| 摘要 |
<p>: A pushbutton, particularly a key of a keyboard, comprises an upper part for operation by finger touch and a lower part serving to operate an activating member, such as an electrical contact, the lower part being constructed with two surface portions of different inclination to the direction of movement of the pushbutton, said surface portions being engaged by a spring wire so as to create a sudden drop of the restoring spring force when the spring wire passes from the more inclined surface portion to the less inclined surface portion.</p> |
