Backlights having selected output light flux distributions and display systems using same
Assignee3M Innovative Properties Company
InventorsJohn A. Wheatley, Michael A. Meis, Rolf W. Biernath, Philip E. Watson, Tao Liu
Life of this patent
Estimating the term…
Abstract
A backlight that includes a front reflector (120) and a back reflector (130) that form a hollow light recycling cavity including an output surface (104) is disclosed. At least a portion of the back reflector is non-parallel to the front reflector. The backlight also includes at least one semi-specular element disposed within the hollow light recycling cavity, and one or more light sources (140) disposed to emit light into the hollow light recycling cavity, where the one or more light sources are configured to emit light into the hollow light recycling cavity over a limited angular range.
Claims31
A backlight, comprising:
- a partially transmissive front reflector and a back reflector that form a hollow light recycling cavity comprising an output surface, wherein at least a first portion of the back reflector is non-parallel to the front reflector;
- at least one semi-specular element disposed within the hollow light recycling cavity;
- and
- one or more light sources disposed to emit light into the hollow light recycling cavity, wherein the one or more light sources are configured to emit light into the hollow light recycling cavity over a limited angular range.
A method of forming a backlight that is operable to provide a desired output light flux distribution, comprising:
- forming a hollow light recycling cavity comprising an output surface, wherein the hollow light recycling cavity further comprises a partially transmissive front reflector, a planar back reflector, and a semi-specular element disposed within the hollow light recycling cavity;
- positioning one or more light sources to emit light into the light recycling cavity over a limited angular range;
- selecting the desired output light flux distribution;
- measuring a first output light flux distribution;
- comparing the first output light flux distribution to the desired light flux distribution;
- shaping the back reflector or altering the reflective properties of the semi-specular element;
- measuring a second output light flux distribution;
- and
- comparing the second output light flux distribution to the desired output light flux distribution.
A display system, comprising:
- a display panel;
- and
- a backlight disposed to provide light to the display panel, the backlight comprising:
- a partially transmissive front reflector and a back reflector that form a hollow light recycling cavity comprising an output surface, wherein at least a first portion of the back reflector is non-parallel to the front reflector;
- at least one semi-specular element disposed within the hollow light recycling cavity;
- and
- one or more light sources disposed to emit light into the hollow light recycling cavity, wherein the one or more light sources are configured to emit light into the hollow light recycling cavity over a limited angular range.
Dependencies are inferred from the claim text.