Overlapping Light Guide Plates for Edge-Lit Backlight Modules
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Solution Overview
Problem
Conventional direct-lit backlight modules for liquid crystal displays are thick due to the need for long light mixing distances, making them unsuitable for thinner displays, and struggle to achieve high dynamic contrast ratios effectively.
Innovation Solution
An edge-lit type backlight module with overlapping light guide plates, each having light-emitting and total reflection regions alternately disposed, allows for independent control of light sources and scattering, mimicking the light distribution of direct-lit modules while maintaining a thinner profile.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a direct-lit backlight module uses emitter arrays to create multiple sub-regions for high dynamic contrast ratio, then the image detail division and brightness control are improved, but the light mixing distance increases and the module thickness becomes relatively thick
Solution Approach 1:
The light guide plate is divided into multiple sub-regions using interface structures that extend along the light travel direction. These interfaces have different refractive indices to prevent light mutual interference between adjacent sub-regions, enabling independent brightness control of each sub-region without requiring a thick module structure
Solution Approach 2:
The patent transitions from a conventional planar light guide plate to a three-dimensional structured light guide plate with interfaces extending in the light travel direction. This dimensional change creates multiple sub-regions that can be independently controlled, achieving high dynamic contrast ratio in a thinner profile by utilizing the third dimension for light management
2Stability of the object's composition
If a direct-lit backlight module uses emitter arrays to achieve even light distribution, then the brightness uniformity is improved, but the light emitter occupies space and requires long light mixing distance
Solution Approach 1:
The interface structures with different refractive indices act as intermediaries to manage light propagation. These interfaces prevent light mutual interference between adjacent sub-regions and guide light distribution uniformly across the light guide plate without requiring space-occupying emitter arrays or long mixing distances
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
Enhances the dynamic contrast ratio by allowing independent control of brightness in multiple sub-regions, approaching the light-emitting effect of direct-lit modules while maintaining a thinner design.
Implementation Method 1
The light guide plate is disposed with light-emitting regions and total reflection regions disposed alternately, configured to totally reflect light emitted from a light source disposed on a side of the light incident surface in the total reflection regions
Implementation Method 2
The light-emitting regions of the light guide plate are disposed with a diffraction grating, and the diffraction grating is disposed on the light-emitting surface of the light guide plate
Implementation Method 3
An index of refraction of the interfaces is smaller than an index of other regions of the light guide plate. The plurality of interfaces are configured to divide the light guide plate into a plurality of sub-regions to prevent mutual interference between the light travelled in two adjacent sub-regions
Data Source
AI summary
The disclosure discloses an edge-lit type backlight module, a display and a light guide plate. The edge-lit type backlight module includes at least two light guide plates disposed to be overlapped. Each of the light guide plates respectively includes a light-emitting surface, a bottom surface and at least one light incident surface. The bottom surface of the light guide plate on an upper layer and the light-emitting surface of the light guide plate on a lower layer are disposed opposite. Light sources are disposed on the light incident surfaces of each of the light guide plates, and disposed to be mutually independent. In travel directions of light of the light sources, each of the light guide plates is disposed with light-emitting regions and total reflection regions disposed alternately. The light emitted from the light sources is totally reflected in the total reflection regions.