In-Display Fingerprint Sensor Pixel Sharing Cathode and Power Lines
Solution Overview
Problem
Conventional fingerprint sensors in smartphones restrict screen design, preventing full-screen displays due to the need for a separate fingerprint recognition module that increases thickness and manufacturing costs.
Innovation Solution
Embedding a photosensor in the display panel allows for fingerprint recognition without a separate sensor module, sharing power and signal lines with display pixels and using the same electrode layer for light emitting elements and photodiodes, enabling full-screen displays with adjusted exposure times for improved sensing accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate fingerprint sensor module is placed below the screen, then fingerprint recognition function is achieved, but device thickness increases and manufacturing cost increases
Solution Approach 1:
The patent merges the fingerprint sensor pixels with the display pixels by embedding sensor pixels within the display panel structure. The sensor pixels share the same substrate, transparent electrode layers, and circuit wiring as the display pixels, eliminating the need for a separate fingerprint sensor module below the screen and thereby reducing device thickness.
Solution Approach 2:
The display panel is designed to serve multiple functions: it acts as both the display interface and the fingerprint sensing interface. The same transparent electrode layers and circuit structures are utilized for both displaying images and sensing fingerprint patterns, achieving multi-functionality without adding separate components.
2Reliability
If a separate fingerprint sensor module is placed below the screen, then fingerprint recognition function is achieved, but assembly process complexity increases and manufacturing cost increases
Solution Approach 1:
The fingerprint sensor pixels are integrated into the display panel during the same manufacturing process. Both display pixels and sensor pixels are formed on the same substrate using the same thin-film deposition and patterning techniques, eliminating the need for separate assembly of a fingerprint sensor module and simplifying the manufacturing process.
Solution Approach 2:
The display panel structure is designed to perform both display and fingerprint sensing functions. The same transparent electrode layers, substrate, and circuit wiring are used for both purposes, reducing the number of assembly steps and manufacturing complexity compared to integrating a separate sensor module.
3Device complexity
If sensor pixels share power lines with display pixels, then device structure is simplified, but voltage fluctuation may affect display luminance stability
Solution Approach 1:
The patent applies different voltage compensation strategies to different regions of the display panel. Display pixels use standard driving voltages optimized for luminance output, while sensor pixels use adjusted driving voltages optimized for fingerprint sensing accuracy. This local differentiation allows shared power lines without compromising either display quality or sensing performance.
Solution Approach 2:
The driving voltage parameters for sensor pixels are specifically adjusted compared to display pixels. By changing the voltage parameters applied to sensor pixels during fingerprint recognition mode, the system compensates for potential voltage drops on shared power lines, ensuring stable display luminance while achieving accurate fingerprint sensing.
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 solution simplifies the display panel structure, reduces manufacturing costs, and enhances fingerprint recognition accuracy by extending exposure time without affecting display pixel luminance, enabling full-screen designs in mobile terminals.
Implementation Method 1
Each of the sensor pixels includes a photosensor driving circuit configured to drive a photodiode
Data Source
AI summary
A display device and a mobile terminal including the same includes a display area in which a first group of display pixels to which pixel data is written are arranged, and a sensing area in which a second group of display pixels and a plurality of sensor pixels are arranged; each of the display pixels includes a pixel circuit configured to drive a light emitting element; each of the sensor pixels includes a photosensor driving circuit configured to drive a photodiode; a low potential power voltage and a pixel driving voltage are applied to the pixel circuit and the photosensor driving circuit; a cathode electrode of the light emitting element and the cathode electrode of the photodiode share the same metal electrode, and are commonly connected to a low potential power line to which the low potential power voltage is applied.