Backlight Unit Optical Sheet Positioning for Thermal Expansion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In liquid crystal display (LCD) backlight units, optical sheets deform due to heat expansion, leading to changes in distance between the sheets and the light guide plate, which can cause display failures, and existing methods to secure these sheets compromise their ability to accommodate expansion.
Innovation Solution
A backlight unit design featuring optical sheets with extensions that protrude from their edges, where inner and outer surface position defining portions on the receiving member securely fasten the sheets, allowing for sufficient expansion while maintaining a precise location, with a ratio of distances between these defining portions ranging from 1:3 to 1:6.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the optical sheets are tightly secured within the backlight unit to prevent movement, then the stability of the optical sheet position is improved, but the ability to accommodate heat expansion of the optical sheets deteriorates
Solution Approach 1:
The optical sheet is divided into a body portion and a protrusion extending from its edge. The protrusion acts as a separate element that engages with the receiving member to provide positioning without constraining the main body of the optical sheet, allowing the sheet to expand while maintaining position stability.
Solution Approach 2:
The protrusion serves as an intermediary element between the optical sheet and the receiving member. It provides the positioning function by engaging with the receiving member's inner surface position defining portion, while the optical sheet body remains free to expand into the space defined by the outer surface position defining portion.
2Adaptability or versatility
If the distance between the optical sheet and the frame is increased to accommodate expansion, then the adaptability to heat expansion is improved, but the precision of the optical sheet location deteriorates
Solution Approach 1:
The positioning system is segmented into two distinct functions: the inner surface position defining portion that provides precise location through engagement with the protrusion, and the outer surface position defining portion that provides expansion space. This segmentation allows both precision and adaptability to coexist.
Solution Approach 2:
Different regions of the receiving member have different functional qualities: the inner surface position defining portion provides precise positioning with minimal clearance, while the outer surface position defining portion provides larger clearance for expansion. This local differentiation of quality allows the system to achieve both precision and adaptability.
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 prevents optical sheet deformation by allowing for heat-induced expansion while securely fastening the sheets, ensuring consistent optical properties and preventing display failures.
Implementation Method 1
Heat is generated from the light source during an operation of the backlight unit, thereby increasing the temperature of the backlight unit. Thin optical sheets experience changes in length by heat expansion.
Data Source
AI summary
A backlight unit includes an optical sheet, a receiving member configured to receive the optical sheet, the receiving member having a support surface supporting the optical sheet, an extension configured to protrude from a side surface of the optical sheet, an inner surface position defining portion configured to define a location of the optical sheet, the inner surface position defining portion being substantially perpendicular to the support surface of the receiving member and facing an inner surface of the extension, and an outer surface position defining portion substantially perpendicular to the supporting surface of the receiving member and facing an outer surface of the extension, wherein a first distance between the inner surface position defining portion and the inner surface of the extension is less than a second distance between the outer surface position defining portion and the outer surface of the extension.