Electrostatic shielding application
In order to avoid the influence of the external electric field on the equipment, or to avoid the influence of the electric field of the electrical equipment on the outside world, a cavity conductor is used to cover the external electric field, so that the interior is not affected, and the electrical equipment does not affect the outside world. This is called electrostatic shielding.ESD shielding bag.
In order to prevent the external field (including electric field, magnetic field, electromagnetic field) from entering a certain area to be protected, it is called shielding. The shielding is divided into electrostatic shielding, hydromagnetic shielding, and electromagnetic shielding are three different branches of electromagnetics. These three shieldings The fundamental purpose is to use the inductive effect generated by the external field on the shield shell to resist the influence of the external field according to different physical principles, thus establishing a barrier for the "protected area" and suppressing external interference.ESD shielding bag
The shield of the cavity conductor that is not grounded is an outer shield, and the shield of the cavity conductor ground is fully shielded. The cavity conductor is in electrostatic equilibrium in the external electric field, and its internal field strength is always equal to zero. Therefore, it is impossible for an external electric field to have any influence on its internal space. If there is a charged body in the cavity conductor, its internal surface will produce an equal amount of induced charge when it is electrostatically balanced. If the outer casing is not grounded, the outer surface will generate the same amount of induced charge as the inner charged body. At this time, the electric field of the induced electric charge will have an influence on the outside world. At this time, the cavity conductor can only shield the external electric field, but cannot shield the internal electrified body. The impact on the outside world, so called external shielding. If the outer casing is grounded, even if there is a charged body inside, the algebraic sum of the charge induced by the inner surface and the charge of the charged body is zero, and the induced charge generated by the outer surface flows into the ground through the grounding wire. The outside world cannot affect the inside of the shell, and the influence of the internal charged body on the outside is also eliminated, so this shielding is called full shielding. In order to prevent interference from external signals, electrostatic shielding is widely used in scientific and technical work.ESD shielding bag
In the state of electrostatic equilibrium, whether it is a hollow conductor or a solid conductor; no matter how much the conductor itself is charged, or whether the conductor is in an external electric field, it must be an equipotential body whose internal field strength is zero, which is the theoretical basis of electrostatic shielding. For example, the metal cover on the outside of the electronic equipment, the lead skin on the outside of the communication cable, etc. are all shielding measures for preventing external electric field interference.