| 摘要 |
Electric toothbrush includes a hollow handle and a rotary brush. A gravity-induced movement responsive switch, such as mercury switch, is located within the handle, and a hand-operated switch is located on the outer surface of the handle. A user by operating a hand-operated switch sets the brush to a lower row of teeth or an upper row of teeth thus switching over an electromotor located within the handle whereas the mercury switch automatically reverses the direction of rotation of the electromotor shaft depending upon respective tilted positions of the handle. An intermediate element, for example a spur-gearing coupling is interconnected between the shaft of the motor and the brush.
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