Thermal Head Energy Control for High-Resolution Dot Area Gradation
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Solution Overview
Problem
Current image forming methods using thermal transfer ink ribbons face challenges in achieving high-resolution, high-quality multi-gradation images due to limitations in gray-scale representation, particularly with methods like dither and error diffusion, and the requirement for a porous-surface layer on recording media, which restricts the application to specific media types and leads to unstable dot formation and sensitivity issues.
Innovation Solution
The method involves comparing gray-scale values of pixels with a threshold value pattern and a gray-scale conversion table to control energy application to the thermal head, allowing for dot area gradation and multi-gradation representation, enabling high-resolution and high-quality image formation on various media types by combining area and dot modulated patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If dither method is used to represent multi-gradation, then gray-scale values can be represented, but dither matrix becomes large and resolution becomes lowered
Solution Approach 1:
The patent changes the parameter of dot area size to represent gray-scale values instead of using dither patterns. By controlling the area of each dot within a pixel, the system achieves multi-gradation without increasing the matrix size or compromising resolution. This allows high-resolution images to be formed while representing multiple gray-scale values.
2Quantity of substance
If error diffusion method is used for line thermal printer, then images can be formed, but accumulated heat has great effect on thermal head
Solution Approach 1:
The patent implements periodic action by controlling the thermal head heating in a structured sequence based on the dot pattern. By organizing the heating process according to the calculated dot positions and areas, the system manages heat accumulation and prevents excessive temperature rise in the thermal head while maintaining image formation capability.
3Manufacturing precision
If dot area gradation method is used, then multi-gradation images with higher resolution can be obtained, but method is restricted to only special porous recording medium
Solution Approach 1:
The patent achieves universality by developing a dot area gradation method that can be applied to various recording media types. The method controls the thermal head to form dots with different areas based on gray-scale values, making it compatible with both porous and non-porous media. This allows the same method to work across different media without requiring medium-specific adjustments.
4Adaptability or versatility
If intermediate transfer medium is used, then images can be formed on various recording media, but dots are formed with weak printing energy and unstable spots occur
Solution Approach 1:
The patent changes the parameter of printing energy distribution by controlling the thermal head heating intensity based on dot area requirements. By adjusting the energy applied to each dot according to its size and position, the system achieves stable dot formation while maintaining compatibility with various recording media. This prevents weak printing energy and unstable spots.
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 enables the formation of high-resolution, high-quality multi-gradation images on diverse recording media by stabilizing dot formation and reducing sensitivity issues, while allowing for flexible application across different media types.
Implementation Method 1
forms images by thermally transferring, for example, ink of a thermal transfer ink ribbon onto a medium to be recorded
Implementation Method 2
then by recording the images by transferring the images onto the medium using heat and pressure
Data Source
AI summary
An image with sufficient gray-scale representation and high resolution is formed on a medium to be recorded, such as an intermediate transfer body, using a thermal printer employing thermal transfer ink. When thermal transfer ink of a thermal transfer ink ribbon 18 is thermally transferred onto an intermediate transfer body 12 by a thermal head 14, gray-scale values of pixels of a filter image having a threshold value pattern used to determine whether each of a plurality of pixels of an original image is an object to be printed, based on gray-scale values of the pixels, are compared with the gray-scale values of the pixels of the original image, and then the gray-scale values of the pixels of the original image are converted based on the result of the comparison. A gray-scale conversion table in which energy applied to the pixels at the time of printing is prescribed corresponding to the gray-scale values of the pixels is compared with the converted gray-scale values of the pixels of the original image, and the converted gray-scale values of the pixels of the original image are further converted on the basis of the result of the comparison. In addition, the application of a current to the thermal head 14 is controlled according to the converted gray-scale values of the pixels of the original image.