Privacy Touch Screen with LC Retarder Noise Shielding
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Solution Overview
Problem
Existing privacy displays lack switchable functionality for controlling off-axis optical output, and touch screens are not efficiently integrated with directional displays to provide high contrast and luminance for on-axis viewing while reducing visibility for off-axis positions.
Innovation Solution
A touch input display device with a spatial light modulator (SLM), a switchable liquid crystal retarder, and passive retarders, where touch electrode arrays are formed on the surfaces of passive retarders, allowing for high contrast and luminance in on-axis viewing and low luminance in off-axis positions, with reduced thickness and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If micro-louvre optical films are used for privacy display, then off-axis luminance is reduced, but the display loses electrical switchability
Solution Approach 1:
The patent combines micro-louvre optical films with switchable liquid crystal retarders and polarisers to create a hybrid system that merges the off-axis luminance control of micro-louvre films with the electrical switchability of liquid crystal technology, resolving the contradiction between privacy function and switchability
Solution Approach 2:
The invention uses composite optical structures combining multiple materials and components (micro-louvre films, liquid crystal layers, polarisers, compensation retarders) to achieve both privacy display functionality and electrical controllability simultaneously
2Adaptability or versatility
If switchable liquid crystal retarders and polarisers are added to provide electrical switchability, then device complexity increases
Solution Approach 1:
The liquid crystal retarder layer serves multiple functions simultaneously: it controls the privacy state by adjusting optical retardation, maintains display visibility through compensation, and enables touch sensing functionality, thereby reducing the need for separate dedicated components
Solution Approach 2:
The invention controls privacy display states by changing the optical parameters (retardation, orientation) of liquid crystal layers through voltage application, allowing dynamic adjustment of off-axis luminance without adding mechanical moving parts or complex switching mechanisms
3Measurement precision
If touch electrode arrays are placed on passive retarders, then touch sensitivity is enhanced, but manufacturing precision requirements increase
Solution Approach 1:
The passive retarder layer serves dual purposes: it provides optical compensation for the liquid crystal display and simultaneously serves as the substrate for mounting touch electrode arrays, eliminating the need for separate touch sensor substrates and simplifying manufacturing alignment
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 switchable privacy display with enhanced touch sensitivity and reduced thickness, cost, and improved accuracy by integrating touch sensing with directional control, maintaining high visibility for on-axis users and low visibility for off-axis viewers.
Implementation Method 1
a switchable liquid crystal retarder comprising a layer of liquid crystal material arranged between the display polariser and the additional polariser, wherein the switchable liquid crystal retarder is a polar direction control retarder that is arranged, in a switchable state of the switchable liquid crystal retarder, simultaneously to introduce no net relative phase shift to orthogonal polarisation components of light passed by the display polariser along an axis along a normal to the plane of the switchable liquid crystal retarder and introduce a relative phase shift to orthogonal polarisation components of light passed by the display polariser along an axis inclined to a normal to the plane of the switchable liquid crystal retarder
Implementation Method 2
a display polariser arranged on the output side of the SLM, wherein the display polariser is a linear polariser; an additional polariser arranged on the output side of the display polariser, wherein the additional polariser is a linear polariser
Implementation Method 3
TW-1612360 discloses a touch input display device comprising... capacitive touch... and a touch sensing element, including a single-layer or multi-layer electrodes
Data Source
Figure 1A
Figure 1B
Figure 2A
AI summary
A display comprises a polarised output spatial light modulator, switchable liquid crystal retarder, absorbing polariser and touch panel electrodes. The electrodes of the switchable liquid crystal retarder shield the touch panel electrodes from the electrical noise of the spatial light modulator addressing. The touch panel control and sensing may be synchronised with the driving signal of the switchable liquid crystal retarder. The touch panel may be operated independently of the timing of the data addressing of the spatial light modulator.