Head Unit Substrate Segmentation for Ink Pressure Uniformity
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Solution Overview
Problem
High-speed and high-accuracy printing demands, characterized by increased nozzle density and number, lead to variations in ink pressure and challenges in supplying sufficient electric power to piezoelectric elements in existing head units.
Innovation Solution
A head unit design featuring multiple substrates and flexible wiring substrates that branch and transfer signals to reduce current flow, ensuring efficient power supply and minimizing ink pressure variations, while also positioning substrates to widen ink flow passages and protect wiring from ink adherence and noise interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of nozzles and nozzle density are increased to achieve high-speed and high-accuracy printing, then printing speed and accuracy are improved, but ink pressure variations occur and sufficient electric power cannot be supplied to all piezoelectric elements
Solution Approach 1:
The head unit is divided into multiple independent driving modules (first driving module and second driving module), each with its own piezoelectric elements and nozzles. This segmentation allows for better distribution of ink supply pathways and electrical connections, reducing pressure variations and improving power supply reliability across the high-density nozzle array.
2Productivity
If the number of nozzles and nozzle density are increased to achieve high-speed and high-accuracy printing, then printing speed and accuracy are improved, but sufficient electric power cannot be supplied to all piezoelectric elements
Solution Approach 1:
The electrical system is segmented into multiple independent circuits through separate driving modules. Each module has dedicated power supply pathways, allowing sufficient current to reach each piezoelectric element despite the high total number of nozzles (600 or more).
Solution Approach 2:
Multiple substrates are arranged in the thickness direction (stacked configuration), creating three-dimensional power distribution. This vertical arrangement allows power to be supplied from multiple directions, ensuring adequate electrical power reaches all piezoelectric elements even in high-density configurations.
3Power
If multiple substrates are stacked to reduce current flow and improve power distribution, then electric power supply is improved, but device complexity increases
Solution Approach 1:
Each substrate serves multiple functions: providing mechanical support for piezoelectric elements, establishing electrical connections through terminals and wiring substrates, and defining ink flow passages. This multi-functionality reduces the need for additional components, offsetting the complexity of the stacked configuration.
4Reliability
If substrates are positioned to widen ink flow passages, then ink pressure uniformity is improved, but the space required for substrate arrangement increases
Solution Approach 1:
The ink flow passages are arranged in the thickness direction between stacked substrates, utilizing the vertical dimension rather than expanding only in the horizontal plane. This allows widened passages for improved pressure uniformity while maintaining a compact overall head unit volume.
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 design enhances discharge accuracy and reduces variations in ink pressure, enabling reliable operation of high-density nozzle arrays with improved power distribution and noise protection.
Implementation Method 1
each of the piezoelectric elements is driven according to a driving signal, and accordingly, a predetermined amount of liquid is discharged from the nozzles at a predetermined timing
Data Source
AI summary
There is provided a head unit including: a first substrate including a first surface provided with a first terminal and a second surface provided with a second terminal; a second substrate including a third surface provided with a third terminal; a first flexible wiring substrate that connects the first terminal and the third terminal to each other; a first driving module that is electrically connected to the second substrate; a third substrate including a fourth surface provided with a fourth terminal; a second flexible wiring substrate that connects the second terminal and the fourth terminal to each other; a second driving module that is electrically connected to the third substrate; and a liquid flow passage through which the liquid is supplied to the first driving module and the second driving module, in which the liquid flow passage is positioned between the second substrate and the third substrate.