Acoustic wave element and communication apparatus

1. An acoustic wave element, comprising:

an IDT electrode comprising a plurality of electrode fingers; and

reflector electrodes on the two sides of the IDT electrode, wherein

the IDT electrode comprises

a major part and

at least one end part which is located between the major part and one of the reflector electrodes and is located along a direction of propagation of an acoustic wave together with the major part,

the at least one end part,

comprises a pitch of the plurality of electrode fingers, the pitch being substantially the same as a pitch of the plurality of electrode fingers in the major part,

is electrically connected in parallel with respect to the major part, and

is divided into two or more sections along the direction of propagation of the acoustic wave, the two or more sections being electrically connected in series with each other,

the two or more sections comprise

a first section adjacent to the major part in the direction of propagation, and

a second section adjacent to the first section in the direction of propagation,

the IDT electrode comprises two bus bars which face each other in a direction crossing the direction of propagation,

one bus bar of the two bus bars is divided in the direction of propagation at a boundary between the major part and the first section, and

another bus bar of the two bus bars is divided in the direction of propagation at a boundary between the first section and the second section.

2. The acoustic wave element according to claim 1 , wherein:

the at least one end part is divided into a first part which is adjacent to the major part, a second part which is adjacent to a side of the first part opposite from the major part, and a third part which is located between the second part and the one of the reflector electrodes, and

in each of the first part, second part, and third part, the number of the plurality of electrode fingers is four or more and 10 or less fingers.

3. The acoustic wave element according to claim 2 , wherein in any of the first part, the second part, and the third part, the pitch of the plurality of electrode fingers becomes 1.001 or more time and 1.003 or less time the pitch of the plurality of electrode fingers in the major part.

4. A communication apparatus, comprising:

a first filter comprising a first passing band; and

a second filter comprising a second passing band which is different from the first passing band, wherein

the acoustic wave element according to claim 1 is used for the acoustic wave filter used in the first filter or the second filter.

5. The communication apparatus according to claim 4 , wherein

the acoustic wave filter comprises

the acoustic wave element and

a second acoustic wave element comprising a second IDT electrode and second reflector electrodes on the two sides of the second IDT electrode,

the at least one of the reflector electrodes in the acoustic wave element comprises a plurality of reflection electrode fingers arranged along the direction of propagation of the acoustic wave,

one of the second reflector electrodes in the second acoustic wave element comprises a plurality of second reflection electrode fingers arranged along the direction of propagation of the acoustic wave, and

the number of the reflection electrode fingers is smaller in comparison with the number of the second reflection electrode fingers.

6. The acoustic wave element according to claim 1 , wherein the electrode fingers are repeatedly arranged so that a phase of the acoustic wave excited in the major part and a phase of the acoustic wave excited in the at least one end part become substantially in-phase.

7. The acoustic wave element according to claim 1 , wherein the number of the plurality of electrode fingers of the at least one end part is four or more and 30 or less fingers.

8. The acoustic wave element according to claim 1 , wherein each of the sections obtained by division of the at least one end part comprises the same number of plurality of electrode fingers.

9. The acoustic wave element according to claim 1 , wherein:

the at least one end part is divided into a first part which is adjacent to the major part and a second part which is located between the first part and the one of the reflector electrodes, and

in each of the first part and the second part, the number of the plurality of electrode fingers is six or more and 12 or less fingers.

10. The acoustic wave element according to claim 1 , wherein

the at least one end part is divided into a first part which is adjacent to the major part and a second part which is located between the first part and the one of the reflector electrodes, and

in the first part, the number of the plurality of electrode fingers is eight or more and 12 or less fingers, and

in the second part, the number of the plurality of electrode fingers is 12 or more and 16 or less fingers.

11. The acoustic wave element according to claim 1 , wherein:

the at least one of the reflector electrodes comprises a plurality of reflection electrode fingers arranged along the direction of propagation of the acoustic wave, and

the number of the plurality of reflection electrode fingers is 10 or more and 20 or less fingers.

12. An acoustic wave element, comprising:

an IDT electrode comprising pluralities of electrode fingers; and

reflector electrodes on the two sides of the IDT electrode, wherein

the IDT electrode comprises

a major part and

at least one end part which is located between the major part and one of the reflector electrodes and is located along a direction of propagation of an acoustic wave together with the major part,

the at least one end part,

comprises a pitch of the plurality of electrode fingers, the pitch being substantially the same as a pitch of the plurality of electrode fingers in the major part,

is electrically connected in parallel with respect to the major part, and

is divided into two or more sections in a direction different from the direction of propagation of the acoustic wave, the two or more sections being electrically connected in series with each other,

the major part comprises

a first bus bar and a second bus bar which face each other in a direction crossing the direction of propagation,

a plurality of a first electrode fingers which extend from the first bus bar toward the second bus bar,

a plurality of a second electrode fingers which extend from the second bus bar toward the first bus bar, and which mesh with the plurality of the first electrode fingers,

when viewed in the direction of propagation, a plurality of electrode fingers of each of the two or more sections of the at least one end part overlap the plurality of first electrode fingers and the plurality of second electrode fingers of the major part.