Wide Lateral Angle Frontlight for Reflective Displays
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Solution Overview
Problem
Devices with reflective displays, such as e-book readers, suffer from limited viewing angles, causing content to appear dark or impossible to read when viewed from angles greater than 30 degrees from normal due to reduced light scattering and reflection.
Innovation Solution
Incorporating light guides with extraction features that refract light at varying angles, allowing more light to be reflected towards the viewer, thereby increasing the viewing angle by directing light from one end of the device to another and using a reflective display to reflect this light back to the user.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a reflective display is used, then power consumption is reduced, but viewing angle is limited
Solution Approach 1:
A light guide is introduced as an intermediary component between the light source and the reflective display. The light guide redirects light at specific angles to compensate for the limited viewing angle of the reflective display, while the display itself remains passive and reflective, maintaining low power consumption. The light guide acts as a mediator that solves the viewing angle problem without requiring the display to become active.
Solution Approach 2:
The light guide incorporates extraction features at specific locations and orientations to redirect light in particular directions. These localized modifications to the light guide structure create enhanced light scattering at specific angles, providing wide viewing angles in the horizontal direction while maintaining the reflective display's inherent vertical viewing characteristics.
2Adaptability or versatility
If light is directed at wide angles, then viewing angle increases, but light intensity decreases
Solution Approach 1:
The extraction features in the light guide are designed with specific geometries (such as prisms or gratings) that control the angular distribution of extracted light. By carefully designing the parameters of these extraction features, the system optimizes the balance between viewing angle and light intensity, ensuring that light is redirected at wide angles while maintaining sufficient brightness for readable content.
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 solution enhances the viewing angle of devices with reflective displays, allowing content to be readable from wider angles without significant brightness reduction, improving usability by maintaining light intensity across a broader range of viewing positions.
Implementation Method 1
Incorporating light guides with extraction features that refract light at varying angles, allowing more light to be reflected towards the viewer
Implementation Method 2
using a reflective display to reflect this light back to the user
Data Source
AI summary
Devices, systems, and methods are provided for generating a wide angle frontlight for use with reflective displays. A display device may include a first end and a second end opposite the first end, and a first side and a second side opposite the first side. The display device may include a first light source, and a first light guide able to receive first light from the first light source. The display device may include a reflective display, the first light guide including a first refractive device, the first refractive device refracts a first portion of the first light toward the reflective display in a first direction toward the first side and to refract a second portion of the first light toward the reflective display in a second direction toward the second side, and the first direction separated from the second direction by a first angle of at least forty degrees.