| 摘要 |
<p>The alarm switch consists of a cylinder (1) which has a cylindrical cavity (6) at the lower end, and a narrower tube (9) extending axially through the cylinder. At the top end of the tube is a switch contact (13). In the cavity (6) is a metal ball bearing (19a) which can roll through the tube when the switch is inverted, operating the switch contact. The device may be worn by shop assistants, bank employees, etc. strapped to the arm. If attacked and forced to raise the arms, an employee will automatically operate the switch which may be arranged to initiate a burglar alarm. It may also be used by the disabled as a warning if they fall.</p> |
