Under-Display Sensor with Piezoelectric and Photodetector Pixels
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Solution Overview
Problem
Traditional touchscreen technologies are inadequate for accurate fingerprint scanning and fail to provide additional features like multi-touch sensing and stylus tracking, requiring separate components which increase costs.
Innovation Solution
An under-display sensor using a thin-film transistor (TFT) array with piezoelectric sensor elements and diodes that function as photodetectors for light sensing and peak detectors for pressure sensing, enabling fingerprint scanning, multi-touch sensing, and stylus tracking without additional components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional touchscreen technologies are used, then basic touch interaction is enabled, but fingerprint scanning capability is insufficient
Solution Approach 1:
The patent implements a single under-display sensor that performs multiple functions: optical fingerprint scanning using photodetectors, pressure sensing using piezoelectric elements, and stylus tracking. This multi-functional approach resolves the contradiction by enabling fingerprint scanning accuracy while avoiding the need for separate components, thus maintaining versatility.
Solution Approach 2:
The patent merges optical sensing (photodetectors) and pressure sensing (piezoelectric elements) into a single integrated under-display sensor array. This combination allows the system to achieve both fingerprint scanning accuracy and additional functionalities like multi-touch and stylus tracking through one unified component structure.
2Adaptability or versatility
If separate components are added for fingerprint scanning and additional features, then functional capability is improved, but device complexity and cost increase
Solution Approach 1:
The under-display sensor is designed as a universal component that provides optical fingerprint scanning, pressure sensing for multi-touch, and stylus tracking capabilities all through a single integrated array, eliminating the need for multiple separate components and reducing overall device complexity.
Solution Approach 2:
The patent combines photodetectors and piezoelectric sensor elements into a single integrated under-display sensor structure, merging multiple sensing functions into one component that reduces device complexity while maintaining full functional capability.
3Measurement precision
If optical fingerprint sensors are used, then fingerprint scanning is enabled, but additional functionalities like multi-touch sensing and stylus tracking are not provided
Solution Approach 1:
The under-display sensor achieves universality by incorporating both photodetectors for optical fingerprint scanning and piezoelectric elements for pressure sensing, enabling the single component to provide fingerprint scanning, multi-touch sensing, and stylus tracking functionalities simultaneously.
Solution Approach 2:
The patent merges optical sensing capabilities (photodetectors) and pressure sensing capabilities (piezoelectric elements) into one integrated under-display sensor array, allowing simultaneous execution of fingerprint scanning and additional functionalities like multi-touch and stylus tracking.
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 provides cost-effective and integrated fingerprint scanning, multi-touch sensing, and stylus tracking capabilities, enhancing user interaction and security while maintaining a thin and durable touchscreen design.
Implementation Method 1
each pixel of the array comprises a respective piezoelectric sensor element... for each pixel of a second set of pixels of the array, the respective piezoelectric sensor element detects the pressure wave
Implementation Method 2
for each pixel of a first set of pixels of the array, the respective diode operates as a photodetector to perform the sensing of the light
Implementation Method 3
a piezoelectric layer coupled with the TFT sensor... which can generate a pressure wave during the pressure sensing mode
Data Source
AI summary
Techniques described herein address these and other issues by providing an under-display sensor capable of providing fingerprint scanning over an entire display using optical and/or ultrasonic means. To do so, the sensor comprises an array of pixels, where each can pixel comprises a piezoelectric sensor element and a diode capable of being used as a photodetector during a light-sensing mode, and as a peak detector during a pressure-sensing mode. The sensor may further comprise a piezoelectric layer and one or more electrodes, which can generate a pressure wave during the pressure sensing mode.