Air ionizer
Air ionization is an effective method of eliminating static charges on non-conductive materials and isolated conductors. Air ionizing apparatus that produces both positive and negative air ions can be used to reduce electrostatic charges on various objects such as semiconductor wafers and die during fabrication processes. Air ionizers generate large quantities of positive and negative ions in the surrounding atmosphere which serve as mobile carriers of charge in the air. As ions flow through the air, they are attracted to oppositely charged particles and surfaces. Neutralization of electrostatically charged surfaces can be rapidly achieved through the process. Increasing the ion content of the air within a room can be desirable for a variety of reasons. For example, a high negative ion content freshens the air and has beneficial physiological effects on persons who breathe the air. Air ions of either polarity act to remove dust, pollens, smoke and the like by imparting an electrical charge to such particulates. The charged particles are electrostatically attracted to walls or other nearby surfaces and tend to cling to such surfaces. Air ionizing devices which neutralize electrical charges in charged bodies by means of ions have conventionally been used as devices for eliminating static electricity in production environments such as clean rooms or the like in which semiconductors, or liquid crystal displays (LCDs) are manufactured. Air ionizers are not only used in industry to prevent electrostatic charge build-up and to neutralize existing charges. Ionizers are also used for therapeutic purposes to produce mostly negative ions which have a beneficial effect on respiratory diseases and allergies, perform a tranquilizing function, lower bacteria, and improve reaction time. There are several different types of electrically operated air ionizers, although, the fundamental technology employed for generating ions, known as corona discharge is generally the same in all such electrical air ionizers. Corona discharge type ionizers are commonly used as such air ionizing devices. In the case of such corona discharge type ionizers, a high positive or negative voltage is respectively applied to a positive or negative electrode, so that a corona discharge is generated, and the air surrounding the tip end of the abovementioned electrode is positively and negatively ionized; then, these ions are conveyed by air currents so that the charges on charged bodies are neutralized by ions of the opposite polarity. Air ionizers are generally well known in the art and are employed for a variety of uses, one of which is reducing electrostatic discharge in connection with the manufacture of semiconductors and other products. Air ionizers generate large quantities of both positive and negative ions which are dispensed into the surrounding atmosphere to increase the conductivity of the air within a facility. As ions from the air ionizer flow through the air they are attracted to oppositely charged particles and surfaces causing neutralization of such particles and surfaces. The result is that the positive and negative ions in the ionized air create a static dissipative environment by making the air a carrier of beneficial charges which both dissipate unwanted charges once they occur and significantly limit the magnitude of possible charge generation. Negative corona occurs when free electrons flow from the electrode into the surrounding air. Positive corona results from the flow of electrons from the air molecules into the electrode. The resulting ion current strength is a function of the applied voltage, the sharpness and conductivity of the electrode, the humidity of the air, atmospheric pressure and other factors. A typical electrical ionizer comprises a housing having an air inlet, a high voltage source, an electrode with a sharp point connected to the high voltage source for creating the corona discharge which generates the ions, an air outlet and a fan, blower or other air mover for causing air to flow in through the air inlet, past the electrode for picking up the ions and out through the air outlet to the surrounding environment.
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