Thermal Printhead Barcode Shifting for Dot Failure Avoidance
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Solution Overview
Problem
Thermal printer dots in weighing scales have a limited lifespan, and existing code checker technologies can only extend their life to a certain extent, failing to fully mitigate the impact of marginal or failed dots, which limits the printer's functionality and reliability.
Innovation Solution
A controller in the thermal printer identifies marginal or out-of-specification print elements and shifts the print location of critical fields like bar codes to align with gaps or offset them, avoiding the use of failing dots, thereby extending the printhead's useful life and ensuring continued functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If code checker technology is used to disable marginal printhead dots, then the life of marginal dots is extended, but the technology has limits in terms of prolonging dot life and cannot fully mitigate the impact of failed dots
Solution Approach 1:
The system performs preliminary detection of marginal dots before they fail completely. The controller identifies dots with resistance values indicating marginal status and proactively creates avoidance patterns for these dots before they become fully failed, thereby extending printhead life while maintaining printing reliability.
Solution Approach 2:
The system dynamically adjusts printing patterns based on the real-time status of printhead dots. When a marginal dot is detected, the controller dynamically modifies the print job to shift barcodes or text fields, redistributing print elements to avoid using the marginal dot, thus adapting the printing process to the current printhead condition.
2Reliability
If marginal print elements are completely disabled to ensure printing quality, then printing reliability is maintained, but the operational lifespan of the printhead is reduced
Solution Approach 1:
Instead of uniformly disabling all marginal dots across the entire printhead, the system applies local quality control by creating avoidance patterns only for specific marginal dots that are detected. Each marginal dot receives individualized treatment based on its resistance value and position, allowing other healthy dots to continue functioning normally.
Solution Approach 2:
The system changes the operational parameters of marginal dots from 'fully active' to 'avoided' based on resistance measurements. This parameter change is not binary but rather a dynamic adjustment where the controller modifies print patterns to redistribute print elements away from dots exceeding resistance thresholds, thereby extending their usable life.
3Productivity
If the printer continues to use failing dots, then productivity is maintained, but the quality of printed barcodes deteriorates
Solution Approach 1:
The system takes preliminary action by detecting resistance changes in dots before they fail completely. By identifying marginal dots in advance and creating avoidance patterns, the system prevents quality deterioration before it occurs, allowing continuous printing with maintained quality standards.
Solution Approach 2:
The system implements continuous feedback monitoring of printhead dot resistance values. The controller regularly measures resistance and uses this feedback to dynamically adjust print patterns, ensuring that dots approaching failure thresholds are avoided before they can produce poor quality barcodes, thereby maintaining both productivity and 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 solution effectively prolongs the life of thermal printer dots by strategically shifting print fields to avoid using failing elements, ensuring reliable printing of critical information like bar codes, even when dots are marginal or failed, thus enhancing the printer's operational lifespan and reducing downtime.
Implementation Method 1
The heating is by resistive elements or 'dots' typically arranged in a row in a printhead
Implementation Method 2
thermal printers in which the image is produced by localized heating of paper that has a very thin thermosensitive coating
Data Source
Figure 1~2
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Figure 4
AI summary
A printing device (52) includes a thermal printhead (52a) with a plurality of print elements (52b). A controller (50) is configured to identify an out of specification status of at least one print element (52b), wherein the controller (50) is further configured to determine whether printing of a specific print field requires use of the print element (52b) having the out of specification status and, if so, to determine whether a print location of the specific print field can be shifted such that the print element (52b) having out of specification status will be one of (i) aligned with a gap in the specific print field or (ii) offset to one side of the specific print field. A weighing scale (10) incorporating the printing device (52) is also provided.