Relay connectors are arranged to supply power from power boards arranged on the back side of a chassis having a substantially plate-shaped configuration to discharge tubes arranged on the front side of the chassis. Each relay connector includes a holder having an insulation property and to be mounted to the chassis, and further includes a relay terminal mounted to the holder and capable of electrical connection to the discharge tube and the power board. The relay terminal is immune to direct contact with the chassis. This enables the use of a metallic chassis.