KNN Piezoelectric Droplet Head Multi-Path Optimization
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Solution Overview
Problem
The use of potassium sodium niobate (KNN)-based materials in piezo-type droplet discharge heads results in smaller droplet discharge amounts and higher temperature dependence, leading to potential image quality deterioration and reduced head life due to increased driving frequency.
Innovation Solution
A droplet discharge head that employs a piezoelectric element with a perovskite-type composite oxide containing potassium, sodium, and niobium, where the number of paths in multi-path recording, the piezoelectric constant d31, and the sodium molar fraction ratio satisfy a specific relationship, optimizing image quality and head life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If KNN-based material is used as piezoelectric material to reduce lead content, then environmental load is reduced, but displacement amount during voltage application becomes smaller resulting in small droplet discharge amount
Solution Approach 1:
The patent applies parameter changes by precisely controlling the compositional parameters of the KNN-based piezoelectric material. Specifically, it adjusts the molar ratios of potassium, sodium, and niobium elements within defined ranges (0.95≤x≤1.05, 0.05≤y≤0.15, 0.85≤z≤0.95) to optimize the piezoelectric properties. This enables the material to achieve sufficient displacement amount while maintaining its non-lead composition, thus resolving the contradiction between environmental friendliness and droplet discharge performance
Solution Approach 2:
The patent uses composite materials by creating a multi-element KNN-based piezoelectric material with specific compositional ratios. The material combines potassium, sodium, and niobium in optimized proportions, forming a composite structure that enhances piezoelectric characteristics. This composite approach allows the material to overcome the limitations of simple KNN, achieving both environmental compatibility and adequate droplet discharge amount
2Productivity
If driving frequency is increased to achieve desired discharge amount, then productivity is improved, but temperature rise causes deterioration of image quality and shortening of head life
Solution Approach 1:
The patent changes the material parameters of the piezoelectric element to achieve higher displacement amount at lower driving frequencies. By optimizing the compositional parameters (x, y, z ratios) of the KNN-based material, the system can maintain adequate droplet discharge performance while operating at reduced frequencies, thereby preventing temperature rise and its associated problems with image quality and head life
3Duration of action of stationary object
If multi-path recording is performed to reduce driving frequency, then head life is extended, but image quality may deteriorate without proper optimization of number of paths and piezoelectric characteristics
Solution Approach 1:
The patent optimizes the parameters of the piezoelectric material to work effectively with multi-path recording. By adjusting the compositional parameters (x, y, z) to specific ranges, the material achieves sufficient displacement amount that allows using a smaller number of paths (n=2 or 3) while maintaining both head life extension and good image quality. This parameter optimization ensures that multi-path recording does not compromise printing quality
Solution Approach 2:
The patent establishes a feedback relationship between the piezoelectric material characteristics and the multi-path recording parameters. The optimized material properties provide sufficient displacement to determine the appropriate number of paths needed, creating a balanced system where head life is extended through multi-path recording while image quality is maintained through proper material-parameter matching
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 optimized configuration achieves good image quality and extended life of the droplet discharge head by balancing the number of paths, piezoelectric characteristics, and sodium molar fraction ratio, preventing discharge failures and temperature-related issues.
Implementation Method 1
a piezoelectric element includes a first electrode, a second electrode, and a piezoelectric layer disposed between the first electrode and the second electrode
Data Source
AI summary
A droplet discharging head executes multi-path recording in which dot recording in one main scanning line is completed by n main scans when n is an integer of 2 or more. The droplet discharging head includes: a plurality of nozzles configured to discharge a liquid as droplets; a pressure chamber defining substrate defining a pressure chamber communicating with the nozzles; a piezoelectric element including a first electrode, a second electrode, and a piezoelectric layer containing a perovskite-type composite oxide containing K, Na, and Nb as a main component; and a vibration plate forming a part of a wall surface of the pressure chamber and configured to vibrate by driving of the piezoelectric element. The number of paths n in the multi-path recording, a piezoelectric constant d31 [m/v] of the piezoelectric element, and a ratio x of a Na molar fraction to a total value of a K molar fraction and the Na molar fraction in the piezoelectric layer satisfy a relationship represented by a formula (1).