Motor Control System for Tape Tension in Thermal Printers
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Solution Overview
Problem
Existing tape drives for thermal transfer printing apparatuses are mechanically complex, require regular maintenance, and struggle to accurately control tape tension and speed, leading to issues with print quality and wastage, especially in continuous configurations where substrate and tape speeds vary.
Innovation Solution
A motor control system utilizing brushless DC motors or comparable motors, with a controller that switches between position control mode and torque control mode to maintain precise tape tension and position, ensuring smooth transitions and accurate control of tape movement between spools, thereby maintaining consistent tape tension and preventing wastage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mechanical clutch is used to maintain tape tension, then the tape tension can be maintained, but the device complexity increases and regular maintenance is required
Solution Approach 1:
The patent replaces the mechanical clutch system with an electronic control system using two motors (first and second motors) that can be independently controlled. The controller adjusts the torque of each motor based on the diameters of the spools to maintain constant tape tension, eliminating the need for mechanical clutches and their associated complexity and maintenance requirements.
Solution Approach 2:
The patent dynamically changes the torque parameter of the motors based on the varying diameters of the spools. The controller continuously monitors and adjusts the motor torques to compensate for diameter changes, maintaining constant tape tension without mechanical intervention. This parameter-based control replaces the fixed mechanical clutch approach.
2Ease of operation
If the supply spool is operated at a fixed torque, then the operation is simple, but the tape tension varies as the diameter of the supply spool varies
Solution Approach 1:
The patent changes the torque parameter from fixed to variable based on spool diameter. The controller calculates the required torque for each motor based on the current diameters of the supply and take-up spools, ensuring that the tape tension remains constant even as the spools wind down or are replenished.
Solution Approach 2:
The system uses feedback from the controller that monitors the spool diameters and adjusts the motor torques accordingly. This closed-loop control ensures that tape tension remains consistent by continuously adapting the motor parameters to the current system state, rather than operating at fixed torque.
3Productivity
If the tape moves at varying speeds to match substrate acceleration, then the printing can continue, but the tape tension control becomes more difficult
Solution Approach 1:
The patent divides the tape drive system into two independently controlled segments: the first motor controls the supply spool while the second motor controls the take-up spool. This segmentation allows independent optimization of each motor's function, with the controller coordinating their torques to maintain constant tape tension during acceleration and speed variations.
Solution Approach 2:
The controller dynamically adjusts the torque parameters of both motors based on the tape speed and acceleration requirements. By changing the torque parameters in response to speed variations, the system maintains constant tape tension even during continuous printing operations with varying substrate speeds.
Data Source
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AI summary
A motor control system (25) including a motor (16, 18) having an associated rotary position encoder (20, 22), and a controller (24) for controlling the operation of the motor (16, 18), wherein the motor (16, 18) is switchable between a position control mode and a torque control mode.