Pupillated Backlight Optics for Uniform Privacy Display Viewing
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Solution Overview
Problem
Existing privacy displays face challenges in providing uniform illumination and efficient control of privacy modes, with micro-louvre optical films causing high losses and Moiré artefacts, and existing solutions requiring user intervention or complex keystroke controls.
Innovation Solution
An illumination apparatus featuring a waveguide arrangement and an optical turning film component with prismatic elements that deflect light uniformly across a plane, allowing for adjustable facet angles and multiple light sources to enhance spatial uniformity and switchable privacy modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If micro-louvre optical films are used to provide privacy function, then off-axis visibility is reduced, but head-on illumination losses increase and Moiré artefacts occur
Solution Approach 1:
The optical film is segmented into multiple discrete microlens elements arranged in an array, where each microlens independently focuses light. This segmentation allows selective directional control of light transmission, achieving privacy function while maintaining higher head-on illumination efficiency compared to continuous micro-louvre structures.
Solution Approach 2:
The patent changes the optical parameters by using microlenses with specific focal lengths and aperture angles that can be optimized independently. By adjusting the lens curvature, spacing, and focal properties, the system achieves both privacy protection and reduced illumination losses through precise control of light focusing angles.
2Manufacturing precision
If micro-louvre pitch is selected for panel resolution, then display quality is improved, but inventory and cost increase
Solution Approach 1:
The microlens array is designed with a universal pitch that can be used across different panel resolutions. The lens parameters are optimized to work effectively with standard display pixel pitch ranges, eliminating the need for multiple inventory variants and reducing manufacturing complexity while maintaining display quality.
3Object-affected harmful factors
If removable louver film is added for privacy mode, then privacy function is provided, but ease of operation deteriorates due to fitting and removal difficulties
Solution Approach 1:
The privacy function is merged with the display structure by integrating the microlens array directly into the display assembly, making it a permanent fixture rather than a removable component. This eliminates the operational complexity of fitting and removing films while maintaining effective privacy protection.
4Adaptability or versatility
If electronic privacy control is implemented, then privacy mode switching is enabled, but device complexity increases requiring user keystroke intervention
Solution Approach 1:
The system provides automatic privacy mode switching based on detected viewing conditions or user proximity, eliminating the need for manual keystroke controls. Sensors detect whether a user is in position and automatically activate or deactivate privacy mode, reducing operational complexity while maintaining adaptability.
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
The solution provides increased uniformity and efficiency in illumination, reducing Moiré artefacts and user intervention, while enabling seamless switching between privacy and public modes with improved luminance distribution.
Implementation Method 1
first and second opposed light guiding surfaces arranged to guide light along the first waveguide, the second light guiding surface being arranged to guide light by total internal reflection
Implementation Method 2
being arranged to cause light from the at least one light source to exit from the first waveguide through the second light guiding surface by breaking total internal reflection
Implementation Method 3
the input surface comprises: an array of prismatic elements each comprising a pair of facets defining a ridge therebetween... wherein the prismatic elements are arranged to deflect the light exiting the first waveguide
Data Source
AI summary
A switchable backlight for a switchable privacy display apparatus comprises a collimated waveguide, first and second light sources and an optical turning film comprising elongate prismatic elements with facet orientations that pupillate the output of the waveguide in two orthogonal directions for each of first and second light sources. High luminance uniformity is achieved for a head-on user in privacy and public viewing modes and high uniformity of security factor is achieved for off-axis snoopers, with increased speed of privacy switch-on in privacy mode.