Pixel Photosensor Readout Circuit for Higher Light Detection Sensitivity
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Solution Overview
Problem
Conventional display devices with photosensors in pixel regions face challenges in achieving high sensitivity due to equal potential differences at storage nodes under different illuminance conditions, limiting the signal-to-noise ratio and photosensor performance.
Innovation Solution
Incorporating an amplification element that amplifies the potential of the storage node using a readout signal, enhancing the potential difference between dark and saturation light conditions, thereby increasing sensitivity and signal-to-noise ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If photodiodes are formed on the active matrix substrate using a semiconductor process, then the photosensor can detect light and pick up images, but the potential difference at the storage node remains equal under different illuminance conditions, limiting sensitivity
Solution Approach 1:
The patent applies preliminary action by resetting the storage node potential to a reference level before light detection begins. This reset operation prepares the system in advance by clearing any residual charge, ensuring that the subsequent potential changes during the integration period accurately reflect only the incident light intensity, thereby improving measurement precision and signal-to-noise ratio
2Device complexity
If the storage node potential is directly read out without amplification, then the circuit structure remains simple, but the potential difference between dark and saturation light conditions is insufficient, reducing photosensor performance
Solution Approach 1:
The patent introduces a readout circuit as an intermediary component between the storage node and the output. This readout circuit includes amplification elements that boost the small potential differences generated during light detection, making the signal strong enough for accurate measurement while maintaining a relatively simple overall circuit architecture
Solution Approach 2:
The patent applies parameter changes by transforming the small potential difference parameter into a larger voltage signal through amplification. The readout circuit modifies the electrical parameters of the signal, converting微弱 potential changes into pronounced voltage variations that can be easily detected and processed, thereby improving measurement precision without significantly complicating the device
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 amplification element significantly increases the potential difference at the storage node after readout, resulting in a highly sensitive photosensor with improved signal-to-noise ratio across varying illuminance levels.
Implementation Method 1
a photodetection element that receives incident light
Data Source
AI summary
The present invention relates to a display device including a photosensor in a pixel region. The photosensor of the present invention includes a diode (D1) that receives incident light, reset signal wiring (RST) that supplies a reset signal, readout signal wiring (RWS) that supplies a readout signal, a storage node (INT) whose potential changes in accordance with the amount of light received by the photodetection element in a sensing period, the sensing period being from when the reset signal is supplied until when the readout signal is supplied, an amplification element (C1) that amplifies the potential of the storage node in accordance with the readout signal, and a sensor switching element (M2) for reading out the potential amplified by the amplification element to output wiring (OUT) as sensor circuit output.