In-Cell Light Sensing Pixels for PPG Signal Accuracy
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Electronic devices with bio-sensing capabilities, such as smartphones and smartwatches, face challenges in reducing the display region size and increasing the bezel size due to separate sensors being used for bio-sensing operations like fingerprint sensing and photoplethysmography (PPG) sensing.
Innovation Solution
Incorporating an in-cell light sensor technique within the display region of the display device, utilizing a display panel with pixels that include both light emitting and light sensing elements, and a panel driver to guide users to place fingers on specific sensing regions for PPG signal generation, enhancing accuracy through multiple sensing regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a separate sensor is used for bio-sensing operations, then the sensor can be optimized for sensing performance, but the display region size is reduced and the bezel size is increased
Solution Approach 1:
The patent merges the light emitting element and light sensing pixel into a single integrated pixel structure within the display panel. The light emitting element emits light that passes through the liquid crystal layer and reaches the light sensing pixel, combining the display function and PPG sensing function in one pixel. This integration eliminates the need for separate sensors and maintains the full display region for both display and sensing purposes.
Solution Approach 2:
The integrated pixel serves multiple functions: it acts as both a display pixel for showing visual information and a sensing pixel for PPG bio-sensing operations. The light emitting element provides light for both display and sensing, while the light sensing pixel detects light for both display modulation and blood volume changes. This multi-functionality allows the same structural space to fulfill both display and sensing roles.
2Measurement precision
If multiple sensing regions are displayed on adjacent pixel groups, then the accuracy of PPG signals is improved, but the device complexity increases
Solution Approach 1:
The patent divides the display panel into multiple adjacent pixel groups (first and second adjacent pixel groups) with distinct sensing regions. Each pixel group contains light emitting elements and light sensing pixels arranged to form separate sensing zones. This segmentation allows independent PPG measurements from multiple finger positions simultaneously, improving accuracy by enabling multi-point sensing without requiring a completely separate sensor array.
Solution Approach 2:
The patent utilizes the spatial arrangement of pixels in two dimensions (horizontal and vertical adjacent groups) to create multiple sensing regions. By organizing light emitting elements and sensing pixels in adjacent groups across different dimensions, the system can simultaneously sense multiple finger positions on the display surface, adding spatial dimensionality to the sensing capability without proportionally increasing device complexity.
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 solution increases the accuracy of PPG signals and biomarker determination by integrating light sensing pixels within the display panel, allowing for precise sensing and biomarker generation without enlarging the bezel size.
Implementation Method 1
a light sensing pixel that includes a photodiode
Data Source
AI summary
A display apparatus includes a display panel that includes a plurality of pixels and a panel driver that drives the display panel. The pixels include an adjacent horizontal pixel group that includes first to second pixel-rows and an adjacent vertical pixel group that includes first to second pixel-columns. The pixels include an emitting pixel that includes a light emitting element and a light sensing pixel that includes a photodiode. The panel driver drives the display panel to display a first guidance image that guides a user to place fingers on a first sensing region and a second sensing region of the display panel. The light sensing pixel outputs a sensing current that generates photoplethysmography (PPG) signals by sensing the fingers of the user. The first sensing region and the second sensing region are displayed on one of the adjacent horizontal pixel group or the adjacent vertical pixel group.