Patent ID: 7217025

Claim:
A backlight unit comprising: a light guide panel (LGP); a point light source emitting light and arranged at an edge of the LGP; and a refraction member being positioned between the point light source and the LGP, wherein the refraction member is shaped to refract the light emitted from the point light source toward an optical axis of the point light source in order to reduce an azimuth angle of light that is incident upon the LGP, wherein the refraction member comprises a prism array of V-shaped prisms, wherein the V-shaped prisms comprise apexes facing the LGP, wherein the refraction member further comprises a transparent member wherein the prism array is attached to the transparent member on a side adjacent the LGP, wherein the refraction member further comprises a transparent portion arranged along the optical axis of the light source, wherein the transparent portion is shaped to prevent light emitted from the light source from being totally reflected, and wherein the width of the transparent portion is determined so that a full width half maximum (FWHM) of the light emitted by the light source and incident upon the LGP is at a minimum value; and light flux/steradian is at a maximum value.