JP2003050994A - Fingerprint checking device and fingerprint image reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To protect a semiconductor fingerprint sensor against static electricity, dust, etc., with simple constitution. SOLUTION: In order to place a finger 10 on a semiconductor fingerprint sensor 3, an opening/closing door 1 is opened with the finger 10. Even if the finger 10 is charged with static electricity, the static electricity of the finger 10 is conducted from the opening/closing door 1 to GND7 through a cable 6 and discharged to the GND of a power source through the GND of a circuit once the opening/closing door 1 as a conductor is touched. At the moment the semiconductor fingerprint sensor 3 is touched with the finger 10, the finger 10 is electrostatically discharged without fail and there is no danger that the semiconductor fingerprint sensor 3 is broken by the static electricity of the finger 10. When the finger 10 is put away thereafter, the opening/closing door 1 is closed with the force of a restoring spring 5 through the operation of Fig. 5, Fig. 4, and Fig. 3 reverse to the above-mentioned operation. Consequently, the opening/closing door 1 is touched without fail before the semiconductor fingerprint sensor 3 is touched in a next chance and the semiconductor fingerprint sensor 3 is never touched with the electrostatically charged finger 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fingerprint collation device and a fingerprint image reading device equipped with a semiconductor fingerprint sensor for reading a human fingerprint.

[0002]

2. Description of the Related Art Conventionally, as a technique for protecting a semiconductor fingerprint sensor from static electricity, for example, Japanese Patent Application Laid-Open No. 2000-2225 has been proposed.
As disclosed in Japanese Patent Laid-Open No. 55-55 "Fingerprint image acquisition device and fingerprint collation device", there is known a method of avoiding electrostatic breakdown by providing an operator having a discharge mechanism (hereinafter, referred to as a first method). Prior art). In addition, as a technology already commercialized, a fingerprint collation device that protects the semiconductor fingerprint sensor from static electricity and dust by providing a shutter on the semiconductor fingerprint sensor (for example, a fingerprint collation device FIU-710 manufactured by Sony Corporation). ) Is provided (hereinafter referred to as the second conventional technology).

[0003]

However, in the above-mentioned first prior art, whether or not the operator is touched depends on the intention of the operator, and when the semiconductor fingerprint sensor is touched without touching the operator. There is a problem that the sensor is more likely to be destroyed. Further, since the semiconductor fingerprint sensor is exposed, dust may be attached to the semiconductor fingerprint sensor or the semiconductor fingerprint sensor may be accidentally pulled out, and the sensor may be destroyed. Further, in the second conventional technique, it is necessary to provide a mechanism for holding the opened state after opening the shutter with a finger, and a mechanism for closing the shutter after a predetermined time, which causes a complicated structure and cost increase. was there. Further, in the above two conventional techniques, as disclosed in, for example, Japanese Patent Application Laid-Open No. 10-165382, “Biological Detection Device”, it is determined whether or not a living body is used by utilizing the fact that a finger touches an electrode during image reading. There is a problem that the method for detecting cannot be used.

Therefore, an object of the present invention is to provide a fingerprint collation device and a fingerprint image reading device capable of protecting a semiconductor fingerprint sensor from static electricity and dust with a simple structure. Another object of the present invention is to provide a fingerprint collation device and a fingerprint image reading device capable of detecting a living body.

[0005]

In order to achieve the above object, the present invention provides a fingerprint collation device having a semiconductor fingerprint sensor, wherein the semiconductor fingerprint sensor is housed and a finger can be inserted. It has a conductive opening / closing door which is provided in an opening portion of the storage portion and is opened by being pushed inside the storage portion by inserting a finger of an operator into the storage portion. Further, the present invention provides a fingerprint image reading apparatus equipped with a semiconductor fingerprint sensor, wherein the semiconductor fingerprint sensor is housed and a finger can be inserted therein. And a conductive opening / closing door which is opened by being pushed inside the storage portion by inserting into the storage portion.

In the fingerprint collation device of the present invention, the operator inserts a finger through the opening of the storage portion in which the semiconductor fingerprint sensor is arranged, so that the opening / closing lid is pressed and opened to bring the finger into contact with the semiconductor fingerprint sensor. Then, it becomes possible to read the fingerprint by the semiconductor fingerprint sensor and collate the fingerprint. At this time, the operator's finger is neutralized by the conductive opening / closing lid, and the semiconductor fingerprint sensor can be protected from electrostatic breakdown. Further, when the semiconductor fingerprint sensor is not used, the storage section can be closed with the opening / closing lid to prevent dust and the like from being generated in the semiconductor fingerprint sensor. Further, the opening / closing door is configured by a pair of door pieces having a double door structure, and the living body can be detected by detecting the signal of each door piece by the living body detection circuit.

In the fingerprint image reading apparatus of the present invention, when the operator inserts a finger through the opening of the accommodating portion in which the semiconductor fingerprint sensor is arranged, the opening / closing lid is pressed and opened to bring the finger into contact with the semiconductor fingerprint sensor. As a result, the fingerprint can be read by the semiconductor fingerprint sensor. At this time, the operator's finger is neutralized by the conductive opening / closing lid, and the semiconductor fingerprint sensor can be protected from electrostatic breakdown. Further, when the semiconductor fingerprint sensor is not used, the storage section can be closed with the opening / closing lid to prevent dust and the like from being generated in the semiconductor fingerprint sensor. Further, the open / close door is composed of a pair of door pieces having a double door structure, and the signal of each door piece is connected to the living body detection circuit, whereby it becomes possible to detect the living body.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a fingerprint collation device and a fingerprint image reading device according to the present invention will be described below. The embodiments described below are preferred specific examples of the present invention, and various technically preferable limitations are given. However, the scope of the present invention is not limited to the present invention in the following description. Unless otherwise stated, the present invention is not limited to these embodiments. FIG. 1 is a block diagram for explaining the function of the fingerprint collation device according to the first embodiment of the present invention. This fingerprint collation device includes a fingerprint image capturing unit 31,
Image A / D conversion unit 32, authentication unit 33, main CPU
It has 34 and a memory 35, and is connected to an external device 36. The function of each unit will be described below with reference to FIG.

First, the fingerprint image capturing unit 31 is, for example, a capacitance type fingerprint sensor using a semiconductor (see, for example, Japanese Patent Laid-Open No. 11-118415), and converts the unevenness of the fingerprint into an analog image signal. It is a thing. The image A / D conversion unit 32 is, for example, an IC that converts an analog signal into an 8-bit digital signal, and converts the analog image signal sent from the fingerprint image capturing unit 31 into a digital image signal. The authentication unit 33 performs a process of creating registered fingerprint data using the digital image signal sent from the image A / D conversion unit 32, and a matching process. The main CPU 34 controls the entire system such as control of the fingerprint image capturing unit 31, finger placement detection and determination of collation results, and control of data transmission / reception with the external device 36. The memory 35 is, for example, a non-volatile memory such as a flash memory, and stores the registered fingerprint data and the parameters of the fingerprint collation device. The external device 36 is, for example, a personal computer, and is connected to the fingerprint collation device via a communication line such as USB or RS232C, and transmits / receives data.

FIG. 2 is a top view showing the appearance of the fingerprint collation device shown in FIG. 3 is a cross-sectional view showing the structure of the fingerprint image capturing unit 31 of the fingerprint collation device shown in FIG.
3 shows a cross section taken along the line AA of FIG. 2. As shown in FIG.
In this fingerprint collating apparatus, a rectangular opening 41 into which the operator's finger 10 is inserted is provided on the upper surface of the housing 4.
1, an opening / closing door 1 having a double door structure is provided. That is, the opening / closing door 1 has a pair of door pieces 11A and 11B via hinges (not shown) provided on both right and left sides of the rectangular opening 41.
Rotatably attached to each door piece 11A, 1A
By pressing 1B lightly with your finger, the door piece has a symmetrical structure 1
The opening 41 is opened and closed by rotating 1A and 11B.

Further, as shown in FIG. 3, door pieces 11A, 1
A return spring 5 is provided between 1B and the inner wall of the housing 4. This return spring 5 is provided with a finger 10 for each door piece 11
A and 11B are in a contracted state when rotated inside the housing 4, and automatically extend when the finger 10 is removed,
Return each door piece 11A, 11B to the original position and open the opening 4
1 is to be closed. As such a return spring 5, for example, a leaf spring or the like having a simple structure can be used, and each of the door pieces 11A and 11B can be easily mounted by merely placing the finger 10 on the opening / closing door 1. It has a spring force enough to rotate. Also, each door piece 11A,
11B is made of a conductive material such as aluminum. Instead of forming the door pieces 11A and 11B themselves from a conductive material, the surface may be coated with a conductive film to have conductivity.

Then, such an opening 41 and the opening / closing door 1
The wiring board 2 is arranged inside the upper side wall of the housing 4 in which the semiconductor fingerprint sensor 3 is arranged. That is, in this fingerprint collation device, the inner space of the opening 41 of the housing 4 is configured as a storage portion for the semiconductor fingerprint sensor 3. The wiring board 2 is mounted with electronic components required as a fingerprint collation device. The semiconductor fingerprint sensor 3 reads the fingerprint image by directly touching the sensor surface with the finger 10, and for example, Sony CXA3271GE can be used.

Next, the structure and operating principle of the semiconductor fingerprint sensor 3 will be described. This semiconductor fingerprint sensor 3 has a sensor surface formed by providing an insulating film on the upper surface of metal electrodes arranged in an array. By placing a finger on the sensor surface, the metal electrode, the insulating film, and the finger are three. To form a capacitor. Here, the difference between the raised portion and the valley portion of the fingerprint is the difference in the distance between the finger, which is the electrode, and the metal electrode, which is the difference in the capacitance value of the formed capacitors. In addition, the capacitance value of the raised portion is determined by the dielectric constant of the insulating film, and the valley portion is additionally provided with an air layer. Therefore, the capacitance value of the raised portion and the valley portion becomes larger than the difference in distance. Therefore, the accumulated charge of each electrode is transferred and converted into a voltage to output the unevenness of the fingerprint as an electric signal.

However, since the electrode immediately below the insulating film on the surface of the sensor is an electrode, it is vulnerable to static electricity, and even static electricity charged on the human body may reach the electrode of the sensor and destroy the sensor. Therefore, in this example, the opening / closing door 1 is made electrically conductive and is connected to the GND (ground) 7 of the wiring board 2 to remove static electricity before the finger 10 touches the semiconductor fingerprint sensor 3. . That is, each of the door pieces 11A and 11B of the opening / closing door 1 is connected to the G of the wiring board 2 via the cable 6.
It is connected to ND7. As a result, when the finger 10 charged with static electricity touches the opening / closing door 1, the static electricity is discharged to the GND 7
It is designed to escape. GND7 is a reference GND of the electric circuit of the wiring board 2, and is the GND of the power supply.
Connected with.

The fingerprint sensor used in this example will be described below. FIG. 9 is an explanatory diagram showing the principle configuration of the fingerprint sensor, and FIG. 10 is a circuit diagram showing the internal circuit of the fingerprint sensor. As shown in FIG. 9, in this fingerprint sensor, a large number of metal electrodes 103 are arranged in an array on a silicon (Si) substrate 101 with an interlayer film 102 interposed therebetween, and the upper surface thereof is covered with an insulating film (Over Coat) 104. By placing the finger 105 directly on the upper surface of the insulating film 104, the unevenness due to the fingerprint is detected. That is, since the finger 105 is a conductor, by placing it on the upper surface of the insulating film 104, the metal electrode 103, the insulating film 104, and the finger 105 are placed.
Therefore, the capacitor 106 is formed by the three. The difference between the ridge 105A and the valley 105B of the fingerprint is the difference in the distance between the finger 105, which is an electrode, and the metal electrode 103, which is the difference in the capacitance value of the formed capacitor 106. Further, the capacitance value of the raised portion 105A is determined by the dielectric constant of the insulating film 104, but an air layer is added to the valley portion 105B, so that the raised portion 105A and the valley portion 1
The capacitance value of 05B becomes larger than the difference in distance. Therefore, according to such a principle, the amount of electric charge accumulated in each electrode 103 is different by applying a constant voltage to the metal electrode 103. Therefore, by transferring the electric charge and converting it into a voltage, the unevenness of the fingerprint is formed. Can be output as an electric signal.

Next, the circuit operation when converting the unevenness of the fingerprint into an electric signal will be described with reference to the circuit diagram shown in FIG. First, the circuit shown in FIG. 10 includes a sensor unit 120A that detects a capacitance value based on a fingerprint, a sense amplifier unit 120B that converts the capacitance value into a voltage signal, and an output unit 120C that amplifies and outputs the voltage signal. , And three differential amplifiers 121, 122, 123 for sense and output. Further, in FIG. 10, the capacitance Cs is the finger 10
5 and the capacitor 106 formed between the metal electrode 103
The capacitance Cp is a parasitic capacitance formed between the metal electrode 103 and the silicon substrate 101. The capacitance Cp ′ is a capacitance (Cp≈Cp ′) for the purpose of canceling the parasitic capacitance Cp, and the capacitances Ch1 and Ch2 are hold capacitances. The capacitors Cf1 and Cf2 are feedback capacitors that determine the gain of each amplifier. Swr, Swe,
Sw1 to Sw11 are switches, and
The node voltage V has three levels VH, VM, and VL, and has a relationship of VH-VM≈VM-VL.

Next, the operation of such a circuit will be described. In addition, each switch Swr, Swe, Sw1 to Sw
11 defaults all off states. (1) From the default state, first, the switches Sw1 and S
The w4 and Swr are turned on, and the connection point Vcel of the capacitors Cs and Cp is set to VH. Here, the accumulated charge at the connection point Vcel is (Cs + Cp) VH. (2) After that, the switches Sw1 and Swr are turned off. (3) Next, the switches Sw11 and Sw3 are turned on, and the connection point Vdmy between the capacitor Cp ′ and the switch Sw3 is set to VL.
And Here, the accumulated charge at the connection point Vdmy is Cp′V
It becomes L. (4) After that, the switches Sw3 and Sw11 are turned off. (5) Next, the switch Sw2 is turned on, and the connection point Vsl between the amplifier 121 and the switches Swr and Sw3 is set to VM. (6) After that, the switch Sw4 is turned off.

(7) Next, the switches Swr, Sw3, S
Turn on w5. At this time, from the connection points Vcel and Vdmy to the connection point Vsl
The charge moving to (actually between the capacitors) is (Cs + Cp) (VH-VM) -Cp '(VM-VL) .apprxeq.Cs (VH-VM) (Equation 1) Therefore, the gain of the sense amplifier unit 120B is Since it is determined without depending on the parasitic capacitance, the required dynamic range of the signal can be widened. Vsns = VM-Cs (VH-VM) / Cf1 (Equation 2) Then, in the capacitor Ch1, the voltage Vs determined by this Equation 2 is applied.
ns is accumulated. (8) After that, the switch Sw5 is turned off.

(9) Next, the switch Sw6 is turned on to set the voltage Voi on the input side of the capacitor Cf2 to VOS. (10) After that, the switch Sw6 is turned off. (11) Next, the switches Swe and Sw7 are turned on. At this time, the amount of charge transferred from the capacitance Ch1 to the capacitance Cf2 is (VOS-Vsns) Ch1. This allows
The voltage of the output Voo of the capacitance Cf2 is determined, and the capacitance Ch2
Accumulated in. Then, this voltage is applied to the Buf amplifier 123.
Is output to the output terminal Aout via.

Next, the operation of the fingerprint collation device having such a configuration will be described. First, as shown in FIG. 3, the opening / closing door 1 is always closed by the force of the return spring 5 before placing the finger 10. Next, in order to place the finger 10 on the semiconductor fingerprint sensor 3, the opening / closing door 1 is first opened with the finger 10 as shown in FIG. At this time, even when the finger 10 is electrostatically charged, the static electricity of the finger 10 is
It is transmitted in the order of door 1 → cable 6 → GND7, and static electricity is discharged to the GND of the power supply through the GND of the circuit. Therefore, as shown in FIG.
When touching, the finger 10 is always destaticized and the finger 1
There is no risk of destroying the semiconductor fingerprint sensor 3 with static electricity of 0. Then, when the finger 10 is released, the force of the return spring 5 causes
The opening / closing door 1 is closed by the operation of FIG. 5 → FIG. 4 → FIG. As a result, before the next time, the semiconductor fingerprint sensor 3 is touched, the opening / closing door 1 is always touched, and the charged finger 10 does not touch the semiconductor fingerprint sensor 3.

Next, a fingerprint collation device according to a second embodiment of the present invention will be described. This fingerprint collating device is disclosed in, for example, Japanese Patent Laid-Open No. 10-165382 entitled "Biometric detection device".
The living body detection circuit that detects a living body by touching the two measurement electrodes with the finger 10 as described in 1) is mounted. In this case, the door pieces 11A, 1 of the opening / closing door 1 described above
It can be realized by using 1B for two measuring electrodes. FIG. 6 is a cross-sectional view showing the structure of the fingerprint image capturing section of the fingerprint collating apparatus according to the second embodiment.
The part corresponding to the -A line cross section is shown. Also, FIG.
FIG. 7 is a block diagram showing a connection structure between the fingerprint matching device shown in FIG. 6 and a living body detection circuit.

First, the configuration newly added in the present embodiment will be described with reference to FIGS. 6 and 7. In addition,
The same components as those shown in FIGS. 1 to 5 will be described using the same reference numerals. The cable 21 is a conductor cable that connects one door piece 11A of the opening / closing door 1 and one input terminal 1 of the living body detection circuit 23. Also, the cable 22
Is a conductor cable that connects the other door piece 11B of the opening / closing door 1 and the other input terminal 2 of the living body detection circuit 23. The diode D1 is a zener diode for overvoltage protection connected between the cable 21 and GND7.
The diode D2 is a zener diode for overvoltage protection connected between the cable 22 and GND7. Further, the biological detection circuit 23 is disclosed in Japanese Patent Laid-Open No. 10-1653.
The circuit portion other than the measurement electrode of No. 82 is shown. The living body detection circuit 23 includes an oscillation circuit whose oscillation frequency changes according to the electrostatic capacitance between the input terminal 1 and the input terminal 2 and a counter for measuring the oscillation frequency, and sends the measured frequency to the main CPU 34. Therefore, it is detected whether or not it is a living body.

Next, the operation will be described. First, when the charged finger 10 touches the door 1 shown in FIG. 6, the static electricity flows from the door 1 to the cable 21 → zener diode D1 → GND7 or the cable 22 → zener diode D2 → GND7 and is discharged to GND7. It Therefore, the finger 10 is discharged, and there is no danger of destroying the semiconductor fingerprint sensor 3 even if it touches the semiconductor fingerprint sensor 3. Next, the finger 10 touches the semiconductor fingerprint sensor 3, and the open / close door 1 and the finger 10 are constantly in contact with each other while the fingerprint image is read. Therefore, it is possible to always determine whether or not a living body is present by the living body detection circuit 23, and it is possible to perform control so that a camouflaged finger does not read an image.

Next, a living body detection circuit 2 utilizing electrostatic capacitance
A specific configuration example of 3 and the operating principle will be described. Figure 8
FIG. 3 is a block diagram showing a circuit configuration example of a living body detection circuit 23 used in this example. This living body detection circuit is an oscillation circuit using a Schmitt inverter, and includes an input terminal 1, an input terminal 2, a counter 42, and a Schmitt inverter IC4.
3, resistor R44 and the like. Input terminal 2 is G
Input terminal 1 is grounded to ND, Schmitt inverter IC
Connect to Vin of 43. Further, the output voltage Vout of the Schmitt inverter IC43 is fed back to the input terminal of the Schmitt inverter IC43 via the resistor R44. The output voltage Vout is also connected to the input terminal IN of the counter 42, and the output terminal OUT of the counter 42 is connected to the main CPU 34. Then, if a capacitor C is provided between the input terminal 1 and the input terminal 2,
When x is connected, it oscillates, and Schmitt inverter IC43
A square wave is output from the Vout terminal of. The frequency of this square wave is read by the counter 42 to determine whether or not it is a living body.

Next, the structure of each part of the living body detection circuit 23 will be described. First, the resistor R44 has a relatively large resistance value, for example, a resistance value of about 100 kΩ.
The counter 42 is a counter that measures how many square waves are input to the input terminal IN at a certain fixed time. Then, the count number measured in the fixed time is output from the output terminal OUT. The Schmidt inverter IC43 is an inverter having a hysteresis characteristic. Here, the inverter outputs a potential with the input inverted, and if the input voltage Vin is Low, the output voltage V
The output voltage Vout is High, and the output voltage Vout is Low when the input voltage Vin is High.

The hysteresis characteristic is also called a hysteresis phenomenon,
It is a phenomenon in which the state of something is not determined only by the conditions in which it is currently placed, but depends on the history of the state that it has undergone in the past. As an example of the operation, the threshold value for the Schmitt inverter IC43 to determine that the input voltage Vin has changed from Low to High is 2.5V, but the threshold value to determine that the input voltage Vin has changed from High to Low is 2.V. It operates with the characteristic of trying to maintain the past state as much as possible, such as 0V. Such characteristics are originally intended to prevent malfunction due to external noise, but they are also used as an oscillation circuit. Less than,
The threshold voltage for determining that the input voltage Vin has changed from Low to High is V (L → h), and the input voltage Vin is H
The threshold voltage for determining that the voltage has changed from high to low is V
This will be described as (h → L).

Next, the specific operation of the living body detecting circuit 23 will be described. First, immediately after the Schmidt inverter IC43 is powered on, Vin = Low since no charge is stored in the capacitor Cx. here,
Since IC43 is an inverter, Vout = High. Then, since the output voltage Vout becomes High,
Charging of the capacitor Cx starts through the resistor R44.
The resistor R44 is for controlling the amount of electric charge with which the capacitor Cx is charged so that this charging does not end instantaneously. Therefore, the input voltage Vin gradually rises, and when the threshold value V (L → h) is reached, the output voltage Vout of the Schmitt inverter IC43 is inverted and becomes Low. Then, discharging of the capacitor Cx starts, a current flows through the resistor R44, and the input voltage Vin gradually decreases. Then, when the input voltage Vin falls to the threshold value V (h → L), the output voltage Vout is inverted and becomes High.
It becomes h and rises again. After that, repeat this operation,
A square wave oscillating voltage appears at the output. If the Schmitt inverter IC43 does not have a hysteresis characteristic, the threshold V (L → h) and the threshold V (h → L) have the same potential, so that the oscillation occurs at a high frequency regardless of the capacitance value of the capacitor Cx. In this circuit, the Schmitt inverter IC43 must have hysteresis characteristics.

As described above, by connecting the capacitor Cx between the input terminal 1 and the input terminal 2, oscillation is generated,
The oscillation potential is output from the output terminal of the Schmitt inverter IC43. Therefore, if the object in contact between the input terminal 1 and the input terminal 2 has a capacitance like the capacitor Cx, an oscillation frequency corresponding to the capacitance can be obtained. That is, since electrostatic capacitance exists between two points on the human finger, a square wave corresponding to the electrostatic capacitance is generated. However, paper and OHP sheets,
Capacitance is different between a fingerprint that can be a pseudo-fingerprint such as silicon and a fingerprint. For example, the capacitance of paper is 1/10 of that of a finger.
˜1 / 1000, and the electrostatic capacity of the OHP sheet and silicon is almost zero. Therefore, this oscillation frequency is also different between the finger and other objects, and it is possible to detect whether or not the subject is a living body. Therefore, this difference in frequency is measured by the frequency counter 42, and the main CPU
By sending to 34, the final judgment becomes possible.

Next, a specific procedure of the authentication method in this example will be described. Generally, there are various methods such as feature point extraction, direction code matching, and pattern matching in fingerprint collation methods, and the feature point extraction method that is most often used will be described. 11A and 11B are explanatory diagrams showing a specific example of a local fingerprint. Figure 11 shows the fingerprint.
The point (end point) where the ridge as shown in FIG.
1 (B) are interspersed with branching points (branch points). It is known that these points are called characteristic points, and the arrangement is different from person to person. Therefore, it is possible to determine whether or not the fingerprints are the same by quantitatively evaluating the degree of coincidence of the positional relationship between the characteristic points scattered.

Next, FIG. 12 is a flow chart showing a fingerprint registration operation, and FIG. 13 is a flow chart showing a fingerprint collation operation. First, in the fingerprint registration operation (FIG. 12), the fingerprint image is captured (gray gradation image) in step S101, and the gray gradation image is converted into a binary image in step S102. Then, in S103, feature points are extracted from the binary image. Next, in step S104, the number of extracted feature points is calculated, and it is determined whether or not there are more than a preset threshold value. Here, if there is a number equal to or greater than the threshold value, the process proceeds to step S105, and if there is no number equal to or greater than the threshold value, the process proceeds to step S101. This is because it is impossible to determine whether or not the fingers are the same finger unless a certain number or more of feature points are compared, and therefore registration cannot be performed when the number of feature points is less than that number. Next, in step S105, the positional relationship of the extracted feature points is converted into data, and registration data is created.
This completes the fingerprint registration operation.

Next, in the fingerprint collation operation (FIG. 13), the fingerprint image is captured (gray gradation image) in step S111, and the gray gradation image is converted into a binary image in step S112. Then, in step S113, feature points are extracted from the binary image. Next, in step S114, the positional relationship of the extracted feature points is converted into data, compared with registered data, and the number of coincidences is calculated. Then, it is determined whether or not the number of coincidences exceeds a preset threshold value, and if it exceeds, it is determined that they are the same fingerprint (step S115). Also,
If the number of matches is less than or equal to a preset threshold, it is determined that the fingerprints are different (step S116). This ends the fingerprint collation operation.

As described above, the fingerprint collation device according to each embodiment of the present invention can obtain the following effects. (1) Before the finger touches the semiconductor fingerprint sensor, it always touches the open / close door with the double door structure, so even if the finger is charged with static electricity, the static electricity is removed, and as a result, there is no danger of destroying the semiconductor fingerprint sensor by static electricity. . (2) Unless the opening / closing door of the double door structure is opened with a finger, the opening / closing door is closed, so that dust and the like can be prevented from adhering to the semiconductor fingerprint sensor. (3) As a static electricity protection for the conventional semiconductor fingerprint sensor, in the case of the fingerprint collation device using the conductive switch, it is necessary to perform two operations of pushing the switch and then placing the finger on the sensor. Further, in the case of a fingerprint collation device having a shutter for electrostatic protection, it is necessary to open the shutter and put a finger. However, in the case of a fingerprint collating apparatus having an opening / closing door having a double door structure, the operation of placing a finger directly opens the door, so that the operator only needs to perform one operation and the operability is improved.

(4) In the case of the fingerprint collation device having the conventional shutter, it is necessary to provide a mechanism for holding the shutter in the opened state when the shutter is opened. If such a mechanism is not provided, there is a problem that it is difficult to operate because the shutter closes before the finger is placed. However, in the case of the open / close door having the double door structure, the operation of placing the finger directly opens the door, so that a mechanism for holding the open state is unnecessary and the problem of difficulty in operation does not occur. (5) Since the finger is always in contact with the door while the finger is placed on the semiconductor fingerprint sensor, the fact that the finger is in contact with the electrode is utilized as in the case of the "living body detection device" in Japanese Patent Laid-Open No. 10-165382. It is easy to add a living body detection function.

Although the above description has been made with respect to a fingerprint collation device having a fingerprint collation function, the present invention can be similarly applied to a fingerprint image reading device having no collation function as described above. Is. Further, in the above-described embodiment, as the optimum example of the present invention, the double door open / close door is provided. However, in order to eliminate static electricity and prevent dust, it is sufficient to have one conductive open / close door. Such effects can be obtained, and such a configuration is also included in the present invention.

[0035]

As described above, in the fingerprint collation device of the present invention, when the operator inserts his / her finger through the opening of the accommodating portion in which the semiconductor fingerprint sensor is arranged, the opening / closing lid is pressed and opened to open the finger. By contacting the semiconductor fingerprint sensor, the semiconductor fingerprint sensor can read the fingerprint and collate the fingerprint. Therefore, at the time of fingerprint collation, the operator's finger is neutralized by the conductive opening / closing lid, so that the semiconductor fingerprint sensor can be protected from electrostatic breakdown. Further, when the semiconductor fingerprint sensor is not used, the storage section can be closed with the opening / closing lid to prevent dust and the like from being generated in the semiconductor fingerprint sensor. Further, the opening / closing door is configured by a pair of door pieces having a double door structure, and the living body can be detected by detecting the signal of each door piece by the living body detection circuit.

Further, in the fingerprint image reading apparatus of the present invention, the operator inserts his / her finger into the opening of the accommodating portion in which the semiconductor fingerprint sensor is arranged, so that the opening / closing lid is pressed and opened to turn the finger into the semiconductor fingerprint sensor. By bringing them into contact with each other, the fingerprint can be read by the semiconductor fingerprint sensor. Therefore, when the fingerprint is read, the operator's finger is neutralized by the conductive opening / closing lid, and the semiconductor fingerprint sensor can be protected from electrostatic breakdown. Further, when the semiconductor fingerprint sensor is not used, the storage section can be closed with the opening / closing lid to prevent dust and the like from being generated in the semiconductor fingerprint sensor. Further, the open / close door is composed of a pair of door pieces having a double door structure, and the signal of each door piece is connected to the living body detection circuit, whereby it becomes possible to detect the living body.

[Brief description of drawings]

FIG. 1 is a block diagram illustrating a function of a fingerprint matching device according to a first embodiment of the present invention.

FIG. 2 is a top view showing the appearance of the fingerprint matching device shown in FIG.

3 is a cross-sectional view taken along the line AA of FIG. 2 showing a structure of a fingerprint image capturing section of the fingerprint collation device shown in FIG.

4 is a cross-sectional view taken along the line AA of FIG. 2 showing the operation of the fingerprint image capturing section shown in FIG.

5 is a cross-sectional view taken along the line AA of FIG. 2 showing the operation of the fingerprint image capturing section shown in FIG.

FIG. 6 is a cross-sectional view showing a structure of a fingerprint image capturing section of the fingerprint collation device according to the second embodiment of the present invention.

7 is a block diagram showing a state in which a living body detection circuit is connected to the fingerprint matching device shown in FIG.

8 is a block diagram showing a circuit configuration example of a living body detection circuit 23 shown in FIG.

FIG. 9 is an explanatory diagram showing a basic configuration of a fingerprint sensor.

10 is a circuit diagram showing an internal circuit of the fingerprint sensor shown in FIG.

FIG. 11 is an explanatory diagram showing a specific example of a local fingerprint.

FIG. 12 is a flowchart showing a fingerprint registration operation in the fingerprint matching device shown in FIG.

13 is a flowchart showing a fingerprint matching operation in the fingerprint matching device shown in FIG.

[Explanation of symbols]

1 ... Opening / closing door, 2 ... Wiring board, 3 ... Semiconductor fingerprint sensor, 4 ... Housing, 5 ... Return spring, 6 ... Cable, 7
...... GND, 10 ...... fingers, 11A, 11B ...... door pieces, 4
1 ... Opening part, 31 ... Fingerprint image capturing part, 32 ... Image A / D conversion part, 33 ... Authentication part, 34 ... Main CP
U, 35 ... Memory, 36 ... External device.

Claims (14)

[Claims] 1. A fingerprint collation apparatus including a semiconductor fingerprint sensor, wherein a storage unit that stores the semiconductor fingerprint sensor and into which a finger can be inserted, and an opening provided in the storage unit are provided. A fingerprint collation device, comprising: a conductive opening / closing door that is opened by being pushed into the storage section by being inserted into the storage section. 2. The opening / closing door has a pair of door pieces provided on both left and right sides of the storage section, and each door piece opens and closes in a double door structure. Fingerprint matching device. 3. The fingerprint collation according to claim 1, wherein the opening / closing door is biased by a return spring means for returning to a closed position when the operator's finger is pulled out from the storage section. apparatus. 4. The fingerprint collation apparatus according to claim 1, wherein the opening / closing door is made of a conductive material. 5. The fingerprint collation device according to claim 1, wherein the opening / closing door has a surface coated with a conductive film. 6. The fingerprint collation device according to claim 1, wherein the door is connected to a GND line in the device. 7. A conductive part of each door piece of the opening / closing door is connected to an input terminal of a living body detection circuit, and a conductive part of each door piece of the opening / closing door is connected via an overvoltage protection means.
The device is connected to the ND line.
The fingerprint matching device described. 8. A fingerprint image reading apparatus equipped with a semiconductor fingerprint sensor, wherein the semiconductor fingerprint sensor is housed and a finger can be inserted, and an operator's finger is provided in an opening of the housing. A fingerprint image reading device, comprising: a conductive opening / closing door that is opened by being pushed inside the storage portion by inserting the. 9. The opening / closing door has a pair of door pieces provided on both left and right sides of the storage portion, and each door piece opens and closes in a double door structure. Fingerprint image reader. 10. The opening / closing door is biased by a return spring means for returning the door to a closed position when an operator's finger is pulled out from the storage section.
The fingerprint image reading device described. 11. The fingerprint image reading device according to claim 8, wherein the opening / closing door is made of a conductive material. 12. The fingerprint image reading device according to claim 8, wherein the opening / closing door has a surface coated with a conductive film. 13. The fingerprint image reading device according to claim 8, wherein the opening / closing door is connected to a GND line in the device. 14. A conductive portion of each door piece of the open / close door is connected to an input terminal of a living body detection circuit, and a conductive portion of each door piece of the open / close door is connected to a GND line via an overvoltage protection means. 9. The fingerprint image reading device according to claim 8, which is connected.