Foldable display device

Patent metadata

Field	Value
Publication number	US-2017200915-A1
Application number	US-201615237481-A
Country	US
Kind code	A1
Filing date	Aug 15, 2016
Priority date	Jan 11, 2016
Publication date	Jul 13, 2017
Grant date	—

Abstract

A foldable display device includes a display panel, a polarizing member on the display panel, a window on the polarizing member, a first adhesive member between the display panel and the polarizing member, and a second adhesive member between the polarizing member and the window. In a first state, the display panel, the polarizing member, the window, the first adhesive member, and the second adhesive member are bent along a bending axis such that the window is closer to the bending axis than the display panel is. The first and second adhesive members have a storage modulus in a range of about 5×10 4 Pa to about 5×10 5 Pa at about −25° C. The second adhesive member has a storage modulus in a range of about 4.5×10 4 Pa to about 6.5×10 4 Pa at about 60° C. The first adhesive member has a stress-relaxation ratio greater than about 40 and less than about 50.

First claim

What is claimed is:

1 . A foldable display device comprising:
a display panel; a polarizing member on the display panel; a window on the polarizing member; a first adhesive member between the display panel and the polarizing member; and a second adhesive member between the polarizing member and the window, wherein, in a first state, the display panel, the polarizing member, the window, the first adhesive member, and the second adhesive member are bent along a bending axis such that the window is closer to the bending axis than the display panel is, wherein each of the first adhesive member and the second adhesive member has a storage modulus in a range of about 5×10 4 Pa to about 5×10 5 Pa at about −25° C., wherein the second adhesive member has a storage modulus in a range of about 4.5×10 4 Pa to about 6.5×10 4 Pa at about 60° C., wherein the first adhesive member has a stress-relaxation ratio that is greater than about 40 and less than about 50, the stress-relaxation ratio being defined as
Stress-relaxation ratio (%)=100× G ( t 2)/ G ( t 1), and

wherein G(t1) is an initial stress-relaxation modulus measured in a state in which the first adhesive member is about 600 μm thick, the initial stress-relaxation modulus being measured with a rheometer in a stress-relaxation test mode when a strain of about 25% is removed after being applied using a parallel plate for about 100 seconds at about 60° C., and G(t2) is a stress-relaxation modulus measured after the strain is applied to the first adhesive member for about 300 seconds.

2 . The foldable display device of claim 1 , wherein, in a second state, the display panel, the polarizing member, the window, the first adhesive member, and the second adhesive member are unbent.

3 . The foldable display device of claim 1 , wherein the first adhesive member has a residual strain in a range of about 5 to about 8 at about 60° C., the residual strain being defined as
Residual strain (%)= L 2/ L 1×100, and

wherein L1 is a maximum creep strain for the state in which the first adhesive member is prepared to be about 600 μm and when a stress of about 2000 Pa is applied to the first adhesive member for about 1 hour at about 60° C. using a rheometer, and L2 is unrecovered residual recovery strain that remains along with elastic recovery strain that is recovered when the applied stress is removed after achieving the maximum creep strain.

4 . The foldable display device of claim 1 , wherein the first adhesive member has a thickness in a range of about 25 μm to about 100 μm.

5 . The foldable display device of claim 1 , wherein the second adhesive member has a thickness in a range of about 25 μm to about 100 μm.

6 . The foldable display device of claim 1 , wherein the first adhesive member has a peel strength of at least about 800 gf/in.

7 . The foldable display device of claim 1 , wherein the second adhesive member has a peel strength of at least about 800 gf/in.

8 . The foldable display device of claim 1 , wherein the first adhesive member comprises a first silicone-based base polymer, a first adhesion imparting agent, and a first cross-linking agent, and
wherein the second adhesive member comprises a second silicone-based base polymer, a second adhesion imparting agent, and a second cross-linking agent.

9 . The foldable display device of claim 1 , further comprising:
a protective film below the display panel; and a third adhesive member between the display panel and the protective film, wherein, in the first state, the protective film and the third adhesive member are bent along the bending axis and, in a second state, are unbent.

10 . The foldable display device of claim 9 , wherein a thickness of the third adhesive member is less than a thickness of each of the first adhesive member and the second adhesive member.

11 . The foldable display device of claim 9 , wherein the third adhesive member has a storage modulus in a range of about 5×10 4 Pa to about 5×10 5 Pa at about −25° C.

12 . The foldable display device of claim 1 , further comprising a touch sensing unit between the polarizing member and the window,
wherein, in the first state, the touch sensing unit is bent along the bending axis and, in the second state, is unbent.

13 . The foldable display device of claim 12 , further comprising a fourth adhesive member between the polarizing member and the touch sensing unit,
wherein, in the first state, the fourth adhesive member is bent along the bending axis and, in a second state, is unbent.

14 . The foldable display device of claim 13 , wherein a thickness of the fourth adhesive member is less than a thickness of each of the first adhesive member and the second adhesive member.

15 . The foldable display device of claim 13 , wherein the fourth adhesive member has a storage modulus in a range of about 5×10 4 Pa to about 5×10 5 Pa at about −25° C.

16 . The foldable display device of claim 12 , wherein the touch sensing unit directly contacts the polarizing member.

Assignees

• Samsung Display Co Ltd

Inventors

• Lee Jihwa
• Kim Jinkyu
• Oh Minju
• Lee Jeongkug
• Lee Chansong
• Lee Hyoungwook

Classifications

• Y02E10/549

  Organic PV cells · CPC title

• G06F2203/04102

  Flexible digitiser, i.e. constructional details for allowing the whole digitising part of a device to be flexed or rolled like a sheet of paper · CPC title

• B32B2457/206

  Organic displays, e.g. OLED · CPC title

• B32B2457/20

  Displays, e.g. liquid crystal displays, plasma displays · CPC title

• B32B2307/51

  Elastic · CPC title