Display Panel with Cholesteric Reflectors for Brighter Immersive Devices
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Solution Overview
Problem
Polarization-based optical systems in personal immersive devices suffer from reduced brightness due to the transmission of only a portion of light through a polarizer.
Innovation Solution
A display panel design incorporating a reflective layer with varying thicknesses and pitches of cholesteric liquid crystals for each sub-pixel, along with differently thicknessed color filters and encapsulation layers, to selectively transmit and reflect different colors, enhancing light recycling and brightness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If polarization-based optical systems are used to reduce distance between user's eyes and display panel, then device miniaturization is achieved, but brightness is lowered due to light transmission loss through polarizer
Solution Approach 1:
The patent recovers light that would otherwise be lost by using a reflective layer with cholesteric liquid crystals to reflect specific wavelengths back through the color filter. This light recycling mechanism recovers approximately 50% of the light that would normally be discarded by the polarizer, thereby improving brightness without increasing device size.
Solution Approach 2:
The patent changes the optical parameters by using cholesteric liquid crystals with specific pitch values (e.g., 200-400 nm) that are tuned to reflect specific wavelengths. This parameter optimization enables selective reflection of wavelengths that enhance brightness while maintaining the compact polarization-based structure.
2Volume of moving object
If conventional polarizers are used to achieve polarization-based optical systems, then device miniaturization is achieved, but light loss occurs reducing brightness
Solution Approach 1:
Instead of allowing light to be discarded by the polarizer, the patent recovers it through a reflective layer with cholesteric liquid crystals that reflect specific wavelengths back through the color filter, converting the energy loss into a brightness enhancement.
Solution Approach 2:
The patent converts the harmful effect of light loss through the polarizer into a beneficial effect by using the reflected light to enhance brightness. The wavelength-selective reflection converts what would be wasted light into useful illumination.
3Illumination intensity
If additional light concentrating layers are added to improve brightness, then brightness is improved, but device complexity and size increase
Solution Approach 1:
The reflective layer with cholesteric liquid crystals serves multiple functions simultaneously: it acts as a wavelength-selective mirror, a light recycling mechanism, and integrates with the color filter system. This multi-functionality achieves brightness improvement without requiring separate dedicated light concentrating layers.
Solution Approach 2:
The patent merges the reflective function with the color filter assembly by positioning the cholesteric liquid crystal layer between the color filter and the electrode. This integration combines multiple optical functions into a single integrated structure, avoiding additional complexity.
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
The design improves brightness by recycling light through selective reflection and transmission, minimizing device size and reducing the need for additional light concentrating layers, while maintaining color accuracy.
Implementation Method 1
The reflective layer may include a first reflective portion disposed on the first sub-pixel, a second reflective portion disposed on the second sub-pixel, and a third reflective portion disposed on the third sub-pixel, wherein thicknesses of the first reflective portion to the third reflective portion are different. The first reflective portion to the third reflective portion may include cholesteric liquid crystals, and pitches of the cholesteric liquid crystals included in the first reflective portion to the third reflective portion may be different.
Implementation Method 2
The first reflective portion may selectively transmit and reflect red light corresponding to the pitch of the cholesteric liquid crystal, the second reflective portion may selectively transmit and reflect green light corresponding to the pitch of the cholesteric liquid crystal, and the third reflective portion may selectively transmit and reflect blue light corresponding to the pitch of the cholesteric liquid crystal.
Data Source
AI summary
An embodiment discloses a display panel including a substrate, a plurality of pixels including a first sub-pixel, a second sub-pixel, and a third sub-pixel disposed on the substrate, and a reflective layer including a first reflective portion disposed on the first sub-pixel, a second reflective portion disposed on the second sub-pixel, and a third reflective portion disposed on the third sub-pixel, wherein thicknesses of the first reflective portion to the third reflective portion are different, and a display device including the same.