Iris recognition camera system for mobile device

Abstract

An iris recognition camera system for mobile device includes a sensor and associated circuit, a lens and lighting sources including a lighting source element, a displaying light source element and IR LED light source elements, wherein the lighting sources are installed around the center of a camera lens with a certain clearance, and the lighting sources are attached on an FPCB and arranged on the four sides of the center of the camera lens and equipped with an FPCB cover for protection and a guiding mirror so that a user may conveniently acquire an image of his or her iris watching the image of his or her iris so as to identify and process only a living iris.

Claims

1. An iris recognition camera system for mobile device comprising a sensor and associated circuit, a camera lens and lighting sources including a lighting source element, a displaying light source element and IR LED light source elements, wherein the lighting sources are installed around the center of the camera lens with a predetermined clearance, and the lighting sources are attached on an FPCB and arranged on the four sides of the center of the camera lens and equipped with an FPCB cover for protection and a guiding mirror configured for acquisition by a user of an image of his or her iris watching the image of his or her iris thereby to determine that the iris is a living iris.

2. The iris recognition camera system for mobile device of claim 1, wherein, for a primary measure, the IR LED light source elements are arranged on the four sides of the camera lens and lighted simultaneously, diagonally and alternately lighted either from the upper and lower sides or from the left and right sides or lighted in a predetermined order which verifies the iris pattern and determines whether the iris is sham, then, for a secondary measure, the wavelength of infrared rays equal to or more than 800 nm is selected so as to strengthen sham iris detection performance.

3. The iris recognition camera system for mobile device of claim 1, wherein the upper surface, the lower surface or both of the upper and lower surfaces of the FPCB cover is etched to have fine protrusions and depressions that are configured to scatter or diffuse light or be coated or formed with a material containing a substance that scatters or diffuses light.

4. The iris recognition camera system for mobile device of claim 1, wherein a cross section of the FPCB cover is configured so that the upper and/or lower surface act as a concave spherical surface and convex spherical surface or a convex spherical and concave spherical surface, respectively, or act as a prism so as for the radiation angle of lighting by the lighting sources to intersect with the principal axis of the camera at the focal length.

5. The iris recognition camera system for mobile device of claim 1, wherein the guiding mirror is an elliptical mirror and the elliptical mirror is coated with a substance that reflects visible rays and transmits infrared rays.

6. The iris recognition camera system for mobile device of claim 3, wherein a cross section of the FPCB cover is configured so that the upper and/or lower surface act as a concave spherical surface and convex spherical surface or a convex spherical and concave spherical surface, respectively, or act as a prism so as for the radiation angle of lighting by the lighting sources to intersect with the principal axis of the camera at the focal length.

7. An iris recognition camera system for mobile device, comprising comprising a sensor and associated circuit, a camera lens and lighting sources including a lighting source element, a displaying light source element and IR LED light source elements wherein, for primary measure, the IR LED light source elements are installed around the center of the camera lens with a predetermined clearance and are configured to be lighted simultaneously, diagonally and alternately lighted either from the upper and lower sides or from the left and right sides or lighted in a predetermined order which verifies the iris pattern and determines whether the iris is sham, and, for secondary measure, the wavelength of infrared rays equal to or more than 800 nm is selected so as to strengthen sham iris detection performance and the lighting sources are attached on an FPCB and arranged on the four sides of the center of the camera lens and equipped with an FPCB cover for protection wherein at least one of an upper surface and a lower surface of the FPCB cover is etched to have fine protrusions and depressions configured to scatter or diffuse light or is coated or formed with a material containing a substance that scatters or diffuses light and a cross section of the FPCB cover is configured so that at least one of the upper and lower surface acts as a concave spherical surface and convex spherical surface or a convex spherical and concave spherical surface, respectively, or acts as a prism so as for the radiation angle of lighting by the lighting sources to intersect with the principal axis of the camera at the focal length, and further comprising an elliptical guiding mirror coated with a substance that reflects visible rays and transmits infrared rays and is configured for acquisition by a user of an image of his or her iris watching the image of his or her iris thereby to determine that the iris is a living iris.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a front view of en embodiment of the present invention.

(2) FIG. 2 is a longitudinal cross-sectional view of FIG. 1.

(3) FIG. 3 illustrates an FPCB partially selected from FIG. 1.

(4) FIG. 4 illustrates light sources arranged on an FPCB in FIG. 3.

(5) FIG. 5 is a front view of an FPCB cover with cross-sections of a variety of embodiments according to the present invention.

(6) FIG. 6 illustrates a guiding mirror according to an embodiment of the present invention and an example of an iris reflected thereon.

(7) FIG. 7 shows an example of a diagram that plots the radiation angle of an IR LED.

(8) FIG. 8 is a photograph that shows solid patterns on an iris according to an embodiment of the present invention.

(9) FIG. 9 illustrates patterns that changes depending on the direction of light according to an embodiment of the present invention.

(10) FIG. 10 is a photograph that arrows the uniformity of brightness of a surface directly irradiated by a light emitting element according to an embodiment of the present invention.

(11) FIG. 11 is a photograph that shows the uniformity of brightness of a surface irradiated by a light emitting element shielded with an FPCB cover.

(12) FIG. 12 is an orthogonal coordinate system that expresses an elliptical mirror according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

(13) The key technological principle of the present invention is to enhance the uniformity of brightness in the vicinity of an iris then improve the iris recognition performance by equipping an IR LED light source element with an inclined surface in its upper and lower side or with an FPCB cover on which protrusions and depressions that diffuse or scatter light, to effectively prevent static electricity being discharged via an IR LED light source element into internal devices, to operate by identifying a real, biological eye and to minimize the size and volume of an iris image-acquiring camera by employing an elliptical mirror optimized as an iris-guiding mirror.

(14) The present invention will now be described more specifically with reference to the following preferred embodiments, examples of which are illustrated in the accompanying drawings.

(15) Any structure or size of a feature of the subject matter may be simplified unless it poses a problem for the description of the present invention.

(16) As illustrated in FIG. 1, an iris recognition camera system for a mobile device according to the invention comprises an FPCB 10 that is composed of an image sensor and its associated circuit (not shown), a camera 70, a displaying light source element 50, a lighting source element 40 and IR LED light source elements 20, an FPCB cover 60 and a guiding mirror 30 that guides a user.

(17) The displaying light source element 50 guides a user's iris to be accurately placed on the object plane of the lens and allows a user to visually notice that iris recognition is being process, which may be an audible method using a sound device or combined method employing both the displaying light source element 50 and sound device.

(18) As illustrated in FIG. 2, the lighting source element 40 is separated by a certain clearance from the center line (O) of the lens 80 of the camera 70 and supports the biometric process that excludes a sham eye of an iris recognition camera system by changing the intensity of light and to deliberately adjust the size of the pupil.

(19) The object plane of the lens 80 on which an iris is placed is separated by a certain distance from the end of the camera 70, practically being the area in the vicinity of the lens center line (O) while the image-forming surface of the lens 80 is an image sensor surface.

(20) The lighting center line is aligned to have an inclined lighting angle corresponding to arctangent D/L with the lens center line (O) of the camera 70 so that the lighting center line should be oriented to the object plane of the lens 80.

(21) Here, the lighting sources 20;40;50 are disposed in parallel with or approximately in parallel with the lens center line (O) of the camera 70 and are equipped with an FPCB cover 60 that was designed and mounted so that the lighting sources may be separated from the lens center line (O) of the camera 70 and emit light to the object plane.

(22) As illustrated in FIG. 3, the IR LED light source elements 20 are configured to emit 2 or more wavelengths of infrared rays, are arranged to surround the circumference of the camera 70. Also, it may be required to analyze an iris image acquired by simultaneously lighting all the IR LED light source elements, diagonally and alternately lighting some of the IR LED light source elements 20 arranged on the four sides of the camera lens 80 or lighting in a predetermined order so as to detect a sham iris including a photograph or video.

(23) This is because a real iris has solid geometry of which pattern changes depending on the direction of lighting and consequently by the effect of the shadow, as illustrated in FIG. 8 and FIG. 9. A sham iris appeared in a photograph or video, however, doesn't change its pattern regardless of the change in the light direction.

(24) In other words, as illustrated in FIG. 3 and FIG. 9, an iris pattern appears as solid geometry and any size and depth of the solid is not identical to each other. When illuminated to acquired an iris image, the shape of pattern changes based on the light direction and flexion (groove) depth of the iris whereas a sham pattern in a photograph or video doesn't show such a change.

(25) Also changing is the luminance (brightness) of a living eye, depending on the wavelength of an infrared ray irradiated. Therefore, it may be required to install and diagonally and alternately light 2 or more IR LED light source elements 20 that have a different wavelength from each other to facilitate detection of a sham eye.

(26) As illustrated in FIG. 5, the upper and lower surfaces of the FPCB cover 60 may be required to be corroded (to have minute protrusions and depressions) so as to scatter light or be coated with a material containing a substance that scatters light so that the light from the IR LED light source elements 20 may be radiated uniformly.

(27) The cross-sectional shape of the FPCB cover 60 may be designed in a variety of ways, as shown in the expanded view in FIG. 5, to deliberately adjust the radiation angle or irradiation direction of the IR LED light source elements 20.

(28) Such an FPCB cover 60 is configured taking into consideration the tact that the radiation of a typical IR LED light source element 20 is not uniform into which the curvature and geometry of the material such as glass that covers the emitting point and the distance the irradiated rays travel factor. The uniformity of light was significantly enhanced, which is verified when comparing the uniformity of light on the surface that was directly radiated from an IR LED light source element and the uniformity of light on the surface that was radiated from an IR LED light source equipped with an FPCB cover 60, as illustrated in FIG. 10 and FIG. 11.

(29) As illustrated in FIG. 6, a guiding mirror 30 is mounted so that a user may look at his or her eye so as to position his or her iris at an optimized place. It is preferred to use a concave mirror, as the guiding mirror, to see a correct image only at a certain distance, but further preferred to use an elliptical mirror to adjust the size of image and to minimize the size of a camera.

(30) The present invention provides relative ease of manufacturing because the IR LED light source element 20 may be vertically assembled exploiting simple fixing tools. The assembly is assessed even with naked eyes in terms of whether it has been completed vertically, which may lead to ease of production quality control.

(31) Furthermore, the present invention prevents erroneous operation by shutting off any external interferences of static electricity, successfully produces a uniform amount of light. In other words, the present invention allows stable acquisition of an iris image based on uniform lighting.

(32) In other application, the direction or radiation angle of light may be designed as preferred by adjusting the cross-section of the FPCB cover 60, as illustrated in FIG. 5, so as to counter the discrepancy between the lens center line and lighting center line.

(33) For iris recognition, a user should accurately position his or her iris on the object plane of the camera 70, which requires an application to measure the definition of an image and inform the user, via voice guide, etc., that his or her iris is in focus so as to encourage the user to accurately position his or her iris on the object plan of the camera 70.

(34) Here, the threshold value of definition measurement fluctuates and is affected by the number of iris patterns, which sometimes leads to recognition failure, when the iris image is not definite even though the application determines it is in focus—in this case, “too many iris patterns.”

(35) On the other hand, there are some situations that lead to another recognition failure when the application determines that it is out of focus even though the iris image is definite—in this case, “too few iris patterns.” Therefore, it may be not appropriate to assess the definition of an iris image based on the threshold value measured.

(36) In this present invention, to enable a user to place his or her iris accurately on the object plane of the camera 70, primary guidance is provided using the guiding mirror 30, an elliptical mirror, and then secondary guidance is provided to perform acquiring at an accurate location by visually or aurally providing notification that iris recognition is being implemented via a sound device (not shown) or an displaying light source element 50 to a user using a program that determines whether iris recognition can be performed on an image by measuring the size of the iris and contrast, thereby increasing the success rate of iris recognition.

(37) That is, the present invention provides either visually or acoustically a user with information on the definition of an iris, whether it is an image that can be processed and whether it is an iris that meets a predetermined specification, which different from existing methods that determine the accuracy of iris location, irrespective of the iris definition, as per a threshold value that determines only whether it is in focus.

(38) Methods are employed that lead a user to locate his or her iris at a proper position by rendering the user, for example, look at a mirror or detect the iris position using a distance sensor, etc. When using a mirror, the user may see his or her iris image that has been reflected from the mirror located at a certain distance but cannot adjust the size of the reflected image. When using a distance sensor, it is also difficult to guide an iris to an accurate location because the sensor performance is limited in terms of operation speed and other restrictions, which leads to a considerable measurement error within a short distance.

(39) The present invention guides an iris by means of an elliptical mirror so as to locate the iris at an accurate position to acquire an image.

(40) The elliptical mirror may be expressed in an orthogonal coordinate system (with X and Y axes) as follows:
x.sup.2/a.sup.2+y.sup.2/b.sup.2=1(a>b)

(41) This may be plotted as illustrated in FIG. 12.

(42) where A=(a,0), B=(0,b), A′=(−a,0), B′=(0,−b) and the distance between the origin and A or A′ and B or B′ is a and b, respectively.

(43) Here, the set of points P(x,y), the sum of which distances from two foci F(c,0) and F′(−c,0) amounts to 2a, is an ellipse that passes A, B, A′ and B′. That is, by adjusting the value of a and b, the shape and focal length (distance between A and F) may also be adjusted. (b.sup.2=a.sup.2−c.sup.2 and a,b and c are positive numbers.)

(44) The present invention constructs en elliptical mirror by rotating an ellipse and cuts a part of the elliptical mirror with the point A as its center to use the partial elliptical mirror in guiding an iris. The distance between A, the center of the elliptical mirror, and F, one of the foci of the elliptical mirror, is a-c, the focal length. It is easy to locate an iris at F and it is also easy to find an accurate position because the definition changes very sharply as per the change of the focal length (horizontal movement). Additionally, an iris image of a desired size may be obtained by simply adjusting the values of a and b so as to adjust the size of an iris image that has been reflected from the elliptical mirror with the focal length maintained constant.

(45) In other words, a guiding mirror 30, which was manufactured from an elliptical mirror then has a circular or rectangular shape, is required to be installed at the front end of the camera 70.

(46) As illustrated in FIG. 1, FIG. 3 and FIG. 4, IR LED light source elements 20 are vertically mounted in an FPCB 10 and multiple infrared rays that have wavelengths different from each other and within 750 to 900 nm. Here, the IR LED light source elements 20 are arranged on the four sides of a camera 70 with a certain clearance. The IR LED light source elements 20 may be lighted simultaneously, diagonally and alternately lighted diagonally around a camera lens 80 either from the upper and lower sides or from the left and right sides or lighted in a predetermined order so as to verify whether the subject is a biological eye or sham.

(47) The upper and lower surfaces of an FPCB cover 60 are preferred to be etched (to have fine protrusions and depressions) so as to scatter light or be coated with a material containing a substance that scatters light so that the illumination of the IR LED light source elements 20 may be uniform. The cross-section of the FPCB cover 60 may be manipulated so as to obtain a radiation angle or direction of the lighting that is preferred. Any erroneous operation, by static electricity, of the IR LED light source elements 20 may be prevented by shutting off external interferences. Furthermore, it is simple to assemble and manufacture an iris recognition camera system according to the present invention, which raises productivity and maintains good quality.

(48) A guiding mirror 30 illustrated in FIG. 6 is manufactured from an elliptical mirror of which curvature is larger than that of a concave mirror so as to decrease the size of an iris image that is reflected on the guiding mirror 30 when seen from a constant distance. Therefore, a small volume (less than 1 cm.sup.3) of a camera may be materialized by reducing the size of the guiding mirror 30 so as to embed it in a mobile device.

(49) If a conventional camera is employed of which size has been reduced, it is difficult for a user to acquire an image of his or her iris. On the other hand, if a distance sensor or guiding mirror is additionally employed, it becomes almost impossible to apply it to a mobile device such as a mobile phone because the size of the camera increases.

(50) The present invention can allow a user to conveniently acquire an image of his or her iris while watching it and expand the applicability in mobile devices including smart phones and tablet PCs that are widely used currently, by embedding an iris recognition camera system, the size and volume of which can be minimized, in those mobile devices with reduced costs.