Touch Sensor Pixel Sharing Common Lines for Fingerprint Detection
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Solution Overview
Problem
Current touch sensors face challenges in miniaturization and integration for simultaneous touch and fingerprint sensing, particularly in efficiently managing sensor pixels and power supply to enhance accuracy and multi-touch capabilities.
Innovation Solution
A touch sensor design incorporating sensor pixels, a sensor scan driver, a power supply unit, and a read-out circuit, where adjacent sensor pixels share common lines, and alternating common voltages are used to determine touch events, allowing for efficient sensing of touch positions, pressures, and fingerprint patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If each sensor pixel is connected to separate common lines, then power supply and signal reading are simplified, but the number of lines increases and device area expands
Solution Approach 1:
Two adjacent sensor pixels share a common line, merging the function of separate lines into a shared resource. This reduces the total number of common lines from N (one per pixel) to N/2 (shared between pairs), directly addressing the contradiction by decreasing device complexity while maintaining manufacturability through the shared connection architecture
Solution Approach 2:
The system dynamically assigns different common voltages to shared common lines at different time periods, allowing sequential access to sensor pixels. This temporal dynamic approach enables the shared line to serve multiple pixels without permanent connection conflicts, resolving the contradiction between line reduction and manufacturing ease
2Area of stationary object
If adjacent sensor pixels share common lines, then the number of lines is reduced and device is miniaturized, but power supply management becomes more complex
Solution Approach 1:
The power supply unit alternates between providing first common voltage and second common voltage to shared common lines in different time periods. This periodic voltage assignment allows sequential activation of different sensor pixel groups, enabling miniaturization through shared lines while managing power supply complexity through time-division multiplexing
Solution Approach 2:
Sensor pixels are divided into groups that share common lines, with each group activated at different time periods. This segmentation allows the power supply unit to manage fewer simultaneous connections while maintaining comprehensive coverage, reducing device area through sharing while organizing power supply management into manageable temporal segments
3Measurement precision
If alternating common voltages are applied to shared lines, then touch sensing accuracy is improved, but the control mechanism becomes more complex
Solution Approach 1:
The read-out circuit detects output signals from sensor pixels through shared common lines and determines touch events based on the presence or absence of signals during specific time periods. This feedback mechanism enables accurate touch sensing by comparing expected vs. actual signal patterns, improving measurement precision while the control complexity is managed through systematic voltage assignment rules
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 enables miniaturized and integrated touch sensors that effectively detect touch positions, pressures, and fingerprint patterns with improved accuracy and reduced line requirements, enhancing multi-touch capabilities and sensor efficiency.
Implementation Method 1
A capacitive touch sensor senses a point at which capacitance is changed as a hand of a user or an object is in contact therewith, thereby detecting a touch position
Data Source
AI summary
A touch sensor includes: a plurality of sensor pixels; a sensor scan driver for supplying sensor scan signals to the sensor pixels through sensor scan lines; a power supply unit for supplying common voltages to the sensor pixels through common lines; and a read-out circuit connected to the sensor pixels through the common lines, the read-out circuit configured to sense a touch by using an output signal output through the common lines, wherein two sensor pixels adjacent to each other among the sensor pixels share one common line.