JPH0683944A - Uneven shape detecting device - Google Patents

Abstract

PURPOSE:To make an uneven shape detection part thin and improve light efficiency as to the uneven shape detecting device for a body such as a fingerprint. CONSTITUTION:This detecting device is equipped with a photoconductor 21 having a plane 21-2 abutting on the body 1 having unevenness to be detected, an illumination light incidence surface 21-1 which crosses the plane 21-2 at a proper angle, a reflecting surface 21-3 which reflects reflected light R3 generated when illumination light R made incident from the illumination light incidence surface 21-1 irradiates the body 1 almost in parallel to the body abutting plane 21-2, and a condenser lens 21-5 for reflected light R3 reflected by the reflecting surface 21-3, a reflecting mirror 11 which reflects projection light from the lens 21-5 almost at right angles to the body abutting plate 21-2, and an image pickup system 4 on which the reflected light R3 from the reflecting mirror 11 is made incident.

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.

[0002] Conventionally, research has been conducted on fingerprint matching for personal identification, and at that time, the uneven shape formed by the fingerprint of the finger pressed against one surface of the parallel transparent light guide member from the outside of the other surface. Light is made incident and is detected after propagating in the light guide. At this time, since the configuration is enlarged, it is desired to easily develop a thin device.

[0003]

2. Description of the Related Art Research has been conducted to identify an individual with a fingerprint so that a person can enter a computer room or use a terminal connected to the computer. This is because fingerprints have the characteristics that they are the same for all people and do not change for life.Therefore, place your finger on the flat plate of the fingerprint sensor, and the light emitted from below detects it as uneven image data of the fingerprint, and saves it in advance as a data file. Match with the stored data.

FIG. 4 and FIG. 5 are schematic views of a concave-convex shape detecting portion 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.

A finger 1 is placed on the inclined surface of the right-angled prism 2 (top surface in the figure).
And is illuminated by the light source 3 provided on the side. When there is unevenness like the fingerprint of the finger 1, the concave portion 5 is an air layer and is called a valley line of the fingerprint, and the convex portion 6 is called a ridge line of the fingerprint. Is totally reflected and goes straight to the other side different from the light source of the prism 2, and at the ridge line of the fingerprint shown by the convex portion 6, the illumination light is scattered in all directions in the prism 2.

Therefore, the light reflected from the concave portion 5 emerges from the prism 2 and strongly enters the imaging system 4, and the light reflected by the convex portion 6 weakly enters the imaging system 4. In the image pickup system 4, a lens focusing unit (not shown) is used, and a fingerprint image with contrast is obtained by the intensity of light corresponding to the valley line and the ridge line of the fingerprint of the finger 1.

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

The finger 1 is pressed against one surface 7 _-2 of the light guide 7, and the illumination light is made to _enter from the other surface 7 _-1 in a substantially vertical direction. 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,
Scatter in all directions. Most of the light then re-enters the surface 7 _-2 in the vertical direction, travels straight in the light guide 7, exits from the other surface 7 _-1 (R ₁ ), and disappears in the distance.

On the other hand, the light striking the convex portion 6 is actually the convex portion 6
As a new light source, the light is scattered in the light guide body 7, and a part of the light is emitted from the light guide body 7 as indicated by R ₂ , and the other part is totally reflected as shown by R ₃ Propagates inside.

The light component indicated by R ₃ is imaged by the diffraction grating 8 and a fingerprint image is obtained by the image pickup system 4 provided outside the light guide 7 such as one using a CCD. FIG. 6 is a schematic view of a concave-convex shape detecting portion in a thinned conventional fingerprint sensor.

In FIG. 6 (Japanese Patent Laid-Open No. 1-321576)
), 9 is a light guide, 9_-1And 9 _-2Means that the light guides 9 are
Opposite surfaces parallel to each other, 10 is the inclined surface 9 of the light guide 9._-3Set up in
Curved surface (lens) for focusing light beam, 11 exits from curved surface 10
It is a reflecting mirror that reflects light toward the imaging system 4.

The finger 1 is pressed against one surface 9 _-2 of the light guide 9 so that the illumination light is incident in the substantially vertical direction 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. Most of the light then re-enters the surface 9 _-2 in the vertical direction, travels straight in the light guide 9, exits from the other surface 9 _-1, and disappears in the distance.

On the other hand, the light striking the convex portion 6 is the same as the convex portion 6.
As a new light source, the light is scattered inside the light guide body 9, a part of the light is emitted from the light guide body 7, and the other part is totally reflected and propagates inside the light guide body 9 as indicated by R3. Scatter out of 10.

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

In FIG. 7 (see Japanese Laid-Open Patent Publication No. 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 into a dogleg shape, and one end of the light guide 13 is opposed to the image pickup system 4 such as one using a CCD.

In the concave / convex shape detecting section, the light guide 13
Corresponds to the light guide 9, and the contact surface of the finger 1 of the light guide 13 is the door 14
It is exposed in the V-shaped recess 16 of.

[0017]

As described above, the conventional concave-convex shape detecting section is provided with the imaging system 4 in a direction away from the light guide body, or the imaging light is repeatedly reflected inside the light guide body. It is configured to propagate.

When the image pickup system 4 is separated from the light guide (triangular prism), the thickness of the device is increased and it is difficult to make the device thin. Therefore, like a fingerprint collation system, the device is attached to the door to enter the computer room. When tightly controlled, it cannot be completely embedded in thin doors.

In the structure in which the imaging light is repeatedly reflected and propagates in the light guide, there is a disadvantage that the propagation loss of the imaging light is large and a clear imaging is hindered. It should be noted that the thinned conventional fingerprint sensor concave-convex shape detection unit can be accommodated in a thinner one, for example, in a door, but the thickness of the accommodation portion such as the door cannot be 20 mm or less.

[0020]

FIG. 1 is a basic configuration diagram of a concave-convex shape detecting section in an apparatus of 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 A reflecting surface 21 _-3 that reflects the reflected light R ₃ when R irradiates the finger 1 so that the reflected light R ₃ is substantially parallel to the plane 21 _-2, and a reflecting surface that projects from the end surface 21 _-4. 21 reflected light R ₃ from _-3 comprises a lens 21 _-5 for condensing light guide 21
In addition to the above, a reflection mirror 11 for reflecting the light emitted from the lens 21 _{-5 in a} direction substantially perpendicular to the plane 21 _-1, and an image pickup system 4 on which the light reflected by the reflection mirror 11 is incident.

[0021]

According to the above means, the imaging light is extracted from the light guide body only once in the light guide body, and the light source of the illumination light is arranged obliquely downward with respect to the light guide body. .

Therefore, the propagation loss of the image pickup light in the light guide body is as small as that of the conventional one using the right-angle prism, and the thickness for accommodating the concave-convex shape detecting portion is the same as that of the conventional one using the right-angle prism. It can be made thinner than the conventional one that uses a light guide that repeatedly reflects light.

[0023]

EXAMPLE FIG. 2 shows the concavo-convex shape of an apparatus according to an example of the present invention
It is a block diagram of a detection part. In FIG. 2, 22 is a transparent glass.
It is a light guide made of plastic or plastic, and the light guide 22 is
Touch an object having irregularities to be detected, for example, the finger 1.
Plane 22_-2And plane 22_-2To the light source
Plane 22 for taking in the illumination light R emitted from _-1And the illumination light R
Reflected light R when the finger 1 illuminates₃The anti-reflection
Light R₃Is plane 22_-2Anti-parallel to
Surface 22_-3And the end face 22_-FourMore protruding reflective surface 22_-3Reflection from
Light R₃Lens 22 for condensing_-FiveAnd

Plane 22_-1And 22_-3And should be on the same plane
For plane 22_-2Plane 22 facing _-6The angle α to
For example, at 20 degrees, outside such a light guide 22, a lens
twenty two_-FiveLight emitted from the plane 22_-1Reflected almost at a right angle to
An image of the reflecting mirror 11 and the reflected light of the reflecting mirror 11 are incident.
And system 4.

Therefore, the finger 1 is pressed against a predetermined portion of the flat surface 22 _-2 of the light guide 22, and the illumination light R from the outside of the flat surface 22 _-1 is applied to the finger 1.
The contact surface between the surface and the plane 22 _-2 is irradiated. Then, the reflected light R ₃ corresponding to the unevenness (fingerprint) of the finger 1 is reflected on the flat surface 22 _-3 , emitted from the lens 22 _-5 , and then reflected by the reflecting mirror 11, and is reflected by the imaging system 4 such as one using a CCD. Being imaged.

FIG. 3 is a diagram showing an application example of an apparatus for detecting a fingerprint image according to the present invention. In the information processing system,
When applying the fingerprint collation system for the purpose of limiting the number of persons who can access the database, if the fingerprint input device is not specially provided and can be embedded in the keyboard 25, for example, it does not spoil the appearance and is easy to use. Become a system. FIG. 8 shows an example in which the keyboard 25 is embedded, and 26 is a terminal device.

[0027]

As described above, according to the present invention, the image pickup light is extracted from the light guide body only once in the light guide body, so that the propagation loss of the image pickup light is reduced and clear image pickup is performed. It is also possible to accommodate a thin object of about 20 mm, for example, a door.

[Brief description of drawings]

FIG. 1 is a basic configuration diagram of a concave-convex shape detection unit in a device of the present invention.

FIG. 2 is a configuration diagram of a concave-convex shape detection unit of the device according to the embodiment of the present invention.

FIG. 3 is a diagram showing an application example of an apparatus 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 diagram of an uneven shape detecting unit in a conventional thin fingerprint sensor.

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

[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 receiving surface of the light guide 21 _-3 , 22 _-3 is the reflecting surface of the light guide 21 _-5 , 22 _-5 is the condenser lens of the light guide R is the illumination light that irradiates the uneven object R ₃ Is the reflected light from the uneven object (imaging light)

Front page continuation (72) Inventor Eietsu Takahashi 1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture, Fujitsu Limited

Claims (1)

[Claims] 1. An object (1) having unevenness 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) Against
Illumination light intake surface that intersects at an appropriate angle (21 _-1, twenty two_-1)
And the illumination light intake surface (21_-1, twenty two_-1)
Light (R) reflected on the object (1) (R₃) Abutting the object
Plane (21_-2, twenty two_-2) Is reflected in a direction almost parallel to
Reflective surface (21_-3, twenty two_-3) And the reflective surface (21_-3, twenty two_-3) Reflected
Reflected light (R₃) Focusing lens (21_-Five, twenty two_-Five) With
The light guide (21, 22) and the lens (21_-Five, twenty two_-Five)
The light is brought into contact with the object plane (21_-2, twenty two_-2) Almost perpendicular to
(11) and the reflected light (R₃)But
Concavo-convex shape characterized by having an incident imaging system (4)
Detection device.