Image Processor USB State Synchronization Power Saving
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional image processing devices with power saving modes face operational mismatching issues when USB devices are attached or detached, as the main system cannot recognize state changes during power saving mode due to its power supply being turned off, leading to potential errors upon returning to normal mode.
Innovation Solution
An image processing device with a sub-control unit that manages power supply changes and monitors USB device states, holding the USB driver state before power saving mode and adjusting it upon return to ensure synchronization with the actual USB device state, using a state transition sequence to correct any mismatches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the main system power supply is turned off during power saving mode, then power consumption is reduced, but the system cannot recognize USB device state changes
Solution Approach 1:
The control system is divided into two independent parts: the main system (CPU) that consumes high power and can be turned off, and the sub-system (ASIC) that consumes minimal power and remains active. The sub-system specifically handles USB device monitoring and power saving mode control, allowing it to detect USB state changes even when the main system is powered off.
Solution Approach 2:
The sub-system acts as an intermediary between the USB devices and the main system. It monitors USB device states, manages power saving mode transitions, and communicates with the main system only when necessary (upon wake-up triggers). This intermediary role allows the main system to remain unaware of USB state changes during power saving mode, eliminating the contradiction between power saving and state recognition.
2Loss of energy
If the main system is turned off to save power, then energy loss is reduced, but operational mismatching occurs upon return to normal mode
Solution Approach 1:
The sub-system performs preliminary actions by monitoring USB device states continuously even when the main system is powered off. It detects wake-up triggers (USB device attachment, detachment, or data activity) and prepares the system for smooth transition back to normal mode, preventing operational mismatching by ensuring the main system wakes up only when necessary.
3Adaptability or versatility
If the sub-system continuously monitors USB devices during power saving mode, then USB device usage is supported, but power consumption increases
Solution Approach 1:
The sub-system is designed with local quality optimized for low-power operation. It uses an ASIC architecture that consumes minimal power (significantly less than the main CPU) while performing USB monitoring functions. This allows the system to maintain USB device support during power saving mode with acceptable power consumption levels.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An object of the invention is to provide an image processing device having a sub-system performing a power saving control to support the use of a USB device or provided to allow the supporting of the use of a USB device, in which operational mismatching which may occur at a start of a the power saving mode between the USB device and a USB device driver provided in the main system of the image processing device can be effectively suppressed. A state of the USB device driver before the mode of the image processing device is changed to the power saving mode is held, and, when the state of the USB device acquired after the mode of the image processing device returns from the power saving mode differs from the held state of the USB device driver, an estimated state-transition sequence for changing a state of the USB device driver is determined by an ACPI driver based on a result of comparison of the held state of the USB device driver and the acquired state of the USB device, thereby changing the state of the USB device driver according to the estimated state-transition sequence.