# US 11,451,652 B2 · Foldable display module

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- Number: US 11,451,652 B2
- Document ID: US11451652B2
- Status: Granted
- Kind: B2
- Application number: 16/973,450
- Filed: 2020-09-17
- Published: 2022-06-16
- Granted: 2022-09-20
- Earliest claimed: 2020-07-13
- Assignees: Wuhan China Star Optoelectronics Semiconductor Display Technology Co., Ltd.
- Applicants: Wuhan China Star Optoelectronics Semiconductor Display Technology Co., Ltd.
- Inventors: Guochun Yan; Zhuo Zhang; Yongzhen Jia; Chunmei He; Yuan Zhao; Xiaomeng Hou
- Web page: https://patentgrep.com/patent/US11451652B2

## CPC

- H04M 1/0268: {including a flexible display panel}
- B32B 7/12: using interposed adhesives or interposed materials with bonding properties
- B32B 15/08: of synthetic resin
- B32B 15/18: comprising iron or steel {(B32B15/011, B32B15/012 and B32B15/013 take precedence)}
- B32B 27/281: {comprising polyimides}
- G06F 1/1652: {the display being flexible, e.g. mimicking a sheet of paper, or rollable}
- G09F 9/301: {flexible foldable or roll-able electronic displays, e.g. thin LCD, OLED}
- H04M 1/0214: {Foldable telephones, i.e. with body parts pivoting to an open position around an axis parallel to the plane they define in closed position (combined with translation movement H04M1/0235)}
- B32B 2255/10: on synthetic resin layer or on natural or synthetic rubber layer
- B32B 2255/20: Inorganic coating
- B32B 2255/24: Organic non-macromolecular coating
- B32B 2255/26: Polymeric coating
- B32B 2307/402: Coloured
- B32B 2307/414: Translucent
- B32B 2307/42: Polarizing, birefringent, filtering
- B32B 2307/536: Hardness
- B32B 2307/54: Yield strength; Tensile strength
- B32B 2307/732: Dimensional properties
- B32B 2307/748: Releasability
- B32B 2457/20: Displays, e.g. liquid crystal displays, plasma displays
- H04M 1/0266: {for a display module assembly}
- Y02E 10/549: Organic PV cells
- H04M: TELEPHONIC COMMUNICATION (circuits for controlling other apparatus via a telephone cable and not involving telephone switching apparatus G08)
- B32B: LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N)
- G09F: DISPLAYING; ADVERTISING; SIGNS; LABELS OR NAME-PLATES; SEALS
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION

## Abstract

The present application provides a foldable display module. The foldable display module includes a flexible display panel, a first module, and a second module. The flexible display panel is disposed between the first module and the second module. A ratio of a rigidity of the first module to a rigidity of the second module ranges from 0.8 to 1.2.

## Claims

### Claim 1

A foldable display module, comprising a flexible display panel, a first module, and a second module;
wherein the flexible display panel is disposed between the first module and the second module;
wherein the first module comprises n first submodules, each of the first submodules comprises a first functional layer and a first adhesive layer, the first adhesive layer is disposed between the first functional layer and the flexible display panel, the first functional layer in an i-th first submodule comprises a first elastic modulus E1i and a first thickness H1i, the first adhesive layer in the i-th first submodule comprises a first storage modulus E3i and a third thickness H3i, n is an integer greater than or equal to 1, and i is an integer greater than or equal to 1 and less than or equal to n;
wherein the second module comprises m second submodules, each of the second submodules comprises a second functional layer and a second adhesive layer, the second adhesive layer is disposed between the second functional layer and the flexible display panel, the second functional layer in a j-th second submodule comprises a second elastic modulus E2j and a second thickness H2j, the second adhesive layer in the j-th second submodule comprises a second storage modulus E4j and a fourth thickness H4j, m is an integer greater than or equal to 1, and j is an integer greater than or equal to 1 and less than or equal to m; and
wherein the first elastic modulus E1i, the first thickness H1i, the first storage modulus E3i, the third thickness H3i, the second elastic modulus E2j, the second thickness H2j, the second storage modulus E4j, and the fourth thickness H4j satisfy the following formula:
∑
1
n
⁢
E
1
⁢
i
×
H
1
⁢
i
2
+
∑
1
n
⁢
E
3
⁢
i
×
H
3
⁢
i
2
=
α
⁡
(
∑
1
m
⁢
E
2
⁢
j
×
H
2
⁢
j
2
+
∑
1
m
⁢
E
4
⁢
j
×
H
4
⁢
j
2
)
,
and
α represents an allowable coefficient and is greater than or equal to 0.8 and less than or equal to 1.2.

### Claim 2 (depends on 1)

The foldable display module according to claim 1, wherein α is greater than or equal to 0.9 and less than or equal to 1.1.

### Claim 3 (depends on 1)

The foldable display module according to claim 1, wherein α is equal to 1.

### Claim 4 (depends on 1)

The foldable display module according to claim 1, wherein a maximum allowable reference coefficient βmax of an adhesive layer satisfies the following formula:
β
max
≥
π
4
×

Ea
×
H
⁢
a
2
-
E
⁢
b
×
H
⁢
b
2

E
⁢
c
×
H
⁢
c
2
;
Ec and Hc are respectively a storage modulus and a thickness of the adhesive layer, Ea and Ha are respectively an elastic modulus and a thickness of a first film layer, and Eb and Hb are respectively an elastic modulus and a thickness of a second film layer;
the adhesive layer is disposed between the first film layer and the second film layer to adhere the first film layer and the second film layer;
at least one of the first adhesive layer or the second adhesive layer is the adhesive layer; and
the maximum allowable reference coefficient βmax of the adhesive layer is proportional to a maximum allowable strain of the adhesive layer.

### Claim 5 (depends on 4)

The foldable display module according to claim 4, further comprising a plurality of adhesive layers;
wherein maximum allowable reference coefficients βmax of the plurality of adhesive layers gradually decrease along a bending direction of the foldable display module.

### Claim 6 (depends on 4)

The foldable display module according to claim 4, wherein Ec ranges from 10 kPa to 100 kPa, and Hc ranges from 5 microns to 80 microns.

### Claim 7 (depends on 4)

The foldable display module according to claim 4, wherein material of the adhesive layer is selected from at least one of acrylates, acrylate derivatives, silicones, or modified silicones.

### Claim 8 (depends on 1)

The foldable display module according to claim 1, wherein the first module comprises two first submodules;
in one of the first submodules, the first functional layer is a polarizer, and the first adhesive layer is a first adhesive layer A;
in the other one of the first submodules, the first functional layer is a cover plate, and the first adhesive layer is a first adhesive layer B;
one of the first submodules comprising the polarizer is disposed between the flexible display panel and the one of the first submodules comprising the cover plate;
an elastic modulus of the cover plate ranges from 1 GPa to 12 GPa, and a thickness of the cover plate ranges from 40 microns to 120 microns;
a storage modulus of the first adhesive layer B ranges from 20 kPa to 100 kPa, and a thickness of the first adhesive layer B ranges from 20 microns to 80 microns;
an elastic modulus of the polarizer ranges from 1 GPa to 8 GPa, and a thickness of the polarizer ranges from 20 microns to 80 microns;
a storage modulus of the first adhesive layer A ranges from 10 kPa to 60 kPa, and a thickness of the first adhesive layer A ranges from 5 microns to 40 microns;
the second module comprises one second submodule;
in the second submodule, the second functional layer is a backplate support layer, and the second adhesive layer is a second adhesive layer A;
an elastic modulus of the backplate support layer ranges from 1 GPa to 6 GPa, and a thickness of the backplate support layer ranges from 10 microns to 40 microns; and
a storage modulus of the second adhesive layer A ranges from 10 kPa to 50 kPa, and a thickness of the second adhesive layer A ranges from 8 microns to 40 microns.

### Claim 9 (depends on 8)

The foldable display module according to claim 8, wherein the second module further comprises another one of the second submodule;
one of the second submodules is disposed between the flexible display panel and the other one of the second submodules;
in the other one of the second submodules, the second functional layer is a rigid support layer, and the second adhesive layer is a second adhesive layer B;
an elastic modulus of the rigid support layer is greater than 100 GPa, and a thickness of the rigid support layer ranges from 20 microns to 60 microns; and
a storage modulus of the second adhesive layer B ranges from 10 kPa to 40 kPa, and a thickness of the second adhesive layer B ranges from 20 microns to 80 microns.

### Claim 10 (depends on 9)

The foldable display module according to claim 9, wherein the elastic modulus of the cover plate ranges from 3 GPa to 10 GPa, and the thickness of the cover plate ranges from 53 microns to 120 microns;
the storage modulus of the first adhesive layer B ranges from 30 kPa to 80 kPa, and the thickness of the first adhesive layer B ranges from 40 microns to 60 microns;
the elastic modulus of the polarizer ranges from 2 GPa to 6 GPa, and the thickness of the polarizer ranges from 30 microns to 60 microns;
the storage modulus of the first adhesive layer A ranges from 20 kPa to 40 kPa, and the thickness of the first adhesive layer A ranges from 10 microns to 25 microns;
the elastic modulus of the backplate support layer ranges from 2 GPa to 5 GPa, and the thickness of the backplate support layer ranges from 18 microns to 35 microns;
the storage modulus of the second adhesive layer A ranges from 20 kPa to 40 kPa, and the thickness of the second adhesive layer A ranges from 18 microns to 35 microns;
the elastic modulus of the rigid support layer is greater than 100 GPa, and the thickness of the rigid support layer ranges from 30 microns to 50 microns; and
the storage modulus of the second adhesive layer B ranges from 10 kPa to 40 kPa, and the thickness of the second adhesive layer B ranges from 30 microns to 50 microns.

### Claim 11 (depends on 9)

The foldable display module according to claim 9, wherein the storage modulus of the first adhesive layer B is greater than the storage modulus of the second adhesive layer B.

### Claim 12 (depends on 9)

The foldable display module according to claim 9, wherein a peeling strength between the second adhesive layer B and the rigid support layer is greater than 5 N/cm.

### Claim 13 (depends on 9)

The foldable display module according to claim 9, wherein an elongation of the second adhesive layer B is greater than 1000%.

### Claim 14 (depends on 8)

The foldable display module according to claim 8, wherein a peeling strength between the first adhesive layer B and at least one of the cover plate or the polarizer is greater than 3 N/cm.

### Claim 15 (depends on 1)

The foldable display module according to claim 1, wherein a thickness of the foldable display module ranges from 280 microns to 380 microns.