Light Guide Plate Directivity Conversion Pattern for Color Uniformity
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Solution Overview
Problem
Surface illumination devices with thin light guide plates experience color unevenness due to the inclination of light emission direction from LEDs, leading to inefficient light distribution and increased leakage, which affects the balance between light use efficiency and device thickness.
Innovation Solution
A light guide plate with a directivity conversion pattern is introduced, featuring inclined surfaces and lenticular lenses to redirect light, ensuring that light from LEDs is evenly distributed across the exit surface, reducing color unevenness and enhancing light use efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the thickness of the light guide plate is decreased to achieve a thinner surface illumination device, then the device thickness is reduced, but the light source height becomes greater than the light guide plate thickness causing light leakage and degraded light use efficiency
Solution Approach 1:
The light guide plate is divided into two functional regions: a light introduction unit with greater thickness to contain the light source and an light guide plate body with smaller thickness for light guidance. This segmentation allows the light source to be properly contained while maintaining an overall thin profile.
Solution Approach 2:
An inclined surface is introduced in the light introduction unit, creating a dimensional transition from the light source region to the light guide plate body. This inclined surface redirects light that would otherwise leak upward, converting harmful light leakage into useful light guidance.
2Loss of energy
If a light introduction unit with greater thickness is provided to improve light use efficiency, then light leakage is reduced, but the overall device thickness increases
Solution Approach 1:
The light guide plate is divided into two functional regions: a light introduction unit with greater thickness to contain the light source and an light guide plate body with smaller thickness for light guidance. This segmentation allows the light source to be properly contained while maintaining an overall thin profile.
Solution Approach 2:
The light guide plate has non-uniform thickness distribution: the light introduction unit has greater thickness where needed for light source containment and efficient light coupling, while the light guide plate body has reduced thickness for overall device thinning. This local quality variation optimizes both light efficiency and device thickness.
3Productivity
If light is emitted from LEDs at an inclined direction, then the light can be directed toward the light guide plate, but color unevenness occurs between central and side portions of the light exit surface
Solution Approach 1:
Lenticular lenses with curved surfaces are formed on the light exit surface of the light guide plate body. These lenses redirect light rays at different angles, mixing light from different regions and converting inclined light emission into uniform light distribution across the exit surface.
Solution Approach 2:
The lenticular lenses act as an intermediary optical element between the light guide plate and the external environment. They modify the light direction and distribution, mixing light rays to eliminate color unevenness while maintaining efficient light output.
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 directivity conversion pattern effectively mixes light of different colors, reducing color unevenness between the central and side portions of the light guide plate, while maintaining high luminance efficiency and minimizing light leakage.
Implementation Method 1
an inclined surface that is inclined toward the end of the light guide plate body from a point of the maximum thickness of the light introduction unit is provided in the light introduction unit
Implementation Method 2
the light guide plate body includes a directivity conversion pattern in a region located between the light introduction unit and an effective illumination region of the light guide plate body... and the directivity conversion pattern converts a directivity direction of the light passing through the effective illumination region
Implementation Method 3
a lenticular lens 16 is formed in a surface... the directional pattern of the light exiting from the light exit surface is spread by the lenticular lens 16
Data Source
AI summary
A light guide plate includes a light introduction unit that confines light incident from a point light source through the light incident surface and a light guide plate body. The light introduction unit includes an inclined surface inclined toward an end of a surface of the light guide plate body from a surface in a portion having the thickness greater than that of the light guide plate body. The light guide plate body includes a directivity conversion pattern located between the light introduction unit and an effective illumination region of the light guide plate body. The directivity conversion pattern converts a directivity direction of the light passing through an effective illumination region from the light introduction unit such that an angle formed by the light and a direction perpendicular to the light incident surface increases when viewed from a direction perpendicular to a light exit surface.