Patent ID: 7901600

Claim:
A method for producing an optical sheet comprising the steps of: arranging an uncured hardening resin on a transparent base made of a flexible material; pressing a mother die having projections onto the hardening resin, and pressing tops of the projections onto the transparent base until: (a) the uncured hardening resin is in contact with a valley between adjacent projections on the mother die, and (b) depressions are formed in the transparent base; forming the hardening resin by curing the hardening resin in a state that the projections are pressed onto the transparent base; and peeling the formed hardening resin from the mother die together with the transparent base, wherein the depressions are formed to a sufficient depth to generate a stress in the hardening resin in a direction opposite to a direction of stress owing to a shrinkage of the hardening resin during the curing step.