Inkjet printhead with nozzle chambers each holding two fluids

• US 7,934,808 B2
• Filed: 07/20/2009
• Issued: 05/03/2011
• Est. Priority Date: 07/15/1997
• Status: Expired due to Fees

• Current Assignee: Memjet Technology Ltd. (Memjet Limited)
• Original Assignee: Silverbrook Research Pty Limited
• Inventors: Silverbrook, Kia
• Primary Examiner(s): Do; An H
• Application Number:
  US12/506,145
• Publication Number:
  US 20090278897A1
• Time in Patent Office: 652 Days
• Field of Search: 347/40, 347/47, 347/54, 347/56, 347/62, 347/65
• US Class Current: 347/54
• CPC Class Codes: B41J 2/14 Structure thereof only for on-demand ink jet heads
• CPC Class Codes: B41J 2/14314 Structure of ink jet print heads with electrostatically actuated membrane
• CPC Class Codes: B41J 2/14427 Structure of ink jet print heads with thermal bend detached actuators
• CPC Class Codes: B41J 2/16 Production of nozzles
• CPC Class Codes: B41J 2/1623 bonding and adhesion
• CPC Class Codes: B41J 2/1626 etching
• CPC Class Codes: B41J 2/1628 dry etching
• CPC Class Codes: B41J 2/1629 wet etching
• CPC Class Codes: B41J 2/1631 photolithography
• CPC Class Codes: B41J 2/1632 machining
• CPC Class Codes: B41J 2/1635 dividing the wafer into individual chips
• CPC Class Codes: B41J 2/1637 molding
• 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 2/1643 thin film formation by plating
• CPC Class Codes: B41J 2/1645 thin film formation by spincoating
• CPC Class Codes: B41J 2/1646 thin film formation by sputtering
• CPC Class Codes: B41J 2/1648 Production of print heads with thermal bend detached actuators
• CPC Class Codes: B41J 2/16585 for paper-width or non-reciprocating print heads
• CPC Class Codes: B41J 2/17513 Inner structure
• CPC Class Codes: B41J 2/17596 : Ink pumps, ink valves
• CPC Class Codes: B41J 2002/041 : Electromagnetic transducer
• CPC Class Codes: B41J 2002/14346 : Ejection by pressure produced by thermal deformation of ink chamber, e.g. buckling
• CPC Class Codes: B41J 2002/14435 : Moving nozzle made of thermal bend detached actuator
• CPC Class Codes: B41J 2002/14443 : Nozzle guard
• CPC Class Codes: B41J 2202/21 : Line printing
• CPC Class Codes: G06F 21/79 : in semiconductor storage media, e.g. directly-addressable memories
• CPC Class Codes: G06F 21/86 : Secure or tamper-resistant housings
• CPC Class Codes: G06F 2221/2129 : Authenticate client device independently of the user
• CPC Class Codes: G06K 1/121 : by printing code marks applying code marks to labels B65C9/46; marking or coding completed packages B65B61/26
• CPC Class Codes: G06K 19/06037 : multi-dimensional coding
• CPC Class Codes: G06K 7/14 : using light without selection of wavelength, e.g. sensing reflected white light G06K7/10831 - G06K7/1097 take precedence
• CPC Class Codes: G06K 7/1417 : 2D bar codes
• CPC Class Codes: G07F 7/08 : by coded identity card or credit card or other personal identification means without personal verification means G07F7/02
• CPC Class Codes: G07F 7/086 : by passive credit-cards adapted therefor, e.g. constructive particularities to avoid counterfeiting, e.g. by inclusion of a physical or chemical security-layer for security documents G07D7/00; for the reading of record-carriers in general G06K7/00; for the design of coded credit-cards G06K19/10
• CPC Class Codes: G07F 7/12 : Card verification
• CPC Class Codes: G11C 11/56 : using storage elements with more than two stable states represented by steps, e.g. of voltage, current, phase, frequency
• CPC Class Codes: H04N 23/00 : Cameras or camera modules comprising electronic image sensors; Control thereof
• CPC Class Codes: H04N 5/2628 : Alteration of picture size, shape, position or orientation, e.g. zooming, rotation, rolling, perspective, translation

Abstract

An inkjet printhead that has an array of droplet ejectors, each having a chamber with a nozzle and an actuator for ejecting drops of ink through the nozzle. During use, each of the chambers hold ink and a gas, the gas remaining in the chamber during activation and deactivation of the actuator. The actuators each have a part with a hydrophilic coating for contacting ink in preference to other parts of the actuator such that the gas and the ink are in direct contact with each other at an interface within the chamber, and at least part of the actuator is positioned at the interface between the ink and the gas. By insulating at least some of the actuator from the printhead substrate, more heat is directed into the ink that is ejected from the nozzle. If the actuator is a thermal or thermal bend, the insulating fluid allows the resistive elements to heat more quickly and use less power. This reduces the overall power consumption of the printhead.

Claims

1. An inkjet printhead comprising:

an array of droplet ejectors, each having a chamber with a nozzle; and

,

an actuator for ejecting drops of ink through the nozzle;

such that during use,

each of the chambers hold ink and a gas, the gas remaining in the chamber during activation and deactivation of the actuator;

wherein,

the actuators each have a part with a hydrophilic coating for contacting ink in preference to other parts of the actuator such that the gas and the ink are in direct contact with each other at an interface within the chamber, and at least part of the actuator is positioned at the interface between the ink and the gas.

2. An inkjet printhead as claimed in claim 1 wherein part of each of the actuators has a hydrophobic coating such that the gas contacts the hydrophobic coated part of the actuator in preference to other parts of the actuator.

3. An inkjet printhead as claimed in claim 1 wherein each of the actuators moves a surface within the chamber to eject drops of ink.

4. An inkjet printhead as claimed in claim 1 wherein each of the actuators comprises an electrothermal heater positioned for heating ink in said chamber to a temperature above the boiling point of the ink, causing a bubble to form in order to eject a drop of the ink from said nozzle.

5. An inkjet printhead as claimed in claim 1 wherein each of the actuators is adapted to use differential thermal expansion upon Joule heating to cause ejection of, or assist the ejection of ink from said nozzle.

6. An inkjet printhead as claimed in claim 1 wherein each of the actuators comprises a material with a very high coefficient of thermal expansion, such that thermal expansion of the actuator causes ejection of, or assists the ejection of, ink from said nozzle.

7. An inkjet printhead as claimed in claim 1 wherein each of the actuators is capable of directly firing the ink drops from said nozzle, without the assistance of an external field.

8. An inkjet printhead as claimed in claim 1 wherein each of the actuators is a differential expansion bend actuator capable of converting a high force, low travel mechanism to high travel, lower force mechanism.

9. An inkjet printhead as claimed in claim 1 wherein each of the actuators bends when energized.

10. An inkjet printhead as claimed in claim 1 wherein the chamber, the actuator and the nozzle in each of the drop generators are configured such that ink refills the chamber after drop ejection by the surface tension of the ink.

11. An inkjet printhead as claimed in claim 1 adapted to maintain the ink at a positive pressure wherein each of the drop ejectors has an ink inlet, such that during use, ink in said chamber is restricted from flowing out of the ink inlet during drop ejection by the positive ink pressure.

12. An inkjet printhead as claimed in claim 1 wherein each of the drop ejectors has an ink inlet and each of the chambers has an ink inlet an ink pushing surface, the ink inlet positioned close to the ink pushing surface, such that during drop ejection, ink in said chamber is restricted from flowing out of the ink inlet by the ink pushing surface.

13. An inkjet printhead as claimed in claim 1 further adapted to energize said actuator in rapid succession for clearing dried or partially dried ink in said nozzle.

14. An inkjet printhead as claimed in claim 1 further adapted to provide an enhanced drive to said actuator for clearing dried or partially dried ink in said nozzle.

15. An inkjet printhead as claimed in claim 1 wherein the apparatus is formed on and through a substrate, the nozzle is formed on a front surface of the substrate such that ink flows through the substrate, and ink drops are ejected from the front surface.