Process for the manufacture of electrophoretic displays
View Patent ↗This invention relates to a process for the manufacture of a multi-color electrophoretic display involving adding colorant solutions or dispersions of different colors and charged pigment particles in separate steps. The process comprises a first step of pattern-wise filling colorant solutions or dispersions into microcups in predetermined areas, followed by a step of pattern-wise or non-pattern-wise adding an electrophoretic fluid comprising charged pigment particles dispersed in a dielectric solvent or solvent mixture into the microcups which are pre-filled with the colorants.
1. A process for manufacturing an electrophoretic display, comprising the following steps in sequence:
(i) pattern-wise filling microcups by ink jet printing with colorant solutions or dispersions of different colors, each of said colorant solutions or dispersions comprising a carrier solvent,
(ii) removing said carrier solvent in said colorant solutions or dispersions,
(iii) non-pattern-wise filling the microcups with an electrophoretic fluid comprising charged pigment particles dispersed in a dielectric solvent or solvent mixture.
2. The process of claim 1 , wherein said inkjet printing is carried out with a printer head comprising multiple nozzles.
3. The process of claim 1 , wherein said colorant solution or dispersion comprises a dye or pigment.
4. The process of claim 1 wherein said colorant solution or dispersion is colorless.
5. The process of claim 1 , wherein said colorant solution or dispersion further comprises a surfactant, dispersant or viscosity modifier.
6. The process of claim 1 , wherein said carrier solvent is a dielectric solvent or solvent mixture.
7. The process of claim 1 , wherein said carrier solvent is a common solvent or solvent mixture.
8. The process of claim 7 , wherein said common solvent or solvent mixture is selected from the group consisting of hydrocarbons, alkyl ketones, alkyl esters, alcohols, ethers, water and mixtures thereof.
9. The process of claim 1 , wherein said electrophoretic fluid comprises charged pigment particles of the same color in a dielectric solvent or solvent mixture.
10. The process of claim 1 , wherein said electrophoretic fluid comprises charged pigment particles of different colors in a dielectric solvent or solvent mixture.
11. The process of claim 1 , further comprising top-sealing of the filled microcups with a sealing composition having a specific gravity no greater than that of the electrophoretic fluid.
12. The process of claim 1 , further comprising top-sealing of the filled microcups with a sealing composition which is hardened in situ.
13. The process of claim 1 , wherein said step (i) of filling is carried out in sections and each of said sections has a color system of two or more colors.
14. The process of claim 13 , wherein said color system has two colors.
15. The process of claim 1 , wherein said carrier solvent is dried off in step (ii).
16. The process of claim 1 , wherein the colorants are soluble or dispersible in the dielectric solvent or solvent mixture.