Measuring and testing – Vibration – By mechanical waves
Patent
1994-12-29
1996-10-08
Williams, Hezron E.
Measuring and testing
Vibration
By mechanical waves
73606, 73628, 382124, G01N 2900
Patent
active
055633455
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention is directed to a device for identifying fingerprints by use of ultrasound having an electronic evaluating circuit, a body which is filled with liquid and has a supporting surface with a plane outer side for the fingerprint to be analyzed, an ultrasonic transmitter and ultrasonic receiver, and is used for identifying fingerprints as means for authorizing access for persons to technical systems, rooms, vehicles, etc.
The invention serves in particular to replace PIN numbers used in connection with banking cards or other authorization identification. Accordingly, the invention can be applied in such areas as
2. Description of the Related Art
There are a number of known commercially available technical solutions which are based on graphical comparison of the skin surface of the finger with reference patterns stored in computer memory. For this purpose, the fingerprint to be analyzed is photographed by a pixel-oriented optoelectronic camera (e.g., a CCD matrix camera), the measured values are convened in an analog-to-digital converter or ADC and entered in an electronic computer in which they are compared with reference images, e.g., based on the patterns of the fingerprint, which are stored in the computer memory.
A process and an arrangement using ultrasonic waves for analyzing fingerprints instead of photo-optical (imaging) elements is known from DE-OS 36 10 397, wherein the following possibilities were considered: ultrasonic radiation in its entirety or in part, depending upon the concrete arrangement, is directed onto the hologram. be used for identification, for example, by way of correlation analysis.
The application of ultrasonic waves as described above has the following advantages: environmental influences (e.g., small surface-area disfigurement or soiling of the examined skin region) due to the holistic character of feature detection; so that it is relatively forgery-proof; amplitude as well as its phase can be utilized for feature detection so as to increase reliability of identification.
Further, it is obviously possible to realize devices on the basis of ultrasound which are smaller, more robust and less expensive than devices based on optical, graphical comparisons.
An arrangement in which a quantity of individual elements arranged in matrix form is provided as ultrasonic transmitter and/or ultrasonic receiver is described in DE-OS 40 16 105 "Process and Arrangement for Determining Surface Structures". The individual transmitter elements are preferably actuated successively in time in a pulsed manner. In this type of operation, the transmitter matrix and the receiver matrix can be identical and the individual elements are operated optionally as transmitters or receivers via a measuring point change-over switch. Further, it is obvious that the matrix form can be substituted by arranging pairs of transmitters and receivers on a scanner.
Based on the laws of Fourier transforms, it is obvious that the individual receiver signals in such an arrangement are not invariant with respect to rotation of the fingerprint on the supporting surface.
Moreover, since the received signals are (complex) sound amplitudes in analogous Fourier transforms with the use of ultrasound, the receiver signals also depend on the positioning of the fingerprint (multiplicative linear phase function corresponding to the displacement rule of Fourier transforms).
OBJECT AND SUMMARY OF THE INVENTION
The primary object of the present invention is to provide a device for identifying fingerprints by means of ultrasound according to the of the general nature described above so as to obtain receiver signals which are invariant with respect to rotation and translation relative to changes in position of the fingerprint on the supporting surface.
In accordance with the invention, in a device for identifying fingerprints by use of ultrasound having an electronic evaluating circuit, a body which is filled with liquid and has a supporting surface with a plane outer side f
REFERENCES:
patent: 4086818 (1978-05-01), Reynolds
patent: 4977601 (1990-12-01), Bicz
patent: 5211059 (1993-05-01), Hayakawa et al.
patent: 5218644 (1993-06-01), Bauer
patent: 5224174 (1993-06-01), Schneider et al.
patent: 5258922 (1993-11-01), Grill
Sound and Ultrasound Waves in Air, Water and Solid Bodies, (V. A. Krasil'nikov) 1963, National Science Foundation, Jersualem, IL, Third Edition, Translated from Russian (pp. 194-196).
Fundamentals of Ultrasonics, ( J. Blitz, et al) 1967, Butterworths, London, GB Second Edition (pp. 37-38).
Kersten Ralf T.
Oehmke Volker
Thorwirth Guenter
Ashraf Nashmiya
Jenoptik GmbH
Williams Hezron E.
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