JP2557520B2 - Personal authentication device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] The present invention relates to a personal authentication device that authenticates an individual by using a physical characteristic such as a handprint or a fingerprint.

(Prior Art) Recently, a device using a fingerprint or the like has been developed as a device for authenticating an individual. In this type of personal authentication device, the input unit includes a transparent prism on which a finger or the like is placed, a light source that irradiates the finger with light through the prism, and a finger and the prism by the light irradiation from the light source. It is composed of a camera that converts a finger image obtained by the difference between contact and non-contact into an electric signal. That is, in the personal authentication device configured as described above, the light from the light source is totally reflected on the portion on the prism that is not in contact with anything, and the light is scattered on the portion on which the skin is in contact. A fingerprint image, an entire image of a finger, an image of a handprint, or the like is obtained by using the image.

However, when a fingerprint image or the like is read by contact / non-contact between the prism and the skin, nothing can be obtained as an image when the prism and the skin are not in contact. Therefore, in an actual personal authentication device, it is necessary to detect by using some means that a finger or the like is placed on the prism, that is, that image information necessary for authentication (verification) is being input. was there.

(Problems to be Solved by the Invention) As described above, in a device for reading a fingerprint image or the like by contact / non-contact between the prism and the skin, it is necessary to use some means that a finger or the like is placed on the prism. It had to be detected.

Therefore, the present invention can easily and reliably detect that a finger is placed on the finger rest, at low cost,
Moreover, it is an object of the present invention to provide a personal authentication device that is easy to use for the person to be authenticated.

[Configuration of the Invention] (Means for Solving the Problems) In the personal identification device of the present invention, a finger rest for inputting image information of a finger and image information of a finger placed on the finger rest are provided. Using the reading means for reading, the generating means for generating the characteristic information by adding the image information of the finger read by the information means in the direction orthogonal to the longitudinal direction of the finger, and the characteristic information generated by the generating means A detection unit that detects whether or not a finger is placed on the finger rest, and, when the detection unit detects that a finger is placed on the finger rest, the characteristic information output from the generation unit is output. It comprises a collating means for collating with the characteristic information stored in advance.

(Operation) The present invention determines whether or not a finger image is obtained by using the feature information, which is the addition signal of the input image information in the direction orthogonal to the longitudinal direction of the finger, to determine whether the finger image is obtained. It is configured to detect whether or not is placed on the finger rest.

(Embodiment) An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 shows a personal identification device of the present invention. In FIG. 2, reference numeral 11 denotes a finger rest on which the person to be authenticated places his or her finger F when inputting image information of the finger, and is constituted by, for example, a transparent prism. This finger rest 11
The image information of the finger F placed on the finger is read by the camera 13 as a reflected light image by irradiating the light from the light source 12 arranged below the finger stand 11 through the finger stand 11. It is like this.

The image information of the finger F input to the camera 13 is converted into an electric signal here, and then A / D converted by the A / D converter 14 to be digitized. The digitized finger image is temporarily stored in the image memory 16 by the control unit 15.

On the other hand, the IC card 17 prestores the characteristic information extracted from the finger image of each person to be authenticated. The characteristic information is, for example, an addition signal obtained by adding the image densities of the finger image in the direction orthogonal to the longitudinal direction of the finger. The IC card 17 is configured such that the reading / writing device 18 controlled by the control unit 15 writes (reads) or reads (when collating) the characteristic information. Writing device
The dictionary unit 19 in which the characteristic information of each person to be authenticated is registered in advance is constituted by 18.

The control unit 15 obtains the characteristic information of the finger F from the finger image stored in the image memory 16, and compares the obtained characteristic information with the characteristic information registered in the dictionary unit 19 (positioning), Identity verification is performed. Further, the control unit 15 confirms that the image information of the finger F is obtained by using the characteristic information obtained from the finger image at the time of the collation, that is, the finger F is placed on the finger rest 11. Whether or not it is detected. That is, only when it is detected from the feature information obtained from the input finger image that the finger F is placed on the finger rest 11, the matching process using the feature information is performed. .

The host machine 20 controls, for example, opening / closing of a door and ringing of an alarm buzzer according to the collation result from the control unit 15. The control target of the host machine 20 differs depending on the security system to which the personal authentication device is applied.

FIG. 3 schematically shows the finger image and the characteristic information (addition signal).

The image Fx is read by the camera 13,
1 is an image pattern of a finger digitized by an A / D converter 14.

The feature information A (x) is obtained by pixel density D (x, x) of the finger image Fx in the direction y perpendicular to the longitudinal direction x of the finger.
It is a one-dimensional signal obtained by adding y).

The characteristic information A (x) has a steep valley (minimum value) at the position of the lateral wrinkle corresponding to each joint portion, and this serves as a parameter (individuality) for authenticating an individual. In this embodiment, the size of the image is 512 pixels in each of the x direction and the y direction.

Next, the operation of the personal identification device having the above configuration will be described. This device is roughly divided into two categories, "registration process" and "collation process".

FIG. 4 is a flow chart for explaining the “registration process”. For example, assume that the finger F of the person to be authenticated is placed on the finger rest 11 in the registration mode. Then, the image information of the finger F is converted into an electric signal by the camera 13, further A / D converted by the A / D converter 14 and digitized, and then temporarily stored in the image memory 16 as the finger image Fx. (Step ST1).

This finger image Fx is displayed in the control unit 15 in the longitudinal direction x of the finger.
The densities D (x, y) are added in the direction y perpendicular to the vertical direction. As a result, the characteristic information A (x) is generated as shown in FIG. 3 (step ST2).

The characteristic information A (x) thus obtained is registered in the dictionary unit 19 (step ST3). That is, the characteristic information A (x) is stored in the authenticated IC card 17 via the reading / writing device 18 under the control of the control unit 15.

This completes the registration process, and the feature information A (x) regarding the finger F of the person to be authenticated is thus registered in the dictionary unit 19.

FIG. 1 is a flow chart for explaining the “collation process”. Here, first input the finger image Fx (step
ST11) and generation of the characteristic information A (x) from this finger image Fx (step ST12) are obtained by the same processing as those in the above-described registration.

When the characteristic information A (x) is obtained, the control unit 15 detects whether or not the finger F is placed on the finger rest 11 using the characteristic information A (x) (steps ST13, 14). .
In this case, for example, the sum of the amplitudes of the respective elements in the characteristic information A (x), that is, the total sum E of the addition positions corresponding to each pixel of the characteristic information A (x) in the longitudinal direction x of the finger is obtained.

Then, the sum E of the added values of the obtained feature information A (x)
Is compared with the threshold rest THe to detect whether or not the finger F is placed on the finger rest 11.

E ≧ THe ... Detecting that the finger F is placed E <THe ... Detecting that the finger F is not placed That is, the sum E of the respective additions of the characteristic information A (x) is
It changes depending on the contact / non-contact state of the finger F and the finger rest 11. As a result, the value becomes large when the finger F is placed on the finger rest 11, and becomes small when the finger F is not placed. Therefore, by setting the threshold value THe to an appropriate value in advance, the finger F on the finger rest 11 can be calculated from the sum E of the added values of the characteristic information A (x).
It is possible to detect whether or not is loaded.

As the parameter E for detecting whether or not the finger F is placed on the finger rest 11, the sum of squares of the added values of the characteristic information A (x) (sum of squares of the amplitudes of the elements) is used. You can also

Further, as the parameter E, it is also possible to use the sum of powers of the added values of the characteristic information A (x).

When the sum of squares or the sum of exponentiations of the respective added values of the characteristic information A (x) is used as the parameter E, the dynamic range of the parameter E, which is a physical quantity, can be increased, and thus the ease of detection is further improved.

Thus, in step ST14 above, the finger rest
11 When it is detected that the finger F is not placed on,
Step ST described above until it is detected that it is loaded
1 to 14 is repeated.

On the other hand, in step ST14, the finger F is placed on the finger rest 11.
When it is detected that the
The characteristic information registered in advance is read out, and the characteristic information read out from the dictionary unit 19 and the characteristic information generated from the finger image are aligned to perform collation (step ST15). That is, the feature information read from the dictionary unit 19
Ad (i), and the feature information generated from the finger image is A (i)
In addition, the characteristic information Ad (i) and the characteristic information A
When the addition result obtained by adding the squared error from the information A (i + m) obtained by shifting (i) by m over a certain range is S (m), this addition result S (m) is Is represented by In this case, the addition result S (m) is
Information A (i + m) obtained by shifting the characteristic information Ad (i) read from 19 and the characteristic information A (i) generated from the finger image by m.
Is a parameter indicating the degree of coincidence with the addition result S (m)
The smaller is, the higher the degree of agreement is. Therefore, m is changed within a certain range, and the addition result S at that time is changed.
The alignment is completed at m'when (m) becomes the smallest, that is, the value of S (m ') when the addition result S (m) becomes the smallest is taken as the collation result.

The result S (m ') of the collation thus obtained is used for the determination as to whether or not the person to be authenticated is the principal, that is, for the confirmation of the principal (step ST16). In this case, it is determined whether the person is the other person or the other person by using the result S (m ') of the collation and a threshold value TH which is an experimentally obtained reference.
Judgment is based on the size relationship with. That is, S (m ′) ≦ TH ... person S (m ′)> TH ... others As a result of this determination, if the person is determined to be the person, a coincidence signal is generated, and if it is determined to be another person, a disagreement signal is generated. Output to the host machine 20. Then, in the host machine 20, processing corresponding to the signal, for example, opening the door for the coincidence signal, sounding an alarm buzzer for the disagreement signal, etc., is applied to the security system to which the device is applied. The corresponding control is performed.

As described above, by determining whether or not the image of the finger is obtained by using the feature information that is the addition signal of the input image information in the direction orthogonal to the longitudinal direction of the finger, the finger is placed on the finger stand. It is designed to detect whether or not it is placed on top.

That is, the feature information is a set of added values of pixel densities, and using the information about the pixel densities in the feature information,
A parameter for detecting whether or not the finger is placed on the finger rest is calculated. As a result, for example, a special device such as a photocoupler for detecting the presence or absence of a finger on the finger rest, a switch for notifying that the finger is placed by the operation of the person to be authenticated, and the like can be added randomly. Without the need for special hardware configuration such as comparing the gray value of multiple arbitrary pixels on a finger image with a threshold value using an accessible image memory or complicated software processing, It becomes possible to detect whether or not an image is input by a very simple method. Therefore, it is possible to easily and surely detect whether or not the finger is placed, and it is not necessary to bother the person to be authenticated and increase the cost.

It should be noted that, in the above-described embodiment, the device for authenticating an individual by using the image information of the entire finger has been described as an example, but the present invention is not limited to this, and is applicable to a device using a fingerprint image or a handprint image, for example. is there.

Further, it is sufficient that the image information of at least one finger can be input, and therefore, the device configured to perform authentication using an image of a handprint or an arbitrary finger image included in a plurality of finger images can be used. Can also be easily applied.

Of course, various modifications can be made without departing from the scope of the invention.

[Effects of the Invention] As described above in detail, according to the present invention, it is possible to easily determine that a finger image has been input and to determine the input timing of image information without adding a special device or function. Since it is possible to automate, it is possible to easily and surely detect that a finger is placed on the finger rest, and it is possible to provide a low-cost personal authentication device that is easy for the person to be authenticated. .

[Brief description of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 is a flow chart for explaining the flow of processing at the time of collation,
FIG. 2 is a configuration diagram schematically showing an example of a personal authentication device, FIG. 3 is a diagram shown for explaining a finger image and characteristic information,
FIG. 4 is a flowchart shown to explain the flow of processing at the time of registration. 11 ... Finger rest, 12 ... Light source, 13 ... Camera, 15 ... Control section, 19 ... Dictionary section, F ... Finger.

Claims (4)

(57) [Claims] 1. A finger rest for inputting image information of a finger,
Reading means for reading the image information of the finger placed on the finger rest; generating means for adding the image information of the finger read by the information means in the direction orthogonal to the longitudinal direction of the finger to generate characteristic information; A detection unit that detects whether or not a finger is placed on the finger rest by using the characteristic information generated by the generation unit, and a case where the detection unit detects that the finger is placed on the finger rest. The personal authentication device further comprises: collating means for collating the characteristic information output from the generating means with previously stored characteristic information. 2. The individual according to claim 1, wherein the detection means compares the sum of added values of the characteristic information in the direction orthogonal to the longitudinal direction of the finger with a threshold value. Authentication device. 3. The detection means compares the sum of squares of added values in a direction orthogonal to the longitudinal direction of the finger in the characteristic information with a threshold value. Personal authentication device. 4. The detection means compares the sum of powers of addition values in the direction orthogonal to the longitudinal direction of the finger in the characteristic information with a threshold value. Personal authentication device.