Stacked Cholesteric Liquid Crystal Layers for Blue Light Filtering
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Solution Overview
Problem
Liquid crystal display devices emit blue light, which can cause eye strain and sleep disorders due to its properties of reaching the retina without being absorbed by the cornea or lens, and existing solutions like blue light blocking layers can affect display quality by blocking necessary blue components of visible light.
Innovation Solution
A liquid crystal display device configuration using stacked cholesteric liquid crystal layers that reflect left-handed and right-handed circularly polarized blue light, allowing only non-blue light to reach the display panel, thereby reducing blue light emission while maintaining high display quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a resin layer (blue light blocking layer) is overlapped on the display surface or back surface to reduce blue light, then blue light emission is reduced, but display quality deteriorates due to blocking of necessary blue components of visible light
Solution Approach 1:
The invention divides the blue light blocking function into two separate liquid crystal devices, each handling one type of circularly polarized light. The first device blocks left-handed circularly polarized blue light while transmitting right-handed, and the second device blocks right-handed circularly polarized blue light while transmitting left-handed. This segmentation allows selective blocking of harmful blue light components without affecting display quality, as each device operates on a specific polarization state.
Solution Approach 2:
The invention applies different optical properties to different parts of the system by using two distinct liquid crystal devices with opposite chiralities. Each device is positioned at a specific location in the stacked configuration, with the first device having positive birefringence and the second having negative birefringence. This local differentiation enables selective blue light blocking while maintaining overall display performance.
2Use of energy by moving object
If white LED is used as light source, then broad spectrum light is provided, but harmful blue light components are included in the emitted light
Solution Approach 1:
The invention converts the harmful blue light emitted by white LEDs into a beneficial filtering opportunity. By using stacked liquid crystal devices with selective circular polarization reflection, the harmful blue light components are reflected back through the light guide to the LED, converting potential harm into an opportunity for selective wavelength filtering. This allows the white LED's broad spectrum emission to be utilized while eliminating the harmful blue components.
Solution Approach 2:
The light guide serves as an intermediary element between the white LED and the liquid crystal devices. It transports the broad spectrum light from the LED to the liquid crystal filters, and also reflects the blocked blue light back to the LED. This intermediary structure enables the conversion of harmful blue light into a controllable filtering process without losing the beneficial broad spectrum characteristics of the white LED.
3Object-affected harmful factors
If blue light is blocked to protect eye health, then eye strain and sleep disorders are reduced, but the overall visible light spectrum is compromised
Solution Approach 1:
The invention segments the visible light spectrum handling by separating blue light blocking from the main display function. Two dedicated liquid crystal devices are stacked specifically for blue light filtering, while the main liquid crystal display panel handles the display function using the remaining visible spectrum. This segmentation protects eye health by blocking blue light while preserving the完整性 of the visible light spectrum for display purposes.
Solution Approach 2:
The stacked liquid crystal devices act as intermediary filters between the light source and the display panel. They selectively remove harmful blue light components while allowing the rest of the visible spectrum to pass through to the display panel, thus protecting eye health without compromising the overall illumination quality and color representation of the display.
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 solution effectively reduces blue light emission, minimizing eye strain and sleep disorders while ensuring high display quality by selectively reflecting blue light and allowing other wavelengths to be used for display operations.
Implementation Method 1
a first cholesteric liquid crystal layer sandwiched between the first substrate and the second substrate... the first cholesteric liquid crystal layer reflects one of left-handed circularly polarized light and right-handed circularly polarized light, of light in a blue light wavelength range, in a planar state
Data Source
AI summary
According to one embodiment, a liquid crystal display device includes a first liquid crystal device, a second liquid crystal device, and a liquid crystal display panel, the first liquid crystal device including a first substrate including a first electrode thereon, a second substrate including a second electrode thereon, and a first cholesteric liquid crystal layer, the second liquid crystal device including a third substrate including a third electrode thereon, a fourth substrate including a fourth electrode thereon, and a second cholesteric liquid crystal layer, wherein the first liquid crystal device and the second liquid crystal device are stacked successively.