Fingerprint Pixel Module Resistor Layout for ESD Protection
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Solution Overview
Problem
Fingerprint identification systems face damage from electrostatic currents due to accumulated charges at the top-layer electrode, which cannot be mitigated by existing pixel modules lacking an electrostatic protection circuit due to area constraints.
Innovation Solution
Incorporating a resistor between the top-layer electrode and the pixel circuit, formed from a polycrystalline silicon layer, to suppress electrostatic current and provide protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the top-layer electrode is exposed outside the integrated circuit to receive finger contact, then the fingerprint identification function is enabled, but electrostatic charges accumulate in the vicinity of the top-layer electrode causing electrostatic current damage to the pixel circuit
Solution Approach 1:
The patent introduces an electrostatic protection circuit as an intermediary component between the top-layer electrode and the pixel circuit. This protection circuit includes a first switching element connected between the top-layer electrode and the pixel circuit, which acts as a mediator to prevent direct harmful electrostatic current from reaching the pixel circuit while still allowing the top-layer electrode to receive finger contact for fingerprint identification.
2Area of stationary object
If the pixel circuit area is kept small to meet the constraint of being less than or equal to the top-layer electrode area, then the pixel module design is compact, but no additional electrostatic protection circuit can be accommodated
Solution Approach 1:
The patent merges the electrostatic protection function with the existing pixel circuit structure by integrating the protection circuit within the same pixel module footprint. The first switching element of the protection circuit is combined with the pixel circuit components, allowing both the compact pixel circuit and the electrostatic protection function to coexist within the area constraint of being less than or equal to the top-layer electrode area.
Solution Approach 2:
The patent implements multi-functionality by designing the pixel circuit to simultaneously perform fingerprint detection and electrostatic protection functions. The first switching element serves dual purposes: it is part of the pixel circuit for detecting capacitance changes during fingerprint identification, and it acts as the electrostatic protection element to block harmful electrostatic currents. This universal design allows the pixel module to achieve both compact area and reliable electrostatic protection.
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 resistor effectively suppresses electrostatic current, protecting the pixel circuit and enhancing the electrostatic protection function of the pixel module, enabling safer operation of fingerprint identification systems.
Implementation Method 1
a resistor, coupled between the top-layer electrode and the pixel circuit... the resistor is configured to suppress a current between the top-layer electrode and the pixel circuit
Implementation Method 2
a contact capacitance being formed between the top-layer electrode and the finger; a pixel circuit, used for detecting a capacitance value of the contact capacitance
Data Source
AI summary
A pixel module and a fingerprint identification system are provided. The pixel module includes: a top-layer electrode, configured to receive a contact of a finger, a contact capacitance being formed between the top-layer electrode and the finger; a pixel circuit, configured to detect a capacitance value of the contact capacitance; and a resistor, coupled between the top-layer electrode and the pixel circuit. The pixel module suppresses the electrostatic current formed by the electrostatic charges, thereby achieving the effect of electrostatic protection.