Active Pixel Sensor Array Pre-Discharging Circuit
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Solution Overview
Problem
Existing under-screen fingerprint detection technologies face delays in signal acquisition due to the gradual increase in voltage at certain points during the strobing transistor's off state, leading to increased reading time for active pixel sensor arrays.
Innovation Solution
The implementation of an active pixel sensor array with a pre-discharging sub-circuit that adjusts the voltage between the source following and strobing sub-circuits, allowing for synchronized on and off times across rows, reducing the time required for signal readout by pre-discharging adjacent rows, thus enhancing signal readout efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the strobing sub-circuit is turned off to read the voltage signal, then the voltage at the node between source following and strobing sub-circuits gradually increases, but this causes a delay in signal acquisition and increases the reading time
Solution Approach 1:
The pre-discharging sub-circuit performs preliminary action by actively discharging the node between source following and strobing sub-circuits before the strobing sub-circuit is turned off. This preliminary discharge action prevents the gradual voltage increase that would otherwise occur during the strobing sub-circuit's off state, enabling faster and more accurate signal acquisition without increasing the reading time.
2Device complexity
If the voltage at the node between source following and strobing sub-circuits is allowed to increase gradually during strobing sub-circuit's off state, then no additional circuit is needed, but the signal readout time increases
Solution Approach 1:
The pre-discharging sub-circuit is introduced to perform preliminary discharge of the node before the strobing sub-circuit turns off. This preliminary action eliminates the need to wait for gradual voltage increase, significantly improving signal readout efficiency while adding only a single additional sub-circuit component.
Solution Approach 2:
The pre-discharging sub-circuit ensures continuous and efficient voltage control by actively managing the node voltage before and during the strobing sub-circuit's operation. This continuous voltage management eliminates idle waiting periods and maintains high signal readout efficiency throughout the operation cycle.
3Adaptability or versatility
If the strobing sub-circuit and pre-discharging sub-circuit have different on/off times across rows, then each row can be optimized independently, but this creates timing complexity and coordination issues
Solution Approach 1:
The patent implements dynamic timing control where the on/off times of the strobing sub-circuit and pre-discharging sub-circuit are adjusted based on the specific row being processed. Each row can have customized timing parameters to optimize performance, while the system dynamically coordinates these variations to maintain overall synchronization and prevent timing conflicts across the array.
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 solution shortens the time for the active pixel sensor array to fall from a high voltage state to a stable state, reducing the overall signal readout period and improving detection efficiency.
Implementation Method 1
each of the pixel circuits includes: a photoelectric conversion sub-circuit
Data Source
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AI summary
A active pixel sensor array includes plurality of pixel circuits arranged in multiple rows and one column or multiple rows and multiple columns, each pixel circuit including: photoelectric conversion sub-circuit; resetting sub-circuit for resetting photoelectric conversion sub-circuit based on reset signal; source following sub-circuit connected between resetting sub-circuit and photoelectric conversion sub-circuit; strobing sub-circuit connected to source following sub-circuit and for switching on/off state based on strobe signal; and pre-discharging sub-circuit with one terminal connected between source following sub-circuit and strobing sub-circuit, and for switching on/off state based on received pre-discharge signal; when pixel circuits are arranged in multiple rows and columns, on time and off time of strobing sub-circuit in same row are same, and on time of strobing sub-circuit in each row is same as that of pre-discharging sub-circuit in next row, and off time of strobing sub-circuit is same as that of pre-discharging sub-circuit in next row.