Out-of-ink sensing system for an ink-jet printer

A method of detecting when a reservoir is out of ink in an ink-jet printer having a docking bay into which an ink supply can be inserted, the ink supply having the reservoir for containing a quantity of ink, a variable volume chamber in fluid communication with the reservoir, the chamber being movable from a retracted position to an expanded position to draw ink from the reservoir into the chamber and movable from the expanded position to the retracted position to expel ink from the chamber and to the printer, the chamber being normally biased toward the expanded position, the method comprising the steps of:

• moving an actuator into contact with the chamber to urge the chamber toward the retracted position and expel ink from the chamber;
• monitoring the position of the actuator to determine when the actuator has urged the chamber into the retracted position;
• in response to an initial determination that the chamber is in the retracted position withdrawing the actuator from contact with the chamber to allow the chamber to move to the expanded position;
• a predetermined after withdrawing the actuator, moving the actuator into contact with the chamber;
• monitoring the position of the actuator to determine whether the chamber expanded from the retracted position during the predetermined time;
• and
• outputting an out-of-ink signal if the chamber did not expand during the predetermined time.