KR20030093841A - System and Method of Finger-print Recognition - Google Patents

Abstract

The present invention relates to a fingerprint recognition system and method for obtaining a fingerprint image using a thermal resistance sensor.

In the conventional optical fingerprint recognition system, since the optical device and the photoelectric device are required to be bulky, there is a problem in that the use range is limited, and the capacitive fingerprint recognition system has a dry surface skin of a finger to be contacted. In this case, the conductivity is reduced, so the fingerprint image is not detected. The sensor is very sensitive to the pressure of the finger and the electric field generated in the natural world, and the sensor may be destroyed by the electrostatic discharge on the finger surface and the contact surface of the sensor. have.

According to the present invention, by obtaining a fingerprint image using a thermal resistance sensor, it is possible to increase the reliability of authentication and increase durability. In addition, by extracting feature points from the thermal resistance sensor that receives the fingerprint image and the input fingerprint image, and configuring peripheral circuits that perform authentication and inquiry using the extracted feature points as one chip, the size of the system can be reduced. It can be applied to various fields regardless of volume.

Description

System and Method of Finger-print Recognition

The present invention relates to a fingerprint recognition system and method, and more particularly, to a fingerprint recognition system and method for obtaining a fingerprint image using a heat resistance sensor.

In general, fingerprints are one of the physical characteristics of a person, and each person has a characteristic that each person is different from one another and does not change for a lifetime unless damaged. Therefore, fingerprints have been widely used as a means of personal authentication for a long time.

The fingerprint recognition system for identifying individuals using such fingerprints enables identification of fingerprints by examining an average of 100 feature points per finger, and compares reference data with input fingerprint data to match a certain number or more. If you do so, the same fingerprint will be judged.

As such, the fingerprint recognition system is now being used only in special security devices, and as the low-cost sensors are used, the range of use is gradually increasing, such as those used in peripheral devices of the PC such as a keyboard and a mouse.

Therefore, there is a need for a convenient, small-scale, low-power, low-cost fingerprint sensor, and the fingerprint detection methods studied to date can be broadly classified into optical, capacitive, and thermal sensing technologies.

The above-described optical method is a method mainly used in the early days, and when the surface of the finger is illuminated by using visible light or infrared light, the reflected light is captured by the photoelectric device to obtain a fingerprint image. Since it becomes necessary and bulky, there is a problem that the use range is limited.

In addition, the capacitance type uses the principle that the capacitance varies depending on the distance between the two electrodes, and the difference between the capacitance according to the distance between the sensing electrode and the valley of the fingerprint and the capacitance according to the distance between the sensing electrode and the floor of the fingerprint It is possible to implement a sensor without additional devices by using only a CMOS (Complementary Metal Oxide Semiconductor) process by obtaining a fingerprint image, but the conductivity of the surface of the contacted finger becomes poor, so that the fingerprint image cannot be detected. There is this. In addition, the sensor is very sensitive to the pressure of the finger and the electric field in the natural world, which can destroy the sensor due to electrostatic discharge on the surface of the finger and the contact surface of the sensor. There is a problem in that the distance difference is smaller than the actual size, so that accurate fingerprint images cannot be obtained.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object thereof is to provide a fingerprint recognition system and method for increasing the reliability of authentication and increasing durability by acquiring a fingerprint image using a heat resistance sensor. .

In addition, another object of the present invention is to extract a feature point from the thermal resistance sensor and the fingerprint image received from the fingerprint image, and to configure a peripheral circuit for performing authentication and inquiry by using the extracted feature point as a single chip, the system To reduce the size of the

1 is a diagram showing the electrical configuration of the fingerprint recognition system according to the present invention.

2 is a cross-sectional view showing the structure of a heat resistance cell constituting a heat resistance sensor.

Figure 3 is a perspective view showing the structure of the heat resistance cell.

4 is a perspective view showing a form in which thermal resistance cells are integrated.

5 is a perspective view showing another fingerprint recognition system in the present invention.

6 and 7 are flowcharts for explaining another fingerprint recognition method according to the present invention.

*** Explanation of symbols for the main parts of the drawing ***

100. Fingerprint identification system 110. Thermal resistance sensor, 110a. Heat resistance cell,

115. Filter section 120. Amplifier section 125. A / D conversion unit,

130.RAM, 135. ROM, 135a. Image Converter,

135b. Feature point extraction unit, 140. Flash memory section 145. Analytical Controls,

150. DMA, 155. Serial Communication Unit, 160. Parallel communication unit,

165. Central Processing Unit

Fingerprint recognition system according to the present invention for achieving the above object, by detecting the difference between the heat of the portion where the valley of the fingerprint and the portion in contact with the surface with a resistance, and the resistance difference of each detected portion A thermal resistance sensor for converting into an electrical signal and obtaining a fingerprint image in the form of an analog signal; A / D conversion means for filtering and amplifying a fingerprint image received through the thermal resistance sensor and converting the fingerprint image into a digital signal; An image converter converting the digital signal into a normal image signal; A feature point extractor for extracting feature points from the normal image signal; A first memory unit configured to store a normal image signal normalized by the image converter, a feature point extracted by the feature point extractor, and user information corresponding to the normal image signal and the feature point in a database form; An analysis collation unit for normalizing the image conversion unit and comparing the feature point extracted by the feature point extracting unit with fingerprint information stored in the first memory unit to determine whether the user is present; A second memory unit for temporarily storing the digital signal converted by the A / D conversion means; Memory access means for directly accessing the second memory unit; A communication unit which transmits a result of processing and fingerprint information determined by the analysis control unit to the outside or receives a signal from the outside; After converting an analog fingerprint image received through the thermal resistance sensor into a digital signal, converting the digital signal into a normal image signal, extracting feature points, and then comparing the fingerprint image with the fingerprint information previously stored in the first memory unit. It is provided with a control unit for controlling the whole system to determine whether or not through comparison.

Here, the thermal resistance sensor, a plurality of thermal resistance cells are made of an integrated, each thermal resistance cell, the insulating layer is provided on the silicon substrate for insulating thermal and electrical signals; A heat resistance layer provided on the insulating layer and having a different resistance by heat; It is provided on the heat resistance layer is characterized in that it comprises a protective silicon layer which transmits infrared rays but keeps the heat resistance layer from the outside.

Further, the heat resistance layer is implemented in an S-shape in order to obtain the maximum resistance difference, and is characterized in that the middle portion is formed to be thick in order to sense heat well.

In addition, the components may be integrated into one chip using a CMOS process.

On the other hand, the fingerprint recognition method according to the present invention, the registration process of extracting the normal image signal and the feature point from the fingerprint image received through the heat resistance sensor, and one-to-one correspondence with the user information stored in the memory unit; After extracting the normal image signal and the feature point from the fingerprint image received through the thermal resistance sensor, and comparing the extracted feature point with the fingerprint information pre-stored in the memory unit comprises the authentication process to determine the identity.

Here, the registration process, the step of receiving information on the user to register the fingerprint; Receiving a fingerprint image through a heat resistance sensor; Filtering and amplifying the fingerprint image and converting the fingerprint image into a digital signal; Converting the digital signal into a normal image signal and extracting feature points from the normal image signal; And storing the regular image signal, the feature point, and the user information in a database form in a one-to-one correspondence.

The authentication process may include receiving a fingerprint image through a heat resistance sensor; Filtering and amplifying the fingerprint image and converting the fingerprint image into a digital signal; Converting the digital signal into a normal image signal and extracting feature points from the normal image signal; Comparing the extracted feature points with fingerprint information previously stored in the memory to determine whether matching fingerprint information exists; If the matching fingerprint information exists, authenticating the user who inputs the fingerprint as a legitimate user; If the matching fingerprint information does not exist, it is characterized in that it comprises the step of authenticating the user who entered the fingerprint as an invalid user.

Hereinafter, a fingerprint recognition system and method according to an exemplary embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is a road showing the electrical configuration of the fingerprint recognition system according to the present invention, a thermal resistance sensor 110, a filter 115, an amplifier 120, an A / D (Analog to Digital) conversion unit (125), RAM (Random Access Memory) 130, flash memory unit 140, ROM (Read Only Memory) 135, central processing unit 165, analysis control unit 145, A direct memory access (DMA) 150, a serial communication unit 155, and a parallel communication unit 160 are provided.

In such a configuration, the thermal resistance sensor 110 detects the difference between the heat of the portion where the valley of the fingerprint in contact with the surface and the floor is located as a resistance, and the resistance difference of each detected portion as an electrical signal. By converting, a fingerprint image in the form of an analog signal is obtained.

In the heat resistance sensor 110, titanium (Ti) whose resistance is changed by heat using a heat resistance method is finely integrated on a silicon substrate in a size of approximately 30 μm, and the pixel size is approximately 30 μm × 30. It is about 750 DPI (Dot Per Inch), and has a 300 × 300 pixel class.

2 is a cross-sectional view showing the structure of a heat resistance cell constituting a heat resistance sensor, each heat resistance cell (110a) is provided on the silicon substrate (a) and the insulating layer (b) for insulating thermal and electrical signals; The insulating layer (b) is provided on the titanium (Ti) metal layer (c), the resistance of which is changed by heat, and the titanium (Ti) metal layer (c) is provided on the infrared ray, but the titanium metal layer (Ti) from the outside (c) It is provided with an N-type silicon layer (d) to protect the), when the heat is applied to measure the voltage across the titanium (Ti) metal layer (c).

As described above, the titanium (Ti) metal layer (c) has to be increased in length in order to increase the resistance difference as much as possible in a small space, and as shown in FIG. It is thicker than other parts.

As shown in FIG. 4, the heat resistance cells 110a are finely integrated with a size of 0.3 μm on the substrate to form the heat resistance sensor 110.

On the other hand, the filter unit 115 equalizes the voltage measured by the thermal resistance sensor 110 to even the fingerprint image in the form of an analog signal, and the amplifier unit 120 converts the analog signal filtered by the filter unit 115 into a digital signal. Amplify to suit the conversion.

The A / D converter 125 converts the analog signal amplified by the amplifier 120 into a digital signal.

The RAM 130 temporarily stores the digital fingerprint signal converted by the A / D converter 125.

The ROM 135 extracts a feature point of the fingerprint from the image converter 135a for converting the digital fingerprint signal stored in the RAM 130 into a normal image signal, and the image signal normalized by the image converter 135a. It comprises a feature point extraction unit 135b.

The flash memory unit 140 stores a fingerprint image normalized by the image converter 135a, a feature point of the fingerprint extracted by the feature point extractor 135b, and user information corresponding to the image and feature point of the fingerprint in a database form. do.

The analyzing and contrasting unit 145 determines the identity by comparing the fingerprint information extracted by the feature point extracting unit 135b after being normalized by the image converter 135a with the fingerprint information stored in the flash memory unit 140.

The DMA 150 is input through the thermal resistance sensor 110 to directly access fingerprint information stored in the RAM 130 from the outside.

The serial communication unit 155 and the parallel communication unit 160 transmit the processing result and the fingerprint information that are compared and judged by the analysis control unit 145 to the outside or receive a signal from the outside.

The central processing unit 165 controls the entire system, converts the fingerprint image received through the thermal resistance sensor 110 into a digital signal, stores it in the RAM 130, and converts the stored digital fingerprint signal into a normal image signal. The feature point of the fingerprint is extracted from the normalized fingerprint image and compared with the previously stored data to determine whether or not the user.

As shown in FIG. 5 using the CMOS process, the components described above are integrated into one chip, thereby simplifying the manufacturing process of the fingerprint recognition system, reducing volume and power consumption, and reducing the risk of malfunction. To reduce it.

6 and 7 are flowcharts illustrating a fingerprint recognition method according to the present invention.

The fingerprint recognition method according to the present invention extracts an image and a feature point from a fingerprint image received through the heat resistance sensor 110, registers one-to-one correspondence with corresponding user information, and stores the same through the heat resistance sensor 110. After the image and the feature point is extracted from the received fingerprint image, the extracted feature point is compared with the fingerprint information pre-registered in the flash memory unit 140 through an enrollment process.

First, referring to the registration process, as shown in FIG. 6, when a fingerprint image of a user who receives user information for registering a fingerprint and inputs user information through the thermal resistance sensor 110 is input, a filter is input. In the unit 115, the analog image format fingerprint image received through the thermal resistance sensor 110 is filtered and evenly applied to the amplification unit 120 to convert the analog signal format fingerprint signal into a digital signal suitable for digital signal conversion. Amplify to level (S10, S12, S14).

The fingerprint image amplified by the amplifying unit 120 through the above-described process S14 is converted into a digital signal by the A / D converter 125, stored in the RAM 130, and stored in the RAM 130. The fingerprint signal is converted into a normal image signal by the image converter 135a (S16 and S18).

Thereafter, the feature point extractor 135b extracts the feature point of the fingerprint from the image signal normalized by the image converter 135a through step S18 (S20), and the fingerprint image normalized in step S18, and The feature point of the fingerprint and the user information input in the process S10 are stored in a database form in the flash memory unit 140 in a one-to-one correspondence (S22).

As described above, after receiving and storing the fingerprint information of the user through the registration process, the user authentication is performed through the authentication process, as shown in FIG. 7, through the thermal resistance sensor 110. When the fingerprint image of the analog signal format is input, the filter unit 115 filters the fingerprint image of the analog signal format received through the thermal resistance sensor 110 and evens it, and then applies it to the amplifying unit 120 to apply the analog signal format. Amplify the fingerprint signal to a digital signal level suitable for digital signal conversion (S30, S32).

Through the process S32, the fingerprint image amplified by the amplification unit 120 is converted into a digital signal by the A / D converter 125, stored in the RAM 130, and the image of the fingerprint signal stored in the RAM 130. The conversion unit 135a converts the image into a normal image signal (S34 and S36).

Thereafter, the feature point extractor 135b extracts the feature point of the fingerprint from the image signal normalized by the image converter 135a through the process S36 (S38), and stores the extracted feature point in the flash memory unit 140. Compared with the fingerprint information, it is determined whether there is fingerprint information that matches the extracted feature point (S40, S42).

If there is fingerprint information that matches the extracted feature point as a result of the determination in step S42, the user who inputs the fingerprint in step S30 is authenticated as a legitimate user (S44).

On the other hand, if the fingerprint information corresponding to the extracted feature point does not exist as a result of the determination in step S42, the user who inputs the fingerprint in step S30 is authenticated as an invalid user (S46).

The fingerprint recognition system and method of the present invention are not limited to the above-described embodiments, and may be modified and implemented in various ways within the scope of the technical idea of the present invention.

According to the fingerprint recognition system and method of the present invention as described above, by using the thermal resistance sensor to obtain a fingerprint image, it is possible to increase the reliability of authentication and increase durability.

In addition, by extracting feature points from the thermal resistance sensor that receives the fingerprint image and the input fingerprint image, and configuring peripheral circuits that perform authentication and inquiry using the extracted feature points as one chip, the size of the system can be reduced. It can be applied to various fields regardless of volume.

Claims (8)

Heat resistance sensor that detects the difference in heat between the part where the valley of the fingerprint is in contact with the surface and the part where the floor is located with a resistance, and converts the resistance difference between each detected part into an electric signal to obtain an analog signal type fingerprint image Wow; A / D conversion means for filtering and amplifying a fingerprint image received through the thermal resistance sensor and converting the fingerprint image into a digital signal; An image converter converting the digital signal into a normal image signal; A feature point extractor for extracting feature points from the normal image signal; A first memory unit configured to store a normal image signal normalized by the image converter, a feature point extracted by the feature point extractor, and user information corresponding to the normal image signal and the feature point in a database form; An analysis collation unit for normalizing the image conversion unit and comparing the feature point extracted by the feature point extracting unit with fingerprint information stored in the first memory unit to determine whether the user is present; After converting an analog fingerprint image received through the thermal resistance sensor into a digital signal, converting the digital signal into a normal image signal, extracting feature points, and then comparing the fingerprint image with the fingerprint information previously stored in the first memory unit. Fingerprint recognition system comprising a control unit for controlling the entire system to determine whether or not through comparison. The method of claim 1, wherein the thermal resistance sensor, A plurality of heat resistance cells are made of an integrated, each heat resistance cell, An insulating layer provided on the silicon substrate to insulate thermal and electrical signals; A heat resistance layer provided on the insulating layer and having a different resistance by heat; And a protective silicon layer disposed on the heat resistance layer to transmit infrared rays, but to protect the heat resistance layer from the outside. The method of claim 2, wherein the heat resistance layer, Fingerprint recognition system is implemented in the S-shape to obtain the maximum resistance difference, the center portion is formed to be thick in order to sense heat well. The method of claim 1, A second memory unit for temporarily storing the digital signal converted by the A / D conversion means; Memory access means for directly accessing the second memory unit; And a communication unit which transmits a result of processing and fingerprint information determined by the analysis collation unit to the outside or receives a signal from the outside. The fingerprint identification system of claim 1 or 4, wherein the components are integrated into one chip using a CMOS process. A registration process of extracting a regular image signal and a feature point from a fingerprint image received through a thermal resistance sensor and storing the regular image signal and a feature point in one-to-one correspondence with user information; And extracting a normal image signal and a feature point from a fingerprint image received through a heat resistance sensor, and then comparing the extracted feature point with fingerprint information stored in the memory unit to determine whether the user is authenticated. The method of claim 6, wherein the registration process, Receiving information about a user who wants to register a fingerprint; Receiving a fingerprint image through a heat resistance sensor; Filtering and amplifying the fingerprint image and converting the fingerprint image into a digital signal; Converting the digital signal into a normal image signal and extracting feature points from the normal image signal; And storing the normal image signal, the feature point, and the user information in a database form in a one-to-one correspondence. The method of claim 6, wherein the authentication process, Receiving a fingerprint image through a heat resistance sensor; Filtering and amplifying the fingerprint image and converting the fingerprint image into a digital signal; Converting the digital signal into a normal image signal and extracting feature points from the normal image signal; Comparing the extracted feature points with fingerprint information previously stored in the memory to determine whether matching fingerprint information exists; If the matching fingerprint information exists, authenticating the user who inputs the fingerprint as a legitimate user; And if the fingerprint information corresponding to the result of the determination does not exist, authenticating the user who inputs the fingerprint as an invalid user.