Backside Pressure Electrode for Touch Input Devices
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Solution Overview
Problem
Current touch input devices struggle to detect touch pressure without compromising the visibility and optical transmittance of the display module, while also being cost-effective and thin.
Innovation Solution
A touch input device with a pressure electrode formed on the backside of the display panel, using a substrate with a reference potential layer to detect capacitance changes based on pressure applied, allowing for thin design and reduced manufacturing costs without affecting display quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a pressure sensing electrode is formed on the front side of the display panel, then touch pressure detection capability is improved, but the visibility and optical transmittance of the display module deteriorate
Solution Approach 1:
The pressure sensing electrode is inverted from the conventional front-side placement to the backside of the display panel. This inversion allows the electrode to be positioned away from the light path, thereby maintaining high optical transmittance and visibility while still enabling accurate touch pressure detection through capacitance changes.
2Measurement precision
If a separate reference potential layer is formed separately from the pressure electrode, then touch pressure detection accuracy is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The substrate serves multiple functions: it acts as both the structural base of the display module and the reference potential layer for capacitance-based pressure sensing. By integrating the reference potential function into the existing substrate, the design avoids adding separate reference layers, thereby maintaining detection accuracy while reducing structural complexity and manufacturing cost.
3Manufacturing precision
If a support member is disposed only on the circumference of the substrate, then the distance between pressure electrode and reference potential layer is maintained, but the device thickness is reduced
Solution Approach 1:
The support function is segmented from a full-substrate support structure to a circumferential-only support arrangement. Support members are placed only at the edges/circumference of the substrate, which is sufficient to maintain the required distance between the pressure electrode and reference potential layer while minimizing the overall device thickness and material usage.
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 accurate detection of touch pressure and position without degrading the display module's visibility or optical transmittance, while reducing manufacturing costs and achieving a thinner design.
Implementation Method 1
a pressure electrode which is formed on a back side of the display panel and is for detecting the pressure; and a substrate which is disposed under the display panel and comprises a reference potential layer which is formed separately from the pressure electrode. The touch input device detects the touch pressure on the basis of a capacitance change amount according to a change of a distance between the pressure electrode and the reference potential layer
Data Source
Figure 1
Figure 2A~2B
Figure 2C~2E
AI summary
A touch input device capable of detecting a touch pressure is provided that includes: a display module having a pressure electrode which is formed on a back side of the display panel and is for detecting the pressure; and a reference potential layer which is formed separately from the pressure electrode. The touch input device detects the touch pressure on the basis of a capacitance change amount according to a change of a distance between the pressure electrode and the reference potential layer. As a result of this, the touch input device becomes thinner, has a reduced manufacturing cost thereof, and detects a touch position and touch pressure without deteriorating the visibility and optical transmittance of the display module.