Asymmetric Thermal Printhead Elements for High Resolution Printing

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Solution Overview

Problem

Conventional thermal print heads have limitations in achieving high resolution due to symmetric print elements, resulting in pixels with equal width and length, which restricts their ability to produce images with higher resolution along one axis without increasing the number of control circuits.

Innovation Solution

The asymmetric thermal print head design features print elements with distinct burn widths and lengths, allowing for higher resolution along one axis while maintaining lower resolution along the other, achieved by shifting the print head relative to the substrate, and using fewer control circuits.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If symmetric print elements are used in conventional thermal print heads, then the structure is simple and control circuits are fewer, but the print resolution is limited along both axes

Engineering Contradiction:
Improveprint resolutionVSAvoidcontrol circuits
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent applies asymmetry by designing print elements with non-square heating regions where the dimension along the first axis differs from the dimension along the second axis. This asymmetric geometry allows the print head to achieve different effective resolutions along different axes, thereby improving overall print resolution capability without requiring a proportional increase in control circuits for each dimension

Inventive Principle:
Principle #4Asymmetry

2Manufacturing precision

If the number of control circuits is increased to achieve higher resolution, then print resolution improves, but device complexity and production costs increase

Engineering Contradiction:
Improveprint resolutionVSAvoidcontrol circuits
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent makes each print element multi-functional by designing it to serve dual purposes: controlling pixel dimensions along both the first and second axes simultaneously. The asymmetric heating region of each print element allows a single control circuit to influence resolution in two different directions, thereby achieving high resolution without requiring separate control circuits for each axis

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Manufacturing precision

If symmetric print elements are used, then production costs are lower, but the ability to produce high-resolution images along one axis is restricted

Engineering Contradiction:
Improveprint resolutionVSAvoidproduction cost
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent applies local quality by making each print element asymmetric with different heating region dimensions along different axes. This allows the print head to provide locally optimized resolution characteristics - higher effective resolution along the axis where the heating region is smaller, while maintaining manufacturability through a single standardized asymmetric element design rather than requiring different elements for different resolution requirements

Inventive Principle:
Principle #3Local quality

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 design enhances print resolution along one axis by approximately double, reducing the number of control circuits required and lowering production costs, while maintaining effective image printing capabilities.

Implementation Method 1

Each print element is configured to heat a pixel-sized portion of the print ribbon to transfer a corresponding image pixel of the print consumable to the substrate

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Data Source

PatentEP3505354B1Thermal printhead having asymmetric recording elements
Publication Date: 2021.03.17 ASSA ABLOY AB
  • EP3505354B1 patent drawingFigure 1~5
  • EP3505354B1 patent drawingFigure 3~4
  • EP3505354B1 patent drawingFigure 6~7

AI summary

An asymmetric thermal print head includes a print head body (100) and a plurality of print elements (106) supported on the print head body. The print elements are aligned along a first axis (108). Each print element includes a heater portion having a burn width (134) measured along the first axis corresponding to a first print resolution, and a burn length (136) measured along a second axis (128), which is perpendicular to the first axis, corresponding to a second print resolution. The second print resolution is higher than the first print resolution. One or more control circuits (176) are configured to individually activate the print elements.