Compact, simple, 2D raster, image-building fingerprint scanner

• US 6,122,394 A
• Filed: 05/01/1997
• Issued: 09/19/2000
• Est. Priority Date: 05/01/1996
• Status: Expired due to Term

• Current Assignee: RPX Clearinghouse LLC (RPX Corporation)
• Original Assignee: Xros, Inc. (Nortel Networks Corporation)
• Inventors: Downing, Philip, Slater, Timothy G., Neukermans, Armand P.
• Primary Examiner(s): Mehta, Bhavesh
• Assistant Examiner(s): CHAWAN, SHEELA C
• Application Number:
  US08/846,837
• Time in Patent Office: 1,237 Days
• Field of Search: 382/124, 382/126, 382/212, 382/125, 382/127, 382/115, 382/116, 382/181, 382/120, 340/146, 340/71, 356/168, 356/165, 356/167, 359/196
• US Class Current: 382/124
• CPC Class Codes: G02B 26/085 the reflecting means being moved or deformed by electromagnetic means
• CPC Class Codes: G06V 10/12 Details of acquisition arrangements; Constructional details thereof
• CPC Class Codes: G06V 40/1324 by using geometrical optics, e.g. using prisms G06V40/1312 takes precedence
• CPC Class Codes: G06V 40/1329 Protecting the fingerprint sensor against damage caused by the finger

Abstract

A beam (38) of electromagnetic radiation deflected by a moving mirror plate (56) of a micromachined scanner (54) produces a two dimensional ("2D") raster (132) on a scanned surface (28) of a block (34). The block (34) is transparent to electro-magnetic radiation of pre-established wavelengths. A radiation inlet-face (36) of the block (34) admits the beam (38) that then impinges on the scanned surface (28) to exit the block (34) through a radiation outlet-face (42). After exiting the block (34), the beam (38) impinges upon a radiation detector (142). Total internal reflection ("TIR") of the beam (38) from the scanned surface (28) at fingerprint valleys and frustration of TIR at fingerprint ridges causes the radiation detector (142) to produce a time-varying electrical signal that represents the fingerprint. The scanned surface (28) may be formed by a patch (302) of resilient material, that may be tinted to be transparent only at the pre-established wavelength of the electro-magnetic radiation.

Claims

1. A compact, simplified, image-building scanner for generating a time-varying electrical signal that represents a fingerprint of a human subject, the scanner comprising:

a solid block formed from a material that is transparent to electro-magnetic radiation of a pre-established wavelength, said block including a scanned surface that the human subject touches with a finger for which a representation of the fingerprint is to be generated, said block also including a radiation inlet-face for admitting into said block a beam of electro-magnetic radiation having the pre-established wavelength, and said block further including a radiation outlet-face through which exits from said block at least a portion of electro-magnetic radiation admitted into said block through the radiation inlet-face, the radiation inlet-face and the radiation outlet-face of said block being distinct from the scanned surface thereof, said block being shaped so that the beam of electro-magnetic radiation entering through the radiation inlet-face impinges upon the scanned surface of said block before exiting from said block through the radiation outlet-face;

a radiation source for emitting a beam of electro-magnetic radiation having the pre-established wavelength;

a first micromachined scanner having a mirror for deflecting the beam emitted from said radiation source, the beam of electro-magnetic radiation emitted by said radiation source impinging upon the mirror of said first micromachined scanner and being deflected thereby to form a two dimensional ("2D") raster of the beam, the 2D raster formed by the deflected beam emitted from said first micromachined scanner being directed into said block through the radiation inlet-face thereof, whereby the 2D raster of the beam impinges upon the scanned surface of said block; and

a radiation detector which receives electro-magnetic radiation admitted into said block through the radiation inlet-face thereof, impinges upon the scanned surface of said block, and exits from said block through the radiation outlet-face thereof, said radiation detector being responsive to the received electro-magnetic radiation for producing the time-varying electrical signal that represents the fingerprint of the human subject'"'"'s finger then touching the scanned surface of said block.

2. The scanner of claim 1 wherein a material for said block is selected from a group consisting of glass and polymeric materials.

3. The scanner of claim 1 wherein the electro-magnetic radiation has a pre-established wavelength between 630 and 780 nanometers.

4. The scanner of claim 1 wherein the radiation outlet-face is distinct from the radiation inlet-face.

5. The scanner of claim 1 wherein the radiation outlet-face is identical to the radiation inlet-face.

6. The scanner of claim 1 wherein said radiation source is a laser diode.

7. The scanner of claim 1 wherein the beam emitted by said radiation source has a power between 1 and 5 milliwatts.

8. The scanner of claim 1 wherein said first micromachined scanner has a single mirror that rotates about two axes for deflecting the beam to form the 2D raster.

9. The micromachined scanner of claim 8 wherein rotation of the mirror for deflecting the beam along a first axis of the 2D raster is energized by a force applied to the micromachined scanner electro-magnetically, and rotation of the mirror for deflecting the beam along a second axis of the 2D raster is energized by a force applied to the micromachined scanner electrostatically.

10. The scanner of claim 1 wherein the beam, as deflected by said first micromachined scanner, moves across the scanned surface parallel to a first axis of the 2D raster with a sinusoidal velocity.

11. The scanner of claim 1 wherein the beam, as deflected by said first micromachined scanner, has a first scanning frequency parallel to a first axis of the 2D raster, and has a second scanning frequency parallel to a second axis of the 2D raster, the scanning frequency along the first axis being greater by a fixed integer ratio than the scanning frequency along the second axis.

12. The scanner of claim 1 further comprise a second micromachined scanner, each micromachined scanner having a mirror that rotates about a single axis for deflecting the beam, rotation of the mirror of the first of the micromachined scanners deflecting the beam to form a first axis of the 2D raster, and rotation of the mirror of the second of the micromachined scanners deflecting the beam to form a second axis of the 2D raster.

13. The micromachined scanners of claim 12 wherein movements of the mirrors for deflecting the beam along both axes of the 2D raster are energized by forces respectively applied to the mirrors electro-magnetically.

14. The scanner of claim 1 wherein said radiation detector is selected from a group consisting of a photo-cell, a photo-diode, or an avalanche photo-diode.

15. The scanner of claim 1 wherein a patch secured to the block provides the scanned surface of said block touched by the human subject'"'"'s finger.

16. The scanner of claim 15 wherein the patch is formed by a layer of resilient material secured to a harder material forming said block.

17. The scanner of claim 15 wherein the patch forming the scanned surface of said block is tinted to be transparent to electro-magnetic radiation at the pre-established wavelength, and to be less transparent to electro-magnetic radiation at wavelengths other than the pre-established wavelength.

18. The scanner of claim 1 wherein a resilient material forms the scanned surface of said block touched by the human subject'"'"'s finger.

19. The scanner of claim 18 wherein the scanned surface of said block is tinted to be transparent to electro-magnetic radiation at the pre-established wavelength, and to be less transparent to electro-magnetic radiation at wavelengths other than the pre-established wavelength.

20. The scanner of claim 1 wherein said block, said radiation source, said first micromachined scanner, and said radiation detector are all enclosed within a housing having a volume that is no larger than twenty-one (21) cubic-centimeters ("cm³ "), and the scanned surface of said block that the human subject'"'"'s finger touches having a surface area which is no smaller than three (3) square-centimeters ("cm² ").

21. The scanner of claim 1 wherein the block includes a lens of varying focus for maintaining a constant size for the beam throughout the 2D raster formed by the beam impinging on the scanned surface.

22. The scanner of claim 1 further comprising a controller for controlling operation of the scanner and including a fingerprint-data collection-unit for sampling fingerprint data from the time-varying electrical signal generated by the scanner, operation of the fingerprint-data collection-unit for sampling fingerprint data and operation of the controller for deflecting the beam along the 2D raster acquiring fingerprint data that are uniformly spaced along both axes of the 2D raster.

23. The scanner of claim 1 further wherein an image generated from fingerprint data obtained from the scanner depends only upon the time-varying electrical signal produced by the radiation detector, and upon beam-position signals supplied by said first micromachined scanner.

24. A compact, simplified scanner for generating a time-varying electrical signal that represents a fingerprint of a human subject, the scanner comprising:

a housing that encloses a radiation source, a micromachined scanner, and a radiation detector, said housing providing a scanned surface that the human subject touches with a finger for which a representation of the fingerprint is to be generated, the scanned surface that the human subject'"'"'s finger touches having a surface area which is no smaller than three (3) cm², and said housing occupying a volume that is no larger than twenty-one (21) cm³.

25. A method for verifying an individual'"'"'s identity comprising the steps of:

pressing an authentication token against a scanned surface of a compact, simplified, image-building scanner that includes;

a solid block formed from a material that is transparent to electro-magnetic radiation of a pre-established wavelength, said block including the scanned surface, said block also including a radiation inlet-face for admitting into said block a beam of electro-magnetic radiation having the pre-established wavelength, and said block further including a radiation outlet-face through which exits from said block at least a portion of electro-magnetic radiation admitted into said block through the radiation inlet-face, the radiation inlet-face and the radiation outlet-face of said block being distinct from the scanned surface thereof, said block being shaped so that the beam of electro-magnetic radiation entering through the radiation inlet-face impinges upon the scanned surface of said block before exiting from said block through the radiation outlet-face;

a radiation source for emitting a beam of electro-magnetic radiation having the pre-established wavelength;

a micromachined scanner having a mirror for deflecting the beam emitted from said radiation source, the beam of electro-magnetic radiation emitted by said radiation source impinging upon the mirror of said first micromachined scanner and being deflected thereby to form a two dimensional ("2D") raster of the beam, the 2D raster formed by the deflected beam emitted from said first micromachined scanner being directed into said block through the radiation inlet-face thereof, whereby the 2D raster of the beam impinges upon the scanned surface of said block; and

a radiation detector which receives electro-magnetic radiation admitted into said block through the radiation inlet-face thereof, impinges upon the scanned surface of said block, and exits from said block through the radiation outlet-face thereof, said radiation detector being responsive to the received electro-magnetic radiation for producing a time-varying electrical signal that represents an item pressed against the scanned surface of said block;

operating the scanner to obtain authentication-token by processing the time-varying electrical signal produced by the radiation detector to read the authentication token pressed against the scanned surface;

touching the scanned surface of the scanner with a finger;

operating the scanner to scan a fingerprint on the finger pressed against the scanned surface of the scanner to obtain fingerprint data from the time-varying electrical signal produced by the radiation detector; and

comparing the authentication-token information with the fingerprint data to verify the individual'"'"'s identity.