| 摘要 |
PROBLEM TO BE SOLVED: To provide a switch device for a power tool, preventing the occurrence of an arc when a contact is off, and surely preventing over discharge of a battery power supply. SOLUTION: This switch device for a power tool includes: a power supply switch SW1, which is put in the connecting state between a DC motor M and a battery power supply E and conducts when a lead-in amount of a trigger switch exceeds a predetermined threshold; a switching element SW2 to which the DC motor M and the battery power supply E are connected between both ends through the power supply switch SW1; a CPU 7, which outputs an on-duty control signal according to the lead-in amount of the trigger switch; a drive circuit for driving the switching element SW2 according to a control signal of the CPU 7; and a circuit-changing switch 10 operated interlocking with the trigger switch to change from the state of connecting the gate of the switching element SW2 to an output end of a driver circuit 8 to the state of connecting to the ground of the circuit in the timing before the power supply switch SW1 changes from on state to the off state in returning the trigger switch. COPYRIGHT: (C)2008,JPO&INPIT
|
