Pump action refill ink jet printing mechanism

• US 6,416,168 B1
• Filed: 07/10/1998
• Issued: 07/09/2002
• Est. Priority Date: 07/15/1997
• Status: Expired due to Fees

• Current Assignee: Zamtec Limited (Memjet Limited)
• Original Assignee: Silverbrook Research Pty Limited
• Inventors: Silverbrook, Kia
• Primary Examiner(s): Barlow, John
• Assistant Examiner(s): Do, An H.
• Application Number:
  US09/112,778
• Time in Patent Office: 1,460 Days
• Field of Search: 347/44, 347/54, 347/56, 347/84, 347/85, 347/67, 347/94, 347/48
• US Class Current: 347/54
• CPC Class Codes: B41J 2/14427 Structure of ink jet print heads with thermal bend detached actuators
• CPC Class Codes: B41J 2/1628 dry etching
• CPC Class Codes: B41J 2/1629 wet etching
• CPC Class Codes: B41J 2/1632 machining
• CPC Class Codes: B41J 2/1635 dividing the wafer into individual chips
• CPC Class Codes: B41J 2/1639 sacrificial molding
• CPC Class Codes: B41J 2/1642 thin film formation by CVD [chemical vapor deposition]
• CPC Class Codes: B41J 2/1648 Production of print heads with thermal bend detached actuators
• CPC Class Codes: B41J 2/17596 Ink pumps, ink valves
• CPC Class Codes: B41J 2202/05 Heads having a valve
• CPC Class Codes: B41J 3/445 Printers integrated in other types of apparatus, e.g. printers integrated in cameras

Abstract

This patent describes an ink jet printer based around ink jet nozzles which utilize a pump action so as to rapidly refill a nozzle chamber for ejection of subsequent ink drops. The nozzle chamber includes a first actuator for ejecting ink and a second actuator for pumping ink into the nozzle chamber. The actuators can comprise thermal bend actuators having a conductive heater element encased within a material having a high co-efficient of thermal expansion. The heater element is of a serpentine form and is concertinaed upon heating.

Claims

1. An ink jet printhead comprising:

a nozzle chamber having an ink ejection port in one wall of said chamber;

an ink supply source interconnected to said nozzle chamber via another wall of said chamber;

a first moveable actuator in said another wall of said chamber for ejecting ink from said ink ejection port; and

a second moveable actuator in said another wall of said chamber for pumping ink into said chamber from said ink supply source after said first actuator has caused the ejection of ink from said chamber.

2. An ink jet printhead as claimed in claim 1 wherein said actuators comprise thermal bend actuators.

3. An ink jet printhead as claimed in claim 1 wherein said first actuator is arranged substantially opposite said ink ejection port and first and second actuators form segments of a nozzle chamber wall opposite said ink ejection port and between said nozzle chamber and ink supply source.

4. An ink jet printhead as claimed in claim 1 wherein said actuators comprise a conductive heater element encased within a material having a high co-efficient of thermal expansion whereby said actuators operate by means of electrical heating by said heater element.

5. An ink jet printhead as claimed in claim 4 wherein said heater element is of a serpentine form and is concertinaed upon heating so as to allow substantially unhindered expansion of said material during heating.

6. An ink jet printhead as claimed in claim 4 wherein said actuator material has a high coefficient of thermal expansion and comprises substantially polytetrafluoroethylene.

7. An ink jet printhead as claimed in claim 4 wherein said heater material comprises substantially copper.

8. An ink jet printhead as claimed in claim 2 wherein the thermal actuators are attached to a substrate and the heating of said actuators is primarily near the attached end of said device.

9. An ink jet printhead as claimed in claim 1, wherein:

(a) said first actuator ejects ink from said ink ejection port; and

(b) said second actuator pumps ink towards said ink ejection port so as to rapidly refill the nozzle chamber around the area of said ink ejection port.

10. An ink jet printhead as claimed in claim 1 wherein surfaces of said actuators are treated to make them hydrophilic.

11. An ink jet printhead as claimed in claim 1 wherein said actuators are formed by utilization of a sacrificial material layer which is etched away to release said actuators.

12. An ink jet printhead as claimed in claim 1 wherein portions of said nozzle include a silicon nitride covering so as to insulate and passivate them from adjacent portions.

13. An ink jet printhead as claimed in claim 1 wherein said nozzle chamber is formed from crystallographic etching of a silicon substrate.

14. An ink jet printhead as claimed in claim 1 wherein said nozzle is constructed via fabrication from a silicon wafer utilizing semiconductor fabrication techniques.

15. An ink jet printhead as claimed in any one of claims 1 to 5 wherein:

(a) said first actuator is activated to eject ink from said ink ejection port;

(b) said first actuator is deactivated so as to cause a portion of said ejected ink to break off from a main body of ink within said nozzle chamber;

(c) said second actuator is activated to pump ink towards said ink ejection port so as to rapidly refill the nozzle chamber around the are of said ink ejection port; and

(d) said first actuator is activated to eject ink from the ink ejection port while simultaneously deactivating said second actuator so as to return to its quiescent position;

otherwise

(e) said second actuator is deactivated to return to its quiescent position.

16. An ink jet printhead comprising:

a nozzle chamber having an ink ejection port in one wall of said chamber;

an ink supply source interconnected to said nozzle chamber via another wall of said chamber;

a first moveable actuator in said another wall of said chamber for ejecting ink from said ink ejection port said first moveable actuator being arranged substantially opposite said ink ejection port;

a second moveable actuator in said another wall of said chamber for pumping ink into said chamber from said ink supply source after said first actuator has caused the ejection of ink from said chamber,

wherein said first and second actuators form segments of a nozzle chamber wall opposite said ink ejection port and between said nozzle chamber and ink supply source; and

said actuators comprise a conductive heater element encased within a material having a high co-efficient of thermal expansion whereby said actuators operate by means of electrical heating by said heater element and wherein said heater element is of a serpentine form and is concertinaed upon heating so as to allow substantially unhindered expansion of said material during heating.