Browse Prior Art Database

Electronic Aiming of Ink Jets

IP.com Disclosure Number: IPCOM000088221D
Original Publication Date: 1977-May-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 3 page(s) / 49K

Publishing Venue

IBM

Related People

Pimbley, WT: AUTHOR [+2]

Abstract

When more than one jet is used to print characters or images, the aim of each nozzle relative to the others becomes critical, if high print quality is to be obtained. As seen in Fig. 1, parallel ink streams 1-5 are projected from plural orifices in nozzle plate 10 past a block 11 of charging plates 1A-5A, where individual drops are selectively charged and then caused to pass between deflection plates 12 and 13, where they are normally dispersed, in accordance with the charge, to Rutter 14 or a print medium (not shown). For checking and adjusting the aim of each jet stream, all ink drops of all jet streams are initially directed in an uncharged state to gutter 14. The aim of each stream is checked and adjusted, one at a time, by deflecting the stream to the drop detector.

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Electronic Aiming of Ink Jets

When more than one jet is used to print characters or images, the aim of each nozzle relative to the others becomes critical, if high print quality is to be obtained. As seen in Fig. 1, parallel ink streams 1-5 are projected from plural orifices in nozzle plate 10 past a block 11 of charging plates 1A-5A, where individual drops are selectively charged and then caused to pass between deflection plates 12 and 13, where they are normally dispersed, in accordance with the charge, to Rutter 14 or a print medium (not shown). For checking and adjusting the aim of each jet stream, all ink drops of all jet streams are initially directed in an uncharged state to gutter 14. The aim of each stream is checked and adjusted, one at a time, by deflecting the stream to the drop detector. The drop detector, in the form of a piezoelectric sensor 15, is located behind gutter 14 off to the side of the page so that charged drops clearing the edge of gutter 14 may impact sensor 15 and generate a detectable output voltage.

The aim in the direction of deflection may be checked by determining at what deflection potential the stream just impacts an edge of the drop detector which is perpendicular to the direction of deflection. A DC bias determined by this deflection potential can then be added to the deflection signals, when printing, to correct the aim in this direction, which is parallel to the direction of deflection.

The aim of a jet stream in the direction perpendicular to the direction of deflection can be adjusted by varying the time delay of information fed to the charge plate for that stream. If the aim in this orthogonal direction is correct, a standard time delay for shift register(s) 1B-5B for the subject stream is used. If the orthogonal aim is to the left of the correct position, a delay greater than normal is added to shift register(s) 1B-5B, when printing i...