Electric shaver with rotatable outer cutting member with v-shaped hair access opening

Abstract

An electric shaver (1) comprises at least one hair cutting unit (9a, 9b, 9c) having a central axis (11), an outer cutting member (13) with a hair inlet opening (61), and an inner cutting member (15). The inner and outer cutting members rotate about the central axis in a first rotational direction (R1) at a first rotational speed ([omega] 1) and in a second rotational direction (R2) opposite the first rotational direction at a second rotational speed ([omega] 2) lower than the first rotational speed, respectively. The hair entry opening comprises a V-shaped opening portion (63) pointing in a direction opposite the second direction of rotation (R2). A tangential speed (VT) of the outer cutting member with respect to the central axis (11) measured at a position radial to a central base point (65) of the V-shaped opening portion is in a range of 7.5 cm / s to 50 cm / s.

Description

Technical Field

[0001] The present invention relates to an electric shaver, comprising:

[0002] - at least one hair cutting unit having a central axis, an outer cutting member having a hair entry opening arranged in an annular shaving area, the annular shaving area being arranged concentrically around the central axis, and an inner cutting member covered by the outer cutting member and having an annular array of cutting elements arranged concentrically around the central axis; and

[0003] - a drive system, which is configured to: rotate the inner cutting member of each hair cutting unit in a first rotational direction around the central axis of the hair cutting unit at a first rotational speed, and rotate the outer cutting member of each hair cutting unit in a second rotational direction around the central axis of the hair cutting unit at a second rotational speed, the second rotational direction being opposite to the first rotational direction, and the second rotational speed being lower than the first rotational speed. Background Art

[0004] As is well known, an electric shaver comprises at least one hair cutting unit with a central axis, an outer cutting member and an inner cutting member, the outer cutting member having a hair entry opening arranged in an annular shaving area, the annular shaving area being concentrically arranged around the central axis, the inner cutting member being covered by the outer cutting member, and having an annular array of cutting elements concentrically arranged around the central axis, and the electric shaver also comprises a drive system, the drive system being configured to rotate the inner cutting member of each hair cutting unit around the central axis of the hair cutting unit relative to the outer cutting member. Such an electric shaver generally comprises a shaving unit, wherein two or more such hair cutting units are supported by a supporting structure of the shaving unit. The electric shaver generally comprises a main housing for accommodating an electric motor. The shaving unit can be permanently or releasably coupled to the main housing. When the shaving unit is coupled to the main housing, the motor is coupled to the inner cutting member of the hair cutting unit via a transmission system, thereby allowing the motor to rotate the inner cutting member relative to the outer cutting member. During rotation of the inner cutting member, hair penetrates into the outer cutting member via its hair entry opening and is cut by the interaction of the cutting edge provided on the cutting element of the rotating inner cutting member and the counter-cutting edge provided at the hair entry opening of the outer cutting member.

[0005] An important characteristic of the hair cutting unit of such an electric shaver is the hair capture efficiency, i.e., the degree to which hair can penetrate into the hair entry opening of the outer cutting member when the electric shaver is moved on the user's skin (the annular shaving area of ​​the outer cutting member is in contact with the skin). High hair capture efficiency is desirable because it can reduce the time consumed by the shaving process required to achieve the desired shaving result (e.g., in terms of the average remaining hair length after the shaving process). The higher the hair capture efficiency, the better the hair can penetrate into the hair entry opening of the outer cutting member and be cut by the hair cutting unit, e.g., during a single movement stroke of the electric shaver on a specific area of ​​the skin, and the smaller the average remaining hair length obtained after the shaving process. In order to improve the hair capture efficiency, it has been proposed that the outer cutting member of the hair cutting unit is also driven to rotate around the central axis of the hair cutting unit. In particular, for this purpose, it has been proposed to rotate the outer cutting member in a rotation direction opposite to the rotation direction of the inner cutting member at a rotation speed (number of revolutions per unit time) significantly lower than that of the inner cutting member. To this end, known electric shavers have a drive system configured to rotate the inner cutting member of each hair cutting unit at a first rotational speed around the central axis of the hair cutting unit in a first rotational direction, and to rotate the outer cutting member of each hair cutting unit at a second rotational speed around the central axis of the hair cutting unit in a second rotational direction, the second rotational direction being opposite to the first rotational direction and the second rotational speed being lower than the first rotational speed. Examples of these known electric shavers are disclosed in the following prior art.

[0006] US2,283,834 discloses an electric shaver, including a hair cutting unit, the hair cutting unit having an outer cutting member, the outer cutting member being provided with a slit-shaped hair entry opening extending substantially radially relative to the central axis of the hair cutting unit. The hair cutting unit has an inner cutting member, which rotates at a relatively high speed (e.g., 6,000 rpm to 15,000 rpm). The outer cutting member rotates in a direction opposite to the direction of rotation of the inner cutting member at a significantly lower speed within the range of 40 rpm to 120 rpm, preferably at about 80 rpm. According to the patent, the relatively slow and continuous rotation of the outer cutting member enables the tilted hairs growing in all directions to be better and more regularly captured in the slit-shaped hair entry opening compared to the situation that may be achieved by means of a circular manual movement of a shaver with a fixed outer cutting member.

[0007] US10,195,751B2 discloses an electric shaver, comprising a shaving unit with three hair cutting units. Each hair cutting unit has an inner cutting member and an outer cutting member, respectively, and the outer cutting member is provided with a slit-shaped hair entry opening, a circular hair entry opening or a hair entry opening with a circular and slit-shaped combination shape extending radially relative to the central axis of the hair cutting unit. The inner cutting member and the outer cutting member of each hair cutting unit are rotatably driven in opposite directions around the central axis of the hair cutting unit. According to the patent, by improving the action of the user to lift and catch hair, the rotation of the outer cutting member achieves a better favorable effect for skin feeling. In one example, the shaver has a gear transmission mechanism, which is configured to convert a motor rotation speed of 8,000 rpm into a rotation speed of the outer cutting member of about 10 rpm.

[0008] US6,901,662B1 discloses an electric shaver, comprising a shaving unit with three hair cutting units. Each hair cutting unit has an inner cutting member and an outer cutting member, respectively, and the outer cutting member is provided with a hair entry opening in the form of a slot or a perforation. The inner cutting member and the outer cutting member of each hair cutting unit rotate in opposite directions around the central axis of the hair cutting unit. In addition, the three hair cutting units are mounted on a common support frame, which rotates relative to the fixed shaver body around the central axis of the shaving unit. According to the patent, the combination of the rotation of the outer cutting member around the central axis of the hair cutting unit and the rotation of the hair cutting unit around the central axis of the shaving unit forces all hair ends to stand upright and enter the slot or the perforation of the outer cutting member. The rotation speed of the outer cutting member is approximately twice the rotation speed of the common support frame on which the hair cutting unit is mounted. In particular, the rotation speed of the outer cutting member is in the range of 2 rev / sec to 10 rev / sec (120 rpm to 600 rpm), and the rotation speed of the common support frame is in the range of 1 rev / sec to 5 rev / sec (60 rpm to 300 rpm). However, the combination of the rotation of the inner and outer cutting members around the central axis of the hair cutting unit and the rotation of the hair cutting unit around the central axis of the shaving unit requires a complex and bulky drive system. Summary of the invention

[0009] An object of the present invention is to provide an electric shaver as described in the previous "Field of the Invention" section, which has a significantly improved hair capture efficiency compared to the electric shavers known from at least the aforementioned US2,283,834 and US10,195,751, but does not require an additional rotational movement of the hair cutting unit around the central axis of the shaving unit as proposed in the aforementioned US6,901,662B1.

[0010] In order to achieve the above object, the present invention provides an electric shaver, comprising:

[0011] - at least one hair cutting unit having a central axis, an outer cutting member having a hair entry opening arranged in an annular shaving area, the annular shaving area being arranged concentrically around the central axis, and an inner cutting member covered by the outer cutting member and having an annular array of cutting elements arranged concentrically around the central axis; and

[0012] a drive system configured to rotate the inner cutting member of each hair cutting unit in a first rotational direction around a central axis of the hair cutting unit at a first rotational speed, and to rotate the outer cutting member of each hair cutting unit in a second rotational direction around the central axis of the hair cutting unit at a second rotational speed, the second rotational direction being opposite to the first rotational direction and the second rotational speed being lower than the first rotational speed;

[0013] in:

[0014] - the hair entry opening of the outer cutting member of each hair cutting unit comprises a V-shaped opening portion pointing in the first rotational direction of the inner cutting member; and

[0015] - The second rotation speed of the outer cutting member of each hair cutting unit is such that a tangential speed of the outer cutting member relative to the central axis measured at a radial position of a central base point of the V-shaped opening portion relative to the central axis is in the range of 7.5 cm / s to 50 cm / s.

[0016] Therefore, in electric shaver according to the present invention, the inner cutting member and outer cutting member of each hair cutting unit are driven by a drive system to rotate in opposite directions around the central axis of the hair cutting unit, wherein the second rotational speed (in revolutions per unit time) of the outer cutting member is lower than the first rotational speed (in revolutions per unit time) of the inner cutting member. In particular, according to the present invention, the hair entry opening of the outer cutting member comprises a V-shaped opening portion, which points to the first rotational direction of the inner cutting member, i.e., points to the direction opposite to the second rotational direction of the outer cutting member. In addition, the second rotational speed of the outer cutting member makes the tangential speed of the outer cutting member measured at the radial position of the central base point of the V-shaped opening portion relative to the central axis in the range of 7.5cm / s to 50cm / s. For the V-shaped opening portion, the term "central base point" refers to the point where the two legs of the V-shaped opening portion are connected to each other.

[0017] Experiments conducted by the inventors of the present invention have confirmed that, for a prior art hair cutting unit having an outer cutting member and having a straight groove-shaped hair entry opening extending approximately in a radial direction relative to the central axis of the hair cutting unit, by rotating the outer cutting member in a direction opposite to the rotation direction of the inner cutting member, the hair capture efficiency is improved, thereby achieving a reduction in the average remaining hair length after the shaving process. However, it was found that the improvement in hair capture efficiency and the final reduction in the average remaining hair length were relatively small and even not perceptible by the user. The experiments also proved that, for a hair cutting unit having an outer cutting member and having a hair entry opening with a V-shaped opening portion pointing to a first rotation direction of the inner cutting member, by rotating the outer cutting member at a second rotation speed in a direction opposite to the rotation direction of the inner cutting member, so that the tangential speed of the outer cutting member relative to the central axis is in the range of 7.5 cm / s to 50 cm / s, the hair capture efficiency is greatly improved, thereby achieving a very obvious and user-perceivable reduction in the average remaining hair length after the shaving process. In particular and surprisingly, it was found that the electric shaver according to the present invention is significantly superior to an electric shaver having an outer cutting member with radially extending straight hair entry openings in terms of the relative improvement in hair capture efficiency and the relative reduction in the average remaining hair length caused by the rotation of the outer cutting member, i.e. relative to the hair capture efficiency and the average remaining hair length achieved by a fixed outer cutting member.

[0018] In one embodiment of the electric shaver according to the present invention, the second rotation speed of the outer cutting member of each hair cutting unit is such that the tangential speed of the outer cutting member relative to the central axis is in the range of 11.25 cm / s to 30.0 cm / s. In this embodiment, a significant improvement in hair capture efficiency as described above is achieved while minimizing the additional skin friction caused by the rotation of the outer cutting member, and thereby achieving a significant and user-perceivable reduction in the average remaining hair length after the shaving process.

[0019] In another embodiment of the electric shaver according to the present invention, the hair entry opening of the outer cutting member of each hair cutting unit further comprises a radially inner straight opening portion and a radially outer straight opening portion, the radially inner straight opening portion being connected to the V-shaped opening portion at a first end of the V-shaped opening portion facing the central axis of the hair cutting unit, the radially outer straight opening portion being connected to the V-shaped opening portion at a second end of the V-shaped opening portion facing away from the central axis of the hair cutting unit, the radially inner straight opening portion and the radially outer straight opening portion each having a main extension direction in a radial direction relative to the central axis of the hair cutting unit. In this embodiment, the radially inner straight opening portion and the radially outer straight opening portion of the hair entry opening provide a higher hair capture efficiency for hair approaching the hair entry opening of the outer cutting member via the inner peripheral area of ​​the annular shaving area and the outer peripheral area of ​​the annular shaving area, respectively. The V-shaped opening portion of the hair entry opening provides a higher hair capture efficiency for hair approaching the hair entry opening via the central area of ​​the annular shaving area.

[0020] In one embodiment of the electric shaver according to the present invention, a particularly significant improvement in hair capturing efficiency is achieved, wherein the hair entry opening extends a first radial distance in a radial direction relative to the center axis of the hair cutting unit, and the V-shaped opening part of the hair entry opening extends a second radial distance in the radial direction, and the second radial distance is at least 50% of the first radial distance.

[0021] In a preferred embodiment of the electric shaver according to the invention, the V-angle of the V-shaped opening portion of the hair entry opening is in the range of 60° to 135°. In this embodiment, for the V-shaped opening portion, the V-angle is defined as the angle enclosed by the two legs of the V-shaped opening portion. The V-angle in the range of 60° to 135° provides a stretching effect on the skin in two mutually separated directions, which reduces the bulging of the skin into the hair entry opening and, in turn, reduces the skin irritation caused by the shaving process.

[0022] In another embodiment of the electric shaver according to the present invention, the cutting element of the inner cutting member of each hair cutting unit comprises a cutting edge, and the cutting edge has a V-shaped cutting edge portion pointing to the second rotation direction of the outer cutting member, and the V-shaped cutting edge portion and the V-shaped opening portion of the hair entry opening of the outer cutting member are aligned in the tangential direction relative to the central axis of the hair cutting unit. Therefore, in this embodiment, the V-shaped opening portion of the hair entry opening of the outer cutting member and the V-shaped cutting edge portion of the cutting element of the inner cutting member point to directions opposite to each other. In this embodiment, the skin irritation caused by the shaving process is further reduced, because: due to the interaction of the V-shaped opening portion of the hair entry opening of the outer cutting member and the V-shaped cutting edge portion of the cutting element of the inner cutting member, the hair captured by the hair entry opening is mainly cut in the central area of ​​the V-shaped opening portion, and in this central area, the degree of skin arching to the hair entry opening is at a minimum level. It should be noted that in this embodiment of the electric shaver according to the invention, the benefits of the invention in terms of improved hair capture efficiency are effectively combined with the benefits of improved shaving comfort (i.e. the reduced skin irritation provided by the shaving unit known from WO 2013 / 104965 A1 of the present applicant). However, the invention also covers embodiments in which the cutting edges of the cutting elements have a more conventional shape, such as a substantially straight shape or a slightly curved shape, each cutting edge having a main extension direction in the radial direction.

[0023] Because as long as the first rotation speed is within the normal range applied to rotary electric shavers, the influence of the first rotation speed of the inner cutting member on the hair capturing efficiency of the hair cutting unit will be limited, the first rotation speed of the inner cutting member of each hair cutting unit of the electric shaver according to the present invention can be such that the tangential speed of the inner cutting member relative to the central axis measured at a radial distance from the central axis is in the range of 70 cm / s to 375 cm / s, more preferably in the range of 140 cm / s to 250 cm / s, wherein the radial distance is equal to the radial distance of the radial position of the center base point of the V-shaped opening part from the central axis.

[0024] In one embodiment of the electric shaver according to the present invention, the drive system includes a single motor, which is configured and arranged to rotate the inner cutting member of each hair cutting unit and the outer cutting member of each hair cutting unit around the central axis of each hair cutting unit via a transmission system. The structure of the electric shaver can be simplified by using a single motor. The motor can be arranged in the main housing of the shaver, at least one hair cutting unit can be arranged in the shaving unit, the shaving unit is connected to the shaver of the main housing, and the transmission system can be partially arranged in the main housing and partially arranged in the shaving unit. As an alternative to a single motor, the drive system can have a first motor and a second motor, the first motor is used to rotate the inner cutting member of each hair cutting unit, and the second motor is used to rotate the outer cutting member of each hair cutting unit independently of the rotation of the inner cutting member. In this alternative embodiment, the electric shaver can, for example, have a user input member, by means of which the user can select the second rotation speed of the outer cutting member in a manner independent of the first rotation speed of the inner cutting member, or turn on or off the rotation of the outer cutting member in a manner independent of the rotation of the inner cutting member.

[0025] The above and other aspects of the invention will become apparent and elucidated with reference to the following detailed description of embodiments of an electric shaver according to the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The present invention will be explained in more detail below with reference to the accompanying drawings, in which the same or similar features are indicated by the same reference numerals, and in which:

[0027] Figure 1 Schematically shows an electric shaver according to the present invention;

[0028] Figure 2 is along Figure 1 A schematic cross-sectional view of the hair cutting unit of the electric shaver taken along line II-II in FIG.

[0029] Figure 3 Schematically shows Figure 1 A driving system for an electric shaver;

[0030] Figure 4a is Figure 1 A top view of a shaving unit of an electric shaver;

[0031] Figure 4b shows Figure 3 Part of the drive system;

[0032] Figure 5 yes Figure 2 A top view of an outer cutting member of a hair cutting unit;

[0033] 6a and 6b show an outer cutting member with a straight hair entry opening and an outer cutting member with a rotation speed varying with the outer cutting member. Figure 5 A graph of the hair capture efficiency of the outer cutting member;

[0034] 7a and 7b show shaving efficiency diagrams of a hair cutting unit having an outer cutting member with straight hair entry openings and a hair cutting unit having an outer cutting member with straight hair entry openings. Figure 2 A hair cutting unit, wherein the shaving efficiency varies with the rotation speed of the outer cutting member of the hair cutting unit; and

[0035] Figure 8 Shows Figure 2 The inner cutting member of the hair cutting unit. DETAILED DESCRIPTION

[0036] Figure 1 An embodiment of an electric shaver 1 according to the invention is schematically shown. The electric shaver 1 comprises a main housing 3, which is designed to be held by a user's hand during operation. The shaving device 1 also comprises a shaving unit 5 coupled to the main housing 3. The shaving unit 5 comprises a support structure 7 and three hair cutting units 9a, 9b, 9c supported by the support structure 7. The support structure 7 may comprise Figure 1 The shaving unit 5 is releasably connected to the main housing 3 by means of a coupling structure not shown in the drawing, which coupling structure is of a type known to those skilled in the art. Alternatively, the shaving unit 5 may be permanently connected to the main housing 3. It should be noted that the shaving unit of the electric shaver according to the present invention may include different numbers of hair cutting units, such as one, two or more than three hair cutting units. It should also be noted that Figure 1 The general layout of the electric shaver is shown only in a schematic manner and is not intended to limit the scope of the invention to the specific detailed design of the electric shaver shown. For example, the present invention also covers an embodiment of the electric shaver in which the shaving unit is coupled to the main housing via a relatively narrow, centrally arranged coupling structure, wherein there is an open space around the coupling structure between the shaving unit and the main housing, as is known in the art.

[0037] Figure 2 is along Figure 1 Schematic diagram of the cross section of the hair cutting unit 9c taken along the line II-II in FIG. The hair cutting units 9a and 9b are similar to the hair cutting unit 9c. The hair cutting unit 9c comprises a central axis 11, an outer cutting member 13 and an inner cutting member 15. The outer cutting member 13 has an annular shaving area 17 arranged concentrically around the central axis 11. The annular shaving area 17 is arranged to contact the skin of the user of the electric shaver 1 and comprises a hair entry opening ( Figure 2The inner cutting member 15 is covered by the outer cutting member 13 and has an annular array of cutting elements 21 arranged concentrically around the central axis 11. The electric shaver 1 includes a drive system (described in detail below) configured to rotate the inner cutting member 15 and the outer cutting member 13 relative to each other around the central axis 11 during operation of the electric shaver 1. Due to the mutual rotation of the inner cutting member 15 and the outer cutting member 13, hair on the user's skin that penetrates the hair entry opening in the annular shaving area 17 is cut by the interaction of the cutting edge 23 on the cutting element 21 of the inner cutting member 15 and the counter-cutting edge 25 on the bridge portion 19 of the outer cutting member 13. It should be noted that the electric shaver according to the present invention can have two or more annular shaving areas arranged concentrically around the central axis, as is known in the art.

[0038] The driving system of the electric shaver 1 mentioned above is Figure 3 It is schematically shown in FIG. 1 and is indicated by reference numeral 27. Figure 3 In the illustrated embodiment, the drive system 27 comprises a single motor 29 arranged in the main housing 3. According to the present invention, the drive system 27 is configured to cause the inner cutting member 15 of each hair cutting unit 9a, 9b, 9c to rotate at a first rotation speed ω1 around the central axis 11 of the hair cutting unit 9a, 9b, 9c in a first rotation direction R1 (in Figure 2 ) and rotate the outer cutting member 13 of each hair cutting unit 9a, 9b, 9c at a second rotation speed ω2 around the central axis 11 of the hair cutting unit 9a, 9b, 9c in a second rotation direction R2 (in Figure 2 The second rotation direction is opposite to the first rotation direction R1, and the second rotation speed ω2 is lower than the first rotation speed ω1. To this end, the drive system 27 includes a transmission system 31, through which the motor 29 can rotate the inner cutting member 15 and the outer cutting member 13 of each hair cutting unit 9a, 9b, 9c, wherein the transmission system 31 is partially arranged in the main housing 3 and partially arranged in the shaving unit 5. It should be noted that for simplicity, Figure 3 Only one of the hair cutting units 9c is shown in detail. It will be explained below how the drive system 27 drives the other hair cutting units 9a, 9b. It should also be noted that for simplicity, Figure 3 The support structure 7 of the shaving unit 5 is only partially shown.

[0039] like Figure 3As shown, the transmission system 31 includes a first main gear 33 and a second main gear 35, each of which is mounted on a motor shaft 37 of the motor 29. The transmission system 31 also includes three sub-gears 39, which are respectively mounted on three driving spindles 41, which are respectively connected to the three inner cutting members 15 of the hair cutting units 9a, 9b, 9c, and are rotatably journaled relative to the support structure 7 of the shaving unit 5. The three sub-gears 39 are respectively meshed with the first main gear 33. It should be noted that Figure 3 Only one pinion gear 39 and one drive spindle 41 coupled to the inner cutting member 15 of the hair cutting unit 9c are shown, the pinions gears and drive spindles associated with the inner cutting members 15 of the hair cutting units 9a and 9b being arranged in a corresponding manner.

[0040] The transmission system 31 further includes a secondary shaft 43 arranged parallel to the motor shaft 37. The upper portion of the secondary shaft 43 is arranged between the two secondary gears 39, but the arrangement Figure 3 4. The secondary shaft 43 carries a third main gear 45 and a fourth main gear 49, the third main gear 45 meshing with the second main gear 35 via a plurality of intermediate gears 47. The transmission system 31 further comprises a third shaft 51, which is arranged in a straight line with the motor shaft 37 and is rotatably journalled relative to the support structure 7 of the shaving unit 5. The third shaft 51 carries a fifth main gear 53 and a sixth main gear 55, the fifth main gear 53 meshing with the fourth main gear 49. The outer cutting members 13 of the hair cutting units 9a, 9b, 9c respectively comprise a secondary gear 57 meshing with the sixth main gear 55, the sixth main gear 55 being arranged centrally between the secondary gears 57 of the outer cutting members 13. It should be noted that Figure 3 Only the secondary gear 57 of the outer cutting member 13 of the hair cutting unit 9c is shown, and the secondary gear 57 of the outer cutting member 13 of the hair cutting units 9a and 9b is arranged in a corresponding manner. For the sake of clarity, the arrangement of the secondary gear 57 of the outer cutting member 13 of all three hair cutting units 9a, 9b, 9c is shown in Fig. 4b. Fig. 4a shows that each outer cutting member 13 is surrounded by the skin support member 59a, 59b, 59c of the corresponding hair cutting unit 9a, 9b, 9c respectively. The skin support member 59a, 59b, 59c provides a rotational support for the corresponding outer cutting member 13 respectively, and also covers the secondary gear 57 of the corresponding outer cutting member 13.

[0041] It should be noted that the drive system 27 described in detail above is only an example of how to implement the drive system in the electric shaver according to the present invention. The skilled person will be able to design alternative embodiments of the drive system, by which the inner cutting member 15 and the outer cutting member 13 of each hair cutting unit 9a, 9b, 9c can be rotated in mutually opposite directions R1, R2 around the central axis according to the present invention, wherein the second rotation speed ω2 of the outer cutting member 13 is lower than the first rotation speed ω1 of the inner cutting member 15. Instead of a single motor 29, the drive system 27 can have a first motor and a second motor, the first motor being used to rotate the inner cutting member 15 of each hair cutting unit 9a, 9b, 9c, and the second motor being used to rotate the outer cutting member 13 of each hair cutting unit 9a, 9b, 9c in a manner independent of the rotation of the inner cutting member 15. In this alternative embodiment, the electric shaver 1 may, for example, have a user input component, by means of which the user can select the second rotation speed ω2 of the outer cutting member 13 in a manner independent of the first rotation speed ω1 of the inner cutting member 15, or turn on or off the rotation of the outer cutting member 13 in a manner independent of the rotation of the inner cutting member 15.

[0042] As is known from prior art electric shavers, the hair capture efficiency of the hair cutting units 9a, 9b, 9c can be improved by rotating the outer cutting member 13 of each hair cutting unit 9a, 9b, 9c in a rotation direction R2 opposite to the rotation direction R1 of the inner cutting member 15 at a rotation speed ω2 lower than the rotation speed ω1 of the inner cutting member 15. The hair capture efficiency is the degree to which hair can penetrate the hair entry opening of the outer cutting member 13 during movement of the electric shaver 1 over the skin of the user (the annular shaving area 17 of the outer cutting member 13 is in contact with the skin). The higher the hair capture efficiency, the better the hair can penetrate the hair entry opening of the outer cutting member 13 and be cut by the hair cutting units 9a, 9b, 9c, for example during a single movement stroke of the electric shaver 1 over a specific area of ​​the skin, and the smaller the average remaining hair length obtained after the single movement stroke.

[0043] In order to further improve the hair capturing efficiency of the hair cutting units 9a, 9b, 9c, according to the present invention, the outer cutting member 13 of each hair cutting unit 9a, 9b, 9c of the electric shaver 1 has a hair entry opening 61, and the hair entry opening 61 includes a V-shaped opening portion 63 pointing to the first rotation direction R1 of the inner cutting member 15, that is, pointing to the direction opposite to the second rotation direction R2 of the outer cutting member 13, such as Figure 5As shown. In addition, according to the present invention, the second rotation speed ω2 of the outer cutting member 13 of each hair cutting unit 9a, 9b, 9c is such that the tangential speed VT of the outer cutting member 13 relative to the central axis 11 of the hair cutting unit 9a, 9b, 9c is in the range of 7.5 cm / s to 50 cm / s. In this regard, the tangential speed VT is measured at the radial position RC of the central base point 65 of the V-shaped opening portion 63 relative to the central axis 11, as shown in FIG. Figure 5 The center base point 65 is the point where the two legs 67a, 67b of the V-shaped opening portion 63 are connected to each other. Figure 5 Therefore, VT=2π*RC*ω2, and ω2=VT / (2π*RC).

[0044] The inventors of the present invention have conducted experiments in the form of numerical simulations using the following models: a mathematical model of human skin with hair; a mathematical model of a hair cutting unit having an outer cutting member having a straight groove-shaped hair entry opening extending approximately in a radial direction relative to the central axis of the hair cutting unit; and a mathematical model of hair cutting units 9a, 9b, 9c. Figures 6a and 6b show graphs of the hair capture efficiency of an outer cutting member having a straight hair entry opening and an outer cutting member 13, respectively, as the hair capture efficiency varies with the second rotation speed ω2 (in rpm). In these figures, the hair capture efficiency is represented by the average penetration depth APD (in mm) of the hair into the hair entry opening of the corresponding outer cutting member. Simulations were performed for a uniform hair length of 1 mm and multiple single strokes of the corresponding outer cutting member at a stroke speed between 10 cm / s and 30 cm / s on a specific skin area. For the outer cutting member 13, the radial position RC of the center base point 65 of the V-shaped opening portion 63 relative to the central axis 11 is 9 mm. For an outer cutting member with a straight hair entry opening, the radial position of the central radial point of the straight hair entry opening is also 9 mm. Therefore, the value ω2=500 rpm in the figure corresponds to the value VT=47 cm / s. The figure shows the comparable hair capture efficiency (APD) of the outer cutting member with a straight hair entry opening and the outer cutting member 13 when there is no rotational movement of the outer cutting member (ω2=0). As the outer cutting member rotates, the hair capture efficiency (APD) of the outer cutting member with a straight hair entry opening is slightly improved, and the optimal hair capture efficiency is achieved at a rotation speed ω2 of about 200 rpm, as shown in Figure 6a. As shown in Figure 6b, compared with the outer cutting member with a straight hair entry opening, as the outer cutting member 13 of the electric shaver 1 according to the present invention rotates, the hair capture efficiency (APD) of the outer cutting member 13 is significantly improved to a greater extent. As shown in Figure 6b, for the outer cutting member 13, the optimal hair capture efficiency is achieved at a second rotation speed ω2 of about 300 rpm. In particular, it can be clearly seen from Figures 6a and 6b that the relative improvement in hair capture efficiency (APD) caused by the rotation of the outer cutting member, that is, the ratio of the average penetration depth (APD) of hair entering the hair entry opening when the outer cutting member is rotating and when it is not rotating, is found that the outer cutting member 13 of the electric shaver 1 according to the present invention is significantly higher than the outer cutting member having a radially extending straight hair entry opening.

[0045] Fig. 7a and Fig. 7b respectively show the graph of the shaving efficiency of the hair cutting unit with the outer cutting member with straight hair entry opening and the hair cutting unit 9a, 9b, 9c, which varies with the second rotation speed ω2 (in rpm). In these figures, the shaving efficiency is represented by the average hair length reduction ALR (in mm) achieved by each hair cutting unit. Simulation is performed for multiple single strokes of a uniform hair length of 1 mm and a stroke speed of the corresponding hair cutting unit on a specific skin area between 10 cm / s and 30 cm / s. For the outer cutting member 13 of the hair cutting unit 9a, 9b, 9c, the radial position RC of the center base point 65 of the V-shaped opening portion 63 relative to the central axis 11 is 9 mm. For the hair cutting unit with the outer cutting member with straight hair entry opening, the radial position of the center radial point of the straight hair entry opening is also 9 mm. Therefore, the value ω2=500 rpm in the figure corresponds to the value VT=47 cm / s. The figure shows that, in the absence of rotational movement of the outer cutting member (ω2=0), the shaving efficiency (expressed as ALR) of the hair cutting units 9a, 9b, 9c is about 25% higher than that of the hair cutting units with the outer cutting member having the straight hair entry opening. As the outer cutting member rotates, the shaving efficiency (ALR) of the hair cutting units with the outer cutting member having the straight hair entry opening increases slightly, and the best shaving efficiency is achieved at a rotation speed ω2 of about 120 rpm, as shown in FIG7a. As shown in FIG7b, as the outer cutting member 13 of the hair cutting units 9a, 9b, 9c of the electric shaver 1 according to the present invention rotates, the shaving efficiency (ALR) of the hair cutting units 9a, 9b, 9c increases significantly to a greater extent than that of the hair cutting units with the outer cutting member having the straight hair entry opening. As shown in FIG7b, for the hair cutting units 9a, 9b, 9c, the best shaving efficiency is achieved at a second rotation speed ω2 of about 300 rpm. In particular, it can be clearly seen from Figures 7a and 7b that the hair cutting units 9a, 9b, and 9c of the electric shaver 1 according to the present invention are significantly higher in terms of the relative improvement in shaving efficiency (ALR) caused by the rotation of the outer cutting member, that is, the ratio of the average hair length reduction (ALR) when the outer cutting member is rotating and when it is not rotating, than the hair cutting unit having an outer cutting member with a radially extending straight hair entry opening.

[0046] As can be seen from FIG. 7b , when the second rotation speed ω2 of the outer cutting member 13 is about 80 rpm (corresponding to a VT value of about 7.5 cm / s), a significant improvement in shaving efficiency (ALR) of about 10% may have been achieved. As can be clearly seen from FIG. 7a , such a significant relative improvement in shaving efficiency (ALR) cannot be achieved by rotating the outer cutting member with a straight hair entry opening. In addition, the line L in FIGS. 7a and 7b threpresents an improvement in shaving efficiency (ALR) that is considered to be particularly perceptible to the user of the electric shaver 1. For the outer cutting member 13, this improvement in shaving efficiency (ALR) that is particularly perceptible to the user is achieved when the second rotation speed ω2 is between about 120 rpm (corresponding to VT=11.25 cm / s) and about 550 rpm (corresponding to VT=50 cm / s). In view of the fact that the rotation of the outer cutting member 13 causes more skin friction, VT values ​​higher than 50 cm / s may not be preferred. Therefore, according to the present invention, the second rotation speed ω2 of the outer cutting member 13 is such that the tangential speed VT of the outer cutting member 13 measured at the radial position RC of the center base point 65 of the V-shaped opening portion 63 of the hair entry opening 61 is in the range of 7.5 cm / s to 50 cm / s, and the more preferred range of VT values ​​is between 11.25 cm / s and 50 cm / s.

[0047] In addition, as shown in Fig. 7b, in the range of ω2 values ​​from about 120 rpm (VT = 11.25 cm / s) to about 300 rpm (VT = 28.3 cm / s), the relative improvement of shaving efficiency (ALR) is comparable to the relative improvement of shaving efficiency (ALR) in the range of ω2 values ​​from about 300 rpm (VT = 28.3 cm / s) to about 550 rpm (VT = 50 cm / s). Since the smaller the VT value, the less skin friction caused by the rotation of the outer cutting member 13, according to an embodiment of the present invention, the range of VT values ​​between 11.25 cm / s and 30.0 cm / s provides a preferred combination of a significant improvement in hair capture efficiency and shaving efficiency as described above and minimization of additional skin friction caused by the rotation of the outer cutting member 13.

[0048] Similar experiments have been conducted on hair cutting units with external cutting members, in which the hair entry opening (particularly its V-shaped opening portion) is arranged at a radial distance farther or closer to the central axis than the radial distance RC of the external cutting member 13 described above, and the experiments have shown that the range of VT values ​​according to the present invention as described above (within which the benefits of the present invention as described above are achieved) is independent of the radial distance. In other words, in embodiments in which the V-shaped opening portion 63 of the hair entry opening 61 according to the present invention is arranged at a radial distance RC farther or closer to the central axis 11, respectively, the second rotation speed ω2 of the external cutting member 13 should be reduced or increased in proportion to the radial distance RC in order to obtain comparable results in terms of improving hair capture efficiency and shaving efficiency. For example, in the embodiments described above, the second rotation speed ω2 is about 300 rpm (RC=9 mm), in the embodiment of RC=12 mm, comparable results are achieved at the second rotation speed ω2 of about 225 rpm, and in the embodiment of RC=6 mm, comparable results are achieved at the second rotation speed ω2 of about 450 rpm.

[0049] like Figure 5 As shown, the hair entry openings 61 of the outer cutting member 13 extend a first radial distance RD1 in the radial direction relative to the central axis 11. The V-shaped opening portions 63 of the hair entry openings 61 extend a second radial distance RD2 in the radial direction relative to the central axis 11. Figure 5 In the embodiment shown, the ratio RD2 / RD1 is about 0.75. In embodiments of the electric shaver in which the ratio RD2 / RD1 is at least 0.5, a particularly significant improvement in the hair capture efficiency and the shaving efficiency is achieved. However, for smaller ratios, improvements in the hair capture efficiency and the shaving efficiency can also be achieved, in particular when the first radial distance RD1 over which the hair entry opening 61 extends is relatively large.

[0050] exist Figure 5 In the embodiment shown, the hair entry opening 61 of the outer cutting member 13 further comprises a radially inner straight opening portion 69a and a radially outer straight opening portion 69b. The radially inner straight opening portion 69a is connected to the V-shaped opening portion 63 of the hair entry opening 61 at a first end 71a of the V-shaped opening portion 63 facing the central axis 11. The radially outer straight opening portion 69b is connected to the V-shaped opening portion 63 at a second end 71b of the V-shaped opening portion 63 facing away from the central axis 11. The radially inner straight opening portion 69a and the radially outer straight opening portion 69b respectively have a main extension direction in a radial direction relative to the central axis 11. In this embodiment, when the hair cutting units 9a, 9b, 9c are randomly moved on the user's skin, the radially inner straight opening portion 69a provides a higher hair capture efficiency for the hair approaching the hair entry opening 61 of the outer cutting member 13 via the inner peripheral area 73 of the annular shaving area 17. During this random movement, the radially outer straight opening portion 69b provides a higher hair capture efficiency for hair approaching the hair entry opening 61 via the peripheral area 75 of the annular shaving area 17, while the V-shaped opening portion 63 provides a higher hair capture efficiency for hair approaching the hair entry opening via the central area 61 of the annular shaving area 17.

[0051] also, Figure 5 The V angle α of the V-shaped opening portion 63 of the hair entry opening 61 is shown, and the V angle α is defined as the angle enclosed by the two legs 67a, 67b of the V-shaped opening portion 63. Figure 5In the embodiment shown, the V angle α is about 115°. The preferred range of the V angle α is 60° to 135°. In the case where the value of the V angle α is within this preferred range, in addition to providing improved hair capture efficiency and shaving efficiency, the V-shaped opening portion 63 also provides a stretching effect on the skin in two mutually separated directions during the rotation of the outer cutting member 13 in the second rotation direction R2. The skin stretching effect reduces the skin that arches into the hair entry opening 61, and thereby reduces the skin irritation caused by the shaving process.

[0052] Figure 8 Shown is an inner cutting member 15 of a hair cutting unit 9a, 9b, 9c, a first rotation direction R1 of the inner cutting member 15 around the central axis 11 of the hair cutting unit 9a, 9b, 9c, and a second rotation direction R2 of the outer cutting member 13. Each cutting element 21 in the annular array of cutting elements 21 is connected to the bracket 77 of the inner cutting member 15 via a curved connecting element 79. The bracket 77, the cutting element 21 and the curved connecting element 79 can be integrally formed by a single metal plate in a manner known to those skilled in the art. The cutting blade 23 of each cutting element 21 is arranged on the leading edge or leading edge (relative to the first rotation direction R1) of the upper surface 81 of the cutting element 21. The bracket 77 is connected to one of the three drive spindles 41 of the drive system 27 as described above in a manner known to those skilled in the art. Therefore, in Figure 8 The coupling between the drive spindle 41 and the bracket 77 is not shown.

[0053] exist Figure 8 In the illustrated embodiment, the cutting edges 23 of the cutting elements 21 of the inner cutting member 15 respectively include a V-shaped cutting edge portion 83 pointing in the second rotation direction R2 of the outer cutting member 13, i.e., in a direction opposite to the first rotation direction R1 of the inner cutting member 15 and in a direction opposite to that indicated by the V-shaped opening portion 63 of the hair entry opening 61 of the outer cutting member 13. Figure 8In the embodiment shown, each V-shaped cutting edge portion 83 extends over the entire extension of the cutting edge 23, respectively. The V-shaped cutting edge portion 83 of the cutting edge 23 of the inner cutting member 15 is aligned with the V-shaped opening portion 63 of the hair inlet opening 61 of the outer cutting member 13 in a tangential direction relative to the central axis 11. Alignment means that the center base point 85 of each V-shaped cutting edge portion 83 is arranged at a radial distance RCC from the central axis 11, which is substantially equal to the radial position RC of the center base point 65 of the V-shaped opening portion 63 relative to the central axis 11. In this embodiment, skin irritation caused by the shaving process is further reduced because: due to the interaction of the V-shaped opening portion 63 of the hair inlet opening 61 of the outer cutting member 13 with the V-shaped cutting edge portion 83 of the cutting element 21 of the inner cutting member 15, the hair captured by the hair inlet opening 61 is mainly cut in the central area of ​​the V-shaped opening portion 63, in which the degree of skin arching into the hair inlet opening 61 is at a minimum level. However, it should be noted that the present invention also covers embodiments in which the cutting edges 23 of the cutting elements 21 of the inner cutting member 15 have a more conventional shape, such as a substantially straight shape or a slightly curved shape, each cutting edge having a main extension direction in the radial direction.

[0054] The first rotational speed ω1 of the inner cutting member 15 has a limited effect on the hair capturing efficiency of the hair cutting units 9a, 9b, 9c. Therefore, as known to those skilled in the art, the first rotational speed ω1 can be selected mainly based on the hair cutting efficiency required for the cutting elements 21 of the rotating inner cutting member 15. Figure 8 In the embodiment of the present invention, the preferred range of the first rotation speed ω1 is such that Figure 8 The tangential velocity VTT of the cutting element 21 of the inner cutting member 15 relative to the central axis 11 measured at the radial distance RCC from the central axis 11 is in the range of 70 cm / s to 375 cm / s, more preferably in the range of 140 cm / s to 250 cm / s. In the present embodiment, RCC=9 mm, and the range of the above tangential velocity VTT corresponds to the range of the first rotational speed ω1 between about 750 rpm and 4000 rpm and between about 1500 rpm and 2700 rpm, respectively.

[0055] It will be clear to those skilled in the art that the scope of the present invention is not limited to the examples discussed above, and that several modifications and changes may be made without departing from the scope of the present invention as defined in the appended claims. The present invention is intended to be understood as including all such modifications and changes as long as they fall within the scope of the claims or their equivalents. Although the present invention is illustrated and described in detail in the drawings and the specification, such illustrations and descriptions are to be considered merely illustrative or exemplary and not restrictive. The present invention is not limited to the disclosed embodiments. The accompanying drawings are schematic, and details that are not necessary for understanding the present invention may have been omitted, and these details may not necessarily be drawn to scale.

[0056] In the process of practicing the claimed disclosure, variations of the disclosed embodiments may be understood and implemented by those skilled in the art through study of the drawings, the specification and the appended claims. In the claims, the word "comprising" does not exclude other steps or elements, and the indefinite article "a" or "an" does not exclude a plurality. Any reference signs in the claims shall not be construed as limiting the scope of the invention.

[0057] Unless expressly stated otherwise, elements and aspects discussed for or in connection with a particular embodiment may suitably be combined with elements and aspects of other embodiments.Thus, the fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

Claims

1. An electric shaver (1), comprising: at least one hair cutting unit (9a, 9b, 9c) having a central axis (11), an outer cutting member (13) having a hair entry opening (61) arranged in an annular shaving area (17) arranged concentrically around the central axis, and an inner cutting member (15) covered by the outer cutting member and having an annular array of cutting elements (21) arranged concentrically around the central axis; as well as a drive system (27) configured to: rotate the inner cutting member of each hair cutting unit at a first rotation speed (ω1) around the central axis of the hair cutting unit in a first rotation direction (R1), and rotate the outer cutting member of each hair cutting unit at a second rotation speed (ω2) around the central axis of the hair cutting unit in a second rotation direction (R2), wherein the second rotation direction is opposite to the first rotation direction and the second rotation speed is lower than the first rotation speed; Features: The hair entry opening (61) of the outer cutting member (13) of each hair cutting unit (9a, 9b, 9c) comprises a V-shaped opening portion (63) pointing in the first rotation direction (R1) of the inner cutting member (15); and The second rotation speed (ω2) of the outer cutting member of each hair cutting unit makes the tangential speed (VT) of the outer cutting member relative to the central axis (11) in the range of 7.5 cm / s to 50 cm / s, and the tangential speed (VT) of the outer cutting member relative to the central axis (11) is measured at the radial position (RC) of the central base point (65) of the V-shaped opening part relative to the central axis.

2. The electric shaver (1) according to claim 1, wherein: The second rotation speed (ω2) of the outer cutting member (13) of each hair cutting unit (9a, 9b, 9c) is such that the tangential speed (VT) of the outer cutting member relative to the central axis (11) is in the range of 11.25 cm / s to 30.0 cm / s.

3. The electric shaver (1) according to claim 1 or 2, wherein: The hair entry opening (61) of the outer cutting member (13) of each hair cutting unit (9a, 9b, 9c) further comprises a radially inner straight opening portion (69a) and a radially outer straight opening portion (69b), wherein the radially inner straight opening portion is connected to the V-shaped opening portion at a first end (71a) of the V-shaped opening portion (63) facing the central axis (11) of the hair cutting unit, and the radially outer straight opening portion is connected to the V-shaped opening portion at a second end (71b) of the V-shaped opening portion facing away from the central axis of the hair cutting unit, and the main extension direction of each of the radially inner straight opening portion and the radially outer straight opening portion is in a radial direction relative to the central axis of the hair cutting unit.

4. The electric shaver (1) according to any one of claims 1 to 3, wherein: The hair entry opening (61) extends a first radial distance (RD1) in a radial direction relative to the central axis (11) of the hair cutting unit (9a, 9b, 9c), and the V-shaped opening portion (63) of the hair entry opening extends a second radial distance (RD2) in the radial direction, the second radial distance being at least 50% of the first radial distance.

5. The electric shaver (1) according to any one of claims 1 to 4, wherein: The V angle (α) of the V-shaped opening portion (63) of the hair entrance opening (61) is in the range of 60° to 135°.

6. The electric shaver (1) according to any one of claims 1 to 5, wherein: The cutting element (21) of the inner cutting member (15) of each hair cutting unit (9a, 9b, 9c) comprises a cutting edge (23) having a V-shaped cutting edge portion (83) pointing in the second rotation direction (R2) of the outer cutting member (13), the V-shaped cutting edge portion and the V-shaped opening portion (63) of the hair entry opening (61) of the outer cutting member being aligned in a tangential direction relative to the central axis (11) of the hair cutting unit.

7. The electric shaver (1) according to any one of claims 1 to 6, wherein: The first rotation speed (ω1) of the inner cutting member (15) of each hair cutting unit (9a, 9b, 9c) makes the tangential speed (VTT) of the inner cutting member relative to the central axis (11) in the range of 70 cm / s to 375 cm / s, more preferably in the range of 140 cm / s to 250 cm / s, and the tangential speed (VTT) of the inner cutting member relative to the central axis (11) is measured at a radial distance (RCC) from the central axis, wherein the radial distance (RCC) is equal to the radial distance of the radial position (RC) of the central base point (65) of the V-shaped opening portion (63) from the central axis.

8. The electric shaver according to any one of claims 1 to 7, wherein: The drive system (27) comprises a single motor (29) which is configured and arranged to rotate the inner cutting member (15) of each hair cutting unit (9a, 9b, 9c) and the outer cutting member (13) of each hair cutting unit around the central axis (11) of the hair cutting unit via a transmission system (31).

9. The electric shaver (1) according to claim 8, wherein: The motor (29) is arranged in a main housing (3) of the shaver, wherein the at least one hair cutting unit (9a, 9b, 9c) is arranged in a shaving unit (5) of the shaver, the shaving unit being connected to the main housing, and wherein the transmission system (31) is partially arranged in the main housing and partially arranged in the shaving unit.

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