Patent ID: 6164766
Filing Date: 2000-12-26
Classification: B41J,F16G

Abstract:
An ink refill system for an ink jet printer having a print carriage that traverses across a print medium and is adapted to receive one or more ink jet cartridges, the ink refill system comprising:a disposable ink jet cartridge removably mountable in the print carriage and constructed as a self-contained unit that includes a print head and an ink supply container that stores a first quantity of liquid ink at a given negative pressure hydrodynamic condition;an ink reservoir external to the print carriage that stores a second quantity of ink for replenishing the first quantity of ink in the ink supply container;flexible supply tubing that couples the ink reservoir to the ink supply container to supply ink from the second quantity of ink to the first quantity of ink during operation of the ink jet printer as the print carriage traverses across the print medium; andmeans for refilling the ink supply container from the ink reservoir during operation of the ink jet printer as the print carriage traverses across the print medium such that the refilling of the ink reservoir is accomplished in a manner that preserves the negative pressure hydrodynamic condition of the ink jet cartridge;wherein the means for refilling the ink supply container is an on-demand, active system that periodically refills the ink supply container and comprises:means for sensing when the first quantity of ink in the ink supply container is below a predetermined threshold;means for pumping from a portion of the second quantity of ink from the ink reservoir to the ink supply container in the ink jet cartridge in response to the means for sensing; anda foam body having at least a first surface operably coupled to the print head and a second surface onto which the portion of the second quantity of ink is pumped from the supply tubing:wherein the means for sensing comprises:an ink level sensor having at least two electrical contacts, each contact mounted through an aperture in a side surface of the ink jet cartridge and extending into the foam body; andcircuit means for monitoring a change in the status of the ink level sensor and activating the means for pumping in response to the change.