ELECTRO-OPTIC MEDIA AND WRITABLE DISPLAY INCORPORATING THE SAME

• US 20200133089A1
• Filed: 10/28/2019
• Published: 04/30/2020
• Est. Priority Date: 10/30/2018
• Status: Active Grant

• Current Assignee: E Ink Holdings Incorporated
• Original Assignee: E Ink Holdings Incorporated
• Inventors: MCCREARY, Michael D., PAOLINI, Jr., Richard J., TELFER, Stephen J., MORRILL, Samantha
• Granted Patent: US 11,513,413 B2
• Time in Patent Office: Days
• CPC Class Codes: B32B 17/10522 Electrophoretic layer
• CPC Class Codes: G02F 1/0027 Ferro-electric materials
• CPC Class Codes: G02F 1/167 by electrophoresis
• CPC Class Codes: G02F 1/1673 by magnetophoresis
• CPC Class Codes: G02F 2001/1678 characterised by the composition or particle type
• CPC Class Codes: G06F 3/03545 Pens or stylus

Abstract

An electro-optic device comprising electrophoretic medium including a dispersion of a plurality of particles in a fluid configured to migrate within the fluid in a direction responsive to an applied electric field. The plurality of particles include a first type of particles having a first charge of a first charge polarity, a second type of particles having a second charge of a second charge polarity, and a third type of particles having a third charge of the second charge polarity. The first charge polarity is opposite to the second charge polarity, and the third type of particles are configured to migrate within the fluid in a direction responsive to an applied magnetic field gradient.

Claims

1. An electro-optic device comprising:

a first surface on a viewing side;

a second surface on the opposite side of the first surface;

an electrophoretic medium disposed between a light-transmissive electrically conductive layer and an array of pixel electrodes and comprising a plurality of particles in a fluid, the plurality of particles comprising;

a first type of particles having a first color, a first charge of a first charge polarity;

a second type of particles having a second color, a second charge of a second charge polarity; and

a third type of particles having a third color, a third charge of the second charge polarity;

wherein the first, second and third colors are different from one another;

the first charge polarity is opposite to the second charge polarity;

the plurality of particles are configured to migrate within the fluid in a direction responsive to an applied electric field;

the third type of particles are configured to migrate within the fluid in a direction responsive to an applied magnetic field gradient;

the second type of particles have an electric field threshold, such that;

(a) application of a voltage potential difference between the light-transmissive electrically conductive layer and a pixel electrode to generate an electric field stronger than the electric field threshold and having a polarity driving the second type of particles adjacent to the light-transmissive electrically conductive layer, will cause a pixel corresponding to the pixel electrode to display the second color at the first surface;

(b) application of a voltage potential difference between the light-transmissive electrically conductive layer and a pixel electrode to generate an electric field stronger than the electric field threshold and having a polarity driving the first type of particles adjacent to the light-transmissive electrically conductive layer, will cause a pixel corresponding to the pixel electrode to display the first color at the first surface;

(c) once the first color is displayed at the first surface, application of a voltage potential difference between the light-transmissive electrically conductive layer and a pixel electrode to generate an electric field weaker than the electric field threshold and having a polarity driving the third type of particles adjacent to the light-transmissive electrically conductive layer, will cause a pixel corresponding to the pixel electrode to display the third color.

2. The electro-optic device of claim 1, wherein the second type of particles are not responsive to a magnetic field gradient. The electro-optic device of claim 1, wherein the first color is white.

5. The electro-optic device of claim 1, wherein the average diameter of the third type of particles is larger than the average diameter of the second type of particles.

6. The electro-optic device of claim 1, wherein the fluid is a non-polar solvent.

7. The electro-optic device of claim 1, in combination with a touch sensor anti a digitizer.

8. The electro-optic device of claim 7 in combination with a stylus.

9. The electro-optic device and stylus of claim 8, wherein the stylus comprises a magnetic material proximate to a first tip of the stylus.

10. The electro-optic device and stylus of claim 9 further comprising a second stylus having a non-magnetic tip.

11. The electro-optic device and stylus of claim 10, wherein the stylus comprises a second non-magnetic tip on an opposing end of the stylus relative to the first tip.

12. The electro-optic device and stylus of claim 11, wherein the device is configured to display at least one color when the non-magnetic tip contacts a surface of the display.

13. The electro-optic device and stylus of claim 12, wherein the device is configured to display at least two colors.

14. A method of operating an electro-optic device according to claim 1 comprising the steps of:

contacting a first location on the first surface of the device with one of a first and second stylus;

applying an electric field to cause one of the first type and second type of particles to migrate towards the first location;

contacting a second location on the first surface of the display with one of the first and second stylus; and

applying a magnetic field gradient to cause the third type of particles to migrate towards the second location.

15. A method of operating an electro-optic device according to claim 8 comprising the steps of:

contacting a first location on the first surface of the device with the stylus comprising a magnetic tip to cause the third type of particles to migrate towards the first location;

contacting again the first location on the first surface of the device with the stylus comprising a magnetic tip to cause a second type of particles to migrate towards the first location.

4. The electro-optic device of claim 3, wherein the second color is black.

16. A method of operating an electro-optic device, wherein the electro-optic device comprises (a) a first surface on a viewing side;

(b) a second surface on the opposite side of the first surface;

(c) art electrophoretic medium disposed between a light-transmissive electrically conductive layer and an array of pixel electrodes and comprising a plurality of particles in a fluid, the plurality of particles comprising

(1) a first type of particles having a first color, a first charge of a first charge polarity;

(2) a second type of particles having a second color, a second charge of a second charge polarity; and

(3) a third type of particles having a third color, a third charge of the second charge polarity;

wherein the first, second and third colors are different from one another;

wherein the first charge polarity is opposite to the second charge polarity;

wherein the plurality of particles are configured to migrate within the fluid in a direction responsive to an applied electric field; and

wherein the third type of particles are configured to migrate within the fluid in a direction responsive to an applied magnetic field gradient;

comprising the steps of;

contacting a first location on a first surface of the device with a stylus comprising a magnetic tip to cause a third type of particles to migrate towards the first location;

contacting again the first location on the first surface of the device with the stylus comprising a magnetic tip to cause a second type of particles to migrate towards the first location.