XPost: sci.electronics.design, sci.electronics.equipment, sci.el   
   ctronics.repair   
   From: dhky@shaw.ca   
      
   On 08/03/2015 1:22 AM, Charlie+ wrote:   
   > On Fri, 6 Mar 2015 23:03:13 -0800, DaveC  wrote as   
   > underneath :   
   >   
   >> 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?   
   >>   
   > Any inkjet that uses chipped cartridges guestimates the emptiness.  Old   
   > Canon printers certainly used the reflective prism, IP4000 was about the   
   > last that had unchipped carts. and thus had an accurate end level   
   > warning.  I think most printers now would guestimate on the safe side   
   > judging by the complaints of half full carts being classed as empty. I   
   > dont know if Canon still uses the prisms on their modern chipped carts   
   > but I would think probably not as the guestimate method gets you to buy   
   > more ink earlier! Someone with one of the more modern Canons will know   
   > Im sure! ... HP have had chips since very early days so levels will be   
   > guestimated by software.  C+   
   My old(?) Canon MP 620 uses chipped cartridges as far as I know and when   
   I get an empty signal -the cartridge is fully emptied.   
      
      
      
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