Patent ID: 11880059
Assignee: 3M INNOVATIVE PROPERTIES COMPANY
Field: Electrical machinery, apparatus, energy (Electrical engineering)
Classification: CPC G | IPC F  G

Claim 0:
1. A backlight for providing illumination to a liquid crystal panel, comprising:
a reflective polarizer, such that for a substantially normally incident light and for at least one visible wavelength in a range extending from about 400 nm to about 800 nm, the reflective polarizer reflects at least 60% of the incident light having a first polarization state and transmits at least 60% of the incident light having an orthogonal second polarization state; and
an extended light source comprising:
a diffuse reflective film assembly; and
an emission surface disposed between the reflective polarizer and the diffuse reflective film assembly, the extended light source configured to emit light through the emission surface toward the reflective polarizer, wherein the diffuse reflective film assembly comprises:
a specularly reflective film, such that for a substantially normally incident light and for the at least one visible wavelength, the reflective film specularly reflects at least 80% of the incident light for each of the first and second polarization states; and
an optically diffusive film disposed between the emission surface and the specularly reflective film and bonded to the specularly reflective film at a plurality of discrete spaced apart bonded locations, wherein the optically diffusive film comprises a plurality of fibers, and wherein at least 20% of the fibers have an average diameter less than about 5 microns, and at least 50% of the fibers have an average diameter greater than about 8 microns.