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MAINTENANCE STATION

IP.com Disclosure Number: IPCOM000025829D
Original Publication Date: 1988-Jun-30
Included in the Prior Art Database: 2004-Apr-04
Document File: 4 page(s) / 140K

Publishing Venue

Xerox Disclosure Journal

Abstract

One of the major problems in maintaining the reliability of a thermal ink jet printer is the problem related to clogging of the nozzles of the printhead. Each printhead has a plurality of ink filled capillary channels. Each channel terminates at one end with a nozzle which confronts a recording medium, such as paper. The other end communicates with a relatively small ink holding manifold. For a carriage type printer, one or more ink supply carriages has fixedly mounted thereon a printhead with means for sealingly interconnecting the printhead manifold with the ink in the cartridge. The ink in the printhead is maintained at a slightly negative pressure so that a meniscus is formed at each nozzle to prevent weeping of the ink therefrom. Ink droplets are ejected on demand by selectively addressing a resistor located in each channel slightly upstream from the nozzle with a current pulse. Each current pulse causes the resistor to form a momentary vapor bubble which ejects the droplet during the bubble's growth and collapse. Clogging occurs whenever the ink meniscus is exposed to air for relatively long periods of time without droplets being ejected, such as during printer standby.

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Page 1 of 4

KEROX DISCLOSURE JOURNAL

MAINTENANCE STATION

Proposed George 0. Hempel Classification

U.S. C1.346/140R Int. C1. Gold 15/16

22

/

14

Volume 13 Number 3 May/June 1988

14'

131

[This page contains 1 picture or other non-text object]

Page 2 of 4

MAINTENANCE STATION (Cont'd)

One of the major problems in maintaining the reliability of a thermal ink jet printer is the problem related to clogging of the nozzles of the printhead. Each printhead has a plurality of ink filled capillary channels. Each channel terminates at one end with a nozzle which confronts a recording medium, such as paper. The other end communicates with a relatively small ink holding manifold. For a carriage type printer, one or more ink supply carriages has fixedly mounted thereon a printhead with means for sealingly interconnecting the printhead manifold with the ink in the cartridge. The ink in the printhead is maintained at a slightly negative pressure so that a meniscus is formed at each nozzle to prevent weeping of the ink therefrom. Ink droplets are ejected on demand by selectively addressing a resistor located in each channel slightly upstream from the nozzle with a current pulse. Each current pulse causes the resistor to form a momentary vapor bubble which ejects the droplet during the bubble's growth and collapse. Clogging occurs whenever the ink meniscus is exposed to air for relatively long periods of time without droplets being ejected, such as during printer standby.

A maintenance station 10 capable of sealing the nozzles of four printheads 12 that are attached to separate ink supply cartridge 14, both in dashed line, is shown in the accompanying figure. During the standby mode, the one or more cartridges with integral printhead is traversed to one side of the printer and beyond the normal pagewidth printing platen (not shown), where the maintenance station is located. The station has coaxially aligned openings 16 in chamber 18 and seal 20 through which the printheads can eject droplets before they are returned to the printing area in order to clear the nozzles of any part...