Electronic device with reduced-stress flexible display

Patent metadata

Field	Value
Publication number	US-9516743-B2
Application number	US-201313778932-A
Country	US
Kind code	B2
Filing date	Feb 27, 2013
Priority date	Feb 27, 2013
Publication date	Dec 6, 2016
Grant date	Dec 6, 2016

Abstract

An electronic device may have a flexible display. The display may have portions that are bent along a bend axis. The display may have display circuitry such as an array of display pixels in an active area and signal lines, thin-film transistor support circuitry and other display circuitry in an inactive area of the display surrounding the active area. The display circuitry may be formed on a substrate such as a flexible polymer substrate. The flexible polymer substrate may be formed by depositing polymer on a support structure that has raised portions. The raised portions may create locally thinned regions in the flexible polymer substrate. The reduced thickness of the flexible polymer substrate in the thinned regions may help ensure that a neutral stress plane that is associated with bending the display along the bend axis is aligned with the display circuitry, thereby minimizing stress in the display circuitry.

First claim

What is claimed is:

1. A display, comprising:
a display substrate having an active area, an inactive area, and a locally thinned region, wherein the locally thinned region is located in the inactive area;
an array of display pixels on the display substrate in the active area;
display circuitry including gate driver circuitry on the display substrate in the inactive area, wherein the gate driver circuitry overlaps the locally thinned region of the display substrate, wherein the display pixels lie in a plane, and wherein the locally thinned region of the display substrate curves out of the plane such that the inactive area is at least partially hidden from view by a user; and
an encapsulation layer formed over the gate driver circuitry such that a neutral stress plane intersects with and spans laterally across the entire width of the gate driver circuitry over the locally thinned region of the display substrate.

2. The display defined in claim 1 wherein the inactive area does not contain display pixels.

3. The display defined in claim 2 wherein the display circuitry includes a plurality of metal lines in the inactive area, wherein the metal lines overlap the locally thinned region, and wherein the metal lines curve with the locally thinned region.

4. The display defined in claim 3 wherein the metal lines include serpentine segments that curve with the locally thinned region of the display substrate.

5. The display defined in claim 1 wherein the display pixels comprise organic light-emitting diode display pixels.

6. The display defined in claim 1 wherein the display circuitry includes thin-film transistors.

7. The display defined in claim 1 wherein the display substrate comprises a polymer layer.

8. The display defined in claim 7 wherein the encapsulation layer comprises a polymer encapsulation layer on the display substrate.

9. The display defined in claim 8 wherein at least a portion of the neutral stress plane lies within the polymer encapsulation layer.

10. A method of forming a display, comprising:
depositing a polymer display substrate layer onto a support structure having raised areas so that the raised areas create recesses within the polymer display substrate layer and create corresponding locally thinned regions of the polymer display substrate layer that are thinned relative to an adjacent region of the polymer display substrate layer, wherein the polymer display substrate layer has a first thickness in the locally thinned regions and a second thickness in the adjacent region and wherein the first thickness is less than the second thickness;
forming an insulating layer above the polymer display substrate layer;
forming display circuitry including at least one thin-film transistor on the polymer display substrate layer that at least partly overlaps the locally thinned regions; and
forming an encapsulant layer over the display circuitry such that a neutral stress plane runs through the thin-film transistor where the thin-film transistor overlaps one of the locally thinned regions, wherein a thickness of the encapsulant layer and the insulating layer is less than the second thickness of the polymer display substrate layer in the adjacent region.

11. The method defined in claim 10 further comprising:
removing the deposited polymer display substrate layer and the display circuitry from the support structure.

12. The method defined in claim 11 further comprising:
bending the polymer display substrate layer and display circuitry that have been removed from the support structure along the locally thinned regions.

13. The method defined in claim 12 wherein forming the display circuitry comprises forming an array of display pixels in an active area on the display, wherein the active area is surrounded by an inactive border area, wherein the locally thinned regions are in the inactive border area, and wherein bending the polymer display substrate layer comprises bending the polymer display substrate layer in the inactive border area.

14. An electronic device, comprising:
a housing having an interior surface; and
a flexible display mounted in the housing, wherein the flexible display has at least one edge that is bent along a bend axis and wherein the flexible display includes a polymer substrate with a first and second regions separated by a locally thinned region that overlaps the bend axis, wherein the flexible display includes a metal trace formed on the polymer substrate and an encapsulant layer formed on the metal trace such that a neutral stress plane intersects with the metal trace where the metal trace overlaps the locally thinned region and such that tensile stress is formed in the encapsulant layer where the encapsulant layer overlaps the metal trace, wherein the first region of the polymer substrate defines a plane, wherein the second region of the polymer substrate is bent out of the plane, and wherein the second region of the polymer substrate is parallel to the interior surface of the housing.

15. The electronic device defined in claim 14 wherein the flexible display includes an array of organic light-emitting diode display pixels in an active area, wherein the metal trace is one of a plurality of metal traces in an inactive area that surrounds the active area, and wherein the metal traces include at least some bent metal traces in the portion of the flexible display that overlaps the locally thinned region.

Assignees

• Apple Inc

Inventors

• Kim Kyung Wook
• Park Young Bae
• Chang Shih Chang
• Yang Byung Duk

Classifications

• Y02E10/549

  Organic PV cells · CPC title

• H05K1/0278

  Rigid circuit boards or rigid supports of circuit boards locally made bendable, e.g. by removal or replacement of material · CPC title

• G06F1/1652 Primary

  the display being flexible, e.g. mimicking a sheet of paper, or rollable · CPC title

• H05K1/028 Primary

  Bending or folding regions of flexible printed circuits (H05K1/0283 takes precedence) · CPC title

• H01L2251/5338

  Electricity · mapped topic