Optical Sheet Holding Structure for Display Luminance Stability
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Solution Overview
Problem
Display apparatuses using liquid crystal panels face issues with uneven luminance and luminance degradation due to wrinkling or bending of optical sheets caused by thermal expansion, which can lead to breakage, especially under vibration or transportation conditions.
Innovation Solution
An optical sheet holding structure featuring a flat and hollow holding surface with engaging parts that include a base standing on the surface and an engagement piece extending parallel to it, where the base and engagement hole lengths are matched to prevent in-plane and thickness direction movement, ensuring stable positioning and reducing the risk of wrinkling or bending.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the optical sheet is held with a gap between the hole and positioning pin to accommodate thermal expansion, then the optical sheet can be easily assembled and thermal expansion is accommodated, but the optical sheet can move in-plane and in the thickness direction causing positional shift and fluctuation
Solution Approach 1:
The positioning pin is divided into two functional segments: a first positioning portion with a diameter matching the hole size to prevent in-plane movement, and a second positioning portion extending in the thickness direction to prevent out-of-plane movement. This segmentation allows each portion to address a specific degree of freedom, resolving the contradiction between assembly ease and positioning precision.
Solution Approach 2:
The positioning solution transitions from two-dimensional in-plane positioning to three-dimensional positioning by adding the thickness direction component. The first positioning portion handles in-plane positioning while the second positioning portion handles thickness direction positioning, thereby eliminating positional shift and fluctuation in all directions.
2Ease of operation
If the frame is narrowed to achieve slimmed border, then the display apparatus becomes more compact and modern, but the residual portion outside the hole becomes significantly narrower making the optical sheet vulnerable to breakage under vibration
Solution Approach 1:
The positioning pin applies localized support precisely at the hole location where the optical sheet is most vulnerable. By concentrating the positioning function at this critical point with dual positioning portions, the structure provides enhanced local reinforcement without requiring overall frame widening, thus maintaining aesthetic quality while improving reliability.
Solution Approach 2:
The positioning pin structure provides preemptive protection by firmly securing the optical sheet at the vulnerable hole location before vibration or external forces are applied. The dual-positioning design anticipates potential breakage risks and prevents them through prior mechanical reinforcement at the critical residual portion.
3Manufacturing precision
If positioning pins are used to hold the optical sheet, then the optical sheet is positioned and held, but the optical sheet can still move in the thickness direction causing fluctuation and potential wrinkling or bending
Solution Approach 1:
The positioning pin is segmented into two distinct functional portions: the first positioning portion (diameter matching hole size) constrains in-plane movement, while the second positioning portion (extending in thickness direction) constrains out-of-plane movement. This segmentation comprehensively addresses all movement degrees of freedom, ensuring both positioning accuracy and structural stability.
Solution Approach 2:
The positioning pin serves multiple functions simultaneously: it acts as both an in-plane positioning element and a thickness direction positioning element. This multi-functionality eliminates the need for separate positioning mechanisms and ensures comprehensive stabilization of the optical sheet against all types of movement.
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 prevents wrinkling, bending, and breakage of optical sheets, maintaining uniform luminance and enhancing the structural integrity of the display apparatus by accurately positioning and stabilizing the optical sheet, even under conditions of thermal expansion and vibration.
Implementation Method 1
The optical sheet is thermally expanded due to heat principally from the light source
Data Source
AI summary
Provided are an optical sheet holding structure capable of preventing an optical sheet from wrinkling and bending in a display apparatus, and from breakage during a vibration test, thereby preventing occurrence of problems such as uneven luminance, luminance degradation and the like, and a display apparatus including the optical sheet holding structure.A chassis for holding an optical sheet includes an engaging part for engaging the optical sheet. The engaging part includes a base provided to stand on a surface of a holding plate for the optical sheet orthogonally to the holding plate and in the thickness direction of the holding plate, and an engaging portion extending substantially parallel to a holding surface from the front edge of the base toward the outside of the frame of the chassis. A distance between the holding surface of the holding plate for the optical sheet and the surface of the engaging piece facing the holding surface is substantially equal to the thickness of the optical sheet. The cross-section of the base of a central engaging part is formed into a shape substantially identical to the shape of an engagement hole provided in the optical sheet.