Fingerprint Sensor Vertical Blank Signal Timing
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Solution Overview
Problem
Existing display apparatuses face challenges in enhancing fingerprint sensing performance due to interference from touch sensing signals and display noise.
Innovation Solution
The display apparatus incorporates a fingerprint sensor with a mesh structure of first and second sensing electrodes, a touch sensor with a bridge pattern, and a controller that generates a vertical blank signal to manage driving of the fingerprint sensor, optimizing its performance by adjusting report rates based on noise levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the fingerprint sensor operates continuously at high report rate, then fingerprint sensing performance is improved, but power consumption increases and noise interference from touch sensing affects fingerprint accuracy
Solution Approach 1:
The fingerprint sensor operates periodically rather than continuously, with the driver controlling activation during specific time windows when touch sensing is not active. This periodic operation reduces power consumption while maintaining fingerprint sensing capability, resolving the contradiction between continuous high-performance sensing and energy efficiency.
Solution Approach 2:
The system pre-coordinates fingerprint sensing operations with touch sensing schedules, activating the fingerprint sensor only during time windows when touch sensing signals are not present. This preliminary planning of operation timing prevents noise interference and reduces unnecessary power consumption.
2Speed
If the fingerprint sensor operates during active display period, then real-time fingerprint detection is improved, but display noise interferes with sensing accuracy
Solution Approach 1:
The fingerprint sensing operation is extracted from the continuous display period and relocated to specific time windows during vertical blank periods when display noise is absent. This separation removes the harmful display noise from the sensing process while maintaining timely fingerprint detection capability.
Solution Approach 2:
The vertical blank period serves as an intermediary time window that mediates between display operation and fingerprint sensing. During this intermediate period, neither display nor touch sensing is active, providing a noise-free environment for accurate fingerprint detection.
3Device complexity
If touch sensing and fingerprint sensing share the same sensor structure, then device complexity is reduced, but touch sensing signals interfere with fingerprint sensing accuracy
Solution Approach 1:
The sensor operation is segmented into distinct time windows: touch sensing periods and fingerprint sensing periods. By dividing the operational timeline and assigning different functions to different segments, the system uses a single shared sensor structure without signal interference, resolving the contradiction between structural simplicity and sensing accuracy.
Data Source
AI summary
A display apparatus includes a fingerprint sensor that includes first sensing electrodes and second sensing electrodes, a touch sensor that includes third sensing electrodes and fourth sensing electrodes, a fingerprint sensor driver that transmits a first driving signal to the fingerprint sensor and receives a first sensing signal from the fingerprint sensor, a touch sensor driver that transmits a second driving signal to the touch sensor and receives a second sensing signal from the touch sensor, and a controller that generates a vertical blank signal that has an on-voltage during a vertical blank period and transmits the vertical blank signal to the fingerprint sensor driver. During an on-voltage period of the vertical blank signal, the fingerprint sensor driver drives the fingerprint sensor once.