Dual Organic Photodiode Pixel Circuit for In-Cell Light Sensing
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Solution Overview
Problem
Electronic devices with integrated bio-sensing operations, such as fingerprint sensing and photoplethysmography, face challenges in reducing the display region size and increasing the bezel size due to separate sensors being used, which can be addressed by incorporating an in-cell light sensor technique.
Innovation Solution
A light sensing pixel design featuring two organic photodiodes connected to a single sensing pixel circuit, with equal anode extensions to the circuit, allowing for improved resolution and accuracy in light sensing operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate sensor is used for bio-sensing operations, then the sensor can be integrated into the display device, but the display region size is reduced and the bezel size is increased
Solution Approach 1:
The patent merges the light sensing function with the display pixel structure by integrating an organic photodiode directly into the pixel. The photodiode is positioned at the same location as the light emitting element, allowing the pixel to serve dual purposes: displaying light and sensing light intensity for bio-sensing operations.
Solution Approach 2:
The pixel structure is designed to perform multiple functions simultaneously. The organic light emitting element provides display functionality while the integrated organic photodiode provides light sensing functionality. This multi-functional design eliminates the need for separate sensors, maintaining full display region usage.
2Device complexity
If one organic photodiode is connected to one sensing pixel circuit, then the circuit design is simple, but the resolution and accuracy of light sensing are limited
Solution Approach 1:
The patent combines two organic photodiodes into a single sensing pixel circuit by sharing common circuit components such as the transistor and readout line. This merging approach maintains circuit simplicity while improving measurement precision through the use of two photodiodes that can detect light intensity with enhanced resolution.
Solution Approach 2:
The patent introduces a temporal dimension to the measurement process by sequentially activating the two organic photodiodes through different transfer signals. The first photodiode is activated by a first transfer signal and the second photodiode by a second transfer signal, allowing the circuit to capture light intensity information from multiple spatial positions through time-multiplexed measurement.
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 design enhances the resolution and accuracy of light sensing in display panels by efficiently utilizing a single sensing pixel circuit to drive two organic photodiodes, optimizing space utilization and performance.
Implementation Method 1
a first organic photodiode; a second organic photodiode; and a sensing pixel circuit configured to perform a light sensing operation using the first organic photodiode in response to a first transfer signal, and to perform a light sensing operation using the second organic photodiode in response to a second transfer signal
Data Source
AI summary
A light sensing pixel of a display device includes a first organic photodiode; a second organic photodiode; and a sensing pixel circuit configured to perform a light sensing operation using the first organic photodiode in response to a first transfer signal, and to perform a light sensing operation using the second organic photodiode in response to a second transfer signal.