Grooved Heater Substrate for Crack Suppression
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Solution Overview
Problem
The manufacturing process of heaters for image forming apparatuses faces challenges in maintaining mechanical and thermal strength while minimizing substrate thickness, which leads to increased micro cracking and decreased productivity due to additional processing steps for forming glass films on end surfaces.
Innovation Solution
A heater design featuring a substrate with a heat-resistant insulating material, a heating resistor, and a conductor covered by a protection film, with strategically formed groove portions along the outer periphery, where the coefficient A (100×D/(T×P)) is maintained between 0.4 and 0.9 to control substrate thickness, depth, and pitch, preventing excessive cracking and maintaining mechanical and thermal strength without additional processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the thickness of the substrate is decreased to increase thermal efficiency, then thermal efficiency is improved, but mechanical strength and thermal shock strength decrease and micro cracking becomes more likely
Solution Approach 1:
The patent applies local quality by forming groove portions only at specific locations (end surfaces) of the substrate rather than uniformly throughout. These localized grooves create stress concentration points that prevent crack propagation, allowing the substrate to maintain high thermal efficiency with reduced thickness while preventing catastrophic failure through localized structural modification.
Solution Approach 2:
The groove portions are formed in advance during the manufacturing process before the substrate is put into service. This preliminary action of creating controlled stress concentration zones prevents future crack propagation, allowing the thin substrate to maintain its strength without requiring additional protective coatings or post-processing steps.
2Strength
If a glass film is formed on the end surface to suppress decrease in mechanical strength, then mechanical strength is improved, but productivity decreases due to additional processing process
Solution Approach 1:
The groove portions are formed using the same laser scribing process that is already used for creating split lines during manufacturing. This self-service approach means the strength-enhancing feature is created as a byproduct of the existing manufacturing process, eliminating the need for separate glass film formation steps and maintaining high productivity.
Solution Approach 2:
The patent merges the function of creating split lines with the function of enhancing mechanical strength by using the same laser scribing process to form both the split lines and the groove portions. This consolidation of functions eliminates additional processing steps while achieving both manufacturing objectives.
3Strength
If groove portions are formed to control cracking, then mechanical strength is improved, but manufacturing complexity increases
Solution Approach 1:
The patent replaces complex mechanical or chemical processes (such as glass film formation or additional coating steps) with a simplified laser scribing process. The same laser that creates split lines also forms the groove portions, substituting a potentially complex multi-step process with a single integrated optical process.
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 effectively suppresses variations in external dimensions, enhances mechanical and thermal strength, and reduces manufacturing costs by eliminating the need for additional processing steps, thereby improving the productivity and reliability of the heater.
Implementation Method 1
groove lines (split line) are formed on a flat plate-shaped base material through groove processing using a laser scribing technique
Implementation Method 2
a ceramic substrate is provided with a heating resistor
Data Source
AI summary
A heater according to an embodiment includes a substrate that is formed of a heat resistant insulating material, a heating resistor that is provided on the substrate, a conductor that is provided on the substrate and that is electrically connected to the heating resistor, and a coating film that covers the heating resistor and the conductor. A plurality of groove portions are arranged on an end surface of the substrate along an outer periphery of the substrate, and a coefficient A=100×D/(T×P) satisfies 0.4≤A≤0.9 where T [μm] is the thickness of the substrate, D [μm] is the depth of the groove portion in a thickness direction of the substrate, and P [μm] is a pitch between the groove portions.