Planar Lighting Device Warping Prevention
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Solution Overview
Problem
Existing planar lighting devices with light guide plates face issues of expansion/contraction and warping due to temperature and humidity changes, leading to uneven brightness, reduced light efficiency, and potential damage to light sources and liquid crystal display panels, as no prior solutions address these problems effectively.
Innovation Solution
A planar lighting device design that includes a light source, a light guide plate with a sliding mechanism to maintain constant distance and prevent warping, and a reinforcing member to absorb expansion/contraction, ensuring uniform light distribution and preventing damage to components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If a light guide plate is used to reduce backlight unit thickness, then thickness is reduced, but uniform light amount distribution deteriorates
Solution Approach 1:
The patent applies local quality by varying the thickness of the light guide plate at different locations. The light guide plate has a first region with greater thickness and a second region with lesser thickness, creating local variations in optical path length that compensate for natural light intensity decay and achieve uniform light distribution across the exit surface.
Solution Approach 2:
The patent changes the geometric parameter (thickness) of the light guide plate to optimize light distribution. By adjusting the thickness parameter across different regions, the optical path length is modified to ensure uniform light emergence, resolving the contradiction between thinness and uniformity.
2Stability of the object's composition
If the light guide plate is fixed rigidly to prevent expansion/contraction, then dimensional stability is improved, but warping and uneven brightness occur
Solution Approach 1:
The patent applies dynamics by making the light guide plate movable relative to the housing through a sliding mechanism. This allows the light guide plate to expand and contract freely in response to temperature and humidity changes without generating internal stresses that would cause warping, while the sliding mechanism maintains optical alignment through elastic deformation of connecting components.
Solution Approach 2:
The patent introduces intermediary components (sliding mechanism and elastic components) between the light guide plate and housing. These intermediaries accommodate dimensional changes and maintain mechanical connection without transmitting constraining forces that would cause warping, thus preserving both dimensional stability and brightness uniformity.
3Temperature
If the light guide plate is allowed to expand/contract freely, then thermal expansion is accommodated, but distance from light source varies causing efficiency loss
Solution Approach 1:
The patent applies beforehand cushioning by pre-positioning the light guide plate at an optimal distance from the light source using fixing means. The elastic components provide cushioning that maintains this optimal distance during thermal expansion and contraction, preventing both excessive separation (which would reduce efficiency) and excessive contact (which would cause warping).
Solution Approach 2:
The patent implements a feedback mechanism where the sliding mechanism detects positional changes of the light guide plate due to thermal expansion and automatically adjusts the position through elastic component deformation. This feedback loop maintains the optimal optical distance dynamically, ensuring consistent light admission efficiency despite temperature variations.
4Manufacturing precision
If fixing means is used to maintain constant distance, then optical alignment is improved, but expansion/contraction stress causes warping
Solution Approach 1:
The patent applies dynamics by making the fixing means flexible rather than rigid. The elastic components allow the fixing means to deform dynamically in response to thermal expansion and contraction forces, maintaining constant optical axis distance while accommodating dimensional changes without generating warping stresses.
Solution Approach 2:
The patent changes the mechanical property (elasticity) of the fixing means to enable it to maintain optical alignment while accommodating dimensional changes. The elastic components transform the fixing means from a rigid constraint into a flexible connector that preserves optical precision without inducing warping.
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 maintains constant optical axis distances, prevents warping, and ensures uniform light emission, even with large light guide plates, enhancing the reliability and efficiency of the lighting device.
Implementation Method 1
a light guide plate for admitting light emitted by the light source and emitting a light through the light exit plane
Implementation Method 2
expansion/contraction of the light guide plate
Implementation Method 3
elastically hold the fixing means with respect to the housing
Implementation Method 4
fixing means for fixing and integrating the light source and the light guide plate
Implementation Method 5
a reinforcing member for reinforcing the housing according to the expansion/contraction of the light guide plate
Data Source
AI summary
A planar lighting device is capable of keeping the light entrance plane of the light guide plate spaced a constant distance from the light source and the light guide plate spaced a constant distance from the liquid crystal display panel even when the light guide plate expands, contracts or warps. This prevents break of the light source, decrease of light admission efficiency, occurrence of uneven brightness, and break of the liquid crystal display panel and permits a thin, larger, and lightweight design. The planar lighting device includes a fixing member for keeping them spaced from each other, a housing for accommodating the light source and the light guide plate, a sliding mechanism to elastically hold the fixing means against the housing while keeping the light source spaced a constant distance from the light guide plate, and a reinforcing member for reinforcing the housing.