A container (10), for example a drinks bottle, comprises means of producing an output such as a light signal (13) when the container is opened. Opening the container (10) causes switching of a detector circuit (20) included in the container (10), which in turn causes production of the output signal....http://www.google.ca/patents/US20060139928?utm_source=gb-gplus-sharePatent US20060139928 - Container with light or sound generator
