Test LED applications, it should be found that the use of high-frequency current drive often charred black, and ultimately lead to the lamp becomes dead lights. Specific performance in the colloidal gold due to sustained high temperature silicon carbide burning black, this is because of the high frequency impedance is much higher than the DC resistance, impedance increased the heat more serious colloid burning black gold, the reason for this phenomenon is the skin .
What is the skin
The skin effect is called the skin effect, and when the alternating current through the conductor, the current will be concentrated in the surface of the conductor flows, this phenomenon is called the skin. Electromagnetism of the skin effect, eddy current (eddy current) scientific terms. This phenomenon is by a dynamic of ferromagnetic material, the ferromagnetic material in the unpowered, not energized in the opposite direction of the surface of the ferromagnetic material of the magnetic field, the magnetic field will produce a cutting magnetic sense line current, this current is called the eddy This phenomenon is the impact of the skin.
Second, skin principle role
The skin effect, high frequency current or voltage conductor electron conductivity, will focus on the surface of the normal conductor, rather than the average distribution of the conductor cross-sectional area. The skin effect of the conductor resistance increases effective. The higher the frequency, the more remarkable the effect. When a high-frequency current through the current conductor can be considered that only a thin layer on the surface of the conductor, which is equivalent to the conductor cross-section decreases, the resistance increases. The central portion of the present line, almost no current flows through the center portion is removed in order to save material. Therefore, in the high-frequency circuit can be used the hollow conductor in place of the solid conductor. In addition,
Also tend to use a plurality of mutually insulated fine wires woven into a bundle, and replacement of the same cross-sectional area of the thick filament strand bundles in order to weaken the skin effect in the high frequency circuit, which is called the Debate line.
Third, set the application on the skin effect
Conductor conductor and the depth of the alternating electromagnetic field strength decrease exponentially, so in the sunscreen in the mixed conductor particles (typically zinc oxide and titanium dioxide), can make the intensity of the sun's ultraviolet (high frequency electromagnetic wave) reduction. This is a principle of physical sunscreens. Additionally, the skin effect and the electromagnetic shielding method, the use of the skin effect can prevent high-frequency electromagnetic waves penetrate the conductor, electromagnetic shielding device, which is also the elevator, the reasons for poor mobile phone signal reception. In industrial applications, the influence of the metal surface of the skin is hardened.