SAR ADC Sampling for Low-Power Background Subtraction
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Solution Overview
Problem
Existing systems for background subtraction in computer vision and sensor applications face inefficiencies due to high data rates and power consumption, particularly when comparing large amounts of analog signals to background conditions.
Innovation Solution
An analog-to-digital converter (ADC) system that uses a Successive Approximation Register (SAR) architecture with a sample-and-hold component and comparator to generate a 2-bit output indicative of whether an input signal falls within a threshold of a background signal, reducing the need for fine quantization and thus lowering data rate and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional ADC systems perform fine quantization of all sensor signals, then measurement precision is improved, but power consumption and data rate increase significantly
Solution Approach 1:
The patent segments the ADC operation into two distinct phases: a first mode that performs fine quantization for accurate background subtraction, and a second mode that performs coarse quantization for lower power consumption. This segmentation allows the system to switch between precision and power efficiency based on operational needs, resolving the contradiction between measurement precision and power consumption.
Solution Approach 2:
The system dynamically switches between two quantization modes based on the operational context. The first mode uses higher bit-depth quantization when precise background subtraction is needed, while the second mode uses lower bit-depth quantization when power consumption needs to be reduced. This dynamic adaptation resolves the contradiction by allowing the system to optimize for either precision or power efficiency depending on current requirements.
2Measurement precision
If conventional ADC systems process all sensor data at high resolution, then data accuracy is improved, but data processing load and complexity increase
Solution Approach 1:
The patent segments data processing into two stages: first, background subtraction is performed using high-precision data to establish accurate baseline values; second, subsequent measurements use reduced-precision quantization since the background has already been removed. This segmentation reduces the overall data processing complexity while maintaining accuracy where it matters most.
Solution Approach 2:
The patent extracts and removes the background component from the sensor signal before further processing. By performing background subtraction first and then using coarser quantization on the residual signal, the system reduces data processing complexity. The background information is extracted once at high precision, and subsequent processing operates on smaller, simpler residual values.
3Measurement precision
If ADC systems use high-bit-depth quantization for all pixels, then image quality is improved, but data transmission volume and bandwidth requirements increase
Solution Approach 1:
The patent segments the imaging process into background capture and foreground detection phases. During background capture, high-bit-depth quantization is used to ensure image quality. During foreground detection, the system uses the previously captured background image for subtraction, allowing subsequent frames to use lower bit-depth quantization while maintaining effective image quality for detecting changes.
Solution Approach 2:
The patent performs preliminary background subtraction using high-quality images captured during a background-only period. This preliminary action removes the need for subsequent high-bit-depth quantization, as the background has already been established. The foreground objects can then be detected using lower-precision data, reducing overall data volume while maintaining detection accuracy.
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 proposed ADC system significantly reduces power requirements and data processing by performing only two comparison operations per pixel, allowing for efficient identification of foreground objects while maintaining accuracy in background subtraction.
Implementation Method 1
a comparator configured to compare the sampled signal with a reference voltage to generate a digital output
Data Source
AI summary
An analog-to-digital converter (ADC) sampling system and method for imaging and non-imaging systems to conserve power consumption is provided. The ADC sampling system performs only two comparisons for each pixel based on a background value and a threshold value to determine whether the light detected by the pixel is different from a background image.