Optical Touch Panel Using Liquid Crystal Modulation for Anti-Interference
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current touch panels face challenges with accuracy due to electromagnetic interference and thickness issues, as capacitive and resistive panels are prone to interference and infrared panels require additional components that increase thickness, making them difficult to achieve precise and thin touch control.
Innovation Solution
A touch panel comprising a liquid crystal layer sandwiched between substrates with optical detection layers that convert light intensity into electric signals, using polarizers and a black matrix to separate pixels and allow infrared light passage, enabling accurate touch detection without external infrared emitters and detectors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If capacitive or resistive touch control is used, then the touch panel can be manufactured with current mainstream technologies, but the panel becomes prone to electromagnetic wave interference and achieves poor measurement precision
Solution Approach 1:
The patent replaces electromagnetic field-based detection (capacitive/resistive) with optical field-based detection. Light sources emit light that passes through the liquid crystal layer, and photodetectors detect changes in light intensity or polarization caused by touch-induced liquid crystal molecule reorientation, thereby determining touch position. This substitution eliminates susceptibility to electromagnetic interference while achieving accurate touch control.
Solution Approach 2:
The patent introduces liquid crystal molecules as an intermediary between the touch input and the detection system. When touched, the liquid crystal molecules reorient, modulating the optical properties (intensity or polarization) of transmitted light. This intermediary converts mechanical touch into optical signals that can be detected by photodetectors, achieving both anti-interference capability and measurement precision.
2Measurement precision
If infrared touch control technology is used to improve touch detection capability, then touch control accuracy can be enhanced, but the panel thickness increases due to additional external infrared emitters and detectors
Solution Approach 1:
The patent merges the display function and touch detection function into a single integrated structure. The liquid crystal layer serves both as the display medium and the touch sensing element. The same light sources and photodetectors used in the display system are utilized for touch detection, eliminating the need for separate infrared emitters and detectors, thereby reducing panel thickness while maintaining touch detection capability.
Solution Approach 2:
The patent makes the liquid crystal layer and optical components multi-functional. The liquid crystal layer not only controls light for display purposes but also modulates light in response to touch for sensing purposes. The photodetectors serve both to detect display light and to detect touch-induced light changes. This multi-functionality eliminates the need for dedicated thick infrared components.
3Measurement precision
If optical detection layers are added to the touch panel, then touch accuracy is improved, but the device complexity increases
Solution Approach 1:
The patent combines the optical detection layers with the existing display structure. The light sources are positioned behind the substrate, and photodetectors are integrated into the display panel layers. The liquid crystal layer itself serves as the sensing element, eliminating the need for separate complex sensing structures. This merging approach improves touch accuracy while minimizing additional complexity.
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 enhances touch accuracy by minimizing electromagnetic interference and reduces panel thickness, allowing for thinner and lighter designs with improved multi-point touch control capabilities.
Implementation Method 1
a liquid crystal layer, which comprises a plurality of liquid crystal molecules
Implementation Method 2
Each of the plurality of first optical detection components is configured to detect, and to convert into a first electric signal, an intensity of a light transmitting through the liquid crystal layer and shedding thereupon
Implementation Method 3
The first polarizer is disposed over a light-incident surface of the first substrate, and the second polarizer is disposed between the liquid crystal layer and the first optical detection layer
Data Source
AI summary
A touch panel includes a first substrate, a liquid crystal layer, a second substrate, a first optical detection layer, and a black matrix. The first optical detection layer is over a light-emitting surface of the liquid crystal layer and includes a plurality of first optical detection components, whose orthographic projections on the first substrate are within an orthographic projection of the black matrix. A touch control can be determined based on a change of a first electric signal converted by each first optical detection component based on an intensity of a light transmitting through the liquid crystal layer. The light can be an infrared light. A plurality of second optical detection components can be further disposed over a light-incident surface of the liquid crystal layer to pairingly correspond to, and utilized to determine a touch control along with, the plurality of first optical detection components.