Non-overlapping Piezoelectric and Electrostatic Touch Sensor Design
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional touch sensors face reduced detection sensitivity due to the interference between piezoelectric pressure detection sensors and electrostatic position detection sensors, where the piezoelectric electrodes act as electromagnetic shields, hindering the detection of finger touches.
Innovation Solution
The configuration includes a pressure detection sensor with piezoelectric detecting electrodes on opposed sides of a piezoelectric film and an electrostatic position detection sensor with position detecting electrodes on opposed sides of a dielectric substrate, with the electrodes positioned differently to avoid overlap, allowing for high-sensitivity detection of static electricity and pressure variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If piezoelectric detecting electrodes are provided on the substantially whole principal surfaces of the piezoelectric material, then pressure detection coverage is improved, but the piezoelectric detecting electrode acts as an electromagnetic shield that degrades position detection sensitivity
Solution Approach 1:
The piezoelectric detecting electrodes are segmented and arranged only in the peripheral region of the piezoelectric material, rather than covering the entire principal surface. This segmentation allows the central region to remain free of electrodes, eliminating the electromagnetic shielding effect in the position detection area while still enabling pressure detection through the peripheral electrodes.
Solution Approach 2:
Different regions of the piezoelectric material are assigned different functions: the peripheral region contains piezoelectric detecting electrodes for pressure detection, while the central region is kept free of electrodes to maintain position detection sensitivity. This local differentiation resolves the contradiction by optimizing each region for its specific purpose.
2Device complexity
If the pressure detection sensor is disposed on the operation surface side of the electrostatic type position detection sensor, then structural configuration is simplified, but the piezoelectric detecting electrode interferes with the electrostatic type position detection sensor
Solution Approach 1:
The piezoelectric detecting electrodes are segmented to occupy only the peripheral region, creating a clear spatial separation between the pressure detection function (periphery) and position detection function (center). This segmentation allows the simplified stacked structure to function properly without electromagnetic interference in the position detection area.
3Area of stationary object
If piezoelectric detecting electrodes cover the whole principal surface, then pressure detection area is maximized, but detection sensitivity of finger touch degrades due to electromagnetic shielding
Solution Approach 1:
The piezoelectric detecting electrodes are segmented and positioned only in the peripheral region, creating a balance between pressure detection area and position detection sensitivity. The peripheral electrodes provide sufficient pressure detection capability while leaving the central area free for accurate position detection without electromagnetic shielding.
Solution Approach 2:
The electrode distribution is made non-uniform with higher density at the periphery and zero density at the center. This local quality differentiation optimizes both pressure detection (periphery) and position detection (center) simultaneously, resolving the area-sensitivity contradiction.
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 enhances the sensitivity of touch detection on an operation surface by preventing electrode overlap, allowing for accurate detection of touch positions and pressing forces while maintaining translucency and reducing temperature-induced sensitivity variations.
Implementation Method 1
a pressure detection sensor that includes a piezoelectric film in which piezoelectric detecting electrodes are arranged on opposed sides thereof
Implementation Method 2
an electrostatic type position detection sensor that includes a dielectric substrate in which position detecting electrodes are arranged on opposed sides thereof
Data Source
AI summary
A touch sensor that includes a pressure detection sensor and a position detection sensor. The pressure detection sensor and the position detection sensor are sequentially disposed from an operation surface side of the touch sensor. The position detection sensor includes a dielectric substrate, first position detecting electrodes on a first principal surface of the dielectric substrate, and second position detecting electrodes on a second principal surface of the dielectric substrate. The pressure detection sensor includes a piezoelectric film, a first piezoelectric detecting electrode on a first principal surface of the piezoelectric film, and a second piezoelectric detecting electrode on a second principal surface of the piezoelectric film. The first and second piezoelectric detecting electrodes are disposed so as to not overlap the first and second position detecting electrodes.