| 摘要 |
An apparatus for sounding an audible alarm when an object, such as a child or a pet, falls into a pool. An elongated housing is secured to the pool such as by fastening it to a pool ladder, with a control head on one end above the water surface and the other, sensing, head below the surface. At least one reed switch is positioned at the lower end of the housing. An elongated permanent magnet is mounted in a support body typically a buoyant body fastened to a flexible but stiff strap so that one pole of the magnet is adjacent to the reed switch. The magnet is positioned with the line through the north and south magnetic poles being approximately perpendicular to the switch. The strap is secured to an open container below the housing such that the strap and buoyant body can pivot in a single plane lying substantially parallel to the length of the reed switch. Thus, when the pool is calm the center of the magnet is adjacent to the reed switch. When a body falls into the pool, the resulting wave and compression causes the buoyant body to pivot, moving the magnet relative to the reed switch, activating the reed switch, causing the alarm to sound. A second reed switch can be arranged parallel to and offset from the first reed switch to allow the switches to be connected to the alarm in a manner permitting system sensitivity to be varied. Alternative magnet supports may be used.
|
