A backlight device that includes a transparent substrate, a plurality of protrusions, a first layer of transparent material, a second layer of transparent material and a light source. A power storage element generates a DC output voltage from an input voltage. A spring is interposed between the piston assembly and the propellant to urge the piston assembly in the projecting direction. For example, the backbone of the communications network may consist of a satellite uplink. 10 m or less, ten or more dislocation lines per grain are present at a fringe portion of the grain, and when the grain is viewed from a direction perpendicular to the main plane, it has a hexagonal or triangular shape whose edge andor corner are partly substantially hollowed.