Sensor Shielding Electrode Parasitic Capacitance Reduction
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Solution Overview
Problem
Current sensor technologies face challenges in accurately detecting fine uneven patterns, such as fingerprints, due to degradation in sensor sensitivity caused by parasitic capacitance and potential variations, which affect detection accuracy.
Innovation Solution
The sensor design incorporates a common electrode that electrically shields detection electrodes both within and outside the active area, along with a control line drive circuit and multiplexer, to suppress parasitic capacitance and potential variations, enabling precise detection by switching between self-capacitive and mutual-capacitive sensing modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a sensor uses conventional detection electrode configuration without extensive common electrode coverage, then device complexity is reduced, but parasitic capacitance increases causing detection accuracy degradation
Solution Approach 1:
The common electrode is segmented into multiple regions corresponding to different detection areas, with each segment independently controllable. This allows selective activation of electrode segments to minimize parasitic capacitance while maintaining detection accuracy in active areas.
Solution Approach 2:
The common electrode is maintained at a uniform potential across its entire surface through careful electrical connection design. This equipotential configuration minimizes potential variations and parasitic capacitance effects, improving detection accuracy without requiring complex electrode structures.
2Measurement precision
If the common electrode covers both active and outside areas extensively, then parasitic capacitance is suppressed improving detection accuracy, but manufacturing complexity increases
Solution Approach 1:
The common electrode serves multiple functions: it acts as a detection electrode in the active area, provides shielding in the outside area, and functions as a reference potential source. This multi-functionality reduces the need for separate structures, simplifying manufacturing while maintaining detection accuracy.
Solution Approach 2:
The common electrode structure merges the shielding function and detection function into a single integrated component. By combining these functions, the patent reduces the number of separate electrodes and connections needed, thereby simplifying the manufacturing process while suppressing parasitic capacitance.
3Measurement precision
If potential adjustment signals are applied to the common electrode synchronized with write signals, then detection sensitivity is enhanced, but energy consumption increases
Solution Approach 1:
The potential adjustment signal is applied periodically to the common electrode in synchronization with the write signal cycles. This periodic adjustment enhances detection sensitivity by maintaining optimal potential conditions during active sensing periods while allowing energy conservation during inactive periods.
Solution Approach 2:
The potential adjustment signal maintains continuous useful action during the sensing period by being synchronized with write signals. This ensures that the common electrode consistently provides optimal potential conditions for detection throughout the active sensing window, maximizing sensitivity while minimizing energy use during non-sensing periods.
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 configuration enhances detection accuracy and sensitivity by reducing parasitic capacitance and potential variations, allowing for effective detection of fine uneven patterns like fingerprints.
Implementation Method 1
a common electrode located above the control lines, the signal lines and the detection switches, opposed to the control lines, the signal lines and the detection switches, and including openings, each of the openings being opposed to one of the detection switches
Data Source
AI summary
A sensor is provided and includes a first control line; a first signal line; a first auxiliary line; a first detection electrode; a first detection switch connected to the first detection electrode, the first control line and the first signal line; and a first shielding electrode connected to the first auxiliary line, wherein the first shielding electrode is located to overlap the first signal line via an insulating film.