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Aspirated Ink Jet Head Design

IP.com Disclosure Number: IPCOM000053126D
Original Publication Date: 1981-Sep-01
Included in the Prior Art Database: 2005-Feb-12
Document File: 5 page(s) / 162K

Publishing Venue

IBM

Related People

Blanck, TW: AUTHOR [+7]

Abstract

In aspirated ink jet printing, moving air is cause to surround and flow in substantially the same direction as the ink stream. The moving air greatly reduces the aerodynamic interaction between drops and thereby permits simpler drop placement algorithms, yields higher throughput by eliminating the need for guard drops, and makes possible superior print quality by inhibiting the necessity for merged drop pairs. The head design described hereinafter permits more predictable orientation of the ink stream when air flows through the aspirator tunnel by providing for a double-flared deflection electrode, and by providing a flat air reentrance surface, makes ink stream viewing at the charge electrode simpler.

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Aspirated Ink Jet Head Design

In aspirated ink jet printing, moving air is cause to surround and flow in substantially the same direction as the ink stream. The moving air greatly reduces the aerodynamic interaction between drops and thereby permits simpler drop placement algorithms, yields higher throughput by eliminating the need for guard drops, and makes possible superior print quality by inhibiting the necessity for merged drop pairs. The head design described hereinafter permits more predictable orientation of the ink stream when air flows through the aspirator tunnel by providing for a double-flared deflection electrode, and by providing a flat air reentrance surface, makes ink stream viewing at the charge electrode simpler. Moreover, additional sealing means between the ink stream head and aspirator proper (two versions) as well as critical ink stream adjustment by head orientation relative to the aspirator body are provided.

Turning first to Figs. 1 and 2, an ink jet printer head assembly 10, comprising an ink jet head 11, which is connected in a manner which is explained more fully hereinafter to an aspirator body portion 20, is illustrated therein. The ink jet printer head 11 is connected to, and forms part of, a hemispherical dish 12 which rides on a hemispherical surface 13 associated with the body portion 20 of the aspirator. The assembly 10 is connected to a base member 21 which rests upon the carrier which effects translation of the assembly 10 along a print line substantially parallel to a print medium such as paper (not shown). The aspirator body portion 20 includes a tunnel like structure 22 therein having a hollow circumferentially extending chamber 23 surrounding the tunnel portion 22. Air enters an air inlet 24, passes into the chamber 23 and through a foraminous screen 25 for entry of the same into the bore 22a of the tunnel 22 so that air and ink travel co-extensively through the bore 22a of the tunnel.

Ink is applied to the head 11 under pressure, and a piezoelectric crystal (not shown) perturbates the ink causing the pressurized ink stream, which emanates from a nozzle 14 of the head 11 to break up into ink drops. Connected to the head just forward of the nozzle is a charge electrode 15 which effects charging of the ink droplets to some predetermined varying level to vary the height of impingement of the ink droplets upon the print-receiving medium.

In order to effect deflection of those ink drops which are charged and are passing through the bore 22a of the tunnel 22, deflection electrodes 26 and 27 are embedded in the upper and lower walls of the bore 22a so as to effect a deflection of the charged droplets in proportion to the charge thereon. As illustrated in Fig. 2, a gutter assembly 28 serves to receive uncharged drops to provide for ink recirculation.

In aspirated ink jet printers such as disclosed in U.S. Patent 4,097,872, the tunnel bore 22a is asymmetric. During start up of the system, it is con...