Inkjet Head Substrate Fuse Sections for Short Circuit Protection
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Solution Overview
Problem
Inkjet printing apparatuses face challenges in protecting heating resistors from physical and chemical actions, where the protection layer must balance thickness for durability and fusibility, leading to potential short circuits and reduced resistor density due to space requirements for through holes.
Innovation Solution
A substrate for inkjet heads featuring a base with a heating resistor layer, a thick first protection layer for insulation, and a thin, high-melting-point second protection layer with fuse sections that connect individual sections to a common section, allowing for efficient energy use and rapid fuse blowing in case of damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the upper protection film is made thick to protect heating resistors from physical and chemical actions, then the protection performance is improved, but the energy required to blow the fuse increases and the film cannot be made thin
Solution Approach 1:
The protection film has different thicknesses in different regions: it is thick in the heat action section to provide protection, and thin in the fuse section to enable easy fuse blowing with minimal energy. This local quality variation resolves the contradiction between protection performance and fuse blowability.
2Reliability
If individual through holes are provided to form fuses in another wiring layer, then the fuse function is achieved, but the density of arranged heating resistors becomes low and the substrate area becomes large
Solution Approach 1:
The fuse sections are formed within the upper protection film itself rather than requiring separate through holes in other wiring layers. This merging of the fuse function into the existing protection film structure achieves the fuse function without reducing heating resistor density or increasing substrate area.
3Use of energy by moving object
If the upper protection film is made thin to enable fuse blowing, then the energy required to blow the fuse decreases, but the protection performance deteriorates
Solution Approach 1:
The protection film is thin only in the fuse section where it needs to be blowable, while remaining thick in the heat action section where protection is needed. This localized thinning resolves the contradiction between fuse blowability and protection performance.
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 solution ensures long-lasting inkjet heads with minimal impact on adjacent resistors, as the thin fuse sections can be blown quickly, preventing short circuits and extending the life of the apparatus by concentrating energy and reducing the risk of electrochemical reactions.
Implementation Method 1
a heating resistor layer disposed on the base and including a plurality of heating resistors that generate heat to eject ink
Implementation Method 2
the second protection layer includes a plurality of individual sections provided to correspond to the plurality of heating resistors, a common section connecting the plurality of individual sections, and fuse sections connecting the individual sections and the common section, the fuse sections being formed to be thinner than the individual sections
Data Source
AI summary
There are provided a substrate for an inkjet head, an inkjet head, and an inkjet printing apparatus wherein in a case where current is carried through a protection layer for heating resistors, electrical connection to its periphery is prevented without fail. The substrate for the inkjet head includes a first protection layer disposed to cover a heating resistor layer and having an insulation property and a second protection layer disposed to contact the first protection layer and having conductivity. The second protection layer includes a plurality of individual sections provided to correspond to the plurality of heating resistors, a common section connecting the plurality of individual sections, and fuse sections connecting the individual sections and the common section, the fuse sections being formed to be thinner than the individual sections.