Research Laboratories of Australia Pty Ltd.

Blair D Howell

Terence M Lawson

A method for pressure induced development of electrostatic latent images comprising forming an electrostatic latent image on a support member and subsequently placing the image bearing surface of the member in face contact with a receiving sheet, applying a dispersion to at least one of the contacting surfaces in a first state wherein the flow properties of the dispersion are non-Newtonian and the dispersion consists of a liquid phase and of a solid phase comprising flocculated electroscopic marking particles forming a matrix sufficiently strong to prevent extraction of individual electroscopic marking particles from the matrix by electrostatic attraction, using a pressure roller to apply to the dispersion a shear stress of sufficient magnitude to convert the dispersion to a second state wherein the flow properties of the dispersion become Newtonian and the solid phase is deflocculated in the liquid phase to allow individual electroscopic marking particles to deposit in accordance with the latent image, and separating the support member and the sheet whereby an image deposit is produced on the member and the sheet.

Pressure induced development of electrostatic latent images

The method of developing an electrostatic latent image contained on a surface comprising the steps of applying to a surface a dispersion in a first state wherein the flow properties of the dispersion are non-Newtonian and wherein the dispersion consists of a liquid phase and of a solid phase comprising flocculated electroscopic marking particles forming a matrix sufficiently strong to prevent extraction of individual electroscopic marking particles from the matrix and applying to the dispersion a shear stress of sufficient magnitude to convert the dispersion from the first state to a second state wherein the flow properties of said dispersion become Newtonian and wherein said solid phase is deflocculated.

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Lockleys, Australia

Blair D Howell