A system and method for distributing guaranteed bandwidth among service groups in a network node are described. The lumbar support has a lower projection including a pair of cylindrical protrusions at both sides with resilient and metal gaskets put thereon, an outer gear formed around one of the pair of protrusions, and a through hole through the protrusions. A structure of an inorganic film, an organic film, and an inorganic film is not continuously provided from under a sealing material under a cathode for a light-emitting element. The electrostatic capacity of the rectifier part is smaller than that of the light emitting part.