Touch Input Device Pressure Detection via Capacitance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current touch input devices that incorporate a display module struggle to detect touch pressure without compromising the thickness, manufacturing cost, or visibility and light transmittance of the display module.
Innovation Solution
A touch input device design featuring a display module with a first and second glass or plastic layer, touch electrodes, and a reference electrode, where the distance between the electrodes changes with bending, allowing for capacitance-based detection of touch pressure without degrading the display's performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a separate pressure detection module is added to the touch screen, then touch pressure detection capability is improved, but device thickness and manufacturing cost increase
Solution Approach 1:
The patent merges the pressure detection function with the existing display module by integrating touch electrodes directly into the display structure. The display module serves dual purposes: displaying visual information and detecting touch pressure through capacitance changes, eliminating the need for separate pressure detection modules and reducing overall device complexity.
Solution Approach 2:
The display module is designed to perform multiple functions simultaneously. It not only displays visual content but also detects touch position and pressure magnitude through integrated touch electrodes. This multi-functionality approach allows the same structural component to serve both display and sensing purposes, reducing the need for additional dedicated pressure sensors.
2Device complexity
If touch electrodes are integrated into the display module, then device thickness is reduced, but visibility and light transmittance of the display module may be degraded
Solution Approach 1:
The patent employs thin-film technology for the touch electrodes, using transparent conductive materials deposited as thin layers on the display substrate. This thin-film approach minimizes the optical impact while maintaining electrical functionality, allowing light to pass through with minimal attenuation and preserving display visibility.
Solution Approach 2:
The touch electrodes utilize transparent conductive materials that are optically transparent in the visible spectrum. By selecting materials with appropriate optical properties, the electrodes maintain electrical conductivity while being visually transparent, thus not degrading the visibility or light transmittance of the display module.
3Measurement precision
If the distance between touch electrode and reference electrode is reduced to improve pressure sensitivity, then capacitance change increases, but manufacturing precision requirements increase
Solution Approach 1:
The patent incorporates a spacer layer between the touch electrode and reference electrode during the manufacturing process. This spacer layer pre-establishes a controlled distance relationship, eliminating the need for post-manufacturing adjustment and reducing the precision requirements for final assembly. The spacer ensures consistent electrode spacing across all devices.
Solution Approach 2:
The patent optimizes the capacitance detection parameters and electrode geometry to achieve sufficient pressure sensitivity without requiring extremely small electrode distances. By adjusting detection sensitivity parameters and electrode design, the system achieves adequate pressure detection capability while maintaining relaxed manufacturing tolerance requirements.
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
Enables simultaneous detection of touch position and pressure with a thinner, cost-effective, and high-transmittance display module, maintaining visibility and reducing manufacturing costs.
Implementation Method 1
An electrical signal which is changed by a capacitance between the touch electrode and the reference electrode is detected from the touch electrode. The capacitance is changed by change of a distance between the touch electrode and the reference electrode.
Data Source
AI summary
A touch input device detecting a touch position and a touch pressure includes a display module having a first layer made of glass or plastic and a second layer disposed under the first layer and made of glass or plastic; touch electrodes formed within the display module for detecting the touch position and the touch pressure; and a reference electrode disposed apart from the touch electrode. The touch position is detected by a sensing signal received from the touch electrode. An electrical signal changed by a capacitance between the touch electrode and the reference electrode is detected from the touch electrode. The capacitance is changed by change of a distance between the touch electrode and the reference electrode. The distance between the touch electrode and the reference electrode is changed by the bending of the display module. The touch pressure is detected based on the capacitance.