Achieved results so far
It was shown, that image quality increases with the number of base colours used, however, the connection between these values is not linear and additional improvement cannot be achieved over a point. Additional colours, however, requires additional powder nozzles needed to be integrated into the printing head which raises both the costs and the complexity. For this reason, a set of 7 colors has been chosen to be implemented into SPABRINK.
Besides, brightness level investigation has concluded that 4 brightness level per colour should targeted . To achieve the 256 / 32 / 16 colour models automatic colour selection was applied by using the MacOS colour palette. These colours will be fine-tuned after testing them with the current printing technology. Unfortunately, commercially available graphical software is limited in simulating perfect colour schemes, but they can be improved.
As the special physical parameters of the powders cannot be taken into account in simulations, physical tests are crucial for technology optimization. Several parameter will be considered during these test such as the number of base colors, brightness levels or pixel resolution.
Physical tests will reveal how different powders can be mixed in reality and how close are these mixed colours to the simulated ones. Based on the results of the physical tests, the selected colour scheme might be further tuned as well as the number of brightness levels. The aim of this work is to provide superb image quality with the least number of base colours.
As a result of the extensive tests and experiments, it is proven now that powder attachment could be precisely and firmly controlled while allowing easy powder removal with a very low static power consumption.
The relatively large number of tested materials led to the conclusion that the most advantageous powders for SPABRINK application are among the organic materials. Inorganic powders are very stable; they have good electrical properties, but it is extremely difficult to achieve the sufficient colour variations, not speaking about colour gamut. The high melting temperature makes any modification expensive, difficult and limited. The little bit worse printability of these materials probably can be managed with opimization of the print nozzle. Due to the wide range of available colours in the market makes polyester materials the ideal choice.
The design of the rolling mechanism required for the rotation of the electrostatic surface of the prototype has been delivered and mechanical design of the housing is in progress.
Web-based service specification
SPABRINK will also provide an online platform for the end-users to observe and maintain their advertisements via internet. The server will be connected to the SPABRINK endpoint devices and the information provided by these instruments will be processed and collected in a database by the data collector and communication manager application. The web application will provide this transformed data to the user in various formats and it will communicate the SPABRINK Advertisement Board by the communication manager SPABRINK server component.
The development of this system will be started in the last third of the project.
The SPABRINK development is currently at an early stage. Several further aspects may appear that can also cause new claims for the powder and new requirements may come also from the electrostatic fixation technique. These claims can hopefully be fulfilled with some such arrangements as particle size modifications or mixing with additives. To perform these possible tasks successfully we suggest close and frequent consultations with all the RTD participants.