CMOS Image Sensor Self-Diagnosis via Internal Test Patterns
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Solution Overview
Problem
Electronic cameras, especially those used in cinema production, face challenges in detecting minor image interference and defects during operation, which can lead to costly retouching and potential re-shooting due to the bulkiness and complexity of existing calibration equipment and analysis software.
Innovation Solution
An image sensor with a signal preprocessing device that applies test input signals to column lines to simulate exposure situations, allowing for real-time monitoring and defect detection without voltage drop, using switches and independently regulated voltage sources to ensure accurate measurements and pattern generation for identifying issues in sensor leads and signal processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If test patterns are filmed with the camera to verify correct function, then defects can be detected, but the equipment is bulky and requires special analysis software and technical knowledge
Solution Approach 1:
The patent applies the copying principle by generating test images directly within the image sensor itself rather than using external physical test patterns. The sensor creates synthetic test patterns (such as black and white stripes or homogeneous areas) internally, eliminating the need for bulky external verification equipment and specialized software, while still enabling comprehensive defect detection
Solution Approach 2:
The image sensor performs self-diagnosis by generating and processing its own test images. The sensor's internal resources (processing units, memory, output interfaces) are utilized to create, analyze, and evaluate test patterns without requiring external computers or specialized software, making the verification process self-contained and independent
2Reliability
If manual retouching is performed for defective images, then image quality can be corrected, but labor costs and time increase significantly
Solution Approach 1:
The patent implements feedback by continuously monitoring image quality parameters during capture and automatically comparing them against predefined quality thresholds. When defects are detected, the system provides immediate feedback and can trigger automatic corrections or alerts, eliminating the need for time-consuming manual retouching later in the workflow
Solution Approach 2:
The system performs preliminary quality checks and defect detection at the moment of image capture rather than waiting for post-production. By identifying and addressing potential issues immediately when they occur, the system prevents the accumulation of defective images that would later require manual retouching, saving significant time and resources
3Ease of operation
If test input signals are applied through column lines with voltage drop, then signal preprocessing can be tested, but measurement accuracy decreases
Solution Approach 1:
The patent applies equipotentiality by connecting voltage sources directly to the column lines through switches, ensuring that the test signal is applied at the same potential level throughout the column line without voltage drop. This maintains signal integrity and measurement accuracy while still allowing comprehensive testing of the signal preprocessing pathway
Data Source
AI summary
The present invention relates to an image sensor, in particular a CMOS image sensor, for electronic cameras, having a plurality of light-sensitive pixels arranged in rows and columns, wherein all or at least some of the pixels of a column are connected to a respective common column line, and wherein the image sensor has a signal preprocessing device for one or more of the column lines to process a exposure signals generated by the pixels which can be applied to the respective column line. The image sensor is made selectively to apply one of at least two test input signals to the column lines.