Flexible image display device

Abstract

A flexible image display device includes a window substrate, a polarizing plate, and a touch panel, wherein a distance between a neutral plane and a lower surface of the touch panel based on a visible side during bending is 34% or less to an entire thickness of the flexible image display device. The flexible image display device has excellent flexibility and may significantly reduce a defect rate due to a damage of the touch panel by minimizing the damage of the touch panel even if repeatedly applying bending fatigue thereto.

What is claimed is: 
     
       1. A flexible image display device comprising:
 a window substrate; 
 a polarizing plate; and 
 a touch panel between the window substrate and the polarizing plate, wherein a distance between a neutral plane and a lower surface of the touch panel based on a visible side during bending is 34% or less to an entire thickness of the flexible image display device,; and 
 a display panel disposed on a side opposite to the window substrate based on the polarizing plate and the touch panel, 
 wherein a substrate of the touch panel has a toughness of 2,000 MPa % or more; and 
 the window substrate, the touch panel and the display panel have an elastic modulus of 2 GPa to 7 GPa, respectively, and the polarizing plate has an elastic modulus of 7 GPa or less. 
 
     
     
       2. The flexible image display device according to  claim 1 , further comprising a display panel disposed on a side opposite to the window substrate based on the polarizing plate and the touch panel. 
     
     
       3. The flexible image display device according to claim  2  1, wherein a thickness between an upper surface of the window substrate and a lower surface of the display panel is 500 μm or less. 
     
     
       4. The flexible image display device according to claim  2  1, wherein the window substrate has a thickness thicker than a total thickness of the polarizing plate, the touch panel and the display panel, and an elastic modulus larger than an elastic modulus of a laminate of the polarizing plate, the touch panel and the display panel. 
     
     
       5. The flexible image display device according to  claim 2 , wherein the window substrate, the touch panel and the display panel have an elastic modulus of 2 GPa to 7 GPa, respectively, and the polarizing plate has an elastic modulus of 7 GPa or less. 
     
     
       6. The flexible image display device according to  claim 2 , wherein optical clear adhesive layers are located between the window substrate and the polarizing plate, and between the touch panel and the display panel. 
     
     
       7. The flexible image display device according to  claim 2 , wherein the window substrate, the polarizing plate, the touch panel and the display panel are laminated in this order. 
     
     
       8. The flexible image display device according, to  claim 7 , wherein the substrate of the touch panel has a front retardation of ±2.5 nm or less. 
     
     
       9. The flexible image display device according to claim  2  1, wherein the window substrate, the touch panel, the polarizing plate and the display panel are laminated in this order. 
     
     
       10. The flexible image display device according to  claim 1 , wherein the touch panel satisfies Equation 1 below:
   (Toughness of touch panel substrate/Stress applied to the touch panel during bending)>9%  [Equation 1]
 
 wherein the stress is a stress applied to the touch panel when bending the flexible image display device with a radius of curvature of 2.5 mm at a speed of 40 times/minute at room temperature by repeating 300,000 times. 
 
     
     
       11. A flexible image display device comprising:
 a window substrate;   a touch panel, wherein a distance between a neutral plane and a lower surface of the touch panel based on a visible side during bending is 34% or less to an entire thickness of the flexible image display device, and a substrate of the touch panel has a toughness of 2,000 MPa % or more;   a polarizing plate between the window substrate and the touch panel; and   a display panel disposed on a side opposite to the window substrate based on the polarizing plate and the touch panel,   wherein a thickness between an upper surface of the window substrate and a lower surface of the display panel is 500 μm or less.   
     
     
       12. The flexible image display device according to claim 11, wherein the window substrate has a thickness thicker than a total thickness of the polarizing plate, the touch panel and the display panel, and an elastic modulus larger than an elastic modulus of a laminate of the polarizing plate, the touch panel and the display panel. 
     
     
       13. The flexible image display device according to claim 11, wherein the window substrate, the touch panel and the display panel have an elastic modulus of 2 GPa to 7 GPa, respectively, and the polarizing plate has an elastic modulus of 7 GPa or less. 
     
     
       14. The flexible image display device according to claim 11, wherein optical clear adhesive layers are located between the window substrate and the polarizing plate, and between the touch panel and the display panel. 
     
     
       15. The flexible image display device according to claim 11, wherein the window substrate, the polarizing plate, the touch panel and the display panel are laminated in this order. 
     
     
       16. The flexible image display device according to claim 15, wherein the substrate of the touch panel has a front retardation of ±2.5 nm or less. 
     
     
       17. The flexible image display device according to claim 11, wherein the touch panel satisfies Equation 1 below:
   (Toughness of touch panel substrate/Stress applied to the touch panel during bending)>9%  [Equation 1]
   wherein the stress is a stress applied to the touch panel when bending the flexible image display device with a radius of curvature of 2.5 mm at a speed of 40 times/minute at room temperature by repeating 300,000 times.