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BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
method of manufacturing an ultrasonic transducer utilizing the frequency of an ultrasonic band.
2. Description of the Related Art According to the characteristics of conventional ultrasonic
transducers, the axial direction z axis of a cylindrical ultrasonic transducer is perpendicular to
that and has an angle of When the two axes are the x-axis and the y-axis respectively,
they are completely different from those having approximately the same level of reception or
transmission sensitivity with respect to the x-axis and the z-axis. For the former, it was
manufactured by a relatively simple process as shown in the flowcharts of FIG. 4 and FIG. 5, but
when making a bottomed weir (outer case), the thickness of the bottom portion is made high in
dimensional accuracy It had the defect that things were very difficult and the yield was low. In
the latter case, in which there is a difference between the characteristic levels of the ultrasonic
transducers in the x-axis and z-axis directions and it is not possible to grind concentrically with
the central axis of the outer case. Since it is possible, the processing cost is very expensive, and it
is difficult to finish the thickness of the bottom with high accuracy, and it is also possible to make
the outer case etc. of constant elastic steel made of the same material as the diaphragm. It has a
fatal flaw of high industrial value and low value.
Problems to be Solved by the Invention The problems to be solved are the improvement of the
yield, the reduction of cost and the improvement of the performance which are generated in the
manufacture from the basic constitution of the ultrasonic transducer as described above.
[Means for Solving the Problems] First, as a means for solving when the sensitivity levels of
ultrasonic transducers in the x-axis and y-axis directions are equal, a portion corresponding to
the bottom of a conventional bottomed crucible (outer case) It was decided to use a flat plate
with high processing accuracy and separate from the cylindrical part, as a constant elastic steel
material with good temperature characteristics.
Further, as a solution when the sensitivity levels in the x-axis direction and the y-axis direction
are different, there are: By separately making the component and the outer case which give
causality to the directional characteristics separate, it is easy to procure each with the material
according to the purpose. 2. By making the component supporting the directivity
characteristics and the pipe supporting the inner terminal base separately, it is possible to create
a directivity characteristics control plate by punching a flat plate, and an ultrasonic transducer
with arbitrary directivity characteristics. Manufacture easily. 3. Separately from the member
constituting the vibration system and the member for controlling directivity, materials and
shapes suitable for the purpose are selected and combined. 4. In order to meet the demands
on performance of ultrasonic transducers, which are relatively strict, and to meet the strict
demands on cost, the directivity control body is separated even though the outer case and the
vibration system are integrated (control body and base support It is natural to divide the above
into the category of the present invention).
manufacturing an ultrasonic transducer, a new concept is to select each component which
satisfies the conditions for sufficiently exhibiting many different functions respectively. Do. That
is, according to the embodiment of the present invention, optimum conditions for each single
member can be obtained by separately and individually achieving the desired functions for each
component of the ultrasonic transducer easily and accurately. It is an embodiment of the present
invention to select and combine irrespective of other related members.
[Example 1] Conventionally, since the bottomed crucible is used as the outer case, it is very
difficult to precisely process the thickness of the bottom portion which needs a function as a
resonance plate of a vibration system. At the same time, metal aluminum used in the case as a
material which is easy to squeeze and crimp is not suitable as a material constituting the
vibration system because it thermally expands with temperature. In the present invention, as
shown in FIGS. 1, 2 and the flowcharts (1-1) and (1-2), the end of the outer pipe shown in a
perspective view in F11 is drawn and processed so as to show a cross section in F12. In this case,
it is also within the scope of the object of the present invention to punch out and create only the
central portion leaving the outer periphery of the bottom of the bottomed crucible with a
finished outer case similar to drawing and caulking from a pipe. I omitted it. The drive source of
the ultrasonic transducer or the ceramic diaphragm F13 that has been polarized to convert it into
an electrical signal in response to a mechanical signal, and the outer diameter is smaller than the
inner diameter of the outer pipe and larger than the opening diameter of the bottom Constant
elastic steel with a thickness that resonates after bonding to a ceramic plate at the target
resonant frequency, eg, from Sumitomo Special Metals Ltd. Smith Pan C with a temperature
coefficient equivalent to that used as a wristwatch strip The flat plate with high mechanical
dimension accuracy is punched out with a punching press, and the resonance disk F14 is bonded
and bonded so as not to cause eccentricity, the adhesive is sufficiently cured and dried, and then
the characteristic inspection as a vibration system member is performed. Conventionally, when
heat treatment for disassembling the adhesive is applied to the outer pipe (case) integrated in the
case where a defect occurs in this inspection step, the aluminum is softened and deformed by
heat, so it must be discarded at the same time It was not. Since the constant elasticity steel of the
present invention is nickel or an iron-based alloy, it may be subjected to heat treatment to
separate the ceramic plate F13 and the resonant plate F14 at a temperature at which the
adhesive is decomposed in a nonoxidizing atmosphere. It is possible. This greatly contributes to
cost reduction. In particular, what must be regarded as important in this inspection process is
that the bottom thickness of the conventional bottomed bowl is not only low in working
efficiency but also the processing accuracy and the roughness of the processing surface as well.
Or, it is significantly inferior to the surface roughness. As a result, the distribution width of the
resonance frequency of the vibration system of the present invention, in other words, the ratio of
the standard deviation σ is 0.47, and the ratio of the resonance frequency falling within a
predetermined range is twice or more the conventional ratio. Next, an adhesive is applied to the
outer peripheral surface of the non-defective vibration system member and the outer peripheral
surface of the surface to which the ceramic vibrator is not bonded, and the outer case F12 is
inserted into the outer case F12.
[Following from the flowchart (1-1) to the same (1-2)] Next, the inner pipe F15 is inserted into
the outer pipe. On the other hand, the back plate F16 is placed on the back of the terminal base
F17, and the terminal 31 on the ground side and the back plate are joined with a conductive
material such as solder if necessary. On the other hand, the hot side terminal 32 and a ceramic
electrode are connected, and then the outer case is crimped temporarily (an illustration is
omitted) to check the performance, and the upper end of the outer case is crimped. In the present
embodiment, a terminal base on which terminals are planted is used, but the case of using an
electrode wire which can substitute for the terminal as this member is also included in the scope
of the present invention. A longitudinal sectional view of a plane passing through the central axis
of the ultrasonic transducer created by the flowcharts (1-1) and (1-2) is shown in FIG. According
to the present invention, by separating the resonance plate that constitutes the outer case and
the vibration system, the mechanical dimensions of the thickness that causes the resonance
frequency can be accurately made with high accuracy by creating a flat plate of constant elastic
steel by pressing At the same time as the variation width of 0.47 is reduced to 0.47 times the
conventional one and the yield is improved, it is possible to manufacture an ultrasonic transducer
with stable temperature characteristics. Embodiment 2 This embodiment of the present invention
is also effective for the ones having equal sensitivity levels of the ultrasonic transducers in the xaxis and y-axis directions, as well as the ones having special directional characteristics which are
not equal. In the drawings, in particular, those having special directivity characteristics in which
sensitivity differences in the x-axis and y-axis directions are provided will be described. As a
material of the outer case, one end of an aluminum pipe F21 is drawn and crimped, and drawn
and crimped as shown in the cross-sectional view F22. 猶 In this outer case, it is also free to
punch out the bottom of the bottomed bowl with an accurate diameter punch. Next, as a
piezoelectric material, a disk F23 with electrodes on both sides of PZT-based ceramic and
subjected to polarization treatment (in particular, it is not limited to a disk shape, and polygonal,
oval or elliptical ones are also aimed freely As a drive element or passive element that constitutes
a vibration system, having a conversion function of mechanical energy and electrical energy and
having a function of stably acting in a specific frequency band), and directivity characteristics of
the ultrasonic transducer required A directional control body F24 which causes the directivity
designed to satisfy the shape to cause and cause it is bonded and joined to a plate made of a
constant elastic material which is a main component of a vibration system on a pressed resonant
plate F25 and dried, and then primary If a performance inspection is conducted and a defective
product occurs, heat treatment in a non-oxidizing atmosphere is performed in this step to
thermally decompose and recover the adhesive of the ceramic plate F23, the directivity control
body F24, and the resonant plate F25. Things are possible.
In the method of the conventional ultrasonic transducer, the outer case and the resonance plate
etc. are integrally made of aluminum, and when the adhesive is subjected to thermal
decomposition, an aluminum material whose hardness reacts to heat regardless of the
environment atmosphere. Due to the basic nature of the above, there was a defect that the cost
was high because many losses including material costs occurred because the recovery was not
possible. The good product applies an adhesive to the periphery of the resonance plate and the
outer contour surface in contact with the squeezed portion of the outer case, or alternatively, the
adhesive is filled in the squeezed inside of the outer case in advance. The resonator and its joint
member are inserted into F22, and pressure insertion is performed and fixed to a predetermined
position by the inner pipe F26. On the other hand, the back plate F27 is attached to the terminal
base F28, and if necessary, the ground terminal 61 and the back plate are soldered for electrical
conduction and mechanical bonding. On the other hand, the hot terminal 62 connects the
electrodes of the vibrator using lead wires. A cross-sectional view of an ultrasonic transducer
longitudinally cut along a plane passing through the central axis of the outer case completed
through the steps as shown in flowchart 2-2 below is as shown in FIG. As apparent from this
embodiment, in the conventional method, sensitivity levels in the x-axis and y-axis directions are
very difficult, in other words, at a solid angle based on the central axis of the outer case of the
ultrasonic transducer. Can be made at very low cost by simply creating a directional control body
that can be designed at any level in the press work separately from other members, and at the
same time, the main body of the vibration system is In order to separate the constant elastic steel
material of the shape with high accuracy in the mechanical form of the resonance plate
separately from the outer case and the directivity control body that causes the directivity
characteristics, the shape material that exhibits the desired performance for each member By
adopting selectively, it was possible to obtain an ultrasonic transducer with excellent
temperature characteristics and special directional characteristics. Third Embodiment In the
present embodiment, the ultrasonic transducer having special directivity characteristics having
different sensitivity levels in the x-axis direction and y-axis direction will be described in detail in
comparison with the conventional manufacturing method. Write down. First, conventionally, Qm
(in the case where vibration driving body is stuck to material and excitation is made in material
ultrasonic wave band with machinability of material and resonance frequency fR and
antiresonance frequency far are Qm f fR / (far-fR It is well known that an aluminum material is
used because it is relatively suitable as a material of an ultrasonic transducer) and is a standard
of hardness against vibration. Conventionally, as shown in FIG. 7, the aluminum rod is adopted as
the raw material and processed to show the manufacturing process of the outer case 74, the
aluminum rod 71 is cut to adjust the volume to which the cutting allowance is added as the
material of the outer case. First, the final shape is designed based on the cold forging method,
and after the general shape is formed into a wedge-shaped formed body 72 as shown in a
perspective view in FIG. The mold of the cutting hole 73 was processed into an oval shape as
shown in a plan view in FIG.
In this processing, the shape of the hole causes the directivity characteristics of the ultrasonic
transducer to be causal, and the thickness of the bottom is both important factors to affect the
resonance frequency, and in particular, the thickness of the bottom is primarily the ultrasonic
transducer Assuming that the given thickness was 0.3 mm, because it was inversely related to
the resonance frequency of the other resonance frequency, another dispersion element was
placed within the resonance frequency tolerance within 0.5% required of the ultrasonic
transducer. In order to control it, it must be further suppressed to 70% or less of that. In absolute
numerical terms, a very high accuracy of 0.3 mm × 0.005 × 0.7 = 0.00105 mm is an ideal
value. In the flowchart 3 for the implementation shown in FIG. 8, the cause of the occurrence of a
certain degree of defect in the inspection step is mainly because the accuracy of the thickness of
the bottom 75 has not reached the target level. The machined outer case 74 is shown by e in the
x-axis direction and by f in the y-axis direction. The stage 76 is provided in the opening of the
outer case 74 for the purpose of mounting the terminal base 92 on which the ground terminal
91 and the hot terminal 96 are erected as shown in the flow chart 3 The longitudinal crosssectional view of is as shown in FIG. Conventional ultrasonic transducers that require this type of
directivity have a relatively easy operation when cutting for the purpose of providing a hole
concentrically with a general outer case, and finish the bottom thickness with considerable
accuracy Although it is possible, as in the present embodiment, to make an outer case suitable for
an ultrasonic transducer that requires a difference in sensitivity level in the x-axis direction and
y-axis direction is extremely poor in workability, and Since it is difficult to increase the finishing
accuracy, there are defects that result in poor yield and high price. In the present invention, as
shown in a perspective view and a sectional view of the member in FIG. 10, first, the outer case
101 is completely separated from the outer case 101 by making it completely separate from the
member 102 for causing the directivity characteristic. The concentric inner holes were easily
machined with high accuracy. Next, a plan view d, a perspective view e, a longitudinal crosssectional view in the x-axis direction of a directional characteristic control rod 102 made by
cutting a rod made by extrusion molding having an opening 102-1 satisfying directivity. Insert as
shown in the cross-sectional view g in the f, y axis directions, and unite the outer case with the
directional control body. By constructing the outer case according to the present invention and
the control body 102 that causes the directivity to be separate from each other as compared with
the conventional integral type, the operation is simple and the mechanical accuracy is high. The
ultrasonic transducer using the member is characterized by low cost because of its good
workability, and high dimensional accuracy, so that it is possible to manufacture a product with
less variation in resonance characteristics.
In order to make the outer case according to the present invention a finished product of an
ultrasonic transducer, a ceramic vibrator 111 is disposed at a predetermined position, a metal
back plate 112 is mounted on the back surface, and two lead terminals are erected. Figure 11
prepare the electrical connection between the hot terminal and the electrode of the ceramic
vibrator, insert it, temporarily crimp the outer case, inspect the characteristics of the ultrasonic
transducer, and check the non-defective product. The lead wires 113-1 and 113-2 are soldered to
the terminal 114 according to the purpose as shown in the cross-sectional view of FIG.
[Embodiment 4] The inner diameter 122 of the aluminum pipe 71 has an outer diameter 16.0
mm, an inner diameter 15.4 mm, a length 13.0 mm, and a directivity at the center based on the
size of the objective ultrasonic transducer. The directivity obtained by oblong extrusion that
connects maximum and minimum points in parallel with the line connecting the center points of
two arcs with a radius of 4.5 mm and a gap between the center points of 3.5 mm. The control
body 122 is shown in plan view in FIG. 12c. The outer diameter of the control body 122 is 15.2
mm to be fitted to the inner diameter of the pipe 121, and the length is 8.0 mm. Next, as shown
in FIG. D, one piece of a round polygon or rectangular piezoelectric ceramic 124 is selected and
bonded to a resonator 123 fixed at a distance of 1.3 mm from the end of the pipe to cause a
resonance frequency. An adhesive is applied to the surface in contact with the directivity
characteristic control body 122 and inserted as shown in the cross section j in FIG. J, and the end
of the pipe 121 is in a state where the bonding surface of the resonator 123 sufficiently adheres
to the control body. After drawing and crimping 121-11 as shown in FIG. 14k, as shown in a
longitudinal sectional view of one example of the finished product in FIG. 14a, the lead wire 143
on the hot side is joined to the electrode surface of the piezoelectric body. At this time,
particularly when a sufficient tensile strength is required for the lead wire, it is free to provide a
stopper 144 which does not penetrate the opening of the ground terminal as shown in a
schematic view in FIG. 14b. Next, as shown in FIG. 13, a hole 132 is provided at the central
portion, and a hole 132 or a terminal 133-1, 133-2 for the ground terminal plate 131 having a
terminal 133-1 of a type having claws raised around it. Inserted from the head of the pipe while
pulling out from the gaps 134-1, 2, 3 and 4 made by raising 133-3 and 133-4, the lower surface
thereof is joined to the upper end surface of the directivity control body 122 to be piezoelectric
With the pressure applied to electrically connect the ground electrode surface of the insulating
ceramic 124, the head 121-2 of the pipe (outer case) 121 is squeezed and crimped as shown in
FIG. 142 is soldered to one of the terminals of the ground terminal plate 131, and it is made of
foamable silicone resin, which has a low vibration attenuation rate such as silicone rubber, and
has the effect of improving the transient phenomenon of the ultrasonic transducer This figure an
insulating resin which is indicated by a single layer, to complete the multi-type are implanted into
a layer.
In the present embodiment, although the control body of the directional characteristic is
described as being integral with the inner support pipe F26, it is naturally within the scope of the
present invention if it is separate as already described in the second embodiment. Also, with
regard to the order of assembly work, this embodiment shows one example of many assembly
means, and it is free to change the means, but the feature of the present invention is that for each
part, the intended function In another method, the ultrasonic transducer with high accuracy and
temperature characteristics can be produced inexpensively by increasing yield.
According to the present invention, in order to minimize the temperature dependence of
frequency, which is an important characteristic of the ultrasonic transducer, by making the outer
case and the resonator separate, an effect that can not be achieved by the conventional one is
realized. It is possible to obtain an arbitrary directivity characteristic with high accuracy by
separately obtaining a control body that can be obtained and cause the directivity characteristic
of an industrially valuable ultrasonic transducer to be causally separated, and the application
range of the ultrasonic transducer Significantly expanded and industrially valuable. It is possible
to make a flat plate by press processing etc. by using a control body that causes the direction of
the ultrasonic transducer to cause and cause the direction of the ultrasonic transducer as a
separate body from the terminal base support pipe, and the control body is easily obtained with
high accuracy It is possible to easily mass-produce the transducers with high accuracy and has
industrial value. A stable vibration system can be configured by using a resonator that causes the
vibration system of the ultrasonic transducer as a cause and a control body that causes the
directivity as a separate body, and the accuracy of the frequency characteristic is improved and
the temperature characteristic is improved. At the same time, inexpensive ultrasonic transducers
having special directional characteristics can be produced and are industrially valuable. If special
directivity is required even though the cost of the ultrasonic transducer is particularly low,
although the members constituting the vibration system and the outer case should be the same
body, the directivity and causality control body should be separate By doing this, it is possible to
produce at a cost that has never been considered before, and it has industrial value.
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jp2001128292, description
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