Rotation of the external cutting member of the shaving unit

Abstract

In the shaving unit for an electric shaver, the hair-cutting unit 30 has a housing 40 having a central axis Ac, an external cutting member 31 supported by the housing 40, and an internal cutting member 32 covered by the external cutting member 31. The external cutting member 31 is rotatable about the central axis Ac relative to the housing 40, and the internal cutting member 32 is rotatable about the central axis Ac relative to the external cutting member 31. The hair-cutting unit 30 further has a transmission unit 60, which includes a first transmission member 61 accommodated in the housing 40 and attached to the internal cutting member 32, a second transmission member 62 attached to the external cutting member 31, and at least one intermediate transmission member 63, 64, 65. The first transmission member 61 is coupled to the second transmission member 62 via the intermediate transmission member.

Description

[Technical Field]

[0001] The present invention relates to a shaving unit for an electric shaver, comprising a support member and at least two hair-cutting units supported by the support member, each hair-cutting unit comprising: a housing having a central axis; an external cutting member supported by the housing and including an annular shaving area with a plurality of hair entry ports, the external cutting member being rotatable about a central axis relative to the housing; an inner cutting member surrounded by the outer cutting member, rotatable about a central axis relative to the outer cutting member, and having a coupling member; The shaving unit has a respective drive shaft for each hair-cutting unit that is releasably coupled to the coupling member of the internal cutting member for rotating the internal cutting member about the central axis relative to the external cutting member.

[0002] Furthermore, the present invention relates to an electric shaver, which comprises: a main body that houses a motor; The shaving unit has a support member coupled to the main body. [Background technology]

[0003] Electric shavers and shaving units for electric shavers are well known. Electric shavers are generally used to shave body hair, which may be facial hair, and are powered from a mains power source and / or an electrical energy storage device such as a battery.

[0004] In a commonly known setup, a shaving unit comprises an assembly of a support member and at least two hair-cutting units supported by the support member. Conventionally, each hair-cutting unit comprises a combination of an external cutting member having a shaving area with a hair entry opening as a non-driven element and an internal cutting member as a driven element, at least the internal cutting member having one or more cutting edges. In such a case, using a shaving unit incorporated in an electric shaver involves placing the shaving unit in an operating mode, in which the internal cutting member of the hair-cutting unit is actually moved, and the shaving unit is moved over the skin in such a manner that the shaving area of ​​the external cutting member of the hair-cutting unit faces and contacts the skin. During this process, hairs protruding from the skin are captured in the space of the housing of the hair-cutting unit, where the hairs are brought into contact with the external cutting member at the position of the hair entry opening and are cut when they meet the cutting edge of the internal cutting member. Summary of the Invention [Problem to be solved by the invention]

[0005] For a shaving unit of the type having the above-mentioned combination of an external cutting member and an internal cutting member in each of the at least two hair-cutting units, it is also proposed to rotate the external cutting member relative to a fixed portion of the shaving unit's periphery. This can improve the hair-catching ability of the at least two hair-cutting units because the skin is allowed to encounter more open areas of the external cutting member, i.e., more hair entry points. Known measures aimed at achieving good hair-catching ability of the at least two hair-cutting units rely on stimulating user behavior, particularly behavior involving moving the shaving unit in a circular motion on the skin. However, it is often observed that users do not perform the circular motion in the correct manner, or even do not perform the circular motion at all. Therefore, rather than trying to force the user to perform a specific action, it is desirable to structurally adjust the shaving unit, and having a rotating external cutting member is just such an adjustment. However, the presence of the required additional drive element may result in an increased size of the at least two hair-cutting units and may also reduce the skin-contour-following ability of the at least two hair-cutting units.

[0006] Patent document CH376798A discloses an electric shaver with a single hair-cutting unit. The hair-cutting unit has an external foil-type cutting member rotatably mounted on the shaver's main housing by ball bearings, so that the external cutting member is rotatable around the central axis of the hair-cutting unit. The hair-cutting unit also has an internal cutting member attached to a drive shaft driven by a motor, so that the internal cutting member is rotatable around the central axis by the motor. The motor can rotate the external cutting member at a relatively low speed around the central axis via a transmission mechanism disposed between the drive shaft and the external cutting member. The transmission mechanism includes a first gear wheel attached to the drive shaft, a second gear wheel stationarily mounted on the inner surface of the main housing, a third gear wheel stationarily mounted on the inner surface of the external cutting member, and a pair of diametrically opposed intermediate gear wheels that engage with the first, second, and third gear wheels, respectively.

[0007] The object of the present invention is to provide a shaving unit in which at least two hair-cutting units each have a rotatable external cutting member, but which does not have the above-mentioned drawbacks, in particular the increased size and reduced skin contouring ability of at least two hair-cutting units. [Means for solving the problem]

[0008] The present invention provides a shaving unit for an electric shaver, the shaving unit having a support member and at least two hair-cutting units supported by the support member, each hair-cutting unit comprising: a housing having a central axis; an external cutting member supported by the housing and including an annular shaving area with a plurality of hair entry ports, the external cutting member being rotatable about a central axis relative to the housing; an inner cutting member covered by the outer cutting member and rotatable about a central axis relative to the outer cutting member, the inner cutting member having a coupling member; the shaving unit has, for each hair-cutting unit, a respective drive shaft releasably coupled to the coupling member of the internal cutting member for rotating the internal cutting member about the central axis relative to the external cutting member; Each hair-cutting unit has a transmission unit by means of which the external cutting member is rotatable about a central axis relative to the housing, said transmission unit being accommodated in the housing of said hair-cutting unit, which comprises: a first transmission member attached to the internal cutting member so as to be rotatable therewith about the central axis; a second transmission member attached to the external cutting member so as to be rotatable therewith about the central axis; and at least one intermediate transmission member through which the first transmission member is coupled to the second transmission member to convert rotation of the internal cutting member about the central axis into rotation of the external cutting member about the central axis.

[0009] From the above definition of the shaving unit according to the present invention, the shaving unit has, for each hair-cutting unit, a separate transmission unit used to rotate the external cutting member of the respective hair-cutting unit, the transmission unit being accommodated in the housing of the respective hair-cutting unit and comprising an assembly of a first transmission member, a second transmission member and at least one intermediate transmission member. The first transmission member is attached to the internal cutting member of the respective hair-cutting unit, and the second transmission member is attached to the external cutting member of the respective hair-cutting unit. Thus, in each respective hair-cutting unit, the transmission unit is configured to cause the movement of the external cutting member based on the movement of the internal cutting member. In other words, in each respective hair-cutting unit, the external cutting member is powered by the internal cutting member via the transmission unit in the respective hair-cutting unit during operation. This means that no separate drive train is needed outside the hair-cutting unit to rotate the external cutting member in addition to the internal cutting member, but rather the existing drive train for driving the internal cutting member is extended. This provides the possibility of having a desired rotatable external cutting member without having to increase the dimensions of the shaving unit, at least to the extent that a significantly larger appearance of the shaving unit is obtained. Due to the fact that for each individual hair-cutting unit, the transmission unit is accommodated in the hair-cutting unit housing, it is achieved that any skin-contour-following pivotal movement of the hair-cutting unit is not hindered in any way. In particular, the hair-cutting unit housing including the transmission unit accommodated therein can be configured to be pivotable relative to the support member of the shaving unit, which allows each hair-cutting unit of the shaving unit to individually follow any local skin contour during the shaving process without affecting the rotational drive of the external cutting member of the hair-cutting unit.

[0010] When a shaving unit has at least two hair-cutting units, having the option to follow the contours of the skin is particularly appropriate, since otherwise the user would only be able to move the at least two hair-cutting units over the skin in a fixed, predetermined structural relationship. When each of the at least two hair-cutting units of the shaving unit is pivotable relative to the support member about at least one pivot axis, it is advantageous if the coupling member of the internal cutting member of each hair-cutting unit, by which the internal cutting member is releasably coupled to the respective drive shaft associated with the hair-cutting unit, is configured to maintain rotational coupling with the respective drive shaft during pivoting of the hair-cutting unit about at least one pivot axis. Thus, in a drive train extending from the drive shaft via a transmission unit to the external cutting member, the transmission unit is entirely disposed between the coupling member and the external cutting member, which allows the transmission unit to pivot relative to the respective drive shaft together with the internal and external cutting members. For example, each of the individual drive shafts may have a coupling head, in which case the coupling member of the internal cutting member of each hair-cutting unit has a cavity that accommodates the coupling head of the individual drive shaft associated with the hair-cutting unit, the surfaces of the coupling head and the cavity being configured to slide against each other during pivoting of the hair-cutting unit around at least one pivot axis, this does not alter the fact that the present invention covers other options regarding the manner in which pivoting movement of the hair-cutting unit is enabled.

[0011] In order to prevent increased skin irritation from the rotating external cutting members in view of the normal range of rotational speed of the internal cutting members, it is practical for the transmission unit of each hair-cutting unit in the shaving unit according to the invention to be configured to reduce the speed in the direction from the internal cutting members to the external cutting members, i.e., the transmission unit is configured to convert the rotation of the internal cutting members around the central axis at a first rotational speed into the rotation of the external cutting members around the central axis at a second rotational speed, said second rotational speed being lower than said first rotational speed. For example, it is practical if the speed reduction rate of the transmission unit is such that during normal operation of the shaving unit, the external cutting members operate at a rotational speed in the range of about 40 rpm to 120 rpm, while the rotational speed of the internal cutting members is as high as a speed in the range of about 2,000 rpm to 2,500 rpm.

[0012] Consumer testing has shown that when a shaving unit including a hair-cutting unit in which the external cutting member rotates at a speed ranging from about 40 rpm to 120 rpm during operation is used on a subject's skin for shaving, the average user finds the shaving action comfortable. At the same time, as an advantageous result of rotating the external cutting member, the hair-capturing efficiency of the hair-cutting unit is less dependent on the manner in which the user moves the shaving unit over the skin, especially in areas where it is difficult to achieve the recommended circular motion of the shaving unit over the skin.

[0013] In a practical embodiment of the shaving implement according to the invention, the transmission unit comprises an arrangement of meshing gear wheels. In this respect, the transmission unit in particular comprises: the first transmission member has a first gear wheel disposed coaxially with the central axis on the coupling member of the internal cutting member; the second transmission member has a second gear wheel disposed coaxially with the central axis inside the annular flange portion of the external cutting member; At least one intermediate transmission member has at least one intermediate gear wheel through which the first gear wheel is coupled to the second gear wheel, and each intermediate gear wheel has a rotation bearing arranged on the housing.

[0014] The arrangement of the second gear wheel inside the annular flange of the external cutting member offers many possibilities for realizing a compact design of the transmission unit: the annular flange is part of the external cutting member of a conventional cup-like design, and the dimensions and other characteristics of said flange can be easily adapted to better fit the second gear wheel.

[0015] Further advantageous options that exist in the context of the present invention and allow for a compact design of the transmission unit include 1) when the transmission unit has at least two intermediate gear wheels, and when the rolling bearings of the individual intermediate gear wheels are included in an integral housing part, and 2) when at least one intermediate transmission member is designed to have a pair of intermediate gear wheels in a stacked configuration.

[0016] A practical example of an alternative to gear wheels is a belt drive. In such a case, the first and second transmission members can be designed as wheels engaging with a belt of the belt drive, the belt constituting an intermediate transmission member of the transmission unit. Furthermore, the transmission unit can also have a friction wheel, in which case damage as a result of high loads on the hair-cutting unit can be prevented due to slippage of the friction wheel.

[0017] It should be noted that with regard to the housing of each hair-cutting unit, known practical options are also applicable in the context of the present invention, namely the option where the housing has a skin-contacting surface that surrounds the external cutting member of the hair-cutting unit.

[0018] As mentioned above, the present invention also relates to an electric shaver, which comprises: a main body that houses a motor; The shaving unit has a support member coupled to the main body.

[0019] In the context of the electric shaver according to the present invention, it is particularly practical if the support member of the shaving unit has a connecting member by means of which the shaving unit is releasably connected to the main body. Furthermore, the connecting member can accommodate a main drive shaft which is coupled to the motor when the shaving unit is connected to the main body, and the shaving unit can have a transmission system which converts the rotation of the main drive shaft into the rotation of the individual drive shafts of each hair-cutting unit of the shaving unit. In such a case, the main drive shaft may be configured to extend in a position where its longitudinal axis coincides with the central axis of the housing of the shaving unit, although this is not essential in the context of the present invention.

[0020] The above-mentioned and other aspects of the invention will be apparent from and will be explained with reference to the following detailed description of a practical embodiment of a shaving unit having three hair-cutting units, each hair-cutting unit having a housing, an outer cutting member rotatable relative to the housing, an inner cutting member rotatable relative to the housing, and a transmission unit for transmitting rotational motion from the inner cutting member to the outer cutting member. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a diagrammatic perspective view of an electric shaver having a shaving unit and a main body according to an embodiment of the present invention; [Figure 2] FIG. 2 shows a schematic cross-sectional view of a hair-cutting unit of a shaving unit. [Figure 3] 10 shows diagrammatically another cross-sectional view of the hair-cutting unit and how it is organized into the larger entity of the shaving unit; FIG. [Figure 4] FIG. 2 is a perspective bottom view of the hair cutting unit, showing the housing portion. [Figure 5] FIG. 2 is a perspective bottom view of the hair cutting unit, with the housing portion omitted. [Figure 6] 10A and 10B are diagrams showing the configuration of a transmission unit of the hair cutting unit; DETAILED DESCRIPTION OF THE INVENTION

[0022] The invention will now be explained in more detail with reference to the figures, in which like or similar parts are designated with the same reference numerals.

[0023] The present invention relates to a shaving unit 10 configured to be used in an electric shaver 1. With reference to Figure 1, it should be noted that the shaving unit 10 comprises a support member 20 and three hair-cutting units 30 supported by the support member 20. In the context of the present invention, the number of hair-cutting units 30 can be freely selected and does not necessarily have to be three, provided that the number is at least two.

[0024] FIG. 1 shows how a shaving unit 10 is combined with a main body 2 in an electric shaver 1, with a support member 20 of the shaving unit 10 being connected to the main body 2. The main body 2 may be of any suitable design and is only diagrammatically indicated by a dashed line. The electric shaver 1 is a handheld device, and it is assumed that, in order to perform a shaving action on the skin with the shaver 1, a user of the shaver 1 holds the main body 2, places the shaving unit 10 on the skin, and moves the shaving unit 10 over the skin. The electric shaver 1 is shown in a normal orientation, which is an orientation in which the shaving unit 10 is located above the main body 2. This orientation forms the basis for the terms used herein to indicate the positional relationship of elements. Nevertheless, it should be noted that the definitions of the shaving unit 10 and the electric shaver 1 in the appended claims are not limited to this orientation, i.e., the definitions are applicable to the shaving unit 10 and the shaver 1 in any possible orientation.

[0025] The shaving unit 10 forms part of the electric shaver 1, by which the action of cutting hair from the skin can actually take place, while the main housing 2 can serve to house a motor 3 that drives the elements of the shaving unit 10 involved in such action. The main housing 2 can further include means for powering the motor 3, such as a rechargeable battery 4.

[0026] As is known per se in the field of electric shavers, it is practical if the shaving unit 10 and the main housing 2 are releasably connectable to one another and the support member 20 of the shaving unit 10 has a connecting member 21 which accommodates a main drive shaft 22 which is coupled to the motor 3 in the connected state to the body 2 of the shaving unit 10. This option is shown in Figure 1, where both the main drive shaft 22 and the output shaft 5 of the motor 3 are shown in dashed lines.

[0027] In the following, a further description of the setup of the hair-cutting unit 30 of the shaving unit 10 is provided. As can be seen from the cross-sectional view shown in Figure 2, the hair-cutting unit 30 has a housing 40 having a central axis Ac, an outer cutting member 31 supported by the housing 40 and surrounded by a skin-contacting surface 41 of the housing 40, and an inner cutting member 32 covered by the outer cutting member 31. The outer cutting member 31 has an annular shaving area 33 with a plurality of hair entry openings. Note that for clarity, the hair entry openings are omitted from the figures. The inner cutting member 32 is rotatable about the central axis Ac relative to the outer cutting member 31. When the electric shaver 1 is operated to perform a shaving operation, and both the skin-contacting surface 41 of the housing 40 and the shaving area 33 of the external cutting member 31 are in contact with the skin, hairs trapped in the hair entry openings in the shaving area 33 of the external cutting member 31 as the shaving unit 10 is moved over the skin are cut by the internal cutting members 32 which are driven to perform a rotational movement relative to the external cutting member 31 during operation. In this regard, it is noted that the shaving unit 10 has an individual drive shaft 34 for each hair-cutting unit 30, and in each hair-cutting unit 30, the individual drive shaft 34 is releasably coupled to the internal cutting member 32 by a coupling member 35 of the internal cutting member 32. The shaving unit 10 further comprises a transmission system 50 which converts rotation of the main drive shaft 22 into rotation of the individual drive shaft 34 of each hair-cutting unit 30 of the shaving unit 10. It should be noted that such a transmission system 50 may have multiple gear wheels, for example, one such gear wheel is shown in FIG.

[0028] A notable feature of the shaving unit 10 is that the external cutting member 31 is rotatable about a central axis Ac relative to the housing 40; The hair-cutting unit 30 has a transmission unit 60 by means of which this feature of the external cutting member 31 is actually realized. As best shown in Figures 4, 5 and 6, the transmission unit 60 is housed within the housing 40 of the hair-cutting unit 30, which is a first transmission member 61 attached to the internal cutting member 32 so as to be rotatable therewith about a central axis Ac; a second transmission member 62 attached to the external cutting member 31 so as to be rotatable together with the external cutting member 31 about the central axis Ac; It has three intermediate transmission members 63, 64, 65, through which the first transmission member 61 is connected to the second transmission member 62, and rotation of the internal cutting member 32 around the central axis Ac is converted into rotation of the external cutting member 31 around the central axis Ac.

[0029] Based on this configuration, when the inner cutting member 32 is rotationally driven, all of the transmission members 61 , 62 , 63 , 64 , 65 are also rotationally driven, so that the rotational movement of the inner cutting member 32 brings about the rotational movement of the outer cutting member 31 .

[0030] In the context of the present invention, the number of intermediate transmission members 63, 64, 65 can be freely selected and does not necessarily have to be three, as long as the number is at least one. In this embodiment, the intermediate transmission members 63, 64, 65 are arranged below the internal cutting member 32. Furthermore, in this embodiment, the first transmission member 61 has a first gear wheel arranged coaxially with the central axis Ac on the connecting member 35 of the internal cutting member 32, and the second transmission member 62 has a second gear wheel arranged coaxially with the central axis Ac inside the annular flange portion 36 of the external cutting member 31, and the intermediate transmission members 63, 64, 65 have intermediate gear wheels through which the first gear wheel is coupled to the second gear wheel. In particular, in this embodiment, each of the intermediate transmission members 63, 64, 65 has a pair of gear wheels in a stacked configuration. As best seen in FIG. 4 , the rotary bearings 42, 43, 44 of the individual intermediate transmission members 63, 64, 65 are included in the integral housing portion 45, and the transmission members 63, 64, 65 are mounted to the housing portion 45 by being rotatably disposed on the rotary bearings 42, 43, 44, while the positions of the transmission members 63, 64, 65 in the direction of the central axis Ac are fixed.

[0031] It would be practical if, during operation, the external cutting member 31 could be rotated at a significantly slower speed than the internal cutting member 32, resulting in a more comfortable and effective hair cutting process. From this perspective, it would be practical if the transmission unit 60 was designed to reduce the rotational speed in the direction from the internal cutting member 32 towards the external cutting member 31. For example, in order to set a rotational speed of 100 rpm of the external cutting member 31 to the normal value of the rotational speed of the internal cutting member 32, the speed reduction ratio could be in the range of about 20-25.

[0032] In this embodiment, in order to enable the hair-cutting units 30 to follow the skin contours, each hair-cutting unit 30 is pivotally arranged on the support member 20. The coupling member 35 of the internal cutting member 32 is configured to maintain rotational coupling to the respective drive shaft 34 of the internal cutting member 32 in each possible pivot position of the hair-cutting unit 30 relative to the support member 20. To that end, the coupling member 35 has a cavity 37 that receives the coupling head 38 of the respective drive shaft 34, and the shapes and dimensions of the coupling head 38 and the cavity 37 relative to each other are selected so that the surfaces of the coupling head 38 and the cavity 37 slide over each other during pivoting of the hair-cutting unit 30 relative to the support member 20. Due to their arrangement on the internal cutting member 31, the external cutting member 32 and the housing 40, respectively, the individual transmission members 61, 62, 63, 64, 65 of the transmission unit 60 do not interfere with any other elements of the hair-cutting unit 30 during pivoting, so that the ability to rotate the external cutting member 31 relative to the housing 40 does not impair the skin contour following ability of the hair-cutting unit 30. Furthermore, the coupling members 35 provide a releasable coupling between the internal cutting member 31 and each drive shaft 34 in that the coupling head 38 of each drive shaft 34 can be moved out of the cavity 37 of the coupling member 35 by moving the coupling member 35 axially away from the respective drive shaft 34, as is known in the art.

[0033] The scope of the present invention is not limited to the above examples, and it will be apparent to those skilled in the art that several modifications and variations thereof are possible without departing from the scope of the present invention as defined in the appended claims. It is intended that the present invention be construed as including all such modifications and variations insofar as they come within the scope of the claims or their equivalents. Although the present invention has been illustrated and described in detail in the drawings and description, such illustration and description are for illustrative or exemplary purposes only and are not restrictive. The present invention is not limited to the disclosed embodiments. The drawings are schematic, in which details not necessary for understanding the invention may be omitted and are not necessarily drawn to scale.

[0034] Variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the figures, the description, and the appended claims. In the claims, the word "comprising" does not exclude other steps or elements, and the indefinite article "a" or "an" does not exclude a plurality. Any reference signs in the claims should not be construed as limiting the scope of the invention.

[0035] Elements and aspects discussed for or in connection with a particular embodiment can be combined with elements and aspects of other embodiments as appropriate, unless otherwise expressly stated. Thus, the mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

[0036] The terms "having" and "including" as used herein will be understood by those skilled in the art to cover the term "consisting of." Thus, the terms "having" or "including" may mean "consisting of" in one embodiment, but may mean "including / having / comprising at least the specified species and, optionally, one or more other species" in another embodiment.

[0037] Notable aspects of the present invention can be summarized as follows: In a shaving unit 10 for an electric shaver 1, a hair-cutting unit 30 of the shaving unit 10 has a housing 40 having a central axis Ac, an external cutting member 31 supported by the housing 40, and an internal cutting member 32 covered by the external cutting member 31. The external cutting member 31 is rotatable about the central axis Ac relative to the housing 40, and the internal cutting member 32 is rotatable about the central axis Ac relative to the external cutting member 31. The hair-cutting unit 30 further has a transmission unit 60, which is accommodated in the housing 40 and includes a first transmission member 61 attached to the internal cutting member 32, a second transmission member 62 attached to the external cutting member 31, and at least one intermediate transmission member 63, 64, 65. The first transmission member 61 is coupled to the second transmission member 62 via an intermediate transmission member, and the rotation of the inner cutting member 32 around the central axis Ac is converted into the rotation of the outer cutting member 31 around the central axis Ac.

Claims

1. A shaving unit for an electric shaver, comprising: a support member; and at least two hair-cutting units supported by the support member, each hair-cutting unit comprising: a housing having a central axis; an external cutting member supported by the housing and including an annular shaving area with a plurality of hair entry ports, the external cutting member rotatable about the central axis relative to the housing; an inner cutting member surrounded by the outer cutting member and rotatable about the central axis relative to the outer cutting member, the inner cutting member having a coupling member; the shaving unit has, for each hair-cutting unit, a respective drive shaft coupled to the coupling member of the internal cutting member for rotating the internal cutting member about the central axis relative to the external cutting member; Each hair-cutting unit has a transmission unit, which allows the external cutting member to rotate about the central axis relative to the housing, and the transmission unit is accommodated in the housing of the hair-cutting unit, and the transmission unit comprises: a first transmission member attached to the internal cutting member so as to be rotatable therewith about the central axis; a second transmission member attached to the external cutting member so as to be rotatable therewith about the central axis; and at least one intermediate transmission member, wherein the first transmission member is coupled to the second transmission member via the intermediate transmission member, and rotation of the internal cutting member about the central axis is converted into rotation of the external cutting member about the central axis.

2. each hair-cutting unit is pivotable relative to said support member about at least one pivot axis; 2. The shaving unit of claim 1, wherein the coupling member of the internal cutting member of each hair-cutting unit maintains a rotational coupling with a respective drive shaft associated with the hair-cutting unit while the hair-cutting unit pivots about the at least one pivot axis.

3. Each individual drive shaft has a coupling head; the coupling member of the internal cutting member of each hair-cutting unit has a cavity for receiving the coupling head of a respective drive shaft associated with the hair-cutting unit; 3. The shaving unit of claim 2, wherein the coupling head and the cavity surface slide against each other during pivoting of the hair-cutting unit about the at least one pivot axis.

4. 2. The shaving unit of claim 1, wherein the transmission unit converts rotation of the internal cutting member about the central axis at a first rotational speed into rotation of the external cutting member about the central axis at a second rotational speed, the second rotational speed being lower than the first rotational speed.

5. 5. The shaving unit of claim 4, wherein the first rotational speed is in the range of about 20 to 25 times the second rotational speed.

6. 6. The shaving unit according to claim 1, wherein the transmission unit drives the external cutting member at a rotational speed in the range of about 40 rpm to about 120 rpm.

7. In the transmission unit, the first transmission member has a first gear wheel disposed coaxially with the central axis and on a coupling member of the internal cutting member; the second transmission member has a second gear wheel disposed inside the annular flange portion of the outer cutting member and coaxially disposed with respect to the central axis; 6. A shaving unit according to claim 1, wherein the at least one intermediate transmission member has at least one intermediate gear wheel, through which the first gear wheel is coupled to the second gear wheel, and each intermediate gear wheel has a rotation bearing arranged on the housing.

8. 8. A shaving unit according to claim 7, wherein the transmission unit comprises at least two intermediate gear wheels, the rotation bearings of the individual intermediate gear wheels being included in an integral housing part.

9. 8. The shaving apparatus of claim 7, wherein in the transmission unit, the at least one intermediate transmission member comprises a pair of intermediate gear wheels in a stacked configuration.

10. 6. A shaving unit according to any preceding claim, wherein the housing of each hair-cutting unit has a skin-contacting surface surrounding the external cutting member of the hair-cutting unit.

11. An electric shaver, a main body that houses a motor; 6. An electric shaver comprising a shaving unit according to claim 1, wherein the support member of the shaving unit is coupled to the main body.

12. The support member of the shaving unit has a connecting member, and the connecting member allows the shaving unit to be connected to the main body; the connecting member accommodates a main drive shaft that is coupled to the motor when the shaving unit is connected to the main body; 12. The electric shaver of claim 11, wherein the shaving unit comprises a transmission system that converts rotation of the main drive shaft into rotation of individual drive shafts of each hair-cutting unit of the shaving unit.

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