Display laminate with single packet biaxially birefringent reflective polarizer
Multilayer optical film reflective polarizers previously considered to have excessive off-axis color can provide adequate performance in an LC display without any high haze light diffusing layer or air gap between the reflective polarizer and the back absorbing polarizer of the display. The reflective polarizer has only one packet of microlayers, and is oriented using a standard tenter such that birefringent microlayers in the film are biaxially birefringent. The microlayers in the packet have a layer thickness profile suitably tailored to avoid excessive perceived color at normal and oblique angles. A laminate made by combining this type of reflective polarizer with an absorbing polarizer, without an air gap or any high haze light diffusing layer or structure between the polarizers, can be used and incorporated into a liquid crystal display or the like with adequate color performance both at normal incidence and oblique incidence up to a polar angle of 60 degrees.
1. A display, comprising:
a liquid crystal panel; and
a reflective polarizer attached to the liquid crystal panel with no air gap therebetween, the reflective polarizer comprising a coherent grouping of a plurality of microlayers reflecting and transmitting light by optical interference, such that for substantially normally incident light and for at least one wavelength in a first wavelength range from 450 nm to 700 nm, the plurality of microlayers substantially reflects the incident light polarized along a block axis and substantially transmits the incident light polarized along an orthogonal pass axis, and such that for light incident at 60 degrees and linearly polarized in a plane of incidence of the incident light and for a second wavelength range from 400 nm to 700 nm, the plurality of microlayers:
transmits between 70% to 90% of the incident light for at least one wavelength in the second wavelength range; and
has a high frequency spectral variability of less than 0.08 over the second wavelength range.
2. The display of claim 1 further comprising an absorbing polarizer attached to the reflective polarizer with no air gap therebetween, the absorbing polarizer having a pass axis substantially aligned with the pass axis of the reflective polarizer.
3. The display of claim 2 , wherein the absorbing polarizer is disposed between the liquid crystal panel and the reflective polarizer.
4. The display of claim 1 , wherein the coherent grouping of a plurality of microlayers comprises a plurality of alternating first and second microlayers, the first microlayers being biaxially birefringent, the second microlayers being substantially isotropic.
5. The display of claim 1 , wherein the reflective polarizer is attached to a glass layer of the liquid crystal panel.
6. The display of claim 1 , wherein the high frequency spectral variability is a standard deviation of a spectral transmission of the plurality of microlayers relative to a best fit curve of the form a 0 +a 1 λ+a 2 λ 2 +a 3 λ 3 .
7. The display of claim 1 , wherein the high frequency spectral variability is less than 0.05.
8. The display of claim 1 , wherein the high frequency spectral variability is at least 0.01.
9. The display of claim 1 , wherein an adhesive layer attaches the reflective polarizer to the liquid crystal panel.