JP3802886B2 - Sweep fingerprint authentication device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sweep type fingerprint authentication apparatus, and more particularly to a sweep type fingerprint authentication apparatus that detects and authenticates a user's fingerprint by a sweep method using a thermal sensor.
[0002]
[Prior art]
Conventionally, various technologies have been proposed as fingerprint authentication devices (for example, Patent Document 1).
In the fingerprint sensor, fingerprint collation device, and the like disclosed in Patent Document 1, a plurality of minute temperature sensor elements are arranged on a substrate at minute intervals. In addition, a protrusion capable of conducting heat is provided in a recess on the temperature sensor element that is generated when the wiring and the insulating film are laminated. For this reason, the crest of the fingerprint is surely brought into contact with the detection surface of the protrusion, and the heat of the sensor element moves to the crest of the fingerprint through the protrusion, so that the temperature of the sensor element is lowered. On the other hand, since the protrusion does not contact the valley of the fingerprint, in this case, the temperature of the sensor element does not decrease. Therefore, fingerprints can be detected with high accuracy by detecting the temperatures of a plurality of arranged sensor elements.
[0003]
[Patent Document 1]
JP 2002-269548 A
[Problems to be solved by the invention]
However, since the line sensor in the conventional fingerprint authentication apparatus as described above has the same sensor elements as the central part as shown in FIG. 5, the use of the apparatus is used as shown in FIG. Among them, the temperature distribution of the line sensor is lower in the peripheral part than in the central part due to the outflow of heat to the outside, and the S / N ratio becomes worse in the peripheral part. Further, since the signal amplification processing is performed at the peripheral portion at the same amplification factor as that at the central portion, there is a problem that sensitivity of the peripheral portion is lowered and fingerprint authentication accuracy is deteriorated.
[0005]
Therefore, the present invention has been made to solve such a problem, and a fingerprint authentication device having high fingerprint authentication accuracy having the same high sensitivity as that of the central portion in the peripheral portion of the line sensor is also provided. The purpose is to provide.
[0006]
[Means for Solving the Problems]
In order to solve the above-described problem, a sweep type fingerprint authentication apparatus according to the present invention is a sweep type fingerprint authentication apparatus that detects and authenticates a user's fingerprint by a sweep method using a thermal sensor, and is centered at a peripheral portion. In a line sensor in which a sensor element having a larger area than a part or a sensor element having a long area in a direction in which a user's finger is swept is arranged, or in a peripheral part. A line sensor in which a sensor element whose resistance value is higher than the central part, or whose resistance value is gradually increased as it approaches the peripheral part, or a supply voltage to the line sensor is increased in the peripheral part from the central part. Alternatively, the power supply means that gradually increases as it approaches the peripheral part, or the signal amplification factor of the line sensor is increased in the peripheral part from the central part. Or, characterized in that it comprises a signal amplifying correcting means for stepwise increases toward the peripheral portion.
[0007]
As a result, the sweep type fingerprint authentication device can maintain the same high sensitivity as that of the central portion in the peripheral portion of the line sensor, and the accuracy of fingerprint authentication is improved.
[0008]
The present invention can be realized not only as such a sweep type fingerprint authentication apparatus but also as a method for correcting the amplification factor of a signal of a line sensor, or a program for causing a general-purpose computer to function as a sweep type fingerprint authentication apparatus. It can also be realized as.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a sweep-type fingerprint authentication apparatus according to an embodiment of the present invention will be described with reference to the drawings.
(Embodiment 1)
FIG. 1 is an external view of a sweep type fingerprint authentication apparatus 10 according to the present invention. As shown in FIG. 1A, the sweep type fingerprint authentication device 10 is a device that detects a user's fingerprint by a sweep method using a thermal sensor, includes a line sensor 4, and is connected to an external device 20 when used. ing. The external device 20 is a mobile phone, for example, and can be used only by a registrant, and use by other than the registrant is prohibited. As shown in FIG. 1B, the user who wants to perform the fingerprint authentication operation touches the upper part of the line sensor 4 of the sweep type fingerprint authentication apparatus 10 with the first joint and the second joint of the finger 30. After placing a gap, the finger 30 is slowly and smoothly slid in the direction of arrow A.
[0010]
FIG. 2 is a block diagram of the sweep type fingerprint authentication apparatus 10 according to the first embodiment. The sweep fingerprint authentication apparatus 10 includes a line sensor 4, a power supply unit 11, a wiring 12, a signal amplification unit 13, an A / D (Analog-to-Digital) conversion unit 14, a signal processing unit 15, and an output interface 16. .
[0011]
Inside the line sensor 4, one end of each sensor element 1 is connected to the power supply unit 11 and the other end is connected to the signal amplifying unit 13 by wiring 12.
The power supply unit 11 selects each column of the line sensor 4 and supplies power to the sensor element 1.
[0012]
The signal amplifying unit 13 detects each current in each of the four rows output from the line sensor 4, amplifies it, and outputs it to the A / D conversion unit 14.
[0013]
The A / D conversion unit 14 converts the analog signal of the current from the signal amplification unit 13 into a digital signal and outputs it to the signal processing unit 15.
[0014]
The signal processing unit 15 receives the digital signal from the A / D conversion unit 14 and finally synthesizes one fingerprint data from a series of fingerprint data divided into a line. Further, the combined fingerprint data is compared with fingerprint data registered in advance, and if it is determined that they are the same, authentication is performed, and if they are determined not to be the same, authentication is not performed. Then, the determination result is transmitted to the external device 20 through the output interface 16.
[0015]
FIG. 3 is a diagram showing an example of arrangement of sensor elements in the line sensor according to the present invention. FIG. 3A shows a line sensor 4a in which a sensor element 1a having a large area is arranged at the periphery. FIG. 3B shows a line sensor 4b in which sensor elements 1b having a large area are arranged step by step as approaching the periphery. FIG. 3C shows a line sensor 4c in which a sensor element 1c having a long shape in the direction in which the user's finger is swept in the peripheral portion is arranged. FIG. 3D shows a line sensor 4d in which a sensor element 1d having a shape that gradually increases in the direction in which the user's finger is swept as it approaches the periphery.
[0016]
In any of FIGS. 3A to 3D, since a sensor element having a large area is disposed in the peripheral portion of the line sensor, the amount of heat generated in the peripheral portion is larger than in the conventional case, as shown in FIG. In addition, the decrease in the temperature of the sensor element at the peripheral portion, which has been a problem of the prior art, is improved, and the peripheral portion can be kept at the same temperature as the central portion. Therefore, the same high sensitivity can be maintained in the peripheral part as in the central part.
[0017]
As described above, in any of FIGS. 3A to 3D, the sensitivity in the peripheral part of the line sensor is maintained at the same level as that in the central part, so that the accuracy of fingerprint authentication is improved.
[0018]
(Embodiment 2)
The appearance and block configuration of the present embodiment are almost the same as those of the first embodiment. The arrangement of the sensor elements in the line sensor is the same as in FIG. However, the resistance value of the sensor element is different from that of the first embodiment.
[0019]
FIG. 6 is a diagram illustrating an example of the resistance value of the sensor element according to the second embodiment. In the present embodiment, the resistance value of the sensor element is set so as to become higher stepwise than the resistance value of the central sensor element as it approaches the peripheral part. As a result, the current flowing through the peripheral sensor element increases, the heat generation amount of the peripheral sensor element increases, and as shown in FIG. 4, a decrease in the peripheral temperature is prevented, and the S / N ratio is improved. Eventually, the peripheral portion can maintain the same high sensitivity as the central portion, and the accuracy of fingerprint authentication is enhanced.
[0020]
In the present embodiment, the resistance value characteristic is not stepwise, and a sensor element having a high resistance value only in the peripheral portion may be arranged.
[0021]
(Embodiment 3)
The appearance and block configuration of the present embodiment are almost the same as those of the first embodiment. The arrangement of the sensor elements in the line sensor is the same as in FIG. However, the function of the power supply unit is different from that of the first embodiment.
[0022]
FIG. 7 is a diagram illustrating an example of a supply voltage to the line sensor according to the third embodiment. As shown in FIG. 7, in this embodiment, the function of the power supply unit in FIG. 2 is set so that the supply voltage to the sensor element increases as it approaches the peripheral part. As a result, the current flowing through the peripheral sensor element increases, the heat generation amount of the peripheral sensor element increases, and as shown in FIG. 4, a decrease in the peripheral temperature is prevented, and the S / N ratio is improved. Eventually, the peripheral portion can maintain the same high sensitivity as the central portion, and the accuracy of fingerprint authentication is enhanced.
[0023]
In the present embodiment, the characteristics of the supply voltage to the line sensor may not be stepwise, and may be set so that the supply voltage increases only at the peripheral portion.
[0024]
(Embodiment 4)
The appearance and block configuration of the present embodiment are almost the same as those of the first embodiment. The arrangement of the sensor elements in the line sensor is the same as in FIG. However, it differs from Embodiment 1 in that the amplification factor of the signal of the line sensor is corrected.
[0025]
FIG. 8 is a diagram showing correction of the amplification factor in the signal processing unit in FIG. 2 according to the present embodiment. Conventionally, correction is not performed in the signal processing unit, but the correction of the amplification factor in the signal processing unit according to the present embodiment becomes higher as the input signal is from a sensor element closer to the peripheral portion. Is set as follows. As a result, even if the temperature of the sensor element in the peripheral part is lower than that in the central part and the sensitivity is poor, the signal amplification factor is set high. High sensitivity can be maintained, and the accuracy of fingerprint authentication is increased.
[0026]
Note that the correction of the amplification factor in the signal processing unit according to the present embodiment may not be a stepwise characteristic as shown in FIG. . Further, the correction may be performed not by the signal processing unit but by the signal amplification unit.
[0027]
As described above, the sweep type fingerprint authentication apparatus according to the present invention has been described based on the embodiments. However, the present invention is not limited to these embodiments. For example, in the first, second, third, and fourth embodiments of the invention, the sweep type fingerprint authentication apparatus 10 is separated from the external device 20, but these may be unified to form an integrated structure.
[0028]
【The invention's effect】
As is clear from the above description, according to the sweep type fingerprint authentication device of the present invention, the amount of heat generation is increased at the peripheral part of the line sensor, or the signal amplification factor of the line sensor is increased from the central part to the peripheral part. Therefore, the peripheral portion can have the same high sensitivity as the central portion, and the detection accuracy of the portion near the end of the fingerprint of the user's finger is improved, leading to a reduction in detection errors.
[0029]
Therefore, according to the present invention, the fingerprint authentication operation with good sensitivity can be performed in the peripheral portion as well as in the central portion, which leads to the improvement of fingerprint recognition accuracy, and its practical value is extremely high.
[Brief description of the drawings]
FIG. 1 is an external view of a sweep type fingerprint authentication apparatus according to the present invention.
FIG. 2 is a block diagram of a sweep type fingerprint authentication apparatus according to the present invention.
FIG. 3 is a diagram showing an example of arrangement of sensor elements in the line sensor according to the first embodiment of the present invention.
FIG. 4 is a diagram illustrating an example of a temperature distribution of a sensor element in a line sensor according to the present invention.
FIG. 5 is a diagram showing an example of the arrangement of sensor elements in the line sensor according to Embodiments 2 and 3 of the present invention.
FIG. 6 is a diagram showing an example of a resistance value of a sensor element according to Embodiment 2 of the present invention.
FIG. 7 is a diagram illustrating an example of a supply voltage to a line sensor in a power supply unit according to a third embodiment of the present invention.
FIG. 8 is a diagram showing an example of amplification factor correction in a signal processing unit according to Embodiment 4 of the present invention;
[Explanation of symbols]
1, 1a, 1b, 1c, 1d Sensor element 4, 4a, 4b, 4c, 4d Line sensor 10 Sweep fingerprint authentication device 11 Power supply unit 12 Wiring 13 Signal amplification unit 14 A / D conversion unit 15 Signal processing unit 16 Output Interface 20 External device 30 Finger

Claims (4)

A sweep type fingerprint authentication device that detects and authenticates a user's fingerprint by a sweep method using a thermal sensor,
Equipped with a line sensor that suppresses a decrease in sensitivity at the periphery,
2. The sweep type fingerprint authentication apparatus according to claim 1, wherein a sensor element having a resistance value higher in the peripheral part than in the central part is arranged in the peripheral part . The line sensor is
Sweep type fingerprint authentication device according to claim 1, wherein the sensor element stepwise resistance value increases is arranged closer to the periphery. A sweep type fingerprint authentication device that detects and authenticates a user's fingerprint by a sweep method using a thermal sensor,
A sweep type fingerprint authentication apparatus comprising: a power supply means for increasing a supply voltage to the line sensor in a peripheral portion from a central portion. The power supply means is
The sweep-type fingerprint authentication device according to claim 3, wherein the supply voltage to the line sensor is increased stepwise as it approaches the periphery.

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