a maximum tip width (16) in the range of 150 μm to 400 μm or 200 μm to 300 μm; and / or h) the opening angle (α) defined by the pair of cutting edges (9) of adjacent cutting teeth (6) facing each other is in the range of 10° to 30°, or 15° to 25°, or 20° to 25°; and / or i) the sum of the wedge angle (γ) and the opening angle (α) is less than 80° or less than 75°, and / or is in the range of 60° to 80° or 65° to 75°; and / or j) the sum of the tip angle (β), the wedge angle (γ) and the opening angle (α) is less than 150° or less than 140°, and / or is in the range of 110° to 150° or 120° to 140°; and / or k) The cutting device system of claim 18, wherein the cutting device system is part of an electric shaver and / or a trimmer, and optionally further comprises at least one of the features above configured according to any one of claims 1 to 18.

Images