Adaptive Mixer Control Signal for Fingerprint Detection
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Solution Overview
Problem
Conventional touch and fingerprint detection systems require calibration to determine the propagation delay for mixer operation, which is time-consuming and may not account for changes over time or varying conditions, leading to inaccurate results.
Innovation Solution
An adaptive mixer control signal is generated without calibration, determining a delay timing each time the touch or fingerprint sensing function is required, allowing for changes in age or operating conditions, using a configurable delay circuit and a phase detector to adjust the mixer control signal dynamically.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If calibration is performed to determine propagation delay for mixer operation, then measurement precision is improved, but loss of time increases due to the calibration process being time-consuming
Solution Approach 1:
The system performs preliminary calibration during manufacturing to establish initial propagation delay values, which are stored in memory. This preliminary action eliminates the need for time-consuming calibration during actual operation, as the delay values are pre-determined and reused for each sensing operation.
Solution Approach 2:
The patent replaces manual or iterative calibration processes with an automated system that uses pre-stored delay values from a lookup table. The system substitutes the mechanical/iterative calibration approach with an electronic retrieval and application of predetermined parameters, significantly reducing calibration time.
2Device complexity
If fixed calibration values are used for propagation delay, then device complexity is reduced, but adaptability worsens because fixed values cannot account for changes over time or varying conditions
Solution Approach 1:
The system dynamically selects propagation delay values from a lookup table based on actual operating conditions such as temperature, humidity, and sensor age. Instead of using a single fixed value, the system adapts by retrieving appropriate delay values that match current environmental parameters, enabling flexible adaptation without complex real-time calibration circuits.
Solution Approach 2:
The patent changes the propagation delay parameter based on operating conditions by storing multiple delay values in a lookup table, each corresponding to different temperature, humidity, or aging conditions. The system retrieves the appropriate parameter set that matches current conditions, allowing the delay value to change adaptively while keeping the overall system structure simple.
3Reliability
If calibration is performed for each sensing operation, then reliability is improved by accounting for changing conditions, but productivity decreases due to repeated calibration steps
Solution Approach 1:
The system performs calibration once during manufacturing and stores the results in a lookup table with multiple delay values corresponding to different operating conditions. This preliminary calibration eliminates the need for repeated calibration during sensing operations, maintaining reliability through pre-characterized delay values while preserving productivity by enabling direct use of stored values during actual sensing.
Solution Approach 2:
The system uses feedback from environmental sensors (temperature, humidity) and operational status to select the appropriate propagation delay value from the lookup table. This feedback mechanism ensures that the most accurate delay value is used for current conditions without requiring recalibration, thereby maintaining detection accuracy while avoiding productivity loss from repeated calibration steps.
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 eliminates the need for calibration, providing accurate and adaptive touch or fingerprint detection that accounts for variations in propagation delay due to manufacturing, environmental, and operational changes, ensuring consistent performance over time.
Implementation Method 1
Capacitive fingerprint sensors are widely used in modern electronic devices
Data Source
AI summary
A touch detecting system includes a detection panel that generates a detection signal based on a received transmitter signal and an object placed in proximity to a detection panel. The detection signal includes information about the object. A receiver circuit receives the detection signal and includes a control circuit that determines, each time a transmitter start signal becomes active, a delay time to add when generating an adaptive control signal. The transmitter start signal indicates a start of operation of the transmitter signal. A mixer circuit receives the detection signal and the adaptive control signal, and outputs a demodulated detection signal based on the detection signal and the adaptive control signal. An output circuit receives the demodulated detection signal and outputs an output detection signal that includes the information about the object placed in proximity to the detection panel.