Switchable Filter Pixels for Image Sensor Noise Correction
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Solution Overview
Problem
Existing image-capturing devices face challenges in obtaining image signals from light-shielded pixels, leading to incomplete data collection and reduced image quality due to color mixing and dark current noise.
Innovation Solution
The device employs a dual-pixel system with filter units that can switch between light-shielding and transmissive states, using a correction unit to calculate and apply color mixing correction coefficients and dark current components, allowing for rigorous signal correction and high-quality image generation without dead pixels during main image capture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If light-shielded pixels are used for calibration, then color mixing correction accuracy is improved, but image signal acquisition is lost at light-shielded pixel positions
Solution Approach 1:
The filter unit is configured to switch between light-shielding state and transmissive state dynamically. During calibration mode, the filter unit shields light to enable accurate color mixing correction measurement. During image capture mode, the filter unit transmits light to allow image signal acquisition at all pixel positions, eliminating dead pixels while maintaining calibration accuracy through temporal separation of functions.
Solution Approach 2:
The system periodically switches between calibration operation and image capture operation. The filter unit alternates between light-shielding state for calibration and transmissive state for imaging. This periodic action allows the same pixel to serve dual purposes: calibration reference and image signal acquisition, resolving the contradiction between needing light-shielded pixels for accuracy and needing all pixels functional for imaging.
2Measurement precision
If filter units are set to light-shielding state for calibration, then dark current noise measurement is improved, but image capture capability is reduced
Solution Approach 1:
The filter unit dynamically changes its optical state based on operational mode. During dark current calibration, the filter unit adopts light-shielding state to block incident light and enable accurate dark current measurement. During normal image capture, the filter unit switches to transmissive state to allow full light transmission and maintain high imaging productivity, thus resolving the contradiction between measurement accuracy and capture efficiency through temporal separation.
Solution Approach 2:
The system performs dark current calibration in advance before actual image capture. By conducting calibration measurements when the filter unit is in light-shielding state prior to imaging, the system obtains dark current reference data without compromising subsequent image capture productivity. This preliminary action separates the measurement function from the capture function in time, allowing both to optimize their respective performances.
3Loss of information
If all pixels are used for image capture, then image data completeness is improved, but color mixing and dark current correction accuracy deteriorate
Solution Approach 1:
The system implements periodic alternation between calibration mode and image capture mode. During calibration periods, the filter unit shields light at specific pixel positions to enable accurate measurement of color mixing and dark current characteristics. During capture periods, all pixels including previously light-shielded ones are activated for complete image data acquisition. This periodic switching allows the system to achieve both complete image data and high correction accuracy by separating measurement and capture functions in time.
Solution Approach 2:
The filter units dynamically adjust their state based on operational requirements. Pixels that serve as calibration references during calibration mode become fully functional image capture pixels during imaging mode. This dynamic reconfiguration allows the same pixel array to provide both calibration reference signals and complete image data, resolving the contradiction between data completeness and measurement precision through temporal functional separation.
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 approach enables accurate correction of pixel signals, eliminating noise components and ensuring high-quality image data by utilizing light-shielded pixels for calibration and transmissive pixels for image capture, thereby improving image quality and efficiency.
Implementation Method 1
a photoelectric conversion unit that generates an electric charge through photoelectric conversion of light transmitted through the filter unit
Data Source
AI summary
Image-capturing device includes: an image sensor that includes a first pixel and a second pixel, each having a filter unit that can be switched to a light-shielding state in which light is blocked or to a transmissive state in which light is transmitted, a photoelectric conversion unit that generates an electric charge through photoelectric conversion of light transmitted through the filter unit and an output unit that outputs a signal based upon electric charge generated at the photoelectric conversion unit, and; a correction unit that corrects a signal output from the output unit of the first pixel while the filter unit of the first pixel is in a transmissive state, based upon a signal output from the output unit of the first pixel with the filter unit of the first pixel set in a light-shielding state and with the filter unit of the second pixel set in a transmissive state.