disposed diagonally above the fixing unit 60 the sheet 4 is further conveyed between ejection rollers 64 disposed in the upper portion of the housing 2 and is finally ejected to the output tray 5 a fan 67 is disposed above the fixing unit 60 the fan 67 and a circuit board 69 are disposed on the right side of the image forming apparatus 1 the fan 67 is configured to circulate air e g suck air through a duct 66 that is disposed above the fixing unit 60 and behind the image formation units 30 the circuit bard 69 is configured to supply power to the individual parts a pair of engine frames 70 is disposed on the right and left sides of the belt unit 20 the image formation units 30 the belt cleaner unit 40 and the led units 50 to support them the engine frames 70 that support the above units will be described with reference to fig2 fig2 is a perspective partially cutaway view of the engine frames 70 as shown in fig2 the engine frames 70 are formed of sheet metal by stamping to have left right symmetry and disposed inside the housing 2 the engine frames 70 are connected by tubular reinforcing members 80 disposed horizontally at four places of a front upper portion a front lower portion a rear upper portion and a rear lower portion a flat partition plate 71 is fixed at the lower ends of the engine frames 70 and configured to horizontally partition between the belt cleaner unit 40 and the sheet.