Uniformly Polarized Backlight With Prism-Based Light Recovery
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Solution Overview
Problem
Conventional LCD devices suffer from polarization losses that reduce brightness and cause inefficiencies, with non-uniform polarization leading to brightness and contrast variations, and autostereoscopic displays experience further brightness reduction due to light division into multiple viewing zones.
Innovation Solution
A backlight unit with collimated light emission and a prism system that separates and aligns both polarization components, combined with a half-wave plate to rotate polarization orientation, ensuring uniform illumination across the LCD panel, and a liquid crystal layer for individual control of light polarization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional backlight units generate unpolarized light and pass through a polarizer, then the required polarization state is achieved, but approximately half of the emitted light is discarded causing substantial energy loss and reduced brightness
Solution Approach 1:
The invention segments the backlight unit into multiple independent light-emitting elements, each equipped with its own collimator and polarization control components. This segmentation allows each element to independently generate and control polarized light, eliminating the need for a single lossy polarizer and enabling utilization of both polarization components across the display panel.
Solution Approach 2:
The invention changes the polarization state parameter by using half-wave plates in each light-emitting element to rotate the polarization orientation. This allows dynamic control over the polarization state, enabling both s-polarized and p-polarized light to be effectively utilized and directed toward the LCD panel, thereby eliminating polarization losses.
2Stability of the object's composition
If conventional LCD devices use secondary polarizers and additional optical elements to achieve uniform polarization, then polarization uniformity is improved, but optical inefficiencies increase and system performance decreases
Solution Approach 1:
The invention performs preliminary polarization control by integrating collimators and half-wave plates directly into each light-emitting element before the light enters the LCD panel. This preliminary action ensures that both s-polarized and p-polarized light are properly oriented and utilized from the source, eliminating the need for secondary polarizers and additional optical elements that would otherwise be required to correct polarization non-uniformity.
3Adaptability or versatility
If autostereoscopic display systems divide light into multiple viewing zones using parallax barriers or lens arrays, then multiple viewing angles are achieved, but brightness intensity per zone is reduced
Solution Approach 1:
The invention segments the backlight into multiple independent light-emitting elements, each capable of generating fully polarized light. This segmentation, combined with the polarization control in each element, ensures that sufficient brightness is maintained in each viewing zone while still enabling autostereoscopic functionality through the properly oriented polarized light.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enhances brightness and maintains uniform polarization, reducing power consumption and improving image quality by directing both polarization components towards the LCD panel, thus achieving high luminance and efficient light utilization.
Implementation Method 1
a collimator arranged on an optical path of light rays emitted in an individual one of the at least one direction, to collimate the light rays
Implementation Method 2
a first prism arranged on said optical path after the collimator, configured to reflect a given portion of the collimated light rays having one of a first polarization orientation and a second polarization orientation along the optical axis of the backlight unit and to transmit another portion of the collimated light rays having another of the first polarization orientation and the second polarization orientation
Implementation Method 3
a half-wave plate arranged on said optical path after the first prism, configured to rotate a polarization orientation of the another portion of the collimated light rays from the another of the first polarization orientation and the second polarization orientation to the one of the first polarization orientation and the second polarization orientation
Implementation Method 4
a second prism arranged on said optical path after the half-wave plate, configured to reflect the another portion of the collimated light rays having the one of the first polarization orientation and the second polarization orientation along the optical axis of the backlight unit
Data Source
AI summary
A backlight unit for a liquid crystal display device includes an array of light-emitting elements. Each element includes a light source configured to emit light laterally relative to an optical axis of the backlight unit. A collimator is arranged on an optical path of emitted light rays in at least one direction to collimate the light rays. A first prism is positioned after the collimator to reflect a portion of the collimated light rays with one polarization orientation along the optical axis and transmit another portion with the opposite polarization orientation. A half-wave plate, arranged after the first prism, rotates the polarization of the transmitted light. A second prism, positioned after the half-wave plate, reflects the rotated light along the optical axis.