Image Sensor Fault Detection Circuit for Column Line Stability
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Solution Overview
Problem
Image sensors face performance degradation due to faults such as resistive shorts, broken connections, and parasitic capacitance issues in column lines, which affect the stability and accuracy of pixel signal readout.
Innovation Solution
A fault detection circuit is introduced, comprising a signal unit for applying electrical signals to column lines, a determining unit for measuring responses, and a controller for identifying faults and outputting a fault status, allowing for the detection of resistive shorts, broken connections, and other issues, and enabling the readout unit to be powered down or accounting for faults during image processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fault detection circuitry is added to detect column line faults, then reliability is improved, but device complexity increases
Solution Approach 1:
The fault detection circuit merges with the existing readout unit by sharing the same column line connection and utilizing the same signal processing infrastructure. The fault detection functionality is integrated into the readout unit rather than being a separate external circuit, thereby improving reliability while minimizing the increase in device complexity.
Solution Approach 2:
The readout unit is designed to perform multiple functions: normal pixel signal readout and fault detection. By making the readout unit universal, the patent avoids adding dedicated fault detection hardware for each function, thus improving reliability without proportionally increasing device complexity.
2Productivity
If multiple readout units are provided for simultaneous processing of multiple column lines, then productivity is improved, but device complexity increases
Solution Approach 1:
The image sensor is divided into multiple readout units, each responsible for processing signals from a specific subset of column lines. This segmentation allows parallel processing of multiple column lines simultaneously, improving productivity while keeping each individual readout unit's complexity manageable through modular design.
3Device complexity
If column line faults are not detected, then device complexity remains low, but reliability deteriorates due to performance degradation
Solution Approach 1:
The fault detection circuit enables the image sensor to self-diagnose column line faults without requiring external testing equipment or complex additional circuitry. The system monitors its own health status using integrated fault detection capabilities, improving reliability while maintaining relatively simple device architecture.
Data Source
AI summary
The present invention relates to a fault detection circuit for detecting one or more column faults in a pixel array of an image sensor. The present invention further relates to a readout circuit for reading out a column line of an image sensor, and to an image sensor comprising the same.The fault detection circuit according to the invention comprises a signal unit for applying an electrical signal to a given column line of the pixel array, a determining unit for measuring a response to the applied electrical signal and for determining whether a fault exists for said given column line in dependence of the measured response, and a controller for controlling the signal unit and the determining unit, and for outputting a fault status for said given column line.