ELECTRIC POWER TOOL
First Claim
1. An electric power tool comprising:
- a rechargeable battery;
a motor;
a detector configured to detect a parameter that affects a voltage drop of the rechargeable battery and output a detection signal corresponding to the detected parameter;
a controller configured to receive the detection signal and generate a control signal in accordance with the detection signal; and
a power switching unit operated in accordance with the control signal from the controller to switch between a situation in which the rechargeable battery supplies electric power to the motor and a situation in which the rechargeable battery stops supplying electric power to the motor,wherein the controller is configured to;
control the power switching unit using a pulse width modulation (PWM) control signal when the electric power tool is activated, andchange a duty ratio of the PWM control signal in accordance with the detection signal of the detector.
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Accused Products
Abstract
An electric power tool includes a rechargeable battery, a motor, a detector that detects a parameter that affects a voltage drop of the rechargeable battery and outputs a detection signal corresponding to the detected parameter, a controller that receives the detection signal and generates a control signal in accordance with the detection signal, and a power switching unit operated in accordance with the control signal from the controller to switch between a situation in which the rechargeable battery supplies electric power to the motor and a situation in which the rechargeable battery stops supplying electric power to the motor. The controller controls the power switching unit using a pulse width modulation (PWM) control signal when the electric power tool is activated. The controller changes a duty ratio of the PWM control signal in accordance with the detection signal of the detector.
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Citations
14 Claims
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1. An electric power tool comprising:
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a rechargeable battery; a motor; a detector configured to detect a parameter that affects a voltage drop of the rechargeable battery and output a detection signal corresponding to the detected parameter; a controller configured to receive the detection signal and generate a control signal in accordance with the detection signal; and a power switching unit operated in accordance with the control signal from the controller to switch between a situation in which the rechargeable battery supplies electric power to the motor and a situation in which the rechargeable battery stops supplying electric power to the motor, wherein the controller is configured to; control the power switching unit using a pulse width modulation (PWM) control signal when the electric power tool is activated, and change a duty ratio of the PWM control signal in accordance with the detection signal of the detector. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. An electric power tool comprising:
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a rechargeable battery; a motor; a motor driver connected to the motor; a detector configured to detect a parameter that affects a voltage drop of the rechargeable battery; and a controller connected to the detector and the motor driver to control the motor, wherein the controller is configured to; generate a pulse width modulation (PWM) control signal in accordance with the detected parameter, the PWM control signal having a duty ratio less than 100%, provide the motor driver with the PWM control signal having the duty ratio less than 100% throughout a motor start-up period to start the motor, and provide the motor driver with the PWM control signal having a duty ratio of 100% when the motor start-up period ends. - View Dependent Claims (10, 11, 12, 13, 14)
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Specification