Planar Illumination Plate Spring Heat Expansion
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Solution Overview
Problem
Existing planar illumination apparatuses using rubber supports for light guide plates face issues with heat expansion, leading to uneven luminance due to creases on optical sheets, and low reliability against heat, as the rubber pushes up the optical sheet when expanding perpendicular to the light emitting surface.
Innovation Solution
A planar illumination apparatus with a plate spring made of stainless steel is provided between the light guide plate and the frame, pressing the light guide plate in two directions that are different from the direction of heat expansion, preventing the optical sheet from being pushed up and maintaining optical stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a rubber-made supporting portion is used to support the light guide plate, then the light guide plate is supported and movement is suppressed, but the supporting portion expands by heat in a direction perpendicular to the light emitting surface, pushing up the optical sheet and causing creases
Solution Approach 1:
The patent changes the material parameter from rubber to plate spring, and changes the expansion behavior parameter from perpendicular expansion to in-plane expansion. The plate spring expands in the plane of the light guide plate rather than perpendicular to it, preventing optical sheet creases while maintaining support stability.
Solution Approach 2:
The patent uses a composite structure combining the plate spring supporting portion with the light guide plate and optical sheet. The plate spring acts as an intermediate element that transfers heat expansion forces in-plane rather than perpendicular to the optical sheet, creating a composite system that resolves the contradiction between support stability and heat reliability.
2Stability of the object's composition
If the supporting portion expands perpendicular to the light emitting surface, then the light guide plate is supported, but the optical sheet is pushed up leading to creases and uneven luminance
Solution Approach 1:
The patent changes the expansion direction parameter from perpendicular to the light emitting surface to in-plane expansion. The plate spring's elastic deformation occurs within the plane of the light guide plate, preventing vertical displacement of the optical sheet and maintaining its flatness.
3Reliability
If a plate spring is used to press the light guide plate in two directions, then heat expansion is suppressed without pushing up the optical sheet, but the device complexity increases
Solution Approach 1:
The plate spring performs multiple functions simultaneously: it supports the light guide plate, suppresses heat expansion, prevents optical sheet creases, and maintains positional stability. This multi-functionality reduces the need for separate components, actually simplifying the overall device structure despite the sophisticated mechanism.
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 suppresses the occurrence of creases on the optical sheet, ensuring uniform luminance and high reliability against heat, while allowing for a slimmer border design by preventing the plate spring from expanding perpendicular to the light emitting surface.
Implementation Method 1
the rubber-made supporting portion expands by heat in a direction perpendicular to a light emitting surface of the light guide plate
Implementation Method 2
a plate spring provided between the light guide plate and the border and configured to press the light guide plate in a first direction and in a second direction different from the first direction
Data Source
AI summary
A planar illumination apparatus according to an embodiment includes a light guide plate configured to emit, from an exit surface, light incident from a side surface, a frame including a border that encloses the light guide plate, and a plate spring provided between the light guide plate and the border and configured to press the light guide plate in a first direction and in a second direction different from the first direction.