Liquid jetting apparatus and method of producing liquid jetting apparatus

1. A liquid jetting apparatus, comprising:

a first pressure chamber;

a second pressure chamber located next to the first pressure chamber in a first direction;

a first insulating film covering the first pressure chamber and the second pressure chamber;

a first piezoelectric element arranged above the first pressure chamber, the first insulating film being intervened between the first pressure chamber and the first piezoelectric element;

a second piezoelectric element arranged above the second pressure chamber, the first insulating film being intervened between the second pressure chamber and the second piezoelectric element;

a third pressure chamber;

a fourth pressure chamber located next to the third pressure chamber in the first direction;

a third piezoelectric element arranged above the third pressure chamber, the first insulating film being intervened between the third pressure chamber and the third piezoelectric element;

a fourth piezoelectric element arranged above the fourth pressure chamber with the first insulating film being intervened between the fourth pressure chamber and the fourth piezoelectric element;

a plurality of traces comprising a plurality of first trace elements arranged between the first piezoelectric element and the second piezoelectric element in the first direction and at least one second trace element arranged between the third piezoelectric element and the fourth piezoelectric element in the first direction, a number of the at least one second trace element being different from a number of the plurality of first trace elements; and

a second insulating film covering the plurality of traces, a width of a first part of the second insulating film covering the plurality of first trace elements between the first piezoelectric element and the second piezoelectric elements being identical to a width of a second part of the second insulating film covering the at least one second trace element between the third piezoelectric element and the fourth piezoelectric element,

wherein the first pressure chamber includes a first end and a second end in the first direction, the second pressure chamber includes a third end and a fourth end in the first direction, and the second end of the first pressure chamber is located next to the third end of the second pressure chamber in the first direction,

wherein the second insulating film includes two ends between the second end of the first pressure chamber and the third end of the second pressure chamber in the first direction.

2. The liquid jetting apparatus according to claim 1 , further comprising:

a partition wall partitioning the first pressure chamber and the second pressure chamber in the first direction; and

a third insulating film arranged between the partition wall and the trace,

wherein, two ends of the third insulating film in the first direction are located between the second end of the first pressure chamber and the third end of the second pressure chamber in the first direction.

3. The liquid jetting apparatus according to claim 2 , wherein, between the first piezoelectric element and the second piezoelectric element, the two ends of the second insulating film in the first direction and the two ends of the third insulating film in the first direction are in the same position in the first direction, respectively.

4. The liquid jetting apparatus according to claim 1 , wherein two ends of the second insulating film in a second direction orthogonal to the first direction are arranged above the first pressure chamber and the second pressure chamber to extend on upper surfaces of the first piezoelectric element and the second piezoelectric element.

5. The liquid jetting apparatus according to claim 1 , wherein a width of the second insulating film in the first direction, is not longer, by 3.8 μm, than a gap between the second end of the first pressure chamber and the third end of the second pressure chamber in the first direction.

6. A method of producing a liquid jetting apparatus, comprising:

preparing a channel substrate formed with a first insulating film, a first piezoelectric element arranged on the first insulating film to correspond to a first pressure chamber, a second piezoelectric element arranged on the first insulating film to correspond a second pressure chamber located next to the first pressure chamber in a first direction, a third piezoelectric element arranged on the first insulating film to correspond to a third pressure chamber, a fourth piezoelectric element arranged on the first insulating film to correspond to a fourth pressure chamber located next to the first pressure chamber in a first direction, and a plurality of traces comprising a plurality of first trace elements arranged between the first piezoelectric element and the second piezoelectric element in the first direction and at least one second trace element arranged between the third piezoelectric element and the fourth piezoelectric element in the first direction, a number of the at least one second trace element being different from a number of the plurality of first trace elements;

forming a second insulating film, on the channel substrate, to cover the first piezoelectric element, the second piezoelectric element, the third piezoelectric element, the fourth piezoelectric element and the trace;

removing a part of the second insulating film covering the first piezoelectric element and the second piezoelectric element and another part of the second insulating film covering the third piezoelectric element and the fourth piezoelectric element, the part of the second insulating film and another part of the second insulating film being removed such that a width of a first remaining part of the second insulating film covering the plurality of first trace elements between the first piezoelectric element and the second piezoelectric element is identical to a width of a second residual part of the second insulating film covering the at least one second trace element between the third piezoelectric element and the fourth piezoelectric element,

wherein the first pressure chamber includes a first end and a second end in the first direction, the second pressure chamber includes a third end and a fourth end in the first direction, and the second end of the first pressure chamber is located next to the third end of the second pressure chamber in the first direction,

wherein the part of the second insulating film is removed such that two ends of residual second insulating film covering the trace between the first piezoelectric element and the second piezoelectric element in the first direction are located between the second end of the first pressure chamber and the third end of the second pressure chamber.

7. The method of producing the liquid jetting apparatus according to claim 6 , wherein the part of the second insulating film is removed such that a width of the residual second insulating film in the first direction, is not longer, by 3.8 μm, than a gap between the second end of the first pressure chamber and the third end of the second pressure chamber in the first direction.

8. The method of producing the liquid jetting apparatus according to claim 6 , wherein the part of the second insulating film is removed such that a gap between one of the two ends of the residual second insulating film and the second end of the first pressure chamber and a gap between the other of the two ends of the residual second insulating film and the third end of the second pressure chamber, respectively, are not shorter than a distance which is 12% of a distance between the second end of the first pressure chamber and the third end of the second pressure chamber in the first direction.

9. The method of producing the liquid jetting apparatus according to claim 6 , further comprising:

forming, before forming the trace on the channel substrate, a third insulating film to cover the first piezoelectric element, the second piezoelectric element, and a partition wall partitioning the first pressure chamber and the second pressure chamber in the first direction; and

removing a part of the third insulating film covering the first piezoelectric element and the second piezoelectric element,

wherein the part of the third insulating film is removed such that two ends of residual third insulating film in the first direction are located between the second end of the first pressure chamber and the third end of the second pressure chamber.

10. The method of producing the liquid jetting apparatus according to claim 6 , wherein the part of the second insulating film and the part of the third insulating film are removed at a time.