The working characteristics of a typical piezoelectric film element

The DTI element is a standard MSI piezoelectric film structure that is die-cutting on the piezoelectric polymer matrix and on the effective area of 12x30mm with a silver ink electrode printed on two sides.

1, electric - machine transformation

(1 directions) 25x10-12 m/V, 700x10-6N/V

(3 directions) 33x10-12m/V

2, machine - electric transformation

(1 directions) 12x10-3V mu / epsilon, 400x10-3V/ m 14.4V/N

(3 directions) 13x10-3V/N

3, thermoelectric transformation

8V/ degree K (@25 C)

4. Capacitance

1.36x10-9F, dissipation coefficient 0.018@10kHz impedance @10kHz12K Omega

5. Maximum working voltage

DC:280V (in the 1 direction, the displacement of 7 mu m)

AC:840V (in the 1 direction, the displacement of 21 mu m)

6, maximum force (in the direction of d31, fracture)

6~9kgF (voltage output 830~1275V)

Electric one machine transformation

Piezoelectric film is generally impossible to achieve large displacement and force, for example, when designing loudspeaker, this is obvious, because its low frequency performance (below 500Hz) is very limited. Even a large area of piezoelectric film can not produce high amplitude pressure pulse at low frequency. As we learned from the current design of ultrasonic space distance sensor (40~50KHz) and medical ultrasound imaging applications, it can not be applied to ultrasonic frequencies at too low frequencies and too high.

On the ultrasonic ranging, vertical beam height control of piezoelectric film element, and sensor curvature and controls the horizontal beam width, piezoelectric film transducer can achieve 360 degree vision, ranging from a few centimeters to several meters and has a very high resolution.

The structure of a double piezoelectric film (similar to a bimetallic piece) can make the small displacement of the two pieces of reverse connecting elements turn into an obvious perturbed motion. This principle can be made into small wind blades and optical reflectors. Such elements consume only very low energy (because it is capacitive). Because of its high capacitance, large components may be harder to drive, especially when a transformer is provided with a driving voltage. It is very important to design an excellent amplifier.

Although the force is very small, but the piezoelectric film but can be used to motivate other mechanical structure in very wide frequency range. If coupled with the vibration in piezoelectric film device to accept the whole system can have very high dynamic range, although the film on a structure generated by the resonant point the insertion loss is generally 66dB. If enough gain is added between the two components, the structure will generate self oscillation on its natural frequency, just like MSI's "ringing" technology created in the manufacture of pressure, load and liquid level sensors. This resonant mechanical system does not require a high voltage drive. The amplifier circuit operates on a double track operational amplifier or simply uses a single 9 volt battery. From the analysis point of view, when the piezoelectric membrane is applied to monitor the results, low voltage, such as the noise source of the spectrum analyzer of 70mVrms, is enough to introduce mechanical energy into the structure.
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