A light source device which is uniform in the intensity of distribution of an emitted light and high in the optical utilization efficiency, a display device which is high in recognability and is energy-saving, and an information terminal are provided. The light-emitting diodes include at least one n-doped layer, at least one p-doped layer, and an active region disposed between the at least one n-doped layer and the at least one p-doped layer. 5-10 W in a package of the order of centimeters. The channel sections of the inlet andor outlet channel are defined by at least two elements and the vibration-reducing cavities are also defined by at least two elements. In an alternative embodiment, the tertiary mirror instead of the fold mirror can be moved into either the bypass position or the non-bypass position. Also, the operations include fading in at least one node at a level below the selected node into the first hierarchy tree on the display.