Thermal Printer Pixel Density Correction for Dot Repeatability
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Solution Overview
Problem
Thermal printers face issues with repeatability and sharpness of printed dots, especially when there are large changes in image density due to the delay in thermal response of the thermal head, leading to printing defects and unevenness.
Innovation Solution
The thermal printer extends the number of pixels in the feed direction of the paper sheet to generate extended image data, analyzes changes in density, and corrects the density of each pixel to account for thermal response delays, ensuring high repeatability and sharpness even in images with large density changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the thermal head heats the ink seat to perform printing with large density changes, then the printing speed is maintained, but the thermal response delay causes poor repeatability and sharpness of printed dots
Solution Approach 1:
The invention applies preliminary action by predicting the required heating amount for each heater element based on image data before actual printing occurs. The prediction unit calculates the necessary heating adjustments in advance to compensate for thermal response delay, ensuring that even when printing at high speed with large density changes, the repeatability and sharpness of printed dots are maintained.
2Use of energy by moving object
If the heating amount is reduced for low density printing, then energy consumption decreases, but uneven ink development occurs due to energization pulse distribution
Solution Approach 1:
The invention applies local quality by adjusting the heating amount for each individual heater element based on the specific density requirements of different regions in the image. The prediction unit calculates customized heating amounts for each heater element, ensuring that even in low density areas, the energization pulse distribution is optimized to prevent uneven ink development while maintaining energy efficiency.
3Productivity
If multiple lines are heated continuously to improve printing speed, then productivity increases, but thermal damage accumulates in the ink sheet
Solution Approach 1:
The invention applies parameter changes by dynamically adjusting the heating amount parameter for each heater element based on predicted requirements. Instead of continuous heating at constant power, the system varies the heating parameters line by line, reducing thermal accumulation in the ink sheet while maintaining high printing speed through optimized heat application.
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 approach provides high repeatability and sharpness of printed dots, effectively addressing the issues of density changes and thermal response delays, resulting in improved printing quality.
Implementation Method 1
A thermal printer heats an ink seat by a thermal head and thermally transfers ink to a paper sheet
Implementation Method 2
Heater elements are linearly disposed (in a straight line) in the thermal head used in the thermal printer
Data Source
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AI summary
Provided is a thermal printer achieving high repeatability of one dot even in an image having a large change in a density and capable of printing a printing material having high sharpness. A thermal printer includes: an image data extension processing unit generating extended image data having a plurality of extended pixels in which the number of pixels in a feed direction of a paper sheet is extended for image data of the image; a printing data correction processing unit correcting a density of at least one extended pixel of the plurality of extended pixels based on a change in a density of the plurality of extended pixels in the extended image data in the feed direction of the paper sheet or a change in a density of a plurality of pixels in the image data before being extended in the feed direction of the paper sheet; and a printing unit printing the image on the paper sheet by the thermal head based on the extended image data in which the density of the at least one extended pixel is corrected.