Optical Filter for Narrow Fingerprint Sensing Region
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Solution Overview
Problem
Current display devices face challenges in accurately narrowing the fingerprint sensing region for improved fingerprint recognition, as existing technologies struggle to maintain high accuracy while minimizing the area of the fingerprint sensing region without reducing the aperture ratio of the light sensing unit.
Innovation Solution
A display device design incorporating a light blocking layer with an optical filter having a multilayer structure of low and high refractive layers, which alternately disposed on each other, and a color filter to enhance the interference effect, thereby increasing the ratio of incident light contributing to the sensing signal and reducing the fingerprint sensing region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the fingerprint sensing region is narrowed by reducing the opening area of the light blocking layer, then the accuracy of fingerprint recognition is improved, but the aperture ratio of the light sensing unit is reduced
Solution Approach 1:
The patent applies local quality by introducing an optical filter with specific optical properties (refractive index, light transmission characteristics) at the precise location of the light blocking layer opening. This allows the fingerprint sensing region to be narrowed optically while the physical opening area remains unchanged, thus improving recognition accuracy without reducing the aperture ratio. The optical filter creates a localized optical effect that confines the sensing region without physically constraining the light path.
Solution Approach 2:
The patent utilizes parameter changes by modifying the optical parameters (refractive index, light transmission wavelength, reflection characteristics) of the optical filter to control the behavior of incident light. By carefully selecting and tuning these optical parameters, the system achieves effective narrowing of the fingerprint sensing region through optical confinement while maintaining the physical aperture dimensions, thereby resolving the contradiction between sensing region size and aperture ratio.
2Measurement precision
If the opening area of the light blocking layer is reduced to narrow the fingerprint sensing region, then the sensing accuracy is improved, but the amount of incident light is reduced
Solution Approach 1:
The optical filter introduces local quality by creating a region with distinct optical properties that selectively guides and concentrates incident light onto the photoelectric conversion element. This localized optical manipulation ensures that sufficient light energy is delivered to the sensing region while maintaining narrow sensing boundaries, thus improving sensing accuracy without sacrificing incident light quantity.
Solution Approach 2:
The patent employs parameter changes by optimizing the optical filter's transmission characteristics, refractive index, and thickness to maximize light transmission efficiency. These parameter adjustments ensure that the optical filter confines the sensing region while simultaneously maintaining high light transmission, thereby resolving the contradiction between sensing accuracy and incident light amount.
3Measurement precision
If the optical filter is added to control light transmission and narrow the sensing region, then the fingerprint recognition accuracy is improved, but the device complexity is increased
Solution Approach 1:
The optical filter serves multiple functions simultaneously: it narrows the fingerprint sensing region, controls light transmission, and can be integrated with existing display structure layers. This multi-functionality reduces the need for additional separate components, thereby improving recognition accuracy while minimizing the increase in device complexity.
Solution Approach 2:
The optical filter is nested within the existing display device structure, integrated with the light blocking layer and other functional layers. This nesting approach allows the optical filter to be incorporated into the existing device architecture without requiring separate housing or additional external components, thus improving sensing accuracy while keeping the overall device complexity manageable.
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 design effectively narrows the fingerprint sensing region without reducing the aperture ratio, enhancing the accuracy of fingerprint recognition by optimizing the transmission and reflection of light wavelengths, specifically increasing the ratio of the sensing signal and reducing noise signals.
Implementation Method 1
an optical filter overlapping the photoelectric conversion element in a thickness direction of the substrate and having a multilayer film
Implementation Method 2
the optical filter includes a low refractive layer and a high refractive layer having a higher refractive index than that of the low refractive layer
Implementation Method 3
a photoelectric conversion element disposed on the substrate and configured to sense incident light
Data Source
AI summary
A display device includes: a substrate; a light emitting element disposed on the substrate and configured to emit light; a photoelectric conversion element disposed on the substrate and configured to sense incident light; a light blocking layer disposed on the photoelectric conversion element and having an opening; and an optical filter disposed in the opening of the light blocking layer to transmit incident light.