A projector includes a light source assembly, a digital micro-mirror device, and a projection lens. The light source assembly includes a lamp and a color wheel positioned for receiving light generated by the lamp. The color wheel includes a motor having a contacting portion, a filter, a light-blocker, and a light-isolating sheet. The filter is mounted on the contacting portion of the motor and includes a first area and a second area. Light beams used for forming an image only pass through the first area. The light-blocker is disposed on the filter opposite to the motor. The light-isolating sheet is disposed on the first area and positioned between the filter and the motor and configured for isolating the light beams arrived on the second area.