In-Cell Fingerprint Sensor Circuit for Strong Light Recognition
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In-cell fingerprint recognition technology faces challenges in distinguishing between finger valley and ridge signals under strong light conditions due to high transmittance, leading to sensor failure.
Innovation Solution
A display panel with a fingerprint recognition circuit that includes a photosensitive circuit, storage circuit, and output circuit, featuring capacitors with electrodes arranged in specific layers and configurations to enhance charge storage capacity and signal differentiation, thereby improving anti-strong light performance and signal-to-noise ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the display panel uses high transmittance OLED technology for in-cell fingerprint recognition, then the display quality and lightness are improved, but the sensor cannot distinguish between finger valley and ridge signals under strong light conditions
Solution Approach 1:
The patent introduces a temporal dimension by implementing dual-mode operation (photoelectric conversion mode and charge storage mode) for the fingerprint sensor. The sensor can switch between real-time signal detection and integrated charge accumulation, allowing it to overcome the limitation of strong light interference by accumulating charges over time rather than relying solely on instantaneous signal differentiation.
Solution Approach 2:
The patent changes the operational parameters of the fingerprint sensor by introducing adjustable integration time and switching between different circuit modes. The control circuit can adjust the charge integration duration and switch between photoelectric conversion and charge storage operations, enabling the sensor to adapt to different lighting conditions and maintain measurement precision under strong light.
2Device complexity
If a simple photosensitive circuit is used for fingerprint recognition, then the device complexity is reduced, but the signal-to-noise ratio deteriorates under strong light conditions
Solution Approach 1:
The patent designs a multi-functional circuit that serves both fingerprint sensing and display functions within the same pixel structure. The OLED pixel can operate in different modes (display mode and fingerprint sensing mode), and the circuit can switch between photoelectric conversion and charge storage operations, achieving multiple functions without proportionally increasing device complexity.
Solution Approach 2:
The patent implements preliminary charge accumulation in the storage circuit before signal readout. By pre-integrating the photoelectric charges during a controlled integration period and isolating them in the storage circuit, the system prepares the signal in advance, separating the charge accumulation phase from the readout phase, thereby improving signal-to-noise ratio without requiring complex real-time processing circuits.
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 effectively improves the ability to recognize fingerprints under strong light conditions by increasing the storage capacity of the PIN photodiode and enhancing the signal-to-noise ratio, preventing sensor saturation and ensuring accurate fingerprint recognition.
Implementation Method 1
the photosensitive circuit is configured to convert a received optical signal into an electrical signal
Data Source
AI summary
A display panel is provided, including: a base substrate; a pixel circuit on the base substrate, the pixel circuit includes a transistor including an active layer, a gate electrode, a first electrode and a second electrode; and a fingerprint recognition circuit including a photosensitive circuit, a storage circuit and an output circuit, the storage circuit includes a first capacitor including a first capacitance electrode and a second capacitance electrode; the first capacitance electrode is arranged in the same layer as at least one of the gate electrode, the active layer, the first capacitor or the second electrode, and/or, the second capacitance electrode is arranged in the same layer as at least one of the gate electrode, the active layer, the first electrode or the second electrode; the first capacitance electrode is located in a layer different from a layer where the second capacitance electrode is located.