Patent ID: 6856238
Filing Date: 2005-02-15
Classification: F41A

Abstract:
1. An apparatus for limiting usage of an associated appliance to an authorized user, comprising: an electronic unit operatively coupled to the associated appliance, said electronic unit configured to regulate activation of the associated appliance; at least one authorizing unit associated with an authorized user, said authorizing unit configured to periodically emit a signal representative of a unique message; wherein said electronic unit is further configured to receive said signal; and wherein said electronic unit is further configured to calculate a differential strength of said signal to identify a spatial relationship including at least a distance and orientation of said at least one authorizing unit relative to said electronic unit; and wherein said electronic unit is further configured to activate the associated appliance only in response to said unique message corresponding to a predetermined message and said identified spatial relationship establishing a presence of said at least one authorizing unit within a predetermined limited spatial volume relative to said electronic unit, said electronic unit including an omni-directional antenna having a first signal detection region and a directionally sensitive antenna having a second signal detection region; and wherein an intersection of said first and second signal detection regions defines said predetermined limited spatial volume relative to said electronic unit, and said electronic unit being configured to calculate said differential signal strength utilizing a signal received at said omni-directional antenna and a signal received at said directionally sensitive antenna.