Display Substrate Layout for Thin Ultrasonic Fingerprint Sensing
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Solution Overview
Problem
Conventional ultrasonic fingerprint recognition systems for electronic devices, especially those integrated with OLED display panels, increase device thickness due to the placement of sensors at the bottom of the screen, compromising the lightweight design.
Innovation Solution
A display substrate design that integrates ultrasonic sensing elements and micro light-emitting elements on the same layer, with the ultrasonic sensing elements positioned away from the base substrate and electrically connected to a circuit structure layer, allowing for non-overlapping projections and reduced module thickness, while a transparent organic insulating layer protects the micro light-emitting elements and piezoelectric functional layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ultrasonic sensing elements are attached to the bottom of the display screen, then fingerprint recognition function is achieved, but the thickness of the display module increases
Solution Approach 1:
The patent merges the ultrasonic sensing elements with the display substrate by integrating them onto the same substrate. The sensing elements are disposed on the display substrate and electrically connected to drive circuits formed on the same substrate, eliminating the need for separate attachment at the bottom of the display screen. This integration maintains fingerprint recognition functionality while reducing overall module thickness.
Solution Approach 2:
The patent transitions from a three-dimensional stacked structure (sensors at the bottom) to a two-dimensional planar integration on the display substrate. By disposing sensing elements and drive circuits on the same substrate plane, the design achieves functional integration without increasing the thickness dimension, effectively moving the solution from vertical stacking to lateral arrangement.
2Length of moving object
If ultrasonic sensing elements and micro light-emitting elements are disposed on the same layer, then non-overlapping projections are achieved, but precise positioning and insulation are required
Solution Approach 1:
The patent introduces an insulating layer as an intermediary between the ultrasonic sensing elements and micro light-emitting elements disposed on the same layer. This insulating layer prevents electrical interference and short circuits between the two types of elements while allowing them to coexist on the same substrate plane, thereby enabling thin design without compromising manufacturing feasibility.
Solution Approach 2:
The patent applies different functional properties to different regions of the substrate. The insulating layer is selectively positioned between sensing elements and light-emitting elements, providing localized electrical isolation where needed while maintaining other areas' functionality. This localized differentiation enables precise positioning and proper insulation without affecting the entire substrate uniformly.
3Strength
If transparent organic insulating layer covers micro light-emitting elements, then protection and light transmittance are maintained, but signal loss reduction for ultrasonic elements is achieved
Solution Approach 1:
The transparent organic insulating layer is selectively applied to cover only the micro light-emitting elements while leaving the ultrasonic sensing elements exposed. This localized insulation approach protects the light-emitting elements from damage and maintains their light transmittance properties, while simultaneously preventing the insulating layer from interfering with ultrasonic signal transmission from the sensing elements.
Solution Approach 2:
The transparent organic insulating layer serves as a protective intermediary for the micro light-emitting elements, providing mechanical protection and electrical isolation without blocking light transmission. Its transparency ensures that it does not interfere with the optical function of light-emitting elements while also not impeding ultrasonic signal paths to the sensing elements.
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
This design enhances the signal-to-noise ratio and quality of ultrasonic detection, reduces signal loss, and maintains light transmittance, contributing to a thinner and more efficient display module.
Implementation Method 1
The multiple ultrasonic sensing elements each include a piezoelectric functional layer
Implementation Method 2
a transparent organic insulating layer protects the micro light-emitting elements and piezoelectric functional layers, maintaining light transmittance
Data Source
AI summary
Provided is a display substrate, which includes a base substrate, a circuit structure layer disposed on the base substrate, multiple ultrasonic sensing elements and multiple micro light-emitting elements. The multiple ultrasonic sensing elements are disposed on a side of the circuit structure layer away from the base substrate, and are electrically connected to the circuit structure layer, and the multiple light-emitting elements are disposed on the side of the circuit structure layer away from the base substrate, and are electrically connected to the circuit structure layer. An orthographic projection of the multiple ultrasonic sensing elements on the base substrate does not overlap with an orthographic projection of the multiple micro light-emitting elements on the base substrate.