Recently, inkjet-printing industry demands high-speed and single-pass printing that requires simultaneous jetting of a large number of ejectors. As a result, the jetting reliability has become an important issue in most industrial inkjet-printing applications. To ensure the jetting reliability, a real-time monitoring of the jetting status is needed. Since the monitoring process should not interrupt the printing process, the monitoring time for all of the nozzles should be less than 1 second. For this purpose, the authors developed two module prototypes to monitor the commercial inkjet heads with 1024 nozzles: (1) a head driver with an internal self-sensing capability; (2) an external monitoring module that can be used for third-party drivers. To deal with a large number of nozzles effectively, the authors are proposing a parallel sensing scheme that can be used to monitor multi-head jetting. Lastly, the authors verified our monitoring scheme by using a drop visualization system for a comparison of the monitoring results with the droplet jetting images. © 2017 Society for Imaging Science and Technology.

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As the application of the direct printing method becomes diversified, printing on substrates with non-flat surfaces is increasingly required. However, printing on three-dimensional surfaces suffers from a number of difficulties, which include ink flow due to gravity, and the connection of print lines over sharp edges. This study presents an effective way to print a fine pattern (~ 30 μm) on three different faces with sharp edge boundaries. The method uses a deflectable and stretchable jet stream of conductive ink, which is produced by near-field electrospinning (NFES) technique. Due to added polymer in the ink, the jet stream from the nozzle is less likely to be disconnected, even when it is deposited over sharp edges of objects. As a practical industrial application, we demonstrate that the method can be effectively used for recent display applications, which require the connection of electrical signal and power on both sides of the glass. When the total length of printed lines along the ‘Π’ shaped glass surfaces was 1.2 mm, we could achieve the average resistance of 0.84 Ω.

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