Drop ejection assembly

1. A drop ejector, comprising:

a flow path in which fluid is pressurized to eject drops from a nozzle, the nozzle having an inlet and an outlet, and the outlet being formed in a substantially planar substrate and lying in a plane defined by a surface of the substrate;

a radial channel formed in the substrate on the same surface as the outlet, the radial channel having dimensions configured to and being spaced from the outlet a distance to draw fluid into the space defined by the radial channel, a portion of the radial channel being below the plane defined by the surface of the substrate; and

at least one connecting channel formed in the substrate and extending from the radial channel, the connecting channel being configured to move fluid away from the outlet.

2. The drop ejector of claim 1 wherein the radial channel has a width that is about twice the outlet width or less.

3. The drop ejector of claim 1 wherein the radial channel has a width of about 100 microns or less.

4. The drop ejector of claim 1 wherein a depth of the radial channel is from about 2 micron to about 50 micron.

5. The drop ejector of claim 1 wherein the substrate is a silicon material.

6. The drop ejector of claim 1 wherein the planar substrate includes a plurality of nozzles and radial channels proximate the nozzles.

7. The drop ejector of claim 1 wherein the outlet width is about 200 micron or less.

8. The drop ejector of claim 1 including a piezoelectric actuator.

9. The drop ejector of claim 1 wherein the radial channel is spaced from the outlet by a distance of about 20% of an outlet width or more.

10. The drop ejector of claim 1 further comprising a vacuum source in communication with the connecting channel.

11. The drop ejector of claim 1 further comprising a wicking material in communication with the connecting channel.

12. The drop ejector of claim 1 wherein fluid is drawn into the space defined by the radial channel during jetting.

13. A drop ejector, comprising:

first and second flow paths in which fluid is pressurized to eject drops from first and second nozzles, the nozzles each having an inlet and an outlet, and the outlet being formed in a substantially planar substrate and lying in a plane defined by a surface of the substrate;

first and second radial channels formed in the substrate on the same surface as the outlets, the radial channels having dimensions and being spaced from the outlets a distance configured to draw fluid into the space defined by the radial channels, a portion of the radial channels being below the plane defined by the surface of the substrate; and

first and second connecting channels formed in the substrate and extending from the first and second radial channels, and a third connecting channel connecting the first and second radial channels, the connecting channels being configured to move fluid away from the outlet.

14. The drop ejector of claim 13 wherein the first and second channels are in the shape of a circle.

15. A method of fluid ejection, comprising:

ejecting a drop through a nozzle having an inlet and an outlet formed in a substrate and lying in a plane defined by a surface of the substrate;

positioning a radial channel in the substrate proximate the nozzle opening on the same surface as the outlet;

providing at least one connecting channel in the substrate, the connecting channel extending from the radial channel;

drawing fluid into the radial channel during fluid ejection, the fluid moving from the radial channel into the connecting channel, a portion of the radial channel being below the plane defined by the surface of the substrate.

16. The method of claim 15 wherein the fluid has a surface tension of about 20-50 dynes/cm.

17. The method of claim 15 wherein the fluid has a viscosity of about 1 to 40 centipoise.

18. The method of claim 15 wherein the radial channel is spaced from the outlet by a distance of about 20% of an outlet width or more.

19. The method of claim 15 further comprising providing a vacuum source in communication the connecting channel.

20. The method of claim 15 further comprising providing a wicking material in communication with the connecting channel.

21. The method of claim 15 wherein the fluid is drawn into the radial channel by capillary forces.

22. The method of claim 15 wherein the fluid is drawn into the radial channel by gravity.

23. The method of claim 15 wherein fluid is drawn into the space defined by the radial channel during jetting.