Thermal Head Shift for Uniform Image and Protective Layer Quality
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Solution Overview
Problem
The existing thermal transfer methods result in uneven thermal energy distribution due to the parallel arrangement of heat generating elements in thermal heads, leading to irregularities and reduced smoothness and glossiness of the image and protective layers on the transfer receiving material.
Innovation Solution
Shifting the relative positions of the thermal head and the transfer receiving material in a direction parallel to the main scanning direction, with a specific ratio of shift distance to dot pitch, to ensure uniform thermal energy distribution and improve the smoothness and glossiness of the formed image and protective layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a thermal head with parallel heat generating elements is used for thermal transfer, then image formation capability is achieved, but uneven thermal energy distribution occurs causing surface irregularities
Solution Approach 1:
The invention changes the relative position parameter between the thermal head and transfer receiving material by introducing a shift amount q in the main scanning direction. This parameter change compensates for the uneven thermal energy distribution caused by the parallel heat generating elements, ensuring uniform heating across the entire thermal head surface and preventing surface irregularities.
2Manufacturing precision
If a line heater is added to transfer protective layer, then surface smoothness and glossiness improve, but device size and production cost increase
Solution Approach 1:
The invention makes the thermal head perform multiple functions: both image formation and protective layer transfer. By utilizing the existing thermal head's heating capability and adding only a positional shift mechanism, the system eliminates the need for a separate line heater while achieving the same surface quality improvement.
Solution Approach 2:
The invention merges the image formation process and protective layer transfer process into a single operation using the same thermal head. The thermal head simultaneously transfers both the color material layers and the transferable protective layer to the transfer receiving material, reducing device complexity.
3Manufacturing precision
If pressing surface is added to flatten protective layer, then surface smoothness improves, but device complexity increases
Solution Approach 1:
The invention performs preliminary action by shifting the relative position before the protective layer transfer occurs. This preventive measure ensures uniform thermal energy distribution from the start, avoiding the formation of projected portions that would require subsequent pressing to flatten.
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 the smoothness and glossiness of the image and protective layers by adjusting the thermal energy distribution, preventing irregularities and improving the overall quality of the image and protective layers.
Implementation Method 1
applying thermal energy provided by a heat source referred to as a thermal head to the thermal transfer sheet
Implementation Method 2
The thermal head, which is the heat source for carrying out the thermal transfer, usually has a structure in which a plurality of heat generating elements is arranged in parallel
Data Source
Figure 1~3
Figure 4~5
AI summary
[Problem to be solved] The present invention provides a thermal transfer method capable of improving the smoothness and the glossiness of the surfaces of the resulting image and protective layer. [Solution] Provided is a method for forming an image and a protective layer on a transfer receiving material, by thermal transfer. This method is characterized in that it comprises: supplying a thermal transfer sheet between a thermal head of a thermal printer and a platen roller disposed opposite to the thermal head, wherein the thermal transfer sheet comprises a plurality of color material layers and a transferable protective layer which are arranged in a face serial manner, and wherein the thermal head comprises a plurality of heat generating portions which are arranged so as to extend substantially in parallel with each other; transferring the color material layers of the thermal transfer sheet onto the transfer receiving material, by heat of the thermal head, to form an image on the transfer receiving material; transferring the transferable protective layer of the thermal transfer sheet onto the transfer receiving material, by heat of the thermal head, to form a protective layer on the transfer receiving material; and shifting the relative positions of the thermal head and the transfer receiving material with respect to each other, in a direction substantially in parallel with a main scanning direction (the direction in which the heat generating portions are arranged), after transferring the color material layers at least once.