Hybrid Pixel Design for Synchronous and Asynchronous Readouts
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Solution Overview
Problem
Current pixel technologies face challenges in combining synchronous and asynchronous readouts efficiently, leading to high power dissipation, noise, and limited low-light sensitivity, especially in capturing detailed scene context and inter-frame dynamics at high frame rates, while also being unsuitable for small pixels and limited to specific imaging applications.
Innovation Solution
A hybrid pixel design that combines a buffered direct injection frame-based capture circuit with a dynamic vision system event-driven capture circuit, allowing simultaneous operation and reducing component count, power usage, and noise, while enabling inter-frame scene dynamic updates at higher frame rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If frame-based readout is used to capture detailed scene context, then measurement precision is improved, but power dissipation increases and temporal redundancies are read out
Solution Approach 1:
The pixel circuit is segmented into distinct functional blocks: a photodiode for signal generation, a first capacitor for integrating frame-based signals, and a second capacitor for integrating event-driven signals. This segmentation allows independent operation of frame-based and event-driven readout paths, enabling the system to capture detailed scene context through frame-based readout while reducing power dissipation by selectively activating only the necessary readout path at any given time.
2Use of energy by moving object
If event-driven readout is used to reduce power dissipation, then power efficiency is improved, but detailed scene context is not captured
Solution Approach 1:
The pixel circuit is designed with multi-functionality to support both frame-based and event-driven readout modes. The shared photodiode and dual-capacitor architecture enable the same pixel to capture detailed scene context when operating in frame-based mode and to achieve power efficiency when operating in event-driven mode. The circuit can dynamically switch between modes or operate both simultaneously, ensuring that detailed scene context is captured when needed while maintaining power efficiency during static scenes.
3Adaptability or versatility
If monolithic silicon-based construction with two photodiodes is used, then asynchronous and frame-based readout are enabled, but device complexity increases and pixel size increases
Solution Approach 1:
The patent merges the frame-based and event-driven readout paths into a single shared photodiode structure. Instead of using two separate photodiodes as in prior art, the invention combines both readout functionalities into one photodiode that can be connected to either the first capacitor (for frame-based readout) or the second capacitor (for event-driven readout). This merging reduces device complexity and decreases pixel size while maintaining dual readout capability.
Solution Approach 2:
The invention transitions from a spatial separation of readout paths (two separate photodiodes) to a temporal separation (single photodiode switching between modes). By adding the time dimension to the readout architecture, the system achieves dual readout capability without increasing spatial complexity. The shared photodiode can be dynamically assigned to different readout modes based on operational requirements, effectively using time-multiplexing to reduce device complexity.
4Area of moving object
If small pixel size is used, then pixel density is improved, but integrating multiple components becomes difficult
Solution Approach 1:
The pixel circuit employs a nested architecture where the first capacitor and second capacitor are integrated within the same pixel structure, sharing common elements such as the photodiode and readout circuitry. The capacitors are arranged in a nested configuration where one capacitor's circuit elements are embedded within or adjacent to the other capacitor's structure. This nesting approach maximizes component density while minimizing the overall pixel area, enabling small pixel size without compromising the ability to integrate multiple components.
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
The hybrid pixel design achieves low-power, low-latency operation with reduced temporal and spatial redundancies, enabling detailed scene context capture and higher effective frame rates, suitable for sensitive imaging applications like missile warning and remote sensing, without adding noise.
Implementation Method 1
a photodiode in electrical communication with both the frame-based and event-driven capture circuits
Data Source
AI summary
A hybrid frame-based and event driven pixel, the pixel comprising a frame-based capture circuit, an event-driven capture circuit, and a photodiode in electrical communication with both the frame-based and event-driven capture circuits, wherein the frame based capture circuit is a buffered direct injection circuit, and wherein the event-driven capture circuit is a dynamic vision system circuit.