Counter-boring techniques for improved ink-jet printheads

This invention relates to ink jet printers. In particular, this invention relates to novel designs and methods of manufacture of ink-jet printheads capable of providing ink-droplet-tail-break-off control and preventing meniscus overshoot in order to overcome the puddling, pen directionality, and ruffle problems associated with thermal-ink-jet printing. Novel designs and methods of manufacture of ink-jet printheads capable of providing ink-droplet-tail-break-off control and preventing meniscus overshoot in order to overcome the puddling, pen directionality, and ruffle problems associated with thermal-ink-jet printing are disclosed. A printhead for use in an ink-delivery system includes a substrate that has at least one ink ejector thereon. An orifice-plate member is positioned over and above the substrate. The orifice-plate member has at least one ink-transfer bore extending therethrough. The orifice-plate member further includes: a top surface that defines a top opening for the ink-transfer bore, a bottom surface that defines a bottom opening for the ink-transfer bore, and a counter-bore in the top surface that is in fluid communication with the ink-transfer bore. The counter-bore can be: concentric or non-concentric with the ink-transfer bore, a full or partial counter-bore, and symmetric or asymmetric. In addition, the counter-bore can also be deep enough to hold the ink meniscus. Lastly, the counter-bore can smooth, round and/or provide a more uniform edge around the ink-transfer bore. By providing one or more combinations of these features, the present invention is able to control the tail break-off of expelled ink-jet droplets and/or minimize meniscus overflow.