Printhead with backflow resistant nozzle chambers

• US 7,703,890 B2
• Filed: 03/03/2009
• Issued: 04/27/2010
• 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): JACKSON, JUANITA DIONNE
• Application Number:
  US12/397,217
• Publication Number:
  US 20090185007A1
• Time in Patent Office: 420 Days
• Field of Search: 347/20, 347/54, 347 56- 59, 347 61- 65, 347/67, 347 92- 94
• US Class Current: 347/54
• 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 2/1623 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 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: 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

A printhead that has an array of ink ejection nozzles, an array of chambers adapted to store ink for ejection through each of the nozzles respectively, a plurality of ink inlet channels for feeding ink the array of chambers, and a plurality of actuators, one of the actuators being positioned in each of the chambers respectively for ejecting drops of ink through the nozzle. A plurality elongate ink feed channels is connected to the ink inlet channels. Each of the ink inlet channels is long and narrow relative to the dimensions of the chamber such that ink in said chamber is restricted from flowing out during ink drop ejection by viscous drag generated by the ink inlet channel. This enhances the droplet ejection efficiency as less of the pressure pulse generated by the actuator is lost to ink back flow.

Claims

1. A printhead comprising:

an array of ink ejection nozzles;

an array of chambers adapted to store ink for ejection through each of the nozzles respectively;

a plurality of ink inlet channels for feeding ink to the array of chambers;

a plurality of actuators, one of the actuators being positioned in each of the chambers respectively for ejecting drops of ink through the nozzle; and

,

a plurality of elongate ink feed channels connected to the ink inlet channels;

a silicon substrate for supporting the array of chambers and defining the elongate ink feed channels, the silicon substrate having a planar structure with one surface that supports the chambers and an opposing surface from which the elongate ink feed channels extend; and

layers of CMOS drive circuitry supported on the silicon substrate;

wherein,

the ink inlet channels each extend through the layers of CMOS drive circuitry and

each of the ink inlet channels being long and narrow relative to the dimensions of the chamber such that ink in said chamber is restricted from flowing out during ink drop ejection by viscous drag generated by the ink inlet channel.

2. A printhead according to claim 1 wherein the actuator has at least one resistive heater element.

3. A printhead according to claim 1 wherein the ink feed channel defines a straight flow path.

4. A printhead according to claim 1 wherein the actuator is radially shaped and adapted to bend at outer edges thereof to effect ejection of ink from the chamber.

5. A printhead according to claim 1 wherein the array of ink ejection nozzles are all formed in a common layer of material which partially defines the array of chambers, each of the chambers also being partially defined by at least one side wall extending from the common layer of material towards the silicon substrate.

6. A printhead according to claim 5 wherein the common layer of material and the at least one side wall are integral.

7. A printhead according to claim 1 wherein the actuator material has an antiferroelectric and a ferroelectric phase, wherein applying an electric field to the actuator material results in a transition from the antiferroelectric to the ferroelectric phase in order to eject drops of ink from said nozzle.

8. A printhead according to claim 1 wherein said actuator comprises conductive plates which are separated by a compressible or fluid dielectric, such that applying a voltage to said plates causes said plates to attract each other and displace ink, said displacement resulting in ejection of ink drops from said nozzle.

9. A printhead according to claim 1 wherein the actuator is adapted to apply a strong electric field to the ink, whereupon electrostatic attraction accelerates the drops of ink towards a print medium.

10. A printhead according to claim 1 wherein said actuator comprises an electromagnet and a permanent magnet, wherein the electromagnet is configured to directly attract a permanent magnet, to cause ejection of, or assists the ejection of ink from said nozzle.

11. A printhead according to claim 1 wherein said actuator comprises a soft magnetic core and a solenoid adapted to induce a magnetic field in the soft magnetic core, the soft magnetic core having two parts spaced apart such that inducing a magnetic field in the soft magnetic core causes said two parts to attract each other, to cause ejection of or assist the ejection of, ink from said nozzle.

12. A printhead according to claim 1 wherein the actuator is adapted to use a Lorenz force acting on said actuator to cause ejection of, or assist the ejection of ink from said nozzle.

13. A printhead according to claim 1 wherein the actuator includes material that exhibit giant magnetostrictive effect, wherein the actuator is adapted to use the giant magnetostrictive effect to cause ejection of, or assist the ejection of ink from said nozzle.

14. A printhead according to claim 1 wherein said actuator is adapted to use differential thermal expansion upon Joule heating to cause ejection of, or assist the ejection of ink from said nozzle.

15. A printhead according to claim 1 wherein said actuator 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.

16. A printhead according to claim 1 wherein said actuator comprises a polymer with a high coefficient of thermal expansion which is doped with conducting substances to increase its conductivity such that resistively heating the actuator results in mechanical motion which ejects or assists in ejecting ink from said nozzle.

17. A printhead according to claim 1 wherein said actuator comprises a shape memory alloy capable of thermal switching between its martensitic state and its austenic state, the switching between states causing the actuator to change shape in order to cause ejection of, or assist in causing ejection of, ink from said nozzle.

18. A printhead according to claim 1 wherein said actuator is a linear magnetic actuator, wherein activation of the actuator causes ejection of, or assists in causing ejection of, ink from said nozzle.