Open-Loop Amplifier Pixel Circuit for Event-Based Vision Sensors
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Solution Overview
Problem
Conventional image sensors are slow in detecting rapid motion and generate excessive data, making them inefficient for applications like security systems and autonomous vehicles that require quick motion detection and processing.
Innovation Solution
A sensor with pixels that include a photosensitive element, a converter, a capacitor, an amplifier with defined gain, and a reset device, which operates without feedback to generate and amplify signals based on light intensity changes, allowing for efficient and asynchronous detection of motion events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional image sensors capture full images frame by frame, then complete image data is obtained, but detection speed for rapid motion is slow and data processing burden increases
Solution Approach 1:
The patent extracts only the essential motion detection function from conventional full-frame image capture. By using event-driven pixels that respond only to brightness changes, the system extracts motion events without capturing redundant static scene data, thereby improving detection speed while maintaining motion detection accuracy
Solution Approach 2:
The patent implements dynamic sampling where pixels adaptively respond to scene changes rather than using fixed frame rates. The event-driven architecture allows the system to dynamically adjust detection activity based on actual motion occurrence, improving both speed and efficiency in detecting rapid motion
2Loss of information
If conventional image sensors capture full images, then detailed scene information is obtained, but data volume increases exponentially requiring extensive processing
Solution Approach 1:
The patent extracts only motion-relevant information from the scene by using event-driven pixels that generate signals only when brightness changes occur. This extraction principle filters out redundant static data while preserving complete motion information, dramatically reducing data volume from exponential to linear with respect to motion events
Solution Approach 2:
The patent applies local quality by making each pixel independently responsive to local brightness changes rather than processing the entire image uniformly. This allows the system to capture motion information precisely where it occurs without generating data from static regions, reducing overall data volume while maintaining motion information completeness
3Productivity
If autonomous vehicles process captured data quickly to match human perception time, then real-time decisions are enabled, but processing efficiency is capped by large data volumes
Solution Approach 1:
The patent performs preliminary action by having pixels pre-process light information and generate event signals directly at the sensor level before data leaves the pixel array. This preliminary processing filters and formats data in advance, enabling faster downstream processing and reducing decision time while improving processing efficiency
Solution Approach 2:
The patent implements self-service through event-driven pixels that autonomously detect and signal brightness changes without requiring external control or processing. Each pixel independently generates motion events when needed, reducing the processing burden on external systems and enabling real-time decisions within human perception timeframes
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
Enables fast and efficient motion detection and data acquisition, reducing the need for extensive processing and data handling, suitable for real-time applications in security systems and autonomous vehicles.
Implementation Method 1
a photosensitive element configured to generate a current signal in response to brightness of light impinging on the photosensitive element
Data Source
AI summary
A pixel circuit is provided for use in an image sensor. The pixel circuit includes a photosensitive element configured to generate a current signal in response to brightness of light impinging on the photosensitive element, and a converter configured to receive the current signal from the photosensitive element and generate a voltage signal based on the received current signal. The pixel circuit also includes a capacitor electrically coupled to the converter in series and configured to receive the voltage signal from the converter, and an amplifier electrically coupled, at an input, to the capacitor in series and configured to generate, at an output, an amplified signal based on an output signal from the capacitor, wherein there is no feedback between the output and the input of the amplifier. Further, the pixel circuit includes a reset device configured to reset the amplifier in response to a trigger signal being generated.