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

• US 5,844,579 A
• Filed: 12/04/1995
• Issued: 12/01/1998
• Est. Priority Date: 12/04/1995
• Status: Expired due to Term

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Hewlett-Packard Company (HP Inc.)
• Inventors: Underwood, John A., Barinaga, John A., Cameron, James M.
• Primary Examiner(s): Fuller, Benjamin R.
• Assistant Examiner(s): HALLACHER, CRAIG ALAN
• Application Number:
  US08/566,819
• Time in Patent Office: 1,093 Days
• Field of Search: 347/7, 347/85, 347/86, 347/87
• US Class Current: 347/7
• CPC Class Codes: B41J 2/17513 Inner structure
• CPC Class Codes: B41J 2/1752 Mounting within the printer
• CPC Class Codes: B41J 2/17566 Ink level or ink residue control
• CPC Class Codes: B41J 2002/17573 using optical means for ink level indication
• CPC Class Codes: B41J 2002/17576 using a floater for ink level indication

Abstract

An ink supply for an ink-jet printer is provided with a main reservoir, which is typically maintained at ambient pressure. The main reservoir is coupled to a variable volume chamber via a one-way valve which allows the flow of ink from the reservoir to the chamber and prevents the flow of ink from the chamber to the reservoir. The chamber is coupled to a fluid outlet which is normally closed to prevent the flow of ink. However, when the ink supply is installed in a printer, the fluid outlet establishes a fluid connection between the chamber and the printer. The chamber is part of a pump provided with the ink supply that can be actuated to supply ink from the reservoir to the printer. The volume of the chamber can be monitored during actuation of the pump to detect when the quantity of ink within the ink supply is low.

Claims

1. A system for detecting when an ink supply for an ink-jet printer is out of ink, the system comprising:

a reservoir with the ink supply for containing ink;

a chamber coupled to the reservoir, the chamber having a volume variable between an expanded position and a retracted position and being normally biased toward the expanded position, wherein expansion of the chamber draws ink from the reservoir into the chamber;

a pump operatively associated with the reservoir;

an actuator movable between a first position in which said actuator engages the chamber to bias the chamber toward the retracted position to expel ink from the pump and a second position in which said actuator does not engage the chamber to allow the chamber to expand toward the expanded position to draw ink from the reservoir; and

a sensor associated with the actuator for monitoring the position of the actuator to detect when the chamber is in the retracted position, wherein in response to a first detection that the chamber is in the retracted position the actuator is moved to the second position to allow the chamber to draw ink from the reservoir, and wherein an out-of-ink signal is generated in the event that the sensor detects that the chamber is in the retracted position after the actuator is moved from the second position to the first position.

2. The system of claim 1 in which the sensor comprises an optical detector.

3. The system of claim 2 in which the actuator further comprises a flag fixed to the actuator and positioned to activate the optical detector when the chamber is in the retracted position.

4. 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.