Electronic blackboard

1. An electronic blackboard comprising:

a display panel;

a polarizing plate disposed on the display panel, wherein the polarizing plate comprises a polarizer and a high hardness plastic film which are integrated with each other by an adhesive layer; and

a touch sensor recognizing input information through a contact of a user,

wherein the electronic blackboard signalizes written content contacted by the user on an uppermost surface of an uppermost part of the electronic blackboard to directly realize as an image on the display panel,

wherein the high hardness plastic film comprises:

a supporting substrate;

a first coating layer in direct contact with the supporting substrate, formed on a lower side of the supporting substrate, and having a first elastic modulus; and

a second coating layer in direct contact with the supporting substrate, formed on an upper side of the supporting substrate, and having a second elastic modulus,

wherein the high hardness plastic film is disposed at the uppermost part of the electronic blackboard, and the second coating layer provides the uppermost surface,

wherein the first elastic modulus is 300 MPa to 1500 MPa, as measured by ASTM D882, and

wherein the second elastic modulus is 2000 MPa to 3000 MPa as measured by ASTM D882.

2. The electronic blackboard according to claim 1 , wherein the first coating layer and the second coating layer are independently identically or differently formed by curing a coating composition comprising:

a binder comprising:

tri- to hexafunctional acrylate;

at least one selected from the group consisting of mono- to difunctional acrylate, photocurable elastomer, and amphipathic block copolymer; and

a photoinitiator.

3. The electronic blackboard according to claim 1 , wherein the supporting substrate is a film inducing circular polarization or depolarization.

4. The electronic blackboard according to claim 1 , wherein the polarizing plate has pencil hardness of 7H or more under 1 kg load.

5. The electronic blackboard according to claim 1 , wherein the polarizing plate further comprises:

a second adhesive layer formed on a lower side of the polarizer; and

an isotropic or anisotropic polymer film attached to the second adhesive layer.

6. The electronic blackboard according to claim 1 , wherein the touch sensor is a capacitive, resistive, or optical touch sensor.

7. The electronic blackboard according to claim 1 , wherein the touch sensor comprises a conductive layer on at least one side thereof.

8. The electronic blackboard according to claim 1 , further comprising:

a second adhesive layer formed on a lower side of the polarizer; and

an optical functional layer attached to the second adhesive layer.

9. The electronic blackboard according to claim 8 , wherein the optical functional layer comprises at least one transparent polymer film, liquid crystal film or a combination thereof.

10. The electronic blackboard according to claim 9 , wherein the transparent polymer film is at least one selected from the group consisting of a cellulose based film, an acryl based film, a cycloolefin based film, a polyester based film, and a polycarbonate based film.

11. The electronic blackboard according to claim 9 , wherein the transparent polymer film is a protection film or a compensation film.

12. The electronic blackboard according to claim 11 , wherein the compensation film is ±A film, ±B film, ±C film or a combination thereof.

13. The electronic blackboard according to claim 12 , wherein the display panel is an IPS-LCD panel, and

the compensation film is a laminate of −B film and +C film.

14. The electronic blackboard according to claim 12 , wherein the display panel is a VA-LCD panel, and

the compensation film is a laminate of −B film or +A film and +C film.