Backlight Module Coherent Light via Grating Total Reflection
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Solution Overview
Problem
Traditional backlight modules emit non-coherent light, which is unsuitable for holographic three-dimensional displays, and existing coherent light sources are not suitable for large-area applications due to their small emitting areas.
Innovation Solution
A backlight module comprising a light guide plate with intersecting grating structures and a point light source, where light rays undergo multiple total reflections to form a large-area coherent light source, maintaining the same wavelength and polarization state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a traditional backlight module is used, then the light source has a large emitting area, but the emitted light is non-coherent and cannot be utilized by the spatial light modulator
Solution Approach 1:
The patent introduces a light guide plate as an intermediary component between the point light source and the spatial light modulator. This light guide plate transforms the light from the point source into a large-area coherent light source that is compatible with holographic display requirements, thus mediating between the conflicting requirements of coherence and large emitting area
Solution Approach 2:
The patent changes the physical parameters of light propagation by designing specific optical paths within the light guide plate, including total internal reflection paths and grating structures. These parameter changes transform the light characteristics from non-coherent to coherent while maintaining large emitting area, resolving the contradiction between light coherence and adaptability
2Illumination intensity
If existing coherent light sources (lasers) are used, then the light has high coherence, but the emitting area is very small and not suitable for large-area holographic display
Solution Approach 1:
The patent uses the light guide plate to extend the light propagation in additional spatial dimensions through total internal reflection paths. This dimensional extension transforms a point source (0D) into a large-area source (2D) while preserving coherence, effectively resolving the contradiction between coherence and emitting area through dimensional transformation
Solution Approach 2:
The light guide plate is divided into multiple functional regions including first and second light incidence surfaces, first and second light-emitting surfaces, and grating structures. This segmentation allows different portions to perform specific functions in the light transformation process, enabling the system to achieve both coherence and large emitting area through coordinated action of segmented components
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 provides a coherent light source suitable for holographic three-dimensional displays, enhancing the performance of the backlight module by ensuring coherent light emission with consistent wavelength and polarization.
Implementation Method 1
a light ray emitted from the point light source enters, at a first preset angle, into the first part and undergoes multiple total reflections in the first part. Reflected light enters into the second part... undergoes multiple total reflections in the second part
Implementation Method 2
both the first light-emitting surface and the second light-emitting surface are set as grating structures
Data Source
AI summary
A backlight module and a display device include a light guide plate and a point light source. The light guide plate includes a first part and a second part. The first part includes a first light incidence surface and a first light-emitting surface intersecting with the first light incidence surface. The second part includes a second light incidence surface and a second light-emitting surface intersecting with the second light incidence surface. The first light incidence surface intersects with the second light-emitting surface, the first light-emitting surface and the second light incidence surface are arranged oppositely, and both the first light-emitting surface and the second light-emitting surface include grating structures.