Touch Sensor Strain Gauge Pressure Detection
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Solution Overview
Problem
Current touch sensors for display devices lack the capability to effectively detect pressure inputs, relying solely on capacitance changes which can be unreliable for precise pressure measurement.
Innovation Solution
A touch sensor design incorporating a strain gauge with resistance lines and a Wheatstone bridge circuit, which changes resistance values in response to pressure, allowing for accurate pressure detection in addition to capacitive touch position sensing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a pressure sensor is added to detect pressure inputs, then pressure detection capability is improved, but device complexity increases
Solution Approach 1:
The patent combines the pressure detection function with the existing touch electrode structure by forming a strain gauge using the same conductive material and fabrication process. The strain gauge is integrated into the touch sensor layer structure, merging pressure sensing with the existing capacitive touch electrode system, thereby adding pressure detection capability without significantly increasing device complexity
Solution Approach 2:
The conductive material and fabrication process serve multiple functions: they form both the capacitive touch electrodes for position detection and the strain gauge elements for pressure detection. This multi-functionality allows a single structural element to perform both sensing functions, reducing the need for separate dedicated pressure sensor components
2Measurement precision
If resistance lines are arranged in specific patterns to form strain gauge, then pressure measurement precision is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent utilizes the piezoresistive effect, where the resistance of the conductive lines changes in response to mechanical strain applied to the substrate. By arranging the resistance lines in specific grid patterns and utilizing the change in resistance values under pressure, the system achieves precise pressure measurement. The specific resistance line arrangements create measurable resistance changes that correspond to applied pressure, enabling accurate detection while using standard fabrication processes
3Ease of manufacture
If touch electrodes and resistance lines are formed in the same layer, then ease of manufacture is improved, but measurement precision may be compromised
Solution Approach 1:
The patent segments the functional elements within the same layer by creating distinct patterns: touch electrodes are arranged in specific configurations for capacitive sensing, while resistance lines are arranged in separate grid patterns for pressure sensing. This segmentation allows both functions to coexist in the same layer without interfering with each other, maintaining ease of manufacture while preserving measurement precision through distinct spatial arrangements
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 precise pressure measurement and improved touch input recognition, enhancing the functionality of display devices by combining capacitive touch position detection with pressure sensitivity.
Implementation Method 1
a strain gauge including rows of resistance lines arranged along the second direction, each of the rows of resistance lines including: resistance lines arranged in the first direction and electrically connected to each other along the first direction
Implementation Method 2
the resistance lines all connected to each other in series
Data Source
AI summary
A display device includes: a base substrate; a light emitting element located on the base substrate; a thin-film encapsulation layer located on the light emitting element; touch electrodes located on the thin-film encapsulation layer, each of the touch electrode including an opening; and a strain gauge including: resistance lines located in the openings, respectively, the resistance lines located in the same layer as the touch electrodes and having variable resistance values changed in response to a touch input; a first connection line connecting two resistance lines neighboring each other along a first direction; and a second connection line connecting two resistance lines neighboring each other along a second direction, the second direction intersecting the first direction, wherein the first connection line and the second connection line are located between the thin-film encapsulation layer and the resistance lines.