Light Guide Plate Blue Light Reflection for Color Uniformity
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Solution Overview
Problem
Recent reductions in light guide plate thickness lead to visible color unevenness due to yellow tint in sidelight-type spread illuminating apparatuses, particularly in compact mobile devices, where the thickness of the emitting portion tapers away from the light source, causing partial color unevenness and affecting color tone uniformity.
Innovation Solution
A blue light reflecting unit is disposed on the emitting surface side or opposite side near the boundary between the incident light wedge part and the emitting part of the light guide plate, selectively returning blue light components into the plate, thereby increasing blue light emission relative to longer wavelengths, such as yellow light, to enhance color tone uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the thickness of the emitting portion of the light guide plate is decreased to reduce overall device thickness, then the device becomes thinner and more compact, but color unevenness occurs in the region toward the incident light surface due to yellow tint
Solution Approach 1:
The patent applies local quality by introducing a blue light reflecting unit at a specific location (near the boundary between the incident light wedge part and the emitting part) to selectively reflect blue light components. This localized intervention corrects the yellow tint in the affected region without altering the overall thin structure of the light guide plate, thereby maintaining color tone uniformity while preserving the reduced thickness design.
Solution Approach 2:
The patent changes the optical parameters by introducing a blue light reflecting unit that selectively reflects blue light components (wavelength around 450-480nm) in the region toward the incident light surface. This parameter change compensates for the yellow tint caused by the reduced thickness, adjusting the spectral composition to achieve uniform color tone across the emitting surface.
2Length of moving object
If a wedge part is formed to taper thickness from the incident light surface toward the emitting part, then the light guide plate can be made thinner, but blue light leakage occurs causing visible color unevenness
Solution Approach 1:
The patent converts the harmful blue light leakage into a beneficial effect by using a blue light reflecting unit to selectively reflect the leaked blue light components back into the light guide plate. This transforms the harmful blue light leakage that causes color unevenness into a useful mechanism for maintaining color tone uniformity, particularly in the thin emitting portion region.
Solution Approach 2:
The patent applies local quality by positioning the blue light reflecting unit specifically near the boundary between the incident light wedge part and the emitting part, where blue light leakage and yellow tint occur. This localized solution addresses the color unevenness problem in the affected region without affecting the overall wedge structure and thin profile of the light guide plate.
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 effectively suppresses visible color unevenness by increasing blue light emission in the affected regions, resulting in improved color tone uniformity across the light guide plate, even in thin designs.
Implementation Method 1
a blue light reflecting unit is disposed on at least one of the emitting surface side or an opposite side of the emitting surface side near a boundary between the incident light wedge part and the emitting part
Data Source
AI summary
A spread illuminating apparatus includes a light source that emits white light, and a light guide plate including an incident light surface which is an end surface at which the light source is disposed and an emitting part that emits light which has entered from the incident light surface in a spread pattern from an emitting surface. The light guide plate includes an incident light wedge part between the incident light surface and the emitting part, the incident light wedge part including an inclined surface and tapering in thickness from the incident light surface side toward a forward direction. Also, a blue light reflecting unit is disposed on at least one of the emitting surface side or an opposite side of the emitting surface side near a boundary between the incident light wedge part and the emitting part.