| 摘要 |
<p>PURPOSE:To detect pressure distribution in accordance with a fingerprint pattern by a piezoelectric thin film sensor with high accuracy by arranging a sensor element to which polarization processing is applied in matrix shape via upper and lover plane electrodes. CONSTITUTION:A sensor element 1 is formed in such a manner that a piezoelectric thin film 5 with at least width size W of a lower plane electrode 4 is formed on the lower plane electrode 4. The element is comprised by forming an upper plane electrode 6 retracted by size W2 of 1/2 the piezoelectric thin film 5 from the boundary side of the lower plane electrode 4 on the piezoelectric thin film, and applying the polarization processing via the lower plane electrode 4 and the upper plane electrode 6. The piezoelectric sensor element 1 consisting of the piezoelectric thin film 5 is brought into contact with the chevron part (ridge) of a fingerprint, and the pressure of each piezoelectric element at a part coming in contact with the chevron part is converted to an electrical output signal by a piezoelectric effect. Only a piezoelectric element at a part to which the polarization processing is applied via the lower plane electrode 4 and the upper plane electrode 6 is provided with the piezoelectric effect, and no influence on a neighboring element is applied, thereby. the pressure distribution in accordance with the fingerprint pattern of a finger can be accurately detected.</p> |
