Cam-Controlled Platen Roller Pressing Force for Thermal Printers
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Solution Overview
Problem
Conventional printing devices require different springs for pressing and separating the platen roller from the thermal head, leading to increased spring tolerance and reduced precision in controlling the pressing force, which affects printing quality.
Innovation Solution
A printing device with a cam mechanism that rotates to adjust the pressing force of the platen roller against the thermal head, using a single set of springs for both pressing and separating, allowing for precise control of the pressing force through the cam's inclined surfaces and pressers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If different springs are used for pressing and separating the platen roller, then the pressing force can be controlled, but the spring tolerance increases and precision is reduced
Solution Approach 1:
The patent combines the pressing and separating functions into a single spring mechanism. The platen roller is pressed against the thermal head by a single spring that also provides the separating force when the cam rotates to its idle position. This eliminates the need for multiple springs with different tolerances, reducing overall spring tolerance accumulation and improving pressing force control precision.
Solution Approach 2:
The patent uses a cam mechanism to dynamically control the pressing force. The cam's rotating surface varies the compression of the single spring during rotation, providing different pressing forces at different angular positions. This dynamic control allows precise adjustment of pressing force without requiring multiple springs with different static characteristics.
2Adaptability or versatility
If multiple springs are used for pressing and separating, then the functions are differentiated, but the device complexity increases
Solution Approach 1:
The patent merges the pressing and separating functions into a single spring-cam system. The single spring provides both the pressing force when compressed by the cam and the separating force when the cam rotates to its idle position. This reduces the number of spring components from two to one, simplifying the device while maintaining functional differentiation through the cam's rotational motion.
Solution Approach 2:
The single spring serves multiple functions: it acts as both the pressing spring and the separating spring. The cam mechanism enables this universal spring to perform different functions at different rotation angles, eliminating the need for separate dedicated springs for each function and reducing overall device complexity.
3Measurement precision
If a cam mechanism is used to control pressing force, then precision is improved, but the device structure becomes more complex
Solution Approach 1:
The cam mechanism provides dynamic control of the pressing force through its rotating profile. As the cam rotates, its varying radius or profile height dynamically adjusts the compression of the spring, thereby precisely controlling the pressing force applied to the platen roller. This dynamic control achieves high precision without requiring complex feedback systems.
Solution Approach 2:
The cam acts as an intermediary mechanism between the motor drive and the spring pressing system. It translates rotational motion into controlled linear compression of the spring, providing precise pressing force control while isolating the complexity of the control mechanism from the simple spring-platen roller assembly.
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 enables improved printing quality by accurately controlling the pressing force, reducing spring tolerance, and simplifying the device's design while allowing for easy adjustment of the pressing force, enhancing the printing process.
Implementation Method 1
a cam including a first guide for releasing pressing of the platen roller against the print head and a second guide for pressing the platen roller against the print head
Data Source
AI summary
The printing device comprises: a print head for printing on a tape; a platen roller for conveying the tape by rotation with the tape held between the print head and the platen roller; a supporter for rotatably supporting the platen roller; and a cam including a first guide for releasing pressing of the platen roller against the print head and a second guide for pressing the platen roller against the print head.