Light Sensing Unit in Display Device for Fingerprint Recognition
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The integration of biological recognition systems, such as fingerprint sensing, into portable electronic devices like smartphones is hindered by the need for silicon chips, which increases manufacturing complexity, cost, and compromises aesthetic and usage convenience due to the required space and process additions.
Innovation Solution
A display device structure featuring a first substrate with a pixel driving unit and a second substrate with a light sensing unit, where the light sensing unit is positioned on the displaying side, allowing for biological recognition without the need for additional space on the device surface, and the light sensing unit and pixel driving unit are fabricated on different substrates to maintain resolution and aperture ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a capacitor fingerprint sensing device is used for biological recognition, then biological recognition function is achieved, but device surface space is occupied and manufacturing complexity increases
Solution Approach 1:
The patent merges the fingerprint sensing function with the display structure by integrating the light sensing unit directly into the display panel's second substrate. This combination eliminates the need for separate sensing areas on the device surface, as the display pixels themselves serve dual purposes: displaying information and sensing fingerprint patterns through light absorption differences.
Solution Approach 2:
The display pixels are designed to perform multiple functions: they serve as both display elements and sensing elements. The same pixel structure that emits or displays light also detects light absorption patterns when a finger is placed on the screen, enabling fingerprint recognition without requiring dedicated sensing hardware or additional surface space.
2Adaptability or versatility
If a capacitor fingerprint sensing device is used, then biological recognition is achieved, but manufacturing cost and process complexity increase due to silicon chip requirements
Solution Approach 1:
The patent combines the fingerprint sensing function with the existing display manufacturing process. The light sensing unit is fabricated using the same thin-film transistor (TFT) and pixel electrode structures that are already part of the display panel construction, eliminating the need for separate silicon chip fabrication and integration processes.
Solution Approach 2:
The display panel's existing structures (pixel electrodes, transparent conductive layers, and substrate) serve dual purposes: they perform their primary display function while simultaneously providing the sensing capability. The pixel electrodes act as both display elements and sensing electrodes, eliminating the need for additional dedicated sensing components or complex multi-step manufacturing processes.
3Ease of manufacture
If the light sensing unit is integrated into the display structure, then manufacturing is simplified and costs are reduced, but light loss and overlap between sensing unit and pixel driving unit may occur
Solution Approach 1:
The patent applies local quality by differentiating the optical properties of different pixel regions. The pixel electrodes in the sensing area are designed with specific transparency characteristics that allow sufficient light transmission for fingerprint detection while maintaining display functionality. The sensing unit's light detection capability is optimized for specific wavelength ranges, enabling discrimination between reflected light from the finger and display emitted light.
Solution Approach 2:
The system uses periodic modulation of the display backlight or pixel activation to separate the sensing signal from the display signal. By controlling when display pixels are activated and when sensing measurements are taken, the system can distinguish fingerprint-related light absorption patterns from the background display light, minimizing interference and energy loss.
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 manufacturing, reduces costs, enhances aesthetic experience, and maintains high resolution by minimizing light loss and overlap between the light sensing unit and pixel driving unit, allowing for efficient fingerprint recognition without compromising the device's appearance or functionality.
Implementation Method 1
the light sensing unit is used for receiving the light and outputting the fingerprint sensing signal
Implementation Method 2
the light sensing unit comprises a sensing transistor, and the sensing transistor comprises an active layer formed by an amorphous silicon layer
Data Source
AI summary
A display device is described. The display device includes a first substrate, a second substrate, and a display layer disposed between the first substrate and the second substrate. The first substrate includes a pixel driving unit. The second substrate includes the light sensing unit.