Reflection Sheet Fixing for Planar Illumination Wrinkle Control
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Solution Overview
Problem
Planar illumination devices with fully fixed reflection sheets suffer from wrinkles due to temperature and humidity changes, leading to non-uniform brightness and deteriorated brightness distribution, particularly in frame-size reduction applications.
Innovation Solution
A planar illumination device design where only the end portion of the reflection sheet is fixed to the floor surface using a fixing member, allowing for controlled stretching and preventing wrinkles, while maintaining uniform brightness distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If all sides of the reflection sheet are fixed to the frame or light guide plate, then the reflection sheet is securely positioned, but wrinkles occur on the reflection sheet due to shrink and stretch with temperature and humidity changes, causing non-uniform brightness
Solution Approach 1:
The fixing of the reflection sheet is segmented into two parts: one side is fixed to the frame for stable positioning, while the other side is fixed to the light guide plate at only one position (one-side fixing) to allow thermal expansion and contraction without generating wrinkles. This segmentation resolves the contradiction by providing both positioning stability and brightness uniformity.
Solution Approach 2:
Different fixing methods are applied to different sides of the reflection sheet based on their functional requirements. The side facing the frame uses complete fixing for stability, while the side facing the light guide plate uses one-side fixing to prevent wrinkle formation. This local differentiation of fixing quality resolves the contradiction between stable positioning and brightness uniformity.
2Reliability
If the reflection sheet is fixed with all sides to ensure stable positioning, then positioning is stable, but brightness distribution deteriorates due to wrinkles caused by thermal expansion and contraction
Solution Approach 1:
The reflection sheet fixing is segmented such that one side is fully fixed to the frame for reliable positioning, while the other side is partially fixed (one-side fixing) to the light guide plate to maintain brightness distribution. This segmentation allows the system to achieve both positioning reliability and proper brightness distribution.
Solution Approach 2:
The fixing structure is made dynamic by allowing one side of the reflection sheet to move freely (not fully fixed) in response to thermal expansion and contraction. This dynamic approach prevents wrinkles that would otherwise deteriorate brightness distribution while maintaining positioning reliability through the fixed side.
3Area of stationary object
If frame size is reduced to meet design requirements, then device compactness is improved, but stabilizing brightness distribution around the frame becomes more difficult
Solution Approach 1:
The reflection sheet fixing is segmented with one-side fixing to the light guide plate, which prevents wrinkle formation and maintains brightness distribution stability even in reduced frame sizes. This segmentation allows compact design while preserving illumination quality.
Solution Approach 2:
The fixing parameter is changed from complete fixing to one-side fixing, which alters the mechanical constraints on the reflection sheet. This parameter change enables the system to maintain brightness distribution stability in smaller frames by allowing thermal movement without wrinkle formation.
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
Prevents the occurrence of non-uniform brightness and deterioration of brightness distribution on the light-emitting surface, enabling more accurate and stable illumination while reducing frame size.
Implementation Method 1
a reflection sheet that is disposed in the main surface side of the light guide plate and reflects light
Data Source
AI summary
A planar illumination device according to an embodiment includes: a light guide plate that guides an incident light from a side surface; a light source that is disposed in the side surface side and emits light incident to the side surface; a frame that has a floor surface extending along a main surface of the light guide plate and accommodates the light guide plate and the light source; a reflection sheet that is disposed in the main surface side of the light guide plate and reflects light; and a first fixing member that is disposed between the reflection sheet and the floor surface and fixes at least a part of an end portion of the reflection sheet in the light source side to the floor surface.