Organic Photodiode Display Pixels for Fingerprint and PPG Sensing
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Solution Overview
Problem
Existing electronic devices with separate bio-sensing sensors reduce the display region size and increase the bezel size, necessitating improved driving conditions for integrated light-sensing pixels within the display device.
Innovation Solution
A display device with a light-emitting pixel and a light-sensing pixel, including an organic photodiode, that adjusts the global reset signal and reset voltage between fingerprint-sensing and photoplethysmography-sensing modes to optimize driving conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a separate bio-sensing sensor is used, then sensing function is provided, but display region size is reduced and bezel size is increased
Solution Approach 1:
The patent merges the bio-sensing function with the display panel by integrating light-sensing pixels directly into the display structure. The light-sensing pixel includes an organic photodiode that can detect light for bio-sensing operations, combining what were previously separate components (display and sensor) into a single integrated unit, thereby maintaining full display region without requiring additional separate sensor hardware
Solution Approach 2:
The light-sensing pixel is designed to perform multiple functions: it serves as both a display pixel (emitting light) and a bio-sensing pixel (detecting light for fingerprint sensing and photoplethysmography). The organic photodiode within the pixel structure enables it to detect reflected light for various sensing modes, making the display region multi-functional and eliminating the need for dedicated separate sensors
2Area of stationary object
If integrated light-sensing pixel is used, then display region size is maintained, but driving conditions need to be optimized for different sensing modes
Solution Approach 1:
The patent implements dynamic adjustment of driving conditions based on the sensing mode. The readout circuit changes the reset voltage level and global reset signal timing according to whether the device is operating in fingerprint-sensing mode, photoplethysmography-sensing mode, or normal display mode. This dynamic adaptation allows the same integrated pixel to optimize its performance for different functions without requiring separate hardware for each mode
Solution Approach 2:
The patent changes key electrical parameters including reset voltage level and global reset signal timing based on the operating mode. In fingerprint-sensing mode, the reset voltage is set to a first level with specific reset timing, while in photoplethysmography-sensing mode, the reset voltage is set to a second level with different timing characteristics. These parameter changes enable the organic photodiode to perform optimally in each sensing mode while maintaining integration
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 sensing accuracy and optimizes driving conditions for both fingerprint-sensing and photoplethysmography-sensing operations, maintaining display region integrity.
Implementation Method 1
a light-sensing pixel including an organic photodiode
Data Source
AI summary
A display device includes a display panel including a light-emitting pixel including a light-emitting element, and a light-sensing pixel including an organic photodiode, and configured to reset the organic photodiode to a reset voltage in response to a global reset signal, a data driver configured to provide a data signal to the light-emitting pixel, a scan driver configured to provide a scan signal to the light-emitting pixel and to the light-sensing pixel, and a readout circuit connected to the light-sensing pixel through a readout line, and configured to change at least one of the global reset signal or the reset voltage between a first sensing mode and a second sensing mode.