Patent Publication Number: US-2009232362-A1

Title: Biometric information acquisition apparatus and biometric authentication apparatus

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a biometric information acquisition apparatus and a biometric authentication apparatus. 
     2. Description of Related Art 
     Fingerprint authentication, vein authentication and iris authentication are known among biometric authentication technologies. Particularly, vein authentication attracts attention as promising technology because forgery of authentication information is more difficult compared to fingerprint authentication and authentication can be executed relatively easily. 
     Techniques related to vein authentication are disclosed in Japanese Unexamined Patent Application Publication No. 2001-119008 (hereinafter referred to as the patent document 1) and Japanese Unexamined Patent Application Publication No. 2006-218019 (hereinafter referred to as the patent document 2) The patent document 1 discloses the imaging apparatus that is used for biometric authentication. In this imaging apparatus, the light source ( 100 ), the support ( 300 ) and the image authentication portion ( 200 ) are stacked on top of each other, thereby reducing the size of the imaging apparatus. The patent document 2 discloses the apparatus that acquires a blood vessel image using the line sensor. 
     Further, Japanese Unexamined Patent Application Publication No. 2001-344213 (hereinafter referred to as the patent document 3) discloses the biometric authentication apparatus that includes the imager, the host device, the authentication portion and the memory portion. The imager, the host device, the authentication portion and the memory portion are connected through the external bus. Image data captured by the imager is output to the external bus. At the time of performing authentication, biometric information prestored in the memory portion is output to the external bus. 
     Furthermore, the biometric information acquisition apparatus disclosed in Japanese Unexamined Patent Application Publication No. 2007-257307 (hereinafter referred to as the patent document 4) moves the sliding member including the line sensor by the driver to sequentially capture images of a part of a subject. 
     In vein authentication, it is necessary to apply near-infrared light over a given range of a subject for the purpose of acquiring high-quality vein images. In order to apply near-infrared light all over a given range of a subject, it is necessary to keep a light source away from the subject or prepare a large number of light sources. This causes enlargement of a biometric information acquisition apparatus that acquires vein images, which increases a proportion to a main equipment body. 
     SUMMARY OF THE INVENTION 
     The present invention has been accomplished to address the above concern, and an object of the present invention is thus to further reduce the size of a biometric information acquisition apparatus while ensuring application of light over a given range of a subject. 
     According to an embodiment of the present invention, there is provided a biometric information acquisition apparatus that includes a light illuminator that illuminates a subject with light at least over a range corresponding to a pixel arrangement region where a plurality of pixels to receive light from the subject are arranged, and an imager placed on the same plane as the light illuminator and including the pixel arrangement region. 
     In this biometric information acquisition apparatus, one or more pixel arrays each including the plurality of pixels may be formed in the pixel arrangement region. 
     Further, the light illuminator may include a light guide extending along a pixel arrangement direction in the pixel array. 
     The light illuminator may include an organic light emitting layer extending along a pixel arrangement direction in the pixel array. 
     The light illuminator may include a plurality of light emitting devices arranged at substantially regular intervals. 
     The light illuminator may uniformize light within a range corresponding to the pixel array and output uniform light. 
     The light guide described above may have a light output surface extending along a pixel arrangement direction in the pixel array. 
     Further, the light guide and the imager may be sequentially arranged in a direction intersecting with the pixel arrangement direction in the pixel array. 
     The above biometric information acquisition apparatus may further include a substrate where at least the light guide and the imager are mounted. 
     The above biometric information acquisition apparatus may further include a capacitance sensor including one or more electrode arrays each having a plurality of electrodes arranged along the pixel arrangement direction in the pixel array, and the capacitance sensor and the imager may be sequentially arranged in a direction intersecting with the pixel arrangement direction in the pixel array. 
     Alternatively, in the biometric information acquisition apparatus described above, the light illuminator may include a first light source and a second light source to emit light with different wavelengths, a first light guide to guide light emitted from the first light source and output the light to the subject, and a second light guide to guide light emitted from the second light source and output the light to the subject, and the first light guide, the second light guide and the imager may be arranged in a direction intersecting with a pixel arrangement direction in the pixel array. 
     In the above biometric information acquisition apparatus, the first light source may emit near-infrared light, and the second light source may emit visible light. 
     The biometric information acquisition apparatus described above may further include a plurality of lenses arranged corresponding to the plurality of pixels. 
     Further, the biometric information acquisition apparatus described above may further include a light shielding layer placed between the plurality of lenses and the imager, and the light shielding layer may have a plurality of optical openings corresponding to optical axes of the lenses. 
     According to another embodiment of the present invention, there is provided a biometric authentication apparatus that includes a light illuminator to illuminate a subject with light at least over a range corresponding to a pixel arrangement region where a plurality of pixels to receive light from the subject are arranged, and a semiconductor device placed on the same plane as the light illuminator and including the pixel arrangement region where the plurality of pixels are arranged, the semiconductor device including an imaging region to capture an image of the subject at least in the range corresponding to the pixel arrangement region, an authentication region to perform authentication by comparing biometric information acquired by imaging in the imaging region with prestored biometric information, and a first transfer region to transfer the biometric information acquired by imaging in the imaging region from the imaging region to the authentication region. 
     In this biometric authentication apparatus, the semiconductor device may further include an interface region to supply an authentication result in the authentication region to an external host device, and a second transfer region to transfer a signal indicating an authentication result in the authentication region to the interface region. 
     In the above biometric authentication apparatus, the semiconductor device may further include an encryption region to encrypt an authentication result in the authentication region. 
     In the above biometric authentication apparatus, the semiconductor device may further include a control region to control luminance of light illuminated on the subject. 
     According to the embodiments of the present invention described above, it is possible to further reduce the size of a biometric information acquisition apparatus while ensuring application of light over a given range of a subject. 
     The above and other objects, features and advantages of the present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not to be considered as limiting the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         FIG. 1  is a schematic perspective view showing a biometric information acquisition apparatus according to a first embodiment of the present invention; 
         FIG. 2A  is a schematic diagram showing the cross-sectional structure of the biometric information acquisition apparatus according to the first embodiment of the present invention; 
         FIG. 2B  is a schematic diagram showing the cross-sectional structure of the biometric information acquisition apparatus according to the first embodiment of the present invention; 
         FIG. 2C  is a schematic diagram showing the cross-sectional structure of the biometric information acquisition apparatus according to the first embodiment of the present invention; 
         FIG. 3A  is an explanatory view to describe the function of a light guide according to the first embodiment of the present invention; 
         FIG. 3B  is an explanatory view to describe the function of the light guide according to the first embodiment of the present invention; 
         FIG. 4  is an explanatory view showing the topside structure of the biometric information acquisition apparatus according to the first embodiment of the present invention; 
         FIG. 5  is an explanatory view to describe the function of the biometric information acquisition apparatus according to the first embodiment of the present invention; 
         FIG. 6  is a block diagram showing the schematic configuration of a biometric authentication apparatus according to the first embodiment of the present invention; 
         FIG. 7  is a flowchart to describe the operation of the biometric authentication apparatus according to the first embodiment of the present invention; 
         FIG. 8A  is an explanatory view to describe the movement of a finger; 
         FIG. 8B  is an explanatory view to describe the movement of a finger; 
         FIG. 9A  is an explanatory view to describe the positional relationship of acquired vein images; 
         FIG. 9B  is an explanatory view to describe the positional relationship of acquired vein images; 
         FIG. 10  is a schematic perspective view showing a biometric information acquisition apparatus according to a second embodiment of the present invention; 
         FIG. 11  is a timing chart to describe the operation of the biometric information acquisition apparatus according to the second embodiment of the present invention; 
         FIG. 12  is a schematic perspective view showing a biometric information acquisition apparatus according to a third embodiment of the present invention; 
         FIG. 13  is a schematic perspective view showing a biometric information acquisition apparatus according to a fourth embodiment of the present invention; 
         FIG. 14  is a schematic perspective view showing a biometric information acquisition apparatus according to a fifth embodiment of the present invention; 
         FIG. 15  is a schematic diagram showing the cross-sectional structure of an area light source according to the fifth embodiment of the present invention; 
         FIG. 16  is a block diagram showing the configuration of a biometric authentication system according to a sixth embodiment of the present invention; 
         FIG. 17  is a schematic diagram showing a biometrics IC according to the sixth embodiment of the present invention; 
         FIG. 18  is a schematic diagram showing another biometrics IC according to the sixth embodiment of the present invention; 
         FIG. 19  is a schematic diagram showing a connection between the biometrics IC and a host device; 
         FIG. 20  is a schematic diagram showing a biometric authentication apparatus according to a seventh embodiment of the present invention; 
         FIG. 21  is a block diagram showing the configuration of a biometric authentication system according to an eighth embodiment of the present invention; 
         FIG. 22  is a block diagram showing the configuration of a biometric authentication apparatus according to a ninth embodiment of the present invention; 
         FIG. 23  is a front view schematically showing a biometric information acquisition portion according to the ninth embodiment of the present invention; 
         FIG. 24  is a front view schematically showing a placing table; 
         FIG. 25  is a rear view schematically showing the placing table; 
         FIG. 26  is a bottom view schematically showing the placing table; 
         FIG. 27A  is a front view schematically showing a casing member that contains a light source, an imager and so on; 
         FIG. 27B  is a partially enlarged view schematically showing a line sensor; 
         FIG. 28  is a front view schematically showing another placing table; 
         FIG. 29  is a front view schematically showing a biometric information acquisition portion according to a tenth embodiment of the present invention; 
         FIG. 30  is a rear view schematically showing another placing table; 
         FIG. 31A  is a front view schematically showing a pattern; 
         FIG. 31B  is a front view schematically showing a pattern; 
         FIG. 31C  is a front view schematically showing a pattern; 
         FIG. 31D  is a front view schematically showing a pattern; 
         FIG. 32  is a view showing a signal indicating read positional information and a line signal obtained by capturing an image of a finger; 
         FIG. 33  is a bock diagram schematically showing the configuration of a biometric authentication apparatus according to the tenth embodiment of the present invention; 
         FIG. 34  is a bock diagram schematically showing the configuration of a biometric authentication apparatus according to an eleventh embodiment of the present invention; 
         FIG. 35  is a front view schematically showing a pattern having a light amount adjusting pattern; and 
         FIG. 36  is a view showing a signal obtained by performing imaging while controlling the light amount of a light source. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Exemplary embodiments of the present invention are described hereinafter with reference to the drawings. Each embodiment is simplified for convenience of description. The drawings are given in simplified form by way of illustration only, and thus are not to be considered as limiting the present invention. The drawings are given merely for the purpose of explanation of technological matters, and they do not show the accurate scale or the like of each element shown therein. The same elements are denoted by the same reference symbols, and the redundant explanation is omitted. The terms indicating the directions, such as up, down, left and right, are used on condition that each drawing is viewed from the front. 
     First Embodiment 
     The configuration and the functions of a biometric information acquisition apparatus are described hereinafter with reference to  FIGS. 1 to 5 . 
       FIG. 1  is a schematic perspective view of a biometric information acquisition apparatus  60 . As shown in  FIG. 1 , the biometric information acquisition apparatus  60  includes a light source  21 , a light guide  22 , an image pickup device (imager)  31 , an optical functional layer  32 , a light source  41 , a light guide  42 , a capacitance sensor  10 , and a wiring board (packaging substrate)  50 . The light source  21 , the light guide  22 , the image pickup device  31 , the light source  41 , the light guide  42  and the capacitance sensor  10  which are supported by the wiring board  50  and placed on the same plane. The light guide  22 , the image pickup device  31 , the light guide  42  and the capacitance sensor  10  are arranged in this order from left to right. The biometric information acquisition apparatus  60  is used for vein authentication. 
     The light source  21  and the light guide  22  are referred to collectively as a light illumination unit  20 . Likewise, the light source  41  and the light guide  42  are referred to collectively as a light illumination unit  40 . Further, the image pickup device  31  and the optical functional layer  32  are referred to collectively as an image acquisition unit  30 . The light illumination unit is equivalent to a light illuminator. 
     The biometric information acquisition apparatus  60  acquires a plurality of vein images of a finger (subject)  96  placed above at different timings. Based on the vein images acquired by the biometric information acquisition apparatus  60 , an image for biometric authentication is created. 
     The biometric information acquisition apparatus  60  acquires a plurality of fingerprint images of the finger  96  placed above. Based on the fingerprint images acquired by the biometric information acquisition apparatus  60 , the moving direction of the finger  96  and the moving amount per unit time of the finger  96  are obtained. 
     A biometric authentication apparatus that incorporates the biometric information acquisition apparatus  60  combines the vein images to create an image for biometric authentication based on the moving direction of the finger  96  and the moving amount per unit time of the finger  96 . The relative positions of the acquired vein images are obtained from the moving direction of the finger  96  and the moving amount per unit time of the finger  96 . The acquisition of vein images and the acquisition of fingerprint images are performed at the same timing in the biometric information acquisition apparatus  60 . 
       FIGS. 2A to 2C  are schematic diagrams showing the partial cross-sectional structures of the biometric information acquisition apparatus  60 .  FIG. 2A  shows the schematic cross section along line  2 A- 2 A in  FIG. 1 .  FIG. 2B  shows the schematic cross section along line  2 B- 2 B in  FIG. 1 .  FIG. 2C  shows the schematic cross section along line  2 C- 2 C in  FIG. 1 . 
     As shown in  FIG. 2A , the capacitance sensor  10  includes a sensor substrate  15  and a protective film  16 . On the top face of the sensor substrate  15 , an electrode array composed of a plurality of electrodes EL 1  to EL 8  arranged in a row. The capacitance sensor  10  serves as a fingerprint detection unit that detects the movement of the fingerprint pattern of the finger  96  (a means of detecting the movement of the fingerprint pattern of the finger  96 ). 
     The capacitance sensor  10  detects the values of capacitances formed between the finger  96  placed above and the respective electrodes EL 1  to EL 8  using capacitance detectors connected between the respective electrodes EL 1  to EL 8 . A capacitance value detected by each capacitance detector corresponds to the distance between each electrode EL 1  to EL 8  and the skin of the finger  96 . A fingerprint is formed in the surface of the finger  96 . When the finger  96  is placed on the capacitance sensor  10 , the capacitance distribution, which is output from the capacitance detectors connected to the respective electrodes EL 1  to EL 8 , corresponds to the fingerprint pattern on the electrodes EL 1  to EL 8 . In this way, the capacitance sensor  10  acquires the fingerprint images of the finger  96  placed above. The arrangement of the electrodes is arbitrary. For example, the electrodes may be arranged in matrix. The fingerprint images (information) detected by the capacitance sensor  10  are used for obtaining the moving direction of the finger  96  and the moving amount per unit time of the finger  96 . 
     The protective film  16  shown in  FIG. 2A  is a thin film that protects the electrodes ELI to EL 8  from the outside world. The protective film  16  is deposited on the sensor substrate  15 . The material of the protective film  16  may be transparent resin, glass or the like, for example. 
     As shown in  FIG. 2B , the light illumination unit  20  includes the light source  21  and the light guide  22 . The structure of the above-described light illumination unit  40  is the same as the structure of the light illumination unit  20 . Thus, repeated description is omitted. 
     The light source  21  is a semiconductor optical element with a mold-packaged semiconductor chip such as a semiconductor light emitting diode (LED) or a semiconductor laser diode (LD). By applying a current between the electrodes, the light source  21  outputs light with a wavelength in the near-infrared region (which is a wavelength of 600 nm to 1000 nm, and it is 760 nm or 870 nm in this example). 
     The light guide  22  is substantially transparent to the output light from the light source  21 . The light guide  22  is a planar member having a top surface  23 , a bottom surface  24  and a side surface  25 . The light source  21  is placed opposite to the side surface  25  of the light guide  22 . The material of the light guide  22  is arbitrary. For example, the light guide  22  may be made of quartz, resin, glass or the like. 
     The bottom surface  24  of the light guide  22  has a plurality of grooves  26  extending in the direction perpendicular to the sheet. Because of the grooves  26 , a plurality of projections  27  and a plurality of reflective surfaces  28  and  29  are formed on the bottom surface  24  of the light guide  22 . 
     Referring to  FIGS. 3A and 3B , the functions of the light guide  22  are described hereinafter. As shown in  FIG. 3A , the output light from the light source  21  which has entered the light guide  22  through the side surface (light incident surface)  25  of the light guide  22  propagates to the left of the sheet within the light guide  22  and is then reflected by the reflective surface  29  and output through the top surface (light output surface)  23 . By arranging the reflective surfaces  29  appropriately, it is possible to obtain the output light intensity distribution as shown in  FIG. 3B , for example. Specifically, the distribution can be obtained in which the output light intensity at the center of the light guide  22  is higher than the output light intensity at the ends of the light guide  22 . 
     Referring back to  FIG. 2C , the image acquisition unit  30  includes the image pickup device  31  and the optical functional layer  32 . 
     The image pickup device  31  is a semiconductor imager (which is a so-called line sensor) that includes a pixel array composed of a plurality of pixels PX 1  to PX 8  arranged in a row. The pixels PX 1  to PX 8  may be photodiodes, for example. Each pixel PX 1  to PX 8  outputs a current having a value corresponding to the incident light intensity. An output current from each pixel PX 1  to PX 8  is converted into a voltage by an I/V converter and finally converted into a digital signal by an A/D converter. 
     The optical functional layer  32  includes a light shielding layer  33  and a lens substrate  34 . The light shielding layer  33  is placed on the image pickup device  31 . The lens substrate  34  is placed on the light shielding layer  33 . 
     The light shielding layer  33  has a plurality of light shielding portions  35  respectively corresponding to the pixels PX 1  to PX 8 . The lens substrate  34  has a plurality of lenses L 1  to L 8  respectively corresponding to the pixels PX 1  to PX 8 . The lenses L 1  to L 8  are convex microlenses with a lens diameter of about several to several hundreds of micrometers. The light shielding portions  35  absorb incident light. The light shielding portions  35  are made of black resin, for example. Each light shielding mechanism  35  has an opening OP corresponding to the optical axis AX of each lens L 1  to L 8 . 
     The light that is incident on the image acquisition unit  30  propagates as follows. The light input to the respective lenses L 1  to L 8  is converged by the lens action at each lens, passes through the substrate part of the lens substrate  34 , then passes through the opening OP of the light shielding mechanism  35  of the light shielding layer  33  and is finally input to each pixel PX 1  to PX 8  of the image pickup device  31 . 
     By setting the lens diameter of the respective lenses L 1  to L 8  appropriately, it is possible to suitably acquire the vein images of the finger  96 . 
     Further, the light shielding portions  35  of the light shielding layer  33  effectively separates optical channels between the lenses and the pixels, thereby effectively avoiding crosstalk between the optical channels. It is thereby possible to improve the quality of images finally obtained by the image pickup device  31 . 
       FIG. 4  is an explanatory view showing the topside structure of the biometric information acquisition apparatus  60 . In  FIG. 4 , an x-axis and a y-axis orthogonal to each other are set. 
     As shown in  FIG. 4 , the light guide  22  is a longitudinal member along the y-axis. The light guide  42  is the same as the light guide  22 . 
     The plurality of pixels PX 1  to PX 8  are arranged along the y-axis. Likewise, the plurality of lenses L 1  to L 8  are arranged along the y-axis. Likewise, the plurality of electrodes EL 1  to EL 8  are arranged along the y-axis. Thus, the arrangement direction of the pixels, the arrangement direction of the lenses and the arrangement direction of the electrodes are substantially parallel to one another. Further, the longitudinal direction of each light guide is substantially parallel to the arrangement direction of the pixels, the arrangement direction of the lenses and the arrangement direction of the electrodes. The light guide  22 , the image acquisition unit  30  (image pickup device  31 ), the light guide  42  and the capacitance sensor  10  are arranged in this order along the x-axis. 
     Referring then to  FIG. 5 , the functions of the biometric information acquisition apparatus  60  are additionally described below.  FIG. 5  is a schematic diagram showing the cross-sectional structure along line x 5 -x 5  in  FIG. 4 . 
     As shown in  FIG. 5 , the output light from the light source  21  is applied to the finger  96  through the light guide  22 . The light having passed through the finger  96  is input to the image acquisition unit  30 . On the other hand, the output light from the light source  41  is applied to the finger  96  through the light guide  42 . The output light from the light source  41  is partially absorbed by a vein  102  of the finger  96 . The output light from the light source  21  is absorbed by the vein  102  of the finger  96 . The image pickup device  31  acquires vein images by the plurality of pixels PX 1  to PX 8 . 
     As schematically shown in  FIG. 5 , the capacitance sensor  10  detects the value of a parasitic capacitance Cx formed between the electrode EL 4  of the sensor substrate  15  and the skin of the finger  96 . The skin of the finger  96  has a plurality of grooves  101  that form a fingerprint pattern. The value of the parasitic capacitance Cx corresponds to the distance between the top surface of the electrode and the skin of the finger  96 . The capacitance sensor  10  acquires fingerprint images of the finger  96  in the range corresponding to the placement range of the electrodes EL 1  to EL 8 . 
     The structure and the operation of a biometric authentication apparatus that incorporates the biometric information acquisition apparatus  60  are described hereinafter with reference to  FIGS. 6 to 9B . 
     As shown in  FIG. 6 , a biometric authentication apparatus  80  includes a processing unit  81 , an authentication execution unit  82 , an image formation unit  83 , a storage unit  84 , a light emitting unit  85 , a vein image acquisition unit  86  and a fingerprint detection unit  87 . The light emitting unit  85  is equivalent to the light illumination units  20  and  40 . The vein image acquisition unit  86  is equivalent to the image acquisition unit  30 . The fingerprint detection unit  87  is equivalent to the capacitance sensor  10 . The biometric authentication apparatus  80  is configured by a general computer having the biometric information acquisition apparatus as an interface. The configuration of the biometric authentication apparatus  80  is not limited to the one shown in  FIG. 6 . 
     The biometric authentication apparatus  80  operates as shown in  FIG. 7 . It is assumed that the biometric authentication apparatus  80  is incorporated into a cellular phone. 
     First, the cellular phone that incorporates the biometric authentication apparatus  80  is in a non-operating state. 
     Next, the biometric authentication function of the cellular phone is activated (S 1 ). A specific method of activating the biometric authentication function is arbitrary. For example, the biometric authentication function may be activated when a user presses a certain button of the cellular phone. 
     Following the activation of the biometric authentication function, light is applied to the finger  96  from the light emitting unit  85  (S 2 ). Specifically, the light illumination units  20  and  40  of the biometric information acquisition apparatus  60  illuminate the finger  96  with light. In the step S 2 , the finger  96  moves toward the front along the arrow of  FIG. 1 . 
     Then, the vein image acquisition unit  86  acquires a plurality of vein images at very short time intervals, and the fingerprint detection unit  87  acquires a plurality of fingerprint images at very short time intervals as well (S 3 ). Specifically, the biometric information acquisition apparatus  60  acquires a plurality of vein images of the finger  96  placed on the image acquisition unit  30  at very short time intervals. Likewise, the biometric information acquisition apparatus  60  acquires a plurality of fingerprint images of the finger  96  placed on the capacitance sensor  10  at very short time intervals. In this example, the biometric information acquisition apparatus  60  acquires the vein images and the fingerprint images at the same timing. 
     After that, the image formation unit  83  forms a vein image for authentication (S 4 ). Because a line sensor is used in this embodiment, only the vein image in the range corresponding to one pixel array is obtained. Thus, in order to achieve highly accurate vein authentication, the image pickup device  31  acquires a plurality of vein images during the movement of the finger  96 , and the image formation unit  83  forms one vein image from the plurality of vein images. 
     The image formation unit  83  obtains the moving direction of the finger  96  and the moving amount per unit time of the finger  96  from the plurality of fingerprint images acquired by the fingerprint detection unit  87  and forms a vein image for authentication from the plurality of vein images acquired by the vein image acquisition unit  86 . 
     The operation of the image formation unit  83  is described hereinafter with reference to  FIGS. 8A ,  8 B,  9 A and  9 B. 
     In some cases, the finger  96  moves horizontally across the biometric information acquisition apparatus  60  as schematically shown by the arrow in  FIG. 8A . In other cases, the finger  96  moves diagonally across the biometric information acquisition apparatus  60  as schematically shown by the arrow in  FIG. 8B . 
     In the case of  FIG. 8A , the image pickup device  31  acquires vein images in the range of a region R 1 , a region R 2  and a region R 3  sequentially as schematically shown by the arrow in  FIG. 9A . In the case of  FIG. 8B , the image pickup device  31  acquires vein images in the range of a region R 4 , a region R 5  and a region R 6  sequentially as schematically shown by the arrow in  FIG. 9B . 
     In the case of  FIG. 8A , the image formation unit  83  horizontally combines the plurality of images acquired by the image pickup device  31  to form one vein authentication image. In the case of  FIG. 8B , the image formation unit  83  diagonally combines the plurality of images acquired by the image pickup device  31  to form one vein authentication image. 
     When the image formation unit  83  forms a vein image for authentication from a plurality of vein images acquired by the vein image acquisition unit  86 , the image formation unit  83  identifies the relative positions of the respective vein images acquired by the vein image acquisition unit  86  based on the plurality of fingerprint images acquired by the fingerprint detection unit  87 . 
     A fingerprint pattern of the finger  96  has a certain regularity. Therefore, the image formation unit  83  can determine the moving direction of the finger  96  and determine the moving amount per unit time of the finger  96  by identifying the transition of the capacitance distributions sequentially output from the fingerprint detection unit  87 . 
     Specifically, the image formation unit  83  compares the sequentially acquired capacitance distributions on the same principle as an optical mouse and identifies the same pattern of movement contained in the capacitance distributions. The moving amount per unit time and the moving direction of the finger  96  are thereby determined. The unit time corresponds to a frame interval (acquisition interval) of the capacitance distributions acquired by the fingerprint detection unit  87 . 
     Alternatively, the image formation unit  83  may determine the moving direction of the finger  96  and determine the moving amount per unit time of the finger  96  by applying a given algorithm to the capacitance distributions sequentially output from the fingerprint detection unit  87 . 
     Refer now back to  FIG. 7 . 
     The authentication execution unit  82  then executes authentication (S 5 ). Specifically, the authentication execution unit  82  executes biometric authentication based on the authentication image output from the image formation unit  83  and the vein image prestored in the storage unit  84 . For example, the authentication execution unit  82  determines that the authentication is succeeded if the number of parts where the way the veins are branched matches between the images is equal to or more than N (N is a natural number of 2 or above), and it determines that the authentication is failed if the number of parts where the way the veins are branched matches between the images is less than N (S 6 ). Because a specific method of authentication depends on an image processing method, it is not limited to the above example. 
     If the authentication is succeeded, the function of the cellular phone that incorporates the biometric authentication apparatus  80  is activated (S 7 ). Then, the cellular phone returns to a normal operating state. If, on the other hand, the authentication is failed, the cellular phone that incorporates the biometric authentication apparatus  80  remains in the non-operating state. 
     As described above, by incorporating the biometric authentication apparatus  80  into the cellular phone, the security of the cellular phone increases significantly. 
     In this embodiment, the biometric information acquisition apparatus  60  is miniaturized with use of the line sensor. Further, the image pickup device  31  and the light guide  22  are placed on the same plane. This sufficiently reduces the thickness of the biometric information acquisition apparatus  60 . Because light from each light source is output through the top surface of each light guide (the surface facing the finger  96 ), the light is sufficiently applied over a desired range of the finger  96  without any inhibition. On the top surface of the image pickup device  31  (the surface facing the finger  96 ), a plurality of pixels are placed. Each light guide guides the input light to a desired light output surface through a plurality of reflective surfaces arranged appropriately. 
     Further, the components necessary for acquiring biometric information (the light source  21 , the light guide  22 , the image pickup device  31 , the light source  41 , the light guide  42  and the capacitance sensor  10 ) are mounted on the common wiring board  50 , thereby implementing the modularity of the biometric information acquisition apparatus. 
     Furthermore, the optical functional layer  32  is placed on the image pickup device  31 , thereby enabling the image pickup device  31  to acquire higher quality vein images. Adjustment of the focal length of the lens according to the depth of the vein from the skin of the finger  96  enables the image pickup device  31  to acquire clearer vein images. Placement of the light shielding layer having a plurality of openings corresponding to the optical axes of the lenses on the image pickup device  31  allows reduction of crosstalk between optical channels, thereby enabling the image pickup device  31  to acquire clearer vein images. 
     A procedure to manufacture the biometric information acquisition apparatus  60  is arbitrary, as long as the light source  21 , the light guide  22 , the image acquisition unit  30 , the light source  41 , the light guide  42  and the capacitance sensor  10 , which are prepared beforehand, are mounted on the wiring board  50 . A procedure to manufacture the image acquisition unit  30  is also arbitrary. The optical functional layer  32  is fabricated using normal semiconductor process technology (a thin film formation step, an etching step, a heating step etc.). The optical functional layer  32  fabricated in this manner is fixed on top of the image pickup device  31 , thereby creating the image acquisition unit  30 . 
     Second Embodiment 
     The configuration and the functions of a biometric information acquisition apparatus that is used for vein authentication are described hereinafter with reference to  FIGS. 10 and 11 . 
     A biometric information acquisition apparatus  61  according to a second embodiment of the present invention detects the movement of the fingerprint pattern of the finger  96  using an optical method. The biometric authentication apparatus  80  obtains the moving amount per unit time of the finger  96  and the moving direction of the finger  96  based on the detection result of the biometric information acquisition apparatus  61 . In this case also, the same advantages as the first embodiment are obtained. Therefore, a means of detecting the movement of the fingerprint pattern of the finger  96  (the fingerprint detection unit) is not limited to the capacitance sensor, and it may be implemented using a line sensor for vein image acquisition. 
     As shown in  FIG. 10 , the biometric information acquisition apparatus  61  includes a light illumination unit  70 . The light illumination unit  70  illuminates the finger  96  with light in the visible region. Pattern information (fingerprint information) reflecting the fingerprint image of the finger  96  can be thereby acquired by the image pickup device  31 . Thus, the image pickup device  31  of this embodiment acquires pattern information reflecting a fingerprint image (which is referred to hereinafter simply as pattern information) in addition to vein images. Then, based on a plurality of pieces of pattern information acquired by the image pickup device  31 , a vein image for authentication is formed from a plurality of vein images acquired by the image pickup device  31 . The pattern information acquired by the image pickup device  31  is used to obtain the moving amount per unit time of the finger  96  and the moving direction of the finger  96 . 
     The light illumination unit  70  includes a light source  71  and a light guide  72 . 
     The light source  71  is a semiconductor optical device with a mold-packaged semiconductor chip such as a semiconductor light emitting diode (LED) or a semiconductor laser diode (LD). By applying a current between the electrodes, the light source  71  outputs light with a wavelength in the visible region (which is a wavelength of 360 nm to 830 nm, and it is 530 nm in this example). 
     The light guide  72  is a light guiding member that is substantially transparent to the output light from the light source  71 . The light guide  72  has the same structure as the light guides  22  and  42 . The light guide  72  guides the light from the light source  71  input through the side surface (light incident surface) to the top surface (light output surface) through a plurality of reflective surfaces formed on the bottom surface. Depending on a difference in the wavelength of light to be guided, the arrangement interval of the reflective surfaces formed on the light guide  72  may be different from that of the light guides  22  and  42 . 
     The biometric information acquisition apparatus  61  operates as shown in  FIG. 11 . 
     During t 0  and t 1 , the biometric information acquisition apparatus  61  is in vein image acquisition mode. In this period, near-infrared light is output from the light source  21  and the light source  41 . The light output from each light source is applied to the finger  96  through each light guide. Then, the vein image in the range corresponding to the placement range of the pixels PX 1  to PX 8  is acquired by the image pickup device  31 . 
     During t 1  and t 2 , the biometric information acquisition apparatus  61  is in fingerprint information acquisition mode. In this period, visible light is output from the light source  71 . The light output from the light source  71  is applied to the finger  96  through the light guide  72 . Then, the pattern information (fingerprint information) reflecting the fingerprint image in the range corresponding to the placement range of the pixels PX 1  to PX 8  is acquired by the image pickup device  31 . 
     The operation during t 2  and t 3  is the same as the operation during t 0  and t 1 . The operation during t 3  and t 4  is the same as the operation during t 1  and t 2 . Thus, repeated explanation is omitted. 
     The biometric information acquisition apparatus  61  repeats the vein image acquisition mode and the fingerprint information acquisition mode at very short time intervals. 
     When the image formation unit  83  forms a vein image for authentication from a plurality of vein images acquired by the image pickup device  31 , it identifies the relative positions of the respective vein images acquired by the image pickup device  31  based on the plurality of pieces of pattern information acquired by the image pickup device  31 . The operation of the image formation unit  83  is the same as that described in the first embodiment. 
     By obtaining the moving amount per unit time of the finger  96  and the moving direction of the finger  96  using the optical method as described above and then identifying the relative positions of the plurality of vein images based thereon, it is possible to generate one authentication image from a plurality of vein images regardless of the movement of the finger  96 . 
     In this embodiment, the fingerprint detection unit  87  is composed of the light illumination unit  70  and the image acquisition unit  30 . Further, when the image formation unit  83  forms a vein image for authentication from a plurality of vein images acquired by the image pickup device  31 , it identifies the relative positions of the respective vein images acquired by the image pickup device  31  based on the plurality of pieces of pattern information reflecting the vein images acquired by the image pickup device  31 . 
     Although the focal length of the lenses L 1  to L 8  is set according to vein images to be acquired, the pattern reflecting fingerprint image may be also acquired by the pixels PX 1  to PX 8 . 
     Third Embodiment 
     A biometric information acquisition apparatus according to a third embodiment of the present invention is described hereinafter with reference to  FIG. 12 . 
     In this embodiment, a plurality of light sources  21  are arranged along the pixel arrangement direction of the image pickup device  31 , without using the light guide  22 . Likewise, a plurality of light sources  41  are arranged along the pixel arrangement direction of the image pickup device  31 , without using the light guide  42 . In this case also, the same advantages as those described in the first embodiment are obtained. Thus, it is possible to illuminate a subject with light over a desired range without increasing the size of the biometric information acquisition apparatus  61 . 
     The light sources  21  and  41  emit near-infrared light. Light sources  21   a  to  21   c  are arranged at substantially equal intervals. Likewise, light sources  41   a  to  41   c  are arranged at substantially equal intervals. By arranging the plurality of light sources  21  and  41  in this manner, it is possible to easily generate uniform light over the range corresponding to the pixel array of the image pickup device  31 . The light sources  21   a  to  21   c  constitute a light illuminator. The light sources  41   a  to  41   c  also constitute a light illuminator. 
     Fourth Embodiment 
     A biometric information acquisition apparatus according to a fourth embodiment of the present invention is described hereinafter with reference to  FIG. 13 . 
     In this embodiment, the light sources  71  that output visible light are placed instead of the light sources  21  of the third embodiment. In this case also, the same advantages as those described in the second embodiment are obtained. 
     Light sources  71   a  to  71   c  are arranged at substantially equal intervals. By arranging the plurality of light sources  71  in this manner, it is possible to easily generate uniform light over the range corresponding to the pixel array of the image pickup device  31 . The light sources  71   a  to  71   c  constitute a light illuminator. 
     Fifth Embodiment 
     A biometric information acquisition apparatus according to a fifth embodiment of the present invention is described hereinafter with reference to  FIGS. 14 and 15 . 
     In this embodiment, an area light source  90  using electroluminescence is employed as a light illuminator. In this case also, the same advantages as those described in the first embodiment are obtained. In this example, two area light sources  90   a  and  90   b  are arranged with the image pickup device  31  placed therebetween. 
     The area light source  90  is a longitudinal member along the pixel arrangement direction of the image pickup device  31 . The area light source  90  emits light by energization. The area light source  90  emits light within the range corresponding to the pixel array of the image pickup device  31 . Specifically, the area light source  90  outputs light with a uniform intensity over the range corresponding to the pixel array of the image pickup device  31 . 
     If the output light of the area light source  90  does not contain near-infrared light, a wavelength conversion filter is placed on the area light source  90 . With utilization of the wavelength conversion filter, the area light source  90   a  may be used as a near-infrared light source, and the area light source  90   b  may be used as a visible light source. In this case, the same advantages as the second embodiment are obtained. 
     The schematic cross-sectional structure of the area light source  90  is described hereinafter with reference to  FIG. 15 . As shown in  FIG. 15 , the area light source  90  includes a transparent substrate  91 , an electrode layer  92 , an organic EL layer  93 , an electrode layer  94 , and a transparent substrate  95 . 
     The transparent substrates  91  and  95  are transparent planar members such as glass. The electrode layers  92  and  94  are electrodes that are transparent to the output light from the organic EL layer  93 . The electrode layers  92  and  94  may be patterned. The organic EL layer (organic light emitting layer)  93  is a layer in which an electron transport layer, a light emitting layer and a positive hole transport layer are sequentially placed on top of one another. 
     By applying a power between the pair of electrode layers  92  and  94 , the energy state of organic molecules forming the light emitting layer makes a transition, so that light with a given wavelength is generated from the light emitting layer. The light generated by the light emitting layer is output to the front through the electrode layer  94  and the transparent substrate  95 . The electrode layer  92  may have characteristics that reflect the light generated by the light emitting layer. Further, a reflective layer may be placed between the light emitting layer  93  and the transparent substrate  91 . The thickness of each layer shown in  FIG. 15  does not indicate an actual thickness. 
     Sixth Embodiment 
     A sixth embodiment of the present invention is described hereinafter with reference to  FIGS. 16 to 19 . 
     The biometric authentication system disclosed in the patent document 3 is susceptible to hacking that acquires biometric information or analyzes an authentication algorithm by analyzing the data of the external bus during authentication. 
     A banking terminal such as an automated teller machine (ATM) involves a small number of end users, and a provider of a service can thus manage the machine safely, so that it has less risk of such hacking. On the other hand, a cellular phone, a personal computer (PC) and so on are used by a large number of end users, and it is thus difficult for a provider of a service to manage those machines so as to avoid hacking, and therefore it is susceptible to hacking. In such a case, it is extremely important to prevent hacking from taking place. 
     In light of the foregoing, an object of this embodiment is to ensure higher security in addition to, or in place of, the object described in the above embodiments. 
     As shown in  FIG. 16 , a biometric authentication system  1  includes a biometric authentication apparatus  105  and a host device  150 . The biometric authentication apparatus  105  compares biometric information such as fingerprint patterns and finger vein patterns acquired from captured images with prestored biometric information to perform authentication. The host device  150  operates according to the authentication result that is output from the biometric authentication apparatus  105 . 
     The biometric authentication apparatus  105  includes a light source  100  and a semiconductor device (biometrics integrated circuit (IC))  120 . The semiconductor device  120  is equivalent to the image pickup device  31  described in the above embodiments. 
     As shown in  FIG. 16 , the biometrics IC  120  includes an imager  121 , an authentication portion  122 , a storage portion  123 , an interface portion  124 , input/output terminals  125 , an encryption portion  126 , and a decryption portion  127 . Corresponding to the functional portions shown in  FIG. 16 , the biometrics IC  120  includes an imaging region  121 , an authentication region  122 , a storage region  123 , an interface region  124 , an input/output terminal region  125 , an encryption region  126  and a decryption region  127  as shown in  FIG. 17 . The biometrics IC  120  is a monolithic IC. 
     As shown n  FIG. 16 , the biometrics IC  120  includes internal buses B 1  to B 5 . The internal bus B 1  connects the imager  121  and the authentication portion  122 . The internal bus B 2  connects the authentication portion  122  and the interface portion  124 . The internal bus B 3  connects the authentication portion  122  and the storage portion  123 . The internal bus B 4  connects the authentication portion  122  and the encryption portion  126 . The internal bus B 5  connects the authentication portion  122  and the decryption portion  127 . The internal buses function as signal transmission channels. The biometrics IC  120  has signal transmission regions corresponding to the internal buses. 
     This embodiment employs the above-described biometrics IC  120 . It is thereby possible to perform acquisition and authentication of biometric information on the same chip, thus preventing the biometric information from being output to the outside. It is practically difficult to pull the data flowing through the internal bus from the outside. By prohibiting access to the imaging data from the outside, it is possible to ensure high security. 
     The light source  100  corresponds to the light source  21  or the light source  71 . In this case also, the light guide  22 ,  42 ,  72  may be used as in the above-described embodiments. The light source  100  may be eliminated in the case of acquiring fingerprint patterns as biometric information. 
     The imager  121  includes one or more pixel arrays where a plurality of pixels are arranged. An optical functional portion (cf.  FIG. 2C ) is placed on top of the imager  121 . 
     The imager  121  captures an image of a finger moving above an image pickup surface. Alternatively, the imager  121  may capture an image of a finger fixed in position while being slid. Further, an area sensor in which a plurality of pixels are arranged in matrix may be used as the imager  121  as shown in  FIG. 18 . 
     In the case of performing biometric authentication based on fingerprint patterns, an electrostatic sensor that detects electrical charges according to the projections and recesses of a finger may be used as the imager  121 . Alternatively, a thermal sensor that detects a temperature difference in the projections and recesses of a finger may be used. In either case, fingerprint patterns can be acquired by each sensor. The imager  121  is preferably a complementary metal-oxide semiconductor (CMOS) image sensor in terms of semiconductor device manufacturing process. 
     A bandpass filter (optical functional portion) is placed on the imager  121 . The mechanism that the imager  121  captures vein images or fingerprint images is the same as that described in the above embodiments. The imager  121  outputs a signal generated by imaging to the authentication portion  122  through the internal bus B 1 . 
     The authentication portion  122  performs analog-to-digital conversion, binarization and so on of the signal supplied from the imager  121  and acquires biometric information. Further, the authentication portion  122  compares the biometric information with prestored biometric information to perform authentication. 
     When the authentication portion  122  receives an authentication command from the host device  150 , it controls the imager  121  and acquires biometric information. Then, the authentication portion  122  compares the acquired biometric information with the biometric information prestored in the storage portion  123  to perform authentication. The authentication command is transferred from the host device  150  to the authentication portion  122  through the interface portion  124  and the internal bus B 2 . The data captured by the imager  121  is transferred from the imager  121  to the authentication portion  122  through the internal bus B 1 . Authentication data to be used as master data is transferred from the storage portion  123  to the authentication portion  122  through the internal bus B 3 . 
     The storage portion  123  stores data captured by the imager  121  as master data. When the authentication portion  122  receives a registration command form the host apparatus  150 , it controls the imager  121  to acquire data and registers the data into the storage portion  123 . 
     The authentication portion  122  outputs a signal (information) indicating an authentication result to the host device  150  through the internal bus B 2  and the interface portion  124 . 
     The authentication portion  122  preferably encrypts the signal indicating an authentication result and then outputs it to the host device  150 . As described earlier, the biometrics IC  120  includes the encryption portion  126  that encrypts the signal indicating an authentication result. The encryption portion  126  and the authentication portion  122  are connected through the internal bus B 4 . The encryption portion  126  executes encryption of the signal that is supplied from the authentication portion  122  through the internal bus B 4 . The encryption portion  126  then outputs the encrypted signal to the authentication portion  122  through the internal bus B 4 . The encrypted signal is transferred from the authentication portion  122  to the host device  150  through the internal bus B 2  and the interface portion  124 . By encrypting the signal to be output to the outside, it is possible to further enhance security. Specifically, it is possible to achieve high tamper resistance (resistance to leakage of internal information to the outside) and high security against hacking. 
     As shown in  FIG. 19 , when the authentication portion  122  receives a request command for an internal status of the biometrics IC  120  from the host device  150 , it outputs a signal indicating the internal status of the biometrics IC  120 . At this time also, the authentication portion  122  preferably encrypts the internal information signal of the biometrics IC  120  using the encryption portion  126  and then outputs it to the host device  150 . 
     The storage portion  123  may be battery-backupable memory, rewritable nonvolatile memory or the like. The storage portion  123  stores registered biometric information, a program for implementing biometric information, a program for implementing image formation, an internal status of the biometrics IC  120  and so on. 
     The storage portion  123  may store biometric information of a plurality of persons. In this case, the biometric information of a person to be authenticated is selectable by a personal ID. Thus, a personal ID is assigned to each one of biometric information. After an authentication command and a signal indicating a personal ID are transferred from the host device  150  to the authentication portion  122  as shown in  FIG. 19 , the authentication portion  122  reads the biometric information corresponding to the received personal ID from the storage portion  123  and performs authentication using the biometric information. 
     The host device  150  preferably encrypts the authentication command and the signal indicating a personal ID and outputs them. The biometrics IC  120  includes the decryption portion  127  that decrypts the encrypted authentication command and the encrypted signal indicating a personal ID. The decryption portion  127  and the authentication portion  122  are connected through the internal bus B 5 . The encrypted signal that is output from the host device  150  is input to the authentication portion  122  through the interface portion  124  and the internal bus B 2 . The encrypted information is then supplied from the authentication portion  122  to the decryption portion  127  through the internal bus B 5  and decrypted by the decryption portion  127 . The decrypted information is transferred from the decryption portion  127  to the authentication portion  122  through the internal bus B 5 . This enhances security against information leakage. 
     In the case where the storage portion  123  stores a plurality of pieces of biometric information, the acquired biometric information may be sequentially compared with the plurality of pieces of stored biometric information. This eliminates the need for a user to select a person upon authentication in the host device  150 , thereby improving user-friendliness. 
     The host device  150  is a cellular phone, a PC or the like that incorporates the biometric authentication apparatus  105 , for example. The host device  150  and the biometrics IC  120  are connected to each other with their connectors coupled to each other. The host device  150  outputs a command indicating start or stop of authentication and a command indicating registration of biometric authentication, and, if needed, a command requesting the internal status of the biometrics IC  120  and a signal indicating a personal ID, to the biometrics IC  120 . The host device  150  receives the signal indicating an authentication result from the biometrics IC  120  and, when the authentication result matches the biometric information of the identical person, for example, turns on the main power. 
     The biometrics IC according to the embodiment includes the imager  121 , the authentication portion  122 , the storage portion  123 , the interface portion  124 , the input/output terminals  125 , the encryption portion  126  and the decryption portion  127 . Those functional portions are placed on the same surface (the top surface in  FIG. 16 ) of a monolithic chip. 
     Further, it is preferred to place the authentication portion  122 , the storage portion  123 , the interface portion  124 , the input/output terminals  125 , the encryption portion  126  and the decryption portion  127  within a region L with the same width as the imager  121 . This effectively suppresses an increase in chip size. 
     Seventh Embodiment  
     A seventh embodiment of the present invention is described hereinafter with reference to  FIG. 20 . 
     In a biometric authentication apparatus  106  according to the embodiment, the storage portion  123  is not placed on the biometrics IC  120 , which is different from the sixth embodiment. The biometric authentication apparatus  106  according to the embodiment encrypts the data to be stored in the storage portion  123  and stores it into an external apparatus (e.g. the host device). In this case, the authentication portion  122  transfers the biometric information acquired by controlling the imager  121  to the encryption portion  126 , and then transfers the information encrypted by the encryption portion  126  to the external storage portion  123 . At the time of executing authentication, the authentication portion  122  makes control so that the encrypted information stored in the external storage portion  123  is transferred to the decryption portion  127 . The authentication portion  122  executes authentication using the information decrypted by the decryption portion  127 . 
     In the case where a large number of users share the biometric authentication apparatus, the memory capacity of the storage portion  123  increases, which makes it difficult to place the storage portion  123  on the same chip as the imager  121 . In light of this, the storage portion  123  is placed externally, and encrypted data is transferred to the storage portion  123  in this embodiment. This allows a large number of users to share the biometric authentication apparatus. Further, this ensures high security just like the above-described embodiments. Specifically, it is possible to ensure high tamper resistance and high security against hacking. 
     It is preferred to place the imager  121 , the authentication portion  122 , the interface portion  124 , the input/output terminals  125 , the encryption portion  126  and the decryption portion  127  on the same surface (the top surface in  FIG. 20 ) of the chip. Further, it is preferred to arrange them with their top ends at a substantially equal height. 
     Eighth Embodiment 
     An eighth embodiment of the present invention is described hereinafter with reference to  FIG. 21 . 
     In a biometric authentication apparatus  107  according to the embodiment, the authentication portion  122  includes a control portion  122   a  that controls the illumination intensity of the light source  100  that illuminates a subject with light, which is different from the sixth embodiment. The control portion  122   a  controls the illumination intensity of the light source  100  in such a way that a signal (e.g. a signal voltage) output form the imager  121  has an optimum signal level. Specifically, the control portion  122   a  makes control so as to increase the illumination intensity of the light source  100  when an output level of the imager  121  is low. On the other hand, the control portion  122   a  makes control so as to decrease the illumination intensity of the light source  100  when an output level of the imager  121  is high. It is thereby possible to reduce variations of the brightness of acquired biometric information. 
     Ninth Embodiment  
     A ninth embodiment of the present invention is described hereinafter with reference to  FIGS. 22 to 28 . 
     The biometric information acquisition apparatus according to the patent document 4 needs to have a space for moving the sliding member including the line sensor below a subject. Likewise, the biometric information acquisition apparatus according to the patent document 4 needs to have a space for containing the driver or the like. 
     An object of this embodiment is to capture a desired image with a smaller space in addition to, or in place of, the object described in the above embodiments. 
     The biometric authentication system  1  includes a biometric information acquisition portion (biometric information acquisition apparatus)  2  and an authentication portion  3 . The biometric information acquisition portion  2  acquires images of a subject and acquires biometric information such as fingerprint patterns and finger vein patterns. The authentication portion  3  performs authentication by comparing the biometric information acquired by the biometric information acquisition portion  2  with the prestored biometric information. The biometric authentication system  1  is suitably incorporated into a cellular phone, a PC, an ATM or the like, which is electronic equipment. 
     The biometric information acquisition portion  2  includes a light source  100 , an imager  200 , a control portion  300 , an analog/digital (A/D) converter  400 , a processing portion  500 , a line memory  600  and a frame memory  700 . 
     The biometric information acquisition portion  2  includes a moving mechanism  800  as shown in  FIGS. 23 to 26 . The movement of a finger, which is a subject, is guided by the moving mechanism  800 . Specifically, the finger is guided by the moving mechanism  800  and moves in the direction intersecting with the pixel arrangement direction of a line sensor  201 . The line sensor  201  acquires images at different timings in the process of moving the finger. The images of a desired number of lines are thereby captured, and one authentication image can be created from those images. 
     The moving mechanism  800  includes a placing table  801  and a guiding member  802 . The placing table  801  is a planar member having transparency to light applied to the finger from the light source  100  (which is referred to hereinafter simply as inspection light) as shown in  FIG. 24 . The placing table  801  includes a placing portion  803  having a size that allows placement of at least a given part of the finger to be imaged. On the bottom surface of the placing portion  803 , two L-shaped members  804  are placed as shown in  FIGS. 25 and 26 . The L-shaped members  804  are placed in parallel with the direction of the finger, at both ends of the imaging region of the finger. The L-shaped member  804  has a horizontal piece  804   a  projecting outward. On the top surface of the placing portion  803 , a reverse U-shaped position regulating member  805  outlining the periphery of the finger is placed. The position to place the finger is regulated by the position regulating member  805 . A user&#39;s finger is thereby placed on a predetermined position, so that highly accurate images can be captured. 
     The guiding member  802  may have a horizontal piece that can fit into a groove portion  804   b  of the L-shaped member  804 . The guiding member  802  is an L-shaped member or a squared U-shaped member, for example. The length of the guiding member  802  is longer than the length of a given part of the finger to be placed on the placing portion  803 . The horizontal piece of the guiding member  802  fits into the groove portion  804   b  of the L-shaped member  804 . The guiding member  802  may be fixed to the housing of a cellular phone, for example. 
     A casing member  900  is placed between the two guiding members  802 . The both ends of the casing member  900  are fixed to the guiding members  802 . 
     The casing member  900  contains the plurality of light sources  100  and the imager  200 . In the casing member  900 , the arrangement direction of the plurality of light sources  100  is substantially parallel to the pixel arrangement direction of the line sensor  201 . The guiding member  802  regulates the moving direction of the placing table  801 . The longitudinal direction of the line sensor  201  coincides with the direction intersecting with the moving direction of the placing table  801 . 
     A user puts the finger on the substantially planar placing table  801  placed above the light sources  100  and the line sensor  201 . Next, the user manually slides the placing table  801  in the direction intersecting with the pixel arrangement direction of the line sensor  201  (downward on the sheet). A given part of the finger placed on the placing table  801  passes across the line sensor  201 . The imager  200  sequentially captures images within the sliding region of the placing table  801 . In this embodiment, the placing table  801  that operates manually is used. In this case, there is no need to make a space for moving the line sensor, which is an imaging component, and a space for containing a driver. Further, there is no need to have a driving source for moving the sliding member. This enables acquisition of images with a smaller space without a driving source compared to related art. This also allows use of a line sensor, which is less expensive than an area sensor. Further, this permits effective use of the space below the placing table  801  by placing an electronic component or the like. It is thereby possible to reduce the size of electronic equipment that incorporates the biometric authentication system  1 . 
     The light source  100  is a semiconductor light emitting diode (LED), a semiconductor laser diode (LD) or the like. The biometric information acquisition portion  2  applies inspection light to the finger placed on the placing portion  803  by driving the light source  100 . The inspection light is visible light (with a wavelength of about 360 to 800 nm) or near-infrared light (with a wavelength of about 0.7 to 2.5 μm). The inspection light may be applied to the finger directly from a LED or the like or indirectly using a light guide or the like. Further, the light source may be eliminated in the case of acquiring fingerprint patterns as biometric information. 
     Reflected light or transmitted light from the finger enters the imager  200  through the placing portion  803 . The imager  200  is a complex element in which an optical functional portion is placed on top of the line sensor  201 . The line sensor  201  includes a plurality of pixels arranged in a row as shown in  FIG. 27B . Alternatively, an area sensor that includes a plurality of pixels arranged in matrix may be used. 
     The reflected light or transmitted light from the finger which is input from above passes through a bandpass filter (optical functional portion) that shields external disturbance light. Then, the input light is focused on each pixel PX of the line sensor  201  by a microlens array (optical functional portion) The imager  200  then photoelectrically converts the input light in each pixel PX, reads a signal from each pixel PX and supplies it to the A/D converter  400 . 
     The light source  100  and the imager  200  are controlled by the control portion  300 . The control portion  300  directs the light source  100  and the imager  200  to start or stop operation, for example. For instance, the control portion  300  controls the imager  200  to output imaging data at a given read timing. The control portion  300  controls the biometric information acquisition portion  2  as a whole. 
     The A/D converter  400  converts the output signal from each pixel PX form analog to digital and supplies the result to the processing portion  500 . The processing portion  500  sequentially writes the supplied signals into the line memory  600 . The line memory  600  accumulates the supplied signals from the respective pixels PX. When signals for one pixel array (a line signal) are accumulated, the line memory  600  supplies the line signal to the frame memory  700  through the processing portion  500 . The frame memory  700  accumulates the supplied line signals. When a desired number of line signals (which forms a desired image) are accumulated, the frame memory  700  supplies the desired number of line signals to the processing portion  500 . The processing portion  500  performs binarization or the like on the desired number of supplied line signals. 
     The image data acquired by the biometric information acquisition portion  2  is supplied from the processing portion  500  to the authentication portion  3 . The authentication portion  3  compares the acquired biometric information with the prestored biometric information to perform authentication. 
     The biometric information acquisition portion  2  preferably includes a returning mechanism  1000  that returns the placing table  801  to its original position as shown in  FIG. 23 . For example, an elastic body  1001  such as a spring is placed in parallel to the longitudinal direction of the guiding member  802 . One end of the elastic body  1001  is coupled to a coupling piece  1002  placed on the bottom surface of the placing portion  803 . The other end of the elastic body  1001  is coupled to a coupling piece  1003  placed on the housing of a cellular phone or the like. By placing the returning mechanism  1000 , user-friendliness is improved. Specifically, the returning mechanism  1000  eliminates the need for a user to manually return the placing table  801  to the original position (the initial position of the placing table  801 ). Further, the returning mechanism  1000  allows the placing table  801  to return to its original position with high accuracy, thereby improving the quality of images to be captured next. 
     Further, it is preferred to place a nonslip member  1100  made of resin or the like on the top surface of the placing portion  803  as shown in  FIG. 28 . The nonslip member  1100  is located at the lower end of the position regulating member  805 . The nonslip member  1100  may be placed in any position as long as it does not affect imaging. Further, the nonslip member  1100  is not limited to resin or the like as long as it is a member that increases resistance with the finger. 
     Tenth Embodiment 
     A tenth embodiment of the present invention is described hereinafter with reference to  FIGS. 29 to 33 . 
     A biometric information acquisition portion  12  has a regular pattern  1200  above the line sensor  201  as shown in  FIGS. 29 and 30 . The pattern  1200  enables detection of the moving amount of the placing table  801  with respect to the line sensor  201 . 
     The line sensor  201  includes a pixel for capturing an image of a finger and a pixel for detecting a pattern. The pattern  1200  is placed above the pattern detection pixel. The movement of the pattern is detected by the pattern detection pixel. The pattern  1200  is formed substantially parallel to the moving direction of the finger. 
     The pattern  1200  has an address code  1200   a  illustrated in  FIGS. 31A  so as to add position information (address) to the image captured by the line sensor  201 . The pattern  1200  is formed in advance on the bottom surface of the placing portion  803 . With the pattern  1200 , it is possible to specify the position of the acquired image data. 
     The pattern  1200  moves as the placing portion  803  moves. The imager  200  captures the image of the address code  1200   a  at the same time as capturing the image of the finger, thereby acquiring position information. It is thereby possible to acquire the position information of image data in addition to the image data acquired at certain timing. The relative positions of the respective image data are thereby obtained. Based on the relative positions of the respective image data, one authentication image can be created from the plurality of image data. The line sensor repeats the image pickup operation at sufficiently short time intervals. 
     The imager  200  reads the position information obtained by the address code  1200   a  and the imaging data of the finger in association with each other. As shown in  FIG. 33 , a position information extraction portion  1300  extracts the position information obtained by the address code  1200   a.    
     The position information extraction portion  1300  supplies the imaging data of the address code  1200   a  to an address detection portion  1400 . The address detection portion  1400  detects an address based on the supplied data. The address detection portion  1400  supplies a signal indicating the address to the processing portion  500  through the control portion  300 . The output of the pattern detection pixel may be converted from analog to digital and then directly connected to the address detection portion  1400  without through the position information extraction portion  1300 . 
     On the other hand, the imaging data of the finger is accumulated in the line memory  600  through the processing portion  500 . The line memory  600  supplies the accumulated line signals obtained by capturing images of the finger to the processing portion  500 . 
     The processing portion  500  associates the supplied position information with the imaging data of the finger and supplies them to the frame memory  700 . With the movement of the placing table  801 , the position information and the imaging data of the finger supplied from the processing portion  500  are associated and sequentially supplied to the frame memory  700 . The frame memory  700  is configured to arrange the line signals obtained by capturing images of the finger based on the position information. The frame memory  700  arranges the line signals obtained by capturing images of the finger based on the supplied position information and thereby creates one desired composite image. In this manner, one desired composite image can be created with high accuracy from one row of image data output from the line sensor  201 . 
     In this embodiment, the imager  200  reads the signal obtained by capturing images of the address code  1200   a  in advance as shown in  FIG. 32 . However, the imager  200  may read the line signal obtained by capturing images of the finger in advance and then read the signal obtained by capturing the image of the address code  1200   a  after that. The reading of the signals is regulated by the control of a vertical scanning circuit and a horizontal scanning circuit of the imager  200 . 
     The pattern  1200  may have a triangular light reflecting portion  1200   b  and a light absorbing portion  1200   c  in a black region (which is a shaded area in the illustration) as shown in  FIG. 31B . If data obtained when the line sensor  201  captures an image of the light reflecting portion  1200   b  is binarized by the address detection portion  1400 , a signal pulse having a certain length is obtained. The address detection portion  1400  counts the number of pixels of the line sensor  201  corresponding to the length of the signal pulse and detects the address of the line signal obtained by capturing images of the finger. 
     Further, the pattern  1200  may have a light reflecting portion  1200   d  in which rectangular white spots each having substantially the same height as the length of one side of the pixel of the line sensor  201  are arranged on an N-line and a light absorbing portion  1200   e  in a black region (which is a shaded area in the illustration) different from the light reflecting portion as shown in  FIG. 31C . In this case, if a signal obtained when the line sensor  201  captures an image of the white spots is binarized by the address detection portion  1400 , a signal pulse corresponding to the arrangement of the white spots is obtained. The address detection portion  1400  detects the address of the line signal obtained by capturing images of the finger based on the position of the signal pulse. By arranging the white spots on the N-line as shown in  FIG. 31C , the shift amount between the white spots adjacent vertically is large, thereby facilitating detection of the address of the line signal obtained by capturing images of the finger. 
     Furthermore, the pattern  1200  may have a light reflecting portion  1200   f  in a region of white blocks each having substantially the same height as the length of one side of the pixel of the line sensor  201  and a light absorbing portion  1200   g  in a region of black blocks (which is a shaded area in the illustration) which are arranged in an alternate manner per line (in a checkered pattern) as shown in  FIG. 31D . In this case, the address detection portion  1400  counts the number of times when the light reflecting portion  1200   f  and the light absorbing portion  1200   g  are switched in turn, thereby detecting the address of the line signal obtained by capturing images of the finger. 
     The patterns  1200  of  FIGS. 31A to 31D  are shown by way of illustration, and any pattern may be used as long as it can detect the address. 
     Further, a detecting means of the moving amount of the placing table  801  with respect to the line sensor  201  is not limited to the above-described pattern. For example, the moving amount of the placing table  801  with respect to the line sensor  201  may be detected using a means of detecting the moving amount such as an encoder. Thus, the detecting means may have any structure as long as it can detect the moving amount of the placing table  801  with respect to the line sensor  201 . 
     Eleventh Embodiment 
     An eleventh embodiment of the present invention is described hereinafter with reference to  FIGS. 34 to 36 . 
     A biometric information acquisition portion  13  according to this embodiment controls the amount of output light from the light source  100 . 
     Specifically, the pattern  1200  has a light amount adjusting marker  1200   h  as shown in  FIG. 35 . The pattern  1200  is formed on the bottom surface of the placing portion  803 . The light amount adjusting marker  1200   h  is a gray vertically-oriented region, for example. The light amount adjusting marker  1200   h  is formed on the front of the address code and the light reflecting portion so as to adjust the initial light amount of the light source  100 . 
     As the placing portion  803  moves, the pattern  1200  having the light amount adjusting marker  1200   h  moves. Like the address code and the light reflecting portion described above, an image of the light amount adjusting marker  1200   h  is captured by the imager  200  and then extracted by the position information extraction portion  1300 . 
     The position information extraction portion  1300  supplies the signal obtained by capturing the image of the light amount adjusting marker  1200   h  to the address detection portion  1400  and a light amount adjusting marker detection portion  1500 . The light amount adjusting marker  1200   h  has a shape of a vertically-oriented block with an equal width. Thus, a continuous long signal pulse, which is different from the address code and the light reflecting portion described above, is supplied to the address detection portion  1400  and the light amount adjusting marker detection portion  1500 . The address detection portion  1400  thereby recognizes that the supplied signal is not a signal for address detection. The light amount adjusting marker detection portion  150  recognizes that the supplied signal is a signal for light amount adjustment. 
     The light amount adjusting marker  1200   h  is gray. Thus, the light amount adjusting marker detection portion  1500  may recognize that the supplied signal is a signal for light amount adjustment when a signal indicating a gray level is supplied continuously. 
     The light amount adjusting marker detection portion  1500  supplies the signal obtained by capturing the image of the light amount adjusting marker  1200   h  to the control portion  300 . The control portion  300  is configured to determine the light amount of the light source  100  in such a way that the signal level of the signal obtained by imaging becomes an optimum signal level based on a prescribed relational expression. The relational expression represents the relationship between the signal level of a signal obtained by imaging in advance and the light amount of the light source  100 . 
     When the signal obtained by capturing the image of the light amount adjusting marker  1200   h  is supplied, the control portion  300  determines the initial light amount of the light source  100  in such a way that the signal has an optimum signal level. The control portion  300  controls the light source  100  based on the determined initial light amount. In this state, the imager  200  captures images of the finger. Then, the imager  200  reads the imaging data obtained by capturing images of the finger and the information obtained by capturing images of the address code or the light reflecting portion. 
     The position information extraction portion  1300  extracts the information read as described above and supplies the extracted information to the address detection portion  1400  and the light amount adjusting marker detection portion  1500 . Because a signal different from the signal obtained by capturing the image of the light amount adjusting marker  1200   h  is supplied, the light amount adjusting marker detection portion  1500  recognizes that it is not a signal for light amount adjustment. The address detection portion  1400  recognizes that it is a signal for address detection. 
     The address detection portion  1400  extracts an address based on the above information and supplies a signal indicating the address to the control portion  300 . 
     The imaging data output from the line sensor is supplied to the line memory  600  and the control portion  300  through the processing portion  500 . The control portion  300  determines a signal level of the imaging data. Based on the signal level, the control portion  300  controls the light source  100  so as to maintain the signal level of imaging data to be acquired by the next imaging operation to an appropriate value. Specifically, the control portion  300  controls the light source  100  so as to emit the determined light amount. The control portion  300  then controls the imager  200  to output a signal obtained by the next imaging. 
     The control portion  300  supplies the information indicating an address to the processing portion  500 . On the other hand, the line memory  600  supplies the stored imaging data to the processing portion  500 . The processing portion  500  associates the address information with the imaging data and supplies them to the frame memory  700 . 
     The biometric information acquisition portion  13  repeatedly makes control in such a way that the level of an output to be acquired by the next imaging becomes an optimum value. The light source  100  is controlled to emit an optimum light amount at the next imaging. By a change in the intensity of outside light, a change in the moving speed of the placing table  801  or the like, it is possible to deal with a change in the amount of light input to the line sensor.  FIG. 36  shows a signal obtained when the imager  200  captures images of the pattern  1200  and the finger while controlling the light amount of the light source  100 . 
     The above-described embodiments may be combined as appropriate. The semiconductor device  120  is applicable to the other embodiments. Further, the moving mechanism  800  may be applied to the other embodiments (the first embodiment, the sixth embodiment etc.). 
     A specific structure of the light illuminator is arbitrary. The biometric information acquisition apparatus may be applied to the biometric authentication apparatus that executes fingerprint authentication in addition to vein authentication. Equipment into which the biometric authentication apparatus is incorporated may be installation equipment in addition to a cellular phone, a laptop PC or the like. The subject is not limited to a human finger, and it may be another part of a human body such as a human palm. The image pickup device maybe a general image pickup device including a plurality of pixels arranged in matrix and capable of acquiring an image over a desired range at a time. The capacitance sensor may be the one including a plurality of electrodes arranged in matrix and capable of detecting an image of a fingerprint over a desired range at a time. A specific structure of the biometric authentication apparatus is arbitrary. Further, it is feasible to move the biometric information acquisition apparatus by a mechanical means, rather than moving the finger. A method of creating one authentication image from separated images may be also arbitrary. 
     From the invention thus described, it will be obvious that the embodiments of the invention may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended for inclusion within the scope of the following claims.