Fingerprint Sensor Micro-Lens Distance Optimization
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Solution Overview
Problem
Fingerprint recognition devices face issues of non-uniform brightness and crosstalk due to improper distance between the self-illuminating light emitting panel and the micro-lens layer, which affects the light receiving angle of each micro lens.
Innovation Solution
A fingerprint recognition device is designed with a micro-lens layer positioned between the light emitting layer and the image sensing layer, where the distance between the micro-lens layer and the light emitting layer is set to be less than or equal to 800 um and greater than or equal to h1, where h1=x/(2×tan θ), ensuring optimal light receiving angles for each micro lens and preventing non-uniform brightness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the distance between the self-illuminating light emitting panel and the micro-lens layer is reduced to prevent crosstalk, then the light receiving angle of each micro lens is optimized, but non-uniform brightness occurs
Solution Approach 1:
The patent applies parameter changes by establishing a specific distance range (h1 to 800 μm) between the light emitting layer and micro-lens layer, where h1 = x/(2×tanθ). This parameter optimization resolves the contradiction by finding the optimal distance that simultaneously prevents crosstalk and maintains uniform brightness across all pixels.
2Measurement precision
If the light receiving angle of each micro lens is optimized to prevent crosstalk, then signal accuracy is improved, but the sensor becomes sensitive to distance variations causing non-uniform brightness
Solution Approach 1:
The patent applies preliminary action by pre-calculating and setting the optimal distance range (h1 to 800 μm) before manufacturing. This preliminary determination of the distance parameter eliminates the need for complex post-manufacturing adjustments and reduces sensitivity to manufacturing variations.
3Reliability
If a constant light receiving angle is maintained for each micro lens, then crosstalk is prevented, but the distance between the light emitting panel and micro-lens layer must be precisely controlled
Solution Approach 1:
The patent resolves this contradiction by changing the approach from controlling the light receiving angle directly to controlling the distance parameter. By setting the distance between h1 and 800 μm, the system maintains constant light receiving angles for all micro lenses while simplifying the control mechanism to a single distance parameter rather than requiring complex angular control systems.
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 configuration effectively prevents non-uniform brightness and crosstalk by ensuring the correct distance between the micro-lens layer and the light emitting layer, optimizing the light receiving angle for each micro lens.
Implementation Method 1
The micro-lens layer is disposed between the light emitting layer and the image sensing layer and has a plurality of micro lenses respectively corresponding to the pixels
Implementation Method 2
Fingerprint signals detected by an in-display fingerprint recognition sensor are transmitted downward through a transparent region of a self-illuminating light emitting panel
Data Source
AI summary
A fingerprint recognition device including a light emitting layer, an image sensing layer and a micro-lens layer is provided. The image sensing layer has a plurality of pixels. The micro-lens layer is disposed between the light emitting layer and the image sensing layer and has a plurality of micro lenses respectively corresponding to the pixels. A distance between the micro-lens layer and the light emitting layer is less than or equal to 800 um and greater than or equal to h1, where h1=(x/2×tan θ), x is the minimum distance between two micro lenses respectively corresponding to different pixels on a plane where the micro-lens layer is disposed, and θ is an FWHM light receiving angle of each of the micro lenses.