Driving methods for tir-based image displays
AssigneeConcord (Hk) International Education Limited
InventorsThomas JOHANSSON, Vivek PORUSH, 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.
Claims18
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 method comprising:
- applying a first waveform comprising a first drive voltage applied for a first duration to cause movement of the electrophoretically mobile particle from the front electrode towards the rear electrode;
- and
- applying a second waveform comprising a second drive voltage applied for a second duration to cause movement of the electrophoretically mobile particle from the rear electrode towards the front electrode;
- wherein a mean amplitude of the first and second waveforms is approximately zero.
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 method comprising:
- applying a first waveform comprising a first drive voltage applied for a first duration to cause movement of the electrophoretically mobile particle from the front electrode towards the rear electrode;
- applying a second waveform comprising a second drive voltage applied for a second duration to cause movement of the electrophoretically mobile particle from the rear electrode towards the front electrode;
- and
- applying a third waveform comprising a third drive voltage applied for a third duration to cause movement of the electrophoretically mobile particle from the front electrode back towards the rear electrode,
- wherein a mean amplitude of the first, second, and third waveforms is approximately zero.
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 method comprising:
- driving the electrophoretically mobile particle to a target electrode by applying a first waveform comprising a first drive voltage applied for a first duration;
- and
- holding the electrophoretically mobile particle at the target electrode by applying a second waveform comprising a second drive voltage applied for a second duration to maintain the electrophoretically mobile particle at the target electrode,
- wherein the second drive voltage is more than 0V but less than the first drive voltage.
A method to control movement of an electrophoretically mobile particle in a medium interposed between a front electrode and a arear electrode of a total internal reflection (TIR) display, the method comprising:
- driving the electrophoretically mobile particle to a target electrode by applying a first waveform comprising a first drive voltage applied for a first duration;
- and
- holding the electrophoretically mobile particle at the target electrode by applying a second waveform comprising a series of drive voltages applied over a second duration to maintain the electrophoretically mobile particle at the target electrode, wherein
- the series of drive voltages alternate between a second drive voltage and a third drive voltage,
- the second drive voltage is less than the first drive voltage but more than 0V, and
- the third drive voltage is approximately 0V.
Dependencies are inferred from the claim text.