Display Panel Light Sensor Circuit for Fingerprint Signal Integrity
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Solution Overview
Problem
Existing display devices with integrated light sensors face challenges in achieving optimal performance for fingerprint sensing due to inefficiencies in signal generation and transmission by transistors, particularly in managing leakage currents and signal magnitude variations.
Innovation Solution
Incorporation of p-channel metal oxide semiconductor (PMOS) transistors in the sensing circuitry, including a first and second sensing transistor with back gate electrodes, and a light-receiving element connected to a control node, along with a display panel driver to manage sensing signals effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a light sensor is added to the display device for fingerprint sensing, then user authentication capability is improved, but device complexity increases
Solution Approach 1:
The patent combines the light sensor functionality with the display device structure by integrating the sensing transistor, light-receiving element, and back gate electrode directly into the display panel architecture. This merging approach allows fingerprint authentication to be performed using the display device itself without adding separate authentication hardware, thus improving versatility while controlling complexity.
Solution Approach 2:
The display device is designed to serve multiple functions: displaying visual information and performing fingerprint authentication. The light sensor components (sensing transistor, light-receiving element, back gate electrode) enable the display device to function as both a display and a biometric authentication device, achieving multi-functionality that improves adaptability.
2Measurement precision
If the light sensor uses a back gate electrode with sensing gate signal to enhance signal-to-noise ratio, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The back gate electrode is specifically positioned at the light sensor region rather than across the entire display. The sensing gate signal is applied locally to the back gate electrode of the sensing transistor, creating a localized electric field that enhances the signal-to-noise ratio for light detection. This local quality approach improves measurement precision without requiring modifications across the entire display structure.
Solution Approach 2:
The back gate electrode introduces an additional control dimension to the sensing transistor operation. By applying the sensing gate signal to the back gate, the patent creates a second gate control mechanism that independently modulates the transistor's electrical characteristics, thereby enhancing the light sensing capability and signal-to-noise ratio through this additional dimensional control.
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
Enhances the accuracy and reliability of fingerprint sensing by reducing leakage currents and increasing signal magnitude, thereby improving user authentication capabilities.
Implementation Method 1
a light-receiving element connected to a control node of the first sensing transistor
Data Source
AI summary
Provided herein may be a display device including a display panel including a sub-pixel, and a light sensor configured to generate a sensing signal corresponding to a quantity of received light, and including a first sensing transistor configured to generate the sensing signal, and including a back gate electrode configured to receive a sensing gate signal, a second sensing transistor configured to provide the sensing signal to a readout line in response to the sensing gate signal, and a light-receiving element connected to a control node of the first sensing transistor, and a display panel driver configured to drive the display panel.