Electric shaver

Abstract

To provide a shaving device capable of generating comfortable warming feeling by adding heat to a skin.SOLUTION: An electric shaving device 200 comprises: a first hair cutting unit 150; a first inner cutting member 252; and a first outer cutting member 152. The first inner cutting member 252 is movable with respect to the first outer cutting member 152, and the first outer cutting member 152 is configured to come into contact with a skin 204 during use. The electric shaving device 200 further comprises a second outer cutting member 162 configured to come into contact with the skin 204 during the use, and a bipolar wireless frequency RF generator unit 120 configured to apply a RF voltage of a first polarity to the first outer cutting member 152. The first outer cutting member 152 is configured as a whole to transmit the RF voltage of the first polarity, and the bipolar wireless frequency RF generator unit 120 is further configured to apply a RF voltage of a second polarity to the second outer cutting member 162.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to an electric shaver, and more particularly to an electric shaver including a radio frequency (RF) generator unit for heating the skin during use.

Background Art

[0002] It is generally recognized that the application of heat to the skin within a certain temperature range, for example from about 38°C to 40°C, can evoke a pleasant warm sensation. Methods of warming the skin include applying a hot towel, steam, infrared rays, etc. to the skin. Integrating a skin warming unit into a personal care device generally improves the sensory experience of the user while performing a personal care routine.

[0003] One personal care device that employs a skin warming unit is an electric shaver. Electric shavers including heated mechanical elements are known, and these mechanical elements can provide warmth to the skin via heat conduction during shaving. The warmth creates comfort and improves the user experience.

[0004] Another method of warming the skin is the use of deep dermal heating using radio frequency (RF) energy. The use of RF energy is different from mechanical elements that provide heating using heat conduction. In the application of RF heating, two electrodes are applied to the skin, each applying RF energy charged in opposite directions to the skin. This creates an electric field in the skin between the two electrodes. RF energy can penetrate deeper into the skin than heat transfer by heated mechanical elements, and thus heating can be applied to a relatively large area of the skin. Heating can be applied throughout the depth of penetration without relying on the thermal conductivity of both the heat applicator and the skin as required by the use of heated mechanical elements.

[0005] The use of RF energy to heat the skin is incorporated into some beard trimming devices. For example, US8,516,706 discloses a blade razor in which a blade or a separate electrode adjacent to the blade conducts RF energy to heat the skin. US2015 / 133906 discloses another example in which a shaving cap of an electric shaver includes a plurality of negatively charged electrodes. The electrodes are separated by an insulating member that is part of the shaving cap. SUMMARY OF THE INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION

[0006] Thus, while shaving devices are available that can apply heat to the skin using RF energy, the known art suffers from drawbacks. For example, it is known that the RF electric field density is inversely proportional to the geometric size of the conductive electrode and, in particular, the size of the electrode portion that contacts the skin. Accordingly, the use of a pointed blade as an electrode, or the use of a conductor of similar dimensions with a very small skin contact area, can generate a high-energy RF field. For example, the sharp edge or corner of a blade that contacts the skin can result in a current concentration that generates a high-energy RF field in the skin. A high-energy RF field can generate hot spots, which can result in an uncomfortable or even painful heat sensation for the user. As another drawback, the use of a plurality of small electrodes in the shaving cap of an electric shaver results in a small distance between the electrodes. As a result, heating is concentrated in a small volume of skin under the electrodes, resulting in only partial warming of the skin and not eliciting a strong warming experience. Accordingly, configuring a shaving device with appropriately sized electrodes to heat the skin is difficult, at least in part, due to the limited area available for configuring such electrodes in the skin contact area of the shaving device.

[0007] Accordingly, there is a need for an improved shaving device that can apply heat to the user's skin using RF energy and elicit a comfortable warming sensation. MEANS FOR SOLVING THE PROBLEM

[0008] According to the present invention, there is provided an electric shaver having a first hair cutting unit comprising a first inner cutting member and a first outer cutting member configured to cover the first inner cutting member, the first inner cutting member being movable relative to the first outer cutting member, the first outer cutting member having a first skin contact area including a first plurality of hair entry openings, the first skin contact area being configured to contact the skin during use. The electric shaver further has a second skin contact area configured to contact the skin during use and a bipolar radio frequency (RF) generator unit configured to apply an RF voltage of a first polarity to the first outer cutting member, the entire first outer cutting member being configured to conduct the RF voltage of the first polarity, the bipolar RF generator unit being further configured to apply an RF voltage of a second polarity to the second skin contact area.

[0009] In some examples, the electric shaver further has a second hair cutting unit comprising a second inner cutting member and a second outer cutting member configured to cover the second inner cutting member, the second inner cutting member being movable relative to the second outer cutting member, the second outer cutting member including the second skin contact area and including a second plurality of hair entry openings provided in the second skin contact area, the entire second outer cutting member being configured to conduct the RF voltage of the second polarity. In some examples, the first skin contact area is annular, the first inner cutting member is rotatable relative to the first outer cutting member, the second skin contact area is annular, and the second inner cutting member is rotatable relative to the second outer cutting member.

[0010] In some examples, the electric shaver further has a third hair cutting unit, which includes a third internal cutting member and a third external cutting member configured to cover the third internal cutting member, where the third internal cutting member is movable relative to the third external cutting member, and the third external cutting member has a third skin contact area including a plurality of third hair entry openings, and the bipolar RF generator unit is configured to apply a voltage of a first polarity to the third external cutting member, and the entire third external cutting member is configured to conduct an RF voltage of the first polarity.

[0011] In some examples, the second hair cutting unit is disposed between the first hair cutting unit and the third hair cutting unit.

[0012] In some examples, the first external cutting member and the second external cutting member each have a shaving foil extending parallel to the longitudinal direction, and the first internal cutting member and the second internal cutting member are each configured to linearly reciprocate parallel to the longitudinal direction relative to the first external cutting member and the second external cutting member. In some examples, the third external cutting member has a shaving foil extending parallel to the longitudinal direction, and the third internal cutting member is configured to linearly reciprocate parallel to the longitudinal direction relative to the third external cutting member.

[0013] In some examples, the first skin contact area is annular, the first internal cutting member is rotatable relative to the first external cutting member, and the first hair cutting unit further has a first cover element including the second skin contact area, and the first cover element is disposed on the first external cutting member at a central position relative to the first skin contact area, such that the first skin contact area surrounds the second skin contact area, and the first cover element is electrically insulated from the first external cutting member. In some examples, the first cover element is disk-shaped. In some examples, the entire first cover element can be configured to conduct an RF voltage of a second polarity.

[0014] In some examples, the electric shaver further has a second hair cutting unit, the second hair cutting unit having a second internal cutting member and a second external cutting member configured to cover the second internal cutting member, the second internal cutting member being rotatable relative to the second external cutting member, the second external cutting member having an annular-shaped third skin contact area and a plurality of second hair entry openings, the third skin contact area contacting the skin during use, the second hair cutting unit further having a second cover element including a fourth skin contact area configured to contact the skin during use, the second cover element being disposed on the second external cutting member at a central position relative to the third skin contact area, such that the third skin contact area surrounds the fourth skin contact area, the second cover element being electrically insulated from the second external cutting member, the bipolar RF generator unit being configured to apply an RF voltage of a first polarity to the second external cutting member, the entire second external cutting member being configured to conduct the RF voltage of the first polarity, the bipolar RF generator unit being further configured to apply an RF voltage of a second polarity to the fourth skin contact area. In some examples, the second cover element is disc-shaped. In some examples, the entire second cover element can be configured to conduct the RF voltage of the second polarity.

[0015] In some examples, the voltages of the first and second polarities have a frequency in the range of 0.5 MHz to 4 MHz.

[0016] In some examples, the RF voltage of the first polarity and the RF voltage of the second polarity have a peak-to-peak voltage in the range of 10 volts (V) to 100 V.

[0017] These and other aspects will become apparent from and will be described with reference to the embodiments set forth below.

Brief Description of the Drawings

[0018]

Figure 1

Figure 2

Figure 3A

Figure 3B

Figure 4

Figure 5A

Figure 5B

Figure 5C

Figure 6A

Figure 6B

DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, exemplary embodiments will be described with reference to the following drawings, which are merely illustrative.

[0020] Accordingly, an example according to the present invention provides an electric shaver in which an external cutting member of a hair cutting unit is used as a first electrode for transmitting RF energy to the skin. A cover element of the external cutting member or another external cutting member can be used as the second electrode. Thus, since the external cutting member provides a relatively large portion of the skin contact area of the electric shaver, a larger surface area is used to supply RF energy to the skin. Using a larger area as the RF electrode means that a larger area of the skin receives RF energy, which allows for deeper penetration and thus improved warming. As described above, warming the skin to about 38° C. to 40° C. can improve the user's tactile sensation. The hair cutting unit can have any suitable design, such as a foil type hair cutting unit or a rotary hair cutting unit with a cutter that reciprocates linearly, as will be further described below.

[0021] FIG. 1 is a diagram of an exemplary electric shaver 100 to which the technology described in this document can be applied. In FIG. 1, the electric shaver 100 is in the form of a foil-type shaver, but it should be understood that the technology described in this document can be applied to any type of electric shaver 100, such as a rotary shaver, as will be described later with reference to FIGS. 4 and 5. The hair cutting device 100 has a main body 110 held in the user's hand and a cutting head 140 in the form of a shaving portion including a plurality of hair cutting units 150, 160 for cutting / shaving hair. In the illustrated example of FIG. 1, the shaving portion has a first hair cutting unit 150 and a second hair cutting unit 160. Each hair cutting unit 150, 160 has an individual internal cutting member having a plurality of cutter blades and an individual external cutting member 152, 162 including a plurality of hair entry openings. The hair entry openings can have holes and / or slits. Each external cutting member 152, 162 has an individual skin contact area that contacts the user's skin during use of the shaver 100. The hair entry openings are part of the skin contact area. In the embodiment of FIG. 1, each outer cutting member 152, 162 is a shaving foil extending parallel to the longitudinal direction. The external cutting members 152, 162 are configured to cover the individual internal cutting members, and the individual internal cutting members are movable relative to the external cutting members. For example, the plurality of cutter blades can linearly reciprocate parallel to the longitudinal direction with respect to the shaving foil. The hair passes through the openings of the shaving foils 152, 162, and the reciprocating movement of the cutter blades cuts the hair, and the cut ends can gather in the hair collection area of the shaver 100. Accordingly, the electric shaver 100 further has a motor 130 configured to move the internal cutting members relative to the individual external cutting members 152, 162 to provide a cutting action.

[0022] The electric shaver 100 further has a bipolar RF generator unit 120. The bipolar RF generator unit has a bipolar RF energy source configured to generate a bipolar RF voltage. The RF voltage can have a pulse width modulation (PWM) voltage signal with a peak-to-peak voltage in the range of 10 to 100 V, preferably 30 to 70 V. The PWM voltage signal can have a duty cycle in the range of 1 to 100%, preferably 25 to 75%. The voltage signal has a frequency in the range of 0.5 to 4 MHz, preferably 1 MHz. Using these parameters of the RF signal, the skin can be warmed to about 38°C to 40°C, which can improve the user's tactile sensation.

[0023] The RF generator unit 120 is configured to apply a first RF voltage to the skin via a skin contact area provided by one of the hair cutting units 150, 160, for example, the outer cutting member 152, 162 of the first hair cutting unit 150. Thus, the RF generator unit 120 is configured to apply the first RF voltage to, for example, the outer cutting member 152 of the first hair cutting unit 150. The outer cutting member 152 can conduct the first RF voltage and is formed of a conductive material that is biocompatible with the skin. For example, the outer cutting member 152 can be formed of a metal such as stainless steel, silver, or silver chloride. Thus, the entire outer cutting member 152 conducts the first RF voltage. In other words, the outer cutting member 152 is used as the first electrode for the RF signal. The RF generator unit 120 is further configured to apply a second RF polar voltage to another skin contact area of the electric shaver 100. In this embodiment, the second RF voltage is applied to the outer cutting member 162 within the second hair cutting unit 160. The outer cutting member 162 can also conduct the second RF voltage and is formed of a conductive material that is biocompatible with the skin. Thus, the outer cutting member 162 can be formed of the same or a similar material as the outer cutting member 152. Thus, the entire outer cutting member 162 conducts the second RF voltage. Thus, the outer cutting member 162 of the second hair cutting unit 160 is used as the second electrode for the RF signal.

[0024] Although not shown in FIG. 1, the external cutting members 152, 162 are electrically insulated from each other within the cutting head 140 / electric shaver 100. As a result, the "circuit" of the RF voltage is completed only when the external cutting members 152, 162 are in contact with the skin. Electrical insulation can be provided, for example, by having a distance of at least 2 millimeters (mm) between the external cutting members 152, 162, or by spatially separating the external cutting members 152, 162 from each other. Additionally or alternatively, electrical insulation can be provided by an insulating material disposed between the external cutting members 152, 162, such as non-conductive plastic.

[0025] In use, the application of the external cutting members 152, 162 of the cutting head 140, and particularly the first hair cutting unit 150 and the second hair cutting unit 160, to the skin enables RF energy to be applied to the skin so as to cause heating. As described above, in the RF energy heating procedure, the operation of the RF generator unit 120 and the application of the electrodes create an electric field in the skin, causing RF energy to flow through the skin from one electrode to the other. Thus, for example, RF energy from the external cutting member 152 of the first hair cutting unit 150 flows through the skin to the external cutting member 162 of the second hair cutting unit 160 due to the application of the external cutting members 152, 162 of the first and second hair cutting units to the skin, resulting in a heating effect on the skin.

[0026] FIG. 2 shows a schematic example of an electric shaving device 200 that applies RF energy to the skin 204 to provide warmth to the skin 204. FIG. 2 schematically shows the elements present in FIG. 1, and corresponding elements have the same reference numerals. FIG. 2 can be considered a partial cross-section through the side of the shaver 100 of FIG. 1.

[0027] Accordingly, FIG. 2 shows a first hair cutting unit 150 having an internal cutting member 252 and an external cutting member 152 (referred to as the "first external cutting member" 152). The shaver 100 further has a second hair cutting unit 160 including an individual internal cutting member 262 and an individual external cutting member 162 (referred to as the "second external cutting member" 162). Each external cutting member 152, 162 has an individual skin contact area including a plurality of hair entry openings 266 through which hair 202 on the skin 204 can pass. Each internal hair cutting member 252, 262 is movable relative to the individual external cutting members 152, 162, such that movement of the internal hair cutting members 252, 262 relative to the individual external cutting members 152, 162 cuts the hair 202 passing through the openings 266.

[0028] The shaver 200 further has an RF energy source 120 configured to apply an RF voltage of a first polarity, for example a positive RF voltage, to the first external cutting member 152 and an RF voltage of a second polarity, for example a negative RF voltage, to the second external cutting member 162. Thus, in use, the first external cutting member 152 and the second external cutting member 162 function as electrodes for conducting the RF voltage, and RF energy is applied to the skin 204 to which the shaver is applied. The RF energy flows, for example, from the second external cutting member 162 to the first external cutting member 152, generating a heated area 206 in the skin 204. The entirety of the first external cutting member 152 and the entirety of the second external cutting member 162 can conduct individual RF voltages, and thus a relatively large area can be used to transfer the RF energy to the skin 204. As a result, the heated area 206 is relatively large and can induce a comfortable warming sensation over a relatively wide area of the skin 204.

[0029] As shown in FIG. 2, the first and second external cutting members 152, 162 are electrically insulated from each other. As a result, RF energy flows between the external cutting members 152, 162 to generate the heating region 206, and skin contact is required for it to pass through the skin 204. In some examples, the first and second external cutting members 152, 162 are at least 2 mm apart to achieve electrical insulation when not in contact with the skin 204. In some examples, the first and second external cutting members 152, 162 and the first and second hair cutting units 150, 160 can be electrically insulated from each other by the presence of an insulating material, such as a plastic material, between the first and second hair cutting units 150, 160.

[0030] FIGS. 3A and 3B show different hair cutting unit / shaving foil arrangements of electric shavers 300a, 300b. FIG. 3A shows a shaver 300a having a first hair cutting unit with an external cutting member in the form of a first shaving foil 350a and a second hair cutting unit with an external cutting member in the form of a second shaving foil 360a. Similar to what was described above with respect to FIGS. 1 and 2, the entirety of the first shaving foil 350a can conduct an RF voltage of a first polarity, and the entirety of the second shaving foil 360a can conduct an RF voltage of a second polarity. When not in contact with the skin, the two shaving foils 350a, 360a are electrically insulated from each other. Thus, contact of the shaving foils 350a, 360a of the shaver 300a with the skin results in RF energy flowing through the skin, for example, from the first shaving foil 350a to the second shaving foil 360a, generating a comfortable warming sensation across the area of the skin.

[0031] Figure 3B shows another shaver 300b having first and second hair cutting units with respective first and second shaving foils 350b, 360b as external cutting members and further having a third hair cutting unit with an external cutting member in the form of a third shaving foil 370b. Similar to shaver 300a, the entirety of the first shaving foil 350b is configured to conduct an RF voltage of a first polarity, and the entirety of the second shaving foil 360b is configured to conduct an RF voltage of a second polarity. The entirety of the third shaving foil 370b is also configured to conduct an RF voltage of the first polarity. The shaving foils 350b, 360b, and 370b are parallel to each other, and the hair cutting units are arranged in shaver 300b such that the first shaving foil 350b and the third shaving foil 370b are on opposite sides of the second shaving foil 360b. When not in contact with the skin, the three shaving foils 350b - 370b are electrically insulated from each other. Thus, when the electric shaver 300b is applied to the skin, RF energy flows, for example, from the first and third shaving foils 350b, 370b to the second shaving foil 360b, generating a comfortable warming sensation across the area of the skin. The increase in the number of shaving foils in shaver 300b compared to shaver 300a can result in a larger area of the skin being warmed.

[0032] Figure 4 is a diagram of another exemplary electric shaver 400 to which the techniques described in this document can be applied. Figure 4 shows the elements present in Figure 1, with corresponding elements having the same reference numerals and not being described in detail hereinafter for simplicity.

[0033] The electric shaver 400 is in the form of a rotary shaver and has a cutting head 140 including a first hair cutting unit 150 having a first external cutting member 152, a second hair cutting unit 160 having a second external cutting member 162, and a third hair cutting unit 470 having a third external cutting member 472. The first, second, and third hair cutting units 150, 160, 470 can be attached to the cutting head 140 at appropriate attachment positions. In the illustrated embodiment, the hair cutting units 150, 160, 470 have a triangular arrangement, but it should be understood that the hair cutting units can alternatively be arranged in a row. The external cutting members 152, 162, 472 of the hair cutting units each have a skin contact area including a plurality of hair entry openings, which are configured to contact the skin during use. The individual skin contact areas of the first, second, and third hair external cutting members 152, 162, 472 are annular (i.e., ring-shaped). Each of the first, second, and third hair cutting units 150, 160, 470 further has an individual internal cutting member rotatable with respect to the individual external cutting members 152, 162, 472, particularly having a plurality of cutter blades. The external cutting members 152, 162, 472 are each configured to cover the individual internal cutting members. The hair entry openings can have holes and / or slits. During use, the hair passes through the hair entry openings, and the rotation of the cutter blades with respect to the external cutting members 152, 162, 472 cuts the hair passing through the openings.

[0034] The first hair cutting unit 150, the second hair cutting unit 160, and the third hair cutting unit 470 each further include a first cover element 452, a second cover element 462, and a third cover element 474. Each of the first, second, and third cover elements 452, 462, 474 is disposed on the first, second, and third external cutting members 152, 162, 472, respectively. Each of the first, second, and third cover elements 452, 462, 474 has a skin contact region configured to contact the skin during use. Each of the first, second, and third cover elements 452, 462, 474 is further disposed centrally with respect to the individual annular skin contact regions of the first, second, and third external cutting members 152, 162, 472, such that the skin contact regions of the external cutting members 152, 162, 472 surround the individual cover elements 452, 462, 474. As shown in FIG. 4, each cover element 452, 462, 474 is disk-shaped and is thus a cover element that may also be referred to as a cap or a de-capping element. Those skilled in the art will recognize other suitable shapes and / or forms of the cover element.

[0035] The bipolar RF generator unit 120 is configured to apply an RF voltage of a first polarity to the skin via a skin contact area provided by one of the external cutting members 152, 162, 472, for example, the first external cutting member 152. Accordingly, the RF generator unit 120 is configured to apply an RF voltage of a first polarity to the external cutting member 152 of, for example, the first hair cutting unit 150. The entire external cutting member 152 conducts the first RF voltage, and as a result, the first cutting member 152 is used as a first electrode for the RF signal. The bipolar RF generator unit 120 is further configured to apply an RF voltage of a second polarity to the skin via another skin contact area, for example, via a skin contact area provided by the first cover element 452 disposed at the center of the skin contact area of the first external cutting member 152. Accordingly, the RF generator unit 120 is configured to apply an RF voltage of a second polarity to the first cover element 452, for example. Accordingly, the first cover element 452 can be used as a second electrode for the RF signal. Accordingly, for example, the first RF voltage can be supplied to the skin via the first external cutting member 152, and the second RF voltage can be supplied to the skin via the first cover element 452. The entire cover element 452 can be configured to conduct an RF voltage of a second polarity.

[0036] Although not shown in FIG. 4, the first external cutting member 152 and the first cover element 452 are electrically insulated from each other in the cutting head 140 / electric shaver 400. As a result, the "circuit" of the RF voltage is completed only when the external cutting member 152 and the first cover element 452 are in contact with the skin. The electrical insulation can be achieved by an insulating material located between the first external cutting member 152 and the first cover element 452, such as non-conductive plastic.

[0037] During use, the application of the cutting head 140, and in particular, the skin contact areas of the first external cutting member 152 and the first cover element 452 to the skin enables RF energy to be applied to the skin, resulting in heating of the skin. Thus, RF energy flows through the skin, for example, from the first external cutting member 152 to the first cover element 452 due to the application of the first hair cutting unit to the skin, resulting in a heating effect on the skin.

[0038] In some examples, the bipolar RF generator unit 120 is further configured to apply a first polarity RF voltage to the skin through a skin contact area provided by one additional external cutting member 152, 162, 472, for example, the second external cutting member 162. The entirety of the second external cutting member 162 can conduct the first RF voltage. As a result, the second external cutting member 162 is used as a third electrode for the RF signal. The bipolar RF generator unit 120 is further configured to apply an RF voltage of a second polarity to another skin contact area, for example, to a second cover element 462 disposed at the center of the skin contact area of the second external cutting member 162. Thus, the second cover element 462 can be used as a fourth electrode for the RF signal. The entirety of the second cover element 462 can be configured to conduct an RF voltage of a second polarity.

[0039] Similar to the first external cutting member 152 and the first cover element 452 described above, the second external cutting member 162 and the second cover element 462 are also electrically insulated from each other. As a result, when the cutting head 140 is applied to the skin, RF energy flows, for example, from the second external cutting member 162 to the second cover element 462, generating heating of the skin.

[0040] In some examples, the bipolar RF generator unit 120 is further configured to apply a first polarity RF voltage to the skin via the skin contact areas provided by each of the external cutting members 152, 162, 472, and is further configured to apply a second polarity RF voltage to each of the cover elements 452, 462, 474. In such examples, the third external cutting member 472 and the third cover element 474 are also electrically insulated from each other, similar to the first external cutting member 152 and the first cover element 452 described above. The entire third external cutting member 472 can be configured to conduct an RF voltage of the first polarity. The entire third cover element 474 can be configured to conduct an RF voltage of the second polarity. Accordingly, each of the external cutting members 152, 162, 472 and the cover elements 452, 462, 474 can be used as RF electrodes for RF signals. Accordingly, during use, via the application of the cutting head 140 to the skin, RF energy flows, for example, from the external cutting members 152, 162, 472 through the skin to the cover elements 452, 462, 474, generating a heating area in the skin.

[0041] RF energy can flow substantially between individual pairs of the external cutting members 152, 162, 472 and the cover elements 452, 462, 474. For example, RF energy can flow substantially from the first hair cutting unit 152 to the first cover element 452.

[0042] In an alternative approach to the approach described above, rather than connecting the cover elements 452, 462, 474 to the bipolar RF generator unit 120 to apply a second polarity RF voltage to the skin, at least one of the external cutting members 152, 162, 472 is used to apply a first polarity RF voltage to the skin, and another one of the external cutting members 152, 162, 472 is used to apply a second polarity RF voltage to the skin, thereby completing the circuit and enabling the skin to be heated. Accordingly, the use of the external cutting members 152, 162, 472 as electrodes for the bipolar RF generator unit 120 is similar to the embodiments described above with respect to FIGS. 1 and 2.

[0043] Figures 5A - C show different external cutting member / cover element arrangements of rotary shavers 500a, 500b, 500c.

[0044] Figure 5A shows the arrangement of rotary shaver 500a having three hair cutting units, each unit having individual external cutting members 152a, 162a, 472a and individual cover elements 452a, 462a, 474a.

[0045] As described above with respect to FIG. 4, the external cutting members 152a, 162a, 472a are configured to conduct an RF voltage of a first polarity, and the cover elements 452a, 462a, 474a are configured to conduct an RF voltage of a second polarity. The external cutting members 152a, 162a, 472a and the cover elements 452a, 462a, 474a are electrically insulated from each other when not in contact with the skin. Thus, when applied to the skin, an electric field is generated between the external cutting members 152a, 162a, 472a and the cover elements 452a, 462a, 474a. As a result, RF energy flows, for example, from the external cutting members 152a, 162a, 472a to the individual cover elements 452a, 462a, 474a.

[0046] Figure 5B shows another arrangement of the rotary shaver 500b having two hair cutting units. The first hair cutting unit has a first outer cutting member 152b, and the second hair cutting unit has a second outer cutting member 452b. The first hair cutting unit further has a first cover element 452b disposed on the first outer cutting member 152b and positioned at the center of the skin contact area of the first outer cutting member 152b. The second hair cutting unit further has a second cover element 462b disposed on the second outer cutting member 162b and positioned at the center of the skin contact area of the second outer cutting member 162b. Each of the outer cutting members 152a, 162a is configured to conduct an RF voltage of a first polarity, and each of the cover elements 452b, 462b is configured to conduct an RF voltage of a second polarity. The outer cutting members 152b, 162b and the cover elements 452b, 462b are electrically insulated from each other when not in contact with the skin. Thus, in a manner similar to that described above, upon application of the shaver 500b to the skin, an electric field is generated in the skin between the outer cutting members 152b, 162b and the cover elements 452b, 462. As a result, RF energy flows between the outer cutting members 152b, 162b and the cover elements 452b, 462, and the area of the skin is warmed.

[0047] FIG. 5C relates to the above-described alternative approach in which only the external cutting members are used as the electrodes of the bipolar RF generator unit 120. Thus, FIG. 5C shows another arrangement of the rotary shaver 500c having two hair cutting units. Similar to the shaver 500b, the first hair cutting unit has a first external cutting member 152c and a first cover element 452c, and the second hair cutting unit has a second external cutting member 162c and a second cover element 462c. The first external cutting member 152c is configured to conduct an RF voltage of a first polarity, and the second external cutting member 162c is configured to conduct an RF voltage of a second polarity. In the shaver 500c, neither the first cover element 452c nor the second cover element 462c is connected to the bipolar RF generator unit 120, and neither provides an RF voltage to the skin by itself. In this embodiment, the first cover element 452c and the second cover element 462c are made of an electrically non-conductive material such as plastic. The first external cutting member 152c and the second external cutting member 162c are electrically insulated from each other when not in contact with the skin. Application of the skin to the shaver 500c generates an electric field in the skin between the first external cutting member 152c and the second external cutting member 162c, as a result of which RF energy flows, for example, from the first hair cutting unit 550c to the second hair cutting unit 560c, warming the area of the skin. Alternatively, the first cover element 452c may be conductive and connected to the first external cutting member 152c to conduct an RF voltage of the first polarity together with the first external cutting member 152c. Similarly, the second cover element 462c may be conductive and connected to the second external cutting member 162c to conduct an RF voltage of the second polarity together with the second external cutting member 162c.

[0048] Figures 6A and 6B show the results of pleasure scores obtained using an electric shaver according to an example of the present disclosure. The pleasure scores were provided by different users using a foil type shaver as shown in FIG. 2 and were compared to pleasure scores provided by the same users using a known skin tightening device that applies RF energy to the skin to warm the skin and promote skin tightening. The users of the devices were asked to rate the perceived comfort of the skin warming by each device as "2" for comfortable, "1" for mild warmth, and "0" for no warmth or negligible warmth. The pleasure score "A" relates to the foil shaver and the pleasure score "B" relates to the skin tightening device. The RF voltage of each device was modulated with a 10 Hz PWM signal with a duty cycle of 80% at different RF frequencies and RF voltages. In these tests, shaving gel was applied to the skin before use of the device. The shaving gel used had a conductivity in the range of 0.01 to 0.25 S / m for an RF energy frequency of 1 MHz.

[0049] Figure 6A shows the results obtained at a peak-to-peak voltage of 50 V for bipolar RF voltages applied at frequencies of 0.5 MHz, 1 MHz, 2 MHz, and 4 MHz. As shown in the figure, at this voltage level, the foil type shaver outperformed the skin tightening device across all frequencies, and the most comfortable score was obtained at a frequency of 1 MHz for a peak-to-peak voltage of 50 V. Figure 6B shows the results obtained at a peak-to-peak voltage of 100 V for bipolar RF voltages applied at frequencies of 0.5 MHz, 1 MHz, 2 MHz, and 4 MHz. As shown in the figure, the foil type shaver was able to induce at least a mild sense of warmth across all frequencies, and the highest pleasure score was also obtained here at a frequency of 1 MHz.

[0050] Accordingly, an example according to the present disclosure presents an electric shaver that can impart a pleasant warm feeling to the skin through the application of RF energy to the skin. The RF voltage is applied to the skin through at least one of the hair cutting units of the electric shaver, and the entire external cutting member of the hair cutting unit is configured to conduct the RF voltage. The external cutting member can occupy a relatively large portion of the skin contact area of the electric shaver during use. Therefore, an electric field can be generated between the external cutting member and other electrodes (e.g., a cap associated with the hair cutting unit or the external cutting member of another hair cutting unit) through a relatively large area of the skin. Accordingly, the flow of RF energy due to the electric field warms the skin over a relatively wide area, evoking a pleasant warm sensation. The RF heating of the skin can further increase the microcirculation of blood in the skin and improve the moisturization of the skin. Further, RF heating can also enhance local absorption.

[0051] Modifications to the disclosed embodiments can be understood and implemented by those skilled in the art who practice the principles and techniques described herein from a consideration of the figures, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. One processor or other unit can perform the functions of a plurality of items recited in the claims. 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. A computer program can be stored or distributed in a suitable medium, such as an optical storage medium or a solid-state medium, supplied together with or as part of other hardware, but can also be distributed in other forms, such as via the Internet or other wired or wireless communication systems. Any reference signs in the claims should not be construed as limiting the scope of the invention.

Claims

**Claim 1** An electric shaver, comprising a first hair cutting unit, said first hair cutting unit comprising a first internal cutting member, a first external cutting member covering said first internal cutting member, said first internal cutting member being movable relative to said first external cutting member, said first external cutting member including a first skin contact area having a plurality of first hair entry openings, said first skin contact area contacting the skin during use, and said electric shaver further comprising a second skin contact area contacting the skin during use, and a bipolar radio frequency (RF) generator unit for applying an RF voltage of a first polarity to said first external cutting member, the entirety of said first external cutting member conducting the RF voltage of said first polarity, said bipolar RF generator unit further applying an RF voltage of a second polarity to said second skin contact area. **Claim 2** Further comprising a second hair cutting unit, said second hair cutting unit comprising a second internal cutting member, a second external cutting member covering said second internal cutting member, said second internal cutting member being movable relative to said second external cutting member, said second external cutting member including a second skin contact area provided with a plurality of second hair entry openings, and the entirety of said second external cutting member conducting the RF voltage of said second polarity. The electric shaver according to claim 1. **Claim 3** Further comprising a third hair cutting unit, said third hair cutting unit comprising a third internal cutting member, a third external cutting member covering said third internal cutting member, said third internal cutting member being movable relative to said third external cutting member, said third external cutting member including a third skin contact area having a plurality of third hair entry openings, wherein said bipolar RF generator unit applies the voltage of said first polarity to said third external cutting member, and the entirety of said third external cutting member conducts the RF voltage of said first polarity. The electric shaver according to claim 2. **Claim 4** The electric shaver according to claim 3, wherein said second hair cutting unit is disposed between said first hair cutting unit and said third hair cutting unit. **Claim 5** ​ ​ The first external cutting member and the second external cutting member each have a shaving foil extending parallel to the longitudinal direction, and the first internal cutting member and the second internal cutting member each linearly reciprocate parallel to the longitudinal direction with respect to the first external cutting member and the second external cutting member, respectively. The electric shaver according to any one of claims 2 to 4.

6. The third external cutting member has a shaving foil extending parallel to the longitudinal direction, and the third internal cutting member linearly reciprocates parallel to the longitudinal direction with respect to the third external cutting member. The electric shaver according to claim 5, which depends on claim 3 or 4.

7. The first skin contact area is annular, and the first internal cutting member is rotatable with respect to the first external cutting member. The second skin contact area is annular, and the second internal cutting member is rotatable with respect to the second external cutting member. The electric shaver according to claim 2.

8. The first skin contact area is annular, and the first internal cutting member is rotatable with respect to the first external cutting member. The first hair cutting unit further has a first cover element including the second skin contact area, the first cover element is disposed on the first external cutting member centered with respect to the first skin contact area, the first skin contact area surrounds the second skin contact area, and the first cover element is electrically insulated from the first external cutting member. The electric shaver according to claim 1.

9. The first cover element is disc-shaped. The electric shaver according to claim 1.

10. The whole of the first cover element conducts the RF voltage of the second polarity. The electric shaver according to claim 8 or 9.

11. It further has a second hair cutting unit, the second hair cutting unit includes a second internal cutting member and a second external cutting member covering the second internal cutting member, and the second internal cutting member is rotatable with respect to the second external cutting member. The second external cutting member includes an annular third skin contact area having a plurality of second hair entry openings, and the third skin contact area contacts the skin during use. The second hair cutting unit further includes a second cover element having a fourth skin contact area that contacts the skin during use, the second cover element being disposed on the second external cutting member at a central position with respect to the third skin contact area, the third skin contact area surrounding the fourth skin contact area, and the second cover element being electrically insulated from the second external cutting member. The bipolar RF generator unit applies the RF voltage of the first polarity to the second external cutting member, the entire second external cutting member conducting the RF voltage of the first polarity, and the bipolar RF generator unit applying the RF voltage of the second polarity to the fourth skin contact area. The electric shaver according to claim 8, 9 or 10. **Claim 12** The electric shaver according to claim 11, wherein the second cover element is disc-shaped. **Claim 13** The electric shaver according to claim 11 or 12, wherein the entire second cover element conducts the RF voltage of the second polarity. **Claim 14** The electric shaver according to any one of claims 1 to 13, wherein the RF voltages of the first and second polarities have a frequency in the range of 0.5 MHz to 4 MHz. **Claim 15** The electric shaver according to any one of claims 1 to 14, wherein the RF voltage of the first polarity and the RF voltage of the second polarity have a peak-to-peak voltage in the range of 10 volts to 100 volts.

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