Adaptive Fingerprint Sensor Power Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current fingerprint sensing systems face challenges in acquiring high-quality images from 'difficult' fingers, such as dry fingers, while maintaining low energy consumption and avoiding the need for separately gating pixel sensing cells, which increases time and energy efficiency.
Innovation Solution
A fingerprint sensing system with a thicker dielectric structure and read-out circuitry that includes charge amplifiers and sampling circuitry to sense changes in potential difference between the finger and sensing structures, allowing increased potential difference only when necessary, thereby maintaining low energy consumption and quick image acquisition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the reference potential of the sensor array is allowed to swing in relation to a device reference potential to improve sensing for difficult fingers, then fingerprint sensing performance is improved, but energy consumption increases
Solution Approach 1:
The patent implements dynamic reference potential adjustment where the reference potential swings only when necessary to capture fingerprint patterns from difficult fingers. The system transitions between a first operational mode with stable reference potential (low power) and a second operational mode with swinging reference potential (high performance), allowing adaptive optimization of both power consumption and sensing performance based on actual sensing needs.
Solution Approach 2:
The patent changes the reference potential parameter dynamically between two operational modes. In the first mode, the reference potential remains stable at a first level for low power consumption. In the second mode, the reference potential swings between different levels to enhance sensing capability for difficult fingers. This parameter change allows the system to adapt to different sensing requirements while optimizing energy usage.
2Use of energy by moving object
If pixel sensing cells are gated separately to reduce power consumption, then energy consumption is reduced, but image acquisition time increases
Solution Approach 1:
The patent employs periodic action by enabling multiple pixel sensing cells simultaneously in the second operational mode when high-performance fingerprint sensing is required. This periodic switching between selective gating (power-saving) and simultaneous activation (speed-optimizing) allows the system to balance power consumption and image acquisition speed based on the specific sensing situation.
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 system achieves improved fingerprint sensing performance with reduced energy consumption and faster image acquisition by dynamically controlling the potential difference between the finger and sensing structures, enhancing results for challenging fingers without increasing overall power usage.
Implementation Method 1
All capacitive fingerprint sensors provide a measure indicative of the capacitance between several sensing structures and a finger placed on or moved across the surface of the fingerprint sensor.
Implementation Method 2
a driving signal is injected into the finger by pulsing a conductive structure arranged in the vicinity of the sensor array and measuring the resulting change of the charge carried by the sensing structures in the sensor array
Data Source
Figure 1~2a
Figure 2b
Figure 3
AI summary
A fingerprint sensing system comprising a device connection interface, and a sensing arrangement including sensing structures, a read-out circuitry connected the sensing structures, and a sensing arrangement controller for controlling the sensing arrangement between at least a first sensing arrangement operational mode and a second sensing arrangement operational mode. The system further comprising supply circuitry connected to the sensing arrangement, and comprising a supply circuitry controller for controlling the supply circuitry between a first supply circuitry operational mode and a second supply circuitry operational mode in which modes different supply power is provided to the sensing arrangement. The supply circuitry controller transitions the supply circuitry between its modes in response to a power state signal indicative of a future transition of the sensing arrangement from the first operational mode to the second operational mode.