Electric Shaver RF Electrode Layout for Uniform Skin Warming
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Solution Overview
Problem
Existing electric shavers using bipolar RF energy for skin heating face challenges in achieving homogeneous skin warming with minimal hotspots, as large and multiple electrodes are costly and bulky, and phase shifting solutions are sensitive to accuracy.
Innovation Solution
An electric shaver design with at least three electrodes and hair-cutting units, where RF energy is modulated into phase-shifted amplitude signals, distributing energy evenly across the skin-contacting area without bulky phase steering devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If large and multiple electrodes are used to minimize hotspots and achieve homogeneous skin heating, then heating uniformity is improved, but device complexity and cost increase
Solution Approach 1:
The skin-contacting area is divided into multiple zones with electrodes arranged in a specific geometric pattern (e.g., triangular arrangement with at least three electrodes). Each electrode segment contributes to a distributed heating pattern that collectively achieves homogeneous skin heating without requiring a single large electrode
Solution Approach 2:
The RF energy is delivered in periodic pulses with controlled duty cycles. By modulating the RF energy delivery in periodic intervals and adjusting the pulse width, the system achieves homogeneous heating through temporal distribution of energy, avoiding the need for continuously active large electrodes
2Stability of the object's composition
If phase shifting or steering devices are used to distribute RF field and achieve homogeneous heating, then heating uniformity is improved, but device complexity and size increase
Solution Approach 1:
The system controls heating homogeneity by adjusting RF energy delivery parameters such as voltage amplitude, pulse width, and duty cycle rather than using complex phase steering devices. By changing these parameters dynamically, homogeneous heating is achieved with simpler circuitry
Solution Approach 2:
The RF energy delivery is made dynamic through pulse-width modulation and adjustable duty cycles. The system adapts the energy delivery in real-time based on detected skin impedance and temperature feedback, achieving homogeneous heating without static complex phase steering mechanisms
3Temperature
If bipolar RF energy is used for skin heating in electric shaver, then skin warming is achieved, but hotspot formation occurs reducing heating homogeneity
Solution Approach 1:
Different regions of the skin-contacting area are heated with locally optimized RF energy delivery. Each electrode zone is controlled independently with adjusted voltage and pulse parameters to ensure uniform temperature distribution across the entire contact area, preventing localized hotspots
Solution Approach 2:
The system incorporates temperature sensors and impedance detection to monitor skin conditions in real-time. Based on this feedback, the RF energy delivery parameters are dynamically adjusted to maintain homogeneous heating and prevent hotspot formation, ensuring stable temperature control
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Achieves more uniform skin warming with reduced hotspots, enhancing user comfort by ensuring consistent heating across a larger skin surface area.
Implementation Method 1
The use of the RF energy is different from the heated mechanical elements, which use thermal transfer to provide heating. In RF heating applications, two electrodes are applied to the skin, which each apply oppositely charged RF energy to the skin. This generates an electric field in the skin, between the two electrodes.
Implementation Method 2
an RF energy modulator configured to transform the RF energy generated by the RF generator into N periodic amplitude-modulated RF energy signals
Data Source
AI summary
According to an aspect. there is provided an electric shaver (100, 900, 1000, 1100, 1400, 1600) that comprises: a skin-contacting area (200, 910, 1110, 1410, 1610) arranged to contact 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-contacting area (200, 910, 1110, 1410, 1610) and each having an external cutting member (152, 162, 172, 1482, 1682) with a plurality of hair-entry openings and an internal cutting member covered by and moveable relative to the external cutting member (152, 162, 172, 1482, 1682); N electrodes (180a-d) arranged in the skin-contacting area (200, 910, 1110, 1410, 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 basic frequency fRF and a basic period TRF=1/fRF; 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 (SI, S2, S3) to a respective one of the N electrodes (180a-d); wherein: seen perpendicularly to the skin-contacting area (200, 910, 1110, 1410, 1610), the external 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 distance (202) being a distance between the geometric center points (156, 166, 176, 1486, 1686) of a pair of the hair-cutting units (150, 160, 170, 1480, 1680), and a first minimum pitch distance being a minimum of the first pitch distances of all pairs of the hair-cutting units (150, 160, 170, 1480, 1680); seen perpendicular to the skin-contacting area (200, 910, 1110, 1410, 1610), each of the N electrodes (180a-d) has a geometric center point (182a-c), a second pitch distance (204) being a distance between the geometric center points (182a-c) of a pair of the N electrodes (180a-d), and a second minimum pitch distance being a minimum of the second pitch distances (204) of all pairs of the N electrodes (180a-d); a ratio between the second minimum pitch distance and the first minimum pitch distance is at least 0.8; a basic period TMOD of the N periodic amplitude-modulated RF energy signals (S1, S2, S3) is larger than the basic period TRF; and an nth of the N periodic amplitude-modulated RF energy signals (S1, S2, S3) has a phase difference of TMOD*(U−1)/N relative to a first of the N periodic amplitude-modulated RF energy signals (S1, S2, S3), wherein 2≤n≤N.