Reflective Display Illuminator with Light Guide Structures
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Solution Overview
Problem
Reflective displays are not well-suited for use in low ambient light environments as they rely on external light sources and cannot increase illumination intensity beyond ambient light levels, limiting their usability in dim or dark conditions.
Innovation Solution
A light guide with optically coupled light sources and light redirecting structures is integrated into the display, allowing for supplemental illumination and automatic adjustment of light intensity based on ambient conditions, using sensors and controllers to activate and vary the light sources for uniform or localized illumination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a reflective display is used, then power consumption is reduced and efficiency is improved, but illumination intensity is limited by ambient light levels
Solution Approach 1:
The display system is segmented into two independent illumination paths: the ambient light path for general viewing and the supplemental light path for low-light conditions. This allows the display to maintain reflective efficiency while adding controlled illumination capability through separate light sources and light guide structures.
Solution Approach 2:
A light guide acts as an intermediary component that captures light from supplemental sources and distributes it uniformly across the display surface. The light guide includes light redirecting structures that mediate between the light source and the display, ensuring even illumination without compromising the reflective display's efficiency.
2Ease of manufacture
If a reflective display is used, then manufacturing simplicity is maintained, but usability in low ambient light environments deteriorates
Solution Approach 1:
The supplemental illumination system is merged with the reflective display structure by integrating light sources and light guide components directly into the display assembly. This combination allows the display to function in both reflective mode (using ambient light) and supplemented mode (using artificial light), maintaining ease of manufacture while improving low-light usability.
3Illumination intensity
If supplemental light sources are added, then illumination intensity in low light environments is improved, but device complexity increases
Solution Approach 1:
The light guide structure serves multiple functions: it acts as a light distributing element for supplemental illumination, a light redirecting element for uniform illumination distribution, and an optical coupling element between light sources and the display. This multi-functionality reduces the need for separate components, thereby limiting the increase in device complexity while achieving improved illumination intensity.
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
Enables reflective displays to operate effectively in low light environments by providing supplemental illumination, maintaining uniformity and adjusting intensity to match ambient conditions, thereby enhancing usability and image quality.
Implementation Method 1
Light rays emitted into light guide 14 by light sources 16 are ordinarily confined within light guide 14 by total internal reflection
Implementation Method 2
Light guide 14's front and rear planar surfaces 22, 24 are substantially transparent to incident light rays
Implementation Method 3
A plurality of light redirecting structures 30 are provided or formed within light guide 14
Data Source
AI summary
An illuminator for a reflective display (10) incorporates a light guide (14) having substantially transparent front and rear planar surfaces which overlap the display's viewing surface when the surfaces are substantially parallel and adjacent to the viewing surface. A light source (16) emits light into the light guide. A plurality of light redirecting structures (30) is distributed on the light guide's rear surface. The structures are shaped to redirect through the light guide toward the viewing surface light rays which encounter the structures. Most light rays emitted into the light guide by the light source which do not encounter any of the structures are confined within the light guide by total internal reflection. Most light rays emitted into the light guide by the light source which encounter any of the structures are re directed through the light guide toward the viewing surface, substantially uniformly illuminating the display in a low ambient light environment.