Light Guide Plate Slant Surfaces for LCD Thickness Reduction
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Solution Overview
Problem
In liquid crystal display devices, increasing the size of surface light source devices while maintaining luminance and luminance uniformity and reducing thickness is challenging, as it is difficult to achieve both size increase and thickness reduction without compromising optical characteristics.
Innovation Solution
The implementation of a light guide plate with inclined surfaces that decrease in thickness from the edges to the center, allowing for a more compact design and improved light path efficiency, which includes a flat surface opposed to the liquid crystal cell and a second surface with slant surfaces connected by circular arc-shaped connection portions, enabling a thinner structure without degrading luminance and uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the size of surface light source device is increased, then the display area is expanded, but the thickness cannot be reduced and luminance uniformity deteriorates
Solution Approach 1:
The light guide plate employs a slant surface configuration that utilizes the angular dimension to control light paths. By inclining the surface at specific angles (e.g., 45 degrees), the patent creates a three-dimensional light guidance structure that enables thinner overall device thickness while maintaining effective light distribution across the display area.
Solution Approach 2:
The light guide plate features non-uniform thickness distribution where the thickness varies from the center toward the edges. This local variation in thickness allows different regions of the plate to perform specialized functions - the thinner edge regions reduce overall device thickness while the thicker central region maintains structural integrity and optical performance.
2Area of stationary object
If the size of surface light source device is increased, then the display area is expanded, but luminance uniformity deteriorates
Solution Approach 1:
The light guide plate employs varying thickness across different regions, with the edge portions being thinner than the central portion. This local thickness variation is specifically designed to compensate for light loss at edges, ensuring uniform luminance output across the entire display area while enabling the device to be thinner at the edges.
Solution Approach 2:
The light guide plate utilizes asymmetric slant surface angles and non-uniform thickness distribution to control light paths differently across various regions. This asymmetric design allows optimization of light extraction and distribution to achieve uniform luminance across the display area.
3Ease of manufacture
If conventional light guide plate structure is used, then manufacturing is simple, but luminance increase is limited and thickness reduction is difficult
Solution Approach 1:
The patent modifies the geometric parameters of the light guide plate by introducing slant surfaces at specific angles (e.g., 45 degrees) and creating non-uniform thickness profiles. These parameter changes in the plate's physical geometry enable enhanced light extraction and distribution, resulting in 4-5% luminance increase while maintaining manufacturability through standard molding techniques.
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
This configuration results in a 4% to 5% increase in luminance and allows for a reduction in the thickness of the liquid crystal module while maintaining optical characteristics, enabling a more compact and efficient design.
Implementation Method 1
a light guide plate which guides light beams from light source devices to a liquid crystal cell
Implementation Method 2
a surface light source device which is disposed behind the liquid crystal panel and applies light to the liquid crystal panel
Data Source
AI summary
According to one embodiment, a liquid crystal display device includes a liquid crystal cell, light source devices and a light guide plate. The light guide plate applies, to a rear surface of the liquid crystal cell, light beams from the light source devices. The light guide plate includes a first light input portion at a first-shorter-side side surface and a second light input portion at a second-shorter-side side surface. The light guide plate includes a flat first surface opposed to the rear surface and a second surface opposite to the first surface. The second surface includes a first slant surface inclined so that a thickness of the light guide plate decreases as a position goes from the first-shorter-side side surface to an approximately central portion and a second slant surface inclined so that the thickness decreases as a position goes from the second-shorter-side side surface to the approximately central portion.