Flexible display panel with bent substrate

• US 9,614,168 B2
• Filed: 01/04/2016
• Issued: 04/04/2017
• Est. Priority Date: 01/12/2015
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Zhang, Zhen, Tao, Yi, Drzaic, Paul S., Wurzel, Joshua G.
• Primary Examiner(s): Cao, Phat X
• Application Number:
  US14/987,129
• Publication Number:
  US 20160204366A1
• Time in Patent Office: 456 Days
• CPC Class Codes: H01L 23/4985 Flexible insulating substrates H01L23/49572 and H01L23/49855 take precedence
• CPC Class Codes: H01L 23/5387 Flexible insulating substrates H01L23/5388 takes precedence
• CPC Class Codes: H10K 2102/311 Flexible OLED
• CPC Class Codes: H10K 2102/351 Thickness
• CPC Class Codes: H10K 50/844 Encapsulations
• CPC Class Codes: H10K 59/121 characterised by the geometry or disposition of pixel elements
• CPC Class Codes: H10K 59/131 Interconnections, e.g. wiring lines or terminals
• CPC Class Codes: H10K 77/111 Flexible substrates
• CPC Class Codes: H10K 85/141 comprising aliphatic or olefinic chains, e.g. poly N-vinylcarbazol, PVC or PTFE
• CPC Class Codes: Y02E 10/549 Organic PV cells

Abstract

A display may have an array of organic light-emitting diodes that form an active area on a flexible substrate. Metal traces may extend between the active area and an inactive area of the flexible substrate. Display driver circuitry such as a display driver integrated circuit may be coupled to the inactive area. The metal traces may extend across a bend region in the flexible substrate. The flexible substrate may be bent in the bend region. The flexible substrate may be made of a thin flexible material to reduce metal trace bending stress. A coating layer in the bend region may be provided with an enhanced elasticity to allow its thickness to be reduced. The flexible substrate may be bent on itself and secured within an electronic device without using a mandrel.

Claims

1. A display, comprising:

a flexible substrate;

an array of pixels that form an active area on the flexible substrate;

metal traces that extend from the active area to an inactive area on the flexible substrate across a bend region on the flexible substrate, wherein the flexible substrate is folded over against itself at the bend region so that the active area overlaps the inactive area, wherein the inactive area defines a plane parallel to the active area;

first and second polymer layers interposed between the active area and the inactive area that is overlapped by the active area; and

first, second, and third adhesive layers, wherein the first adhesive layer is interposed between the first polymer layer and the active area of the flexible substrate and attaches the first polymer layer to the active area of the flexible substrate, wherein the second adhesive layer is interposed between the second polymer layer and the inactive area of the flexible substrate and attaches the second polymer layer to the inactive area of the flexible substrate, wherein the third adhesive layer is interposed between the first and second polymer layers and attaches the first and second polymer layers together, wherein the first, second, and third adhesive layers have aligned edges that are separated from the bent region of the flexible substrate by a gap, and wherein the first and second polymer layers and the first, second, and third adhesive layers are the only layers interposed between the active area of the flexible substrate and the plane defined by the inactive area of the flexible substrate.

2. The display defined in claim 1 wherein the flexible substrate is a polyimide substrate with a thickness of less than 16 microns.

3. The display defined in claim 1 wherein the flexible substrate is a polyimide substrate with an elasticity of less than 5 GPa.

4. The display defined in claim 1 wherein the flexible substrate is coated with a coating layer in the bend region that has an elasticity of more than 0.7 GPa.

5. The display defined in claim 4 wherein the flexible substrate is a polyimide substrate.

6. The display defined in claim 5 wherein the flexible substrate has a thickness of less than 16 microns.

7. The display defined in claim 1 wherein the first and second polymer layers have respective first and second edges at the bend region that are aligned with each other.

8. The display defined in claim 1 wherein the first and second polymer layers have respective first and second edges and, and wherein the respective first and second edges of the polymer layers are aligned with the aligned edges of the first, second, and third adhesive layers.

9. The display defined in claim 1 wherein the first and second polymer layers have respective first and second edges at the bend region that are not aligned with each other.

10. The display defined in claim 1 wherein the array of pixels comprises an array of organic light-emitting diode pixels.

11. A display, comprising:

a flexible substrate having opposing first and second surfaces;

an array of pixels that form an active area on the first surface of the flexible substrate, wherein the flexible substrate is folded at a bend region;

first and second polymer layers that are attached between a first portion of the second surface of the flexible substrate and a second portion of the second surface of the flexible substrate;

a first layer of adhesive between the first and second polymer layers, the first layer of adhesive having a first edge; and

a second layer of adhesive between the second polymer layer and the second portion of the second surface of the flexible substrate, the second layer of adhesive having a second edge aligned with the first edge.

12. The display defined in claim 11 further comprising metal traces that extend from the active area to an inactive area on the flexible substrate across the bend region, wherein the inactive area is free of pixels.

13. The display defined in claim 12 wherein the first layer of adhesive has a protruding portion that protrudes from between the first and second polymer layers and that contacts the flexible substrate.

14. The display defined in claim 11 wherein the array of pixels comprises an array of organic light-emitting diode pixels.

15. The display defined in claim 14 wherein the flexible substrate is coated with a coating layer in the bend region.

16. The display defined in claim 11, further comprising:

a third layer of adhesive between the first polymer layer and the first portion of the second surface of the flexible substrate, wherein the third layer of adhesive has a third edge aligned with the first edge and with the second edge.

17. An organic light-emitting diode display, comprising:

thin-film transistor circuitry that forms an array of pixels;

a flexible substrate having a first surface on which the thin-film transistor circuitry is formed and having an opposing second surface, wherein the flexible substrate is bent back on itself in a bend region so that a first portion of the second surface faces a second portion of the second surface;

at least one polymer layer and at least one layer of adhesive that attach the first portion to the second portion; and

a polymer coating on the first surface of the flexible substrate, wherein the polymer coating overlaps a portion of the thin-film transistor circuitry so that the thin-film transistor circuitry is interposed between the polymer coating and the first surface, wherein the polymer coating is bent back on itself in the bend region and extends behind the first and second portions of the second surface of the flexible substrate to overlap the array of display pixels, the at least one polymer layer, and the at least one layer of adhesive.

18. The organic light-emitting diode display defined in claim 17 wherein the at least one polymer layer comprises first and second polymer layers, and wherein the at least one layer of adhesive includes adhesive between the first and second polymer layers that attaches the first polymer layer to the second polymer layer.

19. The organic light-emitting diode display defined in claim 17 further comprising:

a moisture barrier film that overlaps the thin-film transistor circuitry, wherein the polymer coating overlaps the moisture barrier film so that the moisture barrier film and the thin-film transistor circuitry are interposed between the polymer coating and the first surface.

20. An apparatus, comprising:

a flexible substrate;

an array of pixels on the flexible substrate that form an active area of the flexible substrate, wherein the active area has a rectangular shape that is surrounded by an inactive area;

metal traces that extend from the active area to the inactive area on the flexible substrate across a bend region on the flexible substrate, wherein the flexible substrate is folded over against itself at the bend region so that the active area overlaps the inactive area;

first and second polymer layers interposed between the active area and the inactive area that is overlapped by the active area; and

first, second, and third adhesive layers, wherein the first adhesive layer is interposed between the first polymer layer and the active area of the flexible substrate and attaches the first polymer layer to the active area of the flexible substrate, wherein the second adhesive layer is interposed between the second polymer layer and the inactive area of the flexible substrate and attaches the second polymer layer to the inactive area of the flexible substrate, wherein the third adhesive layer is interposed between the first and second polymer layers and attaches the first and second polymer layers together, and wherein the inactive area of the flexible substrate overlaps at least half of the active area of the flexible substrate.

21. The apparatus defined in claim 20 wherein the flexible substrate is a polyimide substrate with a thickness of less than 16 microns.

22. The apparatus defined in claim 20 wherein the flexible substrate is a polyimide substrate with an elasticity of less than 5 GPa.

23. The apparatus defined in claim 20 wherein the flexible substrate is coated with a coating layer in the bend region that has an elasticity of more than 0.7 GPa.

24. The apparatus defined in claim 20 wherein the flexible substrate is a polymer substrate.

25. The apparatus defined in claim 20 wherein the flexible substrate is a polymer substrate, the apparatus further comprising:

an array of sensor structures in the active area.

26. The apparatus defined in claim 20 wherein the first and second polymer layers have respective first and second edges and wherein the third adhesive layer has a protruding portion that extends from between the first and second polymer layers past the first and second edges.

27. The apparatus defined in claim 20, wherein the first and second polymer layers overlap at least half of the active area of the flexible substrate.

28. The apparatus defined in claim 27, wherein the first, second, and third adhesive layers overlap at least half of the active area of the flexible substrate.