Backlight Optical Waveguide and Cone Sheet for Viewing Angle Switching
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Solution Overview
Problem
Conventional liquid crystal display devices face challenges in switching between wide-viewing-angle and narrow-viewing-angle modes efficiently, leading to reduced luminance and visibility issues due to the inefficiency of light directivity and mounting position limitations of the light source.
Innovation Solution
A light source device with a light guiding member and optical member that increases directivity in two dimensions, allowing the light source to be mounted flexibly and enhancing luminance by concentrating luminous flux in the frontal direction, while a transparent/scattering state switching element adjusts the viewing angle range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a conventional light source device is used in liquid crystal display devices, then the light source can be mounted on the back surface of the liquid crystal panel, but the directivity of light is insufficient leading to reduced luminance and limited mounting position flexibility
Solution Approach 1:
The patent introduces a light guiding member with a specific geometric structure (prism-shaped cross-section) that redirects light from the light source in a controlled manner. This structural dimensionality change enables light to be guided along the backlight unit while maintaining high directivity, thereby improving luminance without restricting mounting positions.
Solution Approach 2:
The patent employs an optical member with variable refractive index or optical properties that can be adjusted to control light directivity. By changing optical parameters such as refractive index distribution or surface geometry, the system achieves high luminance and flexible mounting without requiring precise positioning of the light source.
2Adaptability or versatility
If the light source device is designed to switch viewing angles, then wide-angle and narrow-angle modes can be achieved, but light loss increases leading to reduced luminance efficiency
Solution Approach 1:
The patent incorporates a dynamic light control mechanism that can adjust the radiation angle of light based on display requirements. The optical member can dynamically redirect light paths to achieve either wide-angle or narrow-angle viewing modes without significant light loss, maintaining luminance efficiency while providing viewing angle adaptability.
Solution Approach 2:
The patent introduces an intermediary optical member that acts as a mediator between the light source and the liquid crystal panel. This optical member efficiently redirects light to achieve different viewing angles while minimizing light loss, thereby enabling viewing angle switching without sacrificing luminance efficiency.
3Illumination intensity
If opaque slitted sheets are used to control light direction, then directivity can be improved, but light loss increases significantly
Solution Approach 1:
The patent replaces mechanical light blocking structures (opaque slitted sheets) with an optical guiding mechanism based on refraction and total internal reflection. The light guiding member with prism-shaped cross-section redirects light through optical principles rather than mechanical blocking, achieving high directivity with minimal light loss.
Solution Approach 2:
The patent changes the optical parameters of the light guiding member (refractive index, surface geometry) to optimize light direction control. By adjusting these parameters, the system achieves high directivity comparable to opaque slitted sheets but with significantly reduced light loss through efficient optical redirection.
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 high luminance and flexible mounting options for the light source, enabling efficient switching between wide-angle and narrow-angle viewing modes with reduced light loss and improved display visibility.
Implementation Method 1
a light guiding member for emitting the light incident from the light source in a first direction that is different from the incidence direction of the light
Implementation Method 2
an optical member for emitting the light incident from the light guiding member in a second direction that is different from the first direction
Implementation Method 3
a transparent/scattering state switching element capable of switching between a state of transmitting the light incident from the light-direction regulating element, and a state of scattering the light
Data Source
AI summary
In the display device, a light source unit, a louver, a transparent/scattering state switching element, and a transmissive liquid crystal panel are provided in sequence, an optical waveguide and a cone sheet are provided to the light source unit, and a light source is disposed on the side of the optical waveguide. The light-exiting surface of the optical waveguide is made flat, and a tilted surface that is tilted to the side of the light source with respect to the light-exiting surface is formed in a light diffusing surface. A flat plate is provided to the cone sheet, and a plurality of circular cones are arranged two-dimensionally on the light-incident surface of the flat plate. The central axes of the circular cones are parallel to each other. The transparent/scattering state switching element is capable of switching between a state for transmitting incident light and a state for scattering the light. By this configuration, a light source device is obtained having high directivity, high luminance, and no limitations on the mounting position of the light source.