USB Type-C Interface Dynamic Role Switching for POS Printers
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Solution Overview
Problem
The USB-Type-C interface in existing printing apparatuses lacks a suitable Dual Role Port (DRP) setting, which hinders efficient power management and communication between the printer and external devices, particularly in Point of Sale (POS) systems.
Innovation Solution
A USB-Type-C interface is configured to switch between a first state for executing printing operations and a second state for supplying power to external devices, utilizing a state identification terminal that alternates between two potentials when no external device is connected, ensuring the printer can operate as both a sink and a source, and supply power to connected devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the USB-Type-C interface uses a standard DRP setting, then the interface can support both DFP and UFP functions, but the printing apparatus cannot efficiently manage power delivery and communication with external devices
Solution Approach 1:
The patent implements dynamic switching of the CC terminal potential between first potential (indicating UFP) and second potential (indicating DFP) based on the operational state. The control circuit dynamically determines whether to switch the CC terminal to first or second potential according to whether the printing apparatus is in printing mode or power supply mode, enabling adaptive role switching that optimizes power management and communication efficiency
Solution Approach 2:
The patent changes the electrical parameter (potential level) of the CC terminal to indicate different operational states. By switching the CC terminal potential between first potential (when external device is connected) and second potential (when external device is disconnected), the system encodes state information in the electrical parameter, allowing the external device to correctly identify the printing apparatus role without complex signaling protocols
2Speed
If the CC terminal switches potential frequently to indicate state changes, then the external device can quickly detect role changes, but switching during external device connection causes communication errors
Solution Approach 1:
The control circuit performs preliminary detection to determine whether an external device is connected before switching the CC terminal potential. By checking the connection state in advance and preventing potential switching when a device is connected, the system avoids causing communication errors or role confusion, ensuring reliable operation while still enabling rapid state detection when appropriate
3Power
If the USB-Type-C interface is configured for power supply mode by default, then power can be supplied to external devices, but printing operations cannot be executed in response to external device requests
Solution Approach 1:
The system dynamically switches between power supply mode and printing operation mode based on external device requests and operational conditions. The control circuit monitors incoming requests and switches the CC terminal potential accordingly, enabling the printing apparatus to adapt its role between DFP (power supply) and UFP (printing operation) as needed
Solution Approach 2:
The USB-Type-C interface is designed to support multiple functions through the DRP configuration and dynamic role switching. The same physical interface can serve both as a power supply port (DFP) and as a data communication port for printing operations (UFP), eliminating the need for separate interfaces and enabling versatile operation modes
Data Source
AI summary
A printing apparatus includes a printing section performing printing, and a USB-Type-C interface configured to perform switching to a first state in which a printing operation is executed or a second state in which the power is supplied to the external device. The USB-Type-C interface includes a state identification terminal held at a first potential indicating that the USB-Type-C interface is coupled in the first state or a second potential indicating that the USB-Type-C interface is coupled in the second state. The state identification terminal is periodically switched between the first potential and the second potential during a unit time when the external device is not coupled to the USB-Type-C interface, and in the unit time, a time at which the state identification terminal is held at the second potential is longer than a time at which the state identification terminal is held at the first potential.