Droplet formation and dropping position control in electrostatic inkjet phenomena

A preliminary investigation was conducted on formation and control of micro droplet in electrostatic Inkjet phenomena. High voltage was applied between an insulative capillary tube filled with ion-conductive water and a plate electrode. At the beginning of corona discharge, a Taylor cone was formed at the tip of the tube and the top of the cone was broken to form a very small droplet that was dispersed like mist at wide angle due to the Coulomb repulsive force of charged mist. When the applied voltage was further increased, water droplet was formed periodically. The charge to mass ratio of the droplet was measured and compared with the Rayleigh's limit. It was less than the limit because the droplet vibrated at the formation of the droplet. Another experimental set-up was constructed to control the dropping position of the droplet. A ring electrode was settled between the capillary tube and the plate electrode to control the dropping position of the droplet.