| 摘要 |
PROBLEM TO BE SOLVED: To provide a switch for a power tool and a power tool using the same, which switch has a function for warning a decrease in residual capacity of a battery, the function being easily understandable for an operator, and can prevent an over-discharge of the battery. SOLUTION: The switch 31 for the power tool comprises a trigger 3 interlocked with a sliding contact point 5, a PWM control section 6 for outputting a PWM signal Vp according to a voltage V1 of the sliding contact point and a reference voltage V2, a battery residual capacity judging section 7 which judges the residual capacity of a rechargeable battery 2 by detecting the voltage Vb of the battery and outputs a port output Vm, and a switching element 13 for driving a motor 1 by a switching control signal Vo according to the PWM signal Vp and the port output Vm. The switch 31 is configured such that the motor 1 is driven by the PWM signal Vp under usual conditions, and when the residual capacity of the rechargeable battery 2 has become smaller than a first required value, the maximum rotational speed at the maximum pulled value of the trigger 3 is fixed so as to be operable and to be lower than the maximum speed, and further when the residual capacity of the rechargeable battery 2 has become smaller than a second required value, the motor 1 is cut off from the rechargeable battery 2. COPYRIGHT: (C)2005,JPO&NCIPI
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