Micro-electromechanical fluid ejection device having a buckle-resistant actuator

• US 7,066,575 B2
• Filed: 10/21/2004
• Issued: 06/27/2006
• 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): Meier, Stephen
• Assistant Examiner(s): Do, An H.
• Application Number:
  US10/968,922
• Publication Number:
  US 20050057610A1
• Time in Patent Office: 614 Days
• Field of Search: 347/54, 347/56, 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
• CPC Class Codes: Y10T 29/49083 : Heater type
• CPC Class Codes: Y10T 29/49117 : Conductor or circuit manufacturing
• CPC Class Codes: Y10T 29/49128 : Assembling formed circuit to base
• CPC Class Codes: Y10T 29/49169 : Assembling electrical component directly to terminal or elongated conductor
• CPC Class Codes: Y10T 29/49172 : by molding of insulating material
• CPC Class Codes: Y10T 29/49401 : Fluid pattern dispersing device making, e.g., ink jet

Abstract

A micro-electromechanical fluid ejection device includes a substrate that defines a fluid inlet channel and incorporates a wafer and CMOS layers positioned on the wafer. A nozzle chamber structure is positioned on the substrate to define a nozzle chamber in fluid communication with the fluid inlet channel and a fluid ejection port in fluid communication with the nozzle chamber. The nozzle chamber structure incorporates a fluid ejecting member that is displaceable with respect to the substrate to act on fluid in the nozzle chamber to eject the fluid from the fluid ejection port. An elongate actuator arm is connected at one end to the substrate and at an opposite end to the fluid ejecting member. The arm has an active beam assembly and a passive beam assembly spaced from and parallel to the active beam assembly. The beam assemblies are mechanically connected, but electrically isolated from each other. The active beam assembly defines an electrical heating circuit connected to the CMOS layers and capable of thermal expansion so that the arm experiences differential thermal expansion to be displaced with respect to the substrate thus displacing the fluid ejecting member. A spacing between the active beam assembly and the passive beam assembly is between one percent and twenty percent of a length of the actuator arm.

Claims

1. A micro-electromechanical fluid ejection device that comprises

a substrate that defines a fluid inlet channel and incorporates a wafer and CMOS layers positioned on the wafer;

a nozzle chamber structure that is positioned on the substrate to define a nozzle chamber in fluid communication with the fluid inlet channel and a fluid ejection port in fluid communication with the nozzle chamber, the nozzle chamber structure incorporating a fluid ejecting member that is displaceable with respect to the substrate to act on fluid in the nozzle chamber to eject the fluid from the fluid ejection port; and

an elongate actuator arm connected at one end to the substrate and at an opposite end to the fluid ejecting member, and having an active beam assembly and a passive beam assembly spaced from and parallel to the active beam assembly, the beam assemblies being mechanically connected, but electrically isolated from each other, with the active beam assembly defining an electrical heating circuit connected to the CMOS layers and being capable of thermal expansion so that the arm experiences differential thermal expansion to be displaced with respect to the substrate thus displacing the fluid ejecting member, wherein

a spacing between the active beam assembly and the passive beam assembly is between one percent and twenty percent of a length of the actuator arm.

2. A micro-electromechanical fluid ejection device as claimed in claim 1, in which said spacing is between five percent and ten percent of the length of the actuator arm.

3. A micro-electromechanical fluid ejection device as claimed in claim 1, in which the fluid ejecting member comprises a crown portion that defines the fluid ejection port and a skirt portion that depends from a periphery of the crown portion, the nozzle chamber structure including a wall that bounds the inlet channel and overlaps the skirt portion so that displacement of the fluid ejecting member results in a change of volume of the nozzle chamber to eject fluid from the nozzle chamber.

4. A micro-electromechanical fluid ejection device as claimed in claim 3, in which the passive beam assembly is interposed between the active beam assembly and the substrate so that thermal expansion of the active beam assembly causes the opposite end of the actuator to be displaced towards the substrate resulting in the fluid ejecting member reducing a volume of the nozzle chamber so that fluid is ejected from the fluid ejection port.

5. A micro-electromechanical fluid ejection device as claimed in claim 3, in which a connecting member interconnects the opposite end of the actuator arm and the fluid ejecting member.

6. A micro-electromechanical fluid ejection device as claimed in claim 3, in which the wall that bounds the inlet channel has an inwardly directed lip which, together with the skirt portion, provides an anchor point for a meniscus that defines a fluidic seal for preventing fluid leakage during operation.

7. A micro-electromechanical fluid ejection device as claimed in claim 1, in which the beam assemblies are both substantially of titanium nitride.