Thermal Printer Pulse Control for Uniform Optical Density
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Solution Overview
Problem
Existing printing methods using thermal heads often result in uneven optical density and reduced print quality due to variations in print speed across a page, leading to inconsistent print quality.
Innovation Solution
The method involves adjusting print speed to a constant speed by extending the scanning line time and correcting the length of the application period of the energizing current, ensuring uniform optical density through the use of a continuously variable speed method and heat history control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If print speed is varied per line to optimize printing efficiency, then productivity is improved, but manufacturing precision deteriorates due to non-uniform optical density
Solution Approach 1:
The patent implements dynamic print speed adjustment by dividing the printing area into multiple regions and assigning different print speeds to each region based on the density of print targets. This allows the system to adaptively change printing parameters during the printing process, optimizing both efficiency and quality for different areas of the print medium.
Solution Approach 2:
The patent applies different print speeds to different regions of the print medium based on local characteristics. By analyzing the distribution of print targets and dividing the area into regions with varying densities, the system assigns appropriate print speeds to each region, ensuring high-quality printing in dense areas while maintaining efficiency in sparse areas.
2Manufacturing precision
If print speed is reduced to maintain uniform optical density, then manufacturing precision is improved, but productivity deteriorates due to decreased printing throughput
Solution Approach 1:
The patent segments the print medium into multiple regions based on print target density, allowing different print speeds to be applied to different segments. This segmentation enables the system to maintain uniform optical density across the entire print medium while avoiding unnecessary speed reductions in regions where they are not needed, thus preserving printing throughput.
Solution Approach 2:
The patent dynamically changes the print speed parameter across different regions of the print medium based on local print target density. By adjusting this critical parameter spatially rather than uniformly, the system achieves uniform optical density while maintaining high overall printing throughput.
3Device complexity
If constant print speed is used to simplify control, then device complexity is reduced, but manufacturing precision deteriorates due to inability to handle varying print densities
Solution Approach 1:
The patent performs preliminary analysis of the print data to identify regions with different print target densities before actual printing begins. Based on this pre-analysis, the system pre-determines the optimal print speed for each region, storing these parameters for use during printing. This preliminary action enables quality consistent printing without requiring complex real-time control adjustments during the printing process.
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 enhances print quality by maintaining consistent optical density across a page, preventing reductions in throughput and improving overall print quality.
Implementation Method 1
a thermal head supplies a predetermined current independently to a plurality of heating elements, which are arranged in a line shape, to heat them and form a dot pattern
Data Source
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AI summary
An embodiment of the present invention provides a printer configured to print on a print medium having a thermal color developing layer. The printer includes a thermal head, a pulse setting unit, an application period correction unit, and a print speed determination unit. The thermal head has a plurality of heating elements that are arranged in a line. The pulse setting unit is configured to set a first application period of a pulse of energizing current, during a scanning line time for one line. The pulse of energizing current is configured to apply thermal energy that causes the thermal color developing layer to develop color, to the plurality of heating elements. The application period correction unit is configured to correct a length of the first application period, which is set by the pulse setting unit, based on an image to be printed. The print speed determination unit is configured to determine print speed to be applied in printing the whole image at a constant speed, by extending the scanning line time so as to contain a maximum length of the first application period that has been corrected by the application period correction unit.