Electric Shaver RF Electrode Integration for Uniform Skin Warming
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Solution Overview
Problem
Existing electric shavers using RF energy for skin heating face challenges such as high energy RF fields causing hotspots and fractional skin warming due to small electrode sizes and distances, leading to unpleasant sensations.
Innovation Solution
The electric shaver employs bi-polar RF generator units that apply RF voltage to large external cutting members and covering elements, using them as electrodes to generate an electric field across a larger skin area, ensuring deeper penetration and uniform warming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If small electrodes are used in the shaving cap, then the device complexity is reduced, but the heating is focussed to small volumes of skin resulting in only fractional warming
Solution Approach 1:
The patent merges the cutting members with the electrode function by making the entire external cutting member conductive. This combines the hair cutting function and the RF heating function into a single integrated component, eliminating the need for separate small electrodes in the shaving cap while achieving broad skin contact for effective warming.
Solution Approach 2:
The external cutting member serves multiple functions: it acts as both the hair-cutting element and the RF electrode. This multi-functionality allows the device to achieve both effective hair cutting and broad skin warming without increasing device complexity or requiring additional specialized components.
2Use of energy by moving object
If pointed blades or small conductors are used as electrodes, then the RF electric field density increases, but hotspots are generated causing unpleasant or painful heat sensation
Solution Approach 1:
The patent applies local quality by ensuring uniform RF voltage distribution across the entire external cutting member surface. The conductive coating is applied uniformly to create consistent electrical properties across the localized contact areas, preventing current concentration at specific points while maintaining effective RF energy delivery to the skin.
Solution Approach 2:
The patent changes the electrical parameters of the cutting member by making it conductive through coating or material selection. This parameter change allows the cutting member to function as an electrode with controlled electrical properties, distributing RF energy uniformly across its surface area rather than concentrating it at sharp edges or small contact points.
3Area of stationary object
If the entire external cutting member conducts RF voltage, then the skin-contacting area increases for better warming, but the device complexity increases
Solution Approach 1:
The patent merges the cutting members with the electrode function by making the entire external cutting member conductive. This combines the hair cutting function and the RF heating function into a single integrated component, eliminating the need for separate small electrodes in the shaving cap while achieving broad skin contact for effective warming.
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
This configuration provides a pleasant warming sensation by uniformly heating the skin to 38°C to 40°C, enhancing user experience and improving skin hydration and microcirculation.
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
Electric shavers are known which include a heated mechanical element, which can provide warmth to the skin during shaving via the thermal transfer of heat.
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
According to an aspect, there is provided an electric shaver (100, 300a-b, 400, 500a-c) that comprises a first hair-cutting unit (150) that comprises: a first internal cutting member (252); and a first external cutting member (152, 152a, 152b, 152c) arranged to cover the first internal cutting member (252) and wherein the first internal cutting member (252) is movable relative to the first external cutting member (152, 152a, 152b, 152c); wherein the first external cutting member (152, 152a, 152b, 152c) comprises a first skin-contacting area comprising a first plurality of hair-entry openings (266), wherein the first skin-contacting area is arranged, in use, to contact skin. The electric shaver (100, 300a-b, 400, 500a-c) further comprises a second skin-contacting area arranged, in use, to contact the skin and a bi-polar radio frequency (RF) generator unit (120) configured to apply a first polarity RF voltage to the first external cutting member (152, 152a, 152b, 152c), and wherein the entirety of the first external cutting member (152, 152a, 152b, 152c) is configured to conduct the first polarity RF voltage; and wherein the bi-polar RF generator unit (120) is further configured to apply a second polarity RF voltage to the second skin-contacting area.