Head chip and head unit

• US 6,491,383 B2
• Filed: 05/24/2001
• Issued: 12/10/2002
• Est. Priority Date: 05/25/2000
• Status: Active Grant

• Current Assignee: Seiko Instruments Incorporated (Seiko Group)
• Original Assignee: Seiko Instruments Incorporated (Seiko Group)
• Inventors: Harajiri, Toshihiko
• Primary Examiner(s): Vo, Anh T. N.
• Application Number:
  US09/864,939
• Publication Number:
  US 20020003558A1
• Time in Patent Office: 565 Days
• Field of Search: 347/54, 347/56, 347/68, 347/69, 347/71, 349/107, 359/608
• US Class Current: 347/68
• CPC Class Codes: B41J 2/14209 of finger type, chamber walls consisting integrally of piezoelectric material
• CPC Class Codes: B41J 2/1609 of finger type, chamber walls consisting integrally of piezoelectric material
• CPC Class Codes: B41J 2/1623 bonding and adhesion
• CPC Class Codes: B41J 2/1632 machining
• CPC Class Codes: B41J 2/1643 thin film formation by plating
• CPC Class Codes: B41J 2002/14362 Assembling elements of heads

Abstract

A head chip and a head unit, in which manufacturing cost is reduced and also manufacturing steps are simplified, are provided. In a head chip 10 in which: partition walls 12 made of piezoelectric ceramic are arranged on two upper and lower sheets of a first board 11 and a second board 16 with predetermined intervals; chambers 13 are defined between the respective partition walls 12; a driver voltage is applied to electrodes 14 provided on the side surfaces of the partition walls 12 to change the capacity in ink flow paths; and the ink filled in the ink flow paths is jetted from nozzle openings, the first board 11 and the second board 16 are formed of a dielectric material; wiring lines 15 which are electrically conducted to the electrodes 14 and elongated to the outside of the end portions of the partition walls 12 in the longitudinal direction, are provided on the surface of any one of the first board 11 and the second board 16; and further the wiring lines 15 include an inorganic conductive film 15a as the lowermost layer and metal films 15b and 15c formed thereon.

Claims

1. A head chip in which:

partition walls made of piezoelectric ceramic are arranged on two upper and lower sheets of a first board and a second board with predetermined intervals;

chambers are defined between the respective partition walls;

a driver voltage is applied to electrodes provided on side surfaces of said partition walls to change the capacity in said chambers; and

the ink filled in said chambers is jetted from nozzle openings, characterized in that;

said first board and said second board are formed of a dielectric material, and also wiring lines, which are electrically conducted to said electrodes and elongated to an outside of end portions of said partition walls in a longitudinal direction, are provided on a surface of either one of said first board and said second board; and

further, said wiring lines include an inorganic conductive film as a lowermost layer and metal films formed thereon.

2. A head chip as claimed in claim 1, characterized in that said dielectric material is glass.

3. A head chip as claimed in claim 1 or 2, characterized in that said inorganic conductive film is made of at least one sort of material selected from the group consisting of ITO, SnO₂, ZnO, and ATO.

4. A head chip as claimed in claim 1 or 2, characterized in that said inorganic conductive film is elongated between one of said first board and said second board and the end portions of said partition walls in a width direction, and also an end portion of the elongated inorganic conductive film in the width direction and said electrodes are electrically conducted to each other.

5. A head chip as claimed in claim 4, characterized in that a thickness of said inorganic conductive film is set to be equal to or less than 3 μ

m.

6. A head chip as claimed in claim 1 or 2, characterized in that said electrodes and said metal films are formed by selective electroless plating.

7. A head chip as claimed in claim 1 or 2, characterized in that said electrodes and said metal films are formed of a nickel layer and a gold layer.

8. A head chip as claimed in claim 1 or 2, characterized in that a nozzle plate having said nozzle openings is provided at the end portions of said partition walls in the longitudinal direction, at which said chambers are opened, and also an ink chamber that communicates with said respective chambers is provided on an another end portion side of said partition walls.

9. A head chip as claimed in claim 8, characterized in that said nozzle plate is formed of a dielectric material.

10. A head chip as claimed in claim 1 or 2, characterized in that said partition walls are formed by jointing two sheets of piezoelectric ceramic having different polarization direction in the thickness direction.

11. A head chip as claimed in claim 1 or 2, characterized in that regions corresponding to said chambers are provided with concave portions in one of said first board and said second board, which is provided with said wiring lines.

12. A head chip as claimed in claim 1 or 2, characterized in that a driver circuit is provided with a region corresponding to said wiring lines in one of said first board and said second board, which is provided with said wiring lines.

13. A head unit characterized in that said head unit comprises the head chip as claimed in claim 1 or 2 and a head holder that mounts the head chip.

14. A head unit as claim in claim 13, characterized in that said head holder may detachably hold an ink cartridge in which ink is stored.