Planar Illumination Device Frame Narrowing via Thermal Expansion Clearance
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Solution Overview
Problem
Existing planar illumination devices face challenges in narrowing the frame width due to the expansion and contraction of components like the light guide plate and optical sheets, which affects optical characteristics and makes frame narrowing difficult.
Innovation Solution
A planar illumination device configuration that includes a light guide plate, a light source, optical sheets, a bottom frame, and a top frame, where the end portion of the bottom frame's side wall forms a space with the top frame's frame portion to create a clearance for the optical sheets, allowing for further frame narrowing by optimizing the placement and adjustment of the side walls based on the anisotropic thermal expansion coefficients of the optical sheets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a clearance is provided between the side walls of the bottom frame and the light guide plate/optical sheet to accommodate thermal expansion, then the reliability is improved, but the frame width increases making frame narrowing difficult
Solution Approach 1:
The side walls are designed with different thicknesses at different locations. The first side walls have a first thickness while the second side walls have a second thickness that is different from the first, allowing different clearances to be provided in different regions. This enables the frame to accommodate thermal expansion in specific areas while maintaining a narrow overall frame width in other areas.
Solution Approach 2:
The invention changes the parameter of side wall thickness to control the clearance distribution. By adjusting the thickness of side walls at different positions, the design optimizes the balance between providing sufficient clearance for thermal expansion and achieving frame narrowing, resulting in a frame width that is 0.4 mm smaller than conventional designs.
2Length of stationary object
If the clearance is made small to achieve frame narrowing, then the frame width is reduced, but it becomes difficult to support the light guide plate and optical sheet during thermal expansion and contraction
Solution Approach 1:
Different regions of the frame are designed with different side wall thicknesses to provide localized support. The first and second side walls have different thicknesses, creating different clearance characteristics in different areas. This allows the frame to provide sufficient support stability in critical areas while maintaining narrow dimensions in other areas.
3Length of stationary object
If the side wall thickness is reduced to achieve frame narrowing, then the frame width is reduced, but the structural strength may be compromised
Solution Approach 1:
The side walls are designed with non-uniform thickness distribution. By strategically placing thicker sections where structural strength is needed and thinner sections where space is critical, the design achieves frame narrowing while maintaining necessary structural integrity. The different thicknesses of first and second side walls optimize both strength and compactness.
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 enables further frame narrowing while maintaining optimal optical characteristics, achieving a total frame narrowing of 0.4 mm by reducing the side wall thickness and clearance engagement between the bottom and top frames.
Implementation Method 1
components of the planar illumination device such as the light guide plate and the optical sheet expand and contract according to temperature
Implementation Method 2
the coefficient of linear thermal expansion of a Dual Brightness Enhancement Film (DBEF) often used as an optical sheet has anisotropy with respect to two perpendicular directions
Data Source
AI summary
A planar illumination device of an embodiment includes a light guide plate, a light source, one or more optical sheets, a bottom frame, and a top frame. The light guide plate receives light from a light incident side surface. The light source emits light to the light incident side surface of the light guide plate. The optical sheet is disposed on a light exit surface side of the light guide plate. The bottom frame houses the light guide plate, the light source, and the optical sheet. The top frame includes an opening, engages with the bottom frame and covers a light exit surface side of the optical sheet. An end portion on an opening side of a side wall of the bottom frame forms a space with a frame portion of the top frame, where the space corresponds to a clearance for an end portion of the optical sheet.