Display Device Timing Controller for Fingerprint Sensing
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Solution Overview
Problem
Current display devices face challenges in effectively integrating fingerprint recognition functionality, particularly in efficiently switching between image display and fingerprint sensing modes without compromising image quality or recognition accuracy.
Innovation Solution
The display device incorporates a timing controller that adjusts frame frequencies and pulse intervals between scan signals to differentiate between image display and fingerprint sensing modes, using a first frame frequency for image display and a lower second frame frequency for fingerprint sensing, allowing for extended fingerprint readout periods and improved signal processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a high frame frequency is used for image display, then image display performance is improved, but fingerprint recognition accuracy deteriorates due to insufficient readout time
Solution Approach 1:
The patent applies dynamics by switching between two distinct frame frequencies based on operational mode. During fingerprint sensing mode, the system uses a lower frame frequency (e.g., 1Hz) to extend the readout period and improve recognition accuracy. During normal image display mode, the system switches to a higher frame frequency (e.g., 60Hz or 120Hz) to maintain display performance. This dynamic frequency adjustment resolves the contradiction by optimizing the frame rate for each specific function rather than using a fixed rate.
Solution Approach 2:
The patent changes the frame frequency parameter adaptively based on the operational state. The timing controller receives a mode signal indicating whether the display panel should be in image display mode or fingerprint sensing mode, and accordingly adjusts the scan driver's frame frequency. This parameter change allows the system to allocate sufficient time for photo sensor readout during fingerprint sensing while maintaining high refresh rates during normal display operation.
2Measurement precision
If a low frame frequency is used for fingerprint sensing, then fingerprint readout time is extended and recognition accuracy is improved, but image display productivity is reduced
Solution Approach 1:
The system dynamically adjusts the frame frequency based on the current operational mode. When fingerprint sensing is detected, the frame frequency is reduced to allow extended readout time for accurate fingerprint recognition. When image display is the active mode, the frame frequency is increased to maintain high display productivity. This dynamic switching ensures that each function receives the optimal frame rate without compromising the other.
Solution Approach 2:
The patent implements periodic action through time-division multiplexing between image display and fingerprint sensing operations. The display panel alternates between these two functions in a periodic manner, with the timing controller managing the transition. During fingerprint sensing periods, the lower frame frequency allows complete readout cycles. During display periods, the higher frame frequency maintains visual quality. This periodic switching resolves the contradiction by dedicating specific time intervals to each function with appropriate frame rates.
3Productivity
If the scan driver operates at high frame frequency continuously, then image display quality is maintained, but fingerprint sensing capability is compromised due to insufficient readout period
Solution Approach 1:
The scan driver's operating frequency is made dynamic rather than fixed. Based on the mode signal from the timing controller, the scan driver switches between high frame frequency operation for image display and low frame frequency operation for fingerprint sensing. This dynamic adaptation enables the system to maintain both high image display quality during display mode and effective fingerprint sensing capability during sensing mode, resolving the contradiction between the two functions.
Solution Approach 2:
The patent segments the operational timeline into distinct image display periods and fingerprint sensing periods. During fingerprint sensing periods, the scan driver operates at a reduced frame frequency to allocate sufficient time for photo sensor readout. During image display periods, the scan driver operates at high frame frequency to maintain display quality. This temporal segmentation allows each function to operate under optimal parameters without interfering with the other.
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 enhances fingerprint recognition accuracy and reliability by optimizing the driving frequency during fingerprint readout periods, while maintaining image display performance, thus improving overall user experience.
Implementation Method 1
the photo sensors sense light reflected from a fingerprint
Implementation Method 2
photo sensors electrically connected to each of the scan lines and the sensing lines
Data Source
AI summary
A display device comprises a display panel which comprises scan lines, sensing lines, pixels electrically connected to each of the scan lines, and photo sensors electrically to each of the scan lines and the sensing lines, a scan driver which outputs scan signals to the scan lines according to a scan control signal, a timing controller which outputs the scan control signal to the scan driver, and a readout circuit which receives light sensing signals of the photo sensors from the sensing lines. The timing controller sets a frame frequency of the scan control signal to a first frame frequency in a first mode in which the display panel displays an image. The timing controller sets the frame frequency of the scan control signal to a second frame frequency in a second mode in which the photo sensors sense a fingerprint.