Optical Biometric Sensor Adaptive Readout Timing
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Solution Overview
Problem
Biometric sensors, particularly optical fingerprint sensors, face challenges in optimizing data transfer between the sensor and a host device due to limited data bus capacity, leading to sub-optimal utilization and potential need for costly buffer solutions.
Innovation Solution
An optical biometric sensor with timing circuitry that controls the exposure of photodetectors based on the current data transfer capacity of the bus, ensuring the data production rate matches the bus's capability, thereby allowing immediate data transfer without unnecessary delays or intermediate storage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the biometric sensor continuously produces data at maximum rate, then the data production efficiency is improved, but the data transfer bus cannot handle the data flow causing sub-optimal utilization and potential data loss
Solution Approach 1:
The patent implements dynamic control of the exposure timing circuitry to adjust the data production rate in real-time based on the current data transfer capacity of the bus. The circuitry monitors bus availability and dynamically modifies when photodetector subsets start exposure, ensuring data production matches transfer capability without requiring costly buffer solutions.
Solution Approach 2:
The system employs feedback mechanisms where the timing circuitry receives information about the present data transfer capacity on the bus and uses this feedback to control the start of exposure timing. This closed-loop control ensures that data production is automatically adjusted to match transfer capacity, preventing data overflow and ensuring reliable transfer.
2Quantity of substance
If the data production rate exceeds the bus transfer capacity, then more data can be captured, but costly buffer solutions are required to store intermediate data
Solution Approach 1:
The timing circuitry performs preliminary action by controlling the start of exposure timing in advance to ensure data is ready for transfer exactly when the bus becomes available. This proactive timing control eliminates the need for buffer memory by ensuring data production is synchronized with transfer capacity from the outset.
Solution Approach 2:
The system achieves self-service by having the timing circuitry automatically adjust exposure timing based on real-time bus capacity monitoring. The biometric sensor autonomously regulates its own data production rate to match transfer capability, eliminating the need for external buffer memory or complex data management infrastructure.
3Ease of operation
If the host device controls the data readout timing, then the host has full control over data processing, but the biometric sensor cannot optimize data production to match bus capacity
Solution Approach 1:
The timing circuitry is designed with multi-functionality, serving both the host device's control requirements and the sensor's optimization needs. It responds to host control signals while simultaneously monitoring bus capacity and adjusting exposure timing to optimize data production, making the system adaptable to both control paradigms.
Solution Approach 2:
The system implements dynamic control where the timing circuitry can operate in different modes based on host requirements. It maintains responsiveness to host control commands while dynamically adjusting exposure timing to optimize data production efficiency, allowing the system to adapt its behavior based on operational context.
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 optimizes data transfer between the biometric sensor and host device, even with asynchronous clocks, by synchronizing data production with the bus's capacity, reducing the need for buffers and ensuring efficient data handling.
Implementation Method 1
an image sensor comprising an array of photodetectors, wherein for acquiring sensing signals, the image sensor is controllable to sequentially start exposure of subsets of photodetectors
Data Source
Figure 1~2
Figure 3
Figure 4A~4B
AI summary
The present invention relates to an optical biometric sensor (100) comprising: an image sensor (302) comprising an array (301) of photodetectors (304), wherein for acquiring sensing signals, the image sensor is controllable to sequentially start exposure of subsets (306, 308, 309) of photodetectors; and a timing circuitry (310) configured to control the start of exposure of a subset of photodetectors based on a present data transfer capacity on a data transfer bus (312) configured to transfer data indicative of the acquired sensing signals from the optical biometric sensor to a host device (314).