Patent Application
20210073503
The present patent application claims the priority of Japanese patent application No. 2017/254149 filed on Dec. 28, 2017, and the entire contents of Japanese patent application No. 2017/254149 are hereby incorporated by reference.
The present invention relates to a fingerprint authentication device.
A start control device is known which is provided with a start switch giving an instruction to start or stop a drive source, a start-up means for starting the drive source, a fingerprint sensor for scanning fingerprints, and a control means which, based on inputs from the fingerprint sensor and the start switch, implements a start-up process to control activation. of the start-up means e.g., Patent Literature 1).
When the start switch gives an instruction to start, the control means of the start control device performs fingerprint verification by comparing a fingerprint scanned by the fingerprint sensor with a pre-registered fingerprint before start-up by the start-up means, and once a match is found, the control means authenticates the user as a genuine user and allows the start-up means to start up.
Patent Literature 1: JP 2008/174095 A
In case of the start control device described in Patent Literature 1, if the detection threshold at the time of scanning fingerprints is set to high so that, e.g., false detection due to variation between individuals who register fingerprints is reduced, an operating finger may not be detected even though it is touching. On the other hand, when the detection threshold is set to low, false detection may increase.
It is an object of the invention to provide a fingerprint authentication device which can set an appropriate detection threshold.
According to an embodiment of the invention, a fingerprint authentication device comprises an authentication unit by which the smallest detection value among detection values resulting from a plurality of touches performed on a detection surface to register a fingerprint is set as a detection threshold for fingerprint detection performed after the registration.
According to an embodiment of the invention, it is possible to provide a fingerprint authentication device which can set an appropriate detection threshold.
A fingerprint authentication device in an embodiment is generally configured to have an authentication unit by which the smallest detection value among detection values resulting from a plurality of touches performed on a detection surface to register a fingerprint is set as a detection threshold for fingerprint detection performed after the registration.
This fingerprint authentication device is configured that the smallest detection value at the time of registration is used as the detection threshold after the registration. Therefore, unlike when the detection threshold is fixed, it is possible to set an appropriate detection threshold.
The fingerprint authentication device 1 is to perform authentication of fingerprint which is one of biometric information. The fingerprint authentication device 1 is arranged on a start switch 5 of a vehicle as shown in
The fingerprint authentication device 1 is generally configured to have, e.g., a control unit 14 as an authentication unit by which the smallest detection value among detection values resulting from plural touches performed on a detection surface 11 to register a fingerprint is set as a detection threshold (an update detection threshold Th3) for fingerprint detection performed after the registration, as shown in
As an example, the fingerprint authentication device 1 is provided with a registration unit 12 for registering plural fingerprints.
The start switch 5 is arranged on, e.g., in front of an operator sitting in a driver's seat or on a floor console located between the driver's seat and the front passenger seat. The start switch 5 instructs a vehicle to start, or to prepare to start, a drive system of the vehicle by a push operation (ON operation) performed on an operation surface 51 of an operation button 50, and instructs to stop the drive system by a next push operation (OFF operation).
The start switch 5 in the present embodiment mounts the fingerprint authentication device 1 and is thus configured to output a signal instructing to start the drive system when a push operation is detected and a fingerprint of an operating finger touched the detection surface 11 at the time of the push operation is authenticated by the fingerprint authentication device 1.
A fingerprint scanning unit 10 is arranged so that the detection surface 11 is exposed at the center of the operation surface 51 of the start switch 5. For example, a sensor configured to scan a fingerprint pattern, such as capacitive, electric field strength measuring, pressure-sensative, or thermal-sensitive type is used as the fingerprint scanning unit 10.
The fingerprint scanning unit 10 in the present embodiment is a capacitive sensor, as an example. The fingerprint scanning unit 10 is configured to detect a capacitance value C generated between itself and the operating finger which touches the operation surface 51 to operate the start switch 5, and also to scan a fingerprint of the operating finger.
As an example, the fingerprint scanning unit 10 has plural electrodes located under the detection surface 11 and intersecting in an insulated state. The fingerprint scanning unit 10 is configured to, e.g., drive one electrode intersecting in one direction, to sequentially read the capacitance values C generated between the electrode and the operating finger by electrodes intersecting in the other direction, and to generate scanned information S1 including information corresponding to the fingerprint obtained by image processing and information of a total capacitance value CT as a detection value which is the sum of the capacitance values C for one cycle of scanning. As an example, the fingerprint scanning unit 10 converts the detected capacitances into digital values and calculates the sum of the values.
In the present embodiment, the total capacitance value CT is used as the detection value as an example, but it is not limited thereto. A maximum value or a peak value of the read capacitance values may be used as the detection value.
The fingerprint authentication device 1 may be configured such that, e.g., the fingerprint scanning unit 10 outputs the capacitance values C to the control unit 14 and the control unit 14 calculates the total capacitance value CT.
As an example, the registration unit 12 has a set button 120 and registration buttons 121 to 123, which are arranged in the vicinity of the start switch 5, as shown in
The set button 120 and the registration buttons 121 to 123 are a group of buttons which are pressed when registering fingerprints or when identifying a registered individual by the fingerprint.
A word “SET” is printed on the set button 120, as an example. Alphabets “A” to “C” are printed on the registration buttons 121 to 123, as an example. These “A” to “C” indicate registration A to registration C. The number of registration buttons and the number of biometrics which can be registered are arbitrary.
An operator, when registering his/her fingerprint, presses the set button 120, then presses the registration button selected to register a fingerprint, and places the operating finger onto the detection surface 11, as an example. In this registration operation, registration information 140 associating the operated button with a fingerprint template is stored in the control unit 14.
When, after the registration, the registered individual presses the registration button used to register the fingerprint and subsequently performs an ON operation on the start switch 5, authentication is performed by comparing the fingerprint of the registered individual with the fingerprint template included in the registration information 140.
The fingerprint template here is used for authentication of fingerprint and consists of characteristic features of the fingerprint. To perform authentication, the control unit 14 extracts the characteristic features of the scanned fingerprint and calculates the degree of match against the template, as an example.
The registration unit 12 generates, e.g., operation information S2 corresponding to a combination of pressed registration buttons and outputs it to the control unit 14. The control unit 14 determines whether it is the normal mode or the registration mode, etc., based on the operation information S2.
As a modification, the fingerprint authentication device 1 may be configured that, e.g., more than three fingerprints can be registered by combining the registration buttons. When, e.g., a fingerprint A is already registered in the fingerprint authentication device 1, the same registered individual can register a fingerprint B in addition to the fingerprint A by pressing the registration button 121 “A” as well as the registration buttons 122 “B”.
Also as a modification, the fingerprint authentication device 1 may be configured to, e.g., identify an individual having a registered fingerprint by communication with an electronic key and to register plural fingerprints of the same registered individual.
The control unit 14 is, e.g., a microcomputer composed of a CPU (Central Processing Unit) performing calculation and processing, etc., of the acquired data according to a stored program, and a RAM (Random Access Memory) and a ROM (Read Only Memory) as semiconductor memories, etc. The ROM stores, e.g., a program for operation of the control unit 14, an initial detection threshold Th1, a registration detection threshold Th2, the update detection threshold Th3, the registration information 140, and a similarity threshold 141. The RAM is used as, e.g., a storage area for temporarily storing calculation results, etc.
When authentication of the fingerprint is successful, the control unit 14 outputs an instruction signal S3 which indicates successful authentication. The start switch 5 gives an instruction to start the drive system when a push operation is detected and the instruction signal S3 indicating successful fingerprint authentication is input.
The initial detection threshold Th1 is a default value which is set when any fingerprint is not registered. The initial detection threshold Th1 is set to higher than the registration detection threshold Th2.
The registration detection threshold Th2 is a detection threshold for the registration mode used when registering a fingerprint.
The update detection threshold Th3 is a detection threshold which is set based on a smallest total capacitance value Cmin obtained at the time of registering the fingerprint. The initial detection threshold Th1, the registration detection threshold Th2 and the update detection threshold Th3 are detection thresholds for determining a touch by the operating finger on the detection surface 11, in other words, for determining whether or not to perform authentication of fingerprint.
The similarity threshold 141 is a threshold value related to the degree of match obtained when comparing the characteristic features of the scanned fingerprint to the registered fingerprint template. As an example, when the number of the characteristic features to be compared is 100 and the number of matches found between the characteristic features of the scanned fingerprint and the characteristic features of the template is not less than “70” which is the similarity threshold 141, the control unit 14 authenticates the operator as the registered individual who has the registered fingerprint.
Next, registration of fingerprint will be described.
The control unit 14 is configured to set the total capacitance value Cmin, which is the smallest among the plural total capacitance values Ct obtained at the time of registering the fingerprint, as the update detection threshold Th3. The control unit 14 is also configured to switch from the preset initial detection threshold Th1 to the lower registration detection threshold Th2 at the time of registration of fingerprint.
In detail, the control unit 14 sets, e.g., the initial detection threshold Th1 in a state that any fingerprint is not registered, as shown in
Next, the control unit 14 obtains plural total capacitance values Ct from N times of touches on the detection surface 11 which are performed, e.g., until a necessary and sufficient template is created. The control unit 14 targets only the total capacitance values Ct not less than the registration detection threshold Th2 and creates the template using plural fingerprints with which such total capacitance values Ct are obtained.
Next, the control unit 14 newly sets the smallest total capacitance value Ct (Cmin), which is not less than the registration detection threshold Th2 and is one of the total capacitance values Ct obtained before the template is created, as the update detection threshold Th3.
The control unit 14 is configured to not perform authentication of fingerprint when the detection value (the detected total capacitance value Ct) is smaller than the detection threshold (the update detection threshold Th3).
In detail, when, e.g., the fingerprint template is created and the registration mode ends, the control unit 14 changes to the normal mode in which authentication of fingerprint is performed using the update detection threshold Th3 as the detection threshold.
Then, the control unit 14 acquires the scanned information S1 from the fingerprint scanning unit 10 and firstly compares the total capacitance value Ct with the update detection threshold Th3. Then, when the total capacitance value Ct is not less than the update detection threshold Th3 as the example shown in
On the other hand, when the total capacitance value Ct is smaller than the update detection threshold Th3 as the example shown in
The control unit 14 is configured to not update the already set detection threshold (the update detection threshold Th3) when a detection value (the total capacitance value Ct) resulting from a touch performed on the detection surface 11 to register an additional fingerprint is a detection value (the total capacitance value Ct) not less than the already set detection threshold (the update detection threshold Th3).
The control unit 14 is also configured to operate such that, when the detection value (the total capacitance value Ct) resulting from a touch performed on the detection surface 11 to register an additional fingerprint is a detection value (the total capacitance value Ct) lower than the already set detection threshold (the update detection threshold Th3), the already set detection threshold (the update detection threshold Th3) is updated to the lower detection value (the total capacitance value Ct).
In detail, when the same registered individual additionally registers a fingerprint, the control unit 14 lowers the threshold from the update detection threshold Th3 to the registration detection threshold Th2 as the example shown in
Next, the control unit 14 obtains plural total capacitance values Ct from N times of touches on the detection surface 11 which are performed, e.g., until a necessary and sufficient template is created.
Next, the control unit 14 compares the smallest total capacitance value Ct (Cmin), which is not less than the registration detection threshold Th2 and is one of the total capacitance values Ct obtained before the template is created, to the update detection threshold Th3 before being reduced. When the smallest total capacitance value Ct (Cmin) is not less than the update detection threshold Th3 as the example shown in
On the other hand, when the smallest total capacitance value Ct (Cmin) is lower than the update detection threshold Th3 as the example shown in
Next, an example of an operation of the fingerprint authentication device 1 in the present embodiment when in the registration mode will be described in reference to the flowchart of
When it is determined, based on the operation information S2 input from the registration unit 12, that the registration mode is instructed, the control unit 14 of the fingerprint authentication device 1 switches from the normal mode to the registration mode (Step 1). Then, the control unit 14 changes from the currently set detection threshold (the initial detection threshold Th1 or the update detection threshold Th3) to the registration detection threshold Th2 (Step 2).
Next, based on the scanned information S1 input from the fingerprint scanning unit 10, the control unit 14 creates a template, using fingerprints with the total capacitance values Ct not less than the registration detection threshold Th2.
When it is “Yes” in Step 3, i.e., when the template is created (Step 3: Yes), the control unit 14 sets the smallest total capacitance value Ct (Cmin) among the total capacitance values Ct of the fingerprints used to create the template, as the update detection threshold Th3 (Step 4).
At this stage, in case that the registration mode is a mode for registering an additional fingerprint, i.e., in case that the update detection threshold Th3 has been already set, the control unit 14 updates the update detection threshold Th3 only when the smallest total capacitance value Ct is lower than the already set update detection threshold Th3.
Then, after setting the update detection threshold Th3, the control unit 14 switches from the registration mode back to the normal mode (Step 5) and ends the registration process.
The fingerprint authentication device 1 in the present embodiment can set an appropriate detection threshold. In detail, in the fingerprint authentication device 1, the smallest total capacitance value Ct (Cmin) obtained in the registration mode is set and used as the update detection threshold Th3 in the normal mode. Therefore, unlike when the detection threshold is fixed, it is possible to set a detection threshold appropriate for the registered individual and this reduces false detection or no detection. In addition, the fingerprint authentication device 1 is configured that the smallest total capacitance value Ct (Cmin), which is obtained when the operator intentionally touches the detection surface 11 until the fingerprint template is created, is set as the update detection threshold Th3. Therefore, accuracy as the threshold is high as compared to when such a configuration is not adopted.
The fingerprint authentication device 1 lowers the detection threshold to the registration detection threshold Th2 in the registration mode. Therefore, unlike when such a configuration is not adopted, the fingerprint is easily detected and the appropriate smallest total capacitance value Ct (Cmin) is easily obtained.
In case that the same registered individual additionally registers a fingerprint and when the smallest total capacitance value Ct (Cmin) lower than the currently used update detection threshold Th3 is obtained, the fingerprint authentication device 1 makes an update. Therefore, unlike when such a configuration is not adopted, it is possible to set a further appropriate detection threshold. In addition, since the fingerprint authentication device 1 does not update when the smallest total capacitance value Ct (Cmin) obtained in the additional registration mode is not less than the currently used update detection threshold Th3, it is possible to maintain the appropriate detection threshold.
The fingerprint authentication device 1 does not perform authentication of fingerprint when the total capacitance value Ct is lower than the update detection threshold Th3. Therefore, unlike when such a configuration is not adopted, the processing load of the control unit 14 is reduced.
Although some embodiment and modifications of the invention have been described, these embodiment and modifications are merely examples and the invention according to claims is not to be limited thereto. These new embodiment and modifications may be implemented in various other forms, and various omissions, substitutions and changes, etc., can be made without departing from the gist of the invention. In addition, all combinations of the features described in these embodiment and modifications are not necessary to solve the problem of the invention. Further, these embodiment and modifications are included within the scope and gist of the invention and also within the invention described in the claims and the range of equivalency.
1 FINGERPRINT AUTHENTICATION DEVICE
10 FINGERPRINT SCANNING UNIT
11 DEJECTION SURFACE
12 REGISTRATION UNIT
14 CONTROL UNIT
51 OPERATION SURFACE
Th1 INITIAL DETECTION THRESHOLD
Th2 REGISTRATION DETECTION THRESHOLD
Th3 UPDATE DETECTION THRESHOLD
| Number | Date | Country | Kind |
|---|---|---|---|
| 2017-254149 | Dec 2017 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2018/045924 | 12/13/2018 | WO | 00 |
