PRINTER WITH GAS BUBBLE OCCLUSION RESISTANT CONDUITS

• US 20090231401A1
• Filed: 03/12/2008
• Published: 09/17/2009
• Est. Priority Date: 03/12/2008
• Status: Active Grant

• Current Assignee: Memjet Technology Ltd. (Memjet Limited)
• Original Assignee: Silverbrook Research Pty Limited
• Inventors: Wang, Miao, Morgan, John Douglas Peter, Silverbrook, Kia, McAuliffe, Patrick John
• Granted Patent: US 8,118,418 B2
• Time in Patent Office: Days
• US Class Current: 347/92
• CPC Class Codes: B41J 2/175 Ink supply systems ; Circuit parts therefor
• CPC Class Codes: B41J 2/185 Ink-collectors; Ink-catchers

Abstract

An inkjet printer with a printhead and a conduit connected to the printhead. The conduit defines a flow path for the printing fluid and has an internal cross section configured such that the surface tension of printing fluid within it favors gas bubble growth along the conduit length over radial bubble growth that would fully occlude the flow path.

Claims

1. An inkjet printer comprising:

a printhead with an array of nozzles for ejecting printing fluid;

a conduit connected to the printhead, the conduit defining a flow path for the printing fluid;

wherein,

the conduit has an internal cross section configured such that the surface tension of the printing fluid favors gas bubble growth along the conduit length over radial bubble growth that would fully occlude the flow path.

2. An inkjet printer according to claim 1 wherein the internal cross section has a first area and the second area adjoining the first area, the first area being defined as an area that will allow radial growth of the gas bubble until it is completely occluded, and second area being defined as an area that will resist radial intrusion of a gas bubble that completely occludes the first area.

3. An inkjet printer according to claim 2 wherein the second area is shaped such that any gas bubble capable of expanding radially from the first area into the second area until the second area is void of printing fluid, would require an internal gas pressure greater than the internal gas pressure of gas bubbles formed in the printing fluid by outgassing.

4. An inkjet printer according to claim 1 wherein the internal cross section is star-shaped.

5. An inkjet printer according to claim 1 wherein the internal cross section is triangular.

6. An inkjet printer according to claim 1 wherein the internal cross section is ‘

T’

-shaped.

7. An inkjet printer according to claim 1 wherein the internal cross section is cross-shaped.

8. An inkjet printer according to claim 1 wherein the internal cross section is ‘

three leaf clover’

-shaped.

9. An inkjet printer according to claim 1 wherein the internal cross section is “

four leaf clover”

-shaped.

10. An inkjet printer according to claim 1 wherein the flow path extends between the printhead and a printing fluid reservoir.

11. An inkjet printer according to claim 10 wherein the printing fluid reservoir is a sump positioned at a lower elevation than the printhead, the sump having a headspace of air above the printing fluid, and an inlet located in the headspace, the conduit being connected to the inlet such that during printer standby periods, the printing fluid in the conduit hanging from the printhead creates negative hydrostatic pressure in the printhead.

12. An inkjet printer comprising:

a printhead with an array of nozzles for ejecting printing fluid;

a conduit connected to the printhead, the conduit defining a flow path for the printing fluid;

wherein,

the conduit has an internal cross section configured such that its dimension in a first direction far exceeds its dimension in the second direction normal to the first direction such that the gas bubble growing within the conduit will break into smaller separate gas bubbles because of Plateau-Rayleigh instability, before the gas bubble can occlude the flow path.

13. An inkjet printer according to claim 12 wherein the cross section of the conduit is an elongate rectangle.

14. An inkjet printer according to claim 12 wherein the cross section of the conduit has several intersecting, elongate rectangle sections.

15. An inkjet printer according to claim 12 wherein the cross section of the conduit is annular such that the radial width of the conduit is far less than the circumference.

16. An inkjet printer according to claim 12 wherein the flow path extends between the printhead and a printing fluid reservoir.

17. An inkjet printer according to claim 16 wherein the printing fluid reservoir is a sump positioned at a lower elevation than the printhead, the sump having a headspace of air above the printing fluid, and an inlet located in the headspace, the conduit being connected to the inlet such that during printer standby periods, the printing fluid in the conduit hanging from the printhead creates negative hydrostatic pressure in the printhead.