Patent ID: 7239382

Claim:
A polarizing plate grading method, comprising: providing a polarizing plate; choosing a first measurement range A 1 on the polarizing plate; conducting an initial measurement of the polarizing plate by putting the polarizing plate under X 1 ° C. for Y 1 hours, then measuring a first measurement range to obtain a maximum chromatic value Z 1max , and a minimum chromatic value Z 1min , and then subtracting the minimum value from the maximum value to obtain the net chromatic difference value W 1 ; conducting a temperature change measurement on the polarizing plate by putting the polarizing plate under X 2 ° C. (X 2 ≠X 1 ) for Y 2 hours, then measuring a first measurement range to obtain a maximum chromatic value Z 2max and a minimum chromatic value Z 2min , and by subtracting the minimum chromatic value from the maximum chromatic value to obtain the net chromatic difference value W 2 ; obtaining a polarizing plate grading index Q by dividing the value obtained from subtracting the net chromatic difference value W 1 from the net chromatic difference value W 2 , by the net chromatic difference value W 1 ; grading the polarizing plate according to the polarizing plate grading index; and providing the grading information to the user.