Abstract: A battery charger for charging a detachably attached battery pack by supplying an electric power from an external power source, the battery charger includes a notification unit for notifying a user of a charging operation by turning on or flickering a light-emitting member. The notification unit notifies the user of a power connection state of the battery charger by turning on or flickering the light-emitting member immediately after the battery charger is electrically connected to the external power source without attaching the battery pack thereto, and the notification unit turns off the light-emitting member after a predetermined period of time lapses and keeps the light-emitting member in an off-state until the battery pack is attached to the battery charger.

Abstract: A charger for an electric power tool includes a charging unit for charging a secondary battery detachably attached to the charger; a notification unit for notifying an operation state of the charging unit by using a combination of a turn-on and turn-off of the notification unit; a brightness reducing unit for reducing a light brightness of the notification unit; and a controller for controlling the notification unit and the brightness reducing unit. If an operation state of the charging unit satisfies a specific condition, the controller controls the brightness reducing unit to reduce the light brightness of the notification unit.

Abstract: A power tool system with enhanced antitheft capability has a hand-held power tool and a wearable piece worn by the user. The wearable piece incorporates a certification unit which stores an identification code specifying the power tool and transmits the identification code to an authenticator incorporated in the power tool. The authenticator reads the identification code from the certification unit and to provide an authentication signal when the identification code is authenticated to be eligible for a privileged use of the power tool. The power tool is enabled only in response to the authentication signal, and otherwise disabled for avoiding unauthorized use. A communication is established between the certification unit and the authenticator for transmission of the identification code, while the user holds the power tool with the wearable piece carried on.

Abstract: A rechargeable electric power tool includes a motor driven by a secondary battery, a switching element for regulating power distribution to the motor, a motor control unit for controlling rotation of the motor through the switching element, a lead wire for supplying a drive current to the motor therethrough and a trigger switch changed over by a user for turning on or off the drive current supplied to the motor through the lead wire. In the rechargeable electric power tool, upon changeover of the trigger switch, a microcomputer determines a magnitude relation between a detected temperature outputted from a first thermistor and a first temperature threshold value. If the detected temperature is determined to be greater than the first temperature threshold value, the microcomputer is set in a limited operation mode in which a revolution number of the motor is limited to a predetermined value or less.

Abstract: In a rechargeable electric power tool, upon changeover of a trigger switch, a microcomputer determines the magnitude relation between the detected temperature outputted from the first thermistor and the first temperature threshold value, the second temperature threshold value and the third temperature threshold value, and the magnitude relation between the first calculated temperature increase rate and the first preset temperature increase rate. If the detected temperature is determined to be greater than the first temperature threshold value or if the first calculated temperature increase rate is determined to be greater than the first preset temperature increase rate after the detected temperature has been determined to be greater than the second temperature threshold value, the microcomputer is set in a limited operation mode in which the revolution number of the motor is limited to a predetermined value or less.

Abstract: An electric power tool includes a tool body and a battery pack removably mounted to the tool body. The battery pack is used as a power source of the tool body. The electric power tool further includes a lock unit for keeping the battery pack mounted to the tool body and an interrupter switch for interrupting the operation of the tool body when the lock unit does not keep the battery pack mounted to the tool body. Accordingly, the electric power tool is not operable when the battery pack is not completely mounted to the tool body.

Abstract: A battery pack includes a status detection unit for detecting a status of a battery; a switch unit for interrupting a discharging path of the battery; a notification unit for notifying a user of the status of the battery; an operation unit operable by the user; and control unit for opening and closing the switch unit. The control unit is configured to have the switch unit interrupt the discharging path of the battery when the status of the battery detected by the status detection unit is abnormal. Further, the control unit is configured to have the notification unit notify the user of the availability to restart a discharging operation and close the switch unit in response to an operation signal inputted from the operation unit to make the battery pack dischargeable when the status of the battery detected by the status detection unit is recovered from the abnormal status.

Abstract: A charging device includes a charging unit; a detection unit for detecting a temperature and a temperature increasing rate of a rechargeable battery; a controller for controlling the charging unit to supply a charging current to the rechargeable battery; and a compensating unit for setting a value of the first threshold to be greater if the temperature of the rechargeable battery at the time of mounting the rechargeable battery on the charging device is equal to or smaller than a second threshold and smaller if otherwise. The charging unit stops supplying the charging current to the rechargeable battery if the temperature increasing rate is equal to or greater than a first threshold.

Abstract: A battery charger includes an attachment portion capable of being connected to a plurality of battery packs; a connection unit for connecting one of the battery packs connected to the attachment portion to a charging path; a state detection unit for detecting a state of each of the battery packs; a remaining capacity detection unit; and a charging control unit. The remaining capacity detection unit detects a remaining capacity based on the state of the battery pack detected by the state detection unit after each of the battery pack is charged for a specified period of time. Further, the charging control unit assigns priorities to the battery packs such that one whose remaining capacity detected by the remaining capacity detection unit is closer to a fully charged state thereof has a higher priority, and controls the connection unit to charge the battery packs according to the assigned priorities.

Abstract: A constant-current battery charger includes a power supply for supplying a charge current to a secondary cell, and a current monitor for monitoring a charge current being supplied to the cell. A controller is included for varying the charge current in accordance with the monitored charge current. The controller calculates a current difference between a predetermined target current and the instant charge current, and generates a demand of varying the charge current at a first charge rate when the current difference is out of a predetermined range, and varying the charge current at a second charge rate when the current difference is within the predetermined range. The controller generates the demand repeatedly at regular or varying intervals for varying the charge current. The first charge rate is set to be higher than the second charge rate in order to make a rapid charging until it comes close to the target current.

Abstract: A charging device includes a charging unit; a detection unit for detecting a temperature and a temperature increasing rate of a rechargeable battery; a controller for controlling the charging unit to supply a charging current to the rechargeable battery; and a compensating unit for setting a value of the first threshold to be greater if the temperature of the rechargeable battery at the time of mounting the rechargeable battery on the charging device is equal to or smaller than a second threshold and smaller if otherwise. The charging unit stops supplying the charging current to the rechargeable battery if the temperature increasing rate is equal to or greater than a first threshold.

Abstract: A power tool system with enhanced antitheft capability has a hand-held power tool and a wearable piece worn by the user. The wearable piece incorporates a certification unit which stores an identification code specifying the power tool and transmits the identification code to an authenticator incorporated in the power tool. The authenticator reads the identification code from the certification unit and to provide an authentication signal when the identification code is authenticated to be eligible for a privileged use of the power tool. The power tool is enabled only in response to the authentication signal, and otherwise disabled for avoiding unauthorized use. A communication is established between the certification unit and the authenticator for transmission of the identification code, while the user holds the power tool with the wearable piece carried on.

Abstract: A constant-current battery charger includes a power supply for supplying a charge current to a secondary cell, and a current monitor for monitoring a charge current being supplied to the cell. A controller is included for varying the charge current in accordance with the monitored charge current. The controller calculates a current difference between a predetermined target current and the instant charge current, and generates a demand of varying the charge current at a first charge rate when the current difference is out of a predetermined range, and varying the charge current at a second charge rate when the current difference is within the predetermined range. The controller generates the demand repeatedly at regular or varying intervals for varying the charge current. The first charge rate is set to be higher than the second charge rate in order to make a rapid charging until it comes close to the target current.