Thermal Printer Head Positioning Stability
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Solution Overview
Problem
Existing thermal printer units face challenges in maintaining high print quality due to variations in paper thickness and stiffness, as the positional relationship between the thermal head and platen roller can shift during paper conveyance, leading to decreased image quality and requiring frequent adjustments.
Innovation Solution
A thermal printer unit is designed with a combination of fixing means, thermal head movement preventing means, and thermal head rotation preventing means to maintain the optimal positional relationship between the thermal head and platen roller, preventing movement in the paper conveyance and rotating directions, and incorporating torsion prevention to stabilize the thermal head.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the thermal head and platen roller are pressurized and nipped away from the vertex of the platen roller to obtain high print quality, then print quality is improved, but the thermal head moves in the rotating direction due to applied force, changing the relative position and decreasing image quality
Solution Approach 1:
The invention applies a preliminary counteracting force through the support member to offset the rotating force (F3) that causes thermal head movement. By designing the support member to provide opposing support, the system prevents the thermal head from moving in the rotating direction before the movement can occur, thereby maintaining the optimal relative position while enabling high-quality printing away from the platen roller vertex
2Reliability
If the thermal head movement preventing method is implemented using existing techniques, then the thermal head is prevented from moving in the paper conveyance direction, but the thermal head still moves in the rotating direction due to force applied by paper of different thickness and stiffness, requiring frequent position adjustments
Solution Approach 1:
The support member is designed to provide universal support that simultaneously addresses both paper conveyance direction stability and rotating direction stability. This single structural element performs multiple functions: supporting the thermal head, preventing movement in the paper conveyance direction, and counteracting rotating forces from papers of varying thickness and stiffness, thereby eliminating the need for frequent adjustments across different paper types
3Device complexity
If a driving portion of the platen roller is located only on one side, then the structure is simplified, but distortion phenomenon is generated on both sides of the thermal head due to driving delay or pressurizing balance
Solution Approach 1:
The support member acts as a counterbalancing element that compensates for the distortion forces generated by the single-sided driving portion. By providing opposing support force, the support member counteracts the driving delay and pressurizing imbalance, preventing distortion phenomena on both sides of the thermal head while maintaining the simplified single-sided driving structure
Data Source
AI summary
A thermal printer unit according to the invention includes a thermal head, a platen roller which is disposed while facing the thermal head, a support member which fixes the thermal head while thermal transfer ribbon and receptor paper are pressurized and nipped between the thermal head and the platen roller, a conveyance mechanism which conveys the thermal transfer ribbon and the receptor paper using the thermal head and the platen roller, an engaging groove which prevents the thermal head from moving in a paper conveyance direction by the support member, and a retaining portion which prevents the thermal head from moving in a rotating direction, the movement of the thermal head in the rotating direction being generated according to rotation of the platen roller.