| 摘要 |
A battery-operated burglar alarm mounted to the inside of a door and capable of being armed from either side. Two slides on the device provide for two modes of operation in cooperation with a plate fastened to the door frame. One slide permits manual arming of the alarm from the inside with the door closed. Another slide permits manual pre-arming of the alarm from the inside with the door open and subsequent automatic arming of the alarm as the door is closed. Depending upon the mode of operation, unauthorized opening of the door can either lock the door and instantaneously sound an alarm or sound an alarm after a predetermined time with the door unlocked. A combination switch deactivates the alarm and another switch can alter the combination.
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