Electric shaver comprising rotatable outer cutting member having adjustable rotational speed

Abstract

The electric shaver (1) comprises at least one hair cutting unit (9a, 9b, 9c) having a central axis (11), an outer cutting member (13) having a hair inlet opening (61), and an inner cutting member (15). The inner cutting member and the outer cutting member rotate about the central axis at a first rotational speed ([omega] 1) and a second rotational speed ([omega] 2), respectively, and rotate relative to each other. The electric shaver further comprises a detection system (87) for measuring at least one user-related parameter (URP) related to the skin or hair of a user of the electric shaver or related to manipulation of the electric shaver by the user relative to the user's body. The electric shaver further comprises a processor (89) for controlling a second rotational speed ([omega] 2) of the outer cutting member according to the at least one measured user-related parameter.

Description

Technical Field

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

[0002] - at least one hair cutting unit, the outer cutting member having a central axis, an outer cutting member having a hair entry opening arranged in an annular shaving area 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 said central axis; and

[0003] - a drive system configured to rotate the inner cutting member of each hair cutting unit around the central axis of the hair cutting unit at a first rotational speed, and to rotate the outer cutting member of each hair cutting unit around the central axis of the hair cutting unit at a second rotational speed, and to rotate the inner cutting member and the outer cutting member of each hair cutting unit relative to each other around the central axis of the hair cutting unit. Background Art

[0004] As is well known, an electric shaver comprises at least one hair cutting unit, which has a central axis, an outer cutting member and an inner cutting member, the outer cutting member having a hair entry opening provided in an annular shaving area, the annular shaving area being arranged concentrically around the central axis, the inner cutting member being covered by the outer cutting member and having an annular array of cutting elements arranged concentrically around the central axis, and also comprising a drive system, the drive system being configured to rotate the inner cutting member of each hair cutting unit relative to the outer cutting member around the central axis of the hair cutting unit. 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 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 a cutting edge arranged on the cutting element of the rotating inner cutting member and a counter cutting edge arranged 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 the hair entry opening of the outer cutting member when the electric shaver moves on the user's skin (when the annular shaving area of ​​the outer cutting member contacts the skin). A higher hair capture efficiency is desirable because it will reduce the time of the shaving process required to achieve the desired shaving result, for example, in terms of the average remaining hair length after the shaving process. The higher the hair capture efficiency, for example, during a single movement stroke of the electric shaver on a specific area of ​​the skin, the hair will better penetrate the hair entry opening of the outer cutting member and be cut by the hair cutting unit, and the average remaining hair length obtained after the shaving process is shorter. In order to improve the hair capture efficiency, it has been proposed to also drive the outer cutting member of the hair cutting unit to rotate around the central axis of the hair cutting unit. For this purpose, the known electric shaver has a drive system, which is configured to rotate the inner cutting member of each hair cutting unit at a first rotation speed (number of revolutions per unit time) around the central axis of the hair cutting unit, and to rotate the outer cutting member of each hair cutting unit at a second rotation speed (number of revolutions per unit time) around the central axis of the hair cutting unit, and to rotate the inner cutting member and the outer cutting member of each hair cutting unit relative to each other around the central axis of the hair cutting unit.

[0006] US2,283,834 discloses an electric shaver, comprising a hair cutting unit having an outer cutting member, the outer cutting member being provided with a slit-shaped hair entry opening, the 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, for example between 6,000rpm and 15,000rpm (revs / min). The outer cutting member rotates in a direction opposite to the direction of rotation of the inner cutting member at a significantly lower speed, ranging between 40rpm and 120rpm, preferably about 80rpm. According to the patent, the relatively slow and continuous rotation of the outer cutting member enables the oblique hairs growing in all directions to be better and more regularly captured in the slit-shaped hair entry opening than can be achieved by the circular manual movement of the shaver with a fixed outer cutting member.

[0007] US10,195,751B2 discloses an electric shaver, which includes a shaving unit with three hair cutting units. Each hair cutting unit has an inner cutting member and an outer cutting member, 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 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 driven to rotate in the same direction or in directions opposite to each other around the central axis of the hair cutting unit. According to the patent, the rotation of the outer cutting member produces a more favorable effect for skin feeling by improving the action of lifting and catching hair of the user. In one example, the shaver has a gear transmission mechanism, which is configured to convert the motor rotation speed of 8,000rpm into the rotation speed of the outer cutting member of about 10rpm.

[0008] A disadvantage of these known electric shavers is that the rotation speed of the outer cutting member may not be optimal in all situations in which the user uses or operates the shaver, and in general may not be optimal for all users of the shaver. In particular, the hair capture efficiency of the shaver, although improved by the rotation of the outer cutting member, may vary depending on the specific way in which the user uses or operates the shaver or on the specific properties of the user's hair, and may therefore not be optimal in all use cases or for all users. In addition, in certain situations, for example, depending on the specific properties of the user's skin, some users may find the rotation of the outer cutting member unpleasant.

[0009] JP2010227225A discloses an electric shaver having a main body or a gripping part and a shaving unit or a head part arranged on the upper part of the gripping part. The head part includes three hair cutting units or blade blocks, each of which has an outer cutting member or an outer blade and an inner cutting member or an inner blade. The outer blades of the blade blocks extend parallel to each other in the longitudinal direction of the head part. An electric inner blade drive device is arranged in the head part for reciprocating the inner blade of each blade block relative to the outer blade of the blade block parallel to the longitudinal direction. In addition, an electric head drive device is arranged in the head part, which is configured to reciprocate the entire head part in the longitudinal direction and / or in the transverse direction of the head part extending perpendicular to the longitudinal direction, and / or to swing and reciprocate the entire head part around the central rotation axis of the head part extending perpendicular to the longitudinal direction and the transverse direction. According to the patent application, due to at least one of the longitudinal vibration, transverse vibration and swing vibration of the head part described previously, the entry rate of beard hair into the outer blade of the blade block is improved, so that the shaving performance of the electric shaver is improved. In addition, a detection component for detecting the operating state of the shaver is provided, and a control component for controlling the head drive device based on the detection signal from the detection device is provided. As a result, the penetration rate of beard hair into the outer blades of the blade block and the shaving performance are stable even when the operating state of the shaver is different. Examples of the measured operating state are the moving speed or moving acceleration of the head portion and the contact pressure received by the outer blades from the user's skin. Based on the detection signal, the control component can control the frequency, amplitude, speed or acceleration of the longitudinal vibration and / or lateral vibration and / or oscillating vibration of the entire head portion. Summary of the invention

[0010] The object of the present invention is to provide an electric shaver of the type described above in the section "Field of the Invention" which does not have the disadvantages described above in connection with the electric shavers known from US Pat. No. 2,283,834 and US Pat. No. 10,195,751.

[0011] In order to achieve the above object, the present invention provides an electric shaver, comprising:

[0012] - 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

[0013] a drive system configured to rotate the inner cutting member of each hair cutting unit about the central axis of the hair cutting unit at a first rotational speed and the outer cutting member of each hair cutting unit about the central axis of the hair cutting unit at a second rotational speed, and to rotate the inner and outer cutting members of each hair cutting unit relative to each other about the central axis of the hair cutting unit;

[0014] The electric shaver also includes:

[0015] a detection system configured and arranged to measure at least one user-related parameter related to the skin or hair of a user of the electric shaver or to the user's handling of the electric shaver relative to the user's body; and

[0016] - a processor configured and arranged to control the drive system such that a second rotational speed at which the drive system rotates the outer cutting member about the central axis of the hair cutting unit is dependent on at least one measured user-related parameter.

[0017] Therefore, in the electric shaver according to the present invention, the inner cutting member of each hair cutting unit rotates around the central axis of the hair cutting unit with a first rotation speed (revolutions per unit time) by a driving system, and the outer cutting member of each hair cutting unit rotates around the central axis of the hair cutting unit with a second rotation speed (revolutions per unit time) by a driving system. The inner cutting member and the outer cutting member can have the same rotation direction or the opposite rotation direction to each other around the central axis. As known in the art, by the first and second rotation speeds and the rotation direction of the inner cutting member and the outer cutting member, the relative rotation between the inner cutting member and the outer cutting member should be implemented to a degree sufficient to realize an effective hair cutting process.

[0018] Specifically, according to the present invention, the second rotational speed at which the drive system rotates the outer cutting member depends on at least one user-related parameter measured by means of the detection system. Specifically, the at least one user-related parameter is related to the skin or hair of the user of the electric shaver, or is related to the manipulation of the electric shaver by the user relative to the user's body. Therefore, the processor can automatically adapt the second rotational speed of the outer cutting member to, for example, a specific user-specific way in which the user manipulates the electric shaver relative to the user's body that affects the hair capture efficiency, a user-specific hair property that affects the hair capture efficiency, or a user-specific skin property that affects the way the user experiences the rotation of the outer cutting member. Specifically, the processor can automatically adapt the second rotational speed of the outer cutting member so that the hair capture efficiency is maintained at an optimal level or at least a desired level independently or less dependent on the specific way in which the user manipulates the electric shaver or the user-specific hair property, or so that the user's experience of the rotation of the outer cutting member is acceptable independent of or less dependent on the user's specific skin property. Examples of these user-related parameters and the way to control the second rotational speed of the outer cutting member depending on these user-related parameters will be described below in conjunction with embodiments of the present invention.

[0019] In an embodiment of the electric shaver according to the present invention, at least one user-related parameter includes at least one of the following parameters: the position of the electric shaver on the user's body; the amount of accumulated shaving time of the electric shaver for multiple different areas of the user's body during the shaving process; the speed of movement of the user moving the electric shaver on the user's body; the pressure or force with which the user presses the electric shaver against the body; parameters related to the user's skin properties; and parameters related to the user's hair properties. The detection system can be configured and arranged to measure only one of the user-related parameters or to measure two or more of the user-related parameters. Therefore, the processor can be configured and arranged to control the second rotation speed of the outer cutting member depending on only one of the user-related parameters or depending on two or more of the user-related parameters.

[0020] In an embodiment of the electric shaver according to the present invention, wherein at least one user-related parameter comprises the position of the electric shaver on the user's body, i.e., as a first example of a user-related parameter associated with the user manipulating the electric shaver relative to the user's body, the detection system comprises a detector configured and arranged to measure the position of the electric shaver on the user's body. In such an embodiment, the processor may, for example, be configured to reduce the second rotation speed of the outer cutting member when the detector detects that the electric shaver moves from a position on the user's body where the skin is known to have a relatively low sensitivity (e.g., a cheek region) to a position on the user's body where the skin is known to have a relatively high sensitivity (e.g., a neck region), or vice versa. In this way, the user may experience that the rotation of the outer cutting member is acceptable, regardless of or less affected by the position where the electric shaver actually shaves.

[0021] In an embodiment of the electric shaver according to the present invention, wherein at least one user-related parameter includes the amount of cumulative shaving time of the electric shaver for a plurality of different areas of the user's body during the shaving process, i.e., as a second example of a user-related parameter related to the manipulation of the electric shaver by the user relative to the user's body, the detection system includes a detector configured and arranged to measure the position of the electric shaver on the user's body, and the processor is configured to measure the amount of cumulative shaving time of the electric shaver for each of the plurality of different areas of the user's body based on the position of the electric shaver measured by the detector and the timing output provided by the timer. When the user shaves the same skin area for a longer time, even in the cheek area, skin irritation increases. When the amount of cumulative shaving time in a specific skin area exceeds a predefined threshold, the increase in the skin irritation can be limited, for example, by automatically reducing the second rotation speed of the outer cutting member. For this purpose, the processor can be configured to reduce the second rotation speed of the outer cutting member when the amount of cumulative shaving time measured for a specific area of ​​the plurality of different areas of the user's body exceeds the predefined threshold and the position of the electric shaver measured by the detector is within the specific area of ​​the plurality of different areas of the user's body.

[0022] In an embodiment of the electric shaver according to the present invention, at least one of the user-related parameters comprises the speed of movement of the electric shaver by the user on the user's body, i.e., as a third example of a user-related parameter related to the manipulation of the electric shaver by the user relative to the user's body, the detection system comprises a detector configured and arranged to measure the speed of movement of the electric shaver by the user on the user's body. A known problem with electric shavers is that the hair capture efficiency of the hair cutting unit decreases when the user increases the speed of movement of the electric shaver on the body. The hair capture efficiency can be increased by increasing the second rotational speed of the outer cutting member at least within a predefined range of the second rotational speed, the predefined range of the second rotational speed depending on the detailed design of the outer cutting member, in particular the design of the hair entry slot of the outer cutting member. Therefore, in this embodiment, the processor can be configured to increase the second rotational speed of the outer cutting member when the measured speed of movement increases.

[0023] In an embodiment of the electric shaver, wherein at least one user-related parameter comprises the pressure or force with which the user presses the electric shaver against the body, i.e., as a fourth example of a user-related parameter associated with the manipulation of the electric shaver by the user relative to the user's body, the detection system comprises a detector configured and arranged to measure the pressure or force with which the user presses the electric shaver against the body. When the pressure or force increases, the degree to which the skin arches into the hair entry opening of the outer cutting member increases, resulting in a potential increase in skin irritation. Because the degree to which the skin arches into the hair entry opening can be reduced by increasing the second rotational speed of the outer cutting member, when the processor in this embodiment is configured to increase the second rotational speed of the outer cutting member when the measured pressure or force increases, the increase in skin irritation caused by the increase in the pressure can be prevented or limited.

[0024] In an embodiment of the electric shaver according to the present invention, wherein at least one user-related parameter comprises a parameter related to the user's skin properties, the detection system comprises a detector configured and arranged to measure the parameter related to the user's skin properties. A well-known skin property affected by the shaving process is, for example, skin redness, which may indicate the degree of skin irritation caused by the shaving process. In this example, the processor may be configured to reduce the second rotational speed of the outer cutting member when the detector measures an increase in skin redness. The processor may also control the second rotational speed of the outer cutting member depending on another skin property, particularly when such skin property affects the hair capture efficiency.

[0025] In an embodiment of the electric shaver according to the present invention, wherein at least one user-related parameter comprises a parameter related to the user's hair properties, the detection system comprises a detector, and the detector is configured and arranged to measure the parameter related to the user's hair properties. Preferably, the hair properties are hair properties that may affect the hair capture efficiency of the hair cutting unit, such as hair length, hair thickness or hair density on the skin. For example, when the hair length is measured by the detector, the processor can be configured to increase the second rotation speed of the outer cutting member when the detector measures an increase in the hair length. Therefore, the hair capture efficiency of longer hairs can be increased.

[0026] In an embodiment of an electric shaver according to the present invention, a drive system comprises a single motor, the single motor 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 the hair cutting unit via a transmission system, and a processor is configured and arranged to control the single motor so that the second rotational speed of the outer cutting member depends on the measured user-related parameter. Using a single motor in this embodiment makes the structure of the electric shaver relatively simple. In this embodiment, the regulation of the second rotational speed of the outer cutting member by the processor also usually causes the first rotational speed of the inner cutting member to be proportionally regulated. However, as long as the first rotational speed remains within the required range for effective hair cutting, this regulation of the first rotational speed of the inner cutting member can be acceptable in many practical applications.

[0027] In a preferred embodiment of the electric shaver according to the present invention, the drive system includes a first motor and a second motor, the first motor is configured and arranged to rotate the inner cutting member of each hair cutting unit around the central axis of the hair cutting unit, the second motor is configured and arranged to rotate the outer cutting member of each hair cutting unit around the central axis of the hair cutting unit, and the processor is configured and arranged to control the second motor so that the second rotation speed of the outer cutting member depends on the measured user-related parameter. In this embodiment, the second rotation speed of the outer cutting member can be adjusted independently of the first rotation speed of the inner cutting member. For example, the first motor can keep the first rotation speed of the inner cutting member at a constant value that is most suitable for hair cutting, and the second motor can adjust the second rotation speed of the outer cutting member when the measured user-related parameter changes, so that the hair capture efficiency of the hair cutting unit is maintained at an optimal level. In this embodiment, the independent control of the rotation of the outer cutting member also allows, for example, to provide a user input member, by means of which the user can turn on or off the rotation of the outer cutting member, or select between a plurality of predefined speed ranges of the outer cutting member based on user preferences.

[0028] In another embodiment of the electric shaver according to the present invention, the drive system is configured to rotate the inner cutting member of each hair cutting unit around the central axis of the hair cutting unit in a first rotation direction, and the outer cutting member of each hair cutting unit is rotated in a second rotation direction opposite to the first rotation direction around the central axis of the hair cutting unit, and the second rotation speed of the outer cutting member is lower than the first rotation speed of the inner cutting member. Compared with the embodiment in which the inner cutting member and the outer cutting member rotate in the same direction, by rotating the inner cutting member and the outer cutting member of each hair cutting unit in mutually opposite directions, the rotation speed of the inner cutting member that mainly determines the hair cutting efficiency of the inner cutting member relative to the outer cutting member can be reduced. In addition, it is found that the optimal value or range (revolutions per unit time) of the second rotation speed of the outer cutting member that mainly determines the hair catching efficiency of the outer cutting member is generally lower than the optimal value or range (revolutions per unit time) of the first rotation speed of the inner cutting member required for optimal hair cutting.

[0029] In an embodiment of the electric shaver according to the present invention, wherein the drive system is configured to rotate the inner cutting member and the outer cutting member of each hair cutting unit in directions opposite to each other as previously described, the hair entry opening of the outer cutting member of each hair cutting unit may include a V-shaped opening portion pointing to a first rotation direction of the inner cutting member, and the second rotation speed of the outer cutting member of each hair cutting unit may be such that the tangential speed of the outer cutting member relative to the central axis is in the range between 7.5 cm / s and 50 cm / s, the tangential speed being measured at the radial position of the central base point of the V-shaped opening portion relative to the central axis. In this embodiment, 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.

[0030] Experiments conducted by the inventors of the present invention have demonstrated that, for a hair cutting unit having an outer cutting member, the outer cutting member having a straight slot-shaped hair entry opening extending substantially in a radial direction relative to the central axis of the hair cutting unit, an increase in the hair capture efficiency and, therefore, a reduction in the average remaining hair length after a shaving process can be achieved by rotating the outer cutting member in a direction opposite to the rotation direction of the inner cutting member. The experiments further showed that, for a hair cutting unit having an outer cutting member with a hair entry opening, the hair entry opening having a V-shaped opening portion pointing in a first rotation direction of the inner cutting member, a very significant increase in the hair capture efficiency and, therefore, a reduction in the average remaining hair length after a shaving process in a very significant and user-perceptible manner can be achieved 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 within the above-mentioned range of between 7.5 cm / s and 50 cm / s. Specifically and surprisingly, the hair capture efficiency of the electric shaver according to an embodiment of the present invention is relatively increased, while the average remaining hair length is relatively reduced, i.e., the hair capture efficiency and the average remaining hair length achieved with a fixed outer cutting member are found to be significantly higher than those of an electric shaver having an outer cutting member with a hair entry opening extending toward the pen diameter. When, in this embodiment, the second rotational 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 within a more preferred range of 11.25 cm / s to 30.0 cm / s, the hair capture efficiency is significantly increased, and therefore, the average remaining hair length after the shaving process is reduced in a significant and user-perceptible manner, as previously described, while the degree of additional skin friction caused by the rotation of the outer cutting member is minimal.

[0031] In an embodiment of the electric shaver according to the present invention, the hair entry opening extends a first radial distance in a radial direction relative to a central axis of the hair cutting unit, and the V-shaped opening portion 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, thereby achieving a particularly significant improvement in hair capturing efficiency.

[0032] 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 relatively high hair capture efficiency for hair approaching the hair entry opening of the outer cutting member via the inner circumferential area of ​​the annular shaving area and the outer circumferential area of ​​the annular shaving area, respectively. The V-shaped opening portion of the hair entry opening provides a relatively high hair capture efficiency for hair approaching the hair entry opening via the central area of ​​the annular shaving area.

[0033] 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, the V-angle is defined as the angle enclosed by the two legs of the V-shaped opening portion relative to the V-shaped opening portion. A V-angle in the range of 60° to 135° produces a stretching effect on the skin in two mutually divergent directions, which results in a reduced arching of the skin into the hair entry opening, thereby reducing skin irritation caused by the shaving process.

[0034] 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

[0035] The present invention will be explained in more detail with reference to the accompanying drawings, in which the same or similar features are indicated with the same reference numerals, and in which:

[0036] Figure 1 Schematically shows an electric shaver according to the present invention;

[0037] Figure 2 It is along Figure 1 A schematic cross-sectional view of the hair cutting unit of the electric shaver along the line II-II in FIG.

[0038] Figure 3 Schematically shows Figure 1 A driving system for an electric shaver;

[0039] Figure 4a is Figure 1 A top view of a shaving unit of an electric shaver;

[0040] Figure 4b shows Figure 3 Part of the drive system;

[0041] Figure 5 yes Figure 2 A top view of an outer cutting member of a hair cutting unit;

[0042] Figures 6a and 6b show an outer cutting member with a straight hair entry opening and Figure 5 A graph of the hair capture efficiency of an outer cutting member as a function of the rotational speed of the outer cutting member;

[0043] 7a and 7b show a hair cutting unit with an outer cutting member having a straight hair entry opening and Figure 2 a graph of the shaving efficiency of a hair cutting unit as a function of the rotation speed of an outer cutting member of the hair cutting unit;

[0044] Figure 8 Shows Figure 2 an inner cutting member of a hair cutting unit;

[0045] Fig. 9 Schematically shows Figure 1 Detection system, processor and drive system of electric shaver;

[0046] Figures 10a-10f schematically show Fig. 9 Different embodiments of the detection system shown in ; and

[0047] Fig.11 Schematically shows Figure 1 An alternative embodiment of a drive system for an electric shaver. DETAILED DESCRIPTION

[0048] 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 further 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 a coupling structure (not shown) Figure 1 , and of a type well known to those skilled in the art), by means of which the shaving unit 5 is releasably connected to the main housing 3. 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 1The general layout of the electric shaver is shown only in a schematic manner and is not intended to limit the scope of the present 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 connected to the main housing via a relatively narrow centrally arranged coupling structure, wherein there is an open space between the shaving unit and the main housing around the coupling structure, as is well known in the art.

[0049] Figure 2 It is along Figure 1 Schematic cross-sectional view of the hair cutting unit 9c 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 2 The 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, the hair on the user's skin penetrating into the hair entry opening present in the annular shaving area 17 is cut by the interaction of the cutting edge 23 and the counter-cutting edge 25, which is present on the cutting element 21 of the inner cutting member 15 and the counter-cutting edge 25 is present on the bridge portion 19 of the outer cutting member 13. It should be noted that, as is well known in the art, the shaver according to the present invention can have two or more annular shaving areas arranged concentrically around the central axis.

[0050] The drive system of the electric shaver 1 mentioned above is schematically shown in Figure 3 and is indicated by reference numeral 27. Figure 3 In the embodiment shown in FIG. 1 , the drive system 27 comprises a single motor 29 which is arranged in the main housing 3. Furthermore, in this embodiment, the drive system 27 is configured to rotate the inner cutting member 15 of each hair cutting unit 9a, 9b, 9c around the central axis 11 of the hair cutting unit 9a, 9b, 9c in a first rotation direction R1 (e.g., Figure 2) and rotates at a first rotation speed ω1, and causes the outer cutting member 13 of each hair cutting unit 9a, 9b, 9c to rotate around the central axis 11 of the hair cutting unit 9a, 9b, 9c in a second rotation direction R2 opposite to the first rotation direction R1 (as shown in Figure 2 ) and rotates at a second rotational speed ω2 which is lower than the first rotational speed ω1. For this purpose, the drive system 27 comprises a transmission system 31, via which the motor 29 is able to 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. The driving system 27 for the other hair cutting units 9a, 9b will be explained below. It should also be noted that for simplicity, Figure 3 The support structure 7 of the shaving unit 5 is only partially shown.

[0051] like Figure 3 As shown in , 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, each of which is mounted on a corresponding drive shaft in three drive shafts 41, and the drive shafts 41 are each connected to a corresponding internal cutting member in three internal cutting members 15 of the hair cutting units 9a, 9b, 9c, and each is rotatably journaled relative to the support structure 7 of the shaving unit 5. The three sub-gears 39 are each meshed with the first main gear 33. It is worth noting that Figure 3 Only one of the pinion gears 39 and one of the drive shafts 41 coupled to the inner cutting member 15 of the hair cutting unit 9c is shown, and the pinion gears and drive shafts associated with the inner cutting members 15 of the hair cutting units 9a and 9b are arranged in a corresponding manner.

[0052] The transmission system 31 also includes a secondary shaft 43 arranged in parallel with the motor shaft 37. The upper portion of the secondary shaft 43 is arranged between the two secondary gears 39, but the arrangement is Figure 3. The secondary shaft 43 carries a third main gear 45 and a fourth main gear 49, which mesh with the second main gear 35 via a plurality of intermediate gears 47. The transmission system 31 also includes a third shaft 51, which is arranged in a straight line with the motor shaft 37 and is rotatably journaled 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, which mesh with the fourth main gear 49. The outer cutting members 13 of the hair cutting units 9a, 9b, 9c each include a secondary gear 57, which meshes with the sixth main gear 55, and the sixth main gear 55 is centrally arranged 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 gears 57 of the outer cutting members 13 of the hair cutting units 9a and 9b are arranged in a corresponding manner. For the sake of clarity, the arrangement of the secondary gears 57 of the outer cutting members 13 of all three hair cutting units 9a, 9b, 9c is shown in Fig. 4b. Fig. 4a shows that the outer cutting members 13 are each surrounded by the skin support members 59a, 59b, 59c of the corresponding hair cutting units 9a, 9b, 9c. The skin support members 59a, 59b, 59c each provide a rotational bearing for the corresponding outer cutting member 13, and also cover the secondary gear 57 of the corresponding outer cutting member 13.

[0053] As known from the electric shavers of the prior art, 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 around the central axis 11 of the hair cutting unit 9a, 9b, 9c. The hair capture efficiency refers to the degree to which hair can penetrate into the hair entry opening of the outer cutting member 13 when the electric shaver 1 is moved over the skin of the user and the annular shaving area 17 of the outer cutting member 13 is in contact with the skin. For example, the higher the hair capture efficiency, the better the hair will penetrate into the hair entry opening of the outer cutting member 13 and be cut by the hair cutting units 9a, 9b, 9c 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 a single movement stroke. In order to improve the hair catching efficiency, the rotation direction R2 of the outer cutting member 13 of each hair cutting unit 9a, 9b, 9c can be opposite to the rotation direction R1 of the inner cutting member 15, as shown in the embodiment of the figure, or the inner cutting member 15 and the outer cutting member 13 of each hair cutting unit 9a, 9b, 9c can have the same rotation direction. In the latter case, the rotation speeds ω1 and ω2 of the inner cutting member 15 and the outer cutting member 13 should be sufficiently different from each other, so that the relative rotation between the inner cutting member 15 and the outer cutting member 13 is implemented to a degree sufficient to achieve an effective hair cutting process, as known to those skilled in the art. Therefore, the present invention is not limited to the embodiment in which the inner cutting member 15 and the outer cutting member 13 of the hair cutting unit 9a, 9b, 9c have mutually opposite rotation directions R1, R2, as shown in the embodiment of the drawings.

[0054] In the embodiment of the present invention shown in the drawings, a particularly significant improvement in the hair capturing efficiency of the hair cutting units 9a, 9b, 9c is achieved by providing the outer cutting member 13 of each hair cutting unit 9a, 9b, 9c of the electric shaver 1 with a hair entry opening 61, the hair entry opening 61 comprising a V-shaped opening portion 63 pointing in the first rotation direction R1 of the inner cutting member 15, i.e., in a direction opposite to the second rotation direction R2 of the outer cutting member 13, as shown in FIG. Figure 5 As shown in . In addition, in this embodiment, the second rotation speed ω2 of the outer cutting member 13 of each hair cutting unit 9a, 9b, 9c is lower than the first rotation speed ω1 of the inner cutting member 15. Specifically, the second rotation speed ω2 causes the tangential speed VT of the outer cutting member 13 relative to the central axis 11 of the hair cutting unit 9a, 9b, 9c to be between 7.5 cm / s and 50 cm / s. In this regard, the tangential speed VT should be 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 As shown in . Therefore, VT=2π*RC*ω2, and ω2=VT / (2π*RC). It should be noted that the present invention is not limited to electric shavers in which the hair entry opening of the rotating outer cutting member has a V-shaped opening portion as in the embodiment shown in the figure. The outer cutting member can, for example, have a more conventional straight or slightly curved hair entry slot, which extends mainly in a radial direction relative to the central axis of the hair cutting unit, or have other well-known hair entry opening geometries.

[0055] The inventor of the present invention has used the mathematical model of human skin with hair, the mathematical model of the hair cutting unit with outer cutting member and the mathematical model of the embodiment of hair cutting unit 9a, 9b, 9c, and carried out experiment in the form of numerical simulation, wherein the outer cutting member has a straight grooved hair entry opening extending substantially in the radial direction relative to the central axis of the hair cutting unit. Fig. 6a and Fig. 6b respectively show the figure of the hair capture efficiency of the outer cutting member with straight hair entry opening and the outer cutting member 13 as the function of the second rotation speed ω2 (in rpm). In these figures, the hair capture efficiency is expressed as the average penetration depth APD (in mm) of hair entering the hair entry opening of the corresponding outer cutting member. Simulation is for the uniform hair length of 1mm and the multiple single strokes carried out with the stroke speed between 10cm / s and 30cm / s of the corresponding outer cutting member on the specific skin area. For the outer cutting member 13, the radial position RC of the center base point 65 of the V-shaped opening part 63 relative to the central axis 11 is 9mm. For the 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 9mm. Therefore, the value ω2=500rpm in the figure corresponds to the value VT=47cm / s. These figures show that the hair capture efficiency (APD) of the outer cutting member with a straight hair entry opening is comparable to that of the outer cutting member 13 when the outer cutting member does not rotate (ω2=0). With the rotation of the outer cutting member, the hair capture efficiency (APD) of the outer cutting member with a straight hair entry opening increases slightly, and the best hair capture efficiency is achieved at a rotation speed ω2 of about 200rpm, as shown in Figure 6a. As shown in Figure 6b, with the rotation of the outer cutting member 13 of the electric shaver 1 according to this embodiment of the present invention, the hair capture efficiency (APD) of the outer cutting member 13 increases significantly compared with the outer cutting member with a straight hair entry opening. As shown in Figure 6b, for the outer cutting member 13, the best hair capture efficiency is achieved when the rotation speed ω2 is about 300rpm. Specifically, it can be clearly seen from Figures 6a and 6b that the hair capture efficiency (APD) is relatively increased due to the rotation of the outer cutting member, that is, the ratio between the average penetration depth (APD) of the hair into the hair entry opening when the outer cutting member is rotating and when it is not rotating is significantly higher for the outer cutting member 13 of the electric shaver 1 according to this embodiment of the present invention than for the outer cutting member having a hair entry opening extending in the direction of the pen diameter.

[0056] Fig. 7a and Fig. 7b respectively show the figure of the shaving efficiency of the hair cutting unit and the hair cutting unit 9a, 9b, 9c of the outer cutting member with straight hair entry opening as the function of the second rotation speed ω2 (in rpm). In these figures, the shaving efficiency is expressed as the average hair length reduction ALR (in mm) achieved by means of the corresponding hair cutting unit. Simulation is for the uniform hair length of 1mm and the multiple single strokes of the corresponding hair cutting unit on a specific skin area with a stroke speed between 10cm / s and 30cm / s. For the outer cutting member 13 of the hair cutting unit 9a, 9b, 9c, the radial position RC of the central base point 65 of the V-shaped opening part 63 relative to the central axis 11 is 9mm. For the hair cutting unit with the outer cutting member with straight hair entry opening, the radial position of the central radial point of the straight hair entry opening is also 9mm. Therefore, the value ω2=500rpm in the figure corresponds to the value VT=47cm / s. These figures show that, in the case where the outer cutting member does not rotate (ω2=0), the shaving efficiency (in ALR) of the hair cutting units 9a, 9b, 9c is about 25% higher than the shaving efficiency of the hair cutting units with the outer cutting member having a straight hair entry opening. With the rotation of the outer cutting member, the shaving efficiency (ALR) of the hair cutting units with the outer cutting member having a straight hair entry opening increases slightly, and the best shaving efficiency is achieved when the rotation speed ω2 is about 120rpm, as shown in Figure 7a. As shown in Figure 7b, with the rotation of the outer cutting member 13 of the hair cutting units 9a, 9b, 9c of the electric shaver 1 according to this embodiment of the present invention, the shaving efficiency (ALR) of the hair cutting units 9a, 9b, 9c increases significantly compared to the hair cutting units with the outer cutting member having a straight hair entry opening. As shown in Figure 7b, for the hair cutting units 9a, 9b, 9c, the best shaving efficiency is achieved when the second rotation speed ω2 is about 300rpm. Specifically, it can be clearly seen from Figures 7a and 7b that the relative increase 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, is significantly higher for the hair cutting units 9a, 9b, and 9c of the electric shaver 1 according to this embodiment of the present invention than for the hair cutting units having an outer cutting member with a hair entry opening extending in the direction of the pen diameter.

[0057] It can be derived from FIG. 7b that a significant increase in the shaving efficiency (ALR) of about 10% can already be achieved when the second rotation speed ω2 of the outer cutting member 13 is about 80 rpm, which corresponds to a value of VT of about 7.5 cm / s. It is clear from FIG. 7a that such a significant relative increase in the shaving efficiency (ALR) cannot be achieved by rotating the outer cutting member with a straight hair entry opening. Furthermore, the line L in FIGS. 7a and 7b is th The second rotation speed ω2 represents an increase in shaving efficiency (ALR), which is considered to be particularly noticeable by the user of the electric shaver 1. For the outer cutting member 13, this increase in shaving efficiency (ALR) that is particularly noticeable by the user can be 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). Considering that the skin friction caused by the rotation of the outer cutting member 13 is relatively large, VT values ​​higher than 50 cm / s may not be preferred. Therefore, in this embodiment of the present invention, the second rotation speed ω2 of the outer cutting member 13 is such that the tangential velocity 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 within the range between 7.5 cm / s and 50 cm / s, and the more preferred range of VT values ​​is between 11.25 cm / s and 50 cm / s.

[0058] In addition, as shown in FIG. 7 b, the relative increase in shaving efficiency (ALR) in the range of ω2 values ​​between about 120 rpm (VT=11.25 cm / s) and about 300 rpm (VT=28.3 cm / s) is comparable to the relative increase in shaving efficiency (ALR) in the range of ω2 values ​​between about 300 rpm (VT=28.3 cm / s) and about 550 rpm (VT=50 cm / s). Since the skin friction caused by the rotation of the outer cutting member 13 is lower at lower VT values, according to another 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 significantly increased hair capture and shaving efficiency as previously described with minimal additional skin friction caused by the rotation of the outer cutting member 13.

[0059] Similar experiments conducted on a hair cutting unit with an outer cutting member (wherein, as previously described, the hair entry opening with the outer cutting member (particularly its V-shaped opening portion) is arranged at a greater or smaller radial distance from the central axis than the radial distance RC of the outer cutting member 13) show that the range of VT values ​​in this embodiment of the present invention as previously described (within which the benefits of this embodiment of the present invention as previously described are achieved) is not affected by the radial distance. In other words, in the embodiment of the present invention, the V-shaped opening portion 63 of the hair entry opening 61 is arranged at a greater or smaller radial distance RC from the central axis 11, respectively, and the second rotation speed ω2 of the outer cutting member 13 should be reduced or increased in proportion to the radial distance RC, respectively, so as to achieve similar results in terms of improving hair capture and shaving efficiency. For example, in the embodiment described previously, the second rotation speed ω2 is about 300 rpm (RC=9 mm), and similar results will be achieved when the second rotation speed ω2 is about 225 rpm in the embodiment with RC=12 mm, and similar results will be achieved when the second rotation speed ω2 is about 450 rpm in the embodiment with RC=6 mm.

[0060] like Figure 5 As shown in , the hair entry openings 61 of the outer cutting member 13 each extend a first radial distance RD1 in a radial direction relative to the central axis 11. The V-shaped opening portions 63 of the hair entry openings 61 each extend a second radial distance RD2 in a radial direction relative to the central axis 11. Figure 5 In the embodiment shown in , 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 hair capture and shaving efficiency is achieved. However, for smaller values ​​of the ratio, an improvement in hair capture and 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.

[0061] exist Figure 5In the embodiment shown in, the hair entrance opening 61 of the outer cutting member 13 also includes 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 entrance opening 61 at the 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 the second end 71b of the V-shaped opening portion 63 facing away from the central axis 11. The main extension direction of the radially inner straight opening portion 69a and the radially outer straight opening portion 69b is in the radial direction relative to the central axis 11. In this embodiment, the radially inner straight opening portion 69a provides a relatively high hair capture efficiency for the hair approaching the hair entrance opening 61 of the outer cutting member 13 via the inner circumferential area 73 of the annular shaving area 17 during the random movement of the hair cutting units 9a, 9b, 9c on the user's skin. During this random movement, the radially outer straight opening portion 69b provides a relatively high hair capture efficiency for hair approaching the hair entry opening 61 via the outer circumferential area 75 of the annular shaving area 17, while the V-shaped opening portion 63 provides a relatively high hair capture efficiency for hair approaching the hair entry opening 61 via the central area of ​​the annular shaving area 17.

[0062] also, Figure 5 The V angle α of the V-shaped opening portion 63 of the hair entry opening 61 is shown, which is defined as the angle enclosed by the two legs 67a, 67b of the V-shaped opening portion 63. Figure 5 In the embodiment shown in , the V angle α is about 115°. The preferred range of the V angle α is from 60° to 135°. When the value of the V angle α is within this preferred range, in addition to providing improved hair capture and shaving efficiency, the V-shaped opening portion 63 also provides a stretching effect on the skin in two mutually divergent directions during the rotation of the outer cutting member 13 in the second rotation direction R2. The skin stretching effect causes a reduction in the arching of the skin into the hair entry opening 61, thereby reducing skin irritation caused by the shaving process.

[0063] Figure 8Shown is the inner cutting member 15 of hair cutting unit 9a, 9b, 9c, the first rotation direction R1 of the inner cutting member 15 around the central axis 11 of hair cutting unit 9a, 9b, 9c and the second rotation direction R2 of outer cutting member 13. Each cutting element 21 in the annular array of cutting elements 21 is connected to the support 77 of inner cutting member 15 via curved connecting element 79. Support 77, cutting element 21 and curved connecting element 79 can be formed integrally by a single metal plate in a manner known to those skilled in the art. The cutting edge 23 of each cutting element 21 is provided on the leading edge or the front edge (relative to the first rotation direction R1) of the upper surface 81 of cutting element 21. Support 77 is connected to one of the three drive shafts 41 of previously described drive system 27 in a manner well known to those skilled in the art. Therefore, Figure 8 The connection between the drive shaft 41 and the bracket 77 is not shown.

[0064] exist Figure 8 In the embodiment shown in , the cutting edges 23 of the cutting elements 21 of the inner cutting member 15 each include a V-shaped cutting edge portion 83, which points to the second rotation direction R2 of the outer cutting member 13, i.e., the direction opposite to the first rotation direction R1 of the inner cutting member 15, and the direction opposite to the direction in which the V-shaped opening portion 63 of the hair entry opening 61 of the outer cutting member 13 points. Figure 8 In the embodiment shown in , the V-shaped cutting edge portions 83 each extend over the entire extension of the cutting edge 23. The V-shaped cutting edge portions 83 of the cutting edge 23 of the inner cutting member 15 and the V-shaped opening portions 63 of the hair inlet opening 61 of the outer cutting member 13 are aligned in the tangential direction relative to the central axis 11. Said alignment means that the central 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 central base point 65 of the V-shaped opening portion 63 relative to the central axis 11. In this embodiment, due to the fact that the V-shaped opening portions 63 of the hair inlet opening 61 of the outer cutting member 13 and the V-shaped cutting edge portions 83 of the cutting element 21 of the inner cutting member 15 interact, the skin irritation caused by the shaving process is further reduced, and the hair captured by the hair inlet opening 61 is mainly cut in the central area of ​​the V-shaped opening portion 63, wherein the degree of arching of the skin into the hair inlet opening 61 is at a minimum level. However, it is worth noting 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.

[0065] 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, 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, as known to those skilled in the art. 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 shown in 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, where RCC=9 mm, the range of the tangential velocity VTT corresponds to the first rotational speed ω1 in the range of about 750 rpm to 4000 rpm and about 1500 rpm to 2700 rpm, respectively.

[0066] The inventor of the present invention realizes that, for an electric shaver in which the outer cutting member of the hair cutting unit rotates around the central axis of the hair cutting unit to increase the hair capturing efficiency, the hair capturing efficiency may also depend on other parameters besides the second rotational speed of the outer cutting member. Specifically, the inventor realizes that the hair capturing efficiency may depend on the specific way in which the user manipulates the electric shaver relative to the user's body and the specific hair properties of the specific user. The inventor also realizes that different users may experience different rotations of the outer cutting member depending on the specific skin properties. Therefore, without any further measures, the second rotational speed of the outer cutting member may not be optimal in all cases in which the user uses or operates the electric shaver, and may not generally be optimal for all users of the electric shaver.

[0067] In order to prevent or at least alleviate this problem, in the electric shaver 1 according to the present invention, the second rotation speed ω2 of the outer cutting member 13 of the hair cutting units 9a, 9b, 9c is automatically adapted so that the hair capturing efficiency will be maintained at an optimal level or at least a desired level, regardless of or less affected by the specific way in which the user manipulates the electric shaver 1, and / or regardless of or less affected by the user's specific hair properties, and / or so that the rotation of the outer cutting member is experienced by the user as acceptable, regardless of or less affected by the user's specific skin properties. For this purpose, as Fig. 9As schematically shown in FIG. 8 , according to the present invention, the electric shaver 1 comprises a detection system 87, which is configured and arranged to measure at least one user-related parameter, wherein the user-related parameter is related to the skin or hair of a user of the electric shaver 1 or to the manipulation of the electric shaver 1 by the user relative to the user's body. Furthermore, according to the present invention, the electric shaver 1 comprises a processor 89, which is configured and arranged to control the drive system 27 so that the drive system 27 rotates the outer cutting member 13 around the central axis 11 of the hair cutting unit 9a, 9b, 9c at a second rotation speed ω2 that depends on the at least one measured user-related parameter. Fig. 9 As shown in , during use, the detection system 87 can generate an output signal URP representing the value of the measured user-related parameter. The output signal URP can be received by the processor 89, and the processor 89 can generate an output signal ω2, which represents the second rotation speed ω2 of the outer cutting member 13 to be achieved by the drive system 27. The drive system 27 may include a power control module 91, which is connected to the battery 93 and is configured to power the motor 29 based on the output signal ω2, so that the drive system 27 achieves the second rotation speed ω2 of the outer cutting member 13. For this purpose, the power control module 91 may include a feedback speed control, which is known to those skilled in the art and is therefore not discussed in detail.

[0068] Figure 3 Schematically shows the positions of the processor 89, the power control module 91 and the battery 93 in the main housing 3 of the electric shaver 1. Examples of user-related parameters, a detection system for measuring user-related parameters and a specific method for controlling the second rotation speed ω2 of the outer cutting member 13 according to the user-related parameters will be described below with reference to further embodiments of the present invention.

[0069] It should be noted that the present invention also covers embodiments in which the processor and / or the detection system are arranged separately from the main housing 3 and the shaving unit 5, for example, in a separate electronic device (such as a smartphone). In such embodiments, the term "electric shaver" should be understood as a "shaving system" including such a separate electronic device.

[0070] Examples of user-related parameters that can be measured by the detection system 87 include the position of the electric shaver 1 on the user's body, the cumulative amount of shaving time that the electric shaver 1 shaves against multiple different areas of the user's body during the shaving process, the speed of movement of the user moving the electric shaver 1 on the user's body, the pressure or force with which the user presses the electric shaver 1 against the body, parameters related to the user's skin properties, and parameters related to the user's hair properties. The mentioned position of the electric shaver 1, the mentioned cumulative amount of shaving time, the mentioned speed of movement, and the mentioned pressure are examples of user-related parameters related to the user's manipulation of the electric shaver 1 relative to the user's body. In other words, in these examples, the value of the user-related parameter depends on how the user manipulates the electric shaver 1 relative to the user's body, such as placing, moving, or pressing. The detection system 87 can be configured and arranged to measure only one user-related parameter or to measure two or more user-related parameters. Therefore, the processor 89 can be configured and arranged to control the second rotation speed ω2 of the outer cutting member 13 depending on only one user-related parameter or depending on two or more user-related parameters.

[0071] In an embodiment of the electric shaver 1 according to the present invention, in which the user-related parameters include the position of the electric shaver 1 on the user's body, the detection system 87 is configured and arranged to measure the position of the electric shaver 1 on the user's body. For this purpose, the detection system 87 may include any suitable detector known to those skilled in the art. As an example, the detection system 87 may include a system for determining the position of the device on the surface of a body part of a subject, such as disclosed by WO2020 / 182698A1 in the name of the applicant. In this example, as shown in Figure 10a, the detection system 87 includes an orientation sensor 95, such as an inertial measurement unit (IMU) sensor, which is arranged in the main housing 3 of the electric shaver 1 (such as Figure 3 ) or in the shaving unit 5 to measure the sequence of 3D orientations of the electric shaver 1 during use and generate a corresponding output signal 3DO. In this example, the detection system 87 also includes a processing unit 97, which is configured to compare the sequence of 3D orientations of the electric shaver 1 with the normal vector on the 3D representation of the user's body or body part (such as the face and neck area) stored in the processing unit 97. The processing unit 97 is also configured to: determine the position of the electric shaver 1 on the body or body part based on the position of the normal vector on the 3D representation according to the comparison, and generate a corresponding output signal LS, which is used as Fig. 9, and is supplied to the processor 89 according to the embodiment of the output signal URP shown in . More details of the detection system are disclosed by WO2020 / 182698A1. In this embodiment, the processor 89 can be configured, for example, to apply a relatively low second rotation speed ω2 when the detection system 87 detects that the electric shaver 1 is present in an area of ​​the user's body where the known skin has a relatively high sensitivity (such as the neck area), and to apply a relatively high second rotation speed ω2 when the detection system 87 detects that the electric shaver 1 is present in an area of ​​the user's body where the known skin has a relatively low sensitivity (such as the cheek area). In this way, the user will experience that the rotation of the outer cutting member 13 is acceptable, regardless of or less affected by the position where the electric shaver 1 actually shaves. Alternatively, the processor 89 can adjust the second rotation speed ω2 based on the detected position of the electric shaver 1 based on different position-related properties (for example, based on the average user's hair properties in different areas of the body). The processing unit 97 of the detection system 87 can be part of the processor 89 or separate from the processor 89, as shown in Figure 10a.

[0072] In another embodiment of the electric shaver 1 according to the present invention, the user-related parameters include the accumulated amount of shaving time of the electric shaver 1 for multiple different areas of the user's body during the shaving process. In this other embodiment, as shown in Figure 10b, the detection system 87 includes an orientation sensor 95 and a processing unit 97, as previously described with reference to the embodiment of Figure 10a, for measuring the position of the electric shaver 1 on the user's body and generating a corresponding output signal LS. In this embodiment, the detection system 87 also includes a timer 99, which is configured to output a timing signal TS. The detection system 87 also includes another processing unit 101, which is configured to determine the accumulated amount of shaving time of the electric shaver 1 for each of the multiple different areas of the user's body based on the output signal LS of the processing unit 97 and the timing signal TS of the timer 99. The other processing unit 101 generates an output signal LCST, which is used as Fig. 9The embodiment of the output signal URP shown in is supplied to the processor 89, and represents the cumulative shaving time of the user's body area actually shaved by the electric shaver 1. In this embodiment, the processor 89 can be configured, for example, to reduce the second rotation speed ω2 of the outer cutting member 13 when the output signal LCST of the other processing unit 101 indicates that the cumulative shaving time of the user's body area actually shaved by the electric shaver 1 exceeds a predefined time threshold. In this way, the increase in skin irritation caused by the rotation of the outer cutting member 13 that may occur when the user shaves the same skin area for too long is limited or prevented. The processing unit 97, the timer 99 and the other processing unit 101 of the detection system 87 can be part of the processor 89 or can be separated from the processor 89, as shown in Figure 10b.

[0073] In another embodiment of the electric shaver 1 according to the present invention, the user-related parameters include the speed of movement of the user moving the electric shaver 1 on his body. In this other embodiment, as shown in Figure 10c, the detection system 87 may include an orientation sensor 95 (as previously described with reference to the embodiments of Figures 10a and 10b) and a processing unit 103. In this embodiment, the orientation sensor 95 is an IMU sensor as previously described. The processing unit 103 is configured to receive an output signal ACC, which is generated by the IMU sensor and represents the measured acceleration of the electric shaver 1. The processing unit 103 is configured to determine the speed of movement of the electric shaver 1 on the user's body based on the measured acceleration, and generate a corresponding output signal MS, which is used as Fig. 9 The processing unit 103 of the detection system 87 may be a part of the processor 89 or may be separated from the processor 89, as shown in FIG10c. The detection system 87 may include: Figure 4A The displacement sensor 105 schematically shown in the figure is arranged in the shaving unit 5, such as an optical displacement sensor known to those skilled in the art, instead of including an IMU sensor. In this case, the processing unit 103 is configured to determine the movement speed of the electric shaver 1 according to the displacement measured by the displacement sensor 105.

[0074] A known problem with electric shavers is that when the user increases the speed of movement of the electric shaver on the body, the hair capture efficiency of the hair cutting unit decreases. To alleviate this problem, in the present embodiment, the processor 89 is configured to increase the second rotational speed ω2 of the outer cutting member 13 of the hair cutting unit 9a, 9b, 9c when the speed of movement of the electric shaver 1 measured by the detection system 87 increases. By increasing the second rotational speed ω2, the hair capture efficiency can be increased, that is, at least within a predefined range of the second rotational speed ω2 depending on the detailed design of the outer cutting member 13, for example, for the embodiment of the outer cutting member 13 shown in Figure 6b, between 0 and 300rpm. The increase in hair capture efficiency achieved by increasing the second rotational speed ω2 can partially compensate or even completely compensate for the decrease in hair capture efficiency caused by the increase in the speed of movement of the electric shaver 1. The processor 89 can be configured to gradually increase the second rotational speed ω2 as the measured speed of movement increases. Alternatively, the processor 89 can be configured to gradually increase the second rotational speed ω2 at a specific threshold of the measured speed of movement. In another example, when the measured movement speed is lower than a first threshold, the second rotation speed ω2 is set to a first predefined value, when the measured movement speed exceeds a second threshold higher than the first threshold, the second rotation speed ω2 is set to a second predefined value higher than the first predefined value, and the second rotation speed ω2 is set to a value between the first predefined value and the second predefined value in proportion to the value of the measured movement speed between the first threshold and the second threshold.

[0075] With respect to this embodiment, the inventors have also found that, in order to achieve the best improvement in hair capture efficiency, the processor 89 must set the second rotation speed ω2 of the outer cutting member 13 of the hair cutting units 9a, 9b, 9c so that the tangential speed VT (as previously defined) of the outer cutting member 13 relative to the central axis 11 of the hair cutting units 9a, 9b, 9c is higher than the motion speed measured by the detection system 87. It was found that most users of electric shavers move the shavers over the body at a speed between 10 cm / s and 30 cm / s. For an embodiment of the outer cutting member 13, it was found that a tangential speed VT of about 14 cm / s (corresponding to ω2=150 rpm) provides the best hair capture efficiency at a motion speed of 10 cm / s. For motion speeds of 20 cm / s and 30 cm / s, it was found that the optimal values ​​of the tangential speed VT of the outer cutting member 13 are about 28 cm / s (corresponding to ω2=300 rpm) and about 38 cm / s (corresponding to ω2=400 rpm), respectively.

[0076] In an embodiment of the electric shaver 1, in which the user-related parameter includes the pressure or force with which the user presses the electric shaver 1 against the body, the detection system 87 is configured and arranged to measure said pressure or force. For this purpose, the detection system 87 may include any suitable detector known to those skilled in the art. As an example, the detection system 87 may include a pressure sensing system, as disclosed in WO2020 / 212276A1 in the name of the applicant. The main components of this known pressure sensing system are schematically shown in Figure 3 10 d , and comprises: a pair of leaf springs 107, by means of which the support structure 7 of the shaving unit 5 is elastically suspended relative to the main housing 3 in a direction parallel to the central axis 109 of the shaving unit 5; a permanent magnet 111 mounted on the support structure 7; and a Hall sensor 113 mounted on the main housing 3 in a position close to the magnet 111. Due to the use of the leaf springs 107, the distance between the permanent magnet 111 parallel to the central axis 109 of the shaving unit 5 and the Hall sensor 113 depends on the pressure exerted on the shaving unit 5 parallel to the central axis 109 of the shaving unit 5. As schematically shown in FIG. 10 d , in this embodiment, the Hall sensor 113 generates an output signal HS representing the magnetic field strength of the magnet 111 measured at the position of the Hall sensor 113, which depends on the distance between the magnet 111 and the Hall sensor 113, and thus on the pressure pressing the shaving unit 5 against the body. As schematically shown in FIG. 10d , in this embodiment, the detection system 87 further comprises a processing unit 115, which is configured to determine the pressure or force pressing the shaving unit 5 against the body based on the output signal HS of the Hall sensor 113, the known magnetic properties of the permanent magnet 111 and the Hall sensor 113, and the known elastic properties of the blade spring 107. The processing unit 115 generates an output signal PF representing the determined pressure or force, which is used as Fig. 9 The embodiment of the output signal URP shown in is supplied to the processor 89. The processing unit 115 of the detection system 87 can be part of the processor 89 or separate from the processor 89, as shown in Figure 10d. More details of the pressure sensing system are disclosed by WO2020 / 212276A1. It is worth noting that the detection system 87 can have a different type of pressure sensor instead of the pressure sensing system described previously, for example, one or more mechanical pressure sensors 117 of a type known to those skilled in the art, which can be arranged on the shaving unit 5, as schematically shown in Figure 4a.

[0077] When the pressure or force increases, the degree to which the skin arches into the hair entry opening 61 of the outer cutting member 13 increases, which may lead to an increase in skin irritation experienced by the user. It has been found that the degree to which the skin arches into the hair entry opening 61 can be reduced by increasing the second rotational speed ω2 of the outer cutting member 13. Therefore, as a first example related to this embodiment, the processor 89 is configured to increase the second rotational speed ω2 when the detection system 87 detects an increase in the pressure or force applied to the shaving unit 5. Thereby, an increase in skin arching and an increase in related skin irritation caused by the increase in the pressure or force can be prevented or limited.

[0078] When the pressure or force increases, the friction between the skin and the rotating outer cutting member 13 increases, which may also lead to an increase in skin irritation experienced by the user. Because the skin friction can be reduced by reducing the second rotation speed ω2 of the outer cutting member 13, in a second example related to the present embodiment, the processor 89 is configured to reduce the second rotation speed ω2 when the detection system 87 detects an increase in the pressure or force applied to the shaving unit 5. Therefore, the increase in skin friction and the increase in related skin irritation caused by the increase in the pressure or force can be prevented or limited. In this embodiment, the electric shaver 1 can be provided with a user interface, by means of which the user can select a preferred way for the processor 89 to adapt the second rotation speed ω2 according to the measured pressure, that is, to control the arching of the skin into the hair entry opening 61 according to the first example described previously, or to control the skin friction according to the second example described previously.

[0079] In an embodiment of the electric shaver 1 according to the present invention, in which the user-related parameters include parameters related to the user's skin properties, the detection system 87 is configured and arranged to measure parameters related to the user's skin properties. In one example, the skin property-related parameter is skin redness, which is a well-known skin property affected by the shaving process. The degree of skin redness is considered to be an indication of the degree of skin irritation caused by the shaving process. In this example, the detection system 87 may have an optical color sensor 119, which is arranged in the shaving unit 5, as schematically shown in Figure 4a, and is configured to detect the degree of skin redness. Alternatively, as schematically shown in Figure 10e, the detection system 87 may have a camera 121, which may be arranged separately from the main housing 3 and the shaving unit 5, for example, in a smartphone. The camera 121 is configured to generate an output signal IMG representing an image of the user's skin. The detection system 87 also includes a processing unit 123, which is configured to analyze the image generated by the camera 121, determine the degree of skin redness based on the analysis, and generate a corresponding output signal SR, which is used as Fig. 910e. The processor 89 is supplied with the embodiment of the output signal URP shown in the figure. In this example, the processor 89 can be configured to reduce the second rotation speed ω2 of the outer cutting member 13 when the detection system 87 measures an increase in skin redness. The processing unit 123 of the detection system 87 can be part of the processor 89 or can be separated from the processor 89, as shown in Figure 10e. In addition to skin redness, the processor 89 can also control the second rotation speed ω2 of the outer cutting member 13 according to other skin properties, in particular when such skin properties are affected by the second rotation speed ω2 of the outer cutting member 13 and / or when such skin properties affect the hair capture efficiency of the outer cutting member 13.

[0080] In an embodiment of the electric shaver 1 according to the present invention, in which the user-related parameters include parameters related to the hair properties of the user, the detection system 87 is configured and arranged to measure the parameters related to the hair properties of the user. In one example, the hair properties are hair properties that may affect the hair capture efficiency of the external cutting member 13 of the hair cutting unit 9a, 9b, 9c. Examples of such hair properties include hair length, hair thickness or hair density on the skin. As schematically shown in Figure 10f, similar to the embodiment shown in Figure 10e, the detection system 87 may have a camera 121, which is configured to generate an output signal IMG representing an image of the user's skin. The detection system 87 also includes a processing unit 125, which is configured to analyze the image generated by the camera 121, determine the hair properties based on the analysis, and generate a corresponding output signal HP, which is used as Fig. 9 10f . The processor 89 is supplied with the output signal URP shown in the embodiment of ...

[0081] As discussed previously, in Figure 3In the embodiment shown in , the drive system 27 of the electric shaver 1 includes a single motor 29 and a transmission system 31, and the motor 29 can rotate the inner cutting member 15 and the outer cutting member 13 of each hair cutting unit 9a, 9b, 9c via the transmission system 31. The use of a single motor 29 in this embodiment makes the structure of the electric shaver 1 relatively simple. In this embodiment, the adjustment of the second rotation speed ω2 of the outer cutting member 13 by the processor 89 will also cause a proportional adjustment of the first rotation speed ω1 of the inner cutting member 15. This adjustment of the first rotation speed ω1 is acceptable in many practical applications, as long as the first rotation speed ω1 remains within the range required for effective hair cutting of the rotating inner cutting member 15. Fig.11 Schematically shown is an alternative embodiment of a drive system 127 of an electric shaver 1 according to the invention, which allows adjusting the second rotation speed ω2 of the outer cutting member 13 independently of the first rotation speed ω1 of the inner cutting member 15. Figure 3 The drive system 27 shown in FIG. 1 corresponds to the part of the embodiment of the electric shaver 1. Fig.11 The drive system 127 and parts of the alternative embodiment of the electric shaver 1 are shown in Fig.11 The corresponding reference numerals are used to indicate the components.

[0082] like Fig.11 As shown in, in the alternative embodiment, the drive system 127 includes a first motor 129 and a second motor 133, the first motor 129 being configured and arranged to rotate the inner cutting member 15 of each hair cutting unit 9a, 9b, 9c around the central axis 11 of the hair cutting unit 9a, 9b, 9c via a first transmission system 131, and the second motor 133 being configured and arranged to rotate the outer cutting member 13 of each hair cutting unit 9a, 9b, 9c around the central axis 11 of the hair cutting unit 9a, 9b, 9c via a second transmission system 135. The first transmission system 131 includes a main shaft 137, which carries a first main gear 33, which is previously referred to as Figure 3 The main shaft 137 is rotatably journaled on the main housing 3 and the support structure 7 of the shaving unit 5 and is arranged to be driven by the first motor 129 via an intermediate gear 139 mounted to the motor shaft 141 of the first motor 129 and an intermediate gear 143 mounted to the main shaft 137. The first main gear 33 is driven by the intermediate gear 139 mounted to the motor shaft 141 of the first motor 129. Figure 3 The second transmission system 135 includes a second main gear 145 mounted to a motor shaft 147 of the second motor 133. The second main gear 145 is connected to each of the three inner cutting members 15 by means of the three pinion gears 39 and the three drive shafts 41 mentioned in the drive system 27 shown in FIG. Figure 3The third main gear 45 mentioned in the drive system 27 shown in FIG. 1 is meshed. Therefore, the second main gear 145 is engaged by the third main gear 45 mentioned in FIG. Figure 3 The third main gear 45 , the countershaft 43 , the fourth main gear 49 , the fifth main gear 53 , the third shaft 51 , the sixth main gear 55 and the three countershafts 57 mentioned in the drive system 27 shown in FIG. 2 are coupled to each of the three outer cutting members 13 .

[0083] When the electric shaver 1 includes an alternative embodiment of the drive system 127, the processor 89 is configured and arranged to control the second motor 133 of the drive system 127 so that the second rotational speed ω2 of the outer cutting member 13 depends on the measured user-related parameters, for example according to the examples discussed previously with reference to Figures 10a-10f. Specifically, the processor 89 can control the second rotational speed ω2 independently of the first rotational speed ω1 of the inner cutting member 15. For example, the processor 89 can control the first motor 129 so as to maintain the first rotational speed ω1 at a constant value, which is optimal for hair cutting by the rotating inner cutting member 15, and the processor 89 can control the second motor 133 so as to adjust the second rotational speed ω2 when the measured user-related parameters change to maintain the hair capture efficiency of the outer cutting member 13 at an optimal level. To this end, as will be clear to a person skilled in the art, the power control module 91 may be configured to independently power the first motor 129 and the second motor 133 based on a first output signal of the processor 89 associated with a first rotational speed ω1 to be achieved by the first motor 129 and a second output signal of the processor 89 associated with a second rotational speed ω2 to be achieved by the second motor 133, respectively. In this alternative embodiment of the drive system 127, independent control of the rotation of the outer cutting member 13 also allows, for example, providing a user input member by means of which the user can turn the rotation of the outer cutting member 13 on or off or select between a plurality of predefined ranges of the second rotational speed ω2 based on user preferences.

[0084] 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 variations may be made thereto without departing from the scope of the invention as defined in the appended claims. The present invention is intended to be interpreted as including all such modifications and variations as long as they are within the scope of the claims or their equivalents. Although the present invention has been illustrated and described in detail in the drawings and the specification, these illustrations and descriptions should be regarded as merely illustrative or exemplary and not restrictive. The present invention is not limited to the disclosed embodiments. The drawings are schematic, details not necessary for understanding the present invention may be omitted, and may not necessarily be drawn to scale.

[0085] Those skilled in the art may understand and implement variations to the disclosed embodiments by studying the drawings, the specification and the appended claims when practicing the claimed invention. In the claims, the word "comprising" does not exclude other steps or elements, and the indefinite article "a" or "an" does not exclude the plurality. Any reference signs in the claims should not be construed as limiting the scope of the invention.

[0086] Unless otherwise explicitly stated, elements and aspects discussed for or in relation to a particular embodiment may be appropriately combined with elements and aspects of other embodiments. Therefore, the mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be fully utilized.

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, 127) configured to rotate the inner cutting member of each hair cutting unit at a first rotational speed (ω1) around the central axis of the hair cutting unit, and to rotate the outer cutting member of each hair cutting unit at a second rotational speed (ω2) around the central axis of the hair cutting unit, and to rotate the inner cutting member and the outer cutting member of each hair cutting unit relative to each other around the central axis of the hair cutting unit; Characterized in that the electric shaver (1) further comprises: a detection system (87) configured and arranged to measure at least one user-related parameter (URP) related to the skin or hair of a user of the electric shaver or to the manipulation of the electric shaver by the user relative to the user's body; and - a processor (89) configured and arranged to control the drive system (27, 127) so that the drive system causes the second rotational speed (ω2) to depend on at least one user-related parameter measured, and the outer cutting member (13) rotates around the central axis (11) of the hair cutting unit (9a, 9b, 9c) at the second rotational speed.

2. An electric shaver (1) according to claim 1, wherein the at least one user-related parameter (URP) comprises at least one of the following: - the position of the electric shaver on the body of the user (LS); - a cumulative amount of shaving time (LCST) of the electric shaver for a plurality of different areas of the user's body during a shaving session; - the speed of movement (MS) at which the user moves the electric shaver over the user's body; - the pressure or force (PF) with which the user presses the electric shaver against the body; - parameters related to the user's skin properties (SR); and - Parameters related to the hair properties of said user (HP).

3. The electric shaver (1) according to claim 2, wherein: - said at least one user-related parameter (URP) comprises said position (LS) of said electric shaver on said user's body, and - the detection system (87) comprises a detector (95, 97) configured and arranged to measure the position of the electric shaver on the body of the user.

4. The electric shaver (1) according to claim 2, wherein: - the at least one user-related parameter (URP) comprises an amount of cumulative shaving time (LCST) of the electric shaver for a plurality of different areas of the user's body during a shaving session; - the detection system (87) comprises a detector (95, 97) configured and arranged to measure the position (LS) of the electric shaver on the body of the user; as well as - The processor (89) is configured to measure the amount of accumulated shaving time of the electric shaver for each of the plurality of different areas of the user's body based on the position of the electric shaver measured by the detector and the timing output (TS) provided by the timer (99).

5. The electric shaver (1) according to claim 2, wherein: - said at least one user-related parameter (URP) comprises said movement speed (MS) of said user moving said electric shaver over said user's body; as well as - the detection system (87) comprises a detector (95, 103; 105, 103) configured and arranged to measure the speed of movement of the electric shaver by the user over the user's body.

6. The electric shaver (1) according to claim 2, wherein: - the at least one user-related parameter (URP) comprises the pressure or force (PF) with which the user presses the electric shaver against the body; and - the detection system (87) comprises a detector (113, 115; 117) configured and arranged to measure the pressure or force with which the user presses the electric shaver against the body.

7. The electric shaver (1) according to claim 2, wherein: - said at least one user-related parameter (URP) comprises a parameter (SR) related to said skin property of said user; and - the detection system (87) comprises a detector (119; 121, 123) configured and arranged to measure a parameter related to the skin property of the user.

8. The electric shaver (1) according to claim 2, wherein: - said at least one user-related parameter (URP) comprises a parameter (HP) related to said hair property of said user; and - The detection system (87) comprises a detector (121, 125) configured and arranged to measure a parameter related to the hair property of the user.

9. An electric shaver (1) according to any one of claims 1 to 8, wherein the drive system (27) comprises a single motor (29), the single motor being 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), and wherein the processor (89) is configured and arranged to control the single motor so that the second rotational speed (ω2) of the outer cutting member depends on the measured user-related parameter (URP).

10. An electric shaver (1) according to any one of claims 1 to 8, wherein the drive system (127) comprises a first motor (129) and a second motor (133), the first motor being configured and arranged to rotate the inner cutting member (15) of each hair cutting unit (9a, 9b, 9c) around the central axis (11) of the hair cutting unit, and the second motor being configured and arranged to rotate the outer cutting member (13) of each hair cutting unit around the central axis of the hair cutting unit, wherein the processor (89) is configured and arranged to control the second motor (133) so that the second rotational speed (ω2) of the outer cutting member depends on the measured user-related parameter (URP).

11. An electric shaver (1) according to any one of claims 1 to 10, wherein the drive system (27, 127) is configured to rotate the inner cutting member (15) of each hair cutting unit (9a, 9b, 9c) around the central axis (11) of the hair cutting unit in a first rotation direction (R1), and to rotate the outer cutting member (13) of each hair cutting unit around the central axis of the hair cutting unit in a second rotation direction (R2) opposite to the first rotation direction, and wherein the second rotation speed (ω2) of the outer cutting member is lower than the first rotation speed (ω1) of the inner cutting member.

12. An electric shaver (1) according to claim 11, wherein the hair entry opening (61) of the outer cutting member (13) of each hair cutting unit (9a, 9b, 9c) includes a V-shaped opening portion (63) pointing to 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 is such that the tangential speed (VT) of the outer cutting member relative to the central axis (11) is in the range between 7.5 cm / s and 50 cm / s, more preferably in the range between 11.25 cm / s and 30.0 cm / s, and the tangential speed is measured at the radial position (RC) of the center base point (65) of the V-shaped opening portion relative to the central axis.

13. An electric shaver (1) according to claim 12, wherein the hair entry opening (61) extends a first radial distance (RD1) in a radial direction relative to the center 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, and the second radial distance is at least 50% of the first radial distance.

14. An electric shaver (1) according to claim 12 or 13, wherein the hair entry opening (61) of the outer cutting member (13) of each hair cutting unit (9a, 9b, 9c) further includes a radially inner straight opening portion (69a) and a radially outer straight opening portion (69b), the radially inner straight opening portion being connected to the V-shaped opening portion (63) at a first end (71a) of the V-shaped opening portion facing the central axis (11) of the hair cutting unit, and the radially outer straight opening portion being 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.

15. The electric shaver (1) according to any one of claims 12 to 14, wherein a V angle (α) of the V-shaped opening portion (63) of the hair entrance opening (61) is in the range of 60° to 135°.

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