JP4350547B2 - Personal authentication device - Google Patents

Description

  The present invention relates to a personal authentication device using biometric information, and more particularly to a personal authentication device using a blood vessel pattern of a finger as biometric information.

  For example, a key is conventionally used to release a door lock of an automobile and start an engine. This conventionally used key may be driven by a malicious person other than the owner of the car due to the key being stolen or keyhole picking.

  Therefore, in order to increase security, it is known to use a fingerprint, which is biometric information, as a means for personal authentication instead of a key to release the door lock of an automobile or start an engine (see, for example, Patent Documents 1 and 2). .)

  However, since fingerprints can be counterfeited, a method of personal authentication using an image including a blood vessel pattern of a finger that differs depending on an individual as biometric information has been proposed as a method for further enhancing security (for example, Patent Documents). 3).

  In this method, when light is radiated from a light source including a component of near-infrared light to the finger (defined as an infrared light source in the present specification and claims), the finger is transmitted through the finger and re-radiated from the finger. Since the intensity distribution of infrared light includes information on the blood vessel pattern of the finger (mainly the vein pattern), this is detected by the imaging means, and the detected finger blood vessel pattern matches the pre-registered finger blood vessel pattern. By determining, the person who registered the finger blood vessel pattern is specified and authenticated.

  In this way, as a personal authentication device that performs personal authentication using the blood vessel pattern of the finger as biometric information, infrared light is irradiated toward the finger from an infrared light source disposed on the abdomen or side of the finger, There is known a personal authentication device that acquires an image including a blood vessel pattern of a finger by capturing an image of the abdominal side of the subject using an imaging unit (see, for example, Patent Document 4).

  In such a personal authentication device, infrared light irradiated from the infrared light source toward the finger and incident on the inside of the finger is transmitted while being scattered and absorbed by the living tissue, and part of the light is reflected (re-radiated) to the irradiation side. However, since the degree of this reflection varies among individuals, the light amount output of the infrared light source is controlled.

Specifically, the control of the light amount output of the infrared light source is performed as follows, for example. That is, the brightness of the finger area of the image acquired by the imaging means is fed back, and when the brightness of the finger area is smaller than the target brightness, the light output is increased, and the brightness of the finger area is higher than the target brightness. When it is large, the light amount output is controlled to be small, and the light amount output of the infrared light source is controlled so that the brightness of the obtained image becomes the target brightness.
JP 61-53972 A Japanese Patent Laid-Open No. 6-72291 JP 2001-184507 A JP 2000-5148 A

  In the control of the light amount output of the infrared light source as described above, when irradiation with the infrared light source is performed without placing a finger, there is no reflected light from the finger, and the image acquired by the imaging means is a background image. Thus, the brightness of the background image is always input to the feedback loop performing the control regardless of the light amount output of the infrared light source. In this case, when the brightness of the background image is darker than the target brightness by the amount of light reflected from the finger, feedback control is performed so that the light output of the infrared light source is increased, and Control is performed so that the amount of light is maximized. This increases unnecessary current consumption and causes heat generation and deterioration of the infrared light source.

  An object of the present invention is to provide a personal authentication apparatus that does not irradiate an infrared light source when there is no finger by detecting the presence or absence of a finger.

In order to achieve the above object, an invention according to claim 1 is provided with an infrared light source and an imaging means, irradiates the living body with infrared light from the infrared light source, reflects the light after entering the living body, and reflects the living body. and blood vessel pattern of the finger re-radiated by the infrared light obtained by imaging by the imaging means from the surface, in the personal authentication apparatus for identifying an individual by collating the blood vessel pattern of the finger that is registered in advance,
Providing an auxiliary light source for irradiating the living body with infrared light toward the imaging direction side of the imaging means;
The light intensity when there is no living body is measured in advance with the light-receiving element provided separately from the imaging means or the imaging means,
If the value of the light intensity when there is no biological body that has been measured in advance is smaller than a predetermined threshold, after turning on the auxiliary light source, measure the light intensity by the imaging means or the light receiving element, It is determined that there is a living body when the value of the light intensity when the auxiliary light source is turned on is larger than a value obtained by adding a predetermined value to the threshold value, and the light intensity when there is no living body measured in advance Is equal to or greater than the predetermined threshold value, the light intensity is measured by the imaging means or the light receiving element while the auxiliary light source is turned off, and the light intensity value when the auxiliary light source is turned off is the threshold value. It is characterized by having a living body determination function that determines that there is a living body when the value is smaller than a value obtained by subtracting a predetermined value from .

  According to the present invention, it is possible to reliably detect whether or not a finger is placed on the finger placement unit before performing personal authentication by turning on the infrared light source. By detecting the presence / absence of the finger as described above, an unnecessary increase in current consumption can be suppressed by not irradiating the infrared light source when the finger is not placed.

  The best mode for carrying out the personal authentication apparatus according to the present invention will be described below with reference to FIGS.

  First, a first example of an embodiment of a personal authentication device according to the present invention will be described with reference to FIGS.

  A personal authentication device 100 shown in FIG. 1 includes a microcomputer 101, an infrared light source 102, a finger placement unit 103, an imaging unit 104, a drive circuit 105, a memory 106, and a power supply circuit 107. Further, the personal authentication device 100 of this example includes an auxiliary light source 108 for detecting the finger F.

  The personal authentication device 100 including such a component illuminates the infrared light source 102 to irradiate the finger F placed on the finger placement unit 103 with infrared light and reflects the light after being incident on the finger F. The reflected light re-radiated from the surface on the ventral side of the finger F is imaged as a finger image including a blood vessel pattern on the imaging means 104, and personal authentication is performed using the obtained image including the blood vessel pattern.

  The microcomputer 101 energizes the infrared light source 102 and the auxiliary light source 108 by the drive circuit 105 and irradiates the finger F placed on the finger placement unit 103 with infrared light from the infrared light source 102 and the auxiliary light source 108. It is like that. Further, the microcomputer 101 determines whether or not the finger F is placed on the finger placement unit 103, whether or not the detected blood vessel pattern matches the pre-registered blood vessel pattern, or the infrared light source 102 Control of the entire personal authentication apparatus 100 such as light amount control is also performed.

  The finger F is placed on the finger placement unit 103 so that the ventral side of the finger F faces the imaging unit 104. Infrared light is emitted from the infrared light source 102 provided on both sides of the finger rest 103 toward the finger F placed on the finger rest 103 in this manner.

  Examples of the infrared light source 102 include a light emitting diode. The infrared light source 102 is driven by, for example, a drive circuit 105 shown in FIG. The drive circuit 105 of this example includes resistors 105a to 105c and an Nch-MOS transistor 105d. The microcomputer 101 outputs a PWM (Pulse Width Modulation) signal capable of controlling the duty ratio, and drives the Nch-MOS transistor 105d. As this drive frequency, several 10 to several 100 kHz is used. Here, if the light reception integration time (shutter time) of the image sensor (described later) of the image pickup means 104 shown in FIG. 1 is sufficiently longer than the drive cycle of the Nch-MOS transistor 105d, the image sensor of the image pickup means is low. It becomes a band pass characteristic. That is, only the DC component is received, and a uniform image is obtained. In addition to the PWM signal, a DC voltage signal, a PAM (Pulse Amplitude Modulation) signal, or the like can be used as the drive signal.

  Infrared light irradiated from the infrared light source 102 toward the finger F enters the finger F and scatters, and is absorbed by hemoglobin of blood in the blood vessel of the finger F. The infrared light incident on the inside of the finger F is reflected inside the finger F and is emitted again from the ventral side of the finger F, and a finger image including a blood vessel pattern is formed on the imaging means 104. .

  The image pickup means 104 includes an infrared transmission filter, a lens, and an image sensor such as a CCD or a CMOS. The infrared transmission filter is used to cut a wavelength band that causes noise to obtain a blood vessel pattern and transmit only infrared light including the blood vessel pattern. The imaging unit 104 captures an image toward the finger placement unit 103, and the image sensor captures a finger image including a blood vessel pattern formed by infrared light transmitted through the infrared transmission filter. The brightness of the image, that is, the brightness of the area (the area of the finger F) in the imaging range IA (see FIG. 3) of the image sensor is measured.

  An image including a blood vessel pattern imaged by the imaging means 104 is photoelectrically converted into an electric signal and is taken into a microcomputer.

  Here, an example of a blood vessel pattern to be imaged will be described with reference to FIG.

  For example, when the finger F is placed at the center of the imaging range IA of the image sensor, the contour of the finger F and the blood vessel pattern BV are obtained as an image captured by the imaging unit 104 as shown in the figure. Since the blood vessel pattern BV varies depending on the individual, the blood vessel pattern BV is registered in advance in the memory 106 constituted by a nonvolatile memory or the like.

  Returning to FIG. 1, as the auxiliary light source 108, for example, a light emitting diode can be used as in the infrared light source 102. As described above, when the finger image including the blood vessel pattern is captured by the imaging unit 104 and personal authentication is performed, the auxiliary light source 108 is placed on the finger F before the infrared light source 102 emits infrared light. It is used for detecting whether or not it is placed on the part 103, and infrared light is irradiated toward the finger F placed on the finger placing part 103.

  The power supply circuit 107 is supplied with power from an external power supply VB.

  The personal authentication device 100 configured as described above is connected to the engine starting device 200 via a LAN, and the operation of starting the automobile engine by the personal authentication device 100 is performed by a program stored in the microcomputer 101 shown in FIG. Be controlled. Hereinafter, the operation of the microcomputer 101 will be described with reference to the flowchart of FIG.

  When the program stored in the microcomputer 101 is started, first, the process proceeds to step S10, and the microcomputer 101 performs initialization processing of the personal authentication device 100.

  Next, the process proceeds to step S20. In step S20, first, in step S22, the microcomputer 101 determines whether the finger F is placed within a predetermined range (finger placement unit 103). Next, in step S24, the light amount control of the infrared light source 102 is performed. .

  Here, the detection method and the light amount control of the finger F in step S20 will be specifically described with reference to FIG.

  In this step S20, first, the auxiliary light source 108 is turned on in step S22a, and then in step S22b, the light intensity FTBron (the auxiliary light source referred to in the claims) in the area of the finger F (the imaging area IA of the image sensor). The imaging means 104 measures the light intensity when the is turned on.

  Next, in step S22c, the auxiliary light source 108 is turned off, and in step S22d, the light intensity FTBRoff (light when the auxiliary light source in the claims is turned off) in the area of the finger F (image sensor imaging area IA) is turned off. Intensity) is measured by the imaging means 104.

  In step S22e, the microcomputer 101 compares the light intensity FTBRon when the auxiliary light source 108 is turned on with the light intensity FTBRoff when the auxiliary light source 108 is turned off.

  Here, when the finger placement unit 103 has the finger F, when the auxiliary light source 108 is turned on, the light from the auxiliary light source 108 is reflected, so that FTBRon becomes larger than FTBRoff. On the contrary, when the finger placement unit 103 does not have the finger F, the light is not reflected even if the auxiliary light source 108 is turned on, so that FTBRon and FTBRoff are substantially equal. From the above, in the comparison between FTBRon and FTBRoff, determination is made by adding a predetermined value a as an offset to FTBRoff, and if FTBRon is larger than FTBRoff + a, it is determined that the finger F is present, and the process proceeds to step S24a. On the other hand, if FTBRon is smaller than FTBRoff + a, it is determined that there is no finger F, and the process proceeds to step S24c.

  When it is determined in step S22 that the finger F is present and the process proceeds to step S24a, after the infrared light source 102 is turned on in this step S24a, the image capturing unit 104 captures an image, and in step S24b, the infrared light is captured. The light amount output LP of the light source 102 is controlled. The light amount output control of the infrared light source 102 is performed by, for example, a control model shown in FIG.

This control model is executed by a program in the microcomputer 101. The difference between the target brightness TBR of the image and the brightness FBR of the finger area captured by the image sensor of the imaging means 104 is obtained by the subtractor SUB, and the value obtained by multiplying by the coefficient K1 (> 0) is 1 by the integral element I. Integrate every image capture. However, the maximum value and the minimum value are limited by a limiter so as not to overflow in the integral element I. The value is set as the light amount output value LP ^{+ 1} of the infrared light source 102 when the next image is acquired. That is, negative feedback is performed using the brightness FBR of the region of the finger F of the actually acquired image. That is, when the brightness FBR of the region of the finger F is smaller than the target brightness TBR, the light amount output LP is increased, and when the brightness FBR of the region of the finger F is larger than the target brightness TBR, the light amount output LP is decreased. This is a feedback loop. Thereby, the light amount output from the infrared light source 102 is controlled so that the light amount is controlled according to the amount of infrared light emitted from the belly of the finger F when the finger F is placed on the finger placement unit 103. Become.

  Here, when the finger F is not placed on the finger placement unit 103, the re-radiated light (reflected light) disappears and a background image is acquired. If the detection of the presence or absence of the finger F is not performed and the light source control is performed by turning on the infrared light source 102 even when the finger F is not placed on the finger placement unit 103, the feedback loop includes an infrared ray. Regardless of the light output of the light source 102, the brightness of the background image is always input. When the background is darker than the target value, a positive numerical value is always input to the integral element I and sticks to the limiter's max value. Therefore, when the infrared light source 102 is turned on without detecting the presence or absence of the finger F, when the finger F is not present, the infrared light source 102 emits light at the maximum output. That is, unnecessary current consumption increases, or heat generation and deterioration of the infrared light source 102 are caused.

  Therefore, in the present invention, the finger F is detected in step S22, and if there is no finger F, the process proceeds to step S24c to prevent the infrared light source 102 from emitting light, thereby preventing an unnecessary increase in current consumption.

  Returning to FIG. 4, after the finger detection / light quantity control process in step S20 as described above is performed, personal authentication is performed in steps S30 to S50.

  Specifically, first, in step S30, the microcomputer 101 determines whether authentication should be started. This determination is performed by using whether or not the finger F is placed on the finger placement unit 103 in step S24e, or by providing a switch on the finger placement unit 103 on which the finger F is placed and turning on the switch. . If it is determined that the authentication is not started, the process returns to step S20. If it is determined that the authentication is started, the process proceeds to step S40.

  In step S40, the microcomputer 101 performs an authentication process using a finger image including a blood vessel pattern.

  Specifically, this step S40 includes steps from step S41 to step S46. First, in step S41, the finger F is detected by the image sensor of the imaging means 104 to which the authentication start signal is input from the microcomputer 101. The intensity distribution of the light emitted from the photoelectric converter is photoelectrically converted and taken into the microcomputer 101.

  Next, in step S42, the infrared light source 102 is turned off.

  Next, in step S43, the microcomputer 101 performs an arithmetic process on the acquired intensity distribution to detect a characteristic parameter of the blood vessel pattern. Note that the processing method in this step can be realized by performing filter processing combining integration processing and differentiation processing as disclosed in Patent Document 3 (Japanese Patent Laid-Open No. 2001-184507).

  Next, in step S44, the extracted feature parameter is collated with one or a plurality of parameters stored in the memory 106 in advance. Here, the blood vessel pattern of the finger F obtained in step S43 is compared with the registered blood vessel pattern called from the memory 106, and the degree of difference between the two is calculated.

  Next, in step S45, the collation result is determined from the degree of difference calculated in step S44. If there is a result with a small degree of difference, it is determined that the person is a registered person, the driver is authenticated as a regular driver, and the process proceeds to step S50. On the other hand, if the difference is large, the process proceeds to step S46 as an unregistered person or a verification failure.

  In step S46, it is determined whether all the registered data stored in the memory 106 have been collated. If all the data has been collated, it is determined that there is no registered data, and the process returns to step S20. On the other hand, if there is registration data that has not been collated, the process returns to step S44 and the collation is repeated.

  If the driver is authenticated as a regular driver in step S45 and the process proceeds to step S50, an engine start permission command is issued to the engine starter 200 via the LAN, and the engine is started.

  According to the personal authentication device 100 of this example as described above, before the personal authentication is performed by turning on the infrared light source 102, the auxiliary light source 108 is turned on and off, and whether or not the condition of FTBron> FTBRoff + a is satisfied. It is possible to reliably detect whether or not the finger F is placed on the finger placement unit 103. By detecting whether or not the finger F is present, the infrared light source 102 is not irradiated when the finger F is not placed, so that an increase in unnecessary current consumption can be suppressed.

  In the finger detection in step S22, as shown in FIG. 7, a phototransistor 110 is provided as a light receiving element in the vicinity of the image pickup means 104, and the auxiliary light source 108 is turned on by the phototransistor 110 instead of the image pickup means 104. The light intensity FTBRon and the light intensity FTBRoff when the auxiliary light source is turned off may be measured.

  Further, when the finger F is detected in the finger detection process in step S22 of FIG. 5, the finger F detection process may not be performed for a certain period. An example of this is shown in FIG. In this example, when the finger F is detected in the finger detection process in step S22 after the initialization process (not shown in FIG. 8) in step S10, the variable count is cleared to zero in step S23, and the light amount control process in step S24. To do.

  Then, after the image capture in step S24a in step S24 and the light amount control in step S24b, the process proceeds to step S30. In step S30, if it is determined that the authentication is started, the process proceeds to the authentication process in step S40. If it is determined that the authentication is not started, the process proceeds to step S60.

  When the process proceeds to step S40, the processes from step S41 to step S46 are performed (only step S45 is shown in FIG. 8). And when it determines with having collated all the data in step S46, it transfers to step S60.

  In step S60, 1 is added to count, and if count <α in the next step S62, the finger detection process in step S22 is not performed, the process returns to step S24 and the light amount control is performed again, and count = α, that is, If the light amount control in step S24 is looped α times, the process proceeds to the finger detection process in step S22.

  On the other hand, if it is determined that there is no finger in the finger detection process in step S22, the infrared light source 102 is kept turned off in step S24c, and the process returns to step S22 without proceeding to the authentication start in step S30. Perform finger detection processing.

  Further, as a modification of this example, the auxiliary light source 108 may not be provided as shown in FIG. In this case, in the finger detection process in step S22, as shown in FIG. 10, in step S22a and step S22c, a part or all of the infrared light source 102 is turned on instead of turning on the auxiliary light source. F is detected.

  Next, a second example of the embodiment of the personal authentication device according to the present invention will be described with reference to FIGS.

  The personal authentication device 100 in this example has the same configuration as that in FIG. 1 or FIG. 7, and the description of each configuration is omitted. In the following description, the configuration shown in FIG. 1 is used.

  In the personal authentication device 100 of this example, first, in step S220 of FIG. 11, the finger F is placed on the finger placement unit 103 by the imaging unit 104 in the initialization process immediately after the personal authentication device 100 is powered on. Measure the intensity BGBR of the background light when it is not. Then, BGBR and BGBRth are compared in microcomputer 101 using predetermined value BGBRth as a threshold value. When BGBR <BGBRth, the process proceeds to step S221. When BGBR ≧ BGBRth, the process proceeds to step S224.

  Details of step S221 are shown in FIG. In the figure, when the process proceeds from step S220 to step 221, the auxiliary light source 108 is turned on, the brightness FBRon of the finger F region is measured, and the presence / absence of the finger is detected.

  Specifically, first, the process proceeds to the state before one image in step S222: no finger. Here, first, the process proceeds to step S222a, and the auxiliary light source 108 is turned on. At this time, the light output LP of the infrared light source 102 is set to zero.

  Next, the process proceeds to step S222b, and the presence / absence of a finger is determined. Specifically, the brightness FTBRon of the finger F region is measured by the imaging unit 104, and when the microcomputer 101 determines that FTBRon> BGBRth + b (b is a predetermined value), the finger placement unit 103 has the finger F In step S223, one image before: transition to the finger presence state. If not, the process returns to step S222a.

  When the process proceeds to step S223, in step S223, first, the process proceeds to step S223a, the auxiliary light source 108 is turned off, and the variable count is cleared to zero. Next, the process proceeds to step S223b, the infrared light source 102 is turned on, and the light amount output LP of the infrared light source 102 is controlled. The light output LP is controlled by the control model shown in FIG.

Next, the process proceeds to step S223c, and it is determined whether there is no finger F in the finger placement unit 103. Here, although the light output LP of the infrared light source 102 is increased from the previous time, the brightness FTBR of the image in the finger F region (measured by the imaging unit 104) becomes darker (LP> LP ⁻¹ & FTBR < FTBR ^-1 ) or the light intensity output LP of the infrared light source 102 is the maximum value, but the brightness FTBR of the image of the finger F is dark (LP = maximum output & FTBR <BGBR + d (d is a predetermined value)) and the microcomputer 101 Is determined, it is determined that there is no possibility of the finger F. When the condition is satisfied, the process proceeds to step S223d, and 1 is added to count. Here, if the condition is satisfied α times continuously (count ≧ α), it is determined that the finger F is not present, and the process proceeds to step S222 (step S222a).

  On the other hand, if count <α in step S223d, it is determined that the finger F may still be present, and the process proceeds to step S223b. If it is determined in step S223c that the condition is not satisfied and the finger F is present, the process proceeds to step S223e, the count is cleared to zero, and the process proceeds to step S223b. Thereby, even if the finger F is present and step S223c is satisfied in the process of controlling the light output of the infrared light source 102, it is possible to prevent erroneous determination that there is no finger.

  On the other hand, the case where the process proceeds from step S220 to step S224 (when BGBR ≧ BGBRth) will be described with reference to FIG.

  When the process proceeds to step S224, the brightness FTBRoff of the finger F region is measured with the auxiliary light source 108 turned off, and the presence / absence of the finger is detected.

  Specifically, when the process proceeds from step S220 to step S224, first, the process proceeds to the state before one image of step S225: a fingerless state. Here, first, the process proceeds to step S225a, and the light amount output LP of the infrared light source 102 is set to zero. At this time, the auxiliary light source 108 remains off.

  Next, the process proceeds to step S225b, and the presence / absence of a finger is determined. Specifically, the brightness FTBRoff of the region of the finger F is measured by the imaging unit 104, and when the microcomputer 101 determines that FTBRoff <BGBRth-c (c is a predetermined value), the finger placement unit 103 is instructed. It is determined that there is F, and the process proceeds to the state with one finger before one image in step S226. When the condition is not satisfied, the process returns to step S225a.

  When it is determined in step S225 that the finger F is present and the process proceeds to step S226, first, the process proceeds to step S226a and the variable count is cleared to zero. Next, the process proceeds to step S226b, and the infrared light source 102 is turned on to perform light amount control. This light quantity control is performed by the control model shown in FIG.

  Next, the process proceeds to step S226c, and 1 is added to count. Here, if count <β (predetermined value), the process returns to step S226b, and the light amount control of the infrared light source 102 is performed. On the other hand, when the light amount is controlled β times and count = β (predetermined value) is satisfied, the process proceeds to step S226d to determine the possibility that the finger placement unit 103 does not have the finger F. Here, the brightness FTBRoff of the image in the finger F region is measured by temporarily setting the output of the infrared light source 102 to zero. If it is bright, that is, if the microcomputer 101 determines that FTBRoff> BGBRth + e (e is a predetermined value), it is determined that there is no finger F, and the process proceeds to step S225a. On the other hand, if it is dark, that is, if the microcomputer 101 determines that FTBRoff> BGBRth + e (e is a predetermined value) is not satisfied, it is determined that the finger F is present, the process proceeds to step S226a, count is cleared to zero, and step S226b is performed. Return to and perform light quantity control.

  In steps S223 and S226 where it is determined that there is a finger, when the microcomputer 101 determines that authentication is started, the process directly proceeds to authentication processing in step S40.

  According to the personal authentication apparatus 100 of the second example of such an embodiment, it has the same effect as the first example of the embodiment, and reliably detects the presence / absence of a finger regardless of the contrast of the background. Can do. Therefore, even when the personal authentication device 100 of this example is used in a place where the brightness is different, it is possible to reliably detect the presence or absence of a finger.

  In this example, when the personal authentication device is provided with the phototransistor 110 as shown in FIG. 7, the background light intensity BGBR when the finger F is not placed on the finger placement unit 103 is used. The measurement of the light intensity FTBRon of the finger F region when the auxiliary light source 108 is turned on and the brightness FTBR of the finger F region measured in the determination of the possibility that the finger placement unit 103 does not have the finger F As in the first example of FIG.

  Next, a third example of the embodiment of the personal authentication device according to the present invention will be described with reference to FIGS. Only parts different from the first example of the above embodiment will be described.

  As shown in FIG. 14, the personal authentication device 100 of this example is obtained by adding a switch to the personal authentication device shown in FIG. This switch 120 is provided so as to cover the finger placement unit 103 so that when the finger F is placed on the finger placement unit 103 and the switch 120 is pressed, a signal from the switch 120 is input to the microcomputer 101. It has become.

  In such a personal authentication device 100 of this example, as shown in FIG. 15, the finger detection process of step S22 includes only the process of step S22f, and depending on whether or not the switch 120 is pressed in this step S22f, It is determined whether or not the finger placement unit 103 has the finger F.

  If it is determined in step S22f that the finger placement unit 103 does not have the finger F, the process of step S22f is repeated. On the other hand, if it is determined that the finger placement unit 103 has the finger F, the process proceeds to step S24, and after the infrared light source 102 is turned on, an image is captured in step S24a. Then, in step S24b, the light amount of the infrared light source 102 is controlled, and the process proceeds to step S24f.

  In step S24f, it is determined whether step S24a and step S24b are looped n times, or whether the light output LP of the infrared light source 102 is stable. If the determination result is OK, the process directly proceeds to the authentication process in step S40. (The process of step S30 (see FIG. 4) is not performed).

  The personal authentication device 100 of this example as described above has the same effect as the personal authentication device 100 of the first example of the above embodiment, and performs the authentication process after the light output LP of the infrared light source 102 is stabilized. It can be carried out.

The figure which shows an example of a structure of the personal authentication apparatus in the 1st example of embodiment of this invention, and a 2nd example. The figure which shows an example of the drive circuit of an infrared light source. The figure which shows the imaging example of a finger | toe and a blood vessel pattern. The figure which shows an example of the program operation | movement flowchart of the microcomputer in the 1st example of embodiment of this invention. The figure which shows an example of the flowchart of finger detection and light quantity control in the 1st example of embodiment of this invention. The control block diagram of the light quantity output of an infrared light source. The figure which shows the other structural example of the personal authentication apparatus in the 1st example of an embodiment of this invention, and a 2nd example. The figure which shows the other example of the flowchart of the finger detection in the 1st example of embodiment of this invention. The figure which shows the other structural example of the personal authentication apparatus in the 1st example of embodiment of this invention. The figure which shows an example of the flowchart of finger detection in the personal authentication apparatus shown in FIG. The figure which shows an example of the flowchart of the finger detection in the 2nd example of embodiment of this invention. The figure which shows an example of the flowchart of the finger detection in the 2nd example of embodiment of this invention. The figure which shows an example of the flowchart of the finger detection in the 2nd example of embodiment of this invention. The figure which shows an example of a structure of the personal authentication apparatus in the 3rd example of embodiment of this invention. The figure which shows an example of the flowchart of the finger detection in the personal authentication apparatus shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Personal authentication apparatus 101 Microcomputer 102 Infrared light source 103 Finger placing part 104 Imaging means 105 Drive circuit 105a-105c Resistance 105d Nch-MOS transistor 106 Memory 107 Power supply circuit 108 Auxiliary light source 110 Phototransistor 120 Switch 200 Engine starter

Claims (1)

An infrared light source and an imaging means, and the living body is irradiated with infrared light from the infrared light source, and the infrared light reflected after being incident on the living body and re-radiated from the living body surface is imaged by the imaging means. In a personal authentication device for identifying an individual by collating the acquired blood vessel pattern of a finger with a previously registered finger blood vessel pattern ,
Providing an auxiliary light source for irradiating the living body with infrared light toward the imaging direction side of the imaging means;
The light intensity when there is no living body is measured in advance with the light-receiving element provided separately from the imaging means or the imaging means,
If the value of the light intensity when there is no biological body that has been measured in advance is smaller than a predetermined threshold, after turning on the auxiliary light source, measure the light intensity by the imaging means or the light receiving element, It is determined that there is a living body when the value of the light intensity when the auxiliary light source is turned on is larger than a value obtained by adding a predetermined value to the threshold value, and the light intensity when there is no living body measured in advance Is equal to or greater than the predetermined threshold value, the light intensity is measured by the imaging means or the light receiving element while the auxiliary light source is turned off, and the light intensity value when the auxiliary light source is turned off is the threshold value. A personal authentication device characterized by having a living body determination function that determines that there is a living body when smaller than a value obtained by subtracting a predetermined value from .

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