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Thursday, June 20, 2013

Electrophoretic image display (EPID)


The motion of charged particles of pigments suspended in a liquid under the influence of an electric field is known as Electrophoresis. Electrophoretic image displays use this phenomenon. The main parts of this display are dc voltage source, base plate, electrode segments, coloured liquid, transparent electrode and electrophoretic pigment particles. A liquid suspension consists of pigment particles are sandwiched between a pair of electrodes. One among the two electrodes is transparent and made as common electrode. On the application of dc electric field, pigment particles move electrophoretically towards electrodes and this motion is dependent on the polarity of the charge on the particles. The transparent electrode is preferably maintained at ground potential and segment electrodes at different potentials. Colour combinations of both the pigment particles and the suspending liquid can be used to achieve a desired colour display. Electrophoretic image displays are characterized by large character size, low power dissipation and internal memory. 

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