Assembly for detecting the superficial structures of fingers and/or palms

• US 6,407,804 B1
• Filed: 02/05/2001
• Issued: 06/18/2002
• Est. Priority Date: 06/04/1999
• Status: Expired due to Term

• Current Assignee: Cross Match Technologies GmbH (Assa Abloy AB)
• Original Assignee: Heimann Biometric Systems GmbH
• Inventors: Richter, Uwe, Hillmann, Juergen
• Primary Examiner(s): Font, Frank G.
• Assistant Examiner(s): STAFIRA, MICHAEL PATRICK
• Application Number:
  US09/762,351
• Time in Patent Office: 498 Days
• Field of Search: 356/71, 356/601, 382/4, 382/5
• US Class Current: 356/71
• CPC Class Codes: G06V 10/145 Illumination specially adapted for pattern recognition, e.g. using gratings
• CPC Class Codes: G06V 40/13 Sensors therefor

Abstract

An arrangement for detecting the surface structures of fingers, palms or other parts of the skin placed on an image scanning surface, wherein the image scanning surface is formed at a scanning prism, an illumination beam path is directed to the image scanning surface in the interior of the scanning prism, and the light reflected from the latter impinges on the reception surface of an optoelectronic detection device. In an arrangement of the type described above, a part of the illumination beam path or a separate illumination beam path is directed to reference structures which are fixed in place and, from the latter, to the reception surface, wherein separate partial areas of the reception surface are reserved for the detection of the surface structures and for the detection of reference structures.

Claims

1. An arrangement for detecting the surface structures of fingers, palms or other parts of the skin placed on an image scanning surface comprising:

said image scanning surface being formed at a scanning prism;

an illumination beam path being directed to the image scanning surface in the interior of the scanning prism, and the beam reflected from the latter impinging on the reception surface of an optoelectronic detection device;

a part of the illumination beam path or a separate illumination beam path being directed to reference structures and, from the latter, to the reception surface;

separate partial areas of the reception surface being reserved for the detection of the surface structures and for the detection of reference structures.

2. The arrangement according to claim 1, wherein the reference structures are arranged so as to be fixed in place on the scanning prism, wherein separate partial areas which do not intersect are reserved for the reference structures and for the surface structures to be detected, and a common illumination beam path is provided for these partial areas.

3. The arrangement according to claim 1, wherein the reference structures are arranged so as to be fixed in place on the entrance face of the scanning prism, wherein separate partial areas which do not intersect are reserved for the reference structures and for the surface structures to be detected, and a common illumination beam path is provided for these partial areas.

4. The arrangement according to claim 1, wherein the reference structures are arranged so as to be fixed in place on the exit face of the scanning prism, wherein separate partial areas which do not intersect are reserved for the reference structures and for the surface structures to be detected, and a common illumination beam path is provided for these partial areas.

5. The arrangement according to claim 1, wherein the reference structures are arranged so as to be fixed in place on the image scanning surface of the scanning prism, wherein separate partial areas which do not intersect are reserved for the reference structures and for the surface structures to be detected, and a common illumination beam path is provided for these partial areas.

6. The arrangement according to claim 1, wherein semi-transparent reference structures are introduced in the illumination beam path and/or in the beam reflected by the image scanning surface.

7. The arrangement according to claim 6, wherein the semi-transparent reference structures are arranged on the scanning prism so as to be fixed in place or are reflected into the beam path, wherein the cross-sectional areas of the beam path provided for the detection of the surface structures and the cross-sectional areas of the beam path provided for the detection of the references structures and the surface portions of the reception surface provided for the detection of the surface structures and the surface portions of the reception surface provided for the detection of the reference structures intersect.

8. The arrangement according to claim 1, wherein the optoelectronic detection device is combined with an evaluating circuit in which the images which are obtained from the reference structures are subjected to a comparison with stored data, and conclusions concerning whether or not the predetermined device parameters are adhered to can be drawn from the comparison.

9. The arrangement according to claim 6, wherein a first computing function for determining a correction factor i_ij for every image element ij is provided in the evaluating circuit, where k_ij=reference gray value/actual gray value, wherein every image element ij corresponds to an individual sensor of the reception surface, the reference gray values are determined for every individual sensor with a uniformly bright image without structures and, further, a second computing function is provided by which the determined actual gray value of every image element ij is multiplied by the associated correction factor k_ij, resulting in an image of the surface structure which is free from reference structures.

10. The arrangement according to claim 6, wherein a control circuit is provided, by which the reference structures are recorded and the recorded images are compared with the stored data whenever the apparatus is put into operation and/or after expiration of a predetermined operating period.

11. The arrangement according to 6, claims wherein a control circuit is provided by which the detection of the reference structures is initiated manually and comparison with the stored data can therefore be carried out at optional times.

12. The arrangement according to claim 2, wherein covers are provided for the reference structures arranged on the image scanning surface.

13. The arrangement according to claim 1, wherein the reference structures arranged on the scanning prism are printed, scratched in, etched, glued on in the form of a film or arranged in some other optically active way.

14. The arrangement according to claim 1, wherein an optical device is provided for reflecting and/or mixing reference structures into the illumination beam path or in the beam path reflected by the image scanning surface.

15. The arrangement according to claim 1, wherein grooves with different widths and different spacing and orientation are provided as reference marks and are configured for monitoring the image transfer, the MTF, the image scale, geometric distortion, gray step linearity, gray value number and/or signal-to-noise ration.