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US 2021/0231844 A1Published application
Multilayer reflector
Assignee3M Innovative Properties Company
InventorsGilles J. Benoit, Matthew B. Johnson
Life of this patent
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Abstract
Multilayer reflectors are described. In particular, multilayer reflectors that partially transmit blue light and reflect green and red light are described. The multilayer reflectors have good efficiency and color performance in a backlight including a downconverting material.
Claims20
A multilayer optical reflector, comprising:
- a plurality of optical repeat units, each optical repeat unit having a total optical thickness and including a birefringent polymer and a second polymer and having a f-ratio, defined as the ratio of an optical thickness of the birefringent polymer to the total optical thickness of the optical repeat unit;
- wherein the plurality of optical repeat units are configured such that a blue hemispheric reflectivity for unpolarized light averaged over the range from 420 to 480 nm is less than 55%;
- and
- wherein the plurality of optical repeat units are configured such that a red-green hemispheric reflectivity for unpolarized light averaged over the range from 520 to 650 nm is greater than 97%.
1 more element
An extended area light source, comprising:
- a blue light source, wherein the blue light source has a maximum emitted wavelength between 420 nm and 480 nm;
- a downconverting material, wherein the downconverting material absorbs light emitted from the blue light source and reemits light having a wavelength between 550 and 800 nm;
- and
- the multilayer optical reflector of any of the preceding claims, wherein the multilayer optical reflector is disposed in an optical path between the blue light source and the downconverting material.
1 more element
Dependencies are inferred from the claim text.