Always-On Pixel Circuit Using Subset Scanning for Motion Detection
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Solution Overview
Problem
Image sensors operating in always-on mode face high power consumption due to continuous scanning and monitoring of their field of view, which is inefficient and may lead to increased energy usage and heat generation.
Innovation Solution
The method involves capturing low-spatial resolution frames using a subset of pixels in the sensor array, generating depth maps from these frames, and comparing them to determine if an object has moved within the field of view. This approach reduces the number of active pixels and thus decreases power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If continuous scanning and monitoring is performed using all pixels in always-on mode, then object detection capability is maintained, but power consumption increases significantly
Solution Approach 1:
The patent divides the sensor array into multiple pixel groups, where only a subset of pixels is actively scanning at any given time while other pixels remain in a low-power state. This segmentation allows the system to maintain object detection capability through coordinated scanning of multiple groups while significantly reducing overall power consumption compared to having all pixels scan continuously.
2Use of energy by moving object
If a subset of pixels is used for scanning, then power consumption is reduced, but spatial resolution and detection precision decrease
Solution Approach 1:
The patent implements periodic switching between multiple pixel groups, where each group performs scanning duties in alternating time intervals. This periodic action ensures that over time, all pixels contribute to the scanning function, maintaining comprehensive spatial coverage and detection precision while allowing individual pixels to rest in low-power states, thus reducing overall power consumption.
Data Source
AI summary
An imaging device includes a sensor array with a number of pixels. In an embodiment, the imaging device can be operated by capturing a first low-spatial resolution frame using a subset of pixels of the sensor array and then capturing a second low-spatial resolution frame using the same subset of pixels of the sensor array. A first depth map is generated using raw pixel values of the first low-spatial resolution frame and a second depth map is generated using raw pixel values of the second low-spatial resolution frame. The first depth map can be compared to the second depth map to determine whether an object has moved in a field of view of the imaging device.