JP2001266134A - Fingerprint input device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fingerprint input device which can appropriately judge the authenticity of a finger used for input without needing any expensive light source. SOLUTION: A finger placed on an image sensor 3 is irradiated with a light emitting diode 4 and the finger is substantially emitted by scattering light in the finger. The swelling line part of a fingerprint where high luminance is detected by contact with the image sensor 3 and the trough line part of the fingerprint where low luminance is detected by a gap with the image sensor 3 are identified and the fingerprint is detected. Thus, the regular light emitting diode 4 can be used instead of a laser diode and the manufacture cost of a whole device is reduced. The light emitting intensity and the oscillation frequency of the light emitting diode 4 are time-sequentially changed, the change of the light emitting state of the light emitting diode 4 is detected from an obtained picture through the image sensor 3 and it is judged whether the real time input of the fingerprint is appropriately performed or not according to whether the fluctuation is correlated with the time sequential change of the light emitting state of the light source.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a fingerprint input device, and more particularly, to an improvement in the cost of a hardware structure required for determining whether or not a finger used for input is a living body. And improvements to achieve enhanced security against forgery input of electronic and physical fingerprints.

[0002]

2. Description of the Related Art As means for determining whether a finger used for input of a fingerprint input device is a living body or a counterfeit product, the finger is transmitted and irradiated with laser light from a laser diode. A device that makes a determination based on whether or not noise of speckle light is included in output light has been proposed, for example, in Japanese Patent Application No. 63-154962.

Further, the fingertip is pressed against the glass of the input surface to optically identify the ridges (convex portions) and the valley lines (concave portions) of the fingerprint and read an image. There is also known a device that determines whether a finger is a living body or a counterfeit by detecting a temporal change of a sensor output caused by a change of the finger.

[0004]

[Problems to be solved by the invention]
No. 154962 has a drawback that the overall device manufacturing cost is relatively high because the light source for illuminating the finger is limited to an expensive laser diode for irradiating coherent light because of the need to use speckle light.

[0005] Further, in the case of using a change in the degree of adhesion of the fingertip to judge the authenticity of the finger, a malfunction is supposed when a forged product made of an elastic material whose degree of adhesion changes due to the pressing force is used. In addition, since the change in sensor output caused by the change in the degree of adhesion due to sweating is exponential (lawful), there is a concern about electronic counterfeiting of sensor signals using an unjust device.

[0006]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to eliminate the drawbacks of the prior art, eliminate the need for a particularly expensive light source, and accurately determine the authenticity of a finger used for input. It is to provide a device. Further, it is also possible to provide a fingerprint input device that can secure necessary and sufficient security even when it is difficult to forge a sensor signal and the sensor signal is reproduced and input by stealing the sensor signal. Is part of its purpose.

[0007]

According to the present invention, there is provided an image sensor on which a finger to be inspected is placed, and a finger placed on the image sensor is irradiated with the finger to diffuse light therein, thereby forming a finger. A light source that emits light substantially, an image acquisition unit that activates an image sensor at predetermined intervals to acquire an image of a finger, and determines the presence or absence of blood flow based on a time-series change in the image acquired by the image acquisition unit. The above object is achieved by a configuration characterized by comprising a living body determination unit that performs the determination.

[0008] As described above, the finger is illuminated by diffusing the light inside, and the ridge portion of the fingerprint which is in close contact with the image sensor (the convex portion of the fingerprint where relatively high luminance is detected by contact with the image sensor). ) And a valley portion (a fingerprint recess in which relatively low luminance is detected due to the effect of a gap generated between the image sensor).
Unlike conventional fingerprint input devices that use speckle light, there is no need to consider the wavelength of the light source. Therefore, a normal light emitting diode can be used, which is advantageous in reducing the manufacturing cost of the device. In addition, by determining the presence or absence of blood flow by evaluating the chronological change of the image acquired by the image acquisition unit at predetermined intervals by the living body determination unit, it is determined whether the finger to be examined is a living body. Since identification is performed, it is possible to prevent a mistake in authenticity determination of a forged finger with a high probability.

Further, in addition to the above configuration, a light emission control unit for outputting a light emission control signal for changing the light emission state of the light source in time series, and detecting a change in the light emission state of the light source from the image acquired by the image acquisition unit. Along with a real-time input determining means for determining whether the fluctuation is correlated with a time-series change in the light emitting state of the light source, the living body determining means, from the image obtained by the image obtaining means. It is also possible to adopt a configuration in which a function for removing an influence caused by a change in the light emitting state of the light source is added.

[0010] According to this configuration, the light emission state of the light source that irradiates the finger changes in a time series, and at the same time, the change in the light emission state of the light source is reflected in the data of the image acquired at predetermined intervals by the image acquisition means. Is done. Then, the real-time input determination unit detects a change in the light emitting state of the light source from the image acquired by the image acquiring unit, and determines whether the change is correlated with a time-series change in the light emitting state of the light source. judge. This makes it possible to determine whether or not the fingerprint image input to the fingerprint input device is an image input in real time (real time). It will be possible to prevent with a very high probability. Also, on the side of the living body determination unit, a function of removing an effect caused by a change in the light emission state of the light source from the image acquired by the image acquisition unit is added, so that regardless of the change in the light emission state of the light source, In addition, it is possible to accurately evaluate an image acquired every predetermined period to determine the presence or absence of blood flow, and identify whether or not a finger to be inspected is a living body.

By changing the light emission intensity of the light source with the light emission control signal, the light emission state of the light source can be changed in time series.

In this case, the real-time input determining means detects a change in the light emission intensity of the light source from the image acquired by the image acquisition unit, and the change correlates with a time-series change in the light emission intensity of the light source. Will be determined. Then, the living body determination unit evaluates the images acquired at predetermined intervals by removing an effect caused by a change in the light emission intensity of the light source from the image acquired by the image acquisition unit, and determines whether there is a blood flow. .

Further, the light emission state of the light source can be changed in time series by changing the oscillation frequency of the light source with the light emission control signal.

In this case, the real-time input determining means detects a change in the oscillation frequency of the light source from the image acquired by the image acquisition section, and the variation correlates with a time-series change in the oscillation frequency of the light source. Will be determined. Further, the living body determination unit evaluates the images acquired at predetermined intervals by removing an effect caused by a change in the oscillation frequency of the light source from the image acquired by the image acquisition unit, and determines the presence or absence of blood flow. .

Further, the light emission state of the light source may be changed in time series by changing the light emission intensity and the oscillation frequency of the light source with the light emission control signal.

In this case, the real-time input determining means detects a change in the light emission intensity and the oscillation frequency of the light source from the image acquired by the image acquisition section, and the change indicates a change in the light emission intensity and the oscillation frequency of the light source in time series. It is determined whether or not there is a correlation with the change. In addition, the living body determination unit evaluates the image acquired at predetermined intervals by removing an effect caused by a change in the light emission intensity and the oscillation frequency of the light source from the image acquired by the image acquisition unit, and evaluates whether there is a blood flow. Is determined.

Further, the light emission control section may be provided with a signal generation function for randomly generating a light emission control signal.

When this configuration is applied, it is extremely difficult to externally predict how the light emitting state of the light source changes in a time-series manner. In this way, it is possible to sufficiently cope with fraud such as replay input. For example, even if the stolen sensor signal was reproduced and input again later when the fingerprint input device was properly used in the past, in most cases, the light emitting state of the light source recorded in the reproduced and input signal was often changed. Since the chronological change is different from the chronological change in the light emission state of the light source due to the newly generated light emission control signal at the time of this input operation, it is determined that the fingerprint input operation of this time is illegal in real time. It is accurately detected by the input determination means.

Preferably, the light emission control section is provided on a main device side connected to the fingerprint input device main body.

By providing the light emission control unit for generating the light emission control signal on the main device side, not on the fingerprint input device main body, it becomes difficult for a third party to steal the light emission control signal, and security against unauthorized operation is further increased. Will be strengthened.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 are functional block diagrams showing an embodiment in which the present invention is applied to a fingerprint input device used for restricting use of a workstation, a personal computer, and the like.
FIG. 1 mainly shows a portion of the fingerprint input device main body 1 connected to a workstation, a personal computer, or the like, and FIG. 2 shows a main part of a workstation, personal computer, or the like related to the functions of the fingerprint input device main body 1. The drawing includes a part of the configuration of the device 2.

As shown in FIG. 1, an image sensor 3 for placing a finger 15 to be inspected is provided on the upper surface of the housing of the fingerprint input device main body 1. In the vicinity, a light emitting diode 4 serving as a light source for irradiating a finger 15 placed on the image sensor 3 is provided. The image sensor 3 is a two-dimensional image sensor provided with a large number of light receiving elements 5 arranged two-dimensionally, and the surface in contact with the finger 15 is mechanically and electrically protected by a light-transmitting protective film 6. The buffer 7 is a part that captures an image from the image sensor 3 and functions as a part of an image acquisition unit.

The driver 8 receives a command from the outside, that is, in this case, receives a light emission control signal from the main device 2, and controls the light emission intensity of the light emitting diode 4, the oscillation frequency, and the like. It is. That is, in this embodiment, the light emission control unit for outputting the light emission control signal is provided not on the fingerprint input device main body 1 but on the main device 2 side.

As shown in FIG. 2, the fingerprint input device main body 1 is connected to the main device 2 via an interface 9, and the CPU 10 and the like of the main device 2 constitute a light emission control section of the fingerprint input device. Will be. Also, this CP
U10 also functions as a living body determination unit and a real-time input determination unit of the fingerprint input device. Each of the ROM 11, the RAM 12, the external storage device 13, and the manual data input device 14 is a component on the main device 2 side.
It is also storage means for storing a plurality of light emission control signals, and also serves as a part of signal generation function realizing means in the light emission control unit.

In this embodiment, both the light emission intensity and the oscillation frequency of the light emitting diode 4 are changed in time series by a light emission control signal, and the ROM 11 stores, for example, (P1, T1), (P2, T2), ..., (P
(i, Ti),..., (Pn, Tn). Here, Pi is a value indicating the light emission intensity, and Ti is a value corresponding to a time for keeping the light emission intensity Pi, that is, a reciprocal of the oscillation frequency.

The CPU 10 as a light emission control unit receives a start signal from the fingerprint input device main body 1 and randomly selects one light emission control signal from a plurality of light emission control signals.
The light emission control signals (P1, T1), (P2,
T2), ..., (Pi, Ti), ..., (Pn, T
n) is read out in the order of i = 1 to n, and Pi is sequentially read out.
The light emission intensity and oscillation frequency of the light emitting diode 4 are changed in time series by holding the light emission intensity of the light emitting diode for Ti seconds.

Here, the data strings (P1, T1), (P2, T2),... Constituting one light emission control signal are simplified.
.., (Pi, Ti),..., (Pn, Tn) are shown, but in reality, they have a data array similar to this, and the numerical value of each data item, that is, the emission intensity and A plurality of data strings having different light emission durations are stored in the ROM 11 for the number of light emission control signals.

It is desirable that the minimum value of the light emission intensity Pi is set at least to a level at which fingerprint identification processing by the image sensor 3 can be performed.
The value of i should be set to a value different from the frequency of blood pulsation in order to prevent erroneous recognition due to a change in brightness of an image due to blood pulsation.

Next, a fingerprint input process using the fingerprint input device body 1 will be described with reference to the flowcharts of FIGS.

The CPU 10 first sets the interface 9
Then, the output from the image sensor 3 is read via the buffer 7 (step s1), and whether or not the deviation between the value and the value detected in the previous processing cycle exceeds a predetermined value, that is, It is determined whether the finger 15 is placed and the output from the image sensor 3 fluctuates (step s2).

If the result of this determination is false, it means that the output from the image sensor 3 has not fluctuated, that is, the finger 15 is not placed.
After temporarily storing the output value read this time in the register as the comparison value to be used in the next cycle (step s3), the PU 10 shifts to the process of step s1 again. Unless the finger 15 is placed on the image sensor 3 and the output does not significantly fluctuate, the processes of steps s1 to s3 are repeatedly executed in the same manner as described above.

When it is confirmed in step s2 that the finger 15 has been placed on the image sensor 3 and the output has fluctuated, the CP as a signal generation function implementing means is determined.
U10 randomly generates a random number within a predetermined upper limit and lower limit using a random number function or the like, and selects a data string of a light emission control signal corresponding to the value from the ROM 11 (step s4). For example, if there are ten sets of light emission control signals, the above-described upper and lower limits are divided into ten equal parts, and one set of light emission control signals is associated with each of them, and the generated random number is It is possible to randomly select only one set of the data sequence of the light emission control signal depending on which divided range belongs.

Next, the CPU 10 as a light emission control unit
Initializes the value of the index i to 1, reads the leading data (Pi, Ti) corresponding to the index i = 1 from the data sequence of the light emission control signal of the ROM 11 selected in the process of step s4, and outputs the output intensity Pi Is output to the driver 8 to start lighting the light emitting diode 4 (step s5). Then, the CPU 10 resets and restarts the timer T1 for measuring the elapsed time after the start of light emission and the timer T2 for measuring the light emission time based on each data of the data string of the light emission control signal, and temporarily stores the timer T1. Is initialized (step s6).

Next, C which constitutes a part of the image acquisition means
The PU 10 reads the image of the image sensor 3 via the buffer 7 (step s7), obtains the average value P of the brightness of the image (step s8), and calculates this value P together with the elapsed time T1 after the start of light emission (P , T1) is additionally stored in the data file for temporary storage (step s9).

The CPU 10 as a living body determination means
Removes the change in the light emitting state of the light emitting diode 4 from the image read in the processing of step s7, that is, the effect caused by the intensity of the light emitting intensity, and identifies the ridges and valleys of the fingerprint from the relative contrast ratio. (Step s1)
0). As means for removing the effect caused by the intensity of the light emission intensity of the light emitting diode 4 from the read image, for example, an average brightness of the entire image is obtained, and the brightness (contrast) of each part of the fingerprint is determined with reference to the brightness of the background. Concentration). Since the finger 15 placed on the image sensor 3 emits light substantially by scattering light from the light emitting diode 4 therein, as shown in FIG. The ridge portion directly in contact with is photographed brightly, and the valley line portion formed with the image sensor 3 by the dent of the fingerprint is photographed relatively dark.

Next, the CPU 10 as a living body determination means
Compares the density of each part of the fingerprint thus obtained with the fingerprint stored in the previous cycle data storage register, that is, the density of each part of the fingerprint read in the processing of the previous cycle (step s11),
Whether there is blood flow, that is, the finger 1 on the image sensor 3
It is determined whether 5 is a real finger with blood or a fake (step s12). If there is a blood flow, the movement of red blood cells and hemoglobin changes the light and darkness of the light propagation path at each position inside the finger, so as described above, after removing the effect caused by the intensity of the light emission intensity from the image, By comparing the change in brightness of the minute part of each part of the image with the data of the corresponding part taken in the previous cycle,
It is possible to determine the presence or absence of blood flow, that is, whether or not the subject is a living body.

If the result of the determination in step s12 is false, that is, if the image density of each part of the fingerprint is the same as that in the previous cycle and no pulsation of blood is detected, the image sensor Since the finger 15 placed on the 3 is a counterfeit product, the CPU 10 as the living body determination means rejects the input operation by the finger 15 and returns to the process of step s1, and returns the appropriate finger. It returns to the initial standby state of waiting for mounting.

On the other hand, when the result of the determination in step s12 is true and at least this finger 15 is confirmed to be a living body finger, the CPU 10 removes the influence caused by the intensity of the light emission intensity. The image data detected this time is updated and stored in the previous cycle data storage register as comparison data used in the comparison processing of step s11 in the next cycle (step s13).

Next, the CPU 10 as a light emission control unit
Is the light emission time Ti determined by the light emission control signal (Pi, Ti) measured by the timer T2 for measuring the light emission time.
Is determined (step s14).

If the measurement time of the timer T2 has not reached the light emission time Ti, the CPU 1 as a light emission control unit
0 indicates that the current light emission intensity Pi is held and the process returns to step S7.
In the same manner as described above, the processes in steps s7 to s14 are repeatedly executed, and the relationship (P, T) between the average value P of the image brightness and the elapsed time T1 after the start of light emission is performed.
The data of 1) is additionally stored in the data file for temporary storage, and in parallel with this, the fingerprint detection processing and the biological detection processing are repeatedly executed.

When it is confirmed in the determination processing in step s14 that the measurement time of the timer T2 has reached the light emission time Ti during the execution of such processing repeatedly, the CPU 10 as the light emission control unit determines the value of the index i. Is incremented by one (step s15), and it is determined whether or not the current value of the index i exceeds the number n of the components of the data of the currently selected light emission control signal (step s16).

Here, the current value of the index i is the number of data n
If it does not exceed, it means that it is necessary to read the next data of the data string constituting the light emission control signal and keep the light emitting diode 4 lit. Therefore, in this case, the CPU 10 as the light emission control unit resets and restarts the value of the timer T2 to start measuring the light emission time based on the next data (step s17).
The next data (Pi, Ti) is read from the currently selected emission control signal in accordance with the value of the index i incremented in the process of step s15, and the magnitude of the output intensity Pi is switched based on this value Pi to emit light. The lighting of the diode 4 is started (step s18), and the process returns to step S7 to repeatedly execute the same process as described above.

By this processing operation, both the light emission intensity and the oscillation frequency of the light emitting diode 4 are time-sequentially (P1, T
1), (P2, T2), ..., (Pi, Ti), ...
, (Pn, Tn).
FIG. 5 shows an example of a time-series change of the light emitting state of the light emitting diode 4.
Is indicated by a thick solid line.

While the switching process is repeated, the current value of the index i finally exceeds the number n of data, and the last data (P
(n, Tn) that the light emission control is completed.
When detected in the discrimination processing of No. 16, the CPU 10 as the real time input determination means sets the light emission control signal (P1, T1) selected this time with the elapsed time T1 after the start of light emission as a time axis.
1), (P2, T2), ..., (Pi, Ti), ...
, (Pn, Tn), the change in the light emission intensity Pi of the light emitting diode 4 (the thick solid line diagram in FIG. 5), and the average brightness (P, T1) of the image stored in the temporary storage data file. ) (Thin solid line diagram in FIG. 5)
Is calculated (step s19), and whether the correlation is greater than a preset reference value, that is, the average value of the brightness of the image following the change in the light emission intensity of the light emitting diode 4 Is determined (step s20).

Here, the change in the average brightness P of the image caused by the pulsation of blood is sufficiently smaller than the change in the average brightness P of the image caused by the change in the light emission intensity Pi. , I = 1 to n, the value of the light emission time Ti is also set to a value different from the blood pulsation, so that the average value P of the brightness of the image slightly changes due to the blood pulsation. Also, whether or not the light input to the image sensor 3 appropriately responds to the change in the intensity of the light emission control signal, that is, the change in the light emission intensity of the light emitting diode 4 and the change in the average value of the image brightness Can be accurately determined whether or not there is a sufficient correlation.

If a sufficient correlation is found between the change in the light emission intensity of the light emitting diode 4 and the change in the average value of the brightness of the image, the CPU 10 as the real-time input determination means sets this time. It is determined that an appropriate fingerprint input operation has been performed under the control of the selected light emission control signal, and an appropriate signal indicating that an appropriate input operation has been performed is added to the fingerprint data in addition to the detected fingerprint data. The process is passed to the routine for combination processing (step s21), and all the processes related to one fingerprint input are completed, and the process again enters a standby state waiting for a fingerprint input operation. Since the process related to the fingerprint verification itself is already known, the description is omitted here.

If a sufficient correlation is not found in the discrimination processing in step s20, the CPU 10 as a real-time input judgment means uses an illegal data reproducing device to input a forged signal or the like. It is considered that the operation has been performed, and in addition to the data of the detected fingerprint, an improper signal indicating that the unauthorized operation has been performed is passed to the fingerprint collation processing routine (step s22). The process related to fingerprint input is completed, and the process enters a standby state again for waiting for a fingerprint input operation.

As described above, a plurality of light emission control signals having different light emission intensities and oscillation frequencies of the light emitting diode 4 are stored in the ROM 11, and the light emission control signal is randomly selected from the plurality of light emission control signals to change the light emitting state of the light emitting diode 4. Although an example of the processing in the case of changing the light emission in a series has been described, a plurality of light emission control signals in which only the light emission intensity of the light emitting diode 4 is changed without changing the oscillation frequency (the value of each Ti), or A plurality of light emission control signals having different oscillation frequencies (values of each Ti) without changing the light emission intensity are stored in the ROM 11.
May be stored, and a light emission control signal may be randomly selected from them.

Even when only one light emission control signal is stored in the ROM 11, the light emitting diode 4
If the light emission intensity and oscillation frequency (values of each Ti) are set in a complicated manner, it is possible to sufficiently cope with the input of a counterfeit signal using an unauthorized data reproducing device or the like.

In the above embodiment, the light emission control unit of the fingerprint input device is provided by the CPU 10 and the ROM 1 of the main device 2.
1 and furthermore, the real-time input determination means is configured by the CPU 10 of the main device 2 so as to realize strong security against input of a forged signal using an unauthorized data reproducing device or the like. However, technically, it is possible to provide a dedicated CPU on the side of the fingerprint input device main body 1 and use it as a real-time input determining means, or as a light emission control unit and a real-time input determining means.

[0051]

The fingerprint input device according to the present invention utilizes a light source that emits light substantially by emitting light by irradiating a finger placed on the image sensor and diffusing light inside the finger. A configuration in which a fingerprint ridge is detected by detecting a relatively high luminance and a valley of a fingerprint where a relatively low luminance is detected by a gap between the image sensor and the fingerprint is detected. Therefore, it is not necessary to particularly consider the wavelength of the light source. Therefore, it is not necessary to use a coherent light laser diode as in a conventional fingerprint input device using speckle light, and a normal light emitting diode can be used, thereby easily reducing the manufacturing cost of the entire device. can do. In addition, the image sensor is activated at predetermined intervals to acquire a fingerprint image, and the living body determination unit evaluates the chronological change of the image, and determines whether the subject's finger is a living body based on the presence or absence of blood flow. Therefore, it is possible to prevent a mistake in authenticity determination of a finger of a counterfeit product with a high probability.

Further, the light emission state of the light source, that is, the light emission intensity and the oscillation frequency are changed in a time series according to the light emission control signal from the light emission control unit, and the light emission state of the light source is also determined from the image acquired by the image acquisition unit. A time-series change is detected, and whether the change is correlated with the time-series change in the light emitting state of the light source is used to determine whether a real-time fingerprint input is performed using a valid fingerprint input device. Is determined, it is possible to prevent with a very high probability a mistake in authenticity determination for electronic forgery of the sensor signal.

In addition, the light-emitting intensity of the light source and the chronological change of the oscillation frequency are randomly generated each time by the signal generating function of the fingerprint input device. It is extremely difficult to electronically falsify input data by knowing in advance the chronological changes in the emission intensity and oscillation frequency of the input data. Further, even when a sensor signal generated by a legitimate method is plagiarized and reproduced and input later, this can be accurately detected as an illegal input operation.

Since the light emission control unit is not provided in the fingerprint input device main body but is provided on the side of the main device connected to the fingerprint input device main body, the light emission control signal itself can be stolen by a third party. Is extremely difficult, and security against unauthorized operations is further enhanced.

[Brief description of the drawings]

FIG. 1 is a functional block diagram illustrating a fingerprint input device main body.

FIG. 2 is a functional block diagram showing a part of the configuration of a main device in relation to functions of the fingerprint input device.

FIG. 3 is a flowchart showing an outline of a fingerprint input process using the fingerprint input device main body.

FIG. 4 is a continuation of the flowchart showing an outline of the fingerprint input process.

FIG. 5 is a conceptual diagram showing an example of a time-series change of a light-emitting state Pi of a light-emitting diode and an example of a change of an average value P of brightness of an image corresponding thereto.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Fingerprint input device main body 2 Main device 3 Image sensor 4 Light emitting diode (light source) 5 Light receiving element 6 Light transmissive protective film 7 Buffer (part of image acquisition means) 8 Driver 9 Interface 10 CPU (light emission control part, living body judgment means) , Real time input determination means, signal generation function realization means) 11 ROM 12 RAM 13 external storage device 14 manual data input device (CRT / MDI) 15 finger

Claims (7)

[Claims] 1. An image sensor on which a finger to be inspected is placed, and a light source which irradiates the finger placed on the image sensor and diffuses light therein to thereby substantially emit the finger. An image acquisition unit that activates the image sensor at predetermined intervals to acquire an image of the finger, and a living body determination unit that determines the presence or absence of blood flow based on a time-series change in the image acquired by the image acquisition unit. A fingerprint input device comprising: 2. An image sensor on which a finger to be inspected is placed, and a light source which irradiates the finger placed on the image sensor and diffuses light therein to thereby substantially emit the finger. A light emission control unit that outputs a light emission control signal that changes the light emission state of the light source in time series, an image acquisition unit that activates the image sensor at predetermined intervals to acquire an image of the finger, and the image acquisition A real-time input determination unit that detects a change in the light emitting state of the light source from the image obtained by the unit and determines whether the change is correlated with a time-series change in the light emitting state of the light source; A biological determination unit that determines the presence or absence of blood flow based on a time-series change of an image obtained by removing an influence caused by a change in the light emitting state of the light source from the image acquired by the image acquisition unit. Fingerprint input device. 3. The fingerprint input device according to claim 2, wherein the light emission control signal is a signal that changes the light emission intensity of the light source in a time-series manner. 4. The fingerprint input device according to claim 2, wherein the light emission control signal is constituted by a signal that changes the oscillation frequency of the light source in a time series. 5. The fingerprint input device according to claim 2, wherein the light emission control signal is constituted by a signal that changes a light emission intensity and an oscillation frequency of the light source in a time-series manner. 6. The light emission control section is provided with a signal generation function for randomly generating the light emission control signal. 6. The fingerprint input device according to claim 5. 7. The device according to claim 2, wherein the light emission control unit is provided on a main device connected to the fingerprint input device main body.
The fingerprint input device according to any one of claims 1 to 4.