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IMPROVED DESIGNS TO PREVENT AIR INGESTION OF A THERMAL INK JET PRINTHEAD

IP.com Disclosure Number: IPCOM000027427D
Original Publication Date: 1996-Dec-31
Included in the Prior Art Database: 2004-Apr-07
Document File: 4 page(s) / 148K

Publishing Venue

Xerox Disclosure Journal

Abstract

Disclosed are five channel design modifications for a thermal ink jet printhead that prevents air ingestion by addressing the problem of the meniscus shape during refill. As used in this description, "air ingestion" refers to air being sucked in from the front of a printhead and becoming trapped on a heater surface to prevent drops from being fired.

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XEROX DISCLOSURE JOURNAL

IMPROVED DESIGNS TO PREVENT AIR INGESTION OF A THERMAL INK JET PRINTHEAD Int. C1. B41J 29/38 Eduardo M. Freie

Proposed Classification
U. S. C1. 347/005

FIG. 7

FIG. 2

XEROX DISCLOSURE JOURNAL - Vol. 21, No. 6 NovemberDecernber 1996 357

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IMPROVED DESIGNS TO PREVENT AIR INGESTION OF A THERMAL INK JET PRINTHEAD (CONT'D)

FIG. 3

FIG. 4

FIG. 5

358 XEROX DISCLOSURE JOURNAL - Vol. 21, No. 6 NovembedDecember 1996

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IMPROVED DESIGNS TO PREVENT AIR INGESTION OF A THERMAL INK JET PRINTHEAD (CONT'D)

Disclosed are five channel design modifications for a thermal ink jet printhead that prevents air ingestion by addressing the problem of the meniscus shape during refill. As
used in this description, "air ingestion" refers to air being sucked in from the front of a printhead and becoming trapped on a heater surface to prevent drops from being fired.

When a drop is fred in a thermal ink jet printhead, the ink located in the front channel region is ejected and the refill process, driven by surface tension begins. Exactly where the meniscus is after fuing depends, among other things, on the amount of ink ejected. It may happen, either by temperature increase or by design that, after fuing, the meniscus retracks all the way back to the heater region. In this case, air may be trapped on top of the heater surface and no subsequent firing can occur until the air is removed.

As the meniscus starts to refd the channel (at the heater region), its shape depends on geometry of the channel and contact angles. If the meniscus 10 advances first at the roof and goes to the front region, as shown in Figure 1, the probability of having air ingestion is high. If, on the other hand, the meniscus 10 gets to the heater surface fust, as shown in Figure 2, the air will be displaced from the heater and ingestion will not occur.

The meniscus can be made to displace air from the heater pit during refdl more efficiently by any one of the following improvements or combinations thereof:

1. Making the roof of the heater (channel plate) differentially less wetable than the heater surface. This is accomplished by su...