Light Guide Plate Deflection Patterns for Inclination Luminance Stability
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Solution Overview
Problem
Surface illumination devices in mobile devices, such as smartphones, experience rapid luminance changes and flickering when the device is vertically inclined due to narrow directivity of light emission, leading to poor visibility of icons.
Innovation Solution
The use of a surface illumination device with first and second deflection patterns on the light guide plate, where the first pattern is oriented at a right angle to the light source and the second pattern is parallel, allowing light to be reflected from the side surface and improving directivity without degrading front luminance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a single deflection pattern is used in the light guide plate, then the light emission has narrow directivity and high front luminance, but the luminance changes rapidly and flickering occurs when the device is inclined
Solution Approach 1:
The patent divides the deflection pattern into two distinct types: first deflection patterns with inclined surfaces oriented at angles of 45° or more relative to the light source, and second deflection patterns with inclined surfaces oriented at angles of less than 45°. This segmentation allows light to be reflected through multiple paths, broadening the emission directivity while maintaining front luminance, thereby preventing flickering and luminance instability during device inclination.
2Illumination intensity
If the deflection pattern is oriented to maximize front luminance, then the directivity angle is narrow, but the visibility deteriorates when the device is vertically inclined
Solution Approach 1:
The patent applies different local qualities to different regions of the light guide plate by positioning first deflection patterns and second deflection patterns at specific locations. The first deflection patterns (with inclined surfaces at 45° or more) are arranged to provide broad-angle reflection, while the second deflection patterns (with inclined surfaces at less than 45°) are positioned to maintain front luminance. This local differentiation enables the system to adapt to various viewing angles and device orientations.
Solution Approach 2:
The patent introduces a new dimension to light reflection by utilizing side surface reflection in addition to the conventional bottom surface reflection. The second deflection patterns are specifically designed to reflect light that has undergone side surface reflection, creating an additional light path dimension. This multi-dimensional approach broadens the directivity angle while preserving front luminance, improving visibility during device inclination.
3Adaptability or versatility
If dome-shaped patterns are used to broaden directivity, then the directivity angle spreads, but the front luminance is significantly degraded
Solution Approach 1:
The patent employs asymmetric deflection patterns with specifically engineered inclined surfaces rather than symmetric dome-shaped patterns. The first deflection patterns have inclined surfaces oriented at 45° or more to the light source, while the second deflection patterns have inclined surfaces at less than 45°. This asymmetric configuration enables selective reflection of light at different angles, broadening the directivity angle while maintaining high front luminance, unlike dome-shaped patterns that uniformly scatter light and degrade front luminance.
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 maintains consistent luminance and prevents flickering even when the device is inclined, enhancing display quality by optimizing light usage and reducing costs.
Implementation Method 1
the light incident to the light guide plate 16 from the light source 17 is guided in the light guide plate 16 while totally reflected by the upper surface, the lower surface, and both side surfaces of the light guide plate 16
Implementation Method 2
the light is transmitted while refracted by the deflection pattern 18 in the case that the deflection pattern 18 is provided in the light-emitting surface 16c
Data Source
AI summary
A surface illumination device has a light source and a light guide plate having a light-emitting surface. The light guide plate guides light from the light source such that the light is emitted from a display region of the light-emitting surface. A plurality of first deflection patterns having deflection inclined surfaces and a plurality of second deflection patterns having deflection inclined surfaces are formed in the display region in at least one of the light-emitting surface of the light guide plate and an opposite surface to the light-emitting surface. When viewed from a direction perpendicular to the light-emitting surface of the light guide plate, the first deflection pattern is disposed such that an angle formed by a line normal to the deflection inclined surface and a direction connecting the light source and the first deflection pattern is less than or equal to 30°.