Print head for printing a suspension fluid comprising particles, printing apparatus and method

Patent metadata

Field	Value
Publication number	US-10160207-B2
Application number	US-201515522129-A
Country	US
Kind code	B2
Filing date	Oct 29, 2015
Priority date	Oct 29, 2014
Publication date	Dec 25, 2018
Grant date	Dec 25, 2018

Abstract

The invention is directed at a print head for printing a suspension fluid. The print head comprises a nozzle having one or more nozzle outlets for allowing the suspension fluid to be ejected from the nozzle, a flow path including a supply channel for supplying the suspension fluid to the one or more nozzle outlets, and a supply pump for establishing a flow within the flow path. The nozzle further comprises an actuator for imparting pressure fluctuations on the suspension fluid at the one or more nozzle outlets for generating a stream of droplets therefrom. The flow path further comprises a shear section for locally increasing the shear rate at least at a location in the flow path upstream of the one or more nozzle outlets. The flow path further includes a return channel for allowing excess fluid not ejected from the nozzle to flow away from the one or more nozzle outlets. The shear section is configured to locally increase the shear rate to be larger than a shear rate obtained near at least one of the one or more nozzle outlets. The invention is further directed at a printing apparatus, a method of printing, and a method of manufacturing a print head.

First claim

The invention claimed is:

1. Print head for printing a suspension fluid comprising particles, the print head comprising a nozzle having one or more nozzle outlets for allowing the suspension fluid to be ejected from the nozzle, a flow path including a supply channel for supplying the suspension fluid to the one or more nozzle outlets, and a supply pump for establishing a flow within the flow path, wherein the nozzle further comprises an actuator for imparting pressure fluctuations on the suspension fluid at the one or more nozzle outlets for generating one or more droplets therefrom,
wherein the flow path further comprises a shear section for locally increasing the shear rate at least at a location in the flow path upstream of the one or more nozzle outlets, and a return channel for allowing excess fluid not ejected from the nozzle to flow away from the one or more nozzle outlets, wherein the shear section is configured to locally increase the shear rate for imposing a shear force on said particles which is larger than an attractive force between said particles in a particle agglomeration, wherein at least one of the one or more nozzle outlets is located in a wall of a branch channel extending from the supply channel.

2. Print head according to claim 1 , wherein the shear section comprises at least one element of a group comprising: a flow constriction; a channel reduction of the supply channel, the channel reduction reducing at least one dimension of the supply channel; a structure present in said supply channel, such as a rim, wall, or protrusion; a bend in the supply channel.

3. Print head according to claim 1 , wherein at least one of the one or more nozzle outlets is located in a wall of the supply channel, and wherein the supply channel is connected to the return channel.

4. Print head according to claim 1 , wherein at least one of the one or more nozzle outlets is located in a nozzle chamber which is connected to the supply channel for receiving the suspension fluid, the nozzle chamber comprising the actuator for imparting the pressure fluctuations.

5. Print head according to claim 4 , wherein the nozzle chamber is connected to the supply channel via a branch channel extending from the supply channel, the nozzle chamber being sized or shaped for imparting said pressure fluctuations.

6. Print head according to claim 1 , wherein the branch channel connecting the one or more nozzle outlets to the supply channel extends from an inner bend of a bended portion of the supply channel.

7. Print head according to claim 4 , wherein the nozzle chamber is arranged between an outlet portion of the supply channel and an inlet portion of the return channel.

8. Print head according to claim 7 , wherein the nozzle chamber is shaped having a broad central section and narrow end sections, wherein each one of the outlet portion of the supply channel and the inlet portion of the return channel is located in a respective end section of the nozzle chamber.

9. Print head according to claim 8 , wherein multiple of the one or more nozzle outlets are located distributed across the width of the central section.

10. Print head according to claim 1 , further comprising a return pump cooperating with the supply pump for controlling a volumetric flow rate ejected from the one or more nozzle outlets.

11. Print head according to claim 1 , further comprising a pressure regulator unit downstream of the nozzle chamber outlet cooperating with the supply pump for controlling a pressure in the nozzle near the one or more nozzle outlets.

12. Printing apparatus for printing a suspension fluid, the apparatus comprising a print head according to claim 1 , wherein the supply channel of the flow path is connected to a fluid container for receiving the suspension fluid, and wherein the return channel is connected to the fluid container for releasing therein the excess suspension fluid.

13. Method of printing a suspension fluid comprising particles using a print head, the print head comprising a nozzle having one or more nozzle outlets, a supply pump, and a flow path comprising a supply channel, the method comprising:
supplying, through the supply channel, the suspension fluid to the one or more nozzle outlets, using the supply pump for establishing a flow through the supply channel;
ejecting, by the nozzle, the suspension fluid from the one or more nozzle outlets, while simultaneously imparting, by an actuator comprised by the nozzle, pressure fluctuations on the suspension fluid at the one or more nozzle outlets for generating one or more droplets therefrom,
locally increasing the shear rate in the supply channel upstream of the one or more nozzle outlets using a shear section, wherein the shear rate is increased for imposing a shear force on said particles which is larger than an attractive force between said particles in a particle agglomeration, and
removing from the one or more nozzle outlets excess fluid not ejected from the nozzle using a return channel.

14. Method of manufacturing a print head for printing suspension fluids comprising particles, the method comprising: providing a nozzle having one or more nozzle outlets for allowing the suspension fluid to be ejected from the nozzle; providing a flow path including a supply channel for allowing supply of the suspension fluid to the one or more nozzle outlets; providing a supply pump for enabling to establish a flow within the flow path; and providing an actuator within the nozzle for enabling to impart pressure fluctuations on the suspension fluid at the one or more nozzle outlets for generating one or more droplets therefrom;
wherein the flow path is provided comprising a shear section for enabling local increasing of the shear rate at least at a location in the flow path upstream of the one or more nozzle outlets, the shear section being configured to locally increase the shear rate for imposing a shear force on said particles which is larger than an attractive force between said particles in a particle agglomeration, and wherein the flow path is further provided comprising a return channel for allowing excess fluid not ejected from the nozzle to flow away from the one or more nozzle outlets.

15. Method according to claim 14 , wherein at least one of the one or more nozzle outlets is provided such as to be located in a nozzle chamber which is connected to the supply channel for receiving the suspension fluid, the nozzle chamber comprising the actuator for imparting the pressure fluctuations.

16. Method according to claim 15 , wherein the nozzle chamber is provided such as to be connected to the supply channel via a branch channel extending from the supply channel, the nozzle chamber being sized or shaped for imparting said pressure fluctuations; and
wherein the branch channel connecting the one or more nozzle outlets to the supply channel is provided such as to extend from an inner bend of a bended portion of the supply channel.

17. Method according to claim 15 , wherein the nozzle chamber is provided to arranged between an outlet portion of the supply channel and an inlet portion of the return channel;
wherein the nozzle chamber is shaped having a broad central section and narrow end sections, wherein each one of the outlet portion of the supply channel and the inlet portion of the return channel is located in a respective end section of the nozzle chamber; and
wherein multiple of the one or more nozzle outlets are provided to be located distributed across the width of the central section.

18. Method according to claim 13 , wherein at least on

Assignees

• TNO

Inventors

• Rijfers Andries
• Houben René Jos
• Koldeweij Robin Bernardus Johannes

Classifications

• A23P30/20

  Extruding · CPC title

• B41J2202/12

  with ink circulating through the whole print head · CPC title

• B41J2202/11

  characterised by specific geometrical characteristics · CPC title

• B41J2/14 Primary

  Structure thereof {only for on-demand ink jet heads} · CPC title

• A23V2002/00

  Food compositions, function of food ingredients or processes for food or foodstuffs · CPC title