In a known print head, the print head comprises a surface having arranged therein at least one nozzle. Ink is ejected from the print head through said nozzle. When printing, ink may be spilled on the nozzle surface of the print head. Ink present on the nozzle surface close to a nozzle may have a negative influence on the performance of a print head during jetting of the ink. Therefore, it is important to prevent presence of ink on the nozzle surface close to a nozzle.
It is known to prevent ink to be present close to a nozzle by applying an anti-wetting coating around a nozzle. This prevents the formation of an ink film. Instead, ink that comes into contact with the anti-wetting coating will form a droplet, having a relatively small contact area with the coating. However, absent any driving force, the droplets may stay on the anti-wetting coating. If a droplet is present on the anti-wetting coating near the nozzle, this may still have a negative influence on the jetting performance. Therefore, a driving force is needed to remove ink droplets from the surface of the print head. Moreover, it is necessary to prevent droplets of ink present on the surface to move back to a nozzle.
WO 2008/079878 describes patterns of anti-wetting coating applied on the surface of a fluid ejector. Various patterns, containing anti-wetting coating and uncoated, wetting regions are described. However, no driving force is generated in order to remove the ink further away from the nozzles and additional means are needed to remove the ink. In the cited document, this is done by moving a wiper to and fro at a predetermined distance from the surface.
EP 2 072 261 describes an orifice plate for an ink jet print head, wherein an anti-wetting gradient is created on the surface of the orifice plate and wherein the wettability increases gradually with increasing distance from the edge of the orifice. In this way, a driving force is created for moving droplets of ink away from a nozzle and no wiper is needed to remove the ink. However, because of the shape of the pattern, droplets of ink, especially larger droplets of ink may move back towards the nozzle. Therefore, improvement of the pattern of anti-wetting material around a nozzle is needed still. Moreover, an anti-wetting gradient according to EP 2 072 261 is difficult to apply on a nozzle surface.
It is an object of the invention to provide a print head comprising a pattern of anti-wetting material, wherein the pattern is shaped such that a driving force is created to remove ink from a nozzle.
USPTO Backgrounds
USPTO Backgrounds