Inkjet printers with elongate chambers, nozzles and heaters
View Patent ↗An inkjet printhead with an array of nozzles arranged in a series of rows, each nozzle having an ejection aperture, a chamber for holding printing fluid and a heater element for generating a vapor bubble in the printing fluid contained by the chamber to eject a drop of the printing fluid through the ejection aperture. The nozzle, the heater element and the chamber are all elongate structures that have a long dimension that exceeds their other dimensions respectively. The respective long dimensions of the nozzle, the heater element and the chambers are parallel and extend normal to the row direction. To increase the nozzle density of the array, each of the nozzle components—the chamber, the ejection aperture and the heater element are configured as elongate structures that are all aligned transverse to the direction of the row. This raises the nozzle pitch, or nozzle per inch (npi), of the row while allowing the chamber volume and therefore drop volume to stay large enough for a suitable color density. It also avoids the need to spread the over a large distance in the paper feed direction (in the case of pagewidth printers) or in the scanning direction (in the case of scanning printheads).
1. An inkjet printhead comprising:
an array of nozzles arranged in a series of rows, each nozzle having an ejection aperture, a chamber for holding printing fluid and a heater element for generating a vapor bubble in the printing fluid contained by the chamber to eject a drop of the printing fluid through the ejection aperture; wherein,
the nozzle, the heater element and the chamber are all elongate structures that have a long dimension that exceeds their other dimensions respectively; and,
the respective long dimensions of the nozzle, the heater element and the chambers are parallel and extend normal to the row direction wherein the array of nozzles is formed on an underlying substrate extending parallel to the roof layer and the chamber is partially defined by a sidewall extending between the roof layer and the substrate, the side wall being shaped such that its interior surface is at least partially elliptical.
2. An inkjet printhead according to claim 1 wherein each of the rows in the array is offset with respect to it adjacent row such that none of the long dimensions of the nozzles in one row are not collinear with any of the long dimensions of the adjacent row.
3. An inkjet printhead according to claim 1 wherein the printhead is a pagewidth printhead for printing to a media substrate fed past the printhead in a media feed direction such that the long dimensions of the nozzles are parallel with the media feed direction.
4. An inkjet printhead according to claim 1 wherein the long dimensions of the nozzles in every second are in registration.
5. An inkjet printhead according to claim 1 wherein the ejection apertures for all the nozzles is formed in a planar roof layer that partially defines the chamber, the roof layer having an exterior surface that is flat with the exception of the ejection apertures.
6. An inkjet printhead according to claim 1 wherein the sidewall is elliptical except for an inlet opening for the printing fluid.
7. An inkjet printhead according to claim 6 wherein the minor axes of the nozzles in one of the rows partially overlaps with the minor axes of the nozzles in the adjacent row with respect to the media feed direction.
8. An inkjet printhead according to claim 7 wherein the ejection apertures are elliptical.
9. An inkjet printhead according to claim 8 wherein the heater elements are beams suspended between their respective electrodes such that, during use, they are immersed in the printing fluid.
10. An inkjet printhead according to claim 6 wherein the vapor bubble generated by the heater element is approximately elliptical in a cross section parallel to the ejection aperture.
11. An inkjet printhead according to claim 8 further comprising a supply channel adjacent the array extending parallel to the rows.
12. An inkjet printhead according to claim 11 wherein the array of nozzles is a first array of nozzles and a second array of nozzles is formed on the other side of the supply channel, the second array being a mirror image of the first array but offset with respect to the first array such that none of the major axes of the ejection apertures in the first array are collinear with any of the major axes of the second array.
13. An inkjet printhead according to claim 12 wherein the major axes of the ejection apertures in the first array are offset from the major axes of the ejection apertures in the second array in a direction transverse to the media feed direction by less than 20 microns.
14. An inkjet printhead according to claim 13 wherein the offset is approximately 8 microns.
15. An inkjet printhead according to claim 1 wherein the printhead has a nozzle pitch in the direction transverse to the direction of media feed greater than 1600 npi.
16. An inkjet printhead according to claim 1 wherein the substrate is less than 3 mm wide in the direction of media feed.