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Security module for a printing apparatus

  • US 5,720,012 A
  • Filed: 01/27/1997
  • Issued: 02/17/1998
  • Est. Priority Date: 01/12/1995
  • Status: Expired due to Term
First Claim
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1. A printing apparatus comprising:

  • an image output terminal for rendering an image on a surface according to imagewise digital data, including at least one command receiving element for operating a mechanical element of the image output terminal in response to a command signal, and a status element for producing a status signal in response to a condition within the image output terminal;

    an electronic subsystem, adapted to output imagewise digital data as video signals and a command signal to the image output terminal, and to receive a status signal from the status element;

    a connection between the image output terminal and the electronic subsystem, the connection acting as a medium for passage of video signals, command signals and status signals therethrough, the connection including at least a video line for transmission of video signals, a status line for transmission of status signals, and a command line for transmission of command signals; and

    a security module, having a security algorithm associated therewith, operatively interposed along the command line and the status line between the image output terminal and the electronic subsystem, the security module adapted to receive a command signal through the command line, process the command signal according to the security algorithm, and selectably output an altered command signal to the image output terminal through the command line, the security module being further adapted to receive a status signal through the status line from the status element associated with the image output terminal, process the status signal according to the security algorithm, and selectably output an altered status signal to the electronic subsystem through the status line, the security module being independent of the video line and not altering the video signals.

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