| 摘要 |
<p>A switch (20) for controlling a rotational speed of a motor (18) includes an operation member (21), a first circuit (22), and a second circuit (27). The first circuit (22) includes a brush (24) coupled to the operation member (21) having a contact (T1) and also includes a variable resistive plate (23) having a resistance that changes in response to a contact position of the contact point of the brush (24), so that the first circuit (22) outputs a control signal to the motor (18) according to the contact position of the contact point. The second circuit (27) connects the brush (24) and the resistive plate (23) without through the contact point when the brush (24) is positioned at a given position relative to the resistive plate (23).</p> |
