Display Device Segmented Light Emission for Fingerprint Authentication
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Solution Overview
Problem
Display devices that use light for fingerprint sensing face challenges in distinguishing between valid and forged fingerprints, leading to potential security issues due to the difficulty in differentiating between the two.
Innovation Solution
A display device configuration with a selected area where pixels emit light in a sensing pattern, utilizing light sensors and a readout circuit to generate sensing information, including a first mode for photoplethysmography (PPG) information and a second mode for fingerprint image information, allowing for the discrimination between valid and forged fingerprints with minimal configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If light sensors are used for fingerprint sensing, then fingerprint authentication function is enabled, but ability to distinguish forged fingerprint from valid fingerprint deteriorates
Solution Approach 1:
The sensing area is divided into a first area for light emission and a second area for light reception. This segmentation allows the system to collect multiple types of sensing information (PPG information from the second area and fingerprint image information from both areas), enabling discrimination between valid and forged fingerprints while maintaining fingerprint authentication functionality
Solution Approach 2:
The light sensors in the second area serve dual purposes: they receive light for PPG information detection and contribute to fingerprint image information collection. This multi-functionality allows the same hardware configuration to achieve both health-based authentication and traditional fingerprint imaging, improving forged fingerprint detection without adding separate dedicated sensors
2Measurement precision
If separate areas for light emission and reception are implemented, then discrimination between PPG and fingerprint image information is enabled, but device complexity increases
Solution Approach 1:
The same light sensors in the second area are used for both PPG information detection and fingerprint image information collection. By controlling the emission timing and reading sensing signals at different periods, the system achieves multiple sensing functions without requiring separate dedicated sensor arrays, thus limiting the increase in device complexity
Solution Approach 2:
The control circuit controls pixel light emission and light sensor reading in different periods within a frame period. During a first period, pixels emit light and the readout circuit reads sensing signals for PPG information; during a second period, pixels emit light again and the readout circuit reads sensing signals for fingerprint image information. This periodic action allows one hardware configuration to serve multiple sensing purposes
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
Enables effective fingerprint sensing and discrimination between valid and forged fingerprints, enhancing security by using a minimal configuration that separates light emission and reception areas to differentiate between PPG and fingerprint image information.
Implementation Method 1
a plurality of light sensors configured to generate sensing signals corresponding to a received light amount
Implementation Method 2
the first sensing information may be photoplethysmography (PPG) information
Data Source
AI summary
A display device includes: a plurality of pixels in which at least a first portion of the pixels positioned in a selected area are configured to emit light in a sensing pattern; and a plurality of light sensors configured to generate sensing signals corresponding to a received light amount, wherein the selected area comprises a first area and a second area, and wherein in a first mode, a second portion of pixels positioned in the first area are configured to emit light in the sensing pattern, and to generate first sensing information using sensing signals generated by light sensors positioned in the second area, which does not overlap the first area.