Mobile Image Sensor Always-On Mode for Low-Power Sensing
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Solution Overview
Problem
Image sensors in mobile devices do not operate in ultra-low power (ULP) mode, leading to unnecessary power consumption during low-power states.
Innovation Solution
Implementing an image sensor with an always-on (AON) mode that captures low resolution data during low-power states and high resolution data during normal-power states, utilizing a sensor hub to analyze sensor data for state transitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If the image sensor operates continuously to capture sensor data during low-power state, then the sensor data availability is improved, but the power consumption increases
Solution Approach 1:
The image sensor changes its operational parameters by switching between different resolution modes (high resolution for normal-power state, low resolution for low-power state) and sampling frequencies (first frequency for high resolution, second lower frequency for low resolution) based on power state conditions, thereby reducing power consumption while maintaining sensor data availability
Solution Approach 2:
The image sensor dynamically adjusts its operation mode based on the power state of the mobile device. The sensor hub determines the power state and configures the image sensor accordingly - operating in first mode during normal-power state and second mode during low-power state, making the system adaptive to changing conditions
2Measurement precision
If the image sensor captures high resolution image data continuously, then the image quality is improved, but the power consumption and data processing load increase
Solution Approach 1:
The image sensor applies different quality levels to different operational contexts by capturing high resolution image data during normal-power state when full quality is needed, and low resolution image data during low-power state when power conservation is prioritized, making quality adaptive to operational requirements
Solution Approach 2:
The image sensor changes resolution parameters and sampling frequencies based on operational mode. During second mode (low-power state), it captures low resolution image data at a second frequency, while during first mode (normal-power state), it captures high resolution image data at a first frequency, optimizing the balance between quality and power consumption
3Use of energy by moving object
If the image sensor operates in ultra-low power mode with reduced sampling frequency, then the power consumption is reduced, but the sensor data coverage and detection capability decrease
Solution Approach 1:
The system dynamically switches between operational modes based on power state. The sensor hub monitors power state and configures the image sensor accordingly - using second mode with lower sampling frequency during low-power state to conserve energy, and switching to first mode with higher sampling frequency during normal-power state to maintain full detection capability
Solution Approach 2:
The image sensor serves multiple functions by operating in different modes for different purposes: during low-power state, it provides basic sensor data monitoring with reduced sampling, while during normal-power state, it provides comprehensive high resolution imaging. This multi-functionality allows the single sensor to meet varying operational requirements
Data Source
AI summary
A mobile device includes an application processor and an image sensor. The application processor includes an imaging subsystem configured to process high resolution image data through a first interface and a sensor hub configured to process sensor data through a second interface. The image sensor operates in one of first and second modes. The image sensor is configured to capture the high resolution image data in response to a request from the imaging subsystem and the imaging subsystem is configured to access the high resolution image data using the first interface for performing a first operation, during the first mode. The image sensor is configured to capture low resolution image data and the sensor hub is configured to access the low resolution image data using the second bus for performing a second operation, during the second mode.