| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a power supply device and the like for precisely detecting a foreign body metal different from a power supply object and preventing abnormal overheat when power is supplied by using a magnetic field. <P>SOLUTION: A charging tray 1 includes a primary side coil 10 on a circuit board. A positive electrode 14A and a negative electrode 14B are discretely arranged on an upper surface side. Electric short circuit (or capacitive coupling) occurs between the electrodes and a parameter such as an impedance changes when the foreign body (foreign body metal) is placed over the electrodes by applying voltage between the electrodes. A change amount of such parameter is compared with a threshold for foreign body detection, which is previously set. Thus, presence or absence of the foreign body is detected. The change amount of the parameter due to the foreign body is sufficiently larger than that when a portable telephone set 2 is placed. Thus, the foreign body and the portable telephone set 2 are easily selected by the threshold. When the foreign body is detected, heating of the foreign body is prevented by immediately taking measures such as the charging stop. <P>COPYRIGHT: (C)2012,JPO&INPIT |
