Solid-State Imaging Element Defective Pixel Identification
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Solution Overview
Problem
Non-synchronous solid-state imaging elements face challenges in identifying defective pixels without increasing system scale, as existing test methods require a modulation light source and controlled device, making it difficult to perform tests efficiently.
Innovation Solution
A solid-state imaging element with an address event detecting unit that identifies defective pixels based on detection frequency statistics, including a current-voltage conversion circuit, subtractor, and quantizer, which generates detection signals and invalidates outputs for defective pixels, allowing for efficient identification and exclusion of defective pixels without a modulation light source.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a modulation light source and controlled device are used to test defective pixels, then defective pixel identification capability is improved, but device complexity increases
Solution Approach 1:
The imaging element performs self-testing by utilizing its own internal operations to identify defective pixels. The address event detection circuit continuously monitors pixel responses during normal imaging operations, and the detection frequency acquisition unit analyzes the statistical properties of detected events to automatically identify defective pixels without requiring external test equipment.
Solution Approach 2:
The address event detection circuit serves dual purposes: it functions as the primary imaging mechanism for capturing visual information and simultaneously acts as a test mechanism for identifying defective pixels. The same circuitry used for normal operation is leveraged to perform defective pixel detection, eliminating the need for separate testing infrastructure.
2Measurement precision
If continuous monitoring of detection frequency is performed, then defective pixel identification accuracy is improved, but processing time increases
Solution Approach 1:
The system continuously accumulates detection frequency data in the background during normal imaging operations. By the time defective pixel identification is needed, the statistical data has already been collected and processed, allowing for immediate identification without additional processing delay. The preliminary accumulation of statistical information during operation eliminates the need for separate testing time.
3Productivity
If detection frequency statistics are used to identify defective pixels, then test efficiency is improved, but data processing complexity increases
Solution Approach 1:
The system replaces complex physical test setups with statistical data processing. Instead of using modulation light sources and controlled devices, the patent uses the address event detection circuit to collect detection frequency data and applies statistical analysis to identify defective pixels. This substitution of mechanical testing with computational statistics simplifies the overall system while maintaining test efficiency.
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 easy identification and exclusion of defective pixels, reducing system complexity and improving test efficiency by using detection frequency statistics to determine abnormal pixels and invalidate their outputs.
Implementation Method 1
each pixel having a photodiode that photoelectrically converts incident light to generate a current signal
Data Source
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AI summary
A defective pixel is easily identified in a solid-state imaging element that detects an address event. An address event detecting unit detects, as an address event, a fact that an absolute value of a change amount of luminance exceeds a predetermined threshold value with regard to each of a plurality of pixels, and outputs a detection signal indicating a result of the detection. A detection frequency acquisition unit acquires a detection frequency of the address event with regard to each of the plurality of pixels. A defective pixel identification unit identifies, on the basis of a statistic of the detection frequency, a defective pixel where an abnormality has occurred among the plurality of pixels.