Ridge Recognition Substrate With Dummy Devices for Noise Calibration
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Solution Overview
Problem
Fingerprint imaging quality is compromised by transverse noise and illumination noise from frequent transistor switching and light reflection in existing fingerprint recognition technologies.
Innovation Solution
A fingerprint recognition substrate is designed with a photosensitive region and a light-shielding region, incorporating photo sensors and dummy devices that act as capacitors without photoelectric conversion, using an equivalent dielectric layer to calibrate output currents and filter noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If photo sensors are arranged in an array at the photosensitive region, then fingerprint detection capability is improved, but transverse noise and illumination noise from transistor switching compromise imaging quality
Solution Approach 1:
The substrate is divided into a photosensitive region containing photo sensors and a light-shielding region containing dummy devices. This segmentation isolates the noise-generating transistors in the light-shielding region from the photo sensors in the photosensitive region, preventing transverse noise and illumination noise from compromising fingerprint detection capability.
Solution Approach 2:
Dummy devices are introduced as intermediary elements in the light-shielding region. These dummy devices contain transistors that generate noise similar to the photo sensor transistors, allowing for noise calibration and compensation without directly interfering with the photo sensors' fingerprint detection function.
2Measurement precision
If dummy devices are added to the light-shielding region, then noise calibration capability is improved, but device structure complexity increases
Solution Approach 1:
The dummy devices in the light-shielding region are designed with the same transistor structure as the photo sensors, allowing them to serve multiple functions: generating comparable transverse noise for calibration purposes, occupying space to maintain array uniformity, and potentially serving as additional sensing elements if needed. This multi-functionality reduces the need for separate calibration components.
3Object-generated harmful factors
If light-shielding region is introduced, then illumination noise is reduced, but photosensitive region area is reduced
Solution Approach 1:
The substrate is designed with spatially varying properties: the photosensitive region has high light sensitivity for fingerprint detection, while the light-shielding region has low light sensitivity to prevent illumination noise. This local differentiation allows each region to optimize its function - the photosensitive region maximizes detection area while the light-shielding region minimizes noise generation from external light sources.
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
Improves fingerprint imaging quality by removing dark noise and illumination noise, ensuring accurate reflection of image fluctuations and enhancing overall image quality.
Implementation Method 1
each photo sensor including a first electrode, a photoelectric conversion structure, and a second electrode arranged in layers; the photoelectric conversion structure is electrically connected with the first electrode, and the photoelectric conversion structure directly contacts with the second electrode
Data Source
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AI summary
Provided in the present disclosure are a ridge recognition substrate and a ridge recognition apparatus. The ridge recognition substrate comprises: a base substrate, which comprises a photosensitive area and a light-shielding area, which is located on at least one side of the photosensitive area; a plurality of photosensitive devices, which are arranged in the photosensitive area in an array, wherein the photosensitive devices each comprise a first electrode, a photoelectric conversion structure and a second electrode, which are arranged in a stacked manner, the photoelectric conversion structure being electrically connected to the first electrode, and the photoelectric conversion structure being in direct contact with the second electrode; and a plurality of virtual devices, which are arranged in the light-shielding area in an array, wherein the virtual devices each comprise a third electrode, an equivalent dielectric layer and a fourth electrode, the third electrode and the first electrode being in the same layer, the fourth electrode being located on the side of the layer, where the second electrode is located, that faces away from the base substrate, and the equivalent dielectric layer being located between the layer where the third electrode is located and the layer where the fourth electrode is located; and the virtual devices are configured to not perform photoelectric conversion.