Monolithic sensor of fingerprints
First Claim
1. A fingerprint sensor comprising a matrix of pressure microsensors sensitive to the pattern of a fingerprint, the matrix of pressure microsensors being implemented in an integrated circuit, each pressure microsensor of the matrix including a deformable diaphragm which closes off a cavity, the cavity being disposed between the diaphragm and a substrate of the integrated circuit, the diaphragm being formed of an insulator material, and the diaphragm having disposed thereon a conductive element of the microsensor which deforms under the effect of a pressure applied to the diaphragm.
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Accused Products
Abstract
An electronic fingerprint sensor works by the detection of pressure, the ridge lines of the finger exerting a greater pressure than the valleys. The sensor has a matrix of pressure microsensors and electronic control and signal-processing circuits. It is made in an entirely monolithic form, according to techniques for the making of electronic circuits (deposition of thin layers, photo-etching, doping and thermal processing), both for the pressure detection part and for the signal-processing and control part. The matrix-type pressure sensor uses either piezoelectric resistors lying on an insulator layer stretched above a cavity or a variable capacitor or a microcontactor.
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Citations
19 Claims
- 1. A fingerprint sensor comprising a matrix of pressure microsensors sensitive to the pattern of a fingerprint, the matrix of pressure microsensors being implemented in an integrated circuit, each pressure microsensor of the matrix including a deformable diaphragm which closes off a cavity, the cavity being disposed between the diaphragm and a substrate of the integrated circuit, the diaphragm being formed of an insulator material, and the diaphragm having disposed thereon a conductive element of the microsensor which deforms under the effect of a pressure applied to the diaphragm.
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14. A fingerprint sensor comprising:
a matrix of pressure microsensors sensitive to the pattern of a fingerprint, the matrix of pressure microsensors being implemented entirely in an integrated circuit, each pressure microsensor of the matrix including a first electrode disposed on a substrate of the integrated circuit, a deformable diaphragm which closes off a cavity, the cavity being disposed between the diaphragm and the substrate of the integrated circuit, the diaphragm being formed of an insulator material, and a second electrode, the second electrode being disposed on the diaphragm between the diaphragm and the substrate, the second electrode being deformable under the effect of a pressure applied to the diaphragm so as to have an open position and a closed position, the second electrode being electrically connected with the first electrode in the closed position, the second electrode being electrically disconnected from the first electrode in the open position, and the open and closed positions of the second electrode providing an indication of the pressure applied to the diaphragm.
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15. A fingerprint sensor comprising:
a matrix of pressure microsensors sensitive to the pattern of a fingerprint, the matrix of pressure microsensors being implemented entirely in an integrated circuit, each pressure microsensor of the matrix including a deformable diaphragm which closes off a cavity, the cavity being disposed between the diaphragm and a substrate of the integrated circuit, the diaphragm being formed of an insulator material, and a piezoelectric resistor, the piezoelectric resistor being disposed on the diaphragm, the piezoelectric resistor being deformable under the effect of a pressure applied to the diaphragm so as to have a resistance which varies according to the pressure applied to the diaphragm, the resistance providing an indication of the pressure applied to the diaphragm. - View Dependent Claims (16, 17)
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18. A fingerprint sensor comprising:
a matrix of pressure microsensors sensitive to the pattern of a fingerprint, the matrix of pressure microsensors being implemented entirely in an integrated circuit, each pressure microsensor of the matrix including a deformable diaphragm which closes off a cavity, the cavity being disposed between the diaphragm and a substrate of the integrated circuit, the diaphragm being formed of an insulator material, and a variable capacitor, the variable capacitor having first and second electrodes which are disposed in the cavity, the first electrode being fixedly joined to the diaphragm, the second electrode being disposed on the substrate, a capacitance between the first and second electrodes providing an indication of the pressure applied to the diaphragm. - View Dependent Claims (19)
Specification