Vehicle Imaging Sensor Self-Diagnosis Using a Dummy Pixel
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Solution Overview
Problem
Existing imaging devices lack a reliable self-diagnosis mechanism to detect malfunctions, such as signal line breaks or short circuits, which can affect image quality and device performance.
Innovation Solution
The proposed imaging system and device incorporate a first dummy pixel that applies a voltage corresponding to the first voltage of a control line to a signal line, allowing for AD conversion and diagnosis processing to be performed, thereby enabling self-diagnosis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a BIST function is implemented for self-diagnosis, then device reliability is improved, but device complexity increases
Solution Approach 1:
The imaging device performs self-diagnosis using its own internal resources. The dummy pixel and control circuitry are integrated within the imaging device itself, allowing it to autonomously detect malfunctions without requiring external testing equipment. The device uses its existing AD conversion circuit and signal processing pathways to conduct self-testing, making the system self-sufficient for diagnostic purposes.
Solution Approach 2:
A dummy pixel is introduced as an intermediary element to facilitate diagnosis. This dummy pixel receives control signals and generates test output signals that pass through the same signal processing pathways as real pixel signals. By comparing the dummy pixel output with expected values, the system can detect malfunctions in control lines, signal lines, and processing circuits without directly testing these components.
2Measurement precision
If dummy pixels are added for diagnosis, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The dummy pixel is positioned in a specific location within the pixel array (typically in a non-imaging region or as a replacement for a real pixel during testing). This localized addition allows diagnosis functionality to be integrated without affecting the overall pixel array structure or image quality. The dummy pixel has specialized properties (receiving control signals instead of light) that distinguish it from regular pixels while maintaining compatibility with the existing readout circuitry.
3Loss of time
If self-diagnosis is implemented, then loss of time for detecting malfunctions is reduced, but use of energy increases
Solution Approach 1:
The self-diagnosis operation is performed periodically or at specific intervals (e.g., during blanking periods between image captures or at predetermined times). The control circuitry activates the dummy pixel and performs AD conversion only when diagnosis is required, rather than continuously. This periodic operation allows timely detection of malfunctions while minimizing the additional energy consumption compared to continuous monitoring.
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 enables the imaging device to perform effective self-diagnosis, detecting malfunctions and ensuring proper device operation and image quality.
Implementation Method 1
pixels each including a photodiode are arranged in a matrix, and each of the pixels generates an electrical signal corresponding to an amount of received light
Implementation Method 2
an AD conversion circuit (an analog-to-digital converter) converts the electrical signal (an analog signal) generated in each of the pixels into a digital signal
Data Source
AI summary
An imaging system according to the present disclosure includes: an imaging device that is mounted in a vehicle, and captures and generates an image of a peripheral region of the vehicle; and a processing device that is mounted in the vehicle, and executes processing related to a function of controlling the vehicle on the basis of the image. The imaging device includes: a first control line, a first voltage generator that applies a first voltage to the first control line, a first signal line, a plurality of pixels that applies a pixel voltage to the first signal line, a first dummy pixel that applies a voltage corresponding to the first voltage of the first control line to the first signal line in a first period, a converter including a first converter that performs AD conversion on the basis of a voltage of the first signal line in the first period to generate a first digital code, and a diagnosis section that performs diagnosis processing on the basis of the first digital code. The above-described processing device restricts the function of controlling the vehicle on the basis of a result of the diagnosis processing.