Patent ID: 8303155

Claim:
A bifacial light emitting backlight comprising: a light source comprising a base member that extends in a longitudinal direction and a plurality of LEDs that are arranged on a surface of the base member in a longitudinal direction thereof with an interval between one another; a light guide plate having light from the light source incident on an end face thereof, the light guide plate having a top face and a bottom face opposite to the top face; a first microprism array sheet which is a transparent sheet having a plurality of microstructure prisms formed in one face thereof, with the prisms facing the top face of the light guide plate and receiving light from the top face of the light guide plate and directing the light to a first liquid crystal panel; and a second microprism array sheet which is a transparent sheet having a plurality of microstructure prisms formed in one face thereof, with the prisms of the second microprism array sheet facing the bottom face of the light guide plate and receiving light from the bottom face of the light guide plate and directing the light to a second liquid crystal panel, wherein the first microprism array sheet is disposed adjacent to and above the light guide plate and the second microprism array sheet is disposed adjacent to and below the light guide plate, a prism formation region of the second microprism array sheet is smaller than a prism formation region of the first microprism array sheet, and prisms in the prism formation region of the first microprism array sheet are, in an arrangement where a density of prisms arranged increases with distance from the light source, so arranged that the density of prisms arranged increases in a region that faces the prism formation region of the second microprism array sheet, wherein the first and second microprism array sheets are respectively attached to the top and bottom faces of the light guide plate.