6,879,242 Color based lock and key
  Issued: April 12, 2005
  Filed: March 15, 2002
  U.S. Class: 340/5.6
Abstract:  A colored based lock and key, wherein the key includes a color indication incorporated thereon, and the lock includes a color sensor for identifying the color indication, so as to open the lock. According to a preferred embodiment of the invention, the key includes a blank or blanks on which at least one, and preferably a plurality of colors are incorporated. The blank or blanks can be formed of metal, plastic, or any other material on which colors or color emitting or color reflecting materials can be incorporated by various methods. According to other preferred embodiments of the present invention, the lock includes at least one color sensor arranged to sense the color incorporated on the key or on a predefined sequence of keys, when the key or keys are inserted in the lock, or put across the lock or rotated in the lock, and further includes a decision mechanism activated by an electric signal generated upon identification of the color incorporated on the key, to permit opening of the lock. According to another embodiment of the invention, the color sensor includes a light source for directing light at the color incorporated on the key, a reflected light detector, an evaluation unit for determining frequency, and perhaps intensity, of the reflected light.