Reflective Liquid Crystal Display With PBP Light Direction Control
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Solution Overview
Problem
Existing reflective liquid crystal display devices face challenges in maximizing light use efficiency, particularly when used in orientations other than the normal direction, leading to reduced brightness and limited control over emission light direction.
Innovation Solution
Incorporating a Pancharatnam-Berry phase diffraction grating (PBP) in the optical element, which includes a polarizer and a λ/4 plate, to control the direction of emission light and enhance light use efficiency by diffracting oblique incident light to the front, thereby increasing brightness and reducing liquid crystal misalignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a conventional reflective liquid crystal display device is used, then the device structure is simple, but light use efficiency is reduced when used in orientations other than the normal direction
Solution Approach 1:
The optical element is segmented into multiple functional layers: a polarizer layer, a quarter-wave plate layer, and a Pancharatnam-Berry phase diffraction grating layer. Each layer performs a specific optical function, allowing the system to efficiently control light in various viewing directions while maintaining overall structural organization.
Solution Approach 2:
The patent employs composite optical structures combining different optical materials and mechanisms (polarizer, wave plate, and geometric phase diffraction grating) to achieve enhanced light use efficiency. The composite structure leverages the complementary properties of each component to solve the viewing angle and efficiency problem.
2Illumination intensity
If no diffraction grating is used, then the device structure is simpler, but control over emission light direction is limited and brightness is reduced
Solution Approach 1:
The Pancharatnam-Berry phase diffraction grating utilizes geometric phase parameters (orientation angles of anisotropic elements) to control the direction of emitted light. By varying the orientation parameter across the grating structure, the system achieves precise directional control and enhanced brightness without requiring complex mechanical or structural adjustments.
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 PBP diffraction grating enhances light use efficiency by directing specularly reflected components to the front, improving brightness and reducing light scattering, while maintaining alignment of liquid crystal molecules.
Implementation Method 1
a Pancharatnam-Berry phase diffraction grating... to control the direction of emission light and enhance light use efficiency by diffracting oblique incident light to the front
Implementation Method 2
Pancharatnam-Berry phase diffraction grating... which enhances light use efficiency by directing specularly reflected components to the front
Implementation Method 3
an optical element disposed on or above an observer side of the reflective liquid crystal panel and including a polarizer and a Pancharatnam-Berry phase diffraction grating
Implementation Method 4
the optical element includes, in order from its reflective liquid crystal panel side toward its observer side, the polarizer, a λ/4 plate, and the Pancharatnam-Berry phase diffraction grating
Implementation Method 5
a slow axis of the polymerizable liquid crystal, in a plane of the phase difference layer, rotates periodically in an x-axis direction from a first end to a second end of the phase difference layer
Implementation Method 6
the molecular alignment pattern Φ(x) [°] as an alignment direction of the polymerizable liquid crystal at a position a distance x [μm] away in the x-axis direction
Implementation Method 7
the phase difference layer that introduces a phase difference Δnd satisfying the following Formula 1 or Formula 2 to wavelengths λ of 450 nm, 550 nm, and 650 nm
Data Source
AI summary
Provided is a reflective liquid crystal display device that can exhibit increased light use efficiency. The reflective liquid crystal display device includes a reflective liquid crystal panel and an optical element disposed on or above an observer side of the reflective liquid crystal panel and including a polarizer and a Pancharatnam-Berry phase diffraction grating. For example, the optical element may include, in order from its reflective liquid crystal panel side toward its observer side, the polarizer, a λ/4 plate, and the Pancharatnam-Berry phase diffraction grating. The Pancharatnam-Berry phase diffraction grating may include a phase difference layer that introduces a phase difference Δnd satisfying the following Formula 1 or Formula 2 to wavelengths λ of 450 nm, 550 nm, and 650 nm.sin4(Δndπλ)>14π(Formula 1)sin2(Δndπλ) cos2 (Δndπλ)>14π(Formula 2)