BRAND : Nohken
VH10NH VH10FH
VH20NH VH20FH
VH10NH VH10FH
VH20NH VH20FH
The sensor has two piezoelectric crystals, one for oscillation and the other reception, placed on a plate supported at two places. Without material, the plate is set to vibrate at its natural frequency. The vibration decreases when the plate is covered by the material. The decrease in vibration is detected by the piezoelectric crystal, and the electric signal is given to indicate material presence.