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BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing an embodiment of
the present invention, and FIG. 2 is an explanatory view showing an example of a method of
controlling horizontal directivity of a transducer according to the present invention. 1 · · ·
Piezoelectric element, 2 · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · ·
· · · · · · · · · · · · · · · · · · · · · · · · · · · groove portion
DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the structure of a
high-yield cylindrical transducer having low input / output impedance, high transmission /
reception sensitivity, and easy control of horizontal directivity. The conventional cylindrical
transmitters are generally of the respiratory vibration mode in which the circumferential
resonance of the cylindrical piezoelectric ceramic is the basic resonance. However, since the
circumferential resonant frequency of the piezoelectric ceramic i′′lf2 is inversely proportional
to the diameter, the higher the resonant frequency, the smaller the diameter of the cylinder 1; the
smaller the processing becomes difficult and the acoustic emission q: tTa 槓 hand muscle Since
there is a disadvantage that the transmission and reception sensitivity is also extremely small (1)
i.theta. To. Unlike the case of using the respiratory vibration mode, in the case of using the
thickness vibration mode using the above, since the resonant frequency is established
irrespective of the diameter of the cylinder, the acoustic radiation surface can be dogged and the
transmission / reception sensitivity can be raised. However, this transducer has a drawback that
it is omnidirectional in the circumferential direction, that is, horizontal directivity, and it is
impossible to perform inter-finger control from a conventional point of view. In addition, there is
also one in which a large number of transducer elements are arranged on the outer peripheral
surface of the annular main body, but in this structure, there is a disadvantage that it takes a lot
of man-hours when arranging a large number of transducer elements. In many cases, the
electrical characteristics of the transducer elements become nonuniform, resulting in the
drawback that accurate transmission and reception can not be performed. The present invention
has been made in order to eliminate the above-mentioned drawbacks, and a groove portion
having an inner ridge portion in the thickness direction is formed on the outer surface of the
annular piezoelectric element to divide the outer peripheral surface and The present invention
will be described in detail below, which will provide a forgery of a transducer characterized in
that it is provided with electrodes on its face and on its part (2) of the peripheral face which has
been divided. FIG. 1 is a view showing one embodiment of the present invention, in which an
inner peripheral electrode 2 is formed on the inner peripheral surface of an annular piezoelectric
element 1 such as barium titanate, and an outer electrode is also provided on the outer side.
After forming into a series of three, the groove portion 4 is cut from the outer peripheral side so
as to leave the inner peripheral portion in the thickness D direction, and is divided into 12 parts.
It is desirable from the viewpoint of the electrical characteristics that the depth of cut should be
7 or more of the thickness D. The inner peripheral electrode 2 is common to each of the divided
outer peripheral electrodes #, 3 and a lead (not shown) is connected to the inner peripheral
electrode 2 and each outer peripheral electrode 3 to form a predetermined electric circuit
portion ( (Not shown) can be connected. In this embodiment, it is configured to be used in the
thickness normal mode in which the fundamental resonance is the thickness resonance, and
unlike the general cylindrical transducer using the respiratory vibration mode, the cylindrical
diameter is set large. Therefore, there is an advantage that the processing becomes easy, and the
transmission and reception sensitivity is large because the writing radiation surface is large, and
the entrance and exit cable 1 (3) lightness is also low.
Furthermore, since the groove 4 is formed, the piezoelectric e constant takes the form of 0e + e
□ 3331S, E, and is larger than the piezoelectric e constant e63 of the transducer using the
thickness vibration mode without forming the groove 4. Therefore, its transmission / reception
sensitivity is characterized in that it does not form the groove portion a. In addition, since the
plurality of outer peripheral electrodes 3 can be formed by forming the groove portion 4, there is
an advantage that horizontal directivity can be controlled by adjusting the amplitude or phase of
the voltage applied to those outer peripheral electrodes 3. It is explanatory drawing which shows
an example of the system which controls the horizontal directivity of the transducer which
concerns on invention, and the peripheral electrode 3 is divided into N (ld. Consider N as a
multiple of two. The phase gate (4) ψ1 q only corresponding to the distance from the first center
of the outer peripheral electrode 3 with respect to the line LL divided completely in 2 through
the center O of the piezoelectric element 1 (譬 (i −′−) ) When the same amplitude voltage is
applied to the 1st to 7th peripheral electrodes 3 by delaying N, the sound waves emitted from
each electrode are roughly phased to the line of LL, so this transmission and reception of
synthesized sound waves The directivity of the wave has a sharp beam in the direction X
immediately following LL. When used as a force receiver, the same sharp directivity can be
obtained by similarly delaying and adding the phase of the voltage output from each electrode.
Thus, the transducer according to the present invention is characterized in that horizontal
directivity can be arbitrarily controlled although it has an apparently cylindrical shape. Further,
since the transducer according to the present invention only covers the groove portions in the
same direction which do not cross each other, cutting at the time of groove cutting can be
facilitated and the manufacturing yield can be improved. As described above, since the present
invention divides the annular piezoelectric element into a large number, the radiation area is
large, the human output impedance is low, the transmission / reception sensitivity is high, and
(5) the horizontal directivity is easily made It is extremely useful because it can be controlled.
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jps53164172, description
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