Monitoring tag with removal detection

摘要

A tag is provided for being secured to an object whose location is to be monitored. Improved mechanisms are provided for ensuring that removal of the tag is detected and signaled to a monitoring system. One preferred embodiment of the tag of the present invention includes an optical sensor for sensing when the tag is near the surface of the object whose location is being monitored. The optical sensor emits optical signals to the surface of the object being monitored and receives reflected optical signals back therefrom. The tag periodically transmits status messages to the monitoring system which permit the monitoring system to determine whether the tag is being held near the object and whether the tag is within the monitored area. In another embodiment of the present invention, a temperature sensor is substituted for the optical sensor.