Foldable Display Ultrasonic Fingerprint Sensing With Resonator Layer
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Designing an under-display ultrasonic sensor system for foldable displays is challenging due to the attenuation of ultrasonic waves by the display stiffener, which severely impacts the performance of ultrasonic fingerprint sensors.
Innovation Solution
Incorporating a transmission enhancement layer between the ultrasonic sensor stack and the display stiffener, forming a transmission enhancement resonator that enhances ultrasonic wave transmission in suitable frequency ranges for fingerprint sensors, without modifying the existing foldable display stack.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a display stiffener is added to maintain physical integrity of foldable display, then structural strength is improved, but ultrasonic wave transmission deteriorates
Solution Approach 1:
A transmission enhancement layer is introduced as an intermediary component between the ultrasonic sensor stack and the display stiffener. This layer acts as a mediator that facilitates ultrasonic wave transmission while allowing the display stiffener to maintain its structural support function. The transmission enhancement layer has acoustic impedance properties that bridge the mismatch between the sensor stack and the stiffener, reducing ultrasonic wave attenuation without compromising structural integrity.
Solution Approach 2:
The acoustic impedance parameters of the layers in the ultrasonic path are optimized to improve wave transmission. Specifically, the transmission enhancement layer is designed with acoustic impedance values that create a gradual transition from the ultrasonic sensor stack to the display stiffener, reducing reflection and transmission loss. This parameter optimization allows the display stiffener to maintain its mechanical strength while minimizing its harmful effect on ultrasonic transmission.
2Reliability
If transmission enhancement layer is added to improve ultrasonic wave transmission, then sensor performance is improved, but device complexity increases
Solution Approach 1:
The transmission enhancement layer is designed to serve multiple functions within the foldable display device. It not only enhances ultrasonic wave transmission for fingerprint sensing but also maintains compatibility with the existing display stack structure and manufacturing processes. By integrating this layer into the existing manufacturing workflow without requiring separate assembly steps, the additional functionality is achieved with minimal increase in overall 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 improves ultrasonic wave transmission in frequency ranges suitable for fingerprint sensors, maintaining sensor performance while avoiding additional manufacturing costs and time.
Implementation Method 1
form a transmission enhancement resonator that enhances ultrasonic wave transmission in the frequency range suitable for ultrasonic fingerprint sensors
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An apparatus may include an ultrasonic sensor stack, a foldable display stack and a transmission enhancement layer. The foldable display stack may include a display stiffener and display stack layers. The display stack layers may form one or more display stack resonators configured to enhance ultrasonic waves transmitted by the ultrasonic sensor stack in a first ultrasonic frequency range. In some implementations, a transmission enhancement resonator may include the display stiffener and the transmission enhancement layer. In some examples, the transmission enhancement resonator may include at least a portion of the ultrasonic sensor stack. The transmission enhancement resonator may be configured to enhance the ultrasonic waves transmitted by the ultrasonic sensor stack in the first ultrasonic frequency range.