JP2009032227A - Finger vein authentication apparatus and information processing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a finger vein authentication apparatus applicable to a compact information processing apparatus like a mobile phone, and an information processing apparatus using the same. <P>SOLUTION: The finger vein authentication apparatus includes a light source for emitting light toward a finger, an image sensor for taking an image of the transmitted light from the finger, a lens apparatus for imaging the transmitted light to the image sensor, and an image processor for processing the taken image. The lens apparatus 33 includes a short focus wide angle lens unit 38, and the image processor extracts a vein pattern of the finger upon correcting the strain of the taken image. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a finger vein authentication apparatus and an information processing apparatus using the same, and more particularly to a technique for reducing the size of a finger vein authentication apparatus.

  Among various security technologies, the finger vein is known to be able to realize high-precision authentication. Finger vein authentication achieves excellent authentication accuracy because it uses a finger vein pattern inside the body, and can realize high security by being more difficult to forge and tamper than fingerprint authentication.

As a conventional example of this kind of finger vein authentication, for example, a biometric authentication device described in JP-A-2006-155575 is known. The biometric authentication apparatus includes: a light source that emits light passing through a finger; an imaging unit that captures light transmitted through the finger; a finger detection unit that detects that the finger is present at a predetermined position; and the imaging unit Finger area extracting means for extracting the area occupied by the finger from the image photographed by the above, and gain changing means for changing the amplification factor of the image pickup element in the image pickup section according to the image quality of a specific part inside the extracted area; It is equipped with.
JP 2006-155575 A

  Finger vein authentication has the advantage that the authentication device can be made smaller than palm vein authentication. However, in recent years, it is desired that the finger vein authentication device can be further downsized and applied to a small information device by electronic commerce using a small information device such as a mobile phone and the spread of an online bank.

  The biometric authentication device disclosed in Japanese Patent Application Laid-Open No. 2006-155575 always obtains an optimal vein pattern quality without being affected by differences in the external environment when imaging a finger vein pattern using transmitted light. Although it is an imaging method that can be used, there is no description about downsizing the authentication device.

  Therefore, an object of the present invention is to provide a finger vein authentication device applicable to a small device such as a mobile phone and an information processing device including the finger vein authentication device.

  In order to achieve the above object, a finger vein authentication device according to the present invention includes a housing on which a finger is placed, a light source that emits light toward the finger, and imaging that captures the environment inside the finger using the light. A lens device that includes an element, a short-focus wide-angle lens unit that focuses the light from the finger on the image sensor, and a pattern extraction unit that extracts a vein pattern of the finger from an image captured by the image sensor And an image processing unit that corrects image distortion.

  The information processing apparatus according to the present invention further includes the finger vein authentication device and a personal authentication device that performs personal authentication based on the vein pattern output from the finger vein authentication device. The electronic transaction processing is performed based on the authentication result.

  ADVANTAGE OF THE INVENTION According to this invention, the finger vein authentication apparatus applicable to small apparatuses, such as a mobile telephone, and an information processing apparatus provided with the same can be provided.

  A finger vein authentication device suitable for mounting on a small device such as a mobile phone will be described. In this finger vein authentication device, whether light is emitted into a finger from a light source such as an LED (Light Emitting Diode) provided below the finger (finger belly side) and whether the light diffused inside the finger is transmitted through the vein Alternatively, the light is emitted to the outside of the finger under the influence of the internal environment of the finger including the form (vein pattern) of the finger vein, such as reflected from the vein (hereinafter, this light is referred to as “transmitted light”). A base image is taken, a vein pattern is extracted from the image, and personal authentication is performed.

  In order for the imaging unit of the finger vein authentication device to capture a finger vein pattern image clearly, it is desirable to satisfy the following optical conditions. One is that the imaging unit does not capture infrared light reflected by the surface of the finger skin. If this condition is not satisfied, the image of the finger vein pattern includes unnecessary information such as wrinkles on the surface of the finger skin, and the image becomes unclear. The other is that the imaging unit does not capture the infrared light scattered without reaching the depth at which the finger vein exists. If this condition is not satisfied, infrared light that does not contain information on the finger vein pattern will reduce the contrast of the finger vein pattern.

  FIG. 1 is a perspective view showing an example of a finger vein authentication device, which is configured to have a casing 10 that is formed in a cubic shape as a whole. On the plane side of the housing 10, a finger guide portion 11 for placing a finger is provided as shown in FIG. The finger guide portion 11 includes a wall 16, a small protrusion 18, and a small piece 22.

  Further, a groove 12 for separating the finger to be authenticated and an optical system to be described later is provided on the plane side of the housing 10 in order to secure a focal length. As will be described later, in this example, the depth of the groove 12 can be reduced by applying a short focus and wide angle lens unit to the optical system. As a result, the size of the finger vein authentication device is reduced in the thickness direction. Can be

  The width of the groove 12 is narrower than the finger width. The user places his / her finger so as to cover all the grooves 12 as shown in FIG. Thereby, it can prevent that the light and the external light which were discharge | released from the light irradiation port 14 installed in the finger | toe side surface are directly irradiated to the ventral | abdominal side surface of the finger | toe on the groove part 12. FIG. Since less light is reflected from the finger surface, a clear vein image can be taken.

  The irradiation port 14 is disposed outside the finger guide unit 11 so as to emit light generated from a light source such as an LED disposed inside the housing 10 toward the user's finger placed on the finger guide unit 11. It is a light exit provided. In addition, in this example, although the shape of the irradiation port 14 is circular, it is not limited to this, A polygon, such as an ellipse and a rectangle, may be sufficient.

  The bottom surface 24 of the groove 12 is provided with, for example, a rectangular (rectangular) transmitted light inlet 20 for capturing transmitted light from a finger. An IR filter is laid at the transmitted light inlet 20. The IR filter blocks outside light unnecessary for authentication, such as sunlight and fluorescent light. Also, dust and water droplets are prevented from entering the authentication device. An image based on the transmitted light captured from the transmitted light capturing port 20 is captured by a lens device or an image sensor disposed below the bottom surface 24.

  The wall 16 has a relatively short height and protrudes toward the finger, and is formed in a strip shape along the longitudinal direction of the finger on both sides of the finger. Further, since the pair of formed walls 16 face each other in parallel, it has a function of supporting the fingers when the fingers are placed on the plane of the housing 10 and prevents the fingers from shifting in the left-right direction. be able to.

  Further, the wall 16 is made of a material that is opaque to infrared light. This has a function of guiding the light emitted from the plurality of light emission ports 14 arranged on the outer edge side of the flat portion of the housing to the side surface of the finger rather than the finger bottom.

  When the wall 16 makes light incident on the finger from the side of the finger, the light component reaching the deep part of the finger increases with respect to the vein pattern to be photographed, and accordingly, the reflection from the finger surface reduces the image quality as described above. Since the light component is reduced, clear transmitted light can be imaged. Furthermore, since the wall 16 can irradiate the side surface of the finger at a position higher than the finger belly, the finger vein authentication device can capture a clear vein image.

  As shown in FIG. 16, when light enters the finger not from the side of the finger but from the bottom of the finger, the light is indicated by an arrow 82 under the influence of the scattering material 84 such as the epidermis or tissue of the finger. The light that does not reach the vein pattern 80 to be photographed is reflected toward the image sensor 30 side. As a result, light having no vein information is concentrated on the image sensor, and there is a disadvantage that the contrast with respect to the image corresponding to the vein is lowered.

  On the other hand, the finger vein authentication device makes light incident from the side surface of the finger, so that the reflected light component that lowers the contrast described above reaches the lens device 33 while avoiding reaching the lens device 33, It is possible to increase the rate at which the transmitted light 86 having information on the vein pattern reaches the lens device 33 by being transmitted through the finger vein or reflected from the vein.

  In addition, a small protrusion 18 having a short rectangular shape and protruding toward the finger side is present at substantially the center in the longitudinal direction of the wall 16. The small protrusion has a role of pointing to the first joint of the finger, and the user places a finger on the casing so that the first joint of the finger hits the pair of small protrusions 18, thereby the lens unit described below and A vein pattern in which the image sensor is in the vicinity of the first joint of the finger can be captured. Since the joint portion of the finger is recessed compared to the front and back portions thereof, the small protrusion 18 can easily fit into the recessed portion.

  In finger vein authentication, a vein pattern near the first joint of a finger is useful for highly accurate biometric identification. Therefore, it is desirable that the transmitted light capturing port 20 has a rectangular shape having an area capable of capturing an image near the first joint of the finger, for example, a rectangular shape having a long side (10 mm to 20 mm) and a short side (5 mm to 10 mm). When the transmitted light inlet 20 is set to this size, the size of the subject of the finger is about 10 mm × 20 mm.

  The reason why the vein pattern in the vicinity of the first joint of the finger is useful for high-precision biometric identification is that the skin is thin in the vicinity of the joint and the veins are easy to see through.

  The small protrusion 18 may be installed not only at the position of the first joint but also at the position where the fingertip is placed. By performing positioning by touching a plurality of points, the presentation position of the finger is stabilized. A touch sensor may be installed on the small protrusion 18. Thereby, it can be detected that the finger has been placed on the housing 10 reliably, the presenting position of the finger is stabilized every time, and it is possible to prevent the finger vein from being photographed while the finger is away from the apparatus.

  For the same reason, the veins are easily seen through the second joint of the finger. Therefore, it is also possible to use the small protrusion 18 for authentication by aligning the second joint. However, when alignment is performed at the second joint, the finger protrudes greatly from the authentication device to the fingertip side, and when the authentication device is installed, a wider open space is required on the fingertip side. In order to use the authentication device in a compact manner, it is preferable to photograph the first joint.

  Instead of the small protrusion 18, other instruction means such as a sign or a mark indicating the position where the first joint of the finger is placed may be used.

  FIG. 19A is a cross-sectional view showing the installation position of the light source 3 when the casing 10 of FIG. 2 is viewed from the fingertip side. An infrared light source 3 is embedded in the light irradiation port 14. For example, an LED can be used as the light source 3. This may be a bullet-type LED as shown in FIG. 19 (1), or an LED having a flat top surface.

  Hereinafter, the installation position of the light source 3 will be described. The light source 3 is installed on the belly side of the finger. In the conventional finger vein authentication device, since the light source is installed on the upper side or the side surface of the finger, it is necessary to extend the housing to the upper side or the side of the finger to support the light source. I had to increase it. When the light source is installed on the belly side of the finger, it is possible to avoid extending the housing to the upper side or the side surface of the finger, so that the housing can be thinned. Further, as will be described later, the light source 3 was installed on the side surface of the finger in order to reduce the influence of wrinkles on the finger surface.

  There are many fingerprints and joint wrinkles on the finger surface. In order to improve the accuracy for authentication, the veins must be clearly photographed while suppressing the influence of wrinkles. In order to suppress the influence of wrinkles, the light source is arranged in the housing in consideration of the direction of wrinkles.

  For example, when the direction of the wrinkle is perpendicular to the longitudinal direction of the finger, the light source is installed on the side of the finger. As a result, the path of the light emitted from the light source and the direction of the wrinkle become parallel. Accordingly, since the light reaches the image sensor without colliding with the wrinkle wall, the image sensor can capture an image with reduced influence of the wrinkle.

  Since most of the wrinkles around the first joint of the finger are perpendicular to the longitudinal direction of the finger, a light source was installed on the side of the finger.

  In order to authenticate the finger vein, the image processing apparatus examines the luminance value of each pixel in the image, determines that the pixel whose luminance is lower than the surrounding pixels is a vein, and extracts a vein pattern from the image. In order to extract a vein pattern with high accuracy, it is important to irradiate the entire finger with light so that the amount of light is uniform, and the image pickup device captures an image with less luminance unevenness. If there is a bias in the light irradiation and only a part of the area is photographed dark, that area is erroneously extracted as a blood vessel when image processing is performed.

  FIG. 20 shows an example of the arrangement of the light source 3 and the light irradiation port 14 with respect to the housing for the vein authentication device to obtain an image with less luminance unevenness. 20 (1) to (6) are schematic views showing a plane of the housing 10. FIG.

  The light source 3 may be at least a pair on the left and right sides of the housing as long as it can irradiate the finger with sufficient brightness. However, in order to improve the image quality of the vein pattern image, as shown in FIGS. The light sources are preferably arranged in a plurality of pairs in the casing along the longitudinal direction of the finger.

  In this case, it is preferable that the distance between the light sources is made uniform on the left and right sides of the housing so that the light can be irradiated from the fingertip side to the finger base side with uniform brightness.

  Furthermore, it is preferable that the light amounts of a plurality of light sources on the left and right can be controlled independently. Furthermore, if sufficient light does not reach the fingertip and the finger base side only with the light source on the side surface of the finger, the light source 3 is also provided on the fingertip and the finger base side as shown in FIG. It is also possible to assist in the amount of light.

  When a plurality of light sources 3 are arranged, all the light sources 3 are not installed at equal intervals, but light sources are provided at the fingertips and the base side while avoiding the vicinity of the center of the housing as shown in FIGS. 20 (4) to (6). May be arranged. Because the first joint of the finger has thin skin, it is possible to image the vein with less light than other parts. Strong light hits the part other than the first joint, and the first joint receives slightly weak light. In this way, the amount of light can be made uniform over the entire image of the finger.

  The mode for optimally arranging the light source in the housing also varies depending on the characteristics of the optical components used for photographing. In order to reduce the size of the case of the finger vein authentication device, it is effective to use a short-focus lens unit. However, the short focus lens has a drawback that sensitivity tends to decrease as it goes to the periphery of the image. Therefore, when a finger is photographed with this type of lens, the sensitivity of the image region farther from the center of the image, that is, the image region on the fingertip side and the finger base side, becomes lower.

  Therefore, as shown in FIGS. 20 (4) and 20 (5), the light source 3 is arranged near the front end and the rear end of the casing. Thus, when a finger is presented on the housing, light is more strongly irradiated from the light source on the side surface on the fingertip side and the side surface on the finger base side. Therefore, the entire luminance of the captured image is uniform.

  As shown in FIGS. 20 (4) and 20 (5), when the light source is arranged in the casing so as to be on the fingertip and root side, the light emitted from the light source wraps around the fingertip and the ventral side of the finger base.

  As described above, it is useful to irradiate light from the side surface of the finger so that the scattered light from the scattering material 84 does not stand out from the captured image. It is necessary to suppress wraparound.

  Therefore, the wall described in FIG. 1 is placed in a U-shape as shown in FIG. 20 (4), or the wall 16 is sufficiently placed along the longitudinal direction of the finger as shown in FIG. 20 (5). Install it in the case so that it is long. As a result, light can be mainly irradiated on the side surfaces of the fingertip and finger base.

  As shown in FIG. 19 (1), the light source 3 is installed substantially perpendicular to the housing 10 on the left and right sides of the finger. Since the finger has a round shape when viewed from the fingertip side, when the light source 3 is installed on the casing on both sides of the finger and light is irradiated upward from the casing, the light is blocked by the wall 16 and the finger is positioned higher. To reach. This increases the contrast in the vein image.

  In FIG. 19A, the light source 3 exists outside the outline of the finger, but the light source 3 may be installed inside the casing (side closer to the groove 12) than the outline of the finger. Thereby, the width | variety of a housing | casing can be made small.

As described above, it is more preferable that the light source 3 is installed in the housing so as to be separated from the groove portion 12 to suppress the light that wraps around the bottom surface of the finger. It was found that it is sufficient if the distance between the light source 3 and the light source 3 (C _{1 in} FIG. 19 (1)) is at least 2 mm.

  The light source 3 may be slightly inclined toward the inside of the housing as shown in FIG. Thereby, even if the finger is thin, the light source can irradiate the finger with an amount of light sufficient for measurement. Alternatively, a plurality of light sources 3 having different inclination angles may be installed in the housing, and the light sources 3 to be turned on may be switched for each finger thickness. Further, the angle of the light source may be controlled.

  Returning to FIG. 1 and continuing the description, the small piece 22 protrudes from the pair of wall portions 16 toward the center of the casing at each of the fingertip side substantially end portion and the arm side substantially end portion of the casing 10. FIG. 3 is an example of a front view of the small piece 22 as viewed from the casing 10 along the longitudinal direction of the finger vein authentication device according to FIG. In the example of FIG. 3, the small piece 22 includes a tapered surface 22 a that decreases in height toward the center of the housing 10.

  When the finger is placed on the flat surface side of the housing 10, the finger is guided toward the bottom surface of the housing according to the tapered surface 22 </ b> A so that the finger comes into closer contact with the housing. Therefore, it is possible to prevent external light from entering the imaging unit from the gap between the finger and the housing 10 through the gap between the imaging units.

  FIG. 4 is a schematic diagram showing an example of the internal configuration of the finger vein authentication device shown in FIG. 1 and the positional relationship with the finger.

  The lens device 33 forms an image of transmitted light on the image sensor 30, and a lens unit 38 including a first lens 34 on the finger side and a second lens 36 on the image sensor side is supported and fixed to a lens housing 39. It has a configuration. The first lens 34 and the second lens 36 are housed in a lens housing 39 so as to face each other along the optical axis 41.

  The first lens 34 and the second lens 36 are extremely small diameter lenses having an effective diameter (D in FIG. 4) of about 2 mm or less, preferably 1 mm to 1.5 mm. The first lens 34 is formed in a concave shape on the image sensor 30 side. The second lens is a concave lens having a negative power, and the second lens is a convex lens having a positive power on the finger side and the imaging element 30 side.

  The transmitted light inlet 20 formed on the bottom surface 24 of the groove 12 is closed by an IR filter 40.

  Reference numeral 28 denotes a substrate supported by the bottom surface portion 26 of the housing 10.

  On the substrate 28, an image sensor 30 made of CCD or CMOS is fixed, and a peripheral circuit of the image sensor 30 is provided.

  The lens housing 39 is formed in a hollow cylindrical shape so that the lens unit 38 can be accommodated. The lens housing 39 is supported on the substrate 28 by a support member 70.

  The lens unit 38 has a characteristic as a lens having a short focal length and a wide angle of view by combining concave and convex lenses. As a result, the lens unit can be brought close to the finger that is the subject, and a wide range of images can be taken into the image sensor even if the lens unit is brought close to the finger.

  As a result, the distance (conjugate distance) L1 between the finger base 46 and the image sensor 30 can be reduced, and the inventors have verified that the conjugate distance can be within a range of 5 mm to 12 mm. Therefore, the thickness of the housing 10 can be reduced. Thereby, for example, even when the finger vein authentication device 50 is mounted on one casing 52 of a folding mobile phone as shown in FIG. it can.

  Note that FIG. 5 is an example, and the finger vein authentication device 50 may be arranged in the other housing on which the key operation unit 53 is mounted.

  In FIG. 4, reference numeral 48 indicates a just focus position, and reference sign L <b> 2 is a just focus length between the just focus position in the finger and the image sensor 30. The distance between the lens unit 38 and the image sensor 30 is adjusted by moving the lens device 33 forward and backward with respect to the image sensor 30 so that the just focus position 48 is in the finger.

  Even if the distance (conjugate distance) L1 between the finger base 46 and the image sensor 30 is reduced, the just focus position can be set in the finger, so the image sensor 30 corresponds to the vein pattern in the finger. Can produce images.

  As described above, the optical characteristics of the lens unit have been described as short focus and wide angle of view, but preferably the focal length is 0.2 mm to 0.5 mm, and the object side maximum angle of view is 100 ° or more. . If the focal length is less than 0.2 mm, it is difficult to manufacture the lens unit. If the focal length exceeds 0.5 mm, the distance L1 in FIG. 4 cannot be made sufficiently small.

  Furthermore, when the object-side maximum field angle is 100 ° or more, a vein pattern in the range of 10 mm before and after the first joint of the finger can be acquired. In order to perform vein authentication with high accuracy, it is desirable to acquire vein patterns in this range.

  Further, the lens unit preferably has a paraxial magnification of 0.04 or more and 0.1 or less. If the paraxial magnification is less than 0.04, the resolution deteriorates, and if the paraxial magnification exceeds 0.1, there is a possibility that an imaging area necessary for vein pattern authentication cannot be secured.

  If a short-focus lens unit is used, the authentication device can be miniaturized in the height direction as described above. On the other hand, the image obtained by the image sensor 30 may be distorted, and the vein pattern may not be accurately extracted from the image. is there.

  Therefore, the vein authentication device includes an image processing function / means for correcting image distortion. When the present inventor specifically examined various characteristics of the lens unit, it was confirmed that the distortion of the image can be corrected if the optical distortion of the image is in the range of −60% to + 40%.

  In the example of FIG. 4, the lens unit 39 is composed of two lenses. However, the lens unit 39 is not limited to this, and as long as it has the required lens characteristics, one lens or three or more lenses are used. A lens unit may be configured from the lens.

  FIG. 6 is an image before correction obtained by the image sensor 30, and FIG. 7 is an example of an image after distortion correction. The image in FIG. 6 is an image obtained by the image sensor 30 by placing a printed material on which a grid image having a 1 mm interval is printed on the plane side of the housing 10 in FIG. 1. When the distortion was corrected, an image whose shape was distorted toward the periphery as shown in FIG. 6 was corrected or corrected to an image having a substantially uniform grid as shown in FIG. A distortion correction control method will be described later.

  FIG. 8 is a graph showing distortion characteristics. The object height shown in FIG. 8 means the relative position from the center point of the image (optical axis: 41 in FIG. 4) to the edge of the image. For example, the object height of “1.0” means the edge of the image. The object height of “0.6” represents a position 60% from the center point (40% from the end).

  In FIG. 8, 800 is the characteristic of the first lens unit, and 802 is the characteristic of the second lens unit. A negative distortion characteristic indicates that the pixel is distorted toward the center of the image, and a positive distortion characteristic indicates that the pixel is distorted in a direction away from the center of the image.

  The distortion (%) is a value corresponding to “T / S” with respect to the original position of the pixel (distance “T” from the center) and the position of the pixel after distortion (distance “S” from the center). It is. As a result of intensive studies by the inventor, when the optical distortion is less than −60%, the resolution in the peripheral portion deteriorates suddenly, and the image cannot be completely restored even if image distortion correction described later is performed. It has been found.

  Further, it has been found that when the optical distortion exceeds + 40%, it is necessary to process a wide range of images, causing a problem in processing time. Therefore, as long as the distortion is limited between the first characteristic (800) and the second characteristic (802), that is, as long as the optical distortion is within the range of −60% to + 40%, the image Distortion can be corrected by the processing unit.

  As a characteristic of the lens unit, it is preferable that the sensitivity ratio at the maximum object-side angle of view is 10% to 40%. As shown in FIG. 9, the sensitivity of the lens unit with a short focal length and a wide angle of view decreases as it goes to the periphery of the image.

  In FIG. 9, 900 is the sensitivity ratio characteristic of the first lens unit, and 902 is the sensitivity ratio characteristic of the second lens unit. For example, a sensitivity ratio of “0.4” indicates that the luminance is 40% when the luminance at the center of the image is “1.0”. The reduction in sensitivity of the short focus / high angle of view lens unit can be compensated for by irradiating light from the side surface of the finger by arranging the light outlet in the peripheral region of the housing 10 as shown in FIG. .

  As a result of intensive studies by the present inventors, the sensitivity ratio at the maximum object-side angle of view (object height is “1.0”) indicates that the characteristics of the first lens unit (900) and the characteristics of the second lens unit (902). In other words, it was confirmed that the decrease in sensitivity can be compensated if the sensitivity ratio is in the range of 10% to 40%. Therefore, the imaging device 30 can accurately capture the vein pattern in the finger even from the region of the object side maximum field angle of the lens unit.

  Next, the image processing and authentication function of the finger vein authentication device will be described. FIG. 10 is a block diagram illustrating a configuration example relating to the image processing device of the finger vein authentication device. The image processing apparatus includes a pattern extraction unit that extracts a finger vein pattern from an image captured by an image sensor, and an image correction unit that corrects image distortion.

  A CPU (Central Processing Unit) 60 starts an image processing program recorded in the memory 64 based on a user operation, and instructs a DSP (Digital Signal Processor) 62 to capture an image from the image sensor 30. The CPU 60 takes in luminance data of each pixel of the image sensor 30 from the DSP 62 and determines whether or not a finger is placed on the housing 10.

  When the finger is not placed on the housing 10, the external light reaches the image sensor 30, and the luminance of the pixel increases more than a predetermined value. Therefore, the CPU 60 determines that the finger is not placed on the housing 10.

  When the CPU 60 determines that a finger is placed on the housing 10, the luminance of each pixel of the image obtained by the image sensor 30 is checked, and the luminance is uniform among the pixels from the plurality of irradiation ports 14. Control the amount of emitted light individually. Specifically, the amount of light emitted from the irradiation port 14 is controlled by controlling the drive signal supplied to each light source arranged corresponding to each irradiation port 14 and correcting the light emission amount of the light source. .

  Hereinafter, the light amount control will be described in detail. The appropriate amount of light varies depending on the width and thickness of the finger presented to the finger vein authentication device. Therefore, in order to capture a clear finger vein image, it is necessary to adjust the light amount of the light source for each feature of the finger.

  For example, when the thickness of the finger is thin, the luminance tends to be higher than that of a thick finger, so the amount of light is reduced. In addition, a finger having a small width is less likely to receive light because a distance from the light irradiation opening to the finger is longer than that of a finger having a large width. In order to irradiate a finger with a sufficient amount of light, it is necessary to increase the amount of light emitted from the light irradiation port 14.

  Further, even with the same finger, since the width is different between the fingertip side and the finger base side, the appropriate light amount value is different. Therefore, the light amount values on the fingertip side and the finger base side are controlled independently. Alternatively, the finger width may be adjusted in advance so that the fingertip side becomes thicker using the feature that the fingertip is narrower and thicker at the fingertip, and the fingertip side and the fingertip side light quantity may be controlled simultaneously.

  In addition, when it is necessary to irradiate the finger with the same amount of light from each light source, the position of the light source may be arranged closer to the fingertip and further away from the root side. Furthermore, it is preferable to control the left and right light quantity values independently in consideration of the left-right asymmetry of the finger shape and the left-right positional shift when the finger is placed on the housing. The CPU 60 determines the asymmetry of the finger shape, the lateral displacement of the finger, the thickness of the finger, etc. based on the fact that the luminance between the plurality of pixels is not uniformed, Independently control the light source.

  When the CPU 60 determines the end of the light amount correction, the CPU 60 instructs the DSP 62 to perform distortion correction on the image captured by the image sensor 30. The distortion correction is performed by the calculation based on the above-described distortion characteristics. Therefore, the distortion characteristics of the lens unit 38 are obtained in advance and stored in the memory 64 before the finger vein authentication device is shipped. The DSP 62 refers to this distortion characteristic and performs distortion correction on each pixel of the image obtained by the image sensor 30.

  When the distortion is X%, the correction target pixel in the image is multiplied by the correction value (100 / X), and the pixel position with respect to the image center (optical axis) is corrected based on the calculation result. When the distortion is positive, the pixel position is corrected toward the optical axis, and when the distortion is negative, the pixel position is corrected in a direction away from the optical axis. As a result, for example, as shown in FIGS. 6 and 7, a distorted image can be corrected.

  The CPU 60 stores the image after distortion correction in the memory 64, and the CPU 60 determines the density of each pixel of the corrected monochrome image and extracts a vein pattern from the corrected image (feature point extraction).

  Near-infrared light irradiated on the finger from the light source is absorbed by hemoglobin in the vein, but diffuses in various directions by other tissues, so that transmitted light corresponding to the vein pattern passes through the lens unit 38 and is imaged. To 30. Since the transmitted light is weakened by absorption in the pixel region corresponding to the vein pattern, the imaging element 30 obtains a monochrome image in which the region corresponding to the vein pattern is dark.

  The CPU 60 detects a vein pattern from the monochrome image and performs biometric authentication using the detected vein pattern. Specifically, the vein pattern extracted by the finger vein authentication device in this way is registered in the memory 64, and it is determined whether the registered vein pattern and the newly extracted vein pattern match or do not match. To determine whether or not to authenticate the user.

  When the finger vein authentication device is installed in an information processing device such as a mobile phone, or is connected to an external device by wire or wireless, the CPU 60 notifies the information processing device or external device of the result of personal authentication. Using this notification, the information processing apparatus or the like provides various services such as electronic commerce and net banking to the user.

  In the above description, the feature point extraction process is performed after the distortion correction is performed. However, the distortion correction may be performed after the vein pattern is extracted from the image by the feature point extraction process.

  In this case, since the number of pixels to be subjected to distortion correction can be limited to the number of pixels corresponding to the vein pattern, there is an advantage that the DSP 62 can reduce the processing time required for distortion correction. Compared to the case where distortion correction is performed for all pixels, the number of pixels that need to be corrected can be reduced to about 1/8 by performing distortion correction after feature point extraction.

  In the example of FIG. 10, the CPU 60, the DSP 62, and the memory 64 are configured separately, but the present invention is not limited to this, and a part or all of these may be configured as one processing unit. .

  When the finger vein authentication device is mounted on an information processing device such as a mobile phone, image processing and authentication are performed using the CPU of the information processing device instead of providing the CPU 60 or the like in the authentication device. May be.

  Further, part or all of the image processing and authentication functions may be transferred from the information processing apparatus to the server side. Furthermore, instead of storing the vein pattern data in the finger vein authentication device or the information processing device, the pattern data may be registered in the server. When a vein pattern is registered in a finger vein authentication device or an information processing device, the vein pattern is registered after being encrypted so that it cannot be read by others.

  Next, an embodiment in which the finger vein authentication device is applied to a mobile phone will be described in detail. Since the finger vein authentication device described above can shorten the distance between the finger base and the image sensor, even if it is a small information processing device such as a mobile phone, the finger vein authentication device can be used while suppressing the increase in size of the device. It can be mounted on an information processing apparatus.

  11 (1) is a plan view of the casing 52 of the mobile phone, FIG. 11 (2) is a right side view thereof, and (3) is a front view thereof. In this example, the vein authentication device 50 is mounted from the hinge of the mobile phone. In order to make it easy for the user to understand the existence of the vein authentication device 50, the housing 10 of the vein authentication device 50 slightly protrudes from the surface of the housing 52 of the mobile phone.

  As shown in FIG. 12, the user can place the vicinity of the first joint of the index finger on the vein authentication device 50 while holding the mobile phone with only one hand. The tip of the vein authentication device 50 is approximately 3 cm from the tip end of the mobile phone so that the vicinity of the first joint of the finger to be authenticated can be aligned with the vein authentication device while holding the mobile phone 50 in a stable state with one hand. It is preferable to provide at the position.

  Further, as shown in FIG. 13, the vein authentication device 50 may be provided near the open end of the mobile phone. In this case, it is preferable to provide the base end of the authentication device at a position of about 3 cm corresponding to the distance between the fingertip and the first joint from the open end of the mobile phone. By arranging at such a position, when the finger is placed on the vein authentication device 50, the second joint of the finger is naturally bent gently and the finger is prevented from being pressed too much against the vein authentication device 50. Can do.

  In the example of FIG. 5, FIG. 11, etc., it is provided on the plane part of the casing 52 of the mobile phone. However, the present invention is not limited to this. You may do it.

  As described above, the example in which the finger vein authentication device is mounted on the mobile phone has been described. However, the target to which the finger vein authentication device is applied is not limited to the mobile phone, and may be various information processing devices such as a PDA and a notebook personal computer. . In addition to the information processing apparatus, the finger vein authentication apparatus may be mounted on a car or an entry / exit management apparatus.

  FIG. 14 is an AA cross-sectional example of FIG. 1, and FIG. 15 is a BB cross-sectional example thereof. 14 and 15 show how the finger vein authentication device is housed in the mobile phone 52 together with the mobile phone. That is, the housing 10 also serves as a mobile phone housing. In addition, the same code | symbol as the already-mentioned drawing means that it is the same member, and abbreviate | omits description.

  An LED 72 that is a light source is embedded in the casing of the mobile phone 52. A through hole 74 is formed in the housing 10 in a direction perpendicular to the width direction of the LED from the top of the LED 72, and the through hole 74 is connected to the irradiation port 14. Near-infrared light emitted from the LED 72 passes through the through hole 74 and proceeds from the irradiation port 14 toward the finger. Since the wall 16 is provided in the vicinity of the finger bottom along the longitudinal direction of the finger, the light emitted from the LDE 72 enters the finger from the side of the finger across the wall 16.

  The light that has entered from the side of the finger diffuses inside the finger and partly passes through the vein and reaches the image sensor 30 side. The lens unit 38 displays an image corresponding to the vein pattern from the transmitted light on the image sensor 30. Form an image.

  FIG. 17 shows another example of the internal configuration of the finger vein authentication device. In the example of FIG. 14, the center of the irradiation port 14 and the center of the LED 72 are substantially aligned so that light is efficiently emitted from the irradiation port 14. Since the irradiation port 14 is provided outside the wall 16, the width of the finger vein authentication device is increased when the LED 72 is arranged in alignment with the center of the irradiation port 14 as described above.

  In contrast, in the example shown in FIG. 17, the width is narrowed by providing a light guide 90 that guides the light generated from the LED 72 to the irradiation port 14.

  The light guide 90 includes a tapered surface 92 that is inclined toward the outer peripheral side of the housing 10 as it approaches the irradiation port 14. The emitted light that has entered the bottom surface of the light guide 90 from the LED 72 is guided along the tapered surface 92 and is emitted from the irradiation port 14 toward the side surface of the finger.

  Accordingly, the center of the LED 72 can be provided inside the center of the irradiation port 14 while keeping the light efficiently emitted from the irradiation port 14, and thus the width of the finger vein authentication device is reduced. Can do.

  Further, the light guide 90 may be provided for each LED 72 arranged corresponding to each irradiation port 14, or one light guide is provided for each of the plurality of LEDs 72 provided on the left side and the right side. You may make it provide.

  When one light guide is provided on each of the left side and the right side, one rectangular or elliptical irradiation port may be provided along the wall 16 instead of providing a plurality of irradiation ports. By providing such an irradiation port, the light guide can be used in common for a plurality of LEDs, and light can be uniformly applied to the side surface of the finger. Moreover, you may make it provide the irradiation port which has shapes, such as a rectangle, not only in the left-right direction but in the up-down direction.

  FIG. 18 shows an example in which rectangular irradiation ports 14 </ b> A are provided on the left and right and up and down directions of the housing 10. In this example, the projection 18A that indicates the installation position of the first joint of the finger is configured to protrude inward in the width direction of the housing 10, and the small piece 22A that guides the finger toward the groove side is the finger 22A. The taper surface is formed in an R shape in accordance with the outer peripheral shape of.

  Next, the shape of the aforementioned wall 16 will be described in detail. FIG. 19A is a view of the authentication apparatus shown in FIG. 1 as viewed from the fingertip side. 21 and 22 show other forms of the wall 16.

  As shown in FIG. 19 (1), the width of the wall 16 is substantially the same as the distance between the inner edge of the light irradiation port 14 and the outer edge of the groove 16. As shown in FIG. 21, the wall 16 may be narrower than that in FIG. 19 (1), and may be installed in the housing close to the light irradiation port 12 side. As a result, the fulcrum supporting the finger moves to the outside of the finger, and the finger can be placed at a lower position with respect to the housing. Therefore, the height of the wall 16 with respect to the finger is relatively high, and the light source 3 can irradiate light only on the high position of the finger.

  Further, as shown in FIG. 22, the wall 16 may have an R shape in accordance with the outer peripheral shape of the finger. Thereby, since the area which a finger | toe and the wall 16 touch increases, the wall 16 can improve the effect which interrupts | blocks the light which wraps around to the bottom face of a finger | toe. Since the wall 16 matches the shape of the side surface of the finger, the wall 16 can stably support the finger with respect to the housing.

  The light source 3 is installed in the housing so that the upper end of the light source 3 is at the same height as the position of the plane of the housing 10 or slightly lower than that, so that the light source does not protrude from the plane of the housing.

  A part of the upper end of the light source 3 may be covered with the wall 16 or the housing 10 as long as a sufficient amount of light can be applied to the finger from the light source. For example, as shown in FIG. 23, when a part of the light source 3 is arranged so as to be hidden under the wall 16, the light source 3 can be placed close to the inside of the apparatus (the groove 12 side). Thereby, the width | variety of an authentication apparatus can be shortened.

  FIG. 24 shows a finger vein authentication device in which a filter 230 having a different light attenuation rate depending on a region is installed in a housing. 24 (1) is a sectional view of the apparatus, and FIG. 24 (2) is a plan view. FIG. 24 (3) shows the filter 230. A darker region of the filter indicates a higher light attenuation rate, and a thinner region indicates a lower light attenuation rate.

  When a vein is photographed by an authentication device in which a light source is installed on the side surface of the finger as shown in FIG. 24 (2), the photographed image has a higher brightness value in a region closer to the light source and a lower brightness value in a central region of the image. Become. Therefore, a filter 230 is installed between the finger and the image sensor 30 as shown in FIG. As a result, the amount of light reaching the image sensor 30 is uniform between the left and right finger regions and the central region, and it is possible to capture a vein image with uniform brightness over the entire image. Further, the image processing apparatus may perform sensitivity control such as gain and shutter speed for each pixel by the image sensor 30 without installing the filter 230. By lowering the sensitivity of the pixels on the light source side and increasing the sensitivity of the central pixel, it is possible to obtain the same effect as when the filter 230 is installed.

  In the above-described embodiment, the lens unit is composed of two lenses in two groups. However, the lens unit may be composed of one lens or three or more lenses as long as the required lens characteristics are obtained. .

  Of course, the object to which the vein authentication apparatus according to the present invention is applied is not limited to a mobile phone, but may be various information processing apparatuses such as a PDA and a notebook personal computer. In addition to the information processing apparatus, the finger vein authentication apparatus may be mounted on a car or an entry / exit management apparatus.

  Further, the housing is provided with a protruding portion as an instruction means for instructing a position where the first joint of the finger is placed. The instruction means may be used.

  In the above-described embodiment, the finger vein authentication device is provided on the plane of the mobile phone. However, the finger vein authentication device may be provided on the bottom surface of the mobile phone, the side surface, the front surface, or the bottom surface of the mobile phone.

  In the above-described embodiment, the abdomen side of the finger is presented on the housing 10 and the veins on the finger abdomen side are photographed. However, the side and back side of the finger are presented on the housing 10 and You may authenticate using a vein. In particular, when photographing the back side of a finger, it is possible to photograph a clear vein by photographing with the finger bent.

  In the above-described embodiment, the periphery of the first joint of the finger is photographed, but the periphery of the second joint of the finger or a part other than the joint may be used for authentication.

  The embodiment described above is an example, and the present invention is not limited to the above-described embodiment.

It is a perspective view which shows an example of a finger vein authentication apparatus. It is a perspective view which shows the state in which the finger is mounted on the finger vein authentication apparatus. It is an example of the front view of the small piece of a finger vein authentication apparatus. It is the schematic which shows an example of the internal structure of a finger vein authentication apparatus, and the positional relationship with a finger. It is a perspective view which shows an example of the mobile telephone by which a finger vein authentication apparatus is mounted. An example of an image (with distortion) obtained by an image sensor is shown. An example of a corrected image after applying a distortion correction document to an image obtained by an image sensor is shown. It is a characteristic view which shows an example of the relationship between an object height and distortion (%). It is a characteristic view which shows an example of the relationship between an object height and the sensitivity ratio of a lens unit. It is a block diagram which shows the structural example regarding the image processing function of a finger vein authentication apparatus. It is a top view, a right side view, and a front view showing an example of a mobile phone equipped with a finger vein authentication device. It is a perspective view which shows the example of a state in which the user is holding the mobile phone with one hand. It is a perspective view which shows the example of a state in which the user is holding the mobile phone with one hand. It is a figure which shows an example of the AA cross section of the finger vein authentication apparatus shown in FIG. It is a figure which shows an example of the BB cross section of the finger vein authentication apparatus shown in FIG. It is a figure explaining the optical model concerning finger vein authentication. It is a figure which shows an example of an internal structure of a finger vein authentication apparatus. It is a perspective view which shows an example of a finger vein authentication apparatus. It is sectional drawing of the state which looked at the finger vein authentication apparatus of FIG. 2 from the fingertip side. It is a top view of a housing | casing for demonstrating the several form at the time of arrange | positioning a light source to the vein authentication apparatus. (1) is a top view of the housing | casing provided with other embodiment of the light-shielding wall, (2) It is sectional drawing which looked at this housing | casing from the fingertip side. (1) is a top view of the housing | casing provided with other embodiment of the light-shielding wall, (2) It is sectional drawing which looked at this housing | casing from the fingertip side. (1) is a top view of the housing | casing provided with other embodiment of the light-shielding wall, (2) It is sectional drawing which looked at this housing | casing from the fingertip side. (1) is a cross-sectional view of the finger vein authentication device with the neutral density filter as viewed from the fingertip, (2) is a plan view thereof, and (3) is a plan view of the neutral density filter. is there.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Case (finger vein authentication apparatus), 11 Finger guide part, 12 Groove part, 14 Irradiation port, 16 Wall, 18 Protrusion part, 20 Transmitted light taking-in port, 28 Substrate, 30 Image sensor, 33 Lens apparatus, 34 1st Lens, 36 second lens, 38 lens unit, 40 IR filter, 39 lens housing.

Claims (12)

A housing for placing a finger;
A light source that emits light toward the finger;
An image sensor that images the inside of the finger with the light;
A lens device comprising a short-focus wide-angle lens unit that focuses the light from the finger on the image sensor; and
An image processing apparatus comprising: a pattern extraction unit that extracts the finger vein pattern from an image captured by the image sensor; and an image correction unit that corrects image distortion;
A finger vein authentication device comprising:   The finger vein authentication device according to claim 1, wherein the light source is configured to emit near infrared light from a side surface of the finger.   The finger vein authentication device according to claim 1, wherein the lens unit includes a concave lens and a convex lens.   The finger vein authentication device according to claim 1, wherein the lens unit is configured such that a sensitivity ratio at an object-side maximum field angle is limited to a predetermined range.   The finger vein authentication device according to claim 1, wherein the pattern extraction unit extracts the vein pattern from the corrected image after the image correction unit corrects distortion of the image captured by the image sensor.   The finger vein authentication device according to claim 1, wherein after the pattern extraction unit extracts the vein pattern from the captured image, the image correction unit corrects distortion of the extracted vein pattern.   The finger vein authentication device according to claim 1, further comprising a light guide that guides light generated from the light source to the light irradiation port provided in the housing.   The finger vein authentication device according to claim 7, wherein the light emission port is provided in the casing in the vicinity of a side surface in the longitudinal direction of the finger.   The finger vein authentication device according to claim 1, wherein the housing is provided with instruction means for instructing a position where the first joint of the finger is placed.   The finger vein authentication device according to claim 1, wherein the housing is provided with a protruding portion along a side surface of the finger. An information processing apparatus having a finger vein authentication function,
A finger guide unit on which a finger of a user of the information processing apparatus is placed;
A light source that emits light;
An irradiation port provided outside the finger guide part so as to emit light generated from the light source toward the side surface of the user's finger placed on the finger guide part;
A light guide portion for guiding light generated from the light source to the irradiation port;
An image sensor for imaging transmitted light from the user's finger;
A lens unit that forms an image of the transmitted light on the imaging device;
An image processing unit for processing an image captured by the image sensor;
An information processing apparatus comprising:   The personal authentication device comprising: Information processing apparatus for performing electronic transaction processing based on the authentication result in

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