How does the ink level gauge work?
August 19, 2007 – 5:38 pmMany printers will indicate the ink level remaining in the ink tanks, usually in the form of a readout on the screen of the associated computer.
It will be a surprise to many users to be told that the printer doesn’t measure the ink level. The readout is the result of some clever software making an estimate of how much ink is remaining based on the amount of printing and purging done. And this guesstimate can get confused and be totally wrong.
(If you still think a £70 printer contains six electronic liquid level gauges, ask your auto dealer what the fuel gauge for your car costs to replace.)
So how does it work (and how can it go wrong)?
The software works with a sequence of events as follows:
(with free ink sensor)
Printer detects the insertion of an ink tank containing free liquid ink - software assumes it is 100% full.
Ink is used for printing or purging - software estimates the new ink level.
Printer detects that there is no longer any free ink in the tank. Software indicates that tank is low and needs changing soon.
A few pages can be printed with the ink in the internal absorber. Then the software signals “No ink” using a software counter.
Inktank is changed (or ink runs out).
(without free ink sensor)
User signals that a new ink tank has been fitted.
Ink is used for printing or purging - software estimates the new ink level.
Software indicates that tank is low and needs changing soon.
After a few pages, the software signals “No ink” using a software counter.
Inktank is changed (or ink runs out).
The system with free ink sensor works well enough to convince users that the printer contains several electronic liquid level gauges, which it almost certainly does not. This depends on the ink tanks being undisturbed. The removal and replacement of partly full tanks will confuse the software and invalidate the readouts.
If you are having an ink problem, don’t rely on an electronic readout. If the design of the printer permits, remove the ink tank and (assuming it is transparent) look at the ink level. If the tank is opaque, feel its weight or swap it for a full one.