Computational Pixel Imager With In-Pixel Counters for High Dynamic Range
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Solution Overview
Problem
Conventional imaging systems using integrated-circuit technology face limitations in dynamic range and efficiency, particularly in achieving high dynamic ranges with small pixel sizes and in applications requiring low-noise sensing across various spectral ranges.
Innovation Solution
The development of computational pixel imagers (CPIs) with in-pixel digitization circuitry, including arrays of photodetectors and pixel integrated circuits, that enable digital signal processing within the pixel, allowing for infinite dynamic-range sensing and efficient data handling through multi-thread processing and counter configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional imaging systems use integrated-circuit technology with photodetectors and capacitors, then the system can achieve basic imaging functionality, but the dynamic range is limited and pixel size cannot be reduced further
Solution Approach 1:
The patent replaces the conventional capacitor-based charge storage mechanism with a digital counter-based counting mechanism. Instead of accumulating charge on a capacitor and reading it out, the system uses multiple digital counters in each pixel to count photons or photoelectrons directly, enabling infinite dynamic range without being constrained by capacitor size or saturation limits.
Solution Approach 2:
The patent implements multiple counters per pixel that can be configured for different functions: some counters count up, some count down, and they can be selectively enabled or disabled. This multi-functional counter array within each pixel allows the same hardware structure to handle various imaging modes and dynamic range requirements, reducing overall system complexity while maintaining high dynamic range capability.
2Area of moving object
If the pixel size is reduced to increase array density, then more pixels can be packed into the sensor, but noise increases and dynamic range decreases
Solution Approach 1:
The patent replaces the analog charge accumulation approach with digital counting, where each pixel contains multiple digital counters that can independently count events. This digital approach allows for better noise filtering and signal processing within each pixel, maintaining low noise levels even as pixel size decreases and array density increases.
Solution Approach 2:
The patent divides each pixel into multiple independent counting units (first counter, second counter, third counter, etc.), where each counter can be independently controlled and configured. This segmentation allows the pixel to process signals from multiple photodetectors or handle different wavelength ranges independently, improving signal-to-noise ratio and maintaining reliability in smaller pixels.
3Measurement precision
If multiple counters are implemented in each pixel, then infinite dynamic range and multi-thread processing are achieved, but the pixel circuit complexity increases
Solution Approach 1:
The patent designs the multiple counters within each pixel to be universally configurable - they can all perform counting operations, but with different configurations (count up, count down, enabled/disabled states). This universal design allows the same counter circuitry to serve multiple purposes, reducing the need for additional specialized circuits and managing complexity while maintaining infinite dynamic range capability.
Solution Approach 2:
The patent implements control logic that automatically manages the multiple counters based on imaging conditions. The system can selectively enable or disable specific counters, and configure them for different counting directions, without requiring external intervention for each pixel. This self-service approach simplifies the overall control architecture while maintaining the benefits of multiple counters per pixel.
4Productivity
If in-pixel digitization and processing are implemented, then data handling efficiency is improved, but power consumption increases
Solution Approach 1:
The patent segments the pixel array into multiple independently controllable counting units, allowing the system to activate only the necessary counters for current imaging conditions. This segmentation enables selective processing, where only active pixels and counters consume power, reducing overall power consumption while maintaining high data handling efficiency for the active portion of the array.
Solution Approach 2:
The patent implements periodic resetting and reading of counter values, allowing the system to process data in efficient batches rather than continuously. The counters can accumulate data over multiple periods and then be read out and reset in synchronized operations, improving data handling efficiency while minimizing the time counters are active and consuming power.
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
CPIs enhance dynamic range capabilities, reduce noise, and improve efficiency in imaging systems by enabling high-resolution imaging across various spectral ranges with reduced pixel size and power consumption, suitable for applications like industrial inspection, surveillance, and autonomous vehicles.
Implementation Method 1
Each of the pixels may be a charge-coupled device (CCD) or complementary metal-oxide semiconductor (CMOS) device, in which photocurrent generated by illumination of a photodiode of the pixel accumulates charge on a capacitor of the pixel
Data Source
Figure 1A~1B
Figure 2~3A
Figure 3B
AI summary
A stereo imaging system includes an optical assembly and a computational pixel imager (CPI) having a plurality of pixels. Each pixel includes a light sensor and counters that convert a photocurrent from the light sensor to a digital signal. The optical assembly, which directs light from a light field to the CPI, includes an optical field combiner and first and second primary lens assemblies, which are configured to receive first and second portions of the light from the light field, respectively, and to direct the first and second portions of the light to the optical field combiner. The optical field combiner includes a modulator configured to modulate the first and second portions of the light and to direct modulated first and second portions of the light onto the CPI. The counters are configured to perform digital signal processing on the digital signal.