Thermal Head Substrate Warpage Compensation via Resin Curing
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Solution Overview
Problem
Existing methods for manufacturing thermal heads face challenges in controlling heat emission due to warpage of heating elements, leading to curved line printing and uneven pressure from the platen roller, especially when the head substrate warps in the opposite direction during heating, making it difficult to maintain straight line printing.
Innovation Solution
A method involving a sealing resin with adjustable curing conditions, such as resin material, coating amount, heating temperature, or time, is used to warp the head substrate in a concave shape when heating elements emit heat, offsetting the convex warpage during curing, ensuring heating elements are aligned straight for printing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If heating elements are bent by a warpage amount of 't' to compensate for platen roller warpage, then uniform pressure can be maintained during printing, but curved lines are printed and heat emission control becomes difficult
Solution Approach 1:
The head substrate is pre-bent in a specific direction during manufacturing to compensate for the platen roller warpage. This preliminary action ensures that when the platen roller operates, the heating elements maintain proper contact pressure while remaining in a straight configuration for accurate printing.
Solution Approach 2:
The warpage amount of the head substrate is precisely controlled and adjusted to match the platen roller warpage characteristics. By changing the bending parameters of the heating elements during manufacturing, the system achieves both uniform pressure and straight line printing capability.
2Length of moving object
If the head substrate is narrow in width, then the device is more compact, but the head substrate warps in the opposite direction (banana warpage) when heating elements emit heat
Solution Approach 1:
The manufacturing process adjusts the bending parameters of the heating elements based on the head substrate width. For narrower substrates, the warpage compensation is specifically tuned to counteract the banana warpage that occurs during operation, maintaining stable performance across different width configurations.
3Area of stationary object
If multiple heating elements are arranged in the longitudinal direction, then printing coverage is improved, but control of heat emission becomes more difficult
Solution Approach 1:
The head substrate is pre-bent during manufacturing to establish proper geometric relationships between multiple heating elements. This preliminary configuration simplifies the control of heat emission by ensuring that all heating elements start in a straight alignment, making it easier to coordinate their operation for accurate printing.
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 controlled heat emission and uniform pressure from the platen roller, enabling high-quality straight line printing even with narrow head substrates, as the warpage conditions are managed to maintain the alignment of heating elements during printing.
Implementation Method 1
the sealing resin shrinks when cured, so that a convex-shaped warpage of the head substrate occurring when the sealing resin is cured is offset by a concave-shaped warpage of the head substrate
Implementation Method 2
the head substrate is partially thermally expanded by the heat of the heating elements which occurs at the time of printing, such that the central portion of the head substrate warps to the direction of arrow B (called 'banana warpage')
Data Source
AI summary
Both ends of a head substrate in a longitudinal direction warp in a direction away from a cross section of a print substrate (in the convex shape) when a sealing resin is cured. A central portion of the head substrate in a longitudinal direction warps in a direction away from the cross section of the print substrate (in the concave shape) when heating elements emit heat. A curing condition when curing the sealing resin is changed corresponding to the concave-shaped warpage occurring when the heating elements emit heat, such that the convex-shaped warpage of the head substrate occurring when the sealing resin is cured is offset by the concave-shaped warpage of the head substrate and thus the heating elements are arranged in a straight line when the heating elements emit heat at the time of printing.