Grating Spreader for Multiview Display Backlight
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Solution Overview
Problem
Passive electronic displays, such as LCDs and EP displays, face limitations in practical applications due to their inability to emit light, necessitating the use of external light sources like backlights to function effectively.
Innovation Solution
A backlight system with an angle-preserving scattering feature and a grating spreader is employed, providing spatio-angularly homogenous light with multiple principal angular directions to facilitate uniform illumination and enhance the functionality of multiview displays by emitting light in various directions, effectively overcoming the limitations of passive displays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If passive displays (LCDs, EP displays) are used, then power consumption is low and inherent display quality is good, but they cannot emit light and have limited practical application
Solution Approach 1:
The patent combines passive display technology with an active backlight system into an integrated multiview display device. The backlight unit merges light emission functionality with the passive display panel, enabling the display to emit light in multiple directions while maintaining low power consumption characteristics of passive displays.
Solution Approach 2:
The backlight system is designed to provide multiple functions: it serves as both an illumination source and a light distribution mechanism that directs light to multiple viewing angles. The grating spreader and angle-preserving scattering feature work together to create a universal lighting solution that supports multiview functionality.
2Object-generated harmful factors
If external light sources are coupled to passive displays, then light emission capability is achieved, but uniform illumination and angular homogeneity are difficult to achieve
Solution Approach 1:
The grating spreader acts as an intermediary optical element between the light source and the display panel. It diffracts and redistributes light to achieve uniform angular distribution, while the angle-preserving scattering feature serves as another intermediary that maintains beam directionality while providing scattering for even illumination across the display surface.
Solution Approach 2:
The patent employs optical parameters manipulation through the grating spreader's diffraction angle and the scattering feature's angular characteristics. By carefully selecting and adjusting these optical parameters, the system achieves spatio-angularly homogenous light distribution that provides uniform illumination across multiple viewing angles.
3Illumination intensity
If grating spreader with diffractive features is used, then spatio-angularly homogenous light is achieved, but manufacturing precision requirements increase
Solution Approach 1:
The grating spreader is implemented as a thin film or coating layer applied to the light guide plate. This approach reduces manufacturing complexity compared to creating precise three-dimensional diffractive structures, as thin film deposition techniques can achieve the required diffractive patterns with standard semiconductor manufacturing processes.
4Adaptability or versatility
If angle-preserving scattering feature is used, then multiple directional light beams are produced, but device complexity increases
Solution Approach 1:
The angle-preserving scattering feature is merged with the light guide plate structure itself, rather than being a separate component. This integration reduces device complexity by combining multiple functions (light guiding, scattering, and angle preservation) into a single structural element.
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 uniform illumination and enhances the functionality of multiview displays by allowing them to emit light in multiple directions, improving their practical applications and user experience.
Implementation Method 1
a grating spreader configured to spread out light from a light source to provide spatio-angularly homogenous light within the light guide
Implementation Method 2
a light guide configured to guide light... an angle-preserving scattering feature configured to scatter light within the light guide while preserving the angle of propagation
Data Source
Figure 1A~1B
Figure 2~3A
Figure 3B~3C
AI summary
A backlight and a multiview display employ a light guide having angle-preserving scattering feature and a grating spreader. The angle-preserving scattering feature is configured to scatter a portion of guided light out of the light guide as emitted light. The grating spreader includes a diffraction grating and is configured to convert light provided by a light source into spatio-angularly homogenous light to be guided as the guided light. The multiview display includes an array of light valves as well as the angle-preserving scattering feature that includes a multibeam element having a size that is comparable to a size of a light valve of the light valve array.