| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an electronic apparatus for precisely detecting a foreign body and preventing abnormal overheat of the foreign body when power is supplied by using a magnetic field. <P>SOLUTION: A portable telephone set 2 includes a secondary side coil 20 on a circuit board. A positive electrode and a negative electrode are discretely arranged on an upper surface side. When the foreign body (foreign body metal) exists over the electrodes (when the foreign body is sandwiched between a charge tray 1 and the portable telephone set 2), electric short circuit (or capacitive coupling) occurs between the electrodes and a parameter such as an impedance changes by applying voltage between the electrodes. Presence or absence of the foreign body is detected by comparing a change amount of such parameter and a threshold for abnormal body detection. Since the change amount of the parameter is sufficiently larger than that when the foreign body is not sandwiched between the charge tray 1 and the portable telephone set 2, the foreign body is easily detected by the threshold. When the foreign body is detected, measures such as warning are immediately taken. Thus, heating of the foreign body can be prevented. <P>COPYRIGHT: (C)2012,JPO&INPIT |
