Pixel Reset Voltage Segmentation for Failure Detection
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Solution Overview
Problem
Existing photoelectric conversion devices face errors in failure detection due to defects or deterioration of pixels used for failure detection, leading to incorrect decision-making in harsh environments like on-vehicle use.
Innovation Solution
A photoelectric conversion device is designed with a first pixel for image acquisition and a second pixel for failure detection, where the second pixel resets its floating diffusion portion to a lower voltage than the first pixel, allowing for accurate failure decision-making without reducing the dynamic range of the first pixel's signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pixel is used for failure detection, then failure detection function is enabled, but errors in failure decision occur due to pixel defects or deterioration
Solution Approach 1:
The invention divides the pixel array into two distinct types: first pixels for image acquisition and second pixels for failure detection. This segmentation allows each pixel type to be optimized independently, with second pixels specifically designed for reliable failure detection without being affected by the requirements of image acquisition pixels.
Solution Approach 2:
The invention applies different reset voltages to different pixel types: first pixels use a first reset voltage while second pixels use a second reset voltage with smaller amplitude. This local differentiation in electrical characteristics ensures that second pixels maintain stable output signals suitable for failure detection, reducing errors due to pixel defects or deterioration.
2Measurement precision
If reset voltage amplitude is reduced for failure detection pixel, then failure detection accuracy improves, but dynamic range of image acquisition pixel may be affected
Solution Approach 1:
By segmenting the pixel array into first pixels and second pixels with distinct functions, the invention allows the second pixels to use a reduced reset voltage amplitude optimized for failure detection accuracy, while first pixels maintain their full dynamic range for image acquisition.
Solution Approach 2:
The invention applies different reset voltage amplitudes locally to different pixel types: the second reset voltage with smaller amplitude is applied specifically to second pixels for failure detection, while first pixels continue to use the standard reset voltage that maintains full dynamic range for image acquisition.
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 configuration reduces errors in failure detection while maintaining the dynamic range of the image acquisition pixel, ensuring reliable operation in severe environments.
Implementation Method 1
a photoelectrical conversion unit DA, a transfer transistor M1A, a reset transistor M2A
Data Source
AI summary
A photoelectric conversion device includes a first pixel including a photoelectric converter, a first node to which charge is transferred from the photoelectric converter, and a first transistor that resets a voltage of the first node, and configured to output a first signal in accordance with a voltage of the first node, a second pixel including a second node to which a predetermined voltage is supplied and a second transistor that resets a voltage of the second node, and configured to output a second signal in accordance with a voltage of the second node; and a control line connected to the first transistor and the second transistor. The first transistor resets the first node to a first voltage, and the second transistor resets the second node to a second voltage having a smaller amplitude than the first voltage.