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Electrostatic Charging Structure

IP.com Disclosure Number: IPCOM000052098D
Original Publication Date: 1981-Apr-01
Included in the Prior Art Database: 2005-Feb-11
Document File: 2 page(s) / 31K

Publishing Venue

IBM

Related People

Bogardus, EH: AUTHOR [+3]

Abstract

Generally, in ink jet charging schemes, a single electrode, positioned at the jet's break-off point, is used for charging selected droplets. As set forth herein, droplet charging is accomplished by electrostatic induction through the application of a potential difference between the electrode and the ink reservoir (the head). The required charge flows through the continuous jet so that when a droplet breaks off it carries with it a charge proportional to the applied voltage.

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Electrostatic Charging Structure

Generally, in ink jet charging schemes, a single electrode, positioned at the jet's break-off point, is used for charging selected droplets. As set forth herein, droplet charging is accomplished by electrostatic induction through the application of a potential difference between the electrode and the ink reservoir (the head). The required charge flows through the continuous jet so that when a droplet breaks off it carries with it a charge proportional to the applied voltage.

The ink jet charging is accomplished through the use of a two-electrode structure, fabricated directly on the nozzle exit surface. The electrode structure consists of an insulating layer 2 (say, 1 Mu m thick) sandwiched between two aperture-type metallic electrodes 4 and 6. The structure is sputtered directly on the exit surface of a nozzle 8 through the use of appropriate masks.

Operation of this charging scheme is based on the electrochemical properties of electrolytic solutions in contact with solid surfaces, i.e., the electrochemical double layer. Consequently, the ink column 10 inside the nozzle (and also the jet) has a net ionic charge at its interface. This surface charge 12 strongly interacts with the axial electric field 14 created by the two-electrode structure. As the column of ink 10 is forced to move due to external pressure and just at the nozzle exit, it experiences the strong electrode field 14. The aforementioned charge can be enhanced or reta...