Display Device Optical Sheet Undulation Control
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Solution Overview
Problem
Liquid crystal display devices with a direct-under type LED backlight experience image quality degradation due to undulation in the optical sheet, particularly when two panels are superimposed, as the increased light amount compensates for decreased light transmittance, leading to conspicuous undulation and reduced image quality.
Innovation Solution
The display device incorporates a structure with a transparent substrate and optical sheet separated by spacer members, restricting movement in the Z-axis direction, allowing the optical sheet to maintain a free outer peripheral end and absorb thermal stress, thereby preventing undulation and enhancing image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the light amount of the backlight is increased to compensate for decreased light transmittance in dual-panel superimposition, then the contrast ratio is improved, but the undulation of the optical sheet becomes more conspicuous
Solution Approach 1:
The patent divides the support structure into multiple components: a first support member holding the display panel, a second support member holding the optical sheet, and a third support member accommodating LEDs. This segmentation allows independent positioning and stress distribution, preventing the optical sheet from contacting the panel support directly, thereby eliminating undulation while maintaining high light output for improved contrast ratio.
Solution Approach 2:
The patent introduces a third support member as an intermediary structure between the display panel and the optical sheet. This intermediary component (the frame body accommodating LEDs) acts as a mediator that prevents direct contact between the optical sheet and panel support, eliminating the source of undulation while still allowing the backlight to provide sufficient illumination for high contrast ratio.
2Illumination intensity
If two liquid crystal display panels are superimposed to improve contrast ratio, then the contrast ratio is improved, but the light transmittance decreases requiring higher backlight intensity
Solution Approach 1:
The patent segments the support structure into distinct members for the display panel and optical sheet, allowing the optical sheet to be positioned independently without being compressed against the panel support. This maintains optimal light transmission pathways through the optical sheet while supporting the dual-panel configuration needed for high contrast ratio.
3Use of energy by moving object
If the optical sheet is disposed close to the display panel to improve light efficiency, then the light transmittance is improved, but the optical sheet contacts the panel support causing undulation
Solution Approach 1:
The third support member (frame body) serves as an intermediary structure that enables the optical sheet to be positioned close to the display panel for efficient light transmission, while simultaneously preventing direct contact between the optical sheet and panel support. The spacer members attached to the frame body maintain appropriate spacing, eliminating undulation while preserving light efficiency.
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 configuration effectively prevents undulation in the optical sheet, maintaining image quality by allowing the optical sheet to relax thermal stress and maintain a constant distance, thus improving the contrast ratio and overall display performance.
Implementation Method 1
allowing the optical sheet to maintain a free outer peripheral end and absorb thermal stress, thereby preventing undulation
Data Source
AI summary
A display device includes: a first frame including a frame portion covering a peripheral portion of a display panel; a second frame including a panel support sandwiching the display panel with the frame portion; an optical sheet being opposite to the display panel in a first direction, an outer peripheral end of the optical sheet being opposite to the panel support; a transparent substrate on which the optical sheet is disposed; a third frame including a main body having an accommodation space accommodating light emitting elements, and a substrate support extending from the main body to support the transparent substrate; and spacer members disposed between the panel support and the substrate support. The optical sheet and the panel support are disposed with a space interposed therebetween in the first direction, and each spacer member includes a restriction unit restricting movement of the transparent substrate in the first direction.