Sensing the multifeeding of paper sheets requires a precision of approximately 1 mm and narrow directivity. At frequencies above 70 kHz, conventional bending oscillators cannot deliver practical characteristics. This is where the thickness longitudinal oscillation of piezoelectric ceramics comes in.
Here, there is a challenge of matching the acoustic impedance of the piezoelectric ceramics with that of the air.
A large gap between the acoustic impedances of the ceramics and the air would cause a great loss in the oscillating radiation from the former.
To prevent this, a special material, called an acoustic matching layer, is attached to the piezoelectric ceramics for impedance matching with the air. This design allows for the production of ultrasonic sensors for up to a few 100 kHz.
※This item is specialized product for double feed detection of scanner, printer and ATM.
Do not use in other application.
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