A push-mode piezo inkjet equivalent circuit model enhanced by diaphragm displacement measurements

Yasunori Yoshida,Konami Izumi,Shizuo Tokito

doi:10.1063/1.5088384

Abstract

This paper reports on ways to better predict droplet ejection velocity of push-mode piezo inkjet technology by upgrading the conventional equivalent circuit model. Calculation results from the traditional model imply that the driving pulse width conditions without ink ejection only periodically exist in the pull-push piezo driving mode. However, ink ejection is actually observed under any pulse width condition. The displacement of the diaphragm with respect to the piezo element input voltage waveform was measured with a highly accurate capacitive displacement gauge to correct for the difference between the actual measurements and calculations. The equivalent circuit model was then modified so that the measured diaphragm residual oscillations could be expressed. We presumed that an actual inkjet printhead contains an effective spring oscillation component, effective actuator mass, and damping component larger than that used in conventional equivalent circuit model calculations. We demonstrated that the difference between the calculated results and actual measurements could be reduced. Modifications to equivalent circuit model are based on the addition of an effective mechanical spring oscillation component having the same function as the ink chamber compliance, an increase in actuator inertance corresponding to the mass of the actuator, and an effective resistance element expressing a damped oscillation.

Highlights

Since it does not use a plate in its printing process, the inkjet method commonly used for document printing based on digital data, and in recent years it has been used in manufacturing electronic products
The scitation.org/journal/adv push-mode uses a large, thick piezo element that is disadvantageous for miniaturization and has a high nozzle density compared to other methods, but tends to have a high droplet ejection velocity
In the case of TL = 30 μs, the droplet ejection velocity was 2 to 6 m/s, and it had a local minimum around the pulse width of 70 μs

Summary

Introduction

Since it does not use a plate in its printing process, the inkjet method commonly used for document printing based on digital data, and in recent years it has been used in manufacturing electronic products. To fabricate electronic interconnects, metal nanoparticle inks are commonly used, and by performing drying and sintering steps after printing, the solid components are precipitated and fused together that interconnects with high conductivity can be fabricated. The thermal inkjet ejects ink by applying heat, it is difficult to use metal nanoparticle ink in which a solid component is precipitated by heat. Piezo inkjet technology is classified into squeeze mode, bend mode, push mode, sheer mode, or bump mode.. Piezo inkjet technology is classified into squeeze mode, bend mode, push mode, sheer mode, or bump mode.6–10 These are distinguished by the shape and deformation direction of the piezo element in the inkjet printhead. The scitation.org/journal/adv push-mode uses a large, thick piezo element that is disadvantageous for miniaturization and has a high nozzle density compared to other methods, but tends to have a high droplet ejection velocity.

Methods

Results

Conclusion