A light pipe in which light incident on an incident side surface (13) is outputted from a lower surface (12) through a light output means formed on an upper surface (11), the direction of the largest intensity of the light outputted from the lower surface is within an angle of 30 degrees to a normal line with respect to a reference plane of the lower surface, the largest intensity of light leaking from the upper surface in the direction within the angle of 30 degrees is not higher than 1/5 as high as the largest intensity at the lower surface, and the light pipe has a hard coat layer-on the upper surface so that light incident on the lower surface is transmitted from the upper surface; a surface light source device having a light source disposed on the incident side surface of the light pipe; and a reflection type liquid-crystal display device having a liquid-crystal cell provided with a reflection layer disposed on the lower surface side of the surface light source.
A compact backlight system has a light-emitting panel (1) with a front wall (2), a rear wall (3) situated opposite thereto, and furthermore, between the front and the rear wall (2, 3), a translucent input edge surface (4) for coupling light into the light-emitting panel (1). A light source (6, 6', . . . ) is associated with the input edge surface (4). According to the invention, the rear wall (3) in a first portion (12) of the light-emitting panel (1) is provided with a multiplicity of steps (13, 13', . . . ), and a second portion (22) of the light-emitting panel (1) widens from the input edge surface (4) in a direction facing the first portion (12). Preferably, a surface (17) of the steps (13, 13', . . . ) facing the input edge surface (4) makes an angle .beta..sub.av.gtoreq.5.degree. (with respect to a normal on a bisecting plane (20) bisecting the light-emitting panel (1).
A light-diffusing sheet includes a transparent film and a light-diffusing layer formed on at least one side of the transparent film. The transparent film contains a thermoplastic resin having a substituted and/or non-substituted imido group in a side chain, and a thermoplastic resin having a substituted and/or non-substituted phenyl group and nitrile group in a side chain, and the surface with the minute unevenness has an average height-depth spacing (Sm): Sm.ltoreq.80 .mu.m, a center-line average surface roughness (Ra): Ra.ltoreq.0.25 .mu.m and a ten-point average surface roughness (Rz): Rz.ltoreq.9Ra.
A display device is disclosed. The display device includes a lamp emitting light, a plurality of filters dividing the emitted light into a red light, a green light, and a blue light, an additional light source unit compensating a light having a lowest light intensity among the divided red, green, and blue light, and a red liquid crystal display, a green liquid crystal display, and a blue liquid crystal displaying an image by using the light emitted from the lamp and the light emitted from the additional light source unit.
A light-diffusing sheet includes a transparent film and a light-diffusing layer formed on at least one side of the transparent film. The light-diffusing layer is composed of a resin coating layer having a rough surface. The transparent film contains a thermoplastic resin having a substituted and/or unsubstituted imide group at a side chain and a thermoplastic resin having a substituted and/or unsubstituted phenyl group and a nitrile group at a side chain.
