In-Display Fingerprint Sensor Luminance Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Display devices with separate fingerprint sensors increase thickness and manufacturing cost due to the need for external light sources, and result in increased power consumption and potential eye fatigue from elevated image luminance across the entire display area.
Innovation Solution
Incorporating a fingerprint sensor that uses light emitted from the display panel's pixels, with a luminance controller adjusting gamma driving voltage and emission periods to enhance luminance only in the fingerprint sensing area, and a data converter scaling down image data to maintain image quality and reduce power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate fingerprint sensor with external light source is attached to the display panel, then fingerprint sensing function is provided, but the thickness and manufacturing cost increase
Solution Approach 1:
The patent combines the fingerprint sensor with the display panel structure, integrating the fingerprint sensing function into the existing display device rather than using a separate external sensor. This merging eliminates the need for additional external components and reduces overall thickness.
Solution Approach 2:
The display panel serves multiple functions: it displays images and simultaneously acts as a light source for fingerprint sensing. The pixels of the display panel are used to emit light for both display purposes and fingerprint detection, eliminating the need for a separate external light source.
2Reliability
If a separate fingerprint sensor with external light source is attached to the display panel, then fingerprint sensing function is provided, but manufacturing cost increases
Solution Approach 1:
The fingerprint sensor is integrated into the display panel structure, sharing common components such as the light source (pixels) and substrate. This reduces the number of separate components that need to be manufactured and assembled, thereby lowering manufacturing cost.
Solution Approach 2:
The display panel pixels serve dual purposes: displaying images and providing light for fingerprint sensing. This eliminates the need for separate external light sources and reduces the overall component count, leading to lower manufacturing costs.
3Illumination intensity
If the luminance of the entire display area is increased to provide sufficient light for fingerprint detection, then sufficient light for fingerprint sensing is provided, but power consumption increases and eye fatigue occurs
Solution Approach 1:
The patent applies different luminance levels to different regions of the display panel. The first region (fingerprint sensing area) has higher luminance to provide sufficient light for fingerprint detection, while the second region (remaining display area) maintains normal luminance. This localized approach ensures sufficient light for sensing without increasing overall power consumption or causing eye fatigue.
Solution Approach 2:
The display area is divided into two separate regions: a first region for fingerprint sensing with enhanced luminance and a second region for normal display with standard luminance. This segmentation allows independent control of luminance in each region, providing sufficient light where needed while maintaining energy efficiency elsewhere.
4Illumination intensity
If the luminance of the entire display area is increased to provide sufficient light for fingerprint detection, then sufficient light for fingerprint sensing is provided, but eye fatigue occurs
Solution Approach 1:
The display panel provides high luminance only in the specific region where fingerprint sensing is performed, while the rest of the display area maintains normal luminance levels. This localized enhancement ensures sufficient light for accurate fingerprint detection without subjecting the user's eyes to excessive overall brightness, thereby preventing eye fatigue.
Solution Approach 2:
The display area is segmented into a fingerprint sensing region with enhanced luminance and a normal display region with standard luminance. This segmentation ensures that the increased brightness is confined to the necessary area for sensing, avoiding the harmful effect of elevated luminance across the entire display area that would cause eye fatigue.
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 approach reduces the thickness and manufacturing cost of display devices while ensuring sufficient light for accurate fingerprint detection without increasing power consumption or causing eye fatigue, by selectively enhancing luminance in the fingerprint sensing area.
Implementation Method 1
a fingerprint sensor which senses a fingerprint of a finger using light reflected by the finger positioned on the display area among light emitted from the display panel
Implementation Method 2
the luminance controller may select a first gamma driving voltage when the fingerprint sensing mode is in the inactivated state, and select a second gamma driving voltage different from the first gamma driving voltage when the fingerprint sensing mode is in the activated state
Implementation Method 3
the luminance controller may control the light emitting device to emit light during a first period in a frame when the fingerprint sensing mode is in the inactivated state, and control the light emitting device to emit light during a second period, which his longer than the first period, in the frame when the fingerprint sensing mode is in the activated state
Data Source
AI summary
A display device includes: a display panel which displays an image corresponding to an input image data in a display area; and a fingerprint sensor which senses a fingerprint of a finger using light reflected by the finger positioned on the display area among light emitted from the display panel. When a fingerprint sensing mode is changed to an activated state from an inactivated state, a luminance of an image displayed in a first display area corresponding to a position of the finger in the display area is increased.