JPH0823885B2 - Biological detection device and fingerprint collation system using the device - Google Patents

Description

The present invention relates to a living body detection device and a fingerprint collation system using the device, and instantly determines whether the detection target is a living body or a non-living body regardless of the conditions of the detection target. For that purpose, the light beam from the light source is condensed and irradiated on the surface of the detection target in a spot shape, and the light reflected or scattered from the irradiated portion is condensed to form an image of the irradiated portion at a predetermined position. Or by detecting the size of the image of the formed irradiation portion and outputting a detection signal instructing it, or
The light beam from the light source is condensed and irradiated on the surface of the detection target in a spot shape, and the light reflected or scattered from the irradiated portion is condensed to form an image of the irradiated portion at a predetermined position,
While detecting the size of the image of the formed irradiation portion,
Detecting whether or not the center position of the region where reflection or scattering occurs by irradiation of the light beam on the detection target is displaced from the center position of the irradiation portion of the light beam, and detects the size and displacement of the detected image. By outputting a detection signal indicating presence or absence, or by linearly polarizing and condensing a light beam from a light source and irradiating the surface of the detection target in a spot shape, the light reflected or scattered from the irradiation portion is emitted. By collecting and polarizing the light in a predetermined direction and outputting a detection signal indicating the polarization state of the polarized light,
The non-living body is determined based on the output detection signal.

[Industrial applications]

The present invention relates to a biometric device and a fingerprint matching system using the device.

[Conventional technology]

With the introduction of information systems into society in recent years,
The problem is how to keep the system safe.
When using the information system, the person (identity; IDent
A so-called ID card is used as a means of confirming that it is an identity card), but this ID card may be lost or stolen, and the PIN etc. can be easily guessed from the information around the person. Such problems have been pointed out. Therefore, fingerprints with the characteristics of "universality" and "lifetime immutability" are considered as alternatives to ID cards, and a simple personal verification device or fingerprint verification system using fingerprints has been developed at various places. Is being promoted. In this fingerprint collation system, it is usual to handle a fingerprint as an image, and at that time, an input device for converting the detected fingerprint image into image data is required.

FIG. 15 schematically shows the structure of a typical fingerprint image input device. In this device, when the finger 70 is brought into contact with the transparent body 71 to illuminate the entire finger (illustrated by a solid arrow), the scattered light of the ridge (convex) portion of the fingerprint is totally reflected at the interface of the transparent body. The component (shown by a broken line) is imaged by the optical system 72, and an image of a ridge pattern is obtained by using a photodetector 73 such as a charge coupled device (CCD).

However, if a replica having the same recess pattern as the fingerprint registered in advance is created, fingerprint matching can be performed by the replica, which is not preferable from the viewpoint of system safety. Therefore, a mechanism for identifying whether the concavo-convex pattern of the detection object that comes into contact with the fingerprint image input device is caused by a real finger (living body) or a replica (non-living body), that is, a living body detection mechanism. Is required.

As a conventional living body detection method, for example, as shown in FIG. 16, an optical method utilizing a change in the amount of transmitted light due to pulsation of a human body is known (first conventional example). This utilizes the fact that the light transmittance of the finger 80 with respect to the red light from the light source 81 changes at the same cycle as the pulsation, and the cycle of the transmittance change is measured through the photodetector 82, so that the living body or the non-living body It is to determine whether or not.

As another method, for example, as shown in FIG. 17, an electrical method is known that utilizes the difference between the resistance value of a finger and the resistance value of a replica (second conventional example). this is,
Distinction between living body and non-living body by providing transparent electrodes 91 and 92 on the contact surface of the finger (hatched portion), measuring the resistance value of the finger, and comparing with the preset resistance value of the replica. Is to do. In this case, the image of the electrode pattern is also captured in the fingerprint image input device together with the fingerprint image to be compared / determined.

[Problems to be Solved by the Invention]

In the above-described first conventional example, it takes a time of several seconds (several seconds or more) to detect a pulsation. Therefore, when detecting a living body, a finger image input device is used for a finger over a time required to detect the pulsation. The inconvenience arises of having to be kept in contact with. In other words, there is a drawback in that it is not possible to detect whether the detection target is a living body or a non-living body with respect to an instantaneous contact with the detection target.

On the other hand, according to the second conventional example, there is no problem in that the time required for living body detection is short. However, since there is a possibility that the pattern of the electrodes disturbs the fingerprint image, there is no problem in detecting the living body, but there is a disadvantage that the matching becomes difficult in the subsequent fingerprint matching. Also,
Since the resistance value of a human finger varies depending on the pressing force and greatly changes depending on the sweating state, the allowable resistance value must be set to be considerably large. However, if the allowable resistance value is increased, the difference between the resistance value of the replica and the resistance value of the replica becomes relatively small, which causes a problem of difficulty in comparison / discrimination during living body detection. Alternatively, conversely, it may be possible to make the replica have a resistance value equivalent to that of a human finger by some kind of work, so there remains a problem in terms of system safety.

In view of the above problems in the prior art, a main object of the present invention is to provide a living body detection apparatus capable of instantaneously discriminating whether the detection target is a living body or a non-living body, regardless of the conditions of the detection target. To do.

It is another object of the present invention to provide a system in which fingerprint matching is performed using the biometric device.

[Means for solving the problem]

When a spot-shaped light is applied to the surface of a detection target, a phenomenon peculiar to a human finger appears in the appearance of brilliance on the surface. That is, when the detection target is a living body (finger),
Not only the light irradiation point portion shines by reflection, but the irradiation light propagates and diffuses inside the finger and is reflected or scattered inside, so that the peripheral portion of the light irradiation point portion also shines. On the other hand, when the detection target is a non-living body (for example, a replica of silicon (Si) rubber or the like), only the very vicinity of the light irradiation point portion shines due to reflection or scattering.

Therefore, when an imaging optical system in which the light irradiation point is the object point is configured, the size of the object point differs between the living body and the non-living body, and the size of the image formed accordingly also differs. Therefore, by detecting and comparing / determining the size of the image, it is possible to detect whether the detection target is a living body or a non-living body.

Therefore, as the first embodiment of the living body detection apparatus according to the present invention, as shown in the principle diagram of FIG. 1, the light source 1 and the light beam L ₁ from the light source are condensed to be on the surface of the detection target 5. A condensing optical system 2 for irradiating in a spot shape, and an imaging optical system 3 for condensing the light L ₂ reflected or scattered from the irradiation portion of the light beam to form an image of the irradiation portion at a predetermined position. , A detection signal J ₁ which is arranged at the predetermined position, detects the size of the image of the formed irradiation portion, and indicates the size of the detected image
And a light detecting means 4 for outputting the living body, and it is determined whether the detection target is a living body or a non-living body based on a detection signal output from the light detecting means. A sensing device is provided.

When the spot-shaped light is radiated from the diagonal direction on the surface of the detection target, when the detection target is a real finger,
Since the irradiation light diffuses inside the finger as described above, the center of the region where reflection or scattering is caused by the light irradiation is displaced from the center position of the light irradiation portion. On the other hand, when the detection target is a replica, such displacement does not occur because the irradiation light does not propagate or diffuse inside.

Therefore, it is possible to detect whether the detection target is a living body or a non-living body by detecting the size of the formed image and the presence or absence of displacement.

Therefore, as a second mode of the living body detecting apparatus according to the present invention, as shown in the principle diagram of FIG. 2, the light source 1 and the light beam L ₁ from the light source are condensed to be on the surface of the detection target 5. Condensing optical system 2 for irradiating in a spot shape, and imaging optical system 3 for condensing light L ₂ ′ reflected or scattered from the irradiated portion of the light beam to form an image of the irradiated portion at a predetermined position. And a central position of a region R which is arranged at the predetermined position and detects the size of an image of the formed irradiation portion, and which is reflected or scattered by the irradiation of the light beam on the detection target.
Light detection means 4A that detects whether C ₁ is displaced from the center position C ₂ of the irradiation portion of the light beam and outputs a detection signal J ₂ that indicates the size of the detected image and the presence or absence of displacement The present invention provides a living body detection apparatus comprising: and a discrimination unit for discriminating whether the detection target is a living body or a non-living body based on a detection signal output from the light detecting means.

Further, when the spot-shaped light is linearly polarized and irradiated on the surface of the detection target, the irradiated light is reflected on the detection target, or internally reflected or scattered when the target is a finger. , Scattered light having various polarization direction components.

Therefore, when the scattered light is polarized in a predetermined direction, the light intensity of the component in the polarization direction differs between the living body (finger) and the non-living body (replica). Therefore, by comparing and determining the polarization states based on the light intensity of the polarization direction component, it is possible to detect whether the detection target is a living body or a non-living body.

Therefore, as a third form of the living body detection apparatus according to the present invention, as shown in the principle diagram of FIG. 3, the light source 1 and the light beam L ₁ from the light source are linearly polarized and condensed to be detected 5. Polarization / focusing optical system 2A that irradiates the surface of the object in spots
And the light reflected or scattered from the irradiated part of the light beam
L ₂ ″ is condensed, the condensing / polarizing optical system 3 A for condensing the condensed light in a predetermined direction, and the light intensity of the component in the polarization direction of the polarized light L ₃ are detected, It comprises a light detection means 4B which outputs a detection signal J ₃ which indicates the polarization state of the polarized light based on the detected light intensity, and the detection target is a living body based on the detection signal output from the light detection means. There is also provided a living body detecting device characterized in that it is discriminated whether it is a non-living body.

Further, according to the present invention, there is provided a fingerprint collation system including any one of the living body detecting devices of the above-described first to third embodiments. In this system, the pattern of the finger is converted into image data only when the target detected by the living body detection device is a finger, and the converted image data is compared with the image data of the fingerprint registered in advance. Check whether the person is the person.

[Action]

According to the above-described first and second embodiments, when the surface of the detection target is irradiated with spot-like light, a phenomenon peculiar to a human finger appears in the appearance of the brilliance of the surface, which is formed. By detecting the size of the image or whether the center of the region where reflection / scattering occurs is displaced from the center position of the light irradiation part, the detection target is a living body (real finger) or non-living body (replica). ) Is detected. Similarly, in the third embodiment, when the surface of the detection target is irradiated with linearly polarized light, the polarization characteristics of the light reflected or scattered from the surface are essentially different between the human finger and the replica. The living body is detected by comparing and determining the polarization states based on the light intensity of the polarization direction component.

Thus, the biological detection device according to the present invention, whether the target is a living body, regardless of the conditions of the detection target (perspiration state, degree of pressing, length of contact time in the detection system, etc.),
Alternatively, it is possible to instantly detect whether it is a non-living body.

The details of other structural features and operations of the present invention will be described with reference to the accompanying drawings and embodiments described below.

〔Example〕

FIG. 4 shows the configuration of one embodiment of the first mode (see FIG. 1) of the present invention. In the figure, (a) is a top view, (b)
(A) shows the optical system for forming a fingerprint image in the side view seen from the direction of arrow B, and (c) shows the side view seen from the direction of arrow C in (a) of the living body detection according to the present invention. The optical system for this is shown. The device illustrated in FIG. 4 constitutes a part of the fingerprint image input device in the fingerprint matching system.

In FIG. 4, 10 is a finger as a detection target (a real finger or a replica made of Si-based rubber), 11 is a sweating diode (LED) as a light source for finger illumination used when forming a fingerprint image, 12 Is a charge-coupled device (CCD) as a fingerprint image detecting device that generates an electric signal indicating the fingerprint image in response to light corresponding to the fingerprint image, and 13 is a semiconductor laser (or LED) as a light source for detecting a living body. , 14 are photodetectors of the type in which the light receiving region is divided into a plurality of parts. The output of this photodetector 14 is represented by V _L.

Reference numeral 20 denotes a transparent light guide plate, which has four oblique cut surfaces 21 to 24 cut obliquely along the cross-sectional direction thereof. A lens 21a for focusing the light beam from the semiconductor laser 13 is bonded to the oblique cut surface 21, while the oblique cut surface 22 receives the light emitted from the light guide plate 20 as a light receiving surface of the photodetector 14. A lens 22a for focusing is adhered on the top. In this case, diagonal cut faces 21 and 22
The light focused through the lens 21a repeats total reflection in the light guide plate 20, and is further reflected or scattered at the contact portion of the finger 10 with the light guide plate 20, and finally reaches the light receiving surface of the photodetector 14 through the lens 22a. As they reach, they are cut and formed facing each other. The diagonal cut surface 24 constitutes a mirror surface, and an aperture stop 25 is formed on one side surface of the light guide plate 20 facing the diagonal cut surface 24. A lens 26 for adhering the light emitted from the light guide plate 20 onto the light receiving surface of the CCD 12 is adhered to the aperture stop 25. In this case, the diagonal cut surface 24
Means that the light reflected or scattered from the finger 10 by the light irradiation from the fingerprint matching LED 11 is totally reflected on the bottom surface of the light guide plate 20,
Further, it is cut and shaped so that it is reflected by the mirror surface 24 and reaches the light receiving surface of the CCD 12 through the opening of the aperture stop 25 and the lens 26.

FIG. 5 schematically shows a partial configuration example of the photodetector in FIG.

The photodetector 14 includes a light-receiving element having a light-receiving surface 14a divided into _three light-receiving areas P ₁ , P ₂ , and P ₃ , and light-receiving areas P ₁ ,
An operational amplifier 15 that calculates the sum of the optical outputs S ₁ and S ₃ according to the amount of received light in P ₃ , and the output of the operational amplifier 15 and the optical output S ₂ according to the amount of received light in the central light receiving region P ₂ . And an operational amplifier 16 for calculating the difference between Therefore, the output V _{L of the} photodetector 14 is represented by (S ₁ + S ₃ −S ₂ ).

The portion 17 shown by hatching in the figure schematically shows an image obtained by forming the light reflected or scattered from the finger 10 by the light irradiation from the semiconductor laser 13 on the light receiving surface 14a of the photodetector. It is shown in the figure.

Next, the operation (living body detection) of the apparatus of FIG. 4 will be described with reference to FIG.

In FIG. 6, (a) and (b) are diagrams schematically showing a fingerprint of a real finger and a fingerprint of a replica, respectively.
(C) is a light intensity distribution chart along the line AA 'of the light irradiation portion corresponding to (a), and (d) is light along the line BB' of the light irradiation portion corresponding to (b). Intensity distribution chart, (e) is (a)
Is a diagram schematically showing an image on the light receiving surface 14a of the photodetector corresponding to, and (f) is a light receiving surface 14a of the photodetector corresponding to (b).
It is the figure which showed the above image typically.

When the finger 10 is a real finger, as described above, the light-irradiated portion shines due to reflection, and the irradiation light propagates and diffuses inside the finger and is reflected or scattered inside. As a result, the peripheral area around the light irradiation point also shines. That is, flare occurs as shown by the broken line F in (c). As a result, the light receiving surface of the photodetector
The ratio of the image on 14a straddling the light-receiving regions P ₁ and P ₃ on both sides increases, as indicated by hatching in (e). As a result, the calculation result of the light detector 14, that is, the output
V _L increases to the positive side (+ side) (see FIG. 5).

On the other hand, when the finger 10 is a replica, only the very vicinity of the portion irradiated with light shines due to reflection or scattering. In other words, flare does not occur. As a result, in the image on the light receiving surface 14a of the photodetector, as shown in (f), the proportion of light incident on the central light receiving region P ₂ increases. Therefore, the output V _{L of the} photodetector 14 decreases to the negative side (− side).

In the present embodiment, the distance between the photodetector 14 and the light guide plate 20 and the positional relationship, and the size of each light receiving region P ₁ , P ₂ , P ₃ of the photodetector, the output V _{L of the} photodetector 14 is It is set so that it is a positive level when it is a real finger, and a negative level when it is a replica (see FIG. 7).

Thus, according to the apparatus of FIG. 4, the photodetector 14
It is possible to instantly determine whether the finger 10 is a real finger (living body) or a replica (non-living body) depending on whether the signal _VL output from the finger 10 is positive or negative.

In the embodiment shown in FIG. 4, the contact surface of the finger is obliquely irradiated with light and the light reflected in the oblique direction is detected. The light may be incident from directly below the surface and the light reflected immediately below may be detected.

The biometric device described above is appropriately incorporated into the fingerprint image input device in the fingerprint collation system.

The operation sequence of biometric detection and fingerprint collation when the apparatus of FIG. 4 is incorporated in the fingerprint collation system will be described below.
This will be described with reference to the flowchart of FIG.

First, in step 31, initial setting is performed. That is,
The semiconductor laser (LD) 13 for detecting a living body is turned on. As a result, the light beam emitted from the semiconductor laser 13 enters the light guide plate 20 through the lens 21a,
After the total reflection is repeated, the photodetector 1 passes through the lens 22a.
It is focused on the light receiving surface 14a of the four. Note that the optical path from the semiconductor laser 13 to the photodetector 14 shown in FIG. 4 (a) is an example, and it is understood by those skilled in the art that there are many other possible optical paths. Would be obvious.

In step 32, the detection target, that is, the finger 10 is brought into contact with a predetermined position of the light guide plate 20, and in the next step 33, it is determined whether the photodetector output level _VL is positive or negative.
This is because the well-known fingerprint matching device (not shown) is used as a photodetector 14
Is performed by determining the output level V _L of. In this case, when the photodetector output level _VL is negative, it is determined that the detection target is a non-living body (replica) (step 34), and the fingerprint collation thereafter is not performed. That is, the flow ends (end).

When the photodetector output level V _L is positive, the fingerprint collation device determines that the detection target is a living body (real finger) (step 35), and sends a control signal indicating that fact to the fingerprint image input device. (Biological detection device). In the biological detection device,
Receiving this control signal, the LED 11 for fingerprint collation is turned on (step 36). As a result, the light emitted from the LED 11 enters the light guide plate 20 through the oblique cut surface 23, is reflected on the finger contact surface, and then is shown in FIG.
Is totally reflected by the bottom surface of the light guide plate 20, as indicated by the broken line in
Further, the light is reflected by the mirror surface 24, propagates in the light guide plate 20, and is focused on the light receiving surface of the CCD 12 through the opening of the aperture stop 25 and the lens 26. In addition, in FIG.
The optical path from the CCD to the CCD 12 is an example, and many other optical paths can be considered.

In step 37, the fingerprint image input device performs a process for capturing the fingerprint image formed on the CCD 12 and converting the fingerprint image into image data. In step 38, the fingerprint collation device compares the image data with the image data of the fingerprint registered in advance, thereby collating whether or not the person is the person. In the final step 39, the system is controlled based on the fingerprint matching result. For example, in the case of a system for managing entry into a computer room or the like, system control is performed so that entry is prohibited when the collated fingerprint does not match that of the person himself / herself.

It should be noted that when the fingerprint matching LED 11 is turned on in step 36, it causes noise to the living body detection system, so it is preferable to perform the living body detection illumination and the fingerprint matching illumination in series in terms of time. . However, the biometric detection (steps 31 to 33, 35), the illumination of the finger (step 36), and the capture of the fingerprint image (step 37) are set to be performed within a short time such as within several tens of ms. by this,
It is possible to prevent fraudulent acts such as exchanging with a replica for verification after detecting a living body.

FIG. 9 shows the configuration of an embodiment of the second mode (see FIG. 2) of the present invention.

In FIG. 9, reference numeral 40 is a finger as a detection target (a real finger or a replica), 41 is a semiconductor laser (or LED) as a light source for detecting a living body, and 42 is a finger 40 for collecting a light beam from the light source 41. Condensing optical system (lens) for irradiating the surface of the finger in a spot shape, 43 is a transparent light guide plate, and 44 is a predetermined position by condensing the light reflected or scattered from the finger surface by the irradiation of the light beam. An imaging optical system (lens) for forming an image of the irradiated portion, 45a and 45b are photodetectors arranged at the predetermined positions, and 46 is a comparison circuit. This comparison circuit 46, each of the light-receiving surface Pa in the photodetector 45a, 45b,
Output Sa, S according to the amount of light incident on Pb (see Fig. 10)
It has a function of responding to b, performing comparison / collation, and outputting a detection signal V _L1 indicating whether the 40 fingers are real fingers or replicas.

Of the optical paths reflected from the contact portion of the finger in FIG. 9 and reaching the light receiving surfaces of the photodetectors 45a and 45b, the optical path indicated by the solid line is the finger 40 being a non-living body (replica). The optical path of time is shown. Also, a portion R indicated by a broken line in the finger 40
Indicates an area where light reflection or light scattering occurs due to the propagation / diffusion of the irradiation light inside the finger. Such an area is provided when the finger 40 is a living body (real finger). Occurs.
Therefore, in this case, the center of the region R is displaced from the original center position of the light irradiation portion. Therefore, the optical path that is reflected from the contact portion of the finger and reaches the light receiving surface of each of the photodetectors 45a and 45b is considerably wide in cross section as shown by the broken line.

FIG. 10 is a partial schematic diagram showing one structural example of the photodetector and the comparison circuit in FIG.

In FIG. 10, from the photodetector 45a, the light receiving surface Pa
An optical output Sa corresponding to the amount of light incident on is output and input to the comparator 46a. The comparator 46a compares the level of the input signal Sa with a preset constant level Vth, for example, Sa
When> Vth, a signal of “1” is output, and when Sa ≦ Vth, a signal of “0” is output. Similarly for the comparator 46b, the optical output Sb corresponding to the amount of light incident on the light receiving surface Pb of the photodetector 45b is compared with a predetermined level Vth, and when Sb> Vth, the signal of "1" is changed to Sb. It is configured to output a “0” signal when ≦ Vth. The output of each comparator is input to the AND gate 47.

Therefore, the AND gate 47 outputs the detection signal V _L1 of “1” only when the amount of light detected by each of the photodetectors 45a and 45b exceeds the predetermined amount (Vth), and otherwise. In this case, the detection signal V _L1 exhibits the “0” level.

The portion 48 shown by hatching in the figure schematically shows an image obtained by forming the light reflected or scattered from the finger 40 by the light irradiation on the light receiving surfaces Pa and Pb of the respective photodetectors. It is shown.

Next, the operation (living body detection) by the apparatus of FIG. 9 will be described with reference to FIG.

In FIG. 11, (a) and (b) are diagrams showing the positional relationship between the light receiving surface and the image in the case of a real finger and a replica, respectively, and (c) is the output level of each photodetector corresponding to (a). Diagram showing the relationship between Sa and Sb and threshold level Vth, (d)
FIG. 4B is a diagram showing the relationship between the output levels Sa and Sb of each photodetector and the threshold level Vth corresponding to (b). In addition,
In (c) and (d), at time t ₀ , the finger 40 moves the light guide plate 44.
Represents the point in time when touched at a predetermined position.

If finger 40 is a real finger, then
Due to the region R formed therein, the region of the light reflected or scattered from the surface of the finger is considerably spread as shown by the broken line in FIG. Therefore, the image 48 to be formed on the light receiving surface is formed over the light receiving surfaces Pa and Pb of each photodetector as shown in FIG. Therefore, each photodetector 4
From 5a and 45b, optical output Sa and S of a certain level respectively
b is obtained. In this case, if the levels of the obtained optical outputs Sa and Sb are set to be higher than the predetermined level Vth, both of the comparators 46a and 46b in FIG. 10 can output "1". Yes, and by AND gate 47 from “1”
The detection signal V _L1 is output (living body detection).

On the other hand, if the finger 40 is a replica, the area of light reflected or scattered from the surface of the finger will be fairly focused, as shown by the solid line in FIG. Therefore, the image 48 to be formed on the light receiving surface is formed on the light receiving surface Pb of one of the photodetectors as shown in (b). On the light receiving surface Pa of the other photodetector, a very small amount of light, which is about the flare of the light focused and irradiated on the light receiving surface Pb, is incident. Therefore, a certain level of optical output Sb is obtained from one photodetector 45b, and a considerably low level of optical output Sa is obtained from the other photodetector 45a. In this case, the magnitude of the predetermined level Vth is lower than the level of the optical output Sb,
Moreover, if it is set so as to be higher than the level of the optical output Sa, the detection signal V _L1 output from the AND gate 47 in FIG. 10 exhibits the “0” level. This detects that the finger 40 is a replica.

In the embodiment shown in FIG. 9, the image 48 to be formed on the light receiving surface of each photodetector is formed so as to extend over each light receiving surface when the finger is a real finger, and when the replica is used. It is necessary to configure the imaging optical system so that it is formed only on one light receiving surface. In the illustrated example, the photodetector 45b plays a role of detecting that the finger 40 (a real finger or a replica) comes into contact with the light guide plate 43, while the photodetector 45a plays a role of biometric detection.

As described above, according to the apparatus of FIG. 9, the comparison circuit 46
It is possible to instantly determine whether the finger 40 is a real finger (living body) or a replica (non-living body) depending on whether the signal V _L1 output from the device is “1” or “0”. You can Like the device of FIG. 4, the device of FIG. 9 is appropriately incorporated into the fingerprint image input device in the fingerprint matching system.

In the embodiment shown in FIG. 9, the case where the two photodetectors 45a and 45b arranged close to each other are used has been described.
Instead of this, an integrated photodetector in which the light receiving surface is divided into two regions and the light outputs corresponding to the respective regions can be separately taken out may be used.

FIG. 12 shows the configuration of an embodiment of the third mode (see FIG. 3) of the present invention.

In FIG. 12, 50 is a finger as a detection target (a real finger or a replica), 51 is a light source for living body detection such as a semiconductor laser or an LED, and 52 is a linearly polarized light beam from the light source 51 (in the example shown in the figure). A polarizing plate (however, it can be omitted when the light source 51 is a semiconductor laser) for directing light in a direction parallel to the paper surface, 53 is a finger for converging the light beam from the light source 51.
Condensing optical system (lens) for irradiating the surface of 50 in a spot shape, 54 is a transparent light guide plate, and 55 is an optical for condensing light reflected or scattered from the surface of the finger by irradiation of a light beam. The system (lens) is shown.

Further, 56a is a beam splitter for splitting the scattered light entering through the lens 55 into two light beams while preserving the polarization direction, and 56b is a direction orthogonal to the incident direction of the light beam reflected by the beam splitter 56a. A mirror for reflecting the scattered light transmitted through the beam splitter 56a in a predetermined direction (a direction perpendicular to the paper surface in the example shown in the figure), and a scattered light reflected by the mirror 56b in a predetermined direction. A polarizing plate for polarizing in a direction perpendicular to the polarizing direction of the polarizing plate 57a (in the example shown, parallel to the paper surface, and thus the same as the polarizing direction of scattered light incident through the lens 55), and 58a is a polarizing plate. 57a detects the light intensity in the direction polarized and outputs a light output Sa 'according to the light intensity, 58b detects the light intensity in the direction polarized by the polarizing plate 57b, and the light intensity According to Photodetector for outputting an output Sb ', 59 denotes a comparison circuit. This comparison circuit 59
Calculates the ratio of the light outputs Sa ′, Sb ′ output from the photodetectors 58a, 58b, compares the calculated ratio (Sa ′ / Sb ′) with a predetermined value X _0, and It has a function of outputting a detection signal V _L2 indicating whether it is a real finger or a replica.

Next, the operation (living body detection) by the device of FIG. 12 will be described with reference to FIG.

Figure 13 is a comparison of the polarization characteristics of the scattered light by the real finger and the scattered light by the replica finger, the horizontal axis represents the angle between the linear polarization direction of the irradiation light and the polarization direction of the polarizing plate, The vertical axis represents the value obtained by normalizing the output of the photodetector with the maximum output. FIG. 13 shows that the scattered light from the real finger has a better ratio of conservation of the polarization direction of the irradiation light than the scattered light from the finger of the replica. In the example shown in the figure, the polarization direction of the light source is preserved in the case of a real finger by 40 to 50%, and in the case of a replica, only about 20% at most. Therefore, by taking the ratio of the optical outputs Sa 'and Sb' output from the photodetectors 58a and 58b in the comparison circuit 59, the characteristic of the polarization disturbance is different between the real finger and the replica.

Also, as shown in FIG. 13, when the polarizing plate rotation angle is 90 °, between the normalized photodetector output corresponding to the replica (displayed by the solid line) and that corresponding to the real finger (displayed by the broken line). Has a maximum difference. Therefore, if a predetermined value X ₀ is set within the range corresponding to this difference, the polarization of polarization is calculated based on the comparison between the ratio (Sa ′ / Sb ′) calculated in the comparison circuit 59 and the predetermined value X ₀ . The disorder characteristic can be used to detect whether the finger 50 is a real finger or a replica. In consideration of this polarization characteristic, in this embodiment, the polarization directions of the polarizing plates 57a and 57b are different by 90 °. The device of FIG. 13 is appropriately incorporated into the fingerprint image input device in the fingerprint collation system, like the devices of FIGS. 4 and 9.

 FIG. 14 shows the configuration of a modified example of the FIG. 12 embodiment.

In this embodiment, instead of the beam splitter 56a, the mirror 56b and the polarizing plates 57a, 57b used in the configuration of FIG. 12, a Wollaston prism 60 is used to configure a polarization optical system, whereby the optical The number of parts has been reduced to reduce size. For other configurations and operations, see
Since it is similar to the case of the embodiment shown in FIG. 12, its explanation is omitted.

Although the contact type fingerprint image input device (biological detection device) using the light guide plate has been described in each of the above-described embodiments, the present invention is also applicable to a non-contact type device that does not use the light guide plate. Of course.

〔The invention's effect〕

As described above, according to the present invention, when a spot-shaped light or linearly polarized light is applied to the surface of a detection target, the appearance of the surface shines or the polarization characteristics of scattered light from the light irradiation unit are changed. By utilizing the phenomenon peculiar to the human finger or by utilizing the property peculiar to a substance, it is possible to instantly determine whether the detection target is a living body or a non-living body, regardless of the conditions of the detection target. Can be detected.

Moreover, since the property peculiar to the substance is used, the security of the system against the forged fingerprint can be improved.

In addition, since the living body can be detected in a short time, the time required for the personal identification device based on fingerprint collation can be relatively shortened from the viewpoint of the entire system.

Furthermore, it can be incorporated into both a contact type and a non-contact type fingerprint collation device.

[Brief description of drawings]

FIG. 1 is a principle diagram showing a first form of a living body detection device according to the present invention, FIG. 2 is a principle diagram showing a second form of a living body detection device according to the present invention, and FIG. 3 is a living body detection device according to the present invention. FIG. 4 is a principle view showing a third embodiment of the present invention, and FIGS. 4 (a) to 4 (c) are views showing a configuration of an embodiment of the first embodiment shown in FIG. 1, and FIG. ,
(B) is a view on arrow B, (c) is a view on arrow C, FIG. 5 is a circuit diagram schematically showing a partial configuration example of the photodetector in FIG. 4, and FIG. 6 (a). (F) is a diagram for explaining the principle of living body detection by the apparatus of FIG. 4, and FIG. 7 shows the relationship between the output level of the photodetector of FIG. 5 and the discrimination level of living body / non-living body. FIG. 8 is a flow chart showing the flow of biometric detection and fingerprint collation when the apparatus of FIG. 4 is incorporated in the fingerprint collation system, and FIG. 9 is an embodiment of the second embodiment shown in FIG. The figure which shows the structure of an example, FIG. 10 is the circuit diagram which showed partially the one structural example of the photodetector and the comparison circuit in FIG. 9, and FIG. 11 (a)-(d) is FIG. FIG. 12 is a diagram for explaining the principle of living body detection by the apparatus of the embodiment, FIG. 12 is a diagram showing a configuration of an embodiment of the third mode shown in FIG. 3, and FIG. FIG. 12 is a diagram for explaining the principle of living body detection by the apparatus of the embodiment, FIG. 14 is a diagram showing a configuration of a modified example of the embodiment of FIG. 12, and FIG. 15 is a configuration of a typical fingerprint image input device. FIG. 16 is a schematic side view, FIG. 16 is a diagram for explaining one conventional method for detecting a living body, and FIG. 17 is a diagram for explaining another conventional method for detecting a living body. (Explanation of symbols) 1 ... Light source, 2 ... Focusing optical system, 2A ... Polarizing / focusing optical system, 3 ... Imaging optical system, 3A ... Focusing / polarizing optical system, 4,
4A, 4B ...... light detecting means, 5 ...... detected, light from the L ₁ ...... light _{source, L 2, L 2 ',} L 2 "...... reflected or scattered light,
L ₃ ... polarized light, J ₁ , J ₂ , J ₃ ... detection signal, R ...
Area where reflection or scattering occurs.

(72) Inventor Fumio Yamagishi 1015 Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa, Fujitsu Limited

Claims (9)

[Claims] 1. A light source (1) and a condensing optical system (2) which condenses a light beam (L ₁ ) from the light source and irradiates the surface of a detection target (5) in a spot shape.
An imaging optical system (3) for condensing light (L ₂ ) reflected or scattered from the irradiation portion of the light beam to form an image of the irradiation portion at a predetermined position; And a photodetector (4) for detecting the size of the image of the formed irradiation portion and outputting a detection signal (J ₁ ) indicating the size of the detected image. A living body detection apparatus, characterized in that it is determined whether the detection target is a living body or a non-living body based on a detection signal output from the means. 2. The light detecting means comprises a plurality of regions (P ₁ , P ₂ ,
A light detector (14) having a light receiving surface (14a) divided into P ₃ ) and arranged so that an image of the irradiated portion is formed on the light receiving surface. , Light output (S ₁ , S ₂ , S ₃ ) according to the amount of received light in each of the plurality of regions
Is independently taken out, and whether the detection target is a living body or a non-living body is discriminated according to the magnitude of the total (S ₁ + S ₃ −S ₂ ) of the respective light outputs taken out. The living body detection device according to claim 1. 3. The light detecting means comprises a plurality of light detectors arranged in close proximity to each other and arranged so that an image of the irradiated portion is formed across each light receiving surface,
The plurality of photodetectors take out the light output according to the amount of received light, and determine whether the detection target is a living body or a non-living body according to the magnitude of the total of the extracted light outputs. The living body detecting apparatus according to claim 1, wherein the living body detecting apparatus is provided. 4. A light source (1) and a condensing optical system (2) for condensing a light beam (L ₁ ) from the light source and irradiating the surface of a detection target (5) in a spot shape.
An imaging optical system (3) for condensing light (L ₂ ′) reflected or scattered from the irradiation portion of the light beam to form an image of the irradiation portion at a predetermined position, and the predetermined position Is arranged on the object to be detected and the size of the image of the formed irradiation portion is detected, and the center position (C ₁ ) of the region (R) where reflection or scattering occurs on the detection target by irradiation of the light beam is the light beam. Center position of the irradiated part (C ₂ )
From the light detecting means for detecting whether or not the light is displaced, and outputting a detection signal (J ₂ ) indicating the size of the detected image and the presence or absence of the displacement. A living body detection apparatus, wherein it is determined whether the detection target is a living body or a non-living body based on the output detection signal. 5. The light detecting means comprises a plurality of light detectors arranged so as to be close to each other and arranged so that an image of the irradiated portion is formed across each light receiving surface (Pa, Pb). The plurality of photodetectors extract light outputs (Sa, Sb) corresponding to the received light amounts, respectively, and based on a comparison between the extracted light outputs and a predetermined level (Vth), the target is a living body or a non-human body. The living body detection apparatus according to claim 4, wherein it is determined which of the living bodies is the living body. 6. The light detecting means comprises a light detector having a light receiving surface divided into a plurality of regions and arranged so that an image of the irradiated portion is formed on the light receiving surface. The photodetector independently extracts light outputs corresponding to respective light receiving amounts in the plurality of regions, and the object is either a living body or a non-living body based on a comparison between the respective extracted light outputs and a predetermined level. The living body detection device according to claim 4, wherein it is determined whether or not it is. 7. A light source (1) and polarized light for linearly polarizing and condensing a light beam (L ₁ ) from the light source and irradiating the surface of a detection target (5) in a spot shape.
A condensing optical system (2A) and condensing / polarizing optics that condense the light (L ₂ ″) reflected or scattered from the irradiated portion of the light beam and polarize the condensed light in a predetermined direction. System (3A) and a detection signal (J ₃ ) which detects the light intensity of the polarized light component of the polarized light (L ₃ ) and indicates the polarization state of the polarized light based on the detected light intensity And a light detecting means (4B) for outputting the light detecting means (4B), and it is determined whether the detection target is a living body or a non-living body based on the detection signal output from the light detecting means. Biometric detection device. 8. The condensing / polarizing optical system (3A) separates the condensed light into two light fluxes while maintaining the polarization state of the light, and with respect to one of the separated light fluxes. Takes out a first component having the same polarization direction as the light beam, takes out a second component having a polarization direction orthogonal to the light beam with respect to the other light beam, and supplies the second component to the light detecting means (4B). The detection means calculates the ratio of the first and second polarization components, and determines whether the target is a living body or a non-living body based on a comparison between the calculated ratio and a predetermined value. The living body detection device according to claim 7, wherein. 9. The biological detection device according to any one of claims 1 to 8 is provided, and the pattern of the finger is converted into image data only when the object detected by the device is a finger (35). (36, 37) and compare the converted image data with the image data of a fingerprint registered in advance to verify whether or not the user is the authentic person (38). system.