Column Readout Circuitry Test Data Injection for Automotive Image Sensors
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Solution Overview
Problem
Conventional automotive image sensors cannot effectively test their integrity while embedded in a vehicle, as it is challenging to impose a known photonic scene on the pixel array, making it difficult to verify their safety compliance with standards like ISO 26262.
Innovation Solution
Incorporating verification circuitry within the image sensor that allows for the injection of test data into captured image frames during normal operation, enabling on-the-fly verification of the sensor's functionality without disrupting imaging operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional automotive image sensors are embedded within the automobile, then the imaging system can perform normal imaging operations, but it becomes impossible to impose a known photonic scene on the pixel array for safety testing
Solution Approach 1:
The patent introduces an intermediary test data injection mechanism that allows test patterns to be injected into the imaging pipeline without requiring external photonic scenes. Test data is injected at the column readout circuitry level, acting as an intermediary between the pixel array and output, enabling safety verification while the sensor remains embedded in the vehicle.
Solution Approach 2:
The image sensor performs self-testing by injecting test data into its own imaging pipeline and verifying the integrity of its components. The sensor uses its existing resources (readout circuitry, processing pipelines) to conduct safety verification without requiring external testing equipment or separate test modes, enabling continuous self-validation during normal operation.
2Reliability
If separate test mode is implemented for safety verification, then testing can be performed, but imaging operations must be interrupted
Solution Approach 1:
The patent enables continuous operation by allowing test data injection and safety verification to occur concurrently with normal imaging operations. The column readout circuitry can switch between capturing real image data and injecting test data without interrupting the overall imaging pipeline, ensuring both safety verification and imaging productivity continue simultaneously.
3Reliability
If test data injection circuitry is added to verify sensor integrity, then safety compliance is improved, but device complexity increases
Solution Approach 1:
The test data injection circuitry is designed to utilize existing resources in the imaging pipeline, such as column readout circuits and data processing pathways. By making these existing components multi-functional (handling both real image data and test data), the patent avoids adding significant complexity while achieving integrity verification capability.
4Ease of operation
If on-the-fly verification is implemented, then real-time testing is enabled, but additional circuitry for test data injection is required
Solution Approach 1:
The patent merges the test data injection functionality with the existing column readout circuitry. The same circuitry that reads out image data from the pixel array is also used to inject and process test data, combining testing functions with existing readout infrastructure and minimizing additional circuitry requirements while enabling real-time verification.
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
Enables continuous monitoring and verification of image sensor performance, ensuring compliance with safety standards and maintaining system integrity by allowing for real-time testing without entering a separate test mode, thus enhancing vehicle safety systems.
Implementation Method 1
Each pixel receives incident photons (light) and converts the photons into electrical signals
Data Source
AI summary
An imaging system may include an array of image pixels and column readout circuits coupled to each column. The column readout circuits may include test data injection circuitry and converter circuitry coupled to column memory via switching circuits. The injection circuitry may enable the switching circuits so that pixel data is stored on the column memory as rows of an image frame. The injection circuitry may disable the switching circuits and may inject test bits onto the column memory while the switching circuits are disabled. The column memory may store the test bits as one or more rows of the image frame interspersed among rows of the pixel data. Verification circuitry coupled to the column readout circuits may process the test data bits in the image frame to verify proper functionality of some or all of the imaging system without disrupting normal imaging operations by the imaging system.