US Patent 7405891 Projection apparatus

A projection apparatus including an optical engine, a ring, a lens and multiple casings is provided. The optical engine is suitable for producing an image light beam to project an image onto a screen. The ring is fixed on the optical engine. The lens is disposed outside the optical engine and located at a transmission path of the image light beam. The casings are assembled to the ring and connected to each other to form a lens barrel for fixing the lens, and the lens is driven to move relative to the optical engine and the ring by the lens barrel. The projection apparatus has a smaller overall dimension.