Readout Integrated Circuit Discharging Circuit Settling Time
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Solution Overview
Problem
In large fingerprint sensing panels, optical sensors far from output terminals transmit fingerprint sensing signals over longer distances, leading to increased load on sensing lines and prolonged settling times, which degrade the quality of the fingerprint image.
Innovation Solution
A readout integrated circuit with a discharging circuit that controls the discharge of output terminals by a current during a readout period, reducing the settling time of fingerprint sensing signals and improving image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the size of the fingerprint sensing panel is increased, then the sensing area is improved, but the transmission distance from optical sensors to output terminals increases, leading to prolonged settling time
Solution Approach 1:
The sensing panel is divided into multiple sensing regions with multiple output terminals, so that optical sensors are grouped into different readout channels. This segmentation reduces the maximum transmission distance from any sensor to its nearest output terminal, thereby reducing the settling time while maintaining a large overall sensing area
Solution Approach 2:
Multiple output terminals are arranged in a two-dimensional array corresponding to the sensing panel layout, rather than using a single centralized output terminal. This spatial distribution in another dimension reduces the average and maximum transmission distances, solving the settling time issue while preserving large sensing area
2Area of stationary object
If optical sensors are located far from output terminals, then the sensing area coverage is improved, but the load on sensing lines increases, degrading signal quality
Solution Approach 1:
The sensing panel is divided into multiple sensing regions, each with its own output terminal. This segmentation ensures that no optical sensor is located too far from its corresponding output terminal, reducing the load on individual sensing lines and maintaining signal quality across the entire large sensing area
Solution Approach 2:
Each local sensing region is designed with its own output terminal, creating locally optimized signal transmission paths. This ensures that in each local area, the sensing line length and load are controlled, maintaining high signal quality while the overall sensing area remains large
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
The solution significantly reduces the settling time of fingerprint sensing signals, thereby enhancing the quality of the fingerprint image generated by the readout integrated circuit.
Implementation Method 1
The first discharging circuit is configured to discharge an output terminal included in the plurality of output terminals of the optical sensing panel by a first current during a readout period
Data Source
AI summary
A readout integrated circuit configured to read out sensing signals from an optical sensing panel is provided. The optical sensing panel includes a sensor array for fingerprint sensing. The readout integrated circuit includes a plurality of input terminals and a first discharging circuit. The plurality of input terminals are coupled to a plurality of output terminals of the optical sensing panel. The first discharging circuit is coupled to one of the plurality of input terminals. The first discharging circuit serves to discharge an output terminal included in the plurality of output terminals of the optical sensing panel by a first current during a readout period. The readout integrated circuit reads out a voltage of the output terminal as a sensing signal. The first discharging circuit includes a first switch element controlled by a control signal and a first current source which generates the first current.