Printer Power Supply Switching Between USB Devices
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Solution Overview
Problem
Information processing apparatuses connected via multiple USB units face challenges in negotiating power supply from external devices, leading to potential power shortages when one external device cannot provide the necessary electric power.
Innovation Solution
The apparatus includes multiple USB interfaces and a controller that requests power from one external device, determines if it can supply power, and if not, requests power from another external device, ensuring continuous power supply by switching between connected devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the information processing apparatus requests power from only one external device via a single USB interface, then the negotiation process is simple, but the reliability of power supply is reduced when that external device cannot provide sufficient power
Solution Approach 1:
The patent divides the power supply function into multiple independent USB interfaces (first USB connecting unit and second USB connecting unit), each capable of negotiating with separate external devices. This segmentation allows the system to attempt power acquisition through multiple independent channels, improving reliability without requiring complex coordination between interfaces.
Solution Approach 2:
The controller performs preliminary power negotiation with external devices connected to each USB interface before determining the final power supply configuration. By预先 negotiating with multiple potential power sources and storing the negotiation results, the system prepares advance power supply paths, ensuring reliable power acquisition even if one external device fails to provide sufficient power.
2Reliability
If the apparatus connects to multiple external devices via multiple USB interfaces to ensure power supply, then the power supply reliability improves, but the difficulty of managing and coordinating power negotiation increases
Solution Approach 1:
Each USB interface independently performs power negotiation with its connected external device according to the USB PD standard. The controller simply collects the negotiation results from each interface without needing to coordinate complex multi-device negotiations. This self-service approach allows multiple power sources to be managed automatically through standardized protocols, maintaining ease of operation while improving reliability.
Solution Approach 2:
The patent merges the power supply capabilities of multiple external devices connected to different USB interfaces into a unified power management system. The controller combines the power supply information from the first and second USB interfaces to determine the total available power, effectively merging multiple independent power sources into a coordinated power supply solution that maintains simple control logic.
Data Source
AI summary
A CPU of a printer requests a first external device to supply electric power via a first interface through communications according to the USB standard. When the CPU determines that the requested electric power is to be unsupplied from the first external device, the CPU requests a second external device to supply the electric power via a second interface.