Color display device and driving methods therefor
AssigneeE Ink California, LLC
InventorCraig Lin
Life of this patent
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Abstract
The invention relates to electrophoretic layers containing at least five different particles, and to driving methods for displaying at least five, and in some embodiments, six different colors at each pixel or sub-pixel. The electrophoretic layers may also contain uncharged neutral buoyancy particles, and the driving methods may include special shaking waveform sequences.
Claims20
A display layer having a first, viewing surface and a second surface on the opposed side of the display layer from the first surface, the display layer further comprising an electrophoretic medium comprising a fluid and first, second, third, fourth and fifth types of particles dispersed in the fluid, the first, second, third, fourth and fifth types of particles having respectively first, second, third, fourth and fifth optical characteristics differing from one another, the first, third and fourth types of particles having charges of one polarity and the second and fifth types of particles having charges of the opposite polarity, the first type of particles having a greater zeta potential or electrophoretic mobility than the third type of particles, the third type of particles having a greater zeta potential or electrophoretic mobility than the fourth type of particles, and the second type of particles having a greater zeta potential or electrophoretic mobility than the fifth type of particles.
A method of driving a display layer having a first, viewing surface and a second surface on the opposed side of the display layer from the first surface, the display layer being provided with means for applying an electric field between the first and second surfaces, the display layer further comprising an electrophoretic medium comprising a fluid and first, second, third, fourth and fifth types of particles dispersed in the fluid, the first, second, third, fourth and fifth types of particles having respectively first, second, third, fourth and fifth optical characteristics differing from one another, the first, third and fourth type of particles having charges of one polarity and the second and fifth types of particles having charges of the opposite polarity, the method comprising:
- (i) applying a first electric field for a period sufficient to cause the optical characteristic of one of the first or second particles to be displayed at the viewing surface;
- (ii) thereafter, applying a second electric field having a polarity opposite to that of the first electric field for a period insufficient to cause the optical characteristic of the other of the first or second particles to be displayed at the viewing surface;
- and
- (iii) thereafter, applying a shaking waveform.
A driving method for an electrophoretic display comprising a first surface on the viewing side, a second surface on the non-viewing side and an electrophoretic fluid which fluid is sandwiched between a common electrode and a layer of pixel electrodes and comprises a first type of particles, a second type of particles, a third type of particles, a fourth type of particles and a fifth type of particles, all of which are dispersed in a solvent or solvent mixture, wherein:
- (a) the five types of pigment particles have optical characteristics differing from one another;
- (b) the first and second types of particles carry opposite charge polarities;
- (c) the third and fourth types of particles carry the same charge polarity as the first type of particles, and the first type, the third type and the fourth type of particles have progressively lower magnitudes;
- and
- (d) the fifth type of particles carries the same charge polarity as the second type of particles but its magnitude is lower than that of the second type of particles, the method comprising any one or more of (A)-(I) below:
- (A)(i) applying a first driving voltage to a pixel of the electrophoretic display for a first period of time, wherein the first driving voltage has the same polarity as the first type of particles and the first period of time is sufficient to drive the pixel to the color state of the first type of particles to appear at the viewing side, or
- (ii) applying a second driving voltage to a pixel of the electrophoretic display for a second period of time, wherein the second driving voltage has the same polarity as the second type of particles and the second period of time is sufficient to drive the pixel to the color state of the second type of particles to appear at the viewing side;
- (B)(i) driving a pixel of the electrophoretic display to the color of the second type of particles;
- and
- (ii) applying a low driving voltage for a period of time, wherein the low driving voltage has the same polarity as the fourth type of particles and the period of time is sufficient to drive the pixel from the color state of the second type of particles to the color state of the fourth type of particles to appear at the viewing side;
- (C)(i) applying a first driving voltage to a pixel of the electrophoretic display for a first period of time to drive the pixel towards the color state of the second type of particles;
- (ii) applying a second driving voltage to the pixel for a second period of time, wherein the second driving voltage has same polarity as the fourth type of particles and a magnitude lower than that of the first driving voltage, to drive the pixel from the color state of the second type of particles towards the color state of the fourth type of particles to appear at the viewing side;
- and
- repeating steps (i) and (ii);
- (D)(i) applying a first driving voltage to a pixel of the electrophoretic display for a first period of time to drive the pixel towards the color state of the second type of particles;
- (ii) applying a second driving voltage to the pixel for a second period of time, wherein the second driving voltage has same polarity as the fourth type of particles and a magnitude lower than that of the first driving voltage, to drive the pixel from the color state of the second type of particles towards the color state of the fourth type of particles to appear at the viewing side;
- (iii) applying no driving voltage to the pixel for a third period of time;
- and
- repeating steps (i)-(iii);
- (E) (i) applying a first driving voltage to a pixel in the electrophoretic display for a first period of time to drive the pixel towards the color state of the second type of particles;
- (ii) applying no driving voltage to the pixel for a second period of time;
- (iii) applying a second driving voltage to the pixel for a third period of time, wherein the second driving voltage has the same polarity as the fourth type of particles and has a magnitude lower than that of the first driving voltage, to drive the pixel from the color state of the second type of particles towards the color state of the fourth type of particles to appear at the viewing side;
- (iv) applying no driving voltage to the pixel for a fourth period of time;
- and
- repeating steps (i)-(iv);
- (F) (i) applying a first driving voltage to a pixel of the electrophoretic display for a first period of time to drive the pixel towards the color state of the first type of particles;
- (ii) applying a second driving voltage to the pixel for a second period of time, wherein the second driving voltage has same polarity as the fifth type of particles and a magnitude lower than that of the first driving voltage, to drive the pixel from the color state of the first type of particles towards the color state of the fifth type of particles to appear at the viewing side;
- and
- repeating steps (i) and (ii);
- (G)(i) applying a first driving voltage to a pixel of the electrophoretic display for a first period of time to drive the pixel towards the color state of the first type of particles;
- (ii) applying a second driving voltage to the pixel for a second period of time, wherein the second driving voltage has same polarity as the fifth type of particles and a magnitude lower than that of the first driving voltage, to drive the pixel from the color state of the first type of particles towards the color state of the fifth type of particles to appear at the viewing side;
- (iii) applying no driving voltage to the pixel for a third period of time;
- and
- repeating steps (i)-(iii);
- (H)(i) applying a first driving voltage to a pixel in the electrophoretic display for a first period of time to drive the pixel towards the color state of the first type of particles;
- (ii) applying no driving voltage to the pixel for a second period of time;
- (iii) applying a second driving voltage to the pixel for a third period of time, wherein the second driving voltage has the same polarity as the fifth type of particles and has a magnitude lower than that of the first driving voltage, to drive the pixel from the color state of the first type of particles towards the color state of the fifth type of particles to appear at the viewing side;
- (iv) applying no driving voltage to the pixel for a fourth period of time;
- and
- repeating steps (i)-(iv);
- and
- (I) the method comprises applying a driving voltage or a pulsing waveform with alternating a driving voltage and no driving voltage, to a pixel of the electrophoretic display, wherein the pixel is in the color state of the fifth type of particles and the driving voltage has the same polarity as the third type of particles, to drive the pixel from the color state of the fifth type of particles towards the color state of the third type of particles to appear at the viewing side.
A driving method for an electrophoretic display comprising a first surface on the viewing side, a second surface on the non-viewing side and an electrophoretic fluid which fluid is sandwiched between a common electrode and a layer of pixel electrodes and comprises a first type of particles, a second type of particles, a third type of particles, a fourth type of particles, a fifth type of particles and a sixth type of particles, all of which are dispersed in a solvent or solvent mixture, wherein:
- (a) the six types of pigment particles have optical characteristics differing from one another;
- (b) the first type, the third type and the fifth type are high positive particles, mid-positive particles and low positive particles, respectively;
- and
- (c) the second type, the fourth type and the sixth type are high negative, mid-negative and low negative particles, respectively,
- the method comprises applying a driving voltage or a pulsing waveform with alternating a driving voltage and no driving voltage, to a pixel of the electrophoretic display, wherein the pixel is in the color state of the fifth type of particles and the driving voltage has the same polarity as the fourth type of particles, to drive the pixel from the color state of the fifth type of particles towards the color state of the fourth type of particles to appear at the viewing side.
Dependencies are inferred from the claim text.