Thermal Transfer Printer Motor Tension Control
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Solution Overview
Problem
Existing thermal transfer printers using DC motors face challenges in maintaining constant ink ribbon tension due to secular and environmental changes, leading to issues like jamming and wrinkles, and existing solutions increase costs with the use of torque and tension sensors.
Innovation Solution
A thermal transfer printer with a variable calculation unit that acquires parameters for armature current, voltage, and rotational speed of DC motors to calculate and apply constant torque, eliminating the need for expensive sensors by using a central control unit to manage the supply and winding motors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If DC motors are used for supply and winding, then the device complexity is reduced, but the tension control reliability deteriorates due to secular and environmental changes
Solution Approach 1:
The system performs preliminary measurement of armature resistance at startup or calibration phase, storing this value for later use in tension control calculations. This preliminary action compensates for secular changes in motor characteristics without requiring continuous complex sensing during operation.
Solution Approach 2:
The control unit continuously monitors armature current and applies feedback control by adjusting motor voltage based on the relationship between current, resistance, and torque. This feedback mechanism maintains constant tension despite environmental changes affecting motor performance.
2Manufacturing precision
If torque sensors or tension sensors are added, then the tension control precision is improved, but the device complexity and cost increase
Solution Approach 1:
The motor itself serves as the sensing element by utilizing its inherent electrical characteristics (armature current and resistance) to infer torque and tension. This self-service approach eliminates the need for external torque sensors or tension sensors while maintaining control precision.
Solution Approach 2:
The patent replaces mechanical sensing systems (torque sensors, tension sensors) with an electrical measurement system that monitors armature current and resistance. This substitution achieves the same control function with simpler, less expensive components.
3Ease of operation
If constant voltage is applied to DC motors, then the operation is simplified, but the tension stability deteriorates due to motor characteristic changes
Solution Approach 1:
The system transitions from static constant voltage control to dynamic voltage control, where the applied voltage is continuously adjusted based on real-time armature current measurements and the pre-stored resistance value. This dynamic adjustment maintains optimal tension despite changing motor characteristics.
Solution Approach 2:
The control system changes the operating parameters (applied voltage) based on measured armature current and known resistance to maintain constant torque. This parameter adjustment compensates for secular and environmental changes in motor characteristics without complicating the control logic.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration maintains constant ink ribbon tension at a lower cost without torque or tension sensors, effectively addressing secular and environmental changes in DC motors, preventing jamming and wrinkles.
Implementation Method 1
the ink ribbon is heated by the thermal head, and the ink applied to the ink ribbon is thermally transferred to the sheet
Implementation Method 2
a supply motor to rotate the supply bobbin; a winding motor to rotate the winding bobbin; the supply motor and the winding motor are DC motors
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
An object is to provide a thermal transfer printer having an inexpensive configuration and capable of making a tension given to an ink ribbon as constant as possible, even when a secular change and an environmental change occur in a DC motor used as a supply motor and a winding motor. A supply motor control unit 183 controls a supply motor 152 of an ink ribbon supply unit 15. A winding motor control unit 184 controls a winding motor 162 of an ink ribbon winding unit 16. A remaining amount detection unit 17 detects a remaining amount of an ink ribbon 12. A variable calculation unit 185 acquires parameters for an armature current, an applied voltage, and a rotational speed of each of the supply motor 152 and the winding motor 162 while voltages are applied to the supply motor 152 and the winding motor 162 respectively from the supply motor control unit 183 and the winding motor control unit 184, and calculates variables to be used for controlling the supply motor 152 and the winding motor 162 on the basis of the acquired parameters.