JP2993287B2 - Uneven shape detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for easily and accurately detecting an uneven shape of an object such as a fingerprint with a thin structure.

2. Description of the Related Art Conventionally, fingerprint collation for personal identification has been studied. At that time, the unevenness formed by the fingerprint of a finger pressed against one surface of a parallel transparent light guide is viewed from the outside of the other surface. Light is incident and detected after propagating in the light guide. At this time, since the configuration has become larger, it is desired to develop a thin device easily.

[0003]

2. Description of the Related Art It has been studied to identify an individual by a fingerprint and to make it possible to enter a computer room or use a terminal connected to a computer. This is because fingerprints have the characteristics of being unique to everyone and never changing, so put your finger on the flat plate of the fingerprint sensor, detect the fingerprint as irregularity image data with light illuminated from below, and save it in advance in a data file. Check with stored data.

FIGS. 4 and 5 are schematic diagrams of a concavo-convex shape detecting section in a conventional fingerprint sensor. In FIG. 4, reference numeral 1 denotes, for example, a finger on a fingerprint sensor as an object for detecting an uneven shape. 2 is a right angle prism, 3 is a light source of illumination light, and 4 is an imaging system.

[0005] A finger 1 is placed on the slope (upper surface in the figure) of the right-angle prism 2.
To illuminate from the light source 3 provided on the side. When there is unevenness like the fingerprint of the finger 1, the concave portion 5 is called a valley of a fingerprint in the air layer, and the convex portion 6 is called a ridge of the fingerprint. Are totally reflected and go straight to the other side different from the light source of the prism 2, and the illuminating light is scattered to four sides in the prism 2 at the ridge of the fingerprint indicated by the convex portion 6.

Accordingly, the light reflected from the concave portion 5 jumps out of the prism 2 and is strongly incident on the imaging system 4, and the light reflected on the convex portion 6 is weakly incident on the imaging system 4. In the imaging system 4, a fingerprint image with contrast is obtained by using a lens converging unit (not shown) and the intensity of light corresponding to the valleys and ridges of the fingerprint of the finger 1.

FIG. 5 shows an apparatus for obtaining an image having a higher contrast than the apparatus shown in FIG.
_-1 and 7 _-2 are opposing surfaces of the light guide 7 which are parallel to each other, and use transparent glass or plastic as a material;
Reference numeral 8 denotes a diffraction grating having a lens function.

[0008] one surface 7 _-2 light guide body 7 is pressed against the finger 1 to be incident almost vertically illuminating light from the other surface 7 _-1. Then, there is an air layer in the recess 5 of the finger 1 and a part of the illumination light enters the recess 5 and is reflected at a predetermined place,
Scatters in all directions. The most reenters vertically straight through the light guide body 7 on the surface 7 _-2 emitted from the other surface 7 _-1 (R _1), disappears in the distance.

On the other hand, the light hitting the convex portion 6 is
Are scattered into the light guide 7 so as to be used as a new light source, and a part of the light is emitted from the light guide 7 as shown by R ₂ , and the other is totally reflected while the light guide 7 is shown as R _3. Propagating inside.

The light component indicated by R ₃ is imaged by the diffraction grating 8, and a fingerprint image is obtained by an image pickup system 4 provided outside the light guide 7, for example, a CCD. FIG. 6 is a schematic diagram of an uneven shape detection unit in a thinned conventional fingerprint sensor.

Referring to FIG. 6 (JP-A-1-321576)
Reference 9), 9 is a light guide, 9_-1And 9 _-2Are the light guides 9
10 is an inclined surface 9 of the light guide 9_-3Established in
Curved surface (lens) for focusing light beam, 11 is emitted from curved surface 10
This is a reflecting mirror that reflects light toward the imaging system 4.

[0012] applied to one surface 9 _-2 lightguide 9 press the finger 1, is incident almost vertically illumination light from the outside of the other surface 9 _-1. Then, there is an air layer in the recess 5 of the finger 1, and a part of the illumination light enters the recess 5, is reflected at a predetermined place, and is scattered in all directions. The most straight through the light guide 9 and then re-enters the surface 9 _-2 vertically disappear far emitted from the other surface 9 _-1.

On the other hand, the light hitting the convex portion 6
Is scattered into the light guide 9 so as to be a new light source, a part of the light is emitted from the light guide 7, and the other propagates inside the light guide 9 as indicated by R 3 while being totally reflected, and the curved surface Scatter out of 10

Therefore, the reflecting mirror 11 provided outside the light guide 9
The fingerprint image of the finger 1 can be obtained by using the imaging system 4 such as a CCD. FIG. 7 shows an application example of the uneven shape detection unit shown in FIG.

In FIG. 7 (see JP-A-1-321576), 13 is a light guide, 14 is a door in which the light guide 13 is embedded and mounted, 15 is a knob of the door 14, and the light guide 13 is The light guide 13 is bent in the shape of a letter, and one end of the light guide 13 is opposed to the imaging system 4, for example, a CCD.

In the unevenness detecting section, the light guide 13
Corresponds to the light guide 9, and the contact surface of the light guide 13 with the finger 1 is the door 14
Is exposed in the V-shaped recess 16 of FIG.

[0017]

As described above, the conventional concavo-convex shape detecting section is provided in a direction in which the imaging system 4 is deviated from the light guide, or the imaging light is repeatedly reflected in the light guide. This is the configuration to propagate.

If the image pickup system 4 is separated from the light guide (triangular prism), the thickness of the apparatus is increased and it is difficult to reduce the thickness of the apparatus. When strictly controlled, thin doors cannot be completely embedded.

In a configuration in which the imaging light is repeatedly reflected and propagated in the light guide, there is a disadvantage that the propagation loss of the imaging light is large and clear imaging is hindered. In addition, the concave and convex shape detecting section of the thinned conventional fingerprint sensor can be accommodated in a thinner one such as a door, for example, but the thickness of the accommodating section such as the door cannot be reduced to 20 mm or less.

[0020]

FIG. 1 is a diagram showing the basic configuration of an unevenness detecting unit in the apparatus according to the present invention. In FIG.
Light guide 21 made of transparent glass or plastic
Includes a flat 21 _-2 brought into contact with the object for example a finger 1 having unevenness to be detected, the plane 21 _-1 to incorporate illumination light R emitted from the light source intersects at an appropriate angle to the plane 21 _-2, the illumination light R is a reflecting surface 21 _-3 where the reflected light R ₃ brought reflects the reflected light R ₃ to be substantially parallel to the plane 21 _-2 when irradiating the finger 1, protrudes reflecting surface from the end face 21 _-4 21 reflected light R ₃ from _-3 comprises a lens 21 _-5 for condensing light guide 21
Outside of the reflecting mirror 11 allowed to reflected in a direction substantially perpendicular to the emitted light to the plane 21 _-1 from the lens 21 _-5, reflected light of the reflector 11 is comprises an imaging system 4 incident.

[0021]

According to the above means, the imaging light is extracted from the light guide within the light guide only by one reflection, and the light source of the illumination light is disposed obliquely below the light guide. .

Accordingly, the propagation loss of the imaging light in the light guide is as small as that of the conventional one using the right-angle prism, and the thickness for accommodating the unevenness detecting unit is the same as that of the conventional one using the right-angle prism. , And can be thinner than conventional ones using a light guide that repeatedly reflects.

[0023]

FIG. 2 is a perspective view of an apparatus according to an embodiment of the present invention.
It is a block diagram of a detection part. In FIG. 2, 22 is a transparent glass.
Is a light guide made of metal or plastic, and the light guide 22 is
An object having irregularities to be detected, for example, a finger 1 is brought into contact with the object.
Plane 22_-2And plane 22_-2Intersect at an appropriate angle to
Plane 22 for taking in the illumination light R emitted from _-1And the illumination light R
Irradiates finger 1 with reflected light R_ThreeIs reflected
Glow R_ThreeIs the plane 22_-2To be almost parallel to
Launch surface 22_-3And end face 22_-FourMore protruding reflective surface 22_-3Reflection from
Light R_ThreeCondensing lens 22_-FiveWith

Plane 22_-1And 22_-3Should be on the same side as
Because the plane 22_-2Plane 22 facing _-6The angle α to
For example, at 20 degrees, outside such a light guide 22, there is a lens
twenty two_-FiveOutgoing light from plane 22_-1Reflects almost perpendicular to
The reflecting mirror 11 and the imaging that the reflected light of the reflecting mirror 11 enters
System 4 is provided.

[0025] Accordingly, pressing a finger 1 to a predetermined portion of the plane _22-2 of the light guide body 22, the illumination light R from the outside of the plane 22 _-1, the finger 1
Is irradiated on the contact surface between the plate and the plane _22-2 . Then, the reflected light R ₃ corresponding to the finger 1 irregularities (fingerprint) is reflected to the plane 22 _-3, reflected by the reflecting mirror 11 after emitted from the lens 22 _-5, the ones of the imaging system 4 for example, a CCD using You will be imaged.

FIG. 3 is a diagram showing an application example of a device for detecting a fingerprint image according to the present invention. In an information processing system,
When applying the fingerprint collation system for the purpose of limiting the persons who can access the database and the like, without specially providing a fingerprint input device, for example, if it can be embedded in the keyboard 25, it does not impair the appearance and is easy to use. System. FIG. 8 shows an example in which the terminal device is embedded in a keyboard 25, and reference numeral 26 denotes a terminal device.

[0027]

As described above, according to the present invention, the imaging light in the light guide is extracted from the light guide by only one reflection, so that the propagation loss of the imaging light is reduced and clear imaging is achieved. And a thin object of about 20 mm such as a door can be accommodated.

[Brief description of the drawings]

FIG. 1 is a basic configuration diagram of an uneven shape detection unit in a device of the present invention.

FIG. 2 is a configuration diagram of an uneven shape detection unit of the apparatus according to the embodiment of the present invention.

FIG. 3 is a diagram showing an application example of a device for detecting a fingerprint image according to the present invention.

FIG. 4 is a schematic diagram (part 1) of a concavo-convex shape detection unit of a conventional fingerprint sensor.

FIG. 5 is a schematic diagram (part 2) of a concavo-convex shape detection unit of a conventional fingerprint sensor.

FIG. 6 is a schematic view of a concavo-convex shape detection unit in a conventional thin fingerprint sensor.

FIG. 7 is an application example of the uneven shape detection unit shown in FIG. 6;

[Explanation of symbols]

1 reflector 21 object (finger) 4 imaging system 11 having an irregular to be detected light guide 21 _-2, 22 _-2 light guide of uneven object abutment plane 21 _-1, 22 _{- 1} is the illumination light intake surface of the light guide 21 _-3 , 22 _-3 is the reflection surface of the light guide 21 _-5 , 22 _-5 is the light condensing lens of the light guide R is the illumination light R ₃ irradiating the uneven object Is the reflected light from the uneven object (imaging light)

──────────────────────────────────────────────────続 き Continuation of the front page (72) The inventor Eietsu Takahashi 1015 Uedanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Prefecture Inside Fujitsu Limited (56) References JP-A-63-165982 (JP, A) JP-A-2-176984 (JP, A) JP-A-2-307176 (JP, A) JP-A-3-256185 (JP, A) JP-A-63-107063 (JP, U) (58) Fields investigated (Int. Cl. ⁶⁾ , DB name) G06T 1/00

Claims (1)

(57) [Claims] An object (1) having irregularities to be detected is brought into contact with the object (1).
Plane (21_-2, twenty two _-2) And the plane (21_-2, twenty two_-2) For
Illumination light intake surface that crosses at an appropriate angle (21 _-1, twenty two_-1)
And the illumination light intake surface (21_-1, twenty two_-1) Light incident from
Light (R) irradiates the object (1) with reflected light (R_Three) For the object contact
Plane (21_-2, twenty two_-2) To reflect in a direction almost parallel to
Reflective surface (21_-3, twenty two_-3) And the reflecting surface (21_-3, twenty two_-3) Reflection
Reflected light (R_Three) Condenser lens (21_-Five, twenty two_-Five) And
A light guide (21, 22) and the lens (21_-Five, twenty two_-Five)
Light is applied to the object contact plane (21_-2, twenty two_-2) Almost perpendicular to
A reflecting mirror (11) that reflects the light (R)_Three)But
Irregular shape characterized by having an incident imaging system (4)
Condition detection device.