XPost: sci.electronics.design, sci.electronics.equipment, sci.el   
   ctronics.repair   
   From: invalid@invalid.net   
      
   One source I found says that Canon uses light from an LED--bounced from a   
   prism at the bottom of the cartridge after ink is depleted--to trigger the   
   "Empty" signal. Epson apparently counts the spurts of ink and calculates the   
   arrival of "empty".   
      
   I couldn't find how HP do this. Anybody know?   
      
   Thanks.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)