Fingerprint Sensing Module Damping Layer for Ultrasonic Resolution
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Solution Overview
Problem
Current ultrasonic fingerprint recognition technologies face challenges in distinguishing between ultrasonic echoes due to the superposition of signals, leading to difficulties in fingerprint analysis and identification, particularly due to the high number of reflected ultrasonic waves and small pulse intervals.
Innovation Solution
A fingerprint identification sensing module is introduced, featuring a damping layer that absorbs energy from the piezoelectric material layer, reducing the number of pulse wave cycles and improving longitudinal resolution by minimizing signal interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ultrasonic pulse wave is used for fingerprint recognition, then fingerprint identification capability is achieved, but the number of reflected ultrasonic waves increases causing signal superposition and reducing longitudinal resolution
Solution Approach 1:
The patent extracts and removes the harmful reflected ultrasonic waves from the system by introducing a damping layer that selectively absorbs the circulating pulse waves while allowing the useful reflected signals from the fingerprint to pass through, thereby reducing signal superposition and improving longitudinal resolution
Solution Approach 2:
The damping layer acts as an intermediary component between the piezoelectric material layer and the fingerprint surface, mediating the ultrasonic wave propagation by absorbing excess reflected waves and preventing signal superposition, thus resolving the contradiction between achieving fingerprint identification and reducing pulse wave cycles
2Quantity of substance
If damping layer is added to absorb energy from piezoelectric material layer, then number of pulse wave cycles is reduced, but signal-to-noise ratio needs to be maintained
Solution Approach 1:
The damping layer is positioned specifically at locations where reflected ultrasonic waves are most problematic, creating local energy absorption zones that reduce overall pulse wave cycles without uniformly affecting the entire ultrasonic field and thus preserving signal-to-noise ratio
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 damping layer significantly reduces the energy absorption of the piezoelectric material, enhancing the signal-to-noise ratio and simplifying fingerprint analysis, thereby improving recognition speed and accuracy.
Implementation Method 1
a voltage is imposed on a piezoelectric thin film layer (or a piezoelectric material layer) to force the piezoelectric thin film layer to emit high-frequency vibration to generate an ultrasonic wave
Implementation Method 2
the ultrasonic wave is reflected by a user's finger to the piezoelectric thin film layer and converted into an electrical signal for identification by the piezoelectric thin film layer
Implementation Method 3
a damping layer is arranged. The damping layer absorbs energy from the piezoelectric material layer, thereby reducing the number of cycles of the pulse wave
Data Source
AI summary
A fingerprint identification sensing module includes a first electrode and a second electrode, a piezoelectric material layer interposed between the first electrode and the second electrode, and a damping layer, arranged on a surface of the first electrode. The first electrode and the second electrode are arranged opposite.