Switchable Privacy Display With Diffractive View-Angle Control
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Solution Overview
Problem
Existing privacy displays struggle to provide high image visibility to on-axis viewers while maintaining reduced visibility for off-axis snoops, often requiring multiple layers that increase cost, complexity, and power consumption.
Innovation Solution
A display device incorporating a spatial light modulator (SLM) with a switchable diffractive view angle control retarder arrangement (SDVACRA) using a switchable diffractive liquid crystal retarder (SDLCR) and transmissive electrodes to selectively control light phase shifts, allowing for narrow-angle and wide-angle states, enhancing image security and visibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple layers are used to achieve high image visibility and privacy protection, then image security and visibility are improved, but device complexity, cost, and power consumption increase
Solution Approach 1:
The patent combines multiple functional layers (liquid crystal retarder, diffractive optical element, polarizers) into an integrated optical stack that achieves both high image visibility and privacy protection with reduced complexity. The SDLCR integrates the liquid crystal layer with diffractive optical elements and polarizers in a single compact structure, eliminating the need for separate layers while maintaining security and visibility performance.
Solution Approach 2:
The optical stack is designed to perform multiple functions simultaneously: the SDLCR provides both privacy protection through view-angle-dependent luminance reduction and high image visibility through controlled diffractive effects. The same structure achieves both security and visibility without requiring separate dedicated layers for each function.
2Reliability
If multiple layers are used to control view angle and luminance, then privacy protection is improved, but power consumption increases
Solution Approach 1:
The patent merges the liquid crystal retarder with diffractive optical elements and polarizers into a single integrated optical stack, reducing the total number of components that require power. The unified structure eliminates redundant power-consuming elements while maintaining privacy protection through view-angle-controlled luminance reduction.
3Weight of moving object
If a thin, lightweight structure is used, then device portability is improved, but achieving high image visibility and privacy protection becomes more difficult
Solution Approach 1:
The patent implements a nested optical stack structure where the liquid crystal retarder, diffractive optical elements, and polarizers are arranged in a compact nested configuration. This nested arrangement achieves high image visibility and privacy protection within a thin, lightweight structure, eliminating the need for bulky separate layers while maintaining optical performance.
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 a thin, lightweight, and cost-effective display with improved image security and visibility, reducing stray light and power consumption by selectively controlling light output angles, suitable for applications like vehicle infotainment displays.
Implementation Method 1
the layer of liquid crystal material has a structure of orientations which causes the layer of liquid crystal material to introduce net phase shifts to light having a predetermined polarisation state that are uniform across an area of the layer of liquid crystal material and thereby cause the layer of liquid crystal material to provide no diffractive effect to the light having the predetermined polarisation state
Implementation Method 2
causes the SDVACRA to introduce net relative phase shifts to orthogonal polarisation components of the light having the predetermined polarisation state that differ along a viewing axis and an inclined axis that is inclined to the viewing axis
Implementation Method 3
the layer of liquid crystal material has a structure of orientations which causes the layer of liquid crystal material to introduce net phase shifts to the light having the predetermined polarisation state that vary spatially across the area of the layer of liquid crystal material and thereby cause the layer of liquid crystal material to provide a diffractive effect to the light having the predetermined polarisation state
Implementation Method 4
a transmissive electrode arrangement arranged to drive the layer of liquid crystal material, wherein the transmissive electrode arrangement is patterned to be capable of driving the layer of liquid crystal material selectively into a narrow-angle state
Data Source
AI summary
A switchable privacy display device comprises a spatial light modulator and a switchable diffractive view angle control retarder arrangement arranged between a display polariser of the spatial light modulator and an additional polariser. The display achieves high image visibility to an off-axis user in a share mode of operation and high image security to an off-axis snooper in privacy mode of operation.