Thermal Print Head Convex Substrate for Foreign Object Inhibition
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Solution Overview
Problem
Foreign objects such as scraps of paper or thermal print head surface layers can attach to the heat generating portions of thermal print heads, obstructing heat transfer and degrading printing quality during the conveyance of print media.
Innovation Solution
A thermal print head design featuring a substrate with a convex portion having a flat surface and a curved convex surface, where the heat generating portions are arranged on the flat surface, and a method of fabricating this print head using monocrystalline semiconductor substrates with specific etching processes to form the convex structure, which reduces the likelihood of foreign object attachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the heat generating portions are arranged on a flat surface, then the manufacturing process is simple, but foreign objects can attach to the heat generating portions obstructing heat transfer
Solution Approach 1:
The patent applies curvature by forming a convex portion on the substrate surface where the heat generating portions are arranged. This convex shape prevents foreign objects from attaching to the heat generating portions, as the curved surface does not provide flat areas for debris to settle. The convex portion maintains reliable heat transfer to the print medium while avoiding the foreign object attachment problem that would occur on a flat surface.
2Reliability
If the convex portion has only a flat surface, then foreign objects are less likely to attach, but friction and wear increase during print medium conveyance
Solution Approach 1:
The patent combines a flat top surface with curved side surfaces on the convex portion. The flat top surface prevents foreign object attachment and ensures reliable heat transfer, while the curved side surfaces reduce friction and wear during print medium conveyance by providing a smooth transition that guides the print medium without creating sharp edges or high-stress contact points.
3Object-affected harmful factors
If a curved surface is added to the convex portion, then friction and wear are reduced, but the manufacturing process becomes more complex
Solution Approach 1:
The patent controls the curvature parameters of the convex portion to optimize both friction reduction and manufacturability. By carefully selecting the radius of curvature and the angles of the curved surfaces, the design achieves reduced friction and wear while maintaining compatibility with standard semiconductor manufacturing processes, thus balancing manufacturing complexity with performance benefits.
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
The design effectively inhibits the generation of foreign objects and enhances printing quality by reducing friction and wear, ensuring consistent heat transfer and improved print media conveyance.
Implementation Method 1
a resistor layer, including a plurality of heat generating portions arranged in a main scanning direction
Implementation Method 2
The convex portion includes a flat first surface on which each of the plurality of heat generating portions is disposed, and a first curved convex surface connected to the first surface
Data Source
AI summary
The present disclosure provides a thermal print head. The thermal print head includes a substrate, having a main surface facing one side in a thickness direction; a resistor layer, including a plurality of heat generating portions arranged in a main scanning direction and supported by the substrate; and a wiring layer, forming a power path to the plurality of heat generating portions and supported by the substrate. The substrate includes a convex portion protruding from the main surface and extending along the main scanning direction. The convex portion includes: a flat first surface on which each of the plurality of heat generating portions is disposed; and a first curved convex surface connected to the first surface.