Identity verification apparatus and fingerprint image pickup method

• US 7,577,279 B2
• Filed: 03/08/2004
• Issued: 08/18/2009
• Est. Priority Date: 03/13/2003
• Status: Expired due to Fees

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Sano, Emiko, Nakajima, Hajime, Shikai, Masahiro, Shiratsuki, Akihide
• Primary Examiner(s): KIM, CHONG R
• Application Number:
  US10/793,747
• Publication Number:
  US 20040179723A1
• Time in Patent Office: 1,989 Days
• Field of Search: None
• US Class Current: 382/124
• CPC Class Codes: G06V 40/1312 direct reading, e.g. contactless acquisition
• CPC Class Codes: G06V 40/1341 Sensing with light passing through the finger
• CPC Class Codes: G06V 40/14 Vascular patterns

Abstract

An identity verification apparatus includes a light source for applying light that can pass through an object to be detected and having a fingerprints to the object to be detected, an image pickup unit for picking up light emitted from the light source and passing through projections of the fingerprint and light emitted from the light source and passing through depressions of the fingerprint, and for generating a fingerprint image including dark portions corresponding to the projections and bright portions corresponding to the depressions, and a signal processing unit for image processing the fingerprint image generated by the image pickup unit to generate fingerprint information, and for verifying an identity based on the fingerprint information.

Claims

1. A fingerprint formation method comprising:

passing light through an object including a fingerprint surface having projections and depressions to form a pattern of light including dark portions corresponding to the projections and bright portions corresponding to the depressions due to light transmittance of internal tissues proximate the fingerprint surface;

forming an image of the pattern of light in a focal plane located, when forming the image, within the object and spaced from at least part of the fingerprint surface;

generating a fingerprint image from the pattern of light, the fingerprint image including dark portions corresponding to the projections and bright portions corresponding to the depressions;

smoothing the fingerprint image to produce a smoothed image; and

generating a difference image by arithmetically determining differences between the fingerprint image and the smoothed image to remove blood vessel images from the fingerprint image.

2. The method according to claim 1, wherein the focal plane is spaced from said fingerprint surface by a distance in a range from 0.1 mm to 1.0 mm when forming the image of the pattern of light.

3. A fingerprint image generating apparatus comprising:

a light source applying light that can pass through an object including a fingerprint surface having projections and depressions to form a pattern of light;

an image forming unit detecting the pattern of light formed by the light emitted by the light source and passing though the projections and the depressions of the fingerprint surface, the image forming unit comprising

an image pickup sensor having a focal plane that is located within the object and spaced from at least part of the fingerprint surface when forming an image, and forming an image of the pattern of light in the focal plane, and

an image formation unit receiving the image of the pattern of light and generating a fingerprint image including dark portions corresponding to the projections and bright portions corresponding to the depressions; and

an arithmetic operation unit arithmetically determining a difference between the fingerprint image generated by the image formation and a smoothed image producing by smoothing the fingerprint image to produce a difference image from which blood vessel images in the fingerprint image have been removed.

4. The fingerprint image generating apparatus according to claim 3, comprising an object holding member for holding the object.

5. The fingerprint image generating apparatus according to claim 4, wherein the object holding member includes a through hole passing through the object holding member for passage of the light passing through the object when supported by the object holding member and where the fingerprint surface of the object is not in contact with the object holding member.

6. The fingerprint image generating apparatus according to claim 4, wherein

the object holding member is a transparent plate for holding the object and contacting the fingerprint surface;

and

a surface of the transparent plate which the fingerprint surface contacts includes an anti-reflective film coating.

7. The fingerprint image generating apparatus according to claim 3, wherein the focal plane is spaced from the fingerprint surface by a distance in a range from 0.1 mm to 1.0 mm when forming the image of the pattern of light.

8. The fingerprint image generating apparatus according to claim 3, wherein the light from the light source has dominant wavelengths in a red or near-infrared region, and the image pickup sensor is responsive to light having wavelengths in the red or near-infrared region.

9. The fingerprint image generating apparatus according to claim 8, wherein the light from the light source has dominant wavelengths ranging from 630 nm to 780 nm, and the image pickup sensor is responsive to light having wavelengths ranging from 630 nm to 780 nm.

10. The fingerprint image generating apparatus according to claim 3 comprising a signal processing unit processing the fingerprint image to generate fingerprint information for verifying an identity based on the fingerprint information.