Magnetic Printhead Drive Assembly for Thermal Printers
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Solution Overview
Problem
Prior thermal printers rely on pneumatic systems for printhead movement, which limits pressure variation and requires compressed air, and motor-driven systems, which may not offer precise control over printhead positioning and pressure.
Innovation Solution
A thermal printer using a printhead drive assembly with a permanent magnet and an electromagnet to generate controlled attractive and repulsive magnetic forces, allowing for precise movement and pressure control of the printhead, enabling variable printing forces without continuous electromagnet energization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a pneumatic air cylinder is used to move the printhead, then the printhead can be pressed into contact with the printing surface, but the pressure applied cannot be readily varied and compressed air is required
Solution Approach 1:
The patent replaces the pneumatic system with a magnetic field-based actuation system. An electromagnet generates a magnetic field that interacts with a permanent magnet to move the printhead, eliminating the need for compressed air while enabling variable pressure control through electrical signal modulation.
Solution Approach 2:
The patent changes the control parameter from pneumatic pressure to electrical current magnitude. By varying the current supplied to the electromagnet, the magnetic field strength is adjusted, which directly controls the printhead pressing force without requiring changes in compressed air pressure.
2Speed
If a motor is used to move the printhead, then movement can be achieved, but precise control over printhead positioning and pressure is not readily available
Solution Approach 1:
The patent replaces the motor-driven mechanical system with a magnetic field-based actuation system. The electromagnet's magnetic field can be precisely controlled through electrical signals, enabling accurate control of printhead position and pressure without the mechanical complexity of motor control systems.
3Measurement precision
If an electromagnet is used continuously to hold the printhead, then positioning control is achieved, but energy consumption increases
Solution Approach 1:
The patent employs periodic action by using the electromagnet only when needed to change the printhead position or pressure, rather than continuously energizing it to maintain position. The permanent magnet provides continuous holding force, so the electromagnet is activated periodically for adjustments only.
Solution Approach 2:
The permanent magnet provides continuous self-holding force without requiring continuous energy input. The electromagnet assists only when position changes are needed, making the system self-sustaining through the permanent magnet's inherent magnetic field.
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
The solution provides precise control over printhead movement and pressure, improving print quality and reducing energy consumption by allowing for variable printing forces and eliminating the need for continuous electromagnet energization.
Implementation Method 1
a printhead drive assembly configured to cause movement of the printhead towards and away from the printing surface, the printhead drive assembly comprising a permanent magnet and an electromagnet. When the electromagnet is in a first condition, an attractive magnetic force is generated between the permanent magnet and the electromagnet. When the electromagnet is in a second condition, a repulsive magnetic force is generated between the permanent magnet and the electromagnet.
Data Source
AI summary
A printer comprising a printhead configured to selectively cause a mark to be created on a substrate provided adjacent to the printer, the printhead having a first configuration in which the printhead is spaced apart from the printing surface and a second configuration in which the printhead is configured to press the substrate against a printing surface during a printing operation. The printer further comprises a printhead drive assembly configured to cause movement of the printhead towards and away from the printing surface between the first and second configurations, the printhead drive assembly comprising a permanent magnet and an electromagnet. When the electromagnet is in a first condition, an attractive magnetic force is generated between the permanent magnet and the electromagnet, and when the electromagnet is in a second condition, a repulsive magnetic force is generated between the permanent magnet and the electromagnet, each of said attractive and repulsive magnetic forces being configured to one of urge the printhead away from and towards the printing surface. The printhead drive assembly is configured such that, when the printhead is in each of the first and second configurations, it is retained in that configuration by the printhead drive assembly when the electromagnet is in the first condition, the printhead being retained in one of the first and second configurations by said attractive magnetic force generated between the permanent magnet and the electromagnet.