Driving methods for TIR-based image displays
AssigneeConcord (Hk) International Education Limited
InventorsVivek Porush, Thomas Johansson, Graham Beales, Peter T. Kazlas
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Abstract
Optical states in TIR-based image displays may be modulated by movement of electrophoretically mobile particles into and out of the evanescent wave region at the interface of a high refractive index convex protrusions and a low refractive index medium. The movement of particles into the evanescent wave region may frustrate TIR and form dark states at pixels. Movement of particles out of the evanescent wave region may allow for TIR of incident light to form bright states at pixels. The movement of the particles may be controlled by employing the drive methods of pulse width modulation, voltage modulation or a combination thereof.
Claims14
A method to control movement of an electrophoretically mobile particle in a medium interposed between a front electrode and a rear electrode of a total internal reflection (TIR) display, the front electrode having a plurality of semi-hemispherical protrusions, the method comprising:
- applying a first drive voltage to cause movement of the electrophoretically mobile particle from the front electrode towards the rear electrode for a first duration;
- holding the electrophoretically mobile particle proximate the rear electrode by applying a first waveform for a second duration;
- applying a second drive voltage to cause movement of the electrophoretically mobile particle from the rear electrode towards the front electrode for a third duration;
- and
- holding the electrophoretically mobile particle proximate the front electrode by applying a second waveform for a fourth duration;
- wherein the steps of applying the first drive voltage and the second drive voltage causes the electrophoretically mobile particle to move into and out of an evanescent wave region in the TIR display;
- and
- wherein the step of applying the first waveform holds the position of the electrophoretically mobile particle outside of the evanescent wave region and the step of applying the second waveform holds the position of the electrophoretically mobile particle within the evanescent wave region.
An apparatus controller to control movement of an electrophoretically mobile particle in a medium interposed between a front electrode and a rear electrode of a total internal reflection (TIR) display, the apparatus controller comprising:
- a processer;
- a memory in communication with the processor, the memory comprising instructions to cause the processor to:
- apply a first drive voltage to cause movement of the electrophoretically mobile particle from the front electrode towards the rear electrode for a first duration;
- hold the electrophoretically mobile particle in position by applying a first waveform for a second duration;
- apply a second drive voltage to cause movement of the electrophoretically mobile particle from the rear electrode towards the front electrode for a third duration;
- and
- hold the electrophoretically mobile particle in position by applying a second waveform for a fourth duration;
- wherein the front electrode includes a plurality of convex protrusions;
- wherein the processor applies the first drive voltage and the second drive voltage to move the electrophoretically mobile particle out of an evanescent wave region in a TIR-based display;
- and
- wherein the processor applies the first waveform to hold the position of the electrophoretically mobile particle outside of the evanescent wave region and the processor applies the second waveform to hold the position of the electrophoretically mobile particle within the evanescent wave region.
Dependencies are inferred from the claim text.