Electrostatic induced voltage of metal box having different and opposite area when charged body moves away from box

A sensitive device, for example, a giant magnetoresistive head contained in an electronic equipment, often malfunctions because of the induced voltage of less than 10 V when a charged human body is present near the equipment. Such accidents due to electrostatic induction occur when the charged body moves. The author focuses on the induced voltage of opposite polarity generated on the metal box when the charged body moves away from the box. In experiments, metal boxes of different heights are used to change the facing area between the charged body and the box. In addition, the position of the metal box is changed so that the induced voltages of the box can be compared. The results show that the induced voltages and the electric charges increase as the facing area between the metal box and the charged body increases. The induced voltage of the metal box indicates the value of approximately -370% of the charged body when the facing area between the metal box and the charged body increases. Further, the induced voltages and the charges are slightly dependent of the position of the metal box. The results will be useful for the design of electronic equipment from the standpoint of preventing malfunction and failure of the equipment. © 2016 The Institute of Electrical Engineers of Japan.