US Patent 7217002 Ambient lighting system

In a room lighting system (1; 27), e.g. an architectural lighting system, including two alignedly arranged refractive elements (9, 10) whose centers are substantially located in the beam axis (11) of a light source (7) and one (10) of which is mounted to be rotatable about said beam axis (11), also the other refractive element (9) is mounted to be rotatable about said beam axis (11), wherein drive means (18, 19; 13 to 17) plus control means (20) are associated with to the two refractive elements (9, 10) for selective rotation in the same sense or in opposite senses, and both of the refractive elements (9, 10) are prism elements, wherein at least the two refractive prism elements (9, 10) are arranged in a common housing (2; 28).