●All specifications in this catalog and production status of products are subject to change without notice. Prior to the purchase, please contact NEC TOKIN for updated product data.
●Please request for a specification sheet for detailed product data prior to the purchase.
●Before using the product in this catalog, please read "Precautions" and other safety precautions listed in the printed version catalog.
●All specifications in this catalog and production status of products are subject to change without notice. Prior to the purchase, please contact NEC TOKIN for updated product data.
●Please request for a specification sheet for detailed product data prior to the purchase.
●Before using the product in this catalog, please read "Precautions" and other safety precautions listed in the printed version catalog.
2010.03.19
9307PIEVOL04E
INTRODUCTION
Increasingly, we can see the unique properties of mechanical vibration and ultrasonic waves put to use in many ways. And the
single most important key to the effective monitoring or use of vibration is the transducer. Today's transducers are called on for
standards of performance that are higher than
ever before.
For best results in any application, the piezoelectric materials in the transducer should be selected with the specific use in
mind. This catalog contains a wealth
of information to help you evaluate transducer characteristics.
And when it comes to the materials themselves, look to NEC TOKIN's NEPEC
®
NPM piezoelectric ceramics. Using zicron
and lead titanate as the main components, NEPEC materials have a wealth of features:
1) A wide selection range, especially for mechanical
characteristics and degree of electromechanical coupling.
2) High stability against temperature and humidity variations
and aging.
3) Remarkably fine ceramics that can be machined into a
variety of sizes and shapes.
4) Excellent resistance to voltage, permitting transducers
with polarization in any direction.
5) A wide range of potential uses.
This catalog describes NEC TOKIN's standard piezoelectric ceramics, and it also describes NEC TOKIN's line of transducers.
If you cannot find the desired material characteristics or transducer for your application in these pages, please contact us
directly; our engineering staff can work with you to develop materials for your purpose.
References
Please refer to the following bibliography if you want more details of basic theory and applications of transducers:
●All specifications in this catalog and production status of products are subject to change without notice. Prior to the purchase, please contact NEC TOKIN for updated product data.
●Please request for a specification sheet for detailed product data prior to the purchase.
●Before using the product in this catalog, please read "Precautions" and other safety precautions listed in the printed version catalog.
2010.03.19
9307PIEVOL04E
Design Materials
Outline
A piezoelectric material responds mechanically when
voltage is applied, and conversely, generates a voltage in
response to a mechanical change.
To create piezoelectric ceramics, polycrystalline
ceramics are fired and baked at a high temperature. Then
electrodes are mounted and a DC field applied in order to
polarize the ceramic material; once polarized, the
material exhibits piezoelectric properties, allowing it to
be used as a piezoelectric ceramic transducer. These
transducers are also called electrostriction transducers,
since ceramic crystals are deformed by electricity.
Barium titanate and lead zircotitanate are the most
popular piezoelectric ceramics. In addition, NEC TOKIN
also uses a variety of other materials, including
conventional lead zircotitanate.
This results in piezoelectric materials that can be used
in a wide variety of applications: those that use the
piezoelectric effect (such as igniters and pickups), those
that utilize resonance (e.g., filters), and those that utilize
the electrostrictive effect (such as piezoelectric buzzers
and displacement elements).
In addition to barium titanate and lead zircotitanate,
popular as piezoelectric ceramics, NEC TOKIN offers multi-
component solid ceramics developed from conventional
lead zircotitanate ceramics. They meet a wide range of
specifications for a wide range of applications. The main
applications include: those that use the piezoelectric
effect (such as sensors and pickups), those that utilize
resonance (such as transducers for ultrasonic motors and
cleaning equipments), and those that utilize the
electrostrictive effect (such as piezoelectric sound
elements and displacement elements). In addition, they
can be used as ultrasonic vibrators and transducers.
4 Piezoelectric Ceramics Vol.04
●All specifications in this catalog and production status of products are subject to change without notice. Prior to the purchase, please contact NEC TOKIN for updated product data.
●Please request for a specification sheet for detailed product data prior to the purchase.
●Before using the product in this catalog, please read "Precautions" and other safety precautions listed in the printed version catalog.
2010.03.19
9307PIEVOL04E
Evaluation of Transducer Characteristics
NEC TOKIN evaluates the characteristics of
transducer materials based on a number of parameters.
1)
Practically, frequencies minimizing and maximizing
the impedance shown in Fig. 2 are generally treated as
fr and fa, respectively.
Resonant Frequency
When an AC voltage is applied to the transducer and
frequency f is varied to be in agreement with the
natural frequency of the transducer, it vibrates very
violently. This frequency is called resonance
frequency fr.
A constant voltage circuit or a low voltage circuit
was used for measurement of the resonance and anti-
resonance frequencies. Recently. these frequencies
can be measured easily with an impedance analyzer
such as the HP4194A of Hewlett-Packard.
Resonance frequency fr obtained from the
equivalent circuit near the resonance frequency and
anti-resonance frequency fa can be expressed by the
following equations:
L
1
C
1
R
1
Impedance (Ω)
fr
Frequency (Hz)
fa
Fig. 1-2 Impedance characteristic of piezoelectric transducer
Resonant frequency fr can be defined in a number
of different ways, depending on the mechanical
structure and oscillation of the transducer.
C
0
Fig. 1-1 Equivalent circuit of transducer
a)
Radial vibration
fr
=
fr
=
1/
{
2
π
L
1
C
1
}
fa
=
1 /
{
2
π
L
1
C
0
C
1
/
(
C
1
+
C
0
)
}
N
1
[
Hz
]
· · · · · · · · · · (1)
D
t
D
D>3t
Fig. 1-3
Radial vibration is in the direction of the arrows. The
coefficient of electromechanical coupling for this type
of vibration us called Kr.
Piezoelectric Ceramics Vol.04 5
●All specifications in this catalog and production status of products are subject to change without notice. Prior to the purchase, please contact NEC TOKIN for updated product data.
●Please request for a specification sheet for detailed product data prior to the purchase.
●Before using the product in this catalog, please read "Precautions" and other safety precautions listed in the printed version catalog.
