Lighting Device Thermal Management via Asymmetric LED Boards
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Solution Overview
Problem
In liquid crystal display apparatuses, heat tends to accumulate around the upper edge of the light guide plate due to the chimney effect, causing a temperature difference that leads to luminance unevenness and potential thermal expansion issues with the optical sheet, as well as exceeding the temperature rating of other components.
Innovation Solution
A lighting device design featuring a first light source unit with a low thermal conduction efficiency board and a second light source unit with a high thermal conduction efficiency board, where LEDs are positioned on both sides of the light guide plate, with the second unit having a higher thermal dissipation property to manage heat distribution effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If multiple LEDs are arranged on both the upper edge side and lower edge side of the light guide plate to increase luminance, then the luminance of the display apparatus is improved, but heat accumulates around the upper edge side due to the chimney effect, causing temperature difference and luminance unevenness
Solution Approach 1:
The patent applies local quality by assigning different thermal conduction characteristics to different parts of the system. Specifically, the lower edge side uses a light source board with high thermal conduction efficiency to actively dissipate heat, while the upper edge side uses a board with low thermal conduction efficiency to prevent heat accumulation. This localized differentiation of thermal properties resolves the temperature difference problem while maintaining high luminance output from both LED arrays.
2Temperature
If heat dissipation is enhanced at the lower edge side to counteract the chimney effect, then temperature difference is reduced, but the complexity of the lighting device increases due to different light source board designs
Solution Approach 1:
The patent resolves the complexity issue by applying local quality principles - each light source board is designed with specific thermal conduction characteristics suited to its location. The lower edge board incorporates high thermal conduction materials and structures targeted at heat dissipation, while the upper edge board uses low thermal conduction materials to prevent heat accumulation. This localized optimization achieves temperature uniformity without requiring a complete redesign of the entire lighting system.
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 design effectively suppresses the temperature difference between the upper and lower sides of the light guide plate, preventing luminance unevenness and thermal expansion issues, while ensuring the optical sheet and other components operate within safe temperature ranges.
Implementation Method 1
a second light source unit having a second light source row made up of a plurality of light sources aligned in a row, and a second light source board of relatively high thermal conduction efficiency, onto which the light sources making up the second light source row are mounted
Implementation Method 2
when the lighting device is erect, heat generated at the lower edge side travels to the upper edge side under influence of the chimney effect, and thus heat collects around the upper edge side of the light guide plate
Data Source
AI summary
A lighting device includes a first light source unit having a first light source row made up of a plurality of light sources, and a first light source board, onto which the light sources making up the first light source row are mounted, a second light source unit having a second light source row made up of a plurality of light sources, and a second light source board, onto which the light sources making up the second light source row are mounted, and a light guide plate having a plate-like shape and having a first light-incident face where light emitted from the light sources is incident, and a second light-incident face disposed on an opposite side from the first light-incident face where light emitted from the light sources is incident.