LIGHT RECYCLING HOLLOW CAVITY TYPE DISPLAY BACKLIGHT

摘要

An asymetric reflective film is disclosed. Such a film can be used as the front reflector (610) in a hollow cavity backlight (600), which recycles the light. The film consists of alternating polymer layers, whose arrangement and refractive indices are appropriately tailored. Such a backlight addresses the need for thinner, lighter, large-area devices with fewer components but defined output polarisation and adequate viewing angles. A uniform light distribution in the cavity and a directed output light (662) distribution are necessary. The front reflector (610) has a partial reflectivity for one polarisation state (662a) and a high reflectivity for the orthogonal state (666), wherein the partial reflectivities of the desired output polarisation state differ according to according to incident s- and p- polarisation states. A further backlight design is disclosed which comprises a front reflector, which reflects substantially all light of a first incidence angle distribution but partially reflects and transmits other light, which forms a second light distribution. A conversion structure in the cavity converts light of the first distribution into the second distribution. Application: displays or general lighting.