Electronic display ink having inert pigment particles

• Main Author: Morrison, Ian D
• Format: Patent
• Language: English
• Published: 02.06.2020
• Subjects: DEVICES OR ARRANGEMENTS, THE OPTICAL OPERATION OF WHICH ISMODIFIED BY CHANGING THE OPTICAL PROPERTIES OF THE MEDIUM OF THEDEVICES OR ARRANGEMENTS FOR THE CONTROL OF THE INTENSITY,COLOUR, PHASE, POLARISATION OR DIRECTION OF LIGHT, e.g.SWITCHING, GATING, MODULATING OR DEMODULATING; FREQUENCY-CHANGING; NON-LINEAR OPTICS; OPTICAL ANALOGUE/DIGITAL CONVERTERS; OPTICAL LOGIC ELEMENTS; OPTICS; PHYSICS; TECHNIQUES OR PROCEDURES FOR THE OPERATION THEREOF

The ink of the present invention is an oil dispersion of pigment particles. The pigment particles are designed to have no or insignificant response to applied electric fields. The ink comprises a carrier liquid having a concentration of pigment particles disposed in the carrier liquid. A surfactant is included in the carrier liquid, wherein the surfactant is adsorbed on the pigment particles only when activated. The pigment particles having adsorbed the surfactant do not generate a reactive level of particle charge so that the pigment particles move with and not independently from the carrier liquid under an applied electrical field. The surfactant is activated by the application of at least one of heat and solvent to the carrier liquid so that the surfactant molecules adsorb onto the pigment particles.