Electric shaver

Abstract

According to one aspect, there are skin contact areas 200, 910, 1110, 1410, 1610 for contacting the user's skin during use of electric shavers 100, 900, 1000, 1100, 1400, 1600, and at least two hair cutting units 150, 160, 170, 1480, 1680 disposed within the skin contact areas, each hair cutting unit having an external cutting member 152, 162, 172, 1482, 1682 having a plurality of hair entry openings, and an internal cutting member covered by the external cutting member 152, 162, 172, 1482, 1682 and movable relative to the external cutting member; N electrodes 180a - d disposed within the skin contact areas 200, 910, 1110, 1410, 1610 so as to contact the skin during use, where N is at least 3; the fundamental frequency f RF and the fundamental period T RF = 1 / f RF A radio frequency (RF) generator 320 configured to generate RF energy having; and an RF energy modulator 310 configured to convert the RF energy generated by the RF generator into N periodically amplitude - modulated RF energy signals and provide each of the N periodically amplitude - modulated RF energy signals S1, S2, S3 to a corresponding one of the N electrodes. In an electric shaver comprising, when viewed in a direction perpendicular to the skin contact area, the external cutting member of each hair cutting unit has a geometric center point 156, 166, 176, 1486, 1686, a first pitch distance 202 which is the distance between the geometric center points of a pair of hair cutting units, and a first minimum pitch distance which is the minimum value of the first pitch distances of all pairs of hair cutting units; when viewed in a direction perpendicular to the skin contact area, each of the N electrodes has a geometric center point 182a - c, a second pitch distance 204 which is the distance between the geometric center points of a pair of the N electrodes, and a second minimum pitch distance which is the minimum value of the second pitch distances 204 of all pairs of the N electrodes, the ratio between the second minimum pitch distance and the first minimum pitch distance being at least 0.8; the fundamental period T MOD of the N periodically amplitude - modulated RF energy signals S1, S2, S3 is the fundamental period T RFgreater than, and the n-th of the N periodically amplitude-modulated RF energy signals S1, S2, S3 has a phase difference of T * (n - 1) / N with respect to the first of the N periodically amplitude-modulated RF energy signals S1, S2, S3, where 2 ≦ n ≦ N, an electric shaver is provided. MOD *(n - 1) / N, where 2 ≦ n ≦ N, an electric shaver is provided.

Description

[Technical Field] 【0001】 This application relates to an electric shaver, and more particularly to an electric shaver equipped with a radio frequency (RF) generator unit for heating the skin during use. [Background technology] 【0002】 It is generally recognized that applying heat to the skin within a specific temperature range, such as approximately 38°C to 40°C, can evoke a pleasant warming sensation. Methods of warming the skin include applying hot towels, steam, and infrared light. Integrating a skin warming unit into a personal care device generally improves the user's sensory experience while performing personal care routines. 【0003】 One such personal care device that employs a skin heating unit is the electric shaver. Electric shavers are known to contain heated mechanical elements that provide warmth to the skin through heat transfer during shaving. This warmth creates a pleasant sensation, resulting in an improved user experience. 【0004】 Another method of heating the skin is the use of deep dermal heating with radio frequency (RF) energy. The use of RF energy differs from mechanical elements that heat using heat transfer. In RF heating applications, two electrodes are attached to the skin, and each is charged with RF energy in the opposite direction. This creates an electric field in the skin between the two electrodes. RF energy can penetrate deeper into the skin than heat transfer caused by heated mechanical elements, and therefore can heat a relatively large area of ​​skin. Heating can be achieved across the entire depth of penetration without relying on the thermal conductivity of both the heat application means and the skin, as is required with the use of heated mechanical elements. 【0005】 RF-based skin heating was initially used for skincare and tissue excision. For example, tumors within organs are excised by applying RF energy to heat the tumor. This technology was suitable for these applications because RF energy can penetrate deeply into skin tissue and is easy to control. 【0006】 Generally, RF energy supply parameters, such as electrical and physical characteristics (e.g., the geometry of the contact electrodes), can be adjusted to suit specific applications. Typically, large RF electrodes receiving low RF voltages are used in skincare applications, while small RF electrodes receiving high RF voltages are used in surgical applications. 【0007】 For example, surface RF heating applications used in home skincare devices involve the use of bipolar RF energy, where two contact electrodes are placed quite close together, localizing the current flow to a small area. In contrast, clinical RF heating applications employ a technique called unipolar RF, in which one of the contact electrodes is placed far away from the other, allowing the current to flow through the human body. 【0008】 Another RF skin heating technique used in clinical applications involves applying RF energy to the skin using multiple electrodes, for example, three or more, and phase-shifting or steering the RF energy applied to each electrode. For example, U.S. Patent No. 5,383,917 discloses a multiphase RF excision technique employing a two- or three-dimensional electrode array that generates numerous current paths on the surface of the excision area, resulting in a uniform lesion of a size determined by the span of the electrode array. U.S. Patent Application Publication No. 20130231611 discloses an electrosurgical method and device provided for applying phase-controlled RF energy to a treatment site, comprising a multi-electrode electrosurgical probe electrically coupled to multiple RF generators. [Overview of the Initiative] [Problems that the invention aims to solve] 【0009】 One of the challenges of using bipolar RF energy for skin tissue heating is controlling the uniformity of heating within the tissue volume. When applying RF heating to the skin using an electric shaver, uniform heating of the skin with minimal hot spots is desired for a comfortable thermal experience and to avoid discomfort. A common technique to minimize hot spots is to use multiple large electrodes. However, this effect is limited by the fact that most of the heating occurs between the two closest electrodes. As described in U.S. Patent No. 5,383,917 and U.S. Patent Application Publication No. 2013,023,1611, the RF field can be better dispersed within the tissue by phase-shifting or steering the RF energy between multiple electrodes, resulting in more uniform tissue heating. However, these solutions use expensive and bulky RF phase-steering devices required to generate multiphase RF signals. Electric shavers have limited space, and using such relatively large phase-steering devices in them is generally not practical. Furthermore, it has been observed that the thermal effects of phase shift or steering solutions can be sensitive to the accuracy of the phase difference between RF signals. 【0010】 Therefore, improved systems and methods are needed for improved and uniform skin heating using RF with electric shavers. [Means for solving the problem] 【0011】 According to a first specific embodiment, the electric shaver comprises: a skin contact area for contacting the user's skin during use; at least two hair cutting units disposed within the skin contact area, each having an external cutting member having a plurality of hair entry openings and an internal cutting member covered by the external cutting member and movable relative to the external cutting member; and N electrodes disposed within the skin contact area to contact the skin during use, where N is at least 3; and a fundamental frequency fRF and a fundamental period T RF = 1 / fRF A high-frequency (RF) generator configured to generate RF energy having RF , and an RF energy modulator configured to convert the RF energy generated by the RF generator into N periodically amplitude-modulated RF energy signals, and to provide each of the N periodically amplitude-modulated RF energy signals to a corresponding one of the N electrodes. In an electric shaver, when viewed in a direction perpendicular to the skin contact area, the outer cutting member of each hair cutting unit has a geometric center point, a first pitch distance that is the distance between the geometric center points of a pair of hair cutting units, and a first minimum pitch distance that is the minimum value of the first pitch distances of all pairs of hair cutting units. When viewed in a direction perpendicular to the skin contact area, each of the N electrodes has a geometric center point, a second pitch distance that is the distance between the geometric center points of a pair of the N electrodes, and a second minimum pitch distance that is the minimum value of the second pitch distances of all pairs of the N electrodes. The ratio between the second minimum pitch distance and the first minimum pitch distance is at least 0.8. The basic period T of the N periodically amplitude-modulated RF energy signals MOD is the basic period T RF is greater than the basic period T, and the nth one of the N periodically amplitude-modulated RF energy signals has a phase difference of T MOD *(n - 1) / N with respect to the first one of the N periodically amplitude-modulated RF energy signals, where 2 ≤ n ≤ N. An electric shaver is provided. 【0012】 In some examples, the ratio between T MOD and T RF is at least 10, preferably at least 25. 【0013】 In some examples, each of the N periodically amplitude-modulated RF energy signals has the same basic RF energy signal during the basic period T MOD of each respective periodically amplitude-modulated RF energy signal. 【0014】 In some examples, the basic RF energy signal has a first state and a second state. The first state has a basic frequency f RFThe first state consists of a first RF energy signal having a first RF voltage, and the second state consists of a zero signal. 【0015】 In some examples, the basic RF energy signal further comprises a third state consisting of a second RF energy signal obtained by inverting the first RF energy signal. 【0016】 In some cases, the first states of N periodic amplitude-modulated RF energy signals do not occur simultaneously. 【0017】 In some cases, the second state of N periodic amplitude-modulated RF energy signals does not occur simultaneously. 【0018】 In some examples, the N electrodes are positioned adjacent to the hair cutting unit. 【0019】 In some examples, the electric shaver comprises three electrodes and three hair cutting units arranged in a triangular configuration with respect to each other, the internal cutting member of each hair cutting unit being rotatable relative to the external cutting member, and each of the three electrodes positioned in the lateral portion of the skin contact area between two hair cutting units of one pair of hair cutting units. 【0020】 In some examples, an electric shaver comprises N hair cutting units, each of which has an annular external cutting member, and N electrodes comprising N covering elements, each positioned centrally relative to the external cutting member of each of the N hair cutting units. 【0021】 In some examples, an electric shaver comprises N hair cutting units, and each of the N electrodes is composed of at least the skin-contact portion of the external cutting member of each of the N hair cutting units. 【0022】 In some examples, an electric shaver comprises three hair cutting units, the internal cutting member of each hair cutting unit being configured to reciprocate linearly parallel to the longitudinal direction relative to the external cutting member, and the external cutting member of each hair cutting unit having a longitudinal extension parallel to the longitudinal direction. 【0023】 In some examples, an electric shaver comprises four electrodes and four hair cutting units, wherein the internal cutting member of each hair cutting unit is configured to reciprocate linearly parallel to the longitudinal direction relative to the external cutting member, the external cutting member of each hair cutting unit has a longitudinal extension parallel to the longitudinal direction, each of the four electrodes is composed of at least the skin contact portion of the external cutting member of each of the four hair cutting units, and the fundamental RF energy signal comprises a first state, a second state, a third state, and a fourth state in sequence, the first state having a fundamental frequency f RF The second state is composed of a first RF energy signal having a first RF voltage, and the fundamental frequency f RF The third state is comprised of a second RF energy signal having a second RF voltage lower than the first RF voltage, the third state is comprised of a third RF energy signal obtained by inverting the second RF energy signal, and the fourth state is comprised of a fourth RF energy signal obtained by inverting the first RF energy signal. 【0024】 In some examples, the ratio between the second RF voltage and the first RF voltage is between 0.25 and 0.5, preferably between 0.3 and 0.35. 【0025】 In some examples, the RF energy modulator comprises N switch units, each of which is configured to apply each of the N periodic amplitude-modulated RF energy signals to each of the N electrodes. 【0026】 These and other embodiments will become apparent from and will be described with reference to the embodiments described below. 【0027】 Hereinafter, exemplary embodiments are described merely as examples with reference to the following drawings. [Brief explanation of the drawing] 【0028】 [Figure 1] This is an example diagram of an electric shaver. [Figure 2] This is a diagram showing an example of a cutting head for an electric shaver. [Figure 3] This is a diagram illustrating an example of a circuit configuration for applying RF energy to electrodes. [Figure 4a-4c] This is a diagram illustrating an example of an RF signal. [Figures 5a-5c] This is a diagram illustrating an example of an RF signal. [Figures 6a-6c] This is a diagram illustrating an example of an RF signal. [Figure 7] This is a diagram of another example of a circuit configuration for applying RF energy to electrodes. [Figures 8a-8b] This diagram shows an example of applying RF energy to the electrodes of an electric shaver. [Figure 9] This is a diagram of another example of an electric shaver cutting head. [Figure 10] This is a diagram of another example of an electric shaver. [Figure 11] This is a diagram of another example of an electric shaver cutting head. [Figures 12a-12b] This diagram shows an example of applying RF energy to the electrodes of an electric shaver. [Figures 13a-13b] This is a diagram illustrating a further example of applying RF energy to the electrodes of an electric shaver. [Figure 14] This is a diagram of another example of an electric shaver cutting head. [Figures 15a-15b] This is a diagram illustrating another example of applying RF energy to the electrodes of an electric shaver. [Figure 16] This is a diagram of another example of an electric shaver cutting head. [Figures 17a-17b] This is a diagram illustrating a further example of applying RF energy to the electrodes of an electric shaver. [Modes for carrying out the invention] 【0029】 An example provided by this disclosure provides an electric shaver having a skin contact area for contact with the user's skin during use. The skin contact area has at least two hair cutting units, and the skin contact area also has N electrodes for transmitting RF energy, which are positioned to contact the skin during use, where N is at least 3. When viewed perpendicular to the skin contact area, the external cutting member of each hair cutting unit has a geometric center point and a first pitch distance which is the distance between the geometric center points of a pair of hair cutting units. The first minimum pitch distance is the minimum of the first pitch distances for all pairs of hair cutting units. Furthermore, when viewed perpendicular to the skin contact area, each of the N electrodes has a geometric center point and a second pitch distance which is the distance between the geometric center points of a pair of N electrodes. The second minimum pitch distance is the minimum of the second pitch distances for all pairs of N electrodes. The ratio between the second minimum pitch distance and the first minimum pitch distance is at least 0.8. By arranging the hair cutting unit and N electrodes in this manner, the N electrodes are diffused over a considerable area of ​​the skin contact area. Thus, when the skin contact area is applied to the user's skin, the RF energy flows between the N electrodes, warming a large portion of the skin in contact with the skin contact area, leading to improved uniform skin heating. 【0030】 An electric shaver according to an example of this disclosure has a fundamental frequency f RF and fundamental period T RF = 1 / f RF The system further comprises an RF generator configured to generate RF energy having a fundamental period T, and an RF energy modulator configured to convert the RF energy generated by the RF generator into N periodically amplitude-modulated RF energy signals, and to provide each of the N periodically amplitude-modulated RF energy signals to each of the N electrodes. MOD is the fundamental period T RFLarger than the nth of N periodic amplitude-modulated RF energy signals, the nth signal is T greater than the first of N periodic amplitude-modulated RF energy signals. MOD The phase difference is *(n-1) / N, where 2 ≤ n ≤ N. By modulating the RF energy into N periodic amplitude-modulated RF energy signals that are phase-shifted relative to each other, the use of expensive and bulky RF phase-steering devices used in prior art solutions is avoided. As will be explained in more detail below, the phase-shifted N periodic amplitude-modulated RF energy signals cause the RF energy to be generated in varying amounts between different electrodes of the N electrodes for varying periods of time, which further leads to more uniform heating of the skin contact area and the skin in contact, thus avoiding the accumulation of hot spots. 【0031】 Figure 1 is a diagram of an exemplary electric shaver 100 to which the technology described herein can be applied. In Figure 1, the electric shaver 100 is in the form of a rotary shaver, but it will be understood that the technology described herein can be applied to any type of electric shaver 100, such as a foil shaver, as described below. The electric shaver 100 comprises a body 110 which will be held in the user's hand, and a cutting head 140 in the form of a skin contact area which includes a plurality of hair cutting units 150, 160, 170 for cutting / shaving hair. The cutting head of the electric shaver includes a skin contact area which is positioned to come into contact with the user's skin while the shaver is in use. In the example shown in Figure 1, the skin contact area comprises a first hair cutting unit 150, a second hair cutting unit 160, and a third hair cutting unit 170. However, in other examples, the skin contact area may comprise two hair contact units, or four or more hair cutting units. 【0032】 The first hair cutting unit 150 comprises a first external cutting member 152, the second hair cutting unit 160 comprises a second external cutting member 162, and the third hair cutting unit 170 comprises a third external cutting member 172. The first, second, and third hair cutting units 150, 160, and 170 are mounted on the cutting head 140 in appropriate mounting positions. In this exemplary embodiment, the hair cutting units 150, 160, and 170 have a triangular arrangement, but it will be understood that the hair cutting units can be arranged in other configurations. The external cutting members 152, 162, and 172 of the hair cutting units each comprise a plurality of hair entry openings, which are positioned to contact the skin during use. The corresponding skin contact areas of the first, second, and third external hair cutting members 152, 162, and 172 are annular (i.e., ring-shaped). Each of the first, second, and third hair cutting units 150, 160, and 170 further comprises a corresponding internal cutting member, such as a blade, which is rotatable relative to the external cutting members 152, 162, and 172, respectively. The external cutting members 152, 162, and 172 are positioned to cover the respective internal cutting members. The hair entry opening comprises a hole and / or a thin plate. During use, hair protrudes in this case from the hair entry opening, and the rotation of the blade relative to the external cutting members 152, 162, and 172 cuts the hair protruding through the opening. The electric shaver 100 therefore further comprises a motor 130 configured to move the internal cutting members relative to the corresponding external cutting members 152, 162, and 172 so that a cutting action occurs. 【0033】 The first hair cutting unit 150, the second hair cutting unit 160, and the third hair cutting unit 170 each further comprise a first covering element 154, a second covering element 164, and a third covering element 174. The first, second, and third covering elements 154, 164, and 174 are each positioned on the first, second, and third external cutting members 152, 162, and 172, respectively. The first, second, and third covering elements 154, 164, and 174 each comprise a skin contact area positioned to come into contact with the skin during use. Each of the first, second, and third covering elements 154, 164, and 174 is further centered relative to the corresponding ring-shaped skin contact areas of the first, second, and third external cutting members 152, 162, and 172, so that the skin contact areas of the external cutting members 152, 162, and 172 surround the corresponding covering elements 154, 164, and 174. As shown in Figure 1, each covering element 154, 164, and 174 is disc-shaped and is therefore also called a cap, shaving cap, or deco cap. Those skilled in the art will come up with other suitable shapes and / or forms of the covering members. 【0034】 As will be described in more detail below, the electric shaver 100 further comprises N electrodes (not shown in Figure 1) positioned within the skin contact area so as to come into contact with the skin during use. In the example of the present disclosure, the N electrodes comprise at least three electrodes. The N electrodes are configured to transmit RF energy so that, during use, RF energy is applied to the skin in contact with the skin contact area of ​​the electric shaver, thereby warming the skin. Thus, the electric shaver 100 further comprises an RF energy generator unit 120, which is configured to generate RF energy applied to each of the N electrodes in the form of N periodic amplitude-modulated RF energy signals, as will be described in more detail below. 【0035】 Figure 2 shows the skin contact area 200 of the electric shaver. In this case, the skin contact area is included in the cutting head of the electric shaver. Figure 2 shows the skin contact area 200 viewed perpendicular to the surface of the skin contact area. The skin contact area comprises a first hair cutting unit 150, a second hair cutting unit 160, and a third hair cutting unit 170, which operate in corresponding manner as described above with respect to Figure 1. 【0036】 The skin contact area 200 further comprises a first electrode 180a, a second electrode 180b, and a third electrode 180c, which together constitute N electrodes 180a-c. As shown in Figure 2, the N electrodes 180a-c are arranged adjacent to the hair cutting units 150, 160, and 170. In this case, the N electrodes 180a-c and the three hair cutting units 150, 160, and 170 are arranged in a triangular configuration, where N is the number of electrodes 180a-c, and each of the three electrodes 180a-c is positioned in the lateral portion of the skin contact area 200 between each pair of hair cutting units 150, 160, and 170. For example, the first electrode 180a is positioned in the lateral portion of the skin contact area 200 between the pair of hair cutting units consisting of the first hair cutting unit 150 and the third hair cutting unit 170. 【0037】 During use, electrodes 180a-c are configured to warm the user's skin by applying N periodic amplitude-modulated RF energy signals to it. In this case, electrodes 180a-c are made of a conductive material that can transmit N periodic amplitude-modulated RF energy signals and is biocompatible with the skin. For example, electrodes 180a-c are made of a metal such as stainless steel, silver, or silver chloride. In this case, electrodes 180a-c are also electrically isolated from each other so that a "circuit" is formed between them when the electrodes are in contact with the user's skin. 【0038】 As shown in Figure 2, each of the hair cutting units 150, 160, and 170 has corresponding geometric center points 156, 166, and 176. Each of the N electrodes 180a to c also has its own geometric center points 182a to c. The first pitch distance 202 is the distance between the geometric center points 156, 166, and 176 of the pairs of hair cutting units 150, 160, and 170. As shown in Figure 2, each of the hair cutting units 150, 160, and 170 is positioned such that the first pitch distance 202 between each pair of hair cutting units 150, 160, and 170 is substantially the same. However, in other examples, the first pitch distance 202 between pairs of hair cutting units 150, 160, and 170 may be different. Similarly, the second pitch distance 204 is the distance between the geometric center points 182a to c of the pairs of N electrodes 180a to c. As shown in Figure 2, each of the N electrodes 180a-c is positioned such that the second pitch distance 204 between each pair of the N electrodes 180a-c is substantially the same. However, in other examples, the distances between pairs of hair cutting units 150, 160, and 170 may differ. Regardless of the arrangement, the first minimum pitch distance 202 is the minimum of the first pitch distances for all pairs of hair cutting units 150, 160, and 170, and the second minimum pitch distance 204 is the minimum of the second pitch distances for all pairs of the N electrodes 180a-c. To provide skin heating over a large portion of the skin contact area 200, the ratio between the second minimum pitch distance 204 and the first minimum pitch distance 202 is at least 0.8. In this ratio, the N electrodes 180a-c are evenly distributed across most of the skin contact area 200 together with the hair cutting units 150, 160, and 170, which in this case leads to more uniform heating of the skin in contact with the skin contact area 200 during use. For example, due to the arrangement of the N electrodes 180a-c, RF energy flows between each of the N electrodes 180a-c, and as a result, most of the skin in contact with the skin contact area 200 is heated by the application of RF energy. 【0039】 As described above, the electric shaver according to the example of the present disclosure comprises an RF energy generator unit configured to provide each of the N electrodes 180a to c with a corresponding one of N periodic amplitude modulated RF energy signals. Each of the N periodic amplitude modulated RF energy signals is phase-shifted from one another over N phases, resulting in RF energy flowing in varying amounts between the different electrodes over N phases, which leads to increased uniform heating of the skin contact area of ​​the electric shaver according to the example of the present disclosure and the skin in contact with it. 【0040】 Figure 3 shows an example of circuit configuration 300. Circuit configuration 300 includes an RF energy generator unit 120, which is included in an electric shaver according to an example of the present disclosure. The RF energy generator unit 120 has a fundamental frequency f RF and fundamental period T RF The RF energy generator unit 120 is configured to generate RF energy having a voltage V. The RF energy generator unit 120 further comprises an RF energy modulator 310 configured to convert the RF energy generated by the RF generator into N periodic amplitude modulated RF energy signals, and to provide each of the N periodic amplitude modulated RF energy signals to each of the N electrodes. As described in more detail below, the RF energy modulator 310 receives RF energy from the RF energy generator 320 and provides at least one RF voltage signal V. RF The system includes a converter unit 312 configured to output an RF voltage signal V. RF The output is sent to the switch module 314, which outputs N periodic amplitude-modulated RF energy signals to N electrodes 180. As will be described in more detail below, the RF energy modulator 310 is configured to convert the RF energy generated by the RF generator 320 into N periodic amplitude-modulated RF energy signals under the control of the microcontroller unit (MCU) 330. 【0041】 For example, the MCU330 receives the RF voltage signal V output from the converter unit 312.RF However, the RF energy modulator 310 is controlled by the switch module 314 so that it is modulated according to the RF modulated waveform. The RF modulated waveform has a fundamental RF energy signal. The fundamental period T of the RF modulated waveform MOD This is the RF period T of the RF energy output from the RF energy generator 320. RF It is larger than. In some examples, the period T of the RF modulated waveform MOD The RF period is T RF It is substantially larger than, for example, at least 10 times, preferably at least 25 times. By modulating the RF energy output from the RF energy generator 320 with an RF modulated waveform having a period larger than the period of the RF energy, the phases of the N periodically amplitude modulated RF energy signals are shifted relative to one another without using bulky and expensive RF phase steering components. Instead, with proper control of the switch module 314, the N periodically amplitude modulated RF energy signals are applied to the N electrodes 180, and each of the N periodically amplitude modulated RF energy signals is phase-shifted relative to one another. For example, the nth of the N periodically amplitude modulated RF energy signals is phase-shifted relative to the first of the N periodically amplitude modulated RF energy signals. MOD The phase is shifted by a difference of *(n-1) / N, where 2 ≤ n ≤ N. Therefore, when N=3, the N periodic amplitude modulated RF energy signals are shifted from each other by three phases in order to be applied to electrode 180. 【0042】 Figures 4a to 4c show examples of RF signals applied to N electrodes. In the examples shown in Figures 4a to 4c, N=3. 【0043】 Figure 4a shows the RF voltage signal V RF Three modulation signals M1, M2, and M3 are shown for modulating the signal. The first modulation signal M1 is the RF voltage signal V applied to the first electrode. RF This is for modulating the RF voltage signal V applied to the second electrode. RFThis is for modulating the RF voltage signal V applied to the third electrode. RF This is for modulating the RF. The three modulated signals M1, M2, and M3 have the same RF modulated waveform. In the example shown in Figure 4a, the RF modulated waveform has a two-state modulated waveform, and therefore the modulated signals M1 to M3 are two-state modulated signals. The two-state modulated signals M1 to M3 have a first state +1 and a second state 0. 【0044】 Each of the N modulated signals M1, M2, and M3 has a modulation period T. MOD It has three phases Φ 1~3 It is divided into N modulated signals M1, M2, and M3, each of which has three phases Φ 1~3 They are phase-shifted from each other over a certain period. As shown in the diagram, during the first phase Q1, the first modulated signal M1 is in the second state 0; during the second phase Q2, the first modulated signal M1 is in the first state +1; and during the third phase Q3, the first modulated signal M1 is in the second state 0. In this case, the second modulated signal M2 is phase-shifted from the first modulated signal M1 by 1 phase unit, and the third modulated signal is phase-shifted from the first modulated signal M1 by 2 phase units. In this case, the nth of the N modulated signals M1 to M3 is phase-shifted from the 1st of the N modulated signals M1 to M3 by T MOD They are phase-shifted from each other according to the condition that they have a phase difference of *(n-1) / N, where 2 ≤ n ≤ N. 【0045】 Figure 4b shows N periodic amplitude modulated RF voltage signals S1-S3 applied to N electrodes, which in some examples may be called N periodic amplitude modulated RF energy signals S1-S3. The first periodic amplitude modulated RF energy signal S1 is applied to the first electrode, the second periodic amplitude modulated RF energy signal S2 is applied to the second electrode, and the third periodic amplitude modulated RF energy signal S3 is applied to the third electrode. The first, second, and third periodic amplitude modulated RF energy signals S1-S3 are formed by modulating the RF voltage signals according to the first, second, and third modulated signals M1-M3, respectively. In this case, in a similar manner to the N modulated signals M1-M3, the N periodic amplitude modulated RF energy signals are also formed such that the nth of the N periodic amplitude modulated RF energy signals S1-S3 is T MOD The phases are shifted from each other according to the condition that they have a phase difference of *(n-1) / N, where 2 ≤ n ≤ N. In some examples, the RF voltage signal V RF The disconnection modulation is performed by appropriate control of the switch module 314 shown in Figure 3, as will be described in more detail below. 【0046】 As shown in Figure 4b, the RF voltage signal is a modulated RF voltage signal, for example, the fundamental RF frequency f RF A pulse-width modulation (PWM) signal is constructed having the following characteristics. In this case, referring to Figures 4a and 4b, the modulation signals M1 to M3 are in phase Φ of the first state +1. 1~3 During this time, N periodic amplitude-modulated RF energy signals S1~S3 constitute a PWM RF voltage signal, and the modulated signals M1~M3 are in phase Φ of the first state +1. 1~3During this time, the N periodic amplitude-modulated RF energy signals S1 to S3 constitute a zero-voltage signal. For example, referring to Figure 4a, in the first phase Φ1, the first modulated signal M1 and the second modulated signal M2 are in the second state 0, and the second modulated signal M2 is in the first state +1. In this case, referring to Figure 4b, in the first phase Φ1, the first periodic amplitude-modulated RF energy signal S1 and the third periodic amplitude-modulated RF energy signal S3 are at the 0 voltage level, and the second periodic amplitude-modulated RF energy signal S2 is modulated according to the PWM RF voltage signal. 2~3 During this time, N periodic amplitude-modulated RF energy signals S1 to S3 are output in the same way, depending on whether the corresponding modulation signals M1 to M3 are in a first state + 1 or a second state 0. In some examples, the modulation signals M1 to M3 thus represent the envelope of the N periodic amplitude-modulated RF energy signals S1 to S3. 【0047】 As shown in Figure 4b, in some examples, the first states of N periodic amplitude-modulated RF energy signals S1 to S2 do not occur simultaneously. For example, N periodic amplitude-modulated RF energy signals S1 to S3 occur simultaneously with the RF voltage signal V RF In some examples, this is sometimes referred to as the "first state" of N periodic amplitude-modulated RF energy signals S1~S3, but this state consists of three phases Φ 1~3 Within any single phase, no multiple of the N periodic amplitude-modulated RF energy signals S1 to S3 occur simultaneously. 【0048】 Figure 4c shows RF electrode pair signals indicating the flow of RF current between electrodes E1 to E3. In some examples, the RF electrode pair signals indicate the flow of RF energy between electrodes E1 to E3. For example, the first RF electrode pair signal E1-E2 indicates the flow of RF energy between the first electrode E1 and the second electrode E2, the second RF electrode pair signal E2-E3 indicates the flow of RF energy between the second electrode E2 and the third electrode E3, and the third RF electrode pair signal E3-E1 indicates the flow of RF energy between the third electrode E3 and the first electrode E1. 【0049】 RF energy flows between different electrodes E1 to E3 through three phases Φ 1~3 Throughout the Φ1 phase, RF energy flows according to N periodic amplitude-modulated RF energy signals S1-S3 applied to electrodes E1-E3 during any one phase. For example, during the first phase Φ1, RF energy signals exist between the first electrode E1 and the second electrode E2, and between the second electrode E2 and the third electrode E3, which are represented by the first RF electrode pair signals E1-E2 and the second RF electrode pair signals E2-E3, respectively. However, during the first phase Φ1, there is no flow of RF energy between the third electrode E3 and the first electrode E1, which is represented by the 0 signal level of the third RF electrode pair signal E3-E1. This is due to the N periodic amplitude-modulated RF energy signals S1-S3 applied to electrodes E1-E3 during the first phase Φ1. For example, referring to Figure 4b, in the first phase Φ1, the modulated RF voltage signal is applied to the second electrode E2, which is indicated by the second periodically amplitude-modulated RF energy signal S2. However, a zero voltage signal is applied to the first electrode E1 and the third electrode E3, which is indicated by the first periodically amplitude-modulated RF energy signal S1 and the third periodically amplitude-modulated RF energy signal S3. In this case, referring again to Figure 4c, during the first phase Φ1, a voltage difference exists between the second electrode E2 and both the first electrode E1 and the third electrode E3. Therefore, a flow of RF energy occurs between these electrodes, which is indicated by the first RF electrode pair signals E1-E2 and the second RF electrode pair signals E2-E3. In some examples, this flow of RF energy is represented by the RF voltage signal V RF This corresponds to the magnitude of Φ1. However, during the first phase Φ1, there is no voltage difference between the first electrode E1 and the third electrode E3, and the voltage applied to both electrodes is 0. Therefore, during the first phase Φ1, there is no flow of RF energy between these electrodes, which is shown in the third RF electrode pair signal E3-E1. 【0050】 Second and third phase Φ 2~3During this time, N periodic amplitude-modulated RF energy signals S1-S3 change, and therefore the RF electrode pair signals E1-E2, E2-E3, and E3-E1 also change accordingly. In this way, the first, second, and third phases Φ 1~3 Throughout this process, a flow of RF energy occurs between different electrodes E1-E3, which results in more uniform heating of the skin in contact with the three electrodes E1-E3. 【0051】 Figures 4a to 4c illustrate how an RF voltage signal can be amplitude-modulated according to a two-state modulation waveform to apply N phase-shifted periodic amplitude-modulated RF energy signals to N electrodes. However, in other examples, alternative modulation waveforms can be used to modulate the amplitude of the RF voltage signal, or even the amplitude of a bipolar RF voltage signal. 【0052】 Figures 5a to 5c show examples of RF signals applied to N electrodes. In the examples shown in Figures 5a to 5c, N=3. 【0053】 Figure 5a shows the bipolar RF voltage signal V RF+ , V RF- Three modulation signals M1, M2, and M3 are shown, which are used to modulate the signal. Here again, the nth of the N modulation signals M1 to M3 is the first of the N modulation signals M1 to M3, and T MOD According to the condition that there is a phase difference of *(n-1) / N, the modulation period T MOD Three phases Φ between them 1~3 They are phase-shifted from each other across the range. In the example shown in Figure 5a, the modulated signals M1 to M3 each comprise an asymmetric three-state modulated waveform. The asymmetric three-state modulated waveform comprises a first state +1, a second state 0, and a third state -1. 【0054】 In the same manner as described above with respect to Figures 4a to 4c, N modulation signals M1 to M3, which constitute the asymmetric three-state modulated waveform signal in Figure 5a, are applied to the RF voltage signal to generate N periodic amplitude modulated RF energy signals S1 to S3. However, an additional third state-1 of the asymmetric three-state modulated waveform means that the N periodic amplitude modulated RF energy signals S1 to S3 can adopt an additional signal state. In such an example, the third state-1 means that the N periodic amplitude modulated RF energy signals S1 to S3 are positive RF voltage signal V corresponding to the first state+1. RF+ The inverted form is a negative RF voltage signal V RF- This corresponds to adopting the second state 0, which again corresponds to a 0 voltage signal. In several examples, according to this disclosure, references to “positive voltage signal” and “negative voltage signal” may refer not to the polarity of the voltage signal, but rather to one being the inverse of the other. 【0055】 Figure 5b shows the first, second, and third periodic amplitude modulated RF voltage signals S1-S3, which in some examples may be referred to as N periodic amplitude modulated RF energy signals S1-S3. According to the modulated signals M1-M3 in Figure 5a, the N periodic amplitude modulated RF energy signals S1-S3 are applied to the first, second, and third electrodes E1-E3, respectively. In this case, the first, second, and third periodic amplitude modulated RF energy signals S1-S3 also correspond to the modulated signals M1-M3 in Figure 5a, with a modulation period T MOD Between them, three phases Φ 1~3 They are phase-shifted from each other over a certain distance. 【0056】 As described above, the first modulation state +1 is a positive RF voltage signal V RF+ It corresponds to the third modulation state -1, which is a negative RF voltage V RF- These two RF voltage signals correspond to the same fundamental RF frequency f. RFIt may have, but may also have inverted versions of each other. The second state 0 corresponds to a 0 voltage signal. In this case, the periodic amplitude modulated RF energy signals S1 to S3 are positive RF voltage signals V depending on the state of the corresponding modulated signals M1 to M3 between a given phase. RF+ , negative RF voltage V RF- It has either a value of 0 or a 0 voltage signal. 【0057】 For example, referring to Figure 5a, during the first phase Φ1, the first modulated signal M1 is in the third state -1, the second modulated signal M2 is in the first state +1, and the third modulated signal M3 is in the second state 0. Referring to Figure 5b, during the first phase Φ1, the first amplitude-modulated RF energy signal S1 is a negative RF voltage V RF- The second amplitude-modulated RF energy signal S2 is a positive RF voltage V RF+ The third amplitude-modulated RF energy signal S2 includes a 0 voltage signal. The second and third phase Φ 2~3 During this time, N periodic amplitude-modulated RF energy signals S1 to S3 are output in the same way, depending on whether each modulated signal M1 to M3 is in the first state +1, the second state 0, or the third state -1. In some examples, modulated signals M1 to M3 thus represent the envelope of N periodic amplitude-modulated RF energy signals S1 to S3. 【0058】 As shown in Figure 5b, in some examples, the second states of the N periodic amplitude-modulated RF energy signals S1-S2 do not occur simultaneously. For example, the fact that the N periodic amplitude-modulated RF energy signals S1-S3 consist of zero-voltage signals may be called the "first state" of the N periodic amplitude-modulated RF energy signals S1-S3 in some examples, but this state is one of three phases Φ 1~3 Within any single phase, no multiple of the N periodic amplitude-modulated RF energy signals S1 to S3 occur simultaneously. 【0059】 Figure 5c shows the RF electrode pair signals E1-E2, E2-E3, and E3-E1, and the RF energy flow between electrodes E1-E3 is shown in the same manner as in Figure 4c above. In the same manner as above, the RF energy flows between different electrodes E1-E3 in three phases Φ 1~3 The RF energy flows in varying amounts over time, according to N periodic amplitude-modulated RF energy signals S1-S3 applied to electrodes E1-E3 during any one phase. For example, during the first phase Φ1, a larger amount of RF energy flows between the first electrode E1 and the second electrode E2 compared to the RF energy flow between the second electrode E2 and the third electrode E3, and between the third electrode E3 and the first electrode E1. This is shown in Figure 5c, which means that the magnitude of the first RF electrode pair signal E1-E2 is greater than that of the second and third RF electrode pair signals E2-E3 and E3-E1. The reason for this is that during the first phase Φ1, the negative RF voltage signal V RF- A positive RF voltage signal V is applied to the first electrode E1. RF+ This is because a voltage is applied to the second electrode E2, while a 0 voltage signal is applied to the third electrode E3. In this case, during the first phase Φ1, there is a 2V voltage between the first electrode E1 and the second electrode E2. RF A voltage difference of V exists. On the other hand, between the second electrode E2 and the third electrode E3, and between the third electrode E3 and the first electrode E1, RF A voltage difference exists. Therefore, during the first phase Φ1, the RF energy flow between the first electrode E1 and the second electrode E2 is twice that of the RF energy flow between the second electrode E2 and the third electrode E3, and between the third electrode E3 and the first electrode E1. 【0060】 Second and third phase Φ 2~3 During this time, N periodic amplitude-modulated RF energy signals S1-S3 change, and therefore the RF electrode pair signals E1-E2, E2-E3, and E3-E1 also change accordingly. In this way, the first, second, and third phases Φ 1~3Throughout this process, different amounts of RF energy flow occur between different electrodes E1-E3, which results in more uniform heating of the skin in contact with the three electrodes E1-E3. 【0061】 Figures 6a to 6c show examples of RF signals applied to N electrodes. In the examples shown in Figures 6a to 6c, N=3. 【0062】 Figure 6a shows a bipolar RF voltage signal V in the same format as the modulated signal described in Figure 5a. RF+ , V RF- Three modulation signals M1, M2, and M3 are shown, which are used to modulate the signal. Here again, the nth of the N modulation signals M1 to M3 is the first of the N modulation signals M1 to M3, and T MOD According to the condition that there is a phase difference of *(n-1) / N, the modulation period T MOD Three phases Φ between them 1~3 They are phase-shifted from each other over a certain distance, where 2 ≤ n ≤ N. 【0063】 In the example in Figure 6a, the modulated signals M1 to M3 each have a symmetrical three-state modulated waveform. The symmetrical three-state modulated waveform comprises a first state +1, a second state 0, and a third state -1, which, as described above with respect to Figures 5a to 5c, again correspond to a positive RF voltage signal V RF+ , 0 voltage signal, and negative RF voltage V RF- This can correspond to the following. In this case, in the same manner as described above with respect to Figures 5a to 5c, the three modulated signals M1, M2, and M3 are used to modulate the bipolar RF voltage signal to generate three periodic amplitude modulated RF signals S1 to S3 that are applied to three corresponding electrodes E1 to E3. Three phase Φ 1~3 The periodic amplitude-modulated RF signals S1-S3, which vary over time, in this case cause a change in the flow of RF energy between the three electrodes E1-E3, as shown by the RF electrode pair signals E1-E2, E2-E3, and E3-E1 in Figure 6c. Thus, the first, second, and third phases Φ 1~3Throughout this process, a flow of RF energy occurs between different electrodes E1-E3, which results in more uniform heating of the skin in contact with the three electrodes E1-E3. 【0064】 Figures 4a-4c, 5a-5c, and 6a-6c show the fundamental RF frequency f RF and RF period T RF An RF voltage signal having the RF period T is amplitude-modulated with a modulated waveform. RF This document demonstrates how N periodic amplitude-modulated RF signals with substantially smaller modulation periods can be generated. Thus, these N periodic amplitude-modulated RF signals can be phase-shifted from one another without the use of bulky and expensive RF phase-steering devices. Figures 4a-4c, 5a-5c, and 6a-6c illustrate how the above RF voltage signal can be modulated according to 2-state, asymmetric 3-state, and symmetric 3-state modulation waveforms. However, those skilled in the art will understand that other suitable modulation waveforms can be used to amplitude modulate an RF voltage signal according to the examples of this disclosure. 【0065】 Figure 7 shows an example of circuit configuration 700. Circuit configuration 700 has elements in common with circuit configuration 300 described above, and these are given corresponding reference numbers, and they operate substantially in the same way as described above with respect to Figure 3. 【0066】 Circuit configuration 700 uses an RF frequency signal f RF The system includes an RF generator 320 configured to output the frequency f of the RF frequency signal. In some examples, the frequency f of the RF frequency signal is RF The range is 500kHz to 10MHz. The RF generator 320 generates an RF frequency signal f RF The frequency generator 320 is equipped with an oscillator for generating a frequency. The oscillator may be implemented with or without a counter or frequency divider. The frequency generator 320 is controlled by a PWM control signal from a microcontroller unit (MCU) 330. C It receives the RF frequency signal f due to the variation in the duty cycle of the PWM control signal.RF The frequency may vary. In some examples, the duty cycle of the PWM control signal PWM C is 0% to 100% and has a period of 1 ms to 10 ms. In other examples, a part of the MCU 330 is formed by the functionality of the frequency generator 320, and in that case the MCU 330 directly outputs the RF frequency signal f RF . 【0067】 The circuit configuration 700 further includes an RF modulator 310, and the RF modulator 310 further includes a converter unit 312 and a switch module 314. The converter unit 312 is configured to receive the RF frequency signal f RF and convert the RF frequency signal f RF into a bipolar RF voltage signal V RF+ , V RF- . The converter unit 312 includes a positive converter unit 710 and a negative converter unit 720. In some examples, the positive converter unit 710 and the negative converter unit 720 each include a switching power supply such as a boost converter. In this case, a battery voltage V BATT may be additionally supplied to each of the positive converter unit 710 and the negative converter unit 720. In this case, the positive converter unit 710 is configured to convert the RF frequency signal f RF into a positive RF voltage signal V RF+ , and the negative converter unit 720 is configured to convert the RF frequency signal f RF into a negative RF voltage signal V RF- . In an example according to the present disclosure, the terms positive RF voltage signal V RF+ and negative RF voltage signal V RF- do not indicate the polarity of the signal, but may indicate that each signal is inverted with respect to the other. For example, the positive RF voltage signal V RF+ and the negative RF voltage signal V RF- each include a PWM RF voltage signal oscillating at the frequency RF frequency signal f RF , but one is phase-shifted by 180° from the other. In some examples, the positive RF voltage signal V RF+ and the negative RF voltage signal V RF-Each unit has a peak voltage of 10V to 100V. In one example, the positive converter unit 710 and the negative converter unit 720 each have a switch-mode power supply, and the output of the positive converter unit 710 and the negative converter unit 720 is an RF frequency signal f RF Modulated by the PWM positive RF voltage signal V RF+ and PWM negative RF voltage signal V RF- These are each generated. 【0068】 The circuit configuration 700 further comprises a switch module 314 which includes a plurality of switch units 730, 740, and 750. Each of the plurality of switch units 730, 740, and 750 includes a corresponding pair of switches. The first switch unit 730 includes a first switch 732 and a second switch 734. The second switch unit 740 includes a third switch 742 and a fourth switch 744. The third switch unit 750 includes a fifth switch 752 and a sixth switch 754. 【0069】 Switch module 314 receives a positive RF voltage signal V RF+ and a negative RF voltage signal V RF- The system is configured to receive the signal and output N periodic amplitude-modulated RF signals S1, S2, and S3 to N electrodes 180a to c. In the example shown in Figure 7, N=3. 【0070】 In this case, the MCU330 receives a positive RF voltage signal V RF+ and negative RF voltage signal V RF Control signals En for controlling switches 732-754 of switch units 730, 740, and 750 to modulate the amplitude and generate N periodic amplitude modulated RF signals S1-S3. 1~6 It was configured to output the following. 【0071】 As described above with respect to Figures 5a to 5c and Figures 6a to 6c, there are multiple phases Φ 1~3Over time, N periodic amplitude modulated RF signals S1-S3 transition between three values ​​depending on the modulation waveform used to generate the N periodic amplitude modulated RF signals S1-S3. In some examples, the three values ​​are a positive RF voltage signal V RF+ And a 0 voltage signal and a negative RF voltage signal V RF- It consists of the following. In this case, the MCU330 has N periodic amplitude modulated RF signals S1 to S3 and a positive RF voltage signal V RF+ , 0 voltage signal, and negative RF voltage signal V RF- The switch units 730, 740, and 750 are configured to control the operation of switches 732 to 754 so that one of the three values ​​is output to electrodes 180a to c. 【0072】 For example, referring briefly to Figure 5b, during the first phase Φ1, the first amplitude-modulated RF energy signal S1 is a negative RF voltage V RF- The second amplitude-modulated RF energy signal S2 is a positive RF voltage V RF+ The third amplitude-modulated RF energy signal S2 is a 0 voltage signal. In this case, referring again to Figure 7, the MCU 330 controls the switches 732-754 of the switch units 730, 740, and 750 to output N periodic amplitude-modulated RF signals S1-S3 having values ​​outlined in the first phase Φ1 of Figure 5b, and the third amplitude-modulated RF energy signal S2 is a 0 voltage signal. 1~6 Outputs. 【0073】 For example, a negative RF voltage signal V RF- In order to output the first periodic amplitude modulated RF signal S1, the MCU330 outputs a first control signal En1 to activate the first switch 732 so that the first electrode 180a is connected to the output of the negative converter unit 720. The MCU330 also outputs a second control signal En2 to deactivate the second switch 734 so that the first electrode 180a is not connected to the output of the positive converter unit 710. 【0074】 Positive RF voltage signal V RF+In order to output a second periodic amplitude modulated RF signal S2, the MCU330 outputs a fourth control signal En4 to activate a fourth switch 744 to connect the second electrode 180b to the output of the positive converter unit 710. In this case, the MCU330 also outputs a third control signal En3 to disable a third switch 742 so that the second electrode 180b is not connected to the output of the negative converter unit 720. 【0075】 In order to output a third periodic amplitude modulated RF signal S3 with a 0 voltage signal, the MCU330 outputs a fifth control signal En5 and a sixth control signal En6 to disable the fifth switch 752 and the sixth switch 754, respectively. The node between the third switch unit 750 and the third electrode 180c is floated in this case so that no voltage signal or 0 voltage signal is applied to the third electrode 180c during the first phase Φ1 in Figure 5b. 【0076】 Therefore, according to the example of this disclosure, the MCU330 controls multiple phases Φ by appropriate control of switches 732-754 of switch units 730, 740, and 750. 1~3 The system is configured to vary N periodic amplitude modulated RF signals S1 to S3 across each of the Φ. Electrodes 180a to c are configured to receive N periodic amplitude modulated RF signals S1 to S3 in this case, and the RF energy is then divided into multiple phases Φ. 1~3 The fluid flows through the user's skin between electrodes 180a and 180c, potentially causing skin heating. 【0077】 The circuit configuration 700 further includes a low-dropout regulator (LDO) 760. The LDO 760 controls the battery voltage V BATT When it drops to a low level, the battery voltage V BATT It is configured to be adjustable. 【0078】 The circuit configuration 700 further comprises a plurality of sense resistors 770a-c, each comprising a first sense resistor 770a, a second sense resistor 770b, and a third sense resistor 770c. The first, second, and third sense resistors 770a-c are each positioned in close proximity to the first, second, and third electrodes 180a-c, respectively. In this case, the plurality of sense resistors 770a-c are configured to measure the temperature of the surface of the corresponding electrodes 180a-c and the skin in contact with the electrode surface. In the example shown in Figure 7, each of the plurality of sense resistors 770a-c comprises a resistor with a negative temperature coefficient (NTC). In one example, each of the plurality of sense resistors 770a-c forms part of a voltage divider. In this case, the plurality of sense resistors 770a-c are connected to the MCU 330, in which case the voltage values ​​of each of the sense resistors 770a-c are used as safety control elements. In one example, the MCU responds to the temperature of any one of several sense resistors 770a~c rising above a threshold by issuing a PWM control signal. C By changing the RF frequency signal f RF It is configured to reduce and lower the temperature applied to the user's skin. 【0079】 Figures 8a and 8b show the simulation results of RF heating of the skin surface in contact with electrodes 180a-c placed on the cutting head of an electric shaver. 【0080】 Figure 8a shows results obtained using an electric shaver according to an example of the present disclosure, in which N periodic amplitude-modulated RF energy signals are applied to electrodes 180a-c. The user's skin surface was heated to 41.7°C over 5 seconds. As shown, a flow of RF energy occurs between each of electrodes 180a-c. Furthermore, as shown, the skin penetration is approximately 0.9 mm between each of electrodes 180a-c. Because the skin heating penetration is the same between each of the electrodes, this results in more uniform heating of the skin in contact with electrodes 180a-c at the cutting head of the electric shaver. 【0081】 Figure 8b shows the results obtained using an electric shaver, where single-phase RF energy is applied to electrodes 180a-c. The first electrode 180a receives a 0 voltage signal, and the second electrode 180b receives a positive RF voltage signal V RF+ In response, the third electrode 180c receives a negative RF voltage signal V RF- The user's skin was heated to 45.3°C over 5 seconds. Although the temperature heating is higher than that provided by the electric shaver in the example of the present disclosure shown in Figure 8a, the RF energy flow by the shaver shown in Figure 8b is less uniform. As shown, a large RF energy flow occurs between the second electrode 180b and the third electrode 180c. However, the RF energy flow between the first electrode 180a and both the second electrode 180b and the third electrode 180c is reduced. A penetration of 1.4 mm occurs between the second electrode 180b and the third electrode 180c, and the skin heating penetration between these electrodes is also high, while the penetration that occurs between the first electrode 180a and both the second electrode 180b and the third electrode 180c is approximately 0.5 mm. The non-uniformity of the RF energy flow and skin penetration results in a "hotspot" sensation on the user's skin, which is unpleasant. The electric shaver according to the example of the present disclosure shown in Figure 8a heated a 13% larger area of ​​skin without generating hot spots. 【0082】 Examples described in this disclosure include the placement of electrodes within the skin contact area of ​​an electric shaver, with these electrodes adjacent to the hair cutting units of the electric shaver between corresponding pairs of hair cutting units in the lateral portion of the skin contact area. However, other arrangements of the hair cutting units and electrodes are possible, as described below. 【0083】 Figure 9 shows another example of the skin contact area 910 of the electric shaver 900. The electric shaver 900 has elements in common with the skin contact area 200 of the electric shaver described above with respect to Figure 2, and these are given corresponding reference numbers and are substantially the same as those described above. 【0084】 In this case, the electric shaver 900 comprises first, second, and third cutting units 150, 160, and 170. The first, second, and third cutting units 150, 160, and 170 each comprise corresponding covering elements in the form of first, second, and third electrodes 180a to c. In such an example, the first, second, and third electrodes 180a to c are each arranged on the first, second, and third external cutting members 152, 162, and 172 in a manner substantially corresponding to the first, second, and third covering elements 154, 164, and 174 described above with respect to Figure 1. The first, second, and third covering elements are in this case formed of a conductive material for transmitting RF voltage signals. An RF generator unit configured to output N periodic amplitude-modulated RF signals as described above is in this case electrically connected to each of the electrodes 180a to c. During use, N periodic amplitude-modulated RF signals are applied to electrodes 180a-c in the manner corresponding to those described above. In this way, during use, RF energy flows between electrodes 180a-c within the user's skin, warming the skin. 【0085】 The first, second, and third electrodes 180a-c are electrically isolated from other elements of the skin contact area 910 such that the RF voltage "circuit" is completed only when electrodes 180a-c are applied to the user's skin. For example, each of the electrodes 180a-c is electrically isolated from its corresponding external cutting members 152, 162, and 172 by separating the two elements with an insulating material such as non-conductive plastic. 【0086】 Due to the arrangement of electrodes 180a-c in the electric shaver 900, the geometric center points of each hair cutting unit 150, 160, and 170 are aligned with the respective geometric center points of electrodes 180a-c. The first pitch distance 202 between the geometric center points 156, 166, and 176 of each pair of hair cutting units 150, 160, and 170 is the same as the second pitch distance 204 between the geometric center points of each pair of electrodes 180a-c. In the example of the electric shaver 900, the ratio between the second minimum pitch distance 204 and the first minimum pitch distance 202 is 1. Thus, the electrodes 180a-c are again distributed across the main area of ​​the skin contact area 910, and therefore, as a result of this arrangement, more uniform heating is achieved over a large area of ​​skin in contact with the skin contact area 910 during use. For example, due to the arrangement of N electrodes 180a to c, RF energy flows between each of the N electrodes 180a to c, and as a result, most of the skin in contact with the skin contact area 200 is heated by the application of RF energy. 【0087】 The examples presented so far have illustrated the teachings of this disclosure in relation to rotary shavers. However, the teachings of this disclosure can also be additionally applied to other forms of electric shavers, such as foil shavers. 【0088】 Figure 10 shows an example of electric shaver 1000. The electric shaver has elements in common with electric shaver 100 described above, and they are given corresponding reference numbers and operate substantially in the same way as described above. 【0089】 The electric shaver 1000 is in the form of a foil shaver. Accordingly, the cutting head 140 comprises first, second, and third hair cutting units 150, 160, and 170. Each hair cutting unit 150, 160, and 170 comprises a corresponding internal cutting member, such as a blade, and a corresponding external cutting member 152, 162, and 172 having a plurality of hair entry openings. The hair entry openings comprise holes and / or fins. Each external cutting member 152, 162, and 172 comprises a corresponding skin contact area that comes into contact with the user's skin when the shaver 1000 is in use. The hair entry openings are part of the skin contact area. In the embodiment of Figure 10, each external cutting member 152, 162, and 172 is a shaving foil extending parallel to the longitudinal direction. External cutting members 152, 162, and 172 are positioned to cover the corresponding internal cutting members, which are movable relative to the external cutting members. For example, the blades reciprocate linearly parallel to the longitudinal direction of the foil. Hairs protrude through the openings in the foils 152, 162, and 172, and are cut by the reciprocating motion of the blades, with the cut ends collected in the hair collection area of ​​the shaver 1000. The electric shaver 1000 thus further comprises a motor 130 configured to move the internal cutting members relative to the corresponding external cutting members 152, 162, and 172 so that a cutting action occurs. 【0090】 The RF generator energy unit 120 is configured to apply N periodic amplitude modulated RF signals to the skin through the skin contact area provided by the external cutting members 152, 162, and 172 of the respective hair cutting units 150, 160, and 170. For example, each of the external cutting members 152, 162, and 172 of the respective hair cutting units 150, 160, and 170 is formed of a conductive material that is biocompatible with the skin and capable of transmitting N periodic amplitude modulated RF signals, such as a metal such as stainless steel, silver, or silver chloride. Thus, the entire set of external cutting members 152, 162, and 172 is configured to transmit N periodic amplitude modulated RF signals. In other words, the external cutting members 152, 162, and 172 function as N electrodes for applying N periodic amplitude modulated RF signals to the user's skin to warm the skin. Each of the N electrodes in this case is composed of at least the skin-contact portion of one of the corresponding external cutting members 152, 162, and 172 from the four hair cutting units 150, 160, and 170. Each of the external cutting members 152, 162, and 172 is additionally electrically isolated from each other in this case by the electric shaver 1100. For example, there are gaps between each of the external cutting members 152, 162, and 172 that electrically isolate them from each other. In this way, when the external cutting members 152, 162, and 172 are brought into contact with the user's skin, a "circuit" is formed between them. 【0091】 Figure 11 shows another example of the electric shaver 1100. The electric shaver 1100 shares elements with the electric shaver 1000 described above, and they are given corresponding reference numbers and operate substantially in the same manner as described above. 【0092】 The electric shaver 1100 comprises a skin contact area 1110, which includes first and second hair cutting units 150, 160, and 170. As described above, the external cutting members 152, 162, and 172 function as N electrodes for warming the skin by applying N periodic amplitude modulated RF signals to the user's skin. In the arrangement of the electric shaver 1100, the geometric center points 156, 166, and 176 of each of the hair cutting units 150, 160, and 170 are aligned with the geometric center points of each of the electrodes in this case. The first pitch distance 202 between the geometric center points 156, 166, and 176 of each pair of hair cutting units 150, 160, and 170 is in this case the same as the second pitch distance 204 between the geometric center points of each pair of electrodes. In the example of the electric shaver 1100, the ratio between the second minimum pitch distance 204 and the first minimum pitch distance 202 is 1 in this case. Thus, the electrodes 180a to c are again distributed over the main area of ​​the skin contact area 1110, and as a result of this arrangement, more uniform heating is achieved over a large area of ​​skin in contact with the skin contact area 1110 during use. For example, due to the arrangement of the external cutting members 152, 162, and 172 which function as N electrodes, RF energy flows between each of the N electrodes, and as a result, a large portion of the skin in contact with the skin contact area 1110 is heated by the application of RF energy. 【0093】 Figures 12a and 12b show examples of how RF signals can be applied to the external cutting members 152, 162, and 172 of the foil shaver type hair cutting units 150, 160, and 170. 【0094】 Figure 12a shows N modulation signals M1 to M3, where N=3. In this case, the N modulation waveforms M1 to M3 are the RF voltage signals V applied to the first electrode. RF A first modulation signal M1 for modulating the signal, and an RF voltage signal V applied to the second electrode. RF A second modulation signal M2 for modulating the signal, and an RF voltage signal V applied to the third electrode. RFIt consists of a third modulation signal M3 for modulating the first, second, and third electrodes, which comprise the first, second, and third external cutting members 152, 162, and 172 of the electric shaver. 【0095】 Each of the N modulated signals M1 to M3 has a two-state modulated waveform consisting of a first state +1 and a second state 0. As described above with respect to Figures 4a to 4c, the N modulated signals M1 to M3 in two states have the nth of the N modulated signals M1 to M3 being T MOD According to the condition that there is a phase difference of *(n-1) / N, the modulation period T MOD Three phases Φ between them 1~3 The phases are shifted from each other over a certain distance, where 2 ≤ n ≤ N. Therefore, in the same manner as described above with respect to Figures 4a to 4c, the N modulated signals M1 to M3 generate N periodic amplitude modulated RF energy signals applied to the N electrodes, and the RF voltage signal V RF It is used to modulate the amplitude. 【0096】 Figure 12b shows N periodic amplitude modulated RF voltage signals, which in some examples are called N periodic amplitude modulated RF energy signals, with three phases Φ 1~3This shows how it can be applied to the external cutting members 152, 162, and 172 of the electric shaver. In a similar manner to that described above with respect to Figures 4a to 4c, the N periodic amplitude modulated RF energy signals have a first value of +V for the RF voltage signal or a second value of 0V for the zero voltage signal, depending on the state of the corresponding N modulated signals M1 to M3 during a given phase. Referring to Figure 12a, during the first phase Φ1, the first modulated signal M1 is in the first state +1, and the second modulated signal M2 and the third modulated signal M3 are in the second state 0. In this case, referring to Figure 12b, during the first phase Φ1, the first external cutting member 152 receives the first periodic amplitude modulated signal which is the RF voltage signal +V, and both the second external cutting member 162 and the second external cutting member 172 receive the second and third periodic amplitude modulated signals which are the zero voltage signals 0V, respectively. In this case, a flow of RF energy occurs between the first external cutting member 152 and both the second external cutting member 162 and the second external cutting member 172, warming the user's skin. 【0097】 Regarding Figures 4a to 4c, the second and third phases Φ are determined in the same manner as described above. 2~3 During this time, N periodic amplitude-modulated RF energy signals change according to N modulation signals M1 to M3, and as a result, the flow of RF energy between the external cutting members 152, 162, and 172 changes accordingly. In some examples, modulation signals M1 to M3 thus represent the envelope of N periodic amplitude-modulated RF energy signals. Thus, the first, second, and third phases Φ 1~3 Throughout this process, RF energy flows between different external cutting members 152, 162, and 172, which leads to more uniform heating of the skin in contact with the external cutting members 152, 162, and 172. 【0098】 A simulation was performed to measure skin heating using an electric shaver employing modulated signals M1-M3 as shown in Figures 12a-12b. These heating results were compared with a simulation of skin heating using an electric shaver equipped with three shaver foil electrodes to which an unmodulated RF signal was applied. The electric shaver employing modulated signals M1-M3 as shown in Figures 12a-12b heated a 25% larger volume of skin compared to the electric shaver employing an unmodulated RF signal. In the above example, for both shavers, the two foil electrodes located on the sides of the configuration, e.g., the first external cutting member 152 and the third external cutting member 172, had a skin contact area of ​​4 × 25 mm, and the central foil electrode, e.g., the second external cutting member 162, had a skin contact area of ​​5 × 25 mm, with each foil electrode separated by a 4 mm electrical isolation gap. The electric shaver employing modulated signals M1-M3 used a peak-to-peak voltage of magnitude 11 V, while the electric shaver employing an unmodulated RF signal used a voltage of magnitude 19 V. 【0099】 Figures 13a and 13b show another example of how RF signals can be applied to the external cutting members 152, 162, and 172 of the hair cutting units 150, 160, and 170 of the foil shaver. 【0100】 Figure 13a shows N modulation signals M1 to M3, where N=3. In the same manner as described above, for Figures 12a to 12b, the N modulation signals M1 to M3 generate N periodic amplitude-modulated RF energy signals applied to N electrodes, and the RF voltage signal V RF It is used to modulate the amplitude. As shown in Figure 13b, the N electrodes are provided with the first, second, and third external cutting members 152, 162, and 172 of the electric shaver. 【0101】 Referring again to Figure 13a, the N modulated signals M1 to M3 each have an asymmetrical three-state modulated waveform. In the same manner as described above with respect to Figures 5a to 5c, the N modulated signals M1 to M3 in Figure 13a are such that the nth of the N modulated signals M1 to M3 is T MOD According to the condition that there is a phase difference of *(n-1) / N, the modulation period T MOD Three phases Φ between them 1~3 They are phase-shifted from each other over a certain distance, where 2 ≤ n ≤ N. Therefore, in the same manner as described above with respect to Figures 5a to 5c, the N modulation signals M1 to M3 are used to modulate the amplitudes of the positive RF voltage signal +V and the negative RF voltage signal -V in order to generate N periodic amplitude-modulated RF energy signals applied to the N electrodes. 【0102】 Referring to Figure 13b, N periodic amplitude modulated RF voltage signals, sometimes called N periodic amplitude modulated RF energy signals S1 to S3, in this case have three phases Φ 1~3 The first, second, and third external cutting members 152, 162, and 172 of the electric shaver are subjected to this force. Thus, as described above with respect to Figures 5a to 5c, the first, second, and third phases Φ 1~3 Throughout this process, different amounts of RF energy flow occur between different external cutting members 152, 162, and 172E1-E3, which results in more uniform heating of the skin in contact with the three electrodes E1-E3. 【0103】 We have thus presented an example according to this disclosure in which N=3 for N electrodes and N periodic amplitude modulated RF energy signals. However, in other examples, N may be greater than 3, for example, N=4. 【0104】 Figure 14 shows an example of the electric shaver 1400. The electric shaver 1400 has elements in common with the electric shaver 1100 described above, and they are given corresponding reference numbers and operate substantially in the same way as described above. 【0105】 The electric shaver 1400 comprises a skin contact area 1410, which includes first, second, and third hair cutting units 150, 160, and 170, and additionally a fourth hair cutting unit 1480. The fourth hair cutting unit 1480 additionally comprises a fourth external cutting member 1480 of the type of shaver foil. The fourth hair cutting unit 1480 and the fourth external cutting member 1480 in this case operate substantially in accordance with the hair cutting units 150, 160, and 170 and external cutting members 152, 162, and 172 described above with respect to Figure 11. The fourth external cutting member 1480 in this case is formed of a conductive material capable of transmitting the fourth of N periodic amplitude modulated RF signals. Thus, the entire external cutting member 1482 is configured to transmit the fourth of N periodic amplitude modulated RF signals. In other words, the fourth external cutting member 1480 functions as a fourth electrode for applying N periodic amplitude-modulated RF signals to the user's skin to warm it. 【0106】 As described above, the external cutting members 152, 162, 172, and 1482 function as N electrodes for applying N periodic amplitude modulated RF signals to the user's skin to warm it. Due to the arrangement of the electric shaver 1400, the geometric center points 156, 166, 176, and 1486 of the hair cutting units 150, 160, 170, and 1480 are aligned in this case with the geometric center points of the electrodes. The first pitch distance 202 between the geometric center points 156, 166, and 176 of each pair of hair cutting units 150, 160, and 170 is in this case the same as the second pitch distance 204 between the geometric center points of each pair of electrodes 180a to c. In the example of the electric shaver 1400, the ratio between the second minimum pitch distance 204 and the first minimum pitch distance 202 is in this case 1. Thus, the electrodes are again distributed across the main area of ​​the skin contact area 1110, and as a result of this arrangement, more uniform heating is achieved over a large area of ​​skin in contact with the skin contact area 1110 during use. 【0107】 Figures 15a and 15b show examples of how RF signals can be applied to the external cutting members 152, 162, 172, and 1482 of the hair cutting units 150, 160, 170, and 1480 of the foil shaver. 【0108】 Figure 15a shows N modulation signals M1 to M4, where N=4. The N modulation waveforms M1 to M4 are the RF voltage signal V applied to the first electrode. RF A first modulation signal M1 for modulating the signal, and an RF voltage signal V applied to the second electrode. RF A second modulation signal M2 for modulating the signal, and an RF voltage signal V applied to the third electrode. RF A third modulation signal M3 for modulating the signal, and an RF voltage signal V applied to the fourth electrode. RF It consists of a fourth modulation signal M4 for modulating the first, second, third, and fourth electrodes, which comprise the first, second, third, and fourth external cutting members 152, 162, 172, and 1482 of the electric shaver. 【0109】 The N modulated signals M1 to M4 each consist of an asymmetric four-state modulated signal, comprising a first state +1, a second state +1 / 3, a third state -1 / 3, and a fourth state -1. Each of the N modulated signals M1, M2, M3, and M4 has a modulation period T. MOD It has a period of Φ 1~4 It is divided into four phases. In this case, with respect to Figures 4a-4c, 5a-5c, 6a-6c, 12a-12c, and 13a-13c, in the same manner as described above, the N modulated signals M1-M4 are divided such that the nth of the N modulated signals M1-M4 is T MOD According to the condition that there is a phase difference of *(n-1) / N, the modulation period T MOD Four phases Φ between them 1~4 They are phase-shifted from each other over a certain distance, where 2 ≤ n ≤ N. 【0110】 Figure 15b shows N periodic amplitude modulated RF voltage signals, which in some examples may be called N periodic amplitude modulated RF energy signals S1 to S3, with four phases Φ 1~4 This shows how the signals are applied to the external cutting members 152, 162, 172, and 1482 of the electric shaver. In a similar manner to that described above, the N periodic amplitude modulated RF energy signals have multiple values, consisting of a first value +V of the RF voltage signal, a second value +V / 3 of the RF voltage signal, a third voltage signal -V / 3 of the RF voltage signal, and a fourth value -V of the RF voltage signal, depending on the state of the corresponding N modulated signals M1 to M4 during a given phase. In some examples, the modulated signals M1 to M3 thus represent the envelope of the N periodic amplitude modulated RF energy signals S1 to S3. 【0111】 In some examples, the RF generator unit 312 described above generates an RF voltage signal +V / 3 to produce a second voltage value of +V / 3 and a third voltage value of -V / 3. RF / 3 and -V RF An additional converter unit is provided for generating / 3. In such an example, the switch unit 314 further includes an additional switch for applying a second voltage value of +V / 3 and a third voltage value of -V / 3 to N electrodes in this case. 【0112】 In the examples shown in Figures 15a to 15c, the ratio between the magnitudes of the first and fourth voltage values ​​+V, -V and the second and third voltage values ​​+V / 3, -V / 3 is 0.33. However, in other examples, the ratio between the magnitudes of these voltages may be between 0.25 and 0.5, preferably between 0.3 and 0.35. 【0113】 Referring to Figure 15a, during the first phase Φ1, the first modulation signal M1 is in the first state +1, the second modulation signal M2 is in the second state +1 / 3, the third modulation signal M3 is in the third state -1 / 3, and the fourth modulation signal M4 is in the fourth state -1. In this case, referring to Figure 15b, during the first phase Φ1, the first external cutting member 152 receives the first periodic amplitude modulation signal which is the first value +V, the second external cutting member 162 receives the second periodic amplitude modulation signal which is the second value +V / 3, the third external cutting member 172 receives the third periodic amplitude modulation signal which is the third value -V / 3, and the fourth external cutting member 1482 receives the fourth periodic amplitude modulation signal which is the fourth value -V. In this case, in the same manner as described above, a voltage difference exists between the external cutting members 152, 162, 172, and 1482 of the electric shaver during the first phase Φ1, causing a flow of RF energy between the external cutting members 152, 162, 172, and 1482, which warms the user's skin. 【0114】 The second, third, and fourth phases Φ are in the same format as described above. 2~4 During this time, N periodic amplitude-modulated RF energy signals change based on N modulation signals M1 to M4, and as a result, the flow of RF energy between the external cutting members 152, 162, 172, and 1482 changes accordingly. Thus, the first, second, third, and fourth phases Φ 1~4 Throughout this process, RF energy flows in different amounts between different external cutting members 152, 162, 172, and 1482, which leads to more uniform heating of the skin in contact with the external cutting members 152, 162, 172, and 1482. 【0115】 A simulation was performed to measure skin heating using an electric shaver employing modulated signals M1-M4 as shown in Figures 15a-15b. These heating results were compared with a simulation of skin heating using an electric shaver equipped with four shaver foil electrodes to which an unmodulated RF signal was applied. The electric shaver using modulated signals M1-M4 as shown in Figures 15a-15b heated 60% more skin volume compared to the electric shaver using an unmodulated RF signal. In the above example, for both shavers, the foil electrodes of the first external cutting member 152, the second external cutting member 162, the third external cutting member 172, and the fourth external cutting member 1482 had a skin contact area of ​​4 × 25 mm, and each foil electrode was separated by a 4 mm electrical isolation gap. The electric shaver using modulated signals M1-M3 used a peak-to-peak voltage of magnitude 11 V, while the electric shaver using an unmodulated RF signal used a voltage of magnitude 19 V. 【0116】 Figure 16 shows another example of the electric shaver 1600. The electric shaver 1600 has elements in common with the electric shaver 900 described above with respect to Figure 9. The corresponding elements are given corresponding reference numbers and they operate in a manner corresponding to those described above. 【0117】 The electric shaver 1600 comprises a skin contact area 1610, which includes first, second, and third hair cutting units 150, 160, and 170, each having corresponding covering elements in the form of first, second, and third electrodes 180a to c, respectively, in a manner similar to the electric shaver 900 described above. The electric shaver 1600 further comprises a fourth hair cutting unit 1680, which has a covering element in the form of a fourth electrode 180d. In this case, the fourth covering element is additionally formed of a conductive material for transmitting RF voltage signals. An RF generator unit configured to generate N periodic amplitude modulated RF signals as described above is electrically connected to each of the electrodes 180a to d. During use, the N periodic amplitude modulated RF signals are applied to the electrodes 180a to d in the manner corresponding to those described above. In this way, during use, RF energy flows between the electrodes 180a to d within the user's skin, warming the skin. 【0118】 Due to the arrangement of electrodes 180a to 180d in the electric shaver 1600, the geometric center points of each hair cutting unit 150, 160, 170, and 1680 are aligned with the respective geometric center points of electrodes 180a to 180d. The first pitch distance 202 between the geometric center points 156, 166, 176, and 1686 of each pair of hair cutting units 150, 160, 170, and 1680 is the same as the second pitch distance between the geometric center points of each pair of electrodes 180a to 180d. In the example of the electric shaver 1600, the ratio between the second minimum pitch distance 204 and the first minimum pitch distance 202 is 1. Thus, electrodes 180a to d are again distributed across the main area of ​​the skin contact area 910, and as a result of this arrangement, more uniform heating is achieved in a large area of ​​skin in contact with the skin contact area 1610 during use. For example, due to the arrangement of N electrodes 180a to d, RF energy flows between each of the N electrodes 180a to d, and as a result, a large portion of the skin in contact with the skin contact area 200 is heated by the application of RF energy. 【0119】 Figures 17a and 17b show another example of how an RF signal is applied to the electrodes of an electric shaver. 【0120】 Figure 17a shows N modulation signals M1 to M4, where N=4. The N modulation waveforms M1 to M4 are the RF voltage signal V applied to the first electrode. RF A first modulation signal M1 for modulating the signal, and an RF voltage signal V applied to the second electrode. RF A second modulation signal M2 for modulating the signal, and an RF voltage signal V applied to the third electrode. RF A third modulation signal M3 for modulating the signal, and an RF voltage signal V applied to the fourth electrode. RF This consists of a fourth modulation signal M4 for modulating the first, second, third, and fourth electrodes 180a to 1880, which are covered elements of the hair cutting units 150, 160, 170, and 1680, respectively. 【0121】 Each of the N modulated signals M1 to M4 comprises a two-state modulated signal consisting of a first state +1 and a second state 0. In the same manner as described above with respect to Figures 15a to 15b, each of the N modulated signals M1 to M4 has four phases Φ 1~4 The modulation period T is divided into MOD It has the following characteristics. In this case, in the same manner as described above, the N modulated signals M1 to M4 are such that the nth of the N modulated signals M1 to M4 is T MOD According to the condition that there is a phase difference of *(n-1) / N, the modulation period T MOD Four phases Φ between them 1~4 They are phase-shifted from each other over a certain distance, where 2 ≤ n ≤ N. 【0122】 In a manner similar to that described above, N periodic amplitude-modulated RF voltage signals, sometimes referred to as N periodic amplitude-modulated RF energy signals in some examples, are generated by applying N modulation signals M1 to M4 to an RF voltage signal. In a manner similar to that described above, the N periodic amplitude-modulated RF energy signals have multiple values, consisting of a first value +V for the RF voltage signal and a second value 0V for the zero voltage signal, depending on the state of the corresponding N modulation signals M1 to M4 during a given phase. 【0123】 For example, referring to Figure 17a, during the first phase Φ1, the first modulation signal M1 is in the second state 0, the second modulation signal M2 is in the second state 0, the third modulation signal M3 is in the first state +1, and the fourth modulation signal M4 is in the first state +1. In this case, referring to Figure 17b, during the first phase Φ1, the first electrode 180a receives the first periodic amplitude modulation signal with a second value of 0V, the second electrode 180b receives the second periodic amplitude modulation signal with a second value of 0V, the third electrode 180d receives the third periodic amplitude modulation signal with a first value of +V, and the fourth electrode 180d receives the fourth periodic amplitude modulation signal with a first value of +V. In this case, in the same manner as described above, a voltage difference exists between the electrodes 180a to d of the electric shaver during the first phase Φ1, which causes a flow of RF energy between the electrodes 180a to d, warming the user's skin. 【0124】 The second, third, and fourth phases Φ are in the same format as described above. 2~4 During this time, N periodic amplitude-modulated RF energy signals change based on N modulation signals M1~M4, and as a result, the RF energy flow between electrodes 180a~d changes accordingly. In some examples, modulation signals M1~M3 thus represent the envelope of N periodic amplitude-modulated RF energy signals S1~S3. Thus, the first, second, third, and fourth phases Φ 1~4 Throughout this process, a flow of RF energy occurs between different electrodes 180a to d, which results in more uniform heating of the skin in contact with electrodes 180a to d. 【0125】 In carrying out the principles and techniques described herein, those skilled in the art can understand and implement variations of the disclosed embodiments by examining the drawings, this disclosure, and the appended claims. In the claims, the words “equip,” “include,” and “have” do not exclude other elements or steps, and singular elements do not exclude plural elements. A single processor or other unit may perform some of the functions described in the claims. The mere fact that certain techniques are described in different dependent claims does not imply that combinations of these techniques cannot be used advantageously. Computer programs may be stored or distributed on suitable media such as optical storage media or solid-state media supplied together with or as part of other hardware, or they may be distributed in other forms, for example, via the Internet or other wired or wireless telecommunications systems. No reference numeral in the claims should be construed as limiting its scope.

Claims

[Claim 1] The skin contact area for contact with the user's skin during use of the electric shaver, At least two hair cutting units disposed within the skin contact area, each having an external cutting member having a plurality of hair entry openings, and an internal cutting member covered by the external cutting member and movable relative to the external cutting member, N electrodes, which are arranged within the skin contact area so as to come into contact with the skin during use, where N is at least 3, fundamental frequency f ＲＦ and fundamental period T ＲＦ = 1 / f ＲＦ A high-frequency generator that generates high-frequency energy having, A high-frequency energy modulator that converts the high-frequency energy generated by the high-frequency generator into N periodic amplitude modulated high-frequency energy signals, and provides each of the N periodic amplitude modulated high-frequency energy signals to a corresponding one of the N electrodes, An electric shaver equipped with, When viewed perpendicular to the skin contact area, the external cutting member of each hair cutting unit has a geometric center point, a first pitch distance which is the distance between the geometric center points of a pair of hair cutting units, and a first minimum pitch distance which is the minimum of the first pitch distances of all pairs of hair cutting units. When viewed perpendicular to the skin contact area, each of the N electrodes has a geometric center point, a second pitch distance which is the distance between the geometric center points of the pair of N electrodes, and a second minimum pitch distance which is the minimum value of the second pitch distance for all pairs of the N electrodes. The ratio between the second minimum pitch distance and the first minimum pitch distance is at least 0.

8. The fundamental period T of the N periodic amplitude modulated high-frequency energy signals ＭＯＤ is the fundamental period T ＲＦ Larger than, The nth of the N periodic amplitude modulated high-frequency energy signals is T compared to the first of the N periodic amplitude modulated high-frequency energy signals. ＭＯＤ An electric shaver having a phase difference of (n-1) / N, where 2 ≤ n ≤ N. [Claim 2] T ＭＯＤ and T ＲＦ The electric shaver according to claim 1, wherein the ratio between and is at least 10, preferably at least 25. [Claim 3] Each of the N periodic amplitude-modulated high-frequency energy signals has the same basic high-frequency energy signal during the basic period T of each of the periodic amplitude-modulated high-frequency energy signals. ＭＯＤ The electric shaver according to claim 1, which has the same basic high-frequency energy signal during the basic period T of each of the N periodic amplitude-modulated high-frequency energy signals. [Claim 4] The aforementioned fundamental high-frequency energy signal comprises a first state and a second state, wherein the first state is the fundamental frequency f ＲＦ and the first high-frequency voltage (V ＲＦ＋ , V ＲＦ- The electric shaver according to claim 3, comprising a first high-frequency energy signal having ) and the second state comprising a zero signal (0V). [Claim 5] The electric shaver according to claim 4, further comprising a third state in which the basic high-frequency energy signal is composed of a second high-frequency energy signal obtained by inverting the first high-frequency energy signal. [Claim 6] The electric shaver according to claim 4, wherein the first states of the N periodic amplitude-modulated high-frequency energy signals do not occur simultaneously. [Claim 7] The electric shaver according to claim 4, wherein the second state of the N periodic amplitude-modulated high-frequency energy signals does not occur simultaneously. [Claim 8] The electric shaver according to any one of claims 1 to 7, wherein the N electrodes are arranged adjacent to the hair cutting unit. [Claim 9] The electric shaver according to claim 8, comprising three electrodes and three hair cutting units arranged in a triangular configuration with respect to each other, wherein the internal cutting member of each hair cutting unit is rotatable relative to the external cutting member, and each of the three electrodes is positioned in the lateral portion of the skin contact area between two hair cutting units of one pair of the hair cutting units. [Claim 10] An electric shaver according to any one of claims 1 to 7, comprising N hair cutting units, wherein the external cutting member of each of the N hair cutting units is ring-shaped, and the N electrodes each comprises N covering elements positioned at the center of each of the N hair cutting units relative to the external cutting member. [Claim 11] An electric shaver according to any one of claims 1 to 7, comprising N hair cutting units, wherein each of the N electrodes is composed of at least the skin contact portion of each of the external cutting members of the N hair cutting units. [Claim 12] The electric shaver according to claim 11, comprising three hair cutting units, wherein the internal cutting member of each hair cutting unit reciprocates linearly parallel to the longitudinal direction relative to the external cutting member, and the external cutting member of each hair cutting unit has a longitudinal extension parallel to the longitudinal direction. [Claim 13] It is equipped with four electrodes and four hair cutting units. The internal cutting member of each hair cutting unit moves linearly back and forth parallel to the longitudinal direction relative to the external cutting member, and the external cutting member of each hair cutting unit has a longitudinal extension parallel to the longitudinal direction. Each of the four electrodes is composed of at least the skin contact portion of the external cutting member of each of the four hair cutting units, The fundamental high-frequency energy signal comprises a first state, a second state, a third state, and a fourth state in succession, the first state being composed of a first high-frequency energy signal having the fundamental frequency fRF and a first high-frequency voltage, and the second state being composed of the fundamental frequency f ＲＦ The electric shaver according to claim 3, comprising a second high-frequency energy signal having a second high-frequency voltage lower than the first high-frequency voltage, the third state comprising a third high-frequency energy signal obtained by inverting the second high-frequency energy signal, and the fourth state comprising a fourth high-frequency energy signal obtained by inverting the first high-frequency energy signal. [Claim 14] The electric shaver according to claim 13, wherein the ratio between the second high-frequency voltage and the first high-frequency voltage is between 0.25 and 0.5, preferably between 0.3 and 0.

35. [Claim 15] The electric shaver according to any one of claims 1 to 7, wherein the high-frequency energy modulator comprises N switch units, and each of the N switch units applies each of the N periodic amplitude modulated high-frequency energy signals to each of the N electrodes.

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