Ink-jet Head COF FPC Segmentation Cost Reduction
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Solution Overview
Problem
The high cost of manufacturing ink-jet heads is increased due to the requirement of long, expensive COF (Chip On Film) wires to connect piezoelectric actuators to printed boards.
Innovation Solution
An ink-jet head design that uses a combination of a piezoelectric actuator, a driver IC, and a printed board connected via a first wire member (COF) and a second wire member (FPC) with exposed contacts and a circuit component, where the FPC is connected to the COF to shorten the COF length and reduce manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a long COF is used to connect the piezoelectric actuator to the printed board, then the connection is achieved, but the manufacturing cost increases
Solution Approach 1:
The wire member is divided into two segments: a first wire member (COF) connected to the piezoelectric actuator and containing the driver IC, and a second wire member (FPC) connected to the printed board. This segmentation allows the expensive COF to be shortened while maintaining functional connectivity through the FPC extension.
Solution Approach 2:
The first wire member (COF) acts as an intermediary between the piezoelectric actuator and the second wire member (FPC). By placing the driver IC on the COF and connecting it to both the actuator and FPC, the system enables signal transmission without requiring a single long COF, thus reducing cost.
2Ease of manufacture
If the COF is shortened to reduce cost, then manufacturing cost decreases, but connection reliability may be affected
Solution Approach 1:
The first wire member (COF) and second wire member (FPC) are electrically connected through corresponding contacts to form a unified signal transmission path. This merging ensures reliable signal transmission from the printed board through the FPC and COF to the piezoelectric actuator, maintaining connection reliability while using a shorter COF.
3Ease of operation
If signal wires are exposed for connection, then connection flexibility increases, but noise susceptibility increases
Solution Approach 1:
An insulating tape is applied to cover the exposed signal wires and circuit components at the connection point. This simple, inexpensive protective layer prevents noise interference and short circuits while maintaining the flexibility of exposed contacts for connection, effectively addressing the noise susceptibility issue.
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 reduces manufacturing costs by using an inexpensive FPC connected to an expensive COF, allowing for a shorter COF length and stable ink ejection performance while minimizing noise and variation in ink ejection.
Implementation Method 1
a piezoelectric actuator applies pressure to ink contained in a pressure chamber that communicates with an ink ejection port, so that ink is ejected from the ink ejection port
Data Source
AI summary
An ink-jet head includes a passage unit, a piezoelectric actuator, a first wire member, and a second wire member. The first wire member is connected to the piezoelectric actuator and has a driver IC. The second wire member is connected to the first wire member and has wires. The first wire member includes signal wires, the driver IC, a circuit component that electrically connects two or more of the signal wires, and first contacts connected to the respective signal wires. The second wire member includes the wires, and second contacts connected to the respective wires. The corresponding first and second contacts are connected to each other at and around a portion where the first wire member and the second wire member overlap. The circuit component is disposed near any of the first contacts. All of the first and second contacts, and the circuit component are covered with an insulating tape.