Ultrasound unit and ultrasound endoscope
View Patent ↗An ultrasound unit includes a plurality of elements each including N cells, in each of which a bottom electrode and a top electrode that constitutes a membrane are arranged facing each other with a cavity therebetween, wherein the element has N 1 first cells and N 2 (where N 1 ≠N 2 , N 1 +N 2 =N) second cells having higher reception sensitivity and lower transmission sensitivity than the first cells.
1. An ultrasound unit comprising:
a plurality of ultrasound transducer elements, wherein each of the plurality of ultrasound transducer elements comprises:
N ultrasound transducer cells comprising:
N 1 first ultrasound transducer cells, wherein each of the N 1 first ultrasound transducer cells comprises:
a first bottom electrode; and
a first membrane comprising a first top electrode, wherein the first bottom electrode and the first top electrode are arranged to face each other with a first cavity therebetween; and
N 2 (where N 1 ≠N 2 , N 1 +N 2 =N) second ultrasound transducer cells, wherein each of the N 2 second ultrasound transducer cells comprises:
a second bottom electrode; and
a second membrane comprising a second top electrode, wherein the second bottom electrode and the second top electrode are arranged to face each other with a second cavity therebetween,
wherein the each of the N 1 first ultrasound transducer cells and the each of the N 2 second ultrasound transducer cells are configured such that the each of the N 2 second ultrasound transducer cells have higher reception sensitivity and lower transmission sensitivity than the each of the N 1 first ultrasound transducer cells,
wherein the first top electrode is electrically connected with the second top electrode, and the first bottom electrode is electrically connected with the second bottom electrode such that the N1 first ultrasound transducer cells and the N2 second ultrasound transducer cells are configured to be driven to transmit ultrasound together or to receive ultrasound together, and
wherein the N 1 first ultrasound transducer cells and the N 2 second ultrasound transducer cells have membranes having different thicknesses.
2. The ultrasound unit according to claim 1 ,
wherein each of the N 1 first ultrasound transducer cells has transmission sensitivity S T1 and reception sensitivity S R1 ,
wherein each of the N 2 second ultrasound transducer cells has transmission sensitivity S T2 (where S T1 >S T2 ) and reception sensitivity S R2 (where S R1 <S R2 ), and
wherein a following expression is satisfied:
0.9 X≤N 1 ≤1.1 X,
where
X
=
2
S
T
2
S
R
2
-
S
T
1
S
R
2
-
S
T
2
S
R
1
2
(
S
T
1
-
S
T
2
)
(
S
R
1
-
S
R
2
)
N
.
3. The ultrasound unit according to claim 1 ,
wherein each of the N 1 first ultrasound transducer cells has an area A 1 , and each of the N 2 second ultrasound transducer cells has an area A 2 (where A 1 ≠A 2 ).
4. The ultrasound unit according to claim 1 ,
wherein each of the N 1 first ultrasound transducer cells has transmission sensitivity S T1 , reception sensitivity S R1 , and an area A 1 ,
wherein each of the N 2 second ultrasound transducer cells has transmission sensitivity S T2 (where S T1 >S T2 ), reception sensitivity S R2 (where S R1 <S R2 ), and an area A 2 (where A 1 ≠A 2 ), and a following expression is satisfied:
0.9 Z≤N 1 ≤1.1 Z,
where
Z
=
2
S
T
2
S
R
2
A
1
-
(
S
T
1
S
R
2
+
S
T
2
S
R
1
)
A
2
2
S
T
1
S
R
1
A
2
+
2
S
T
2
S
R
2
A
1
-
(
S
T
1
S
R
2
+
S
T
2
S
R
1
)
(
A
1
+
A
2
)
N
.
5. An ultrasound endoscope comprising:
an insertion portion comprising a distal end portion,
wherein the distal end portion comprises the ultrasound unit according to claim 1 .