Display Panel Pixel Light for Fingerprint Sensing
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Solution Overview
Problem
Display devices requiring fingerprint recognition typically need a separate light source, which increases thickness and cost, and can cause afterimages and color differences due to pixel light usage.
Innovation Solution
A display device with a display panel that uses pixels to generate light for fingerprint recognition without a separate light source, featuring a panel driving unit, fingerprint detecting unit, and emitting area setting unit to adjust the emitting area and luminance based on fingerprint sensing operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate light source is added for fingerprint recognition, then fingerprint sensing capability is improved, but device thickness and manufacturing cost increase
Solution Approach 1:
The patent merges the light source function with the display panel by using the display panel's pixels to generate light for fingerprint sensing. This eliminates the need for a separate light source, thereby reducing device thickness while maintaining fingerprint sensing capability. The display panel serves dual purposes: displaying images and providing illumination for fingerprint recognition.
Solution Approach 2:
The display panel is designed to perform multiple functions: it serves as both the image display component and the light source for fingerprint sensing. By making the display panel universal, the patent eliminates the need for additional dedicated components, reducing overall device complexity and thickness.
2Device complexity
If pixel light is used for fingerprint detection, then separate light source is eliminated, but afterimages and color differences occur
Solution Approach 1:
The patent employs periodic action by sequentially activating different color sub-pixels (red, green, blue) in time-separated intervals. During fingerprint sensing, the display panel displays a test image where sub-pixels of different colors are turned on at different times. The photo sensors capture reflected light from each color sequence separately, allowing the system to process and compensate for color differences through temporal separation of color emissions.
Solution Approach 2:
The patent changes the luminance parameters of different sub-pixels to compensate for their inherently different brightness characteristics. By adjusting the driving current or voltage applied to each color sub-pixel, the system equalizes their luminance output, thereby preventing color differences in the fingerprint sensing process while maintaining the use of pixel-generated light.
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 reduces the thickness and cost of the display device, minimizes afterimages, and prevents color differences by using light emitted from the pixels for fingerprint detection, allowing for efficient and accurate fingerprint recognition.
Implementation Method 1
a layer disposed on the display panel and including photo sensors to generate sensing signals upon activation of the photo sensors
Data Source
AI summary
A display device includes a display panel having a display area including pixels in a emitting area, a layer disposed on the display panel and including photo sensors to generate sensing signals upon activation thereof, a panel driving unit to supply a first signal, during a first mode, to display an image in the display area, and supply a second signal, during a second mode, to increase the luminance of the emitting area, a detecting unit to perform a fingerprint sensing operation to detect a fingerprint, during the second mode, based on sensing signals received from the photo sensors, and a setting unit to change a characteristic of the emitting area in response to the fingerprint sensing operation.