JPS5997300

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DESCRIPTION JPS5997300
[0001]
The present invention relates to a resonance type vibration sensor suitable for detecting elastic
vibration in a vibrating object, and more particularly to a manufacturing apparatus of a
resonance type vibration sensor excellent in detection sensitivity for a predetermined frequency.
Configuration of Conventional Example and Problems Thereof Conventionally, as a sensor for
detecting elastic vibration in a vibrating object, a cantilevered bending mode having a resonance
frequency matched to the natural frequency of the vibrating object is a rectangular bimorph
piezoelectric vibrator having a shear structure. well known. Since the rectangle is simple in
shape, it has the advantage that it can be manufactured with high accuracy and it is easy to
analyze and handle the vibration mode. However, in order to stabilize the resonance frequency,
the fixing conditions must be stabilized, but it is supported and fixed by one supporting member
such as multi metal by stress generated mechanically or by temperature change etc. It is difficult
to obtain a stable fixing condition because a shift occurs in the portion where the Further, also in
the manufacturing process, a predetermined resonance frequency is caused to vary due to
dimensional error or assembly error of parts, so it is necessary to make adjustment work to
match the predetermined resonance frequency. Therefore, since the resonance frequency Fr is
determined by the vibrating portion length t and the vibrating portion thickness T of the bimorph
piezoelectric vibrator by Froc'p / 12, the vibrating portion length is set so that the resonance
frequency is lower than a predetermined frequency in advance. An operation is performed to
appropriately adjust the tip of the vibrating portion to a predetermined frequency by cutting
after assembling. Therefore, the assembly process and the frequency adjustment process are
separated, and in the frequency adjustment process, resonance frequency detection and cutting
are alternately performed, which consumes considerable process time. In addition, when cutting
the tip of the vibrating portion, the mechanical contact is performed so that if an excessive force
is applied, the element may be damaged. The object of the present invention is to manufacture a
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resonance type vibration sensor. It is an object of the present invention to solve the abovementioned drawbacks of the prior art in the prior art and to provide a manufacturing apparatus
in which the predetermined frequency adjustment operation is easy, no breakage of the element
in cutting, the process is shortened and the time is reduced. . According to the present invention,
there is provided a vibration sensor having a structure in which a flexural vibration mode
vibrator is localized in a piezoelectric element in which two plate-like piezoelectric elements
having a polarization axis in the thickness direction are pasted and the peripheral is supported
and fixed. A manufacturing apparatus, comprising: a laser processing machine for processing the
flexural vibration mode vibrator; a resonant frequency detector for detecting a resonant
frequency of the flexural vibrator; and the flexural vibration by an error of the resonant
frequency with respect to a predetermined frequency And a laser processing machine controller
for controlling the amount of cutting of the element.
Description of the Embodiments An embodiment of the present invention will be described in
detail with reference to the drawings. FIG. 1 shows a structure in which a flexural vibration mode
vibrator is localized in a piezoelectric vibrator in which two disk-like piezoelectric elements
having a polarization axis in the thickness direction are pasted together. The (,) drawing is a top
view, (b) the drawing is a longitudinal sectional view, and (C) the drawing is a bottom view. The
disc-shaped piezoelectric elements 1 and 2 are sufficiently thin so that electrical conduction can
be achieved by the electrodes 1 a ′ and 2 a ′ of the disc-shaped piezoelectric elements 1 and 2
to form a bonded piezoelectric vibrator. In a state in which the periphery of the laminated
piezoelectric vibrator 1 is supported and fixed, the through portion cutting (hereinafter, the
partially cut portion 3 is referred to as a slit) is performed, and the top electrode is a portion 1as
a bottom electrode surrounded by the slit 3 with a slit It is a piezoelectric vibrator having a
structure in which a partial electrode is formed like the portion 2 a from the enclosed portion to
the peripheral edge. FIG. 2 shows a longitudinal sectional view of a vibration sensor which
supports and fixes the periphery of the pasted 9 mating piezoelectric vibrator. Reference numeral
5 denotes a conductive one-side support member of the bonded laminated piezoelectric vibrator
having a screw portion 5 'attached to a vibrating object, and the support member 5 so that the
piezoelectric vibrator can be supported and fixed using the other support member 6. The support
member 6 is held down. Therefore, in the portion surrounded by the slit 3, the so-called
cantilever of the flexural vibration mode functions as a shear oscillator. Since the bottom
electrode 2a of the bonded piezoelectric vibrator is electrically connected by the support member
5, the support member 5 is used as one terminal for taking out the output voltage of the bending
vibrator, and the other terminal is used as a lead from the top electrode 1a It is taken out
through the line 4 and the like. The resonance frequency Fr is the length of the portion of the
vibrating portion surrounded by the T1 slit 3 or the thickness of the vibrating portion. If t is
defined by Fr ′ ′ r / 12, it can be set to a predetermined number of frequencies. Therefore, the
feature of this structure is that the resonator of the bending vibration mode is localized in the
bonded piezoelectric vibrator, so that the change in the resonant frequency of the bending
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vibrator is small with respect to the change in position to support and fix, is there. Therefore,
assembly can be performed without regard to dimensional errors or assembly errors of the
support parts. Accordingly, an embodiment of a manufacturing apparatus according to the
present invention is shown in a block diagram in FIG. 3 for manufacturing a vibration sensor
having the above-described structure. The slit 3 is processed by the laser processing machine 11
in a state where the periphery of the bonded piezoelectric vibrator 10 is supported and fixed, and
a localized bending vibrator is formed. At this time, the resonance frequency of the bending
vibrator is set to be slightly lower than a predetermined frequency, and the resonance frequency
is measured by the resonance frequency detector 12, and the difference between the resonance
frequency and the predetermined frequency is measured by the laser processing controller 13.
Based on the calculated amount, the laser processing machine is controlled to perform laser
processing based on the calculated amount, thereby obtaining a resonant vibration sensor
coincident with a predetermined frequency.
As described above, there is no damage to the element in a short time and because of
noncontacting processing. By using a measuring instrument such as an impedance meter or a
loumeter or a network analyzer as the resonance frequency detector 12, it is possible to measure
the change in impedance due to the frequency of the bending vibrator and to easily know the
resonance frequency by the minimum value of the impedance. . In addition, in the case of laser
processing, since the high pressure auxiliary gas is supplied to the portion to be cut, the bending
vibrator performs natural vibration immediately after the slit 3 is processed, and the natural
frequency is used as a frequency counter or the like. The resonance frequency can also be known
easily and in a short time by measuring. As described above, according to the present invention,
in the manufacture of a vibration sensor that localizes a bending vibrator in a bonded and
bonded piezoelectric vibrator that is supported and fixed in the periphery, the supporting and
fixing of the bonded piezoelectric vibrator is performed. The resonance frequency is stable with
respect to changes in the part, so that assembly can be performed without concern for
dimensional errors or assembly errors of the support parts, and the manufacture of the bending
vibrator in the bonded piezoelectric vibrator is noncontacting, useless element There is an
advantage that the adjustment operation to set the frequency to a predetermined frequency can
be performed easily and in a short time without damage.
[0002]
Brief description of the drawings
[0003]
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1 (a), (b) and (e) are top views, longitudinal sectional views, and a bottom view showing a bonded
laminated piezoelectric vibrator in which a bending vibrator made by the vibration sensor
manufacturing apparatus of the present invention is localized. FIG. 2 is a longitudinal sectional
view of a vibration sensor, and FIG. 3 is a block diagram of a vibration sensor manufacturing
apparatus according to the present invention.
1, 2 · · · Disk-like piezoelectric element, 1a + 1a '+ 2a + 2 a' · · · Disk-like piezoelectric element
electrode, 3 ... Slit, 4 ... Support member, 10 ... Piezoelectric actuator, 11 ... Laser processing
machine, 12 ... Resonance frequency detector, 13 ... Laser processing machine controller.
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