Biometric object sensor and method

• US 9,697,411 B2
• Filed: 09/09/2015
• Issued: 07/04/2017
• Est. Priority Date: 03/27/2012
• Status: Active Grant

• Current Assignee: Synaptics Incorporated
• Original Assignee: Synaptics Incorporated
• Inventors: Erhart, Richard, Thompson, Erik, Jandu, Jas Singh, Percy, Pam
• Primary Examiner(s): Gilliard, Delomia L
• Application Number:
  US14/849,315
• Publication Number:
  US 20150379323A1
• Time in Patent Office: 664 Days
• Field of Search: None
• CPC Class Codes: G06V 10/143 Sensing or illuminating at different wavelengths
• CPC Class Codes: G06V 40/1312 direct reading, e.g. contactless acquisition
• CPC Class Codes: G06V 40/40 Spoof detection, e.g. liveness detection
• CPC Class Codes: H04N 23/611 where the recognised objects include parts of the human body

Abstract

A biometric image sensor system and method is disclosed which may comprise a first light source having a first wavelength λ₁, a second light source having a second wavelength λ₂, a photodetector configured and positioned to receive light of the first wavelength λ₁ and light of the second wavelength λ₂ reflecting from a biometric object being imaged and to produce a first output indicative of the amount of reflectance of the light of the first wavelength λ₁ and a second output indicative of the amount of reflectance of the light of the second wavelength λ₂, and a computing device configured to compare the difference between the first output and the second output with an authenticity threshold.

Claims

1. A biometric image sensor comprising:

a first light source having a first wavelength λ

₁;

a second light source having a second wavelength λ

₂;

a photodetector configured and positioned to receive light of the first wavelength λ

₁ and light of the second wavelength λ

₂ reflecting from a biometric object being imaged and to produce a first reflectivity output indicative of the amount of reflectance of the light of the first wavelength λ

₁ and a second reflectivity output indicative of the amount of reflectance of the light of the second wavelength λ

₂; and

a processor configured to compare the difference between the first reflectivity output and the second reflectivity output to detect one or more of a leading edge, peak or trailing edge of a change in absorption of oxygen in blood of the biometric object.

2. The biometric image sensor of claim 1 wherein the biometric object is a finger.

3. The biometric image sensor of claim 2 wherein the finger is being imaged to obtain a fingerprint image.

4. The biometric image sensor of claim 3 wherein the processor is configured to compare successive samples to detect the change due to the presence of oxygenated blood in the finger.

5. The biometric image sensor of claim 1 wherein the first wavelength λ

₁ and the second wavelength λ

₂ are selected to coincide with a section of relatively high change in a reflectance vs. wavelength curve for the biometric object.

6. The biometric image sensor of claim 1 wherein the biometric object comprises human skin.

7. The biometric image sensor of claim 1 wherein the first wavelength λ

₁ is in the visible range of yellow light and the second wavelength λ

₂ is in the visible range of one of orange light and red light.

8. The biometric image sensor of claim 1, wherein the biometric object is a finger being imaged to obtain a fingerprint image, and wherein the processor is configured to measure a pulse rate from a periodic presence of oxygenated blood detected while the finger is kept on the biometric image sensor.

21. The biometric image sensor of claim 1, wherein the biometric object is a finger being imaged to obtain a fingerprint image, and wherein detection of one of the leading edge, the peak or the trailing edge of the change in the absorption of oxygen indicates that the finger is from a living body part.

9. A method of sensing an image of a biometric object comprising:

directing a first light source having a first wavelength λ

₁ on the biometric object;

directing a second light source having a second wavelength λ

₂ on the biometric object;

detecting the light of the first wavelength λ

₁ and the light of the second wavelength λ

₂ reflecting from the biometric object being imaged and producing a first reflectivity output indicative of the amount of reflectance of the light of the first wavelength λ

₁ and a second reflectivity output indicative of the amount of reflectance of the light of the second wavelength λ

₂, and

comparing, via a processor, the difference between the first reflectivity output and the second reflectivity output to detect one or more of a leading edge, peak or trailing edge of a change in absorption of oxygen in blood of the biometric object.

10. The method of claim 9 wherein the biometric object is a finger.

11. The method of claim 10 wherein the finger is being imaged to obtain a fingerprint image.

12. The method of claim 11 wherein successive samples are compared to detect the change due to a periodic presence of oxygenated blood in the finger.

13. The method of claim 9 wherein the first wavelength λ

₁ and the second wavelength λ

₂ are selected to coincide with a section of relatively high change in a reflectance vs. wavelength curve for the biometric object.

14. The method of claim 9 wherein the biometric object comprises human skin.

15. The method of claim 9 wherein the first wavelength λ

₁ is in the visible range of yellow light and the second wavelength λ

₂ is in the visible range of one of orange light and red light.

16. The method of claim 9, wherein the biometric object is a finger being imaged by a fingerprint sensor to obtain a fingerprint image, and wherein a pulse rate is measured from a periodic presence of oxygenated blood detected while the finger is kept on the fingerprint sensor.

22. The method of claim 9, wherein the biometric object is a finger being imaged to obtain a fingerprint image, and wherein detection of one of the leading edge, the peak or the trailing edge of the change in the absorption of oxygen indicates that the finger is from a living body part.

17. A biometric image sensor comprising:

a light source configurable to emit a first wavelength λ

₁ of light and a second wavelength λ

₂ of light;

a photodetector configurable and positionable to receive one or more electromagnetic radiation wavelengths reflected from a surface in response to the first wavelength λ

₁ and the second wavelength λ

₂ wherein the reflected electromagnetic radiation is reflecting from a biometric object being imaged to produce a first reflectivity output indicative of the amount of reflectance of the first wavelength λ

₁ of light and a second reflectivity output indicative of the amount of reflectance of the second wavelength λ

₂ of light; and

a processor configured to compare the difference between the first reflectivity output and the second reflectivity output to detect one or more of a leading edge, peak or trailing edge of a change in absorption of oxygen in blood of the biometric object.

18. The biometric image sensor of claim 17, wherein the biometric object is a finger being imaged to obtain a fingerprint image, wherein the processor is configured to compare successive samples to detect the change due to the presence of oxygenated blood in the finger.

19. The biometric image sensor of claim 17, wherein the biometric object is a finger being imaged to obtain a fingerprint image, and wherein the processor is configured to measure a pulse rate from a periodic presence of oxygenated blood detected while the finger is kept on the biometric image sensor.

20. The biometric image sensor of claim 17, wherein the first wavelength λ

₁ of light and the second wavelength λ

₂ of light are selected to coincide with a section of relatively high change in a reflectance vs. wavelength curve for the biometric object.

23. The biometric image sensor of claim 17, wherein the biometric object is a finger being imaged to obtain a fingerprint image, and wherein detection of one of the leading edge, the peak or the trailing edge of the change in the absorption of oxygen indicates that the finger is from a living body part.

24. The biometric image sensor of claim 17, wherein the leading edge of the change in the absorption of oxygen in the blood of the biometric object is detected.

25. The biometric image sensor of claim 17, wherein the peak of the change in the absorption of oxygen in the blood of the biometric object is detected.

26. The biometric image sensor of claim 17, wherein the trailing edge of the change in the absorption of oxygen in the blood of the biometric object is detected.

27. The biometric object of claim 17, wherein the processor is configured to compare the difference between the first reflectivity output and the second reflectivity output over no more than three samples.