Pixel Circuit With In-Cell Light Sensing for Biomarker Accuracy
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Solution Overview
Problem
Electronic devices with separate bio-sensing operations reduce the display region size and increase the bezel size, and in-cell light sensor techniques face challenges in improving biomarker accuracy.
Innovation Solution
A pixel circuit with a light emitter and light sensor, including transistors and photodiodes, adjusts the photodiode voltage based on sensing current to enhance biomarker accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate bio-sensing sensor is used, then bio-sensing operations can be performed, but the display region size is reduced and the bezel size is increased
Solution Approach 1:
The patent combines the light sensor function with the display pixel structure by integrating a photodiode and sensing transistor within the pixel circuit. This merging allows the display device to perform bio-sensing operations (such as PPG) without requiring a separate dedicated sensor, thereby maintaining full display region area while enabling accurate biomarker detection through the integrated light-sensing capability
2Area of stationary object
If in-cell light sensor technique is used to maintain display region size, then display area is preserved, but biomarker accuracy is insufficient
Solution Approach 1:
The patent implements dynamic adjustment of the photodiode voltage through a control transistor that receives feedback from the sensing current. The voltage is adjusted based on the detected light intensity variations, allowing the system to adapt to different environmental conditions and maintain high biomarker accuracy. This dynamic voltage control compensates for threshold voltage variations and environmental factors that would otherwise degrade measurement precision
Solution Approach 2:
The patent changes the operating voltage parameter of the photodiode to optimize sensing performance. By adjusting the photodiode voltage dynamically based on sensing conditions, the system maintains high measurement precision for biomarker detection while operating within the integrated pixel structure, thereby resolving the accuracy limitation of conventional in-cell sensing
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 adjusted photodiode voltage compensates for environmental changes, improving the accuracy of biomarker sensing by maintaining an initial sensing current range.
Implementation Method 1
a light sensor configured to sense the light of the light emitter, and including a photodiode
Implementation Method 2
a light-emitting element configured to emit light based on the driving current
Data Source
AI summary
A pixel circuit includes a light emitter including an emission driving transistor to output a driving current based on a data voltage, a write transistor to apply the data voltage to the emission driving transistor in response to a write gate signal, and a light-emitting element to emit light based on the driving current, and a light sensor to sense the light, and including a sensing driving transistor including a first control electrode for receiving a reset voltage and a sensing voltage, and a second control electrode for receiving an adjustable photodiode voltage, for generating a sensing current in response to the sensing voltage, a sensing initialization transistor to apply the reset voltage to the first control electrode in response to a photo initialization gate signal, and a sensing output transistor to apply the sensing current to a sensing line in response to an output gate signal.