JP4943807B2 - Impedance detection device, impedance detection method, biometric recognition device, and fingerprint authentication device - Google Patents

Description

  The present invention relates to an impedance detection technique, and in particular, an impedance detection technique for applying a predetermined signal to a living body as a subject and detecting the impedance of the living body based on the obtained response signal, and the impedance detection technique. The present invention relates to a technique for performing biometric recognition, and further relates to a fingerprint authentication technique for performing fingerprint authentication using this biometric recognition technique.

  Along with the progress of the information society, technology for maintaining confidentiality of information processing systems has been developed. For example, an ID card has been conventionally used for entrance / exit management of a computer room or the like, but there is a high possibility that the ID card is lost or stolen. For this reason, a personal recognition system is being introduced in which fingerprints of individual persons are registered in advance instead of ID cards and collated when entering a room. In some cases, such a personal recognition system can pass a test if a replica of a registered fingerprint or the like is created. Therefore, the personal recognition system needs to recognize not only the fingerprint verification but also that the subject is a living body.

Conventionally, as a technique for detecting that a subject is a living body, a technique using an impedance detection technique that applies a predetermined signal to the subject and detects the impedance of the subject based on the obtained response signal. It has been proposed (see, for example, Patent Document 1).
FIG. 19 is a block diagram showing a configuration of a conventional biometric recognition apparatus. The biological recognition apparatus includes a detection unit 1, a supply signal generation unit 2, a response signal generation unit 3, a waveform information detection unit 4, and a biological recognition unit 5 as main functional units.

  The detector 1 is in electrical contact with the subject 9 and connects the reactance component and resistance component of the impedance Zf of the subject 9 to the response signal generator 3. When the subject 9 is a living body, the reactance component (imaginary component) of the impedance Zf of the subject 9 is mainly composed of a capacitive component. In the following description, it is assumed that the reactance component of the subject 9 is a capacitive component.

The supply signal generation unit 2 generates a supply signal including a sine wave having a predetermined frequency and outputs the supply signal to the response signal generation unit.
The response signal generation unit 3 includes a resistance element Rs connected between the supply signal generation unit 2 and the detection unit 1, and the supply signal 2S from the supply signal generation unit 2 is applied as an application signal via the resistance element Rs. 1S is applied to the detection unit 1 from one end of the resistance element Rs, that is, the connection point between the resistance element Rs and the detection unit 1, depending on the impedance Zf of the detection unit 1, here the capacitance component and resistance component of the impedance of the subject 9 The changing response signal 3S is output to the waveform information detection unit 4.

The waveform information detection unit 4 detects a phase difference or amplitude from the supply signal 2S from the waveform indicated by the response signal 3S from the response signal generation unit 3, and a detection signal 4S including waveform information indicating the phase difference or amplitude. Is output to the biometric recognition unit 5.
The living body recognition unit 5 recognizes and determines whether or not the subject 9 is a living body based on the waveform information included in the detection signal 4S from the waveform information detection unit 4, and outputs the recognition result 5S.

The operation of the biological recognition apparatus is as follows.
First, when the subject 9 comes into contact with the detection unit 1, the applied signal 1 </ b> S applied to the detection unit 1 based on the supply signal 2 </ b> S from the supply signal generation unit 2 has an impedance characteristic, that is, a capacitance unique to the subject 9. This varies depending on the component and the resistance component, and this is output from the response signal generator 3 as the response signal 3S. A phase difference or amplitude of the response signal 3S is detected by the waveform information detection unit 4, and a detection signal 4S including information indicating the detection result is output to the living body recognition unit 5.

In the living body recognition unit 5, whether or not the subject 9 is a living body is determined based on whether or not the waveform information included in the detection signal 4S from the waveform information detection unit 4 is within the reference range of the legitimate living body waveform information. Is recognized and the recognition result 5S is output.
Note that the magnitude of the reactance component and resistance component of the impedance of the subject may be calculated from these phase differences and amplitudes and compared with the reference range of the reactance component and resistance component of a legitimate living body. In this case, the impedance of the subject in contact with the detection element is detected.

  Next, a specific method for detecting a phase difference will be described with reference to FIG. 20 as a conventional technique for detecting impedance information of a subject in a living body recognition apparatus. FIG. 20 is a block diagram showing a specific configuration of a conventional impedance detection apparatus for detecting a phase difference, and the same or equivalent parts as those in FIG.

In FIG. 20, the detection unit 1 is provided with a detection electrode 11 and a detection electrode 12 for making electrical contact with the subject 9.
The supply signal generation unit 2 is provided with a frequency generation circuit 21 and a waveform shaping circuit 22. The response signal generation unit 3 is provided with a current-voltage conversion circuit 31. The waveform information detection unit 4A is provided with an offset correction circuit 41, a reference signal generation circuit 42, and a phase comparison circuit 43. The biometric recognition unit 5 (not shown) is provided with a signal conversion circuit and a determination circuit.

  In the detection unit 1, the detection electrode 11 is connected to a fixed potential such as a ground potential, and the detection electrode 12 is connected to the output stage of the current-voltage conversion circuit 31 of the response signal generation unit 3. In the supply signal generation unit 2, the frequency generation circuit 21 generates a clock signal 21S having a predetermined frequency, and the waveform shaping circuit 22 generates a supply signal 2S composed of a sine wave or the like based on the clock signal 21S from the frequency generation circuit 21. Output.

  The current-voltage conversion circuit 31 of the response signal generation unit 3 includes a resistance element Rs connected between the supply signal generation unit 2 and the detection unit 1, and has a predetermined output impedance that is sufficiently lower than the impedance of the living body. The supply signal 2S is applied to the subject 9 as the application signal 1S, and the current flowing through the subject 9 through the detection unit 1 at that time is converted into a voltage and output as a response signal 3S.

  The offset correction circuit 41 of the waveform information detection unit 4A corrects the offset generated in the response signal according to the resistance component of the subject 9, that is, the potential difference between the center voltage of the response signal 3S and the reference potential, and performs phase comparison as the signal to be compared 41S. Output to the circuit 43. The reference signal generation circuit 42 outputs a reference signal 42S synchronized with the supply signal 2S to the phase comparison circuit 43. The phase comparison circuit 43 compares the phase of the signal to be compared 41S and the reference signal 42S, thereby detecting the impedance characteristic unique to the subject 9, in this case, the phase difference corresponding to the reactance component, as waveform information, and the waveform A detection signal 4AS including information is output.

The operation of the impedance detection apparatus of FIG. 20 is as follows.
First, the subject 9 is connected to the output stage of the current-voltage conversion circuit 31 via the detection electrode 11 and the detection electrode 12 of the detection unit 1. Here, the impedance inherent to the subject 9 can be represented by a reactance component (mainly a capacitive component) and a resistance component connected between the detection electrode 11 and the detection electrode 12 of the detection unit 1. Therefore, the applied signal 1S applied with a predetermined output impedance from the current-voltage conversion circuit 31 is divided by the output impedance of the current-voltage conversion circuit 31 and the impedance unique to the subject 9. The phase or amplitude of the current flowing through the subject 9 changes according to the impedance inherent to each subject 9, and the change is output as a response signal 3S converted into a voltage.

  FIG. 21 is an example of a signal waveform in each part of the impedance detection apparatus of FIG. In the waveform shaping circuit 22 of the supply signal generation unit 2, a supply signal 2S having a center voltage VA that is a substantially intermediate potential between the operation power supply potential VDD and the ground potential (0V = GND) of the circuit is generated, and the subject 9 is used as the application signal 1S. To be applied. The response signal 3S is a signal including an offset due to the resistance component of the subject 9. For example, when the resistance component is larger than a predetermined value, VB2 higher than the reference potential VB becomes the center voltage, and when the resistance component is smaller than the predetermined value, VB1 lower than the reference potential VB becomes the center voltage. At this time, the offset correction circuit 41 is level-shifted so that the center voltage of the response signal 3S matches the reference potential VB used in the phase comparison circuit 43, and outputs the compared signal 41S with the offset corrected. The phase comparison circuit 43 outputs a waveform having a pulse width corresponding to the phase difference between the signal to be compared 41S and the reference signal 42S as the detection signal 4AS. This pulse width includes waveform information as a phase difference.

Next, with reference to FIG. 22, a specific method for detecting amplitude will be described as another technique for detecting impedance information of a subject in the living body recognition apparatus. FIG. 22 is a block diagram showing a specific configuration of a conventional impedance detection device for detecting amplitude, and the same or equivalent parts as those in FIG. 19 are given the same names.
The configurations of the detection unit 1, the supply signal generation unit 2, and the response signal generation unit 3 in FIG. 22 are the same as those in FIG. 19 described above, and a detailed description thereof is omitted here.

  The waveform information detection unit 4B detects the amplitude of the response signal 3S by comparing the peak voltage value of the response signal 3S with the center voltage value. The waveform information detection unit 4B includes a peak voltage detection circuit 44, a center voltage detection circuit 45, and a voltage comparison circuit 46. The peak voltage detection circuit 44 detects the peak voltage value 44S from the response signal 3S. The center voltage detection circuit 45 detects the center voltage value 45S from the response signal 3S. The voltage comparison circuit 46 detects the amplitude of the response signal 3S from the voltage difference by comparing the peak voltage value 44S and the center voltage value 45S, and outputs a detection signal 4BS including the amplitude as waveform information.

  FIG. 23 is an example of a signal waveform in each part of the impedance detection apparatus of FIG. In the waveform shaping circuit 22 of the supply signal generation unit 2, a supply signal 2S having a center voltage VA that is a substantially intermediate potential between the circuit operation power supply potential VDD and the ground potential (0V = GND) is generated and output to the subject 9. Applied. The response signal 3S is a signal including an offset due to the resistance component of the subject 9. A peak voltage value 44S and a center voltage value 45S (VB) of the response signal 3S are detected and compared by the voltage comparison circuit 46, thereby outputting a voltage value corresponding to the amplitude of the response signal 3S as the detection signal 4BS. . This voltage value includes waveform information as amplitude. The peak voltage value 44S may be the maximum voltage value or the minimum voltage value of the response signal 3S.

Conventionally, there has been proposed a surface shape recognition sensor device configured by adding a function of detecting that a subject is a living body to a fingerprint sensor device (see, for example, Patent Document 1).
FIG. 24 is an external view of the surface shape recognition sensor device. This surface shape recognition sensor device detects, for example, the surface shape of a subject in a surface shape recognition device that authenticates a subject by comparing and collating the shape of the surface to be collated with a subject having fine irregularities with the collation data. Used as a circuit device.

As shown in FIG. 24, the surface shape recognition sensor device 150 includes a detection unit 1 in which a large number of fine detection elements arranged in a two-dimensional manner (array shape or lattice shape) are arranged on the detection surface 8 on the LSI chip. have.
By bringing the subject 9 such as a finger into contact with the detection surface 8 of the surface shape recognition sensor device 150, the surface of the subject 9, here, the uneven shape of the fingerprint is individually detected via each detection element of the detection unit 1. The surface shape data indicating the surface shape of the subject is output.

FIG. 25 is a block diagram illustrating a configuration of the surface shape recognition sensor device. The surface shape recognition sensor device 150 includes a detection unit 1, a surface shape detection unit 6, and a living body recognition unit 7. The detection unit 1 includes detection elements 1A, 1B, and 1C.
The detection element 1 </ b> A includes a detection electrode 11 </ b> A that forms a capacitance with the subject 9 through an insulating film, and a detection electrode 12 </ b> A that is in electrical contact with the subject 9. Among these, the detection electrode 11A is connected to the surface shape detection unit 6, and the detection electrode 12A is connected to a fixed potential such as a ground potential. This fixed potential is supplied at a constant potential (low impedance) from a predetermined supply circuit unit (not shown) such as a power supply circuit.

The detection element 1B has a detection electrode 11B that forms a capacitance with the subject 9 via an insulating film, and a detection electrode 12B that is in electrical contact with the subject 9. Among these, the detection electrode 11 </ b> B is connected to the surface shape detection unit 6, and the detection electrode 12 </ b> B is connected to the living body recognition unit 7.
The detection electrode 1 </ b> C includes a detection electrode 11 </ b> C that forms a capacitance with the subject 9 via an insulating film, and a detection electrode 12 </ b> C that is in electrical contact with the subject 9. Among these, the detection electrode 11C is connected to the surface shape detection unit 6, and the detection electrode 12C is connected to a fixed potential.

The surface shape detection unit 6 is a surface that indicates the uneven shape of the surface of the subject 9 based on the capacitance generated between the detection electrodes 11A, 11B, 11C of the detection elements 1A, 1B, and 1C and the subject 9. It is a circuit unit that outputs shape data 6S.
The living body recognition unit 7 determines whether or not the subject 9 is a living body based on the impedance of the subject 9 connected between the detection electrode 12B of the detection element 1B and the detection electrode 12A of the detection element 1A. The circuit unit that outputs the result 7S.

  Next, the operation of the conventional surface shape recognition sensor device will be described. The operation of the surface shape recognition sensor device 150 includes a surface shape detection operation for detecting the surface shape of the subject 9 by the surface shape detection unit 6 and a biological recognition operation for performing biological recognition of the subject 9 by the biological recognition unit 7. Yes, one of these operations is selectively executed in accordance with control from a higher-level device (not shown).

  First, in the surface shape detection operation, the surface shape detection unit 6 uses the surface shape detection unit 6 to detect the subject based on the magnitude of the capacitance formed between the detection electrode 11A of the detection element 1A and the subject 9. A signal indicating the surface shape at the position of the nine detection elements 1A is generated and output as surface shape data 6S. Also, the detection elements 1B and 1C also show the uneven shape of the surface of the subject by the surface shape detection unit 6 based on the size of the capacitance formed between the detection electrodes 11B and 11C and the subject 9. Output as surface shape data 6S. At this time, since the subject 9 is connected to a fixed potential via the detection electrode 12A of the detection element 1A, the capacitance formed by these detection electrodes 11A, 11B, and 11C is stable, and the surface is low in noise. Shape data 6S is obtained.

  On the other hand, in the biological recognition operation, since the subject 9 is connected to a fixed potential via the detection electrode 12A of the detection element 1A, the detection of the detection element 1A via the subject 9 from the detection electrode 12B of the detection element 1B. A current path to the electrode 12A, that is, a fixed potential is formed. In the living body recognition unit 7, whether or not the subject 9 is a living body based on whether or not the impedance value inherent to the subject 9 existing in the current path is within the reference range indicating the legitimate living body impedance. Determine whether. At this time, the living body recognition unit 7 performs living body recognition using a signal that changes in accordance with the impedance of the subject 9, but the subject 9 is connected to a fixed potential via the detection electrode 12A of the detection element 1A. Therefore, potential fluctuation due to induction to the subject 9 is suppressed, a stable signal is obtained, and accurate biometric authentication is realized.

  In this way, the detection electrode 11A is connected to the surface shape detection unit 6, the detection electrode 1A is connected to the fixed potential, the detection electrode 11B is connected to the surface shape detection unit 6, and the detection electrode 12B is a living body. The detection element 1B connected to the recognition unit 7 and the detection electrode 11C connected to the surface shape detection unit 6 and the detection element 1C connected to the detection electrode 12C at a fixed potential are arranged on the detection surface 8 to detect the surface shape. Based on the individual capacitances obtained from the detection elements 1A, 1B, and 1C, the unit 6 outputs signals indicating the irregularities of the surface shape corresponding to the positions in contact with the detection elements 1A, 1B, and 1C. In the recognition unit 7, whether or not the subject 9 is a living body based on a signal corresponding to the impedance of the subject 9 connected between the detection electrode 12B of the detection element 1B and the detection electrode 12A of the detection element 1A. It is to be determined.

Accordingly, the subject 9 is connected to a fixed potential via the detection electrode 12A of the detection element 1A, and the potential variation induced by the subject 9 can be suppressed and accurate biological recognition can be performed, and the surface with less noise Shape data is obtained.
Further, since each detection element is shared by the surface shape detection operation and the biological recognition operation, it is not necessary to arrange a detection element for biological recognition separately from the detection element for detecting the surface shape, and the layout area is reduced. The increase in manufacturing cost per chip can be avoided without increasing. Accordingly, it is possible to perform living body recognition in addition to detection of the subject without increasing the size of the device, and the device can be easily realized as a chip.

  Next, with reference to FIGS. 26 and 27, the configuration of the detection element used in the conventional surface shape recognition sensor device will be described. FIG. 26 is a front view showing a configuration of a detection unit used in a conventional surface shape recognition sensor device. FIG. 27 is a cross-sectional view taken along the line AA in FIG. 26 showing the configuration of the detection unit used in the conventional surface shape recognition sensor device.

  The detection element 1A includes detection electrodes 11A arranged in a grid pattern on the detection surface 8 of the surface shape recognition sensor device 150, and detection electrodes 12A formed in a wall shape at positions spaced around the periphery of the detection electrodes 11A. It consists of and. Similarly, the detection element 1B is composed of detection electrodes 11B arranged in a grid pattern and detection electrodes 12B formed in a wall shape at positions spaced around the periphery of the detection electrode 11B. The detection element 1C is composed of detection electrodes 11C arranged in a lattice pattern, and detection electrodes 12C formed in a wall shape at positions spaced around the detection electrode 11C.

The detection electrodes 11A, 11B, and 11C are made of a metal film, and an upper side that is close to the subject 9 is covered with an insulating film 14, and a capacitive element is formed using the subject 9 as a counter detection electrode. At this time, since the distance between the subject and the detection electrode changes due to the unevenness of the surface shape of the subject, a capacitance corresponding to the unevenness of the surface shape is formed.
On the other hand, the detection electrodes 12A and 12B are exposed on the upper side and are in electrical contact with the subject 9. Thereby, a fixed potential connected to the detection electrode 12A is applied to the subject 9, and the impedance of the subject 9 is connected to the living body recognition unit 7 via the detection electrode 12B. The detection electrode 12C has an insulating film 14 formed on the upper side and is connected to a fixed potential. At this time, the detection electrodes 12A, 12B, and 12C are shared by the adjacent detection elements 1A, the detection elements 1B, and the detection elements 1C, respectively.

Accordingly, a notch 13 is provided between the detection electrodes 12A and 12C and between the detection electrodes 12A and 12C at the boundary where the detection element 1C and the detection elements 1A and 1B are adjacent to each other to electrically insulate them from each other. Yes.
FIG. 28 is an explanatory diagram showing a sensor surface configuration of the surface shape recognition sensor device. FIG. 29 is an enlarged view of a main part of FIG. A square detection region 8B in which a plurality of detection elements 1B are arranged adjacent to each other is arranged in an island shape in the approximate center of the detection surface 8, a separation region 8C in which a plurality of detection elements 1C are arranged adjacent to each other is arranged, and the outer periphery of the detection region 8B is arranged around the entire circumference. A fixed potential region 8A in which a plurality of detection elements 1A are arranged adjacent to each other is arranged so as to surround the entire outer periphery of the separation region 8C.

International Publication No. 05/016146 Pamphlet International Publication No. 05/019767 Pamphlet

  In such a conventional technique, the detection electrode 12A in the fixed potential region 8A and the detection electrode 12B in the detection region 8B are in contact with the subject 9 and electrically connected to the subject 9 as shown in FIG. The impedance of the subject 9 is detected. At this time, since variations in the contact condition occur due to the shape and state of the surface of the subject 9 or the positional relationship with the detection electrode, detection is necessary to detect the impedance of the subject 9 accurately and stably. The electrode 12A and the detection electrode 12B need to be connected at many points through the subject 9. Therefore, a certain length is required as the peripheral length of the detection region 8B.

On the other hand, the subject 9 may be charged with static electricity. In such a case, when the subject 9 comes close to the detection surface 8, the fixed potential region 8A or the separation region 8C having an exposed detection electrode. There is a high possibility of discharge. Here, when the charged static electricity is discharged to the detection electrode 12A in the fixed potential region 8A, the detection electrode 12A is connected to a low impedance fixed potential, so that the circuit is hardly destroyed. However, when static electricity is discharged to the detection electrode 12B in the detection region 8B, various signal processing circuits are connected to the biometric recognition unit 7 side and have a certain degree of impedance, so these circuits are destroyed. .
At this time, the probability that the static electricity is discharged to the detection region 8B is increased according to the area of the detection region 8B. Therefore, it is desirable that the area of the detection region 8B is small.

  However, when detecting the impedance of the subject 9 as in the biometric recognition operation described above, if the square detection region 8B as shown in FIG. 28 is used, a sufficient length is obtained as the perimeter of the detection region 8B. Requires a relatively large area as the detection region 8B, and when the subject 9 approaches the sensor surface, the static electricity charged on the subject 9 is easily discharged to the detection region 8B, and the living body connected to the detection region 8B is recognized. There was a problem that the circuit of the unit 7 was destroyed by static electricity.

  The present invention is for solving such problems, and can detect the impedance of the subject with high accuracy and can suppress failure due to electrostatic discharge charged in the subject, an impedance detection method, biometric recognition An object is to provide a device and a fingerprint authentication device.

In order to achieve such an object, an impedance detection apparatus according to the present invention includes a detection unit including a plurality of detection elements arranged on a detection surface that is in electrical contact with a subject having an uneven shape on the surface, and an alternating current. A supply signal generating unit for generating a supply signal, and an application signal corresponding to the supply signal applied to the subject and connected to the subject along with the application signal. A response signal generator that generates and outputs an alternating response signal that changes depending on the flowing current, and detects at least one of the phase or amplitude of the response signal as waveform information, and determines the impedance of the subject based on the waveform information. The waveform detection unit includes a waveform information detection unit that outputs a detection signal to be detected, and the detection unit electrically connects the subject in contact with the detection surface to the response signal generation unit. A detection region in which a number of detection elements are arranged in a strip shape, and a fixed potential region in which a plurality of detection elements that electrically connect a subject in contact with the detection surface to a predetermined fixed potential surround the detection region, The separation region is provided between the detection region and the fixed potential region and electrically separates the detection region and the fixed potential region . The detection region has a smaller area than the fixed potential region and is longer in the longitudinal direction. Has a length capable of contacting a plurality of convex portions across the concave portions on the surface of the subject .

At this time, the detection region may be formed such that a plurality of band-like regions in which the detection elements are arranged are joined at the end of the band-like region.
Or you may form a detection area | region so that the strip | belt-shaped area | region in which the detection element is arrange | positioned may make the shape branched in multiple at the branch point.
Or you may make it make the detection area | region form the shape where the strip | belt-shaped area | region where the detection element is arrange | positioned bent at the bending point.

Further, the detection region may be formed in a cross shape as a whole, or may be formed in a ring shape as a whole.
Alternatively, the detection area may be formed such that the corner of the detection area has a curved shape.
Alternatively, the detection region may be formed so as to be symmetric with respect to two axes on the detection surface orthogonal to each other.

Also, the detection region, the detection electrodes form a respective ring shape of each detecting element for electrical contact with the object, these detection electrodes may be formed to have a configuration arranged in an array.

In addition, the impedance detection method according to the present invention is performed by a response signal generation unit for a subject having a concavo-convex shape on a surface that is in electrical contact with a detection unit including a plurality of detection elements arranged on a detection surface. A response signal generating step of applying an application signal corresponding to the AC supply signal and generating and outputting a response signal that changes according to the current flowing through the subject in accordance with the application signal; and at least the phase or amplitude of the response signal A waveform information detection step of detecting either one as waveform information and outputting a detection signal indicating the impedance of the subject based on the waveform information, and the detection unit detects a plurality of detection elements arranged in a band shape A fixed potential in which a subject that is in contact with the detection surface is electrically connected to the response signal generator by a region, and a plurality of detection elements are arranged to surround the detection region. The frequency, the subject in contact with the detection surface electrically connected to a predetermined fixed potential, the isolation region provided between the detection region and the fixed potential region electrically isolates the fixed potential region and the detection region The detection region has a smaller area than the fixed potential region and a length in the longitudinal direction that can contact the plurality of convex portions across the concave portions on the surface of the subject .

  In addition, the living body recognition apparatus according to the present invention includes any one of the impedance detection apparatuses that outputs a detection signal corresponding to the impedance of the subject, and whether the subject is a living body based on the detection signal output from the impedance detection apparatus. A biological recognition unit for determining whether or not.

  The fingerprint authentication apparatus according to the present invention includes the biometric recognition apparatus that determines whether or not the subject is a living body based on a detection signal corresponding to the impedance of the subject, and fingerprint data indicating the unevenness of the fingerprint from the subject. A fingerprint detection device that detects fingerprints, a fingerprint authentication unit that compares fingerprint data and pre-registered verification data, and performs user fingerprint authentication based on the verification result, and a biometric determination output from the biometric recognition device An authentication determination unit that determines whether the user has succeeded in fingerprint authentication based on the result and the fingerprint authentication result output from the fingerprint authentication unit;

According to the present invention, the detection unit includes a detection region in which a plurality of detection elements that are in contact with the detection surface and electrically connect an object having a concavo-convex shape on the surface to the response signal generation unit are arranged in a band shape, and detection A plurality of detection elements that electrically connect a subject in contact with the surface to a predetermined fixed potential are disposed between the detection region and the fixed potential region. And a separation region that electrically separates the fixed potential region, and the detection region has a smaller area than the fixed potential region and has a length in the longitudinal direction across the recesses on the surface of the subject. because it has a possible length in contact with, while maintaining the perimeter of the detection area, it is possible to reduce the area.

  Therefore, it is possible to reduce the probability that static electricity charged in the subject is discharged to the detection region without shortening the perimeter of the detection region, to accurately detect the impedance of the subject, and to discharge the static electricity charged to the subject. Failure can be suppressed. In particular, if the impedance detection device is used as the impedance detection means of the biological recognition device, the biological recognition accuracy and reliability of the subject can be improved. In addition, if such a biometric recognition device is installed in a personal recognition system using a fingerprint authentication device, the security performance and reliability performance of the entire system can be improved, which is very effective.

Next, embodiments of the present invention will be described with reference to the drawings.
[First Embodiment]
First, with reference to FIG. 1, an impedance detection apparatus according to a first embodiment of the present invention will be described. FIG. 1 is a block diagram showing the configuration of the impedance detection apparatus according to the first embodiment of the present invention. FIG. 2 is a front view showing a detection unit of the impedance detection apparatus according to the first embodiment of the present invention.

  The impedance detection device 100 is a device that applies a predetermined signal to the subject and detects the impedance of the subject based on the obtained response signal. The impedance detection apparatus 100 includes a detection unit 1, a supply signal generation unit 2, a response signal generation unit 3, and a waveform information detection unit 4 as main functional units.

  In the present embodiment, the detection unit 1 includes a detection region 8B in which a plurality of detection elements 1B that electrically connect the subject 9 in contact with the detection surface 8 to the response signal generation unit are arranged in a band shape, and the detection surface 8 Between the detection region 8B and the fixed potential region 8A, and a plurality of detection elements 1A that electrically connect the subject 9 that is in contact with the target 9 to a predetermined fixed potential. A separation region 8C that is provided and electrically separates the detection region 8B from the fixed potential region 8A.

Hereafter, with reference to FIG. 1, each function part of the impedance detection apparatus concerning the 1st Embodiment of this invention is demonstrated in detail.
The detection unit 1 is in electrical contact with the subject 9 via a plurality of detection elements disposed on the detection surface 8 that is in electrical contact with the subject 9 made of a living body such as a finger, and the impedance of the subject 9 It has a function of connecting the reactance component and the resistance component of Zf to the response signal generator 3.

The supply signal generation unit 2 has a function of generating a supply signal 2 </ b> S composed of a sine wave having a predetermined frequency and outputting it to the response signal generation unit 3.
The response signal generation unit 3 applies an application signal 1S corresponding to the supply signal 2S from the supply signal generation unit 2 to the detection element 1, and the output impedance of the detection element 1B, that is, the subject 9 has the application signal 1S. It has a function of generating a response signal 3S that changes depending on the capacitance component and resistance component of the impedance and outputting the response signal 3S to the waveform information detection unit 4.

The waveform information detection unit 4 uses the waveform indicated by the response signal 3S from the response signal generation unit 3 as the waveform information indicating the characteristics of the waveform according to the impedance of the subject 9, and the phase difference between the response signal 3S and the supply signal 2S. Alternatively, it has a function of detecting the amplitude and a function of outputting a detection signal 4S indicating the impedance of the subject 9 based on the waveform information consisting of these phase differences or amplitudes.
The specific configurations of the supply signal generation unit 2, the response signal generation unit 3, and the waveform information detection unit 4 will be described with reference to FIGS. 20 and 20 described above according to the type of waveform information detected from the response signal 3S, that is, the phase difference and amplitude. A known circuit configuration such as 22 may be used, and a detailed description thereof is omitted here.

Next, with reference to FIG. 1 and FIG. 2, the detection part of the impedance detection apparatus concerning the 1st Embodiment of this invention is demonstrated in detail.
As shown in FIG. 2, the detection surface 8 of the detection unit 1 is provided with a fixed potential region 8A, a detection region 8B, and a separation region 8C.
In the fixed potential region 8A, a plurality of detection elements 1A that electrically connect the subject 9 in contact with the detection surface 8 to a predetermined fixed potential are arranged so as to surround the detection region 8B. This detection element 1A has a detection electrode 12A connected to a low impedance fixed potential such as a ground potential or a power supply potential, and has a function of electrically connecting the subject 9 to the fixed potential via this detection electrode 12A. is doing.

In the detection region 8B, a plurality of detection elements 1B that electrically connect the subject 9 in contact with the detection surface 8 to the response signal generation unit are arranged in a band shape. The detection element 1B has a detection electrode 12B connected to the response signal generation unit 3, and has a function of electrically connecting the subject 9 to the response signal generation unit 3 via the detection electrode 12B. .
The separation region 8C is provided in a band shape between the detection region 8B and the fixed potential region 8A, and has a function of electrically separating the detection region 8B and the fixed potential region 8A.

  The subject 9 placed on the detection surface 8 contacts the detection element 1A in the fixed potential region 8A and the detection element 1B in the detection region 8B across the separation region 8C, and is fixed via the detection electrode 12A and the detection electrode 12B. The potential and response signal generator 3 are electrically connected to each other. Thereby, the reactance component and the resistance component of the impedance Zf of the subject 9 are connected between the response signal generator 3 and the fixed potential.

At this time, since variations in the contact condition occur due to the shape and state of the surface of the subject 9 or the positional relationship with the detection electrode, detection is necessary to detect the impedance of the subject 9 accurately and stably. The electrode 12A and the detection electrode 12B need to be connected at many points through the subject 9. Therefore, a certain length is required as the peripheral length of the detection region 8B.
For example, when the perimeter of the detection region 8B is LB, the width of the separation region 8C is W _C, and the impedance per unit area of the subject 9 is Zf ₀ , the detection region 8B is fixed between the detection region 8B and the fixed potential region 8A. The generated impedance Zf can be expressed as Zf≈Zf ₀ × (LB / W _C ).

  On the other hand, when the subject 9 is charged with static electricity, when the subject 9 comes close to the detection surface 8, there is a high possibility of discharging to the fixed potential region 8A or the separation region 8C having the exposed detection electrode. Here, when the charged static electricity is discharged to the detection electrode 12A in the fixed potential region 8A, the detection electrode 12A is connected to a low impedance fixed potential, so that the circuit is hardly destroyed. However, when static electricity is discharged to the detection electrode 12B in the detection region 8B, various signal processing circuits are connected to the biometric recognition unit 7 side and have a certain degree of impedance, so these circuits are destroyed. .

At this time, the probability that the static electricity is discharged to the detection region 8B is increased according to the area of the detection region 8B. Therefore, it is desirable that the area of the detection region 8B is small.
In the present embodiment, since the detection elements 1B of the detection region 8B are arranged in a band shape, when the perimeter of the detection region 8B is constant, the conventional square detection region 8B as shown in FIGS. In comparison, the area can be reduced.

FIG. 3 is an explanatory diagram showing a comparison between the shape of the detection region and the perimeter. In the case of a band shape (rectangular shape) like the detection region 8B of the present embodiment, when the length is L and the width is W, the peripheral length of the band shape is (L + W) × 2, and the area is L × W. On the other hand, when forming a square in the same circumferential length, becomes a side length of (L + W) / 2, the area of the square becomes ^{(L + W) 2/4} . Therefore, when L> W, the area of the band shape is always smaller than that of the square, and this can be confirmed by a simple arithmetic process.

FIG. 4 is a graph showing the relationship between the aspect ratio and the area ratio, where the horizontal axis indicates the aspect ratio L / W of the rectangular length L and width W, and the vertical axis indicates a square (L = W). The ratio with respect to the area is shown.
When the circumference of the rectangular shape is constant, that is, on condition that the sum of the length L and the width W of the belt shape is constant, the area in the case of a square is the largest, and the area increases as the aspect ratio increases. It turns out that it becomes small.

  As described above, in the present embodiment, the detection unit 1 includes a detection region 8B in which a plurality of detection elements 1B that electrically connect the subject 9 in contact with the detection surface 8 to the response signal generation unit are arranged in a band shape. A fixed potential region 8A in which a plurality of detection elements 1A that electrically connect the subject 9 in contact with the detection surface 8 to a predetermined fixed potential are arranged so as to surround the detection region 8B, and the detection region 8B and the fixed potential region Since the detection region 8B is provided between the detection region 8B and the separation region 8C that electrically separates the fixed potential region 8A, the area of the detection region 8B can be reduced while maintaining the peripheral length.

Therefore, the probability that static electricity charged in the subject 9 is discharged to the detection region 8B can be reduced without shortening the perimeter of the detection region 8B, the impedance of the subject can be accurately detected, and the subject 9 is charged. Failures due to electrostatic discharge can be suppressed.
In the present embodiment, a rectangular shape is shown as a specific example of the detection region 8B. However, the shape is not limited to a shape having properties such as parallelism of opposing pieces and orthogonality of sides, which are characteristic of the rectangular shape. Any shape may be used as long as it extends in a strip shape in an arbitrary longitudinal direction, and the entire detection region 8B may be curved.

[Second Embodiment]
Next, an impedance detection apparatus according to a second embodiment of the present invention will be described with reference to FIG. FIG. 5: is a front view which shows the detection part of the impedance detection apparatus concerning the 2nd Embodiment of this invention.

  In the first embodiment, the case where the detection region 8B is composed of one band-like region has been described as an example. In the present embodiment, a case will be described in which the detection region 8B as a whole has a shape in which a plurality of band-like regions are joined at the ends of the band-like regions. In addition, about the other structure in the impedance detection apparatus 100 of this Embodiment, it is the same as that of 1st Embodiment, and detailed description here is abbreviate | omitted.

  As shown in FIG. 5, the detection region 8B according to the present embodiment is composed of strip-shaped regions 81, 82, 83, and 84 joined in a cross shape. In these band-like regions 81, 82, 83, and 84, a plurality of detection elements 1 </ b> B are arranged in a band shape. Are joined together. Therefore, the peripheral length of the entire detection region 8B is extended by the joined strip regions 82, 83, and 84.

  As described above, in the present embodiment, the detection region 8B is formed so that the plurality of belt-like regions where the detection elements are arranged are joined at the ends of the belt-like region as a whole. The perimeter of the entire 8B can be easily extended. In particular, since the length in the longitudinal direction of the detection region 8B is limited based on the size of the subject 9 and the detection surface 8, the peripheral length obtained in the detection region 8B composed of one band-like region as shown in FIG. There are limits. As in the present embodiment, the peripheral length of the entire detection region 8B can be easily extended by joining a plurality of band-like regions at the ends.

  In the present embodiment, since the band-shaped areas 81, 82, 83, and 84 are joined in a cross shape to form the detection area 8B, for example, not only the longitudinal direction of the band-shaped areas 81 and 83 but also the band-shaped areas that are orthogonal thereto. Also in the longitudinal direction of the regions 82 and 84, the contact failure between the subject 9 and the detection electrodes 12A and 12B due to the displacement of the placement position can be reduced, and the impedance detection error due to the displacement of the placement position can be suppressed. .

[Third Embodiment]
Next, an impedance detection apparatus according to a third embodiment of the present invention will be described with reference to FIG. FIG. 6: is a front view which shows the detection part of the impedance detection apparatus concerning the 3rd Embodiment of this invention.

  In the first embodiment, the case where the detection region 8B is composed of one band-like region has been described as an example. In the present embodiment, a case will be described in which the detection region 8B as a whole has a shape in which a belt-like region in which detection elements are arranged branches at a branch point. In addition, about the other structure in the impedance detection apparatus 100 of this Embodiment, it is the same as that of 1st Embodiment, and detailed description here is abbreviate | omitted.

  As shown in FIG. 6, the detection region 8B according to the present embodiment has a shape in which a belt-like region 81 branches into a plurality of belt-like regions 82 and 83 at a branch point B in a Y shape. A plurality of detection elements 1B are also arranged in the belt-like regions 82 and 83 in a belt-like manner. Therefore, the peripheral length of the entire detection region 8B is extended by the branched strip regions 82 and 83.

  As described above, in the present embodiment, the detection region 8B is formed so that the belt-like region 81 in which the detection elements are arranged is branched into a plurality at the branch point B as a whole. The perimeter can be easily extended. In particular, since the length in the longitudinal direction of the detection region 8B is limited based on the size of the subject 9 and the detection surface 8, the peripheral length obtained in the detection region 8B composed of one band-like region as shown in FIG. There are limits. As in the present embodiment, the perimeter of the entire detection region 8B can be easily extended by branching the strip region 81 at the branch point B.

  Further, in the present embodiment, the detection region 8B is configured by branching the belt-like region 81 in a Y shape. In contrast, the contact failure between the subject 9 and the detection electrodes 12A and 12B due to the displacement of the mounting position can be reduced, and the impedance detection error due to the displacement of the mounting position can be suppressed. In addition, it is not limited to the branch Y shape of the strip | belt-shaped area | regions 82 and 83, For example, you may branch in arbitrary directions, such as T shape.

[Fourth Embodiment]
Next, an impedance detection apparatus according to a fourth embodiment of the present invention will be described with reference to FIG. FIG. 7: is a front view which shows the detection part of the impedance detection apparatus concerning the 4th Embodiment of this invention.

  In the first embodiment, the case where the detection region 8B is composed of one band-like region has been described as an example. In the present embodiment, a case will be described in which the detection region 8B as a whole has a shape in which a belt-like region in which detection elements are arranged is bent at a bending point. In addition, about the other structure in the impedance detection apparatus 100 of this Embodiment, it is the same as that of 1st Embodiment, and detailed description here is abbreviate | omitted.

  As shown in FIG. 7, the detection region 8B according to the present embodiment has a shape in which the belt-like region 81 is bent at the bending point C into the belt-like regions 82 and 83, respectively, in a U-shape. A plurality of detection elements 1B are also arranged in the belt-like regions 82 and 83 in a belt-like manner. Therefore, the peripheral length of the entire detection region 8B is extended by the bent strip regions 82 and 83.

  Thus, in the present embodiment, since the detection region 8B is formed so that the belt-like region 81 in which the detection element is arranged is bent to the belt-like regions 82 and 83 at the bending point C as a whole, detection is performed. The perimeter of the entire region 8B can be easily extended. In particular, since the length in the longitudinal direction of the detection region 8B is limited based on the size of the subject 9 and the detection surface 8, the peripheral length obtained in the detection region 8B composed of one band-like region as shown in FIG. There are limits. As in the present embodiment, the perimeter of the entire detection region 8B can be easily extended by bending the belt-like region 81 at the bending point C.

  Further, in the present embodiment, the detection region 8B is configured by being bent in a U-shape at the bending points C at both ends of the belt-like region 81. Therefore, for example, not only the longitudinal direction of the belt-like region 81 but also the belt-like region folded from here The contact failure between the subject 9 and the detection electrodes 12A and 12B due to the displacement of the placement position can be reduced also in the branch direction of 82 and 83, and the impedance detection error due to the displacement of the placement position can be suppressed. In addition, by bending the U-shape, the detection region 8B can be efficiently configured in a limited area such as the size of the subject 9 and the detection surface 8, and the entire perimeter of the detection region 8B is extremely efficient. Can be extended well. In this embodiment, a U-shape is described as an example. However, the folding method is not limited to a U-shape, and may be folded by an arbitrary method such as a W-shape. May be increased to a wave shape or a spiral shape.

[Fifth Embodiment]
Next, an impedance detection apparatus according to a fifth embodiment of the present invention will be described with reference to FIG. FIG. 8: is a front view which shows the detection part of the impedance detection apparatus concerning the 5th Embodiment of this invention.

  In the first embodiment, the case where the detection region 8B is composed of one band-like region has been described as an example. In the present embodiment, a case will be described in which the detection region 8B has a ring shape as a whole. In addition, about the other structure in the impedance detection apparatus 100 of this Embodiment, it is the same as that of 1st Embodiment, and detailed description here is abbreviate | omitted.

  As shown in FIG. 8, the detection region 8B according to the present embodiment has an annular shape in which both ends of the band-shaped detection region 8B are joined, and here, a rectangular shape. In the annular detection region 8B, a plurality of detection elements 1B are arranged throughout. In addition, a fixed potential region 8A in which the detection element 1B is arranged instead of the detection element 1B is provided in the center of the detection region 8B, and a separation region 8C is provided between the fixed potential region 8A and the detection region 8B. ing. Thereby, the perimeter of the whole detection area 8B is extended.

  Thus, in this embodiment, since the detection region 8B is formed so as to form a ring as a whole, the perimeter of the entire detection region 8B can be easily extended. In particular, since the length in the longitudinal direction of the detection region 8B is limited based on the size of the subject 9 and the detection surface 8, the peripheral length obtained in the detection region 8B composed of one band-like region as shown in FIG. There are limits. As in the present embodiment, the circumferential length of the entire detection region 8B can be easily extended by adopting an annular shape.

  In addition, according to the present embodiment, since the detection region 8B is formed so as to form an annular shape as a whole, the fixed potential region 8A can be provided in the center of the detection region 8B. Thereby, since the fixed potential region 8A is provided at a position closest to the subject 9 approaching the detection surface 8 at the time of placement, static electricity charged in the subject 9 is fixed potential region. It becomes easy to discharge to 8A. Therefore, the probability of discharge to the detection region 8B can be reduced, and circuit breakdown can be suppressed.

[Sixth Embodiment]
Next, with reference to FIG. 9, the impedance detection apparatus concerning the 6th Embodiment of this invention is demonstrated. FIG. 9: is a front view which shows the detection part of the impedance detection apparatus concerning the 6th Embodiment of this invention.

  In the first embodiment, the case where the detection region 8B is composed of one band-like region has been described as an example. In the present embodiment, a case will be described in which the corners of the detection region 8B are curved. In addition, about the other structure in the impedance detection apparatus 100 of this Embodiment, it is the same as that of 1st Embodiment, and detailed description here is abbreviate | omitted.

  In the detection region 8B according to the present embodiment, as shown in FIG. 9, the corners of the detection region 8B have a curved shape. In general, static electricity has a characteristic of being easily discharged to a sharp portion. Therefore, since the sharp corners of the detection region 8B have a smooth curved shape, static electricity charged on the subject 9 is difficult to be discharged to the detection region 8B.

  Thus, in this embodiment, since the detection region 8B is formed so that the corners are curved, static electricity charged in the subject 9 is difficult to be discharged to the detection region 8B, and a circuit by this discharge Can be prevented from breaking.

In the present embodiment, as shown in FIG. 9, the detection region 8B has been described as an example of a single band-like region. However, the present invention is not limited to this, and other shapes may be used. It can also be applied to the detection region 8B.
FIG. 10: is a front view which shows the other detection part of the impedance detection apparatus concerning the 6th Embodiment of this invention. Here, an example in which the present embodiment is applied to the annular detection region 8B of FIG. 8 is shown, and the same effect as that of FIG. 9 is obtained.

  Moreover, what is necessary is just to select arbitrarily also about the degree of curvature. FIG. 11: is a front view which shows the other detection part of the impedance detection apparatus concerning the 6th Embodiment of this invention. Here, an example in which the present embodiment is applied to the annular detection region 8B of FIG. 8 is shown, and the degree of curvature is increased as compared to FIG. 10, so that the entire detection region 8B has an oval shape. There is no. In this case, the same effect as that of FIG. 9 can be obtained.

[Seventh Embodiment]
Next, with reference to FIG. 12 and FIG. 13, an impedance detection apparatus according to a seventh embodiment of the present invention will be described. FIG. 12 is a front view showing a detection unit of the impedance detection device according to the seventh exemplary embodiment of the present invention, in which an example in which the detection region 8B is in contact with a laterally extending fingerprint is shown. Yes. FIG. 13: is a front view which shows the detection part of the impedance detection apparatus concerning the 7th Embodiment of this invention, and the example which the detection area 8B is contacting with the fingerprint extended in the vertical direction is shown Yes.

  In the first embodiment, the case where the detection region 8B is composed of one band-like region has been described as an example. In the present embodiment, a case will be described in which the detection region 8B is symmetric with respect to two axes on a detection surface orthogonal to each other. In addition, about the other structure in the impedance detection apparatus 100 of this Embodiment, it is the same as that of 1st Embodiment, and detailed description here is abbreviate | omitted.

The detection area 8B according to the present embodiment has a shape that the detection area 8B is symmetrical with respect to two axes X and Y orthogonal to each other on the detection surface 8, in this case, a cross shape composed of band-shaped areas 81 to 84. Yes.
When the detection region 8B having such a shape is used, when the fingerprint ridge 9A and the fingerprint valley 9B are substantially parallel to the axis X as shown in FIG. 83 and the fingerprint ridge 9A are in electrical contact with each other in the contact areas 85 and 86. On the other hand, as shown in FIG. 13, when the fingerprint ridge 9A and the fingerprint valley 9B are substantially parallel to the axis Y, the band-like regions 82 and 84 and the fingerprint ridge 9A perpendicular to them are in contact regions 87. , 88 make electrical contact.

  Thus, in the present embodiment, the detection region 8B is formed so as to be symmetric with respect to two axes on the detection surface orthogonal to each other as a whole, so that the subject placed on the detection surface 8 is Even if the concavo-convex direction of 9 changes, for example, the ridge / valley direction of the fingerprint, the change in the contact area between the subject 9 and the detection region 8B can be suppressed. Accordingly, the subject 9 and the detection region 8B can be reliably brought into contact with each other, and impedance detection errors caused by the unevenness of the subject 9 can be suppressed.

  In the present embodiment, as shown in FIGS. 12 and 13, the case where the detection region 8 </ b> B has a cross shape has been described as an example. However, the present invention is not limited to this, and for example, FIGS. As described above, if the shape is symmetrical with respect to the two axes X and Y that are orthogonal to each other on the detection surface 8, similar effects can be obtained even with other shapes.

[Eighth Embodiment]
Next, with reference to FIG. 14, an impedance detection apparatus according to an eighth embodiment of the present invention will be described. FIG. 14: is a front view which shows the detection part of the impedance detection apparatus concerning the 8th Embodiment of this invention.

In the first embodiment, the case where the detection region 8B is composed of one band-like region has been described as an example. In this embodiment, the detection region. 8B, the average minimum valley line width W ₁ of the fingerprint, the average maximum valley line width W ₂ of the fingerprint, and the average maximum ridge width W ₃ of the fingerprint as a reference A case where the length is longer than W ₁ and W ₂ × 2 + W ₃ or less will be described. In addition, about the other structure in the impedance detection apparatus 100 of this Embodiment, it is the same as that of 1st Embodiment, and detailed description here is abbreviate | omitted.

As shown in FIG. 14, the detection region 8B according to the present embodiment includes an average minimum valley line width W _{1 of} the fingerprint, an average maximum valley line width W _{2 of} the fingerprint, and an average maximum peak of the fingerprint. With reference to the line width W ₃ , the length L is greater than W _{1 and} less than or equal to W ₂ × 2 + W ₃ in the longitudinal direction.
In general, the widths of the fingerprint ridge 9A and the fingerprint valley 9B vary to some extent, and the average minimum width (W ₁ ) of both the fingerprint ridge 9A and the fingerprint valley 9B is about 300 μm. (W ₂ , W ₃ ) is said to be about 600 μm.

At this time, by setting the length L in the longitudinal direction of the detection region 8B to the minimum W ₁ (300 μm), the fingerprint ridge 9A that straddles at least the fingerprint valley 9B and is adjacent to one of the fingerprint valleys 9B. And the detection region 8B can be brought into contact with each other. Further, by setting the length L in the longitudinal direction of the detection region 8B to W ₂ × 2 + W ₃ (1800 μm), at least one fingerprint ridge 9A and the detection region 8B can be brought into contact with each other. Therefore, it can be seen that the length L in the longitudinal direction of the detection region 8B may be W ₁ <L ≦ W ₂ × 2 + W ₃ .

Thus, in the present embodiment, the average minimum valley line width W ₁ of the fingerprint, the average maximum valley line width W ₂ of the fingerprint, and the average maximum ridge width W ₃ of the fingerprint as a reference, Since the detection region 8B is formed with a length L that is greater than W _{1 and} less than or equal to W ₂ × 2 + W _{3 in the} longitudinal direction, the subject 9 and the detection region 8B can be brought into electrical contact with each other with a very small detection region 8B. . Therefore, since the area of the detection region 8B can be reduced to an extremely small size, static electricity charged on the subject 9 is difficult to be discharged to the detection region 8B, and circuit breakdown due to this discharge can be suppressed.

In the present embodiment, as shown in FIG. 14, the case where the detection region 8B is configured by one band-like region has been described as an example. However, the present invention is not limited to this. The present invention can also be applied to detection regions 8B having other shapes such as a cross shape or an annular shape.
FIG. 15: is a front view which shows the other detection part of the impedance detection apparatus concerning the 8th Embodiment of this invention. Here, an example in which the present embodiment is applied to the annular detection region 8B of FIG. 11 is shown, and the length in the longitudinal direction (major axis direction) of the elliptical detection region 8B is the length described above. If the length L is applied, the same effect as in FIG. 14 can be obtained.

For the detection region 8B having a symmetrical shape with respect to the two axes X and Y orthogonal to each other on the detection surface 8 as shown in FIG. 12, the length in the direction along the strip regions 81 and 83 is set. The above L may be applied to the length in the direction along the strip regions 82 and 84. Thereby, even when the direction of the fingerprint ridge 9A and the fingerprint valley line 9B and the direction of the detection region 8B are changed, the subject 9 and the detection region 8B can be brought into electrical contact with the extremely small detection region 8B. The same effect as FIG. 14 is obtained.
Further, in the present embodiment, the example in which the length L of the detection region 8B is based on the fingerprint ridge 9A for one line has been described, but the present invention is not limited to this. The length L may be determined on the basis of the fingerprint ridge 9A. Thereby, stable electrical contact between the subject 9 and the detection region 8B can be obtained.

[Ninth Embodiment]
Next, an impedance detection apparatus according to a ninth embodiment of the present invention will be described with reference to FIG. FIG. 16: is a front view which shows the detection part of the impedance detection apparatus concerning the 9th Embodiment of this invention.
In the present embodiment, in the detection unit 1 of the impedance detection apparatus 100, the detection region 8B has a ring shape in each of the detection electrodes 12B of the detection elements 1B that are in electrical contact with the subject 9, and the detection electrodes 12B A case of having a configuration arranged in an array will be described.

  In the detection region 8B according to the present embodiment, as shown in FIG. 16, the detection electrodes 12B of the detection elements 1B each have an annular shape, and the detection electrodes 12B are arranged in an array. In particular, in the example of FIG. 16, the detection electrodes 12B have a rectangular (square) ring shape, and the adjacent detection electrodes 12B are electrically connected to each other, and the detection electrodes 12B are arranged in an array form, in this case, in a lattice form. For this reason, the detection region 8B has a mesh shape, and as a result, the area of the detection region 8B can be reduced.

  As described above, in the present embodiment, the detection region 8B is configured such that the detection electrodes 12B of the detection elements 1B that are in electrical contact with the subject 9 have an annular shape, and the detection electrodes 12B are arranged in an array. Since it has the configuration, the area of the detection region 8B can be reduced. Therefore, the probability of discharge to the detection region 8B can be reduced, and circuit breakdown can be suppressed.

  In addition, since the detection electrode for detecting the capacitance component that changes according to the unevenness of the surface shape of the subject 9 can be arranged in the space formed in the center of the detection electrode 12B having the ring shape, the impedance detection device The surface shape recognition sensor device can share the detection unit 1, and these devices can be easily integrated. In this case, also in the fixed potential region 8A and the separation region 8C, similarly, the detection electrode for detecting the capacitive component is provided in the central space of the lattice over the entire detection surface 8 by providing a grid-like detection electrode and connecting it to the fixed potential. The surface shape can be detected over the entire detection surface 8.

In the present embodiment, as shown in FIG. 16, the detection region 8B has a cross shape as a whole. However, the present invention is not limited to this, and the detection region 8B has another shape. It can also be applied to.
FIG. 17: is a front view which shows the other detection part of the impedance detection apparatus concerning the 9th Embodiment of this invention. Here, an example in which the present embodiment is applied to a detection region 8B that forms a ring shape (circular ring shape) as a whole is shown, and the same effects as in FIG. 16 can be obtained.

[Tenth embodiment]
Next, with reference to FIG. 18, a biometric recognition apparatus and a fingerprint recognition apparatus according to the tenth embodiment of the present invention will be described. FIG. 18 is a block diagram showing configurations of the biometric recognition apparatus and the fingerprint recognition apparatus according to the tenth embodiment of the present invention.

The biological recognition device 110 is a device that recognizes whether or not the subject 9 is a living body, and includes an impedance detection device 100 and a biological recognition unit 101.
The impedance detection device 100 is configured by any one of the impedance detection devices described in the first to ninth embodiments of the present invention, and applies a predetermined application signal to the subject 9, and the subject 9 The impedance information 1Z of the subject is detected based on the current flowing through the sensor, and a detection signal 4S having waveform information corresponding to the impedance is output.

The biological recognition unit 101 determines whether or not the waveform information of the detection signal 4S obtained from the impedance detection device 100 via the detection unit 1 is within a reference range indicating the legitimate biological impedance characteristics. 9 has a function of determining whether or not it is a living body and outputting a living body recognition result 110S for the subject 9. The biometric authentication unit 112 may be configured from a dedicated circuit or may be configured using an arithmetic processing unit such as a CPU.
As described above, since any one of the impedance detection devices described in the embodiments of the present invention is used as the impedance detection device 100, it is possible to suppress a circuit failure due to electrostatic discharge charged in the subject 9, and to Can be detected with high accuracy, and the biological recognition accuracy and reliability of the subject can be improved.

The fingerprint recognition device 120 is a device that performs user authentication based on the surface shape information 1P detected from the subject 9 made of a finger. The biometric recognition device 110, the fingerprint detection device 111, the fingerprint authentication unit 112, and The authentication determination unit 113 is configured.
As described above, the living body recognition apparatus 110 has a function of recognizing whether the subject 9 is a living body using any one of the impedance detection apparatuses described in the first to eleventh embodiments of the present invention. ing.

The fingerprint detection device 111 has a function of detecting fingerprint data 111S corresponding to the surface shape information 1P indicating the unevenness of the fingerprint obtained from the subject 9 via the detection unit 1.
The fingerprint authentication unit 112 compares the fingerprint data 111S output from the fingerprint detection device 111 with verification data indicating a valid fingerprint registered in advance, and performs user fingerprint authentication based on the verification result have.
The authentication determination unit 113 determines whether the user has succeeded in fingerprint authentication based on the biometric recognition result 110S output from the biometric recognition device 110 and the fingerprint authentication result 112S output from the fingerprint authentication unit 112, and outputs the determination result 120S. It has a function to do.
The fingerprint detection device 111, the fingerprint authentication unit 112, and the authentication determination unit 113 may be configured by a dedicated circuit or may be configured by using an arithmetic processing unit such as a CPU.

  As described above, since the biometric recognition device 110 using any one of the impedance detection devices described in the embodiments of the present invention is used as the impedance detection device 100, a circuit failure due to electrostatic discharge charged in the subject 9 is caused. And the impedance of the subject can be detected with high accuracy. Accordingly, fingerprint authentication of the user can be performed with high reliability and accuracy. If such a fingerprint authentication device is installed in a personal recognition system, the security performance and reliability performance of the entire system can be improved.

It is a block diagram which shows the structure of the impedance detection apparatus concerning the 1st Embodiment of this invention. It is a front view which shows the detection part of the impedance detection apparatus concerning the 1st Embodiment of this invention. It is explanatory drawing which shows the comparison with the shape of a detection area | region, and perimeter. It is a graph which shows the relationship between an aspect ratio and an area ratio. It is a front view which shows the detection part of the impedance detection apparatus concerning the 2nd Embodiment of this invention. It is a front view which shows the detection part of the impedance detection apparatus concerning the 3rd Embodiment of this invention. It is a front view which shows the detection part of the impedance detection apparatus concerning the 4th Embodiment of this invention. It is a front view which shows the detection part of the impedance detection apparatus concerning the 5th Embodiment of this invention. It is a front view which shows the detection part of the impedance detection apparatus concerning the 6th Embodiment of this invention. It is a front view which shows the other detection part of the impedance detection apparatus concerning the 6th Embodiment of this invention. It is a front view which shows the other detection part of the impedance detection apparatus concerning the 6th Embodiment of this invention. It is a front view which shows the detection part of the impedance detection apparatus concerning the 7th Embodiment of this invention. It is a front view which shows the detection part of the impedance detection apparatus concerning the 7th Embodiment of this invention. It is a front view which shows the detection part of the impedance detection apparatus concerning the 8th Embodiment of this invention. It is a front view which shows the other detection part of the impedance detection apparatus concerning the 8th Embodiment of this invention. It is a front view which shows the detection part of the impedance detection apparatus concerning the 9th Embodiment of this invention. It is a front view which shows the other detection part of the impedance detection apparatus concerning the 9th Embodiment of this invention. It is a block diagram which shows the structure of the biometric recognition apparatus and fingerprint recognition apparatus concerning the 10th Embodiment of this invention. It is a block diagram which shows the structure of the conventional biometric recognition apparatus. It is a block diagram which shows the specific structure of the conventional impedance detection apparatus which detects a phase difference. It is an example of a signal waveform in each part of the impedance detection apparatus of FIG. It is the block diagram which showed the specific structure of the conventional impedance detection apparatus which detects an amplitude. It is an example of the signal waveform in each part of the impedance detection apparatus of FIG. It is an external view of a surface shape recognition sensor device. It is a block diagram which shows the structure of a surface shape recognition sensor apparatus. It is a front view which shows the structure of the detection part used with the conventional surface shape recognition sensor apparatus. It is AA sectional drawing of FIG. 26 which shows the structure of the detection part used with the conventional surface shape recognition sensor apparatus. It is explanatory drawing which shows the sensor surface structure of a surface shape recognition sensor apparatus. It is a principal part enlarged view of FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 100 ... Impedance detection apparatus, 1 ... Detection part, 1A, 1B, 1C ... Detection element, 11A, 11B, 11C ... Detection electrode, 12A, 12B, 12C ... Detection electrode, 1S ... Applied signal, 2 ... Supply signal generation part, 2S ... Supply signal, 21 ... Frequency generator, 21S ... Clock signal, 22 ... Waveform shaping circuit, 3 ... Response signal generator, 3S ... Response signal, 31 ... Current-voltage converter, 4 ... Waveform information detector, 4S , 4AS, 4BS ... detection signal, 41 ... offset correction circuit, 41S ... signal to be compared, 42 ... reference signal generation circuit, 42S ... reference signal, 43 ... phase comparison circuit, 44 ... peak voltage detection circuit, 44S ... peak voltage value 45 ... center voltage detection circuit, 45S ... center voltage value, 46 ... voltage comparison circuit, 5 ... biometric recognition unit, 5S ... recognition result, 6 ... surface shape detection unit, 6S ... surface shape data, 7 Biological recognition unit, 7S: recognition result, 8: detection surface, 8A: fixed potential region, 8B ... detection region, 8C ... separation region, 81-84 ... strip region, 85-88 ... contact region, 9 ... subject (finger) ), 9A ... fingerprint ridge, 9B ... fingerprint valley, Zf ... impedance, 101 ... biometric recognition unit, 110 ... biometric recognition device, 110S ... biometric recognition result, 1P ... surface shape information, 1Z ... impedance information, 111 ... fingerprint Detection device, 111S ... fingerprint data, 112 ... fingerprint authentication unit, 112S ... fingerprint recognition result, 113 ... recognition determination unit, 120 ... fingerprint recognition device, 120S ... determination result, 150 ... surface shape recognition device.

Claims (12)

A detection unit comprising a plurality of detection elements disposed on a detection surface that is in electrical contact with a subject having an uneven shape on the surface ;
A supply signal generator for generating an alternating supply signal;
An AC that is connected between the supply signal generation unit and the detection element, applies an application signal corresponding to the supply signal to the subject, and changes according to a current flowing through the subject in accordance with the application signal. A response signal generator for generating and outputting a response signal of
An impedance detection device comprising: a waveform information detection unit that detects at least one of the phase and amplitude of the response signal as waveform information and outputs a detection signal indicating the impedance of the subject based on the waveform information. ,
The detector is
A detection region in which a plurality of detection elements that electrically connect the subject in contact with the detection surface to the response signal generation unit are arranged in a band shape;
A fixed potential region in which a plurality of detection elements that electrically connect the subject in contact with the detection surface to a predetermined fixed potential are arranged so as to surround the detection region;
A separation region that is provided between the detection region and the fixed potential region and electrically separates the detection region and the fixed potential region ;
The detection region has an area smaller than that of the fixed potential region, and a length in a longitudinal direction is a length capable of contacting a plurality of convex portions across the concave portions on the surface of the subject. Detection device. The impedance detection apparatus according to claim 1,
The impedance detection device, wherein the detection region has a shape in which a plurality of band-like regions where the detection elements are arranged are joined at an end of the band-like region. The impedance detection apparatus according to claim 1,
The impedance detection device, wherein the detection region has a shape in which a belt-like region in which the detection element is arranged branches at a branch point. The impedance detection apparatus according to claim 1,
The impedance detection device according to claim 1, wherein the detection region has a shape in which a band-like region in which the detection element is arranged is bent at a bending point. The impedance detection apparatus according to claim 1,
The impedance detection device according to claim 1, wherein the detection region has a cross shape as a whole. The impedance detection apparatus according to claim 1,
An impedance detection apparatus according to claim 1, wherein the detection region has an annular shape as a whole. The impedance detection apparatus according to claim 1,
The detection area is characterized in that the corner of the detection area has a curved shape. The impedance detection apparatus according to claim 1,
The impedance detection device, wherein the detection region is symmetric with respect to two axes on the detection surface orthogonal to each other. The impedance detection apparatus according to claim 1,
The impedance detection apparatus according to claim 1, wherein the detection region has a configuration in which detection electrodes of the detection elements that are in electrical contact with the subject each have a ring shape, and the detection electrodes are arranged in an array. A response signal generating unit applies an applied signal corresponding to an AC supply signal to a subject having an uneven shape on the surface that is in electrical contact via a detection unit composed of a plurality of detection elements arranged on the detection surface. A response signal generating step of generating and outputting a response signal that varies depending on the current flowing through the subject in accordance with the applied signal;
A waveform information detection step of detecting at least one of the phase or amplitude of the response signal as waveform information and outputting a detection signal indicating the impedance of the subject based on the waveform information;
The detector is
By means of a detection region in which a plurality of detection elements are arranged in a band shape, the subject in contact with the detection surface is electrically connected to the response signal generation unit,
By electrically connecting the subject in contact with the detection surface to a predetermined fixed potential by a fixed potential region arranged so that a plurality of detection elements surround the detection region,
The separation region provided between the detection region and the fixed potential region electrically separates the detection region and the fixed potential region ,
The detection region has an area smaller than that of the fixed potential region, and a length in a longitudinal direction is a length capable of contacting a plurality of convex portions across the concave portions on the surface of the subject. Detection method. The impedance detection apparatus according to claim 1, which outputs a detection signal corresponding to the impedance of the subject;
A living body recognition device comprising: a living body recognition unit that determines whether or not the subject is a living body based on a detection signal output from the impedance detection device. The living body recognition apparatus according to claim 11 , which determines whether or not the subject is a living body based on a detection signal corresponding to the impedance of the subject;
A fingerprint detection device for detecting fingerprint data indicating irregularities of the fingerprint from the subject;
A fingerprint authentication unit that compares the fingerprint data with previously registered verification data, and performs fingerprint authentication of the user based on the verification result;
An authentication determination unit that determines success or failure of fingerprint authentication of the user based on a biometric determination result output from the biometric recognition device and a fingerprint authentication result output from the fingerprint authentication unit. apparatus.

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