Nozzle assembly for ejecting small droplets

• US 7,661,796 B2
• Filed: 08/24/2008
• Issued: 02/16/2010
• Est. Priority Date: 10/16/1998
• 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:
  US12/197,277
• Publication Number:
  US 20080309693A1
• Time in Patent Office: 541 Days
• Field of Search: 347/9, 347/47, 347/54, 347/56, 347/65, 347/62
• US Class Current: 347/54
• CPC Class Codes: B41J 2/04505 aiming at correcting alignment
• CPC Class Codes: B41J 2/04516 preventing formation of satellite drops
• CPC Class Codes: B41J 2/04518 reducing costs
• CPC Class Codes: B41J 2/0452 reducing demand in current or voltage
• CPC Class Codes: B41J 2/04528 aiming at warming up the head
• CPC Class Codes: B41J 2/04541 Specific driving circuit
• CPC Class Codes: B41J 2/04543 Block driving
• CPC Class Codes: B41J 2/04553 detecting ambient temperature
• CPC Class Codes: B41J 2/04563 detecting head temperature; Ink temperature
• CPC Class Codes: B41J 2/04565 detecting heater resistance
• CPC Class Codes: B41J 2/0457 Power supply level being detected or varied
• CPC Class Codes: B41J 2/04571 detecting viscosity
• CPC Class Codes: B41J 2/04585 controlling heads based on thermal bent actuators
• CPC Class Codes: B41J 2/04588 using a specific waveform
• CPC Class Codes: B41J 2/0459 Height of the driving signal being adjusted
• CPC Class Codes: B41J 2/04591 Width of the driving signal being adjusted
• CPC Class Codes: B41J 2/04593 Dot-size modulation by changing the size of the drop
• CPC Class Codes: B41J 2/04596 Non-ejecting pulses
• CPC Class Codes: B41J 2/04598 Pre-pulse
• CPC Class Codes: B41J 2/14427 Structure of ink jet print heads with thermal bend detached actuators
• CPC Class Codes: B41J 2/155 : for line printing
• 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 2/1646 : thin film formation by sputtering
• CPC Class Codes: B41J 2/1648 : Production of print heads with thermal bend detached actuators
• CPC Class Codes: B41J 2002/14491 : Electrical connection
• CPC Class Codes: B41J 25/005 : for serial printing movements superimposed to character- or line-spacing movements
• CPC Class Codes: G06K 15/102 : using ink jet print heads
• CPC Class Codes: Y10T 29/49401 : Fluid pattern dispersing device making, e.g., ink jet

Abstract

A nozzle assembly for an inkjet printhead is disclosed. The nozzle assembly includes an inkjet nozzle having an actuator for ejecting an ink droplet having a diameter of less than 20 μm from the inkjet nozzle when a resistive element of the actuator is heated by an electrical current. A drive transistor provides an energy pulse to the resistive element of the actuator, and control logic controls the drive transistor.

Claims

1. A nozzle assembly for an inkjet printhead, said nozzle assembly comprising:

a substrate;

an inkjet nozzle disposed on said substrate, said inkjet nozzle having an actuator for ejecting an ink droplet from said inkjet nozzle when a resistive element of said actuator is heated by an electrical current;

a drive transistor for providing an energy pulse to said resistive element of said actuator; and

control logic for controlling said drive transistor,

wherein the diameter of said ink droplet is less than 20 μ

m, and wherein the resistive element of said actuator is spaced apart from said substrate.

2. The nozzle assembly as claimed in claim 1, wherein said drive transistor, control logic and said inkjet nozzle covers an area of less than 20,000 μ

m².

3. The nozzle assembly as claimed in claim 1, wherein said drive transistor and control logic are formed on a silicon substrate, and said inkjet nozzle is formed over at least one of said drive transistor and control logic.

4. The nozzle assembly as claimed in claim 1, wherein an aperture of said inkjet nozzle through which said ink droplet is ejected has a diameter of less than 15 μ

m.

5. The nozzle assembly as claimed in claim 1, wherein the velocity of said ink droplet is less than 8 m/s.

6. The nozzle assembly as claimed in claim 1, wherein the volume of said droplet is less than 3 pl.

7. The nozzle assembly as claimed in claim 1, wherein the energy of said energy pulse is less than 1 μ

J.

8. The nozzle assembly as claimed in claim 1, wherein the voltage of said energy pulse is less than 10 V.

9. The nozzle assembly as claimed in claim 1, wherein said actuator develops a pressure of less than 100 kPa within said inkjet nozzle.

10. The nozzle assembly as claimed in claim 1, wherein a channel length of said drive transistor is less than 1 μ

m.

11. A printhead comprising a plurality of nozzle assemblies as defined in claim 1, wherein nozzles are spaced from other nozzles ejecting ink of a same color by less than 25 μ

m in a direction transverse to the direction of movement of a print media upon which ink is ejected.

12. A printhead comprising a plurality of nozzle assemblies as defined in claim 1, wherein nozzles are spaced from other nozzles ejecting ink of a different color by less than 400 microns.

13. The printhead defined in claim 11 comprising at least 2000 nozzles fabricated on a single monolithic wafer.