Stacked Surface Light Source Arrays for Local Dimming
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Solution Overview
Problem
Direct type backlight units face challenges in achieving local dimming due to the diffused light from the light guide panel, leading to difficulties in controlling brightness and maintaining contrast, especially with limited light sources and potential blooming and contrast issues on side surfaces.
Innovation Solution
A backlight unit design that stacks surface light sources, such as OLED arrays, to enhance local dimming capabilities by allowing individual control of surface light source blocks, improving resolution and contrast through precise light management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a direct type backlight unit uses a plurality of light sources arranged in a matrix formation, then local dimming capability is improved, but device complexity and cost increase
Solution Approach 1:
The backlight unit is divided into multiple independently controllable light source regions arranged in a matrix formation, allowing selective activation of specific regions for local dimming while managing complexity through modular segmentation
Solution Approach 2:
Different regions of the backlight unit are controlled with different brightness levels by selectively activating specific light sources, enabling local dimming where only certain areas are dimmed while others remain bright, thus improving adaptability without requiring all light sources to operate simultaneously
2Adaptability or versatility
If light sources are arranged in a matrix formation in a direct type backlight unit, then local dimming is enabled, but blooming phenomenon occurs and contrast on side surface decreases
Solution Approach 1:
A light guide panel is introduced as an intermediary component between the matrix-formed light sources and the display panel. This light guide panel redirects and distributes light to reduce direct interference between adjacent light sources, thereby minimizing blooming phenomenon and improving side surface contrast while preserving local dimming capability
Solution Approach 2:
The patent transitions from a conventional edge-type light source arrangement to a direct-type matrix arrangement with light sources positioned at multiple heights, utilizing the vertical dimension to create layered light emission that reduces lateral light interference and improves contrast
3Length of stationary object
If edge type backlight unit is used to reduce thickness, then device thickness is reduced, but local brightness control becomes difficult
Solution Approach 1:
The single edge light source is segmented into multiple light sources arranged in a matrix formation within the direct type backlight unit, enabling independent control of each light source region while maintaining a thin profile through optimized light source positioning and light guide design
Solution Approach 2:
The patent transitions from edge-type to direct-type configuration with light sources positioned at multiple heights, utilizing the vertical dimension to achieve both thinness and local brightness control capability
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 stacking of surface light sources enables enhanced resolution and contrast in local dimming by allowing for precise control of light emission, overcoming the limitations of traditional direct type backlight units and improving image quality.
Implementation Method 1
an organic light emitting diode which includes an anode, a cathode, and an organic compound layer interposed between the anode and the cathode
Data Source
Figure 1~4
Figure 5~7
Figure 8~11a
AI summary
A backlight unit is provided. The backlight unit includes: a first surface light source array; a second surface light source array disposed on an upper portion of the first surface light source array and arranged such that a light emitting surface of the second surface light source array is parallel with a light emitting surface of the first surface light source array; and a reflection plate disposed on a lower portion of the first surface light source array and arranged such that a reflective surface of the reflection plate is parallel with the light emitting surface of the first surface light source array, wherein the second surface light source array is stacked on the first surface light source array such that the first and second surface light source arrays are offset from each other in a plane parallel to the light emitting surfaces.