Optimized Scan Sequence for Biometric Sensor Latency
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Solution Overview
Problem
Conventional optical fingerprint sensors experience latency due to the need to capture baseline images and reset sensor circuitry, leading to longer processing times and potential blurry images from unstable fingers.
Innovation Solution
An optimized scan sequence where a first image is captured with the light source on and then transmitted for matching, followed by a second image captured with the light source off, allowing for parallel processing and reducing the need for a baseline subtraction in most environments, thus improving latency and image stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional optical sensors capture baseline images and reset sensor circuitry before imaging, then measurement precision is improved, but loss of time increases due to longer processing latency
Solution Approach 1:
The patent performs preliminary actions (capturing ambient light baseline and resetting sensor circuitry) in advance before the actual fingerprint imaging. This ensures measurement precision is maintained while the preliminary actions are completed beforehand, reducing the perceived processing latency during the critical imaging moment.
Solution Approach 2:
The patent implements periodic ambient light sampling and sensor reset cycles that occur at regular intervals independent of the fingerprint imaging trigger. This periodic operation separates the precision-critical baseline establishment from the time-critical fingerprint capture, allowing parallel processing that reduces overall latency.
2Adaptability or versatility
If optical sensors capture images in varying lighting environments, then adaptability is improved, but measurement precision deteriorates due to lack of consistent baseline
Solution Approach 1:
The patent continuously monitors ambient light conditions and uses this feedback to dynamically adjust the baseline subtraction process. The system captures ambient light images at regular intervals and uses this real-time feedback to compensate for lighting changes during fingerprint imaging, maintaining measurement precision across varying lighting environments.
Solution Approach 2:
The patent changes the temporal parameter of baseline capture by continuously or periodically sampling ambient light conditions rather than using a single static baseline. This allows the system to adapt to lighting changes by selecting or interpolating appropriate baseline values based on the actual lighting conditions at the time of fingerprint capture.
3Measurement precision
If optical sensors wait for finger settlement before imaging, then measurement precision is improved, but loss of time increases due to extended waiting period
Solution Approach 1:
The patent performs preliminary finger presence detection and settlement monitoring before initiating the actual fingerprint imaging sequence. By detecting finger placement early and monitoring settlement in advance, the system can trigger the imaging process at the optimal moment when the finger is settled, reducing the perceived waiting time while maintaining image stability.
Solution Approach 2:
The patent implements periodic checking of finger settlement status during the pre-imaging phase. Instead of continuous monitoring that would increase latency, the system checks at regular intervals and triggers imaging when settlement criteria are met, balancing the need for stable images with minimizing waiting time.
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 approach reduces latency by eliminating the need for additional image captures when a match is found with the first image, enhancing the reliability and speed of fingerprint verification.
Implementation Method 1
light emanating from the light source is reflected from the input object
Implementation Method 2
some light reflected from the input object is blocked by a collimator filter layer while other light reflected from the input object passes through apertures in the collimator filter layer
Data Source
AI summary
Disclosed are systems and method for imaging an input object. An imaging device includes: a light source that emanates light to a sensing region in which the input object to be imaged is placed; a collimator filter layer; an image sensor array disposed below the collimator filter layer that blocks some light reflected from the input object while other light passes through apertures in the collimator filter layer and arrives at the image sensor array; and a controller configured to cause a first image of the input object to be captured with the light source turned on, and to transmit the first image to a processor associated with the electronic device to perform image matching against one or more template images before causing a second image of the input object to be captured with the light source turned off.