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CN-122003703-A - Biometric device with ultrasound transducer for fingerprint and microvasculature detection

CN122003703ACN 122003703 ACN122003703 ACN 122003703ACN-122003703-A

Abstract

The invention relates to a biometric device comprising an ultrasound transducer circuit, a control circuit and a data processing circuit configured to perform-acquisition of a surface image of an element arranged against a capture surface and a series of volume images of the element determined from a global volume image (114) of a microvasculature of the element thereof, -determination of features of a fingerprint of the element from the surface image and features of microvasculature of the element from the global volume image (114), -comparison of previously determined features with expected theoretical features to identify or not identify the element.

Inventors

  • CHRISTOPHER BERNARD
  • Florian Ayer
  • Saban Tiberius Stella

Assignees

  • 艾迪4优思公司

Dates

Publication Date
20260508
Application Date
20240918
Priority Date
20230922

Claims (14)

  1. 1. A biometric device (100) comprising at least one ultrasound transducer circuit (104), a control circuit (106) and a data processing circuit (108) configured to implement at least the following steps: -acquiring (206, 210) at least one surface image (110) of at least one element (101) of a user's body of the device (100), the at least one element (101) being intended to be arranged against a capturing surface (102) of the device (100), and at least a series of volume images of the element (101), from which a global volume image (114) of the microvasculature of the element (101) is determined; -determining (214, 216, 218, 220) features of a fingerprint of the element (101) from the surface image (110), and determining features of the microvasculature of the element (101) from the global volume image (114); -comparing (222, 224, 226) the features determined in the previous step (214, 216, 218, 220) with features calculated during the user registration preliminary step to identify or not identify the element (101); Wherein the data processing circuit (108) is configured to implement the step (212) of aligning the surface image (110) and the global volume image (114) with each other between the step (206, 210) of acquiring the surface image (110) and the series of volume images and the step (214, 216, 218, 220) of determining the fingerprint of the element (101) and the characteristics of the microvasculature.
  2. 2. The biometric device (100) according to claim 1, wherein the data processing circuit (108) is configured to determine the global volumetric image (114) by implementing a method for spatiotemporal filtering of a series of volumetric images of the element (101).
  3. 3. The biometric device (100) according to any one of the preceding claims, wherein the ultrasound transducer circuit (104) is configured to perform acquisition of a series of volumetric images of the element (101) by pulsed wave doppler type imaging.
  4. 4. The biometric device (100) according to any one of the preceding claims, wherein the data processing circuit (108) is configured such that the step (214, 216, 218, 220) of determining the fingerprint of the element (101) and the characteristic of the microvasculature comprises at least: -determining (214, 216) minutiae (112, 113) of the fingerprint of the element (101) from the surface image (110), and determining points of interest (116) of the microvasculature of the element (101) from the global volume image (114); -calculating (220) a position of at least one detail (113) in the surface image (110) and/or at least one point of interest (116) in the global volume image (114), and calculating a geometrical relationship between the at least one detail (113) and/or the at least one point of interest (116) and at least a portion of the other details (112) and points of interest (116) for the point of interest (116) taking into account a depth of the point of interest (116) in the global volume image (114); And such that the comparing step (222, 224, 226) comprises comparing the previously calculated position and geometry with expected theoretical positions and geometry to identify or not identify the element (101).
  5. 5. The biometric device (100) according to claim 4, wherein the point of interest (116) corresponds to a bifurcation of a microvascular and/or a strong bending point of a microvascular.
  6. 6. The biometric device (100) according to any one of claims 4 or 5, wherein the data processing circuit (108) is configured to implement the step (218) of combining the determined details (112, 113) and points of interest (116) in the form of a point cloud between the step (214, 216) of determining the details (112, 113) and the points of interest (116) and the step (220) of calculating.
  7. 7. The biometric device (100) as claimed in any one of claims 4 to 6, wherein the data processing circuit (108) is configured such that during the calculating step (220) the further details (112) and points of interest (116) for calculating the geometrical relationship correspond to details (112) comprised in a region of the surface image (110) delimited by a planar geometry extending in a dimension perpendicular to the global volume image (114) of the surface image (110) and to points of interest (116) comprised in a region of the global volume image (114) comprised in a volume (120) formed by the planar geometry.
  8. 8. The biometric device (100) recited in claim 7, wherein the planar geometry (118) corresponds to a polygon, a circle, or an ellipse.
  9. 9. The biometric device (100) according to any one of claims 7 or 8, the data processing circuit (108) being configured such that the calculating step (220) is repeated for each determined detail (112, 113) and each determined point of interest (116), and the comparing step (222, 224, 226) is performed for each calculated position and the geometrical relationship of each detail (112, 113) and each point of interest (116).
  10. 10. The biometric device (100) according to any one of claims 4 to 9, wherein the data processing circuit (108) is configured such that the geometrical relationship calculated between a first detail (113) or point of interest (116) and a second detail (112) or point of interest (116) comprises a distance between the first detail (113) or point of interest (116) and the second detail (112) or point of interest (116), an orientation of the first detail (113) or point of interest (116) relative to the second detail (112) or point of interest (116), and an orientation of the second detail (112) or point of interest (116) relative to the first detail (113) or point of interest (116).
  11. 11. The biometric device (100) according to any one of claims 4 to 10, wherein the data processing circuit (108) is configured such that for a point of interest (116) corresponding to a bifurcation or a strong bending point of a microvascular, the calculated geometrical relationship comprises an orientation of each of the microvascular with respect to the other details and the point of interest.
  12. 12. A biometric device (100) according to any one of claims 1 to 3, wherein the data processing circuit (108) is configured such that: -the determination (214, 216, 218, 220) of the fingerprint of the element (101) and the characteristic of the microvasculature comprises extracting at least one characteristic vector from the surface image (110) and the global volume image (114) by implementation of a depth learning algorithm; -comparing (222, 224, 226) the previously determined feature with expected theoretical features to identify or not identify the element (101) comprises comparing the previously determined feature vector with at least one expected theoretical feature vector by means of the deep learning algorithm.
  13. 13. The biometric device (100) according to any one of the preceding claims, wherein the data processing circuit (108) is configured such that the comparing step (222, 224, 226) comprises a calculation of a score (224), the value of which depends on a correlation between the determined characteristic for identifying or not identifying the element (101) and the theoretical characteristic expected.
  14. 14. The biometric device (100) according to any one of claims 4 to 11 and claim 13, wherein the data processing circuit (108) is configured such that during the comparing step (222, 224, 226) a score is calculated for each determined detail (112, 113) and each determined point of interest (116).

Description

Biometric device with ultrasound transducer for fingerprint and microvasculature detection The present application claims priority from French patent application No. 23/10033, entitled "Biometric identification device with ultrasonic transducer for fingerprint and microvasculature detection", filed on month 22 of 2023, 9, which is incorporated herein by reference to the maximum extent allowed by law. Technical Field The present description relates to the field of biometric devices based on capture and detection by ultrasound conduction. Background The biometric device may verify or determine the identity of the device user based on measurements of one or more biometric features of the user, such as a fingerprint, facial shape, iris pattern, retinal pattern, etc. Various techniques by which one or more of these features may be measured according to different criteria include advantages and disadvantages including, inter alia, more or less significant error rates, ease of sealing the template compared to the measurement, ability or lack of ability to detect imitations, proof of activity, ease and comfort of use, required sensor size and required energy consumption. It is known to use fingerprint sensors for biometric, anti-spoof and liveness detection devices, which make optical or capacitive measurements to verify whether a captured fingerprint corresponds to an expected fingerprint (authentication phase), and then implement liveness detection and anti-spoof algorithms, for example, by using infrared systems or image processing performed from the captured fingerprint, it is possible to detect whether a finger provided on the device during fingerprint capture is a fake finger. Disclosure of Invention There is a need to propose a biometric device which does not have at least some of the drawbacks of the existing solutions. An embodiment overcomes all or part of the drawbacks of the known solutions and proposes a biometric device comprising at least one ultrasound transducer circuit, a control circuit and a data processing circuit, configured to perform at least the following steps: -acquiring at least one surface image of at least one element intended to be placed against a capturing surface of the device, and at least one series of volume images of the element, from which a global volume image of the microvasculature of the element is determined; -determining a fingerprint feature of the element from the surface image and a feature of the microvasculature of the element from the global volume image; Comparing the previously determined features, that is to say determined in said previous step, with expected theoretical features, such as features calculated during the preliminary step of user registration, to identify or not identify said element. According to a particular embodiment, the data processing circuit is configured to determine the global volume image by implementing a method for spatiotemporal filtering a series of volume images of the element. According to a particular embodiment, the ultrasound transducer circuit is configured to perform acquisition of a series of volumetric images of the element by pulsed wave doppler type imaging. According to a particular embodiment, the data processing circuit is configured to perform the step of aligning the surface image and the global volume image with each other between the step of acquiring the surface image and the series of volume images and the step of determining the fingerprint of the element and the features of the vasculature. According to a particular embodiment, the data processing circuit is configured such that the step of determining the fingerprint of the element and the characteristic of the microvasculature comprises at least: -determining minutiae of the fingerprint of the element from the surface image and determining points of interest of the microvasculature of the element from the global volume image; -calculating the position of at least one detail in the surface image and/or at least one point of interest in the global volume image, and calculating a geometrical relationship between the at least one detail and/or the at least one point of interest and at least some of the other details and points of interest for the point of interest taking into account the depth of the point of interest in the global volume image; And such that the comparing step comprises comparing the previously calculated position and geometry with expected theoretical positions and geometry to identify or not identify the element. According to particular embodiments, the point of interest corresponds to a bifurcation of a microvascular and/or a strong bending point of a microvascular. According to a particular embodiment, the data processing circuit is configured to implement, between the step of determining the details and the points of interest and the calculation phase, the step of combining the determined details and points of interest in the form of a point