Capacitive Touch Sensor Layout for Linear Multi-Position Detection
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Solution Overview
Problem
Conventional electrostatic capacity type touch sensors are limited in detecting a large number of touch positions and have issues with linearity and detection accuracy of touch positions.
Innovation Solution
The design includes a substrate with concentric common electric potential lines and axisymmetrical detection electrodes, utilizing a charge amplifier to generate output voltages proportional to capacitance differences, allowing for accurate detection of multiple touch positions with improved linearity and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional electrostatic capacity type touch sensor uses a limited number of detection electrodes, then the device complexity is reduced, but the ability to detect a large number of touch positions is limited
Solution Approach 1:
The detection area is divided into multiple segments by arranging detection electrodes in a matrix pattern with both X-axis and Y-axis electrodes. This segmentation allows the system to detect touch positions at multiple intersections without requiring a proportional increase in total electrodes, as each electrode serves multiple detection points along its axis.
Solution Approach 2:
Each detection electrode serves multiple functions by participating in detecting touch positions at multiple intersections. The X-axis electrodes and Y-axis electrodes both contribute to detecting touches at their intersection points, allowing a limited number of electrodes to monitor a larger number of positions through their combined detection capabilities.
2Measurement precision
If conventional touch sensors use simple electrode arrangements, then the device complexity is reduced, but the linearity of correlation between output and touch position deteriorates
Solution Approach 1:
The electrode arrangement is designed with specific local characteristics where detection electrodes are positioned to create distinct detection zones. The matrix configuration allows different regions of the touch surface to be monitored with optimized electrode spacing and positioning, improving the linearity of the correlation between output signal and touch position in each local area.
Solution Approach 2:
The detection system transitions from one-dimensional linear electrode arrangements to two-dimensional matrix arrangements. By introducing both X-axis and Y-axis electrodes that intersect, the system creates a grid of detection points that improves positional accuracy and linearity through the additional dimensional information provided by the orthogonal electrode configurations.
3Measurement precision
If conventional touch sensors use fewer detection points, then the device complexity is reduced, but the detection accuracy of touch positions deteriorates
Solution Approach 1:
The system merges the detection capabilities of X-axis electrodes and Y-axis electrodes at their intersection points. By combining the signals from perpendicular electrode pairs, the system achieves higher detection accuracy at each intersection point while using fewer total electrodes than would be required with a single-axis detection system.
Solution Approach 2:
The intersection points of the X-axis and Y-axis electrodes serve as intermediary detection points that provide precise touch position information. These intermediary points, created by the orthogonal arrangement, allow the system to achieve high detection accuracy without directly placing detection electrodes at every possible touch location.
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
This configuration enables the detection of a large number of touch positions with enhanced linearity and accuracy, improving the overall performance of the electrostatic capacity type touch sensor.
Implementation Method 1
a charge amplifier generating a first output voltage that is proportional to a capacitance difference between a capacitance of a first capacitor formed between the first detection electrode and the first and second common electric potential lines and a capacitance of a second capacitor formed between the second detection electrode and the first and second common electric potential lines
Data Source
AI summary
There is offered an electrostatic capacity type touch sensor capable of detecting a large number of touch positions with high accuracy. The electrostatic capacity type touch sensor is composed of a touch panel and a signal processing circuit. The touch panel is structured to include first through fourth detection electrodes, first and second common electric potential lines, a common electric potential wiring, a common electric potential terminal and first through fourth output terminals disposed on an insulating substrate. The signal processing circuit is structured to include a clock generator, a selection circuit, a charge amplifier, an A/D converter and an arithmetic unit. The charge amplifier detects a change in capacitance induced by that a finger of an operator touches the first through fourth detection electrodes.