JP2010035914A - Personal identification apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a personal identification apparatus that controls failures in personal identification caused by the soil stuck to transparent board. <P>SOLUTION: The personal identification apparatus includes a light source 10, an imaging means 40 for imaging an optical pattern formed by light radiated from the light source, a finger guide plate 20 located between the light source and the imaging means for positioning a fingertip print in opposition to the imaging means in non-contact conditions, a transparent board 30 located between the finger guide plate and the imaging means for preventing the entry of water or dust into the imaging means, and an image processor 50 to attain personal identification through the image processing of an optical pattern after it passes through the fingertip and is imaged by the imaging means, while the fingertip is placed on the guide plate. The image processor 50 includes a soil detection and disposal part that detects the transparent board soil conditions, with no fingertip put on the finger guide plate, by processing the image of the optical pattern, and that if much soil is detected at a prescribed level or higher, determines that the finger guide plate is soiled enough to obstruct the personal identification. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a personal identification device that performs personal authentication based on an image obtained from a fingerprint of a fingertip that is a subject.

  FIG. 9 is a configuration diagram of a conventional personal identification device (see, for example, Patent Document 1). The personal identification device in Patent Document 1 includes a light source 110, a finger guide plate 120, an imaging unit 140, and an image processing unit 150. Further, the imaging unit 140 includes an imaging lens 141 and an imaging element 142.

  A fingertip 100 that is a subject has a fingerprint 101. The fingerprint 101 has a concavo-convex pattern composed of convex portions 102 and concave portions 103. The finger guide plate 120 is provided with an opening 121 so as to hold the fingertip 1 and hold the fingerprint 101 in a non-contact state.

  The light source 110 is provided to irradiate light on the nail side of the fingertip 1 (that is, the opposite side of the fingerprint 101). As this light source 110, what emits the projection light containing the light of a red light thru | or a near infrared region, or the light of a red light thru | or a near infrared light region is used. Light (111) emitted from the light source 110 passes through the inside of the fingertip 1 (112), and further becomes light (112) that has passed through the fingerprint 101.

  The imaging unit 140 is provided to face the fingerprint 101, passes through the fingertip 100, and images light (113) from the light source 110 that has passed through the fingerprint 101. The imaging means 140 includes an imaging lens 141 and an imaging element 142. The imaging element 142 images the light pattern stored by the imaging lens 141 and outputs it as image data.

  The image processing unit 150 performs image processing on the image data of the light pattern output from the imaging unit 140 to obtain fingerprint data, and identifies an individual based on the fingerprint data. More specifically, the image processing unit 150 calculates a difference in transmittance generated between the convex portion 102 and the concave portion 103 when light emitted from the light source 110 provided on the fingernail side passes through the fingertip 100. And acquired as image data via the imaging means 140. Here, since the transmittance of the concave portion 103 is higher than that of the convex portion 102 of the fingerprint 101, an image is obtained in which the convex portion 102 is dark and the concave portion 103 is bright.

  In the personal identification device configured as described above, although not shown, it is common to close the opening 121 between the imaging lens 141 and the finger 100 with a protective plate. This is installed for the purpose of preventing the image forming lens 141 from being damaged by entry of dust such as moisture or dust or foreign matter from the opening 21. Here, the protection plate is formed of, for example, a transparent plate so as not to block the light 113 that has passed through the fingerprint 101.

JP 2003-85538 A

However, the prior art has the following problems.
In the conventional personal identification device, when the protective plate (transparent plate) is dirty, the dirty portion blocks the light 113. Therefore, in the image output from the imaging unit 140, the light and dark pattern corresponding to the unevenness of the fingerprint is lost in this dirty portion. As a result, there is a problem in that the identification performance of the apparatus is deteriorated due to the lack of the light and dark pattern of the fingerprint that should originally exist. Furthermore, due to the deterioration of the identification performance, there is a problem that useless authentication failures increase and the number of user operations increases uselessly.

  The present invention has been made to solve such a problem, and an object of the present invention is to obtain a personal identification device that can suppress the occurrence of useless authentication failure due to dirt on a transparent plate.

  A personal identification device according to the present invention includes a light source that emits light from the fingernail side of a subject, an imaging unit that images a light pattern formed by imaging light emitted from the light source, and a light source and an imaging unit. Located between the finger guide plate for positioning the fingerprint portion of the fingertip in a state of being opposed to the image pickup means in a non-contact manner, and located between the finger guide plate and the image pickup means to prevent the image pickup means from picking up the optical pattern Image processing of the light pattern transmitted through the subject imaged by the imaging means in a state where the subject is placed on the transparent plate and the finger guide plate that prevent moisture or dust from entering the imaging means. In the personal identification device provided with the image processing unit for performing personal authentication, the image processing unit performs the image processing on the light pattern in a state where the subject is not placed on the finger guide plate, and thereby the stain state of the transparent plate Detect And has a contamination detection processing unit for determining the dirt hinder the personal authentication has occurred by detecting a predetermined level or more soil.

  According to the personal identification device of the present invention, a stain state of a transparent plate is detected by image processing of a light pattern in a state where a subject is not placed on a finger guide plate by using an optical system for performing personal authentication. In addition, it is possible to suppress the occurrence of useless authentication failure due to dirt on the transparent plate by judging that dirt that hinders personal authentication has occurred by detecting dirt of a predetermined level or higher. Can be obtained.

  Hereinafter, a preferred embodiment of a personal identification device of the present invention will be described with reference to the drawings.

Embodiment 1 FIG.
FIG. 1 is a configuration diagram of a personal identification device according to Embodiment 1 of the present invention. 1 includes a light source 10, a finger guide plate 20, a transparent plate 30, an imaging means 40, and an image processing unit 50. The normal operation until the light emitted from the light source 10 provided on the nail side passes through the inside of the fingertip 1 and is imaged by the imaging means 40 and is subjected to the authentication processing by the image processing unit 50 is the same as the conventional technology. The same.

  However, the personal identification device according to the first exemplary embodiment is able to determine that the contamination that hinders personal authentication has occurred in the image processing unit 50 by detecting the contamination of a predetermined level or higher. It is characterized by having a dirt notification part 52 for notifying the outside of the judgment result by the part 51 and the dirt detection processing part 51.

  Therefore, the functions and operations of the dirt detection processing unit 51 and the dirt notification unit 52 will be mainly described below. The technical feature of the present invention resides in the dirt detection processing unit 51, and the dirt notification unit 52 is not an essential component.

  First, the operation of the dirt detection processing unit 51 that detects dirt on the transparent plate 30 will be described. FIG. 2 is an internal configuration diagram of the dirt detection processing unit 51 according to Embodiment 1 of the present invention. The stain detection processing unit 51 includes a stain detection activation unit 51a and a stain determination unit 51b. When the dirt detection activation unit 51a determines that the finger output as the subject is not shown in the image output from the imaging unit 40, the dirt detection activation unit 51a detects the dirt on the transparent plate 30 with respect to the subsequent dirt determination unit 51b. Give a start command to do.

  For example, when the image output from the imaging unit 40 is a light pattern having a brightness equal to or higher than a predetermined luminance, the dirt detection activation unit 51a determines that the finger as the subject is not captured. Can do.

  On the other hand, when receiving an activation command from the contamination detection activation unit 51a, the contamination determination unit 51b processes an image without a finger, detects the contamination state of the transparent plate 30, and detects the contamination above a predetermined level. By detecting this, it is determined that the contamination that hinders personal authentication has occurred. A specific method for determining contamination by the contamination determination unit 51b will be described later with reference to a flowchart.

  The dirt determination unit 51b transmits a signal corresponding to the dirt state to the dirt notification unit 52. As an example, the dirt determination unit 51b can notify the detection result in three stages: “dirty degree is small”, “dirty degree is medium”, and “dirty degree is large”.

  Next, the operation of the stain notification unit 52 based on the detection result by the stain determination unit 51b will be described. The dirt notification unit 52 receives a signal corresponding to the detection result by the dirt determination unit 51b and notifies the detection result to the outside. As an example, each operation in the case where the above-described three-stage notification of “small degree of dirt”, “medium degree of dirt”, and “large degree of dirt” is received will be specifically described.

  FIG. 3 is a flowchart of a series of processes performed by the dirt notification unit 52 according to Embodiment 1 of the present invention. In step S301, the stain notification unit 52 receives a signal corresponding to the detection result by the stain determination unit 51b. Next, in step S <b> 302, the stain notification unit 52 determines which of the three levels of notification of “dirty degree is small”, “dirty degree is medium”, and “dirty degree is large” for the dirty state of the transparent plate 30.

(1) Behavior when a notification of “dirty degree is low” is received When the dirty notification unit 52 receives a notification of “low dirt level”, the dirt on the transparent plate 30 does not interfere with the authentication process. The level is determined, and in particular, the outside process is not performed and the series of processes is terminated.

(2) Behavior when receiving notification of “medium contamination” The contamination notification unit 52 performs the processing in step S303 and subsequent steps when receiving the notification of “medium contamination”. First, in step S303, the dirt notification unit 52 notifies the user and the administrator of this information via an external output, thereby prompting “caution”. However, in this case, although notification is made to the outside, functions such as normal authentication processing in the image processing unit 50 remain valid and user authentication can be continued.

  In addition, as a specific example of the notification means by the dirt notification unit 52, for example, when an LED indicating the level of dirt is turned on or a display device such as a liquid crystal panel is provided, characters and pictures are displayed on the screen. It may be displayed, or when the apparatus has communication means such as a network, notification may be made using the network. Then, the dirt notification unit 52 identifies and announces that “the degree of dirt is about” by the tone color, display color, display character, and the like.

  The user or administrator who has received the notification that “the degree of contamination is moderate” performs cleaning of the transparent plate 30. Next, in step S304, the dirt determination unit 51b determines whether or not a dirt reconfirmation command after completion of cleaning has been received from the user or the administrator. In addition to waiting for a reconfirmation command from the user or administrator, the process of reconfirming dirt is automatically performed periodically after a certain period of time, so that the process proceeds to reconfirmation of dirt. It can also be monitored.

  If there is a stain reconfirmation command, the process proceeds to step S305, where the stain notification unit 52 instructs the stain determination unit 51b to perform stain detection again. In step S306, the stain notification unit 52 receives again three-stage notifications of “smudge level is small”, “soil level is medium”, and “stain level is large” in accordance with the detection result by the stain determination unit 51b.

  Next, in step S307, the contamination notifying unit 52 reconfirms the contamination state of the transparent plate 30 as a result of notification in three stages: “dirty level is small”, “dirty level is medium”, and “dirt level is large”. Is determined.

  If the notification of “the degree of dirt is small” is received, the process proceeds to step S308, where the dirt notifying unit 52 determines that the dirt on the transparent plate 30 is clean, resets the notification to the outside, and performs a series of processing. Exit. As a result, the user can perform the authentication operation again. On the other hand, when the notification of “medium contamination level” is still received, the contamination notification unit 52 continues the notification to the outside as it is, and performs the processing after the previous step S304.

(3) Behavior when receiving notification of “large degree of dirt” When the notice of “large degree of dirt” is received, the dirt notification unit 52 performs the processing from step S309. First, in step S309, the dirt notification unit 52 notifies the user and the administrator of this information via an external output, thereby prompting “warning”. Further, in step S310, the dirt notification unit 52 determines that the personal authentication cannot be normally performed because “large degree of dirt” is detected, and stops functions such as normal authentication processing in the image processing unit 50. . Therefore, in such a state that “the degree of dirt is large” is notified, even if the user places a finger on the finger guide plate 20, the authentication process is not performed.

  The user or administrator who has received the notification that “the degree of contamination is large” executes cleaning of the transparent plate 30. Next, in step S311, the dirt determination unit 51b determines whether or not a dirt reconfirmation instruction after completion of cleaning has been received from the user or the administrator. When reconfirming the dirt, the process can be shifted to a process for reconfirming the dirt after a predetermined time has elapsed, in addition to waiting for a reconfirmation command from the user or the administrator.

  If there is a dirt reconfirmation command, the process advances to step S312, and the dirt notification unit 52 instructs the dirt determination unit 51b to perform the dirt detection again. Then, in step S313, the dirt notification unit 52 receives again the three-stage notification of “small dirt level”, “medium dirt level”, and “large dirt level” according to the detection result by the dirt judgment unit 51b.

  Next, in step S314, the contamination notifying unit 52 reconfirms the contamination state of the transparent plate 30 as a result of notification in three stages: “dirty level is small”, “dirty level is medium”, and “dirt level is large”. Is determined.

  If the notification “dirt level is small” is received, the process proceeds to step S315, where the stain notification unit 52 determines that the stain on the transparent plate 30 is clean, resets the notification to the outside, and performs a series of processing. Exit. As a result, the user can perform the authentication operation again.

  On the other hand, when the notification of “large degree of dirt” is still received, or when the notice of “medium degree of dirt” is received after improvement, the dirt notification unit 52 continues the notification to the outside as it is. Then, the authentication processing by the image processing unit 50 is kept stopped, and the processing after the previous step S311 is performed.

  Note that the dirt detection activation unit 51a described with reference to FIG. 2 may always process an image output from the imaging unit 40 and determine that a finger is not reflected in the image, for example. . In addition, an input unit such as a button for activating dirt detection may be provided, and a user or an administrator may periodically start it using the input unit. Further, the clock function may be activated in a time zone (for example, midnight) where it is assumed that there is no user.

Next, a specific example of processing executed by the dirt determination unit 51b will be described.
FIG. 4 is a flowchart showing a series of processes executed by the dirt determination unit 51b in the first embodiment of the present invention. First, in step S401, the dirt determination unit 51b acquires an image in which no finger is placed and the light source 10 is in effect. In this image, in addition to the dirt on the transparent plate 30, there is unevenness in the light irradiated by the light source 10 (the peripheral portion is darker than the vicinity of the center of the transparent plate 30).

  Accordingly, in step S402, the dirt determination unit 51b performs a high-pass filter on the input image. Light unevenness has a low spatial frequency, and dirt has a high spatial frequency. Therefore, by appropriately setting the parameters of the high-pass filter, it is possible to remove light unevenness and leave only dirt.

  Next, in step S403, the dirt determination unit 51b creates a histogram from the image subjected to the high-pass filter. This is a process for obtaining the frequency of pixel values for all the pixels constituting the image. Furthermore, in step S404, the stain determination unit 51b uses the histogram to determine the number N of pixel values that are equal to or greater than the threshold value using a threshold value that is appropriately set in advance, and the average value M of the pixel values of those pixels. Ask for.

  FIG. 5 is a diagram illustrating the determination logic of the contamination state in the contamination determination unit 51b according to the first embodiment of the present invention. In FIG. 5, THn1, THn2, THm1, and THm2 are thresholds appropriately determined in advance. THn1 and THn2 are threshold values for the number of pixels N and have a relationship of THn1 <THn2. Further, THm1 and THm2 are thresholds for the average value M and have a relationship of THm1 <THm2.

  In step S405, the stain determination unit 51b uses the determination logic shown in FIG. 5 to change the stain state to “dirty level is small”, “dirty level is medium”, or “based on the histogram after the high-pass filter process”. It can be identified in three stages of “large degree of dirt”.

  Further, in the above description, it has been described that the authentication process is continued when the dirt state is “small dirt degree” or “medium dirt degree”. In the authentication process in this case, the detection level of the personal authentication when it is detected that “the degree of dirt is small” can be set higher than the detection level of the personal authentication when it is detected that “medium degree of dirt” is detected.

  As described above, according to the first embodiment, an optical system that performs personal authentication is used, and the light pattern that has passed through the transparent plate is captured as an image in a state where the subject is not placed on the finger guide plate. Furthermore, after performing high-pass filter processing and histogram processing, it is possible to detect a contamination state using a predetermined threshold value, and to detect that contamination that hinders personal authentication has occurred by detecting contamination above a predetermined level. it can. As a result, it is possible to obtain a personal identification device that can suppress the occurrence of useless authentication failure due to dirt on the transparent plate.

  Further, when a means for notifying the outside of the occurrence of dirt on the transparent plate is provided, the necessity of cleaning the apparatus can be accurately shown to the user or the administrator. The notification contents can also be ranked according to the level of the dirt state. In addition, maintenance (cleaning) costs can be minimized.

  In addition, depending on the dirt state, the authentication process or the feature amount registration process in the state where the dirt is attached can be stopped, and stable collation performance can be maintained.

  Further, the collation threshold value that determines the safety includes the tolerance of missing fingerprint images. For this reason, since the fingerprint imaging interference due to dirt is reduced in this apparatus, the tolerance for missing fingerprint images can be tightened and the collation threshold can be raised, and as a result, safety can be improved. .

  In addition, since it is possible to accurately indicate the necessity of apparatus cleaning from the host system of this apparatus to the user, it is possible to minimize the cost for maintenance (cleaning). Moreover, since this apparatus does not need to touch an apparatus at the time of collation, it is hygienic, and a user is not accidentally injured and is safe.

Embodiment 2. FIG.
In the first embodiment, authentication processing and detection of dirt on a transparent plate provided in an opening between finger guide plates using light vertically falling from one light source located above the image pickup means 40 The case where processing is performed has been described. On the other hand, in the second embodiment, a case will be described in which authentication processing and dirt detection processing are performed using different configurations.

  FIG. 6 is a partial configuration diagram of the personal identification device according to Embodiment 2 of the present invention. The personal identification device in FIG. 6 includes two light sources 10a and 10b, a finger guide plate 20a, a transparent plate 30a, and an imaging means 40a. In the second embodiment, the point that two light sources are provided, and the transparent plate 30a is provided between the finger guide plate 20a and the imaging means 40a, not the opening between the finger guide plates 20a. Two points are different from those of the first embodiment.

  The imaging means 40a in FIG. 6 has a lens and an imaging element, although not shown. As shown in FIG. 6, the imaging unit 40a according to the second embodiment has an imaging range that can capture not only the finger but also the lower surface of the finger guide plate 20a facing the imaging unit 40a. .

  The transparent plate 30a is located between the finger guide plate 20a and the image pickup means 40a, and has a function of preventing the image pickup by the image pickup means 40a and preventing the entry of dust such as moisture and dust into the apparatus. is doing. Further, the two light sources 10a and 10b are located obliquely above and to the left and right of the finger that is the subject. When imaging a fingerprint, the user's finger is irradiated with light, and when there is no user's finger, a transparent plate It has a function of reflecting to 30a and irradiating the lower surface of the finger guide plate 20a.

  FIG. 7 is an overall configuration diagram of the personal identification device according to Embodiment 2 of the present invention. In FIG. 7, the image processing unit 60 includes an imaging control unit 61, an extraction determination unit 62, a registered fingerprint database 63, a collation unit 64, and a collation threshold setting unit 65.

First, the flow of normal collation processing will be described.
The imaging control unit 61 turns on the light sources 10a and 10b when detecting that the user's finger is placed from the image captured by the imaging unit 40a. Further, the imaging control unit 61 acquires a fingerprint image from the transmitted light after turning on the light sources 10 a and 10 b and transfers the fingerprint image to the extraction determination unit 62. The extraction determining unit 62 extracts feature data necessary for fingerprint matching from the acquired fingerprint image.

  The extraction determining unit 62 can store the extracted feature data of the user's fingerprint as a reference pattern in the registered fingerprint database. When the reference pattern has already been registered and fingerprint verification is performed, the extraction determination unit 62 sends the extracted feature data of the user's fingerprint to the verification unit 64 and causes the verification unit 64 to perform fingerprint verification. Get the verification result.

  The collation unit 64 collates the feature data of the fingerprint extracted by the extraction determination unit 62 with the fingerprint feature data serving as the reference pattern stored in the registered fingerprint database, and collates with the host system 70 and the extraction determination unit 62. Output the result. Further, the collation threshold setting unit 65 has a function of receiving a input from the host system 70 and setting a threshold used in the collation process executed by the collation unit 64.

Next, the stain detection process flow of the transparent plate 30a will be described.
The imaging control unit 61 also turns on the light sources 10a and 10b when detecting that the user's finger is not placed from the image captured by the imaging unit 40a. Further, the imaging control unit 61 turns on the light sources 10a and 10b, acquires a captured image including the lower surface of the finger guide plate 20a irradiated with the light reflected by the transparent plate 30a, and transfers the captured image to the extraction determination unit 62.

  From the acquired captured image including the lower surface of the finger guide plate 20a, the extraction determination unit 62 determines whether the lower surface of the finger guide plate 20a is uniformly irradiated with light because the transparent plate 30a is not soiled, or the transparent plate Since 30a is dirty, it is detected whether partial brightness exists on the lower surface of the finger guide plate 20a. Furthermore, the extraction determining unit 62 outputs a notification signal to the host system 70 when detecting that partial brightness exists. That is, the extraction determination unit 62 in FIG. 7 has the function of the dirt notification unit 52 in the image processing unit 50 shown in FIG. 1 in the first embodiment.

  Next, the flow of inspecting the transparent plate 30a for dirt in the second embodiment will be described. FIG. 8 is a flowchart showing a series of flows of the stain detection process for the transparent plate 30a according to the second embodiment of the present invention. The flowchart of FIG. 8 shows the flow of continuously inspecting the stain on the transparent plate 30a after the result of the normal collation processing is NG.

  However, the start of the stain detection process of the transparent plate 30a in the second embodiment is not limited to such a case. For example, it is conceivable to periodically perform a dirt detection process. Alternatively, it is conceivable to perform the stain detection process after registering the feature data in the registered fingerprint database 63 or before performing the registration process.

  In step S801, the imaging control unit 61 determines whether there is a user's finger in the image captured by the imaging unit 40a. When it is determined that there is no finger, the light sources 10a and 10b are turned on. Since the light emitted from the light sources 10a and 10b does not have the finger 1, it directly reflects on the transparent plate 30a and is reflected on the lower surface of the finger guide plate 20a.

  At this time, if the transparent plate 30a is not soiled, the light emitted from the light sources 10a and 10b is reflected at the same reflectance in any part of the transparent plate 30a and uniformly illuminates the lower surface of the finger guide plate 20a. On the other hand, when dirt is attached to the transparent plate 30a, the reflectance of the portion of the transparent board 30a where the dirt is attached changes. That is, the light reflected by the portion of the transparent plate 30a where the dirt is attached becomes darker (or brighter) than the light reflected by the portion of the transparent plate 30a where the dirt is not attached. For this reason, when there exists a part to which the stain | pollution | contamination of the transparent board 30a adhered, the lower surface of the finger guide board 20a becomes partially dark (or becomes bright).

  In this state, the imaging control unit 61 controls the imaging unit 40a to capture an image including the lower surface of the finger guide plate 20a, and transfers the image to the extraction determination unit 62 as a lower surface captured image of the finger guide plate 20a.

  Upon receiving the lower surface captured image of the finger guide plate 20a, the extraction determination unit 62 analyzes whether the lower surface of the finger guide plate 20a is uniformly illuminated or partially dark (or bright). If the extraction determination unit 62 detects a partially dark (or bright) part, the extraction determination unit 62 determines that the transparent plate 30 a is dirty and outputs a notification signal to the host system 70.

  For example, when one pixel of an image captured by the imaging unit 40a is an 8-bit monochrome density signal such as black when the signal value = 0 and white when the signal value = 255, the extraction determining unit 62 determines the signal of each pixel. The difference between the maximum value and the minimum value is calculated by reading the value, and if the calculated value is larger than a threshold value (for example, 10), it can be determined that there is partial brightness.

  Further, by using a plurality of threshold values for such determination, it is possible to perform the level determination of the dirt state as described in the first embodiment.

  As described above, according to the second embodiment, an optical system that performs personal authentication is used to directly reflect on the transparent plate when the subject is not placed on the finger guide plate, and the lower surface of the finger guide plate. The light pattern reflected in is captured as an image. Furthermore, by obtaining the distribution of the luminance difference of the captured image and determining whether the difference is equal to or greater than the predetermined luminance difference, it is possible to determine that a stain that interferes with personal authentication has occurred. As a result, an effect similar to that of the first embodiment can be obtained.

It is a block diagram of the personal identification device in Embodiment 1 of this invention. It is an internal block diagram of the stain | pollution | contamination detection process part in Embodiment 1 of this invention. It is a flowchart of a series of processes by the dirt notification part in Embodiment 1 of this invention. It is the flowchart which showed a series of processes performed by the stain | pollution | contamination judgment part in Embodiment 1 of this invention. It is the figure which showed the determination logic of the stain | pollution | contamination state in the stain | pollution | contamination judgment part in Embodiment 1 of this invention. It is a partial block diagram of the personal identification device in Embodiment 2 of this invention. It is a whole block diagram of the personal identification device in Embodiment 2 of this invention. It is a flowchart which shows a series of flows of the stain | pollution | contamination detection process of the transparent plate in Embodiment 2 of this invention. It is a block diagram of the conventional personal identification device.

Explanation of symbols

  10, 10a, 10b Light source, 20, 20a Finger guide plate, 21 Aperture, 30, 30a Transparent plate, 40, 40a Imaging means, 50 Image processing unit, 51 Dirt detection processing unit, 51a Dirt detection activation unit, 51b Dirt judgment Unit, 52 dirt notification unit, 60 image processing unit, 61 imaging control unit, 62 extraction determination unit, 63 registered fingerprint database, 64 collation unit, 65 collation threshold setting unit, 70 host system.

Claims (6)

A light source that emits light from the fingernail side of the subject,
Imaging means for imaging a light pattern formed by imaging light emitted from the light source;
A finger guide plate that is positioned between the light source and the imaging means and positions the fingerprint portion of the fingertip in a state of facing the imaging means in a non-contact manner;
A transparent plate that is located between the finger guide plate and the imaging means and prevents entry of dust such as moisture or dust into the imaging means without interfering with the imaging of the light pattern by the imaging means;
A personal identification device comprising: an image processing unit that performs personal authentication by performing image processing on a light pattern transmitted through the subject imaged by the imaging unit in a state where the subject is placed on the finger guide plate In
The image processing unit detects a stain state of the transparent plate by performing image processing on a light pattern in a state where the subject is not placed on the finger guide plate, and detects a stain of a predetermined level or more. A personal identification device comprising a dirt detection processing unit that judges that dirt that interferes with authentication has occurred. The personal identification device according to claim 1,
The dirt detection processing unit changes the detection level of the personal authentication according to the detected dirt state when the detected dirt state of the transparent plate is less than the predetermined level. apparatus. The personal identification device according to claim 1 or 2,
The stain detection processing unit, when detecting a stain of the predetermined level or more, stops the personal authentication by the image processing unit until the stain state of the transparent plate becomes less than the predetermined level. Personal identification device. The personal identification device according to any one of claims 1 to 3,
The dirt detection processing unit generates a filtered image by performing high-pass filtering on an image obtained by the light pattern in a state where the subject is not placed on the finger guide plate, and a histogram is displayed on the filtered image. Analyzing to determine a stain state of the transparent plate, and detecting a stain of the predetermined level or more based on a histogram analysis result to determine that a stain that interferes with personal authentication has occurred. Personal identification device. The personal identification device according to any one of claims 1 to 3,
The personal identification device, wherein the dirt detection processing unit detects a dirt state of the transparent plate based on light and darkness of a light pattern on a lower surface of the finger guide plate facing the imaging unit. The personal identification device according to any one of claims 1 to 5,
The personal identification device further comprising an alarm processing unit for notifying an external alarm when the contamination detection processing unit in the image processing unit detects the contamination of the predetermined level or more.

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