The information acquisition unit 10 is an information acquisition part that acquires biometrics information DIN of a subject, and includes an input unit 12 and an analyzer 14. The input unit 12 is a device (for example, a microphone) that receives a voice spoken by the subject. The analyzer 14 analyzes a voice inputted to the input unit 12 to generate biometrics information DIN reflecting features of that voice. For example, the analyzer 14 generates a cepstral time-series vector sequence of a voice spoken by the subject as biometrics information DIN. To this end, means for executing various computing operations including a frequency analysis (for example, a Fast Fourier Transform (FFT) process) is preferably employed as the analyzer 14.
The storage device 20 is a storage part for storing dictionaries DIC DIC_1˜DIC_m or various parameters used for an authentication process. Various memory devices including a magnetic memory, semiconductor memory, optical memory, etc. are preferably employed as the storage device 20. The storage device 20 may be a device fixedly installed in the biometrics authentication apparatus 100 or a portable device (memory) detachably installed in the biometrics authentication apparatus 100. The dictionaries DIC are template files including biometrics information DO which is compared (collated) with biometrics information DIN during authentication. As shown in
The controller 30 is a device that controls the respective components of the biometrics authentication apparatus 100. In the present embodiment, the controller 30 is a central processing unit (CPU) that functions as an authenticator 32, dictionary manager 34, dictionary reducer 36, and auxiliary authenticator 38 depending on execution of a program. Alternatively, a hardware circuit, such as a digital signal processor (DSP) including electronic circuits for implementing the functions of the above respective components, may be employed as the controller 30.
The authenticator 32 determines validity of a subject by collating biometrics information DIN supplied from the information acquisition unit 10 (analyzer 14) with the biometrics information DO of the dictionaries DIC stored in the storage device 20. The result of the determination by the authenticator 32 is outputted to the output unit 50. The dictionary manager 34 executes update of each dictionary DIC stored in the storage device 20 or addition of a new dictionary DIC to the storage device 20. The dictionary reducer 36 reduces the total number m of dictionaries DIC stored in the storage device 20 by merging the dictionaries DIC together or deleting any dictionary DIC therefrom. The details to be processed by the dictionary manager 34 or dictionary reducer 36 or the respective processing times thereof will be described later in detail. The auxiliary authenticator 38 is a part for auxiliary authenticating the validity of the subject separately from the authentication by the authenticator 32 (this authentication will hereinafter be referred to as “auxiliary authentication”).
The operating unit 40 includes a plurality of operating elements operated by a user. The user can instruct the controller 30 to modify various parameters used for authentication or start authentication, by properly operating the operating unit 40. The output unit 50 is a part for outputting the result of the authentication by the authenticator 32. For example, a display for outputting the authentication result as an image or a speaker for outputting the authentication result as a sound is preferably employed as the output unit 50.
Next, the operation of the biometrics authentication apparatus 100 with the above-stated configuration will be described with reference to
First, a description will be given of an operation of newly registering a dictionary DIC_1 of a valid user (this registration will hereinafter be referred to as “initial registration”). The user instructs the apparatus 100 to start the initial registration, by operating the operating unit 40, and then speaks a specific word to the input unit 12. The analyzer 14 extracts a period in which the user actually spoke, from a voice inputted to the input unit 12, and generates biometrics information DO (for example, a cepstral vector sequence) by analyzing a waveform in the extracted period. Various techniques well known in the art can be employed for the generation of the biometrics information DO. As shown by a dashed line in
If the initial registration of the dictionary DIC_1 is completed through the above procedure, then the controller 30 executes a process of
If the process of
Then, the authenticator 32 determines whether the distance DST_1 calculated at step SA10 is smaller than a threshold value VTHR1 (Step SA11). The threshold value VTHR1 is a parameter stored in the storage device 20, which can be properly modified by the controller 30 according to an operation with respect to the operating unit 40. It should be noted here that the threshold value VTHR1 is set to such a small value as to ensure the precision of authentication at a sufficiently high level (namely, a value within the range of values representing a sufficiently high similarity, among values which can be assumed by the distance DST_1). In this connection, where the distance DST_1 is smaller than the threshold value VTHR1 (that is, where the biometrics information DIN and the biometrics information DO are sufficiently similar), the controller 30 executes processes of step SA12 and step SA13 and then informs the subject through the output unit 50 that the subject has been authenticated as a valid user (Step SA14). If the authentication is appropriately completed in the above manner, various processes by the electronic appliance are enabled.
At step SA12, the controller 30 updates the dictionary DIC_1 in the storage device 20 based on the biometrics information DIN newly acquired during the present authentication (Step SA12). For example, the controller 30 stores the average of the biometrics information DO of the existing dictionary DIC_1 and the new biometrics information DIN in the storage device 20 as new biometrics information DO of the dictionary DIC_1. Alternatively, at step SA12, the biometrics information DO stored in the storage device 20 may be replaced with the new biometrics information DIN.
At the following step SA13, the controller 30 reflects this dictionary DIC_1 update in each parameter stored in the storage device 20. In more detail, the controller 30 adds “1s” to a parameter nUPDATE_1 and parameter nUPDATE_all, respectively, and initializes a parameter nUnUPDATE_1 to “0”. The parameter nUPDATE_i is the number of updates of the dictionary DIC_i representing how many times the dictionary DIC_i was updated up to now. The parameter nUPDATE_all is the total number of updates of all dictionaries DIC stored in the storage device 20. The parameter nUnUPDATE_i is the number of unupdates of the dictionary DIC_i representing how many times the dictionary DIC_i was not updated in authentications.
In the case where it is determined at step SA11 that the distance DST_1 is not smaller than the threshold value VTHR1, the controller 30 determines whether the distance DST_1 is smaller than a threshold value VTHR2 (Step SA15). The threshold value VTHR2 is a parameter stored in the storage device 20, which can be modified by the controller 30 according to an operation with respect to the operating unit 40. It should be noted here that the threshold value VTHR2 is set to a value larger than the threshold value VTHR1 (namely, a value corresponding to a value of the distance DST_1 representing a lower similarity than the threshold value VTHR1).
In the case where the distance DST_1 is within the range between the threshold value VTHR1 and the threshold value VTHR2, the biometrics information DIN and the biometrics information DO are not so similar as to immediately recognize the subject to be valid, compared with the case where the distance DST_1 is smaller than the threshold value VTHR1, and the biometrics information DIN and the biometrics information DO are also not so dissimilar as to definitely deny the validity of the subject. For this reason, when the distance DST_1 is smaller than the threshold value VTHR2 (VTHR1≦DST_1<VTHR2), the validity of the subject is determined by auxiliarily considering the result of auxiliary authentication by the auxiliary authenticator 38 (Step SA16 and Step SA17).
A password pre-registered by a valid user is stored in the storage device 20. The auxiliary authenticator 38 prompts the subject to input a password (Step SA16), and then determines whether a password that the subject inputted through the operating unit 40 in response thereto is the same as the password registered in the storage device 20 (Step SA17). When the determination of step SA17 is positive, the controller 30 executes processes of step SA18 and step SA19 and then proceeds to step SA14. That is, after the fact that the authentication has been appropriately completed is informed from the output unit 50, various processes by the electronic appliance are enabled.
The case where the distance DST_1 is larger than or equal to the threshold value VTHR1, but the subject is determined to be a valid user by virtue of the auxiliary authentication, will probably be a case where the characteristics of the valid user's voice changed depending on the body state of the valid user or surrounding environments. In this regard, at step SA18, the dictionary manager 34 creates a new dictionary DIC_2 including the biometrics information DIN acquired in the present authentication and stores the created dictionary DIC_2 in the storage device 20, so that the subject can be determined to be a valid user at once (namely, without executing the auxiliary authentication by the auxiliary authenticator 38) when biometrics information DIN of the same characteristics as those in the present authentication is inputted in future authentications. Also, the controller 30 reflects this dictionary DIC_2 addition in each parameter stored in the storage device 20 (Step SA19). That is, the controller 30 adds “1s” to a parameter nUPDATE_2 (the number of updates of the dictionary DIC_2) and parameter nUPDATE_all, respectively, and initializes a parameter nUnUPDATE_2, which is the number of unupdates of the dictionary DIC_2, to “0”. The controller 30 further adds “1” to the parameter nUnUPDATE_1 of the dictionary DIC_1 not updated in the present authentication.
In the case where the biometrics information DIN and the biometrics information DO are so dissimilar that the distance DST_1 is larger than or equal to the threshold value VTHR2 (Step SA15:NO) or in the case where the passwords are not the same in the auxiliary authentication (Step SA17: NO), the possibility that the subject will not be a valid user is high. In this connection, when the determination of step SA15 or step SA17 is negative, the controller 30 informs the subject through the output unit 50 that the validity of the subject has been denied (Step SA20). If the validity of the subject is denied in the above manner, various processes by the electronic appliance are disabled.
If a plurality of dictionaries DIC_1˜DIC_m are stored in the storage device 20 by the process of
In the process of
Thereafter, the authenticator 32 determines whether the minimum distance MINDST is smaller than the threshold value VTHR1 (Step SB11). Where the biometrics information DIN and the biometrics information DO are so similar that the minimum distance MINDST is smaller than the threshold value VTHR1, the subject can be recognized as a valid user. In this connection, when the determination of step SB11 is positive, the controller 30 executes step SB12 and step SB13 and then informs the subject through the output unit 50 that the validity of the subject has been authenticated (Step SB14). If the validity of the subject is confirmed in the above manner, various processes by the electronic appliance are enabled.
At step SB12, the dictionary manager 34 updates a dictionary DIC_dMINDST with contents corresponding to the biometrics information DIN through the same process as that of step SA12 of
In the case where it is determined at step SB11 that the minimum distance MINDST is larger than or equal to the threshold value VTHR1, the controller 30 determines whether the minimum distance MINDST is smaller than the threshold value VTHR2, in the same manner as step SA15 of
When the minimum distance MINDST is determined to be larger than or equal to the threshold value VTHR2 at step SB15 or when the subject is determined not to be a valid user at step SB18, the controller 30 informs the subject through the output unit 50 that the validity of the subject has been denied (Step SB21) and then disables various processes by the electronic appliance, in the same manner as
In the case where it is determined at step SB16 that the total number m of dictionaries DIC has reached the maximum value nMAXDIC (m≧nMAXDIC), the controller 30 executes a process of deleting an existing dictionary DIC stored in the storage device 20, as shown in
In the process of
At step SC11, the controller 30 determines whether there is a value exceeding a threshold value UnUPDATE_thr, among the m parameters nUnUPDATE_1˜nUnUPDATE_m corresponding respectively to the dictionaries DIC (Step SC11). The parameter nUnUPDATE_i is incremented when the dictionary DIC_i is not used for the authentication at step SA11 or step SB11 (not updated at step SA12 or step SB12). As a result, the larger parameter nUnUPDATE_i means that the frequency of use of the dictionary DIC_i is lower (namely, the frequency of acquisition of biometrics information DIN similar to the biometrics information DO of the dictionary DIC_i from the subject is lower). In this connection, when the determination of step SC11 is positive, the dictionary reducer 36 deletes one dictionary DIC whose parameter nUnUPDATE_i exceeds the threshold value UnUPDATE_thr, from the storage device 20, and rearranges the remaining (m−1) dictionaries DIC such that the numbers i of the respective dictionaries DIC are consecutive from “1” to “m−1” (Step SC12). Thereafter, the controller 30 initializes a parameter nUPDATE_nMAXDIC and parameter nUnUPDATE_nMAXDIC of a dictionary DIC_nMAXDIC (not created at this time) to be stored in a storage area secured due to the deletion at step SC12, respectively, to 0s (Step SC13) and then proceeds to step SB17 of
When the determination of step SC11 is negative, the controller 30 determines whether a parameter nMINUPDATE is smaller than a threshold value UPDATE_thr (Step SC14). The parameter nMINUPDATE is a minimum value of the m parameters nUPDATE_i-nUPDATE_m corresponding respectively to the dictionaries DIC. The threshold value UPDATE_thr can be modified according to an operation with respect to the operating unit 40. The parameter nUPDATE_i is incremented whenever the dictionary DIC_i is used for the authentication at step SA11 or step SB11. Therefore, the smaller parameter nUPDATE_i means that the frequency of use of the dictionary DIC_i is lower. In this connection, when the determination of step SC14 is positive, the dictionary reducer 36 deletes one dictionary DIC_dMINUPDATE whose parameter nUPDATE_i is the minimum value nMINUPDATE, from the storage device 20, and rearranges the remaining (m−1) dictionaries DIC such that the numbers i of the respective dictionaries DIC are consecutive from “1” to “m−1” (Step SC15). Thereafter, the controller 30 performs the parameter updates at step SC13 and then proceeds to step SB17 of
When the determination of step SC14 is negative, a process (Step SC16˜Step SC18) of merging two dictionaries DIC with similar biometrics information DO among the m dictionaries DIC_1˜DIC_m stored in the storage device 20 is executed. At step SC16, the controller 30 calculates respective inter-dictionary distances with respect to all combinations for selection of two dictionaries DIC among the m dictionaries DIC_1˜DIC_m stored in the storage device 20, and specifies a minimum value MIN_INTERDIC_DST of the calculated distances. Also, the controller 30 determines whether the minimum value MIN_INTERDIC_DST is smaller than a threshold value INTERDIC_thr (Step SC17). The threshold value INTERDIC_thr is stored in the storage device 20 and modified according to an operation with respect to the operating unit 40.
The controller 30 proceeds to step SB21 of
As described above, in the present embodiment, in the case where the distance (DST_1 of
Also, in the case where the distance is larger than or equal to the threshold value VTHR2, the validity of the subject is denied. In the case where the distance is between the threshold value VTHR1 and the threshold value VTHR2, the validity of the subject is auxiliarily authenticated by the auxiliary authenticator 38. Accordingly, although a new dictionary DIC is created even when the biometrics information DIN and the biometrics information DO are so dissimilar that the distance is larger than or equal to the threshold value VTHR1, it is possible to effectively exclude a risk that a new dictionary DIC may be created based on biometrics information DIN acquired from a subject other than a valid user.
Also, in the case where the distance between biometrics information DIN and biometrics information DO of a dictionary DIC_i is smaller than the threshold value VTHR1, the dictionary DIC_i is updated (Step SA12 of
On the other hand, as a method for creating a plurality of dictionaries used for authentication may be considered, for example, a method for prompting a user to speak a plurality of times while changing his speaking style and creating a plurality of dictionaries based on biometrics information DO acquired from speeches of the respective times. In this method, however, the user has the inconvenience of having to speak while changing the speaking style. In contrast, in the present embodiment, a dictionary DIC is automatically updated or created according to whether the distance between biometrics information DIN and biometrics information DO is larger or smaller than the threshold value VTHR1 and threshold value VTHR2. Therefore, the present embodiment has an advantage in that the precision of authentication can be occasionally improved without letting the user recognize the update or creation of a dictionary DIC.
Also, even though the user changes the speaking style, the actual speech may not be so changed as to exhibit a difference between speeches immediately after he wakes up and when he is active during the daytime, or a difference between speeches in a silent environment and a noisy environment. For this reason, in the method which compulsorily changes the speaking style, it is difficult to execute authentication of high precision even where biometrics information DIN changes dramatically in a short period of time (for example, between early morning and daytime). The present embodiment also solves this problem.
In the present embodiment, a user can properly modify various parameters used for authentication or update, addition or deletion of a dictionary DIC. Hence, it is possible to realize authentication compliant with the user's request. For example, as the threshold value VTHR1 and the threshold value VTHR2 become larger, the update or addition of a dictionary DIC is executed at a higher frequency. In contrast, as the threshold value VTHR1 and the threshold value VTHR2 become smaller, authentication of higher precision is realized. In addition, when the maximum number nMAXDIC of dictionaries DIC is larger, more dictionaries DIC can be stored in the storage device 20 to correspond to more various speeches. In contrast, when the maximum number nMAXDIC of dictionaries DIC is smaller, the capacity of data stored in the storage device 20 can be reduced.
Various modifications can be applied to the above embodiment. Various modified embodiments will hereinafter be described in detail. The following embodiments may also be appropriately combined.
Although a configuration for executing authentication based on biometrics information DIN extracted from a voice has been disclosed in the above embodiment for illustrative purposes, the biometrics information DIN used for the authentication may be properly modified. For example, various feature amounts, such as a vein pattern of each part of the body such as a hand or retina, a face image, a fingerprint, an iris, or a handwriting, may be used for the authentication as the biometrics information DIN. Where this biometrics information DIN is used, a device for recognizing an image of each part of the body or the handwriting is employed as the input unit 12. Because the biometrics information DIN such as the handwriting or face shape, together with the voice illustrated in the above embodiment, may change dramatically in a short period of time, the present invention in which authentication of high precision is realized irrespective of a change in the biometrics information DIN is particularly preferably employed in the biometrics authentication apparatus 100 using this biometrics information DIN for the authentication.
Although a configuration in which the auxiliary authenticator 38 executes the auxiliary authentication based on a password inputted from the operating unit 40 has been disclosed in the above embodiment for illustrative purposes, the auxiliary authentication method may be properly modified. For example, a configuration for using a password inputted as a voice from the input unit 12 for the authentication may be employed instead of or together with the configuration for using the password inputted from the operating unit 40 for the authentication. That is, the auxiliary authenticator 38 executes the authentication by specifying a password inputted as a voice to the input unit 12 using a voice recognition technique and collating the specified password with a password registered in the storage device 20. It will be understood from the above illustration that the auxiliary authenticator 38 is a part for executing the auxiliary authentication separately from the authentication by the authenticator 32 (in more detail, based on information (a password) acquired from the subject separately from biometrics information DIN).
Although a configuration for deleting dictionaries DIC one by one has been disclosed in the above embodiment for illustrative purposes, a configuration for deleting a plurality of dictionaries DIC at a time may be employed. For example, at step SC12 of
The input unit 12 and the analyzer 14 may be properly omitted from the biometrics authentication apparatus 100. For example, a configuration in which a terminal with the input unit 12 and analyzer 14 is connected to the biometrics authentication apparatus 100 through a communication network may be employed. In this configuration, the biometrics authentication apparatus 100 receives biometrics information DIN generated by the analyzer 14 of the terminal over the communication network and then uses the received biometrics information DIN for authentication. In the above configuration, means for receiving the biometrics information DIN from the communication network functions as an information acquisition part in one embodiment of the present invention.
Although a configuration in which the distance DST_i between biometrics information DIN and biometrics information DO is used for authentication has been disclosed in the above embodiment for illustrative purposes, an index representing the similarity between the biometrics information DIN and the biometrics information DO is not limited to the distance. For example, a configuration in which the authentication is executed based on a parameter (index) increasing as the biometrics information DIN and the biometrics information DO become more similar may be employed. In this configuration, the threshold value VTHR2 is set to a value smaller than the threshold value VTHR1 (namely, a value representing dissimilarity). Then, it is determined at step SA11 or step SB11 whether the index is larger than or equal to the threshold value VTHR1 (namely, whether the index represents similarity), and it is determined at step SA15 or step SB15 whether the index is larger than or equal to the threshold value VTHR2.
Each parameter (for example, the threshold value VTHR1 or threshold value VTHR2) used for the processing by the controller 30 may be stored in the storage device 20 individually with respect to a plurality of users. The controller 30 executes various processes such as authentication or update, addition or deletion of a dictionary DIC based on a parameter group that the subject designates ahead of the authentication, among a plurality of parameter groups. In this configuration, in the case where one electronic appliance is shared by a plurality of users, it is possible to appropriately authenticate each user, resulting in an increase in convenience of the electronic appliance.
Number | Date | Country | Kind |
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2006-241157 | Sep 2006 | JP | national |