Integrated Touch Module with Low-Reflectance Circular Polarizer
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Solution Overview
Problem
Current anti-reflective coatings, such as those using chiral-quarter-wave and chiral-half-wave phase compensation films, have high reflectance in the visible light range, leading to suboptimal display performance, especially with high-resolution displays like 4K and 8K, and cannot be used directly as substrates for touch sensing structures, hindering the integration of thin and lightweight displays.
Innovation Solution
An integrated touch module is developed, combining a silver nanowire touch sensing structure with a polymer film that serves as both a substrate and phase retardation layer, utilizing a liquid crystal phase retardation layer and linear polarizing layer to achieve low and uniform reflectance across the visible light range, with the polymer film capable of withstanding the process temperature for the touch sensing structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If chiral-quarter-wave and chiral-half-wave phase compensation films are used as anti-reflective coatings, then the display can achieve circular polarization effect, but the reflectance in the visible light range remains too high (about 8%) to effectively remove ambient light reflection
Solution Approach 1:
The patent combines multiple materials with different optical properties: chiral liquid crystal material for quarter-wave compensation, stretched polymer film for half-wave compensation, and linear polarizing layer. This composite structure achieves wideband anti-reflective effect with reflectance below 5% across visible light range, solving the limitation of single-material coatings.
Solution Approach 2:
The patent optimizes key parameters including the thickness of each layer (quarter-wave layer: 50-200μm, half-wave layer: 200-500μm), the helical pitch of chiral liquid crystal (λ/4 to λ/2), and the stretching ratio of polymer film (200%-500%). These parameter adjustments enable precise control of optical path difference to achieve minimal reflectance across the visible spectrum.
2Illumination intensity
If traditional liquid crystal phase retardation layers are used, then optical compensation can be achieved, but they cannot be directly used as substrates for touch sensing structures, requiring additional adhesive layers and supporting substrates that increase thickness
Solution Approach 1:
The stretched polymer film serves multiple functions simultaneously: it provides half-wave phase compensation for optical performance, acts as a mechanical substrate for forming touch sensing electrodes, and eliminates the need for separate adhesive layers. This multi-functional design reduces total thickness while maintaining both optical and structural requirements.
Solution Approach 2:
The patent merges the phase retardation layer and the substrate function into a single stretched polymer film structure. The touch sensing electrodes are directly formed on this film, combining optical compensation and mechanical support functions that were previously separated into multiple layers, thereby achieving ultra-thin profile.
3Length of stationary object
If the polymer film is made thin to achieve ultra-thin and bendable displays, then the flexibility and thinness are improved, but the film must still withstand the process temperature for forming the touch sensing structure
Solution Approach 1:
The patent selects polymer materials with specific glass transition temperatures (Tg) above the touch electrode formation process temperature (typically Tg > 150°C). The stretching ratio is optimized (200%-500%) to achieve the desired thickness while maintaining thermal stability. These parameter choices enable the thin film to withstand high-temperature processing without deformation or loss of optical properties.
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 results in a bendable and ultra-thin integrated touch module with average reflectance less than 5% and standard deviation less than 0.2% across the visible light range, enhancing display quality and allowing the polymer film to function as a direct substrate without additional support, meeting the requirements for thinner and lighter displays.
Implementation Method 1
the linear polarizing layer 10a converts the incident light L into a linearly polarized incident light L1, and the polarization direction of the linearly polarized incident light L1 is vertical
Implementation Method 2
the linearly polarized incident light L1 enters the quarter-wave plate used as the retarder 20a, so that the linearly polarized incident light L1 produces a phase delay, and the linearly polarized incident light L1 is converted into left-handed polarized light Lcl
Implementation Method 3
a polymer film, a liquid crystal phase retardation layer, and a linear polarizing layer constitute a circular polarizing element, an average reflectance of the circular polarizing element in a visible light range is less than 5%
Data Source
AI summary
An integrated touch module and a touch display device are provided. The integrated touch module has a touch sensing structure formed on a polymer film. The polymer film, a liquid crystal phase retardation layer, and a linear polarizing layer constitute a circular polarizing element. The average reflectance of the circular polarizing element in the visible light range is less than 5%, and the standard deviation of the reflectance is less than 0.2%. The touch display device includes the integrated touch module.