Fingerprint Sensor Gate Driver for Selective Array Scanning
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Solution Overview
Problem
Conventional gate drivers for fingerprint sensors require scanning the entire sensing region, leading to increased scanning time, latency, and resource requirements, especially with larger sensing areas and dual-finger authentication, which negatively impacts user experience.
Innovation Solution
A gate driver configuration that includes a first and second flip-flop with a data input and output, coupled to respective groups of sensing pixels, and an insertion circuit to allow the second flip-flop to drive sensing pixels without the first, enabling selective scanning of portions of the array, reducing the need to drive all pixels simultaneously.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the gate driver sequentially drives all columns of sensing elements from first to last in a conventional SISO shift register configuration, then the entire sensing region is scanned, but the scanning time increases proportionally with the size of the sensing region
Solution Approach 1:
The gate driver is divided into multiple independent scan engines (first scan engine, second scan engine, etc.), each capable of driving a portion of the sensing columns. This segmentation allows parallel scanning of different column groups, reducing total scanning time from sequential to concurrent operation across multiple scan engines.
Solution Approach 2:
The patent implements dynamic scan region configuration where the controller can selectively enable or disable specific scan engines based on the detected touch location. This dynamic adjustment optimizes scanning by activating only the necessary portion of the sensing array, reducing scanning time while maintaining full scan coverage capability when needed.
2Adaptability or versatility
If the sensing region size is increased to cover larger display areas or enable dual-finger scanning, then the fingerprint sensor capability is improved, but the scanning time and processing resources increase
Solution Approach 1:
The system dynamically configures the active scan region based on touch detection. When a touch is detected at a specific location, the controller enables only the scan engines corresponding to that region, reducing scanning time. The system can adapt to different scenarios including single-finger and dual-finger authentication by selectively activating appropriate scan engines.
Solution Approach 2:
The sensing array is divided into multiple scan regions, each handled by a dedicated scan engine. This segmentation allows the system to process only the relevant portion of the sensing array based on touch location, maintaining full adaptability for different finger placements while reducing the actual scanning workload and time required.
3Reliability
If the entire array of sensing pixels is driven for scanning, then complete fingerprint capture is achieved, but resource requirements and latency increase
Solution Approach 1:
The controller dynamically determines which scan engines to activate based on touch location detection. This ensures that only the necessary portion of the sensing array is scanned, maintaining complete fingerprint capture for the detected region while reducing latency by avoiding unnecessary scanning of unused regions.
Solution Approach 2:
The system extracts and processes only the relevant portion of the sensing array corresponding to the detected touch region. By taking out only the necessary scan operations and excluding unnecessary ones, the system maintains fingerprint capture reliability while reducing processing time and resource consumption.
Data Source
AI summary
An example gate driver for an array of sensing pixels is disclosed. The gate driver includes a first flip-flop including a first data input and a first data output. The first data output is coupled to a first group of sensing pixels of the array. The gate driver also includes a second flip-flop including a second data input and a second data output. The second data output is coupled to a second group of sensing pixels of the array. The gate driver further includes a first insertion circuit configured to receive a first start signal and to cause, based on the first start signal, the second flip-flop to drive the second group of sensing pixels without the first flip-flop driving the first group of sensing pixels for a scan of the array.