Device for investigation of a finger relief

• US 4,385,831 A
• Filed: 09/22/1980
• Issued: 05/31/1983
• Est. Priority Date: 09/22/1980
• Status: Expired due to Term

• Current Assignee: Siemens Corp. (Siemens AG)
• Original Assignee: Siemens Corp. (Siemens AG)
• Inventors: Ruell, Hartwig
• Primary Examiner(s): McGraw, Vincent P.
• Application Number:
  US06/189,176
• Time in Patent Office: 981 Days
• Field of Search: 356/71, 356/394, 250/566, 340/146.3 E, 350/3.71
• US Class Current: 356/71
• CPC Class Codes: A61B 5/1172 using fingerprinting
• CPC Class Codes: G06V 40/1312 direct reading, e.g. contactless acquisition

Abstract

The fingerprint sensor device derives an electric output signal in accordance with the topographic relief of a finger under investigation. The sensor incorporates a radiation source, a fingerbed, a first radiation transmitting device, a scanning device, a second radiation transmitting device, and a measuring device responsive to the radiation. The fingerbed has an opening for passing a beam of radiation (light or ultrasound, for instance) from the source therethrough. The scanning device scans this beam of radiation across the finger. Thus, the finger relief is directly scanned by a beam of small impingement spot. The back scattered radiation is directed to the measuring device. Here, the intensity distribution is determined.

Claims

1. A device for investigating the pattern of a finger, comprising in combination:

(a) a source for emitting a beam of radiation;

(b) a fingerbed for supporting said finger, said fingerbed defining an opening which leaves free an area of the skin of said finger for investigation, when said finger rests in said fingerbed;

(c) means for passing said beam of radiation to said area under investigation, said beam thereby forming a spot of impingement on said area which has an extension that is smaller than the distance between two adjacent ridges on said skin under investigation;

(d) means for raster scanning said impingement spot in two dimensions over said area under investigation, said finger skin area thereby scattering back a beam of radiation which is modulated in accordance with said pattern on said area, said scanning means comprising a reflection hologram which is tiltable about an axis;

(e) measuring means responsive to said radiation;

(f) lens means for collecting and transmitting said back-scattered beam of radiation to said measuring means, said measuring means thereby measuring the distribution of the back-scattered radiation in accordance with the ridge-valley pattern of said area under investigation; and

(g) output means associated with said measuring means for producing an output signal representing the intensity of back-scattered radiation.

2. The device according to claim 1, wherein said radiation source is adapted to emit a beam of electromagnetic waves.

3. The device according to claim 2, wherein said radiation source is adapted to emit a light beam.

4. The device according to claim 3, wherein said light source is a laser.

5. The device according to claim 3, wherein said means for passing said beam of radiation to said finger contains a first lens for focussing said beam on said finger area.

6. The device according to claim 3, wherein said means for transmitting said reflected beam of radiation contains a second lens for casting an image of said finger area onto said measuring means.

7. The device according to claim 3, wherein said measuring means comprises a photodetector having a light sensitive area for measuring the distribution of light impinging on said area.