In a panel joint structure, a first joint portion and first load transfer portions are formed on an end portion of a first panel, and a second joint portion and second load transfer portions are formed on an end portion of a second panel. A memory of a scanning control device stores correction data of the deviation of the beam pitch, correction data of the light amount difference, and correction data to decrease an influence of a reciprocity failure, for each combination of pixel forming light emitting portions. The actuating mechanism operates the hydraulic pump to provide a hydraulic control line to control movement the valve member from a first position, where the member is open and a through bore is created between the inlet and outlet of the assembly, to a second position, where the valve seals the throughbore and, finally, back to the first position. The first conductive layer is patterned to form a plurality of trenches in the capacitor region.