Image Number 6 for United States Patent #6808273.
A lens cover is provided for being held between the air outlet and the projection lens. This allows the lens cover to prevent hot air exhausted from the air outlet from running across the light path of a projected light from the projection lens when the projection of an image is desired, hence avoiding the generation of shimmers in the projected image. Preferably, the lens cover is arranged vertical to the optical axis of the projection lens for turning movement on an axis located between the projection lens and the air outlet. Accordingly, the lens cover is hardly lost.