US Patent 7591571 Light source device and projection display apparatus

A projection display apparatus generates image light by modulating, with an image signal, light emitted from a light source disposed in a lamp house, and projects the generated image light onto a screen. The projection display apparatus has an air inlet duct for introducing air, to cool the light source, into the lamp house and an air outlet duct for expelling the air discharged from the lamp house out of the projection display apparatus. The air outlet duct has an opening defined in a side wall thereof, and a lid pivotally mounted thereon for selectively opening and closing the opening. The lid is not opened under normal pressure in the air outlet duct when the light source operates normally, and is opened when an abnormal pressure buildup higher than the normal pressure is applied to the lid, thereby releasing the pressure buildup.