Dual-View Automotive Display Using Polarisation Switching to Cut Cross-Talk
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Solution Overview
Problem
Existing privacy displays face challenges in controlling illumination to reduce cross-talk between users, particularly in automotive settings, where micro-louvre optical films cause high losses and Moire artefacts, and require complex inventory and cost management for panel resolution.
Innovation Solution
A display device comprising a spatial light modulator, a linear polariser, an additional polariser, and polarisation-switch retarders that can switch between two polarisation states, allowing for dual view or share modes of operation to reduce cross-talk and improve image contrast by controlling luminance and polarisation states.
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 are high
Solution Approach 1:
The patent changes the optical parameters by using variable retardance films that can dynamically adjust their optical properties. The first variable retardance film has a first retardance value that varies across different regions, and the second variable retardance film has a second retardance value that varies across different regions. This allows the system to control light transmission differently for on-axis and off-axis viewing angles, reducing privacy display leakage while maintaining head-on illumination efficiency.
2Object-affected harmful factors
If micro-louvre optical films are used to provide privacy function, then off-axis visibility is reduced, but Moire artefacts occur due to beating with pixels
Solution Approach 1:
The patent uses variable retardance films with spatially varying optical parameters instead of fixed micro-louvre structures. The retardance values vary continuously across the film surfaces, which prevents the periodic interference patterns that cause Moire artefacts. This approach maintains the ability to control off-axis visibility while eliminating the beating effects with display pixels.
3Manufacturing precision
If micro-louvre pitch is selected for panel resolution, then display quality is maintained, but inventory and cost increase
Solution Approach 1:
The patent employs variable retardance films that can serve multiple functions: they maintain display resolution quality, provide privacy control, and reduce Moire artefacts, all within a single integrated component. The films are designed with specific retardance profiles that work across different display configurations, reducing the need for multiple specialized components and thereby lowering inventory complexity and cost.
4Object-affected harmful factors
If switchable backlights are used to control off-axis optical output, then privacy function is provided, but device complexity increases
Solution Approach 1:
The patent replaces the mechanical switchable backlight system with an optical solution using variable retardance films. Instead of physically switching between different backlight configurations, the system uses the optical properties of the variable retardance films to control light transmission dynamically. This substitution eliminates the mechanical complexity of switchable backlights while achieving the same privacy control function.
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 effectively reduces cross-talk between driver and passenger images, enhancing privacy and image contrast, while also allowing for shared high luminance and contrast views when safe, thereby improving safety and usability in automotive environments.
Implementation Method 1
a view angle control arrangement comprising: an additional polariser arranged on the same side of the spatial light modulator as the display polariser, the additional polariser being a linear polariser; and at least one polar control retarder and a polarisation-switch retarder arranged between the display polariser and the additional polariser
Implementation Method 2
a display polariser arranged on a side of the spatial light modulator, the display polariser being a linear polariser
Data Source
AI summary
A dual view display for an automotive vehicle comprises a spatial light modulator and a polar control retarder comprising a switchable liquid crystal retarder arranged between a first pair of polarisers. The switchable liquid crystal retarder comprises a polarisation-switch retarder and a polar control retarder with an average director that is directed towards an off-axis viewing location. In a first temporal phase of operation, the spatial light modulator and polar control retarder are arranged to direct light comprising a first image towards a first direction and in a second temporal phase of operation to direct light comprising a second image towards a second direction.