WO2015028993A1 - Hand geometry reader - Google Patents

Hand geometry reader Download PDF

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Publication number
WO2015028993A1
WO2015028993A1 PCT/IB2014/064176 IB2014064176W WO2015028993A1 WO 2015028993 A1 WO2015028993 A1 WO 2015028993A1 IB 2014064176 W IB2014064176 W IB 2014064176W WO 2015028993 A1 WO2015028993 A1 WO 2015028993A1
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WO
WIPO (PCT)
Prior art keywords
hand
hand geometry
light rays
geometry reader
transparent optic
Prior art date
Application number
PCT/IB2014/064176
Other languages
French (fr)
Inventor
Varun Akur Venkatesan
Original Assignee
Varun Akur Venkatesan
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Varun Akur Venkatesan filed Critical Varun Akur Venkatesan
Publication of WO2015028993A1 publication Critical patent/WO2015028993A1/en

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Classifications

    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06V—IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING
    • G06V40/00—Recognition of biometric, human-related or animal-related patterns in image or video data
    • G06V40/10—Human or animal bodies, e.g. vehicle occupants or pedestrians; Body parts, e.g. hands
    • G06V40/12—Fingerprints or palmprints
    • G06V40/13—Sensors therefor
    • G06V40/1324—Sensors therefor by using geometrical optics, e.g. using prisms

Definitions

  • the invention relates to capture and verification of biometric data, and more specifically to a hand geometry reader.
  • the object of the invention is to provide a hand geometry reader with reduction in the distance between the photo sensor and the target.
  • the object of the invention is achieved by a hand geometry reader, wherein the hand geometry reader comprises a first transparent optic defining a first optical volume, the first transparent optic comprising a first face adapted to admit at least a portion of light rays corresponding to a hand, the light rays undergoing total internal reflections within the first optical volume, and a photo sensor adapted to capture at least the portion of light rays exiting the first optical volume for acquiring an image of the hand.
  • the hand geometry reader further comprises a light source operably coupled to the first transparent optic, the transparent optic adapted to receive a light produced by the light source and direct the light onto the hand.
  • the first face is adapted to direct the light from the light source onto the hand.
  • the hand is positioned onto the first face.
  • a first portion of the first face is adapted to receive at least the portion of light rays corresponding to the hand and a second portion is adapted as a display.
  • the first face is adapted to admit at least the portion of light rays from a glancing angle of incidence.
  • the first face is adapted to admit at least the portion of light rays from a small angle of incidence.
  • At least a portion of at least one face of the first transparent optic is coated with an optical filter.
  • the optical filter has a peak wavelength of transmission of 880nm.
  • At least the portion of light rays encounter the optical filter a plurality of times.
  • the first face comprises one or more finger pegs projecting outwardly of the first transparent optic for receiving a portion of light from the hand in a predetermined manner.
  • the hand geometry reader further comprises a second transparent optic at an angle to the first face, the second transparent optic defining a second optical volume, the second transparent optic adapted to admit additional light rays corresponding to a side view of the hand the additional light rays undergoing total internal reflections within the second optical volume.
  • the additional light rays exiting the second optical volume are admitted into the first optical volume.
  • the additional light rays exiting the second optical volume are directed onto an additional photo sensor.
  • the light rays corresponding to a front view of the hand is admitted by the first transparent optic and the additional light rays corresponding to the side view of the hand is admitted by the second transparent optic.
  • the photo sensor is adapted to capture a plurality of distinct views of the hand over separate regions of pixels. According to yet another embodiment, the photo sensor is adapted to capture a plurality of distinct views of the hand over overlapping regions of pixels.
  • the hand geometry reader further comprises a processor operably coupled to the photo sensor, the processor configured to receive the image comprising the plurality of distinct views and segregate the plurality of distinct views into a plurality of separate images.
  • the hand geometry reader further comprises an optical device for redirecting light rays from an additional area onto the photo sensor.
  • the hand geometry reader further comprises a turning optic coupled to the first face via a medium of lower refractive index to admit the light rays at a glancing angle.
  • the first transparent optic is a wedge shaped slab.
  • the first optical volume comprises a fluid.
  • the first optical volume comprises a solid.
  • at least a portion of the first optical volume is a vacuum.
  • FIG 1 illustrates a schematic side view of an exemplary hand geometry reader as an example of a biometric system according to an embodiment herein;
  • FIG 2 illustrates a schematic front view of a hand geometry reader according to an embodiment herein;
  • FIG 3 a side view of a hand geometry reader comprising an imaging area dedicated for image capture of the geometry of a hand is illustrated according to an embodiment herein;
  • FIG 4 a front view of a hand geometry reader is illustrated according to an embodiment herein;
  • FIG 5 a transparent optic is illustrated according to an embodiment herein;
  • FIG 6 a transparent optic used for redirection of light from the scene towards the photo sensor is illustrated according to another embodiment herein;
  • FIG 7 illustrates an optical filter arranged on a face of a first transparent optic according to an embodiment herein.
  • FIG 8 is a schematic diagram illustrating a relative positioning of a first transparent optic and a second transparent optic according to an embodiment herein.
  • the invention is based on the concept of using an optic for reducing the distance between the target and the image capturing sensor. This assists in reducing the size of the device.
  • FIG 1 illustrates a schematic side view of an exemplary hand geometry reader as an example of a biometric system according to an embodiment herein.
  • the hand geometry reader 1000 comprises an imaging area 304 dedicated to capture an image of a hand to extract its geometry.
  • the imaging area 304 is made out of a first transparent optic 310 that transmits light from the scene in front of the hand geometry reader 1000 to a photo sensor 308.
  • the first transparent optic defines a first optical volume.
  • the term optical volume herein refers to the volume wherein the light undergoes to and forth reflection before exiting the transparent optic.
  • the imaging area 304 can also act as a display for displaying.
  • the transparent optic 310 may be wedge shaped or planar.
  • the hand geometry reader 1000 comprises one or more second transparent optics 305 that allow for imaging the hand from the side.
  • the one or more second transparent optics define respective second optical volumes.
  • the photo sensor 308 and the light source 309 are arranged adjacent to a side face of the transparent optic 310 such that light from the light source 309 can be transmitted to illuminate the scene and the photo sensor 308 can capture the light reflected from the scene.
  • the scene in this example may be a hand of a user positioned for imaging.
  • the transparent optic 310 provides the advantage of illuminating the scene and imaging the scene using the same optic. Additionally, this assist in reducing the size of the hand geometry reader 1000, and thus, making it less bulky.
  • the hand geometry reader 1000 comprises a processor 311 operably coupled to the light source 309, photo sensor 308 and I/O interfaces.
  • the user input is provided via the I/O interface to the processor 311.
  • the processor 311 is configured to control the light source 309 for illuminating the scene for biometric evaluation.
  • the image captured by the photo sensor 308 is acquired by the processor 311.
  • the processor 311 may be configured to store the acquired image into a memory.
  • FIG 2 illustrates a schematic front view of a hand geometry reader of FIG 1 according to an embodiment herein.
  • the hand geometry reader 1000 comprises an I/O interface area 300 dedicated for input and output functions.
  • the term output function herein refers to providing output, for example a display.
  • the term input function herein refers to receiving input.
  • the I/O interface area 300 comprises a display area 301 dedicated for displaying visual content and a keypad 302 for receiving input from a user.
  • a touch interface may be used for displaying and receiving input.
  • the whole of the I/O interface area 300 may be used for displaying or receiving input.
  • the display area 301 may be configured to display a logo or instructions that may be dynamically updated.
  • the light source 309 may comprise a plurality of light emitting devices.
  • the light source 309 may comprise a light illuminating device for illuminating the scene and a projector to project content to be displayed onto the display area 301.
  • the whole or part of the imaging area 304 may also be used as the display.
  • the whole or part of the imaging area 304 may act as the input interface.
  • the hand geometry reader 1000 may not have a dedicated I/O interface area 300, but the whole or part of the imaging area 304 can be utilized for I/O functions.
  • a first portion of the first transparent optic 310 may be adapted to receive at least a portion of light rays corresponding to the hand and a second portion of the transparent optic may be adapted as a display.
  • the light source 309 may be a projector or a multitude of slides with light sources in order to project various images into the display 301.
  • a set of finger pegs 306 projecting outwardly from the first transparent optic are provided.
  • the finger pegs 306 are provided at different locations for guiding the positioning of the hand of the user.
  • the finger pegs 306 may be optically transparent allowing perpendicular imaging of the hand. The perpendicular imaging is performed through the finger pegs 306 along the axis of the peg.
  • the hand geometry reader 1000 comprises a card swipe reader 313 for reading magnetic cards. Additionally, in an embodiment, the hand geometry reader 1000 comprises a radio frequency identity (RFID) card reader 314 for contactless reading of RFID cards.
  • RFID radio frequency identity
  • the hand geometry reader 1000 can comprise a plurality of authentication mechanisms.
  • FIG 3 a side view of a hand geometry reader 1000 comprising an imaging area 304 dedicated for image capture of the geometry of a hand is illustrated according to an embodiment herein.
  • the imaging area 304 is made out of a first transparent optic 310 that transmits light from the hand kept on the first face 503 to the photo sensor 308.
  • a light source 309 can illuminate the hand kept on the first face 503 via or through the first transparent optic 310 and the reflected light is captured and fed to the photo sensor 308 via the same transparent optic 310.
  • the first face 503 may be a retro-reflective material or coated with thereof in order to reject ambient light.
  • the light reflected from the hand will be significantly less than that from the retro-reflective material and a high contrast image of the silhouette of the hand will be obtained.
  • a first portion of the first face 503 may be adapted to receive light rays corresponding to the hand and a second portion of the first face 503 may be adapted as a display.
  • the hand geometry reader 1000 comprises a second transparent optic 305 configured to transmit light corresponding to another view of the hand and optically feed the image signals to the photo sensor 308 or a second photo sensor.
  • the image signals corresponding to the view captured by the second transparent optic 305 may be fed by the second transparent optic 305 to the photo sensor 308 directly or via the first transparent optic 310.
  • the view captured by the second transparent optic 305 is the side view of the hand.
  • the second transparent optic 305 is adapted to admit additional light rays corresponding to a side view of the hand and the admitted additional light rays undergo total internal reflections within the optical volume defined by the second transparent optic 305.
  • the hand geometry reader 1000 comprises a third transparent optic 510 for capturing a view of the hand opposite to the view captured by the first transparent optic 310.
  • the image signals captured by the third transparent optic 510 can be fed to the photo sensor 308 or another dedicated photo sensor.
  • the processor in such circumstances, may be configured to acquire separate images of the top, bottom and side views of the hand through the transparent optics 310, 510 and 305 respectively. Acquiring images of different views of the hand provides the advantage of obtaining a biometric evaluation with higher accuracy, lower false recognition rate (FRR).
  • FRR false recognition rate
  • the hand geometry reader 1000 comprises an I/O interface area 300 comprising a display area 301 and a keypad 302.
  • the light source 309 could also be adapted to emit additional light upwards to project various images into the display area 301.
  • the light source 309 can be used for illuminating the scene and also project visual content to the display area 301.
  • a set of finger pegs 306 at different locations are provided for guiding the positioning of the hand of a user.
  • the finger pegs 306 may be optically transparent allowing them to image perpendicular to the finger pegs 306 along the axis of the finger pegs 306.
  • a processor (for example, the processor 311 in FIG 1) controls the light in a manner to adaptively illuminating the scene for biometric evaluation.
  • a transparent optic 310 is illustrated according to an embodiment herein.
  • the transparent optic 310 for redirecting the light from the scene towards the photo sensor is a wedge 601.
  • a turning optic 602 is arranged for allowing light from a range of angles to enter into an optical volume 604.
  • the turning optic 602 can be a film comprising geometrical structures for turning the light incident onto it.
  • the light rays undergo successive internal reflections within the optical volume 604 before exiting. At each reflection, the light gets turned by the angled surface 606 closer to the critical angle and gets transported to the base 605 of the transparent optic 310, where it exits to fall on a photo sensor (for example, the photo sensor 308 in
  • an image of the object kept in front of the surface 602 is formed on the photo sensor.
  • the light source (for example, the light source 309 in FIG 3) could be arranged at the base 605 of the wedge 601 or behind the wedge 601.
  • the optical surface 602 of the transparent optic 310 could be coated with hydro-phobic material to resist water, oil and dust.
  • the transparent optic 310 used for redirection of light from the scene towards the photo sensor is illustrated according to another embodiment herein.
  • the transparent optic 310 may comprise any geometrical shape.
  • An optical volume 604 defined by the transparent optic 310 comprises an optical addendum or embossment on one face 503 of the transparent optic 310.
  • a turning optic 602 allows for light from a range of angles to enter the optical volume 604.
  • the light source (for example, the light source 309 in FIG 3) could be arranged at the base of the transparent optic 605 or behind the optical volume 604, depicted as 704.
  • an optical filter may be arranged on a face of the first transparent optic according to an embodiment herein.
  • the optical filter may be coated onto the face of the first transparent optic.
  • the optical filter allows certain wavelengths to be transmitted while other wavelengths to be absorbed or reflected.
  • the optical filter is applied on one face, the light rays reflected from that face can be filtered such that undesired wavelengths are reduced in intensity.
  • the paths of light rays of several wavelengths are illustrated in the shown example of FIG 7.
  • the light rays consist of desired wavelengths 1102 and undesired wavelengths 1101. These light rays travel via internal reflection inside the optical volume 604 contained by the faces 503 and 1104.
  • An optical filter 1105 is arranged on the face 1104 of the transparent optic 310.
  • a portion of the rays of undesired wavelengths 1101 are absorbed or reflected out of the optical volume 604 while the light rays of desired wavelengths 1102 are reflected with no or minimal attenuation towards the face 503. Subsequent reflections occur in the same manner at 1107 and 1108. Hence, a large portion of undesired wavelengths are attenuated via multiple filtering from a single face.
  • FIG 8 is a schematic diagram illustrating a relative positioning of a first transparent optic and a second transparent optic according to an embodiment herein.
  • the second transparent optic 305 may be an offshoot of the first transparent optic 310 such that light collected by both these transparent optics is combined and transported to the photo sensor.
  • the second transparent optic 305 images a side view of the view imaged by the first transparent optic 310.
  • the second transparent optic 305 may be an offshoot of the third transparent optic (for example, the third transparent optic 510 in FIG 3).
  • the hand geometry reader described in the embodiments herein may be operated in one or more of the following user interaction modes. For example, a user may approach the hand geometry reader and swipe his ID card or enter an ID number via the keypad.
  • the hand geometry reader acquires an image of the geometry of the hand of the user.
  • the hand geometry reader may be configured to compare the acquired geometry of the hand of the user with a plurality of stored hand geometry data sets. Based on the acquired geometry of the hand matching with a stored hand geometry, the hand geometry reader is configured to identify the user as candidate of the stored hand geometry. Thereafter, the hand geometry reader may authenticate the user based on the access permissions associated with the candidate.

Abstract

The present invention relates to a hand geometry reader, wherein the hand geometry reader comprises a first transparent optic defining a first optical volume, the first transparent optic comprising a first face adapted to admit at least a portion of light rays corresponding to a hand, the light rays undergoing total internal reflections within the first optical volume, and a photo sensor adapted to capture at least the portion of light rays exiting the first optical volume for acquiring an

Description

Description
HAND GEOMETRY READER
The invention relates to capture and verification of biometric data, and more specifically to a hand geometry reader.
Conventionally, images of hand geometry have been acquired using a camera where the optics require a certain distance from the target to the photo sensor as shown in FIG 1. This limitation creates bulky hand geometry readers which consist of multiple optics in an attempt to reduce the form factor. Such systems usually consist of a platen on which the hand is placed, a folding mirror that directs light from the hand to a lens system that redirects the light to the camera in a minified manner. Folding prisms have been used to revert the light path to a certain extent, but yet create bulky systems.
The object of the invention is to provide a hand geometry reader with reduction in the distance between the photo sensor and the target.
The object of the invention is achieved by a hand geometry reader, wherein the hand geometry reader comprises a first transparent optic defining a first optical volume, the first transparent optic comprising a first face adapted to admit at least a portion of light rays corresponding to a hand, the light rays undergoing total internal reflections within the first optical volume, and a photo sensor adapted to capture at least the portion of light rays exiting the first optical volume for acquiring an image of the hand.
According to an embodiment, the hand geometry reader further comprises a light source operably coupled to the first transparent optic, the transparent optic adapted to receive a light produced by the light source and direct the light onto the hand.
According to another embodiment, the first face is adapted to direct the light from the light source onto the hand.
According to yet another embodiment, the hand is positioned onto the first face.
According to yet another embodiment, a first portion of the first face is adapted to receive at least the portion of light rays corresponding to the hand and a second portion is adapted as a display. According to yet another embodiment, the first face is adapted to admit at least the portion of light rays from a glancing angle of incidence.
According to yet another embodiment, the first face is adapted to admit at least the portion of light rays from a small angle of incidence.
According to yet another embodiment, at least a portion of at least one face of the first transparent optic is coated with an optical filter.
According to yet another embodiment, the optical filter has a peak wavelength of transmission of 880nm.
According to yet another embodiment, at least the portion of light rays encounter the optical filter a plurality of times.
According to yet another embodiment, the first face comprises one or more finger pegs projecting outwardly of the first transparent optic for receiving a portion of light from the hand in a predetermined manner.
According to yet another embodiment, the hand geometry reader further comprises a second transparent optic at an angle to the first face, the second transparent optic defining a second optical volume, the second transparent optic adapted to admit additional light rays corresponding to a side view of the hand the additional light rays undergoing total internal reflections within the second optical volume.
According to yet another embodiment, the additional light rays exiting the second optical volume are admitted into the first optical volume.
According to yet another embodiment, the additional light rays exiting the second optical volume are directed onto an additional photo sensor.
According to yet another embodiment, the light rays corresponding to a front view of the hand is admitted by the first transparent optic and the additional light rays corresponding to the side view of the hand is admitted by the second transparent optic.
According to yet another embodiment, the photo sensor is adapted to capture a plurality of distinct views of the hand over separate regions of pixels. According to yet another embodiment, the photo sensor is adapted to capture a plurality of distinct views of the hand over overlapping regions of pixels.
According to yet another embodiment, the hand geometry reader further comprises a processor operably coupled to the photo sensor, the processor configured to receive the image comprising the plurality of distinct views and segregate the plurality of distinct views into a plurality of separate images.
According to yet another embodiment, the hand geometry reader further comprises an optical device for redirecting light rays from an additional area onto the photo sensor.
According to yet another embodiment, the hand geometry reader further comprises a turning optic coupled to the first face via a medium of lower refractive index to admit the light rays at a glancing angle.
According to yet another embodiment, the first transparent optic is a wedge shaped slab. According to yet another embodiment, the first optical volume comprises a fluid. According to yet another embodiment, the first optical volume comprises a solid. According to yet another embodiment, at least a portion of the first optical volume is a vacuum.
The present invention is further described hereinafter with reference to illustrated embodiments shown in the accompanying drawings, in which:
FIG 1 illustrates a schematic side view of an exemplary hand geometry reader as an example of a biometric system according to an embodiment herein;
FIG 2 illustrates a schematic front view of a hand geometry reader according to an embodiment herein;
FIG 3 a side view of a hand geometry reader comprising an imaging area dedicated for image capture of the geometry of a hand is illustrated according to an embodiment herein; FIG 4 a front view of a hand geometry reader is illustrated according to an embodiment herein;
FIG 5 a transparent optic is illustrated according to an embodiment herein;
FIG 6 a transparent optic used for redirection of light from the scene towards the photo sensor is illustrated according to another embodiment herein;
FIG 7 illustrates an optical filter arranged on a face of a first transparent optic according to an embodiment herein; and
FIG 8 is a schematic diagram illustrating a relative positioning of a first transparent optic and a second transparent optic according to an embodiment herein.
The invention is based on the concept of using an optic for reducing the distance between the target and the image capturing sensor. This assists in reducing the size of the device.
FIG 1 illustrates a schematic side view of an exemplary hand geometry reader as an example of a biometric system according to an embodiment herein. The hand geometry reader 1000 comprises an imaging area 304 dedicated to capture an image of a hand to extract its geometry. The imaging area 304 is made out of a first transparent optic 310 that transmits light from the scene in front of the hand geometry reader 1000 to a photo sensor 308. The first transparent optic defines a first optical volume. The term optical volume herein refers to the volume wherein the light undergoes to and forth reflection before exiting the transparent optic. The imaging area 304 can also act as a display for displaying. The transparent optic 310 may be wedge shaped or planar. A light source 309 illuminates the scene, via the transparent optic 310, and the reflected light is captured via the same transparent optic 310 and fed to the photo sensor 308. According to an embodiment, the hand geometry reader 1000 comprises one or more second transparent optics 305 that allow for imaging the hand from the side. The one or more second transparent optics define respective second optical volumes.
The photo sensor 308 and the light source 309 are arranged adjacent to a side face of the transparent optic 310 such that light from the light source 309 can be transmitted to illuminate the scene and the photo sensor 308 can capture the light reflected from the scene. The scene in this example may be a hand of a user positioned for imaging. The transparent optic 310 provides the advantage of illuminating the scene and imaging the scene using the same optic. Additionally, this assist in reducing the size of the hand geometry reader 1000, and thus, making it less bulky.
Referring still to FIG 1, according to an embodiment, the hand geometry reader 1000 comprises a processor 311 operably coupled to the light source 309, photo sensor 308 and I/O interfaces. The user input is provided via the I/O interface to the processor 311. According to an embodiment, the processor 311 is configured to control the light source 309 for illuminating the scene for biometric evaluation. The image captured by the photo sensor 308 is acquired by the processor 311. In an embodiment, the processor 311 may be configured to store the acquired image into a memory.
FIG 2 illustrates a schematic front view of a hand geometry reader of FIG 1 according to an embodiment herein. In the shown example of FIG 1, the hand geometry reader 1000 comprises an I/O interface area 300 dedicated for input and output functions. The term output function herein refers to providing output, for example a display. The term input function herein refers to receiving input. In the shown example of FIG 2, the I/O interface area 300 comprises a display area 301 dedicated for displaying visual content and a keypad 302 for receiving input from a user. However, in another embodiment, a touch interface may be used for displaying and receiving input. In aspects of a touch interface, the whole of the I/O interface area 300 may be used for displaying or receiving input. For example, the display area 301 may be configured to display a logo or instructions that may be dynamically updated. According to an embodiment, the light source 309 may comprise a plurality of light emitting devices. For example, the light source 309 may comprise a light illuminating device for illuminating the scene and a projector to project content to be displayed onto the display area 301. In embodiments, wherein a projector is used for projecting content to be displayed, the whole or part of the imaging area 304 may also be used as the display. In aspects, wherein a touch interface is used, the whole or part of the imaging area 304 may act as the input interface. In such aspects, the hand geometry reader 1000 may not have a dedicated I/O interface area 300, but the whole or part of the imaging area 304 can be utilized for I/O functions. In embodiments, wherein the whole or part of the imaging area 304 is used as the display, a first portion of the first transparent optic 310 may be adapted to receive at least a portion of light rays corresponding to the hand and a second portion of the transparent optic may be adapted as a display. According to one example, the light source 309 may be a projector or a multitude of slides with light sources in order to project various images into the display 301. Still referring to FIG 2, according to an embodiment, a set of finger pegs 306 projecting outwardly from the first transparent optic are provided. The finger pegs 306 are provided at different locations for guiding the positioning of the hand of the user. The finger pegs 306 may be optically transparent allowing perpendicular imaging of the hand. The perpendicular imaging is performed through the finger pegs 306 along the axis of the peg.
Referring still to FIG 2, according to an embodiment, the hand geometry reader 1000 comprises a card swipe reader 313 for reading magnetic cards. Additionally, in an embodiment, the hand geometry reader 1000 comprises a radio frequency identity (RFID) card reader 314 for contactless reading of RFID cards. Thus, the hand geometry reader 1000 can comprise a plurality of authentication mechanisms.
Referring now to FIG 3, a side view of a hand geometry reader 1000 comprising an imaging area 304 dedicated for image capture of the geometry of a hand is illustrated according to an embodiment herein. The imaging area 304 is made out of a first transparent optic 310 that transmits light from the hand kept on the first face 503 to the photo sensor 308. A light source 309 can illuminate the hand kept on the first face 503 via or through the first transparent optic 310 and the reflected light is captured and fed to the photo sensor 308 via the same transparent optic 310. The first face 503 may be a retro-reflective material or coated with thereof in order to reject ambient light. In such a case, the light reflected from the hand will be significantly less than that from the retro-reflective material and a high contrast image of the silhouette of the hand will be obtained. In aspects, wherein the first transparent optic 310 is adapted to receive light rays and as a display, a first portion of the first face 503 may be adapted to receive light rays corresponding to the hand and a second portion of the first face 503 may be adapted as a display.
Referring still to FIG 3, according to an embodiment, the hand geometry reader 1000 comprises a second transparent optic 305 configured to transmit light corresponding to another view of the hand and optically feed the image signals to the photo sensor 308 or a second photo sensor. The image signals corresponding to the view captured by the second transparent optic 305 may be fed by the second transparent optic 305 to the photo sensor 308 directly or via the first transparent optic 310. In an embodiment, the view captured by the second transparent optic 305 is the side view of the hand. The second transparent optic 305 is adapted to admit additional light rays corresponding to a side view of the hand and the admitted additional light rays undergo total internal reflections within the optical volume defined by the second transparent optic 305. According to an embodiment, the hand geometry reader 1000 comprises a third transparent optic 510 for capturing a view of the hand opposite to the view captured by the first transparent optic 310. The image signals captured by the third transparent optic 510 can be fed to the photo sensor 308 or another dedicated photo sensor. The processor, in such circumstances, may be configured to acquire separate images of the top, bottom and side views of the hand through the transparent optics 310, 510 and 305 respectively. Acquiring images of different views of the hand provides the advantage of obtaining a biometric evaluation with higher accuracy, lower false recognition rate (FRR).
Referring now to FIG 4, a front view of a hand geometry reader 1000 of FIG 3 is illustrated according to an embodiment herein. The hand geometry reader 1000 comprises an I/O interface area 300 comprising a display area 301 and a keypad 302. The light source 309 could also be adapted to emit additional light upwards to project various images into the display area 301. Thus, the light source 309 can be used for illuminating the scene and also project visual content to the display area 301.
Referring still to FIG 4, a set of finger pegs 306 at different locations are provided for guiding the positioning of the hand of a user. The finger pegs 306 may be optically transparent allowing them to image perpendicular to the finger pegs 306 along the axis of the finger pegs 306. A processor (for example, the processor 311 in FIG 1) controls the light in a manner to adaptively illuminating the scene for biometric evaluation.
Referring now to FIG 5, a transparent optic 310 is illustrated according to an embodiment herein.
As shown in the example of FIG 5, the transparent optic 310 for redirecting the light from the scene towards the photo sensor (for example, the photo sensor 308 in FIG 1) is a wedge 601. The wedge
601 may be an optical transparent material such as glass or PMMA. A turning optic 602 is arranged for allowing light from a range of angles to enter into an optical volume 604. The turning optic 602 can be a film comprising geometrical structures for turning the light incident onto it. Light enters the optical volume 604 at a glancing angle and the turning optic 602 turns the light so that the difference with the critical angle of is reduced. The light rays undergo successive internal reflections within the optical volume 604 before exiting. At each reflection, the light gets turned by the angled surface 606 closer to the critical angle and gets transported to the base 605 of the transparent optic 310, where it exits to fall on a photo sensor (for example, the photo sensor 308 in
FIG 1). Thus an image of the object kept in front of the surface 602 is formed on the photo sensor.
According to an embodiment, the light source (for example, the light source 309 in FIG 3) could be arranged at the base 605 of the wedge 601 or behind the wedge 601. The optical surface 602 of the transparent optic 310 could be coated with hydro-phobic material to resist water, oil and dust.
Referring now to FIG 6, a transparent optic 310 used for redirection of light from the scene towards the photo sensor is illustrated according to another embodiment herein. In the shown example of FIG 6, the transparent optic 310 may comprise any geometrical shape. An optical volume 604 defined by the transparent optic 310 comprises an optical addendum or embossment on one face 503 of the transparent optic 310. A turning optic 602 allows for light from a range of angles to enter the optical volume 604. The light source (for example, the light source 309 in FIG 3) could be arranged at the base of the transparent optic 605 or behind the optical volume 604, depicted as 704.
Referring now to FIG 7, an optical filter may be arranged on a face of the first transparent optic according to an embodiment herein. For example, the optical filter may be coated onto the face of the first transparent optic. The optical filter allows certain wavelengths to be transmitted while other wavelengths to be absorbed or reflected. As the optical filter is applied on one face, the light rays reflected from that face can be filtered such that undesired wavelengths are reduced in intensity. The paths of light rays of several wavelengths are illustrated in the shown example of FIG 7. The light rays consist of desired wavelengths 1102 and undesired wavelengths 1101. These light rays travel via internal reflection inside the optical volume 604 contained by the faces 503 and 1104. An optical filter 1105 is arranged on the face 1104 of the transparent optic 310. At the first reflection 1106, a portion of the rays of undesired wavelengths 1101 are absorbed or reflected out of the optical volume 604 while the light rays of desired wavelengths 1102 are reflected with no or minimal attenuation towards the face 503. Subsequent reflections occur in the same manner at 1107 and 1108. Hence, a large portion of undesired wavelengths are attenuated via multiple filtering from a single face.
FIG 8 is a schematic diagram illustrating a relative positioning of a first transparent optic and a second transparent optic according to an embodiment herein. As shown in the example of FIG 8, the second transparent optic 305 may be an offshoot of the first transparent optic 310 such that light collected by both these transparent optics is combined and transported to the photo sensor. As shown the second transparent optic 305 images a side view of the view imaged by the first transparent optic 310. Similarly, the second transparent optic 305 may be an offshoot of the third transparent optic (for example, the third transparent optic 510 in FIG 3). The hand geometry reader described in the embodiments herein may be operated in one or more of the following user interaction modes. For example, a user may approach the hand geometry reader and swipe his ID card or enter an ID number via the keypad. Thereafter, the user places his hand in the imaging area for imaging. The hand geometry reader acquires an image of the geometry of the hand of the user. The hand geometry reader may be configured to compare the acquired geometry of the hand of the user with a plurality of stored hand geometry data sets. Based on the acquired geometry of the hand matching with a stored hand geometry, the hand geometry reader is configured to identify the user as candidate of the stored hand geometry. Thereafter, the hand geometry reader may authenticate the user based on the access permissions associated with the candidate.
While this invention has been described in detail with reference to certain preferred embodiments, it should be appreciated that the present invention is not limited to those precise embodiments. Rather, in view of the present disclosure which describes the current best mode for practicing the invention, many modifications and variations would present themselves, to those of skilled in the art without departing from the scope and spirit of this invention. The scope of the invention is, therefore, indicated by the following claims rather than by the foregoing description. All changes, modifications, and variations coming within the meaning and range of equivalency of the claims are to be considered within their scope.

Claims

Claims: I Claim:
1. A hand geometry reader, comprising: a first transparent optic defining a first optical volume, the first transparent optic comprising a first face adapted to admit at least a portion of light rays corresponding to a hand, the light rays undergoing total internal reflections within the first optical volume, and a photo sensor adapted to capture at least the portion of light rays exiting the first optical volume for acquiring an image of the hand.
2. The hand geometry reader of claim 1 , further comprising a light source operably coupled to the first transparent optic, the transparent optic adapted to receive a light produced by the light source and direct the light onto the hand.
3. The hand geometry reader of claim 2, wherein the first face is adapted to direct the light from the light source onto the hand.
4. The hand geometry reader of claim 1 , wherein the hand is positioned onto the first face.
5. The hand geometry reader of claim 1, wherein a first portion of the first face is adapted to receive at least the portion of light rays corresponding to the hand and a second portion is adapted as a display.
6. The hand geometry reader of claim 1 , wherein the first face is adapted to admit at least the portion of light rays from a glancing angle of incidence.
7. The hand geometry reader of claim 1, wherein the first face is adapted to admit at least the portion of light rays from a small angle of incidence.
8. The hand geometry reader of claim 1, wherein at least a portion of at least one face of the first transparent optic is coated with an optical filter.
9. The hand geometry reader of claim 8, wherein the optical filter has a peak wavelength of transmission of 880nm.
10. A hand geometry reader according to claim 8 wherein at least the portion of light rays encounter the optical filter a plurality of times.
11. The hand geometry reader according to any of the preceding claims, wherein the first face comprises one or more finger pegs projecting outwardly of the first transparent optic for receiving a portion of light from the hand in a predetermined manner.
12. The hand geometry reader according to any of the preceding claims, further comprising a second transparent optic at an angle to the first face, the second transparent optic defining a second optical volume, the second transparent optic adapted to admit additional light rays corresponding to a side view of the hand the additional light rays undergoing total internal reflections within the second optical volume.
13. The hand geometry reader of claim 12, wherein the additional light rays exiting the second optical volume are admitted into the first optical volume.
14. The hand geometry reader according to claim 12, wherein the additional light rays exiting the second optical volume are directed onto an additional photo sensor.
15. The hand geometry reader according to claim 12, wherein the light rays corresponding to a front view of the hand is admitted by the first transparent optic and the additional light rays corresponding to the side view of the hand is admitted by the second transparent optic.
16. The hand geometry reader of claim 13, wherein the photo sensor is adapted to capture a plurality of distinct views of the hand over separate regions of pixels.
17. The hand geometry reader of claim 13, wherein the photo sensor is adapted to capture a plurality of distinct views of the hand over overlapping regions of pixels.
18. The hand geometry reader of claim 16 or 17, further comprising a processor operably coupled to the photo sensor, the processor configured to receive the image comprising the plurality of distinct views and segregate the plurality of distinct views into a plurality of separate images.
19. The hand geometry reader according to any of the preceding claims, further comprising an optical device for redirecting light rays from an additional area onto the photo sensor.
20. The hand geometry reader according any of the preceding claims, further comprising a turning optic coupled to the first face via a medium of lower refractive index to admit the light rays at a glancing angle.
21. The hand geometry reader according to any of the preceding claims, wherein the first transparent optic is a wedge shaped slab.
22. The hand geometry reader according to any of the preceding claims, wherein the first optical volume comprises a fluid.
23. The hand geometry reader according to any of the claim 1 to 21, wherein the first optical volume comprises a solid.
24. The hand geometry acquisition device according to any of the claims 1 to 21, wherein at least a portion of the first optical volume is a vacuum.
PCT/IB2014/064176 2013-09-01 2014-09-01 Hand geometry reader WO2015028993A1 (en)

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