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Description 1, title of the invention
Acoustic pressure sensor with multiple polymer configurations
3, Detailed Description of the Invention The present invention is a polymer polymer pressure!
The invention relates to an ultrasound transducer with phase activated membrane. Polymeric
piezoelectric films have recently been applied as transducers for ultrasound in liquid and also for
airborne ultrasound, due to their low acoustic impedance and favorable flexibility. However, in
this type of transducer, the electroacoustic transducing efficiency is not sufficient when it is
applied to a conventional device using a transducer with an inorganic rolled material. It is an
object of the present invention to provide an ultrasonic transducer in a liquid or an air which has
obtained a total of 9 improvements in the acoustic sound conversion efficiency from such a
polymeric piezoelectric film. According to the present invention, a plurality of curved polymer
pressure [m] having metal electrodes deposited on both front and back sides is a distance
between the polymer piezoelectric films as a half wavelength of the sound wave in the sound
field medium or an integral multiple thereof. To electrically connect the front and back electrodes
of each piezoelectric film in parallel so that ultrasonic waves having a phase that satisfies the
phase matching condition are emitted, and serve as input / output electrical terminals. An
ultrasonic transducer is provided comprising a polymeric piezoelectric film of t-characteristic
configuration. Hereinafter, the present invention will be described in detail with reference to the
drawings. As shown in FIG. 1, EndPage: 1, which has been subjected to a stretching process, is
attached with metal electrodes 2, 2 'on the front and back of a known polymeric piezoelectric
film 1 such as polyvinylidene fluoride, and AC voltage e is applied between the front and back
electrodes. When applied, pressure is generated in the membrane 1 by stretching vibration 3.3
'parallel to the membrane surface. Therefore, if this piezoelectric film 1 is curved as shown in
FIG. 2 and both ends 4, 4 'are fixed, the stretching vibration of the film can be converted to the
piston movement 5 perpendicular to the film surface, thus the film surface is acoustically Sound
waves can be emitted as the emitting surface. I used this to convert the curvature into a
converter. FIG. 3 shows an embodiment according to the present invention. A plurality of curved
transducers 1a, 1b, 1c,... 1n as shown in FIG. Are arranged. 6, 6 'are input / output electric
terminals, which are connected to an AC voltage. Here, each curved transducer is configured to
be excited in an independent vibration mode. When the polarization directions of the respective
curved transducers are aligned in the same direction, the intervals 7a, 7b, ... of the respective
curved transducers are configured to be half wavelengths, and the respective piezoelectric films
If the polarities of the front and back electrodes are alternately reversed and electrically
connected in parallel, the ultrasonic waves emitted independently from the respective curved
transducers satisfy the phase matching condition and thus receive an axial direction far enough
from the transducer. At the sound point, the output sound pressure is superimposed.
Therefore, an increase in output sound pressure proportional to the number of curved
transducers with respect to the same manual voltage can be obtained. If the polarization
directions of the curved m-transducers are not aligned in the configuration of FIG. 3, electrical
connection should be performed so that the ultrasonic waves emitted from the respective
piezoelectric films satisfy the phase matching conditions. good. By changing the distance
between the curved transducers and the size of the piezoelectric film, it is possible to change the
specific direction in which the output sound pressure is superimposed. Also, a panful plate is
provided around each curved m-converter, and the distance from one end of the baffle plate to
the other end of the other buckle plate via the piezoelectric film is adjusted in relation to the
wavelength, and the wave diffraction effect To make the sound pressure increase effect in%
direction remarkable by breaking the gold film on the wall surface so as to have an acoustic
whitening effect in a direction parallel to the vibration direction of the piezoelectric film instead
of the baffle plate. it can. In FIG. 3, one embodiment according to the present invention has been
completely described for the case where a curved transducer is applied, but in the present
invention, it is not necessary to be a curved transducer, and an omnidirectional cylindrical or
partially It may be in the shape of a truncated cylinder or a sphere, or in the shape of a sphere,
such as a hemisphere. In order to maintain such a shape, a suitable method may be employed
such as supporting with an elastic material 'R having a small sound absorbing property; As the
polymeric piezoelectric film used in the present invention, vinylidene fluoride homopolymers,
vinylidene fluoride copolymers, vinylidene fluoride-based fats such as a composition containing
any of these as a main component, vinyl fluoride resin, and further For the composition, a
composition in which a piezoelectric substance is dispersed in a general polymer, a laminate
having any of these as a layer, or the like is used, and a vinylidene fluoride resin is most
preferable. Next, as another embodiment according to the present invention, an airborne
transducer using a polyvinylidene fluoride piezoelectric film will be described in detail. FIG. 4 is a
perspective view of the case where five polyvinylidene fluoride piezoelectric films 1a to 1e are
stacked. The dimensions of the piezoelectric film were 40 m О 40 m and the radius of curvature
was 40 magazines, and the distance between the piezoelectric films was set to 12 attacks
(although they are stretched and displayed in the drawing). Both ends AB of each piezoelectric
film 1a to 1e and CD were fixed by a metal frame (not shown), and AC and BD were supported by
a metal frame (not shown). In this case, the metal frame does not touch the metal electrodes 2
and 2 'of the piezoelectric film. Since the polarization directions of the respective piezoelectric
films are overlapped so as to be the same direction, the connection between the electrodes is not
shown, but is made in the same manner as FIG.
When this transducer is used and the frequency is about 14 KHz, the output voltage for a single
piezoelectric film is shown as O dB as a relative sound pressure level. EndPage: 2 gives an output
sound pressure that can cause 14 dB at a certain angle. . As such according to the invention) 1.
Nasal acoustic stress levels ? 5 can be significantly altered, and can provide particularly
preferred airborne ultrasonic transducers in liquid or air.
4. Brief description of the drawings FIG. 1 is an explanatory view showing the piezoelectric action
of the polymeric piezoelectric film, FIG. 2 is an explanatory view of the electroacoustic
transducing action of the polymeric piezoelectric film, and FIG. 3 is a specific example according
to the present invention FIG. 4 is a perspective view of another embodiment according to the
present invention. la, lb иии Piezoelectric film, 2.2 ? и и и и и и crown, 3.31
иииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииии Four-piece piezoelectric back ends, 5 ............... 14 old piezoelectric
length of the piston ? internal thread direction, 6.6 '......'s output' 4 gas terminal, 7a , 7b ... n cup
pressure '? good range. It's one-to-one IllIZi two-to-one: #:: I's one-figure [F] [F] \ '11: 1 EndPage:
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description, jps55115800
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