Sample-And-Hold Temporal Contrast Vision Sensor
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Solution Overview
Problem
Conventional temporal contrast sensors suffer from high inter-pixel mismatch and high power consumption, leading to low temporal contrast sensitivity and increased sensor device area and cost due to the use of dual-capacitor integrate-and-reset circuits.
Innovation Solution
A mismatch-insensitive single-capacitor Sample-And-Hold circuit is employed for temporal differencing, replacing the dual-capacitor integrate-and-reset circuit, which reduces inter-pixel mismatch and power consumption while maintaining sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a dual-capacitor integrate-and-reset circuit is used for temporal differencing, then temporal contrast sensitivity is improved, but inter-pixel mismatch increases and device area increases
Solution Approach 1:
The patent extracts the temporal differencing function from the traditional integrate-and-reset circuit by implementing a sample-and-hold circuit that samples the photodetector output at discrete time intervals. This separates the temporal sampling function from the integration function, allowing the use of a single capacitor instead of dual capacitors, thereby reducing inter-pixel mismatch while maintaining temporal contrast sensitivity.
Solution Approach 2:
The patent segments the temporal differencing operation into discrete sampling events controlled by a sampling signal. Instead of continuous integration followed by resetting, the circuit samples the photodetector output at specific moments, holding the sampled value for comparison. This segmentation allows precise temporal control and reduces the need for multiple capacitors.
2Measurement precision
If a dual-capacitor integrate-and-reset circuit is used for temporal differencing, then temporal contrast sensitivity is improved, but power consumption increases
Solution Approach 1:
The patent employs periodic sampling action where the sample-and-hold circuit is activated at discrete time intervals by a sampling signal rather than continuous operation. This periodic sampling reduces power consumption by keeping the circuit in a low-power hold state between sampling events, while still capturing temporal contrast information at critical moments.
Solution Approach 2:
By extracting the temporal differencing function into a sample-and-hold mechanism, the patent eliminates the need for continuous integration and frequent resetting operations that consume power in dual-capacitor circuits. The single capacitor is only actively charged during sampling events, significantly reducing overall power consumption.
3Measurement precision
If a dual-capacitor integrate-and-reset circuit is used for temporal differencing, then temporal contrast sensitivity is improved, but sensor device area increases
Solution Approach 1:
The patent merges the temporal sampling and holding functions into a single circuit block using one capacitor instead of two separate capacitors for integration and resetting. The sample-and-hold circuit combines the functions of temporal sampling, signal holding, and temporal differencing in a compact configuration, reducing the overall device area while maintaining temporal contrast sensitivity.
Solution Approach 2:
By segmenting the temporal processing into discrete sampling events, the patent eliminates the need for continuous integration capacitors. The single capacitor is reused for each sampling event, allowing the same hardware component to serve multiple temporal processing functions, thereby reducing the total area required for temporal contrast sensing.
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 solution enhances temporal contrast sensitivity while minimizing power consumption and reducing the sensor area, thus addressing the limitations of prior art approaches.
Implementation Method 1
a photo-sensor stage comprising a photodiode and having an output, said photo-sensor stage configured for delivering a photoreceptor current dependent on a light intensity of an exposure of said photodiode
Data Source
AI summary
This invention relates to a pixel circuit comprising a photo-sensor stage comprising a photodiode delivering a photoreceptor current, a comparison stage configured for detecting a change in a signal voltage derived from said photoreceptor current, a sample-and-hold circuit connected to the converting stage and to the comparison stage, said comparison stage configured to output an input signal for the sample-and-hold circuit, and for emitting a sampling signal to a control terminal of the sample-and-hold circuit when a change is detected in the signal voltage.