US Patent 7357519 Optical projection device

An optical projection device including a light source, a housing, an imaging unit, a projection lens and a dust protection device is provided. The light source is adopted for providing a light beam. The housing has a projection-lens-assembling opening. The imaging unit is disposed in the housing, and on the transmission path of the light beam. In addition, the projection lens in the housing, and exposed by the projection-lens-assembling opening. The dust protection device is disposed between the projection lens and the projection-lens-assembling opening. The optical projection device is thus protected from dust and displaying quality thereof is excellent.