Already in the years 1925/26 Poul Henningsen conceived the three-part light shade, and the first models made in collaboration with Louis Poulsen were displayed at an exhibition in Paris. This collaboration lasted until P. Henningsen's death in 1967. During his lifetime, Poul Henningsen wished to create light fixtures emitting a glare-free light which project soft shadows and guide the light cone to the right spot. For the first time in 1931, a light fixture was created with a shade composed of four parts to be suspended from the ceiling and meant as an alternative to the conventional chandeliers of the time. The model PH 4 should offer an improved illumination to the sides to better brighten room walls and shelves as it was possible with the shade consisting of three parts. During the 1940s, this model disappeared from Louis Poulsen's standard portfolio and was reviewed by the the Danish architects Sophus Frandsen und Ebbe Christensen for the exhibition building Charlottenborg in Copenhagen in 1979 and was larger (PH 6½/6). To solve the reccuring problem of glaring light, the architects decided to add a small, blue shade element. The surfaces of the remaining elements are matt white to achieve the same, pleasant lighting accents especially in museums and exhibition rooms and in high rooms. A smaller model (5/4½) for the concert hall Århus Musikhus was made in 1984.