Patent ID: 7012660

Claim:
A liquid-crystal display device comprising: a light pipe including light output means for outputting light, said light output means formed on an upper surface of said light pipe; a light source disposed near an incident side surface of said light pipe, light traveling along said light pipe being reflected toward a lower surface of said light pipe; a reflection layer disposed on said lower surface of said light pipe so that said reflected light is again reflected, toward the upper surface of said light pipe, to be transmitted through said upper surface of said light pipe; and a liquid-crystal shutter disposed above said upper surface of said light pipe, said liquid-crystal shutter including liquid-crystal cells and at least one polarizing plate, further wherein said light output means comprises a repetitious structure of continuous or discontinuous prism-like irregularities, each of said prism-like irregularities comprising: a short side surface constituted by a slope inclined downward from the incident side surface toward an opposite end of the incident side surface at an inclination angle of less than 45 degrees with respect to a reference plane of said lower surface, and wherein each of said prism-like irregularities are arranged at intervals of a pitch of from 50 μm to 1.5 mm and further comprise: a long side surface constituted by a slope inclined at an inclination angle in a range of from 0 to 10 degrees, exclusive of 0 degree, with respect to said reference plane so that the difference in the inclination angle among all of said slopes of the long side surface is within 5 degrees and the difference in the inclination angle between adjacent long side surfaces is within 1 degree, wherein a vertex of each of the prism-like irregularities is rounded with a predetermined curvature radius.