Electric shaver

Abstract

According to one aspect, there is provided a powered shaver (100, 900, 1000, 1100, 1400, 1600), the powered shaver comprising: a skin contact area (200, 910, 1100, 1400, 16100) arranged to contact a skin of a user during use of the shaver (100, 900, 1000, 1100, 1400, 1600); at least two hair cutting units (150, 160, 170, 148, 168) arranged in the skin contact area (200, 910, 1100, 141, 1610) and each having an outer cutting member (152, 162, 172, 148, 1682) with a plurality of hair entry openings and an inner cutting member covered by and movable relative to the outer cutting member (152, 162, 172, 148, 1682); n electrodes (180a-d) arranged in the skin contact area (200, 910, 1111, 141, 1610) to contact the skin during use, wherein N is at least 3; a radio frequency (RF) generator (320) configured to generate RF energy having a fundamental frequency fRF and a fundamental period TRF = 1 / fRF; 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 (S1, S2, S3) to a respective one of the N electrodes (180a-d); wherein: the outer cutting member (152, 162, 172, 148, 168) of each hair cutting unit (150, 160, 170, 148, 168) has a geometric center point (156, 166, 176, 148, 168), a first pitch (202), and a first minimum pitch, the first pitch being a distance between geometric center points (156, 166, 176, 148, 168) of a hair cutting unit pair of the hair cutting units (150, 160, 170, 148, 168), and the first minimum pitch being a distance between geometric center points (156, 166, 176, 148, 168) of the hair cutting units (150, 160, 170, 148, 168) of the hair cutting units (150, 160, 170, 148, 168). 1680) of the first pitch of all the pairs of hair cutting units; each of the N electrodes (180a-d) has a geometric center point (182a-c) and a second minimum pitch, viewed perpendicular to the skin contact area (200, 910, 1100, 141, 1610), the second pitch (204) being a distance between geometric center points (182a-c) of one of the N electrode pairs (180a-d), and the second minimum pitch being a minimum of the second pitches (204) of all of the N electrode pairs (180a-d); the ratio between the second minimum pitch and the first minimum pitch is at least 0.8; the basic period TMOD of the N periodic amplitude modulated RF energy signals (S1, S2, S3) is greater than the basic period TRF; and an nth periodic amplitude-modulated RF energy signal of the N periodic amplitude-modulated RF energy signals (S1, S2, S3) has a phase difference of TMOD * (U-1) / N with respect to a first periodic amplitude-modulated RF energy signal of the N periodic amplitude-modulated RF energy signals, where 2 < = n < = N.

Description

Technical Field

[0001] The present application relates to an electric shaver and in particular to an electric shaver including a radio frequency (RF) generator unit for heating the skin in use. Background Art

[0002] It is generally believed that heating the skin within a certain temperature range (e.g., about 38° C. to 40° C.) can induce a pleasant thermal sensation. Skin warming methods include applying hot towels, steam, infrared light, etc. to the skin. Integrating a skin warming unit in a personal care device can generally improve the sensory experience of the user during the performance of a personal care routine.

[0003] One such personal care device that employs a skin warming unit is an electric shaver. Electric shavers are known to include a heated mechanical element that can provide warmth to the skin via heat transfer during shaving. The warmth creates a pleasant sensation, thereby improving the user experience.

[0004] Another method of heating the skin is the use of deep skin heating using radio frequency (RF) energy. The use of RF energy is different from the use of heating mechanical elements that provide heating using heat transfer. In RF heating applications, two electrodes are applied to the skin, each electrode applying oppositely charged RF energy to the skin. This generates an electric field in the skin between the two electrodes. Due to the mechanical element of heating, RF energy can penetrate deeper into the skin than heat transfer, and therefore heating can be applied to a relatively large area of ​​the skin. Heating can be applied over the entire penetration depth without having to rely on the thermal conductivity of both the heater and the skin as required using a mechanical element of heating.

[0005] RF-based skin heating first found applications in skin care applications and tissue ablation, for example, tumors in organs can be ablated by applying RF energy to heat the tumor. The ability of RF energy to penetrate deep into skin tissue and the ease of control of RF energy make this technology ideal for these applications.

[0006] Typically, RF energy delivery parameters such as electrical and physical properties, e.g., contact electrode geometry, can be tailored to specific applications. Typically, large RF electrodes receiving low RF voltages are used for skin care applications, while small RF electrodes receiving high RF voltages are used for surgical applications.

[0007] For example, surface RF heating applications used in home skin care devices involve the use of bipolar RF energy, where two contact electrodes are placed substantially close to each other and the current is concentrated in a small area. In contrast, clinical RF heating applications use a method known as monopolar RF, where one contact electrode is placed away from the other (multiple) electrodes to cause the current to flow through the body.

[0008] Another RF skin heating method for clinical applications is to apply RF energy to the skin using several electrodes (e.g., more than two), and phase shift or steer the RF energy applied to each electrode. For example, US5383917 discloses a multi-phase RF ablation technique that uses a two-dimensional or three-dimensional electrode array to generate multiple current paths on the surface of the ablation area, thereby generating a uniform lesion whose size is defined by the span of the electrode array. US20130231611 discloses an electrosurgical method and apparatus for applying phase-controlled RF energy to a treatment site, comprising a multi-electrode electrosurgical probe electrically coupled to multiple RF generators. Summary of the invention

[0009] One of the challenges of heating skin tissue using bipolar RF energy is to control the uniformity of heating within the tissue volume. When using an electric shaver to RF heat the skin, it is necessary to uniformly heat the skin with minimal hot spots to obtain a pleasant warming experience and avoid any discomfort. Using large and multiple electrodes is a common method to reduce hot spots. However, this effect is limited by the fact that most heating occurs between one of the two closest electrodes. By phase shifting or manipulating RF energy between multiple electrodes, such as described in US5383917 and US20130231611, the RF field can be better distributed in the tissue, thereby producing more uniform tissue heating. However, these solutions use expensive and bulky RF phase manipulation devices to generate multi-phase RF signals. In electric shavers with limited space, it is usually impractical to use such relatively large phase manipulation devices. It has also been observed that the thermal effect of the phase shift or manipulation solution is sensitive to the accuracy of the phase difference between the RF signals.

[0010] Therefore, there is a need for improved systems and methods for improving uniform RF-based warming of the skin using an electric shaver.

[0011] According to a first specific aspect, there is provided an electric shaver comprising: a skin contact area arranged to contact the skin of a user during use of the shaver; at least two hair cutting units arranged in the skin contact area and each having an outer cutting member with a plurality of hair entry openings and an inner cutting member covered by the outer cutting member and movable relative to the outer cutting member; N electrodes arranged in the skin contact area to contact the skin during use, wherein N is at least 3; and a plurality of electrodes configured to generate a hair cutting unit having a fundamental frequency f RF and the basic period T RF =1 / f RFa radio frequency (RF) generator for RF energy; an RF energy modulator configured to transform the RF energy generated by the RF generator into N periodic amplitude modulated RF energy signals and provide each of the N periodic amplitude modulated RF energy signals to a corresponding electrode in the N electrodes; wherein: perpendicular to the skin contact area, the external cutting member of each hair cutting unit has a geometric center point, the first pitch is the distance between the geometric center points of a hair cutting unit pair in the hair cutting unit, and the first minimum pitch is the minimum value of the first pitches of all hair cutting unit pairs in the hair cutting unit; from the perspective of perpendicular to the skin contact area, each of the N electrodes has a geometric center point, the second pitch is the distance between the geometric center points of an electrode pair in the N electrodes, and the second minimum pitch is the minimum value of the second pitches of all electrode pairs in the N electrodes; the ratio between the second minimum pitch and the first minimum pitch is at least 0.8; the basic period T of the N periodic amplitude modulated RF energy signals MOD Greater than the basic period T RF ; and the nth periodic amplitude modulated RF energy signal in the N periodic amplitude modulated RF energy signals has T relative to the first periodic amplitude modulated RF energy signal in the N periodic amplitude modulated RF energy signals MOD *(n-1) / N phase difference, where 2≤n≤N.

[0012] In some examples, T MOD With T RF The ratio between may be at least 10, preferably at least 25.

[0013] In some examples, each of the N periodic amplitude modulated RF energy signals has a fundamental period T of the corresponding periodic amplitude modulated RF energy signal. MOD The same basic RF energy signal can be present during this period.

[0014] In some examples, the base RF energy signal may include a first state and a second state, the first state being a signal having a base frequency f RF and a first RF energy signal of a first RF voltage, and the second state is constituted by a zero signal.

[0015] In some examples, the base RF energy signal may also include a third state consisting of a second RF energy signal that is opposite to the first RF energy signal.

[0016] In some examples, the first states of the N periodically amplitude modulated RF energy signals may not occur simultaneously.

[0017] In some examples, the second states of the N periodically amplitude modulated RF energy signals may not occur simultaneously.

[0018] In some examples, the N electrodes are arranged adjacent to the hair cutting unit.

[0019] In some examples, the electric shaver may include three electrodes and three hair cutting units arranged relative to each other in a triangular configuration, wherein an inner cutting member of each hair cutting unit is rotatable relative to an outer cutting member, and wherein each of the three electrodes is arranged in a lateral portion of a skin contact area between two hair cutting units of a corresponding one of the three hair cutting unit pairs.

[0020] In some examples, the electric shaver may include N hair cutting units, wherein the external cutting member of each of the N hair cutting units is annular, and wherein the N electrodes include N covering elements, each covering element being arranged in a central position relative to the external cutting member of a corresponding hair cutting unit of the N hair cutting units.

[0021] In some examples, the electric shaver may comprise N hair cutting units, wherein each of the N electrodes consists of at least a skin contacting portion of an outer cutting member of a corresponding one of the N hair cutting units.

[0022] In some examples, the electric shaver may include three hair cutting units, wherein the internal cutting member of each hair cutting unit is configured to perform linear reciprocating motion relative to the external cutting member parallel to the longitudinal direction, and wherein the external cutting member of each hair cutting unit has a longitudinal extension parallel to the longitudinal direction.

[0023] In some examples, the electric shaver may include four electrodes and four hair cutting units, wherein: the internal cutting member of each hair cutting unit may be configured to perform linear reciprocating motion relative to the external cutting member parallel to the longitudinal direction, and wherein the external cutting member of each hair cutting unit may have a longitudinal extension parallel to the longitudinal direction; each of the four electrodes may be composed of at least a skin contacting portion of the external cutting member of a corresponding hair cutting unit of the four hair cutting units; the basic RF energy signal may sequentially include a first state, a second state, a third state, and a fourth state, the first state being composed of a first state having a basic frequency f RF and a first RF energy signal of a first RF voltage, and the second state is composed of a first RF energy signal having a fundamental frequency f RF and a second RF energy signal of a second RF voltage lower than the first RF voltage, the third state is constituted by a third RF energy signal opposite to the second RF energy signal, and the fourth state is constituted by a fourth RF energy signal opposite to the first RF energy signal.

[0024] In some examples, the ratio between the second RF voltage and the first RF voltage may be between 0.25 and 0.5, preferably between 0.3 and 0.35.

[0025] In some examples, the RF energy modulator includes N switch units, each switch unit configured to apply a corresponding one of the N periodic amplitude modulated RF energy signals to a corresponding one of the N electrodes.

[0026] These and other aspects will be apparent from and elucidated with reference to the embodiments described hereinafter. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Exemplary embodiments will now be described, by way of example only, with reference to the following drawings, in which:

[0028] Figure 1 is an example of an electric shaver;

[0029] Figure 2 is an example of a cutting head for an electric shaver;

[0030] Figure 3 is an example of a circuit system for applying RF energy to an electrode;

[0031] Figures 4a-4c are examples of RF signals;

[0032] Figures 5a-5c are examples of RF signals;

[0033] Figures 6a-6c are examples of RF signals;

[0034] Figure 7 is another example of a circuit system for applying RF energy to an electrode;

[0035] 8a and 8b are examples of RF energy applied to electrodes of an electric shaver;

[0036] Fig. 9 is another example of a cutting head for an electric shaver;

[0037] Fig.10 is another example of an electric shaver;

[0038] Fig.11 is another example of a cutting head for an electric shaver;

[0039] 12a and 12b are examples of RF energy applied to electrodes of an electric shaver;

[0040] 13a and 13b are another example of RF energy applied to the electrodes of an electric shaver;

[0041] Fig.14 is another example of a cutting head for an electric shaver;

[0042] Fig.15a and Fig.15b is another example of RF energy applied to the electrodes of an electric shaver;

[0043] Fig.16 is another example of a cutting head for an electric shaver; and

[0044] Fig.17a and Fig.17b is another example of RF energy applied to the electrodes of an electric shaver. DETAILED DESCRIPTION

[0045] An example according to the present disclosure provides an electric shaver, which includes a skin contact area arranged to contact the skin of a user during use of the shaver. At least two hair cutting units are arranged in the skin contact area, and N electrodes for conducting RF energy are also arranged in the skin contact area to contact the skin during use, wherein N is at least 3. Perpendicular to the skin contact area, the external cutting member of each hair cutting unit has a geometric center point, and the first pitch is the distance between the geometric center points of a hair cutting unit pair in the hair cutting unit. The first minimum pitch is the minimum value of the first pitches of all hair cutting unit pairs in the hair cutting unit. In addition, perpendicular to the skin contact area, each electrode in the N electrodes has a geometric center point, and the second pitch is the distance between the geometric center points of an electrode pair in the N electrodes. The second minimum pitch is the minimum value of the second pitches of all electrode pairs in the N electrodes. The ratio between the second minimum pitch and the first minimum pitch is at least 0.8. This arrangement of the hair cutting unit and the N electrodes causes the N electrodes to be spread over most of the skin contact area. Thus, when used with a skin contact area applied to a user's skin, RF energy may flow between the N electrodes, causing a majority of the skin in contact with the skin contact area to warm, resulting in improved uniform warming of the skin.

[0046] The electric shaver according to an example of the present disclosure further includes an RF generator and an RF energy modulator, wherein the RF generator is configured to generate a signal having a fundamental frequency f RF and the basic period T RF =1 / f RF The RF energy modulator is configured to transform the RF energy generated by the RF generator into N periodic amplitude modulated RF energy signals and provide each of the N periodic amplitude modulated RF energy signals to a corresponding electrode among the N electrodes. The basic period T of the N periodic amplitude modulated RF energy signals is MOD Greater than the basic period TRF , and the nth periodic amplitude modulated RF energy signal among the N periodic amplitude modulated RF energy signals has T relative to the first periodic amplitude modulated RF energy signal among the N periodic amplitude modulated RF energy signals. MOD *(n-1) / N, where 2≤n≤N. Modulating the RF energy into N periodic amplitude modulated RF energy signals that are phase shifted from one another avoids the use of expensive and cumbersome RF phase manipulation equipment used in prior art solutions. As will be described in more detail below, the phase shifted N periodic amplitude modulated RF energy signals cause the RF energy to follow different amounts between different electrodes of the N electrodes in different time periods, which further causes the skin in contact with the skin contact area to be heated more evenly and the accumulation of hot spots can be avoided.

[0047] Figure 1 is a diagram of an exemplary electric shaver 100 to which the techniques described herein may be applied. Figure 1 In the embodiment, the electric shaver 100 is in the form of a rotary shaver, but it will be appreciated that the techniques described herein may 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 to be held in the hand of a user and a cutting head 140 in the form of a skin contact area, the cutting head comprising a plurality of hair cutting units 150, 160, 170 for cutting / shaving hair. The cutting head of the electric shaver comprises a skin contact area, which is arranged to contact the skin of the user during use of the shaver. In the embodiment of the invention, the electric shaver 100 is in the form of a rotary shaver, but it will be appreciated that the techniques described herein may 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 to be held in the hand of a user and a cutting head 140 in the form of a skin contact area, the cutting head comprising a plurality of hair cutting units 150, 160, 170 for cutting / shaving hair. The cutting head of the electric shaver comprises a skin contact area, which is arranged to contact the skin of the user during use of the shaver. Figure 1 In the example shown, 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 may comprise more than three hair cutting units.

[0048] 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 hair cutting unit 150, the second hair cutting unit 160 and the third hair cutting unit 170 can be installed at a suitable installation position in the cutting head 140. In this illustrated embodiment, the hair cutting units 150, 160, 170 have a triangular arrangement, but it should be understood that the hair cutting units can be arranged with an alternative arrangement. The external cutting members 152, 162, 172 of the hair cutting units each comprise a plurality of hair entry openings, and in use, these hair entry openings are arranged to contact the skin. The corresponding skin contact areas of the first external hair cutting member 152, the second external hair cutting member 162 and the third external hair cutting member 172 are annular (i.e., annular). Each hair cutting unit in the first hair cutting unit 150, the second hair cutting unit 160 and the 3rd hair cutting unit 170 also includes a corresponding internal cutting member, for example, a rotatable blade relative to its corresponding external cutting member 152,162,172. The external cutting member 152,162,172 is arranged to cover its corresponding internal cutting member. The hair entry opening may include a hole and / or a thin slice. In use, hair can therefore protrude through the hair entry opening, and the blade cuts the hair protruding through the opening relative to the rotation of the external cutting member 152,162,172. Therefore, the electric shaver 100 also includes a motor 130, which is configured to move the internal cutting member relative to the corresponding external cutting member 152,162,172 to realize cutting action.

[0049] The first hair cutting unit 150, the second hair cutting unit 160 and the third hair cutting unit 170 also include a first covering element 154, a second covering element 164 and a third covering element 174, respectively. Each of the first covering element 154, the second covering element 164 and the third covering element 174 is arranged on the first external cutting member 152, the second external cutting member 162 and the third external cutting member 172, respectively. The first covering element 154, the second covering element 164 and the third covering element 174 each include a skin contact area, which is arranged to contact the skin during use. Each of the first covering element 154, the second covering element 164 and the third covering element 174 is also centered relative to the corresponding annular skin contact area of ​​the first external cutting member 152, the second external cutting member 162 and the third external cutting member 172, so that the skin contact area of ​​the external cutting members 152, 162, 172 surrounds the corresponding covering element 154, 164, 174. Figure 1As shown, each cover element 154, 164, 174 is annular, and thus the cover element may also be referred to as a cap, a shaving cap or a decorative cap. Other suitable shapes and / or forms of the cover element will be known to those skilled in the art.

[0050] As will be described in more detail below, the electric shaver 100 also includes N electrodes ( Figure 1 100 is a schematic diagram of a shaver 100 having a plurality of electrodes. The shaver ...

[0051] Figure 2 The skin contact area 200 of an electric shaver is illustrated. Thus, the skin contact area may be comprised in a cutting head of an electric shaver. Figure 2 The skin contact area 200 is shown viewed perpendicularly relative 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 can be operated in a corresponding manner, as described above with respect to Figure 1 described.

[0052] The skin contact area 200 further includes a first electrode 180a, a second electrode 180b and a third electrode 180c, which together constitute N electrodes 180a-c. Figure 2 As shown, the N electrodes 180a-c are arranged adjacent to the hair cutting units 150, 160, 170. Therefore, the N electrodes 180a-c and the three hair cutting units 150, 160, 170 are arranged in a triangular configuration with each other, wherein each of the three N electrodes 180a-c is arranged in a lateral portion of the skin contact area 200 between a corresponding one of the three hair cutting unit pairs 150, 160, 170. For example, the first electrode 180a is arranged in a lateral portion of the skin contact area 200 between one of the hair cutting unit pairs including the first hair cutting unit 150 and the third hair cutting unit 170.

[0053] In use, the electrodes 180a-c are configured to apply N periodic amplitude modulated RF energy signals to the user's skin to warm the skin. Thus, the electrodes 180a-c are formed of a conductive material that is capable of conducting the N periodic amplitude modulated RF energy signals but is also biocompatible with the skin. For example, the electrodes 180a-c may be formed of a metal, such as stainless steel, silver, or silver chloride. Thus, the electrodes 180a-c may be otherwise electrically isolated from one another, such that when the electrodes are in contact with the user's skin, a "circuit" is formed between the electrodes.

[0054] like Figure 2 As shown, each of the hair cutting units 150, 160, 170 includes a corresponding geometric center point 156, 166, 176. Each of the N electrodes 180a-c also includes a corresponding geometric center point 182a-c. The first pitch 202 is the distance between the geometric center points 156, 166, 176 of a pair of hair cutting units in the hair cutting units 150, 160, 170. Figure 2 As shown, each of the hair cutting units 150, 160, 170 is arranged such that the first pitch 202 between each pair of hair cutting units in the hair cutting units 150, 160, 170 is substantially the same. However, in other examples, the first pitch 202 between each pair of hair cutting units in the hair cutting units 150, 160, 170 may be different. Similarly, the second pitch 204 is the distance between the geometric center points 182a-c of one electrode pair in the N electrodes 180a-c. Figure 2 As shown, each of the N electrodes 180a-c is arranged so that the second pitch 204 between each pair of electrodes in the N electrodes 180a-c is substantially the same. However, in other examples, the distance between each pair of hair cutting units in the hair cutting units 150, 160, 170 can be different. Regardless of the arrangement, the first minimum pitch 202 is the minimum of the first pitches of all hair cutting unit pairs in the hair cutting units 150, 160, 170, and the second minimum pitch 204 is the minimum of the second pitches of all electrode pairs in the N electrodes 180a-c. In order to provide skin warming over a large portion of the skin contact area 200, the ratio between the second minimum pitch 204 and the first minimum pitch 202 is at least 0.8. With this ratio, the N electrodes 180a-c can be evenly distributed on a major portion of the skin contact area 200 together with the hair cutting units 150, 160, 170, so that the skin in contact with the skin contact area 200 can be warmed more evenly during use. For example, due to the arrangement of the N electrodes 180a-c, RF energy may flow between each of the N electrodes 180a-c, such that a majority of the skin in contact with the skin contact area 200 is warmed by the application of RF energy.

[0055] As described above, an electric shaver according to an example of the present disclosure includes an RF energy generator unit configured to provide a corresponding one of the N periodic amplitude modulated RF energy signals to each of the N electrodes 180a-c. According to an example of the present disclosure, each of the N periodic amplitude modulated RF energy signals is phase-shifted from one another at N phases, so that at the N phases, RF energy flows between different electrodes of the N electrodes in different amounts, which results in increased uniform heating of the skin in contact with the skin contact area of ​​the electric shaver.

[0056] Figure 3 An example of a circuit system 300 is illustrated. The circuit system 300 includes an RF energy generator unit 120, which may be included in an electric shaver according to an example of the present disclosure. The RF energy generator unit 120 includes a circuit configured to generate a RF having a fundamental frequency f RF and the basic period T RF The RF energy generator unit 120 further includes an RF energy modulator 310 configured to transform 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 a corresponding electrode in the N electrodes 180. As will be described in more detail below, the RF energy modulator 310 includes a converter unit 312 configured to receive RF energy from the RF energy generator 320 and output at least one RF voltage signal V RF RF voltage signal V RF is output to the switch module 314, which outputs N periodic amplitude modulated RF energy signals to the N electrodes 180. As will be described in more detail below, under the control of the microcontroller unit (MCU) 330, the RF energy modulator 310 is configured to transform the RF energy generated by the RF generator 320 into N periodic amplitude modulated RF energy signals.

[0057] For example, the MCU 330 may control the RF energy modulator 310 so that the RF voltage signal V output from the converter unit 312 is RF The switching module 314 performs modulation according to the RF modulation waveform. The RF modulation waveform may have a basic RF energy signal. The basic period T of the RF modulation waveform MOD is greater than the RF period T of the RF energy output from the RF energy generator 320 RF In some examples, the period T of the RF modulation waveform MOD Can be compared to the RF period T RFMuch larger, for example, at least 10 times larger, preferably at least 25 times larger. By modulating the RF energy output from the RF energy generator 320 with an RF modulation waveform having a period larger than the period of the RF energy, the phases of the N periodic amplitude modulated RF energy signals can be offset relative to each other without using a large number of expensive RF phase manipulation components. Instead, through appropriate control of the switch module 314, the N periodic amplitude modulated RF energy signals can be applied to the N electrodes 180, wherein each of the N periodic amplitude modulated RF energy signals is phase-shifted relative to each other. For example, the nth periodic amplitude modulated RF energy signal among the N periodic amplitude modulated RF energy signals is phase-shifted by T relative to the first periodic amplitude modulated RF energy signal among the N periodic amplitude modulated RF energy signals. MOD *(n-1) / N, where 2≤n≤N. Therefore, when N=3, N periodic amplitude modulated RF energy signals may be shifted from each other in three phases to be applied to the electrode 180.

[0058] Figures 4a-4c illustrate examples of RF signals applied to N electrodes. In the examples shown in Figures 4a-4c, N=3.

[0059] FIG. 4a illustrates a method for modulating the RF voltage signal V RF The first modulation signal M1 is used to modulate the RF voltage signal V applied to the first electrode. RF The second modulation signal M2 is used to modulate the RF voltage signal V applied to the second electrode. RF The third modulation signal M3 is used to modulate the RF voltage signal V applied to the third electrode. RF The three modulation signals M1, M2, M3 include the same RF modulation waveform. In the example shown in FIG4a, the RF modulation waveform includes a two-state modulation waveform, and therefore, the modulation signals M1-M3 are two-state modulation signals. The two-state modulation signals M1-M3 include a first state +1 and a second state 0.

[0060] Each of the N modulation signals M1, M2, M3 has a modulation period T MOD , the modulation period can be divided into three phases Φ 1-3 Each of the N modulation signals M1, M2, and M3 has three phases Φ 1-3As shown in the figure, during the first phase Q1, the first modulation signal M1 is in the second state 0, during the second phase Q2, the first modulation signal M1 is in the first state +1, and during the third phase Q3, the first modulation signal M1 is in the second state 0. Therefore, the second modulation signal M2 is phase-shifted with the first modulation signal M1, and the third modulation signal is phase-shifted with the first modulation signal M1 by two phases. Therefore, according to the N modulation signals M1-M3, the nth modulation signal has T relative to the first modulation signal in the N modulation signals M1-M3. MOD *(n-1) / N, the modulated signals are phase shifted from each other, where 2≤n≤N.

[0061] FIG4 b illustrates N periodic amplitude modulated RF voltage signals S1-S3 applied to N electrodes, which in some examples may be referred to as N periodic amplitude modulated RF energy signals S1-S3. A first periodic amplitude modulated RF energy signal S1 is applied to a first electrode, a second periodic amplitude modulated RF energy signal S2 is applied to a second electrode, and a third periodic amplitude modulated RF energy signal S3 is applied to a third electrode. The first periodic amplitude modulated RF energy signal S1, the second periodic amplitude modulated RF energy signal S2, and the third periodic amplitude modulated RF energy signal S3 are formed by modulating the RF voltage signal according to a first modulation signal M1, a second modulation signal M2, and a third modulation signal M3, respectively. Therefore, in a manner similar to the N modulation signals M1-M3, the nth periodic amplitude modulated RF energy signal among the N periodic amplitude modulated RF energy signals S1-S3 has T relative to the first periodic amplitude modulated RF energy signal of the N periodic amplitude modulated RF energy signals S1-S3. MOD *(n-1) / N (where 2≤n≤N), the N periodic amplitude modulated RF energy signals are also phase-shifted with respect to each other. In some examples, the RF voltage signal V RF The modulation can be achieved by Figure 3 This is performed by appropriate control of the illustrated switch module 314, as will be described in more detail below.

[0062] As shown in FIG. 4b, the RF voltage signal may include a modulated RF voltage signal, for example, having a fundamental RF frequency f RF Therefore, referring to FIG. 4a and FIG. 4b, when the modulation signal M1-M3 is in the first state +1, the phase Φ 1-3 During the period, the N periodic amplitude modulated RF energy signals S1-S3 include PWM RF voltage signals, and the phase Φ of the modulation signals M1-M3 is in the first state +1. 1-3During the period, the N periodic amplitude modulated RF energy signals S1-S3 include a zero voltage signal. For example, referring to FIG. 4a, in the first phase Φ1, the first modulation signal M1 and the second modulation signal M2 are in the second state 0, and the second modulation signal M2 is in the first state +1. Therefore, referring to FIG. 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 a 0 voltage level, and the second periodic amplitude modulated RF energy signal S2 is modulated according to the PWMRF voltage signal. During the second phase Φ2 and the third phase Φ3, the N periodic amplitude modulated RF energy signals S1-S3 are therefore output in a similar manner, depending on whether their corresponding modulation signals M1-M3 are in the first state +1 or the second state 0. In some examples, the modulation signals M1-M3 can therefore represent the envelope of the N periodic amplitude modulated RF energy signals S1-S3.

[0063] As shown in FIG. 4b, in some examples, the first states of the N periodic amplitude modulated RF energy signals S1-S2 do not occur simultaneously. 1-3 In any phase, no multiple N periodic amplitude modulated RF energy signals S1-S3 include the RF voltage signal V RF , in some examples, this can be referred to as a “first state” of the N periodic amplitude modulated RF energy signals S1 - S3 .

[0064] FIG4c illustrates RF electrode pair signals that illustrate RF current flow between electrodes E1-E3. In some examples, the RF electrode pair signals may illustrate RF energy flow between electrodes E1-E3. For example, a first RF electrode pair signal E1-E2 illustrates RF energy flow between a first electrode E1 and a second electrode E2, a second RF electrode pair signal E2-E3 illustrates RF energy flow between the second electrode E2 and a third electrode E3, and a third RF electrode pair signal E3-E1 illustrates RF energy flow between the third electrode E3 and the first electrode E1.

[0065] The RF energy is applied to the electrodes E1-E3 in three phases Φ according to the N periodic amplitude modulated RF energy signals S1-S3 applied to the electrodes E1-E3 during any one phase. 1-34b, in the first phase Φ1, a modulated RF voltage signal is applied to the second electrode E2, as shown by the second periodic amplitude modulated RF energy signal S2. However, as shown by the first periodic amplitude modulated RF energy signal S1 and the third periodic amplitude modulated RF energy signal S3, a 0 voltage signal is applied to the first electrode E1 and the third electrode E3. Thus, referring again to FIG. 4c, during the first phase Φ1, there is a voltage difference between the second electrode E2 and both the first electrode E1 and the third electrode E3. Thus, RF energy flows between these electrodes as shown by the first RF electrode pair signal E1-E2 and the second RF electrode pair signal E2-E3. In some examples, this RF energy flow may correspond to the RF voltage signal V RF However, during the first phase Φ1, since there is no voltage difference between the first electrode E1 and the third electrode E3, the voltage applied to these two electrodes is 0. Therefore, during the first phase Φ1, no RF energy flows between these electrodes, as shown by the third RF electrode pair signal E3-E1.

[0066] During the second phase Φ2 and the third phase Φ3, the N periodic amplitude modulated RF energy signals S1-S3 change, and thus the RF electrode pair signals E1-E2, E2-E3, E3-E1 also change accordingly. Therefore, during the first phase Φ1, the second phase Φ2 and the third phase Φ3, RF energy flows between different electrodes in the electrodes E1-E3, which results in the skin in contact with the three electrodes E1-E3 being heated more evenly.

[0067] 4a-4c illustrate how the RF voltage signal is amplitude modulated according to a bi-state modulation waveform to apply phase-shifted N periodic amplitude modulated RF energy signals to N electrodes. However, in other examples, alternative modulation waveforms may be used to modulate the amplitude of the RF voltage signal or even a bipolar RF voltage signal.

[0068] Figures 5a-5c illustrate examples of RF signals applied to N electrodes. In the examples shown in Figures 5a-5c, N=3.

[0069] FIG. 5a illustrates a method for modulating a bipolar RF voltage signal VRF+ 、V RF- According to the fact that the nth modulation signal among the N modulation signals M1-M3 has T relative to the first modulation signal among the N modulation signals M1-M3, MOD *(n-1) / N phase difference condition, the modulation signal M1-M3 in the modulation period T MOD Again in three phases Φ 1-3 In the example shown in FIG5a, the modulation signals M1-M3 each include an asymmetric three-state modulation waveform. The asymmetric three-state modulation waveform includes a first state +1, a second state 0, and a third state -1.

[0070] In a similar manner as described above with respect to FIGS. 4a-4c, N modulation signals M1-M3 including the asymmetric tri-state modulation waveform signal of FIG. 5a may be applied to the RF voltage signal to generate N periodic amplitude modulated RF energy signals S1-S3. However, the additional third state -1 of the asymmetric tri-state modulation waveform indicates that the N periodic amplitude modulated RF energy signals S1-S3 may adopt additional signal states. In such an example, the third state -1 may correspond to the N periodic amplitude modulated RF energy signals S1-S3 adopting the negative RF voltage signal V RF- , the negative RF voltage signal is the positive RF voltage signal V corresponding to the first state +1 RF+ The second state 0 may again correspond to a 0 voltage signal. In an example, according to the present disclosure, references to a “positive voltage signal” and a “negative voltage signal” may not refer to the polarity of a voltage signal, but to the fact that one voltage signal is the inverse of another voltage signal.

[0071] FIG5b illustrates an example of a first periodic amplitude modulated RF voltage signal S1, a second periodic amplitude modulated RF voltage signal S2, and a third periodic amplitude modulated RF voltage signal S3, which in some examples may be referred to as N periodic amplitude modulated RF energy signals S1-S3. According to the modulation signals M1-M3 of FIG5a, the N periodic amplitude modulated RF energy signals S1-S3 are applied to the first electrode E1, the second electrode E2, and the third electrode E3, respectively. Therefore, the first periodic amplitude modulated RF energy signal S1, the second periodic amplitude modulated RF energy signal S2, and the third periodic amplitude modulated RF energy signal S3 have a modulation period T MOD In a manner corresponding to the modulation signals M1-M3 of FIG. 5a, the three phases Φ 1-3 Again they are phase shifted towards each other.

[0072] As mentioned above, the first modulation state +1 corresponds to a positive RF voltage signal V RF+ , and the third modulation state -1 corresponds to a negative RF voltage V RF-The two RF voltage signals may include the same fundamental RF frequency f RF , but can be opposite voltage signals to each other. The second state 0 corresponds to a 0 voltage signal. Therefore, the periodic amplitude modulated RF energy signal S1-S3 includes a positive RF voltage signal V RF+ , negative RF voltage V RF- or 0 voltage signal, depending on the state of the corresponding modulation signal M1-M3 during a given phase.

[0073] For example, referring to FIG5a, during the first phase Φ1, the first modulation signal M1 is in the third state -1, the second modulation signal M2 is in the first state +1, and the third modulation signal M3 is in the second state 0. Therefore, as shown in FIG5b, during the first phase Φ1, the first amplitude modulated RF energy signal S1 includes a negative RF voltage V RF- , the second amplitude modulated RF energy signal S2 includes a positive RF voltage V RF+ , the third amplitude modulated RF energy signal S2 includes a 0 voltage signal. Therefore, during the second phase Φ2 and the third phase Φ3, the N periodic amplitude modulated RF energy signals S1-S3 are output in a similar manner according to whether the corresponding modulation signal M1-M3 is in the first state +1, the second state 0 or the third state -1. In some examples, the modulation signal M1-M3 can therefore represent the envelope of the N periodic amplitude modulated RF energy signals S1-S3.

[0074] As shown in FIG. 5b, in some examples, the second states of the N periodic amplitude modulated RF energy signals S1-S2 do not occur simultaneously. 1-3 In other words, in any one phase, none of the plurality of N periodic amplitude modulated RF energy signals S1 - S3 includes a zero voltage signal, which in some examples may be referred to as a “first state” of the N periodic amplitude modulated RF energy signals S1 - S3 .

[0075] FIG5c illustrates RF electrode pair signals E1-E2, E2-E3, E3-E1, illustrating the flow of RF energy between electrodes E1-E3 in a manner similar to FIG4c described above. In a manner similar to that described above, RF energy flows between different electrodes in electrodes E1-E3 and is transmitted in three phases Φ according to N periodic amplitude modulated RF energy signals S1-S3 applied to electrodes E1-E3 during any one phase. 1-3For example, during the first phase Φ1, more RF energy flows between the first electrode E1 and the second electrode E2 than 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 FIG. 5c because the magnitude of the first RF electrode pair signal E1-E2 is greater than the magnitude of the second RF electrode pair signal E2-E3 and the third RF electrode pair signal E3-E1. This is because, during the first phase Φ1, the negative RF voltage signal V RF- is applied to the first electrode E1, and the positive RF voltage signal V RF+ is applied to the second electrode E2, and a 0 voltage signal is applied to the third electrode E3. Therefore, during the first phase Φ1, there is a 2V voltage between the first electrode E1 and the second electrode E2. RF However, there is a voltage difference between the second electrode E2 and the third electrode E3 and between the third electrode E3 and the first electrode E1. RF Therefore, during the first phase Φ1, the RF energy flow between the first electrode E1 and the second electrode E2 is twice the RF energy flow between the second electrode E3 and the third electrode E3 and between the third electrode E3 and the first electrode E1.

[0076] During the second phase Φ2 and the third phase Φ3, the N periodic amplitude modulated RF energy signals S1-S3 change, and thus the RF electrode pair signals E1-E2, E2-E3, E3-E1 also change accordingly. Therefore, during the first phase Φ1, the second phase Φ2, and the third phase Φ3, RF energy flows between different electrodes of the electrodes E1-E3 in different amounts, which results in more uniform heating of the skin in contact with the three electrodes E1-E3.

[0077] Figures 6a-6c illustrate examples of RF signals applied to N electrodes. In the examples shown in Figures 6a-6c, N=3.

[0078] FIG. 6 a illustrates three modulation signals M1 , M2 , M3 , which are used to modulate the bipolar RF voltage signal V in a similar manner to the modulation signals described above in FIG. 5 a . RF+ 、V RF- According to the fact that the nth modulation signal among the N modulation signals M1-M3 has T relative to the first modulation signal among the N modulation signals M1-M3 MOD *(n-1) / N phase difference condition (where 2≤n≤N), in the modulation period T MOD In the internal modulation signal, M1-M3 is again in three phases Φ 1-3 Shifted toward each other.

[0079] In the example shown in FIG6a, the modulation signals M1-M3 each include a symmetrical three-state modulation waveform. The symmetrical three-state modulation waveform includes a first state +1, a second state 0, and a third state -1, which may again correspond to a positive RF voltage signal V RF+ , 0 voltage signal and negative RF voltage V RF- , as described above with respect to FIGS. 5a-5c. Thus, in a similar manner as described above with respect to FIGS. 5a-5c, the three modulation signals M1, M2, M3 can be used to modulate the bipolar RF voltage signal to generate three periodic amplitude modulated RF signals S1-S3 for application to the three corresponding electrodes E1-E3. Thus, the three phases Φ 1-3 The continuously changing periodic amplitude modulated RF signals S1-S3 on the electrode pair result in changes in the RF energy flow between the three electrodes E1-E3, as shown in the RF electrode pair signals E1-E2, E2-E3, and E3-E1 in FIG6c. Therefore, in the first phase Φ1, the second phase Φ2, and the third phase Φ3, the RF energy flows between different electrodes in the electrodes E1-E3, which results in the skin in contact with the three electrodes E1-E3 being heated more evenly.

[0080] FIGS. 4a-4c, 5a-5c and 6a-6c illustrate how a modulation waveform is used to modulate a signal having a fundamental RF frequency f RF and RF period T RF The RF voltage signal is amplitude modulated to generate a modulation period much smaller than the RF period T RF N periodic amplitude modulated RF signals. Therefore, these N periodic amplitude modulated RF signals can be phase-shifted with each other without using bulky and expensive RF phase manipulation equipment. Figures 4a-4c, 5a-5c and 6a-6c illustrate how the above-mentioned RF voltage signal is modulated according to a two-state, an asymmetric three-state and a symmetric three-state modulation waveform. However, those skilled in the art will understand that according to the examples of the present disclosure, other suitable modulation waveforms can be used to perform amplitude modulation of the RF voltage signal.

[0081] Figure 7 An example of a circuit system 700 is shown. The circuit system 700 includes elements common to the circuit system 300 described above, which are labeled with corresponding reference numerals and may be used in the same manner as described above. Figure 3 It operates in essentially the same manner as described.

[0082] The circuit system 700 includes a circuit configured to output an RF frequency signal f RF RF generator 320. In some examples, the RF frequency signal f RF The frequency of may be in the range of 500 kHz to 10 MHz. The RF generator 320 may include a device for generating an RF frequency signal f RFThe oscillator can be implemented with or without a counter or divider. The frequency generator 320 can receive a PWM control signal PWM from a microcontroller unit (MCU) 330. C To control the frequency generator 320. For example, the change of the duty cycle of the PWM control signal PWM can change the RF frequency signal f RF In some examples, the PWM control signal PWM C The duty cycle of the frequency generator 320 may be from 0% to 100% and have a period of 1 to 10 ms. In other examples, the functionality of the frequency generator 320 may form part of the MCU 330, where the MCU 330 may directly output the RF frequency signal f RF .

[0083] The circuit system 700 further includes an RF modulator 310, which further includes a converter unit 312 and a switch module 314. The converter unit 312 is configured to receive an RF frequency signal f RF And the RF frequency signal f RF Converted into a bipolar RF voltage signal V RF+ 、V RF- Converter unit 312 includes a positive converter unit 710 and a negative converter unit 720. In some examples, positive converter unit 710 and negative converter unit 720 may each include a switch mode power supply, such as a boost converter. Thus, positive converter unit 710 and negative converter unit 720 may each additionally be provided with a battery voltage V BATT Therefore, the positive converter unit 710 can be configured to convert the RF frequency signal f RF Converted into a positive RF voltage signal V RF+ , and the negative converter unit 720 can be configured to convert the RF frequency signal f RF Converted into a negative RF voltage signal V RF- In an example according to the present disclosure, the term positive RF voltage signal V RF+ and negative RF voltage signal V RF- Instead of indicating the polarity of the signal, it is possible to indicate that each signal is an inverse phase signal of each other. For example, a positive RF voltage signal V RF+ and negative RF voltage signal V RF- Each may include a PWM RF voltage signal, both of which are RF frequency signals f RF The positive RF voltage signal V RF+ and negative RF voltage signal V RF-Each may include a peak-to-peak voltage between 10V and 100V. In one example, the positive converter unit 710 and the negative converter unit 720 may each include a switch mode power supply, wherein the output of each of the positive converter unit 710 and the negative converter unit 720 is driven by an RF frequency signal f RF modulated to generate a PWM positive RF voltage signal V RF+ and PWM negative RF voltage signal V RF- .

[0084] The circuit system 700 further includes a switch module 314, which includes a plurality of switch units 730, 740, 750. Each of the plurality of switch units 730, 740, 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.

[0085] The switch module 314 is configured to receive the positive RF voltage signal V RF+ and negative RF voltage signal V RF- , and output N periodic amplitude modulated RF signals S1, S2, S3 to N electrodes 180a-c. Figure 7 In the example shown, N=3.

[0086] Therefore, MCU 330 is configured to output the control signal En 1-6 To control the switches 732-754 of the switch units 730, 740, 750, thereby modulating the positive RF voltage signal V RF+ and negative RF voltage signal V RF- amplitude to generate N periodic amplitude modulated RF signals S1-S3.

[0087] As described above with respect to FIGS. 5a-5c and 6a-6c, at multiple phases Φ 1-3 In some examples, the N periodic amplitude modulated RF signals S1-S3 can 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 ​​can therefore include a positive RF voltage signal V RF+ , 0 voltage signal and negative RF voltage signal V RF- Therefore, the MCU 330 can be configured to control the operation of the switches 732-754 of the switch units 730, 740, 750 so that the N periodic amplitude modulated RF signals S1-S3 are output to the electrodes 180a-c at one of the following three values: the positive RF voltage signal V RF+ , 0 voltage signal and negative RF voltage signal V RF- .

[0088] For example, referring briefly to FIG. 5 b , in the first phase Φ1 , the first periodic amplitude modulated RF signal S1 includes a negative RF voltage signal V RF- The second periodic amplitude modulated RF signal S2 includes a positive RF voltage signal V RF+ , the third periodic amplitude modulated RF signal S3 includes a 0 voltage signal. Therefore, referring again to Figure 7 , MCU 330 can output control signal En 1-6 The switches 732 - 754 of the switch units 730 , 740 , 750 are controlled to output N periodic amplitude modulated RF signals S1 - S3 , whose values ​​are shown in the first phase Φ1 of FIG. 5 b .

[0089] For example, in order to use a negative RF voltage signal V RF- Outputting the first periodic amplitude modulated RF signal S1, the MCU 330 may therefore output a first control signal En1 to activate the first switch 732, thereby connecting the first electrode 180a to the output of the negative converter unit 720. The MCU 330 may therefore additionally output 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.

[0090] In order to use a positive RF voltage signal V RF+ The second periodic amplitude modulated RF signal S2 is output, and the MCU 330 can therefore output a fourth control signal En4 to activate the fourth switch 744, thereby connecting the second electrode 180b to the output of the positive converter unit 710. The MCU 330 can therefore additionally output a third control signal En3 to deactivate the third switch 742, so that the second electrode 180b is not connected to the output of the negative converter unit 720.

[0091] In order to output the third periodic amplitude modulated RF signal S3 with a 0 voltage signal, the MCU 330 may therefore output the fifth control signal En5 and the sixth control signal En6 to respectively deactivate the fifth switch 752 and the sixth switch 754. Therefore, the node between the third switch unit 750 and the third electrode 180c may be floating, so that during the first phase Φ1 of FIG. 5b, no voltage signal or a 0 voltage signal is applied to the third electrode 180c.

[0092] Therefore, according to an example of the present disclosure, by appropriately controlling the switches 732-754 of the switch units 730, 740, 750, the MCU 330 is configured to operate in multiple phases Φ 1-3 Thus, the electrodes 180a-c are configured to receive N periodic amplitude modulated RF signals S1-S3, wherein the RF energy can be varied at each phase of the N periodic amplitude modulated RF signals S1-S3. 1-3The CO flows between electrodes 180a-c through the user's skin to cause heating of the skin.

[0093] The circuit system 700 further includes a low dropout regulator (LDO) 760. The LDO 760 is configured to BATT When the battery voltage drops to a low level, V BATT .

[0094] The circuit system 700 also includes a plurality of sensing resistors 770a-c, including a first sensing resistor 770a, a second sensing resistor 770b, and a third sensing resistor 770c. The first sensing resistor 770a, the second sensing resistor 770b, and the third sensing resistor 770c can each be arranged adjacent to the first electrode 180a, the second electrode 180b, and the third electrode 180c. Therefore, the plurality of sensing resistors 770a-c are configured to measure the temperature of the surface of the corresponding electrode 180a-c and the temperature of the skin in contact with the electrode surface. Figure 7 In the example shown, each of the plurality of sensing resistors 770a-c comprises a negative temperature coefficient (NTC) resistor. In one example, each of the plurality of sensing resistors 770a-c can form part of a voltage divider. Thus, the plurality of sensing resistors 770a-c can be connected to the MCU 330, wherein the value of the voltage across each of the sensing resistors 770a-c can be used as a safety control element. In one example, in response to the temperature of any one of the plurality of sensing resistors 770a-c rising above a threshold, the MCU can be configured to change the PWM control signal PWM C To reduce the RF frequency signal f RF , thereby reducing the temperature applied to the user's skin.

[0095] Figs. 8a and 8b illustrate simulation results of RF heating of a skin surface in contact with electrodes 180a-c arranged in a cutting head of an electric shaver.

[0096] FIG8a illustrates the results obtained using an electric shaver according to an example of the present disclosure, wherein N periodic amplitude modulated RF energy signals are applied to electrodes 180a-c. The user's skin surface is heated to 41.7°C in 5 seconds. As shown, the RF energy flow occurs between each of the electrodes 180a-c. In addition, as shown, the skin depth penetration between each of the electrodes 180a-c is approximately 0.9mm. Since the skin heating penetration between each electrode is the same, this results in more uniform heating of the skin in contact with the electrodes 180a-c in the cutting head of the electric shaver.

[0097] FIG8b illustrates the results obtained using an electric shaver, wherein single-phase RF energy is applied to electrodes 180a-c. The first electrode 180a receives a zero voltage signal, and the second electrode 180b receives a positive RF voltage signal V RF+ , the third electrode 180c receives a negative RF voltage signal V RF- . The user's skin was heated to 45.3°C in 5 seconds. Although the temperature heating was higher than the heating caused by the electric shaver according to the example of the present disclosure shown in FIG. 8a, the RF energy flow of the shaver shown in FIG. 8b was less uniform. As shown, a large amount of 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. The skin heating penetration between the second electrode 180b and the third electrode 180c is also high, because 1.4mm of penetration occurs between these electrodes, while about 0.5mm of penetration occurs between the first electrode 180a and both the second electrode 180b and the third electrode 180c. Uneven RF energy flow and skin penetration can produce a "hot spot" feeling on the user's skin, which is unpleasant. The electric shaver according to the example of the present disclosure shown in FIG. 8a heats a 13% larger area of ​​skin and does not generate any hot spots.

[0098] An example according to the present disclosure has been described in which electrodes may be arranged in the skin contact area of ​​the electric shaver, the electrodes being adjacent to the hair cutting units of the electric shaver in a lateral portion of the skin contact area between the respective pairs of hair cutting units. However, other arrangements of the hair cutting units and electrodes are also possible, as described below.

[0099] Fig. 9 Another example of a skin contact area 910 of an electric shaver 900 is shown. The electric shaver 900 includes the same skin contact area 910 as described above. Figure 2 Elements common to the skin contacting area 200 of the electric shaver described are labeled with corresponding reference numerals and are labeled in substantially the same manner as described above.

[0100] Thus, the electric shaver 900 includes a first cutting unit 150, a second cutting unit 160, and a third cutting unit 170. The first cutting unit 150, the second cutting unit 160, and the third cutting unit 170 each include a corresponding covering element in the form of a first electrode 180a, a second electrode 180b, and a third electrode 180c. In such an example, the first electrode 180a, the second electrode 180b, and the third electrode 180c are respectively formed in the same manner as described above. Figure 1The first covering element 154, the second covering element 164 and the third covering element 174 are arranged on the first external cutting member 152, the second external cutting member 162 and the third external cutting member 172 in a substantially corresponding manner. Therefore, the first covering element, the second covering element and the third covering element can be formed by a conductive material for conducting RF voltage signals. As described above, the RF generator unit configured to output N periodic amplitude modulated RF signals can therefore be electrically connected to each electrode in the electrodes 180a-c. In use, the N periodic amplitude modulated RF signals can be applied to the electrodes 180a-c in a manner corresponding to the above. Therefore, in use, RF energy can flow between the electrodes 180a-c in the user's skin to warm the skin.

[0101] Thus, the first electrode 180a, the second electrode 180b, and the third electrode 180c can be electrically isolated from other elements of the skin contact area 910, so that the "circuit" of the RF voltage is only completed when the electrodes 180a-c are applied to the user's skin. For example, each of the electrodes 180a-c can be electrically isolated from its corresponding external cutting member 152, 162, 172 by separating the two elements with an insulating material (such as a non-conductive plastic).

[0102] Due to the arrangement of the electrodes 180a-c in the electric shaver 900, the geometric center point of each hair cutting unit 150, 160, 170 is therefore aligned with the geometric center point of each electrode in the electrodes 180a-c. Therefore, the first pitch 202 between the geometric center points 156, 166, 176 of each pair of hair cutting units in the hair cutting units 150, 160, 170 is the same as the second pitch 204 between each pair of electrodes in the electrodes 180a-c. In the example of the electric shaver 900, the ratio between the second minimum pitch 204 and the first minimum pitch 202 can be 1. Therefore, the electrodes 180a-c are again distributed over the main area of ​​the skin contact area 910, and therefore, in use, this arrangement can produce more uniform heating in a large area of ​​skin in contact with the skin contact area 910. For example, due to the arrangement of the N electrodes 180a-c, RF energy may flow between each of the N electrodes 180a-c, such that a majority of the skin in contact with the skin contact area 200 is warmed by the application of RF energy.

[0103] So far, the examples presented have described the teachings of the present disclosure with respect to rotary shavers. However, the teachings of the present disclosure may additionally be applied to other forms of electric shavers, such as foil shavers.

[0104] Fig.10There is shown an example of an electric shaver 1000. The electric shaver comprises elements in common with the electric shaver 100 described above, which elements are numbered with corresponding reference numerals, and may operate in substantially the same manner as described above.

[0105] The electric shaver 1000 is in the form of a foil shaver. Therefore, the cutting head 140 includes a first hair cutting unit 150, a second hair cutting unit 160 and a third hair cutting unit 170. Each hair cutting unit 150, 160, 170 includes a corresponding internal cutting member (such as a blade) and a corresponding external cutting member 152, 162, 172, which includes a plurality of hair entry openings. The hair entry openings may include holes and / or thin sheets. Each external cutting member 152, 162, 172 includes a corresponding skin contact area, which contacts the user's skin when the shaver 1000 is in use. The hair entry opening is part of the skin contact area. Fig.10 In an embodiment of the present invention, each external cutting member 152, 162, 172 is a shaving foil extending parallel to the longitudinal direction. The external cutting members 152, 162, 172 are arranged to cover the corresponding internal cutting members, and the corresponding internal cutting members are movable relative to the external cutting members, for example, the blades can perform linear reciprocating motions relative to the foils parallel to the longitudinal direction. Hairs can extend through the openings of the foils 152, 162, 172, and the reciprocating action of the blades cuts the hairs, wherein the cut ends can be gathered in the hair collection area of ​​the shaver 1000. Therefore, the electric shaver 1000 also includes a motor 130, which is configured to move the internal cutting members relative to the corresponding external cutting members 152, 162, 172 to achieve the cutting action.

[0106] The RF generator energy unit 120 is configured to apply N periodic amplitude modulated RF signals to the skin via the skin contact area provided by the external cutting member 152, 162, 172 of each hair cutting unit in the hair cutting unit 150, 160, 170. For example, each of the external cutting members 152, 162, 172 of each hair cutting unit in the hair cutting unit 150, 160, 170 can be formed by a conductive material that can conduct N periodic amplitude modulated RF signals but is also biocompatible with the skin, such as a metal such as stainless steel, silver or silver chloride. Therefore, the entire external cutting member 152, 162, 172 is configured to conduct N periodic amplitude modulated RF signals. In other words, the external cutting member 152, 162, 172 is used as N electrodes for applying N periodic amplitude modulated RF signals to the user's skin to warm the skin. Thus, each of the N electrodes may be formed by at least the skin contacting portion of the external cutting member 152, 162, 172 of the corresponding hair cutting unit in the N hair cutting units 150, 160, 170. Thus, each of the external cutting members 152, 162, 172 may be further electrically isolated from each other by the electric shaver 1100. For example, there may be a gap between each of the external cutting members 152, 162, 172 to electrically isolate the external cutting members 152, 162, 172 from each other. In this way, when the external cutting members 152, 162, 172 are in contact with the user's skin, a "circuit" may be formed between the external cutting members.

[0107] Fig.11 There is shown another example of an electric shaver 1100. The electric shaver 1100 includes elements in common with the electric shaver 1000 described above, which elements are labeled with corresponding reference numerals, and can operate in substantially the same manner as described above.

[0108] The electric shaver 1100 includes a skin contact area 1110, which includes a first hair cutting unit 150, a second hair cutting unit 160 and a third hair cutting unit 170. As described above, the external cutting members 152, 162, 172 are used as N electrodes for applying N periodic amplitude modulated RF signals to the skin of the user to warm the skin. In the arrangement of the electric shaver 1100, the geometric center points 156, 166, 176 of each hair cutting unit in the hair cutting units 150, 160, 170 are therefore aligned with the geometric center points of each electrode. Therefore, the first pitch 202 between the geometric center points 156, 166, 176 of each pair of hair cutting units in the hair cutting units 150, 160, 170 is the same as the second pitch 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 204 and the first minimum pitch 202 can therefore be 1. Thus, the electrodes 180a-c are again distributed over a major area of ​​the skin contact area 1110, and therefore, in use, this arrangement can produce more uniform heating in a large area of ​​skin in contact with the skin contact area 1100. For example, due to the arrangement of the outer cutting members 152, 162, 172 acting as N electrodes, RF energy can flow between each of the N electrodes such that a majority of the skin in contact with the skin contact area 1110 is warmed by the application of RF energy.

[0109] Fig. 12a and Fig. 12b illustrate an example of how an RF signal may be applied to an outer cutting member 152, 162, 172 of a hair cutting unit 150, 160, 170 of the foil shaver category.

[0110] FIG. 12 a illustrates N modulation signals M1-M3, where N=3. Thus, the N modulation waveforms M1-M3 include a RF voltage signal V applied to the first electrode for modulating the RF voltage signal V applied to the first electrode. RF The first modulation signal M1 is used to modulate the RF voltage signal V applied to the second electrode. RF The second modulation signal M2 and the RF voltage signal V for modulating the RF voltage applied to the third electrode RF As shown in FIG12b, the first electrode, the second electrode and the third electrode comprise a first external cutting member 152, a second external cutting member 162 and a third external cutting member 172 of the electric shaver.

[0111] Each of the N modulation signals M1-M3 includes a two-state modulation waveform including a first state +1 and a second state 0. As described above with respect to FIGS. 4a-4c, according to the nth modulation signal among the N modulation signals M1-M3 having T relative to the first modulation signal among the N modulation signals M1-M3, MOD*(n-1) / N phase difference condition, in the modulation period T MOD In the internal structure, the two-state N modulation signals M1-M3 are in three phases Φ 1-3 4a-c, the N modulation signals M1-M3 can be used to modulate the RF voltage signal V RF amplitude to generate N periodic amplitude modulated RF energy signals for application to the N electrodes.

[0112] FIG12b illustrates how the three phases Φ 1-3 N periodic amplitude modulated RF voltage signals (which may be referred to as N periodic amplitude modulated RF energy signals in some examples) are applied to the external cutting members 152, 162, 172 of the electric shaver. In a similar manner as described above with respect to FIGS. 4a-4c, the N periodic amplitude modulated RF energy signals may include a first value of the RF voltage signal +V or a second value of the zero voltage signal 0V, depending on the state of the corresponding N modulation signals M1-M3 during a given phase. For example, referring to FIG. 12a, during the first phase Φ1, the first modulation signal M1 is in the first state +1, and the second modulation signal M2 and the third modulation signal M3 are both in the second state 0. Therefore, referring to FIG. 12b, during the first phase Φ1, the first external cutting member 152 receives the first periodic amplitude modulated signal as the RF voltage signal +V, and the second external cutting member 162 and the second external cutting member 172 receive the second periodic amplitude modulated signal and the third periodic amplitude modulated signal as the zero voltage signal 0V, respectively. Thus, RF energy flow may occur between both the first outer cutting member 152 and the second outer cutting member 162 and the second outer cutting member 172 to warm the user's skin.

[0113] In a similar manner as described above with respect to FIGS. 4a-4c, during the second phase Φ2 and the third phase Φ3, the N periodic amplitude modulated RF energy signals vary according to the N modulation signals M1-M3, and thus the RF energy flow between the outer cutting members 152, 162, 172 varies accordingly. In some examples, the modulation signals M1-M3 may therefore represent the envelope of the N periodic amplitude modulated RF energy signals. Thus, over the first phase Φ1, the second phase Φ2, and the third phase Φ3, RF energy flow occurs between different outer cutting members of the outer cutting members 152, 162, 172, which results in more uniform heating of the skin in contact with the outer cutting members 152, 162, 172.

[0114] According to Figures 12a-12b, the heating of the skin by an electric shaver was simulated using the modulation signals M1-M3. These heating results were compared with the simulation of skin heating using an electric shaver including three shaver foil electrodes to which an unmodulated RF signal was applied. Compared to the electric shaver using the unmodulated RF signal, the electric shaver using the modulation signals M1-M3 according to Figures 12a-12b heated a 25% larger volume of skin. In the above example, for two shavers, the two foil electrodes located on the configuration side (e.g., the first outer cutting member 152 and the third outer cutting member 172) included a skin contact area of ​​4×25 mm, and the center foil electrode (e.g., the second outer cutting member 162) included a skin contact area of ​​5×25 mm, wherein each foil electrode was separated by an electrical isolation gap of 4 mm. An electric shaver using modulated signals M1-M3 uses a peak-to-peak voltage level of 11V, while an electric shaver using an unmodulated RF signal uses a voltage level of 19V.

[0115] Figs. 13a and 13b illustrate another example of how an RF signal may be applied to an outer cutting member 152, 162, 172 of a hair cutting unit 150, 160, 170 of a foil shaver.

[0116] FIG. 13a illustrates N modulation signals M1-M3, where N=3. In a similar manner as described above with respect to FIG. 12a-12b, the N modulation signals M1-M3 may be used to modulate the RF voltage signal V RF The amplitude of RF energy signals is used to generate N periodic amplitude modulated RF energy signals for application to N electrodes. As shown in FIG. 13b, the N electrodes include a first external cutting member 152, a second external cutting member 162 and a third external cutting member 172 of the electric shaver.

[0117] Referring again to FIG. 13a, each of the N modulation signals M1-M3 includes an asymmetric tri-state modulation waveform. In a manner similar to that described above with respect to FIGS. 5a-5c, the nth modulation signal in the N modulation signals M1-M3 has a T value relative to the first modulation signal in the N modulation signals M1-M3. MOD *(n-1) / N phase difference condition (where 2≤n≤N), in the modulation period T MOD In FIG. 13a, the N modulation signals M1-M3 are in three phases Φ 1-3 Thus, in a similar manner as described above with respect to FIGS. 5a-c, N modulation signals M1-M3 may be used to modulate the amplitude of the positive RF voltage signal +V and the negative RF voltage signal -V to generate N periodic amplitude modulated RF energy signals for application to the N electrodes.

[0118] Referring to FIG. 13b, N periodic amplitude modulated RF voltage signals (in some examples, may be referred to as N periodic amplitude modulated RF energy signals S1-S3) may thus be transmitted at three phases Φ 1-3 5a-5c, RF energy flows in different amounts between different ones of the external cutting members 152, 162, 172, which results in more uniform heating of the skin in contact with the three electrodes E1-E3.

[0119] Thus, examples according to the present disclosure have been given with respect to N electrodes and N periodic amplitude modulated RF energy signals, where N = 3. However, in other examples, N may be greater than 3, such as N = 4.

[0120] Fig.14 There is shown an example of an electric shaver 1400. The electric shaver 1400 includes elements in common with the electric shaver 1100 described above, which elements are labeled with corresponding reference numerals, and may operate in substantially the same manner as described above.

[0121] The electric shaver 1400 comprises a skin contact area 1410, which comprises a first hair cutting unit 150, a second hair cutting unit 160 and a third hair cutting unit 170, and an additional fourth hair cutting unit 1480. The fourth hair cutting unit 1480 also comprises a fourth external cutting member 1480 of the shaver foil type. Thus, the fourth hair cutting unit 1480 and the fourth external cutting member 1480 can be arranged in the same manner as described above with respect to Fig.11 The hair cutting units 150, 160, 170 and the external cutting members 152, 162, 172 described above operate in a substantially corresponding manner. Therefore, the fourth external cutting member 1480 can be formed of a conductive material capable of conducting the fourth periodic amplitude modulated RF signal among the N periodic amplitude modulated RF signals. Therefore, the entire fourth external cutting member 1482 is configured to conduct the fourth periodic amplitude modulated RF signal among the N periodic amplitude modulated RF signals. In other words, the fourth external cutting member 1480 serves as a fourth electrode for applying the fourth periodic amplitude modulated RF signal among the N periodic amplitude modulated RF signals to the user's skin to warm the skin.

[0122] As described above, the external cutting members 152, 162, 172, 1482 are used as N electrodes for applying N periodic amplitude modulated RF signals to the user's skin to warm the skin. Due to the arrangement of the electric shaver 1400, the geometric center points 156, 166, 176, 1486 of each hair cutting unit in the hair cutting units 150, 160, 170, 1480 are therefore aligned with the geometric center points of each electrode. Therefore, the first pitch 202 between the geometric center points 156, 166, 176 of each pair of hair cutting units in the hair cutting units 150, 160, 170 is the same as the second pitch 204 between the geometric center points of each pair of electrodes in the electrodes 180a-c. In the example of the electric shaver 1400, the ratio between the second minimum pitch 204 and the first minimum pitch 202 can be 1. Thus, the electrodes are again distributed over a major area of ​​the skin contact area 1110 and therefore, in use, this arrangement may produce more uniform heating across the large area of ​​skin in contact with the skin contact area 1100.

[0123] Fig.15a and Fig.15b An example of how an RF signal may be applied to an outer cutting member 152, 162, 172, 1482 of a hair cutting unit 150, 160, 170, 1480 of a foil shaver is illustrated.

[0124] Fig.15a N modulation signals M1-M4 are shown, where N=4. The N modulation waveforms M1-M4 include a RF voltage signal V applied to the first electrode for modulating RF The first modulation signal M1 is used to modulate the RF voltage signal V applied to the second electrode. RF The second modulation signal M2 is used to modulate the RF voltage signal V applied to the third electrode. RF The third modulation signal M3 and the RF voltage signal V for modulating the RF voltage applied to the fourth electrode RF The fourth modulation signal M4. Fig.15b As shown, the first electrode, the second electrode, the third electrode and the fourth electrode comprise a first external cutting member 152, a second external cutting member 162, a third external cutting member 172 and a fourth external cutting member 1482 of the electric shaver.

[0125] Each of the N modulation signals M1-M4 includes an asymmetric four-state modulation signal, which includes a first state +1, a second state +1 / 3, a third state -1 / 3 and a fourth state -1. Each of the N modulation signals M1, M2, M3, M4 has a modulation period T MOD , the modulation period can be divided into four phases Φ 1-4Therefore, in a manner similar to that described above with respect to FIGS. 4a-4c, 5a-5c, 6a-6c, 12a-12c, and 13a-13c, according to the n-th modulation signal among the N modulation signals M1-M4 having T relative to the first modulation signal among the N modulation signals M1-M4, MOD *(n-1) / N phase difference condition (where 2≤n≤N), in the modulation period T MOD In the N modulation signals M1-M4, there are four phases Φ 1-4 Shifted toward each other.

[0126] Fig.15b The diagram shows how the four phases Φ 1-4 N periodic amplitude modulated RF voltage signals (which may be referred to as N periodic amplitude modulated RF energy signals S1-S3 in some examples) are applied to the external cutting member 152, 162, 172, 1482 of the electric shaver. In a manner similar to that described above, the N periodic amplitude modulated RF energy signals may include a plurality of values, including a first value of the RF voltage signal +V, a second value of the RF voltage signal +V / 3, a third voltage signal of the RF voltage signal -V / 3, and a fourth value of the RF voltage signal -V, depending on the state of the corresponding N modulation signals M1-M4 during a given phase. In some examples, the modulation signals M1-M3 may therefore represent the envelope of the N periodic amplitude modulated RF energy signals S1-S3.

[0127] In some examples, in order to generate the second voltage value of +V / 3 and the third voltage value of -V / 3, the RF generator unit 312 may include a circuit for generating the RF voltage signal +V RF / 3 and -V RF In such an example, the switch unit 314 may therefore also include an additional switch for applying the second voltage value of +V / 3 and the third voltage value of −V / 3 to the N electrodes.

[0128] exist Figure 15a-Figure 1 In the example shown in FIG5c, the ratio between the magnitudes of the first voltage value +V and the fourth voltage value -V and the magnitudes of the second voltage value +V / 3 and the third voltage value -V / 3 is 0.33. However, in other examples, the ratio between these voltage magnitudes may be between 0.25 and 0.5, preferably between 0.3 and 0.35.

[0129] See also Fig.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. Therefore, referring to Fig.15bDuring the first phase Φ1, the first external cutting member 152 receives a first periodic amplitude modulation signal of a first value +V, the second external cutting member 162 receives a second periodic amplitude modulation signal of a second value +V / 3, the third external cutting member 172 receives a third periodic amplitude modulation signal of a third value -V / 3, and the fourth external cutting member 1482 receives a fourth periodic amplitude modulation signal of a fourth value -V. Therefore, in a manner similar to the above, since there is a voltage difference between the external cutting members 152, 162, 172, 1482 of the electric shaver during the first phase Φ1, RF energy flow may occur between the external cutting members 152, 162, 172, 1482 to warm the user's skin.

[0130] In a similar manner as described above, during the second phase Φ2, the third phase Φ3, and the fourth phase Φ4, based on the N modulation signals M1-M4, the N periodic amplitude modulated RF energy signals change, and thus the RF energy flow between the external cutting members 152, 162, 172, 1482 also changes accordingly. Therefore, over the first phase Φ1, the second phase Φ2, the third phase Φ3, and the fourth phase Φ4, RF energy flow occurs in different amounts between different external cutting members of the external cutting members 152, 162, 172, 1482, which results in more uniform heating of the skin in contact with the external cutting members 152, 162, 172, 1482.

[0131] according to Figure 15a-Figure 15b , the heating of the skin by an electric shaver was simulated using the modulated signals M1-M4. These heating results were compared to skin heating simulations using an electric shaver comprising four shaver foil electrodes, to which an unmodulated RF signal was applied. Compared to an electric shaver using an unmodulated RF signal, the heating results using the Figure 15a-Figure 15b The electric shaver using the modulated signals M1-M4 heats 60% more volume of skin. In the above example, for both shavers, each foil electrode 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 includes a skin contact area of ​​4×25 mm, wherein each foil electrode is separated by an electrical isolation gap of 4 mm. The electric shaver using the modulated signals M1-M3 uses a peak-to-peak voltage magnitude of 11 V, while the electric shaver using the unmodulated RF signal uses a voltage magnitude of 19 V.

[0132] Fig.16 Another example of an electric shaver 1600 is shown. The electric shaver 1600 includes the same Fig. 9 The same elements as those of the electric shaver 900 described above. Corresponding elements described above are marked with corresponding reference numerals and can be operated in a corresponding manner as described above.

[0133] Electric shaver 1600 includes skin contact area 1610, which includes first hair cutting unit 150, second hair cutting unit 160 and third hair cutting unit 170 in a similar manner to electric shaver 900 described above, and each hair cutting unit includes corresponding covering elements in the form of first electrode 180a, second electrode 180b and third electrode 180c. Electric shaver 1600 also includes fourth hair cutting unit 1680, which includes covering elements in the form of fourth electrode 180d. Therefore, the fourth covering element can be formed by a conductive material for conducting RF voltage signal in addition. As described above, the RF generator unit configured to generate N periodic amplitude modulated RF signals can therefore be electrically connected to each of electrodes 180a-d. In use, N periodic amplitude modulated RF signals can therefore be applied to electrodes 180a-d in a manner corresponding to the above. Therefore, in use, RF energy can flow between electrodes 180a-d in the user's skin to warm the skin.

[0134] Due to the arrangement of the electrodes 180a-d in the electric shaver 1600, the geometric center point of each hair cutting unit 150, 160, 170, 1680 is therefore aligned with the geometric center point of each electrode in the electrodes 180a-d. Therefore, the first pitch 202 between the geometric center points 156, 166, 176, 1686 of each pair of hair cutting units in the hair cutting units 150, 160, 170, 1680 is the same as the second pitch between the geometric center points of each pair of electrodes in the electrodes 180a-d. In the example of the electric shaver 1600, the ratio between the second minimum pitch 204 and the first minimum pitch 202 can be 1. Therefore, the electrodes 180a-d are again distributed over the main area of ​​the skin contact area 910, and therefore, in use, this arrangement can produce more uniform heating in a large area of ​​skin in contact with the skin contact area 1610. For example, due to the arrangement of the N electrodes 180a-c, RF energy may flow between each of the N electrodes 180a-d, such that a majority of the skin in contact with the skin contact area 200 is warmed by the application of RF energy.

[0135] Fig.17a and Fig.17b Another example of how to apply an RF signal to the electrodes of an electric shaver is illustrated.

[0136] Fig.17a N modulation signals M1-M4 are shown, where N=4. The N modulation waveforms M1-M4 include a RF voltage signal V applied to the first electrode for modulating RF The first modulation signal M1 is used to modulate the RF voltage signal V applied to the second electrode. RFThe second modulation signal M2 is used to modulate the RF voltage signal V applied to the third electrode. RF The third modulation signal M3 and the RF voltage signal V for modulating the RF voltage applied to the fourth electrode RF The fourth modulation signal M4. Fig.17b As shown, the first electrode 180a, the second electrode 180b, the third electrode 180b and the fourth electrode 180d comprise covering elements of the hair cutting units 150, 160, 170, 1680.

[0137] Each of the N modulation signals M1-M4 comprises a two-state modulation signal, wherein the two-state modulation signal comprises a first state +1 and a second state 0. Figure 15a-Figure 15b In a similar manner, each of the N modulation signals M1-M4 has a modulation period T MOD , the modulation period can be divided into four phases Φ 1-4 Therefore, in a similar manner as described above, according to the fact that the nth modulation signal among the N modulation signals M1-M4 has T relative to the first modulation signal among the N modulation signals M1-M4, MOD *(n-1) / N phase difference condition (where 2≤n≤N), in the modulation period T MOD In the N modulation signals M1-M4, there are four phases Φ 1-4 Shifted toward each other.

[0138] In a manner similar to that described above, N periodic amplitude modulated RF voltage signals may be generated by applying N modulation signals M1-M4 to the RF voltage signal, which signals may be referred to as N periodic amplitude modulated RF energy signals in some examples. In a manner similar to that described above, the N periodic amplitude modulated RF energy signals may include multiple values, including a first value of the RF voltage signal +V and a second value of the zero voltage signal 0V, depending on the state of the corresponding N modulation signals M1-M4 during a given phase.

[0139] For example, refer to Fig.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. Therefore, referring to Fig.17bDuring the first phase Φ1, the first electrode 180a receives a first periodic amplitude modulation signal of a second value of 0V, the second electrode 180b receives a second periodic amplitude modulation signal of a second value of 0V, the third electrode 180d receives a third periodic amplitude modulation signal of a first value of +V, and the fourth electrode 180d receives a fourth periodic amplitude modulation signal of a first value of +V. Therefore, in a manner similar to that described above, since there is a voltage difference between the electrodes 180a-d of the electric shaver during the first phase Φ1, RF energy may flow between the electrodes 180a-d to warm the user's skin.

[0140] In a similar manner as described above, during the second phase Φ2, the third phase Φ3, and the fourth phase Φ4, based on the N modulation signals M1-M4, the N periodic amplitude modulated RF energy signals change, and thus the RF energy flow between the electrodes 180a-d also changes accordingly. In some examples, the modulation signals M1-M3 can therefore represent the envelope of the N periodic amplitude modulated RF energy signals S1-S3. Therefore, during the first phase Φ1, the second phase Φ2, the third phase Φ3, and the fourth phase Φ4, the RF energy flow occurs between different electrodes in the electrodes 180a-d, which causes the skin in contact with the electrodes 180a-d to be heated more evenly.

[0141] By studying the drawings, the present disclosure and the appended claims, those skilled in the art can understand and implement variations to the disclosed embodiments when practicing the principles and techniques described herein. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. A single processor or other unit may implement the functions of several items described in the claims. The fact that certain measures are cited in mutually different dependent claims does not mean that a combination of these measures cannot be used to advantage. The computer program may be stored or distributed on a suitable medium, such as an optical storage medium or solid-state medium provided with or as part of other hardware, but may also be distributed in other forms, such as via the Internet or other wired or wireless telecommunications systems. Any reference signs in the claims should not be interpreted as limiting the scope.

Claims

1. An electric shaver (100, 900, 1000, 1100, 1400, 1600), comprising: a skin contact area (200, 910, 1110, 1410, 1610) arranged to contact the skin of a user during use of the shaver (100, 900, 1000, 1100, 1400, 1600); at least two hair cutting units (150, 160, 170, 1480, 1680) arranged in the skin contact area (200, 910, 1110, 1410, 1610) and each having an outer cutting member (152, 162, 172, 1482, 1682) with a plurality of hair entry openings and an inner cutting member covered by the outer cutting member (152, 162, 172, 1482, 1682) and movable relative to the outer cutting member; N electrodes (180a-d) arranged in the skin contact area (200, 910, 1110, 1410, 1610) to contact the skin during use, wherein N is at least 3; The radio frequency (RF) generator (320) is configured to generate a radio frequency having a fundamental frequency f RF and the basic period T RF =1 / f RF RF energy; an RF energy modulator (310) configured to transform the RF energy generated by the RF generator into N periodic amplitude modulated RF energy signals (S1, S2, S3) and provide each of the N periodic amplitude modulated RF energy signals (S1, S2, S3) to a corresponding electrode of the N electrodes (180a-d); in: The outer cutting member (152, 162, 172, 1482, 1682) of each hair cutting unit (150, 160, 170, 1480, 1680) has a geometric center point (156, 166, 176, 1486, 1686), a first pitch (202) and a first minimum pitch, the first minimum pitch (202) and the second minimum pitch (202) being perpendicular to the skin contact area (200, 910, 1110, 1410, 1610). a pitch being a distance between the geometric center points (156, 166, 176, 1486, 1686) of a hair cutting unit pair among the hair cutting units (150, 160, 170, 1480, 1680), the first minimum pitch being a minimum value among the first pitches (202) of all hair cutting unit pairs among the hair cutting units (150, 160, 170, 1480, 1680); Viewed perpendicularly to the skin contact area (200, 910, 1110, 1410, 1610), each of the N electrodes (180a-d) has a geometric center point (182a-c), a second pitch (204) and a second minimum pitch, wherein the second pitch is the distance between the geometric center points (182a-c) of an electrode pair among the N electrodes (180a-d), and the second minimum pitch is the minimum value of the second pitches (204) of all electrode pairs among the N electrodes (180a-d); A ratio between the second minimum pitch and the first minimum pitch is at least 0.8; The basic period T of the N periodic amplitude modulated RF energy signals (S1, S2, S3) is MOD Greater than the fundamental period T RF ;and The nth periodic amplitude modulated RF energy signal among the N periodic amplitude modulated RF energy signals (S1, S2, S3) has a T relative to the first periodic amplitude modulated RF energy signal among the N periodic amplitude modulated RF energy signals. MOD *(n-1) / N phase difference, where 2≤n≤N.

2. The electric shaver according to claim 1, wherein T MOD With T RF The ratio between them is at least 10, preferably at least 25.

3. An electric shaver according to claim 1 or 2, wherein each of the N periodic amplitude modulated RF energy signals (S1, S2, S3) has a period of about 100 s during the basic period T of the corresponding periodic amplitude modulated RF energy signal. MOD The same basic RF energy signal is present during this period.

4. An electric shaver according to claim 3, wherein the basic RF energy signal comprises a first state and a second state, the first state being a state having the basic frequency f RF and the first RF voltage (V RF+ , V RF- ) is composed of a first RF energy signal, and the second state is composed of a zero signal (0V).

5. The electric shaver according to claim 4, wherein the primary RF energy signal further comprises: A third state is comprised of a second RF energy signal that is opposite to the first RF energy signal.

6. An electric shaver according to claim 3, wherein the first states of the N periodic amplitude modulated RF energy signals (S1, S2, S3) do not occur simultaneously.

7. An electric shaver according to claim 4, wherein the second states of the N periodic amplitude modulated RF energy signals (S1, S2, S3) do not occur simultaneously.

8. An electric shaver according to any one of claims 1 to 7, wherein the N electrodes (180a-d) are arranged adjacent to the hair cutting unit (150, 160, 170).

9. An electric shaver according to claim 8, comprising three electrodes (180a-d) and three hair cutting units (150, 160, 170) arranged in a triangular configuration with respect to each other, wherein the inner cutting member of each hair cutting unit (150, 160, 170) is rotatable relative to the outer cutting member (152, 162, 172), and wherein each of the three electrodes (180a-d) is arranged in a lateral part of the skin contact area (200) between two hair cutting units (150, 160, 170) of a corresponding hair cutting unit pair of three hair cutting units (150, 160, 170).

10. An electric shaver according to any one of claims 1 to 7, comprising N hair cutting units (150, 160, 170, 1680), wherein the external cutting member (152, 162, 172, 1682) of each hair cutting unit of the N hair cutting units (150, 160, 170, 1680) is annular, and wherein the N electrodes (180a-d) comprise N covering elements, each covering element being arranged in a central position relative to the external cutting member (152, 162, 172, 1682) of a corresponding hair cutting unit of the N hair cutting units (150, 160, 170, 1680).

11. An electric shaver according to any one of claims 1 to 7, comprising N hair cutting units (150, 160, 170, 1480), wherein each of the N electrodes (180a-d) is constituted by at least the skin contacting portion of the external cutting member (152, 162, 172, 1482) of a corresponding hair cutting unit among the N hair cutting units (150, 160, 170, 1480).

12. An electric shaver according to claim 11, comprising three hair cutting units (150, 160, 170), wherein the internal cutting member of each hair cutting unit (150, 160, 170) is configured to perform linear reciprocating motion relative to the external cutting member (152, 162, 172) parallel to the longitudinal direction, and wherein the external cutting member (152, 162, 172) of each hair cutting unit (150, 160, 170) has a longitudinal extension parallel to the longitudinal direction.

13. The electric shaver according to claim 3, comprising four electrodes (180a-d) and four hair cutting units (150, 160, 170, 1480), wherein: The inner cutting member of each hair cutting unit (150, 160, 170, 1480) is configured to perform linear reciprocating motion relative to the outer cutting member (152, 162, 172, 1482) parallel to the longitudinal direction, and wherein the outer cutting member (152, 162, 172, 1482) of each hair cutting unit (150, 160, 170, 1480) has a longitudinal extension parallel to the longitudinal direction; Each of the four electrodes (180a-d) is constituted by at least a skin contacting portion of the external cutting member (152, 162, 172, 1482) of a corresponding hair cutting unit of the four hair cutting units (150, 160, 170, 1480); The basic RF energy signal includes a first state, a second state, a third state and a fourth state in sequence, wherein the first state is composed of a signal having the basic frequency f RF and a first RF energy signal of a first RF voltage, the second state is composed of a first RF energy signal having the fundamental frequency f RF and a second RF energy signal of a second RF voltage lower than the first RF voltage, the third state is composed of a third RF energy signal opposite to the second RF energy signal, and the fourth state is composed of a fourth RF energy signal opposite to the first RF energy signal.

14. An electric shaver according to claim 13, wherein a 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.

15. An electric shaver according to any one of claims 1 to 14, wherein the RF energy modulator (310) comprises N switch units (730, 740, 750), each switch unit being configured to apply a corresponding periodic amplitude modulated RF energy signal among the N periodic amplitude modulated RF energy signals (S1, S2, S3) to a corresponding electrode among the N electrodes (180a-d).

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