FINGERPRINT SENSOR

Japanese Patent JP2943437

B2

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.

SUMIHARA MASANORI
TAKEDA KATSU
NISHIKURA TAKAHIRO
KAWASAKI OSAMU

JP21954091A

August 30, 1999

August 30, 1991

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MATSUSHITA DENKI SANGYO KK

G01B7/28; G06F3/041; G06F3/047; G06T1/00; G06V40/13; (IPC1-7): G06T1/00

JP5827277A
JP1253624A

Fumio Iwahashi (2 others)

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