Patent ID: 7875328

Claim:
An optical film comprising: an aromatic-based unit, which has a chain including 5 to 10,000 units, and is represented by Formula 6 below: a styrene-based unit, which is a copolymer of a styrene derivative and maleic anhydride; and one or more of a (meth)acrylate-based unit which is a copolymer of a (meth)acrylate derivative and maleimide; wherein absolute values of an in-plane retardation (R in ) and a thickness retardation (R th ) of the optical film, as defined by the following Equation, are 10 nm or less regardless of stretching: R in =( n x −n y )× d, R th =[( n x +n y )/2 −n z ]×d wherein, n x is the largest refractive index among in-plane refractive indexes of the film, n y is the refractive index in a direction that is vertical to n x of the in-plane refractive index of the film, n z is the thickness refractive index of the film, and d is the thickness of the film; and/or wherein an absolute value of a photoelasticity coefficient of the optical film is 3×10 −12 m 2 /N or less regardless of the stretching.