Thermal Printer Head Swing Mechanism for Even Force Distribution

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Solution Overview

Problem

Thermal printers face issues with uneven pressing forces during paper feeding, leading to print line offset due to the swinging of the thermal head and deformation of the platen roller, which affects printing quality.

Innovation Solution

A thermal printer design incorporating a support pin and deformable mechanism allows the printing device to swing and adjust, ensuring even pressing forces and maintaining the thermal head's position through plastic deformation, while an elastic element and adjustable support pin facilitate adaptive force distribution and gap adjustment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the thermal head is pressed downward to ensure close contact with the paper sheet, then printing quality is improved, but the thermal head may swing due to uneven force distribution, causing print line offset

Engineering Contradiction:
Improveprinting qualityVSAvoidprint line position accuracy
Core Design Contradiction:
Manufacturing precisionVSMeasurement precision

Solution Approach 1:

The patent applies the dynamics principle by making the thermal head movable rather than fixed. The thermal head is allowed to swing on its rotation shaft, and a swing limiting mechanism is introduced to control the range of motion. This dynamic design enables the thermal head to automatically adjust its position in response to uneven paper feeding forces, maintaining even pressing force distribution across the paper sheet while preventing excessive swinging that would cause print line offset.

Inventive Principle:
Principle #15Dynamics

2Adaptability or versatility

If the platen roller is made deformable to adapt to paper thickness variations, then adaptability is improved, but the roller deforms under reactive force, causing thermal head displacement and print line offset

Engineering Contradiction:
Improveadaptability to paper thicknessVSAvoidthermal head position accuracy
Core Design Contradiction:
Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent applies the dynamics principle by making the platen roller deformable rather than rigid. The platen roller is designed to deform elastically in response to reactive forces during paper feeding, allowing it to adapt to variations in paper thickness and maintain good contact with the paper sheet. This dynamic deformability enables the system to accommodate different paper conditions while the swing limiting mechanism prevents excessive thermal head displacement.

Inventive Principle:
Principle #15Dynamics

3Manufacturing precision

If the rotation shaft of the thermal head is positioned rearwardly to minimize platen roller compression, then printing quality is improved, but the thermal head becomes more sensitive to force deviations and swings more easily

Engineering Contradiction:
Improveprinting qualityVSAvoidthermal head position stability
Core Design Contradiction:
Manufacturing precisionVSStability of the object's composition

Solution Approach 1:

The patent applies the preliminary anti-action principle by introducing a swing limiting mechanism that preemptively counteracts the tendency of the thermal head to swing excessively. The swing limiting mechanism is configured to restrict the thermal head's movement within a controlled range, preventing the thermal head from displacing too much in response to force deviations. This preliminary constraint maintains the benefits of the rearwardly positioned rotation shaft for printing quality while compensating for the increased sensitivity to force variations.

Inventive Principle:
Principle #9Preliminary anti-action

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 solution ensures stable and even printing force distribution, preventing print line offset and improving printing quality by allowing the printer to self-adapt to varying forces and paper thickness, maintaining high sensitivity and accuracy.

Implementation Method 1

an elastic element disposed between the holder and the base part, wherein when the recording paper sheet is clamped between the printing device and the platen roller, both the printing device and the platen roller are in close contact with the recording paper sheet due to the elastic element

Methodology Applied
Scientific EffectElastic force: Elasticity

Implementation Method 2

the deformable mechanism is capable of being plastically deformed to keep the position of the printing device

Methodology Applied
Scientific EffectPlastic deformation: Plasticity

Data Source

PatentEP4023447B1Thermal-sensitive printer
Publication Date: 2023.11.29 LIN JINYI
  • EP4023447B1 patent drawingFigure 1~2
  • EP4023447B1 patent drawingFigure 3~4
  • EP4023447B1 patent drawingFigure 5~6

AI summary

A thermal printer comprises a base part, a holding member, a printing device and a platen roller. When an uneven pressing force is applied to the printing device by the recording paper sheet, the printing device is capable of swinging about the support pin serving as a fulcrum in order to even out the pressing force. The deformable mechanism is capable of being plastically deformed to keep the position of the printing device. An elastic element is disposed between the holding member and the base part, and due to the elastic element, both the printing device and the platen roller are in close contact with the recording paper sheet when the recording paper sheet is clamped between the printing device and the platen roller. The printing force of the printing device acting on the printing paper sheet can be distributed more even to achieve clearer printing.