| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a power tool having a battery pack that can clearly show an electric double-layer capacitor's charge completion time, which differs according to the residual quantity of the battery, by obtaining a reference voltage for determining the completion of charging from the battery in a circuit where a signal is being output when the charging of an electric double-layer capacitor is completed. <P>SOLUTION: A power tool provided with a battery pack comprises: electric double-layer capacitors 103 to 108; a battery 101 for charging the electric double-layer capacitors 103 to 108; resistors 109, 110 for detecting voltage of the electric double-layer capacitors 103 to 108; resistors 111, 112 for detecting voltage of the battery 101, and an operational amplifier 113 for comparing these outputs. The operation amplifier 113 uses a divided voltage value of the resistors 111, 112 as a reference voltage. When the divided voltage value of the resistors 109, 110 becomes more than the reference voltage, the operation amplifier 113 outputs a signal showing that the charging of the electric double-layer capacitors 103 to 108 is completed. <P>COPYRIGHT: (C)2012,JPO&INPIT |
