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Asynchronous Ink Jet Printing Method

IP.com Disclosure Number: IPCOM000089794D
Original Publication Date: 1977-Dec-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 36K

Publishing Venue

IBM

Related People

Darling, RH: AUTHOR

Abstract

An asynchronous ink jet printing apparatus is shown in the upper figure. This apparatus comprises a nozzle 10 from which an ink stream is projected, and the nozzle is vibrated so that the stream breaks up into a series of drops of uniform size and spacing. A charge plate 12 is mounted at the point of drop breakoff so that the charge can be selectively applied to each drop as it is formed from the ink stream. The drops are then projected through a deflection field produced between ground plate 14 and high voltage plate 16. Uncharged drops pass to paper 18 for printing, whereas charged drops are deflected to a gutter for recirculation. This printing technique has the advantage that there is synchronization between drop formation time and charging time.

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Asynchronous Ink Jet Printing Method

An asynchronous ink jet printing apparatus is shown in the upper figure. This apparatus comprises a nozzle 10 from which an ink stream is projected, and the nozzle is vibrated so that the stream breaks up into a series of drops of uniform size and spacing. A charge plate 12 is mounted at the point of drop breakoff so that the charge can be selectively applied to each drop as it is formed from the ink stream. The drops are then projected through a deflection field produced between ground plate 14 and high voltage plate 16. Uncharged drops pass to paper 18 for printing, whereas charged drops are deflected to a gutter for recirculation. This printing technique has the advantage that there is synchronization between drop formation time and charging time.

One of the drawbacks of this technology is that consistently poor print patterns can result if the drop breakoff happens to occur during charge pulse rising or decaying time and remains this way for a period of time. To avoid this problem, a frequency mismatch is imposed between the drop rate F(drop) and F(data). This relation is made to be F(drop) = n(F(data)) + Alpha, where Alpha is a small number.

As a result, the phase relationship between drop rate and data rate for successive drops is no longer the same, and bad phasing becomes statistically evenly distributed on the paper instead of being concentrated so that print quality can be improved.

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