Transparent Capacitive Touch Layer for Position and Pressure Sensing
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Solution Overview
Problem
Conventional touch input devices for mobile devices face challenges in accurately detecting touch position and pressure magnitude due to reduced sensitivity, reliability issues with multi-touch recognition, and decreased light transmittance caused by thick electrode layers and insulating layers.
Innovation Solution
A touch input device design featuring a display module with a first and second electrode spaced apart, a spacer layer covering them, and a transparent ground electrode that alters the electric field region, allowing for increased capacitance detection of touch position and pressure magnitude without separate sensors for position and pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a force sensor is integrated to recognize the strength of the touch, then the magnitude of pressure can be detected, but the sensitivity is reduced and the reliability of multi-touch recognition is decreased
Solution Approach 1:
The patent merges the touch sensor and force sensor into a single integrated sensor that can detect both touch position and pressure magnitude simultaneously. The sensor uses a capacitive structure where the touch object forms one electrode and the sensor electrode forms another, with the insulating layer acting as the dielectric. This integration eliminates the need for separate touch and force sensing systems, resolving the contradiction between pressure detection capability and multi-touch recognition reliability.
Solution Approach 2:
The integrated sensor performs multiple functions: it detects touch position through capacitance changes and simultaneously measures pressure magnitude through the same capacitive structure. The sensor electrode and insulating layer serve dual purposes for both touch detection and force sensing, making the system universal and eliminating the reliability issues associated with separate sensor systems.
2Measurement precision
If electrode layers and insulating layers are added for force sensing, then pressure detection is enabled, but light transmittance is decreased
Solution Approach 1:
The patent uses a thin insulating layer as the dielectric between the sensor electrode and touch object. This thin film structure enables force sensing functionality while minimizing the impact on light transmittance. The insulating layer is sufficiently thin to maintain optical performance while still providing the necessary dielectric properties for capacitive force detection.
3Adaptability or versatility
If a touch sensor and force sensor are integrated in the vertical direction, then both touch position and pressure magnitude can be detected, but the sensor structure becomes thicker and light transmittance is reduced
Solution Approach 1:
The patent combines touch sensing and force sensing into a single sensor layer rather than stacking them vertically. The sensor electrode and insulating layer work together to provide both touch position detection and pressure magnitude measurement simultaneously, eliminating the need for multiple vertical layers and reducing overall sensor thickness.
Solution Approach 2:
The integrated sensor performs both touch detection and force sensing functions within the same structural layer. The capacitive structure with the insulating layer serves dual purposes for both sensing modalities, making the sensor universal and eliminating the need for separate vertical integration of touch and force sensors.
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 design enhances sensitivity for pressure detection, maintains reliability for multi-touch recognition, and improves light transmittance by using a single sensor type and optimizing electrode placement.
Implementation Method 1
a capacitance between the first electrode and the second electrode is increased. A position of the touch and a pressure magnitude of the touch are detected based on the increased capacitance
Implementation Method 2
The transparent ground electrode is disposed at a height equal to or greater than a height at which an electric field region is formed between the first electrode and the second electrode
Implementation Method 3
a spacer layer which is formed on the display module and covers the first electrode and the second electrode
Data Source
AI summary
A touch input device which detects a touch position and a touch pressure magnitude may be provided that includes: a display module; a first electrode and a second electrode which are disposed on the display module and are spaced apart from each other; a spacer layer which is formed on the display module and covers the first electrode and the second electrode; and a transparent ground electrode which is disposed on the spacer layer and is formed of a material having transparency. A distance between the transparent ground electrode and the display module is changed by inputting a touch on the transparent ground electrode, and a capacitance between the first electrode and the second electrode is changed by the distance change. The position of the touch and the pressure magnitude of the touch are detected based on the changed capacitance.