Biometric authentication apparatus, biometric authentication method, and non-transitory computer-readable storage medium for storing program for biometric authentication

A biometric authentication apparatus includes: a biometric sensor configured to capture an image of a hand of a user; a touch panel configured to output a contact signal indicating contact positions of fingers of the user in response to the reception of an operation by the fingers of the user; and control circuitry configured to display, on the touch panel, a plurality of marks each of which indicates position at which any of the fingers of the user is intended to come into contact with the touch panel, acquire the contact signal output from the touch panel, and reduce in size one or more marks among the plurality of marks during acquiring biometric information from the image captured by the biometric sensor when the control circuitry detects, in accordance with the contact signal, that the fingers of the user are in contact with the plurality of marks.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2017-020458, filed on Feb. 7, 2017, the entire contents of which are incorporated herein by reference.

FIELD

The embodiments discussed herein are related to a biometric authentication apparatus, a biometric authentication method, and a non-transitory computer-readable storage medium for storing a program for biometric authentication.

BACKGROUND

In order to ensure security upon access to important data via a terminal, biometric authentication is used, for example. The biometric authentication is a technique for confirming the identical person using biometric characteristics such as a fingerprint, the person's face, or veins. In the biometric authentication, acquired biometric information is compared with biometric information registered in advance, and the identical person is confirmed based on whether or not the acquired biometric information matches the registered biometric information. The biometric information to be compared may be biometric characteristic information indicating characteristics of the biometric information.

Since the portability of mobile terminals is being improved, the usability of security functions of the mobile terminals is requested. It is, however, difficult to fix a mobile terminal or stably hold the mobile terminal, depending on the use of the mobile terminal. Thus, if biometric information is imaged in a contactless manner in palm vein authentication or the like, the quality of the acquired biometric information may be degraded due to hand movement. As a result, the identical person may be easily rejected, the number of operations and operation time may increase due to the re-imaging of biometric information or the like, and the usability of the mobile terminal may be reduced.

A large number of mobile terminals include a touch panel. Thus, a technique for acquiring biometric information in a state in which a finger of a user is in contact with a touch panel and in which a relative position of a hand with respect to a mobile terminal is stable has been proposed. In addition, a technique for efficiently acquiring biometric information by sequentially displaying, to a user, a position on a touch panel at which a finger contacts the touch panel has been proposed.

Examples of the related art include International Publication Pamphlet No. WO2014/174674 and Japanese Laid-open Patent Publication No. 2014-215868.

SUMMARY

According to an aspect of the invention, a biometric authentication apparatus includes: a biometric sensor configured to capture an image of a hand of a user; a touch panel configured to output a contact signal indicating contact positions of fingers of the user in response to the reception of an operation by the fingers of the user; and control circuitry configured to display, on the touch panel, a plurality of marks each of which indicates a position at which any of the fingers of the user is intended to come into contact with the touch panel, acquire the contact signal output from the touch panel, and reduce in size one or more marks among the plurality of marks during acquiring biometric information from the image captured by the biometric sensor when the control circuitry detects, in accordance with the contact signal, that the fingers of the user are in contact with the plurality of marks.

DESCRIPTION OF EMBODIMENTS

The sizes of hands vary from person to person. Thus, since a user is forced to maintain a hand in an inappropriate posture for imaging and it is difficult to stably image a palm in a fixed acquisition method or in accordance with a fixed input instruction, the accuracy of biometric authentication may be reduced. For example, if a palm is to be imaged, a user with a small hand is forced to spread user's fingers for the imaging of a palm, and a user with a large hand is forced to close user's fingers for the imaging of a palm.

In conventional biometric authentication, individual differences between biometric parts of users are not considered for the acquisition of biometric information of the biometric parts such as palms. Thus, if biometric authentication is executed using a biometric part imaged in an inappropriate state such as a state in which a user is forced to maintain the biometric part in an uncomfortable posture, it is difficult to stably image the biometric part and improve the accuracy of the biometric authentication.

In other words, since individual differences between biometric parts of users are not considered in conventional techniques, it is difficult to improve the accuracy of biometric authentication using imaged biometric parts.

According to an aspect of the present disclosure, provided are technologies for improving the accuracy of biometric authentication.

According to a biometric authentication apparatus disclosed herein, a biometric authentication method disclosed herein, and a biometric authentication program disclosed herein, when multiple marks specifying positions at which a user uses fingers to contact a touch panel are displayed on the touch panel, and the contact of the fingers with the multiple marks is detected, one or more marks among the marks are reduced and biometric information of a user's hand imaged by a biometric sensor is acquired.

Hereinafter, embodiments of the biometric authentication apparatus disclosed herein, the biometric authentication method disclosed herein, and the biometric authentication program disclosed herein are described with reference to the accompanying drawings.

Embodiments

A biometric authentication technique is to confirm the identical person using characteristic biometric information that indicates a fingerprint, a face, a palm, irises, veins, or the like and varies from person to person. For example, palm authentication is to execute biometric authentication using biometric information indicating palm veins, a palm print, or the shape of a palm. The palm authentication is described below as an example, but biometric authentication is not limited to the palm authentication.

In an embodiment, a biometric authentication apparatus described below may be installed in a terminal. The terminal may be a mobile terminal. The terminal may be a personal computer, a tablet, a smartphone, or the like.

FIG. 1is a block diagram illustrating an example of a hardware configuration of the terminal according to the embodiment. In this example, a terminal1is a mobile terminal such as a tablet or a smartphone. The terminal1includes a central processing unit (CPU)11, a read only memory (ROM)12, a random access memory (RAM)13, an input device14, a display device15, and a biometric sensor16, which are connected to each other as illustrated inFIG. 1. If the terminal1has a communication function, the terminal1may include a known communication section (not illustrated) that executes transmission and reception. In addition, if the terminal1has a function of connecting the terminal1to an external network (not illustrated) such as the Internet, the terminal1may include a known interface (not illustrated).

The CPU11is an example of a controller (or a computer) that controls the entire terminal1. Thus, the controller also controls the biometric authentication apparatus. The ROM12and the RAM13may form a storage device21that is an example of a storage section. In this example, the input device14and the display device15are included in a touch panel22.

The CPU11may execute a computer program including a biometric authentication program and stored in the ROM12, thereby achieving various functions of the terminal1including the biometric authentication apparatus. The ROM12stores the computer program to be executed by the CPU11, various types of data, and the like. The ROM12is an example of a computer-readable storage medium storing a program. The RAM13stores various types of data and registered biometric information.

The input device14of the touch panel22has a function of outputting a contact signal indicating the contact of user's fingers with the touch panel22and inputting the contact signal to the CPU10. The contact signal to be output by the input device14of the touch panel22indicates contact positions that are on the touch panel22and at which the user's fingers have contacted the touch panel22or coordinates of the contact positions, the areas of contact regions of the user's fingers at the contact positions on the touch panel22, the shapes of the contact regions of the user's fingers at the contact positions on the touch panel22, and the like. The input device14of the touch panel22also has a function of inputting, to the CPU11, information that is a character or the like and is indicated by a position at which a user's finger has contacted the touch panel22to input the character or the like. The touch panel that outputs the contact signal and the information such as the character or the like is known. The CPU11may use a known method to detect, based on the contact signal, that the user is performing an operation of sliding fingers on the touch panel22.

The display device15of the touch panel22has a function of displaying characters, figures, messages, multiple marks, input positions including current positions of the user's fingers on the touch panel22, trajectories and directions of a slide operation, and the like, as described later. The multiple marks correspond to an example of a plurality of marks each of which indicates a position at which any of the fingers of the user is intended to come into contact with the touch panel.

The biometric sensor16has a function of imaging a biometric part in a contactless manner in this example. The biometric sensor16includes a camera and may include a biometric illumination light source. In this example, the biometric sensor16is located in the vicinity of the touch panel22and attached to a surface of the terminal1on which the touch panel22is installed.

The biometric sensor16may be a camera for imaging palm veins, a palm print, the shape of a palm, finger's veins, or the like, for example. Alternatively, the biometric sensor16may be a near-infrared sensor (or a near-infrared camera) including a near-infrared illumination light source and an image sensor (or a camera) having sensitivity to a near-infrared wavelength region to be used to image palm veins, finger's veins, or the like, for example. Alternatively, the biometric sensor16may include a near-infrared sensor and a camera having sensitivity to a wavelength region other than the near-infrared wavelength region.

FIG. 2is a functional block diagram illustrating an example of the configuration of the biometric authentication apparatus according to the embodiment. A biometric authentication apparatus31illustrated inFIG. 2includes a biometric information acquirer32to which biometric information is input from the biometric sensor16, a registering and comparing section33, a contact position detector34to which a contact signal and the like are input from the touch panel22, a size detector35, an input instruction generator36, and a display section37. The biometric information acquirer32, the registering and comparing section33, the contact position detector34, the size detector35, the input instruction generator36, and the display section37may be achieved by the CPU11illustrated inFIG. 1, for example, and may be included in the controller achieved by the CPU11, for example. The CPU11may execute the biometric authentication program stored in, for example, the storage device21illustrated inFIG. 1, thereby achieving functions of the biometric information acquirer32, the registering and comparing section33, the contact position detector34, the size detector35, the input instruction generator36, and the display section37, for example.

First, operations to be executed in the registration of biometric information are described below. In the registration of the biometric information, the input instruction generator36generates multiple marks each of which indicates a position at which any of the fingers of the user is intended to come into contact with the touch panel22. Setting values with respect to the multiple marks described later may be stored in, for example, the storage devices21illustrated inFIG. 1by default. In this case, the input instruction generator36may read the setting values with respect to the multiple marks from the storage device21. The display section37displays on the touch panel22the multiple marks generated by the input instruction generator36in accordance with the setting values. When the user uses user's fingers to come into contact with the multiple marks on the touch panel22, the touch panel22outputs, to the contact position detector34, a contact signal indicating that the user's fingers have contacted (touched) the multiple marks. Upon detecting, based on the contact signal, that the user's fingers have contacted all the multiple marks, the contact position detector34outputs the contact signal to the size detector35.

The size detector35detects the size of a hand of the user based on contact positions of the fingers on the touch panel22, the areas of contact regions of the fingers on the touch panel22, the shapes of the contact regions of the fingers on the touch panel22, and the like that are indicated by the contact signal. The size of the hand includes the lengths of the fingers of the hand, the widths of the fingers, the size of the palm of the hand, and the like. The input instruction generator36adjusts one or more display positions of one or more marks to be reduced on the touch panel22, based on the hand's size detected by the size detector35, and outputs, to the display section37, an instruction indicating the adjusted one or more display positions of the one or more marks. The input instruction generator36may output, to the touch panel22, an instruction indicating either or both of trajectories and directions of a user operation of sliding the fingers from the multiple marks, based on one or more types of the contact positions of the fingers on the touch panel22, the areas of the contact regions of the fingers at the contact positions on the touch panel22, and the shapes of the contact regions of the fingers at the contact positions on the touch panel. The contact positions, the areas of the contact regions, and the shapes of the contact regions are indicated by the contact signal. In the generation of the multiple marks specifying the positions at which the user uses fingers to contact the touch panel, the input instruction generator36reduces, based on the hand's size detected by the size detector35, the one or more marks of which the one or more display positions on the touch panel22have been adjusted. The display section37displays, on the touch panel22, the multiple marks generated by the input instruction generator36and including the one or more reduced marks. Thus, the one or more marks among the multiple marks contacted by the user's fingers and displayed on the touch panel22are reduced.

Upon receiving, from the input instruction generator36, the instruction indicating either or both of the trajectories and directions of the user operation of sliding the fingers from the multiple marks, the display section37displays, on the touch panel22, either or both of the trajectories and directions of the slide operation. Specifically, the display section37displays, on the touch panel22, the multiple marks generated by the input instruction generator36and including the one or more reduced marks and either or both of the trajectories and directions of the slide operation. The contact position detector34may detect, based on the contact signal, that the user is performing the operation of sliding the fingers from the multiple marks. When the contact position detector34detects that the user is performing the slide operation, the biometric information acquirer32acquires biometric information of the user's hand imaged by the biometric sensor16during the slide operation. During the slide operation, the biometric information acquirer32may continuously or regularly acquire biometric information of the user's hand imaged by the biometric sensor16.

The biometric information acquirer32that is configured to acquire biometric information of a user's hand imaged by the biometric sensor16may acquire, only during the slide operation, the biometric information output from the biometric sensor16activated during a time period for reading the biometric information. Alternatively, the biometric information acquirer32may activate the biometric sensor16only during the slide operation and acquire the biometric information output from the biometric sensor16.

In this manner, the contact position detector34outputs the contact signal to the size detector35, and the input instruction generator36updates the input instruction based on the size of the user's hand detected by the size detector35. The display section37displays the multiple marks on the touch panel22based on the input instruction updated and output by the input instruction generator36.

The biometric information acquirer32outputs the biometric information imaged by the biometric sensor16to the registering and comparing section33. The registering and comparing section33registers the biometric information in, for example, the storage device21illustrated inFIG. 1. The biometric information output by the biometric information acquirer32to the registering and comparing section33and registered by the registering and comparing section33may be biometric characteristic information indicating characteristics of the biometric information. If the biometric characteristic information is to be extracted from the biometric information, the biometric characteristic information may be extracted using a known method. Since the size detector35detects the size of the hand, it is clear which part of the user's hand corresponds to the biometric information registered by the registering and comparing section33.

Next, operations to be executed in the authentication of biometric information are described. The operations to be executed in the authentication of biometric information are the same as the aforementioned operations to be executed in the registration of biometric information, except for a process to be executed by the registering and comparing section33. In the authentication of biometric information, biometric information is already registered in, for example, the storage device21illustrated inFIG. 1. Thus, the registering and comparing section33compares biometric information acquired by the biometric information acquirer32in the authentication of the biometric information with the biometric information registered in, for example, the storage device21illustrated inFIG. 1. If biometric characteristic information indicating characteristics of the biometric information is already registered, the biometric information output by the biometric information acquirer32to the registering and comparing section33and compared by the registering and comparing section33may be the biometric characteristic information indicating the characteristics of the biometric information. If the biometric information acquired in the authentication matches the registered biometric information, the registering and comparing section33determines that the biometric authentication has been successful, and the registering and comparing section33outputs the comparing result indicating that the user is the identical person. The comparing result may be output to and displayed on the touch panel22or may be output as audio information using a known method, for example.

The biometric information acquirer32, the contact position detector34, the size detector35, the input instruction generator36, and the display section37may form an example of a controlling section that receives a contact signal output from the touch panel22and indicating contact with the touch panel22and controls display on the touch panel22. When the controlling section displays, on the touch panel22, the multiple marks specifying the positions at which the user uses user's fingers to contact the touch panel22, and the controlling section detects, based on a contact signal, that the user has contacted the multiple marks using the fingers, the controlling section reduces one or more of the multiple marks and acquires biometric information of the user's hand imaged by the biometric sensor16.

In this example, the multiple marks indicating the positions at which fingers contact the touch panel are displayed on the touch panel, and one or more of the marks are reduced in response to the contact of the fingers with the marks. Thus, regardless of the size of the user's hand, the multiple fingers may easily contact the marks specifying the contact positions of the fingers without maintaining the hand in an uncomfortable posture. In addition, when the user starts performing an operation of sliding multiple user's fingers, one or more of the multiple marks are reduced and an instruction suitable for the size of the user's hand and indicating either or both of trajectories and directions of the slide operation is displayed on the touch panel. As a result, when the user performs the biometric authentication while using multiple fingers to contact the touch panel of the terminal, the accuracy of the biometric authentication may be improved, regardless of individual differences between the sizes of users' hands.

First Embodiment

Next, a first embodiment is described.FIGS. 3 to 5are plan views describing an example of the display of marks according to the first embodiment. In addition,FIG. 6is a plan view describing an example of the display of marks according to a comparative example.

FIG. 3illustrates an initial state in which multiple marks31-1and31-2specifying positions at which the user uses fingers to contact the touch panel22of the terminal1are displayed on the touch panel22of the terminal1. In this example, the size of the mark31-2is larger than the size of the mark31-1. In addition, in this example, the length of the mark31-2in a vertical direction inFIG. 3is large and the size of the mark31-2is large so that the user is not forced to maintain the hand in an uncomfortable posture. A guide311that specifies either or both of a trajectory and direction of a user operation of sliding a user's finger from the mark31-1is displayed for the mark31-1with the small size. Since the mark31-2with the size larger than that of the other mark31-1is displayed, the user may use a finger to contact the mark31-1at a position at which the finger is easily placed and that is based on the size of the hand of the user. The biometric sensor16is located in the vicinity of the touch panel22and attached to the surface of the terminal1on which the touch panel22is installed. The sensor16may include a camera and a biometric illumination light source17.

FIG. 4illustrates a state in which the user uses fingers to contact the marks31-1and31-2on the touch panel22in the initial state illustrated inFIG. 3. In this example, the mark31-2is displayed in such a manner that the size of the mark31-2with the larger size among the marks31-1and31-2contacted by the fingers is reduced. In addition, coordinates, in a vertical direction inFIG. 4, of the fingers that slide are determined in response to the contact of the user's fingers with the marks31-1and31-2. Thus, a guide312that specifies either or both of a trajectory and direction of a user operation of sliding a user's finger from the mark31-2is displayed for the mark31-2with the reduced size.

FIG. 5is a plan view describing an example of a user operation according to the first embodiment. InFIG. 5, sections that are the same as those illustrated inFIGS. 3 and 4are indicated by the same reference symbols as those illustrated inFIGS. 3 and 4, and a description thereof is omitted. In an initial state ST1illustrated inFIG. 5, the marks31-1and31-2that specify the positions at which the user uses an index finger and a thumb to contact the marks31-1and31-2are displayed on the touch panel22. In this case, since the size of a user's hand500varies depending on the person, the marks31-1and31-2are displayed in such a manner that the size of the mark31-2specifying the position at which the thumb contacts the touch panel22is larger than the size of the mark31-1. In a state in which the user uses the index finger to contact the mark31-1, the user may use the thumb to contact the mark31-2at a position that is on the mark31-2and is based on the size of the hand500. Thus, the marks31-1and31-2that specify the positions at which the fingers contact the touch panel22may be displayed on the touch panel22in such a manner that the user is not forced to maintain the hand in an uncomfortable posture.

In a state ST2illustrated inFIG. 5, the user uses the fingers to contact the marks31-1and31-2on the touch panel22in the initial state ST1. In this example, the marks31-1and31-2are displayed in such a manner that the size of the mark31-2with the larger size among the marks31-1and31-2contacted by the fingers is reduced. In addition, the guide312that specifies either or both of a trajectory and direction of a user operation of sliding the finger is displayed for the mark31-2with the reduced size.

In a state ST3illustrated inFIG. 5, the user has performed an operation of sliding the fingers from the marks31-1and31-2on the touch panel22in the state ST2. For convenience of the description, the guides311and312displayed in halftone are changed to the guides311and312displayed in the same black as the marks31-1and31-2. In addition, in the state ST3, since the user's hand500has moved to an imaging range160suitable for palm imaging by the biometric sensor16, palm information that is an example of user's biometric information is acquired from the biometric sensor16. The palm information is information of palm veins, a palm print, the shape of a palm, or the like.

On the other hand, in the comparative example illustrated inFIG. 6, the sizes of marks31A and31B displayed on the touch panel22before contact are the same, and the marks31A and31B displayed immediately after the contact is similar to the state illustrated inFIG. 4. In addition, guides311A and311B are displayed in such a manner that the guides311A and311B extend in a horizontal direction inFIG. 6from positions at which the corresponding marks311A and311B are initially displayed. Thus, if the size of the user's hand500is in a range estimated upon the design, the user may use fingers to relatively easily contact the marks31A and31B. In addition, when the user performs an operation of sliding the fingers, the biometric sensor16may image a palm within the imaging range160. However, if the size of the user's hand500is larger or smaller than the range estimated upon the design, the user is forced to maintain the hand in an uncomfortable posture in order to use the fingers to contact the marks31A and31B. In addition, when the user performs the operation of sliding the fingers while being forced to maintain the hand in an uncomfortable posture, the biometric sensor16may not appropriately image the palm within the imaging range160. Specifically, the palm to be imaged by the biometric sensor16within the imaging range160may not be close to a planar surface parallel to the touch panel22and may be inclined with respect to the touch panel22, depending on the uncomfortable posture of the hand, or the fingers may be closed due to the uncomfortable posture, and biometric information suitable for the biometric authentication may not be acquired.

On the other hand, in the first embodiment, in the initial state ST1illustrated inFIG. 5, since the marks31-1and31-2are displayed on the touch panel22in such a manner that the size of the mark31-2is larger than the size of the mark31-1, the user is not forced to maintain the hand in an uncomfortable posture. In addition, the user may perform an operation of sliding the fingers while maintaining the hand in a natural posture. Thus, the biometric sensor16may appropriately image the palm within the imaging range160, while the palm is in a state suitable for the imaging of the palm and is close to the planar surface parallel to the touch panel22. Thus, biometric information suitable for the biometric authentication and indicating palm veins or the like may be acquired from the biometric sensor16.

FIG. 7is a flowchart describing an example of a process to be executed in the registration of biometric information according to the first embodiment. The registration process illustrated inFIG. 7may be executed by the CPU11illustrated inFIG. 1. InFIG. 7, in step S1, the CPU11displays the initial state ST1illustrated inFIG. 5on the touch panel22and determines whether or not input by the user or the contact of user's fingers with the marks31-1and31-2has been performed. If the result of the determination of step S1indicates YES, the CPU11detects, based on a contact signal from the touch panel22, that the user has used the fingers to contact the marks31-1and31-2on the touch panel22in step S2. In step S3, the CPU11detects the size of a hand of the user based on contact positions of the fingers on the touch panel22, the areas of contact regions of the fingers on the touch panel22, the shapes of the contact regions of the fingers on the touch panel22, and the like that are indicated by the contact signal. In step S4, the CPU11adjusts, based on the detected size of the hand, a display position of the mark31-2located on the touch panel22and to be reduced. By executing this, the state ST2illustrated inFIG. 5is displayed on the touch panel22, and the reduced mark31-2is displayed at the adjusted display position.

The user performs an operation of sliding the fingers on the touch panel22in the state ST2. In step S5, in the state ST3in which the slide operation has been performed on the touch panel22and that is illustrated inFIG. 5, the CPU11determines whether or not biometric information has been received from the biometric sensor16. If the result of the determination of step S5indicates YES, the CPU11determines whether or not the biometric information imaged by the biometric sensor16within the imaging range160and received is suitable for the biometric authentication and indicates palm veins or the like in step S6. If the result of the determination of step S6indicates NO, the process returns to step S1. On the other hand, if the result of the determination of step S6indicates YES, the process proceeds to step S7A. In step S7A, the CPU11registers the received biometric information in, for example, the storage device21illustrated inFIG. 1. Then, the process is terminated.

FIG. 8is a flowchart describing an example of a process to be executed in the authentication of biometric information according to the first embodiment. The authentication process illustrated inFIG. 8may be executed by the CPU11illustrated inFIG. 1. InFIG. 8, steps that are the same as those illustrated inFIG. 7are indicated by the same reference symbols as those illustrated inFIG. 7, and a description thereof is omitted. In the authentication of biometric information, biometric information is already registered in, for example, the storage device21illustrated inFIG. 1by the registration process illustrated inFIG. 7. Thus, in step S7B illustrated inFIG. 8, the CPU11compares biometric information received in the authentication of biometric information with the biometric information registered in, for example, the storage device21illustrated inFIG. 1. If biometric characteristic information indicating characteristics of the biometric information is already registered, the biometric information to be compared may be the biometric characteristic information indicating the characteristics of the biometric information. If the biometric information acquired in the authentication matches the registered biometric information in step S7B, the CPU11determines that the biometric authentication has been successful, and the CPU11outputs the comparing result indicating that the user is the identical person. Then, the process is terminated. According to the first embodiment, the accuracy of the authentication may be high, regardless of individual differences between the sizes of hands of users.

Second Embodiment

Next, a second embodiment is described. Ergonomically speaking, a motion range of a thumb is larger than those of the other fingers. Thus, in the aforementioned first embodiment, the marks are displayed on the touch panel in such a manner that the size of the mark specifying the position at which the thumb contacts the touch panel is larger than the size of the mark specifying the position at which another finger contacts the touch panel. On the other hand, in the second embodiment, as illustrated inFIG. 9, marks31-1and31-2are displayed on the touch panel22in such a manner that the size of the mark31-1specifying a position at which the index finger contacts the touch panel22is larger than the size of the mark31-2specifying a position at which another finger contacts the touch panel22.FIG. 9is a plan view describing an example of the display of the marks according to the second embodiment. InFIG. 9, sections that are the same as those illustrated inFIGS. 3 and 4are indicated by the same reference symbols as those illustrated inFIGS. 3 and 4, and a description thereof is omitted. According to the second embodiment, the user may freely select a position on the mark having the larger size and displayed on the touch panel22based on the size of the user's hand, a trajectory and direction of an operation of sliding fingers, and the like.

Third Embodiment

Next, a third embodiment is described. In the third embodiment, as illustrated inFIG. 10, a mark31-1specifying a position at which the index finger contacts the touch panel22and a mark31-2specifying a position at which the thumb contacts the touch panel22are displayed on the touch panel22and have large sizes.FIG. 10is a plan view describing an example of the display of the marks according to the third embodiment. InFIG. 10, sections that are the same as those illustrated inFIGS. 3 and 4are indicated by the same reference symbols as those illustrated inFIGS. 3 and 4, and a description thereof is omitted. According to the third embodiment, the marks31-1and31-2that specify the positions that are on the touch panel22and at which the user uses the index finger and the thumb to contact the touch panel22may have ranges (or margins). According to the third embodiment, the marks31-1and31-2that specify the positions at which the user uses the fingers to contact the touch panel22may be displayed on the touch panel22in such a manner that the user is not forced to maintain the hand in an uncomfortable posture.

Fourth Embodiment

Next, a fourth embodiment is described. In the fourth embodiment, as illustrated inFIG. 11, marks31-1,31-2, and31-3that specify positions at which the user uses three or more fingers to contact the touch panel22are displayed on the touch panel22in such a manner that the size of the mark31-2that specifies a position at which the user uses, for example, a single finger (or a thumb in this example) to contact the touch panel22is larger than those of the marks31-1and31-3that specify positions at which the user uses the other fingers to contact the touch panel22. A guide313is displayed for the mark31-3.FIG. 11is a plan view describing an example of the display of the marks according to the fourth embodiment. InFIG. 11, sections that are the same as those illustrated inFIGS. 3 and 4are indicated by the same reference symbols as those illustrated inFIGS. 3 and 4, and a description thereof is omitted. According to the fourth embodiment, the marks31-1to31-3that specify the positions at which the fingers contact the touch panel22are displayed on the touch panel22that is contacted by the user using three or more fingers in such a manner that one or more of the marks have a range for one or more fingers. According to the fourth embodiment, the marks31-1to31-3that specify the positions at which the fingers contact the touch panel22may be displayed in such a manner that the user stably performs an operation of sliding the fingers on the touch panel22while not being forced to maintain the hand in an uncomfortable posture.

Fifth Embodiment

Next, a fifth embodiment is described. In the fifth embodiment, as illustrated inFIG. 12, a representative guide312A is displayed for a mark31-2to be reduced. In this example, the guide312A extends in a horizontal direction from a central portion of the large mark31-2in a vertical direction inFIG. 12.FIG. 12is a plan view describing an example of the display of marks according to the fifth embodiment. InFIG. 12, sections that are the same as those illustrated inFIGS. 3 and 4are indicated by the same reference symbols as those illustrated inFIGS. 3 and 4, and a description thereof is omitted. According to the fifth embodiment, the user may easily image a sliding direction and the like for the large mark31-2before performing an operation of sliding fingers.

Sixth Embodiment

Next, a sixth embodiment is described. In the aforementioned first to fifth embodiments, the size of the hand of the user is detected based on positions that are on the touch panel22and at which the user has contacted the touch panel22using fingers. For example, even if the hand is large and the user uses fingers to contact the touch panel22while closing fingers, the size of the hand is detected as a size smaller than the actual hand. Thus, the size of the hand may be erroneously detected, depending on the posture of the hand, how to place the hand, or the like. In the sixth embodiment, the size of the hand is detected based on an image captured by the biometric sensor16when the user uses fingers to contact the touch panel.FIG. 13is a plan view describing an example of the detection of a large hand.FIG. 14is a plan view describing an example of the detection of a small hand. InFIGS. 13 and 14, sections that are the same as those illustrated inFIG. 3are indicated by the same reference symbols as those illustrated inFIG. 3, and a description thereof is omitted.

If a hand500-1of a user is large, the area of a palm region indicated by hatching and included in an image60-1captured by the biometric sensor16is larger than the area of a background region included in the image60-1, as illustrated in an enlarged manner on the right side ofFIG. 13. On the other hand, if a hand500-2of a user is small, the area of a palm region indicated by hatching and included in an image60-2captured by the biometric sensor16is smaller than the area of a background region included in the image60-2, as illustrated in an enlarged manner on the right side ofFIG. 14. Thus, whether or not the position of a user's thumb contacting the touch panel22is appropriate is determined by determining whether or not the area of a palm region within an image (for example, images60-1and60-2) captured by the biometric sensor16is equal to or larger than a threshold. For example, in the state ST2illustrated inFIG. 5, the length (or the position at which the thumb contacts the touch panel) of the mark31-2in the vertical direction is adjusted in such a manner that the area of a palm region within an image captured by the biometric sensor16is equal to or larger than the threshold. According to the sixth embodiment, multiple marks including the mark31-2may be displayed on the touch panel22in such a manner that biometric information suitable for the biometric authentication is acquired from the biometric sensor16, regardless of the size of the hand of the user.

Seventh Embodiment

Next, a seventh embodiment is described. In the aforementioned sixth embodiment, the size of a user's hand is detected from an image captured by the biometric sensor. On the other hand, in the seventh embodiment, the size of a user's hand and the inclination of the user's hand with respect to the touch panel22are detected.FIGS. 15 and 16are side views describing an example of the detection of the inclination of a hand according to the seventh embodiment. If the palm of the user is close to the planar surface parallel to the touch panel22as illustrated inFIG. 15, the area of a palm region indicated by hatching and included in an image60-3captured by the biometric sensor16is larger than the area of a background region included in the image60-3, as illustrated in an enlarged manner on the right side ofFIG. 15. On the other hand, if the hand500is inclined with respect to the touch panel22, the area of a palm region indicated by hatching and included in an image60-4captured by the biometric sensor16is smaller than a background region included in the image60-4, as illustrated in an enlarged manner on the left side ofFIG. 16.

The CPU11may have a known function of detecting the distance between the biometric sensor16and a target object to be imaged or a vertical position of the hand500from the touch panel22. In this case, the size of the hand500of the user may be detected based on the detected vertical position of the hand500and the area of a palm region within an image captured by the biometric sensor16. Whether or not the posture of the user's hand500with respect to the touch panel22is appropriate may be determined by calculating the relationship between the vertical position of the hand500and the area of the palm region included in the image captured by the biometric sensor16in the state illustrated inFIG. 15in advance and determining whether or not the relationship between the vertical position of the hand500and the area of the palm region included in the image captured by the biometric sensor16in the state illustrated inFIG. 16satisfies the relationship calculated in advance. If it is determined that the posture of the user's hand500with respect to the touch panel22is not appropriate, the result of the determination of step S6illustrated inFIGS. 7 and 8indicates NO, for example. In this case, the CPU11may output a message prompting the user to correct the posture of the hand500and place the palm close to the planer surface parallel to the touch panel22and may cause the process to return step S1. According to the seventh embodiment, the user may be efficiently prompted to correct the posture of the hand500.

Eighth Embodiment

Next, an eighth embodiment is described. In the aforementioned sixth and seventh embodiments, the size of a user's hand is detected from an image captured by the biometric sensor. In the eighth embodiment, the size of the hand is detected based on contact states of user's fingers on the touch panel22.FIGS. 17 and 18are schematic diagrams describing examples of the detection of the size of the hand according to the eighth embodiment.FIGS. 17 and 18illustrate schematic plan views on the upper sides and schematic side views on the lower sides.

If a user with a small hand uses fingers to contact marks on the touch panel22while being forced to spread the fingers, angles between the fingers and the touch panel22are small and ranges601in which the fingers contact the touch panel22are large and in long and thin shapes in directions in which the fingers extend, as illustrated inFIG. 17. In addition, since the user spreads the fingers, the index finger and the thumb form a “V” shape in a plan view.

On the other hand, if a user with a large hand uses fingers to contact the marks on the touch panel22while being forced to close the fingers, ranges602in which the fingers contact the touch panel22are small and in shapes that are short in directions in which the fingers extend, as illustrated inFIG. 18. In addition, the index finger and the thumb extend in the directions nearly parallel to each other in a plan view.

Thus, according to the eighth embodiment, the sizer of the hand is detected based on the contact states of the user's fingers on the touch panel22, as illustrated inFIGS. 17 and 18.

Ninth Embodiment

Next, a ninth embodiment is described. The size of a hand that is detected in each of the aforementioned first to eighth embodiments may be used as a part of biometric information to be compared. For example, if biometric information acquired in the registration of biometric information, and information of the size of the hand, are associated with each other and registered, the size of the hand may be used in the authentication of biometric information. For example, a matching degree of the information of the size of the hand may be included in an authentication score, and the accuracy of the authentication may be improved. In addition, if the terminal1is shared by multiple users, the accuracy of the authentication and the speed of the authentication may be improved by determining, based on the sizes of hands, the order in which multiple templates are searched.

Tenth Embodiment

Next, a tenth embodiment is described. The size of a hand that is detected in each the aforementioned first to eighth embodiments may be used as a part of search information. If the number of users who use the terminal1is limited to one, the improvement of the usability and a reduction in a false non-match rate may be expected by displaying, on the touch panel22, fingers' positions registered based on the detected size of the hand in the authentication of biometric information. Alternatively, the registered fingers' positions may not be displayed on the touch panel22in an initial state, and if the authentication process fails a predetermined number of times, the registered fingers' positions may be displayed on the touch panel22.

If the terminal1is used by multiple users, priorities may be given to fingers' positions based on the frequency of use, elapsed time after the previous use, and the like, and the display of the fingers' positions may be determined based on the priorities. In this case, if the authentication process fails a predetermined number of times, registered positions may be updated to positions for a user of the next priority.

According to the tenth embodiment, the speed of the authentication may be improved by using the size of a hand as a part of search information.

Each of the aforementioned embodiments describes the case where the user operates the touch panel with the right hand. If the user operates the touch panel with the left hand, it is sufficient if, in a state in which the terminal1illustrated inFIG. 3is rotated at an angle of 180 degrees, information bilaterally symmetric with respect to the displayed state illustrated inFIG. 3is displayed on the touch panel22. In this case, coordinates at which the marks are displayed are adjusted based on a relative position of the biometric sensor16with respect to the touch panel22.

The biometric authentication is not limited to the palm authentication and may be finger vein authentication or the like. In addition, the palm authentication is not limited to the palm vein authentication and may be biometric authentication using biometric information such as palm prints, the shapes of palms, or the like, for example.

According to the aforementioned embodiments, in the biometric authentication that is executed while multiple fingers contact the touch panel, the accuracy of the authentication may be high, regardless of individual differences between the sizes of users' hands. In addition, the accuracy of the authentication may be improved by supporting natural input based on the sizes of users' hands.