| 摘要 |
A magnetically operated door chime adapted for mounting on a door and door frame. The door chime includes a casing adapted for mounting on the door frame and having a plunger assembly mounted for reciprocation along a horizontal path perpendicular to the plane of the door when the door is closed. The plunger assembly includes a first magnetic unit on its outer end arranged in face-to-face contact with a second magnetic unit on the door, when the door is closed. A chime bar extends across the path of movement of the other end of the plunger assembly and a spring yieldably biases the plunger assembly in a direction toward the chime bar. The spring is yieldable under the magnetic force between the first and second magnetic units so that the plunger assembly moves with the second magnetic unit as the door is moved away from its closed position until the compression of the spring overcomes the magnetic force between the first and second magnetic units and moves the plunger in the other direction in an impact stroke against the chime bar. A second spring is arranged to move the plunger a short distance in opposition to the first spring to retract the plunger a short distance away from the chime bar and to provide a yieldable abutment for the first magnetic unit when the door is closed.
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