Inkjet Substrate Heater Shielding Logic Noise
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Solution Overview
Problem
Inkjet printheads face challenges in reducing noise interference between heating elements and low-voltage logic signal lines without increasing chip size, as the density of heaters and drive circuits increases, leading to crosstalk noise due to capacitance between traces.
Innovation Solution
The substrate design includes a heating portion positioned between the element row and the signal line, ensuring non-overlap in a direction perpendicular to the face, with the heating portion extending along the GNDH trace area, allowing for efficient arrangement without increasing chip size and reducing noise influence on logic signal lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the density of heaters and drive circuits is increased to improve printing resolution and speed, then productivity is improved, but crosstalk noise between traces increases due to reduced spacing
Solution Approach 1:
A ground trace is introduced as an intermediary element positioned between the heater trace and the logic signal line. This ground trace acts as a shield that intercepts and dissipates electromagnetic interference before it can couple into the logic signal line, thereby reducing crosstalk noise while allowing high-density trace routing
Solution Approach 2:
The shielding structure is applied locally only in the critical region where the heater trace and logic signal line are in close proximity. The ground trace is positioned specifically between these two traces in the area between adjacent color ink supplying ports, providing targeted noise protection without requiring global redesign of the entire substrate
2Reliability
If a subheater is added to control substrate temperature for stable printing, then reliability is improved, but noise interference with logic signal lines increases due to proximity
Solution Approach 1:
A ground trace is positioned between the subheater and the logic signal line to serve as an electromagnetic shield. This ground trace intercepts noise generated by the subheater's operation and prevents it from coupling into the sensitive logic signal line, enabling the subheater to be placed close to logic circuits without causing interference
Solution Approach 2:
The solution utilizes the vertical dimension by implementing a multilayer substrate structure. The ground trace is placed in an intermediate layer between the subheater (in one layer) and the logic signal line (in another layer), providing three-dimensional separation and shielding that reduces noise coupling while maintaining compact packaging
3Device complexity
If the chip size is increased to accommodate more heaters and drive circuits, then device complexity is reduced, but the area of the printhead increases
Solution Approach 1:
The patent implements a multilayer substrate structure that utilizes the vertical dimension for circuit routing. Different functional elements (heaters, drive circuits, logic circuits, ground traces) are distributed across multiple layers, allowing high-density integration without increasing the planar footprint of the printhead
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 stable printing operations by minimizing noise impact on low-voltage logic signal lines, maintaining printing stability without enlarging the chip size, by strategically placing the subheater on the GNDH trace area and separating it from logic signal lines.
Implementation Method 1
a heating portion configured to generate heat used to heat the substrate
Implementation Method 2
an element row including a plurality of elements that are provided in a row, where each of the elements generates energy used to eject a liquid
Data Source
AI summary
A liquid ejection substrate used to eject a liquid includes a substrate having an element row including a plurality of elements provided in a row, where each of the elements generates energy, drive circuits that drive and control the elements, a signal line that is shared by and connected to the drive circuits, the signal line being provided along the element row, and a heating portion generating heat used to heat the substrate, wherein the heating portion is provided so that the heating portion does not overlap the signal line with reference to a direction perpendicular to a face of the substrate.