space therebetween in the internal space the liquid crystal panel 32 and the like are housed electronic components to be housed in the display unit 30 such as the liquid crystal panel 32 are fixed to the lower panel 312 fig2 illustrates the upper panel removed from the display unit fig2 illustrates the display unit having the upper panel removed therefrom fig2 illustrates the upper panel 311 in a reversed state moreover fig2 illustrates a connection side of the main unit 20 and the display unit 30 positioned frontward fig2 illustrates the liquid crystal panel 32 fixed to the lower panel 312 an inverter circuit board 33 for turning on a backlight of the liquid crystal panel 32 and the like moreover in the lower panel 312 a concave section 313 for housing the inverter circuit board 33 is provided the concave section 313 being formed of ribs surrounding its periphery the inverter circuit board 33 is housed in the concave section 313 in a state of being covered with a retaining sheet 34 for retaining the inverter circuit board 33 in the concave section 313 specifically the retaining sheet 34 is formed of a pet film and details thereof will be described later in this embodiment the upper panel 311 is fixed to the lower panel 312 by use of screws or by locking with locking claws provided.