Electro-optic displays, and processes for the production thereof

• US 9,470,950 B2
• Filed: 11/06/2015
• Issued: 10/18/2016
• Est. Priority Date: 06/10/2002
• Status: Expired due to Term

• Current Assignee: E Ink Holdings Incorporated
• Original Assignee: E Ink Holdings Incorporated
• Inventors: Paolini, Richard J. Jr., Whitesides, Thomas Henry
• Primary Examiner(s): PINKNEY, DAWAYNE
• Application Number:
  US14/934,872
• Publication Number:
  US 20160062206A1
• Time in Patent Office: 347 Days
• Field of Search: 359/296, 359265-277, 359245-247, 359/254, 359/242, 430 31- 32, 345/107, 345/49, 345/105, 438/929, 349/33
• US Class Current: 1/1
• CPC Class Codes: B29C 65/02 by heating, with or without pressure
• CPC Class Codes: B29C 66/45 Joining of substantially the whole surface of the articles methods or apparatus for laminating B32B37/00
• CPC Class Codes: B29C 66/71 characterised by the composition of the plastics material of the parts to be joined welding bar compositions B29C65/125
• CPC Class Codes: B29C 66/7314 Electrical and dielectric properties
• CPC Class Codes: B29K 2675/00 Use of PU, i.e. polyureas or polyurethanes or derivatives thereof, for preformed parts, e.g. for inserts
• CPC Class Codes: B29L 2031/3475 Displays, monitors, TV-sets, computer screens
• CPC Class Codes: B32B 2037/0092 in which absence of adhesives is explicitly presented as an advantage
• CPC Class Codes: B32B 2375/00 Polyureas; Polyurethanes
• CPC Class Codes: B32B 2457/20 Displays, e.g. liquid crystal displays, plasma displays
• CPC Class Codes: B32B 37/04 characterised by the partial melting of at least one layer
• CPC Class Codes: B32B 37/16 with all layers existing as coherent layers before laminating
• CPC Class Codes: B32B 37/26 with at least one layer which influences the bonding during the lamination process, e.g. release layers or pressure equalising layers
• CPC Class Codes: B32B 38/10 Removing layers, or parts of layers, mechanically or chemically
• CPC Class Codes: G02F 1/1508 using a solid electrolyte
• CPC Class Codes: G02F 1/167 by electrophoresis
• CPC Class Codes: G02F 1/1677 Structural association of cells with optical devices, e.g. reflectors or illuminating devices
• CPC Class Codes: G02F 1/1681 having two or more microcells partitioned by walls, e.g. of microcup type
• CPC Class Codes: G02F 1/172 based on a suspension of orientable dipolar particles, e.g. suspended particles displays
• CPC Class Codes: G02F 2001/1678 characterised by the composition or particle type
• CPC Class Codes: G02F 2202/022 polymeric

Abstract

An assembly useful for producing an encapsulated electrophoretic display is prepared from an electrophoretic medium comprising a plurality of discrete droplets (904) in a polymeric binder (906), each droplet comprising a plurality of charged particles dispersed in a fluid, and a front sub-assembly comprising a light-transmissive electrically-conductive layer (902) and a color filter array (920). The electrophoretic medium is laminated to the front-assembly (902, 920) at a temperature at which the polymeric binder (906) will flow and secure the electrophoretic medium to the front sub-assembly to form the final assembly, with the light-transmissive electrically-conductive layer (902) disposed between the color filter array (920) and the electrophoretic medium (904, 906).

Claims

1. A process for producing an assembly useful in the production of an encapsulated electrophoretic display, the process comprising:

providing an electrophoretic medium comprising a plurality of discrete droplets in a polymeric binder, each droplet comprising a plurality of charged particles dispersed in a suspending fluid and capable of moving therethrough on application of an electric field to the suspending fluid;

providing a front sub-assembly comprising a light-transmissive electrically-conductive layer and a color filter array; and

laminating the electrophoretic medium to the front-assembly at a temperature at which the polymeric binder will flow, thereby causing the polymeric binder to flow and secure the electrophoretic medium to the front sub-assembly to form the assembly, with the light-transmissive electrically-conductive layer disposed between the color filter array and the electrophoretic medium.

2. A process according to claim 1 wherein each droplet is confined within a capsule wall separate from the polymeric binder.

3. A process according to claim 1 wherein the droplets form the discontinuous phase of a two-phase system and are surrounded by a continuous phase forming the polymeric binder.

4. A process according to claim 1 wherein the electrophoretic medium is provided with a release sheet covering its surface which will be laminated to the front sub-assembly, and the release sheet is removed prior to the lamination.

5. A process according to claim 1 further comprising laminating the assembly to a backplane comprising at least one electrode, thereby causing the polymeric binder to flow and secure the electrophoretic medium to the backplane.

6. A process according to claim 5 wherein the electrophoretic medium is provided with a release sheet covering its surface which is to be laminated to the backplane, and the release sheet is removed prior to the lamination.

7. A process according to claim 1 wherein the polymeric binder flows at a temperature of not more than about 150°

C.

8. A process according to claim 7 wherein the polymeric binder flows at a temperature of not more than about 100°

C.

9. A process according to claim 1 wherein the polymeric binder comprises from about 33 to about 67 percent of the electrophoretic layer.

10. A process according to claim 1 wherein, after the lamination, the polymeric binder is cured so that it no longer flows at a temperature of about 150°

C.

11. A process according to claim 1 wherein the polymeric binder comprises a polyurethane.

12. A process according to claim 5 wherein the backplane is an active matrix backplane comprising a plurality of pixel electrodes and at least one non-linear element associated with each pixel electrode.

13. An article of manufacture comprising, in order:

a color filter array;

a light-transmissive electrically-conductive layer;

an electrophoretic medium comprising a plurality of discrete droplets of electrophoretic medium in a polymeric binder, each droplet comprising a plurality of charged particles dispersed in a suspending fluid and capable of moving therethrough on application of an electric field to the suspending fluid, the polymeric binder flowing at a temperature of not more than about 150°

C.; and

a release sheet in contact with the polymeric binder.

14. A method for manufacturing a hybrid display, the method comprising:

(a) providing a front plane laminate comprising an electro-optic layer and a substrate, the front plane laminate having a first coefficient of thermal expansion (CTE);

(b) producing an electro-optic display by laminating the front plane laminate to a backplane comprising at least one electrode, the backplane having a second CTE;

(c) heating the display to a temperature above a threshold temperature, thereby producing a heated display with a curvature; and

(d) gradually lowering the temperature to an ambient temperature to release structural stress resulting from any differential expansion of the front plane laminate and the backplane such that the curvature is substantially reduced.