JP4402605B2 - Fingerprint image pickup device - Google Patents

Description

  The present invention relates to a fingerprint image pickup apparatus that takes a fingerprint by taking it loosely so that a finger placement unit does not touch the finger.

For example, the fingerprint image fluctuates due to dirt on the skin surface due to sweat or finger oil, and the fingerprint image changes. In order to reduce the influence of this change, the conventional fingerprint image pickup device does not place the finger on the plate glass or the prism, but forms an opening in the finger rest, and exposes the fingerprint portion of the finger to this opening. Thus, a fingerprint is taken in a non-contact state (see, for example, Patent Document 1).
FIG. 6 shows a conventional fingerprint image capturing apparatus having the same configuration as that described in Patent Document 1. That is, the upper surface 32 and the lower surface 33 of the finger placement part 31 are cut out to form an upper opening 32a and a lower opening 33a, respectively. The part to be imaged of the fingerprint of the finger 36 loosely inserted in the finger placement unit 31 is exposed through the lower opening 33a. In addition, a light source 41 is attached above the upper opening 32a, and irradiates the anti-fingerprint side of the finger 36 with a parallel ray refracted by the lens 42, and transmitted light 41a transmitted through the finger 36 is transmitted from the lower opening 33a to the finger. It passes below the placement unit 31. The transmitted light 41a is collected by the lens 43 and draws the fingerprint of the finger 36 on the CCD 44, which is an imaging means. The CCD 44 takes a picture of the fingerprint of the drawn finger 36.

Here, microswitches 37 are respectively attached to the front side and the back side across the lower opening 33a. When the finger 36 is loosely inserted into the finger placement unit 31 and both the microswitches 37 are pressed and actuated by the finger 36, the fingerprint is copied.
That is, when the finger 36 is loosely inserted into the finger placement unit 31 and both the micro switches 37 are operated, the finger placement detection means 51 detects the operation of the micro switch 37. By this detection, the light source lighting means 52 is activated to light the light source 41. The light source 41 irradiates the finger 36, and the transmitted light 41 a draws a fingerprint on the CCD 44 that is the imaging means 53. The imaging unit 53 takes a picture of the fingerprint of the finger 36. When the imaging of the fingerprint is completed, the finger 36 is released from the finger placement unit 31. As a result, both microswitches 37 are restored, the light source extinguishing means 55 is activated, the light source 41 is extinguished, and the fingerprint imaging is completed.

  Similarly, in the non-contact type fingerprint identification device disclosed in Patent Document 2, the fingerprint recognition rate is lowered due to contamination of the glass surface by finger grease or dust caused by placing a finger on the glass surface. It is something to avoid. That is, the finger is placed and fixed so as to be supported by the edge of the opening. The fingerprint portion of the finger is exposed in the opening. The fingerprint portion is irradiated with light from an LED lamp, and the reflected light is received by a CCD to image a fingerprint.

Japanese Patent Laying-Open No. 2003-85538 (paragraph numbers 12 to 14, FIG. 1) JP 2001-167255 A (paragraph numbers 27 and 28, FIG. 1)

The conventional fingerprint image imaging device is configured as described above, and the finger 36 is in direct contact with the finger placement unit 31 except for some imaging target portions. For this reason, it is assumed that other people's finger grease, dust attached to the finger, etc. remain in the finger placement part 31 and transfer to self. There has been a problem that it is not preferable from the viewpoint of sanitation and hygiene that such other people's finger oils and the like are transferred to self.
The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a fingerprint image imaging device that takes a fingerprint by loosely inserting it so that the finger placement unit does not touch the finger.

  A fingerprint image imaging apparatus according to the present invention is a fingerprint image imaging apparatus for taking a picture of a fingerprint by loosely inserting a finger into a finger placement unit, and for positioning from the anti-fingerprint side of the finger toward the finger placement unit. When it is detected that the reflected light is reflected from the nail, the position of the nail in the optical axis direction is detected from the reflected light, and the finger touches the inside of the finger rest. When it is detected that the position is within a predetermined range that is set in advance as a range not to be used, a fingerprint of the finger is copied.

  As described above, the fingerprint image capturing apparatus according to the present invention takes a picture of a fingerprint by placing a finger loosely inserted into the finger placement unit within a predetermined range that is not set in contact with the finger placement unit. It is what I did. In order to specify the predetermined range, the optical axis of the finger is detected by irradiating the positioning light from the anti-fingerprint side of the finger toward the finger rest and detecting that the reflected light is from the nail. The direction, that is, the vertical position of the finger placement portion can be restricted, and the depth direction and the horizontal position of the finger orthogonal to the optical axis can also be restricted by the dimension range of the nail. That is, by detecting the reflected light from the fingernail, it is possible to specify the position of the finger in the three-dimensional space of the finger placement unit, so that the fingerprint can be taken without touching the finger placement unit. There is an effect of being able to.

Embodiments of the present invention will be described below with reference to the drawings. In addition, in each figure, the same code | symbol is attached | subjected to the part which is the same or it corresponds, and duplication of description was omitted.
Embodiment 1 FIG.
1 to 5 show a first embodiment of the present invention.
FIG. 1 is a block diagram showing a configuration of a fingerprint image capturing apparatus according to Embodiment 1 of the present invention.
The finger placement portion 1 has a cylindrical shape, and the upper surface 2 and the lower surface 3 are cut out to form an upper opening 2a and a lower opening 3a, respectively. The front surface 4 and the left and right side surfaces 5 are closed. It is assumed that the finger placement portion 1 has a margin for movement in the left-right direction of the finger 6 by at least the dimension corresponding to the width of the nail 6c of the finger 6.

The part to be imaged of the fingerprint 6a of the finger 6 loosely inserted in the finger placement unit 1 is scheduled to be positioned above the lower opening 3a. Further, a light source 11 is attached above the upper opening 2a, and the outer skin 6b portion of the finger 6 on the side opposite to the fingerprint is irradiated with parallel light refracted by the lens 12. The transmitted light 11a that has passed through the finger 6 passes through the lower opening 3a to the lower side of the finger placement unit 1. Further, the fingerprint 6 a of the finger 6 is drawn on the CCD 14 which is condensed by the lens 13 and is a component of the fingerprint image capturing means 26. The CCD 14 takes a picture of the fingerprint 6a of the drawn finger 6.
A positioning light projector 15 is provided on the opposite side of the finger 6 to irradiate the finger placement unit 1 with light. The reflected light of the light emitted from the positioning light projector 15 is received by the positioning light receiver 16 installed adjacent thereto.
In addition, a predetermined range is set in advance as a range in which the finger 6 does not touch the inside of the finger placement unit 1. In order to guide the finger 6 to be positioned within this predetermined range, a display 17 is attached to the front surface of the case 18.

  Next, the operation will be described. The positioning projector 15 is always lit by the projector lighting means 21. For this reason, the positioning light receiver 16 always receives the reflected light from the lower surface 3. Since the lower surface 3 is jet black, the reflected light is extremely weak. For this reason, it can be determined whether or not the light is reflected from the claw 6c. The reflected light detection means 22 receives the light from the positioning light receiver 16 and detects a reflected portion from the reflected light. As a result, when the light is reflected from the lower surface 3, the “front” of the display device 17 is turned on to guide the finger 6 to advance. Even when the reflected light is from the outer skin 6b, it is possible to identify the reflection from the outer skin 6b from the difference between the claws 6c and the reflectance. Therefore, when the light is reflected from the outer skin 6b, “back” lights up to guide the finger 6 to retreat. When the light is reflected by the claw 6c, “front” and “rear” are turned off and the front-rear position D is set. Furthermore, when the vertical position L of the finger 6 is also in a preset range, that is, when the finger 6 is positioned within a predetermined range, “OK” is lit.

  When the reflected light from the nail 6c is detected by the reflected light detecting means 22, the nail position calculating means 23 calculates the position of the nail 6c in the optical axis direction, that is, the vertical position L in the finger placement portion 1. The calculation result by the claw position calculation means 23 is input to the claw position deviation calculation means 24 to check whether it is within a predetermined range. As a result, when the finger 6 is out of the predetermined range and is higher, the “lower” of the display unit 17 is lit to guide the finger 6 to be lowered. Conversely, in the case of the lower rank, “upper” is lit and the finger 6 is guided to be raised. When both the vertical position L and the front / rear position D are within a predetermined range, “OK” is turned on and the light source lighting means 25 is activated to turn on the light source 11. By this lighting, the image of the fingerprint 6a of the finger 6 is displayed on the CCD 14 by the transmitted light 11a. The image of the fingerprint 6a is captured and recorded in the fingerprint image imaging means 26. Once recorded, the light source extinguishing means 27 is activated to turn off the light source 11 and the fingerprint image capturing is completed.

  FIG. 2 is an explanatory diagram showing the operating characteristics of the reflected light detection means 22. The reflected light detection means 22 has a different detection level P depending on the intensity of the reflected light. Accordingly, the detection level P varies depending on the reflection surface and also on the distance from the positioning projector 15 to the reflection surface. When reflected from the nail 6c, the characteristic shown by the curve C1 is obtained. When the finger 6 is in contact with the lower surface 3, the detection level P is P1b. When the finger 6 is in contact with the upper surface 2, the detection level P is P1t. When the detection level P is Pmax, the claw 6c is positioned at the shortest distance that can be allowed from the positioning projector 15, that is, at the highest allowable level Lmin. On the contrary, when the detection level P is Pmin, it is located at the maximum allowable distance, that is, the minimum allowable Lmax. The detection level allowable range Pw is between the detection levels Pmin and Pmax. Between the corresponding vertical positions Lmin and Lmax is the vertical position allowable range Lw, and the finger 6 images the fingerprint 6a at a position where the nail 6c is within the vertical position allowable range Lw.

Further, when the light is reflected from the outer skin 6b of the finger 6, the reflectance is lower than that of the nail 6c, so that the characteristic indicated by the curve C2 is obtained. That is, when the finger 6 is in contact with the lower surface 3, the detection level P is P2b, and when it is in contact with the upper surface 2, the detection level P is P2t.
Furthermore, the lower surface 3 of the finger rest part 1 is painted in jet black and hardly reflects light. For this reason, when the positioning projector 15 irradiates the lower surface 3, the detection level P = 0.

FIG. 3 is an explanatory view showing a reflection portion of reflected light when the finger 6 is loosely inserted into the finger placement portion 1. FIG. 4 is an explanatory diagram showing the change in the detection level P of the reflected light detection means 22 due to the loose insertion of the finger 6 in correspondence with FIG.
FIG. 3A shows a state where the finger 6 is not sufficiently inserted and the distance from the front surface 4 of the finger placement unit 1, that is, the front-rear position D is D1. For this reason, the positioning light projector 15 irradiates the lower surface 3 of the finger placement part 1, and the reflected light is extremely low, and the detection level P is P1 as shown in FIG.

FIG. 3B shows a state in which the loose insertion of the finger 6 proceeds, the front-rear position D becomes D2, and the positioning light projector 15 irradiates the nail 6c. The reflected light from the claw 6c is received by the positioning light receiver 16. At the front-rear position D2, as shown in FIG. 4, the detection level P of the reflected light detection means 22 is P3, which is within the detection level allowable range Pw.
Here, when the finger 6 finely moves downward and the detection level P reaches P4, the “upper” of the display unit 17 in FIG. 1 is lit to guide the finger 6 to be raised. On the contrary, when the finger 6 is finely moved upward and the detection level P becomes P5, the “lower” of the display 17 in FIG. To be located.

FIG. 3C shows a state where the loose insertion of the finger 6 further proceeds, the front-rear position D becomes D3, and the positioning projector 15 irradiates the outer skin 6b. Since the outer skin 6b has a lower reflectance than the claw 6c, the detection level P of the reflected light detection means 22 is P2.
Here, the reflectance is different between the lower surface 3 of the finger placement unit 1, the outer skin 6b of the finger 6, and the claw 6c. Therefore, in FIG. 4, when the detection level P is higher than the nail reflection area discrimination level PH, it can be detected as reflection from the nail 6c.
Further, when the detection level P is between the nail reflection area discrimination level PH and the skin reflection area discrimination level PL, it can be detected as reflection from the skin 6b.
Furthermore, when the detection level P is lower than the skin reflection area discrimination level PL, it can be detected as reflection from the lower surface 3.

FIG. 5 is a flowchart showing the operation of the fingerprint image capturing apparatus. In step S11, the timer value t = 0 is initialized. The timer value t is for setting a time for capturing a fingerprint image. In step S12, the detection level P is examined from the reflected light of the light irradiated by the positioning projector 15.
If (detection level P <outer skin reflection area discrimination level PL), the process proceeds to step S14 to guide the finger 6 to move forward by turning on the forward light “front” of the display unit 17 and to perform step S11 again. Begin.
If the skin reflection area discrimination level PL <the detection level P <the nail reflection area discrimination level PH, the process proceeds to step S15 to turn on the backward light “after” of the display unit 17 and guide the finger 6 to move backward. At the same time, the procedure S11 starts again.
If (detection level P> claw reflection area discrimination level PH), the process proceeds to step S13, the vertical position of the claw 6c is calculated, and the process proceeds to step S16.

In step S16, if the calculated vertical position L of the claw 6c is lower than the allowable lowest Lmax, the process proceeds to step S17, and the rising lamp “up” on the display unit 17 is turned on to raise the finger 6. Then, step S11 starts operating again. If the vertical position L of the claw 6c is higher than the allowable lowest Lmax, the process proceeds to step S18.
In step S18, if the calculated vertical position L of the nail 6c is higher than the allowable uppermost Lmin, the process proceeds to step S19, and the lowering lamp “down” of the display unit 17 is turned on so that the finger 6 is lowered. Then, step S11 starts operating again. If the vertical position L of the claw 6c is lower than the allowable uppermost Lmax, the process proceeds to step S20. That is, the finger 6 is in the upper and lower position allowable range Lw, and the OK lamp of the display unit 17 is turned on to display that effect.

In step S21, the light source 11 is turned on, and in step S22, the image of the fingerprint 6c is projected on the CCD 14 and captured by the transmitted light 11a. In step S23, the timer value t is read. In step S24, it is checked whether the timer value t has exceeded a predetermined time required for imaging as a time required for imaging the fingerprint 6c. If not exceeded, the process returns to step S12, and the processes in and after step S12 are performed to perform imaging while monitoring the position of the finger 6.
In step S24, when the timer value t exceeds the time required for imaging, the process proceeds to step S25, the light source 11 is turned off, and the imaging process is completed.

  According to the fingerprint image capturing apparatus of the first embodiment, light is emitted from the positioning light projector 15 toward the finger placement unit 1 from the anti-fingerprint side of the finger 6 and the reflected light is reflected from the nail 6c. By detecting, the optical axis direction of the finger 6, that is, the vertical position in the finger placement unit 1 is regulated, so that the position in the optical axis direction as well as the depth direction of the finger 6 orthogonal to the optical axis is determined. And the position in the left-right direction is naturally restricted by the dimension range of the claw 6c. That is, the position of the finger 6 in the three-dimensional space of the finger placement unit 1 can be specified by detecting the reflected light from the nail 6 c of the finger 6. For this reason, since the finger 6 can be placed in a predetermined range that is set in advance as a range where the finger 6 does not touch the finger placement unit 1, the fingerprint 6 c is imaged without the finger 6 touching the finger placement unit 1. can do.

In the first embodiment, the light source 11 is provided on the anti-fingerprint side. However, the light source 11 may be installed on the fingerprint side so that reflected light is projected on the CCD 14 and imaged.
Further, as in the first embodiment, when the light source 11 is provided on the anti-fingerprint side and the light transmitted through the finger 6 is received on the fingerprint side and the fingerprint 6a of the finger 6 is photographed, the positioning light receiver 16 is The positioning light projector 15 can also be used as the light source 11 by receiving the reflected light irradiated by the light source 11 and reflected by the claw 6c. With this combination, the apparatus can be simplified.
Furthermore, since the position of the finger 6 in the left-right direction can be easily determined by visual observation, not depending on the width dimension of the nail 6c, it can be left to the user.
Furthermore, although it becomes unstable because the finger 6 floats in the space, the time required for imaging in step S24 can be shortened by adopting a fast imaging operation, thereby solving the problem related to the instability. be able to.

1 is a block diagram showing an overall configuration of a fingerprint image imaging device according to Embodiment 1 of the present invention. Explanatory drawing which shows the operating characteristic of the reflected light detection means 22 of the fingerprint image imaging device in Embodiment 1 of this invention. 7 is an explanatory view showing a reflection part of reflected light when a finger 6 is loosely inserted into the finger placement part 1 of the fingerprint image capturing apparatus according to Embodiment 1 of the present invention. Explanatory drawing which shows the change of the detection level P of the reflected light detection means 22 accompanying the loose insertion of the finger | toe 6 of the fingerprint image imaging device in Embodiment 1 of this invention. The flowchart which shows operation | movement of the fingerprint image imaging device in Embodiment 1 of this invention. The block diagram which shows the whole structure of the conventional fingerprint image imaging device.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Finger placement part, 2 Upper surface, 2a Upper opening, 3 Lower surface, 3a Lower opening, 4 Front, 5 Side, 6 Finger, 6a Fingerprint, 6b Outer skin, 6c Nail, 11 Light source, 11a Transmitted light, 12 lens, 13 lens, 14 CCD, 15 Light projector for positioning, 16 Light receiver for positioning, 17 Display, 18 Case, 21 Light projector lighting means, 22 Reflected light detection means, 23 Claw position calculation means, 24 Claw position deviation calculation means, 25 Light source lighting means, 26 finger image capturing means, 27 light source extinguishing means.

Claims (2)

In a fingerprint image capturing apparatus that allows a finger to be freely inserted into a finger placement unit and captures a fingerprint with an imaging means,
A projector for positioning that emits light from the anti-fingerprint side of the finger toward the finger rest;
A positioning receiver that receives reflected light of the light emitted from the positioning projector;
Reflected light detecting means for detecting a reflection part of the reflected light received by the positioning light receiver;
Nail position calculating means for detecting the position of the nail in the optical axis direction based on the reflected light from the nail detected by the reflected light detecting means;
The imaging means is operated when the position of the nail detected by the nail position calculating means is within a predetermined range set in advance as a range where the finger does not touch the finger rest. Claw position deviation calculating means ,
The reflected light detection means detects that the reflected light is reflected from the nail when the detection level of the reflected light is higher than a predetermined nail reflection area determination level, and the nail reflection area determination level When the reflected light is reflected from the outer skin of the finger when it is between a predetermined skin reflection area determination level lower than the nail reflection area determination level, and when it is lower than the skin reflection area determination level Detecting that the reflected light is reflected from the lower surface of the finger rest,
The nail position calculating means uses the detection level of the reflected light in the optical axis direction of the nail when the reflected light detecting means detects that the reflected light is reflected from the nail. Detect the position,
The claw position deviation calculating means is located below an allowable uppermost position, which is the shortest distance allowable from the positioning projector, based on the detection level of the reflected light by the claw position calculating means. And when it is detected that it is located above an allowable lowest level that is the longest allowable distance from the positioning projector, that is, within an allowable vertical position range, the nail in the optical axis direction is detected. A fingerprint image capturing apparatus, wherein the position is within the predetermined range . 2. The fingerprint image capturing apparatus according to claim 1, wherein the reflected light detecting means guides the finger to move forward when the reflected light is detected to be reflected from the lower surface, and the reflected light is When it is detected that the reflection from the outer skin is detected, the finger is caused to retract, and when the nail position calculating means detects that the nail is located above the allowable uppermost position. The finger is guided to be lowered, and the finger is raised to be raised when it is detected that the nail is located below the lowest allowable level. Further, the reflected light is detected by the reflected light detecting means. When the reflection from the nail is detected and the nail position calculating means detects that the nail is within the allowable range of the vertical position, the display further displays the fact. Fingerprint image pickup device according to claim.

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