Abstract: The present invention is a method and apparatus for printing documents such as checks that includes an almost imperceptible security image or string of characters on the original face of the document. However, a scanned image of the original document (such as a photocopy) includes a clearly visible presentation of the security image or string of characters that distinguishes the photocopy from the original. The method of creating the security image involves printing a background of a gray scale, removing a portion of the gray scale in the shape of a security image or text, and printing a second gray scale in the removed area causing the two gray scales to appear as one, but where a scanned image of the document distinguishes the two gray scales to reveal the security image.

Abstract: The present invention is a method and apparatus for communicating to a printer a type of installed printer cartridge, where the combination of the cartridge and the printer form a magnetic coupling that can generate a cartridge specific code to identify the toner cartridge as being of a predetermined type. In a preferred embodiment, the magnetic coupling is achieved using at least two reed switches preferably mounted on the printer, with the reed switches biased using fixed magnetic elements placed immediately adjacent the reed switches. In the absence of any further magnetic fields, the reed switches are selected to provide a known set of switch positions corresponding to a bit value of one (“1”) for an open circuit and a bit value of zero (“0”) for a closed circuit.

Abstract: An apparatus for communicating to a printer a type of installed printer cartridge, where the combination of the cartridge and the printer form a magnetic coupling that can generate a cartridge specific code to identify the toner cartridge as being of a predetermined type. In a preferred embodiment, the magnetic coupling is achieved using at least two reed switches preferably mounted on the printer, with the reed switches biased using fixed magnetic elements placed immediately adjacent the reed switches. In the absence of any further magnetic fields, the reed switches are selected to provide a known set of switch positions corresponding to a bit value of one (“1”) for an open circuit and a bit value of zero (“0”) for a closed circuit.