Fingerprint Sensor Peripheral Electrode Power Management
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Solution Overview
Problem
Existing fingerprint identification systems face challenges in achieving a small circuit area, low cost, and low power consumption, particularly in determining whether the pixel array circuit is touched by a user's finger, leading to inefficiencies in power management and security.
Innovation Solution
A fingerprint identification system is designed with peripheral top electrodes overlaid on the circuit, using a capacitive sensing circuit to detect finger contact and generate a control signal to awaken the pixel array circuit from sleep mode, thereby reducing power consumption and maintaining security without additional circuit layout or external elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the pixel array circuit is kept in normal operation mode to ensure immediate fingerprint identification, then the response speed is improved, but the power consumption increases
Solution Approach 1:
The pixel array circuit dynamically switches between sleep mode and normal operation mode based on finger contact detection. The capacitive sensing circuit monitors the sensing electrode, and when finger contact is detected, the pixel array circuit transitions from sleep mode to normal operation mode, optimizing the balance between response speed and power consumption.
Solution Approach 2:
The capacitive sensing circuit performs preliminary detection of finger contact before activating the pixel array circuit. This preliminary action allows the system to prepare for fingerprint identification in advance, ensuring rapid response when finger contact occurs while keeping the pixel array circuit in low-power sleep mode during idle periods.
2Measurement precision
If additional sensing circuits and electrodes are added to detect finger contact, then the detection accuracy is improved, but the device complexity increases
Solution Approach 1:
The capacitive sensing circuit serves multiple functions: it detects finger contact presence, determines finger contact position, and triggers the pixel array circuit activation. By making the sensing circuit multi-functional, the patent avoids adding separate dedicated circuits for each function, thereby improving detection accuracy without proportionally increasing device complexity.
Solution Approach 2:
The patent merges the finger contact detection function with the existing pixel array circuit system. The capacitive sensing circuit is integrated with the pixel array circuit, and the sensing electrode is formed using the same top electrode structure, combining multiple functions into a unified system rather than adding completely separate detection components.
3Area of stationary object
If the pixel array circuit area is reduced to achieve smaller device size, then the device compactness is improved, but the fingerprint sensing capability may be compromised
Solution Approach 1:
The patent divides the fingerprint sensing system into two functional segments: a capacitive sensing circuit for finger contact detection and a pixel array circuit for actual fingerprint identification. This segmentation allows the pixel array circuit to be optimized for its specific function while the sensing circuit handles the preliminary detection, enabling compact design without compromising sensing capability.
Solution Approach 2:
The patent utilizes the capacitive sensing circuit in the peripheral region to detect finger contact, effectively using the surrounding area of the pixel array circuit. This approach allows the system to expand its functional area into the peripheral dimension, enabling compact pixel array design while maintaining effective sensing coverage through the integrated capacitive sensing electrodes.
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 allows for efficient power management by switching the pixel array circuit to normal operation mode only when needed, achieving a small circuit area, low cost, and low power consumption while maintaining effective fingerprint identification.
Implementation Method 1
A layer of peripheral top electrodes is overlaid on a peripheral circuit around the pixel array circuit, and capacitances of the peripheral top electrodes are sensed
Data Source
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AI summary
The disclosure provides a fingerprint identification system, which is formed in an integrated circuit. The fingerprint identification system includes: a pixel array circuit; a first peripheral top electrode; a first capacitive sensing circuit for sensing a capacitance associated with the first peripheral top electrode in a sleep mode and for generating a sensing result; and a logic control circuit for generating the control signal according to the sensing result. When the sensing result shows that the first peripheral top electrode is touched by a finger, the control signal is generated by the logic control circuit so that the pixel array circuit is switched from the sleep mode to the normal operation mode.