Thermal Transfer Printer Joint Shifting and Gradation Correction
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Solution Overview
Problem
Conventional thermal transfer printers face issues with maintaining transfer density and image quality at joints when printing wide images, as the heat storage temperature of the thermal head affects transfer density, and altering ink color sequences leads to color tone variations and reverse transfer phenomena, resulting in noticeable joints and potential quality deterioration.
Innovation Solution
A thermal transfer printer that shifts the joints of Y, M, and C colors to overlap each other and corrects gradation data using pre-set coefficients in the sub-scanning transfer direction, ensuring consistent transfer density and minimizing joint visibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If divided images are printed to form panoramic pictures, then the image width can be extended, but image quality deteriorates at joint sections
Solution Approach 1:
The image is divided into multiple pieces that are printed separately and then combined. This allows the printer to handle images wider than the ink sheet by processing them in segments, solving the limitation of ink sheet width while enabling panoramic printing capability
Solution Approach 2:
Multiple ink sheets are combined in a nested manner where the end portion of one ink sheet overlaps with the start portion of the next ink sheet. This nesting approach allows continuous wide printing while maintaining image quality through proper overlap handling and transfer sequence management
2Ease of operation
If the transfer sequence of ink colors is altered in overlapping sections, then joint sections can be formed, but color tones change
Solution Approach 1:
Different transfer sequences are applied to different sections of the ink sheet. In non-overlapping sections, the normal transfer sequence (Y-M-C) is used, while in overlapping sections, a reversed sequence is employed. This local differentiation maintains color tone consistency while enabling joint section formation
Solution Approach 2:
The transfer sequence is predetermined and controlled based on the position of the ink sheet. The system预先 determines which sections require reversed transfer sequences to maintain color consistency, and this control is implemented before the actual printing process begins
3Productivity
If the thermal head heat storage temperature varies, then printing can be performed, but transfer density becomes inconsistent
Solution Approach 1:
The system monitors and adjusts the transfer sequence and overlap handling based on the heat storage temperature state of the thermal head. By providing feedback control, the system compensates for temperature variations to maintain consistent transfer density across different printing sections
Solution Approach 2:
The transfer sequence parameter is changed dynamically based on the thermal head state. By switching between normal and reversed transfer sequences, the system adapts to temperature variations and maintains consistent transfer density, ensuring uniform image quality throughout the wide print
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 allows for wide printing with inconspicuous joints by maintaining consistent transfer density and preventing color tone changes, thereby enhancing image quality and reducing the occurrence of reverse transfer issues.
Implementation Method 1
a thermal transfer printer forms a color picture by applying heat on the ink sheet from a thermal head to add printing of the colors onto the same area of the recording paper
Data Source
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AI summary
In a thermal transfer printer for printing a color picture by dividing it into pieces with a prescribed size, an image data converting unit 10 includes a joint shifting unit 10b for shifting a joint of each color between the divided pieces so that the joints of individual colors are not aligned with each other in the sub-scanning transfer direction, and a joint processing unit 10c for transferring the joints of the individual colors, which are shifted by the joint shifting unit, so that the joints overlap each other, and for correcting gradation data in the overlapping portion according to correction coefficients that are set in advance for each line in the sub-scanning transfer direction.