Piezoelectric Sensing Layer Under TFT for Ultrasonic Biometrics
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Solution Overview
Problem
Existing display devices face challenges in recognizing biometric information without reducing the active area size, as the arrangement of optical sensors in the bezel area can degrade sensing performance and affect display driving.
Innovation Solution
Incorporating piezoelectric devices within the active area of the display panel for ultrasonic sensing, with a sensing layer including piezoelectric material and thin-film transistors, allowing for biometric recognition without reducing the display panel's active area size, and separating high-temperature and low-temperature fabrication processes for increased convenience.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If optical sensors are arranged in the bezel area to recognize biometric information, then sensing function is provided, but the active area size of the display panel is reduced
Solution Approach 1:
The patent transitions the sensing function from the lateral bezel area to the vertical depth dimension by placing piezoelectric sensors beneath the display panel's active area. This allows biometric sensing to occur within the existing active area footprint without lateral expansion, effectively utilizing the Z-dimension (depth) to resolve the space conflict.
Solution Approach 2:
The patent replaces optical sensing mechanisms with piezoelectric sensing mechanisms. Instead of using optical sensors that require lateral space in the bezel area, the invention employs piezoelectric materials that can be integrated vertically within the active area structure, enabling mechanical-to-electrical signal conversion for touch and biometric detection.
2Area of stationary object
If sensors are implemented in the active area to maintain active area size, then active area size is maintained, but sensing performance is degraded or display driving is affected
Solution Approach 1:
The patent segments the pixel structure into distinct functional layers: display pixels for visual output and sensing pixels for biometric detection. Each pixel type has dedicated thin-film transistors (TFTs) and electrode structures, allowing independent optimization of display and sensing functions without mutual interference, thereby maintaining both active area size and sensing performance.
Solution Approach 2:
The patent introduces piezoelectric materials as intermediary elements between the user's touch and the sensing electrodes. These piezoelectric layers convert mechanical pressure from touch into electrical signals, serving as a mediation mechanism that enables high-performance sensing within the active area without directly interfering with display pixel operation.
3Measurement precision
If piezoelectric devices are built in the active area for ultrasonic sensing, then sensing performance is improved, but fabrication process complexity increases
Solution Approach 1:
The patent merges the fabrication processes for piezoelectric sensing devices with the existing TFT and display layer manufacturing processes. By integrating piezoelectric material deposition, electrode formation, and pixel structure creation into the established fabrication sequence, the invention achieves ultrasonic sensing capability without requiring entirely new fabrication equipment or processes, thereby managing complexity through process consolidation.
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
Enables effective ultrasonic sensing within the display panel's active area while maintaining image display functionality, enhancing process convenience and preventing a reduction in active area size.
Implementation Method 1
piezoelectric devices are built in the active area of the display panel and sensing may be performed using ultrasonic waves
Data Source
AI summary
Provided are a display panel and a display device. After deposition of a thin-film transistor layer and a display layer in which emitting devices are disposed, a sensing layer including a piezoelectric material is disposed under the thin-film transistor layer to facilitate implementation of a display panel having built-in piezoelectric devices. Further, as thin-film transistors for ultrasonic sensing and thin-film transistors for display driving are disposed in different layers, a display panel capable of ultrasonic sensing in an active area may be provided without affecting a display resolution or implementation of display pixels.