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Charge Compensation for Ink Jet

IP.com Disclosure Number: IPCOM000081304D
Original Publication Date: 1974-May-01
Included in the Prior Art Database: 2005-Feb-27
Document File: 2 page(s) / 28K

Publishing Venue

IBM

Related People

Bloom, RD: AUTHOR [+3]

Abstract

During the printing of a character stroke or bar on a high-speed document in an electrostatic ink jet printer, misalignment or curvature of the last printed drop occurs, because of the sizable charge differential between the drop preceding the last printed drop and the following or discarded drops. The misalignment can be corrected by decreasing the charge differential, by adding compensating charges to the discarded drops. It is not necessary to add compensation for the first printed drop, because the aerodynamic effect tends to negate the effect of the large charge differential.

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Charge Compensation for Ink Jet

During the printing of a character stroke or bar on a high-speed document in an electrostatic ink jet printer, misalignment or curvature of the last printed drop occurs, because of the sizable charge differential between the drop preceding the last printed drop and the following or discarded drops. The misalignment can be corrected by decreasing the charge differential, by adding compensating charges to the discarded drops. It is not necessary to add compensation for the first printed drop, because the aerodynamic effect tends to negate the effect of the large charge differential.

For example, in a printer where a series of drops 1-8 may be charged with charging plate voltages of 65 to 160 volts for printing a bar, the following discarded drops 9 and 10, instead of being substantially zero as indicated by the left bar in the figure, are given an intermediate value of 30 volts. This charging voltage deflects drops 9 and 10 into the upper cavity of the gutter which is used for sensing. Likewise, discarded drop 11, is given a nominal value such as 3 volts (essentially uncharged) on the charging plates, so as not to cause undesirable misalignment of the first drop of the following bar. This technique allows a single gutter to be used. This type of compensation reduces the misalignment due to charge interaction among drops and achieves quality printing.

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