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TECHNIQUE FOR CONTROLLING MAINTENANCE FLUID APPLIED TO A THERMAL INK JET PRINTHEAD IN A MAINTENANCE STATION

IP.com Disclosure Number: IPCOM000027481D
Original Publication Date: 1997-Apr-30
Included in the Prior Art Database: 2004-Apr-08
Document File: 2 page(s) / 113K

Publishing Venue

Xerox Disclosure Journal

Abstract

Thermal mk jet printheads, whether of the partial-width scanning type or utilizing full-width print bars, require periodic maintenance which includes wiping or washing of the printhead face to remove ink which has accumulated (dried) along areas around the ink ejecting nozzles. In one procedure, the front face of a full-width bar is wet wiped by a maintenance fluid. Typically, the print bar is at a negative five inches water vacuum; thus there is approximately five inches of water of negative pressure at the nozzle ends of the ink channels within the printhead. A problem with this wet wipe procedure is that a large amount of maintenance fluid is sucked into the channels of the print bar via the nozzles causing serious dilution of the ink. It has also been observed that low surface tension fluid such as water solutions of IPA or Butyl-Carbitol wicked into the printhead through the channels dislodge air bubbles accumulated in the print bar reservoir area.

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XEROX DISCLOSURE JOURNAL

TECHNIQUE FOR CONTROLLING Proposed Classification MAINTENANCE FLUID APPLIED TO A
THERMAL INK JET PRINTHEAD IN A
MAINTENANCE STATION
Yonglin Xie

U. S. C1. 347/087 Int. C1. B41j 2/175

Thermal mk jet printheads, whether of the partial-width scanning type or utilizing full-
width print bars, require periodic maintenance which includes wiping or washing of the printhead face to remove ink which has accumulated (dried) along areas around the ink
ejecting nozzles. In one procedure, the front face of a full-width bar is wet wiped by a maintenance fluid. Typically, the print bar is at a negative five inches water vacuum; thus there is approximately five inches of water of negative pressure at the nozzle ends of the ink channels within the printhead. A problem with this wet wipe procedure is that a large amount of maintenance fluid is sucked into the channels of the print bar via the nozzles causing serious dilution of the ink. It has also been observed that low surface tension fluid such as water solutions of IPA or Butyl-Carbitol wicked into the printhead through the channels dislodge air bubbles accumulated in the print bar reservoir area.

One way of reducing the amount of maintenance fluid entering the channels is to close the ink supply line prior to maintenance, thus removing the five inches of water vacuum. The ink supply then is opened creating a one inch water head. A small negative pressure inside the printhead is created by fring small n# of pulses. The maintenance fluid is then applied. The maximum amount of maintenance fluid that can be sucked into the bar is just enough to release the pressure lost due to the firing of n# of pulses and equals the amount of ink
ejected. The amount of maintenance fluid that gets sucked into the bar can thus be controlled by changing n.

The vent is then closed, and the excess maintena...