“…In order to solve these issues, ink recirculation systems are often used in industry. Figure 3 shows a simple recirculation system equipped with ink level sensors to maintain the ink supply to the print-head [16]. For the re-circulation and continuous ink supply to the head, more than two reservoirs are commonly used, which are indicated as R1 and R2 in figure 3(a).…”
Section: Ink Supply System For Inkjet Print-headmentioning
confidence: 99%
“…However, these earlier methods were not based on real-time monitoring. Recently, real-time monitoring methods based on piezo self-sensing have been developed and a recent study showed that inkjet print-heads with more than 1000 nozzles can be monitored within a few seconds [16], which could potentially increase the reliability of the inkjet printing process for mass production. Inkjet jetting monitoring issues are discussed in section 2.…”
Direct printing methods have been used as manufacturing tools for printed electronics applications due to their cost effectiveness. In this review, the piezo-driven inkjet is discussed in detail since it is a mature technology and suitable for the production printing of printed electronics. In addition, other printing methods are considered for using higher viscosity ink and for producing smaller printed feature size. Various direct printing methods are compared in terms of jet mechanism, printing algorithm, and their applications. In particular high resolution printing methods using high viscosity inks, such as electrohydrodynamic jet, aerosol jet and micro-plotter are reviewed. To understand the recent status of industrial printing applications, display (liquid crystal display and organic light emitting diode) materials and printing issues are discussed. Finally, a brief overview of nano-particle metal based conductive inks is included because these inks have been widely used for printed electronics applications.
“…In order to solve these issues, ink recirculation systems are often used in industry. Figure 3 shows a simple recirculation system equipped with ink level sensors to maintain the ink supply to the print-head [16]. For the re-circulation and continuous ink supply to the head, more than two reservoirs are commonly used, which are indicated as R1 and R2 in figure 3(a).…”
Section: Ink Supply System For Inkjet Print-headmentioning
confidence: 99%
“…However, these earlier methods were not based on real-time monitoring. Recently, real-time monitoring methods based on piezo self-sensing have been developed and a recent study showed that inkjet print-heads with more than 1000 nozzles can be monitored within a few seconds [16], which could potentially increase the reliability of the inkjet printing process for mass production. Inkjet jetting monitoring issues are discussed in section 2.…”
Direct printing methods have been used as manufacturing tools for printed electronics applications due to their cost effectiveness. In this review, the piezo-driven inkjet is discussed in detail since it is a mature technology and suitable for the production printing of printed electronics. In addition, other printing methods are considered for using higher viscosity ink and for producing smaller printed feature size. Various direct printing methods are compared in terms of jet mechanism, printing algorithm, and their applications. In particular high resolution printing methods using high viscosity inks, such as electrohydrodynamic jet, aerosol jet and micro-plotter are reviewed. To understand the recent status of industrial printing applications, display (liquid crystal display and organic light emitting diode) materials and printing issues are discussed. Finally, a brief overview of nano-particle metal based conductive inks is included because these inks have been widely used for printed electronics applications.
“…In this case, the signal from only one nozzle is sensed at a time for monitoring. A scanning scenario developed in our previous study was used to maximize sensing efficiency 22 . Figure 4 Data acquisition module for self-sensing ( A ) Driving schemes for inkjet, and ( B ) FPGA module for self-sensing signals acquisition.…”
Section: Methodsmentioning
confidence: 99%
“…Hence, fast real-time monitoring is required without mechanical alignment to cameras or sensors. To implement real-time monitoring, self-sensing techniques based on sensing the signals of piezoelectric nozzles have been introduced 22 – 25 .…”
Section: Introductionmentioning
confidence: 99%
“…Because the self-sensing signals are acquired directly from the nozzles when the jetting waveform is applied, it becomes possible to achieve scanning frequencies (speeds) as high as tens of kilohertz. Furthermore, through the implementation of parallel scanning methods 22 , 25 , it is feasible to simultaneously sense multiple nozzles, thereby reducing the monitoring time for thousands of nozzles to mere seconds.…”
One of the advantages of inkjet printing in digital manufacturing is the ability to use multiple nozzles simultaneously to improve the productivity of the processes. However, the use of multiple nozzles makes inkjet status monitoring more difficult. The jetting nozzles must be carefully selected to ensure the quality of printed products, which is challenging for most inkjet processes that use multi-nozzles. In this article, we improved inkjet print head monitoring based on self-sensing signals by using machine learning algorithms. Specifically, supervised machine learning models were used to classify nozzle jetting conditions. For this purpose, the self-sensing signals were acquired, and the feature information was extracted for training. A vision algorithm was developed to label the nozzle status for classification. The trained models showed that the classification accuracy is higher than 99.6% when self-sensing signals are used for monitoring. We also proposed a so-called hybrid monitoring method using trained machine learning models, which divides the feature space into three regions based on predicted jetting probability: certain jetting, certain non-jetting, and doubt regions. Then, the nozzles with uncertain status in the doubt region can be verified by jet visualization to improve the accuracy and efficiency of the monitoring process.
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