Advances in technologies for Wide Web Single Pass Printing with piezoelectric Inkjet

Abstract

In the past it has been extremely difficult to attain the required quality and reliability needed to achieve a viable wide array single pass inkjet system to satisfy the needs of the printing industry for label and billing applications. However it is now practical to form such a system by utilizing a combination of several novel technologies.Printed inkjet quality has been achieved in the past by using a very fine pixel array requiring either a high nozzle density across the array or multi-passing techniques to fill in the gaps. The latter not being suitable for single pass applications, the industry has had to stack low nozzle density printheads to synthesize a higher density array. Unrestricted greyscale technology allows for images of apparent binary resolutions of about 1000 DPI to be created from medium resolution arrays. Shared Wall piezoelectric technology allows for the creation of such medium resolution arrays.Reliability is the other critical factor. In the past this has usually been achieved by redundancy or regular maintenance of the printhead to ensure that the nozzles remain primed with an intact meniscus. Again the latter option is not practical for a single pass printer but recirculating the ink at the nozzle (throughflow technology) effectively provides continuous maintenance of the meniscus irrespective of printed duty cycle and so allows for interrupt free operation.Incorporating shared wall operation, greyscale and the throughflow recirculation technologies together in a single printhead can give a physical nozzle density of 360 NPI an apparent binary resolution of nearly 1000 DPI when using 8 greylevels and be virtually maintenance free when printing.