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BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view of a conventional
ultrasonic transducer, FIGS. 2 to 4 show an embodiment of an ultrasonic transducer according to
the present invention, and FIG. 3 is an exploded perspective view, FIG. 4 is an explanatory view
showing the dimension symbols of the main members, FIG. 5 is a sensitivity characteristic
diagram of the conventional example, and FIGS. 6.7 and 8.9 are both sensitivity characteristics in
this embodiment. FIG. 10 ··· · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · composite
oscillator, 11 · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · ·
additional resonators, 13 · · · · · · · · · · · · · · Recessed part.
DETAILED DESCRIPTION OF THE INVENTION The present invention is an ultrasonic transducer
ho for transmitting or receiving ultrasonic signals suitable for use in a remote control device of a
television receiver, an alarm or the like. In particular, the present invention relates to a
transmitter / receiver for obtaining a large transmission / reception MIl & degree over a wide
frequency band. As this bridge ultrasonic transducer, a longitudinal cross-sectional trapezoidal
shaped additional resonator (hereinafter referred to as a "bed-carving co-imager") or an
aluminum-foil-shaped additional resonator (hereinafter referred to as a "rib-cone") is made There
is known a book provided with a canon resonator). And the one using the latter aluminum canon
resonator is (t) 5. , / F 3 / gi sensitivity c main sensitivity) and the frequency between the
frequency point with small sensitivity but the frequency point with the second sensitivity (sub M
degree) is very wide, the middle frequency region It is extremely difficult to obtain a large
sensitivity over a wide frequency band, since most practical and usable sensitivities can not be
obtained. On the other hand, in the former case where nine resin trapezoidal resonators are used,
the frequency gap between the frequency point at which the sensitivity of all is obtained and the
frequency Ik at which the sensitivity of @ 2 is considered is relatively narrow. Wide frequency
bandwidth is satisfactory). By devising the shape of the trapezoidal resonator, a sensitivity
(delivery) of a degree of @ 5 FIG. 17 can be obtained. As indicated by a single point of this
sensitivity, the characteristics over a wide frequency band show the results of measurement
conducted on the transducer having the structure shown in FIG. In FIG. 2K, a composite vibrator
1 is formed by fixing a resin-made trapezoidal resonator 6 near the center of one side of the
ceramic bimorph vibrator 2. The composite vibrator l is fixed by interposing the support member
5 in the dark of the substrate 4 h K, the substrate 4 and the bimorph vibrator 2 (2). 6 is a shield
plate and 7 is an outer case. Then, by further increasing the sensitivity of the intermediate region
between the frequency points where two large confusions can be obtained, a hole is provided
near the center of the 1: part of the trapezoidal resonator 3 to obtain a large sensitivity on the
high frequency side. It is sufficient to stop lowering the frequency band. The sensitivity curve of
this message is shown in FIG. This property is practically satisfactory. However, when an external
cait-off is attached as shown in the first place, the sensitivity characteristic is greatly attenuated
in the intermediate frequency range as indicated by the solid line in FIG. ! It is obvious that it can
not be put to practical use as a container. Therefore, this idea is to attach large size g, ii over a
wide frequency band by attaching a composite vibrator provided with a trapezoidal co-imager
made of a ceramic bimorph vibrator to a recess formed on a substrate. It is an object of the
present invention to provide an ultrasonic transducer.
Hereinafter, embodiments of the present invention will be described in detail with reference to
the drawings. In FIG. IIE 21 and 5, 10 is a composite vibrator, which is formed by bonding a resin
additional condenser 12 with an adhesive to the central part of one side of a square (3) plate-like
pressure tk ramic bimorph oscillator 1. The bimorph oscillator 11 is formed by bonding two
piezoelectric upper-lamic plates 4 together, and the additional co-observer 12 has a trapezoidal
cross-section with a vertical cross-section of 1111 in a circular cross-section. The short side
surface of the trapezoid is in contact with the bimorph oscillator 111C, and the long side surface
functions as an ultrasonic wave transmission (or reception) surface. Reference numeral 13
denotes a substrate, and a circular recess 14 is provided on one side. The bottom surface -K in
the recess 14 and the composite vibrator 10 are attached via a cylindrical rubber support
member 15 between the bimorph vibrator 1m and the bottom surface. Also, even if the
composite m motor 10 is attached to the rubber support member 15 with an elastic adhesive, the
vibration of the bimorph oscillator ll is relatively free. Also, these rubber support members 15 or
elastic adhesive may be located on the two-drum of the bimorph vibrator 11. An external lead
16.17 is inserted and fixed to the substrate 16. Each lead 16 and 17 is connected to the counter
electrode of the bimorph oscillator +1. (4) 18 is a ground plate which is in contact with the back
surface of the substrate ISO. One of the resistors 16 is isolated and the other resistor 17 is
connected by soldering. A case 19 is press-fitted and fixed to the outer periphery of the substrate
13 to cover the members. In the case 19, a hole 20 is provided at a position facing the ultrasonic
wave transmission / reception of the composite vibrator 10, and a rope-like member 21 is
attached to the hole 20. Reference numeral 22 denotes a hole provided in the ultrasonic wave
transmitting / receiving surface of the additional resonator 12, which can reduce the Jf4 wave
number position of the Il & degree generated on the high frequency side. The person 22 may be
appropriately provided according to the desired characteristics. Next, specific examples will be
described. If the dimensions of the main members are set as follows by heating 1 in FIG. 4, the
wave receiving sensitivity characteristic shown in FIG. 6 is obtained. L=tO,2aawT! =
Q, 6 stores D = 11, ah = 1.2, u6 =! 7 '塾 ゝ d = 15. 1 處 111 t, = 2.04 m Distance between the
bottom of the concave portion and the bimorph 20, 7 · 1 菖 6 As is apparent from Fig. 1,
according to (5) of the specific embodiment, the conventional one (Fig. 5) The sensitivity of the
intermediate frequency region is more pronounced compared to. This can be guessed as follows.
That is, the vibration seen from the ultrasonic wave transmission / reception wavefront is in the
mode (upper and lower vibration) near 20 KHz at which the sensitivity on the low band side is
generated, and in the near proximity to 25 KH2 at which the MW in the high band is generated.
Since it is a bending mode, it is presumed that a vibration combining both 7-do will occur in the
intermediate frequency region, and the vibration of this combining mode will cause a lateral-fl
motion, and this bond direction taking al I component The ultrasonic wave μs is also reflected
on the side wall of the recess 14 and it is considered that the predetermined ultrasonic wave
traveling direction ( ′ ′ ′ ′ ′ ′ ′ ′ ′ ′ ′ ′ f ′ ′ 1 · ** osf # il [tr + or 6 ′ ′ 18 ′
′ acoustic wave is necessary to Be
Furthermore, if the shape of the recess 14 is changed while the first-party vibrator 10 has the
same shape, the sensitivity characteristic changes as shown in FIGS. That is, FIG. 7 shows the
depth t, t = In the case of changing j, a (m), FIG. 8 shows the case of changing the
diameter d to d = (fl), and FIG. In the figure, as shown in FIG. 4 (d), the
ridge 1 of the recess 14 is inclined. (6) A case where the angle a is changed to% tx =
As apparent from FIGS. 7-9, the shape of the recess 14 changes the lI & MlllP property, so the
optimum shape of the recess 14 for the composite vibrator used needs to be determined
experimentally. In fact, as a result of conducting experiments on various plating transducers, it is
possible to find the optimum shape of the concave portion for obtaining sensitivity that can be
practically used in response to KI. E In the embodiment described above, the bimorph oscillator ll
may have a disk shape, the cross section of the additional resonator 12 may have a polygonal
shape, and the recess 14 may have a circular shape. It is As described above, according to the
present invention, since the composite vibrator provided with the resin additional resonator at
the center of the bimorph vibrator is attached to the recess of the substrate, the effect of
obtaining high sensitivity over a wide frequency band is obtained. It is useful and practical.