Optical Fingerprint Substrate With Light-Absorbing Reflection Control
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Solution Overview
Problem
Optical fingerprint recognition systems face interference from unabsorbed light reflected by the finger, leading to reduced recognition accuracy when the I-type semiconductor layer is thinned, as it does not completely absorb fingerprint-reflected light, causing multiple reflections that interfere with the recognition process.
Innovation Solution
Incorporating a light-transmitting region in the first electrode and a light-absorbing layer between the base substrate and the photosensitive device to absorb unconverted fingerprint-reflected light, preventing multiple reflections and improving recognition accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the I-type semiconductor layer is thinned to reduce production time and cost, then manufacturing efficiency is improved, but fingerprint recognition accuracy deteriorates due to incomplete light absorption and multiple reflections
Solution Approach 1:
The light absorption function is segmented between the thinned I-type semiconductor layer and the light-absorbing layer. The semiconductor layer converts part of the fingerprint-reflected light to electrical signals, while the light-absorbing layer absorbs the remaining unconverted light, preventing multiple reflections. This segmentation allows the semiconductor layer to be thinned for faster production while maintaining recognition accuracy through the complementary light-absorbing layer.
Solution Approach 2:
The light-absorbing layer acts as an intermediary component between the thinned photoelectric conversion layer and the base substrate. It mediates the unconverted fingerprint-reflected light that passes through the thinned I-type semiconductor layer, absorbing this light to prevent it from reflecting back and interfering with the recognition process, thereby maintaining accuracy despite the reduced thickness of the semiconductor layer.
2Loss of substance
If the I-type semiconductor layer is thinned to reduce material usage and cost, then manufacturing cost is reduced, but light absorption completeness deteriorates causing recognition interference
Solution Approach 1:
The light handling function is divided into two segments: the thinned I-type semiconductor layer performs photoelectric conversion on part of the incident light, and the light-absorbing layer positioned below it absorbs the remaining unconverted light. This segmentation enables material reduction in the semiconductor layer while ensuring complete light management through the light-absorbing layer, preventing recognition interference.
Solution Approach 2:
The light-absorbing layer converts the potentially harmful effect of unabsorbed light (which would cause multiple reflections and interference) into a beneficial outcome by absorbing this light and preventing it from interfering with the recognition process. This transforms what would be a harmful reflection into a controlled absorption event, maintaining reliability despite reduced semiconductor layer thickness.
3Measurement precision
If the light-absorbing layer is added to prevent multiple reflections, then recognition accuracy is improved, but device complexity increases
Solution Approach 1:
The light-absorbing layer serves multiple functions: it absorbs unconverted fingerprint-reflected light to prevent multiple reflections, improves recognition accuracy, and can be integrated with existing device layers. By positioning it between the thinned photoelectric conversion layer and the base substrate, it provides a simple yet effective solution that addresses multiple concerns without significantly increasing overall device complexity.
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
The solution enhances fingerprint recognition accuracy by ensuring that unabsorbed light is absorbed, reducing interference and maintaining recognition performance comparable to systems with conventional I-type semiconductor layer thickness, while also shortening production time and reducing costs.
Implementation Method 1
the photoelectric conversion layer includes an I-type semiconductor layer with a thickness enough to convert a part of fingerprint-reflected light to an electrical signal
Implementation Method 2
a light-absorbing layer located between the base substrate and a layer where the photosensitive device is located to absorb the fingerprint-reflected light that is not converted by the photoelectric conversion layer
Data Source
AI summary
A pattern recognition substrate and a display device are disclosed, the pattern recognition substrate includes: a base substrate; a photosensitive device arranged on the base substrate and including a first electrode, a photoelectric conversion layer and a second electrode that are stacked, where the photoelectric conversion layer includes an I-type semiconductor layer with a thickness enough to convert a part of fingerprint-reflected light to an electrical signal, the first electrode includes a light-transmitting region transmitting the fingerprint-reflected light which is converted by the photoelectric conversion layer; and a light absorbing layer arranged between the base substrate and a layer where the photosensitive device is located to absorb the fingerprint-reflected light not converted by the photoelectric conversion layer.