close

Вход

Забыли?

вход по аккаунту

?

DESCRIPTION JPS6055798

код для вставкиСкачать
Patent Translate
Powered by EPO and Google
Notice
This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or
financial decisions, should not be based on machine-translation output.
DESCRIPTION JPS6055798
[0001]
FIELD OF THE INVENTION The present invention relates to an ultrasonic transducer required for
ultrasonic measurement in the air. The structure of the conventional example and the problems
thereof A piezoelectric ceramic bonded element is often used in a reservoir for transmitting and
receiving ultrasonic waves in air, and the resonance point of the flexural vibration of the bonded
element is The mechanical impedance of air is made to be used at the antiresonance point. Also,
since the mechanical impedance of air is significantly smaller than that of piezoelectric ceramics,
the bonded piezoelectric element is combined with the diaphragm to reduce the mechanical
impedance. I am trying. The structure and characteristics of a conventional ultrasonic transducer
are shown in FIGS. 1 and 2, respectively. As shown in FIG. 1, the connecting shaft 2 is fixed to the
center of the bonding type piezoelectric element 1 in a penetrating manner, and the diaphragm 3
is attached to the connecting shaft 2. Then, the node of the vibration of the bonding type
piezoelectric element 1 is fixed to the tip of the support 4 with the elastic adhesive 5. 6, 6 'are
terminals, 7 is a case covering the bonding type piezoelectric element 1, etc., 8 is a mesh for
protection attached to a through hole formed in the upper part of the case 7, 9, 9' The lead wire
electrically connects the mating piezoelectric element 1 to the terminals 6 and 6 '. Fig. 2 shows
the transmission and reception waveforms when the ultrasonic transducer of the above structure
is driven by a plurality of pulses, and the rise and fall times are delayed, extending over 2
milliseconds or more. there were. When it is necessary to obtain measurement information at
short time intervals using such a conventional ultrasonic transducer, the signal received by the
receiver has a long rise time and a long fall time. It takes time to reach the peak value.
Alternatively, accurate measurement information could not be obtained, for example, the next
signal was received before the fall of the received signal. In addition, when transmitting and
receiving waves are performed by a single element, it takes a considerable amount of time to
transmit and immediately receive signals, during which measurement and extinction can not be
13-04-2019
1
obtained. Furthermore, when sharp directivity characteristics are required of an ultrasonic
transducer using piezoelectric ceramics, there is a disadvantage that the diaphragm, the bonding
type piezoelectric element, and the base for supporting the bonding type piezoelectric element
become extremely large. . Even if a large diaphragm is used, it is difficult to make the piston
vibrate so that it is impossible to sharpen the directivity characteristic significantly. Therefore, if
it is attempted to sharpen the directivity characteristics using a horn, it has become more difficult
to lower the mechanical Q and improve the pulse characteristics. SUMMARY OF THE INVENTION
It is an object of the present invention to provide an ultrasonic transducer having good transient
characteristics and transmission / reception sensitivity characteristics.
Configuration of the Invention According to the present invention, a diaphragm is provided at the
center of the bonded piezoelectric element, and the periphery of the diaphragm is elastically
fixed to the case with an elastic material such as elastic rubber so as to suppress mechanical
vibration. In addition, an ultrasonic transducer having sharp transient characteristics is realized,
and transmission / reception sensitivity characteristics and temperature characteristics are
improved. Description of Embodiment V Hereinafter, an embodiment of the present invention will
be described with reference to the drawings. FIG. 3 is a cross-sectional view of the ultrasonic
transducer of this embodiment. A diaphragm 13 made of metal or resin is attached to a joint
shaft 12 disposed at the center of the bonded piezoelectric element 11. The peripheral portion of
the diaphragm 130 is elastically fixed to the inner side surface of the cylindrical case 17 via a
buffer material 20 such as elastic rubber formed in an annular shape so as to suppress
mechanical vibration. A sound absorbing material 21 is provided at the bottom of the case 17. In
the front of the diaphragm 13, a thin plate 23 having a circular opening 22 at the center and
other openings 22 'and 22' provided on the concentric circle around a straight line passing
through the connecting shaft 12 Is installed. The thin plate 23 and the case 17 covering the
bonded piezoelectric element 11 and the like are fitted and held in the throat of the parabolic
horn 24. 19.19 'is a lead wire electrically connecting the bonding type piezoelectric element 11
and the terminals 1e and 16'. The openings 22.22 'and 22' 'of the thin plate 23 depend on the
size and thickness of the bonding type piezoelectric element 11, the size, thickness and central
angle of the diaphragm 13, the inner diameter of the shock absorbing material 20, etc. , The
optimal shape is different. The representative one is shown in FIG. The resonance frequency f is
determined by the size and shape of the openings 22.22 'and 22 "of the thin plate 23, the
thickness of the thin plate 23, the volume between the thin plate 23 and the diaphragm 13, and
the like. Is set to a value ranging from the resonant frequency fr of the bonding type piezoelectric
element 11 having the diaphragm 13 elastically fixed by the buffer material 2o at the central
portion to the antiresonant frequency. Next, transient characteristics of the ultrasonic transducer
according to the structure of the present invention are shown in FIG. The rise and fall times of
the pulse became 0.2 ms or less. In FIG. 6, the resonance frequency fl + antiresonance frequency
fa of the bonding type piezoelectric element 11 having the diaphragm 13 elastically fixed by the
buffer material 20 at the central portion, the openings 22.22 ', 22', thin plate 23 shows the
13-04-2019
2
frequency characteristics of the transmission sound pressure level and the reception sensitivity
of the present ultrasonic transducer when the relationship between the resonance frequency f o
determined by the same volume of the diaphragm 13 and the like is changed.
f<fr’!、たはf。 In the case of <>, at each maximum frequency, the transmission sound
pressure level was about 123 dB and the reception sensitivity was about -s ei dB. By setting fo to
satisfy fr ≦ fc ≦ fa, it has become clear that the transmission sound pressure Renovope
reception sensitivity has increased. In addition, the frequency characteristics of the transmission
sound pressure level and the reception sensitivity change with the change of the ambient
temperature. This change is caused by the wavelength .lambda. Which resonates due to the
openings 22.22 ', 22 ", the capacitance between the thin plate 23 and the diaphragm 130, and
the like. Is approximately constant independently of temperature, while the speed of sound is
changed, so that the resonance frequency fo is caused by the change according to the equation
shown by f0 = .1 / .lambda.0. However, as shown in FIG. 6 (-), (when it is clear from (→, the
present ultrasonic transducer is approximately Cfo-3) klk to Cfc-j) transmission frequency by
using the transmission frequency The temperature characteristics of pressure level and receiving
sensitivity have been significantly improved. Curves A and B in the figure indicate the
transmission sound pressure level, and curves C and D indicate the reception sensitivity. Effect of
the Invention As described above, the ultrasonic transducer according to the present invention
has excellent transient characteristics and high transmission / reception sensitivity
characteristics, and is extremely useful for ultrasonic application measurement such as a distance
meter using a sound wave. It is.
[0002]
Brief description of the drawings
[0003]
FIG. 1 is a cross-sectional view showing an example of a conventional ultrasonic transducer, FIG.
2 is a diagram showing its transient characteristics, and FIG. 3 is a cross-sectional view showing
an embodiment of the ultrasonic transducer of the present invention. Fig. 4 is a front view
showing an embodiment of the thin plate of the ultrasonic transducer, Fig. 6 is a diagram
showing transient characteristics of the ultrasonic transducer, and Fig. 6 is a sensitivity of the
ultrasonic transducer. Temperature change of frequency characteristics and resonance frequency
f.
13-04-2019
3
It is a figure which shows the relationship with the setting conditions of. . 11 · · · · · · Bonding type
piezoelectric element, 13 · · · · · · · diaphragm 20 · · · · · · · · · · · · · · · · · sound absorbing material, 22
2i. 22 '...... Name of Agent Attorney Nakao Toshio Other 1 person Figure 1 Figure 2 Figure 3
Figure 5
13-04-2019
4
Документ
Категория
Без категории
Просмотров
0
Размер файла
12 Кб
Теги
jps6055798, description
1/--страниц
Пожаловаться на содержимое документа