Light Guide Plate Cylindrical Lens Surfaces for Edge Illumination
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Solution Overview
Problem
In display devices with reflective panels, the intensity of illuminating light emitted from a light guide plate is unevenly distributed due to the narrowing of light divergence when using a flat light receiving section, leading to reduced light intensity at the edges and increased device size when trying to minimize these issues.
Innovation Solution
The light receiving section of the light guide plate is configured with a plurality of cylindrical lens surfaces formed as concave curved surfaces parallel to the thickness direction, which widens the angle of divergence, ensuring even light distribution and minimizing intensity unevenness, even when the light receiving section and light emitting element are close to each other.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a flat light receiving section is used, then the device size can be reduced, but the light intensity distribution becomes uneven with significant decline at edge regions
Solution Approach 1:
The light receiving section is configured with a concave curved surface instead of a flat surface. This curvature causes incident light from the light emitting element to be reflected at varied angles, widening the light distribution and preventing intensity decline at edge regions while maintaining compact device dimensions.
Solution Approach 2:
The concave curved surface creates different local reflection characteristics across the light receiving section. Regions closer to the center reflect light at different angles compared to edge regions, thereby achieving uniform light intensity distribution across the entire light guide plate surface.
2Illumination intensity
If the light receiving section is positioned far from the image display region, then edge light intensity can be maintained, but the device size increases
Solution Approach 1:
By implementing a concave curved surface at the light receiving section, the patent achieves effective light distribution to edge regions without increasing the distance between the light emitting element and the image display region, thus maintaining compact device length.
Solution Approach 2:
Instead of solving the light distribution problem by increasing spatial distance in one dimension, the patent introduces a dimensional change through surface curvature, transforming the flat light receiving section into a three-dimensional concave structure that achieves uniform illumination without extending device length.
3Measurement precision
If cylindrical lens surfaces with convex curved surfaces are used as proposed in prior art, then light can be focused, but the angle of divergence becomes narrower and light intensity at distant regions decreases
Solution Approach 1:
Instead of using convex curved surfaces that focus light and narrow divergence, the patent inverts the approach by employing concave curved surfaces that widen light divergence. This inversion achieves the opposite effect of prior art, distributing light more effectively to distant and edge regions of the light guide plate.
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 sufficient light intensity across the light guide plate, including edge regions, while allowing for a smaller device size by preventing the need for increased spacing between light emitting and receiving elements.
Implementation Method 1
light is refracted upon entering the light guide plate 50, and hence the angle of divergence is narrowed
Data Source
AI summary
An illuminating device includes a light emitting element constituted of a light emitting diode, and a light guide plate including a light receiving section provided on a side face and opposed to the light emitting element. The light guide plate emits illuminating light from a first surface. The light receiving section includes a plurality of cylindrical lens surfaces each formed of a concave curved surface oriented such that an axial direction of the curved surface is parallel to a thickness direction of the light guide plate, the cylindrical lens surfaces being aligned in a direction orthogonal to the axial direction. The cylindrical lens surface is formed of an arcuate surface having a curvature radius of 0.5 mm or less, and more preferably 0.2 mm or less.