Printer Power Control for External Devices
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Solution Overview
Problem
Conventional printing devices that supply power to external devices via an interface, such as USB PD, risk causing power shortages in the external devices when reducing power supply upon receiving a print command, leading to potential power shortages regardless of the type of print command.
Innovation Solution
A printing device with a controller that determines whether to limit or maintain the power supply to an external device based on specific conditions, such as print job type, priority, and power requirements, to prevent power shortages, including a hybrid mode that delays printing during power constraints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the printing device reduces power supplied to the external device when receiving a print command, then the printing device can execute printing, but the external device may suffer power shortage
Solution Approach 1:
The patent changes the parameter of power supply level based on print job priority. High-priority print jobs trigger power reduction to enable printing, while low-priority jobs maintain normal power levels. This dynamic parameter adjustment resolves the contradiction by adapting power supply to the specific needs of each print job type.
Solution Approach 2:
The patent implements dynamic power supply control where the power level is not fixed but adjusts based on real-time conditions (print job priority, power consumption requirements). The controller dynamically switches between power reduction mode and normal power mode, allowing the system to adapt to varying demands and prevent external device power shortages.
2Productivity
If the printing device reduces power supply for every print command, then printing can be executed, but the external device is likely to suffer power shortage
Solution Approach 1:
The patent applies different power supply strategies to different types of print jobs based on their priority and power consumption characteristics. High-priority jobs with low power consumption receive power reduction treatment, while low-priority jobs with high power consumption maintain normal power supply. This localized differentiation resolves the contradiction by avoiding unnecessary power reductions.
Solution Approach 2:
The patent segments print jobs into different priority categories (high and low priority) and applies distinct power supply control policies to each segment. This segmentation allows the system to selectively reduce power only for appropriate job types, preventing external device power shortages while maintaining printing productivity.
3Productivity
If the printing device limits power level to execute printing, then printing can be performed, but the external device may experience power interruption
Solution Approach 1:
The patent performs preliminary evaluation of power consumption requirements before executing printing. The controller assesses whether reducing power will cause external device interruption based on the external device's power consumption profile and the print job's characteristics. This preliminary action prevents harmful power interruptions before they occur.
Solution Approach 2:
The patent implements feedback control where the controller continuously monitors the external device's power status and adjusts power supply accordingly. When the external device shows signs of power stress or interruption risk, the controller modifies power reduction decisions. This feedback mechanism prevents power interruptions while enabling print execution when safe.
Data Source
AI summary
The printing device includes a printing unit, an interface, and a controller. In a case that a print job is received while electric power is being supplied to an external device from the interface, the controller determines whether a first condition or a second condition is met. The print job is for commanding the printing unit to execute printing. The second condition is different from the first condition. The controller executes printing based on the print job while limiting a level of the electric power being supplied to the external device from the interface in a case that the controller determines that the first condition is met. The controller holds the print job without limiting a level of the electric power supplied to the external device from the interface in a case that the controller determines that the second condition is met.