| 摘要 |
PURPOSE: To realize a ultra lightweight back light unit which is capable of having a large-sized light emitting surface having the high brightness and uneven brightness suppressed to the low level. CONSTITUTION: In the back light unit 1 of a both-side lighting system, four rectangular plate-shaped prism array parts 13 (1) to 13 (4), in which prism arrays 13 (1)p to 13 (4)p are formed on the upper surface, are joined together, straight line-like peak parts are almost in parallel with the longitudinal direction of both-light source units 3 and are formed into the gable roof shape so as to be positioned approximately in the middle of the both-light source units 3. A structure, in which a reflecting plate 15 is installed on the lower surface side, is included in this unit. In the two prism array parts 13 (1), 13 (4) on the outer side close to the light source units 3, the ridgelines of respective prisms are intersecting almost orthogonally with or are crossing the straight line-like peak parts of the gable roofs nearly at a right angle. In the two prism array parts 13 (2), 13 (3) on the inner side away from the light source unit 3, the ridgelines of respective prisms are almost in parallel with the straight line peak parts of the gable roofs. |
