Foldable display module

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 E 1i and a first thickness H 1i , the first adhesive layer in the i-th first submodule comprises a first storage modulus E 3i and a third thickness H 3i , 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 E 2j and a second thickness H 2j , the second adhesive layer in the j-th second submodule comprises a second storage modulus E 4j and a fourth thickness H 4j , 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 E 1i , the first thickness H 1i , the first storage modulus E 3i , the third thickness H 3i , the second elastic modulus E 2j , the second thickness H 2j , the second storage modulus E 4j , and the fourth thickness H 4j 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.

2. 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.

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

4. The foldable display module according to claim 1 , wherein a maximum allowable reference coefficient β max 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

;

E c and H c are respectively a storage modulus and a thickness of the adhesive layer, E a and H a are respectively an elastic modulus and a thickness of a first film layer, and E b and H b 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 β max of the adhesive layer is proportional to a maximum allowable strain of the adhesive layer.

5. The foldable display module according to claim 4 , further comprising a plurality of adhesive layers;

wherein maximum allowable reference coefficients β max of the plurality of adhesive layers gradually decrease along a bending direction of the foldable display module.

6. The foldable display module according to claim 4 , wherein E c ranges from 10 kPa to 100 kPa, and H c ranges from 5 microns to 80 microns.

7. 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.

8. 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.

9. 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.

10. 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.

11. 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.

12. 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.

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

14. 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.

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