Planar Lighting Backlight Uniformity Control via Segmented Regions
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Solution Overview
Problem
Conventional liquid crystal display apparatuses face challenges in maintaining uniform luminance and color temperature across the backlight surface due to temperature variations and uneven distribution of LEDs, leading to luminance and color unevenness, which are difficult to correct with existing solutions that require multiple sensors and increased costs.
Innovation Solution
A planar lighting apparatus with a divided light emitting surface, utilizing a first temperature sensor inside the housing and a second temperature sensor outside to measure ambient temperature, along with an optional color sensor, to calculate and correct the driving conditions of each light emitting region, ensuring uniform luminance and color temperature without a sharp increase in cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple temperature sensors and color sensors are deployed to measure and correct luminance and color unevenness, then the uniformity of luminance and color temperature is improved, but the device complexity and cost increase sharply
Solution Approach 1:
The light emitting surface is divided into multiple regions (first light emitting region and second light emitting region) with different color temperatures. This segmentation allows independent control of each region to compensate for temperature-induced color shifts without requiring multiple sensors throughout the entire backlight unit.
Solution Approach 2:
Different regions of the light emitting surface are assigned different color temperatures (first color temperature for first region, second color temperature for second region). This local quality variation enables targeted correction of luminance and color unevenness in specific areas affected by temperature gradients.
2Device complexity
If LEDs are distributed unevenly or temperature varies across the backlight surface, then the structure simplicity is maintained, but luminance unevenness and color unevenness occur
Solution Approach 1:
The backlight unit is divided into multiple light emitting regions with distinct color temperature zones. This segmentation strategy maintains structural simplicity by using a single LED type while creating functional regions that can be independently controlled to achieve uniform visual output.
Solution Approach 2:
The patent changes the color temperature parameter across different regions of the light emitting surface. By varying color temperature (first color temperature vs. second color temperature) in different zones, the system compensates for temperature-induced color shifts and maintains color uniformity without complex structural modifications.
3Device complexity
If a single color temperature is used across the entire light emitting surface, then the device complexity is reduced, but color unevenness occurs under temperature variations
Solution Approach 1:
Different regions emit light at different color temperatures to match their local thermal conditions. The first light emitting region operates at a first color temperature while the second light emitting region operates at a second color temperature, ensuring each region maintains appropriate color characteristics under its specific thermal environment.
Solution Approach 2:
The patent implements parameter changes by varying the color temperature across different spatial regions. This approach maintains relatively simple device control while achieving color uniformity through strategic parameter variation rather than uniform settings throughout the entire backlight unit.
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 maintains uniform luminance and color temperature across the backlight surface, reducing luminance and color unevenness while minimizing the number of sensors and components, thus lowering costs and improving control complexity.
Implementation Method 1
a first temperature sensor disposed inside of the first housing
Implementation Method 2
a second temperature sensor disposed outside of the first housing and inside of the second housing
Implementation Method 3
LEDs are changed due to temperature not only in an amount of light emission, but also in emission spectrum
Data Source
AI summary
Provided are a planar lighting apparatus, a liquid crystal display apparatus, and a planar light source. The planar lighting apparatus includes a planar light source including light emitting elements, a first housing, a light emitting surface divided into light emitting regions, and a first temperature sensor disposed inside of the first housing. The planar lighting apparatus further includes a second housing covering the planar light source; a second temperature sensor disposed outside of the first housing and inside of the second housing; a light-source drive circuit including light-source drive section each driving and controlling the light emitting elements belonging to the corresponding light emitting region; a memory section; and a computing section calculating a driving condition of each light-source drive section and correcting the driving condition on the basis of measurement values of the first temperature sensor and the second temperature sensor, and setup information in the memory section.