Dual channel jetting apparatus for 2D/3D electrohydrodynamic (EHD) printing

Patent metadata

Field	Value
Publication number	US-11141989-B2
Application number	US-201816476676-A
Country	US
Kind code	B2
Filing date	Feb 8, 2018
Priority date	Feb 9, 2017
Publication date	Oct 12, 2021
Grant date	Oct 12, 2021

Abstract

An electrohydrodynamic (EHD) jet printing apparatus or system may include circulation of printing fluid to minimize or eliminate clogging in a nozzle. An exemplary nozzle comprises at least two ink channels—one allowing flow to a droplet emitting opening and one allowing flow away from the droplet emitting opening—configured for circulating ink. The nozzle may transfer ink to a substrate with an EHD technique involving voltage or current modulation. For example, an electric field may be applied between the nozzle and printing substrate such that the ink meniscus changes shape and releases ink from the tip of the liquid cone. A multi-channel nozzle may take a variety of configurations, including two co-axially aligned capillaries, side-by-side parallel capillaries, or capillaries arranged at an angle with respect to one another but converging at a single point where the conical meniscus is formed.

First claim

What is claimed is:

1. A jetting apparatus for printing, comprising
at least one droplet emitting opening for ejecting a printing fluid; and
at least two channels configured to permit contemporaneous delivery of the printing fluid to the droplet emitting opening and withdrawal of printing fluid from the droplet emitting opening, wherein each of the at least two channels has a longitudinal axis, and wherein the longitudinal axes of the at least two channels are oriented at a 0-90 degree angle relative to one another; and
a flow controller configured to control printing fluid flow in the at least two channels and to continuously circulate or recirculate the printing fluid past the at least one droplet emitting opening, and wherein the printing fluid ejected from the at least one droplet emitting opening has a conical meniscus.

2. The jetting apparatus of claim 1 , wherein the flow controller circulates or recirculates the printing fluid past the droplet emitting opening during ejection of droplets and during time between ejection of droplets.

3. The jetting apparatus of claim 1 , wherein the at least two channels are configured such that the circulation or recirculation past the droplet emitting opening prevents any printing fluid stagnation at the droplet emitting opening.

4. The jetting apparatus of claim 1 , wherein the flow controller is configured such that rates of printing fluid flow delivery and printing fluid flow withdrawal are independently adjustable to be the same or different.

5. The jetting apparatus of claim 1 , wherein the flow controller comprises one or more pumps or pressure regulators.

6. The jetting apparatus of claim 5 , wherein the one or more pumps or pressure regulators consists of a single pump or pressure regulator configured to recirculate printing fluid.

7. The jetting apparatus of claim 5 , wherein the one or more pumps or pressure regulators comprises at least two pumps or pressure regulators, one configured for printing fluid delivery and the other configured for printing fluid withdrawal.

8. The jetting apparatus of claim 1 , wherein the least two channels are tubules or capillaries.

9. The jetting apparatus of claim 1 , wherein the at least two channels comprise three or more channels.

10. The jetting apparatus of claim 1 , wherein the jetting apparatus is a nozzle.

11. The jetting apparatus of claim 10 , wherein the at least two channels of the nozzle are in a co-axial or bypass flow configuration.

12. The jetting apparatus of claim 1 , wherein the jetting apparatus is a printhead with a plurality of nozzles.

13. The jetting apparatus of claim 1 , wherein the at least two channels are configured to permit contemporaneous delivery of printing fluids that are conductive.

14. The jetting apparatus of claim 1 , wherein the at least two channels are configured to permit contemporaneous delivery of printing fluids that contain a metal.

15. The jetting apparatus of claim 1 , wherein the printing is electrohydrodynamic jet printing and further comprising a device for applying a voltage or current to the printing fluid at the at least one droplet emitting opening.

16. A jetting apparatus for drop-on-demand printing, comprising
at least one droplet emitting opening for ejecting a printing fluid; and
at least two channels configured to permit contemporaneous delivery of the printing fluid to the droplet emitting opening and withdrawal of printing fluid from the droplet emitting opening, wherein the at least two channels are coaxial with one another.

17. A method of preventing clogging of a drop-on-demand jetting apparatus, comprising
delivering printing fluid to a droplet emitting opening of a jetting apparatus using at least one channel; and
withdrawing printing fluid from the droplet emitting opening using at least one additional channel, wherein said withdrawing step is performed contemporaneously with said delivering step, and wherein the at least one channel and the at least one additional channel each have a longitudinal axis, and wherein the longitudinal axes of the at least one channel and the at least one additional channel are oriented at a 0-90 degree angle relative to one another; and
controlling printing fluid flow with a flow controller in the at least one channel and the at least one additional channel to continuously circulate or recirculate the printing fluid past the at least one droplet emitting opening, and wherein the printing fluid ejected from the at least one droplet emitting opening has a conical meniscus.

18. The method of claim 17 , wherein controlling performed such that continuously circulating or recirculating printing fluid past the droplet emitting opening occurs during ejection of droplets and during time between ejection of droplets.

19. The method of claim 18 , further comprising independently adjusting rates of printing fluid flow delivery and printing fluid flow withdrawal to be the same or different.

20. The method of claim 17 , wherein the step of controlling is performed such that continuously circulating or recirculating printing fluid prevents any printing fluid stagnation at the droplet emitting opening.

21. The method of claim 17 , wherein the delivering step comprises delivery of a printing fluid that is conductive, and the withdrawing step comprises withdrawal of the printing fluid that is conductive.

22. The method of claim 17 , wherein the delivering step comprises delivery of a printing fluid that contains a metal, and the withdrawing comprises withdrawal of the printing fluid that contains a metal.

23. The method of claim 17 , wherein the jetting apparatus is an electrohydrodynamic jetting apparatus, further comprising the step applying a voltage or current to the printing fluid at the at least one droplet emitting opening.

Assignees

• Univ Virginia Commonwealth

Inventors

• Chen Daren
• Zhao Hong

Classifications

• B41J2/04

  generating single droplets or particles on demand · CPC title

• B05B15/58

  preventing deposits, drying-out or blockage by recirculating the fluid to be sprayed from upstream of the discharge opening back to the supplying means {(B05B1/3093 takes precedence)} · CPC title

• B05B5/0255

  spraying and depositing by electrostatic forces only · CPC title

• B41J2/1714 Primary

  Conditioning of the outside of ink supply systems, e.g. inkjet collector cleaning, ink mist removal (B41J2/08, B41J2/16517, B41J2/18 take precedence) · CPC title

• B41J2/17596 Primary

  Ink pumps, ink valves · CPC title