Biometric sensor apparatus and methods

• US 20050008197A1
• Filed: 04/11/2003
• Published: 01/13/2005
• Est. Priority Date: 04/12/2002
• Status: Active Grant

• Current Assignee: Stmicroelectronics (Research & Development) Limited (STMicroelectronics NV)
• Original Assignee: STMicroelectronics Limited (STMicroelectronics NV)
• Inventors: Dennis, Carl
• Granted Patent: US 7,254,255 B2
• Time in Patent Office: Days
• US Class Current: 382/115
• CPC Class Codes: G06V 40/13 Sensors therefor
• CPC Class Codes: G06V 40/1388 using image processing

Abstract

The optical biometric sensor apparatus and methods for analyzing images of biometric features such as fingerprints are adapted to distinguish between live body members and inanimate objects, and to detect spoofing devices applied to live body members. Live body members are detected by transmitting IR light from a first IR light source through an object to an image sensor. The IR transmission characteristics of a live body member vary with the human heartbeat, and multiple images are analyzed to verify whether the object is a genuine live body member. A visible light source illuminates the object for obtaining a detailed image from the sensor for conventional biometric analysis. Transmitted IR images and reflected visible light images are also processed to detect the presence of spoofing devices applied to live body members. Multiple IR and visible light sources of different wavelengths may be used for this purpose.

Claims

1. Biometric sensor apparatus comprising:

a translucent platen having a first side against which a body member to be analyzed by the apparatus is placed, in use of the apparatus, and a second side;

at least one IR light source located on the first side of the platen for transmitting light through the body member and the platen to the second side of the platen;

an optical image sensor located on the second side of the platen for detecting light transmitted through the body member and the platen.

2. The apparatus of claim 1, further including at least one visible light source located on the second side of the platen and arranged such that light from the visible light source is transmitted through the platen and reflected by the body member for detection by the image sensor.

3. The apparatus of claim 1 or claim 2, further including data storage and processing means for storing and processing signals output from the image sensor.

4. The apparatus of claim 3, wherein said data storage and processing means is adapted to store and process a plurality of images obtained from the image sensor in response to IR light transmitted from the IR light source through an object placed on the platen so as to determine whether the object is a live body member.

5. The apparatus of claim 4, wherein the data processing means is adapted to analyze relative intensities of said plurality of images to determine whether variations in those intensities are consistent with characteristics of a human heartbeat.

6. The apparatus of any one of claims 3 to 5 when dependent on claim 2, wherein the data processing means is adapted to process at least one image obtained from the image sensor in response to IR light transmitted from the or each IR light source through a live body member placed on the platen and at least one image obtained from the image sensor in response to visible light from the or each visible light source reflected from the live body member placed on the platen so as to determine the presence or absence of a spoofing device applied to the live body member.

7. The apparatus of any preceding claim, including at least two IR light sources for transmitting IR light through the body member, each of the IR light sources emitting IR light in a waveband that is distinguishable from the waveband of any other of the IR light sources.

8. The apparatus of any preceding claim, wherein the or each IR light source emits IR light in a waveband in the range 700 nm to 1100 nm.

9. The apparatus of any preceding claim, including a first IR light source that emits IR light with a wavelength of 850 nm.

10. The apparatus of claim 9, including a second IR light source that emits IR light with a wavelength of 750 nm.

11. The apparatus of any preceding claim, including at least two visible light sources for reflecting visible light from the body member, each of the visible light sources emitting visible light in a waveband that is distinguishable from the waveband of any other of the visible light sources.

12. The apparatus of any preceding claim, wherein the image sensor is a CMOS image sensor.

13. A method for determining whether an object presented to a biometric sensor device is a live body member, comprising:

transmitting IR light from an IR light source through the object;

detecting IR light transmitted through the object using an optical image sensor;

obtaining a plurality of images from the image sensor in response to IR light transmitted from the IR light source through the object; and

processing said images to determine whether the object possesses predetermined characteristics of a live body member.

14. The method of claim 13, wherein the step of processing said images comprises analyzing relative intensities of said plurality of images to determine whether variations in those intensities are consistent with characteristics of a human heartbeat.

15. A method of determining whether a live body member presented to a biometric sensor device has a spoofing device applied thereto, comprising:

transmitting IR light from at least one IR light source through the body member;

detecting IR light transmitted through the body member using an optical image sensor;

obtaining at least one image from the image sensor in response to IR light transmitted from the IR light source through the body member;

reflecting visible light from at least one visible light source from the body member;

detecting visible light reflected from the body member using the optical image sensor;

obtaining at least one image from the image sensor in response to visible light from the visible light source reflected from the body member; and

processing said images so as to determine the presence or absence of a spoofing device applied to the body member.