Optical Fingerprint Sensor Calibration Using Display-Reflected Test Patterns
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Solution Overview
Problem
Current testing processes for optical fingerprint sensor devices require specialized tools and human interaction, introducing variability and inefficiency in calibrating configuration parameters, especially during production when a specifically-designed piece of ridged silicone is used to provide a test pattern.
Innovation Solution
The method involves displaying a test pattern on the device's display and reflecting it back towards the optical fingerprint sensor using a reflector, eliminating the need for a physically placed test object and minimizing human interaction, thereby facilitating efficient calibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a specifically-designed piece of ridged silicone is used to provide a test pattern, then the sensor can acquire test data, but human interaction is required and variability is introduced into test conditions
Solution Approach 1:
The patent uses a display screen to generate a digital copy of the test pattern (ridges and valleys) instead of requiring a physical silicone object. The display renders the test pattern visually, and the optical sensor captures it through the display, eliminating the need for physical contact and human placement while maintaining test accuracy
Solution Approach 2:
The system uses the device's own display and optical sensor to perform self-testing. The display generates the test pattern, and the optical sensor captures it, allowing the device to calibrate and test its own sensor without external tools or human intervention
2Measurement precision
If a specifically-designed piece of ridged silicone is used to provide a test pattern, then the sensor can acquire test data, but specialized tools are required
Solution Approach 1:
The display screen serves multiple functions: it displays user interface elements and simultaneously generates the test pattern for sensor calibration. The optical sensor also serves dual purposes by capturing both normal fingerprint data and test pattern data. This eliminates the need for specialized testing tools
Solution Approach 2:
Instead of requiring specialized physical test objects, the system uses a digital copy of the test pattern rendered on the display screen. This digital representation is sufficient for the optical sensor to capture and process, eliminating the need for specialized physical tools
3Ease of operation
If human interaction is used to place the test object, then the test pattern can be provided, but variability is introduced into test conditions
Solution Approach 1:
The device performs self-testing by using its own display to generate the test pattern and its optical sensor to capture it. This automated self-service process eliminates human variability and ensures consistent test conditions across all devices and testing instances
Solution Approach 2:
The test pattern is generated as a digital image on the display rather than being physically placed by hand. This digital generation ensures identical, repeatable patterns with consistent positioning and lighting conditions, eliminating the variability introduced by manual placement
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 allows for efficient and convenient testing of optical fingerprint sensors, reducing variability and the need for specialized tools, while ensuring accurate calibration of the sensor's configuration parameters.
Implementation Method 1
reflecting, by a reflector disposed over the display, at least a portion of the displayed test pattern
Data Source
AI summary
A method for testing a sensor of a device includes: displaying a test pattern on a display of the device; reflecting, by a reflector disposed over the display, at least a portion of the displayed test pattern; and capturing, by the sensor, a test pattern frame using the displayed test pattern and the reflector.