Driving sequences for reducing image ghosting in multi-particle electrophoretic displays
AssigneeE Ink Corporation
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 first series have a higher frequency than the voltage pulses of the second and third series, and the voltage pulses of the fourth series have a lower frequency than the voltage pulses of the second and third series;
- and
- (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 first series have a higher frequency than the voltage pulses of the second and third series, and the voltage pulses of the fourth series have a lower frequency than the voltage pulses of the second and third series;
- and
- 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.
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 driving each pixel of the electrophoretic display layer to a targeted color state:
- (a) selecting a waveform for driving a pixel to a targeted color state from a set of waveforms stored in a memory each for driving a pixel to a different 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 a targeted color state, wherein at least two of the waveforms in the set of waveforms have different shaking voltage pulse sequences, the shaking voltage pulse sequence for each waveform configured to reduce image ghosting in the targeted color state produced by the subsequent push-pull voltage pulse sequence in the waveform;
- and
- (b) applying the waveform selected in step (a) to drive the pixel to the targeted color state.
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 waveform in 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 subsequent period of time to drive the pixel to a targeted color state, wherein at least two of the waveforms in the set of waveforms have different shaking voltage pulse sequences, the shaking voltage pulse sequence for each waveform configured to reduce image ghosting in the targeted color state produced by the subsequent push-pull voltage pulse sequence in the waveform;
- and
- 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.