U.S. patent application number 10/153564 was filed with the patent office on 2003-11-20 for ultrasound radiating and receiving device.
Invention is credited to Toda, Kohji.
Application Number | 20030213306 10/153564 |
Document ID | / |
Family ID | 29269825 |
Filed Date | 2003-11-20 |
United States Patent
Application |
20030213306 |
Kind Code |
A1 |
Toda, Kohji |
November 20, 2003 |
ULTRASOUND RADIATING AND RECEIVING DEVICE
Abstract
An ultrasound radiating and receiving device comprises a
piezoelectric substrate, an interdigital arrangement of first and
second comb-shaped electrodes, and a counter electrode. The
interdigital arrangement is mounted on an upper end surface of the
piezoelectric substrate. The counter electrode is formed on a lower
end surface of the piezoelectric substrate, and is in contact with
a surface-part of a material through the lower end surface of the
counter electrode. When an input electric signal is applied between
the first comb-shaped electrode and the counter electrode, a
longitudinal wave is radiated into the material through the
surface-part of the material along the direction vertical to the
lower end surface of the piezoelectric substrate. If the
longitudinal wave is reflected at an object located inside the
material, a reflected longitudinal wave is detected between the
second comb-shaped electrode and the counter electrode as a delayed
electric signal.
Inventors: |
Toda, Kohji; (Yokosuka,
JP) |
Correspondence
Address: |
Kohji Toda
1-49-18 Futaba
Yokosuka
239-0814
JP
|
Family ID: |
29269825 |
Appl. No.: |
10/153564 |
Filed: |
May 20, 2002 |
Current U.S.
Class: |
73/651 |
Current CPC
Class: |
G01N 2291/102 20130101;
G01N 2291/02475 20130101; G01N 2291/044 20130101; G01N 2291/011
20130101; G01N 2291/0421 20130101; G01N 29/36 20130101; G01N 29/022
20130101 |
Class at
Publication: |
73/651 |
International
Class: |
G01D 021/00 |
Claims
What is claimed is:
1. An ultrasound radiating and receiving device comprising: a
piezoelectric substrate; a first comb-shaped electrode formed on an
upper end surface of said piezoelectric substrate; a second
comb-shaped electrode formed on said upper end surface of said
piezoelectric substrate; and a counter electrode formed on a lower
end surface of said piezoelectric substrate and in contact with a
surface-part of a material through the lower end surface of said
counter electrode, said first- and second comb-shaped electrodes
forming an interdigital arrangement, said first comb-shaped
electrode and said counter electrode receiving an input electric
signal, radiating a longitudinal wave into said material through
said surface-part of said material along the direction vertical to
said lower end surface of said piezoelectric substrate, and making
an object located inside said material reflect said longitudinal
wave back, said second comb-shaped electrode and said counter
electrode detecting a reflected longitudinal wave as a delayed
electric signal.
2. An ultrasound radiating and receiving device as defined in claim
1 further comprising an amplifier between said first- and second
comb-shaped electrodes, said amplifier amplifying said delayed
electric signal, and supplying said first comb-shaped electrode
with an amplified electric signal as said input electric
signal.
3. An ultrasound radiating and receiving device as defined in claim
1, wherein the opposite surface-part of said material acts as said
object.
4. An ultrasound radiating and receiving device as defined in claim
1, wherein the ratio of the interdigital periodicity of said
interdigital arrangement to the thickness of said piezoelectric
substrate is smaller than four times the ratio of the longitudinal
wave velocity in said material to the longitudinal wave velocity in
said piezoelectric substrate.
5. An ultrasound radiating and receiving device as defined in claim
1, wherein increasing the number of electrode-finger pairs in said
interdigital arrangement makes the directionality of said
longitudinal wave sharper under a condition that the total amount
of all the finger-areas of said first comb-shaped electrode is
constant.
6. An ultrasound radiating and receiving device as defined in claim
1, wherein said material is a liquid matter.
7. An ultrasound radiating and receiving device as defined in claim
1, wherein said material is a cellular tissue.
8. An ultrasound radiating and receiving device as defined in claim
1 further comprising a polymer film, with which said lower end
surface of said counter electrode is coated.
9. An ultrasound radiating and receiving device as defined in claim
1 further comprising: a scanning unit composed of groups X.sub.i
(i=1, 2, . . . , n) of switches corresponding to the
electrode-fingers of said first comb-shaped electrode,
respectively, one and the next of said groups X.sub.i having common
switches each other except the first switch of said one of said
groups X.sub.i and the last switch of said next of said groups
X.sub.i, said first comb-shaped electrode and said counter
electrode receiving input electric signals via said groups X.sub.i
in turn, and radiating longitudinal waves along the direction
vertical to said lower end surface of said piezoelectric substrate
into said material in the form of a scanned ultrasound beam as a
whole, and then making said object reflect said longitudinal waves
back, said second comb-shaped electrode and said counter electrode
detecting a reflected ultrasound beam as a scanned electric
signal.
10. An ultrasound radiating and receiving device as defined in
claim 1 further comprising: a first scanning unit composed of
groups X.sub.i (i=1, 2, . . . , n) of switches corresponding to the
electrode-fingers of said first comb-shaped electrode,
respectively, one and the next of said groups X.sub.i having common
switches each other except the first switch of said one of said
groups X.sub.i and the last switch of said next of said groups
X.sub.i, and a second scanning unit composed of groups Y.sub.i
(i=1, 2, . . . , n) of switches corresponding to the
electrode-fingers of said second comb-shaped electrode,
respectively, one and the next of said groups Y.sub.i having common
switches each other except the first switch of said one of said
groups Y.sub.i and the last switch of said next of said groups
Y.sub.i, said first comb-shaped electrode, together with said
counter electrode, receiving input electric signals via said groups
X.sub.i in turn, and radiating longitudinal waves along the
direction vertical to said lower end surface of said piezoelectric
substrate into said material in the form of a scanned ultrasound
beam as a whole, and then making said object reflect said
longitudinal waves back, said second comb-shaped electrode,
together with said counter electrode, detecting reflected
longitudinal waves by means of said groups Y.sub.i in turn in the
form of a scanned electric signal as a whole.
11. An ultrasound radiating and receiving device comprising: a
first piezoelectric substrate; a first interdigital arrangement of
two comb-shaped electrodes formed on a lower end surface of said
first piezoelectric substrate, a lower end surface of said first
interdigital arrangement being in contact with a surface-part of a
material; a second piezoelectric substrate; a second interdigital
arrangement of two comb-shaped electrodes formed on an upper end
surface of said second piezoelectric substrate; and a counter
electrode cemented between said first- and second piezoelectric
substrates, one of said two comb-shaped electrodes in said first
interdigital arrangement and said counter electrode receiving an
input electric signal, radiating a longitudinal wave into said
material through said surface-part of said material along the
direction vertical to said lower end surface of said first
piezoelectric substrate, and making an object located inside said
material reflect said longitudinal wave back, one of said two
comb-shaped electrodes in said second interdigital arrangement and
said counter electrode detecting a reflected longitudinal wave as a
delayed electric signal.
12. An ultrasound radiating and receiving device as defined in
claim 11, wherein the finger direction of said second interdigital
arrangement is orthogonal to that of said first interdigital
arrangement.
13. An ultrasound radiating and receiving device as defined in
claim 11, wherein the opposite surface-part of said material acts
as said object.
14. An ultrasound radiating and receiving device as defined in
claim 11, wherein the finger width in said one of said two
comb-shaped electrodes in said first interdigital arrangement is
wider than that in the other of said two comb-shaped electrodes in
said first interdigital arrangement, and the finger width in said
one of said two comb-shaped electrodes in said second interdigital
arrangement is wider than that in the other of said two comb-shaped
electrodes in said second interdigital arrangement.
15. An ultrasound radiating and receiving device as defined in
claim 11, wherein the ratio of the interdigital periodicity of said
first interdigital arrangement to the thickness of said first
piezoelectric substrate is smaller than four times the ratio of the
longitudinal wave velocity in said material to the longitudinal
wave velocity in said first piezoelectric substrate.
16. An ultrasound radiating and receiving device as defined in
claim 11, wherein increasing the number of electrode-finger pairs
in said first interdigital arrangement makes the directionality of
said longitudinal wave sharper under a condition that the total
amount of all the finger-areas of said one of said two comb-shaped
electrodes in said first interdigital arrangement is constant.
17. An ultrasound radiating and receiving device as defined in
claim 11, wherein said material is a liquid matter.
18. An ultrasound radiating and receiving device as defined in
claim 11, wherein said material is a cellular tissue.
19. An ultrasound radiating and receiving device as defined in
claim 11 further comprising a polymer film, with which said lower
end surface of said first interdigital arrangement is coated.
20. An ultrasound radiating and receiving device as defined in
claim 11 further comprising: a first scanning unit composed of
groups X.sub.i (i=11, . . . , n) of switches corresponding to the
electrode-fingers, respectively, of said one of said two
comb-shaped electrodes in said first interdigital arrangement, one
and the next of said groups X.sub.i having common switches each
other except the first switch of said one of said groups X.sub.i
and the last switch of said next of said groups X.sub.i, and a
second scanning unit composed of groups Y.sub.i (i=11, . . . , n)
of switches corresponding to the electrode-fingers, respectively,
of said one of said two comb-shaped electrodes in said second
interdigital arrangement, one and the next of said groups Y having
common switches each other except the first switch of said one of
said groups Y.sub.i and the last switch of said next of said groups
Y.sub.i, said one of said two comb-shaped electrodes in said first
interdigital arrangement, together with said counter electrode,
receiving input electric signals via said groups X.sub.i in turn,
and radiating longitudinal waves along the direction vertical to
said lower end surface of said first piezoelectric substrate into
said material through said surface-part of said material in the
form of a scanned ultrasound beam as a whole, and then making said
object reflect said scanned ultrasound beam back, said one of said
two comb-shaped electrodes in said second interdigital arrangement,
together with said counter electrode, detecting reflected and
scanned ultrasound beams by means of said groups Y.sub.i in turn as
scanned electric signals, and imaging the upper surface-shape of
said object from said scanned electric signals.
21. An ultrasound radiating and receiving device comprising: a
first piezoelectric substrate; a first comb-shaped electrode formed
on a lower end surface of said first piezoelectric substrate, a
lower end surface of said first comb-shaped electrode being in
contact with a surface-part of a material; a second piezoelectric
substrate; a second comb-shaped electrode formed on an upper end
surface of said second piezoelectric substrate; and a counter
electrode cemented between said first- and second piezoelectric
substrates, said first comb-shaped electrode and said counter
electrode receiving an input electric signal, radiating a
longitudinal wave into said material through said surface-part of
said material along the direction vertical to said lower end
surface of said first piezoelectric substrate, and making an object
located inside said material reflect said longitudinal wave back,
said second comb-shaped electrode and said counter electrode
detecting a reflected longitudinal wave as a delayed electric
signal.
22. An ultrasound radiating and receiving device as defined in
claim 21, wherein the finger direction of said second comb-shaped
electrode is orthogonal to that of said first comb-shaped
electrode.
23. An ultrasound radiating and receiving device as defined in
claim 21, wherein the opposite surface-part of said material acts
as said object.
24. An ultrasound radiating and receiving device as defined in
claim 21, wherein the ratio of the interdigital periodicity of said
first comb-shaped electrode to the thickness of said first
piezoelectric substrate is smaller than four times the ratio of the
longitudinal wave velocity in said material to the longitudinal
wave velocity in said first piezoelectric substrate.
25. An ultrasound radiating and receiving device as defined in
claim 21, wherein increasing the number of electrode-finger pairs
in said first comb-shaped electrode makes the directionality of
said longitudinal wave sharper under a condition that the total
amount of all the finger-areas of said first comb-shaped electrode
is constant.
26. An ultrasound radiating and receiving device as defined in
claim 21, wherein said material is a liquid matter.
27. An ultrasound radiating and receiving device as defined in
claim 21, wherein said material is a cellular tissue.
28. An ultrasound radiating and receiving device as defined in
claim 21 further comprising a polymer film, with which said lower
end surface of said first comb-shaped electrode is coated.
29. An ultrasound radiating and receiving device as defined in
claim 21 further comprising: a first scanning unit composed of
groups X.sub.i (i=1, 2, . . . , n) of switches corresponding to the
electrode-fingers, respectively, of said first comb-shaped
electrode, one and the next of said groups X.sub.i having common
switches each other except the first switch of said one of said
groups X.sub.i and the last switch of said next of said groups
X.sub.i, and a second scanning unit composed of groups Y.sub.i
(i=1, 2, . . . , n) of switches corresponding to the
electrode-fingers, respectively, of said second comb-shaped
electrode, one and the next of said groups Y.sub.i having common
switches each other except the first switch of said one of said
groups Y.sub.i and the last switch of said next of said groups
Y.sub.i, said first comb-shaped electrode and said counter
electrode receiving input electric signals via said groups X.sub.i
in turn, and radiating longitudinal waves along the direction
vertical to said lower end surface of said first piezoelectric
substrate into said material through said surface-part of said
material in the form of a scanned ultrasound beam as a whole, and
then making said object reflect said scanned ultrasound beam back,
said second comb-shaped electrode and said counter electrode
detecting reflected and scanned ultrasound beams by means of said
groups Y.sub.i in turn as scanned electric signals, and imaging the
upper surface-shape of said object from said scanned electric
signals.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a device for radiating an
ultrasound into a material and receiving a reflected ultrasound by
means of using a piezoelectric substrate, an interdigital
arrangement of two comb-shaped electrodes formed on an upper end
surface of the piezoelectric substrate, a counter electrode formed
on a lower end surface of the piezoelectric substrate.
[0003] 2. Description of the Prior Art
[0004] A thickness mode piezoelectric transducer with parallel
plate-like electrodes is commonly used for radiating an ultrasound
into a liquid. When receiving a reflected ultrasound from the
liquid, such a conventional type of transducer needs, for example,
a circulator in order to separate a delayed electric signal from an
input electric signal, because the conventional type of transducer
is used both as input- and output electrodes. Accordingly, such the
conventional type of transducer has a difficulty in quick response
measurement, and a complicated circuit-construction. In addition,
such the conventional type of transducer has a difficulty in
scanning operation.
[0005] On the other hand, an interdigital transducer on the
piezoelectric substrate operates at a liquid-solid boundary as a
leaky wave transducer for bulk wave radiation into the liquid. The
leaky SAW traveling on a sufficiently thick substrate compared with
the wavelength has only one mode without velocity dispersion. Such
the interdigital transducer for the leaky SAW has a difficulty in
making the radiation angle vertical.
SUMMARY OF THE INVENTION
[0006] An object of the present invention is to provide an
ultrasound radiating and receiving device capable of making an
interdigital transducer act as a thickness mode transducer.
[0007] Another object of the present invention is to provide an
ultrasound radiating and receiving device operating with a quick
response.
[0008] Another object of the present invention is to provide an
ultrasound radiating and receiving device need not a circulator,
and so on.
[0009] Another object of the present invention is to provide an
ultrasound radiating and receiving device capable of scanning
operation.
[0010] Another object of the present invention is to provide an
ultrasound radiating and receiving device capable of imaging of an
object in a material.
[0011] Another object of the present invention is to provide an
ultrasound radiating and receiving device capable of making the
radiation angle vertical.
[0012] Another object of the present invention is to provide an
ultrasound radiating and receiving device capable of low electric
power consumption.
[0013] Another object of the present invention is to provide an
ultrasound radiating and receiving device capable of radiating an
ultrasound into a cellular tissue and receiving a reflected
signal.
[0014] Another object of the present invention is to provide an
ultrasound radiating and receiving device excellent in durability
and manufacturing.
[0015] A still other object of the present invention is to provide
an ultrasound radiating and receiving device easy in use and having
a small size which is very light in weight and has a simple
structure.
[0016] According to one aspect of the present invention there is
provided an ultrasound radiating and receiving device comprising a
piezoelectric substrate, first and second comb-shaped electrodes
formed on an upper end surface of the piezoelectric substrate, and
a counter electrode formed on a lower end surface of the
piezoelectric substrate. The counter electrode is in contact with a
surface-part of a material through the lower end surface of the
counter electrode. The first- and second comb-shaped electrodes
form an interdigital arrangement.
[0017] If an input electric signal is applied between the first
comb-shaped electrode and the counter electrode, a longitudinal
wave is radiated into the material through the surface-part of the
material along the direction vertical to the lower end surface of
the piezoelectric substrate. The, longitudinal wave is reflected at
an object located inside the material. And then, a reflected
longitudinal wave is detected between the second comb-shaped
electrode and the counter electrode as a delayed electric
signal.
[0018] According to another aspect of the present invention there
is provided an amplifier between the first- and second comb-shaped
electrodes. Thus, the delayed electric signal is amplified via the
amplifier, and supplied to the first comb-shaped electrode as the
input electric signal again.
[0019] According to another aspect of the present invention there
is provided an ultrasound radiating and receiving device, wherein
the opposite surface-part of the material acts as the object.
[0020] According to another aspect of the present invention there
is provided an ultrasound radiating and receiving device, wherein
the ratio of the interdigital periodicity of the interdigital
arrangement to the thickness of the piezoelectric substrate is
smaller than four times the ratio of the longitudinal wave velocity
in the material to the longitudinal wave velocity in the
piezoelectric substrate.
[0021] According to another aspect of the present invention there
is provided an ultrasound radiating and receiving device, wherein
increasing the number of electrode-finger pairs in the interdigital
arrangement makes the directionality of the longitudinal wave
sharper under a condition that the total amount of all the
finger-areas of the first comb-shaped electrode is constant.
[0022] According to another aspect of the present invention there
is provided an ultrasound radiating and receiving device, wherein
the material is a liquid matter.
[0023] According to another aspect of the present invention there
is provided an ultrasound radiating and receiving device, wherein
the material is a cellular tissue.
[0024] According to another aspect of the present invention there
is provided a polymer film, with which the lower end surface of the
counter electrode is coated.
[0025] According to another aspect of the present invention there
is provided a scanning unit composed of groups X.sub.i (i=1, 2, . .
. , n) of switches, which correspond to the electrode-fingers of
the first comb-shaped electrode, respectively. One and the next of
the groups X.sub.i have common switches each other except the first
switch of the one of the groups X.sub.i and the last switch of the
next of the groups X.sub.i.
[0026] If input electric signals are applied between the first
comb-shaped electrode and the counter electrode via the groups
X.sub.i in turn, longitudinal waves are radiated along the
direction vertical to the lower end surface of the piezoelectric
substrate into the material in the form of a scanned ultrasound
beam as a whole. The scanned ultrasound beam is reflected at the
object, and detected between the second comb-shaped electrode and
the counter electrode detecting as a scanned electric signal.
[0027] According to another aspect of the present invention there
are provided a first scanning unit composed of groups X.sub.i (i=1,
2, . . . , n) of switches corresponding to the electrode-fingers of
the first comb-shaped electrode, respectively, and a second
scanning unit composed of groups Y.sub.i (i=1, 2, . . . , n) of
switches corresponding to the electrode-fingers of the second
comb-shaped electrode, respectively. One and the next of the groups
X.sub.i have common switches each other except the first switch of
the one of the groups X.sub.i and the last switch of the next of
the groups X.sub.i. In the same way, one and the next of the groups
Y.sub.i have common switches each other except the first switch of
the one of the groups Y.sub.i and the last switch of the next of
the groups Y.sub.i.
[0028] If input electric signals are applied between the first
comb-shaped electrode and the counter electrode via the groups
X.sub.i in turn, longitudinal waves are radiated along the
direction vertical to the lower end surface of the piezoelectric
substrate into the material in the form of a scanned ultrasound
beam as a whole. The longitudinal waves are reflected at the
object, and detected between the second comb-shaped electrode and
the counter electrode by means of the groups Y.sub.i in turn in the
form of a scanned electric signal as a whole.
[0029] According to another aspect of the present invention there
is provided an ultrasound radiating and receiving device comprising
a first piezoelectric substrate, a first interdigital arrangement
of two comb-shaped electrodes, a second piezoelectric substrate, a
second interdigital arrangement of two comb-shaped electrodes, and
a counter electrode cemented between the first- and second
piezoelectric substrates. The first interdigital arrangement is
formed on a lower end surface of the first piezoelectric substrate.
A lower end surface of the first interdigital arrangement is in
contact with a surface-part of a material. The second interdigital
arrangement is formed on an upper end surface of the second
piezoelectric substrate.
[0030] If an input electric signal is applied between one of the
two comb-shaped electrodes in the first interdigital arrangement
and the counter electrode, a longitudinal wave is radiated into the
material through the surface-part of the material along the
direction vertical to the lower end surface of the first
piezoelectric substrate. The longitudinal wave is reflected at an
object located inside the material, and detected between one of the
two comb-shaped electrodes in the second interdigital arrangement
and the counter electrode as a delayed electric signal.
[0031] According to another aspect of the present invention there
is provided an ultrasound radiating and receiving device, wherein
the finger direction of the second interdigital arrangement is
orthogonal to that of the first interdigital arrangement.
[0032] According to another aspect of the present invention there
is provided an ultrasound radiating and receiving device, wherein
the finger width in the one of the two comb-shaped electrodes in
the first interdigital arrangement is wider than that in the other
of the two comb-shaped electrodes in the first interdigital
arrangement, and the finger width in the one of the two comb-shaped
electrodes in the second interdigital arrangement is wider than
that in the other of the two comb-shaped electrodes in the second
interdigital arrangement.
[0033] According to another aspect of the present invention there
is provided an ultrasound radiating and receiving device, wherein
the ratio of the interdigital periodicity of the first interdigital
arrangement to the thickness of the first piezoelectric substrate
is smaller than four times the ratio of the longitudinal wave
velocity in the material to the longitudinal wave velocity in the
first piezoelectric substrate.
[0034] According to another aspect of the present invention there
is provided an ultrasound radiating and receiving device, wherein
increasing the number of electrode-finger pairs in the first
interdigital arrangement makes the directionality of the
longitudinal wave sharper under a condition that the total amount
of all the finger-areas of the one of the two comb-shaped
electrodes in the first interdigital arrangement is constant.
[0035] According to another aspect of the present invention there
is provided a polymer film, with which the lower end surface of the
first interdigital arrangement is coated.
[0036] According to another aspect of the present invention there
are provided a first scanning unit composed of groups X.sub.i
(i=11, . . . , n) of switches corresponding to the
electrode-fingers, respectively, of the one of the two comb-shaped
electrodes in the first interdigital arrangement, and a second
scanning unit composed of groups Y.sub.i (i=11, . . . , n) of
switches corresponding to the electrode-fingers, respectively, of
the one of the two comb-shaped electrodes in the second
interdigital arrangement. One and the next of the groups X.sub.i
have common switches each other except the first switch of the one
of the groups X.sub.i and the last switch of the next of the groups
X.sub.i. In the same way, one and the next of the groups Y.sub.i
have common switches each other except the first switch of the one
of the groups Y.sub.i and the last switch of the next of the
groups. If input electric signals are applied between the one of
the two comb-shaped electrodes in the first interdigital
arrangement and the counter electrode via the groups X.sub.i in
turn, longitudinal waves are radiated along the direction vertical
to the lower end surface of the first piezoelectric substrate into
the material through the surface-part of the material in the form
of a scanned ultrasound beam as a whole. The scanned ultrasound
beam is reflected at the object, and detected between the one of
the two comb-shaped electrodes in the second interdigital
arrangement and the counter electrode by means of the groups
Y.sub.i in turn as scanned electric signals. Thus, the upper
surface-shape of the object is sensed from the scanned electric
signals.
[0037] According to another aspect of the present invention there
is provided an ultrasound radiating and receiving device
comprising, a first piezoelectric substrate, a first comb-shaped
electrode, a second piezoelectric substrate, a second comb-shaped
electrode, and a counter electrode cemented between the first- and
second piezoelectric substrates. The first comb-shaped electrode is
formed on a lower end surface of the first piezoelectric substrate.
A lower end surface of the first comb-shaped electrode is in
contact with a surface-part of a material. The second comb-shaped
electrode is formed on an upper end surface of the second
piezoelectric substrate.
[0038] If an input electric signal is applied between the first
comb-shaped electrode and the counter electrode, a longitudinal
wave is radiated into the material through the surface-part of the
material along the direction vertical to the lower end surface of
the first piezoelectric substrate. The longitudinal wave is
reflected at an object located inside the material, and detected
between the second comb-shaped electrode and the counter electrode
as a delayed electric signal.
[0039] According to another aspect of the present invention there
is provided an ultrasound radiating and receiving device, wherein
the finger direction of the second comb-shaped electrode is
orthogonal to that of the first comb-shaped electrode.
[0040] According to another aspect of the present invention there
is provided an ultrasound radiating and receiving device, wherein
the ratio of the interdigital periodicity of the first comb-shaped
electrode to the thickness of the first piezoelectric substrate is
smaller than four times the ratio of the longitudinal wave velocity
in the material to the longitudinal wave velocity in the first
piezoelectric substrate.
[0041] According to another aspect of the present invention there
is provided an ultrasound radiating and receiving device, wherein
increasing the number of electrode-finger pairs in the first
comb-shaped electrode makes the directionality of the longitudinal
wave sharper under a condition that the total amount of all the
finger-areas of the first comb-shaped electrode is constant.
[0042] According to other aspect of the present invention there is
provided a polymer film, with which the lower end surface of the
first comb-shaped electrode is coated.
[0043] According to a further aspect of the present invention there
are provided a first scanning unit composed of groups X.sub.i (i=1,
2, . . . , n) of switches corresponding to the electrode-fingers,
respectively, of the first comb-shaped electrode, and a second
scanning unit composed of groups Y.sub.i (i=1, 2, . . . , n) of
switches corresponding to the electrode-fingers, respectively, of
the second comb-shaped electrode. One and the next of the groups
X.sub.i have common switches each other except the first switch of
the one of the groups X.sub.i and the last switch of the next of
the groups X.sub.i. In the same way, one and the next of the groups
Y.sub.i have common switches each other except the first switch of
the one of the groups Y.sub.i and the last switch of the next of
the groups Y.sub.i.
[0044] If input electric signals are applied between the first
comb-shaped electrode and the counter electrode via the groups
X.sub.i in turn, longitudinal waves are radiated along the
direction vertical to the lower end surface of the first
piezoelectric substrate into the material through the surface-part
of the material in the form of a scanned ultrasound beam as a
whole. The scanned ultrasound beam is reflected at the object, and
detected between the second comb-shaped electrode and the counter
electrode by means of the groups Y.sub.i in turn as scanned
electric signals. Thus, the upper surface-shape of the object is
sensed from the scanned electric signals.
BRIEF DESCRIPTION OF THE DRAWINGS
[0045] Other features and advantages of the invention will be
clarified from the following description with reference to the
attached drawings.
[0046] FIG. 1 shows a sectional view of an ultrasound radiating and
receiving device according to a first embodiment of the present
invention.
[0047] FIG. 2 shows a fragmentary top plan view of interdigital
arrangement 2.
[0048] FIG. 3 shows a sectional view of an ultrasound radiating and
receiving device according to a second embodiment of the present
invention.
[0049] FIG. 4 shows a sectional view of an ultrasound radiating and
receiving device according to a third embodiment of the present
invention.
[0050] FIG. 5 shows a fragmentary top plan view of interdigital
arrangement 8 connected with scanning unit 7.
[0051] FIG. 6 shows a sectional view of an ultrasound radiating and
receiving device according to a fourth embodiment of the present
invention.
[0052] FIG. 7 shows a relationship between the relative amplitude
and the radiation angle of one of the seventeen longitudinal waves
into water from the ultrasound radiation device in FIG. 4.
[0053] FIG. 8 shows a top plan view of the finger overlap-zone of
interdigital arrangement 2.
[0054] FIG. 9 shows a top plan view of the finger overlap-zone of
interdigital arrangement 8.
[0055] FIG. 10 shows a sectional view of an ultrasound radiating
and receiving device according to a fifth embodiment of the present
invention.
[0056] FIG. 11 shows fragmentary a top plan view of interdigital
arrangement 8 connected with first scanning unit 10 and second
scanning unit 11.
[0057] FIG. 12 shows a sectional view of an ultrasound radiating
and receiving device according to a sixth embodiment of the present
invention.
[0058] FIG. 13 shows a sectional view of an ultrasound radiating
and receiving device according to a seventh embodiment of the
present invention.
[0059] FIG. 14 shows a schematic illustration of first interdigital
arrangement 13 and second interdigital arrangement 15.
[0060] FIG. 15 shows a sectional view of an ultrasound radiating
and receiving device according to an eighth embodiment of the
present invention.
[0061] FIG. 16 shows a sectional view of an ultrasound radiating
and receiving device according to a ninth embodiment of the present
invention.
[0062] FIG. 17 shows a schematic illustration of first interdigital
arrangement 13 and second interdigital arrangement 15.
[0063] FIG. 18 shows a sectional view of an ultrasound radiating
and receiving device according to a tenth embodiment of the present
invention.
[0064] FIG. 19 shows a sectional view of an ultrasound radiating
and receiving device according to an eleventh embodiment of the
present invention.
[0065] FIG. 20 shows a schematic illustration of first comb-shaped
electrode 16 and second comb-shaped electrode 17.
[0066] FIG. 21 shows a sectional view of an ultrasound radiating
and receiving device according to a twelfth embodiment of the
present invention.
[0067] FIG. 22 shows a sectional view of an ultrasound radiating
and receiving device according to a thirteenth embodiment of the
present invention.
[0068] FIG. 23 shows a schematic illustration of first comb-shaped
electrode 16 connected with first scanning unit 18, and second
comb-shaped electrode 17.
[0069] FIG. 24 shows a sectional view of an ultrasound radiating
and receiving device according to a fourteenth embodiment of the
present invention.
DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EXEMPLARY
EMBODIMENTS
[0070] FIG. 1 shows a sectional view of an ultrasound radiating and
receiving device according to a first embodiment of the present
invention. The ultrasound radiating and receiving device comprises
piezoelectric substrate 1, interdigital arrangement 2 of two
comb-shaped electrodes (2A and 2B), counter electrode 3, amplifier
4, and signal analyzer 5. Piezoelectric substrate 1 is made of a
piezoelectric ceramic plate with a thickness (T) of 500 .mu.m, and
the polarization axis thereof is parallel to the thickness
direction thereof. Interdigital arrangement 2, made of an aluminum
thin film, is formed on an upper end surface of piezoelectric
substrate 1. Counter electrode 3, made of an aluminum thin film, is
formed on a lower end surface of piezoelectric substrate 1. Thus,
the ultrasound radiating and receiving device in FIG. 1 has a small
size, which is very light in weight and has a simple structure. The
lower end surface of counter electrode 3 is in contact with a
surface-part of a material.
[0071] FIG. 2 shows a fragmentary top plan view of interdigital
arrangement 2. Interdigital arrangement 2 has fifteen
electrode-finger pairs, a finger-overlap length (L) of 5 mm, a
finger width (W) of 75 .mu.m, and an interdigital periodicity (P)
of 300 .mu.m. Interdigital arrangement 2 is composed of first
comb-shaped electrode 2A and second comb-shaped electrode 2B.
Amplifier 4 is connected between first comb-shaped electrode 2A and
second comb-shaped electrode 2B in FIG. 1.
[0072] In the ultrasound radiating and receiving device in FIG. 1,
if an input electric signal is applied between first comb-shaped
electrode 2A and counter electrode 3, a longitudinal wave is
radiated into the material through the surface-part of the
material. If the material is water, the longitudinal wave velocity
in water (V.sub.w) is approximately 1,500 m/s. On the other hand,
the longitudinal wave velocity in piezoelectric substrate 1 (V) is
4,500 m/s. Thus, the ratio of the V.sub.w value to the V value,
that is 1,500/4,500, is approximately 0.333. As a result, the ratio
of the interdigital periodicity (P) of interdigital arrangement 2
to the thickness (T) of piezoelectric substrate 1, that is 300/500,
is 0.6, which is still smaller than four times the ratio of the
V.sub.w value to the V value. Under such a condition of
P/T<4V.sub.w/V, the longitudinal wave along the direction
vertical to the lower end surface of piezoelectric substrate 1 is
effectively radiated into water. In the same way, the longitudinal
wave is effectively radiated into, for example, a cellular
tissue.
[0073] If the longitudinal wave is reflected at the opposite
surface-part of the material, as shown in FIG. 1, or at an object
located inside the material, a reflected longitudinal wave is
detected between second comb-shaped electrode 2B and counter
electrode 3 as a delayed electric signal, which is amplified via
amplifier 4, as well as detected at signal analyzer 5. An amplified
electric signal is supplied to first comb-shaped electrode 2A as
the input electric signal again. Thus, supplying comb-shaped
electrode 2A with the input electric signal via amplifier 4 causes
a self-oscillation, and moreover causes the circuit construction
simplified.
[0074] FIG. 3 shows a sectional view of an ultrasound radiating and
receiving device according to a second embodiment of the present
invention. The ultrasound radiating and receiving device has the
same construction as FIG. 1 except for the absence of amplifier 4
and the presence of signal generator 6.
[0075] In the ultrasound radiating and receiving device in FIG. 3,
if an input electric signal from signal generator 6 is applied
between first comb-shaped electrode 2A and counter electrode 3, a
longitudinal wave is radiated into the material through the
surface-part of the material. If the longitudinal wave is reflected
at the opposite surface-part of the material, as shown in FIG. 3, a
reflected longitudinal wave is detected between second comb-shaped
electrode 2B and counter electrode 3 as a delayed electric signal,
which arrives at signal analyzer 5.
[0076] FIG. 4 shows a sectional view of an ultrasound radiating and
receiving device according to a third embodiment of the present
invention. The ultrasound radiating and receiving device comprises
piezoelectric substrate 1, counter electrode 3, amplifier 4, signal
analyzer 5, scanning unit 7, interdigital arrangement 8 of two
comb-shaped electrodes (8A and 8B), and silicone rubber 9, with
which the lower end surface of counter electrode 3 is coated.
Silicone rubber 9 is in contact with a surface-part of a
material.
[0077] FIG. 5 shows a fragmentary top plan view of interdigital
arrangement 8 connected with scanning unit 7. Interdigital
arrangement 8 has twenty electrode-finger pairs, a finger-overlap
length (L) of 5 mm, a finger width (W) of 57 .mu.m, and an
interdigital periodicity (P) of 225 .mu.m. Interdigital arrangement
8 is composed of first comb-shaped electrode 8A connected with
amplifier 4 via scanning unit 7, and second comb-shaped electrode
8B connected with signal analyzer 5 in FIG. 4. Scanning unit 7 has
twenty switches corresponding to the electrode-fingers of first
comb-shaped electrode 8A, respectively. The twenty switches of
scanning unit 7 form seventeen groups X.sub.i (i=1, 2, . . . , 17),
of which each has four switches. In this way, one and the next of
the groups X.sub.i have three common switches each other except the
first switch of the one of the groups X.sub.i and the last switch
of the next of the groups X.sub.i. For example, the groups X.sub.2
and X.sub.3 have three common switches each other except the first
switch of the group X.sub.2 and the last switch of the group
X.sub.3.
[0078] In the ultrasound radiating and receiving device in FIG. 4,
if input electric signals are applied between counter electrode 3
and first comb-shaped electrode 8A via the groups X.sub.i in turn,
seventeen longitudinal waves are radiated into the material in
turn. In this way, the seventeen longitudinal waves are radiated in
the form of a scanned ultrasound beam as a whole into the material
through silicone rubber 9. When the material is water, the ratio of
the V.sub.w value to the V value is approximately 0.333, as
mentioned above. On the other hand, the ratio of the interdigital
periodicity (P) of interdigital arrangement 8 to the thickness (T)
of piezoelectric substrate 1, that is 225/500, is 0.45, which is
still smaller than four times the ratio of the V.sub.w value to the
V value. Under such a condition of P/T<4V.sub.w/V, the scanned
ultrasound beam along the direction vertical to the lower end
surface of piezoelectric substrate 1 is effectively radiated into
water through silicone rubber 9. In addition, the directionality of
the scanned ultrasound beam is sharper than that of the
longitudinal wave in FIG. 1. In other words, the smaller value P/T
than 4V.sub.w/V, the sharper directionality.
[0079] If the scanned ultrasound beam is reflected at the opposite
surface-part of the material, as shown in FIG. 4, a reflected
ultrasound beam is detected between counter electrode 3 and second
comb-shaped electrode 8B as a scanned electric signal, which is
amplified via amplifier 4, as well as detected at signal analyzer
5. An amplified electric signal is supplied to first comb-shaped
electrode 8A as the input electric signals again. Thus, supplying
comb-shaped electrode 8A with the input electric signals via
amplifier 4 causes a self-oscillation, and moreover causes the
circuit construction simplified.
[0080] FIG. 6 shows a sectional view of an ultrasound radiating and
receiving device according to a fourth embodiment of the present
invention. The ultrasound radiating and receiving device has the
same construction as FIG. 4 except for the absence of amplifier 4
and the presence of signal generator 6.
[0081] In the ultrasound radiating and receiving device in FIG. 6,
if input electric signals from signal generator 6 are applied
between counter electrode 3 and first comb-shaped electrode 8A via
the groups X.sub.i in turn, seventeen longitudinal waves are
radiated into the material in turn. In this way, the seventeen
longitudinal waves are radiated in the form of a scanned ultrasound
beam as a whole into the material through silicone rubber 9. If the
scanned ultrasound beam is reflected at the opposite surface-part
of the material, as shown in FIG. 6, a reflected ultrasound beam is
detected as a scanned electric signal between counter electrode 3
and second comb-shaped electrode 8B. Then, the scanned electric
signal arrives at signal analyzer 5.
[0082] FIG. 7 shows a relationship between the relative amplitude
and the radiation angle of one of the seventeen longitudinal waves
into water from the ultrasound radiation device in FIG. 4. It seems
that there exists only the main lobe, because any grating lobe is
suppressed. As a result, the use of interdigital arrangement 8
enables only a vertical radiation to the lower end surface of
piezoelectric substrate 1 into water. Thus, the longitudinal waves
are effectively radiated into, for example, a cellular tissue
through a skin, along a vertical direction to the lower end surface
of piezoelectric substrate 1.
[0083] FIG. 8 shows a top plan view of the finger overlap-zone of
interdigital arrangement 2.
[0084] FIG. 9 shows a top plan view of the finger overlap-zone of
interdigital arrangement 8. The finger overlap-zone of interdigital
arrangement 8 and that of interdigital arrangement 2 are the same
in size. In addition, the total amount of all the finger-areas of
comb-shaped electrode 8A is the same as that of comb-shaped
electrode 2A.
[0085] A comparison between FIGS. 8 and 9 indicates that
interdigital arrangement 8 and interdigital arrangement 2 are
different from each other with respect to the number of
electrode-finger pairs, the finger width (W), and the interdigital
periodicity (P). Actually, the number of electrode-pairs in
interdigital arrangement 8 is {fraction (4/3)} times that in
interdigital arrangement 2. At the same time, the interdigital
periodicity (P) of interdigital arrangement 8 is approximately 3/4
times that of interdigital arrangement 2, and the finger width (W)
of interdigital arrangement 8 is also 3/4 times that of
interdigital arrangement 2. It is recognized that the use of
interdigital arrangement 8 causes a sharper directionality of the
longitudinal wave than interdigital arrangement 2. This means that
increasing the number of electrode-finger pairs suppresses the
grating lobes still more under a condition that the total amount of
all the finger-areas of the first comb-shaped electrode is
constant. As a result, the number of electrode-finger pairs has
influence on the directionality of the longitudinal wave into a
material under the condition that the total amount of all the
finger-areas of the first comb-shaped electrode is constant.
[0086] FIG. 10 shows a sectional view of an ultrasound radiating
and receiving device according to a fifth embodiment of the present
invention. The ultrasound radiating and receiving device has the
same construction as FIG. 4 except for the absence of scanning unit
7, and the presence of first scanning unit 10 and second scanning
unit 11.
[0087] FIG. 11 shows fragmentary a top plan view of interdigital
arrangement 8 connected with first scanning unit 10 and second
scanning unit 11. First comb-shaped electrode 8A is connected with
amplifier 4 via first scanning unit 10, and second comb-shaped
electrode 8B is connected with signal analyzer 5 via second
scanning unit 11 in FIG. 10. First scanning unit 10 has twenty
switches corresponding to the electrode-fingers of first
comb-shaped electrode 8A, respectively. In the same way, second
scanning unit 11 has twenty switches corresponding to the
electrode-fingers of second comb-shaped electrode 8B, respectively.
The twenty switches of first scanning unit 10 form seventeen groups
X.sub.i (i=1, 2, . . . , 17), of which each has four switches. In
this way, one and the next of the groups X.sub.i have three common
switches each other except the first switch of the one of the
groups X.sub.i and the last switch of the next of the groups
X.sub.i. In the same way, the twenty switches of second scanning
unit 11 form seventeen groups Y.sub.i (i=1, 2, . . . , 17) under a
condition that each of the groups Y.sub.i has four switches. In
this time, one and the next of the groups Y.sub.i have three common
switches each other except the first switch of the one of the
groups Y.sub.i and the last switch of the next of the groups
Y.sub.i.
[0088] In the ultrasound radiating and receiving device in FIG. 10,
if input electric signals are applied between counter electrode 3
and first comb-shaped electrode 8A via the groups X.sub.i of first
scanning unit 10 in turn, seventeen longitudinal waves are radiated
in the form of a scanned ultrasound beam as a whole into the
material through silicone rubber 9. When the material is water, the
scanned ultrasound beam along the direction vertical to the lower
end surface of piezoelectric substrate 1 is effectively radiated
into water through silicone rubber 9 under the condition of
P/T<4V.sub.w/V.
[0089] If the seventeen longitudinal waves are reflected at the
opposite surface-part of the material, as shown in FIG. 10,
seventeen reflected longitudinal waves are detected as delayed
electric signals between counter electrode 3 and second comb-shaped
electrode 8B by means of the groups Y.sub.i in turn. In other
words, a scanned electric signal is detected as a whole between
counter electrode 3 and second comb-shaped electrode 8B by means of
the groups Y.sub.i of second scanning unit 11. The scanned electric
signal is amplified via amplifier 4, as well as detected at signal
analyzer 5. An amplified electric signal is supplied to first
comb-shaped electrode 8A as the input electric signals again. Thus,
supplying comb-shaped electrode 8A with the input electric signals
via amplifier 4 causes a self-oscillation, and moreover causes the
circuit construction simplified.
[0090] FIG. 12 shows a sectional view of an ultrasound radiating
and receiving device according to a sixth embodiment of the present
invention. The ultrasound radiating and receiving device has the
same construction as FIG. 10 except for the absence of amplifier 4
and the presence of signal generator 6.
[0091] In the ultrasound radiating and receiving device in FIG. 12,
if input electric signals from signal generator 6 are applied
between counter electrode 3 and first comb-shaped electrode 8A via
the groups X.sub.i of first scanning unit 10 in turn, seventeen
longitudinal waves are radiated in the form of a scanned ultrasound
beam as a whole into the material through silicone rubber 9. If the
scanned ultrasound beam is reflected at the opposite surface-part
of the material, as shown in FIG. 12, a scanned electric signal is
detected between counter electrode 3 and second comb-shaped
electrode 8B by means of the groups Y.sub.i of second scanning unit
11, and then the scanned electric signal arrives at signal analyzer
5.
[0092] FIG. 13 shows a sectional view of an ultrasound radiating
and receiving device according to a seventh embodiment of the
present invention. The ultrasound radiating and receiving device
comprises counter electrode 3, amplifier 4, signal analyzer 5,
silicone rubber 9, first piezoelectric substrate 12, first
interdigital arrangement 13 of two comb-shaped electrodes (13A and
13B), second piezoelectric substrate 14, and second interdigital
arrangement 15 of two comb-shaped electrodes (15A and 15B). First
interdigital arrangement 13, made of an aluminum thin film, is
formed on a lower end surface of first piezoelectric substrate 12.
Second interdigital arrangement 15, made of an aluminum thin film,
is formed on an upper end surface of second piezoelectric substrate
14. Counter electrode 3 is cemented between first piezoelectric
substrate 12 and second piezoelectric substrate 14, which are made
of the same materials as piezoelectric substrate 1, and have the
same sizes as piezoelectric substrate 1. The lower end surface of
first interdigital arrangement 13 is coated with silicone rubber 9,
which is in contact with a surface-part of a material.
[0093] FIG. 14 shows a schematic illustration of first interdigital
arrangement 13 composed of first comb-shaped electrode 13A and
second comb-shaped electrode 13B, and second interdigital
arrangement 15 composed of first comb-shaped electrode 15A and
second comb-shaped electrode 15B in the ultrasound radiating and
receiving device in FIG. 13. The finger direction of first
interdigital arrangement 13 is orthogonal to that of second
interdigital arrangement 15. First interdigital arrangement 13 has
twenty electrode-finger pairs, a finger-overlap length (L) of 5 mm,
and an interdigital periodicity (P) of 225 .mu.m. First comb-shaped
electrode 13A has a finger width (W.sub.A) of 45 .mu.m, and second
comb-shaped electrode 13B has a finger width (W.sub.B) of 12 .mu.m.
Second interdigital arrangement 15 has the same construction
pattern as first interdigital arrangement 13 except that first
comb-shaped electrode 15A has a finger width (W.sub.A) of 12 .mu.m,
and second comb-shaped electrode 15B has a finger width (W.sub.B)
of 45 .mu.m.
[0094] In the ultrasound radiating and receiving device in FIG. 13,
if an input electric signal is applied between first comb-shaped
electrode 13A and counter electrode 3, a longitudinal wave along
the direction vertical to the lower end surface of first
piezoelectric substrate 12 is radiated into the material through
silicone rubber 9. When the material is water, the condition of
P/T<4V.sub.w/V enables a radiation of the longitudinal wave
along the direction vertical to the lower end surface of first
piezoelectric substrate 12 into water. In addition, a condition of
W.sub.A/W.sub.B in first interdigital arrangement 13 makes the
directionality of the longitudinal wave sharper.
[0095] If the longitudinal wave is reflected at an object located
inside the material, as shown in FIG. 13, a reflected longitudinal
wave is detected between second comb-shaped electrode 15B and
counter electrode 3 as a delayed electric signal. In this time, the
directionality of the reflected longitudinal wave is still sharper
than that of the longitudinal wave radiated into the material,
because the finger direction of first interdigital arrangement 13
is orthogonal to that of second interdigital arrangement 15.
[0096] The delayed electric signal detected between second
comb-shaped electrode 15B and counter electrode 3 is amplified via
amplifier 4, as well as detected at signal analyzer 5. An amplified
electric signal is supplied to first comb-shaped electrode 13A as
the input electric signal again. Thus, first comb-shaped electrode
13A, amplifier 4, and second comb-shaped electrode 15B form a
self-oscillation type of delay-line oscillator.
[0097] FIG. 15 shows a sectional view of an ultrasound radiating
and receiving device according to an eighth embodiment of the
present invention. The ultrasound radiating and receiving device
has the same construction as FIG. 13 except for the absence of
amplifier 4 and the presence of signal generator 6.
[0098] In the ultrasound radiating and receiving device in FIG. 15,
if an input electric signal from signal generator 6 is applied
between first comb-shaped electrode 13A and counter electrode 3, a
longitudinal wave along the direction vertical to the lower end
surface of first piezoelectric substrate 12 is radiated into the
material through silicone rubber 9. If the longitudinal wave is
reflected at an object located inside the material, as shown in
FIG. 15, a reflected longitudinal wave is detected between second
comb-shaped electrode 15B and counter electrode 3 as a delayed
electric signal, which arrives at signal analyzer 5.
[0099] FIG. 16 shows a sectional view of an ultrasound radiating
and receiving device according to a ninth embodiment of the present
invention. The ultrasound radiating and receiving device has the
same construction as FIG. 13 except for the presence of first
scanning unit 10 and second scanning unit 11.
[0100] FIG. 17 shows a schematic illustration of first interdigital
arrangement 13 connected with first scanning unit 10, and second
interdigital arrangement 15 connected with second scanning unit 11.
First interdigital arrangement 13 is connected with amplifier 4 via
first scanning unit 10, and second interdigital arrangement 15 is
connected with signal analyzer 5 via second scanning unit 11 in
FIG. 16. The electrode-fingers of first comb-shaped electrode 13A
correspond with the twenty switches of first scanning unit 10,
respectively. In the same way, the electrode-fingers of second
comb-shaped electrode 15B correspond with the twenty switches of
second scanning unit 11, respectively. The twenty switches of first
scanning unit 10 form seventeen groups X.sub.i (i=1, 2, . . . ,
17), of which each has four switches. In this way, one and the next
of the groups X.sub.i have three common switches each other except
the first switch of the one of the groups X.sub.i and the last
switch of the next of the groups X.sub.i. On the other hand, the
twenty switches of second scanning unit 11 form eighteen groups
Y.sub.i (i=1, 2, . . . , 18) under a condition that each of the
groups Y.sub.i has three switches. In this time, one and the next
of the groups Y.sub.i have two common switches each other except
the first switch of the one of the groups Y.sub.i and the last
switch of the next of the groups Y.sub.i.
[0101] In the ultrasound radiating and receiving device in FIG. 16,
if input electric signals are applied between counter electrode 3
and first comb-shaped electrode 13A via the groups X.sub.i in turn,
seventeen longitudinal waves along the direction vertical to the
lower end surface of first piezoelectric substrate 12 are radiated
into the material in turn. In this way, the seventeen longitudinal
waves are radiated in the form of a scanned ultrasound beam as a
whole into the material through silicone rubber 9. When the
material is water, the condition of P/T<4V.sub.w/V enables a
radiation of the scanned ultrasound beam along the direction
vertical to the lower end surface of first piezoelectric substrate
12 into water.
[0102] If the scanned ultrasound beam is reflected at an object
located inside the material, as shown in FIG. 16, a reflected and
scanned ultrasound beam is detected as a scanned electric signal
between counter electrode 3 and second comb-shaped electrode 15B by
means of each of the groups Y.sub.i. In other words, eighteen
reflected and scanned ultrasound beams are detected as eighteen
scanned electric signals between counter electrode 3 and second
comb-shaped electrode 15B by means of the eighteen groups Y.sub.i
in turn. As a result, the upper-surface shape of the object is
imaged from the scanned electric signals at signal analyzer 5.
[0103] On the other hand, the scanned electric signals are
amplified via amplifier 4, as well as detected at signal analyzer
5. Thus, amplified electric signals are supplied to first
comb-shaped electrode 13A as the input electric signals again. As a
result, first comb-shaped electrode 13A, amplifier 4, and second
comb-shaped electrode 15B form a self-oscillation type of
delay-line oscillator.
[0104] FIG. 18 shows a sectional view of an ultrasound radiating
and receiving device according to a tenth embodiment of the present
invention. The ultrasound radiating and receiving device has the
same construction as FIG. 16 except for the absence of amplifier 4
and the presence of signal generator 6.
[0105] In the ultrasound radiating and receiving device in FIG. 18,
if input electric signals from signal generator 6 are applied
between counter electrode 3 and first comb-shaped electrode 13A via
the groups X.sub.i in turn, seventeen longitudinal waves along the
direction vertical to the lower end surface of first piezoelectric
substrate 12 are radiated into the material in turn. In this way,
the seventeen longitudinal waves are radiated in the form of a
scanned ultrasound beam as a whole into the material through
silicone rubber 9. If the scanned ultrasound beam is reflected at
an object located inside the material, as shown in FIG. 18, a
reflected and scanned ultrasound beam is detected as a scanned
electric signal between counter electrode 3 and second comb-shaped
electrode 15B by means of each of the groups Y.sub.i. In other
words, eighteen reflected and scanned ultrasound beams are detected
as eighteen scanned electric signals between counter electrode 3
and second comb-shaped electrode 15B by means of the eighteen
groups Y.sub.i in turn. And then, the scanned electric signals
arrive at signal analyzer 5. As a result, the upper-surface shape
of the object is imaged from the scanned electric signals.
[0106] FIG. 19 shows a sectional view of an ultrasound radiating
and receiving device according to an eleventh embodiment of the
present invention. The ultrasound radiating and receiving device
has the same construction as FIG. 13 except for the presence of
first comb-shaped electrode 16 and second comb-shaped electrode 17
in place of first interdigital arrangement 13 and second
interdigital arrangement 15, respectively.
[0107] FIG. 20 shows a schematic illustration of first comb-shaped
electrode 16 and second comb-shaped electrode 17. First comb-shaped
electrode 16 has forty electrode-fingers, a finger-overlap length
(L) of 5 mm, a finger width (W) of 175 .mu.m, and an interdigital
periodicity (P) of 225 .mu.m. Second comb-shaped electrode 17 has
the same construction pattern as first comb-shaped electrode 16, of
which the finger direction is orthogonal to that of second
comb-shaped electrode 17.
[0108] In the ultrasound radiating and receiving device in FIG. 19,
if an input electric signal is applied between first comb-shaped
electrode 16 and counter electrode 3, a longitudinal wave along the
direction vertical to the lower end surface of first piezoelectric
substrate 12 is radiated into the material through silicone rubber
9. When the material is water, the condition of P/T<4V.sub.w/V
enables a radiation of the longitudinal wave along the direction
vertical to the lower end surface of first piezoelectric substrate
12 into water.
[0109] If the longitudinal wave is reflected at an object located
inside the material, as shown in FIG. 19, a reflected longitudinal
wave is detected between second comb-shaped electrode 17 and
counter electrode 3 as a delayed electric signal. In this time, the
directionality of the reflected longitudinal wave is still sharper
than that of the longitudinal wave radiated into the material,
because the finger direction of first comb-shaped electrode 16 is
orthogonal to that of second comb-shaped electrode 17. In addition,
first comb-shaped electrode 16, amplifier 4, and second comb-shaped
electrode 17 form a self-oscillation type of delay-line
oscillator.
[0110] FIG. 21 shows a sectional view of an ultrasound radiating
and receiving device according to a twelfth embodiment of the
present invention. The ultrasound radiating and receiving device
has the same construction as FIG. 19 except for the absence of
amplifier 4 and the presence of signal generator 6.
[0111] In the ultrasound radiating and receiving device in FIG. 21,
if an input electric signal from signal generator 6 is applied
between first comb-shaped electrode 16 and counter electrode 3, a
longitudinal wave along the direction vertical to the lower end
surface of first piezoelectric substrate 12 is radiated into the
material through silicone rubber 9. If the longitudinal wave is
reflected at an object located inside the material, as shown in
FIG. 21, a reflected longitudinal wave is detected between second
comb-shaped electrode 17 and counter electrode 3 as a delayed
electric signal, which arrives at signal analyzer 5.
[0112] FIG. 22 shows a sectional view of an ultrasound radiating
and receiving device according to a thirteenth embodiment of the
present invention. The ultrasound radiating and receiving device
has the same construction as FIG. 19 except for the presence of
first scanning unit 18 and second scanning unit 19.
[0113] FIG. 23 shows a schematic illustration of first comb-shaped
electrode 16 connected with first scanning unit 18, and second
comb-shaped electrode 17 connected with second scanning unit 19.
First comb-shaped electrode 16 is connected with amplifier 4 via
first scanning unit 18, and second comb-shaped electrode 17 is
connected with signal analyzer 5 via second scanning unit 19 in
FIG. 22. First scanning unit 18 has forty switches corresponding to
the electrode-fingers of first comb-shaped electrode 16,
respectively. In the same way, second scanning unit 19 has forty
switches corresponding to the electrode-fingers of second
comb-shaped electrode 17, respectively. The forty switches of first
scanning unit 18 form thirty-five groups X.sub.i (i=1, 2, . . . ,
35), of which each has six switches. In this way, one and the next
of the groups X.sub.i have five common switches each other except
the first switch of the one of the groups X.sub.i and the last
switch of the next of the groups X.sub.i. On the other hand, the
forty switches of second scanning unit 19 form thirty-seven groups
Y.sub.i (i=1, 2, . . . , 37) under a condition that each of the
groups Y.sub.i has four switches. In this time, one and the next of
the groups Y.sub.i have three common switches each other except the
first switch of the one of the groups Y.sub.i and the last switch
of the next of the groups Y.sub.i.
[0114] In the ultrasound radiating and receiving device in FIG. 22,
if input electric signals are applied between counter electrode 3
and first comb-shaped electrode 16 via the groups X.sub.i in turn,
thirty-five longitudinal waves along the direction vertical to the
lower end surface of first piezoelectric substrate 12 are radiated
into the material in turn. In this way, the thirty-five
longitudinal waves are radiated in the form of a scanned ultrasound
beam as a whole into the material through silicone rubber 9. When
the material is water, the condition of P/T<4V.sub.w/V enables a
radiation of the scanned ultrasound beam along the direction
vertical to the lower end surface of first piezoelectric substrate
12 into water.
[0115] If the scanned ultrasound beam is reflected at an object
located inside the material, as shown in FIG. 22, a reflected and
scanned ultrasound beam is detected as a scanned electric signal
between counter electrode 3 and second comb-shaped electrode 17 by
means of each of the groups Y.sub.i. In other words, thirty-seven
reflected and scanned ultrasound beams are detected as thirty-seven
scanned electric signals between counter electrode 3 and second
comb-shaped electrode 17 by means of the thirty-seven groups
Y.sub.i in turn. As a result, the upper-surface shape of the object
is imaged from the scanned electric signals at signal analyzer
5.
[0116] On the other hand, the scanned electric signals are
amplified via amplifier 4, as well as detected at signal analyzer
5. Thus, amplified electric signals are supplied to first
comb-shaped electrode 16 as the input electric signals again. As a
result, first comb-shaped electrode 16, amplifier 4, and second
comb-shaped electrode 17 form a self-oscillation type of delay-line
oscillator.
[0117] FIG. 24 shows a sectional view of an ultrasound radiating
and receiving device according to a fourteenth embodiment of the
present invention. The ultrasound radiating and receiving device
has the same construction as FIG. 22 except for the absence of
amplifier 4 and the presence of signal generator 6.
[0118] In the ultrasound radiating and receiving device in FIG. 24,
if input electric signals from signal generator 6 are applied
between counter electrode 3 and first comb-shaped electrode 16 via
the groups X.sub.i in turn, thirty-five longitudinal waves along
the direction vertical to the lower end surface of first
piezoelectric substrate 12 are radiated into the material in turn.
In this way, the thirty-five longitudinal waves are radiated in the
form of a scanned ultrasound beam as a whole into the material
through silicone rubber 9. If the scanned ultrasound beam is
reflected at an object located inside the material, as shown in
FIG. 24, a reflected and scanned ultrasound beam is detected as a
scanned electric signal between counter electrode 3 and second
comb-shaped electrode 17 by means of each of the groups Y.sub.i. In
other words, thirty-seven reflected and scanned ultrasound beams
are detected as thirty-seven scanned electric signals between
counter electrode 3 and second comb-shaped electrode 17 by means of
the thirty-seven groups Y.sub.i in turn. And then, the scanned
electric signals arrive at signal analyzer 5. As a result, the
upper-surface shape of the object is imaged from the scanned
electric signals.
[0119] While this invention has been described in connection with
what is presently considered to be the most practical and preferred
embodiment, it is to be understood that the invention is not
limited to the disclosed embodiment, but, on the contrary, is
intended to cover various modifications and equivalent arrangements
included within the spirit and scope of the appended claims.
* * * * *