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METHOD TO IMPROVE EFFICIENCY OF INK-JET PRINT HEADS

IP.com Disclosure Number: IPCOM000026269D
Original Publication Date: 1991-Feb-28
Included in the Prior Art Database: 2004-Apr-05
Document File: 2 page(s) / 69K

Publishing Venue

Xerox Disclosure Journal

Abstract

Many thermal ink jet print head devices are drop-on-demand type. Clogging of the jets during standby periods may be prevented by periodically firing ink through the jets and then into a waste gutter that prevents drying at the nozzle. Unfortunately, this procedure wastes ink that is otherwise useful for printing. Further, the maximum firing rate and the printing rate of the ink jet are limited by the time necessary to reload the jet with ink from an ink reservoir. During firing, a channel leading to the nozzle is heated and the channel must cooled down by conductive or convective means before it can be readied for the next firing. To overcome these shortcomings, the temperature of the print head may be deliberately lowered by external means using at least one cooling element during print operation. The advantages derived from lowering the temperature are: (1.) reduction in the rate of ink evaporation from the jet nozzle and hence and increase in the time between firings required to prevent drying during standby: and (2.) provides for faster cooling of the individual channels and therefore reduces the time between firings in the print mode. The cooling may be accomplished by thermoelectric means such as a Peltier effect device. These devices operate on low voltage direct current and have a high electrical to thermal conversion efficiency (30-50CTc). Moreover, they are ideally suited for this application because their compact size permits easy integration into existing print heads.

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XEROX DISCLOSURE JOURNAL

METHOD TO IMPROVE Proposed Classification EFFICIENCY OF INK-JET PRINT
HEADS
Int. C1. Gold 15/16
N. Kedarnath Mark J. Hirsch

US. C1.346/140

Many thermal ink jet print head devices are drop-on-demand type. Clogging of the jets during standby periods may be prevented by periodically firing ink through the jets and then into a waste gutter that prevents drying at the nozzle. Unfortunately, this procedure wastes ink that is otherwise useful for printing. Further, the maximum firing rate and the printing rate of the ink jet are limited by the time necessary to reload the jet with ink from an ink reservoir. During firing, a channel leading to the nozzle is heated and the channel must cooled down by conductive or convective means before it can be readied for the next firing. To overcome these shortcomings, the temperature of the print head may be deliberately lowered by external means using at least one cooling element during print operation. The advantages derived from lowering the temperature are: (1.) reduction in the rate of ink evaporation from the jet nozzle and hence and increase in the time between firings required to prevent drying during standby: and (2.) provides for faster cooling of the individual channels and therefore reduces the time between firings in the print mode. The cooling may be accomplished by thermoelectric means such as a Peltier effect device. These devices operate on low voltage direct current and have a high electric...