Inkjet head, inkjet printer, and manufacturing method for inkjet head

1. An ink jet head, comprising:

a head substrate including thereon:

a plurality of ink jet elements configured to cause ink to be ejected from a plurality of nozzles; and

a common wire extending from an edge of the head substrate and electrically connected to the ink jet elements in common;

a printed board with a reference potential wire through which a reference potential is provided to the ink jet head; and

a plurality of flexible substrates connected in parallel to each other between the edge of the head substrate and an edge of the printed board,

wherein

a first one of the flexible substrates at a first end of an arrangement of the plurality of flexible substrates and a second one of the flexible substrates at a second end of the arrangement of the plurality of flexible substrates each has a common connection wire directly connected between a portion of the common wire at the edge of the head substrate and a portion of the reference potential wire at the edge of the printed board, and

a line width of the portion of the common wire is greater than a line width of the common connection wire of the first one of the flexible substrates and greater than a line width of the common connection wire of the second one of the flexible substrates.

2. The ink jet head according to claim 1 , wherein

the common connection wire of the first one of the flexible substrates is disposed along an outside edge thereof, and

the common connection wire of the second one of the flexible substrates is disposed along an outside edge thereof.

3. The ink jet head according to claim 1 , wherein the plurality of flexible substrates includes at least three flexible substrates in total.

4. The ink jet head according to claim 3 , wherein a third one of the flexible substrates is between the first one of the flexible substrates and the second one of the flexible substrates in the arrangement of the plurality of flexible substrate.

5. The ink jet head according to claim 4 , wherein the third one of the flexible substrates has no common connection wire electrically connected between the common wire and the reference potential wire.

6. The ink jet head according to claim 4 , wherein the third one of the flexible substrates has a dummy wire at a position of the third one of the flexible substrates corresponding to a position of the common connection wire on the first one of the flexible substrates.

7. The ink jet head according to claim 6 , wherein the dummy wire is electrically isolated from any wire on the head substrate and any wire on the printed board.

8. The ink jet head according to claim 3 , wherein a wire arrangement of the third one of the flexible substrates is the same as a wire arrangement of the first one of the flexible substrates except for the common connection wire thereof.

9. The ink jet head according to claim 5 , wherein a wire arrangement of the third one of the flexible substrates is the same as a wire arrangement of the first one of the flexible substrates except for the common connection wire thereof.

10. The ink jet head according to claim 2 , wherein the first one of the flexible substrates further includes a dummy wire extending between first and second edges thereof along an inside edge opposite to the outside edge.

11. The ink jet head according to claim 10 , wherein the dummy wire is electrically isolated from any wire on the head substrate and any wire on the printed board.

12. The ink jet head according to claim 10 , wherein the common connection wire and the dummy wire are disposed symmetrically with respect to a center line of the first one of the flexible substrates extending between the first and second edges.

13. The ink jet head according to claim 1 , wherein a wire arrangement of the first one of the flexible substrates except for the common connection wire thereof is the same as a wire arrangement of the second one of the flexible substrates except for the common connection wire thereof.

14. The ink jet head according to claim 1 , wherein

the first one of the flexible substrates includes no wire extending between first and second edges thereof at a position along an inside edge opposite to the outside edge, and

the second one of the flexible substrates includes no wire extending between first and second edges thereof at a position along an inside edge opposite to the outside edge.

15. The ink jet head according to claim 14 , wherein a wire arrangement of the first one of the flexible substrates except for the common connection wire thereof is the same as a wire arrangement of the second one of the flexible substrates except for the common connection wire thereof.

16. The ink jet head according to claim 1 , wherein a wire arrangement of the first one of the flexible substrates and a wire arrangement of the second one of the flexible substrates are symmetrical with respect to a center of the head substrate.

17. A method for manufacturing an ink jet head, comprising:

forming a sprocket film including a plurality of flexible substrate regions, each flexible substrate region including:

a first wire extending between a first end of the flexible substrate region and a second end of the substrate region opposite the first end along a third end of the flexible substrate region,

a second wire extending between the first and second ends of the flexible substrate region along a fourth end of the flexible substrate region opposite to the third end, and

a plurality of drive wires to be connected to a drive circuit configured to drive ink jet elements of an ink jet head;

cutting a first region from the sprocket film, the cut first region corresponding to a flexible substrate region with an end portion corresponding to the second wire being excluded; and

using the cut first region as a first flexible substrate having a drive circuit mounted thereon.

18. The method according to claim 17 , further comprising:

cutting a second region from the sprocket film, the cut second region corresponding to a flexible substrate region with an end portion corresponding to the first wire being excluded; and

using the cut second region as a second flexible substrate having a second drive circuit mounted thereon, the second flexible substrate being connected to a head substrate including ink jet elements in parallel with the first flexible substrate.

19. The method according to claim 17 , further comprising:

cutting a third region from the sprocket film, the cut third region corresponding to a flexible substrate region with an end portion corresponding to the first wire and an end portion corresponding to the second wire being excluded; and

using the cut third region as a third flexible substrate having a third drive circuit mounted thereon, the third flexible substrate being between the first flexible substrate and the second flexible substrate and connected in parallel with the first flexible substrate and the second flexible substrate.

20. The method according to claim 17 , further comprising:

connecting the first wire of the first flexible substrate to a common wire of a head substrate that is electrically connected to common terminals of ink jet elements.