Apparatus and method for characterizing electrophoretic display mediums
AssigneeXerox Corporation
InventorsNaveen Chopra, Man-Chung Tam, Gaetano J. Lavigne, Peter M. Kazmaier
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Abstract
A method and an apparatus for measuring reflectivity, charge and/or particle mobility of electrophoretic display mediums and particles are described. The apparatus for evaluating characteristics of an electrophoretic display medium, comprising a cell for containing the electrophoretic display medium, located between conductive substrates, a voltage application unit associated with the cell, an electrometer to measure transient current, and a densitometer to measure reflectance.
Claims9
A method of determining characteristics of an electrophoretic display medium, comprising:
- arranging the electrophoretic display medium in a cell located between conductive substrates,
- changing between a rectangular or triangular waveform to apply switching voltage to the electrophoretic display medium in the cell, and
- measuring at least reflectance of the electrophoretic display medium and transient current of the electrophoretic display medium,
- when selecting the rectangular waveform to apply switching voltage, characteristics of the electrophoretic display medium determined consist of white reflectance, black reflectance, contrast ratio, switching voltage, switching time, switching voltage threshold, mobility of particles, and charge of particles, and
- when selecting the triangular waveform to apply switching voltage, characteristics of the electrophoretic display medium determined consist of white reflectance, black reflectance, contrast ratio, mobility of particles, charge of particles, and charge distribution.
A method of making electrophoretic display devices, comprising:
- preparing a first electrophoretic display medium comprising at least one set of colored particles dispersed in a dielectric liquid substantially free of charge control additives,
- arranging the first electrophoretic display medium in a cell located between conductive substrates,
- changing between a rectangular or triangular waveform to apply switching voltage to the first electrophoretic display medium in the cell,
- measuring at least reflectance of the first electrophoretic display medium and transient current of the first electrophoretic display medium, and
- preparing a second electrophoretic display medium to have substantially the same reflectance and transient current, wherein
- when selecting the rectangular waveform to apply switching voltage, characteristics of the electrophoretic display medium determined consist of white reflectance, black reflectance, contrast ratio, switching voltage, switching time, switching voltage threshold, mobility of particles, and charge of the particles and
- when selecting the triangular waveform to apply switching voltage, characteristics of the electrophoretic display medium determined consist of white reflectance, black reflectance, contrast ratio, mobility of particles, charge of particles, and charge distribution.
Dependencies are inferred from the claim text.