To join an aluminum chassis mounting a PDP panel and circuit board to a casing having electrical conductivity in the form of electrically insulating the same as a measure for the radiation of the PDP.

Insulating spacers 7 are inserted into spacer mounting holes 16 disposed at a back cover 2 and are rotated 45°. The back cover 2 is then held sandwiched by dislodgment preventive ribs 14 and positioning dowels 11 of the insulating spacers 7 rotate progressively without being nabbed during the course of the rotation by the effect of hinges 12. When the dowels rotate 45°, the positioning dowels 11 of the insulating spacers 7 are fitted into the positioning holes 15 of the back cover 2 by the spring characteristic of the hinges 12, by which the positions of the insulating spacers 7 may be locked.