Overlapping Heat Element and Driving Circuit Layout for Printhead Substrate
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Solution Overview
Problem
In inkjet printhead substrates, the heat generated by heat elements for ink foaming inadvertently heats the driving circuits, leading to reduced circuit durability, altered driving characteristics, and potential malfunctions due to uneven heat resistance between the ink and substrate sides.
Innovation Solution
The arrangement of heat elements and driving circuits on the substrate, where the first heat element overlaps at least a part of the second driving circuit when viewed perpendicularly, allows for efficient heat management and reduced substrate size while maintaining circuit reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the heater is arranged immediately above the driving circuit to reduce substrate area, then the substrate size is reduced, but the driving circuit is heated by the heater causing reduced circuit durability and altered driving characteristics
Solution Approach 1:
The patent applies local quality by creating different thermal environments in different regions of the substrate. The region with the heater is designed with higher heat resistance materials or structures, while the driving circuit region is positioned to avoid direct heat exposure. This localized differentiation allows the heater to be placed close to the circuit without uniformly heating the entire circuit area, thus reducing substrate area while protecting circuit durability.
Solution Approach 2:
The patent introduces an intermediary layer or structure between the heater and the driving circuit. This intermediary could be a thermal barrier layer, an insulating structure, or a design configuration that acts as a thermal buffer. The intermediary allows heat to be generated by the heater while preventing direct thermal coupling with the driving circuit, thus enabling compact arrangement without compromising circuit reliability.
2Area of stationary object
If the heater is arranged immediately above the driving circuit to reduce substrate area, then the substrate size is reduced, but the driving characteristics change due to heat influence
Solution Approach 1:
The patent implements local quality by creating spatially differentiated thermal zones. The heater region is optimized for heat generation, while the driving circuit region is positioned or designed to maintain stable thermal conditions. This localized thermal management allows the heater to be close to the circuit for compactness while the driving characteristics remain stable due to the circuit being in a different thermal zone.
Solution Approach 2:
The patent introduces a thermal intermediary structure that mediates between the heater and the driving circuit. This intermediary acts as a thermal buffer that allows the heater to operate at high temperatures while preventing temperature fluctuations from directly affecting the driving circuit. The intermediary could be a thermal barrier, insulating layer, or design configuration that decouples the thermal fields, thus maintaining stable driving characteristics despite compact arrangement.
3Productivity
If heat resistance between ink side and substrate side is balanced, then ink foaming is effective, but the heater heats the substrate immediately below causing circuit issues
Solution Approach 1:
The patent applies local quality by creating different heat resistance characteristics in different regions. The ink side (heater region) is designed with lower heat resistance to allow efficient heat transfer for ink foaming, while the substrate side (circuit region) is designed with higher heat resistance to protect the circuits. This localized differentiation of thermal properties allows effective ink foaming while protecting the circuits from excessive heating.
Solution Approach 2:
The patent changes the heat resistance parameter spatially across the substrate. By varying the heat resistance value from the heater region to the circuit region, the system achieves both effective heat transfer for ink foaming and thermal protection for circuits. This parameter change could be implemented through different material compositions, layer thicknesses, or structural configurations in different regions of the substrate.
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 configuration enables a compact, high-density nozzle design with improved circuit durability and operation reliability, supporting both cost reduction and enhanced image quality in inkjet printing.
Implementation Method 1
a current is applied to the heat elements to generate heat. Ink droplets are discharged by film boiling of ink
Implementation Method 2
Ink droplets are discharged by film boiling of ink
Implementation Method 3
Heater heat for foaming ink under heating is mainly transmitted in a direction of not the ink but a substrate immediately below owing to the balance of a heat resistance between an ink side and a substrate side
Data Source
AI summary
An element substrate comprises: a plurality of heat elements which include a first heat element and a second heat element configured to supply heat to a liquid for printing; and a plurality of driving circuits which include a first driving circuit configured to drive the first heat element and a second driving circuit configured to drive the second heat element, wherein the plurality of heat elements and the plurality of driving circuits are stacked and arranged on the element substrate, and the first heat element is arranged so as to overlap at least a part of the second driving circuit when viewed from a direction perpendicular to the element substrate.