Laminated Piezoelectric Body With Charge Dispersion for Touch Sensitivity
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Solution Overview
Problem
Laminated piezoelectric bodies using fluorine-based resins for touch panels suffer from weak signal intensity due to localized charge density saturation, leading to low sensitivity and high noise ratios, which complicates precise pressure detection.
Innovation Solution
A laminated piezoelectric body design incorporating a fluorine-based resin piezoelectric film with a charge dispersion layer and transparent electrode, where the charge dispersion layer has a specific surface resistivity and thickness, enhancing charge mobility and uniformity, and maintaining transparency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a transparent adhesive layer is used to laminate the transparent electrode film on the piezoelectric film, then the manufacturing process becomes simpler and existing transparent electrode films can be used, but the signal intensity becomes weak and detection sensitivity decreases
Solution Approach 1:
The patent applies local quality by creating a charge dispersion layer with specific electrical properties (surface resistivity of 1.0×10^4 to 1.0×10^8 Ω/sq) at the interface between the piezoelectric film and transparent electrode film. This localized functional layer improves charge collection efficiency without affecting the overall lamination structure or transparency, thereby enhancing detection sensitivity while maintaining ease of manufacture.
2Measurement precision
If the piezoelectric constant d33 is increased to improve signal intensity, then pressing detection sensitivity improves, but the charge density becomes saturated locally which limits further improvement
Solution Approach 1:
The charge dispersion layer acts as an intermediary between the piezoelectric film and transparent electrode film. It mediates the charge transfer process by providing a controlled electrical pathway that prevents charge saturation at the interface, thereby maintaining signal stability and enabling continuous improvement of detection sensitivity without hitting the saturation limit.
3Illumination intensity
If heat treatment is applied to increase ITO crystallinity and reduce resistance, then transparency and electrode performance improve, but the color tone changes and transparency is hard to maintain
Solution Approach 1:
The patent changes the electrical parameters at the interface by introducing a charge dispersion layer with optimized surface resistivity. This parameter change allows the system to achieve low resistance and high transparency without requiring high-temperature heat treatment that would cause color tone changes, thereby simplifying the manufacturing process while maintaining electrode performance.
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 design enables high sensitivity pressure detection while preserving transparency, effectively addressing the signal intensity issues in existing laminated piezoelectric bodies.
Implementation Method 1
a piezoelectric film containing, as a main component, a fluorine-based resin and having a piezoelectric constant d33 of 7 pC/N or more and 40 pC/N or less
Implementation Method 2
a charge dispersion layer disposed on at least one surface of the piezoelectric film, the charge dispersion layer having a surface resistivity of 1.0 × 10^4 to 1.0 × 10^8 Ω/sq
Data Source
Figure 1
Figure 2
AI summary
A laminated piezoelectric body includes: a piezoelectric film containing, as a main component, a fluorine-based resin and having a piezoelectric constant d33 of 7 pC/N or more and 40 pC/N or less; a charge dispersion layer disposed on at least one surface of the piezoelectric film, the charge dispersion layer having a surface resistivity of 1.0 × 104 Ω/sq. or more and 1.0 × 1012 Ω/sq. or less; a transparent electrode; and a transparent adhesive layer disposed between the transparent electrode and the charge dispersion layer. The laminated piezoelectric body has a total light transmittance of 80% or more.