Driving sequences for reducing image ghosting in multi-particle electrophoretic displays
OwnerChih-Yu CHENG, Ning-Wei JAN +3inventors
InventorsChih-Yu CHENG, Ning-Wei JAN, Jing-Po TSAO, Chen-Kai CHIU, Craig LIN
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Abstract
Multi-particle electrophoretic displays, including three and four-particle displays, and methods of driving such displays with waveforms having shaking pulses configured to reduce or eliminate image ghosting.
Claims20
A method of driving an electrophoretic display layer to desired optical states with reduced image ghosting, the electrophoretic display layer being disposed between a viewing surface including a light-transmissive electrode layer and a second opposite surface including a driving electrode layer, the display layer including an electrophoretic medium comprising a non-polar fluid and at least three types of particles dispersed in the non-polar fluid, the at least three types of particles having different optical characteristics from one another, the method comprising the following steps for each pixel of the electrophoretic display layer:
- (a) applying a shaking voltage pulse sequence to a pixel for a first period of time to promote mixing of the at least three types of particles dispersed in the non-polar fluid, the shaking voltage pulse sequence comprising, in order, a first series of shaking voltage pulses, a second series of shaking voltage pulses, a third series of shaking voltage pulses, and a fourth series of shaking voltage pulses, wherein each series of shaking voltage pulses comprises alternating positive and negative voltage pulses repeated a plurality of times, and wherein the voltage pulses of the second and third series have the same frequency, the voltage pulses of the fourth series have a lower frequency than the voltage pulses of the second and third series, and the first, second, third, and fourth series of shaking voltage pulses are separated by either (i) a single separation voltage pulse having an amplitude equal to amplitudes of the shaking voltage pulses of each series of shaking voltage pulses and a pulse width greater than any of the shaking voltage pulses of each series of shaking voltage pulses or (ii) a series of separation voltage pulses having a frequency greater than the shaking voltage pulses of any of the series of shaking voltage pulses;
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- (b) applying a push-pull voltage pulse sequence to the pixel for a second period of time following the first period of time to drive the pixel to a targeted color state at the viewing side of the display layer.
An electrophoretic display device, comprising:
- an electrophoretic display layer disposed between a viewing surface including a light-transmissive electrode layer and a second opposite surface including a driving electrode layer, the display layer including an electrophoretic medium comprising a non-polar fluid and at least three types of particles dispersed in the non-polar fluid, the at least three types of particles having different optical characteristics from one another;
- a memory storing a set of waveforms for driving each pixel of the electrophoretic display layer to a targeted color state, each of the set of waveforms comprising a shaking voltage pulse sequence to be applied for a first period of time to promote mixing of the at least three types of particles dispersed in the non-polar fluid followed by a push-pull voltage pulse sequence to be applied for a second period of time to drive the pixel to the targeted color state, each shaking voltage pulse sequence comprising, in order, a first series of shaking voltage pulses, a second series of shaking voltage pulses, a third series of shaking voltage pulses, and a fourth series of shaking voltage pulses, wherein each series of shaking voltage pulses comprises alternating positive and negative voltage pulses repeated a plurality of times, and wherein the voltage pulses of the second and third series have the same frequency, the voltage pulses of the fourth series have a lower frequency than the voltage pulses of the second and third series, and the first, second, third, and fourth series of shaking voltage pulses are separated by either (i) a single separation voltage pulse having an amplitude equal to amplitudes of the shaking voltage pulses of each series of shaking voltage pulses and a pulse width greater than any of the shaking voltage pulses of each series of shaking voltage pulses or (ii) a series of separation voltage pulses having a frequency greater than the shaking voltage pulses of any of the series of shaking voltage pulses;
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- a processor for selecting a waveform from the set of waveforms appropriate for driving each pixel to a desired color state and applying the waveform to the pixel.
Dependencies are inferred from the claim text.