JPH10234711A - Personal identification device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To collate characteristics of a finger in a short time even in a case of a person to be identified having less sweating quantity or an environment having an insufficient sweating quantity by controlling a device in such a manner as using the maximum voltage value higher than a reference voltage value for an extraction voltage in the first extraction and then gradually lowering the value in order till a prescribed number of times. SOLUTION: A timing pulse generator 17 generates a signal, which controls switching of analog switches 12a, 12b and a sample timing of a sample hold circuit 15, switches the analog switches 12a, 12b by a fall of the signal, and holds the potential difference by a rise by a sample hold circuit 15. This signal is large in a wide contact area between a finger and an electrode, and shows a steep dip in lateral wrinkles of the first and the second joint parts which have a narrow and small contact area. This projection signal collates an individual based on information registered beforehand. The maximum voltage value higher than the reference voltage is used for an extraction voltage at a first extraction and gradually lowered in order till the prescribed number of times.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a personal identification device for performing identification by utilizing a change in resistance generated in an input section due to contact with skin such as a finger or a palm.

[0002]

2. Description of the Related Art In recent years, from the importance of information security,
Interest in personal authentication devices is increasing. Among them, fingerprints are often used for personal authentication. The applicant has
A plurality of linear electrodes long in the direction perpendicular to the length direction of the finger are arranged in the length direction of the finger, and the resistance value between adjacent electrodes when the finger is pressed is sequentially read in the length direction of the finger and synthesized. A method using the obtained signal has already been proposed (JP-A-7-168).
930). According to this method, an optical system is not required, and the apparatus can be reduced in size and cost.

[0003]

In the personal authentication apparatus using the above-described method, a large amount of information can be obtained by reducing the arrangement pitch of the linear electrodes, and the matching accuracy can be improved. However, if the arrangement pitch of the linear electrodes is simply made finer, the number of electrodes and the number of corresponding switches also increase, which not only causes an increase in the size and cost of the device, but also increases the feature extraction time and the matching speed. descend.

[0004] The obtained feature extraction signal changes depending on the contact area between the finger and the linear electrode. The contact area is not simply determined by the positional relationship between the finger (sweat hole) and the electrode,
It varies greatly depending on the material and surface roughness of the electrodes and the substrate. This is because the real contact area with the finger changes due to the surface roughness, and when the surface is rough, the true contact area is small, so the collation accuracy is greatly reduced especially in winter when the amount of sweating is small or low sweating person Has been found by the present inventor. However, even if an attempt is made to increase the real contact area by smoothing the surface, the finger surface itself has irregularities, but this is not infinitely improved.Excessive smoothing conversely causes loss of material and increase in processing time. Invite.

The following facts have been found by the present inventors. That is, there is a large individual difference in the signal strength of the obtained feature extraction signal. This phenomenon largely depends on the amount of sweat from the finger surface, and a person with a small amount of sweat has a low signal intensity. When the signal strength is low, sufficient characteristic information cannot be obtained, and the matching accuracy is reduced.

[0006] Further, even for the same person, the strength of the characteristic pattern of the finger changes due to changes in physical condition and environmental changes such as temperature and humidity. A slight change can be absorbed by signal processing, but if the signal level is extremely lowered, it may not be possible to recognize the person.

Furthermore, at the start of measurement, that is, immediately after placing a finger on the sensor electrode, it has been found that sweating is generally weak and the level of a detection signal is low. Usually, the signal level is monitored so that the matching process is not started until the signal value reaches a predetermined value. However, in this case, the person to be authenticated having a small amount of sweating is restrained for a long time before the start of the verification process.

The present invention has been made on the basis of the above-described problems. A plurality of linear electrodes are arranged, and the resistance value between the electrodes when the skin of the person to be authenticated is pressed is determined in the direction in which the linear electrodes are arranged. It is an object of the present invention to provide a personal authentication apparatus that uses signals that are sequentially read and synthesized, and that enables a collation process in a short time even under conditions such as a person to be authenticated with a small amount of sweat or an environment in which a sufficient amount of sweat is not obtained.

It is another object of the present invention to prevent a characteristic extraction signal level and reproducibility from being lowered in a personal authentication apparatus of this kind so that highly accurate collation can be performed over a long period of time.

Another object of the present invention is to provide a personal identification device of this type that can achieve high matching accuracy without increasing the size of the device, increasing the cost, and lowering the matching speed.

[0011]

SUMMARY OF THE INVENTION A first aspect of the present invention is as follows.
In the personal authentication device, an input surface including a plurality of linear electrodes arranged to make contact with the skin of the person to be authenticated, and an electrical resistance between the linear electrodes obtained by contacting the skin with the input surface. An extraction circuit for extracting the characteristics of the skin from the distribution, storage means for registering the reference data of the skin, and collation for collating the measurement data obtained by the extraction circuit with the reference data Means for extracting the feature by the extraction circuit a plurality of times, and as an extraction voltage applied between the linear electrodes to extract the feature, the extraction voltage is higher than a reference voltage value during the first extraction. Control means for controlling to use the maximum voltage value and to use a voltage value sequentially reduced from the maximum voltage value until a predetermined number of extractions thereafter. To.

Here, as a desirable mode for efficient collation, it is possible to reduce the voltage value at each extraction. However, it is not always necessary to lower the voltage value for each extraction.

According to a second aspect of the present invention, in the personal authentication apparatus according to the first aspect, the control means sets the time when the extraction voltage reaches the reference voltage value as the predetermined number of times. And

According to a third aspect of the present invention, in the personal authentication device, an input surface including a plurality of linear electrodes arranged to make contact with the skin of the person to be authenticated, and the skin comes into contact with the input surface. An extraction circuit for extracting the characteristics of the skin from the distribution of the electrical resistance between the linear electrodes, a storage unit for registering the reference data of the skin, and a measurement obtained by the extraction circuit. Collating means for collating data with the reference data, temperature measuring means for measuring the temperature around the linear electrode, and an extraction voltage applied between the linear electrodes to extract the feature And control means for controlling to use a voltage value higher than a reference voltage value when the temperature measured by the temperature measuring means is lower than a threshold value.

According to a fourth aspect of the present invention, in the personal identification device, an input surface including a plurality of linear electrodes arranged to make contact with the skin of the person to be authenticated, and the skin comes into contact with the input surface. An extraction circuit for extracting the characteristics of the skin from the distribution of the electrical resistance between the linear electrodes, a storage unit for registering the reference data of the skin, and a measurement obtained by the extraction circuit. Matching means for comparing data with the reference data, wherein the input surface has a surface roughness defined by a maximum height of 0.1 to 10 μm and a ten-point average roughness. It is characterized by the following.

According to a fifth aspect of the present invention, in the personal identification device according to any one of the first to fourth aspects, the input surface including the linear electrode is disposed so as to contact the skin of a finger. It is characterized by.

According to a sixth aspect of the present invention, in the personal authentication device, an input surface including a plurality of linear electrodes arranged to make contact with the skin of the person to be authenticated, and the skin comes into contact with the input surface. An extraction circuit for extracting the characteristics of the skin from the distribution of the electrical resistance between the linear electrodes, a storage unit for registering the reference data of the skin, and a measurement obtained by the extraction circuit. And collating means for collating data with the reference data, wherein the linear electrodes are arranged at unequal intervals.

According to a seventh aspect of the present invention, in the personal identification device according to the sixth aspect, the input surface including the linear electrode is disposed so as to contact the skin of a finger, and the first joint of the finger is provided. The distance between the linear electrodes for contacting a portion extending from the second joint to the second joint is set to be smaller than the distance between the linear electrodes for contacting other portions of the finger. And

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1A to 1C are views showing the appearance of an input unit 18 of a feature extracting means 10 of a personal authentication device according to an embodiment of the present invention. As shown in FIG. 1C, which is an enlarged partial plan view, the input section 18 has an array of a large number of linear electrodes 11 arranged at a width and an interval of the order of 100 μm. The upper surface of the linear electrode 11 has an input surface 11 for contacting the skin of a typical finger as the skin of the person to be authenticated.
Functions as a. The number of the linear electrodes 11 and the length of the array of the electrodes 11 in the longitudinal direction (the direction orthogonal to the longitudinal direction of the linear electrodes 11) are usually set so that the second joint can be completely input from the tip of the finger. Is set.

The linear electrodes 11 and the output terminals 3 for connecting them to switches are composed of a large number of conductive wires 4 arranged on the insulating substrate 2. The conductive wiring 4 has a linear electrode 11
Except for the input part 18 and the output terminal part 3 which are composed of an array of the above, the coverlay (insulating layer) 5 covers the part.

The input section 18 having such a structure can be manufactured by the following method. First, a polyimide substrate 2 having a thickness of about 100 μm and a copper (Cu) foil having a thickness of about 18 μm bonded to the input section 18 is prepared. Next, using a photolithography technique, the copper foil is patterned to form a Cu layer pattern serving as a basis for the conductive wiring 4. Next, N is applied to the Cu layer pattern by electroplating.
The conductive layer 4 is formed by laminating 3 μm of the i layer and 10 μm of the Au layer. Next, a polyester film having a thickness of about 25 μm is attached as a coverlay (insulating layer) 5 on the conductive wiring 4 except for the input section 18 and the output terminal section 3.

FIG. 2 is a schematic diagram showing the input unit 18 and the extraction circuit 19 of the feature extraction means 10. Feature extraction means 10
Is to sequentially contact the input surface 11a of the linear electrode 11 with the finger of the person to be authenticated and change the resistance value of the finger surface between adjacent electrodes by switching the analog switches 12a and 12b in the length direction of the finger. read. When a finger is pressed against the n electrodes, the resistance value between the electrodes changes according to the contact area of the finger in contact between the adjacent electrodes 11.

As shown in the figure, a constant voltage power supply 13 (V0) and a reference resistor 14 (Rre) are provided between two adjacent electrodes 11.
f) are connected via analog switches 12a and 12b. Here, assuming that the i-th inter-electrode resistance is R (i), the potential difference V (i) between both ends of the reference resistance 14 (Rref) at this time is given by the following equation.

[0024]

(Equation 1)

By switching the analog switches 12a and 12b, the potential difference is sequentially read in the length direction of the finger. Then, the A / D converter 1 is passed through the sample hold circuit 15.
6 to convert to a digital signal.

The timing pulse generator 17 generates a signal for controlling the switching of the analog switches 12a and 12b and the sample timing of the sample and hold circuit 15. The signal is, for example, as shown in FIG. The analog switches 12a and 12b are switched at the fall of the signal,
Expression (1) by the sample hold circuit 15 at the rising edge
Hold the potential difference V (i).

The signal V (i) obtained in this way is, for example, as shown in FIG. V (i) increases in a portion where the contact area between the finger and the electrode is large. Since the contact area is small at the side wrinkles at the first joint portion and the second joint portion, V (i)
Indicates a small and steep dip. This V (i) is called a projection signal, and personal verification is performed based on this signal and information registered in advance.

FIG. 5 is a diagram showing the overall configuration of the personal authentication device according to the present embodiment. As shown in the figure, the personal authentication device includes a feature extraction unit 10, a storage unit 20, a control unit 30,
It has a host computer 40 and transmission means 50.

As described above, the feature extracting means 10 includes the input section 18 having the array of the linear electrodes 11 and the extracting circuit 19. The feature extracting means 10 extracts a feature of the finger from the distribution of resistance between the electrodes when the finger of the person to be authenticated is contacted along the arrangement direction of the linear electrodes 11.

The storage means 20 has an IC card 21 and a read / write device 22 for writing a projection signal of each person to be authenticated to the IC card 21 and reading it from the IC card 21.

The control means 30 performs a calculation for judging the state of placing the finger based on the extracted characteristic data of the finger extracted by the characteristic extraction means 10 and the data recorded in the storage means 20.
Further, the control unit 30 registers the extracted feature data extracted by the feature extracting unit 10, and stores the extracted feature data and the storage unit 2.
Authentication processing such as collation with reference data of the person to be authenticated stored in advance at 0 is performed.

The host computer 40 inputs the password of the person to be authenticated, and transmits the judgment result and message made by the control means 30 to the person to be authenticated via the transmitting means 50 including a display and a sound output device. , GUI
(Graphical User Interface
s).

First, the person to be authenticated inputs the password set in the personal information file to the host computer 40 in order to call the personal information file storing the reference characteristic data of the finger to be collated from the storage means 20. After the personal information file called out through the control means 30 is confirmed, the transmission means 5 is transmitted through the host computer 40.
From 0, finger placement is instructed by animation.

When a finger whose signal is to be detected is brought into contact with the linear electrode 11 along the array according to the instruction, the extraction circuit 19 determines the resistance value of the finger surface between the adjacent electrodes in the length direction of the finger by analog switches 12a, 12b. To read sequentially,
The signal is recorded in the storage means 20 as a feature extraction signal. Next, the arrangement interval information of the linear electrodes 11 previously input to the storage unit 20 is referred to, and the control unit 30 performs software correction of the extraction signal as necessary. Specifically, if there is a difference between the electrode intervals, the extraction signal is corrected using the difference as a parameter so that the applied voltage per unit length becomes constant.

The control means 30 further determines how to place the finger from the corrected feature extraction signal, and if there is an inadequate place, places the finger on the person to be authenticated via the host computer 40 and the transmission means 50. Instruct the person to correct. For example, when the position in the length direction of the finger is shifted, the first joint and the second joint
It is instructed that the middle part of the joint with the center part in the arrangement direction of the linear electrodes 11 coincides with each other, and the operation is repeated until the finger reaches a predetermined position. If there is no insufficient part, proceed to the next step.

The IC card 21 has the configuration shown in FIG. That is, a control element (eg, CPU) 11 as a control unit
1: Non-volatile data memory 11 whose storage contents can be erased
2, working memory 113, program memory 11
4; and a contact portion 115 for obtaining electrical contact with the read / write device 22. Among these, the portions within the broken lines (control element 111, data memory 112, working memory 113, program memory 1
14) is composed of one (or more) IC chip and is embedded in the IC card body.

The data memory 112 is used for storing various data, and is composed of, for example, an EEPROM.
It stores a program of the control element 111 and the like. The data memory 112 includes, for example, as shown in FIG.
It is divided into a control area 112-0, a directory 112-1, an empty area 112-2, and a plurality of area groups 112-3. Each area is stored in the directory 112-1.
Is managed by As shown in FIG. 8, this directory is configured as a set of area definition information including an area number 121 of each area, a head address 122 of the area, a size 123, and a check code 124. For example,
The head address 122 of the area [01] is an aaa address,
The size of the area corresponds to Sa byte.

Now, there are the following two types of access commands for these areas. One is a command for reading data in the area. As shown in FIG. 9, the command includes a function code indicating the read command and the number of the area to be accessed. the other one is,
This is a command for writing data in the area.
As shown in (1), it is composed of the number of the area to be accessed and the write data.

The operation concept of the IC card will be described with reference to FIG. As shown, after the IC card is electrically activated, the IC card shifts to a command waiting state. At this time, the command is kept waiting, and when it is input, the area number in the command is extracted and it is checked whether or not the corresponding area number exists in the directory. If not, a code indicating that there is no corresponding area is output, and the process returns to the command waiting state. If there is, processing is performed in each command routine corresponding to the function in the command input thereafter, and after the processing result is output, the processing returns to the instruction data waiting state.

In the present embodiment, the IC card 21 is exemplified as a device for performing data management. However, the housing configuration is not limited to a card shape, but may be variously changed such as a bar shape and a block shape.
Also, the present invention is applicable without being limited to a portable electronic device. Also, the configuration content can be variously changed without departing from the gist of the present invention. Although the IC card 21 of the present embodiment particularly uses a contact portion for data transfer with an external device, the IC card 21 does not contact the external device using, for example, light / electric field / magnetic field. May be used.

Next, the flow of processing will be described. The processing is roughly classified into “registration” and “collation”. First, registration will be described. FIG. 12 shows the flow of the registration process.

First, the projection signal V (i) is fetched (step ST1). Next, the projection signal fetched in step ST1 is registered as a dictionary signal Vd (i) in the IC card 11 (step ST2). Thus, the registration process ends.

Next, the flow of the collation processing is shown in FIG. First, a projection signal V (i) is captured (step ST3). Next, the dictionary Vd (i) and the projection signal V extracted in step ST3
A collation calculation with (i) is performed (step ST4).

The collation is realized by calculating the difference E by the following procedure. First, the projection signal read from the IC card 11 is aligned with the dictionary signal Vd (i) and the projection signal V (i) obtained from the input finger image. Vd (i)
S (m) is the sum of the square errors of V (i + m) shifted by m and m over a certain range.

[0045]

(Equation 2)

[0046]

(Equation 3)

S (m) is a parameter indicating the degree of coincidence between V (i + m) and Vk (i), and the smaller the value of S (m), the higher the coincidence. In the alignment, m is changed in a certain range, and M when the value of S (m) becomes the smallest is referred to as a positional shift amount. It is assumed that the alignment is performed at this M. Next, the difference E is calculated as follows.

[0048]

(Equation 4)

[0049]

(Equation 5)

E in the equations (4) and (5) is the sum of the square error between the aligned input signal V (i + M) and the dictionary signal Vd (i) over a certain range. This is normalized by the sum of squares of the dictionary signal Vd (i). E is the aligned input signal V (i + M) and dictionary signal Vd (i)
The greater the value of E, the greater the difference between the two signals, and the smaller the value, the more similar the two signals.

Next, E is compared with a predetermined threshold value TH (step ST5). If E ≦ TH, it is determined that the user is the person (step ST6), and the process is terminated. Otherwise, it is determined to be another person (step ST7), and the process ends. [Embodiment 1] As the linear electrode 11 of the feature extracting means 10 having the structure described with reference to FIG. 1, an electrode having a predetermined surface roughness on an input surface 11a with which a finger contacts is used. Examined. In the experiment, the maximum height and ten-point average roughness of the input surface of the linear electrode 11 were 0.1 μm, 0.5 μm, 5 μm, 10 μm and 2 μm.
Five samples of 0 μm were made.

More specifically, for each sample, as described above, first, a Ni layer and a Au layer were laminated by 3 μm and 10 μm on a Cu layer pattern by electroplating, and a plurality of lines having a plane width and an interval of 100 μm were formed. The conductive wiring 4 including the electrode 11 was formed. Next, for the samples having the maximum height and the ten-point average roughness of 5 μm, 10 μm, and 20 μm, the linear electrode 11 was formed using # 1500, # 600, and # 240 alumina abrasive grains, respectively. The surface was final lap polished. For samples having a maximum height and a ten-point average roughness of 0.1 μm and 0.5 μm, the surface of the linear electrode 11 was lapped and polished, and then # 8, respectively.
Polishing was performed using # 000 and # 4000 alumina abrasive grains.

Using the five samples thus prepared, 1,000 people were collated according to the registration and collation processing described with reference to FIGS. Table 1 shows the relationship between the maximum height and the ten-point average roughness, which indicate the degree of surface roughness, obtained by this experiment, and the personal recognition rate verified by contact with a finger. Here, the stranger exclusion rate was fixed at 99%.

[0054]

[Table 1]

As shown in Table 1, when the maximum height and the ten-point average roughness were between 0.1 μm and 10 μm, a good identity recognition rate of 89% or more was obtained. In a sample having a maximum height and a ten-point average roughness of 1.0 μm or less, the recognition rate slightly increases as the surface becomes smoother. Was. On the other hand, in a sample having a maximum height and a ten-point average roughness of 10 μm or more, the personal recognition rate tended to decrease sharply as the surface became rough.

The reason for obtaining such a result is as follows.
The linear electrode 11 has a maximum height and a ten-point average roughness of 0.1 μm.
It is considered that by using an electrode having a surface roughness of m to 10 μm, a good contact state was obtained between the electrode 11 and the sweat of the finger, and the loss of characteristics during low sweating could be prevented. . [Embodiment 2] As an array of the linear electrodes 11 of the feature extracting means 10 having the structure described with reference to FIG. 1, an array in which the distance between the electrodes 11, that is, the distance between the input surfaces 11a is not constant, as shown in FIG. Used and examined its effects.

More specifically, from the vicinity of the first joint to the second joint
The linear electrodes 11 near the joint were arranged at intervals of 100 μm, and the other linear electrodes 11 were arranged at intervals of 200 μm. As described above, the interval between the linear electrodes 11 is set when the copper foil on the polyimide substrate 2 is patterned by using the photolithography technique to form a Cu layer pattern serving as the basis of the conductive wiring 4. .

FIGS. 12 and 13 show a sample of the present embodiment fabricated in this manner and a comparative sample which is the same as the sample of the present embodiment except that the interval between the linear electrodes 11 is 100 μm. According to the registration and collation processing described with reference to, collation of 1,000 persons was performed. Table 2 shows the personal recognition rate and the feature extraction time obtained by this experiment, which were collated by finger contact. Here, the exclusion rate is 99%
It was fixed.

[0059]

[Table 2]

As shown in Table 2, the feature extraction time was the same for both the sample of the present embodiment and the comparative sample, but the identity recognition rate was higher for the sample of the present embodiment. From this fact, it can be seen that if the identity recognition rate is the same, the feature extraction time can be reduced by omitting the extra electrodes and performing detection.

As described with reference to FIG. 5, the correction of the feature extraction signal when the arrangement intervals of the linear electrodes are unequal can be processed by software. Alternatively, the correction can be made by adjusting the extraction voltage to be constant according to the arrangement interval of the electrodes. Specifically, the power supply 13
A programmable power supply can be controlled by software and used. Further, a plurality of constant voltage sources can be used, or a plurality of constant voltage elements such as a Zener diode and a three-terminal regulator can be used, and these can be switched by a switch.

The displacement of the finger can be calculated by the control means 30 based on the feature extraction signal and the reference signal registered in advance, and can be corrected by the person to be authenticated via the host computer 40 and the transmission means 50. Instead, a finger-shaped finger position mark 7 can be printed on the input unit 18 as shown in FIG. With this configuration, the person to be authenticated does not get lost in the place where the finger is placed, and the loss time due to the correction of the finger position can be omitted. In addition, as shown in FIG.
The recess 8 may be formed at a position slightly recessed from the surroundings, that is, in the recess 8. In this case, since the approximate positioning can be performed only by the touch of the finger, the collation becomes easy.

In the second embodiment, an example has been described in which feature extraction is performed by simultaneously using all the electrodes 11 formed in advance. However, the electrodes are formed evenly at finer electrode intervals than in the second embodiment, and the electrodes 11 are formed. A method is also conceivable in which unnecessary electrodes 11 are omitted when switching between the two. In this case, although there is an increase in the size and cost of the feature extraction means 10, the feature extraction is performed by omitting the electrode 11 in a region where the feature does not appear significantly.
A higher matching accuracy than in the second embodiment can be obtained. Further, in this case, in the array direction of the electrodes 11, the feature can be extracted regardless of where the finger is in contact, so that the influence of the displacement is small, and the burden on the person to be verified by the finger positioning operation is reduced. Can be shortened.

FIG. 17 is a schematic diagram showing the feature extracting unit 10 of the personal authentication device according to another embodiment of the present invention. The components other than the feature extracting unit 10 have the same configuration as that described with reference to FIGS. In FIG. 17, members corresponding to members in FIG. 2 are denoted by the same reference numerals, and detailed description thereof will be omitted.

The feature of this embodiment resides in that a plurality of voltage dividing resistors are connected in parallel with the power supply 13, and an analog switch 12c is connected between the voltage dividing resistors. For example, as shown in the figure, the voltage of the power supply 13 is set to a maximum voltage value V1 = 12 V,
Seven voltage dividing resistors having a resistance value R and one having a resistance value 5R are used. By sequentially switching each voltage dividing resistor, the extraction voltage V applied to the array of
It can be switched from V to 5V at 1V intervals.

FIG. 18 shows an example of control of the extraction voltage.
Assuming that the number of times of scanning the m electrodes is n, the analog switch 12c is controlled, and the highest voltage value V1 = 12V is applied to each electrode in the scan where n = 1 at the start of measurement. After n = 2, the analog switch 12c is switched to sequentially decrease the extraction voltage V by 1V. When n = 8, the extraction voltage V becomes the reference or lower limit voltage value of 5V. n> 8
In the subsequent scanning, the extraction voltage is kept constant at 5V.

In this manner, the characteristic pattern V (i) at the start of the measurement has a sensitivity that is 12/5 times higher than that obtained after n ≧ 8 according to the equation (1). .., 6/5 times sequentially from the second time. Normally, one scan is about 0.1 sec, and the reference or steady voltage value V2 = 5 V is reached 0.8 sec after the start of measurement in eight scans. However, the switching timing of the analog switch 12c is adjusted so that the steady-state voltage V2
If the time until the voltage reaches 5V is set to about 1 to 2 seconds, a good signal can be obtained even for a person to be authenticated having a considerably low sweating amount.

In the above description, the analog switch 12c
Was controlled based on the number of scans from the start of measurement. However, the timing for switching the analog switch 12c can be controlled based on the temperature. For example, in a normal measurement, the steady voltage value V2 = 5
V may be set in advance, and the voltage applied to the electrode 11 may be increased by switching the analog switch 12c only when the ambient environment or the temperature of the finger of the person to be measured is low.

For this reason, for example, as shown by a dashed line in FIG. 1A, the temperature sensor 6 is buried in a part, a plurality of parts or the whole of the electrode gap of the array of the linear electrodes 11 and the finger placed thereon is placed. Detect the temperature of When the temperature measured by the temperature sensor 6 is lower than the threshold temperature T, the analog switch 12c is switched to apply the maximum voltage value V1 = 12V. By doing so, it is possible to measure a good feature pattern even for a person to be authenticated in a state where the body temperature is low and sweating is difficult in a cold region or the like.

The control mechanism of the extraction voltage V is not limited to the circuit shown in FIG. 17. For example, a method of switching a plurality of power supplies, connecting an amplifier, and adjusting the gain by changing the gain is used. However, the same effect can be obtained.

In the embodiment of the present invention described with reference to FIGS. 1 to 18, in order to facilitate understanding,
Each feature is described separately, but these features
Any combination can be used as needed.

[0072]

According to the present invention, personal authentication using a signal in which a plurality of linear electrodes are arrayed and the resistance value between the electrodes when the skin of the person to be authenticated is pressed is sequentially read in the direction of electrode arrangement and synthesized. The device uses a voltage value higher than the reference voltage value as the extraction voltage depending on the conditions, so that verification can be performed in a short time even under conditions such as an authenticated person with a small amount of sweat or an environment where a sufficient amount of sweat cannot be obtained. Processing can be performed.

Further, according to the present invention, in this kind of personal authentication device, by giving a predetermined surface roughness to the linear electrode, it is possible to prevent the characteristic extraction signal level and the reproducibility from being lowered, and to provide a long-term operation. It is possible to perform high-precision matching.

Further, according to the present invention, in this type of personal authentication device, by arranging the linear electrodes at unequal intervals, the size of the device is increased, the cost is increased, and the collation speed is decreased. And high matching accuracy can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing an appearance of an input unit of a feature extracting unit of a personal authentication device according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing an input unit and an extraction circuit of a feature extraction unit.

FIG. 3 is a diagram showing the timing of sample and hold in a feature extraction unit.

FIG. 4 shows a potential difference V between electrodes obtained by a feature extracting means.
The figure which shows the example of the projection signal of (i).

FIG. 5 is a diagram showing an overall configuration of a personal authentication device.

FIG. 6 is a diagram showing a configuration of an IC card.

FIG. 7 is a diagram showing a configuration of a data memory.

FIG. 8 is a diagram showing an example of area definition information.

FIG. 9 is a configuration diagram of an access command.

FIG. 10 is a command configuration diagram for writing data.

FIG. 11 is a diagram showing an operation concept of the IC card.

FIG. 12 is a diagram showing the flow of a registration process.

FIG. 13 is a diagram showing a flow of a matching process.

FIG. 14 is a diagram showing an embodiment of an input unit of a feature extraction unit.

FIG. 15 is a diagram showing a modified example of the input unit of the feature extraction unit.

FIG. 16 is a diagram showing another modification of the input unit of the feature extraction unit.

FIG. 17 is a schematic diagram showing an input unit and an extraction circuit of a feature extraction unit of a personal authentication device according to another embodiment of the present invention.

FIG. 18 is a view for explaining an example of control of an extraction voltage in the feature extraction means shown in FIG. 17;

[Explanation of symbols]

2 ... substrate, 3 ... output terminal part, 4 ... conductive wiring, 5 ... coverlay, 6 ... temperature sensor, 7 ... finger position mark, 8 ... dent
DESCRIPTION OF SYMBOLS 10 ... Feature extraction means, 11 ... Linear electrode, 11a ... Input surface, 12a, 12b, 12c ... Analog switch, 13
... power supply, 14 ... reference resistance, 15 ... sample and hold circuit, 16 ... A / D converter, 17 ... timing pulse generator, 18 ... input unit, 19 ... extraction circuit, 20 ... storage means,
21: IC card, 22: read / write device, 30
... Control means, 40 ... Host computer, 50 ... Transmission means, 111 ... Control element, 112 ... Data memory, 120
-0: control area, 112-1: directory, 112-
2: free area, 112-3: plural area groups, 113:
Working memory 114, Program memory 115
... contact part, 121 ... area number, 122 ... area start address, 123 ... size, 124 ... check code.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hideo Ando 70, Yanagicho, Kawasaki-shi, Kanagawa Prefecture Inside the Toshiba Yanagicho Plant (72) Inventor Motohiko Takeuchi 8 Shinsugita-cho, Isogo-ku, Yokohama-shi, Kanagawa Prefecture Stock Company. (72) Inventor Kenichi Ide 70, Yanagicho, Saiwai-ku, Kawasaki-shi, Kanagawa Prefecture

Claims (7)

[Claims] 1. An input surface including a plurality of linear electrodes arranged to contact the skin of a person to be authenticated, and an electric resistance between the linear electrodes obtained by contacting the skin with the input surface. An extraction circuit for extracting the characteristics of the skin from the distribution of; a storage unit for registering the reference data of the skin; and a collation for collating the measurement data obtained by the extraction circuit with the reference data. Means, and the extraction of the feature by the extraction circuit is repeated a plurality of times, and the extraction voltage applied between the linear electrodes to extract the feature is higher than a reference voltage value at the time of the first extraction. Control means for controlling to use the maximum voltage value and to use a voltage value whose value is sequentially reduced from the maximum voltage value until a predetermined number of subsequent extractions,
A personal authentication device, comprising: 2. The personal authentication apparatus according to claim 1, wherein said control means sets a point in time when said extraction voltage reaches said reference voltage value as said predetermined number of times. 3. An input surface including a plurality of linear electrodes arranged so as to contact the skin of a person to be authenticated, and an electric resistance between the linear electrodes obtained by contacting the skin with the input surface. An extraction circuit for extracting the characteristics of the skin from the distribution of; a storage unit for registering the reference data of the skin; and a collation for collating the measurement data obtained by the extraction circuit with the reference data. Means, a temperature measuring means for measuring a temperature around the linear electrode, and a temperature measured by the temperature measuring means as an extraction voltage applied between the linear electrodes to extract the feature. Control means for controlling to use a voltage value higher than the reference voltage value when the voltage is lower than the threshold value. 4. An input surface including a plurality of linear electrodes arranged so as to contact the skin of a person to be authenticated, and an electric resistance between the linear electrodes obtained by contacting the skin with the input surface. An extraction circuit for extracting the characteristics of the skin from the distribution of; a storage unit for registering the reference data of the skin; and a collation for collating the measurement data obtained by the extraction circuit with the reference data. Means, wherein the input surface has a surface roughness defined by a maximum height of 0.1 to 10 μm and a ten-point average roughness. 5. The personal authentication apparatus according to claim 1, wherein the input surface including the linear electrode is disposed so as to contact the skin of a finger. 6. An input surface including a plurality of linear electrodes arranged to make contact with the skin of a person to be authenticated, and an electric resistance between the linear electrodes obtained by contacting the skin with the input surface. An extraction circuit for extracting the characteristics of the skin from the distribution of; a storage unit for registering the reference data of the skin; and a collation for collating the measurement data obtained by the extraction circuit with the reference data. Means, wherein the linear electrodes are arranged at unequal intervals. 7. The input surface including the linear electrode is arranged to contact the skin of a finger, the input surface of the linear electrode for contacting a portion of the finger from a first joint to a second joint. The personal authentication device according to claim 6, wherein an interval is set to be smaller than an interval between the linear electrodes for contacting other parts of the finger.