Abstract: A projection apparatus, an illumination module and a brightness adjusting method for the projection apparatus are provided. The projection apparatus comprises the illumination module and the actuator. The illumination module comprises a luminous element. First, the actuator drives the luminous element to move from the first position to the second position to detect the first brightness and second brightness generated by the luminous element. When the first brightness is higher than the second brightness, the actuator is adapted to drive the luminous element to the first position. Thereby, the brightness of a projection image generated by the projection apparatus can be adjusted to an optimal value.

Abstract: A projection screen, having a projection surface formed of at least two segments, of which at least two segments are sound radiating segments capable of radiating sound waves from the projection surface and designed to reproduce different frequency ranges.