Tunable Grating Backlight for Local Dimming
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Solution Overview
Problem
Conventional LCDs with single uniform backlights face inefficiencies in power consumption and image quality due to the need for constant illumination across the entire screen, whereas those with local dimming capabilities require multiple light sources and complex optical designs, limiting scalability and zone count.
Innovation Solution
A two-dimensional local dimming backlight system featuring edge-arranged light sources and a tunable grating layer with independently controllable cells, allowing for selective light extraction and reduced power consumption by only illuminating regions of the screen displaying content, while maintaining improved image quality and scalability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single uniform backlight is used, then the device complexity is reduced, but the power consumption efficiency and image quality deteriorate
Solution Approach 1:
The backlight is segmented into multiple independently controllable zones using a tunable grating layer with multiple rows of cells. Each cell can be independently activated or deactivated, allowing the backlight to be divided into distinct functional regions that can be controlled separately, thereby improving power consumption efficiency without requiring multiple separate light sources.
Solution Approach 2:
The grating layer is made dynamically tunable through liquid crystal material that can change its optical properties in response to applied voltage. This dynamic control allows the backlight to adapt its light extraction characteristics in real-time, enabling localized dimming and improving power efficiency while maintaining a single uniform backlight structure.
2Use of energy by moving object
If multiple light sources are used for local dimming, then the power consumption efficiency and image quality improve, but the device complexity and optical design complexity increase
Solution Approach 1:
The tunable grating layer serves multiple functions simultaneously: it acts as a waveguide for light propagation, a diffraction grating for light extraction, and a spatial modulator for local dimming control. This multi-functionality eliminates the need for separate optical components typically required in conventional local dimming systems, reducing optical design complexity while maintaining power efficiency benefits.
Solution Approach 2:
The patent merges the waveguide function and the light extraction function into a single integrated structure. The grating layer is formed within the waveguide itself, combining what would traditionally be separate components into one unified element, thereby simplifying the optical design while enabling local dimming capabilities.
3Adaptability or versatility
If multiple light sources are used for local dimming, then the zone count improves, but the scalability and ease of manufacture deteriorate
Solution Approach 1:
The grating layer is segmented into multiple rows of cells that can be independently controlled, enabling high zone counts. This segmentation is achieved through a systematic pattern formation process that can be scaled to different display sizes and resolutions, maintaining ease of manufacture while increasing adaptability and zone count.
Solution Approach 2:
The number of zones and their dimensions can be adjusted by changing the grating period and cell size parameters during fabrication. This parameter-based control allows the same manufacturing process to produce different zone configurations for various display sizes and applications, improving scalability while maintaining high zone counts.
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
This solution enables reduced power consumption, enhanced image quality, and increased zone counts through efficient light extraction and control, addressing the limitations of single uniform backlights and complex optical designs in conventional LCDs.
Implementation Method 1
a tunable grating layer coupled to a first surface of the waveguide layer... each cell being independently controllable to extract incident light received from within the waveguide layer through the tunable grating layer
Data Source
AI summary
Methods, systems, apparatuses, and computer program products are provided for a backlight assembly for a display device. The backlight assembly includes a transparent waveguide layer, a plurality of light sources, and a tunable grating layer. The light sources are arranged along an edge of the waveguide layer. Each light source transmits light into the waveguide layer through the edge. The grating layer is coupled to the waveguide layer, and has multiple rows. Each row of the grating layer is segmented into a series of cells so the grating layer is sectioned into an array of cells. Each cell is independently controllable to either not extract incident light received from within the waveguide layer, or to extract the incident light for emission from the backlight assembly. In another configuration, the waveguide layer is not present, and the light sources transmit light directly into an edge of the grating layer.