Abstract:
A biometric authentication device uses IR-VCSELs as light sources for performing a better biometric authentication by providing clearer images. A light guide module is introduced to minimize the size of the device. Moreover, the biometric authentication device uses a single image sensing module to gather the vein image and the fingerprint image into the same detection signal which is then analyzed and compared with the pre-stored vein feature data and fingerprint feature data. Therefore, the biometric authentication device can achieve an approach in lowering hardware costs, simplifying circuit designs and providing an outstanding performance.

Description:
[0001]    This application claims the benefit of Taiwan Patent Application Serial No. 101135647, filed Sep. 27, 2012, the subject matter of which is incorporated herein by reference. 
       BACKGROUND OF INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The invention relates to a device and a method for biometric authentication, and more particularly to the biometric authentication device and method which include the image-capturing and detecting the fingerprint and vein images of a user finger for identification. 
         [0004]    2. Description of the Prior Art 
         [0005]    To ensure security over conventional digital personal identification techniques such as those applying personal identification numbers, digital keys, hardware keys having built-in smart chips and so on, more and more personal identification and security systems are interested in adopting biometric authentication apparatuses, such as the biometric authentication apparatus by judging the fingerprints and/or vein growth under the skin. 
         [0006]    In the art, the fingerprint authentication technique can be seen in various Taiwan patents, such as those having the publication numbers 565094, M343215 and 201145179. Yet, in all of those teachings, the identification technique does involve only the identification upon fingerprints. Such a single biometric authentication means obviously provides only limited security protections. Further, in the aforesaid teachings, visible light sources are commonly used and thus inhibited to further detections, for example the investigation through the vein growth of the finger. The foregoing visible light sources are reflective light sources and are projected upward onto the contact surface between the first finger member of user finger and the device so as to generate reflective lights from the contact surface, which is further captured by the device to analyze the fingerprint image. However, though the vein image can be formed by the hemoglobin absorbing lights with specific wavelengths, yet these particular lights with specific wavelengths do not include the visible lights. Furthermore, this conventional fingerprint authentication needs to go through the finger to be depressed substantially onto the contact surface, and such a depression would change the density of the depressed portion on the finger and thus change the original distribution of the veins thereinside. Therefore, it is obvious that the aforesaid authentication method can only be applied to identify the fingerprint, but not relevant to the vein structure inside the first finger member of the tested finger. 
         [0007]    In a US patent with a publication number 20090185726, a 4-in-1 imaging apparatus is provided able to recognize an image for authentication of a user in reading the fingerprint, the finger vein, the palm and the palm vein. However, in this disclosure, only two application pairs are included; in which one is the pair of the fingerprint and the finger vein, and another is the pair of the palm and the palm vein. From the teaching, a time-division is performed to control two reflective light sources at different positions for processing the feature identifications. That is to apply a light source to verify the fingerprint and/or the palm, and another light source to verify the finger vein and/or the palm vein. Apparently, in this teaching, one more control circuit is required to share the identifications and thus complicated circuiting design is inevitable. 
         [0008]    In two related Taiwan patents with publication numbers M375256 and 201211914, vein identification techniques are taught, respectively. However, a common feature in between is that only the vein authentication technique is provided, and so it is clear that such an identification application is less secured. Further, in M375256, the whole apparatus is too big in occupation for lacking a relevant light guiding mechanism, while, in 201211914, neither an appropriate optical system nor a light guiding mechanism is disclosed. 
         [0009]    In a Taiwan patent with a publication number 200947315, a technique to verify both the fingerprint and the finger vein is disclosed. However, in this teaching, major efforts are focused on circuit design and data processing in image and identification verifications, and again neither an appropriate optical system nor a light guiding mechanism is disclosed. Further, in this teaching, 2-D capacitor types of the fingerprint image sensor and the vein image sensor are introduced to perform in order the fingerprint image and the vein image, and it is apparently that such an application can only contribute to a high hardware cost. Also, for two image sensors for different imaging processes are needed in this teachings, thus substantial difficulties and complexities in circuiting and imaging can be foreseen. 
         [0010]    In a US patent with a publication number 20110129128, a technique to verify both the fingerprint and the finger vein is also disclosed. In this teaching, major efforts are focused on circuit design and data processing in image and identification verifications, and again neither an appropriate optical system nor a light guiding mechanism is disclosed. Further, in this teaching, a resistance type or a capacitor type of semiconductor sensing plate is introduced to detect the fingerprint, while another image sensor accompanying a light source is to capture and identify the vein image. Obviously, different sensors for imaging the fingerprint and the vein can result in a higher hardware cost and more complicated circuiting for providing two sets of sensors for separate image capturing and data processing. 
         [0011]    In all the foregoing teachings, a common shortcoming is noticed. The common shortcoming is to regard the vein authentication method in palm or fingers, in which the feature of the oxygen-deficient hemoglobin in the vein to absorb lights with specific wavelengths is utilized to make possible the image capturing and further analyzing upon the vein by the CMOS or CCD, before a verification upon a user according to his/her biometric can be performed. However, according to the present art, the IR LED is the most popular light source and has a wider spectrum by compared to a laser diode. A wider spectrum for the IR LED implies that part of the lights would be absorbed by the peripheral tissues around the vein and consequently noises would be generated therefrom to further form obstacles for further image analysis. Therefore, by compared to the laser diode as a light source, the IR LED can only obtain an obscure image and thus an improvement thereupon is clear. 
       SUMMARY OF THE INVENTION 
       [0012]    Accordingly, A first purpose of the present invention is to provide a biometric authentication device, which an Infra-red (IR) Vertical-cavity Surface-emitting Laser (VCSEL) is used as a light source for the device. By utilizing the VCSEL to obtain more clear images for biometric authentication, the later-stage processing upon the images can be benefited therefrom so that the cost can be reduced and the performance can be enhanced by capturing more clearer and contrast enhanced images, by simplifying the following signal-processing and comparison, and by efficiently applying the software and the later stage elements. 
         [0013]    A second purpose of the present invention is to provide a biometric authentication device that can use a particular optical light guide mechanism to miniaturize the biometric authentication module such that the device can be applied to the portable apparatus such as notebook computers, tabular computers, and smart mobile phones. 
         [0014]    A third purpose of the present invention is to provide a biometric authentication device and method that can introduce a single image-sensing unit to simultaneously capture both the vein image and the fingerprint image into the same sensor signal so as to carry out follow-up analysis upon the vein and the fingerprint characteristics. Also, the feature of requiring only an image-sensing unit can contribute to reduce the hardware cost, to simplify the circuiting design of the circuit board, and to provide an efficiency processing. 
         [0015]    In the present invention, the biometric authentication device for identifying at least a biometric on a portion of the creature (portion-to-be-verified and PTBV, thereinafter) includes: 
         [0016]    a carrier base, having an upper opening for receiving the portion-to-be-verified, which the upper opening further has a base plane and at least one lateral surface; 
         [0017]    a position structure, located at the carrier base at a position respective to the upper opening, the position structure being used to assist the portion-to-be-verified to anchor at a predetermined position at the carrier base in the upper opening; 
         [0018]    at least one light source unit, located at the at least one lateral surface of the carrier base respective to the upper opening; in the case that the portion-to-be-verified reaches the predetermined position, the at least one light source unit being positioned laterally to the portion-to-be-verified, the at least one light source unit being able to project a lateral light onto the portion-to-be-verified, and at least one corresponding image response being generated; 
         [0019]    a light guide module, located inside the carrier base at a position under the base plane respective to the upper opening; and 
         [0020]    an image-sensing unit, located inside the carrier base to receive the at least one image response and further to form thereby a corresponding detection signal readable to a computer. 
         [0021]    In one embodiment of the present invention, the biometric authentication device can further include a filter of visible lights mounted inside or outside the lens of the image sensor so as thereby to filter out the visible lights and thus to increase the pattern identification on lights of specific wavelengths. 
         [0022]    To achieve the aforesaid first purpose of the present invention, the at least one light source unit further includes a plurality of Infra-red Vertical-cavity Surface-emitting Lasers (IR-VCSELs), and a vertical height h 1  between a mean central point of the at least one light source unit at a perpendicular direction and the base plane of the upper opening is no less than one half of a mean vertical thickness h 2  of the PTBV. By utilizing the VCSELs and/or IR-VCSELs to obtain more clear images for biometric authentication, the later-stage processing upon the images can be benefited therefrom so that the cost can be reduced and the performance can be enhanced by capturing more clearer and contrast-enhanced, by simplifying the following signal-processing and comparison, and by efficiently applying the software and the later stage elements. 
         [0023]    To achieve the aforesaid second purpose of the present invention, the light guide module can have at least one prism unit and be separated into a fingerprint-detecting area and a vein-detecting area. When the at least one lateral light projects on the PTBV, a fingerprint image and a vein image can be formed on the image-sensing unit through the fingerprint-detecting area and the vein-detecting area of the light guide module, respectively. Hence, such a particular optical light guide mechanism of the present invention can efficiently miniaturize the biometric authentication module. 
         [0024]    To achieve the aforesaid third purpose of the present invention, by providing the at least one light source unit to project the at least lateral light onto the PTBV, a fingerprint image and a vein image corresponding to the PTBV can be formed simultaneously. The fingerprint image and the vein image are formed on the image-sensing unit through the light guide module. Hence, the detection signal produced by the image-sensing unit and being readable to a computer can contain simultaneously messages of the fingerprint image and the vein image. Also, the feature of requiring only an image-sensing unit to obtain both kinds of images can contribute to reduce the hardware cost, to simplify the circuiting design of the circuit board, and to provide an efficiency processing. 
         [0025]    In addition, according to the present invention, the biometric authentication method for verifying at least a biometric on a portion of a creature (portion-to-be-verified or PTBV, thereinafter) comprises the steps of: 
         [0026]    providing a biometric authentication device, in which the biometric authentication device further includes a carrier base, at least one light source unit, an image-sensing unit and a control module; the carrier base being used to receive the PTBV, the at least one light source unit being to project a light onto the PTBV so as to generate a fingerprint image and a vein image corresponding to the PTBV, the image-sensing unit being to receive the fingerprint image and the vein image and thereby further to generate a detection signal readable to a computer; wherein the detection signal includes simultaneously messages of the fingerprint image and the vein image; wherein the control module connecting electrically at least with the at least one light source unit and the image-sensing unit is to receive the detection signal from the image-sensing unit; 
         [0027]    arranging the PTBV to the biometric authentication device so as thereby to generate simultaneously the detection signal including the messages of the fingerprint image and the vein image; 
         [0028]    the control module of the biometric authentication device receiving the detection signal and further extracting thereinside a fingerprint feature data from the fingerprint image and a vein feature data from the vein image; and 
         [0029]    applying a comparison unit to compare the fingerprint feature data and the vein feature data received from the image-sensing unit of the control module with the fingerprint feature data and the vein feature data pre-stored in the feature database so as to generate and output a comparison result. 
         [0030]    In one embodiment of the present invention, the biometric authentication device can further include a filter of visible lights mounted inside or outside the lens of the image sensor so as thereby to filter out the visible lights and thus to enhance the image performance on lights of specific wavelengths. 
         [0031]    All these purposes are achieved by the biometric authentication device and method described below. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0032]    The present invention will now be specified with reference to its preferred embodiment illustrated in the drawings, in which: 
           [0033]      FIG. 1  is a schematic perspective view of a first embodiment of the biometric authentication device in accordance with the present invention; 
           [0034]      FIG. 2A  is a cross-sectional view of  FIG. 1  along line A-A′; 
           [0035]      FIG. 2B  is a cross-sectional view of  FIG. 1  along line B-B′; 
           [0036]      FIG. 3A  shows another embodiment of the light source unit in accordance with the present invention; 
           [0037]      FIG. 3B  shows a further embodiment of the light source unit in accordance with the present invention; 
           [0038]      FIG. 4A  shows explodedly the position structure  20  and the light guide module  50  of  FIG. 1 ; 
           [0039]      FIG. 4B  is a schematically cross-sectional view of  FIG. 4A  along line C-C′; 
           [0040]      FIG. 5A  is a perspective view of the light guide module  50  of  FIG. 1 ; 
           [0041]      FIG. 5B  is a side view of  FIG. 5A ; 
           [0042]      FIG. 6A  shows schematically, in a top view, the effective detection area above the prism unit of the light guide  50  of  FIG. 1 ; 
           [0043]      FIG. 6B  shows schematically the optical path in the fingerprint-detecting area  51  of the prism unit of  FIG. 6A ; 
           [0044]      FIG. 6C  shows schematically the optical path in the vein-detecting area  52  of the prism unit of  FIG. 6A ; 
           [0045]      FIG. 7A  is a perspective view of another embodiment of the light guide module  50   a  and the position structure  20  in accordance with the present invention; 
           [0046]      FIG. 7B  is an exploded view of  FIG. 7A ; 
           [0047]      FIG. 8  shows schematically the optical path of the light guide module  50   a  of  FIG. 7A ; 
           [0048]      FIG. 9A  shows an application of the biometric authentication device of  FIG. 1  to a biometric authentication system; 
           [0049]      FIG. 9B  shows a block diagram of a first embodiment of the control module for the biometric authentication device of the present invention; 
           [0050]      FIG. 9 c    shows a block diagram of a second embodiment of the control module for the biometric authentication device of the present invention; 
           [0051]      FIG. 10  is a simplified flowchart to demonstrate the biometric authentication method in accordance with the present invention; 
           [0052]      FIG. 11A  shows schematically a typical application of the biometric authentication method of the present invention to a mean or low-level security need environment; 
           [0053]      FIG. 11B  shows schematically a typical application of the biometric authentication method of the present invention to a high security need environment; 
           [0054]      FIG. 12A  shows schematically a first example of vein detection in accordance with the present invention; 
           [0055]      FIG. 12B  shows schematically a second example of vein detection in accordance with the present invention; and 
           [0056]      FIG. 12C  shows schematically a third example of vein detection in accordance with the present invention. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0057]    The invention disclosed herein is directed to a device and a corresponding method for biometric authentication of a creature. In the following description, numerous details are set forth in order to provide a thorough understanding of the present invention. It will be appreciated by one skilled in the art that variations of these specific details are possible while still achieving the results of the present invention. In other instance, well-known components are not described in detail in order not to unnecessarily obscure the present invention. 
         [0058]    Referring now to  FIG. 1 ,  FIG. 2A  and  FIG. 2B , a perspective view of the first embodiment of the biometric authentication device in is accordance with the present invention, a cross-sectional view along line A-A′ of  FIG. 1  and a cross-sectional view along line B-B′ of  FIG. 1  are shown, respectively. In this embodiment, the biometric authentication device  1  for verifying at least a biometric on a portion of the creature (portion-to-be-verified and PTBV, thereinafter) includes a carrier base  10 , a position structure  20 , at least one light source unit  30 , an image-sensing unit  40 , a light guide module  50  and a control module  60 . In the present invention, the PTBV is embodied as a finger; particularly and preferably, the first finger member and the second finger member of the index finger. However, the PTBV can also be any of the middle finger, the thumb, the ring finger and the little finger. 
         [0059]    The carrier base  10  has an upper opening  11  for receiving the PTBV  9 , in which the upper opening  11  further has a base plane  111  and at least one lateral surface  112 . In this embodiment as shown, the carrier base  10  includes two opposing lateral surfaces  112  extending upright to the respective sides of the base plane  111  so as to form a U shape structure in the carrier base  10 , referred to  FIG. 2A . The middle empty portion of the U shape structure in the carrier base  10  is the upper opening  11 . In the case that the finger  9  to be tested is in the upper opening  11 , the finger  9  extends in the upper opening  11  between two opposing lateral surfaces  112 , by having the first finger member located largely at the front half portion of the upper opening  11  while the second finger member is located largely at the rear half portion of the upper portion  11 . 
         [0060]    The position structure  20  is located at the carrier base  10  at a position respective to the base plane  111  of the upper opening  11 . The position structure  20  is used to assist the PTBV  9  to anchor at a predetermined position at the carrier base  10  in the upper opening  11 . 
         [0061]    Referring now to  FIG. 4A  and  FIG. 4B , an exploded view of the position structure  20  and the light guide module  50  of the first embodiment of  FIG. 1  and a cross-sectional view of  FIG. 4A  along line C-C′ are shown, respectively. In this embodiment, the position structure  20  embodied as a finger-anchoring structure further includes a front window  21 , a rear window  22  and a position rib  23  between the front window  21  and the rear window  22 . As shown in  FIG. 4B , by having an inter-member valley  93  between the first finger member  91  and the second finger member  92  to fall onto the position rib  23 , the first finger member  91  can be anchored in the front window  21  and the second finger member  92  can be anchored in the rear window  22  includes a front window. At this time, the front lower end of the first finger member  91  would be rested on the front finger-anchoring area  25  of the position structure  20  so as to have the lower surface (having the fingerprint) of the first finger member  91  to contact tightly onto the top surface of the fingerprint-detecting area of the light guide module  50 , and thereby the fingerprint can be captured. Also, the rear lower end of the second finger member  92  would be rested on the rear finger-anchoring area  26  of the position structure  20 , and thus the lower surface of the second finger member  92  would face, but not depress, the vein-detecting area of the light guide module  50  so as to facilitate the capturing process of the vein image. In practice, the front finger-anchoring area  25  is lower than the position rib  23  and the rear finger-anchoring area  26 , such that a non-contact space would be formed between the upper surface of the vein-detecting area and the second finger member  92 . Upon such an arrangement, the plenty area of the vein  921  in the finger can be arranged to be detected, without sacrificing the detection of the fingerprint. In addition, the position structure  20  can have at least one light-shielding plate  24 , a front plate  27  and a rear plate  28 . The light-shielding plate  24  is located between the at least one light source unit  30  and the light guide module  50  and is there to avoid the light to enter the light guide module  50  from areas other than the front and rear windows  21 ,  22  of the position structure  20 , and thus substantial improvement upon the over-exposure phenomenon around the finger caused by the environmental lights and the diffractive lights can be obtained. In addition, possibility of the noise lights to enter the light guide module  50  from the front and rear windows  21 ,  22  of the position structure  20  can be also reduced. As shown, for the front and rear plates  27 ,  28  are to set along the front and rear surfaces of the light guide module  50 , comprehensive positioning help can be obtained while in assembling the light guide module  50  to the position structure  20 , and also a light-shielding effect against the noise light to enter the light guide module  50  via the front and rear surfaces thereof can be achieved. 
         [0062]    In the present invention, the at least one light source unit  30  is located inside the carrier base  10  at a position respective the at least one lateral surface  112  of the upper opening  11 . As shown in this embodiment shown in  FIG. 1 ,  FIG. 2A  and  FIG. 2B , a plurality of the light source unit  30  are included at each of the two lateral surfaces  112 . When the PTBV  9  is located at the predetermined position in the upper opening  11 , the light source units  30  are just lined to both lateral sides of the PTBV  9 , and at least one lateral light can be projected onto the PTBV so as to generate at least one image corresponding to the PTBV  9 . 
         [0063]    In the present invention, the at least one light source unit  30  includes a plurality of IR-VCSELs, preferably the IR-VCSELs having a wavelength between 780 nm and 850 nm. In this embodiment, the PTBV  9  is at least a portion of the first and second finger members  91 ,  92  of the finger  9 . When the PTBV  9  is set at the predetermined position inside the upper opening  11 , the plural IR-VCSELs  30  are lined to a lateral side of the PTBV  9  in a parallel manner; i.e. extending along the direction the same as the first and second finger members  91 ,  92  extend. Also, a vertical height h 1  between a mean central point of the at least one light source unit  30  at a perpendicular direction and the base plane  111  of the upper opening  11  is no less than one half of a mean vertical thickness h 2  of the PTBV  9 . For example, the mean vertical thickness h 2  of the second finger member of the index finger for an ordinary adult is ranged between 0.8 cm and 1.6 cm. Accordingly, to produce the biometric authentication device of the present invention suitable almost to all ordinary people, the vertical height h 1  between a mean central point of the at least one light source unit  30  at a perpendicular direction and the base plane  111  of the upper opening  11  is preferably larger than or equal 0.8 cm. By providing the biometric authentication device  1  of the present invention, the VCSELs and/or IR-VCSELs are utilized to obtain more clear images for biometric authentication application by their narrower spectrum (i.e., narrower distribution of the wavelength), so that the later-stage processing upon the images can be benefited therefrom. Namely, with clearer and contrast-enhanced image, many benefits from simplifying the comparison time and hardware processing and from reducing the processing elements, the cost can be reduced. However, for the IR-VCSEL is a high-directional element featured in torch-type illumination, a narrow divergence angle and a narrower optical spectrum, the option of applying the conventional reflective light source to the IR-VCSEL of the present invention would induce local (spots like) over-exposure or uneven exposure. 
         [0064]    As described above, the biometric authentication device  1  of the present invention is to arrange the at least one light source unit  30  at a vertical position higher than the PTBV  9  (compared at the horizontal center line  94 ). Also, the light projected from the at least one light source unit  30  to the PTBV  9  is a lateral light, not like the overhead light in the art. Upon such an arrangement, conventional shortcomings in exposure such as the aforesaid surface exposure and over-exposure can be greatly reduced. 
         [0065]    As shown in  FIG. 2A , the at least one lateral light projected by the at least one light source unit  30  defines a virtual central projection line  301 . The lateral light is deflected and/or reflected by the PTBV  9  to produce a corresponding image response. The image response goes downward into the carrier base  10  along a line defining a virtual vertical projection line  302 , and the angle Θ between the virtual central projection line  301  and the virtual vertical projection line  302  is ranged between 30 and 150 degrees. More specifically, when the vertical height h 1  is equal to one half of the mean vertical thickness h 2 , the angle Θ is preferably ranged between 30 and 85 degrees. For the at least one light source unit  30  is higher than the horizontal center line of the PTBV  9 , and also for the angle Θ is formed between the image response and the vertical direction, following advantages can be obtained: (1) the projection light won&#39;t hurt user eyes; (2) the oblique light projection can fit all sizes of the PTBV  9 ; and, (3) the arrangement of the light source units can help the lateral light to have a better penetration close to that of a direct penetrating light. 
         [0066]    Referring now to  FIG. 3A  and  FIG. 3B , two arrangements of the light source unit applicable to the biometric authentication device  1   a  or  1   b  are shown, respectively. In  FIG. 3A , the light source units  30   a  (i.e., IR-VCSELs) for the biometric authentication device  1   a  are mounted at a height substantially equal to the horizontal center line  94  of the PTBV  9 , and the angle Θ between the virtual central projection line  301   a  defined by the lateral light projected by the light source unit  30   a  and the virtual vertical projection line  302   a  defined by the at least one image response is ranged between 60 and 85 degrees. In  FIG. 3B , the light source units  30   b  (i.e., IR-VCSELs) for the biometric authentication device  1   b  are mounted at a height higher than the horizontal center line  94  of the PTBV  9 , and the angle Θ between the virtual central projection line  301   b  defined by the lateral light projected by the light source unit  30   b  and the virtual vertical projection line  302   b  defined by the at least one image response is ranged between 75 and 105 degrees. 
         [0067]    In the present invention, no matter what kind of the arrangement for the light source units is, either of  FIG. 2A ,  FIG. 3A  and  FIG. 3B , the conventional over-exposure phenomenon upon the applications of the IR-VCSELs on the vein authentication practice can be effectively resolved, by amending the light projection (defined by the virtual central projection line  301 ,  301   a  or  301   b ) of the light source unit onto a position higher than the horizontal center line  94  of the finger (PTBV)  9 . Also, by utilizing the internal light scattering of the finger  9 , the vein image can be successfully obtained. The diffraction by the skin of the finger  9  can be blocked by the light-shielding plate  24 . If the VCSEL light source units are to be mounted below the horizontal center line  94 , the light-shield plate  24  would have problems in isolating the surface over-exposure area of the finger  9 . In particular, if the VCSEL light source units are to be mounted right under the horizontal center line  94 , problems in localized spots of over exposure and uneven exposure would become the truth. 
         [0068]    Referring now to  FIG. 12A ,  FIG. 12B  and  FIG. 12C , three typical plots are demonstrated to explain the relationship between the position of the finger and the vein image for applications of the VCSEL as the light source unit. As shown in  FIG. 12A , in the case that the VCSEL light source unit  30   c  is positioned close to the bottom of the finger  9 , the vein image  95   c  would show to have unclear vein lines due to the diffractive lines  951  on the finger surface. As shown in  FIG. 12B , in the case that the VCSEL light source unit  30   d  is positioned on the horizontal center line  94  of the finger  9  and the light projection to the finger  9  is horizontal, the vein image  95   d  would show also to have unclear vein lines due to major over-exposure areas  952  at both sides of the finger  9 . As shown in  FIG. 12C , in the case that the VCSEL light source unit  30   e  is positioned higher than the horizontal center line  94  of the finger  9 , the vein image  95   e  can then be clear enough to show readable vein lines  954  although minor over-exposure areas  953  do still exist at both sides of the finger  9 . Hence, it is obvious that the arrangement of the light source units  30  in both positions and projection directions in accordance with the present invention can provide a solution to overcome the related disadvantages in the art. 
         [0069]    In the present invention, the image-sensing unit  40  is located inside the carrier base  10  and posed by an oblique angle to facing the light guide module  50 . The image-sensing unit  40  can receive the at least one image response of the PTBV  9  and can then thereby generate a detection signal readable to a computer. In the embodiment, the image-sensing unit  40  can further includes a lens set  41 , an image sensor  42 , a sensor circuit board  43  and a filter  44 . The lens set  41  gathers the imaging lights from the light guide module  50  and then further forms corresponding images on the image sensor  42 . The imager sensor  42  can be a CMOS, a CCD or any the like in the art. The sensor circuit board  43  is connecting electrically with the image sensor  42  and the control module  60 . The filter  44  is to filter out the visible lights so as to enhance the identification rate upon some lights with specific wavelengths. In this embodiment, the filter  44  is installed inside to the lens set  41  (between the lens set  41  and the image sensor  42 ). Yet, in another embodiment, the filter  44   a  can also be installed outside to the lens set  41  (between the lens set  41  and the light guide module  50 ). In addition, the filter  44  can be a long pass filter or a bandpass filter for some specific wavelengths. 
         [0070]    As shown in  FIG. 2A ,  FIG. 2B ,  FIG. 4A  and  FIG. 4B , the light guide module  50  is located inside the carrier base  10  at a position under the base plane  111  of the upper opening  11 . Specifically, the light guide module  50  is located right under the position structure  20 . The at least one image response of the PTBV  9  enters downward into the carrier base  10  by penetrating the corresponding windows  21 ,  22  of the position structure  20  at the base plane  111  of the upper opening  11 , and the at least one image response is led to the image-sensing unit  40  by the light guide module  50 . 
         [0071]    Refers now to  FIG. 4A ,  FIG. 4B ,  FIG. 5A  and  FIG. 5B , in which  FIG. 5A  is a perspective view of the light guide module  50  of the first embodiment of the biometric authentication device in accordance with the present invention shown in  FIG. 1  and  FIG. 5B  is a side view of  FIG. 5A  along line D-D′. The light guide module  50  includes at least one prism unit. In the first embodiment shown in  FIG. 4A  and  FIG. 5A , the light guide module  50  includes a single prism unit, which is further divided into a fingerprint-detecting area  51  and a vein-detecting area  52 . The fingerprint-detecting area  51  is located at a position corresponding to the front window  21 , while the vein-detecting area  52  is located at a position corresponding to the rear window  22 . When the at least one light source unit  30  projects the lateral light onto the PTBV  9 , a fingerprint image and a vein image corresponding to the PTBV  9  are simultaneously generated. The fingerprint image and the vein image are further guided by the fingerprint-detecting area  51  and the vein-detecting area  52  of the light guide module  50 , respectively, to simultaneously form images on the image-sensing unit  40 . The image-sensing unit  40  then produces the corresponding detection signal readable to a computer and containing messages of the fingerprint image and the vein image. Namely, the single image (or pattern) as the detection signal produced by the image-sensing unit  40  contains simultaneously the fingerprint image and the vein image, and each of the fingerprint image and the vein image occupies almost half area of the single image. For example, the right hand side of the single image shows the fingerprint image, while the left hand side of the single image shows the vein image. 
         [0072]    The fingerprint-detecting area  51  of the prism unit of the light guide module  50  further includes a top surface  511 , a bottom surface  512  opposing to the top surface  511 , an imaging surface  513  connecting in-between the top surface  511  and the bottom surface  512 , an anti-reflection surface  514  opposing to the imaging surface  513 , and a lateral anti-reflection surface  514   a  neighboring all the top surface  511 , the bottom surface  512 , the imaging surface  513  and the anti-reflection surface  514 . The top surface  511  is also neighbored to the front window  21  of the position structure  20 . When the PTBV  9  is anchored at the predetermined position in the upper opening  11 , the first finger member  91  of the finger  9  contacts the top surface  511  of the fingerprint-detecting area  51 . The fingerprint image entering the fingerprint-detecting area  51  of the prism unit (the light guide module  50 ) via the top surface  511  of the fingerprint-detecting area  51  would be reflected at least once by the bottom surface  512  of the fingerprint-detecting area  51  and then leave the fingerprint-detecting area  51  of the prism unit through the imaging surface  513  of the fingerprint-detecting area  51 . An oblique angle of the imaging surface  513  of the fingerprint-detecting area  51  would help the leaving fingerprint image to form correctly on a corresponding half area of the image-sensing unit  40 . On the anti-reflection surface  514  and the lateral anti-reflection surface  514   a , an anti-reflection material or a light-absorbing material is thereon plated, sprayed, adhered, coated, or painted so as to reduce the reflection on the anti-reflection surface  514  and the lateral anti-reflection surface  514   a  while lights in the fingerprint-detecting area  51  are projected onto the anti-reflection surface  514  and the lateral anti-reflection surface  514   a . Upon such an arrangement, the internal total reflection phenomenon that would degrade the imaging of the fingerprints can be substantially reduced. 
         [0073]    The vein-detecting area  52  of the prism unit of the light guide module  50  further includes thereof a corresponding top surface  521 , a corresponding bottom surface  522  opposing to the top surface  521 , a corresponding imaging surface  523  connecting in-between the top surface  521  and the bottom surface  522 , and a reflection surface  524  opposing to the imaging surface  523  and connecting obliquely the bottom surface  522 . The top surface  521  of the vein-detecting area  52  is neighbored to the rear window  22  of the position structure  20 . When the PTBV  9  is anchored at the predetermined position in the upper opening  11 , the second finger member  92  of the finger  9  is located above the top surface  521  of the vein-detecting area  52  in a manner of having no contact in between. The vein image entering the vein-detecting area  52  of the prism unit (the light guide module  50 ) via the top surface  521  of the vein-detecting area  52  would be reflected at least once individually by the reflection surface  524 , the top surface  521  and the bottom surface  522  of the vein-detecting area  52  and then leave the prism unit (the light guide module  50 ) through the imaging surface  523  of the vein-detecting area  52 . An oblique angle of the imaging surface  523  of the vein-detecting area  52  would help the leaving vein image to form on another half area of the image-sensing unit  40 . On the reflection surface  524  of the vein-detecting area  52 , a mirror may be adhered thereon, or a material with a high reflective index can be thereon plated, sprayed, adhered, coated, or painted so as to reflect the light of the vein image and so as to form an internal total reflection inside the prism unit (the light guide module  50 ). The imaging optical path of the vein image is dependent on a vertical height between the top surface  521  and the bottom surface  522  of the vein-detecting area  52  and a reflection frequency of the vein image inside the vein-detecting area  52 , in which the reflection frequency is determined by the oblique angle between the reflection surface  524  and the bottom surface  522  of the vein-detecting area  52 . 
         [0074]    As shown in  FIG. 5B , it is noted that a height difference h 5  exists between two top surfaces  511  and  521  of the fingerprint-detecting area  51  and the vein-detecting area  52 . The height difference h 5  is accounted to the optical path and is also there to enlarge the non-contact area under the second finger member  92  and thus able to enhance the identification of the vein lines with the help of the finger position rib  23  and the rear finger-anchoring area  26 . Further, it is also noted that another height difference h 6  exists between two bottom surfaces  512  and  522  of the fingerprint-detecting area  51  and the vein-detecting area  52 . The height difference h 6  determines the thickness difference of the prism unit (the light guide module  50 ) between the fingerprint-detecting area  51  and the vein-detecting area  52 , and importantly is the key to determine if the fingerprint image and the vein image can be finally integrated as a unique signal. 
         [0075]    As shown in  FIG. 4A  and  FIG. 4B , for the prism unit (the light guide module  50 ) is located beneath the position structure  20 , the workable detection range is smaller than the upper surface of the prism. Further, portion of the upper surface of the prism is shadowed by the light-shielding plate  24 . The front finger-anchoring area  25  is defined on the position structure  20  in front of the fingerprint-detecting area  51 , and is flush with the fingerprint-detecting area  51  of the prism unit (light guide module  50 ) so as thereby to provide a broader space for resting the finger. The rear finger-anchoring area  26  is defined on the position structure  20  at a position rear to the vein-detecting area  52 , and is flush with the top surface  521  of the vein-detecting area  52  of the prism unit (light guide module  50 ) and the position rib  23 . When the finger  9  is anchored in the upper opening  11 , a non-contact area can be formed between the rear finger-anchoring area  26  and the position rib  28 , and is there to prevent the second finger member  92  from any depression to distort the vein lines inside the second finger member  92 . 
         [0076]    Referring now to  FIG. 6A ,  FIG. 6B  and  FIG. 6C , a top view of an effective detection area above the prism unit of the light guide  50  of  FIG. 1 , the optical path in the fingerprint-detecting area  51  of the prism unit of  FIG. 6A , and the optical path in the vein-detecting area  52  of the prism unit of  FIG. 6A  are shown, respectively. For the light-shielding plate  24  blocks a portion of the space above the prism unit (the light guide module  50 ), the practical detection area of the device is smaller than the upper surface of the prism unit (the light guide module  50 ). The major difference in optical path between the fingerprint-detecting area  51  and the vein-detecting area  52  is that the optical path of the fingerprint image undergoes only one total reflection by the bottom surface  512  of the fingerprint-detecting area  51  inside the fingerprint-detecting area  51  before the fingerprint image goes to the image-sensing unit  40 , while the optical path of the vein image undergoes subsequent reflections, one by the reflection surface  524 , one by the top surface  521  and one by the bottom surface  522  (totally 3 reflections), inside the vein-detecting area  52  before the vein image goes to the image-sensing unit  40 . Apparently, lengths of the optical paths for the fingerprint image and the vein image are not identical. This is because the target to be detected (i.e., the fingerprint) in the fingerprint-detecting area  51  is located under the lower surface of the finger  9 , while the target to be detected (i.e., the vein) in the vein-detecting area  52  is located inside the finger  9 . Therefore, the optical path inside the vein-detecting area  52  is longer than that inside the fingerprint-detecting area  51 . The thickness difference h 6  at the bottom planes is to account for adjusting the final imaging position of the fingerprint and the vein images. 
         [0077]    Referring now to  FIG. 7A  and  FIG. 7B , another embodiment of the light guide module  50   a  for the biometric authentication device in accordance with the present invention is shown in a perspective view and an exploded view, respectively. In this embodiment, the light guide module  50   a  further includes a prism unit (the prism unit as described above), a mirror  56  and a mirror base  57  for mounting the mirror  56 . The prism unit is to form the fingerprint-detecting area  50   a , while the mirror  56  is to form the vein-detecting area. The prism unit (the fingerprint-detecting area  51   a ) located under the front window  21  of the position structure is mounted on a platform  572  of the mirror base  57 . The minor  56  is installed to an oblique surface  571  of the minor base  57 . A flat surface  573  is extended horizontally from and connects the oblique surface  56  at the side close to the image-sensing unit  40 . By providing the reflection minor  56  to the biometric authentication device for capturing the fingerprint image and the vein image simultaneously, the advantage of a simplified design without further consideration on different optical paths corresponding to plural prism units can be achieved in. However, in this embodiment, the adopting of the single prism unit to pair the corresponding mirror so as to form a reduced structured light guide module would pay as a tradeoff in a larger occupied volume and a lengthy optical path. 
         [0078]    As shown in  FIG. 8 , optical paths for the light guide module  50   a  of  FIG. 7A  are schematically shown. The angle θ 2  of the mirror  56  is ½ of the oblique angle θ 1  of the imaging surface of the prism unit (the fingerprint-detecting area  51   a ); i.e. θ 1 =2θ 2 . The height h 7 +h 8  is defined as the total height measured from the top of the flat surface  573  of the mirror base  57  to the tip of the fingerprint-detecting area  51   a  of the prism unit, in which h 7  is the thickness of the fingerprint-detecting area  51   a  and h 8  is the distance between the top of the flat surface  573  and the top of the platform  57 . It is noted that h 8  might not be equal to the elevation height of the mirror  56 . In the present invention, the ratio of h 7  to h 8  is 0.67 (i.e. h 7 :h 8 =2:3). The elevation height of the minor  56  is determined by the angle θ 2  and the distance w 1  measured horizontally from the lower end of the mirror  56  to the lower end of the imaging surface of the prism unit (the fingerprint-detecting area  51   a ); i.e. the width of the flat surface  573 . Preferably, w 1  is equal to h 7 . In the case that the lateral light projects through the finger  9  at a specific angle, the penetrating light would be reflected by the mirror  56 , and then to leave the carrier base from the fingerprint-detecting area  51   a  of the prism unit. Apparently, in this embodiment, the adopting of the mirror to totally reflect all the incoming rays can also form the biometric authentication device and also can perform the image-capturing process. 
         [0079]    Referred now to  FIG. 9A  and  FIG. 9B , an application of the biometric authentication device of  FIG. 1  to a security system and a block diagram of a first embodiment of the control module for the biometric authentication device of the present invention are shown, respectively. In this application, the control module  60  of the biometric authentication device  1  connects electrically at least with the at least one light source unit  30  and the image-sensing unit  40 . The control module  60  is to control the illumination of the light source unit  30  and is to receive the detection signal from the image-sensing unit  40 , in which the detection signal includes simultaneously both the fingerprint image and the vein image. The detection signal is processed in advance before it is sent to an authentication module  70  for signal effective comparison. In the present invention, the authentication module  70  can be a built-in module or a foreign module for a system that requires security protection. In this application, the authentication module  70  can be connected with a computer apparatus  971 , a door-alarm apparatus  972 , a financial transaction apparatus  973  (a teller machine for example), or any the like. Also, the authentication module  70  can be built inside the biometric authentication device so as to form a compact and portable biometric authentication device with the authentication module  70 . The biometric authentication device can be a wireless device or a cabled device, both of which can be connect with a portable electronic information apparatus such as a notebook computer, a tabular computer, a smart phone, and so on. 
         [0080]    As shown in  FIG. 9B , the control module  60  further includes a detecting element  61 , a controller  62 , an image-processing unit  63  and a power module  64 . The detecting element  61  is to detect if or not the PTBV  9  is in the upper opening  11 . For various candidate parts already in the marketplace (such as photo detectors, touch switches, pressure sensor, and so on) can be introduced to act as the detecting element  61  of the present invention and for this detecting element  61  is not one of the major features of the present invention, details thereabout are omitted herein. The controller  62  connecting electrically with the detecting element  61  is to determine the at least one light source unit  30  to project the at least one lateral light according to a detection of the detecting element  61 . The image-processing unit  63  connecting electrically with the image-sensing unit  40  and the controller  62  is to receive the detection signal from the image-sensing unit  40  and to further perform a pre-management  631  and a feature-capturing management  632 . The power module  64  is to provide electricity to energize the biometric authentication device. In the present invention, the pre-management  631  is to perform de-noise and image-rounding processes upon the detection signal, and the feature-capturing management  632  is to extract a fingerprint feature data and a vein feature data from the fingerprint image and the vein image of the detection signal. 
         [0081]    In the present invention, the authentication module  70  is connecting electrically with the control module  60 . In the first application embodiment as shown in  FIG. 9A  and  FIG. 9B , the authentication module  70  is located exteriorly to the carrier base  10  of the device  1 , and is communicated, either wirelessly or by cables, with an I/O interface  65  of the control module  60 . The I/O interface  65  is also connected electrically with the controller  62  and the image-processing unit  63 . However, in another embodiment not shown in the figure, the authentication module  70  can also be directly built inside the device  1  and connected electrically with the image-processing unit  63  without detouring to the I/O interface  65 . 
         [0082]    In the present invention, the authentication module  70  further includes a user interface  71 , a feature database  72  and an authentication unit  73 . The user interface  71  for login a user. The feature database  72  is to pre-store at least the fingerprint feature data and the vein feature data of the user. The authentication unit  73  is to compare the fingerprint feature data and the vein feature data received from the image-processing unit  63  of the control module  60  with the fingerprint feature data and the vein feature data pre-stored in the feature database  72  so as to generate a comparison result for outputting to the user interface  71  (see block  74 ). In the case that the fingerprint feature data and the vein feature data of the image-processing unit  63  are forwarded to the feature database  72 , a login process is performed. At this time, an allowable signal will be issued to the I/O interface  65  and then the prospective login is accepted. On the other hand, in the case that the fingerprint feature data and the vein feature data of the image-processing unit  63  are forwarded to the authentication unit  73 , a comparing process is performed. The authentication unit  73  will perform the comparison between the incoming data and the pre-stored data and then generate a comparison result. The comparison result will be forwarded to the user interface  71  (see also block  74 ) to make known the comparison result. 
         [0083]    In  FIG. 9B , a foreign authentication module  70  is shown to help an identification process upon the testing in the device  1 . Yet, in  FIG. 9C , the authentication module  70  is directly constructed inside the biometric authentication device  1  so as to perform the identification inside the device  1 . Upon such an arrangement, the biometric authentication device  1  can be formed as a portable and systematic-modulated biometric authentication device. 
         [0084]    As shown in  FIG. 9C , the systematic biometric authentication device  1  can also include the same carrier base  10 , the same position structure  20 , the same light source unit  30 , the same image-sensing unit  40  and the same light guide module  50 , as the embodiment described above. The only difference between this embodiment and the previous embodiment is only at the internal structuring of the control module  60   a  and the human-machine interface  700 . As shown in  FIG. 9C , the control module  60   a  includes a detecting unit  61 , a micro-controller (MCU)  62   a , an image-processing unit (DSP)  63   a , a power module  64  and a memory unit  66 . The human-machine interface  700  further includes an I/O interface  701 , a user interface  702 , a mechanism for user login  703 , a mechanism for verifying user  704  and a starter  705 . In the control module  60   a , the micro-controller  62   a  is to communicate with the human-machine interface  700  and to coordinate all the operation of the internal elements. When the login process  703  is performed, the user interface  702  would send a signal to tell the micro-controller  62   a  via the dual I/O interface  701  that a login process needs to be executed. Then, the micro-controller  62   a  would initiate the image-sensing unit  40  and the light source unit  30  and send another signal back to the user interface  702  to acknowledge the user to initiate the login process by performing three times of image capturing process. The detecting element  61  is introduced to judge if three times of the image-capturing process have been performed. The image-sensing unit  40  forwards the captured images back to be temporarily stored in the register  661  of the memory unit  66 . Then, the register  661  would forward the images to the image-processing unit  63   a  for performing the image-processing. When the feature images arrive the image-processing unit  63   a , the pre-management  631  would be performed thereon to amend the images so as to have the contours inside the images easy to be identified. Thereafter, the feature-capturing management  632  is performed to obtain a result containing the fingerprint feature data and the vein feature data. The result is then forwarded to the memory unit  66  and to be stored in the feature database  662 . Also, at the same time, the micro-controller  62   a  is requested to issue a message to the user interface  702  to let known that the establishment of the user featured data is complete. At this time, the characteristic/feature forwarding routine of the present invention is fulfilled. 
         [0085]    The feature authentication routine is performed as follows. When the user places his/her finger  9  into the detection area and the detecting element  61  gets a positive detection, the detecting element  61  would issue a signal to the micro-controller  62   a . The micro-controller  62   a  would then send a corresponding signal to initiate the light source unit  30  and the image-sensing unit  40  to perform image-capturing. After the image-sensing unit  40  forwards the captured image data to the register  661  of the memory unit  66 , the pre-management  631  of the image-processing unit  63   a  would retrieve data inside the register  661  so as to begin the image-processing. The feature-capturing management  632  is then performed to process the data forwarded from the pre-management  631 , and the result in the feature-capturing management  632  would be forwarded to the authentication unit  633 . The authentication unit  633  would compare the data (including the fingerprint feature data and the vein feature data) from the feature-capturing management  632  with the corresponding pre-stored data in the feature database  662 , in which the feature database  662  can pre-store at least one the fingerprint feature data and the vein feature data of at least one user. The comparison result of the authentication unit  633  would be forwarded to the determination unit  634  for the determination unit  634  to decide if the user is a correct user. The decision result in the determination unit  634  would be forwarded to the micro-controller  62   a . In the case that the micro-controller  62   a  gets a wrong message from the determination unit  634 , a corresponding message would be issued to the user interface  702  to tell the user that his/her identification fails and a renewal might be needed. In the case that the micro-controller  62   a  gets a correct message from the determination unit  634 , a corresponding correct message would be also issued to the user interface  702  and, at the same time, another signal is generated and forwarded to the starter  705  to allow the user accessible to the system. 
         [0086]    Referring now to  FIG. 10 , a simplified flowchart to demonstrate the biometric authentication method in accordance with the present invention is shown. In step S 11 , the prism unit (the light guide module  50 ) and the image-sensing unit  40  are cooperatively used to capture the fingerprint image and the vein image which are combined in one single image. Then, in step S 12 , the image-sensing unit  40  forwards the aforesaid image to the image-processing unit  63 . In step S 13 , the image-processing unit  63  performs the feature-capturing management  632  to generate the corresponding fingerprint/vein feature data. In step S 14 , the corresponding fingerprint/vein feature data is sent to the feature database  72  and the authentication unit  73  of the authentication module  70  for performing feature matching comparison process so as thereby to verify if the user is correct (as shown in step S 15 ). 
         [0087]    Referring now to  FIG. 11A  and  FIG. 11B , typical applications of the biometric authentication method of the present invention to a mean/low security need environment and a high security need environment are shown, respectively. It is noted that the biometric authentication device of the present invention can process a single-function authentication and/or a multiple-function authentication. In the case that the biometric authentication device of the present invention is chosen to perform a single-function authentication (S 21 ) as shown in the example of  FIG. 11A  for a mean/low security need environment, a correct result of the authentication (S 25 ) can be obtained upon either one of the comparisons, the fingerprint (S 22 ) or the vein (S 23 ), is met (S 24 ). For example, in the plot of  FIG. 11A , the fingerprint comparison (S 22 ) is matched, but the vein comparison (S 23 ) fails. However, even the vein matching is failed in S 23 , the authentication result in S 25  is still correct. Apparently, such an authentication process meets popular needs, in particular well for the environment that some users might have problems in demonstrating clear fingerprints for some inevitable reasons. In this circumstance, the vein authentication can be more suitable. Nevertheless, both the fingerprint and the vein feature data of all the qualified users are recommended to be pre-stored in the memory unit of the biometric authentication device. On the other hand, if a dual biometric authentication device is chosen to perform the authentication (S 31 ) as shown in  FIG. 11B  for a high security need environment, a positive result of the authentication (S 35 ) can be obtained only upon both the comparisons, the fingerprint (S 32 ) and the vein (S 33 ), are simultaneously met (S 34 ). Such an application environment may include the financial and the research institutes. 
         [0088]    Further, the biometric authentication method in accordance with the present invention is to verify at least a biometric authentication on a portion of a creature (portion-to-be-verified or PTBV, thereinafter) and comprises the steps of: 
         [0089]    providing a biometric authentication device, the biometric authentication device comprising: a carrier base, at least one light source unit, an image-sensing unit and a control module; the carrier base being used to receive the PTBV, the at least one light source unit being to project a light onto the PTBV so as to generate a fingerprint image and a vein image corresponding to the PTBV, the image-sensing unit being to receive the fingerprint image and the vein image and thereby further to generate a detection signal readable to a computer; wherein the detection signal includes simultaneously messages of the fingerprint image and the vein image; wherein the control module connecting electrically at least with the at least one light source unit and the image-sensing unit is to receive the detection signal from the image-sensing unit; 
         [0090]    arranging the PTBV to the biometric authentication device so as thereby to generate simultaneously the detection signal including the messages of the fingerprint image and the vein image; 
         [0091]    the control module of the biometric authentication device receiving the detection signal and further extracting thereinside a fingerprint feature data from the fingerprint image and a vein feature data from the vein image; and 
         [0092]    applying a authentication unit to compare the fingerprint feature data and the vein feature data received from the image-sensing unit of the control module with the fingerprint feature data and the vein feature data pre-stored in the feature database so as to generate a comparison result. 
         [0093]    In accordance with the present invention, the biometric authentication device  1  able to identify the fingerprint and the vein feature simultaneously includes mainly at least one light source unit  30 , a prism unit (light guide module  50 ), a position structure  20 , an image-sensing unit  40  and a control module  60 . The user for the device  1  must firstly perform a login process to connect the user interface for determining the user options. Internally, the device  1  would acknowledge the feature database  72  to establish a user&#39;s feature data, and at the same time, the user is asked to place his/her finger  9  into the device  1 . While in the login process, the finger  9  is needed to stay in the device with the inter-member valley  93  between the first finger member  91  and the second finger member  92  to anchor upon the position rib  23  in the middle of the position structure  20 . Also, the front end of the first finger member  91  is to contact tightly at the top surface  511  of the fingerprint-detecting area  51  of the prism unit (light guide module  50 ), while the rear end of second finger member  92  is to be located in the rear finger-anchoring area  26 . Then, the detecting element  61  would sense the finger  9  and notify the controller  62  the existence of the finger  9  so as to activate the light source unit  30  and the image-sensing unit  40 . The image-sensing unit  40  would perform the imaging exposure control according to its firmware settings, in which the exposure control is obtained by controlling the shutter speed. Through the foregoing exposure control, relevant image exposure can be better achieved even upon facing users with different finger thicknesses. The captured images would be forwarded to the image-processing unit  63  for performing pre-management  631  so as to make clear the contours in the fingerprint and the vein images. After the pre-management  631 , the amended images are then forwarded to the feature-capturing management  632  for performing the extracting of the required biometric. The extracted feature data are then compared with the corresponding feature data pre-stored in the feature database  72 . The comparison result is finally outputted to the user interface  71 . One merit of the device  1  in accordance with the present invention is that the security levels can be variously selected according to the practical needs. While in a mean/low security need circumstance, the correct authentication result can be obtained by matching any single one of the feature, the fingerprint or the vein. Such a circumstance can be found in a door-alarm system for plenty of the qualified users might have problems to provide a clean finger. On the other hand, if an application environment needs higher security control, the correct authentication result can be obtained only by matching both two features, the fingerprint and the vein. Such an application can avoid loss from a piracy feature data and can be seen in most of the financial units and the classified districts. 
         [0094]    While the present invention has been particularly shown and described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and detail may be without departing from the spirit and scope of the present invention.