Integrated Touch Panel Using Piezoelectric and Capacitive Sensing
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Solution Overview
Problem
Existing touch panels require separate sensors for detecting touch position and force, leading to increased thickness and complexity in manufacturing, as well as limitations in sensing changes in touch force over time.
Innovation Solution
Integration of a piezoelectric type touch sensor and a capacitive type touch sensor in a single panel, using an electroactive layer with shared driving electrodes, allowing for simultaneous detection of touch position, force, and changes in force through piezoelectric and capacitive sensing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate touch position sensor and force sensor are provided, then touch position and touch force can be measured, but device thickness increases and manufacturing process becomes complex
Solution Approach 1:
The patent combines a capacitive touch position sensor and a piezoelectric force sensor into a single integrated touch panel structure. The capacitive sensor includes first and second electrodes for detecting touch position, while the piezoelectric sensor uses a piezoelectric layer between electrodes to detect touch force. This merging eliminates the need for separate sensor assemblies, thereby reducing device thickness and simplifying the manufacturing process while maintaining both touch position and force detection capabilities.
2Measurement precision
If capacitive type force sensor is used, then transparency and sensitivity are improved, but device thickness increases due to insulating layer requirements
Solution Approach 1:
The patent employs a piezoelectric layer as a thin film structure that can detect touch force without requiring a thick insulating layer. The piezoelectric layer is positioned between electrodes and generates electrical signals in response to applied pressure, enabling sensitive touch force detection while maintaining a thin overall device profile. This approach avoids the thickness penalty associated with traditional capacitive force sensors that require substantial insulating layers.
3Ease of manufacture
If resistive type force sensor is used, then manufacturing process is simplified, but measurement precision and integration with touch sensor is insufficient
Solution Approach 1:
The patent utilizes a piezoelectric material layer that combines the manufacturing simplicity of resistive sensors with the superior measurement precision of piezoelectric effects. The piezoelectric layer can be integrated into the existing electrode structure using conventional thin-film deposition techniques, maintaining ease of manufacture while providing high-precision touch force detection through the piezoelectric effect, which generates electrical charges in response to mechanical stress.
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 solution reduces the thickness and manufacturing complexity of touch panels while enabling the detection of touch position, force, and force changes, enhancing the sensitivity and flexibility of the touch panel for various display devices.
Implementation Method 1
an electroactive layer, a plurality of driving electrodes on one side of the electroactive layer, the driving electrodes configured to transmit a driving signal
Implementation Method 2
the first sensing electrodes transmitting voltage signals generated responsive to deformation of the electroactive layer
Implementation Method 3
The second sensing electrodes transmit capacitance signals indicating a change in capacitance between the driving electrodes and the sensing electrodes
Data Source
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AI summary
A touch panel includes a plurality of first electrodes which extends in a first direction. The touch panel further includes an electroactive layer which is disposed on the plurality of first electrodes and is formed of an electroactive material. The touch panel further includes a plurality of second electrodes which is disposed on the electroactive layer and extends in a second direction which is different from the first direction. The touch panel further includes an insulating layer which is disposed to cover the electroactive layer and the plurality of second electrodes. The touch panel further includes a plurality of third electrodes which is disposed on the insulating layer and extends in the second direction.