Fingerprint Identification Substrate Shielding Layer Noise Reduction
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Solution Overview
Problem
Existing fingerprint identification technologies face challenges in accurately distinguishing between fingerprint ridges and valleys due to noise interference and signal degradation, leading to reduced signal-to-noise ratio and fingerprint collection accuracy.
Innovation Solution
The proposed fingerprint identification substrate incorporates a shielding layer insulated from the detection electrode, which is electrically coupled to a grounded line or an excitation signal source. This configuration reduces noise interference and enhances signal collection accuracy by minimizing crosstalk between the detection electrode and the driving circuitry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a shielding layer is added between the detection electrode and driving circuitry to reduce noise interference, then the signal-to-noise ratio is improved, but the device complexity increases
Solution Approach 1:
A shielding layer is introduced as an intermediary component between the detection electrode and the driving circuitry. This shielding layer acts as a mediator to block noise interference from the driving circuitry from reaching the detection electrode, thereby improving the signal-to-noise ratio without fundamentally changing the core detection mechanism.
Solution Approach 2:
The substrate structure is segmented into distinct functional layers: the base substrate, the driving circuitry layer, the shielding layer, and the detection electrode layer. This segmentation allows each layer to perform its specific function independently, with the shielding layer specifically tasked with noise reduction, thus improving reliability while maintaining manageable complexity through modular design.
2Object-affected harmful factors
If the shielding layer is electrically coupled to the grounded line to reduce noise, then the noise interference is reduced, but the parasitic capacitance increases
Solution Approach 1:
The harmful parasitic capacitance effect is extracted and isolated by providing an escape path through the via hole to the grounded line. This allows the parasitic capacitance to be deliberately managed and discharged in a controlled manner rather than allowing it to accumulate and degrade the fingerprint signal.
Solution Approach 2:
The parasitic capacitance, which is inherently harmful to signal quality, is converted into a beneficial element by providing a controlled discharge path. The via hole connecting the shielding layer to the grounded line allows the parasitic capacitance to be rapidly discharged, transforming what would be a source of noise into a controlled electrical characteristic that can be managed within the circuit design.
3Object-affected harmful factors
If the orthogonal projection of the shielding layer onto the base substrate at least partially overlaps the orthogonal projection of the detection electrode onto the base substrate, then the noise shielding effectiveness is improved, but the area occupied by the device increases
Solution Approach 1:
The shielding effectiveness is achieved by utilizing the vertical dimension (z-axis) rather than expanding the horizontal footprint. The shielding layer is positioned in the third dimension between the detection electrode and the driving circuitry, allowing overlapping projections without increasing the overall device area, thus maintaining a compact form factor while improving noise shielding.
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
The solution effectively increases the signal-to-noise ratio, improves fingerprint collection accuracy, and enhances the reliability of fingerprint identification by inhibiting charging and discharging of parasitic capacitors, thereby producing higher definition fingerprint images.
Implementation Method 1
a shielding layer arranged at a side of the driving circuitry layer away from the base substrate... The shielding layer is insulated from the detection electrode, and an orthogonal projection of the shielding layer onto the base substrate at least partially overlaps an orthogonal projection of the detection electrode onto the base substrate
Implementation Method 2
The shielding layer is coupled to a grounded line... effectively increases the signal-to-noise ratio, improves fingerprint collection accuracy, and enhances the reliability of fingerprint identification by inhibiting charging and discharging of parasitic capacitors
Data Source
AI summary
The present disclosure provides a fingerprint identification substrate, an electronic apparatus and a fingerprint identification method. The fingerprint identification substrate includes a base substrate, a driving circuitry layer arranged on the base substrate, a shielding layer arranged at a side of the driving circuitry layer away from the base substrate and a detection electrode arranged at a side of the shielding layer away from the base substrate. The detection electrode is electrically coupled to a fingerprint detection circuitry arranged on the driving circuitry layer, the shielding layer is insulated from the detection electrode, and an orthogonal projection of the shielding layer onto the base substrate at least partially overlaps an orthogonal projection of the detection electrode onto the base substrate.