US Patent 7325931 Projection type video display

An ion wind generator is provided at the back of a light source. The ion wind generator negatively ionizes air by corona discharges using negative-side needle electrodes and draws the negatively-ionized air to a ground-side mesh electrode to allow an airflow to be occurred. A photocatalyst filter is provided at the back of the ion wind generator. Even if ozone (O3) is generated and a lower fatty acid is composed by the ozone and alcohol remained in a casing, the lower fatty acid is decomposed into alcohol and oxygen by the photocatalyst filter.