Electrostatic ink jet printing mechanism

• US 6,213,588 B1
• Filed: 07/10/1998
• Issued: 04/10/2001
• 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:
  US09/112,787
• Time in Patent Office: 1,005 Days
• Field of Search: 347/54, 347/84, 347/85, 347/44, 347/20
• 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 2/16 Production of nozzles
• CPC Class Codes: B41J 2/1623 bonding and adhesion
• 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 2/1639 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 2/16585 for paper-width or non-reciprocating print heads
• CPC Class Codes: B41J 2/17596 Ink pumps, ink valves
• CPC Class Codes: B41J 2002/041 Electromagnetic transducer
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• 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: 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

This patent describes an ink jet printer where ink is ejected from a nozzle chamber by means of the utilisation of the electrostatic attraction between two parallel plates. An electrostatic actuator includes a first planar electrode formed within a bottom and a moveable second planar electrode arranged above the first planar electrode. The second planar electrode is moveable to a pre-firing position adjacent to the first planar electrode, thereby causing a corrugated border portion of the second electrode to concertina. Upon reduction of a potential difference, the corrugated border returns to its quiescent position, thereby causing the ejection of ink from the nozzle chamber. Between the first planar electrode and the second planar electrode is an air gap interconnected to an external atmosphere at a side of the nozzle chamber such that air flows into and out of the gap upon movement of the actuator.

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;

an electrostatic actuator comprising a first planar electrode formed within a bottom substrate of the nozzle chamber and a moveable second planar electrode arranged above the first planar electrode and having a corrugated border portion, said second planar electrode being moveable to a pre-firing position adjacent to said first planar electrode, upon forming a potential difference across said electrodes, thereby causing said corrugated border portion of said second electrode to concertina, such that, upon reduction of said potential difference, said corrugated border portion returns to is quiescent position, thereby causing the ejection of ink from said nozzle chamber.

2. An ink jet printhead as claimed in claim 1 wherein between said first planar electrode and said second planar electrode is an air gap interconnected to an external atmosphere at a side of said nozzle chamber such that air flows into and out of said gap upon movement of said actuator.

3. An ink jet printhead as claimed in claim 2 wherein said gap is formed by utilization of a sacrificial material layer which is etched away to release said second planar electrode structure.

4. An ink jet printhead as claimed in claim 1 wherein the electrodes have facing surfaces that are coated with a material having a low coefficient of friction so as to reduce the possibilities of stiction.

5. An ink jet printhead as claimed in claim 4 wherein said material comprises substantially polytetrafluoroethylene.

6. An ink jet printhead as claimed in claim 1 wherein said second planar electrode includes a layer of stiffening material for maintaining the stiffness of said second planar electrode.

7. An ink jet printhead as claimed in claim 6 wherein said stiffening material comprises substantially nitride.

8. 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;

an electrostatic actuator to eject ink from said nozzle chamber via said ink ejection port, said electrostatic actuator comprising a first planar electrode formed within a bottom substrate of the nozzle chamber and a moveable second planar electrode arranged above the first planar electrode, said nozzle chamber and said electrostatic actuator being formed from depositing and etching of material on a single monolithic wafer.

9. An ink jet printhead as claimed in claim 8 wherein an outer surface of said ink chamber includes a plurality of etchant holes provided so as to allow a more rapid etching of sacrificial layers during construction.

10. 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;

an electrostatic actuator comprising a first planar electrode formed within a bottom substrate of the nozzle chamber and a moveable second planar electrode arranged above the first planar electrode and having a corrugated border portion, said second planar electrode being moveable to a pre-firing position adjacent to said first planar electrode, upon forming a potential difference across said electrodes, thereby causing said corrugated border portion of said second electrode to concertina, such that, upon reduction of said potential difference, said corrugated border portion returns to is quiescent position, thereby causing the ejection of ink from said nozzle chamber, said nozzle chamber and said electrostatic actuator being formed from depositing and etching of material on a single monolithic wafer, and wherein between said first planar electrode and said second planar electrode is an air gap interconnected to an external atmosphere at a side of said nozzle chamber such that air flows into and out of said gap upon movement of said actuator, and wherein the electrodes have facing surfaces that are coated with a material comprising substantially polytetrafluoroethylene, and wherein said second planar electrode includes a layer of stiffening material comprising substantially nitride.